Cloning and Interspecific Altered Expression of TPS Gene in Two Invasive Apple Snails, Pomacea canaliculata and Pomacea maculata (Gastropoda: Ampullariidae), Under Different Temperature

摘要

Studies have demonstrated differences in temperature tolerance between two Pomacea species, Pomacea canaliculata and Pomacea maculata. To determine whether the trehalose-6-phosphate synthase (TPS) genes in the two species exhibited different expression profiles at different temperatures, we cloned the full-length cDNA of TPS in the two Pomacea species and analyzed the expression profile of TPS across a temperature gradient through real-time quantitative analysis. The TPS gene of both P. canaliculata (denoted by PcTPS) and P. maculata (denoted by PmTPS) contained 1908 bp and 1914 ORFs encoding 635 and 637 amino acids, respectively. The genes have a classical polyadenylation signal sequence AATAAA and poly(A), as well as two highly conserved motifs of the TPS protein family in deduced amino-acid sequences. Across the temperature gradient (from 3°C to 42°C), the onset temperature (Ton) or maximal temperature (Tmax) for inducing TPS expression in P. maculata was 3°C lower than that in P. canaliculata, and Ton was highly consistent with the upper temperature limits of the range of the two Pomacea species. All results revealed that the cloned genes were inducible TPS gene. Moreover, in terms of gene-expression level, P. maculata was more susceptible to cold temperature than P. canaliculata. The Ton (or Tmax) of TPS could represent the differences in temperature tolerance of the two Pomacea species. The study also provided useful molecular information on the ecological adaptability of invasive apple snails against extreme environmental stress.