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Albany, NY – In today's Academic Minute, Dr. John Hatle of the University of North Florida explains his research using grasshoppers to understand why avoiding reproduction often increases an organism's overall lifespan.
John Hatle is an associate professor of biology at the University of North Florida where he teaches courses in biology, anatomy, and physiology. His current research is focused on tracking how nutrients are used differently in grasshoppers that are denied the opportunity to reproduce. Hatle holds a Ph.D. from the University of Louisiana - Lafayette.
Dr. John Hatle - Reproduction and Lifespan
An animal's lifespan is somewhat plastic, just like age at adulthood in people. The ability to increase human lifespan would likely delay the onset of several major diseases. To work toward this goal, biologists seek to understand the process of aging by using simple model organisms that have short lifespans and can be manipulated in the lab.
In these model organisms, individuals with reduced reproduction live longer. It is unclear how reduced reproduction produces longevity, but the long-standing hypothesis suggests that allocation of ingested nutrients is involved. It is thought that individuals that do not need to put nutrients toward reproduction have more left over for the rest of the body. This allows greater maintenance of the body, and longevity. Many parents of young children have an affinity for this hypothesis. It also fits with many examples of animals with experimentally reduced reproduction and increased lifespan. However, directly testing this requires feeding long-lived animals labeled diets, and then seeing where the nutrients end up in the animal.
To this end, my lab studies nutrient allocation in female grasshoppers that have had the ovary surgically removed. These females live about 20% longer than their peers. Hence, they have reduced reproduction and increased lifespan. However, surprising to us, the routing of ingested nutrients to storage showed no proportional change. This suggests that reduced reproduction extended lifespan but did not work through a change in the distribution of nutrients. This means that reproduction directly damages the body. Exactly how reproduction damages the body remains to be seen, but growth hormones similar to insulin may be involved.>/i>