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Publikationen - Molekulare Signalverarbeitung

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Publikation

Iglesias, N. G.; Gago-Zachert, S. P.; Robledo, G.; Costa, N.; Plata, M. I.; Vera, O.; Grau, O.; Semorile, L. C.; Population structure of Citrus tristeza virus from field Argentinean isolates Virus Genes 36, 199-207, (2008) DOI: 10.1007/s11262-007-0169-x

We studied the genetic variability of three genomic regions (p23, p25 and p27 genes) from 11 field Citrus tristeza virus isolates from the two main citrus growing areas of Argentina, a country where the most efficient vector of the virus, Toxoptera citricida, is present for decades. The pathogenicity of the isolates was determinated by biological indexing, single-strand conformation polymorphism analysis showed that most isolates contained high intra-isolate variability. Divergent sequence variants were detected in some isolates, suggesting re-infections of the field plants. Phylogenetic analysis of the predominant sequence variants of each isolate revealed similar grouping of isolates for genes p25 and p27. The analysis of p23 showed two groups contained the severe isolates. Our results showed a high intra-isolate sequence variability suggesting that re-infections could contribute to the observed variability and that the host can play an important role in the selection of the sequence variants present in these isolates.
Bücher und Buchkapitel

Vaira, A. M.; Acotto, G. P.; Gago-Zachert, S.; Garcia, M. L.; Grau, O.; Milne, R. G.; Morikawa, T.; Natsuaki, T.; Torov, V.; Verbeek, M.; Vetten, H. J.; Genus Ophiovirus 673-679, (2005) ISBN: 9780080575483 DOI: 10.1016/B978-0-12-249951-7.50014-6

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Publikation

Naum-Onganı́a, G.; Gago-Zachert, S.; Peña, E.; Grau, O.; Laura Garcia, M.; Citrus psorosis virus RNA 1 is of negative polarity and potentially encodes in its complementary strand a 24K protein of unknown function and 280K putative RNA dependent RNA polymerase Virus Res. 96, 49-61, (2003) DOI: 10.1016/S0168-1702(03)00172-2

Citrus psorosis virus (CPsV), the type member of genus Ophiovirus, has three genomic RNAs. Complete sequencing of CPsV RNA 1 revealed a size of 8184 nucleotides and Northern blot hybridization with chain specific probes showed that its non-coding strand is preferentially encapsidated. The complementary strand of RNA 1 contains two open reading frames (ORFs) separated by a 109-nt intergenic region, one located near the 5′-end potentially encoding a 24K protein of unknown function, and another of 280K containing the core polymerase motifs characteristic of viral RNA-dependent RNA polymerases (RdRp). Comparison of the core RdRp motifs of negative-stranded RNA viruses, supports grouping CPsV, Ranunculus white mottle virus (RWMV) and Mirafiori lettuce virus (MiLV) within the same genus (Ophiovirus), constituting a monophyletic group separated from all other negative-stranded RNA viruses. Furthermore, RNAs 1 of MiLV, CPsV and RWMV are similar in size and those of MiLV and CPsV also in genomic organization and sequence.
Publikation

Gago-Zachert, S.; Costa, N.; Semorile, L.; Grau, O.; Sequence variability in p27 gene of Citrus Tristeza Virus (CTV) revealed by SSCP analysis Electron. J. Biotechnol. 2, 41-50, (1999) DOI: 10.2225/vol2-issue1-fulltext-3

Citrus tristeza closterovirus (CTV), is a phloem-limited virus transmitted by aphids in a semipersistent manner. The genome of CTV is composed of a ssRNA with two capsid proteins: CP, covering about 95% of the particle length, and a diverged coat protein (dCP), present only in one end of the particle, forming a rattlesnake structure. dCP is the product of p27 gene for which it is also postulated a function in the transmissibility by aphid vectors. Hybridization analysis showed a p27 gene region, which exhibits different patterns with two probes derived from two biological distinct CTV isolates. In an attempt to screen whether that gene region differs in mild and severe strains, six CTV isolates belonging to different biogroups were compared for variations in their p27 gene by analysis of single-strand conformation polymorphism (SSCP). The p27 gene was reverse transcribed and amplified by PCR and thirty clones of each isolate were obtained. From each clone, two fragments of the gene were amplified by PCR: fragment (a), 459 bp long, and fragment (b), 281 bp long. Sequence variations in both gene fragments were studied by SSCP analysis. A variety of SSCP patterns was obtained from each isolate, being isolates belonging to the groups II-IV and III those with the higher and lower number of them. Moreover, SSCP analysis provided a rapid procedure to screen the genetic heterogeneity of the viral isolates reducing considerably the amount of nucleic acid sequenciation necessary to gain that knowledge.
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