Leucine aminopeptidase in the ixodid tick Haemaphysalis longicornis: endogenous expression profiles in midgut.

We previously identified a cDNA from the ixodid tick Haemaphysalis longicornis that encodes leucine aminopeptidase, HlLAP. Functionally, recombinant HlLAP effectively hydrolyzed synthetic amino acid derivatives. Here, we investigated the temporal expression profiles of midgut HlLAP in adult H. longicornis parthenogenetic ticks from the starting of blood feeding until just before the onset of oviposition. Midgut HlLAP transcript expression level was higher during post-engorgement period than that during feeding period. Endogenous HlLAP in the midgut was also observed with higher expression level during post-engorgement period. Histological localization of HlLAP was in the cytosol of midgut epithelial cells, notably the newly differentiated basophilic cells at post-engorgement. Our data suggested that HlLAP was dominantly localized in basophilic cells, where it may play regulatory roles in protein biosynthesis and degradation.