外温
低温保护剂
适应
渗透压
生物
低温生物学
内科学
生态学
生物化学
低温保存
渔业
医学
胚胎
作者
Ross P. Wohlgemuth,Daniel Haro,Heather E. M. Liwanag
标识
DOI:10.1016/j.cbpa.2023.111471
摘要
Ectotherms survive exposure to subzero temperatures through freeze tolerance or freeze avoidance. Among vertebrate ectotherms, glucose is commonly used as a cryoprotectant in freeze tolerant strategies and as an osmolyte in freeze avoidant strategies, while also functioning as a metabolic substrate. Whereas some lizard species are capable of both freeze tolerance and freeze avoidance, Podarcis siculus is limited to freeze avoidance through supercooling. We hypothesized that, even in a freeze-avoidant species such as P. siculus, plasma glucose would accumulate with cold acclimation and would increase in response to acute exposure to subzero temperatures. To investigate this, we tested whether plasma glucose concentration and osmolality would increase in response to a subzero cold challenge before and after cold acclimation. In addition, we examined the relationship between metabolic rate, cold acclimation, and glucose by measuring metabolic rate during the cold challenge trials. We found that plasma glucose increased during the cold challenge trials, and that the increase was more pronounced after cold acclimation. However, baseline plasma glucose decreased throughout cold acclimation. Interestingly, total plasma osmolality did not change, and the increase in glucose only slightly altered freezing point depression. Metabolic rate during the cold challenge decreased after cold acclimation, and changes in respiratory exchange ratio suggest an increased relative use of carbohydrates. Overall, our findings demonstrate an important role for glucose in the response of P. siculus to an acute cold challenge, thus adding evidence for glucose as an important molecule for overwintering ectotherms that use freeze avoidant strategies.
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