The genetic continuity of the potato spindle tuber viroid (PSTVd) genome was analysed after infection of tomato plants with cloned cDNAs of parental strains. During the six weeks of the experiment, several new sequence variants appeared. The sequence variants detected in the progeny population induced sequence-specific disease symptoms. The PSTVd genome therefore follows the pattern expected for typical pseudo-strains propagating in plants as a population of similar sequences. Assessing further the replicon continuity, a PSTVd cDNA mutant with a deletion in the central conserved region was constructed and proven to be non-infectious. Surprisingly, in a sub-population of potato transformants expressing the same deleted PSTVd RNA an infectious viroid was detected. This suggests specific transcript conversion followed by recovery of the full-length pathogen genome ...
The 69 nucleotide left-terminal domain (T(L)) of the potato spindle tuber RNA viroid (PSTVd) constitutes one of its five structural elements. Due to a twofold complementary sequence repeat, two possible conformations are proposed for the T(L) secondary structure; an elongated-rod and a bifurcated form. In the present study, two T(L) mutants were designed that remove the symmetry of the sequence repeats and ensure that either the bifurcated or the elongated-rod conformation is thermodynamically favored. Imino 1H and 15N resonances were assigned for both mutants and the native T(L) domain based on 1H-1H NOESY and heteronuclear 1H-15N HSQC high-resolution NMR spectra. The NMR secondary structure analysis of all constructs establishes unambiguously the elongated-rod form as the secondary structure of the native T(L) domain. Temperature-gradient gel electrophoresis and UV melting experiments corroborate these results. A combined secondary structure and sequence analysis of T(L) domains of other ...
Viroid is small and exists less in host, which is difficult to purify. General method of purification is phenol extract, remove carbohydrate, dialysis, LiCl partition, DNase degradation and cellulose chromatography. The procedure is complicated, recovery ratio is less and the pure sample which is adapted to all kinds of use can t be gotten. A procedure for the separation and preparation of citrus exocortis viroid (CEV)is reported Nucleic acids were extracted from citrus leaves by phenolchloroform treament T...
Asian soybean rust (Phakopsora pachyrhizi), first described in Japan in 1902, is considered a major disease of soybean in tropical and subtropical regions. In susceptible varieties the fungus causes premature defoliation, early maturation, and significant reductions (up to 80%) in yield. This disease does not yet occur in North America.
Viroids are a unique class of noncoding RNAs: composed of only a circular, single-stranded molecule of 246-401 nt, they manage to replicate, move, circumvent host defenses, and frequently induce disease in higher plants. Viroids replicate through an RNA-to-RNA rolling-circle mechanism consisting of transcription of oligomeric viroid RNA intermediates, cleavage to unit-length strands, and circularization. Though the host RNA polymerase II (redirected to accept RNA templates) mediates RNA synthesis and a type-III RNase presumably cleavage of Potato spindle tuber viroid (PSTVd) and closely related members of the family Pospiviroidae, the host enzyme catalyzing the final circularization step, has remained elusive. In this study we propose that PSTVd subverts host DNA ligase 1, converting it to an RNA ligase, for the final step. To support this hypothesis, we show that the tomato (Solanum lycopersicum L.) DNA ligase 1 specifically and efficiently catalyzes circularization of the genuine PSTVd ...
Plant Disease 95:882.1-882.1...Plant Disease 95:882.1-882.1...First Report of Pear blister canker viroid in Pear Trees in Argentina...C. F. Nome and L. V. Difeo, Intituto Nacional de Tecnología Agropecuaria (INTA) - Instituto de Fitopatología y Fisiología Vegetal (IFFIVE), Cordoba, Argentina; A. Giayetto and M. Rossini, Intituto Nacional de Tecnología Agropecuaria (INTA) - Estación Experimental Agropecuaria, Alto Valle, Rio N...
Viroids are the smallest known agents of infectious disease. They consist of only an extremely small, circular, single-stranded ribonucleic acid (RNA) molecule and lack the protein coat of a virus. Viroids cause certain plant diseases, including potato spindle tuber disease, but it is uncertain whether viroids also occur in animal cells. Viroids appear to be transmitted mechanically from one cell to another through cellular debris. Viroids are of considerable interest because of their subviral nature…
Despite the non-coding nature of their small RNA genomes, the visible symptoms of viroid infection resemble those associated with many plant virus diseases. Recent evidence indicates that viroid-derived small RNAs acting through host RNA silencing pathways play a key role in viroid pathogenicity. Host responses to viroid infection are complex, involving signaling cascades containing host-encoded protein kinases and crosstalk between hormonal and defense-signaling pathways. Studies of viroid-host interaction in the context of entire biochemical or developmental pathways are just beginning, and many working hypotheses have yet to be critically tested.
Potato Leafroll Virus (PLRV) and Potato Spindle Tuber Viroid (PSTVd) are pathogenes which cause cultivars degeneratation and yield reduction of potato,and spread extensively. Previous researches indicated that the spreading of PLRV by aphids redounded to the propagation of PSTVd. Therefore, it is especially important for potato cultivars to resist PLRV and PSTVd together. An effective and economic method to cultivate virus-resistant potato cultivars could be by plant genetic engineering.In this research marker-free bivalent expression vector p3301-DR-Isir with RNAi structure of PLRV IS and di-component ribozyme specificly cleaving PSTVd RNA(-)was constructed successfully, which could be used as gene source to transform potato cultivars for high resistances to PLRV and PSTVd. | Plant health
Get information, facts, and pictures about Viroids at Encyclopedia.com. Make research projects and school reports about Viroids easy with credible articles from our FREE, online encyclopedia and dictionary.
PLANT MOLECULAR VIROLOGY GROUP. Activities:. The research topic of the group is molecular biology of the viroids. Viroids are the smallest RNA pathogens that infect the higher plants including some economically important crops. The non-coding viroid RNA genome supplies genetic information such as replicability, pathogenicity, mobility and host-specificity. It is assumed that the RNA sequence folds in a specific secondary structure that provides binding signals for host (protein) factors. It is further assumed that these factors exert in combination with the viroid RNA the genetic program of this RNA replicon. In this context the group is focused on molecular host-viroid interactions mediating viroid replication and movement in host plants and parasitic plants. A role of post-transcriptional gene silencing (PTGS) in viroid pathogenicity is currently under thorough investigation.. Recent projects:. National Science Fund DN06-6. POSTERS:. ...
Various tests are performed for the diagnosis of viruses and virus like organisms. These tests are classified into three categories namely the Biological assays, Serological assays and Molecular assays. Priority diseases are Citrus Tristeza Virus, Pepino Mosaic Virus, Tomato Yellow Leaf Curl Virus, Tomato Spotted Wilt Virus, Potato Spindle Tuber Viroid (PSTVd), Grapevine Flavescence Dorée and Plum Pox Virus. Identification is either done locally, or abroad, as necessary. Biological assays include mechanical transmission of viruses on specific herbaceous indicators. These are used for the confirmation of infection by quarantine pathogens. Serological assays involve mainly Double Antibody Sandwich - Enzyme Linked Immunosorbent Assay (DAS-ELISA) testing and Immunoprinting ELISA. Molecular assays include the use of Reverse Transcriptase - Polymerase Chain Reaction (RT-PCR).​ ...
Comparison of Tomato Bioassay and Slab Gel Electrophoresis for Detection of Potato Spindle Tuber Viroid in Potato. G. L. Schumann, H. D. Thurston, R. K. Horst, S. O. Kawamoto, and G. I. Nemoto. Pages 1256-1259. VIEW ABSTRACT , VIEW ARTICLE. ...
Hop stunt viroid (HSVd) infects a wide range of plants. In this study, we assembled de novo two HSVd genomes from the transcriptome of an apricot species. To examine HSVd variation in a single tree, we sequenced 70 HSVd genomes from unique apricot and plum trees and identified 11 HSVd variants. In addition, we analysed all known 572 HSVd sequences and identified 382 non-redundant HSVd variants. Ph ...
Virusoids are circular single-stranded RNAs dependent on plant viruses for replication and encapsidation. The genome of virusoids consist of several hundred nucleotides and does not code for any proteins. Virusoids are essentially viroids that have been encapsulated by a helper virus coat protein. They are thus similar to viroids in their means of replication (rolling circle replication), but they differ in that viroids do not possess a protein coat. Virusoids, while being studied in virology, are subviral particles rather than viruses. Since they depend on helper viruses, they are classified as satellites. In the virological taxonomy they appear as Satellites/Satellite nucleic acids/Subgroup 3: Circular satellite RNAs. The term virusoid is also sometimes used more generally to refer to all satellites. Symons RH (1991). "The intriguing viroids and virusoids: what is their information content and how did they evolve?" (PDF). Mol. Plant Microbe Interact. 4 (2): 111-21. doi:10.1094/MPMI-4-111. PMID ...
Pethybridge, Sarah J., Hay, Frank S., Barbara, Dez J., Eastwell, Kenneth C. and Wilson, Calum R. (2008) Viruses and viroids infecting hop : significance, epidemiology, and management. Plant Disease, Vol.92 (No.3). pp. 324-338. ISSN 0191-2917 ...
In the study published now in the journal RNA Biology, led by researchers from the Center for Astrobiology (CAB, CSIC-INTA), it has been used, as indicated by Miguel Moreno (researcher of the CAB and first signatory of the work) "a tool of nanotechnology that allows us to obtain 3D images of individual RNA molecules in native conditions and without the need to mark them or coat them with any substance, as we showed for a different biological system together with Luis Vázquez (from the ICMM) and other collaborators in a previous article: Atomic force microscopy (AFM) ". In this way, for the first time, the structure of three different viroids, PSTVd, and two species belonging to the Avsunviroidae family were able to be visualized and analyzed at nanoscale resolution: the viroid of the latent peach mosaic (PLMVd) and the latent viroid of the Eggplant (ELVd ...
How small RNAs are derived from pathogenic RNAs in plants remains to be fully understood. One of the main issues is the form of substrate RNAs for DCL activities. Although it is generally assumed that small RNAs of RNA viruses are derived from dsRNAs formed during replication, direct experimental evidence remains to be provided. The sequence profiles and strand polarities of small RNAs from several tested RNA viruses suggest that they are produced from structured regions of viral RNAs (59, 82).. A hairpin structure of PLMVd could be a substrate for DCL cleavage in wheat germ extract (44). Whether it also acted as an in vivo substrate for DCLs remains to be determined. We have obtained several lines of in vivo as well as in vitro evidence to suggest that srPSTVds are produced mostly from the secondary structure of PSTVd RNAs. First, sequence profiles showed that srPSTVds are predominantly plus strands and are clustered in the two terminal regions of the PSTVd secondary structure. Second, viral ...
EN] Viroids are infectious agents identified only in plants so far. In contrast to viruses, the genome of viroids is composed of a tiny circular RNA (250-400 nt) not coding for proteins, but containing in its compact ...
环形RNA研究历史1>最早的环形RNA分子在20世纪70年代于RNA病毒中发现。(Viroids are single-stranded covalently closed circular RNA molecules existing as highly base-paired rod-like structures) 2>2012年,斯坦福大学和霍华德休斯医学研究所的科学家们发表在
Characteristics of Viruses Minuscule, acellular infectious agent having either DNA or RNA Causes many infections of humans, animals, plants, and bacteria Causes most of the diseases that plague the industrialized world 10/15/11 MDufilho . 2
The sizes of plant viral genomes vary from about four kilo bases (kb) to about twenty kb. Exceptions are the phycodna viruses of algae whose DNAs are over three hundred kb. Virions may be roundish in shape (in actuality an intricate geometrical form called an icosahedron), rod-shaped, or filamentous ...
Author Summary Last year, we reported that circular RNA isoforms, previously thought to be very rare, are actually a pervasive feature of eukaryotic gene expression programs; indeed, the major RNA isoform from hundreds of human genes is a circle. Previous novel RNA species that initially appeared to be special cases, of dubious biological significance, have subsequently proved to have critical, conserved biological roles. An almost universal characteristic of regulatory macromolecules is that they are themselves regulated during development and differentiation. Here, we show that the repertoire of genes expressing circular RNA, the relative levels of circular: linear transcripts from each gene, and even the pattern of splice isoforms of circular RNAs from each gene were cell-type specific, including examples of striking regulation. In humans, we estimate that circular RNA may account for about 1% as many molecules as poly(A) RNA. The ubiquity of circular RNA and its specific regulation could
It is only a question of definition. You can set the boundaries between living things and not living things anywhere.. Some philosophers have argued that using a clear boundary between living and non-living things is not such a good solution. In nature, there would rather be a continuum from a stone to a bacteria.. It is true that in thinking of viruses such as Lausannevirus or Marseillevirus we might be willing to integrate them in the category of living things. These viruses are giant, and even can be parasitized by other viruses.. Viruses are made of proteins and contain nucleic acids (RNA or DNA). If you consider that they are alive, what would you say about viroids? A viroid is just a nucleic acid that is able to infect a host and cause the replication of itself. What about a prion? A prion is a protein that, roughly speaking, has the same consequences as that of a viroid.. I think (one should check the literature, I might be mistaken) that there is a species of parasitoid wasp that ...
Each metabolic step is catalyzed by a par- ticular enzyme, whose production is the responsibility of a single gene. A mutation in the gene alters the activity of the protein for which it is responsible. A modification in the hypothesis is needed to accommodate proteins that consist of more than one subunit. If the subunits are all the same, the protein is a homomultimer, repre- sented by a single gene. If the subunits are dif- ferent, the protein is a heteromultimer. Stated as a more general rule applicable to any het- eromultimeric protein, the one gene : one enzyme hypothesis becomes more precisely expressed as one gene: one polypeptide chain. Different isolates of a particular viroid strain vary from one another, and the change may affect the phenotype of infected cells. For exam- pIe, the mild and severe strains of PSTV differ by three nucleotide substitutions. Viroids resemble viruses in having herita- ble nucleic acid genomes. They fulfill the crite- ria for genetic information. Yet ...
The pervasive expression of circular RNA is a recently discovered feature of gene expression in highly diverged eukaryotes, but the functions of most circular RNAs are still unknown. Computational methods to discover and quantify circular RNA are essential. Moreover, discovering biological contexts where circular RNAs are regulated will shed light on potential functional roles they may play.We present a new algorithm that increases the sensitivity and specificity of circular RNA detection by discovering and quantifying circular and linear RNA splicing events at both annotated and un-annotated exon boundaries, including intergenic regions of the genome, with high statistical confidence. Unlike approaches that rely on read count and exon homology to determine confidence in prediction of circular RNA expression, our algorithm uses a statistical approach. Using our algorithm, we unveiled striking induction of general and tissue-specific circular RNAs, including in the heart and lung, during human ...
Satellites are subviral agents that differ from viroids because they depend on the presence of a helper virus for their propagation.
Read this full essay on Are Viruses, Prions and Viriods Alive?. In order to see where viruses, viroids and prions fit into the scheme of life, we need to kno...
About microscopic forms of life, including Bacteria, Archea, protozoans, algae and fungi. Topics relating to viruses, viroids and prions also belong here ...
About microscopic forms of life, including Bacteria, Archea, protozoans, algae and fungi. Topics relating to viruses, viroids and prions also belong here ...
Scientists at the Lewis Katz School of Medicine at Temple University and colleagues describe a circular RNA that fills a critical role in tissue repair after a heart attack, due to its ability to bind harmful molecules, including microRNAs and proteins.
Zaghlool A, Ameur A, Wu C, Westholm JO, Niazi A, Manivannan M, Bramlett K, Nilsson M, Feuk L Sci Rep 8 (1) 16953 [2018-11-16; online 2018-11-16] Circular RNAs (circRNAs) were recently discovered as a class of widely expressed noncoding RNA and have been implicated in regulation of gene expression. However, the function of the majority of circRNAs remains unknown. Studies of circRNAs have been hampered by a lack of essential approaches for detection, quantification and visualization. We therefore developed a target-enrichment sequencing method suitable for screening of circRNAs and their linear counterparts in large number of samples. We also applied padlock probes and in situ sequencing to visualize and determine circRNA localization in human brain tissue at subcellular levels. We measured circRNA abundance across different human samples and tissues. Our results highlight the potential of this RNA class to act as a specific diagnostic marker in blood and serum, by detection of circRNAs from ...
What is the difference between Alpha helix and Beta Pleated Sheet? Alpha Helix is a right-handed coiled rod-like structure. Beta pleated sheet is a sheet-
Get the latest avocado sunblotch viroid test news on agriculture-xprt.com, the worlds largest agricultural industry marketplace and information resource.
The viroid can be purified from infected avocado leaves by a procedure described for the purification of chrysanthemum stunt viroid from chrysanthemum leaves (Palukaitis & Symons, 1980). The method involves the initial preparation of a partially purified nucleic acid extract containing mostly low M. Wt RNA and DNA, followed by electrophoresis of this extract in polyacrylamide slab gels under non-denaturing conditions. The viroid band, located by staining, is eluted electrophoretically from the gel and further purified by electrophoresis in polyacrylamide slab gels under denaturing conditions (7 M urea); circular viroid molecules are separated from linear ones at this stage. Highly purified circular and linear viroid molecules are eluted electrophoretically from the gel. Residual contaminating polyacrylamide can be removed by sedimentation of the viroid in a sucrose gradient (Palukaitis et al., 1981). Circular viroid molecules purified by this method are infective (Allen, Palukaitis & Symons, ...
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Circular RNA (or circRNA) is a type of RNA which, unlike the better known linear RNA, forms a covalently closed continuous loop, i.e., in circular RNA the 3 and 5 ends normally present in an RNA molecule have been joined together. This feature confers numerous properties to circular RNAs, many of which have only recently been identified. Many circular RNAs arise from otherwise protein-coding genes. They have been categorized as noncoding RNA, but more recently, they have been shown to code for proteins. Some circular RNAs have recently shown potential as gene regulators. Like many other alternative noncoding isoforms, the biological function of most circular RNAs are unclear. Because circular RNAs do not have 5 or 3 ends, they are resistant to exonuclease-mediated degradation and are presumably more stable than most linear RNAs in cells. In contrast to genes in bacteria, eukaryotic genes are split by non-coding sequences known as introns. In eukaryotes, as a gene is transcribed from DNA into ...
Control of microorganisms by physical and chemical agents frequently used terms Sterilization: the process by which all living cells, viable spores, virus, and viroids are either destroyed or removed from an object or habitat. Disinfection: the killing, inhibition, or removal of microorganisms that may cause disease. Sanitization: the microbial population is reduced to levels that are considered safe by public health standards. Antisepsis: the prevention of infection or sepsis -cide: kill; -static: stop germicide: kill pathogens but not necessarily endospores. Bactericide; fungicide; algicide; viricide; bacteriostatic; fungistatic
Athena, Greek Goddess of Wisdom, is a soft yellow semi solid/tonal yarn with darker golden yellow speckles spread throughout. A piece of the Mythical Gods Collection, Athena, works well in a variety of projects and patterns from cables and lace to colorwork and plain stitching. The versatility of
Larry Hale (lhale at UPEI.CA) wrote: : Greetings. : I would like to thank those people who responded to my post concerning : microsatellite oligos back in June. : I am also interested in detection of DNA fragments by silver staining. : Nothing fancy, just 1000-100 bp on a simple polyacrylamide gel. Can anyone : suggest a good kit, or a good published protocol? A procedure for silver staining of RNA and DNA in PAA gels (originating from the protein staining procedure) is described in: Schumacher et al. (1986) Diagnostic procedure for detection of viroids and viruses with circular RNAs by return-gel electrophoresis J. Phytopathology 115, 332-343 May seem somewhat dated, but this procedure is still in use in our lab, amounts of less than 1 ng nucleic acids can be detected. : Thanks again, Larry Hale (LHALE at UPEI.CA) Michael Schmitz Biophysics Dept, University of Duesseldorf FRG ...
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The majority of crop plant constructions for herbicide or disease resistance employ a Promoter from cauliflower mosaic virus (CaMV). Regardless of the gene transferred, all transfers require a promoter, which is like a motor driving production of the genes message. Without a promoter, the gene is inactive, but replicated, CaMV is used because it is a powerful motor which drives replication of the retrovirus and is active in both angiosperms and gymnosperms. The CaMV pararetrovirus replication cycle involves production vegetative virus containing RNA which is reverse transcribed to make DNA similar to HIV, Human Leukemia Virus and Human hepatitis B. (Bonneville et al. RNA Genetics Vo.11, Retroviruses, Viroids and RNA Recombination pp. 23-42, 1988). CaMV is closely related to hepatitis B and is closely related to HIV (Doolittle et al. Quart.Rev.Biol. 64,2, 1989; Xiong and Eickbush, EMBO Joumal 9, 3353, 1990). The CaMV promoter is preferred above other potential promoters because it is a more ...
The World Health Organizations (WHO) International Classification of Diseases (ICD) is used in clinical fields to classify diseases and monitor morbidity (the number of cases of a disease) and mortality (the number of deaths due to a disease). In this section, we will introduce terminology used by the ICD (and in health-care professions in general) to describe and categorize various types of disease.. An infectious disease is any disease caused by the direct effect of a pathogen. A pathogen may be cellular (bacteria, parasites, and fungi) or acellular (viruses, viroids, and prions). Some infectious diseases are also communicable, meaning they are capable of being spread from person to person through either direct or indirect mechanisms. Some infectious communicable diseases are also considered contagious diseases, meaning they are easily spread from person to person. Not all contagious diseases are equally so; the degree to which a disease is contagious usually depends on how the pathogen is ...
Until now, the molecule has been considered "non coding" to make vital proteins for performing regulatory functions in the body, but, in fact, was found to, indeed, be coding.
Arraystar is launching the Rat CircRNA Microarray to empower circRNA expression profiling in rats as an important model organism. 14,145 circRNAs with stringent experimental support are curated from the most recent publications.
هدف: اخیراً سنتز سبز نانوذرات نقره از طریق گیاهان، قارچ، باکتری‌ها و جلبک‌ها انجام می‌گیرد؛ به‌دلیل اینکه روشی ساده، کم هزینه و سازگار با محیط زیست است و می‌تواند جایگزین مناسب برای روش‌های فیزیکی و شیمیایی باشد. در این مطالعه سنتز سبز نانوذرات نقره به‌وسیله عصاره قارچ دنبلان و ارزیابی سمیت سلولی آن توسط MTT گزارش شده است. مواد و روش‌ها: در این تحقیق از عصاره قارچ دنبلان به‌عنوان عامل کاهنده برای تولید زیستی نانوذرات نقره استفاده شد. نانوذرات حاصل برای تعیین اندازه، خواص ساختاری، خواص اپتیکی، ریخت‌شناسی به‌ترتیب با دستگاه‌های طیف‌سنجی مادون قرمز،
Deteksi dan Identifikasi Chrysanthemum Stunt Viroid pada Tanaman Krisan Menggunakan Teknik Reverse Transcriptase Polymerase Chain Reaction (Detection and Identification of Chrysanthemum Stunt Viroid on Chrysanthemum Using Reverse Transcriptase Polymerase
Weed plants characteristic for potato and hop fields have not been considered in the past as potential hosts that could transmit and lead to spreading of potato spindle tuber (PSTVd) and hop stunt (HSVd) viroids, respectively. To gain insight into this problem, we biolistically inoculated these weed plants with viroid populations either as RNA or as cDNA. New potential viroid host species, collected in central Europe, were discovered. From 12 weed species characteristic for potato fields, high viroid levels, detectable by molecular hybridization, were maintained after both RNA and DNA transfers in Chamomilla reculita and Anthemis arvensis. Low viroid levels, detectable by reverse transcription-PCR (RT-PCR) only, were maintained after plant inoculations with cDNA in Veronica argensis and Amaranthus retroflexus. In these two species PSTVd concentrations were 105 and 103 times, respectively, lower than in tomato as estimated by real-time PCR. From 14 weeds characteristic for hop fields, high HSVd ...
With its design, the Subviral RNA Database could be considered as a fundamental building block for the study of these related RNAs. It is freely available via a web browser at the URL: http://subviral.med.uottawa.ca.
Boiko, A.L.; Litvinov, G.S.; Romashev, S.A., 1984: Viroid causing stunt deformity of hop plants in biocenoses of the Ukrainian SSR