11th ICRS Abstract book - Nova Southeastern University

Poster Mini-Symposium 5: Functional Biology of Corals and Coral Symbiosis: Molecular Biology, Cell Biology and Physiology
5.124
Different sensitivity of zooxanthellae types isolated from the corals Madracis and
Agaricia to increasing temperature
Petra VISSER* 1 , Pedro FRADE 2 , Rolf BAK 2
1 Aquatic Microbiology, University of Amsterdam, Amsterdam, Netherlands, 2 Marine
Ecology & Evolution, NIOZ, Den Burg-Texel, Netherlands
The coral genera Madracis and Agaricia are abundant in the Caribbean reefs and harbour
zooxanthellae of clade B and C, respectively. Madracis corals hardly bleach, while
Agaricia corals bleach frequently. Can this difference be explained by the physiological
response to temperature of the Symbiodinium types they harbour? First, we investigated
by genetical analysis which zoox types are present at different depths and in different
coral species of these genera. Second, we performed experiments with coral fragments
and zooxanthellae isolated from these coral genera at different temperatures. We
hypothesized that the zoox from the coral Agaricia lamarcki, which bleaches more
frequently than Madracis senaria, have a higher temperature sensitivity than the zoox
from M.senaria. Experiments were performed in which the photosynthetic yield was
measured after small steps of increasing temperature. We didnot observe a difference
between the species in the average temperature at which the photosynthesis yield
collapsed, but we did find a faster decrease in photosynthesis yield in the range 26-32
degrees. To investigate this further, we will compare the lipid composition (ratio of
unsaturated and saturated fatty acids) and the formation of ROS of the symbionts at high
temperature.
5.125
Genetic Diversity within the Endolithic Alga Ostreobium quekettii that Harbor the
Scleractinian Corals Skeleton
Eldad HOCH* 1,2 , Maoz FINE 1,2
1 Bar-Ilan University, Ramat Gan, Israel, 2 The Interuniversity Institute for Marine
Science, Eilat, Israel
For a couple of decades researchers had focused on the symbiotic dinoflagellate alga
Symbiodinium, residing in the endodermal tissue of reef building corals. Another
associate partner which has been largely over looked is the green alga Ostreobium.
Endolithic in nature, this alga reside in the skeleton of scleractinian corals, forming a
distinctive green band, a few millimeters beneath the coral tissue. It has been
demonstrated, that this alga plays a role in the physiology and metabolism of corals. An
Uptake of photoassimilates by the coral has been shown using a carbon tracer in
azoxanthellate corals. Furthermore, in bleached coral colonies, the endolithic alga can be
an alterative source of energy as they increase their biomass in the bleached areas of the
colony and help the coral to survive during a low energetic state period. This alga is well
dispersed among the marine environment, from colder environments of the North-
Western Pacific to warmer climates including the Mediterranean Sea and tropical oceans.
The alga is abundant in almost all corals species (98%). Ostreobium is also present in
corals over a wide scale water depth gradient, from the shallow to the depths of more
then 100 meters.
Except for one study that questioned the genetic variability of Ostreobium based on
morphology only, most studies refer to it as quekettii or sp. across oceans and regions. In
this study we aimed to characterize the genetic variability of Ostreobium based on DNA
phylogenetic markers ITS1 and ITS2. We successfully extracted DNA from skeletons of
several corals belonging to 6 species of corals from the Mediterranean Sea and the Red
Sea. Screening these amplified markers showed variability between Ostreobium from
different regions, depth and species. We hypothesize that a vast genetic variability of
Ostreobium exists between regions and ecological niches.
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Pigments As Indicators Of Stress Mechanisms in Corals
Kathleen MCDOUGALL* 1 , Angela SQUIER 1 , Kenneth BOYD 1 , Stuart GIBB 1 , Craig
DOWNS 2 , Barbara BROWN 1,3
1 Environmental Research Institute, North Highland College, UHI Millennium Institute, Thurso,
United Kingdom, 2 Haereticus Environmental Laboratory, Clifford, VA, 3 School of Biology,
University of Newcastle, Newcastle upon Tyne, United Kingdom
The loss of algal pigments from zooxanthellae is associated with environmental stress in corals,
however, relatively little attention has been paid to these pigments as biomarkers to investigate
the mechanisms that operate during such stress events. We have previously proposed a suite of
chlorophyll a-like compounds as early biomarkers of stress in coral zooxanthellae. Generation
of the chlorophyll-a like compounds was first noted through retrospective data analysis of high
performance liquid chromatography (HPLC) pigment analyses of algal symbionts from the
shallow water coral Goniastrea aspera in Phuket, Thailand. Higher concentrations of a sub-set
of these chlorophyll a-like products were observed in response to both elevated light and
temperature, providing significant potential as biomarkers of stress in corals. These compounds
have subsequently been seen in the branching corals Porites compressa and Pocillopora
damicornis under laboratory conditions and been shown to be more sensitive than the
xanthophyll ratio or fatty acid profiles as indicators of stress. In order to investigate these
compounds further we proposed to develop model systems to study their formation. Utilising
the macroalga Enteromorpha linza as a readily available model of a photoautotroph which
undergoes bleaching in response to high levels of solar irradiance, we have found the same
chlorophyll a-like compounds present under different environmental conditions as in the coral
zooxanthellae. Additionally, the compounds can be generated in vitro from chlorophyll a using
copper and hydrogen peroxide. Using liquid chromatography-atmospheric pressure chemical
ionisation multistage mass spectrometry (LC-APCI MSn) the compounds produced were
identified as the chlorophyll a oxidation products 132(R)- and 132(S)-hydroxychlorophyll a and
Mg-purpurin-7 dimethyl phytyl ester. The characterisation of these compounds and the
evidence that they are produced under oxidative conditions indicates their potential as
biomarkers of oxidative stresses in corals.
5.128
Regulation Of Gfp-Like Protein Expression in Reef-Building Corals
Joerg WIEDENMANN* 1,2 , Cecilia D'ANGELO 2 , Andrea DENZEL 2 , Alexander VOGT 2 ,
Mikhail MATZ 3 , Franz OSWALD 2 , Anya SALIH 4 , Ulrich NIENHAUS 2
1 National Oceanography Center, University of Southampton, Southampton, United Kingdom,
2 University of Ulm, Ulm, Germany, 3 University of Texas, Austin, TX, 4 University of Western
Sydney, Sydney, Australia
GFP-like fluorescent and colored proteins are responsible for the startling colorful appearance
of hermatypic corals, yet the physiological function of these pigments remains unclear. Precise
understanding of the mechanisms driving their expression is imperative to use these proteins as
intrinsic optical markers of physiological conditions and/or genetic affinity. We have analyzed
the influence of different environmental factors on the regulation of major classes of GFP-like
pigments in corals of the taxa Acroporidae, Merulinidae and Pocilloporidae. The differential
expression patterns were studied by spectroscopic measurements on animals, through
immunochemical analysis of purified extracts and by semiquantitative RT-PCR analysis. We
found that light excerted a strong control of the pigment levels in the tissue of all studied
species. Exposure of the animals to different light qualities established that the increase in coral
pigmentation is primarily dependent on blue light. GFP-like proteins were also differentially
regulated at the transcriptional level by environmental stress factors like heat and cold stress.
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