In 2017, it was discovered that naked mole rats ( Heterocephalus glaber ) could
ID: 3164637 • Letter: I
Question
In 2017, it was discovered that naked mole rats (Heterocephalus glaber) could survive up to 18 minutes in an anoxic (0% oxygen) environment without any permanent damage to the organism. The normal body temperature of naked mole rats is 30°C, making them poikilothermic animals that are able to operate at a range of body temperatures and to alter its body temperature based upon the environment. Even if the animals are warmed to 37°C, they still survive 6 minutes in an anoxic environment, which is still more than 5 minutes longer than the survival of other rodents like mice. You are already familiar with the H. glaber hemoglobin, but as usual, this does not fully explain the naked mole rat ability to survive anoxia.
Blood glucose concentrations during anoxia were found to be similar in mice and mole rats, but during normoxic (normal oxygen levels) conditions, naked mole rate had a blood glucose concentration of 3.49mM while mice had 6.66mM, making them appear hypoglycemic compared to other rodents and mammals.
Given the data in Figures 1A-D, what do you suspect is occurring in naked mole rats versus in mice during anoxic conditions? What is the expected metabolic fate of these sugars in the liver and kidney, considering these organs express fructokinase and glucokinase, but not hexokinase I?
Figure 1: Concentrations of Fructose and Sucrose in mice and naked mole rats during anoxia
1A Fru ctose Levels 1B Fru ctose Levels 25 2 50 200 a 150 20 15 10 liv er ki dney blood mouse nommoxia mouse anoxia mouse nomoxi a mouse a noxia naked mole at normoxianake d mole rat an oxia naked mole at normoxia naked mole rat anoxia 1C Sucrose Levels 1D Sucrose Levels 60 10 30 20 10 400 3 50 3 00 2 50 200 150 50 liv er ki dney blood mouse nom oxia mouse a noxia moLse nomoxia mouse anoxia naked mole at ror moxa-naked mole at anoxia naked mole at normoxia naked mole rat anoxiaExplanation / Answer
Graph is showing that during anoxia, fructose and sucrose concentration is high in naked mole as compared to the mice in the organ like liver, kidney and blood.
The unexpected increased in the fructose and sucrose suggest that sugar are these sugar are helping the naked mole under anoxia. Fructose is converted into fructose 1,6 phosphate by ketohexokinase. Fructolysis is prominent in kidney and liver. In blood, fructose and sucrose concentration differ between two organism because of difference in glycogen synthesis.
Mole rat have ability to use fructose to fuel vital organ. Both fructose and sucrose rises to high level, but source is unknown.