No abstract

Southern rice black-streaked dwarf virus (SRBSDV), a new member of the genus Fijivirus, is a double-stranded RNA virus known to lack poly(A) tails. We now showed that some of SRBSDV mRNAs were indeed polyadenylated at the 3' terminus in plant hosts, and investigated the nature of 3' poly(A) tails. The non-abundant presence of SRBSDV mRNAs bearing polyadenylate tails suggested that these viral RNA were subjected to polyadenylation-stimulated degradation. The discovery of poly(A) tails in different families of viruses implies potentially a wide occurrence of the polyadenylation-assisted RNA degradation in viruses.

Acetylcholinesterase (AChE) is the molecular target of organophosphate (OP) and carbamate (CB) insecticides. The white-backed planthopper, Sogatella furcifera (Horváth, 1899), is a notorious rice pest in Asia and exhibits high resistance against a specific OP pesticide known as chlorpyrifos. To date, there has not yet been a study on the molecular mechanisms that confer resistance to this pesticide in S. furcifera. In this study, we cloned the full-length cDNA of AChE type 1 and type 2 genes from S. furcifera (SfAChE1 and SfAChE2). Both genes appear to be functional and are composed of the classic AChE domains. An analysis of the gene family revealed that SfAChE1 and SfAChE2 cluster into in the insect AChE1 and AChE2 clades, respectively. We first performed qPCR experiments to detect AChE expression patterns in distinct developmental stages and tissues. Our results revealed that SfAChE1 is more highly expressed than SfAChE2. Both genes were most highly expressed during the first instar nymph stage, and then expressed at a decreasing rate until the end of the fifth instar nymph stage. Both SfAChE1 and SfAChE2 were more highly expressed than in other tested tissues. Furthermore, we investigated the association between AChE genes and chlorpyrifos resistance and found that Nanjing (NJ-R) is a chlorpyrifos-resistant strain with high frequencies of a Ser298Pro mutation in SfAChE1. Conversely, the chlorpyrifos-susceptible Guangdong (GD-S) strain did not carry this mutation.