caa a22 4500 465826342 CHVBK 20180323112150.0 cr unu---uuuuu 170327e19900401xx s 000 0 eng 10.1007/BF00258765 doi (NATIONALLICENCE)springer-10.1007/BF00258765 Carbon balance and energetics of cyooprotectant synthesis in a freeze-tolerant insect: responses to perturbation by anoxia [Elektronische Daten] [Janet Storey, Kenneth Storey] Summary: The capacity for polyol synthesis by larvae of Eurosta solidaginis was evaluated under aerobic versus anoxic (N2 gas atmosphere) conditions. Glycerol production occurred readily in aerobic larvae at 13°C. Under anoxic conditions, however, net glycerol accumulation was only 57% of the aerobic value after 18 d, but the total hydroxyl equivalents available for cryoprotection were balanced by the additional synthesis of sorbitol. The efficiency of carbon conversion to polyols was much lower in anaerobic larvae. The ATP requirement of glycerol biosynthesis necessitated a 22% greater consumption of carbohydrate, when anaerobic and resulted in the accumulation of equimolar amounts of l-lactate and l-alanine as fermentative end products. The ratio of polyols produced to glycolytic end products formed was consistent with the use of the hexose monophosphate shunt to generate the reducing equivalents needed for cryoprotectant synthesis. A comparable experiment analyzed sorbitol synthesis at 3°C under aerobic versus anoxic conditions. Sorbitol synthesis was initiated more rapidly in anaerobic larvae, and the final sorbitol levels attained after 18 d were 60% higher than in aerobic larvae. The enhanced sorbitol output under anoxia may be due to an obligate channeling of a high percentage of total carbon flow through the hexose monophosphate shunt at 3°C. Carbon processed in this way generates NADPH which, along with the NADH output of glycolysis, must be reoxidized if anaerobic ATP synthesis is to continue. Redox balance within the hexose monophosphate shunt is maintained through NADPH consumption in the synthesis of sorbitol. Springer-Verlag, 1990 Eurosta solidaginis nationallicence Hexose monophosphate shunt nationallicence Anaerobic metabolism nationallicence Cryoprotectant synthesis nationallicence Freeze-tolerant insects nationallicence Storey Janet Institute of Biochemistry, Carleton University, K1S 5B6, Ottawa, Ontario, Canada aut Storey Kenneth Institute of Biochemistry, Carleton University, K1S 5B6, Ottawa, Ontario, Canada aut Journal of Comparative Physiology B Springer-Verlag 160/1(1990-04-01), 77-84 0174-1578 160:1<77 1990 160 360 https://doi.org/10.1007/BF00258765 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/BF00258765 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Storey Janet Institute of Biochemistry, Carleton University, K1S 5B6, Ottawa, Ontario, Canada aut NATIONALLICENCE 700 1- Storey Kenneth Institute of Biochemistry, Carleton University, K1S 5B6, Ottawa, Ontario, Canada aut NATIONALLICENCE 773 0- Journal of Comparative Physiology B Springer-Verlag 160/1(1990-04-01), 77-84 0174-1578 160:1<77 1990 160 360 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer