Spring 2008 Asa Gray Seminar Series
“Using "Designer Mice" to Study Human Viruses”
Jennifer F. Moffat, PhD
Department of Microbiology and Immunology,
Some viruses only infect humans, such as AIDS (HIV), chicken pox (VZV), and certain lymphomas (HTLV-1). It has been difficult to study these diseases without a small animal model for biomedical research. To address this problem, models were created that graft human tissues into mice that lack an immune system. Using these "designer mice", much progress has been made in understanding how human viruses cause disease, and new antiviral drugs have been tested. Technology has been developed to measured virus infection in living mice using bioluminescent imaging. These tools are important for developing better treatments and vaccines.
“DOES MOTHER NATURE ALWAYS KNOW BEST? The contribution of fetal ethanol experience to adolescent alcohol abuse”
Steven Youngentob, Ph.D
Professor and Vice-Chair
Department of Neuroscience and Physiology
A substantial literature has documented the extensive negative consequences associated with prenatal exposure to ethanol in terms of the drugs toxic effects on the developing nervous system. For example, prenatal exposure to ethanol can cause behavioral changes such as hyperactivity, and learning and memory deficits. Further, gestational exposure is a leading known cause of mental retardation. These observations notwithstanding, there are subtler, yet potentially just as detrimental long-term consequences. Clinical and epidemiological studies provide strong evidence for a relationship between prenatal ethanol exposure and the risk for ethanol abuse in adolescent and young adults. In fact, gestational exposure in humans is considered, perhaps, the best predictor of later ethanol abuse during adolescence. Thus far, there is little evidence regarding the underlying factors contributing to these long-term ingestive consequences. In this respect, there is extensive data demonstrating the general finding that olfactory (smell) and gustatory (taste) experiences influences sensory function, that postnatal behaviors controlled by chemical stimuli can be influenced by fetal experiences with the odorant or tastant, and these early experiences can later modulate intake and preferences for the substance. We have begun testing the theory that altered olfactory and gustatory system responsiveness to ethanol, as a consequence fetal exposure, acts as a potential contributing risk factor for postnatal preference. To accomplish this, we have been applying behavioral and neurophysiological methods to examine the response of early postnatal, adolescent and adult animals to ethanol. The developing data from these studies provide evidence that fetal ethanol experience induces developmental changes in the chemosensory systems involved in the preference for ethanol odor and the perception of ethanol’s flavor: thereby contributing to the risk of initial ethanol ingestion and continued abuse in adolescence.
“Autism and Alcohol. What's the Connection?”
Sandra M. Mooney, Ph.D
Department of Neuroscience and Physiology
Autism is a developmental disorder that is diagnosed based on abnormal social behaviors. The underlying cause of autism is unknown. Based on family histories, there is a clear genetic component to autism; however, it is also likely that there is an environmental contribution. One example is that prenatal exposure to compounds (such as drugs or alcohol) alter fetal development and also cause autistic-like changes in social behaviors. We have been examining how timing of the exposure to alcohol affects social behaviors. Pregnant rats were given a single exposure to alcohol either at a time equivalent to the fourth week of pregnancy (i.e., before may women know they are pregnant) or a time equivalent to the tenth week of pregnancy in humans. We examined the behavior of the offspring and found that not only did both groups of rats exhibit abnormal social behaviors compared to controls, but that the two alcohol groups were different from each other. This suggests that (1) even a short exposure to alcohol can have long-term (possibly permanent) effects on social behavior, (2) the time when the alcohol is given can dictate the behavioral change(s), and (3) exposure to environmental toxins, such as alcohol, may be one of the many causes of autism.
“Little brown bats (Myotis lucifigus) recognize individual identity of conspecifics using sonar calls”
Merck Division of Science and Technology
Southern Vermont College
Bats use sonar calls to locate prey and orient in their environment but they may also be used by conspecifics to obtain information about a caller. Statistical analysis of sonar calls provides evidence that variation carries social information about a caller, including individual identity. We hypothesized that little brown bats (Myotis lucifigus) would be able to recognize individuals given the potential fitness benefits of doing so. We performed playback trials using a habituation-discrimination design to determine whether little brown bats are able to recognize the individual identity of a caller based on variation in their sonar calls. Each subject bat was played the calls of Bat A until they habituated (defined as a 50% decrease from the initial call rate) then the calls of Bat B or a new call sequence of Bat A (a control, referred to as Bat A’) was played. Each subject received a unique pair of playback recordings (Bat A and B) from adult female bats from the same colony (but a different colony than the subject) and the order of trials was randomized. The response measures were habituation time (s) and call rate (call/s). Within a trial, subjects habituated to calls of Bat A and transferred this habituation to the Bat A’ sequence, in addition, they increased their call rates when played calls of Bat B. Comparing between trials, subjects increased their call rate to the calls of Bat B to a greater relative extent than to the calls of Bat A’. These results provide the first evidence that bats recognize individual identity of conspecifics (as opposed to discrimination of groups) which has implications for the social interactions of bats.
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