Modifying the hemolymph glucose concentration response in crayfish

Quantifying the hemolymph glucose concentration response in crayfishComparative Biology

Why is it so important?Comparing features (physiology, behavior, etc.) across different species experiencing similar situations,helps us to hypothesize trends in how organisms respond to their environment!Physiology comparisonsMost invertebratesMost vertebrates

Circulatory system: similar (blood transports nutrients) but different (open vs. closed)Comparative biology crayfish are similar but not that similiar3How do we control our behaviors and energy use?Endocrine SystemCentral Nervous System

For some effects they need to be fast others can be slower. In the case of glucose homeostasis (insulin and glucagon carry out these functions in humans) Crayfish are well characterized for their physiology but several of the hormones and genes expressed are poorly characterized. CHH produced by the eyestalk however is. Its function and what has been known to do. Serotonin has been used to recruit glucose for quick utilization.

4

Glucose: its how cells get energyCellular respirationAerobic (needs oxygen)Anaerobic (no oxygen available)Glucose is required for both!When our muscles run out of oxygen, they switch to anaerobic (much less efficient!)Waste product: lactic acid (muscle cramps)Glucose regulation

Hyperglycemic (too much glucose)Hypoglycemic (not enough glucose)Crayfish produce Crustacean Hyperglycemic Hormone (CHH) from the sinus glands behind their eyes!

CHHThis hormone is similar to glucagon in humans it tells the crayfishs body to release more glucose into the hemolymph!Transition after this slide:as you are well aware of many things can impact not only behaviors but also circulating hormones. Of some that crayfish (and humans may have to deal with are: stress, salinity, and temperature)7Temperature affects blood-glucose levels

Endotherms (mammals, birds) and Ectotherms (reptiles, fish, arthropods, crustaceans) both need to maintain proper blood-glucose levels at different temperatures (remember homeostasis?)Crayfish are well characterized for their physiology but several of the hormones and genes expressed are poorly characterized. CHH produced by the eyestalk however is. Its function and what has been known to do. Serotonin has been used to recruit glucose for quick utilization.

8Salinity affects blood-glucose levels

Substances absorbed/ingested from the environment (food, air, water) can affect your bodys release of hormones such as cortisol (stress hormone), which can in turn stimulate other hormones, including insulin and glucagon, which can affect your blood-glucose level! (homeostasis again!)Stress affects blood-glucose levels

Stress (searching for mates, fighting for territory, avoiding predators, etc.) can elevate blood-glucose levelsFight-or-flight response: Your body releases many hormones, including glucagon, which provides your cells with more glucose, so you have more energy to deal with a tough situation!For lab todayWe want to quantify how different conditions induce changes in crayfish hemolymph glucose concentration.Obtain crayfish, take hemolymph sample, apply treatment, take hemolymph sample againCompare before-treatment to after-treatment: is there a change in glucose concentration?

PLEASE BE CAREFUL WITH YOUR SYRINGES AND NEEDLES, as well as the crayfish claws

If you have ANY QUESTIONS, please ASK your TAInsert needle at this angle

Insert needle under the back of the carapace (1)12