Ticks are obligate hematophagous ectoparasites with a life cycle characterized by a period of starvation; many ticks spend more than 95 % of their life off the host. Autophagy, which is the process of bulk cytoplasmic degradation in eukaryotic cells, is induced by starvation and is essential for extension of the lifespan. Therefore, we hypothesized that autophagy also occurs in ticks; however, there has been no report on autophagy-related (
ATG) genes in ticks. Here, we show the homologue of an
ATG gene,
ATG12, and its expression pattern from the nympal to adult stages in the three-host tick
Haemaphysalis longicornis. The sequence analysis showed that
H. longicornis ATG12 (
HlATG12) cDNA is
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, has a
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ORF coding for a 136-amino acid polypeptide with the carboxy-terminal glycine residue, and has a predicted molecular mass of
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. Moreover, RT-PCR revealed that
HlATG12 was downregulated at the beginning of feeding, upregulated after engorgement, and downregulated again after molting. The expression level of
HlATG12 was highest at 3 months after engorgement. By immuno-electron microscopy, it was demonstrated that HlAtg12 was localized to the region around granule-like structures within midgut cells of unfed adults. In conclusion,
HlATG12 might function during unfed and molting stages.
