11th ICRS Abstract book - Nova Southeastern University

Poster Mini-Symposium 5: Functional Biology of Corals and Coral Symbiosis: Molecular Biology, Cell Biology and Physiology
5.149
Quantum Efficiency For Light Enhanced Ros Production in Corals; A Physiological
Approach To Predict Bleaching
Racheal HOWARD* 1 , Paul FALKOWSKI 2,3
1 SIO, UCSD, La Jolla, CA, 2 IMCS, Rutgers, New Brunswick, NJ, 3 IMCS, Rutgers, New
Brunswick
Existing probability models for coral bleaching report sea surface temperature anomalies,
but are limited by the absence of a mechanistic understanding of the photophysiological
contribution to bleaching. Light is critical for Scleractinian corals, yet the ability to
evolve oxygen in close proximity to high potential redox carriers invites the production
of extremely damaging oxidizing molecules, particularly at high photon densities. We
show evidence that photosynthetically derived reactive oxygen species (ROS) induce
bleaching. We provide a mechanistic model derived from in situ quantitative measures
for light dependent ROS production, corrected for temperature, to be incorporated with
existing probability based satellite data to predict global bleaching events.
5.150
Pocillopora Genotypes May Determine Colony Specificity Between Two Symbiont
Species in The Eastern Pacific
Jorge PINZÓN* 1 , Todd LAJEUNESSE 1
1 Biology, Pennsylvania State University, University Park, PA
Pocillopora in the eastern Pacific associate with two species of Symbiodinium. Different
colonies of Pocillopora spp. contain unique and stable associations with either
symbiodinium type D1 or type C1b-c. The establishment and evolution of unique hostsymbiont
associations has been attributed to several factors including environmental
conditions, geographical isolation, the taxonomic identity of the host and the symbiont, or
any combination of them. In La Paz, Baja California, Pocillopora spp. colonies with
similar partner combinations to those found elsewhere in the eastern Pacific coexist under
the same environmental conditions. This indicates that external environmental conditions
have limited influence on the formation and stability of these associations. Genetic
analysis using two microsatellite markers suggests that the population of Pocillopora
colonies that host Symbiodinium D1 have different alleles and allelic frequencies than the
population of colonies hosting C1b-c. Differences among host genotypes may explain, in
part, the distribution of one species of symbiont over another in colonies exposed to
identical environmental conditions. Such patterns suggest the importance of co-evolution
in the formation of specific interactions among corals and their endosymbionts.
5.151
Zooxanthellae Population Dynamics And Temporal Coral Growth Rate Variations in
acropora Formosa From The Mauritian Waters
Ranjeet BHAGOOLI* 1 , Indurlall FAGOONEE 1
1 Department of BioSciences, University of Mauritius, Reduit, Mauritius
We quantified temporal and spatial variations in zooxanthellae (endosymbiotic dinoflagellates,
Symbiodinium spp.) density, zooxanthellae volume, zooxanthellae mitotic index (MI) in the
highly common coral Acropora formosa and coral linear extension rate at three Mauritian
lagoons namely Balaclava Marine Park, Flic-en-Flac and Trou aux Biches to monitor the health
of coral reefs. Physical parameters such as temperature, dissolved oxygen, nitrate, nitrite and
phosphate concentrations, ultraviolet radiation, pH and salinity were also monitored. Monthly
sunshine and rainfall data were also gathered. Data collected from 1991 to 1998 on a weekly
basis showed a three-fold higher zooxanthellae density, smaller zooxanthellae volume, lower
MI and lower linear coral branch extension rates than in summer. The nitrogen to phosphate (N:
P) ratio, temperature, UVB and amount of sunshine hours were higher in summer. These
results suggest that a non-carrying capacity zooxanthellae density level along with a normal
summer maximum temperature and high N: P ratio allowed Acropora formosa to grow at its
optimal level in the lagoonal waters of Mauritius.
5.82
Heat Shock Protein 90 and nitric oxide co-regulate thermally-induced bleaching in the soft
coral Eunicea fusca
Cliff ROSS* 1 , Lory SANTIAGO 2
1 Dept. of Biology, University of North Florida, Jacksonville, FL, 2 School of Science and
Computer Engineering, University of Houston, Clear Lake, Houston, TX
Heat-shock protein 90 (Hsp90) is a molecular chaperone involved in cellular signaling in a
variety of metabolic systems. While thermotolerance studies in corals have been successful in
designating heat shock proteins as useful biomarkers for measuring abiotic stress, studies
evaluating their plausible functional role(s) in situ are still lacking. In this study, using the soft
coral Eunicea fusca, we demonstrate that thermally-induced stress causes an upregulation in
HSP90. In turn, HSP90 shows a concomitant ability to activate nitric oxide synthase. The
resulting production of nitric oxide (NO) may act as a signaling molecule capable of inducing
zooxanthellae expulsion.
Using nitric oxide synthase (NOS) and Hsp 90 polyclonal antibodies, thermally stress induced-
HSP 90 was shown to co-immunoprecipitate with a constitutive isoform of nitric oxide
synthase. The specific blocking of Hsp90 activity, with the HSP90 inhibitor geldanamycin, was
capable of inhibiting NO production suggesting the involvement of a coordinated regulatory
system.
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