11th ICRS Abstract book - Nova Southeastern University

Poster Mini-Symposium 5: Functional Biology of Corals and Coral Symbiosis: Molecular Biology, Cell Biology and Physiology
5.133
Ecology Of "Solarpowered"nudibranchia (Mollusca:gastropoda) And Their
Potential To Be An Alternative Model Organism For Understanding Bleaching
Ingo BURGHARDT* 1 , Joshua LEFFLER 2 , Katie LIBERATORE 3 , Ursula SHEPHERD 3
1 Department of Animal Ecology, Evolution and Biodiversity, Ruhr-University Bochum,
Bochum, Germany, 2 Department of Wildland Resources, Utah State University, Old
Main Hill, UT, 3 University Honors Program, University of New Mexico, Albuquerque,
NM
In contrast to the well-known symbiosis between different Cnidaria and zooxanthellae
(genus Symbiodinium) the symbiosis between Nudibranchia (Mollusca: Gastropoda) and
Symbiodinium is hardly investigated. Most of these nudibranchs obtain their symbionts
by feeding on zooxanthellate prey (mainly octocorals). As is true in cnidarians,
Symbiodinium is housed intracellulary, inside the cells of the nudibranchs’ digestive
gland. Depending on the nudibranch species the slugs are able to keep zooxanthellae
photosynthetically active for a certain period of time and benefit from the photosynthetic
products.
By means of PAM (Pulse Amplitude Modulated Fluorometry) data, long-term
experiments (under starvation conditions) demonstrated that some species survive solely
on the assimilates of their symbionts for almost one year. Therefore these nudibranchs are
called “solarpowered”. Additionally, interspecific differences in the efficiency of this
symbiosis was proven, reflecting different stages in its evolution. Histology and
ultrastructural investigations clarify special adaptations of these symbiotic species. The
genus Phyllodesmium was used as a model organism to investigate the ecology and
evolution of this mutualism.
The symbiosis between solarpowered nudibranchs and zooxanthellae seems to be an ideal
model to investigate general bleaching processes. Two very different holobionts (coral
and mollusc) with the same symbionts and their response to different environmental
stressors (high water temperatures, high irradiances, low salinity, low pH) can be directly
compared by means of PAM data, histology and electron microscopy. The impact of
higher water temperatures and irradiances was already demonstrated for three
solarpowered nudibranch species by means of PAM data. Future investigations will show
whether the zooxanthellae composition inside the two different holobionts (corals and
nudibranchs) shifts after exposition to stressors and whether isolated and cultivated
Symbiodinium will respond differently to these factors.
5.134
Regulation Of Host Innate Immunity Plays A Role in Cnidarian-Dinoflagellate
Symbiosis
Olivier DETOURNAY* 1 , Santiago PEREZ 2 , Virginia WEIS 1
1 Zoology, Oregon State University, Corvallis, OR, 2 Dept. of Genetics, Standford
University School of Medicine, Stanford, CA
Cnidarians have long been considered simple organisms lacking many of the complex
cellular pathways that are present in higher metazoans. However, these animals are able
to differentiate between invading pathogens and the beneficial, photosynthetic
dinoflagellate Symbiodinium. These dual tasks are only possible if a high level of
recognition and specificity exists that allows the host immune system to eliminate
pathogens and tolerate symbionts. Recent reports have begun to reconcile this obvious
paradox, suggesting that symbiosis is maintained by a complex cross talk between the
host and symbiont. Moreover, genomic evidence has demonstrated that cnidarians
possess homologues to many innate immunity genes from higher vertebrates. These
studies suggest that immunity genes, normally implicated in pathogens clearance, are
regulated in order to maintain the beneficial association. The objective of this study was
to explore the role of immune regulatory mechanisms in specific symbiont tolerance
mediated by the host. We examined the role of host immunity in the symbiosis between
the model anemone Aiptasia pallida and the dinoflagellate Symbiodinium sp., in
particular pro- and anti-inflammatory components of the immune system. Symbiotic and
aposymbiotic A. pallida stimulated with lipopolysaccharide (LPS), a common elicitor of
an immune response, present different profiles of activation as measured by production of
nitric oxide (NO). We show evidence that this production is regulated by a cytokine
known to play a key role in immune regulation in vertebrates. We hypothesize that the
presence of symbionts blocks LPS induction of an effector mechanism leading to the
production of NO through the secretion of an anti-inflammatory cytokine.
5.135
Immunodetection And Partial Characterization Of Two Putative Signal-Transduction
Proteins in symbiodinium Kawagutii
Marco VILLANUEVA* 1 , Claudia MORERA 1 , Roberto IGLESIAS-PRIETO 1 , Patricia
THOMÉ-ORTIZ 1 , Tania ISLAS-FLORES 2
1 Unidad Académica Puerto Morelos, Instituto de Ciencias del Mar y Limnología-UNAM,
Puerto Morelos, Mexico, 2 Plant Molecular Biology, Instituto de Biotecnología-UNAM,
Cuernavaca, Mexico
Two proteins were localized in total extracts of Symbiodinium kawagutii cells through the use
of antibodies directed to proteins potentially involved in signal-transduction. We used
antibodies (termed anti-DP) directed towards a twenty-residue peptide from the C-terminal
sequence of Grb2 (Growth Factor Receptor-Bound Protein 2), which is an adaptor protein from
the signal-transduction cascade of the growth factor stimulus in mammalian cells. Another set
of antibodies (termed anti-RT) were raised against an eight-residue peptide from a protein
originally isolated from common bean (Phaseolus vulgaris), on a Phosphotyrosine-Sepharose
column, implicating thus, a putative SH2 domain for signaling on this protein. We observed by
western blot analyses, that the anti-DP antibodies recognized a 40 kDa protein in total extracts
of Symbiodinium kawagutii, and in the same extracts, the anti-RT antibodies cross-reacted with
a 28 kDa protein. The 28 kDa protein was found to be enriched in soluble and insoluble
detergent fractions extracted from microsomal preparations, suggesting that it may be a
membrane-bound protein. These results show the presence of orthologues of putative signaltransduction
proteins in Symbiodinium and it will be of great interest to study their function and
interactive protein partners in these cells, both during their life cycle and in the symbiotic
process.
5.136
Response Of Coral Fluorescence To Environmental Changes: Insights Into The Function
Of Coral Fluorescent Proteins
Melissa ROTH* 1 , Nancy KNOWLTON 1,2 , Michael LATZ 1 , Dimitri DEHEYN 1
1 Scripps Institution of Oceanography, UCSD, La Jolla, CA, 2 Smithsonian Institution,
Washington D.C.
Despite their potential roles in photo-protection and photo-acclimation, the function of
fluorescent proteins remains poorly understood. Fluorescent proteins are host-based pigments
that are homologous to the green fluorescent protein (GFP), which was originally isolated from
a hydromedusa and is now widely used in biology and biochemistry. Fluorescent proteins are
pervasive in scleractinian corals and can constitute a significant portion of the total protein
content (up to 14%). Fluorescent proteins inherently alter the internal light microenvironment of
the coral by absorbing higher-energy photons and emitting lower-energy photons. This study
examined the coral fluorescence response in Acropora yongei during experimental
manipulations of environmental conditions, primarily light and temperature. Our preliminary
results show that the amount of coral fluorescence was dynamic, and many environmental
changes can induce a response in coral fluorescence. The coral fluorescence response was
reversed when initial environmental conditions were restored. Understanding the role of these
prevalent fluorescent proteins could elucidate mechanisms of coral physiological responses to
environmental changes. Consequently, this research will indicate whether field monitoring of
fluorescence could be useful as a noninvasive measure of coral health, specifically to identify
early signs of coral stress.
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