11th ICRS Abstract book - Nova Southeastern University

Poster Mini-Symposium 5: Functional Biology of Corals and Coral Symbiosis: Molecular Biology, Cell Biology and Physiology
5.120
Surface Proteins Identification Of Symbiotic Gastrodermal Cells in Hermatypic
Coral Euphyllia Glabrescens
Chih-Yao CHANG* 1 , Shao-En PENG 1,2 , Chii-Shiarng CHEN 1,2
1 Institute of Marine Biotechnology, National Dong Hwa University, Pingtung, Taiwan,
2 Coral Research Center, National Museum of Marine Biology and Aquarium, Pingtung,
Taiwan
Regulatory mechanism of marine symbiosis in Cnidarian-dinoflagellate association
remains unclear notwithstanding decades of research. Symbiotic gastrodermal cell
membrane may play important roles in the process of initiation and maintainence of this
endosymbiosis. In order to investigate interactions between symbionts and their host,
preparation of homogeneous gastrodermal cells and culture are prerequisite. Here, we
first examine cell surface proteins of symbiotic gastrodermal cells by a chemical
biotinylation process. The intactness of symbiotic gastrodermal cells and successful
protein biotinylation are shown by confocol microsopy and transmission electron
microscopy. We next to seek identify these biotinylated symbiotic gastrodermal cells
surface membrane specific proteins by 2D SDS-PAGE. Furthermore, two-dimensional
distribution pattern of biotinylated proteins of symbiotic gastrodermal cells are affected
by light irradiation, and show significant difference from that of cultural Symbiodinium. It
indicates a specific labeling of surface proteins and a high light sensitivity of the isolated
gastrodermal cellular membrane. Ongoing work focuses on the identification of
biotinylated proteins, and their future usage in identifying aposymbiotic gastrodermal
cells.
5.121
Symbionts Are A Deadly Burden For Coral Larvae
Andrew BAIRD* 1 , Irina YAKOVLEVA 2
1 James Cook University, townsville, Australia, 2 Institute of Marine Biology, Vladivostok,
Russian Federation
Mutualisms are often viewed as reciprocal exploitations that nonetheless provide net
benefits to each partner. Any feature that aligns the interests of the partners should
promote long-term stability in the association. For example, passing symbionts directly
from parent to offspring should benefit the host by reducing conflict between diverse
symbionts, and benefit the symbiont by guaranteeing transmission. However, in some
symbiotic associations, such as those between corals and zooxanthellae, vertical
transmission is rare, suggesting a substantial cost. Here we show that coral larvae with
zooxanthellae had lower survivorship than larvae of the same species that lacked
zooxanthellae when exposed to high levels of temperature and ultraviolet radiation
(UVR). Higher activity of antioxidant defenses and higher levels of oxidative cellular
damage observed in symbiotic larvae under high temperature and UVR exposures
suggest that reactive oxygen species, produced by the overload of the photosynthetic
apparatus of the zooxanthellae, are responsible for these higher rates of mortality.
Symbionts are clearly a costly burden early in the life history of broadcast spawning
corals under stressful environmental conditions.
5.122
Telomerase Activity And Telomere Sequence in The cassiopea Jellyfish
Michiko OJIMI* 1 , Naoko ISOMURA 1 , Michio HIDAKA 1
1 University of the Ryukyus, Nishihara, Japan
The scyphistome of the jellyfish Cassiopea sp. form vegetative buds, which detach from the
scyphistome and metamorphose into polyps (scyphistomes). Once polyps are infected with
zooxanthellae, they form medusae via strobilation. While the asexual reproduction cycle via
asexual propagules seems to continue endless in a laboratory condition, medusae, which do
sexual reproduction, might be mortal. The underlying mechanisms of this difference in the life
span between the polyp and medusa stages are not understood.
Telomeres, the repetitive nucleotide sequences with associated proteins at the ends of
eukaryotic chromosomes, generally become shortened during cell division and the length of
teleomeres is considered to reflect age of the cells. As the first step to understand the different
life spans of the polyp and medusa stages of Cassiopea sp., we measured telomerase activity in
polyps and young medusae using the stretch PCR method, which was designed to amplify DNA
fragments with telomere sequence, (TTAGGG) n. We found telomerase activity in tissues of
aposymbiotic and symbiotic polyps, asexual propagules and young and adult medusae, though
the success rate of detection varied between stages. We cloned and sequenced the PCR products
and the amplified fragments contained (TTAGGG) n. The present finding that the Cassiopea
jellyfish has the evertebrate f telomere motif of (TTAGGG) n is consistent with recent
studies on corals and other cnidarians (Sinclair et al. 2006; Traut et al. 2007). Although the
telomerase activity was detected in both polyp and medusa stages, further quantitative analyses
of telomerase activity might reveal the underlying mechanisms of different life span of the
polyp and medusa stages of the jellyfish.
5.123
The Effect Of Temperature On The Zooxanthellae Cell Proliferation
Yi-Cheng LEI* 1 , Li-Hsueh WANG 1,2 , Hsieh-He LI 1 , Chii-Shian CHEN 2
1 Institute of Marine Biotechnology, National Dong Hwa University, Hualien, Taiwan, 2 Coral
Research Center, National Museum of Marine Biology and Aquarium, Pingtung, Taiwan
Coral reefs turn visibly pale, also known as coral bleaching, due to loss of their symbiotic
dinoflagellate while exposed to high light intensity and elevated water temperature. Under these
stresses, dysfunctional zooxanthellae were released from the cnidarian hosts. Depending upon
the cnidarian species, there are various levels of bleaching in response to the same temperature,
suggesting that there may be difference in temperature tolerance for each specific
zooxanthellae. To understand how temperature affects zooxanthellae and induces coral
bleaching, we examined cell proliferation and photosynthetic efficiency in zooxanthellae under
various temperatures. Our results revealed that at lower temperatures (i.e. 19 ), the percentage
of cells in G2/M phase dropped in the first L/D cycle, and recovered in the second L/D cycle. At
28 , the percentage of cells in G2/M phase increased to 1.5 folds of control group in both the
first and second L/D cycles. However, at 32 , the percentage of cells in G2/M phase decreased
to 0.4 to 0.5 fold of control group in the first L/D cycle and 0.2 fold of the control in the second
L/D cycle. The quantum yield of zooxanthellae was lower at 32 than at control temperature
(i.e. 25 ), and the amount of glycerol accumulation in the cell was less at 32 than at 25 ,
suggesting that the capacity of photosynthesis and carbon-fixation were reduced under elevated
temperature. The data indicate that four zooxanthellae examined exhibit similar responses with
different temperatures. In conclusion, at low temperature, cell proliferation slows down but
eventually recovered. On the other hand, cell proliferation is permanently inhibited at 32 .
Therefore, elevated water temperature poses a real threat to the population of zooxanthellae.
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