No abstract

The reverse transcription-polymerase chain reaction (RT-PCR) technique was used for detection of prunus necrotic ringspot virus in dormant peach trees which tested negative by ELISA. Total RNA extracted from bark tissue, using a lithium chloride based method, were used for reverse transcription and subsequent amplification of viral sequences. The PCR product, about 300 base pairs in size, was analyzed by gel electrophoresis and visualized by ethidium bromide staining. In some cases, PCR products were not clearly visible in the stained gel and became distinct only following hybridisation with a 32p-labelled virus specific probe. The RT-PCR assay described in this paper is sensitive enough for detection of PNRSV in dormant woody bark tissue and could be incorporated into testing protocols during post-entry quarantines for rapid initial screening of imported budwood and in virus elimination programs.

Plum pox virus (PPV) was detected in wild apricot and cultivated plum maintained in a germ plasm collection in Kazakhstan. Both isolates were typed as D strain, with no evidence of recombination. The virus was detected by triple-antibody sandwich enzyme-linked immunosorbent assay (ELISA) utilizing the universal PPV-specific monoclonal antibody (MAb) 5B as the secondary antibody, and by reverse-transcription polymerase chain reaction (RT-PCR) assay using primers that amplified a 243-bp fragment in the C-terminus of the coat protein (CP) coding region. Immunocapture (IC) RT-PCR was used to detect PPV in nine wild apricot accessions, including eight ELISA-negative and one ELISA-positive. The plum and apricot isolates reacted positively in Western blot assay with the universal MAb 5B, and negatively with the strain-M-specific MAb-AL. Restriction fragment length polymorphism analysis applied to the amplified 243-bp fragment showed that restriction sites for AluI and RsaI were present in the were present in the plum and apricot samples. An amplified 836-bp cDNA fragment derived from the P3-6K1 coding region of both isolates had restriction profiles typical for strain D. Nucleotide identities of 99 to 100% were observed for the 243-bp fragments of the Kazakhstan isolates when compared with the corresponding regions of strain D, and 94 to 95% identity with strain M. Nucleotide sequence analysis of the entire CP coding region of the plum and apricotisolates resulted in the identification of a unique deletion of six nucleotides (two deduced proline amino acid residues) in the N-terminal region in the plum isolate. This is the first deletion of this nature observed among PPV isolates. The DAG motif was present in both isolates. Several nucleotide substitutions in the CP coding region were common to the plum and apricot isolates and appear to be unique to the Kazakstan isolates. This suggests a close relationship between the isolates.

Numerous studies have implicated DTNBP1, the gene encoding dystrobrevin-binding protein or dysbindin, as a candidate risk gene for schizophrenia, though this relationship remains somewhat controversial. Variation in dysbindin, and its location on chromosome 6p, has been associated with cognitive processes, including those relying on a complex system of glutamatergic and dopaminergic interactions. Dysbindin is one of the seven protein subunits that comprise the biogenesis of lysosome-related organelles complex 1 (BLOC-1). Dysbindin protein levels are lower in mice with null mutations in pallidin, another gene in the BLOC-1, and pallidin levels are lower in mice with null mutations in the dysbindin gene, suggesting that multiple subunit proteins must be present to form a functional oligomeric complex. Furthermore, pallidin and dysbindin have similar distribution patterns in a mouse and human brain. Here, we investigated whether the apparent correspondence of pallid and dysbindin at the level of gene expression is also found at the level of behavior. Hypothesizing a mutation leading to underexpression of either of these proteins should show similar phenotypic effects, we studied recognition memory in both strains using the novel object recognition task (NORT) and social novelty recognition task (SNRT). We found that mice with a null mutation in either gene are impaired on SNRT and NORT when compared with wild-type controls. These results support the conclusion that deficits consistent with recognition memory impairment, a cognitive function that is impaired in schizophrenia, result from either pallidin or dysbindin mutations, possibly through degradation of BLOC-1 expression and/or function.

The polymerase chain reaction (PCR) method was reliably used for detection of potato leafroll virus (PLRV) RNA in dormant tubers from field-grown plants and in vitro-propagated microtubers. A simple RNA extraction from tuber and microtuber tissue allowed reverse transcription and PCR amplification of viral sequences. It was also demonstrated that ELISA could be used reliably for detection of PLRV in crude sap extracts of dormant microtubers produced in vitro but not in tubers from field-grown plants.