Multiple vitellogenins from the Haemaphysalis longicornis tick are crucial for ovarian development

Ovarian development and egg maturation are crucial processes for the success of reproduction in ticks. Three full-length cDNAs encoding the precursor of major yolk protein, vitellogenin, were obtained from cDNA libraries of the Haemaphysalis longicornis tick and designated as HIVg-1, HIVg-2 and HIVg-3. The HIVg mRNAs were found in fed females with major expression sites in the midgut, fat body and ovary. Native PAGE and Western blot demonstrated that HIVgs in the hemolymph, fat body and ovary of fed females consisted of four major polypeptides. RNAi results showed that HIVg dsRNA-injected ticks obtained lower body weight, egg weight and showed higher mortality of engorged females after blood sucking than control groups. Our results indicate that all HIVgs are essential for egg development and oviposition. (C) 2010 Elsevier Ltd. All rights reserved.