CORAL GENOMICS GROUP
COMPARATIVE GENOMICS CENTRE

Mail Address: Comparative Genomics Centre,
Molecular Sciences Bldg 21, James Cook University,
Townsville, 4811, Queensland, Australia
Telephone: 61-7-4781 6265 Fax:  61-7-4781 6078


 CONTENTS:
RESEARCH OVERVIEW:
 
 
 
    Our understanding of metazoan genome evolution is based on a small number of complete genome sequences and large EST (Express Sequence Tags) datasets that represent only a few complex animals. Of necessity, therefore, deductions about the evolutionary origins and structures of human genes are largely based on comparisons with the genomes of the insects Drosophila melanogaster and Anopheles gambiae, the nematode Caenorhabditis elegans and the yeasts Saccharomyces cerevisiae and Schizosaccharomyces pombe. The study of the evolution of developmental genes has identified some spectacular examples of conservation of developmental programs, particularly between D. melanogaster and vertebrates. However, a significant number of D. melanogaster and C. elegans genes are highly modified, and the extent of gene loss in these organisms is unknown. Substantial differences between the D. melanogaster and C. elegans genomes, together with the fact that the nematodes and arthropods are now regarded as more closely related than was previously the case, imply that comparisons based only on these organisms may give a misleading view of the ancestral metazoan.

  In terms of understanding the evolution of metazoan genetic and developmental complexity, the Cnidaria are likely to be critically important, as this phylum is regarded as the sister group to the Bilateria. For these reasons, we are using a local cnidarian, the reef-building coral Acropora, as a model system in order to investigate several issues central to the evolution of developmental mechanisms.  Over the last few years, we have established most of the standard molecular methods (in situ hybridisation technology etc.) and tools (genetic libraries etc.) for Acropora, and this has lead to increasing recognition of its value as a comparator by the international community. At present we are using Acropora to address several questions that are central to nervous system development and the evolution of developmental mechanisms.
Anthozoan cnidarians such as Acropora possess the most 'primitive' present-day nervous systems, a morphologically homogeneous nerve net. However, an ongoing EST project that we are carrying out has identified a large number of genes involved in specifying and patterning the advanced nervous systems of flies and mammals. We have shown that several of these genes are expressed in the coral in patterns that resemble those seen in vertebrates. In addition, the cnidarian nervous system appears to be entirely dispensable, as it is possible to indefinitely culture hydra after destroying all nerve cells and the interstitial cells that give rise to them. Therefore despite its apparent simplicity, plasticity and regenerative capabilities, the cnidarian nervous system is patterned by genes related to those of vertebrates. Cnidarians are therefore potentially highly informative for many aspects of nervous system specification and regeneration.
 

 
Evolutionary Genetics
We use Acropora as a model for understanding the evolutionary processes affecting sessile marine invertebrates in general, as these appear to evolve in very different ways to the terrestrial animals upon which much of our understanding of evolutionary processes is based. One of the major differences between these systems is that many sessile marine invertebrates release their gametes into the water column where fertilization takes place. This creates unparalleled opportunities for interspecific hybridization and introgression between species, as has been documented for many species of reef corals. Molecular data and experimental breeding trials have confirmed that interspecific hybridisation occurs and is likely to have contributed to the evolution of modern Indo-Pacific coral species including the genus Acropora
 
    Acropora is the largest extant reef-building coral genus, and is also one of the worldís most widespread scleractinian coral genera, spanning the Indian and Pacific Oceans and the Caribbean Sea. Some species have very restricted distributions, whereas others are found throughout large parts of the tropics, and up to 70 Acropora species can be found in sympatry. An enormous amount of intraspecific morphological variability exists, while at the same time similarities between species are striking; for example, intraspecific geographic differences in morphology can be as large as differences between species. Acropora thus provides an ideal model system for examining speciation and evolution of scleractinian reef coral species in general, on both temporal and spatial scale.
   Whilst interspecific hybridisation clearly occurs between coral species, population genetic approaches indicate that it occurs with much lower frequency than would be expected on the basis of in vitro breeding trials. This implies the existence of (imperfect) gamete recognition systems in corals. A particular area of interest to us is therefore to unravel the basis of coral gamete specificity. Some candidate molecules have emerged from the EST project, and we are presently investigating these.
Coral Spawning
Coral spawning is an intense period of activity for us as, over a period of a few days each year, we try to collect and preserve sufficient embryonic and larval coral material to sustain lab activities for the rest of the year. We also carry out many experiments on the reproductive and developmental biology of Acropora at that time. Fieldwork during coral spawning is generally carried out from Magnetic sland, and takes place following the full moon in mid-late October. The fact that the main reefs generally spawn one lunar month after inshore reefs (such as those around Magnetic Island enables us also to collect material from the Universityís research station on Orpheus Island if we need to. We have also carried out fieldwork on the West Australian reefs, which spawn during autumn rather than spring
Dinoflagellate Genetics
All reef-building corals form obligate symbioses with unicellular algae belonging to the dinoflagellate genus Symbiodinium (nominally a single genus but actually a highly diverse group of organisms) ­ the ability of corals to calcify at rates required to build reefs requires high levels of photosynthesis in their algal symbionts. We are interested in both basic and evolutionary genetics of dinoflagellate. Dinoflagellates are unique eukaryotes in many ways ­ for example, components of their light-harvesting complexes are unrelated to any known proteins, and they do not contain true histone proteins. Little is known about the molecular basis of the interaction of the algae with their coral hosts, nor about the specificity of the interaction.
STAFF
Group Head: Research Staff


Graduate Students

PUBLICATIONS:
 
 
 
LINKS:
 

 

Comparative Genomics Centre, Center, James Cook University, Key words: Coral, Genetics, gene, genome, DNA, linkage, Autoimmune diabetes, Type 1 diabetes mellitus, childhood diabetes, lupus, systemic lupus erythematosus, haemolytic anaemia, hemolytic anemia, Coombs' test, antinuclear antibodies, renal failure, glomerulonephritis, gastritis, type A gastritis, pernicious anemia.