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Faculty Research

Department of Biology

 

Dr. Brent Hendrixson

Urban Jungles Radio Check out a recent interview with Dr. Hendrixson on native U.S. Tarantulas.

As human populations continue to grow without limits, our planet's most precious resource - biological diversity - is disappearing at an unprecedented rate. The consequences of this human-induced mass extinction are not yet well understood, but most scientists agree that the results will be devastating. Continued loss of biodiversity cannot be sustained indefinitely - that is, of course, unless humanity braces itself to experience the same fate. However, before we can begin to comprehend the consequences of extinction or devise conservation strategies, we must know what organisms exist in the biosphere. Many exciting species remain unclassified and millions more await discovery! At its core, my research program aims to identify genetic and species-level diversity in spiders, but ultimately seeks to address broader-scale questions with regards to their evolution, biogeography, and conservation. Students in my laboratory have unique opportunities to synthesize data collected through two seemingly dissimilar areas of biology (field-based and molecular lab-based) to tackle difficult questions that likely cannot be answered by either discipline in itself.

I am presently working on the tarantula genus Aphonopelma. Most species are inadequately defined and a substantial number of undocumented species (i.e., a species that has not been formally named) exist, necessitating this research. A handful of students have traveled with me to California, Nevada, Utah, Arizona, New Mexico, Colorado, Kansas, Oklahoma, and Texas to assist collecting tarantulas so we can better assess the diversity of these spiders in the United States. A few novel spiders were discovered during the course of these field expeditions and future collecting trips into mainland Mexico and Costa Rica will surely uncover many more. In the molecular laboratory, students have learned how to extract DNA from spider tissues, perform PCR (polymerase chain reaction) to amplify genes of interest, and set-up DNA sequencing reactions. In the future, students will become familiar with phylogenetic and GIS (geographic information system) analyses. Generous financial support for my research program has been provided by the National Science Foundation and American Tarantula Society.

 

Dr. Debora Mann

Mississippi is home to a remarkably diverse flora and fauna. The ecology and conservation of our native Mississippi native species is the focus of my research with students. One of our projects is an investigation of the distribution and habitat requirements of a rare species, Webster's salamander, Plethodon websteri. This small, terrestrial salamander is found in scattered locations across five southeastern states including Mississippi, generally in deciduous forests associated with rock outcrops. Its small, isolated populations are highly vulnerable to human-caused disturbances such as mining and deforestation. By locating previously undiscovered populations of this species and coming to a better understanding of its habitat requirements, we can better secure the protection of this species.


Plethodon websteri

 Dr. Sabrice Guerrier 

My lab studies the process of cell-cell fusion. This process is important for the development of human tissues like bone and muscle but is also critical to disease processes such as the transmission of viruses and cancer progression. We use a laboratory strain of Tetrahymena thermophila, a fresh water ciliate, to study cell-cell fusion because they are affordable to maintain, easy to grow and we can make these cells undergo fusion by simply starving them. Despite the fact that these cells seem very different from human cells, they are actually genetically very similar, allowing us to study genes that might be important for human cell fusion in a system much more amenable to working with students.

Using bioinformatics, our lab has identified two families of proteins that may be important for regulating the shape of the plasma membranes when fusion occurs. We are currently using fluorescence microscopy to determine the location of these proteins during the fusion process. In addition we are creating genetic mutants in which these genes are disrupted to determine the effect of losing these proteins on the ability of Tetrahymena to fuse. We hope that results from these studies will provide a better understanding of the mechanisms underlying cell fusion in Tetrahymena and eukaryotic cells in general.

Dr. Beth Hussa 

As a microbiologist, my interest is in understanding the ways in which microbes, particularly bacteria, interact with other host organisms, a phenomenon known as symbiosis. In my lab, we study the bacterium Xenorhabdus nematophila, which interacts  with two different host organisms in two very different ways. The bacterium associates with a microscopic worm called a nematode (Steinernema carpocapsae), which is found in soil and can infect caterpillars . Upon infection, the nematode releases its bacterial partner into the insect’s blood (called hemolymph), and the bacteria kill the insect and break down its tissues as a food source for both bacterial and nematode reproduction. When all of the nutrients are utilized, the bacteria colonize the nematodes once more and the nematode seeks out a new host insect. I am particularly interested how the bacterium regulates gene expression at various stages throughout the symbiotic cycle.

Dr. Sarah Lea Anglin

One of the hallmarks of cancer cells is loss of control of cell division, and understanding the regulators of cell division is essential to understanding the nature of cancer. The main focus of work in my laboratory is to understand the molecular and genetic mechanisms that control cell division. Since these mechanisms are highly evolutionarily conserved, cell division can be studied in lower organisms such as yeast and other fungi, and the findings can then be used to understand cell division in higher organisms, including humans. My laboratory uses two fungi, the budding yeast Saccharomyces cerevisiae and the fungus Aspergillus nidulans, to identify and characterize genes and proteins that control cell division, particular mitotic entry, and exit.


We are currently studying a gene in yeast, Kin3, which is a poorly understood member of the NIMA family of mitotic regulators. Using high-throughput robotics and molecular techniques, we have screened the entire budding yeast genome to identify genes that interact with Kin3, as part of an ongoing study to reveal genes and cellular processes that Kin3 affects. We are also studying two genes in Aspergillus nidulans which were originally identified in our laboratory and which are involved in regulating cell division.

Mutation of one of these genes causes a lethal interaction with a mutation in nimA, the Kin3 homolog of Aspergillus nidulans and the first identified member of this mitotic regulatory family. These studies should lead to a better understanding of the mechanisms that control cell division in these organisms.