Louis J. Guillette - US grants

At least five independent research programs in the Department of Zoology at the University of Florida depend upon ready access to a modern, reliable Atomic Absorption Spectrophotometer (AA Spec) for elemental analysis. These include studies on mechanisms of ion and acid-base regulation in decapod crustaceans, mineral nutrition of the green turtle Chelonia mydas, ion transport in elasmobranch red cells, the role of ions in the evolution of viviparity in reptiles, and ions and body fluid regulation in snakes. The requested AA Spec would replace an inoperable instrument, the only one of its kind on campus. The model requested is fully automated, offering the most versatile state-of-the-art capabilities for multiple users.

A fundamental issue in ecology is determining factors that regulate the density of animal populations. The importance of understanding determinants of animal abundance has increased with the need to develop informed management plans for endangered or threatened species. With respect to primates, these issues are critical because tropical forests occupied by primates are undergoing rapid anthropogenic transformation. However, understanding and predicting factors that determine primate abundance has proven extremely difficult. Numerous studies of forest primates have revealed a high degree of inter-site variation in density, but there are few direct tests of general hypotheses proposed to account for this variation. Notable exceptions are studies of folivorous primates, where the protein/fiber ratio of available leaves has been used to predict folivorous primate biomass. In a previous NSF, Colin Chapman showed that this relationship applied to small spatial scales, and he was able to predict the biomass of neighboring populations of colobine monkeys inside Kibale National Park, Uganda. He also demonstrated diet selection for foods with high protein to fiber ratios and tested two alternative hypotheses (colobines are energy limited or restricted by the availability of particular minerals). However, finding single factor explanations for complex biological phenomena, like determinants of colobine abundance, is unlikely. Rather, recent long-term studies have highlighted the importance of multifactoral explanations. As a result, this current project will explore the possibility that nutrition and parasitism operate synergistically to influence colobus population dynamics. Two approaches will be taken. First, in a system of forest fragments monitored since 1995, this project will test if the size of population change is a function of changes in the availability of quality foods and the level of parasitic infections. To partially evaluate assumptions made when taking the second approach, levels of stress hormones, isolated from fecal samples, will be relate to the magnitude of population change. Secondly, using long-term observation of a stable population, the degree to which periods of stress, as indexed by levels of cortisol metabolites in fecal material, correspond to periods of food scarcity and/or increased parasite infections will be assessed.
The broader impacts of this study are many. For example, this information will be useful in construction of informed management plans for folivorous primates around the world. Funding will also facilitate long-term monitoring in Kibale, building the infrastructure of Makerere University Biological Field Station, promoting Ugandan student training and conservation (2 students have been identified), graduate and undergraduate training at the University of Florida, and dissemination of this information to the public by assisting the development of nature films (particularly with the BBC).

This award supports research and educational activities under the Interdisciplinary Grants in Mathematical Sciences program. The principle investigator who has background in mathematics proposes to obtain a broader background in biology. The projected activities are expected to lead to collaboration between the principle investigator and biologists in the Zoology Department.

The research plan is centered on topics from mathematical epidemiology and involves elements of evolutionary biology. The investigator proposes to use partial deferential equation models and dynamical system theory to study the role of host immunity and age-structure in the competition and coexistence of multiple pathogen subtypes. In particular, she will study a number of emerging phenomena related to the use of vaccines and their impact on evolving pathogens: Strain substitution, subthreshols coexistence and multiple coexistence regimes.

The educational activities are directed towards building the PI's background in biology and expanding the range of experiences for science students at University of Florida. The PI will spend eleven months
of the 2005-2006 academic year in the Zoology Department of University of Florida. She will take several undergraduate and graduate classes in biology. She will read a number of articles in theoretical ecology, she
will interact closely with biologists in the Zoology Department and their students and postdocs.

The PI expects to use her broader background to communicate with a wider range of scientists and to expand the experiences of science students at the University. She will teach a graduate course in mathematical
biology. She will jointly co-mentor with biologists students in mathematics and biology. She will share the results of her research through talks and projects for interested students.

This IGMS project is jointly supported by the MPS Office of Multidisciplinary Activities (OMA) and the Division of Mathematical Sciences (DMS).

[unreadable] DESCRIPTION (provided by applicant): Development of the ovarian follicle is a complex process integral to female fertility. The objective of this proposal is to expand understanding of the mechanism(s) causing the formation of aberrant multi-oocytic follicles (MOFs) during vertebrate folliculogenesis using a novel study species, the American alligator. Multioocytic follicles (MOFs, also called polyovular follicles) have been associated with decreased success rates of in vitro fertilization and increased embryonic loss. MOFs have been studied in laboratory animals, however, a natural population of alligators has been identified in which 100% of neonatal females exhibit this pathology apparently due to environmental contaminant exposure. In comparison, reference alligator populations exhibit no MOFs or a very low frequency. Due to the conserved nature of folliculogenesis, we propose this comparative approach to address the mechanism(s) associated with the development of MOFs. Laboratory research has identified both estrogens and the transforming growth factor inhibin as factors that can induce MOF formation. The central hypothesis of this proposal is that the disruption of the ovarian hormonal milieu by exogenous factors alter ovarian follicle development leading to MOFs. The studies proposed will test this hypothesis by investigating 3 related specific aims. Aim 1 will examine the gene expression patterns for selective components of the estrogen and inhibin/activin signaling pathways in cellular compartments of normal and multioocytic ovarian follicles using laser capture microdissection and quantitative RT-PCR. Aim 2 will examine estrogen-induced perturbation of the inhibin A/Activin A signaling pathway and their potential role in altered granulosa cell proliferation or apoptosis. This will be tested by embryonic exposure to estradiol followed by FSH challenge during 2 life stages. Aim 3 will examine environment estrogen or pharmaceutical anti-estrogen-induced perturbation of the inhibin A/Activin A signaling pathway and their role in altered granulosa cell proliferation or apoptosis to firmly establish if an environmental perturbation leads to altered inhibin/activin signaling. In total, the studies described in this application provide a novel approach to provide new insights into normal follicle development, establish mechanisms by which normal development could be disrupted leading to aberrant ovarian pathologies such as multi-oocytic follicles, and offer new insights into the regulatory functions of inhibin/activins and estrogens in this important reproductive process. Understanding and documenting the conserved mechanisms of induction of MOFs among vertebrates will strengthen the causal and mechanistic relationships, allowing a better understanding of this phenomenon in human populations. [unreadable] [unreadable] [unreadable]