Fish metabolism under adverse conditions

研究将解决环境挑战，特别是低氧和极端温度对鱼类生理和生物化学的影响。比较/环境方法将用于选择在血糖水平和抗冻性方面表现出天然差异的动物。1)低血糖和缺氧鱼类的葡萄糖代谢。细胞外葡萄糖水平显示出相当大的物种变异性。例如，在杜父鱼、刀鱼和大西洋鳕鱼中的水平通常分别为约0.5、2.5和5 mM。实验将评估细胞外葡萄糖浓度是否是葡萄糖利用的主要决定因素，但如果葡萄糖利用在物种之间是相似的，那么这是如何实现的。将确定葡萄糖使用率，并将其与膜转运蛋白的氨基酸序列相关联。还将研究生活在高温亚马逊河中的高度耐缺氧鱼类的葡萄糖转运机制。低氧和高温的结合对这些物种提出了极端的要求，可能需要新的生化策略。2)虹鳟鱼对甘油的吸收。彩虹胡瓜鱼是一种小型鱼类，冬季在海冰下觅食。抗冻性在很大程度上是通过积累高水平的甘油（>200 mM）来实现的。化学甘油类似于冬天放在汽车散热器里的东西。甘油在所有组织中积累，包括红细胞（RBC）。与其他组织不同，红细胞是移动的，并且在通过鳃运输期间，应该将甘油损失到海水中。我们认为，红细胞在通过肝脏时得到充电，并且这种摄取依赖于被称为水甘油孔蛋白（AQGP）的蛋白质。将评估冶炼红细胞具有新的和独特的AQGP的可能性。这些实验将揭示超越模型系统的新陈代谢的基本见解。例如，我们可能会发现，在具有低细胞外葡萄糖的物种中，转运蛋白对葡萄糖具有更高的亲和力，或者红细胞具有先前未表征的AQGP。这些将是生物化学适应环境的新发现。

Research will address the impact of environmental challenges, especially low oxygen and temperature extremes, on the physiology and biochemistry of fish. The comparative / environment approach will be used in selecting animals that exhibit naturally occurring differences in blood glucose levels and resistance to freezing. 1) Glucose metabolism in hypoglycaemic and hypoxic fish. Extracellular glucose levels show considerable species variability. For instance, levels in sculpin, cunner, and Atlantic cod are typically about 0.5, 2.5 and 5 mM, respectively. Experiments will assess if extracellular glucose concentration is a primary determinant of glucose utilization but if glucose utilization is similar across species, just how this is achieved. Rates of glucose use will be determined and related to the amino acid sequences of membrane transporter proteins. Glucose transport mechanisms will also be studied in highly hypoxic resistant fish living in the high temperature Amazon River. The combination of low oxygen and high temperature places extreme demands on these species that may require novel biochemical strategies. 2) Glycerol uptake by rainbow smelt. Rainbow smelt is a small fish that feeds under the sea ice during winter. Freeze resistance is achieved to a large extent by the accumulation of high levels of glycerol (>200 mM). The chemical glycerol is similar to what is placed in car radiators in the winter. Glycerol accumulates in all tissues including red blood cells (RBCs). Unlike other tissues, RBCs are mobile, and during transit through the gills, should lose glycerol to the sea water. We believe that RBCs get recharged upon passage through the liver and that the uptake is dependent upon proteins known as aquaglyceroporins (AQGPs). The possibility that smelt RBCs have novel and unique AQGPs will be assessed. These experiments will reveal fundamental insights into metabolism that extend beyond the model systems. For instance, we may find that in species with low extracellular glucose, that the transporters have a higher affinity for glucose or that smelt RBCs have a previously uncharacterized AQGPs. These would be novel findings of biochemical adaptations to the environment.