Cloning and expression patterns of the brine shrimp (Artemia sinica) glycogen phosphorylase (GPase) gene during development and in response to temperature stress

Glycogen serves as a metabolic reserve and is involved in macromolecular synthesis. Glycogen phosphorylase (GPase) is a key enzyme involved in intracellular glycogen catabolism, catalyzing the first step in glycogen degradation. In the diapause, GPase catalyzes glycogen into the closely related molecule, sorbitol. In this study, the full-length cDNA of the GPase gene (2,790 bp) was isolated from Artemia sinica for the first time by rapid amplification of cDNA ends technology. The GPase gene encoded a protein of 853 amino acids belonging to the Glycosyltransferase GTB type superfamily. The expression pattern and location of GPase were investigated at various stages during the embryonic development of A. sinica using real-time PCR and in situ hybridization. High GPase expression was detected at the 0 and 5 h stages. Subsequently, expression declined and was maintained at a low level during the stages from 10 to 40 h following by a small increase at day 3. Expression was downregulated at temperatures ranging from 25 to 20 °C and was subsequently upregulated in the range 15–5 °C. In situ hybridization assays showed wide distribution of the GPase gene during different developmental stages. From the results of this study, we conclude that the GPase gene expression is stress-related and might play an important role in Artemia development and metabolism.