Structure and distribution of Astakine in the organs of the freshwater snail Pomacea canaliculata.

The freshwater snail Pomacea canaliculata is an emerging pest in EU, and its immune system is a potential target for developing strategies of pest control. Circulating hemocytes represent the cellular component of the P. canaliculata immune system. P. canaliculata hemocytes originate in the pericardial fluid, and are maintained in the ampulla, which may act as a hemocyte reservoir. Astakine-1 is a hematopoietic cytokine first described in the crayfish Pacifastacus leniusculus, and recently described also in the insect Lygus lineolaris and in 51 the bivalve mollusc Crassostrea gigas. Bioinformatic analyses of a comprehensive P. canaliculata transcriptome demonstrated the presence of an Astakine 1-like molecule (Pc-Astakine) also in this organism. Pc-Astakine is 121 aa and contains a domain characterized by 8 cysteins with a conserved distribution pattern homologous to the vertebrate domain prokineticin. Further bioinformatic predictions suggest that the structure of Pc-Astakine may be similar to that one of P. leniusculus Astakine-1. The distribution of Pc-astakine gene expression was evaluated by qPCR. We have observed that all organs analyzed express Pcastakine at detectable levels. However, high expression levels were detected in the ampulla, pericardial fluid and circulating hemocytes. The data suggest that Pc-Astakine may have a wide range of functions, including the regulation of hematopoiesis and the modulation of inflammatory responses, as previously reported for the human Prokineticin-1.