Author Summary Transposable elements are mobile DNA elements that are a prevalent component of many eukaryotic genomes. While transposable elements can often have deleterious effects through insertions into protein-coding genes they may also contribute to regulatory variation of gene expression. There are a handful of examples in which specific transposon insertions contribute to regulatory variation of nearby genes, particularly in response to environmental stress. We sought to understand the genome-wide influence of transposable elements on gene expression responses to abiotic stress in maize, a plant with many families of transposable elements located in between genes. Our analysis suggests that a small number of maize transposable element families may contribute to the response of nearby genes to abiotic stress by providing stress-responsive enhancer-like functions. The specific insertions of transposable elements are often polymorphic within a species. Our data demonstrate that allelic variation
This chapter provides a general description of the types of genetic variation caused by transposable elements in animals and plants, and examines this variation within an evolutionary framework. It focuses on the variation induced by transposable elements in their host organisms. The host variation associated with transposable elements can result from several interconnected aspects of transposable element activity. Estimates of the frequencies of new transposable element-induced mutations have been made under laboratory conditions and varied over an enormous range. The partial or complete sterility associated with several systems of hybrid dysgenesis in Drosophila provides an interesting aspect of variation associated with transposable element activity. Heterochromatin proteins can recognize and silence transposable elements, some of which target heterochromatin for insertion. Thus, the evolution of heterochromatin could have led to a self-perpetuating expansion of domains rich in transposable elements.
Transposable elements are endogenous DNA sequences able to integrate into and multiply within genomes. They constitute a major source of genetic innovations, as they can not only rearrange genomes but also spread ready-to-use regulatory sequences able to modify host gene expression, and even can give birth to new host genes. As their evolutionary success depends on their vertical transmission, transposable elements are intrinsically linked to reproduction. In organisms with sexual reproduction, this implies that transposable elements have to manifest their transpositional activity in germ cells or their progenitors. The control of sexual development and function can be very versatile, and several studies have demonstrated the implication of transposable elements in the evolution of sex. In this review, we report the functional and evolutionary relationships between transposable elements and sexual reproduction in animals. In particular, we highlight how transposable elements can influence expression of
The beta-glucuronidase reporter gene has been used to develop a sensitive assay for the excision of transposable elements introduced into transgenic plants. The reporter gene, inactivated by the insertion of the maize transposable element Activator (Ac) into the 5-untranslated leader, was introduced into the genome of tobacco by Agrobacterium-mediated transformation. Reactivation of the beta-glucuronidase gene was detected in transgenic plants using a fluorometric or histochemical assay. Reactivation of the reporter gene was dependent on the presence of the transposase of Ac, and resulted from the excision of the Ac element. This assay, together with the improved methods for visualization, will provide a valuable and rapid method for studying the basic mechanism of transposition in plants and for developing modified transposable element systems suitable for gene tagging in transgenic plants.. ...
TY - THES. T1 - An En/Spm based transposable element system for gene isolation in Arabidopsis thaliana. AU - Aarts, M.G.M.. N1 - WU thesis 2194 90-5485-622-X Proefschrift Wageningen. PY - 1996. Y1 - 1996. N2 - At the start of the research described in this thesis, the main aim was to develop, study and apply an efficient En/Spm-I/dSpm based transposon tagging system in Arabidopsis thaliana to generate tagged mutants and to provide insights in the possibilities for future applications of such a transposon tagging system in studying plant gene functions. The first step was the introduction of an active En/Spm-I/dSpm system into Arabidopsis. Initially a very simple T-DNA construct was transformed, containing a nearly full En-1 element, without left and right border sequences, and with its promoter replaced by the stronger CaMV 35S promoter. As the same construct harboured a non-autonomous I/dSpm element, only one T-DNA transformation was needed. Transformation of this in cis two- element ...
Transposable elements are mobile genetic elements that are prevalent in plant genomes and are silenced by epigenetic modification. Different epigenetic modification pathways play distinct roles in the control of transposable element transcription, replication and recombination. The Arabidopsis genome contains families of all of the major transposable element classes, which are differentially enriched in particular genomic regions. Whole genome sequencing and DNA methylation profiling of hundreds of natural Arabidopsis accessions has revealed that transposable elements exhibit significant intraspecific genetic and epigenetic variation, and that genetic variation often underlies epigenetic variation. Together, epigenetic modification and the forces of selection define the scope within which transposable elements can contribute to, and control, genome evolution.. ...
Transposons are mobile DNA segments that can disrupt gene function by inserting in or near genes. Here, we show that insertional mutagenesis by the PiggyBac transposon can be used for cancer gene discovery in mice. PiggyBac transposition in genetically engineered transposon-transposase mice induced cancers whose type (hematopoietic versus solid) and latency were dependent on the regulatory elements introduced into transposons. Analysis of 63 hematopoietic tumors revealed that PiggyBac is capable of genome-wide mutagenesis. The Piggybac screen uncovered many cancer genes not identified in previous retroviral or Sleeping Beauty transposon screens, including Spic, which encodes a PU.1-related transcription factor, and Hdac7, a histone deacetylase gene. PiggyBac and Sleeping Beauty have different integration preferences. To maximize the utility of the tool, we engineered 20 mouse lines to be compatible with both transposases in constitutive, tissue-, or temporal-specific mutagenesis. Mice with ...
A chimeric white gene (wpch) and other constructs containing the transposable element mariner from Drosophila mauritiana were introduced into the germline of Drosophila melanogaster using transformation mediated by the P element. In the absence of other mariner elements, the wpch allele is genetically stable in both germ cells and somatic cells, indicating that the peach element (i.e., the particular copy of mariner inserted in the wpch allele) is inactive. However, in the presence of the active element Mos1, the wpch allele reverts, owing to excision of the peach element, yielding eye-color mosaics and a high rate of germline reversion. In strains containing Mos1 virtually every fly is an eye-color mosaic, and the rate of wpch germline reversion ranges from 10 to 25%, depending on temperature. The overall rates of mariner excision and transposition are approximately sixfold greater than the rates in comparable strains of Drosophila simulans. The activity of the Mos1 element is markedly affected ...
TY - JOUR. T1 - Regulation of Tcl transposable elements in Caenorhabditis elegans.. AU - Emmons, S. W.. AU - Ruan, K. S.. AU - Levitt, A.. AU - Yesner, L.. PY - 1985. Y1 - 1985. N2 - C. elegans strains contain variable numbers of a 1.6-kb transposable genetic element. Activity of this element, which is denoted Tcl, shows regulation at at least two levels. At one level, excision of Tcl elements occurs in somatic cells at a frequency several orders of magnitude higher than in germ cells. Evidence is presented suggesting that this results from regulation at the level of trans-acting functions that are required for excision or that repress excision. At the second level, germ line transposition of Tcl occurs at greater frequency in some strains than in others. The hypothesis is proposed that this is because Tcl is one component of a two-element system, the second element of which differs between strains. Evidence for a second putative transposable element family in C. elegans is presented. This ...
Transposon insertion site profiling chip (TIP-chip) was invented by Researchers at the Johns Hopkins High Throughput Biology Center. Tip-chip can be used to help identify otherwise elusive disease-causing mutations in the 97 percent of the genome long believed to be
With regard to the origin of the human species, when the chimp genome was sequenced, it was found to contain nearly all of the transposable elements that the human genome had. The transposable elements were arranged in the same places on chromosomes that were >95% identical in their sequences. I summarized these findings in a paper for OPBSG in 2006. The presence of many transposable elements in the human genome implied that they originated by transposition, and the presence of the same transposable elements in the chimp genome implied that humans and chimps shared a common ancestor. Why? Because of the staggering similarity ...
This chapter discusses the different classes of mobile elements seen in some of the best-characterized animal genome and plant genome. It talks about the some of the general concepts behind the colonization of genomes by mobile elements. There are basically three classes of autonomous mobile elements, all three of which can be found to various extents in different genomes of all animals and plants. These are the DNA transposons, the long terminal repeat (LTR) retrotransposons, and the non-LTR retrotransposons. DNA transposons are very common in the Caenorhabditis elegans genome, as well as several relatively high-copy-number families of their nonautonomous relatives, miniature inverted-repeat transposable elements (MITEs). Other site-specific mobile elements are the HetA and TART elements that make up the telomeres in Drosophila. Only sporadic data are available on mobile elements in reptiles, amphibians, and fish. Almost all the classes of mobile elements are present to some degree in almost all animal
Schöffl, F., Arnold, W., Pühler, A., Altenbuchner, J., & Schmitt, R. (1981). The tetracycline resistance transposons Tn1721 and Tn1771 have three 38-base-pair repeats and generate five-base-pair direct repeats. Mol Gen Genet, 181(1), 87-94. doi:10.1007/ ...
Though transposable elements make up around half of the human genome, the repetitive nature of their sequences makes it difficult to accurately align conventional sequencing reads. However, in light of new advances in sequencing technology, such as increased read length and paired-end libraries, these repetitive regions are now becoming easier to align to. This study investigates the mappability of transposable elements with 50 bp, 76 bp and 100 bp paired-end read libraries. With respect to those read lengths and allowing for 3 mismatches during alignment, over 68, 85, and 88% of all transposable elements in the RepeatMasker database are uniquely mappable, suggesting that accurate locus-specific mapping of older transposable elements is well within reach.
DNA Transposable Elements: Discrete segments of DNA which can excise and reintegrate to another site in the genome. Most are inactive, i.e., have not been found to exist outside the integrated state. DNA transposable elements include bacterial IS (insertion sequence) elements, Tn elements, the maize controlling elements Ac and Ds, Drosophila P, gypsy, and pogo elements, the human Tigger elements and the Tc and mariner elements which are found throughout the animal kingdom.
Transposable elements (TEs) have been highly influential in shaping the structure and evolution of mammalian genomes, as exemplified by TE-derived sequence contributing between 38 and 69% of genomic sequence [1-8]. TE insertions also can influence the transcription, translation or function of genes [1-7]. Functional effects of TE insertions include their regulation of transcription by acting as alternative promoters or as enhancer elements and via the generation of antisense transcripts, or of transcriptional silencers. TEs can alter splice sites or RNA editing, provide alternative poly-adenylation signals or exons, modify chromatin structure or alter translation. Furthermore, TE insertion has been suggested to be a mechanism by which new co-regulatory networks arise [1-7].. TEs are classified on the basis of their transposition mechanism [9]. A class I retrotransposon propagates in the host genome through an intermediate RNA step, requiring a reverse transcriptase to revert it to DNA before ...
Fingerprint Dive into the research topics of Color reversion of the albino medaka fish associated with spontaneous somatic excision of the Tol-1 transposable element from the tyrosinase gene. Together they form a unique fingerprint. ...
The mariner family of transposable elements is one of the most widespread in the Metazoa. It is subdivided into several subfamilies that do not mirror the phylogeny of these species, suggesting an ancient diversification. Previous hybridization and PCR studies allowed a partial survey of mariner diversity in the Metazoa. In this work, we used a comparative genomics approach to access the genus-wide diversity and evolution of mariner transposable elements in twenty Drosophila sequenced genomes. We identified 36 different mariner lineages belonging to six distinct subfamilies, including a subfamily not described previously. Wide variation in lineage abundance and copy number were observed among species and among mariner lineages, suggesting continuous turn-over. Most mariner lineages are inactive and contain a high proportion of damaged copies. We showed that, in addition to substitutions that rapidly inactivate copies, internal deletion is a major mechanism contributing to element decay and the
P element excision generates a DNA double-strand break at the transposon donor site. Genetic studies have demonstrated a strong bias toward repair of P element-induced DNA breaks by homologous recombination with the sister chromatid, suggesting that P element excision occurs after DNA replication, i …
THE Activator/Dissociation (Ac/Ds) transposon family has been extensively characterized since its discovery in maize ,60 years ago (McClintock 1946; Kunze and Weil 2002). Ac/Ds are class II DNA transposons that belong to the hAT superfamily of plant transposable elements (Kunze and Weil 2002). Ac is a 4565-bp autonomous element capable of catalyzing the transposition of itself and nonautonomous Ds elements (McClintock 1949, 1951). Ac encodes a 3.5-kb open reading frame (ORFa) that directs the synthesis of an 807-amino-acid transposase (TPase) essential for both Ac and Ds transposition (Fedoroff et al. 1983; Kunze et al. 1987). The 11 bp imperfect terminal inverted repeats (TIR) and ∼240 bp of subterminal sequences are critical for TPase binding and transposition of both Ac and Ds (Coupland et al. 1988, 1989).. In contrast to the highly conserved structure of Ac elements (Fedoroff et al. 1983; Behrens et al. 1984; Muller-Neumann et al. 1984; Pohlman et al. 1984), Ds elements are structurally ...
Mutator-like transposable elements (MULEs) are widespread across fungi, plants and animals. Most of the research of MULEs has focused on plant where they are discovered and have significant impact on genome structure. Despite being widespread, only a few active MULEs have been identified, meanwhile, the transposition mechanism of the MULEs is previously unknown. Pack-MULEs are able to capture and amplify genes or gene fragments on a large scale, and a subset of plant Pack-MULEs have been shown to be likely playing functional roles in regulating gene expression and providing novel coding capacities. However, the presence of Pack-MULEs in non-plant species has not been reported.. In this study we report that Muta1 identified from the mosquito Aedes aegypti is capable of excision and reinsertion in a yeast transposition assay, element reinsertion generated either 8 bp or 9 bp target site duplications (TSDs) with no apparent sequence preference. Mutagenesis analysis revealed the importance of ...
PiggyBac Transposable Element Derived 5 is an enzyme that in humans is encoded by the PGBD5 gene.[1] PGBD5 is a DNA transposase related to the ancient PiggyBac transposase first identified in the cabbage looper moth, Trichoplusia ni.[2] The gene is believed to have been domesticated over 500 million years ago in the common ancestor of cephalochordates and vertebrates.[3] The putative catalytic triad of the protein composed of three aspartic acid residues is conserved among PGBD5-like genes through evolution,[4], and is distinct from other PiggyBac-like genes.[3] PGBD5 has been shown to be able to transpose DNA in a sequence-specific, cut-and-paste fashion.[4] PGBD5 has also been proposed to mediate site-specific DNA rearrangements in human tumors.[5] ...
The PiggyBac (PB) transposon has emerged as a novel mutagenesis tool for understanding gene function and for phenotypic screening in eukaryotes
misc{7861784, abstract = {DNA transposons are a class of mobile genetic elements that can autonomously move from one genomic location to another. They are powerful drivers of genetic change and have played a significant role in the evolution of many genomes. One such transposable element, IS608 from Helicobacter pylori employs a unique mechanism of transposition as it transposes in a single-stranded DNA form and inserts specifically 3 of a specific tetranucleotide sequence (Kersulyte et al., 2002; Guynet et al., 2008). Previous structural (Ronning et al., 2005; Barabas et al, 2008) and biochemical studies (Ton-Hoang et al., 2005) of IS608, revealed that the element chooses its integration site specifically via base-pairing between the transposon and the target DNA. This unique feature allowed re-directing transposon integration to various four-nucleotide sequences by simply modifying the transposon DNA sequence. A key feature of the retargeting strategy was that, unlike the previous attempts to ...
Described is a mechanism for dependably synchronizing data element activities on web pages among a group of browsers. The web browsers retrieve web pages from an HTTP server. Each of the web pages contains at least one data element and embeds a Master Applet and at least one DTS Applet (DTS stands for data tracking and synchronization). In response the data element activities (such as entering data into a data field) performed at a browser, the DTS Applet passes the activities to the Master Applet, which in turn reports the activities (together with the URL of the web page on which the data element activities have occurred) to a tracking server. The tracking server sends the activity report (together with the URL of the web page on which the data element activities have occurred) to the Master Applets at all participant browsers. The participant Master Applets then instruct their respective DTS Applets to display the data element activities on the web page identified by the URL.
1) a small deletion occurs in the transposase gene of an IS element and plasmid is integrated , 2) a small deletion occurs in the transposase gene of an IS element , 3) two IS elements integrate into a chromosome with only a small distance separating them , 4) an IS element integrates with another IS element with the help of a plasmid
Both classes of transposable elements (DNA and RNA) are tightly regulated at the transcriptional level leading to the inactivation of transposition via epigenetic mechanisms. Due to the high copies number of these elements, the hypothesis has emerged that their regulation can coordinate a regulatory network of genes. Herein, we investigated whether transposition regulation of HsMar1, a human DNA transposon, differs in presence or absence of endogenous HsMar1 copies. In the case where HsMar1 transposition is regulated, the number of repetitive DNA sequences issued by HsMar1 and distributed in the human genome makes HsMar1 a good candidate to regulate neighboring gene expression by epigenetic mechanisms. A recombinant active HsMar1 copy was inserted in HeLa (human) and CHO (hamster) cells and its genomic excision monitored. We show that HsMar1 excision is blocked in HeLa cells, whereas CHO cells are competent to promote HsMar1 excision. We demonstrate that de novo HsMar1 insertions in HeLa cells (human)
Not so conserved after all - Multiple independent losses of the piRNAs in nematodes revealed. A new study carried out by Peter Sarkies (Transgenerational Epigenetic Inheritance & Evolution) in collaboration with Eric Miska (Gurdon Institute, Cambridge) reveals astonishing insights into the evolution of transposon-silencing mechanisms in nematode worms.. Transposons are selfish DNA pieces that insert themselves into the genome. Like a computer virus, they copy themselves and proliferate, which can disrupt essential gene functions.. Because transposons are so disruptive, there is huge selective pressure on organisms to silence them and stop them spreading. Organisms have evolved ingenious ways to suppress transposon activity, especially in the reproductive cells, where a transposition event affects subsequent generations.. The front line of defence against transposons in most animals, from nematode worms to humans, are tiny sequences of RNA, known as Piwi interacting small RNAs (piRNAs). These ...
Sequencing technology and assembly algorithms have matured to the point that high-quality de novo assembly is possible for large, repetitive genomes. Current assemblies traverse transposable elements (TEs) and provide an opportunity for comprehensive annotation of TEs. Numerous methods exist for annotation of each class of TEs, but their relative performances have not been systematically compared. Moreover, a comprehensive pipeline is needed to produce a non-redundant library of TEs for species lacking this resource to generate whole-genome TE annotations. We benchmark existing programs based on a carefully curated library of rice TEs. We evaluate the performance of methods annotating long terminal repeat (LTR) retrotransposons, terminal inverted repeat (TIR) transposons, short TIR transposons known as miniature inverted transposable elements (MITEs), and Helitrons. Performance metrics include sensitivity, specificity, accuracy, precision, FDR, and F1. Using the most robust programs, we create a
During her studies on maize development and chromosomal breakages in maize, McClintock discovered that maize plants which develop patched kernels do not inherit this phenotype in a Mendelian fashion ...
Transposable elements may acquire unrelated gene fragments into their sequences in a process called transduplication. Transduplication of protein-coding genes is common in plants, but is unknown of in animals. Here, we report that the Turmoil-1 transposable element in C. elegans has incorporated two protein-coding sequences into its inverted terminal repeat (ITR) sequences. The ITRs of Turmoil-1 contain a conserved RNA recognition motif (RRM) that originated from the rsp-2 gene and a fragment from the protein-coding region of the cpg-3 gene. We further report that an open reading frame specific to C. elegans may have been created as a result of a Turmoil-1 insertion. Mutations at the 5 splice site of this open reading frame may have reactivated the transduplicated RRM motif. This article was reviewed by Dan Graur and William Martin. For the full reviews, please go to the Reviewers Reports section.
Embryonic stem cells modified to lack DNA methylation allowing transposons to become active. DNA shown in blue. Cells containing active transposons shown in red.
Transposons or Transposable elements (TEs) are mobile genes capable of mobilization from one genomic location to another through non-homologous recombination. As this movement is mediated by its own proteins and does not contribute to the survival of the host that it inhabits, they are known as selfish genomic parasites. Despite their capacity for transposition inside genomes, they can frequently transpose the species boundaries and consequently migrate from one species to another. Such phenomenon is called Horizontal Transposons Transfer. HTT was first discovered by Daniels et al. (1984) when analysing a P element that was transferred from Drosophila willistoni to D. melanogaster. Since then, many more cases have been documented in the literature. Moreover, in the last years, such discoveries have been boosted by the unprecedented amount of new genomes available. Despite the recognition of HTT as a common phenomenon in recent years, it is still difficult to draw major conclusions about HTT ...
The availability of several whole genome sequences makes comparative analyses possible. In primate genomes, the priority of transposable elements (TEs) is significantly increased because they account for ~45% of the primate genomes, they can regulate the gene expression level, and they are associated with genomic fluidity in their host genomes. Here, we developed the BLAST-like alignment tool (BLAT) based comparative analysis for transposable elements (BLATCAT) program. The BLATCAT program can compare specific regions of six representative primate genome sequences (human, chimpanzee, gorilla, orangutan, gibbon, and rhesus macaque) on the basis of BLAT and simultaneously carry out RepeatMasker and/or Censor functions, which are widely used Windows-based web-server functions to detect TEs. All results can be stored as a HTML file for manual inspection of a specific locus. BLATCAT will be very convenient and efficient for comparative analyses of TEs in various primate genomes ...
A family of novel mobile DNA elements is described, examples of which are found at several independent locations and encode a variety of antibiotic resistance genes. The complete elements consist of two conserved segments separated by a segment of variable length and sequence which includes inserted antibiotic resistance genes. The conserved segment located 3′ to the inserted resistance genes was sequenced from Tn21 and R46, and the sequences are identical over a region of 2026 bases, which includes the sulphonamide resistance gene sull, and two further open reading frames of unknown function. The complete sequences of both the 3′ and 5′ conserved regions of the DNA element have been determined. A 59-base sequence element, found at the junctions of inserted DNA sequences and the conserved 3′ segment, is also present at this location in the R46 sequence. A copy of one half of this 59-base element is found at the end of the sull gene, suggesting that sull, though part of the conserved ...
Transposable Elements 2016, Meeting on Transposable Elements is a Genetics Meeting, organized in Cold Spring Harbor, New York. Learn More About Event
Dysregulation of transposable elements in Gasz testes.(A-B) Quantitative RT-PCR analysis of transposable elements in testes from embryonic, newborn, 7- and 1
A Genetic Screen Using the PiggyBac Transposon in Haploid Cells Identifies Parp1 as a Mediator of Olaparib Toxicity. . Biblioteca virtual para leer y descargar libros, documentos, trabajos y tesis universitarias en PDF. Material universiario, documentación y tareas realizadas por universitarios en nuestra biblioteca. Para descargar gratis y para leer online.
Background The revolutionary concept of jumping genes was conceived by McClintock in the late 1940s while studying the Activator/Dissociation (Ac/Ds) system in maize. Transposable elements (TEs) represent the most abundant component of many eukaryotic genomes. Mobile elements are a driving force of eukaryotic genome evolution. McClintocks Ac, the autonomous element of the Ac/Ds system, together with hobo from Drosophila and Tam3 from snapdragon define an ancient and diverse DNA transposon superfamily named hAT. Other members of the hAT superfamily include the insect element Hermes and Tol2 from medaka. In recent years, genetic tools derived from the cut and paste Tol2 DNA transposon have been widely used for genomic manipulation in zebrafish, mammals and in cells in vitro ...
Multiple methods have been introduced over the past 30 years to identify the genomic insertion sites of transposable elements and other DNA elements that integrate into genomes. However, each of these methods suffer from limitations that can frustrate attempts to map multiple insertions in a single genome and to map insertions in genomes of high complexity that contain extensive repetitive DNA. I introduce a new method for transposon mapping that is simple to perform, can accurately map multiple insertions per genome, and generates long sequence reads that facilitate mapping to complex genomes. The method, called TagMap, for Tagmentation-based Mapping, relies on a modified Tn5 tagmentation protocol with a single tagmentation adaptor followed by PCR using primers specific to the tranposable element and the adaptor sequence. Several minor modifications to normal tagmentation reagents and protocols allow easy and rapid preparation of TagMap libraries. Short read sequencing starting from the adaptor ...
Transposable elements (TEs) are mobile genetic elements. They are a significant component of many eukaryotic genomes. They are involved in chromosomal rearrangement by serving as substrates for homologous recombination, in creating new genes through a process of TE domestication, and in modifying and shuffling existing genes by transducing neighboring sequences (Lander et al., 2001). Therefore, both active and inactive TEs are potentially potent agents for genomic change (Kidwell and Lisch, 2001, 2002; Rizzon et al., 2002; Petrov et al., 2003). In the meantime, active TEs are being explored as useful tools for genetic transformation and possible gene drive mechanisms to deliver genes in natural populations (Ashburner et al.,1998; Alphey et al.,2002; Handler and OBrochta, 2004). My thesis project focuses on AGH1, a novel DNA-mediated TE in Anopheles gambiae and related mosquitoes. I have studied its genomic structure, insertion polymorphism, evolution, and transposition activity. As part of ...
Genomes of higher plants vary significantly in their size and complexity. Repetitive DNA sequences have been shown to be the major determinant of genome sizes in higher plants [13]. The prevalence of transposable elements and retroelements can promote unequal crossing-over leading to transposon-mediated rearrangements and gene duplications [40]. It has been hypothesized that transposable elements play a major role in the expansion and diversification of transmembrane receptor kinase-type disease resistance Xa21 gene family [9]. The abundance of retroelements has been observed in several genomic regions containing R genes or RGA loci, such as barley powdery mildew resistance gene, Mla, and Citrus virus resistance gene, Ctv [7, 8]. The variability among 14 rice Xa21 gene members has been considered to be generated mainly from the rearrangements mediated by transposon-like elements [9]. Rps1-k genes are arranged closely. About 38 copies of Rps1-k-like sequences were predicted to exist in the ...
DUGi: Viewing Item from repository DUGiDocs: Transposable elements (TEs) are mobile DNA sequences that have the ability to jump from one location of the genome to another and create copies of them during the process. Although their activity can create mostly harmful mutation, it also represent an important source of genetic variation that have been shown to rewire and fine-tune regulatory networks. Stress response mechanisms are highly conserved across organisms and a major target of natural selection. Despite the latest advances in evolutionary biology, adaptation process remains poorly understood. Therefore, studying stress pathways provide a great opportunity to study how adaptive processes occur. In this study we aim to identify genome-wide putatively adaptive TEs that are candidates to modulate stress response by the addition of stress response elements (SREs) in the promoter of Drosophila melanogaster genes. We combine bioinformatics and population genetics approaches to discard SREs found by
Vitamin B12 has been broadly associated to methionine metabolism, which is an integral part for organic methylation reactions, together with DNA methylation. However, the connection between vitamin B12 and DNA methylation continues to be controversial. In addition, theres rising proof for the affiliation between vitamin B12 and the danger of colorectal most cancers (CRC), though … Read more. ...
Transfer RNA (tRNA)-derived small RNAs (tsRNAs) have been discovered to play vital roles in the incidence and improvement of cancers. However, the tsRNA profile in gastric cancer is unknown. In this examine, we aimed to determine the worldwide tsRNA profile in plasma from gastric cancer sufferers and elucidate the function of tRF-33-P4R8YP9LON4VDP in gastric cancer. … Read more. ...
Read The rice R gene family: two distinct subfamilies containing several miniature inverted-repeat transposable elements, Plant Molecular Biology on DeepDyve, the largest online rental service for scholarly research with thousands of academic publications available at your fingertips.
Bacterial insertion sequences are the simplest form of autonomous mobile DNA. It is unknown whether they need to have beneficial effects to infect and persist in bacterial populations, or whether horizontal gene transfer suffices for their persistence. We address this question by using branching process models to investigate the critical, early phase of an insertion sequence infection. We find that the probability of a successful infection is low and depends linearly on the difference between the rate of horizontal gene transfer and the fitness cost of the insertion sequences. Our models show that the median time to extinction of an insertion sequence that dies out is very short, while the median time for a successful infection to reach a modest population size is very long. We conclude that horizontal gene transfer is strong enough to allow the persistence of insertion sequences, although infection is an erratic and slow process. ...
DNA transposons are ubiquitous components of eukaryotic genomes. Academ superfamily of DNA transposons is one of the least characterized DNA transposon superfamilies in eukaryotes. DNA transposons belonging to the Academ superfamily have been reported from various animals, one red algal species Chondrus crispus, and one fungal species Puccinia graminis. Six Academ families from P. graminis encode a helicase in addition to putative transposase, while some other families encode a single protein which contains a putative transposase and an XPG nuclease. Systematic searches on Repbase and BLAST searches against publicly available genome sequences revealed that several species of fungi and animals contain multiple Academ transposon families encoding a helicase. These AcademH families generate 9 or 10-bp target site duplications (TSDs) while Academ families lacking helicase generate 3 or 4-bp TSDs. Phylogenetic analysis clearly shows two lineages inside of Academ, designated here as AcademH and AcademX for
The gammaherpesviruses include the human pathogens Epstein-Barr virus and Kaposis sarcoma-associated herpesvirus. These viruses establish life-long infections of the host and are associated with a number of malignancies. To better understand gammaherpesvirus pathogenesis, we and others have begun to utilize infection of mice with murine gammaherpesvirus 68 (γHV68). γHV68 is a member of the gamma-2-herpesvirus subfamily based on genome sequence (13, 51). Sequence analysis of γHV68 identified 80 ATG-initiated open reading frames (ORFs) predicted to encode proteins of at least 100 amino acids in length (51). The majority of these ORFs were homologous to known genes present in other gammaherpesviruses (51). The requirement for most of the predicted ORFs during viral replication in vitro is unknown.. Traditional methods of generating mutations in gammaherpesviruses are time-consuming and labor intensive. Homologous recombination in mammalian cells relies on the use of a genetic marker (e.g., ...
al., 1994), it was observed that a 3.8-kb HindIII fragment was present in multiple copies in X. campestris pv. juglandis genome when the fragment was used as a probe in the Southern hybridization with HindIII-digested genomic DNA of X. campestris pv. juglandis. To further localize the repetitive sequence, several subclones from the fragment were used as probes to hybridize with HindIII-digested genomic DNA. The Southern hybridization using 2.0-kb PstI-ClaI fragment as a probe showed the same repetitive pattern as 3.8-kb HindIII fragment; in contrast, the probes outside the 2.0-kb fragment hybridized only to a single genomic restriction fragment, indicating that the repetitive sequence was within the 2.0-kb PstI-ClaI fragment. The 2.0-kb fragment was ligated into pBluescript SK(+), resulting in plasmid pISJ12. The insertion sequence-like element in the fragment was named IS1403 afterward.. To isolate a homologous IS from X. campestris pv. campestris XCC1-1, a 0.5-kb AvaII internal fragment of ...
ISfinder (www-is.biotoul.fr) is a dedicated database for bacterial insertion sequences (ISs). It has superseded the Stanford reference center. One of its functions is to assign IS names and to provide a focal point for a coherent nomenclature. It is also the repository for ISs. Each new IS is indexe …
In this study, first we showed that the Tol2 transposon system is a useful technique in generating stable transfected primary culture cells and, second, we demonstrated that the Tol2 transposon system is applicable to the study of circadian clock oscillations.. The Tol2 transposon was originally discovered from Medaka fish (Orzyias latipes) [12]. An active autonomous member of Tol2 was first identified by the analysis using zebrafish embryos [13]. Since then, the Tol2 transposon system has been mainly used for random insertion mutagenesis and transgene in zebrafish [14]. Although recent reports have indicated that the transposon systems such as piggyBac and SleepingBeauty in addition to Tol2 are also active in mammalian cells [15, 16], few studies have been reported that utilized the Tol2 system for transfection to mammalian primary culture cells. In the present study, we showed that the Tol2 transposon system is a useful tool in generating stable transfected primary culture cells such as MEF ...
We present data on the relationship between the rate of transposition and copy number in the genome for the copia and Doc retrotransposons of Drosophila melanogaster. copia and Doc transposition rates were directly measured in sublines of the isogenic 2b line using individual males or females, respectively, with a range of copia copy numbers from 49 to 103 and Doc copy numbers from 112 to 235 per genome. Transposition rates varied from 3 x 10(-4) to 2 x 10(-2) for copia and from 2 x 10(-4) to 2 x 10(-3) for Doc. A positive relationship between transposition rate and copy number was found both for copia and for Doc when the data were analysed across all the 2b individuals; no significant correlation was found when the data were analysed across the subline means for both retrotransposons tested. Overall, correlation between copia and Doc transposition rate and their copy number in the genome, if any, was not negative, which would be expected if transposable elements (TEs) self-regulate their copy number.
Miniature inverted repeat transposable elements (MITEs) are abundant non-autonomous elements, playing important roles in shaping gene and genome evolution. Their characteristic structural features are suitable for automated identification by computational approaches, however, de novo MITE discovery at genomic levels is still resource expensive. Efficient and accurate computational tools are desirable. Existing algorithms process every member of a MITE family, therefore a major portion of the computing task is redundant. In this study, redundant computing steps were analyzed and a novel algorithm emphasizing on the reduction of such redundant computing was implemented in MITE Digger. It completed processing the whole rice genome sequence database in ~15 hours and produced 332 MITE candidates with low false positive (1.8%) and false negative (0.9%) rates. MITE Digger was also tested for genome wide MITE discovery with four other genomes. MITE Digger is efficient and accurate for genome wide retrieval of
TY - JOUR. T1 - Germline transgenesis of the chordate Ciona intestinalis with hyperactive variants of sleeping beauty transposable element. AU - Hozumi, Akiko. AU - Mita, Kaoru. AU - Miskey, Csaba. AU - Mates, Lajos. AU - Izsvak, Zsuzsanna. AU - Ivics, Zoltan. AU - Satake, Honoo. AU - Sasakura, Yasunori. PY - 2013/1/1. Y1 - 2013/1/1. N2 - Background: Transposon-mediated transgenesis is an excellent method for creating stable transgenic lines and insertional mutants. In the chordate Ciona intestinalis, Minos is the only transposon that has been used as the tool for germline transformation. Adding another transposon system in this organism enables us to conduct genetic techniques which can only be realized with the use of two transposons. Results: In the present study, we found that another Tc1/mariner superfamily transposon, sleeping beauty (SB), retains sufficient activity for germline transformation of C. intestinalis. SB shows efficiencies of germline transformation, insertion into gene coding ...
Large-scale sequencing of human cancer genomes and mouse transposon-induced tumors has identified a vast number of genes mutated in different cancers. One of the outstanding challenges in this field is to determine which genes, when mutated, contribute to cellular transformation and tumor progression. To identify new and conserved genes that drive tumorigenesis we have developed a novel cancer model in a distantly related vertebrate species, the zebrafish, Danio rerio. The Sleeping Beauty (SB) T2/Onc transposon system was adapted for somatic mutagenesis in zebrafish. The carp ß-actin promoter was cloned into T2/Onc to create T2/OncZ. Two transgenic zebrafish lines that contain large concatemers of T2/ OncZ were isolated by injection of linear DNA into the zebrafish embryo. The T2/OncZ transposons were mobilized throughout the zebrafish genome from the transgene array by injecting SB11 transposase RNA at the 1-cell stage. Alternatively, the T2/OncZ zebrafish were crossed to a transgenic line that
TY - JOUR. T1 - Characterization of Gandalf, a new inverted-repeat transposable element of Drosophila koepferae. AU - Marín, Ignacio. AU - Fontdevila, Antonio. PY - 1995/8/1. Y1 - 1995/8/1. N2 - The cloning and characterization of Gandalf, a new DNA-transposing mobile element obtained from the Drosophila koepferae (repleta group) genome is described. A fragment of Gandalf was found in a middle repetitive clone that shows variable chromosomal localization. Restriction, Southern blot, PCR and sequencing analyses have shown that most Gandalf copies are about 1 kb long, are flanked by 12 by inverted terminal repeats and contain subterminal repetitive regions on both sides of the element. As with other elements of the DNA-transposing type (known as the Ac family), the Gandalf element generates 8 by direct duplications at the insertion point. Coding region analysis has shown that the longer open reading frame found in Gandalf copies could encode part of a protein. However, whether or not the 1 kb ...
Transposable elements (TEs) are ubiquitous DNA sequences that can change their positions within a genome or transfer horizontally among genomes (Gilbert et al. 2010). TE movements may cause mutations, affect gene expression, and change genome sizes and structures; therefore, they are considered an important force in gene and genome evolution (Kazazian 2004). TEs are grouped into two major classes according to their transposition mechanism and sequence features. Class I elements, retrotransposons, mobilize via a copy-and-paste model and have the potential to dramatically increase copy number; whereas, class II elements, DNA transposons, transpose via a cut-and-paste model or rolling-circle replication (Kapitonov and Jurka 2001; Wicker et al. 2007). Class II elements have been further divided into 12 superfamilies (Feschotte and Pritham 2007; Wicker et al. 2007). Except for the Helitron and Crypton superfamilies, all class II elements have terminal inverted repeats (TIRs). To date, only six ...
Cell culture and transposition assay HEK 293 cells had been maintained in MEMa medium supplemented with 10% FBS, 100 units ml penicillin, and a hundred ug mL streptomycin. The specifics for your transposition assays had been described pre viously. Inhibitors,Modulators,Libraries Exercise assay in the piggyBac transposase A equivalent procedure as thorough previously was employed to co transfect a hundred ng of piggyBac donor, with various quantity of the piggyBac helper, pCMV Myc piggyBac, ranging from 0 300 ng into 1. 2 105 of HEK 293 cells. pcNDA3. 1NEO, an empty vector used in our prior examine, was employed to best the total level of DNA transfected to 400 ng. Each and every trans fection condition was completed in triplicate. Twenty 4 hours just after transfection, one fifth of transfected cells were subjected to transposition assay.. The remaining transfected cells in triplicate had been pooled and grew in the 35 mm plate for a further twenty four hours prior to staying subjected to ...
TY - JOUR. T1 - Short interspersed transposable elements (SINEs) are excluded from imprinted regions in the human genome. AU - Greally, John M.. PY - 2002/1/8. Y1 - 2002/1/8. N2 - To test whether regions undergoing genomic imprinting have unique genomic characteristics, imprinted and nonimprinted human loci were compared for nucleotide and retroelement composition. Maternally and paternally expressed subgroups of imprinted genes were found to differ in terms of guanine and cytosine, CpG, and retroelement content, indicating a segregation into distinct genomic compartments. Imprinted regions have been normally permissive to L1 long interspersed transposable element retroposition during mammalian evolution but universally and significantly lack short interspersed transposable elements (SINEs). The primate-specific Alu SINEs, as well as the more ancient mammalian-wide interspersed repeat SINEs, are found at significantly low densities in imprinted regions. The latter paleogenomic signature ...
Transposable elements (TEs) are exceptional contributors to eukaryotic genome diversity. Their ubiquitous presence impacts the genomes of nearly all species and mediates genome evolution by causing mutations and chromosomal rearrangements and by modulating gene expression. We performed an exhaustive analysis of the TE content in 18 fungal genomes, including strains of the same species and species of the same genera. Our results depicted a scenario of exceptional variability, with species having 0.02 to 29.8% of their genome consisting of transposable elements. A detailed analysis performed on two strains of Pleurotus ostreatus uncovered a genome that is populated mainly by Class I elements, especially LTR-retrotransposons amplified in recent bursts from 0 to 2 million years (My) ago. The preferential accumulation of TEs in clusters led to the presence of genomic regions that lacked intra- and inter-specific conservation. In addition, we investigated the effect of TE insertions on the expression ...
The morphological stasis of coelacanths has long suggested a slow evolutionary rate. General genomic stasis might also imply a decrease of transposable elements activity. To evaluate the potential activity of transposable elements (TEs) in living fossil species, transcriptomic data of Latimeria chalumnae and its Indonesian congener Latimeria menadoensis were compared through the RNA-sequencing mapping procedures in three different organs (liver, testis, and muscle). The analysis of coelacanth transcriptomes highlights a significant percentage of transcribed TEs in both species. Major contributors are LINE retrotransposons, especially from the CR1 family. Furthermore, some particular elements such as a LF-SINE and a LINE2 sequences seem to be more expressed than other elements. The amount of TEs expressed in testis suggests possible transposition burst in incoming generations. Moreover, significant amount of TEs in liver and muscle transcriptomes were also observed. Analyses of elements ...
The nivea locus of Antirrhinum majus encodes the enzyme chalcone synthase required for the synthesis of red anthocyanin pigment. The stable allele niv-44 contains an insertion in the nivea gene (Tam2) which has all the structural features of a transposable element. We have shown that this insertion can excise from the nivea locus when niv-44 is combined with another allele (niv-99) in a heterozygote. Activation of Tam2 excision is caused by a factor tightly linked to the niv-99 allele and may be due to complementation between Tam2 and a related element, Tam1. Factors which repress the excision of Tam2 and Tam1 are also described. Repression is not inherited in a simple mendelian way. Many stable mutations may be due to the insertion of transposable elements. Our data suggest that their stability may be due to the absence in the genome of activating factors and to the presence of repressors.
Recent analysis of the human and mouse genomes has shown that a substantial proportion of protein coding genes and cis-regulatory elements contain transposable element (TE) sequences, implicating TE domestication as a mechanism for the origin of genetic novelty. To understand the general role of TE domestication in eukaryotic genome evolution, it is important to assess the acquisition of functional TE sequences by host genomes in a variety of different species, and to understand in greater depth the population dynamics of these mutational events. Using an in silico screen for host genes that contain TE sequences, we identified a set of 63 mature chimeric transcripts supported by expressed sequence tag (EST) evidence in the Drosophila melanogaster genome. We found a paucity of chimeric TEs relative to expectations derived from non-chimeric TEs, indicating that the majority (~80%) of TEs that generate chimeric transcripts are deleterious and are not observed in the genome sequence. Using a pooled-PCR
The expression of chromosomal AmpC β-lactamase in Pseudomonas aeruginosa is negatively regulated by the activity of an amidase, AmpD. In the present study we examined resistant clinical P. aeruginosa strains and several resistant variants isolated from in vivo and in vitro biofilms for mutations in ampD to find evidence for the genetic changes leading to high-level expression of chromosomal β-lactamase. A new insertion sequence, IS1669, was found located in the ampD genes of two clinical P. aeruginosa isolates and several biofilm-isolated variants. The presence of IS1669 in ampD resulted in the expression of high levels of AmpC β-lactamase. Complementation of these isolates with ampD from the reference P. aeruginosa strain PAO1 caused a dramatic decrease in the expression of AmpC β-lactamase and a parallel decrease of the MIC of ceftazidime to a level comparable to that of PAO1. One highly resistant, constitutive β-lactamase-producing variant contained no mutations in ampD, but a point ...
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TY - JOUR. T1 - Insertional mutagenesis by the Tol2 transposon-mediated enhancer trap approach generated mutations in two developmental genes. T2 - tcf7 and synembryn-like. AU - Nagayoshi, Saori. AU - Hayashi, Eriko. AU - Abe, Gembu. AU - Osato, Naoki. AU - Asakawa, Kazuhide. AU - Urasaki, Akihiro. AU - Horikawa, Kazuki. AU - Ikeo, Kazuho. AU - Takeda, Hiroyuki. AU - Kawakami, Koichi. PY - 2008/1. Y1 - 2008/1. N2 - Gene trap and enhancer trap methods using transposon or retrovirus have been recently described in zebrafish. However, insertional mutants using these methods have not been reported. We report here development of an enhancer trap method by using the Tol2 transposable element and identification and characterization of insertional mutants. We created 73 fish lines that carried single copy insertions of an enhancer trap construct, which contained the zebrafish hsp70 promoter and the GFP gene, in their genome and expressed GFP in specific cells, tissues and organs, indicating that the ...
High-throughput analysis of genome-wide transposon mutant libraries is a powerful tool for (conditional) essential gene discovery. Recently, several next generation sequencing approaches, e.g. Tn-seq, INseq and TraDIS, have been developed that accurately map the site of transposon insertions by mutant-specific amplification and sequence readout of DNA flanking the transposon insertions site, assigning a measure of essentiality based on the number of reads per gene or per mutant. However, analysis of these large and complex datasets is hampered by the lack of an easy to use and automated tool for transposon insertion sequencing data ...
Many new Drosophila genomes have been sequenced in recent years using new-generation sequencing platforms and assembly methods. Transposable elements (TEs), being repetitive sequences, are often misassembled, especially in the genomes sequenced with short reads. Consequently, the mobile fraction of many of the new genomes has not been analyzed in detail or compared with that of other genomes sequenced with different methods, which could shed light into the understanding of genome and TE evolution. Here we compare the TE content of three genomes: D. buzzatii st-1, j-19, and D. mojavensis. We have sequenced a new D. buzzatii genome (j-19) that complements the D. buzzatii reference genome (st-1) already published, and compared their TE contents with that of D. mojavensis. We found an underestimation of TE sequences in Drosophila genus NGS-genomes when compared to Sanger-genomes. To be able to compare genomes sequenced with different technologies, we developed a coverage-based method and applied it to the D
The Tn3 transposon is a 4957 base pair mobile genetic element, found in prokaryotes. It encodes three proteins: β-lactamase, an enzyme that confers resistance to β-lactam antibiotics (and is encoded by the gene Bla). Tn3 transposase (encoded by gene tnpA) Tn3 resolvase (encoded by gene tnpR) Initially discovered as a repressor of transposase, resolvase also plays a role in facilitating Tn3 replication (Sherratt 1989). The transposon is flanked by a pair of 38bp inverted repeats. This first stage is catalysed by transposase. The plasmid containing the transposon (the donor plasmid) fuses with a host plasmid (the target plasmid). In the process, the transposon and a short section of host DNA are replicated. The end product is a cointegrate plasmid containing two copies of the transposon. Shapiro (1978) proposed the following mechanism for this process: Four single-strand cleavages occur - one on each strand of the donor plasmid and one on each strand of the target plasmid. The donor and target ...
Research in the Arkhipova lab is focused on transposable elements (TEs) in chromosomal DNA. As part of the A. vaga genome sequencing consortium, we have analyzed repetitive DNA content in the genome of the bdelloid rotifer, Adineta vaga (pictured), a microscopic freshwater invertebrate that reproduces asexually. This is the first representative of the Phylum Rotifera for which a complete genome sequence has been determined. We found that TEs and TE-related sequences occupy an unusually small proportion of the A. vaga genome assembly (ca. 3% of genomic DNA). This is in contrast with other aquatic metazoans such as Hydra or Nematostella, where TEs make up 57% and 26% of the genome, respectively. Another surprising feature is the high diversity of TE families and the extremely low number of copies for each family, which indicates that the incoming TEs do not proliferate efficiently in A. vaga. Out of 254 families, the overwhelming majority (208) is represented by only one or two full-length copies ...
Tn-Seq is an experimental method for probing the functions of genes through construction of complex random transposon insertion libraries and quantification of each mutants abundance using next-generation sequencing. An important emerging application of Tn-Seq is for identifying genetic interactions, which involves comparing Tn mutant libraries generated in different genetic backgrounds (e.g. wild-type strain versus knockout strain). Several analytical methods have been proposed for analyzing Tn-Seq data to identify genetic interactions, including estimating relative fitness ratios and fitting a generalized linear model. However, these have limitations which necessitate an improved approach. We present a hierarchical Bayesian method for identifying genetic interactions through quantifying the statistical significance of changes in enrichment. The analysis involves a four-way comparison of insertion counts across datasets to identify transposon mutants that differentially affect bacterial fitness
Interestingly there is no rule such as the higher evolved an organism the more transposable elements. Although we find more transposable elements in higher evolved organisms this rule can not be maintained if compared single species as frogs and humans.. Transposons most often code for transposase the enzyme responsible for the transposon dislocation. As Transposons are so common in a genome it is not surprising that transposases are the most common genes in a genome [2].. ...
antibody-antibodies.com is the marketplace for research antibodies. Find the right antibody for your research needs. The transposable elements of the Drosophila melanogaster euchromatin: a genomics perspective.
The ascomycete fungus Colletotrichum higginsianum causes anthracnose disease of brassica crops and the model plant Arabidopsis thaliana. Previous versions of the genome sequence were highly fragmented, causing errors in the prediction of protein-coding genes and preventing the analysis of repetitive sequences and genome architecture. Here, we re-sequenced the genome using single-molecule real-time (SMRT) sequencing technology and, in combination with optical map data, this provided a gapless assembly of all twelve chromosomes except for the ribosomal DNA repeat cluster on chromosome 7. The more accurate gene annotation made possible by this new assembly revealed a large repertoire of secondary metabolism (SM) key genes (89) and putative biosynthetic pathways (77 SM gene clusters). The two mini-chromosomes differed from the ten core chromosomes in being repeat- and AT-rich and gene-poor but were significantly enriched with genes encoding putative secreted effector proteins. Transposable elements (TEs)
At the beginning of this week we spoke to Dr. Michael Hynes, who was able to give us E. coli SM10 and SM17-1 cells containing the plasmid pOT182. This plasmid contains an E. coli origin of replication, allowing it to act as a suicide vector when transferred to a different bacterial species. pOT182 contains a Tn5 transposon element containing a promotorless lacZ gene, genes for tetracycline resistance as well as a beta-lactamase, transposase and an E. coli origin of replication. These elements are bordered by insertion element sequences which are recognised by the transposase. When transferred to a different host through conjugation, the plasmid itself can no longer replicate. The transposase however can recognise and transfer the sequence between the insertion elements in a cut-and-paste fashion randomly into the genome. In this fashion, the tetracycline and beta-lactam resistant traits would only persist in cells in which the transposon has jumped into the genome, allowing these antibiotics to ...
Pyrenophora teres, P. teres f. teres (PTT) and P. teres f. maculata (PTM) cause significant diseases in barley, but little is known about the large-scale genomic differences that may distinguish the two forms. Comprehensive genome assemblies were constructed from long DNA reads, optical and genetic maps. As repeat masking in fungal genomes influences the final gene annotations, an accurate and reproducible pipeline was developed to ensure comparability between isolates. The genomes of the two forms are highly collinear, each composed of 12 chromosomes. Genome evolution in P. teres is characterized by genome fissuring through the insertion and expansion of transposable elements (TEs), a process that isolates blocks of genic sequence. The phenomenon is particularly pronounced in PTT, which has a larger, more repetitive genome than PTM and more recent transposon activity measured by the frequency and size of genome fissures. PTT has a longer cultivated host association and, notably, a greater range ...
Plant Epigenetics Unit Assistant Professor Hidetoshi Saze​ Abstract Epigenetic Regulation of Genes and Transposable Elements in Plants We are trying to understand epigenetic mechanisms for regulation of gene and transposon activities in the genomes of model plant systems such as Arabidopsis thaliana and rice, using genetic, biochemical and genomic approaches. In addition, we
Adaptation requires genetic variation, but founder populations are generally genetically depleted. Here we sequence two populations of an inbred ant that diverge in phenotype to determine how variability is generated. Cardiocondyla obscurior has the smallest of the sequenced ant genomes and its structure suggests a fundamental role of transposable elements (TEs) in adaptive evolution. Accumulations of TEs (TE islands) comprising 7.18% of the genome evolve faster than other regions with regard to single-nucleotide variants, gene/exon duplications and deletions and gene homology. A non-random distribution of gene families, larvae/adult specific gene expression and signs of differential methylation in TE islands indicate intragenomic differences in regulation, evolutionary rates and coalescent effective population size. Our study reveals a tripartite interplay between TEs, life history and adaptation in an invasive species. ...
Knockout Sudoku allows construction of whole-genome knockout collections for a wide range of microorganisms at a lower cost and increased speed, using combinatorial pooling, next-generation sequencing, and a Bayesian inference algorithm to process and annotate extremely large progenitor transposon insertion mutant collections. Knockout Sudoku is a method for the construction of whole-genome knockout collections for a wide range of microorganisms with as little as 3 weeks of dedicated labor and at a cost of ∼$10,000 for a collection for a single organism. The method uses manual 4D combinatorial pooling, next-generation sequencing, and a Bayesian inference algorithm to rapidly process and then accurately annotate the extremely large progenitor transposon insertion mutant collections needed to achieve saturating coverage of complex microbial genomes. This method is ∼100× faster and 30× lower in cost than the next comparable method (In-seq) for annotating transposon mutant collections by combinatorial
Processes and new genetic materials are provided for cloning specific DNA fragments by using a unique conjugative transposon designated Tn916. The transposon is used to first target specific genes by insertional inactivation. A restriction fragment containing the inserted transposon is then inserted into a plasmid vector and transformed into Escherichia coli or other suitable host by selection for the transposon encoded tetracycline (Tc) resistance. The transformants so produced are then grown in the absence of tetracycline conditions under which Tn916 excises from the chimeric plasmid thus restoring the integrity of the DNA into which the transposon was originally inserted. This process provides a new and useful way of producing new life forms that are useful for making desired products having established utility.
Uncontrolled transposable element (TE) insertions and excisions can cause chromosome breaks and mutations with dramatic deleterious effects. The PIWI interacting RNA (piRNA) pathway functions as an adaptive TE silencing system during germline development. Several essential piRNA pathway proteins appear to be rapidly evolving, suggesting that TEs and the silencing machinery may be engaged in a classical evolutionary arms race. Using a variety of molecular evolutionary and population genetic approaches, we find that the piRNA pathway genes rhino, krimper, and aubergine show patterns suggestive of extensive recurrent positive selection across Drosophila species. We speculate that selection on these proteins reflects crucial roles in silencing unfamiliar elements during vertical and horizontal transmission of TEs into naive populations and species, respectively.
The discovery of transposable elements (TEs) by Barbara McClintock in the 1940s, triggered a new dawning in the development of evolutionary theory. However, similar to Gregor Mendels development of the laws of heredity in the nineteenth century, it was a long time before the full significance of this discovery was appreciated. Nevertheless, by the beginning of the 21st century, the study and recognition of TEs as significant factors in evolution was well underway. However, many evolutionary biologists still choose to ignore them, to highlight the loss of fitness in some individuals caused by TEs, or concentrate on the supposed parasitic nature of TEs, and the diseases they cause.. The major concept and theme of this thesis is that the ubiquitous and extremely ancient transposable elements are not merely junk DNA or selfish parasites but are instead powerful facilitators of evolution. They can create genomic dynamism, and cause genetic changes of great magnitude and variety in the ...
Transposed elements (TEs) are known to affect transcriptomes, because either new exons are generated from intronic transposed elements (this is called exonization), or the element inserts into the exon, leading to a new transcript. Several examples in the literature show that isoforms generated by an exonization are specific to a certain tissue (for example the heart muscle) or inflict a disease. Thus, exonizations can have negative effects for the transcriptome of an organism. As we aimed at detecting other tissue- or tumor-specific isoforms in human and mouse genomes which were generated through exonization of a transposed element, we designed the automated analysis pipeline SERpredict (SER = S pecific E xonized R etroelement) making use of Bayesian Statistics. With this pipeline, we found several genes in which a transposed element formed a tissue- or tumor-specific isoform. Our results show that SERpredict produces relevant results, demonstrating the importance of transposed elements in shaping both
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The transposable element (TE), Tn5, is a conservative transposon that is able to insert a segment of genes bordered by specific 19bp insertion sequences (IS) from one part of the genome (e.g. plasmid vector) randomly to another location, such as the chromosome (Reznikoff, 2008). The transposition event is catalyzed by a transposase enzyme encoded by Tnp gene included in the TE. By inserting a vector construct containing the TE with selectable markers (such as tetracyclin resistance and lacZ) into an organism with a desirable phenotype, we can find out what genetic elements (e.g. genes and promoters) are responsible for that particular function. This can happen via a random insertion of a TE containing a promoterless reporter gene downstream of promoter elements that creates a transcriptional fusion, providing activity in response to specific environmental stimuli. Another advantage of using a transposon approach is that it creates a saturating library of mutants where all possible genetic ...
Stable transgenesis is an undeniable key to understanding any genetic system. Retrovirus-based insertional strategies, which feature several technical challenges when they are used, are often limited to one particular species, and even sometimes to a particular cell type as the infection depends on certain cellular receptors. A universal-like system, which would allow both stable transgene expression independent of the cell type and an efficient sorting of transfected cells, is required when handling cellular models that are incompatible with retroviral strategies. We report here on the combination of a stable insertional transgenesis technique, based on the Tol2 transposon system together with the magnetic cell sorting (MACS) technique, which allows specific selection of cells carrying the transgene in an efficient, reliable and rapid way. This new Tol2/MACS system leads to stable expression in a culture of primary chicken erythroid cells highly enriched in cells expressing the transgene of interest.