1. Effects of Temperature Stress on DNA:RNA Ratios of Tilapia Jacques Chansavang Canterbury High School Fort Wayne, Indiana

2. The Stress Response and Development of Allostatic Load.
Figure 1. The Stress Response and Development of Allostatic Load.
The perception of stress is influenced by one's experiences, genetics, and behavior. When the brain perceives an experience as stressful, physiologic and behavioral responses are initiated, leading to allostasis and adaptation. Over time, allostatic load can accumulate, and the overexposure to mediators of neural, endocrine, and immune stress can have adverse effects on various organ systems, leading to disease.

3. Motivation Animals in nature must respond to a wide variety of environmental changes in order to survive. Changes in temperature, salinity, light, food supply etc can cause changes in animal’s physiology and make them vulnerable and susceptible to diseases. Physiological effects on the individual can potentially translate into changes in the whole population and entire community. Our research team is investigating how aquatic organisms cope at a cellular and whole-organism level to environmental stress. Information about how organisms respond physiologically to their environment will help us understand how organisms may respond to environmental change, including global climatic change.

4. Aquaculture: Farming of aquatic plants and animals -Produces food -Improves natural stocks through recruitment -Produces sport fish and baits for commercial & sport fishing -Supplies materials to hobbyists and scientific research groups -Produces organisms to recycle organic waste -Produces organisms for industrial commodities

5. Aquaculture: Why important
Aquaculture: Why important? -World population is increasing -Agricultural production is not increasing as fast as population -Food supply, particularly cheap high quality protein have been experiencing shortage -Fisheries production is approaching the maximum sustainable yield

6. Problems in Aquaculture: Extensive husbandry methods
Problems in Aquaculture: Extensive husbandry methods Crowding, handling, vaccinating Environmental impacts Temperature, salinity, toxicity from chemical discharge Diseases Parasitic, bacterial, viral All these cause Stress !!

7. Stress in Aquaculture (Factors that impair the normal performance) Stress Response Primary Secondary Tertiary Stress hormones Metabolic changes Whole animal Cortisol DNA:RNA ratio effects: Growth

8. Tilapia Tilapia is a popular fish in aquaculture – they are hardy, prolific, and fast-growing; they require water temperatures from 25 to 28 degrees Celsius. Currently, tilapia are produced in outdoor ponds and indoor systems. Producing tropical tilapia in North America will require an indoor installation where water and air temperature can be controlled, and this will requires a relatively larger capital investment than producing the fish outdoors in a warmer climate.

9. Objectives Broad Objectives To investigate the possibility of farming tilapia in the cooler waters of North America. Specific Objectives To investigate the effects of cool water temperature stress on the physiology of tilapia.

10. DNA: RNA Ratio This measurement indicates whether an organism is growing at a given time. Most animals have a fairly constant amount of DNA (the "blueprints" for growth), and only increase the amount of RNA (the "construction sites" for growth within the cell) when growing. Therefore, a high ratio of RNA to DNA indicates that a lot of "construction" is going on and the animal is growing. By using this technique, researchers can show if fish are stressed and not responding quickly at the cellular level.

11. Experiments Fish Group:. Control- Warm water (28±1oC)
Experiments Fish Group: Control- Warm water (28±1oC) Experimental-Cool-water (18±1oC) Feed: Regular feed Sampling: 0, 4, 8, 24, 48, and 72 hours post-cool water exposure Sample size: 5 fish per group Parameters: DNA:RNA ratios from muscle tissues (From preserved samples collected by Dr. Mustafa’s research team)

12. Sampling Period (Hours)
DNA: RNA Ratios
DNA:RNA Ratio
Sampling Period (Hours)

13. Summary A cool water exposure at about10 degree below the optimum level did not cause any stress that could damage the fish at the cellular level (values decreased immediately after exposure but came back to basal level within 24 hours). (This finding corresponds with other findings at the physiological and immunological levels investigated by the research team).

14. Conclusion Tilapia may grow slower in cooler waters during the cooler months but they will survive and re-grow to the marketable size when they get back to optimal temperature. Aquaculture of Tilapia in cooler waters is possible.

15. Acknowledgement Dr. Ahmed Mustafa and His Research Team For teaching me how to do a scientific research. Special thanks to Ms. Laura Randolph, Dr. Ahmed Mustafa’s graduate student for taking extra steps to help me complete my part of the investigation.