Molecular characterization and expression of vitellogenin genes from the wolf spider Pardosa pseudoannulata (Araneae: Lycosidae)

The wolf spider Pardosa pseudoannulata (Araneae: Lycosidae) is an important biological control agent against rice pests in the paddy ecosystem. Vitellogenin (Vg) is the precursor of the yolk protein and is crucial for reproduction in P. pseudoannulata. We have identified three full-length cDNAs encoding vitellogenins. The PpVg1 transcript is 5598 bp long, with an open reading frame (ORF) of 5379 bp encoding a 1792 amino acid protein. The PpVg2 transcript is 5394 bp long, with an ORF of 5205 bp encoding a 1734 amino acid protein. The PpVg3 transcript is 5229 bp long, with an ORF of a 5019 bp encoding a 1672 amino acid protein. Typical domains are found in all PpVgs sequences, including an N-terminal lipoprotein domain, a DUF1943 domain and the von Willebrand factor type D domain. Phylogenetic analysis indicates that PpVg1, PpVg2 and PpVg3 are grouped with other arachnid Vgs. PpVg1 and PpVg2 are more closely related to Parasteatoda tepidariorum vitellogenin, whereas PpVg3 is segregated into a single clade in the arachnid group. Expression analysis by a quantitative reverse transcriptase-polymerase chain reaction shows that PpVg1, PpVg2 and PpVg3 are mainly expressed in adult females. Mating elicite an increase in the transcription levels of PpVg1 and PpVg2, and the expression level of PpVg3 is up-regulated after first oviposition. The present study represents the first report with respect to the molecular characterization and expression patterns for the spider vitellogenin and will greatly facilitate our understanding of the molecular mechanisms of P. pseudoannulata reproduction.