11th ICRS Abstract book - Nova Southeastern University

Poster Mini-Symposium 5: Functional Biology of Corals and Coral Symbiosis: Molecular Biology, Cell Biology and Physiology
5.87
Growth Rate, Survivorship and Stress Tolerance of Primary Polyps of Acropora
digitifera Infected with Zooxanthellae of Different Genotypes
Ryota SUWA* 1 , Michio HIDAKA 2
1 Department of Marine and Environmental Sciences, Graduate School of Engineering
and Science, University of the Ryukyus, Nishihara-cho, Japan, 2 Department of
Chemistry, Biology and Marine Science, Faculty of Science, University of the Ryukyus,
Nishihara-cho, Japan
The objective of this study was to examine the effects of zooxanthella genotypes on the
growth rate and stress susceptibility of the coral Acropora digitifera during the early
stages of development. Aposymbiotic primary polyps of A. digitifera were infected with
zooxanthellae isolated from various hosts and their growth rate and survivorship were
observed under different conditions. The rate of infection varied depending on
zooxanthella genotypes. Clade A zooxanthellae isolated from the giant clam Tridacna
crocea were most rapidly incorporated by the polyps and the algal density increased even
under high temperature conditions, while homologous zooxanthellae (clade C) were
incorporated only very slowly. The growth rate of the polyps was different among polyps
harboring zooxanthellae of different types. The highest growth rate was observed in
polyps harboring clade A zooxanthellae from T. crocea. The stress tolerance of primary
polyps harboring the clade A zooxanthellae was higher than polyps harboring clade C
zooxanthellae from the sea anemone Aiptasia pulchella or than uninfected polyps. Thus
the clade A zooxanthellae from T. crocea appear most beneficial for primary polyps of A.
digitifera and association with this zooxanthellae is expected to be predominant in the
reefs. However, corals harboring clade A zooxanthellae are rare in the study site, where
T. crocea is abundant. This is probably because suitable symbiont type is different
between juvenile and adult colonies, and/or juvenile corals are more flexible with
symbiont types than adult colonies. Another possibility is that clade A zooxanthellae
were not selected by the coral because symbionts with a much faster growth rate than
host may present a risk of parasitism for the host coral.
5.88
Ultraviolet-Induced Dna Damage And Its Subsequent Repair in Field-Collected
aiptasia Pallida as Monitored By Single-Cell Gel Electrophoresis
Claire HUDSON* 1 , Drew FERRIER 1
1 Department of Biology, Hood College, Frederick, MD
Ultraviolet radiation (UVR) is a commonly occurring genotoxic stress in tropical marine
environments. Shallow-water organisms have a variety of defenses against UVR.
However, DNA damage from UVR still occurs. The exposure to UVR creates unique
forms of damage, primarily as cyclobutane pyrimidine dimers and 6-4 photoproducts.
These types of damage can subsequently be restored by nucleotide excision repair (NER)
or via light-mediated reactions. Single-cell gel electrophoresis (the comet assay) can be
used to quantitate DNA strand breaks created during NER. We optimized the comet
assay to monitor DNA damage in host cells of the zooxanthellate sea anemone Aiptasia
pallida. Following optimization, we documented the extent of DNA damage and the
subsequent repair response in freshly collected A. pallida under simulated field
conditions at the Bermuda Institute for Ocean Sciences. We also determined the types
and amounts of mycosporine-like amino acids (MAAs) that confer protection from UVRinduced
DNA damage. We found that host tissue of field anemones contain a variety of
MAAs, tentatively identified as mycosporine-2-glycine, mycosporine glycine, shinorine
and porphyra-334. Repair of DNA damage incurred from a daily dose of UVR occurred
within eight hours after sunset, with NER taking place during the first 2 hr of recovery in
the dark. These findings suggest that under natural conditions, DNA damage incurred
from UVR does not accumulate from one day to the next in A. pallida.
5.89
Effect Of Caffeine On Coral Symbionts
Kelly POLLACK* 1 , Kimberly BALAZS 2 , Oladele OGUNSEITAN 3
1 School of Social Ecology, University of California, Irvine, Irvine, CA, 2 School of Biological
Sciences, University of California, Irvine, Irvine, CA, 3 School of Social Ecology & Program in
Public Health, University of California, Irvine, Irvine, CA
Caffeine is a ubiquitous tracer of urban wastewater but its ecological effects have not been
adequately studied. Here we report the effect of caffeine on the growth and protein synthesis in
four species of coral algae endosymbionts. We hypothesized that caffeine exposure is associated
with coral bleaching. After 40 days of incubation with various concentrations of caffeine (0 to
100 mg/L) we estimated the minimum inhibitory concentration (MIC) of caffeine are 30 mg/L
for Clade C Symbiodinium goreaui (C), 30 mg/L for Clade B Symbiodinium sp. from
Pseudoterogorgia bipinnata (B7), 50 mg/L for Clade A Symbiodinium microadriaticum (A),
and 75 mg/L for Clade B Symbiodinium sp. from Aiptasia pallida (B6). To explore the effect of
caffeine on proteins we used 2-D gel electrophoresis and peptide mass spectrometry to identify
sensitive proteins. The results show 12 polypeptide spots upregulated and 37 polypeptide spots
downregulated in C, 19 upregulated and 6 downregulated in B7, 14 upregulated and 13
downregulated in A, and 22 upregulated and 7 downregulated in B6. The heat shock protein
HSP70 is among the commonly affected proteins indicating that stress from caffeine exposure
in natural waters may exacerbate the effects of stress from other environmental factors.
5.90
Dna Repair in aptasia Pallida Following Laboratory Exposures To Ultraviolet Radiation
Drew FERRIER* 1 , Claire HUDSON 1
1 Department of Biology, Hood College, Frederick, MD
Cnidarians that inhabit shallow marine environments in tropical latitudes receive substantial
exposure to ultraviolet radiation (UVR). It is well known that UVR damages the DNA of
exposed organisms by creating cyclobutane pyrimidine dimers and 6-4 photoproducts. Damage
may be subsequently repaired through nucleotide excision repair (NER) or directly by lightmediated
reactions using photolyase. Neither of these mechanisms has been well-studied in
cnidarians. We employed the comet assay to document DNA damage from UVR and
subsequent DNA repair under laboratory conditions in the sea anemone Aiptasia pallida. We
used aposymbiotic animals in initial studies. Anemones cultured in the laboratory contain very
low levels of UVR-absorbing mycosporine-like amino acids and thus serve as ideal models for
investigating damage due to UVR. At levels of exposure < 62 kJ m -2 , DNA damage in animal
nuclei increased with increasing exposure to UVR. However, at higher levels of exposure,
DNA damage reached an asymptote. To assess the time-course of repair we subjected anemones
to ~ 30 kJ m -2 of UVR and then kept them in the dark. These animals exhibited a delay of
approximately 4 hours in the initiation of NER. However, this repair mechanism, once
initiated, reduced DNA damage to near pre-exposure levels within 8 hours. Simultaneous
exposure of anemones to both UVR and visible light greatly reduced the amount of DNA
damage. This suggests that light-mediated DNA repair also plays an important role in
anemones and is likely the first line of defense against cumulative DNA damage by UVR in
these animals.
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