Nunez - change in the 1alpha-B mineralocoritcoid The...

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BIO 101C PRESENTATION SUMMARY Randy Bayas Rb25493 12 September 2007 Dr. Nunez. 8 September 2007. Elasmobranches Endocrinology. Elasmobranches are cartilaginous fishes comprising sharks and rays. Dr. Nunez uses these elasmobranches to study the change in levels of 1alpha-b during times of stress. The 1alpha-b hormone serves as a mineralocorticoid, which increases during times of stress. The Dr.’s experiments comprise of using the Atlantic stingray in isolated tanks of salt water. Adding freshwater into the tank slowly reduces the salt-water concentration, enabling stress to occur for the individuals. Although the natural habitat of Atlantic stingrays is salt-water, they are euryhalines. This means that the rays are able to survive in both fresh and salt water habitats. Dr. Nunez’s first hypothesis states that the plasma 1alpha-B increases when stingrays are adapted to fresh water. A 3-hour test was completed in which freshwater was added to the salt-water in order to test the levels of
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Unformatted text preview: change in the 1alpha-B mineralocoritcoid. The experiment showed that there was a “significant decline in plasma osmolarity in the 3 hour test. The 1alpha-B did not change as planned.” Since the original hypothesis did not hold up, a new “tweaked” hypothesis is formed. The newly formulated hypothesis states that the “Plasma 1alpha-B increases when stingrays become hyponatremic.” The levels of the 1alpha-B increase when the salt concentration reaches a certain level, which may be critical for the survival of the animal. In addition to the experiment that was undertaken, Dr. Nunez is able to present background information based upon the experiment. The reason Dasyatis sabina , or Atlantic Stingray, was chosen is from the animals’ ability to be abundant and easily obrained, robust and well adapted to captivity, the wealth of ecological data, and being a euryhaline. All these factors made the Atlantic Stingray the number one choice in Dr. Nunez’s experiments....
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