11th ICRS Abstract book - Nova Southeastern University

Oral Mini-Symposium 5: Functional Biology of Corals and Coral Symbiosis: Molecular Biology, Cell Biology and Physiology
5-22
Dynamic Establishment Of Coral-Dinoflagellate Symbioses in Heat Stressed Coral
Juveniles
David ABREGO* 1 , Bette WILLIS 1 , Madeleine VANOPPEN 2
1 School of Marine and Tropical Biology, James Cook University, Townsville, Australia,
2 Australian Institute of Marine Science, Townsville, Australia
Very little is known about how environmental conditions affect the capacity of newly
settled coral juveniles to acquire symbionts and establish the initial symbiosis. Here we
examine the uptake of Symbiodinium dinoflagellates by newly settled Acropora corals
kept at three different temperatures and two light levels including treatments typically
considered environmentally stressful. Visual scoring and cell counts of the corals
revealed a significant delay in the uptake and establishment of symbionts in high
temperatures (31 °C) and/or high light, even though the relative survival of juveniles in
these treatments was similar to those in the control temperature (28 °C) and low light.
Using real-time quantitative PCR we measured the proportion of symbionts taken up
from a pool of two phylotypes offered. In A. millepora juveniles type D Symbiodinium
was detected in higher proportions than type C1 in juveniles at high temperatures and
high light. These results suggest that type D is more competitive under environmentally
stressful conditions. By comparing the uptake patterns in A. tenuis juveniles we will
discuss the role of the host in regulating the initial establishment of the symbioses and the
generality of type D as a stress-tolerant symbiont.
5-23
Initiation Of Coral/algal Symbioses: The Role Of Cell Surface Lectin/glycan
Interactions in Recognition And Specificity
Elisha WOOD-CHARLSON* 1 , Virginia WEIS 1,2
1 Zoology, Oregon State University, Corvallis, OR, 2 Zoology, Oregon State University,
Corvallis
The majority of corals rely on horizontal transmission of the dinoflagellate symbionts
Symbiodinium spp. to perpetuate their symbiotic condition from one generation to the
next, and most coral hosts are only found in association with a specific clade of symbiont.
How do larval corals and their symbiotic algae discriminate between their preferred
partner and other hosts or microbes during the onset of symbiosis? We hypothesized that
cell surface lectin/glycan interactions act as one mechanism of recognition and specificity
during initial contact between the partners. To determine the role of these interactions
during infection, we modified the glycans on the cell surface of algal symbionts (C1f and
C31, found in nature in adult Fungia scutaria and Montipora capitata, respectively),
introduced the modified symbionts to F. scutaria larvae, and then looked for changes in
infection success. After cell surface modification, infection rates of native C1f algae
decreased. In contrast, cell surface modification of non-native C31 algae resulted in
higher infection rates compared to unmodified, control algae. These data suggest that the
symbiont cell surface plays a role in specificity between F. scutaria larvae and C1f
symbionts. To explore the source of this specificity, we investigated the variability of
glycans present on the cell surface of several clade C symbionts. We found that cell
surface glycan profiles were different for each symbiont, and we hypothesize that a
specific glycan profile serves to identify the symbiont to its host coral. Finally, we
described a complex array of C-type lectins, a type of glycan receptor, in the anemone
Nematostella vectensis genome. The diversity of glycan profiles on symbiont cell
surfaces and C-type lectins in cnidarians suggests that these interactions serve as a signal
for recognition and specificity between symbiotic partners.
5-24
Variability In Cell Surface Glycan Profiles Across A Range Of Symbiodinium
Dinoflagellate Types.
Daniel LOGAN* 1 , Anne LAFLAMME 1 , Virginia WEIS 2 , Simon DAVY 1
1 Victoria University of Wellington, Wellington, New Zealand, 2 Oregon State University,
Corvallis, OR
Symbiodinium sp. dinoflagellates are the symbiotic partner in many cnidarian hosted mutualistic
relationships. These Symbiodinium show a degree of specificity for particular hosts with a
limited range of symbiont types being found in association with a given host. This specificity
may be partially determined through cell surface glycan-lectin interactions during the initiation
of the symbiosis. The diversity of glycans present on the Symbiodinium cell surface was
investigated through the use of sugar-specific fluorescently labeled lectin probes and flow
cytometry. The four lectin probes utilized exhibited differential levels of binding to the cell
surfaces of the initial four Symbiodinium types examined, suggesting variation in cell surface
glycan diversity and concentration between Symbiodinium types. It appears that variation in
glycan profiles may be lowest between Symbiodinium types originally isolated from similar
hosts. This work is ongoing with an expanded range of Symbiodinium types and lectin probes.
Once a wider range of glycan profiles have been compiled, these data will be analyzed to
elucidate whether any correlations between glycan variation, phylogenetic distance and hostsymbiont
specificity exist.
5-25
Identification and Expression Analysis of Symbiotically Enhanced Coral mRNAs
Ikuko YUYAMA* 1 , Toshiki WATANABE 1
1 Department of Marine Bioscience, Ocean Rsearch Institute, The University of Tokyo, Tokyo,
Japan
Hermatypic corals live in obligatory mutualistic symbiosis with the dinoflagellates
Symbiodinium spp. The molecular mechanisms by which corals establish and maintain
symbiosis, however, remain unknown. With the purpose of identifying coral mRNAs that play
pivotal roles in symbiosis, the mRNA expression profiles were compared between juvenile
polyps of Acropora tenuis in the following two states: (i) aposymbiotic, and (ii) inhabited by
Symbiodinium cells strain PL-TS-1 (clade A3) or CCMP2467 (A1). Using suppression
subtractive hybridization and HiCEP (a cDNA AFLP-based expression profiling technique),
eight cDNA fragments were isolated including those which encode sulfate transporter,
syndecan, lipase, and protein kinase. Sequence analysis of the sulfate transporter cDNA
suggested that the encoded protein, an integral membrane protein with eleven trans-membrane
domains, is a cnidarian member of the SLC26A11 sulfate/anion exchanger family. The
expression level of the mRNA was increased by the presence of both Symbiodinium strains PL-
TS-1 and CCMP2467. An immunohistochemical study showed that the sulfate transporter
protein is expressed in a cell-specific manner. Notable expression of the protein was observed in
the following cells: (i) endodermal cells in the tissue between the coelenteron and skeleton in
the peritheca, (ii) mucus cells, and (iii) cells of unidenfied types in the mesenterial filament.
These results may suggest that in the above cells the uptake of SO42- is augmented and
synthesis of sulfated macromolecules (such as glycosaminoglycans) is thereby enhanced by the
presence of Symbiodinium cells. Such sulfated molecules are presumably used for the
formation of the mucus and organic matrix of the calcified skeleton.
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