What is the difference between Autopolyploidy and Allopolyploidy? Autopolyploidy and Allopolyploidy are two main types of polyploidy. Autopolyploidy is the...
Polyploidy was first discovered by Winkler in 1916 during his observations of a spontaneous autopolyploid induced by mechanically damaged tissue (Grant, 1971). Winge (1917) proposed an explanation for polyploidy using an arithmetic series he had observed in Chrysanthemum (2n=18, 36, 54, 72, and 90) and Chenopodium (2n=18, 36) (Grant, 1971). Winge hypothesized that polyploidy occurred by successive increases in the original somatic chromosome number. The most comprehensive work on polyploidy and its relationship to plant evolution is the book "Plant Speciation" by Vern Grant (1981). It has been estimated that 30% to 70% of angiosperms are polyploids (Grant, 1971). The broad range in estimates for angiosperm polyploidy is due to a lack of knowledge about whether these plants are ancient polyploids, or whether more recent events have caused the polyploidy we observe today. Furthermore, no one really knows the true base number of the angiosperms, making estimates of polyploidy for this large and ...
Fig. 1. Polyploid incidence and speciation frequencies across major groups of vascular plants. Polyploid speciation frequencies are the fractions of branching events that were accompanied by a ploidy shift across the studied phylogenetic trees for each group. The speciation frequencies reported here are based on an irreversible model of polyploid evolution. A binomial standard error follows each incidence and frequency estimate. See Fig. S1 for a diagrammatic explanation of estimation methods for polyploid speciation frequencies. Phylogenetic hypothesis/timescale modified from (13), and based on clades defined in refs. 13-16; clade species richness from refs. 13 and 34. The Higher Monocots are represented by Arecales, Commelinales, Poales, Proteales, Zingiberales; the Basal Monocots by Alistmatales, Asparagales, Dioscoreales, Liliales, Pandanales.. ...
ABSTRACT During the past decade there has been a tremendous resurgence of interest in polyploidy that has in large part been stimulated by the development of increasingly powerful genetic and genomic tools. The result has been numerous new insights into the genomic and genetic consequences of polyploidy. The plethora of new discoveries has dramatically reshaped traditional views and concomitantly revealed that polyploidy is a highly dynamic and ubiquitous process. These recent advances in our understanding of polyploidy have stimulated numerous reviews, most focused on the various genetic, epigenetic, and genomic consequences of polyploid evolution. Whereas genetic and genomic attributes of polyploidization have received considerable attention, other crucial areas of polyploid evolution have received much less (e.g., ecology, pollination biology, physiology). The focus of this paper is not to review again recent discoveries, but to emphasize what we do not yet know about polyploidy, which ...
In the past few years we have analysed alterations in genome structure and expression that occur in wheat upon allopolyploidization. Our major findings in natural and synthetic allopolyploid wheat are reviewed here. It was found that allopolyploidization brings about rapid genome evolution through the instantaneous generation of a variety of cardinal genetic and epigenetic alterations comprising: (1) non-random elimination of coding and non-coding DNA sequences, (2) epigenetic changes such as DNA methylation of coding and non-coding DNA leading, among others, to gene silencing, and (3) activation of retroelements, which in turn alters the expression of adjacent genes. These changes were reproducible, occurring in the F1 hybrids or in the first generation(s) of a series of nascent allopolyploids corresponding to various interspecific and intergeneric combinations. Moreover, these changes were similar to those that occurred twice in nature: first, at the transition from diploid to tetraploid wheat ...
Background: Whole genome duplication plays a central role in plant evolution. There are two main classes of polyploid formation: autopolyploids which arise within one species by doubling of similar homologous genomes; in contrast, allopolyploidy (hybrid polyploidy) arise via hybridization and subsequent doubling of nonhomologous (homoeologous) genomes. The distinction between polyploid origins can be made using gene phylogenies, if alleles from each genome can be correctly retrieved. We examined whether two closely related tetraploid Mediterranean shrubs (Medicago arborea and M. strasseri) have an allopolyploid origin - a question that has remained unsolved despite substantial previous research. We sequenced and analyzed ten low-copy nuclear genes from these and related species, phasing all alleles. To test the efficacy of allele phasing on the ability to recover the evolutionary origin of polyploids, we compared these results to analyses using unphased sequences. Results: In eight of the gene ...
True polyploidy rarely occurs in humans, although polyploid cells occur in highly differentiated tissue, such as liver parenchyma, heart muscle, placenta and in bone marrow.[1][48] Aneuploidy is more common. Polyploidy occurs in humans in the form of triploidy, with 69 chromosomes (sometimes called 69, XXX), and tetraploidy with 92 chromosomes (sometimes called 92, XXXX). Triploidy, usually due to polyspermy, occurs in about 2-3% of all human pregnancies and ~15% of miscarriages.[citation needed] The vast majority of triploid conceptions end as a miscarriage; those that do survive to term typically die shortly after birth. In some cases, survival past birth may be extended if there is mixoploidy with both a diploid and a triploid cell population present. There has been one report of a child surviving to the age of seven months with complete triploidy syndrome. He failed to exhibit normal mental or physical neonatal development, and died from a Pneumocystis carinii infection, which indicates a ...
Abstract: Allopolyploidy is a common feature in many angiosperm genera. The perennial wild relatives of soybean in the genus Glycine include at least nine recently formed (within the last million years) allopolyploid taxa. This study examined three allopolyploid and four diploid progenitor taxa using genome-wide single nucleotide polymorphisms (SNPs) and network analysis. Genotyping by sequencing (GBS) was used to generate SNPs and results were compared with previous analyses from transcriptome data. Three lanes of Illumina sequencing produced genotypes for 70 accessions and an alignment of 22 806 SNPs across eight taxa with no missing data. The alignment combined with network analysis confirmed results from previous studies. In addition, the extended sampling made possible by GBS identified accessions that have either been misclassified or samples that came from mixed seed stocks. The most intriguing results are the discovery of previously unrecognized substructure within diploid taxa, and the ...
Polyploidy occurs in cells and organisms when there are more than two paired (homologous) sets of chromosomes. Most organisms are normally diploid, meaning they have two sets of chromosomes - one set inherited from each parent. Polyploidy may occur due to abnormal cell division. It is most commonly found in plants, but it does sometimes happen in animals.[1] Some estimates suggest that 30-80% of living plant species are polyploid, and many lineages show evidence of ancient polyploidy (paleopolyploidy) in their genomes.[2] Huge increases in angiosperm (flowering plants) diversity have coincided with the timing of ancient genome duplications shared by many species.[3] 15% of angiosperm and 31% of fern speciation events are accompanied by ploidy increase.[4][5]. Polyploid plants arise spontaneously in nature. Many polyploids are fitter than their parental species, and may display novel variation or morphologies that contribute to speciation and eco-niche exploitation.[6][7][8]. Polyploidy may occur ...
Glycine subgenus Glycine, the sister group to the cultivated soybean and its progenitor, have received considerable study over several decades. The combination of biosystematic data and an extensive germplasm collection has provided a strong foundation for molecular systematic studies in the group, including those on allopolyploids. These studies have shown that the various polyploid taxa known from the subgenus are all part of a single large allopolyploid complex, linked by shared diploid genomes. Many elements of the complex have arisen recently, and most show evidence of recurrent origins. However, there are also many dissimilarities among even closely related polyploids. Polyploids differ from one another in such ways as number of origins, amount of allelic diversity harboured at different loci, bidirectional vs. unidirectional origins, retention of ribosomal gene homoeologues, success as measured by geographical range and abundance, and patterns of gene expression. © 2004 The Linnean ...
Polyploid cells and organisms are those containing more than two paired (homologous) sets of chromosomes. Most species whose cells have nuclei (Eukaryotes) are diploid, meaning they have two sets of chromosomes-one set inherited from each parent. However, polyploidy is found in some organisms and is especially common in plants. In addition, polyploidy occurs in some tissues of animals that are otherwise diploid, such as human muscle tissues.[1] This is known as endopolyploidy. Species whose cells do not have nuclei, that is, Prokaryotes, may be polyploid organisms, as seen in the large bacterium Epulopiscium fishelsoni [1]. Hence ploidy is defined with respect to a cell. Most eukaryotes have diploid somatic cells, but produce haploid gametes (eggs and sperm) by meiosis. A monoploid has only one set of chromosomes, and the term is usually only applied to cells or organisms that are normally diploid. Male bees and other Hymenoptera, for example, are monoploid. Unlike animals, plants and ...
Polyploid cells and organisms are those containing more than two paired (homologous) sets of chromosomes. Most species whose cells have nuclei (Eukaryotes) are diploid, meaning they have two sets of chromosomes-one set inherited from each parent. However, polyploidy is found in some organisms and is especially common in plants. In addition, polyploidy occurs in some tissues of animals that are otherwise diploid, such as human muscle tissues.[1] This is known as endopolyploidy. Species whose cells do not have nuclei, that is, Prokaryotes, may be polyploid organisms, as seen in the large bacterium Epulopiscium fishelsoni [1]. Hence ploidy is defined with respect to a cell. Most eukaryotes have diploid somatic cells, but produce haploid gametes (eggs and sperm) by meiosis. A monoploid has only one set of chromosomes, and the term is usually only applied to cells or organisms that are normally diploid. Male bees and other Hymenoptera, for example, are monoploid. Unlike animals, plants and ...
Citation: Pendinen, G., Gavrilenko, T., Jiang, J., Spooner, D.M. 2008. Evidence of Allopolyploid Speciation of Wild Tetraploid Mexican Species of Solanum Series Longipedicellata Obtained by In Situ Hybridization. Genome. 51(9):714-720. Interpretive Summary: Chromosomes are the structures in plant cells that contain the hereditary material called DNA. Polyploidy is a term referring to plants that have extra sets of chromosomes, and allopolyploidy refers to a plant having chromosomes obtained through the hybridization of different plant species. Some wild potato species are allopolyploid, and this study uses a technique called chromosome painting to examine the parents of allopolyploid Mexican potato species technically classified in Solanum series Longipedicellata. The results support prior ideas of the parents of these allopolyploid species being the diploid species S. verrucosum and the Mexican diploid species S. jamesii, or a species closely related to S. jamesii. The data are useful to potato ...
An allopolyploid is an individual having two or more complete sets of chromosomes derived from different species. Generation of allopolyploids might be rare because of the need to overcome limitations such as co-existing populations of parental lines, overcoming hybrid incompatibility, gametic non-reduction, and the requirement for chromosome doubling. However, allopolyploids are widely observed among plant species, so allopolyploids have succeeded in overcoming these limitations and may have a selective advantage. As techniques for making allopolyploids are developed, we can compare transcription, genome organization, and epigenetic modifications between synthesized allopolyploids and their direct parental lines or between several generations of allopolyploids. It has been suggested that divergence of transcription caused either genetically or epigenetically, which can contribute to plant phenotype, is important for the adaptation of allopolyploids.
Many plant species of agriculture importance are polyploid, having more than two copies of each chromosome per cell. In this paper, we describe statistical methods for genetic map construction in autopolyploid species with particular reference to the use of molecular markers. The first step is to determine the dosage of each DNA fragment (electrophoretic band) from its segregation ratio. Fragments present in a single dose can be used to construct framework maps for individual chromosomes. Fragments present in multiple doses can often be used to link the single chromosome maps into homologous groups and provide additional ordering information. Marker phenotype probabilities were calculated for pairs of markers arranged in different configurations among the homologous chromosomes. These probabilities were used to compute a maximum likelihood estimator of the recombination fraction between pairs of markers. A likelihood ratio test for linkage of multidose markers was derived. The information
Allopolyploidization (hybridization and whole-genome duplication) is a common phenomenon in plant evolution with immediate saltational effects on genome structure and gene expression. New technologies have allowed rapid progress over the past decade in our understanding of the consequences of allopolyploidy. A major question, raised by early pioneer of this field Leslie Gottlieb, concerned the extent to which gene expression differences among duplicate genes present in an allopolyploid are a legacy of expression differences that were already present in the progenitor diploid species. Addressing this question necessitates phylogenetically well-understood natural study systems, appropriate technology, availability of genomic resources and a suitable analytical framework, including a sufficiently detailed and generally accepted terminology. Here, we review these requirements and illustrate their application to a natural study system that Gottlieb worked on and recommended for this purpose: recent ...
The genus Nicotiana is ideally suited to study polyploidy because of its robust phylogenetic framework and the genus contains a large number of polyploid species (approx 40% are allopolyploids). Nicotiana attenuata is a diploid species which is thought to be involved in the formation of several of these allopolyploids, particularly in the formation of N. bigelovii and N. clevelandii (allotetraploid descendants of the ancestors of N. attenuata and N. trigonophylla). Our research focuses on understanding how the anti-herbivore defense system, as well as pollination, germination and growth systems modified after neo-polyploidization and polyploidy speciation, using synthetic and natural polyploids ...
Endopolyploidy (increased cell ploidy) occurs during normal development in many eukaryotes. In higher plants, endopolyploidy is usually the result of endoreduplication - endonuclear DNA replication that produces chromosomes with multivalent chromatids. According to the karyoplasmic ratio theory, a cells cytoplasmic volume is proportional to its nuclear DNA content. On p. 3817, Christian Chevalier and co-workers test this theory by analysing the structure of endoreduplicated nuclei in tomato fruit, which reach very high ploidy levels during their development. The researchers show that endopolyploidy in tomato pericarp (the fleshy part of the fruit) leads to the formation of polytene chromosomes. Pericarp nuclei, they report, have a complex structure in which numerous deep grooves are filled with mitochondria and in which there is a fairly constant ratio between nuclear surface area and the nuclear volume. Finally, they provide the first direct evidence that endoreduplication triggers enhanced ...
Historically, genetic maps in high-level autopolyploids have been constructed using only alleles present in one homolog, called single-dose or simplex markers (Wu et al. 1992; Sorrells 1992). In a full-sib population, these markers segregate in a 1:1 ratio (if they are present only in one parent), or in a 1:2:1 ratio (if present in both parents, also called double simplex). Given this level of simplification, it is possible to use the five-step procedure coupled with a standard software suitable for diploid populations. Nevertheless, it is well accepted that the use of single-dose markers imposes limitations on the construction of adequate genetic maps. These approaches sub-sample the genome (Hackett et al. 2013; Garcia et al. 2013), which precludes further consideration of multiallelic effects in models for QTL mapping and subsequent studies. Moreover, there is low statistical power to detect linkage when markers are in repulsion phase configurations (Wu et al. 1992; Ripol et al. 1999). ...
After aligning the sequences from all loci, (i) models of sequence evolution were determined for each locus. Gene trees were calculated for each locus with (ii) the sequences derived from the diploid taxa by Bayesian phylogenetic inference (BI), and (iii) sequences from all diploid plus, consecutively, single polyploid individuals were clustered by neighbor-joining analysis to determine phylogenetic affiliation (phasing) of the homoeologous gene copies found in polyploid taxa. Concatenated sequences from all loci (supermatrices) were used for BI of (iv) diploid and (v) diploid plus phased homoeologs of polyploid taxa. (vi) A MSC-based [multispecies coalescent] analysis was conducted to infer species trees from gene trees for the diploid individuals. (vii) To date nodes within the Hordeum phylogeny a molecular clock approach was conducted together with the MSC. (viii) A BCA [Bayesian concordance analysis] was conducted on the diploid taxa to estimate gene tree incongruences. Finally, (ix) ...
The induction of polyploidy is considered the reproductive end of cells, but there is evidence that polyploid giant cancer cells (PGCCs) contribute to cell repopulation during tumor relapse. However, the role of these cells in the development, progression and response to therapy in colon cancer remains undefined. Therefore, the main objective of this study was to investigate the generation of PGCCs in colon cancer cells and identify mechanisms of formation. Treatment of HCT-116 and Caco-2 colon cancer cells with the hypoxia mimic CoCl2 induced the formation of cells with larger cell and nuclear size (PGCCs), while the cells with normal morphology were selectively eliminated. Cytometric analysis showed that CoCl2 treatment induced G2 cell cycle arrest and the generation of a polyploid cell subpopulation with increased cellular DNA content. Polyploidy of hypoxia-induced PGCCs was confirmed by FISH analysis. Furthermore, CoCl2 treatment effectively induced the stabilization of HIF-1α, the differential
The data show a peak of N cells, composed of G M and tetraploid G cells, at a time corresponding towards the population doubling time from the respective cell line followed by a peak of N cells about doubling time later; immediately after which the quantity of polyploid cells decreased, accompanied by an increase while in the fraction of N cells that could be explained by cytokinesis of your polyploid, AZD HPQAtreated cells. Improve within the sub G fraction remained when diploid cells reappeared. We assessed regardless of whether endoreplicated cells maintained the ability to repopulate plaque monolayers. To enrich polyploid cells, H cells had been exposed to two consecutive h AZD HPQA solutions at ICclone separated by replating at lower density and h culture with no AZD HPQA. The first AZD HPQA exposure resulted in N and eN cells, along with the second in and N and eN cells, respectively. Radioresponsiveness of these cells was analyzed inside the plaque monolayer assay inside the absence of ...
Background Great gene figures in herb genomes reflect polyploidy and major gene duplication events. into paralogous protein families respectively. Singleton and paralogous family genes differed substantially in their likelihood of encoding a protein of known or putative function; 26% and Ritonavir 66% of singleton genes compared to 73% and 96% of the paralogous family genes encode a known or putative protein in rice and Arabidopsis respectively. Furthermore a major skew in the distribution of specific gene function was observed; a total of 17 Gene Ontology groups in both rice and Arabidopsis were statistically significant in their differential distribution between paralogous family and singleton proteins. In contrast to mammalian organisms we found that duplicated genes in rice and Arabidopsis tend to have more alternate splice forms. Using data from Massively Parallel Signature Sequencing we show that a significant portion of the duplicated genes in rice show divergent expression although a ...
Polyploidy is a condition in which an organism has more than two sets of chromosomes. It is found naturally in several types of...
BACKGROUND AIMS: One of the classic examples of an allopolyploid is Iris versicolor, Blue Flag (2n = 108), first studied by Edgar Anderson and later popularized by George Ledyard Stebbins in cytogenetics and evolutionary text-books. It is revisited here using modern molecular and cytogenetic tools to investigate its putative allopolyploid origin involving progenitors of I. virginica (2n = 70) and I. setosa (2n = 38). METHODS: Genomic in situ hybridization (GISH), fluorescent in situ hybridization (FISH) and Southern hybridization with 5S and 18-26S ribosomal DNA (rDNA) probes were used to identify the parental origin of chromosomes, and to study the unit structure, relative abundance and chromosomal location of rDNA sequences. KEY RESULTS: GISH shows that I. versicolor has inherited the sum of the chromosome complement from the two progenitor species. In I. versicolor all the 18-26S rDNA units and loci are inherited from the progenitor of I. virginica, those loci from the I. setosa progenitor ...
In this paper, we have presented a new algorithm for constructing a consensus MUL-tree(s) from a collection of MUL-trees, and illustrated its applicability using two examples. Both consisted of collections of gene trees that were constructed from sequence data of polyploid plants, including biparentally informative sequences. In both cases, we have also obtained networks that provide scenarios for how the plants evolved.. As a preprocessing procedure we provide a way to deal with the situation that some input trees might have missing or additional leaf labels. A key task in this context is to determine the multiset of labels that should appear in the consensus tree. The simplest possible approach would be to just take the union of the multisets over all input trees, that is, every label has the maximum multiplicity with which it occurs in an input tree. However, in practice we found that this tended to lead to an overestimation of the multiplicity of some labels, hence our use of a majority rule ...
Genomic and chromosomal instability has been suggested to participate in the progression of CML (6, 18-20). Defects in genome maintenance observed in cancer cells are usually a result of dysfunctions in cell cycle checkpoints and DNA repair. Here, we found that the Bcr-Abl impaired a SAC as well as a postmitotic checkpoint. Our data provide evidence that Bcr-Abl expression led to a substantial downregulation of the BRCA1 protein and decreased expression of the mitotic checkpoint components. Recent findings describe BRCA1 as one of the critical regulators of the spindle checkpoint in both mouse and human cells (9). In a model deficient for a full length of the Brca1 isoform, a number of genes involved in the spindle checkpoint regulation were decreased. BRCA1 knockdown in human prostate and breast cancer cells caused not only downregulation of genes implicated in the SAC but also centrosome malfunctioning, leading to aberrant mitoses (8, 21). Our data showing downregulation of mitotic genes ...
We and others have demonstrated that TIF1γ was a tumor suppressor (24, 27-29), whose mechanism of action has remained elusive. In this study, we demonstrated that stable Tif1γ inactivation resulted in SAC and postmitotic checkpoint attenuation, leading to the accumulation of severe chromosomal abnormalities. As a result, Tif1γ-inactivated cells present mitotic defects increasing their tumor aggressiveness in animal models. Finally, we observed that low TIF1γ expression was associated with increased CIN in different types of human tumors. Therefore, this work highlights an original mechanism by which TIF1γ behaves as a tumor suppressor through its role in the control of mitosis, whose impairment may represent a major tumor-suppressive process.. First of all, we revealed here that the immediate consequence of TIF1γ depletion in different cell types (primary and immortalized MEFs, transformed or immortalized epithelial cells) resulted in a proliferation arrest, mitotic blockade, accumulation ...
A cell nucleus containing four times the haploid number of chromosomes. Scientists have bred tetraploid plants in order to enhance specific qualities, s...
The workflow provides accurate analysis of polyploid organisms, copy number variations or gene dosage effects, giving you valuable insights into the contribution of specific genetic variances ...
Chapter 05: Principle of Inheritance and Variation of Biology Examplar Problems book - b. Form one linkage group c. Will not from any linkage groups d. Form interactive groups that affect the phenotype 2. Conditions of a karyotype 2n ± 1 and 2n ± 2 are called: a. Aneuploidy b. Polyploidy c. Allopolyploidy d. Monosomy 3. Distance between the genes and percentage of recombination shows: a. a direct ...
Polyploidy, the occurrence of more than two complete sets of chromosomes in a single nucleus, is an important process contributing to eukaryotic evolution. Polyploidy is also a widespread speciation mechanism and is common ...
The predominance of sexual reproduction despite its costs indicates that sex provides substantial benefits, which are usually thought to derive from the direct genetic consequences of recombination and syngamy. While genetic benefits of sex are certa
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Genotyping proved the expected parentage of all analyzed accessions of H. pallidiflorum and H. picroides and revealed that nearly all of them originated independently. Genome sizes and genome dosage largely corresponded to morphology, whereas the maternal origin of the allopolyploids had no discernable effect. Polyploid accessions of both parental species usually contained genetic material from other species. Given the phylogenetic distance of the parents, their chromosomes appeared only weakly differentiated in genomic in situ hybridization (GISH), as well as in overall comparisons of the repetitive fraction of their genomes. Furthermore, the repeatome of a phylogenetically more closely related species (H. umbellatum) differed significantly more ...
An increase in the copy number of the genome is common in plants and animals, occurring during the development of individuals. Polyploids have three or more complete sets of chromosomes in their nuclei instead of the two sets found in diploids. For example, in Arabidopsis, tissues of increasing age have an increase in polyploidy, reaching up to sixteen duplications ...
Describes a cell or organism which has more than the normal total number of chromosomes. For example, humans normally have 46 chromosomes per cell - but...
Isabelle Henry et al.s paper was accepted in Plant Cell! In this paper, they characterize a locus associated with regular meiosis in the allopolyploid Arabidopsis suecica (Sue). For the fan of Shel Silverstein and / or Johnny Cash out there, the locus is called "Boy named Sue"... May 28, 2013 ...
Looking for online definition of endopolyploid in the Medical Dictionary? endopolyploid explanation free. What is endopolyploid? Meaning of endopolyploid medical term. What does endopolyploid mean?
Hybridization coupled with whole-genome duplication (allopolyploidy) leads to a variety of genetic and epigenetic modifications in the resultant merged genomes. In particular, gene loss and gene silencing are commonly observed post-polyploidization. Here, we investigated DNA methylation as a potential mechanism for gene silencing in Tragopogon miscellus (Asteraceae), a recent and recurrently formed allopolyploid. This species, which also exhibits extensive gene loss, was formed from the diploids T. dubius and T. pratensis. Comparative bisulfite sequencing revealed CG methylation of parental homeologs for three loci (S2, S18 and TDF-44) that were previously identified as silenced in T. miscellus individuals relative to the diploid progenitors. One other locus (S3) examined did not show methylation, indicating that other transcriptional and post-transcriptional mechanisms are likely responsible for silencing that homeologous locus. These results indicate that Tragopogon miscellus allopolyploids employ
Development of genome-specific primers for homoeologous genes in allopolyploid species: the waxy and starch synthase II genes in allohexaploid wheat Triticum aestivum L. as examples. . 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.
A mutated clone with different ploidy levels in epidermis cells, 5/74/2, of the haploid `Kleiner Liebling` of Pelargonium zonale was investigated to answer the question that how the different ploidy levels were generated. Such a variability did not appear in L2- and L3-derived cells. Consequently, clone 5/74/2 is a periclinal cytochimera with a mixed ploidy epidermis. This type of cytochimera with different ploidy levels in epidermis has not been reported up to now. The epidermis of the blistered leaf or of the hairy leaf is polyploid with different ploidy levels, like the epidermis of the shoots with blistered and hairy leaves. Epidermis cells of normal shoots are diploid. The morphologically blistered leaf surface seems to be the result of a somatic variability in epidermis. Histological investigations of clone 5/74/2 showed two different ways of development of the somatic variability: the cells of the L1 in the apical meristem were already polyploid and the cells in the apical meristem were ...
Systematics/Phytogeography / Taxonomie/ Section. Beck, James [1], Windham, Michael [1], Pryer, Kathleen M. [2]. Investigating the early stages of polyploid evolution in the star-scaled cloak ferns (Astrolepis).. Polyploidy, or the presence of more than two chromosome sets per nucleus, is a pervasive historical and contemporary feature of plant evolution. Most authors view the majority of angiosperms and up to 95% of the approximately 11,000 species of ferns to be polyploid. Although tremendous advances have been made in our understanding of the phylogenetic scope and genomic consequences of polyploidy, we still know relatively little about the initial stages of polyploid evolution in natural populations. Of particular interest are the adaptive potentials of new polyploid lineages. Do new polyploids occupy the same habitats as their parental species (thus implying immediate competition), or are they projected into novel niches? Do independently derived polyploid lineages occupy different niches? ...
Tetraploid cells are detected in some precancerous lesions such as Barretts oesophagus and cervical dysplasia, where their presence coexists with the loss of functional p53 (Heselmeyer et al, 1996; Maley et al, 2004). Owing to the increase in the number of chromosomes, perhaps coupled to changes in the geometry of the mitotic machinery (Storchova et al, 2006; Storchova and Kuffer, 2008), tetraploid cells frequently activate the DNA damage response and become genomically unstable. Thus, tetraploidy may be considered as a metastable state that links normal diploidy to cancer‐associated aneuploidy (Storchova and Pellman, 2004; Fujiwara et al, 2005; Margolis, 2005).. Numerous tumour suppressor genes including p53 (Margolis, 2005), BRCA1 (Schlegel et al, 2003), LATS2 (Aylon et al, 2006) and APC (Tighe et al, 2004) actively repress tetraploidy, meaning that their removal can either stimulate the spontaneous tetraploidization of cells or facilitate the survival of tetraploid cells generated upon ...
As with many grasses, polyploidy is common in wheat.[9] There are two wild diploid (non-polyploid) wheats, T. boeoticum and T. urartu. T. boeoticum is the wild ancestor of domesticated einkorn, T. monococcum.[10] Cells of the diploid wheats each contain 2 complements of 7 chromosomes, one from the mother and one from the father (2n=2x=14, where 2n is the number of chromosomes in each somatic cell, and x is the basic chromosome number). The polyploid wheats are tetraploid (4 sets of chromosomes, 2n=4x=28), or hexaploid (6 sets of chromosomes, 2n=6x=42). The tetraploid wild wheats are wild emmer, T. dicoccoides, and T. araraticum. Wild emmer is the ancestor of all the domesticated tetraploid wheats, with one exception: T. araraticum is the wild ancestor of T. timopheevi.[11] There are no wild hexaploid wheats, although feral forms of common wheat are sometimes found. Hexaploid wheats developed under domestication. Genetic analysis has shown that the original hexaploid wheats were the result of a ...
Effects of polyploidisation on gene flow between natural populations are little known. Central European diploid and tetraploid populations of Arabidopsis arenosa and A. lyrata are here used to study interspecific and interploidal gene flow, using a combination of nuclear and plastid markers. Ploidal levels were confirmed by flow cytometry. Network analyses clearly separated diploids according to species. Tetraploids and diploids were highly intermingled within species, and some tetraploids intermingled with the other species, as well. Isolation with migration analyses suggested interspecific introgression from tetraploid A. arenosa to tetraploid A. lyrata and vice versa, and some interploidal gene flow, which was unidirectional from diploid to tetraploid in A. arenosa and bidirectional in A. lyrata. Interspecific genetic isolation at diploid level combined with introgression at tetraploid level indicates that polyploidy may buffer against negative consequences of interspecific hybridisation. The role of
One of the exciting opportunities stimulated by the convergence of modern genomic approaches with other areas of biology is that of resolving the enigmatic processes by which new phenotypes arise. Using a well-developed model system from the cotton genus (Gossypium) and multiple genomic resources, we are using comparative approaches combined with advanced population development to will reveal the steps and complexities involved in transforming primitive trichomes to the economically important fibers of modern cotton cultivars. Our goal is to understand the genetic causes and system-wide effects that underlie phenotypic change. An exciting dimension to our work is that it involves domestication at both the diploid and allopolyploid levels, permitting us to explore the possibility that polyploid formation created novel opportunities for phenotypic evolution. Also, because two different allopolyploid species were independently domesticated, we have an outstanding opportunity to evaluate ...
Knowledge of phylogenetic relationships among taxa is essential for comparative and evolutionary genomic research. Here, we report reconstruction of the phylogenetic tree of the genus Gossypium containing cultivated cottons of importance in agriculture by using variation of nuclear repetitive DNA sequences. Genomic DNA was isolated from 87 available accessions of 35 species representing all eight basic genome groups of the genus Gossypium and analyzed to infer phylogeny of the genus and genome origin of its polyploid species. Twenty-two interspersed repeated sequence clones derived from G. hirsutum, each representing a repeated sequence family, were hybridized to the genomic DNA of the 35 species, respectively. Southern hybridization showed that 15 of the repetitive DNA sequences could be detected in all of the eight diploid genome groups, five were A genome-specific, and two were detected in some of the non D-genome groups. A total of 642 major restriction bands of repeated sequences were used ...
Whole-cell catalysts overexpressing two enzymes for a double reduction cascade in which aliphatic α-branched α,β-unsaturated aldehydes are converted into Guerbet alcohols as a highly demanded class of lubricants were constructed and characterized. The reaction conditions were optimized to suppress by-product Enzyme catalysis in organic synthesis
The African clawed frogs (Silurana and Xenopus), model organisms for scientific inquiry, are unusual in that allopolyploidization has occurred on multiple occasions, giving rise to tetraploid, octoploid, and dodecaploid species. To better understand their evolution, here we estimate a mitochondrial DNA phylogeny from all described and some undescribed species. We examine the timing and location of diversification, and test hypotheses concerning the frequency of polyploid speciation and taxonomy. Using a relaxed molecular clock, we estimate that extant clawed frog lineages originated well after the breakup of Gondwana, about 63.7 million years ago, with a 95% confidence interval from 50.4 to 81.3 million years ago. Silurana and two major lineages of Xenopus have overlapping distributions in sub-Saharan Africa, and dispersal-vicariance analysis suggests that clawed frogs originated in central and/or eastern equatorial Africa. Most or all extant species originated before the Pleistocene; recent ...