Effect of temperature on the glycometabolism of Hepialus yushuensis larvae
Author of the article:LI Xiu-Zhang LIU Xin LI Yu-Ling
Author's Workplace:College of Animal Husbandry and Veterinary Sciences; Qinghai University, Xining 810016, China
Key Words:Cordyceps sinensis; Hepialus yushuensis; glycogen; trehalose; trehalase
Abstract:
[Objectives] To analyze the carbohydrate content and the
activity of key carbohydrases in Hepialus yushuensis larvae, the
dominant host of Cordyceps sinensis in the main C. sinensis producing areas of Qinghai province, in order to investigate the
mechanism underlying adaptation of H. yushuensis larvae to the Tibetan
Plateau’s cold environment where they are predominantly found in alpine meadows
at an altitude of 3 000-5 000 m and an annual average temperature of < 5 ℃. [Methods] 4th instar larvae of H. yushuensis were randomly assigned to one of three
treatment groups which were kept at temperatures of 5, 15 (control), or 25 ℃ for 1, 2, or 4
hours. At the end of each experiment, the glycogen, fructose, trehalose and sorbitol
content of larvae, and their trehalase, glycerol 3-phosphate dehydrogenase and
glycerol 3-phosphate dehydrogenase activity, were measured. [Results] Glycogen content was significantly lower in
the 25 ℃
treatment group, than the 15 ℃
control group (P<0.05). Trehalose, fructose and sorbitol content were
higher in the 5 ℃
treatment group than in the 25 ℃
group (P<0.05). Trehalase activity was significantly lower in the 5 ℃ treatment group, and
significantly higher in the 25 ℃
group, than in the control group (P<0.05). Glycerol 3-phosphate
dehydrogenase and glyceraldehyde-3-phosphate dehydrogenase activity were
significantly higher in the 5 ℃
group than in the control group (P < 0.05), indicating that low
temperature may accelerate conversion of glycogen and other sugars into
smaller, cold-resistant substances to improve cold-tolerance. [Conclusion] Glycogen catabolism in H. yushuensis larvae appears
to be closely related to increased monosaccharide and sugar alcohol content.
The tendency for catalytic alterations of three key carbohydradases is
consistent with observed changes in 4 kinds of carbohydrates. The carbohydrate
metabolism in H. yushuensis larvae is regulated by trehalase, glycerol
3-phosphate dehydrogenase and glyceraldehyde-3-phosphate dehydrogenase.