Life Lines by Dr. Dolittle

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Tag Archive for ‘fish’

Experimental Biology 2021: Q&A with Dr. Christian Damsgaard

We are delighted to speak with Dr. Christian Damsgaard who is currently an Assistant Professor at the Aarhus Institute of Advanced Studies & Section for Zoophysiology, Aarhus University, Denmark. Dr. Damsgaard is a member of the Comparative and Evolutionary Physiology section of the American Physiological Society and he presented his research “Active Blood Acidification Greatly Enhances Oxygen Supply to the Teleost Retina” at the 2021 Experimental Biology conference today. What initially interested you in studying […]

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Extreme tolerance of dehydration stress

Talk about an extreme animal. During the rainy season annual killifish, Austrofundulus limnaeus, lay eggs that are resistant to droughts. This is an important attribute for a fish that lives in temporary pools of water. The stress-resistant embryos within the eggs literally shut down their metabolism to survive months – possibly years without water. For many fish, exposure to air (and oxygen) can cause profound oxidative stress. Remarkably, this is […]

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Anoxia tolerance in goldfish

The reason mammals are not very good at tolerating hypoxic (i.e. low oxygen) environments, is because the brain relies heavily on oxygen for metabolism. It is so stingy, it uses about 20% of the oxygen in the body to make ATP. Without oxygen, the brain has to rely on glycolysis to make ATP and this process is not good at meeting the energy requirements of the neurons, ultimately resulting in […]

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Why pigs and people absorb more sugar from their diet than fish

Researchers at the University of Saskatchewan in Canada compared how pigs and fish absorb glucose (i.e. sugar) from the diet. They did this by measuring how well glucose moves across the intestinal wall. Their findings appear in the American Journal of Physiology – Regulatory, Integrative and Comparative Physiology.  Transport of dietary glucose from the gut to the blood is facilitated by glucose transporters that pick up glucose and move it […]

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Low-calorie sweeteners – harmful or hype?

Researchers at Columbia University wanted to examine whether low-calorie sweeteners disrupt glucose tolerance as there are conflicting reports in both human and animal studies. Their results examining the link between low-calorie sweeteners and glucose regulation in mice are published in the upcoming issue of the American Journal of Physiology – Regulatory, Integrative and Comparative Physiology. In their first experiment, the research team found no differences in glucose tolerance or body […]

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Warm hypoxic waters impair heart function in some fish

Events causing bodies of water to become hypoxic (low oxygen levels) are increasing with climate change. Water can become hypoxic when it warms up or there are changes in tidal flow, density, wind patterns as well as separation from the main source, such as occurs in a tidepool. While some fish are tolerant of hypoxia and even anoxia (oxygen depleted) environments others, such as Atlantic cod and steelhead trout, rely […]

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Rising water temperatures masculinizes Nile tilapia

Nile tilapia, Oreochromis niloticus, is a species of freshwater fish native to Egypt and Africa. Global warming has the potential to significantly impact this species as water temperatures above 32 to 36.5 degrees Celsius can induce young fish (10-30 days after fertilization) that are genotypically female to become masculinized. Moreover, a recent study published in PLOS ONE showed that some young fish choose to visit warmer waters. A new study published […]

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Lactate directly increases breathing

Hypoxic environments increase ventilation in animals. This helps to bring in more oxygen when environmental levels may be limited. With limited oxygen availability, the body turns to anaerobic metabolism, resulting in the production of lactate ions. These ions are known to indirectly stimulate breathing by lowering blood pH and were more recently discovered to directly stimulate the carotid body to increase breathing. For this reason, lactate ions are thought to […]

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Carnivorous fish are glucose intolerant

Who would have thought that carnivorous fish, like the gilthead sea bream pictured above, and people with diabetes have a lot in common? These fish are glucose intolerant, meaning they are not able to use glucose for energy very well. When these fish are given carbohydrates, their blood sugar increases as does their ability to produce fats through lipogenesis. The purpose of this increase may be to store the excess […]

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Breathing air

Researchers interested in the evolution of air breathing in bony fishes (Osteicthyes) recently published a fascinating review in the Physiologist. The ability to breathe air made life on land as we know it possible. What is interesting though is that the ability to breathe air actually evolved independently possibly 38-67 times in history. Currently, there are over 400 air-breathing fishes belonging to the Sarcopterygii and Actinopterygii classes. To adapt to life on land, […]

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