Fall 2009

Characterization of the Xenorhabdus nematophila colonization protein NilB

Dr. Archna Bhasin
Assistant Professor
Valdosta State University

Hosting Dept: Biology


Abstract:  The bacterium Xenorhabdus nematophila mutualistically colonizes the intestinal vesicle of the nematode Steinernema carpocapsae. The X. nematophila gene nilB (nematode intestinal localization) is essential for S. carpocapsae nematode colonization. Since nilB has no apparent homologues to genes of known function, we undertook a structure-function analysis of this novel protein to determine its function in nematode colonization. NilB is a 55 kD, 466 amino acid protein containing a signal sequence predicted to target it to the membrane. It is also predicted to be an outer-membrane beta-barrel protein with a globular domain, 14 trans-membrane domains, 7 external loops and 6 periplasmic loops. FLAG (DYKDDDDK) tags were inserted at various locations including the N-terminus (after the signal sequence), the globular domain, the external loops as well as the C-terminus. These tagged mutants were analyzed for NilB protein production and for colonization competency. The most interesting mutant contains the FLAG insertion at amino acid 393 (loop 6), produces protein, but is colonization defective. This suggests that external loop 6 of NilB is required for interaction with the nematode intestinal vesicle.

Thursday,  September 10, 2009 4pm

Biological Role and Detection of Nitric Oxide and Activity of Guanylyl Cyclase

Dr. Yakov Woldman
Associate Professor
Valdosta State University

Hosting Dept: Chemistry


Abstract:  In this presentation author discusses the role of nitric oxide in various physiological processes and methods of its detection. The challenge in the detection of nitric oxide originates form extremely low (sub-nanomolar)physiological concentrations. The method suggested allows for measuring nitric oxide production using its natural target - soluble guanylyl cyclase (sGC). Guanylyl cyclase catalyzes the conversion of guanosine triphopshate into guanosine 3', 5'-cyclic monophosphate and inorganic pyrophosphate. The rate of the reaction increases about 200 times upon NO binding with sGC, providing thereby sensor for nitric oxide. The luminescent detection of the above reaction was accomplished by converting inorganic pyrophosphate into ATP with the help of enzyme ATP sulfurylase; ATP, in its turn, was detected in chemiluminescent luciferin-luciferase reaction. The developed luminescent approach allows for measuring the rates of NO generation as low as 1 nM/min.

Thursday,  September 17, 2009 4pm

Sponge-associated microbes: the population and their biotechnological potential

Peter J. McCarthy, Ph.D.
Research Professor Center for Marine Biomedical and Biotechnology Research
Harbor Branch Oceanographic Institute at Florida Atlantic University

Hosting Dept: Biology


Abstract:  Many marine sponges are known to harbor a large and varied population of microorganisms: representatives of the bacteria, archaea and fungi are commonly present and these may constitute as much as 60% of the sponge biomass. Over the last 25 years we have amassed a large culture collection of sponge-derived heterotrophic microbes which is a significant resource for the production of natural products used in drug discovery and also of enzymes which can be used in biomass processing. Although the culture collection contains highly diverse microbes, many questions arise: How many of the microbes present in the sponge are being cultivated? Are the cultivated microbes true residents of the sponge? And, if present, are the commonly isolated microbes found at high or low density in the sponge? The use of molecular techniques has allowed us to start to understand the microbial population present in both shallow water sponges such as Axinella corrugata and deep water Lithistid sponges: Culture-independent 16S rDNA libraries have shown the diversity of microbes while the use of Real Time PCR has quantified both cultivated and uncultivated microbes present in the sponges. Such results are beginning to answer fundamental questions and are guiding us in the development of techniques to cultivate additional groups of microbes.

Thursday,  September 24, 2009 4pm

A marriage of discrete and continuous math - or, how to keep your roommates happy

Charles Kicey, Ph.D.
Math and Computer Science, VSU

Hosting Dept: Math and Computer Science


Abstract:  Generally mathematical subjects and methods are classified as either discrete or continuous; certainly both these branches of mathematics have and continue to increase in their sophistication. However, often the breakthroughs occur (scientifically as well as pedagogically) when connections are made between two, simple, but seemingly unrelated concepts. In this presentation we will illustrate this power. An application to human behavior will be presented for motivation and solved.

Thursday,  October 1, 2009 4pm

Integrative Perspectives on Sex and Aggression: One fish, two fish, red fish….black fish

Ryan Early
University of Alabama

Hosting Dept: Biology


Abstract:  Animals must make critical decisions on a minute-by-minute basis. Some of these decisions, such as whether to persist or flee in an aggressive contest, result in pronounced changes in behavioral and endocrine state. Other decisions, such as whether to be male or female, result in wholesale changes in the phenotype. My laboratory focuses on how animals, particularly fish, translate their social environment and individual social experiences into behavioral/phenotypic change. This requires that we tune into neurobiological, endocrine, and physiological substrates that are sensitive to social input or performance in the social milieu. My seminar will begin with an overview of the types of questions we address in my research laboratory at the University of Alabama. I will then focus on what we’ve done to understand how fish utilize social information to drive future decisions regarding reproductive allocation (i.e., whether to be male or female). Lastly, I will present some “hot off the press” findings that implicate the physical environment as essential in generating behavioral and life history variation in a clonal vertebrate, the mangrove killifish.

Thursday, October 8, 2009 4pm

Functional Relationships between Bats and Their Habitat

Dr. Holly Ober
Assistant Professor
Department of Wildlife Ecology and Conservation University of Florida

Hosting Dept: Biology


Abstract:  The day-to-day research conducted in many scientific fields revolves around the testing of theories.  However, much of the research currently taking place in the field of wildlife ecology is far removed from ecological theory.  This has led to a great deal of repeated efforts among researchers and limited overall progress in the ultimate goal of the discipline to gain a fundamental understanding of basic principles.  Bats are a taxa that has received scant research attention, due in part to the difficulties associated with studying activity patterns of cryptic, nocturnal species.  I will discuss how we used a hypothesis-driven approach to examine linkages in riparian food webs in forests of the Pacific Northwest in an effort to gain a better understanding of foraging ecology of bats.

Thursday,October 15, 2009 4pm

Diamondback Terrapins: Problems and Solutions.

Dr. Joseph Butler
Professor, Department of Biology
University of North Florida, Jacksonville, FL

Hosting Dept: Biology


Abstract:  Diamondback terrapins (Malaclemys terrapin) range from Cape Cod Bay south to Corpus Christi, Texas. I have studied them for nearly 15 years, most of the time in Florida. During my first year I was fortunate to discover an important nesting beach near Jacksonville, and for several years thereafter, my students and I visited the beach daily during nesting season (1 May through 31 October) to search for new nests. Most nests are deposited in May and June, and hatching begins in July and continues through October. Finding nests on the day they were deposited allowed us to determine the incubation (emergence) period. When we captured females on the beach we recorded demographic data. We determined clutch size by x-raying captured gravid females and by counting eggs in deposited nests. When kept overnight for the x-ray process, the terrapins often defecated allowing us to evaluate their diet by fecal analysis. We found that they ate a mostly tiny clams and small crabs. We determined that over 80% of the nearly 500 nests per year are taken by predators, mostly raccoons. One year a graduate student did a raccoon removal study and found that nest predation decreased significantly. One of the major problems facing terrapin populations throughout their range is that they die in crab traps. We did a three-year study around the state of Florida to test by-catch reduction devices (BRDs), which limit the size of terrapin that can enter the traps. This precludes adult females from entering. We found the ~ 70% of terrapins captured in our study could have been prevented from entering if BRDs were employed. We are currently lobbying the FWC for a regulation that would require BRDs on all crab traps.

Thursday, October 22, 2009 4pm

Parasitic Genomes On the Move: A Study of Genome Rearrangement in the Phylum Apicomplexa

Jeremy DeBarry
Doctoral Candidate
Dr. Jeff Bennetzen's Genetics Lab, The University of Georgia

Hosting Dept: Biology


Abstract:  The eukaryotic phylum Apicomplexa contains many obligate intracellular parasites responsible for a wide range of both human and veterinary diseases (e.g. Malaria, Toxoplasmosis, and Theileriosis). The recent availability of annotated genome sequence data for important members of the phylum facilitates detailed comparative genomics studies. Such studies can be utilized for the discovery of the mechanisms underlying genome evolution, leading to a better understanding of the relationships between both the members within the Apicomplexa as well as between the parasites and their hosts. We have developed a gene-marker based bioinformatics pipeline to investigate genome rearrangement of 11 Apicomplexan species across 6 genera. Rearrangement between genera is extremely extensive. Conserved regions are rare between genera and appear to be totally absent between all species. This is especially surprising considering the apparent absence of transposable elements (TEs), (DNA sequences with the ability to mobilize and increase their copy number in a genome), within any of the species examined. TEs are ubiquitous in all other groups of eukaryotes studied to date, and have been shown to be the primary agents responsible for genomic rearrangements in many species. Based on these observations, it appears that there may be a different set of criteria governing genome evolution in the Apicomplexa, relative to other eukaryotes.

Thursday, October 29, 2009 4pm

How ion channels set the rhythm in pituitary cells

Dr. Joel Tabak
Assistant Scholar/Scientist
Department of Biological Science at Florida State University.

Hosting Dept: Biology


Abstract:  Neurons and many endocrine cells exhibit electrical activity. In response to a stimulus, or spontaneously, the potential across the cell membrane can rapidly increase by more than 50 mV and then rapidly decrease back to its resting level. During such an event – called action potential – calcium ions enter the cell and trigger various cellular actions such as hormone release. Cells often fire periodic bursts of action potential that lead to large calcium influx. This electrical activity is the result of differences in ionic concentration across the cell membrane and membrane potential variations occur when ions cross the membrane through ion channels. Sodium and calcium ions enter the cell and therefore raise the membrane potential, while potassium channels exit the cell, decreasing membrane potential. In this talk I will show how interactions between calcium and potassium ion channels create patterns of electrical activity in endocrine cells of the pituitary gland.

Thursday, November 5, 2009 4pm

Chemically mediated defense of the marine bryozoan, Bugula neritina, by its symbiont: bryostatins and their biosynthesis

Dr. Nicole Lopanik
Department of Biology
Georgia State University, Atlanta, GA

Hosting Dept: Biology


Abstract:  Despite recent evidence demonstrating that microbial symbionts often produce secondary metabolites found in marine invertebrates, there are few documented instances of these symbiont-synthesized metabolites playing a role in the survival of the host. Larvae of the sessile marine invertebrate Bugula neritina (Bryozoa) are protected by an effective chemical defense. From the larvae, we isolated three bryostatin-class macrocyclic polyketides, including the novel bryostatin 20, that deterred feeding by a common planktivorous fish that co-occurs with B. neritina. A unique uncultured bacterial symbiont of B. neritina, “Candidatus Endobugula sertula”, was hypothesized as the putative source of the bryostatins. Our research has demonstrated that bryostatins are concentrated in the larvae of B. neritina and protect them against predation by fish, and that bryostatin concentrations decrease as B. neritina ages. Furthermore, aposymbiotic B. neritina larvae were not deterrent and lacked bryostatins, suggesting that the bryostatins are most likely produced by “Ca. Endobugula sertula”. We have isolated a polyketide synthase gene cluster from symbiont-enriched samples of B. neritina that may biosynthesize the bryostatins. This cluster has several enzymatic domains that indicate that it is responsible for making characteristic additions to the pre-bryostatin polyketide chain, and some of these have been shown to function in vitro. This research represents the first example from the marine environment of a microbial symbiont producing an anti-predator defense for its host, and in this case, specifically for the host’s larval stage, which is exceptionally vulnerable to predators.


Thursday, November 12, 2009 4pm

A fish-eyed view of eye development and disease

Dr. James M. Fadool
Associate Professor
Department of Biological Science
Florida State University

Hosting Dept: Biology


Abstract:  The goal of our laboratory is to develop animal models of genetic diseases affecting the eye. Heritable diseases are among the leading causes of blindness in developed countries. Retinitis pigmentosa and allied dystrophies represent a heterogeneous collection of diseases that affect the function and survival of the photoreceptor cells of the retina, in many cases leaving the second order neurons intact. Similarly, the genetic basis of numerous diseases affecting the lens, such as dominant cataracts, aniridia, glaucoma, etc. have been identified or linked to some forms of the diseases. To accelerate research, we use the zebrafish, a small aquarium fish that is readily adapted to the laboratory as a genetic model. We have isolated lines that show increased neural degeneration, altered cell numbers and various defects of the lens. Surprisingly, several of the degeneration models also stimulate the remarkable regenerative capacity of the fish providing new avenues of investigation.


Thursday, November 19, 2009 4pm

End of semester