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Glycolytic regulation in aestivation of the sea cucumber Apostichopus japonicus: evidence from metabolite quantification and rate-limiting enzyme analyses

Xiang, Xiaowei, Chen, Muyan, Wu, Changwen, Zhu, Aiyi, Yang, Jingwen, Lv, Zhenming, Wang, Tianming
Marine biology 2016 v.163 no.8 pp. 167
Apostichopus japonicus, adults, animals, dormancy, enzyme activity, estivation, gene expression, glucose, glycolysis, hexokinase, intestines, metabolites, muscles, nucleotide sequences, pyruvate kinase, pyruvic acid, summer, temperature, tissues, transcription (genetics), trees
Aestivation is a state of dormancy in diverse animal species characterized by a depressed metabolism. High temperatures in the summer trigger aestivation in the adult sea cucumber, Apostichopus japonicus. In the present study, the glycolytic suppression in aestivating A. japonicus was verified by metabolite quantification and activity and a gene expression analysis of rate-limiting enzymes (hexokinase and pyruvate kinase). Significant decreases in glucose concentrations were discovered in the respiration tree (p < 0.01), intestine (p < 0.05) and muscle (p < 0.01) of aestivating A. japonicus; likewise, over this period, pyruvic acid concentrations significantly decreased in the respiration tree (p < 0.05) and intestine (p < 0.01), but were unchanged in muscle. Enzymatic activity variation of hexokinase (Aj-HK) and pyruvate kinase (Aj-PK) in aestivating A. japonicus revealed that Aj-HK remained at high levels in the respiration tree and muscle but significantly decreased in intestine (p < 0.01); the activity of Aj-PK also declined significantly in intestine (p < 0.01), whereas it increased significantly in the respiration tree (p < 0.05) and muscle (p < 0.01). The gene sequences of Aj-HK and Aj-PK were identified, and their transcriptional quantification revealed that the expression of Aj-HK was depressed in all of the examined tissues, whereas Aj-PK expression was depressed in muscle only. These results suggest that glycolytic suppression occurred in aestivating A. japonicus, especially in the intestine, and transcriptional and post-transcriptional modifications are involved in the regulation of glycolytic suppression in this marine species.