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Abstracts Fall 2005

New Animal Models to Study Bioavailable Metals and Mutation Rates

Travis Glenn
Savannah River Ecology Lab, University of Georgia

16 Sep 2005

Heavy metals are increasingly common environmental contaminants.  Although metals can be measured very accurately by chemical methods, predicting the biological effects of the metals in particular environments can be challenging. New model organisms are needed to better understand bioavailability and the biological effects of metals, especially as part of contaminant mixtures. I will present ongoing collaborative research in which we have developed: 1) new strains of transgenic C. elegans that report bioavailable metals, and 2) new markers to directly measure germ-line mutation rates in medaka (aka Japanese rice fish). I will also highlight how the approach used to make the transgenics can be used to study any contaminants of interest (e.g., Arabidopsis) and how mutation rates can be estimated in any eukaryotic organism (e.g., alligators).

 

Improved Growth Rate and Disease Resistance in Farmed Abalone Haliotis midae through Probiotic Treatment

Brett Macey, Grice Marine Laboratory, College of Charleston

23 Sep 2005

Disease has had a severe impact on the international aquaculture industry and is anticipated to become an increasingly important factor, together with the slow growth rate of Haliotis midae, that will negatively impact on the further development and success of the South African abalone mariculture industry. Thus, the future of H. midae mariculture in South Africa depends in part on the development of methods to enhance the growth rate and disease resistance of farmed abalone. The use of probiotics in aquaculture is proving to be highly effective in improving disease resistance, nutrition and/or growth of cultured organisms. I have isolated three enteric microorganisms from the digestive tract of H. midae that are capable of hydrolyzing various protein and starch substrates included in formulated abalone feeds. The three microorganisms significantly increased the amount of protein digestion and absorption in the abalone gut and an assessment of different immune parameters demonstrated the immunostimulatory effect of the three putative probionts included in the diet fed to farmed abalone. Furthermore, I have shown that H. midae fed the probiotic-supplemented diet have an improved survival and growth rate compared to animals not fed probiotics. The microorganisms tested in this study therefore have tremendous potential as probiotics for commercially produced Haliotis midae.

 

 

 

Secondary Metabolic Pathways from the Marine Realm: Mining a Unique Treasure Chest of Biodiversity

Jose V. Lopez, Division of Biomedical Marine Research, Harbor Branch Oceanographic Institution

14 Oct 2005

A growing number of unique and potent natural products (secondary metabolites) are being discovered from marine habitats and organisms.  Untapped macro- and microorganismal diversity in the oceans forms the basis of the observed biochemical phenotypes.  Our molecular biology research in the Division of Biomedical Marine Research at HBOI, aims to isolate and characterize the genetic factors responsible for marine secondary metabolite biosynthesis.  Since many new compounds may be microbial in origin, part of the research focuses on identifying potential microbial sources living within complex communities (sponges) through molecular taxonomic surveys and inventories.  Molecular biology has also enabled culture-independent strategies to identify gene sequences potentially involved in brevetoxin biosynthesis, and also in horizontal gene transfer of secondary metabolite genes among disparate species.  Lastly, transcriptome-based methods are now being applied as a more direct route for isolating secondary metabolite-associated genes and transcripts from marine organisms.

 

The Invasion of Red Lionfish, Pterois volitans, to Marine Ecosystems Off the Southeastern United States: Past, Present, and Future

Scott Meister, South Carolina Department of Natural Resources

21 Oct 2005

Red lionfish, Pterois volitans, a marine scorpionfish indigenous to coral reefs in the Indo-Pacific region, have recently established breeding populations on reefs off the southeastern United States, representing what is believed to be the first documented successful introduction of an invasive marine fish species from the western Pacific to Atlantic coastal waters of the United States.  Using photographic and videographic evidence, in addition to specimen collection, adult-sized individuals have been documented on live-bottom reefs and man-made structures off the Carolinas, Georgia, and Florida at depths ranging from 40-99 m.  Additionally, juveniles have been collected in coastal estuaries off New York, providing strong evidence of reproduction occurring to the south, with egg and larva transport facilitated by the Gulf Stream.  Using meristic and morphological characters, 14 of the 72 specimens documented in this study were positively identified to species level as P. volitans, however the possibility exists that more than one species is involved in the invasion.  Although it is inherently difficult to determine the initial source of introduction of many invasive species, it is believed that captive lionfish were accidentally released into Florida east coast waters in 1992 as a result of Hurricane Andrew.  Being a venomous top-level predator in their native range, the potential impact of this invader on southeastern marine ecosytems is great.

 

Aspects of lionfish life history, especially reproductive biology and food habits, must be investigated throughout their invasive range to provide baseline data and to pinpoint the potential impacts of their establishment in western North Atlantic waters.  As lionfish populations in the southeast continue to expand, DNA sequencing of individuals across their invasive range should be performed to determine if numerous independent introductions have occurred, and nuclear markers should be used to potentially determine parentage.

 

Probing Heterotrimeric G-protein Signaling using High-resolution NMR

John Marino, NIST, Center for Advanced Research in Biotechnology

28 Oct 2005

G-protein coupled receptors (GPCR's) represent a diverse group of seven transmembrane helix receptors that require ligand-dependent activation to initiate heterotrimeric (abg) G-protein mediated intracellular signaling cascades.  Activation of a G-protein by its agonist stimulated GPCR (R*) requires the propagation of structural signals from the receptor binding interface to the guanine nucleotide-binding pocket.  The structural basis for the interaction of a GPCR with its cognate G-protein and the subsequent activation of the G-protein by R* is not well understood.  Using light-activated signaling of the G-protein, transducin (Gt), by rhodopsin as a model system, the interaction of G-protein with solubilized native receptor, as well as a soluble mimic of R*, is being probed using high-resolution NMR methods.  Selective stable isotope labeling and mutation of the G-protein a-subunit (Ga) has allowed the detection of structural and dynamic changes in Ga that correlate with heterotrimer formation, receptor interaction and guanine nucleotide exchange.  Analysis of the conformations of the different functional states of Ga and their implications for how signals may propagate from the receptor to the guanine nucleotide-binding pocket of Ga will be presented.

 

Osmoregulation in Estuarine Crabs: Using Cell and Molecular Biology, but Remembering the Whole Organism

Don Lovett, Department of Biology, The College of New Jersey

18 Nov 2005

The Atlantic blue crab, Callinectes sapidus, is a strong hyper-osmoregulator in dilute seawater.  Although it has been known that a number of cellular and physiological changes occur when the crab acclimates to low salinity, most studies have compared crabs acclimated to low salinity with crabs acclimated to high salinity.  Specifically, acclimation to low salinity is accompanied by a dramatic increase in the activity of Na+,K+-ATPase in the gills, the primary organ for osmoregulation, and changes in the ultrastructure of cells in the gills.  Both of these changes are preceded by up-regulation of some genes.  However, early studies failed to detect changes in gene expression because only fully-acclimated animals were examined.  These findings have led us to examine a number of short-term and long-term mechanisms that may be involved in modulating the crab's response to changes in salinity.

 

Larval Dispersal and Local Adaptation of Nearshore Marine Invertebrates

Erik Sotka, Grice Marine Laboratory, College of Charleston

2 Dec 2005

The degree by which marine organisms adapt to local habitats depends largely on the strength of local selection and the homogenizing effect of dispersal.  In this talk, I'll use several marine invertebrates to discuss 1) how restricted gene flow can promote adaptation to local habitats, and conversely, 2) how local adaptation can promote restricted gene flow.  Such issues become important in an era of increasing human impacts: can local marine organisms adapt to profound alterations in habitat in order to persist?