Sham Nair - Group Leader;

My current research interests are in the area of comparative immunology and genomics. My background has included research on different groups of organisms, including viruses (herpesviruses), bacteria (marine bacteria), slime mold (single-celled eukaryote), plants (apple and peach), invertebrates (insects and marine invertebrates) and vertebrates (marsupials, dairy cattle, mice). The one common approach to all of these projects that I have been involved in is a biomolecular approach to addressing various issues in biological sciences.

My PhD research, conducted at the University of Technology, Sydney (UTS) under the supervision of A/Prof David Raftos and Prof Robert Raison, examined host defense in the solitary tunicate, Styela plicata. In that project, I discovered a collagenous lectin (C-type lectin with a collagenous domain) that appeared to function in concert with a complement C3-like protein. It appears to be homologous to the lectin-mediated complement activation pathway in the vertebrates.

After this, I undertook post-doctoral research at Prof Courtney Smith's laboratory at the George Washington University. Here I investigated transcriptomic responses of sea urchin (Strongylocentrotus purpuratus) blood cells and that work led to the discovery a high degree of molecular diversity in the gene family called 185/333. The expression of these genes are enhanced during immunological responses to non-self challenge. The diversity of 185/333 transcripts and proteins is increased during their expression (when compared to their corresponding gene sequences). There is some evidence to suggest that the sea urchin employs molecular diversity in the 185/333 molecular system as an immunological strategy during infections, although the exact function of these molecules has not been elucidated.

Upon my return to Australia, I worked at Sydney University, examining (using microarrays) the transcriptional responses of mammary gland tissues from specially-derived mouse strains. While there, I also explored the development of transfected cell arrays and mammosphere cultures.

I am currently at Macquarie University, where I have continued to work on my interests in comparative immunology and genomics. During this period, I have undertaken research on the diversity of the 185/333 gene family, genomics of the sea urchin, immunological responses of insects to infections and the relationship between physiological stress and immunity in marine invertebrates (e.g. oysters).

Current members

Masood Muhammad

PhD student

Masood is investigating antiviral immunity in oysters and other molluscs. Some components of the RNAi pathway, such as Dicer and Argonaut, have been identified in molluscs, suggesting that they may have a functional RNAi system. It is also possible that molluscs employ RNAi as a tool to abrogate viral infections. Being filter feeders, molluscs such as oysters may concentrate microbial and other pathogens in their bodies. As some molluscs are also used intensively in agriculture, high population densities can lead to the rapid dissemination of pathogens in farms and other coastal areas. As such, these animals must possess a robust immune system to deal with potential infections by such pathogens. Indeed, infectious disease is one of the biggest threats facing the invertebrate aquaculture industries.

Adam Wilkins

PhD student

What can genomes tell us about how animals protect themselves from infections? This is the primary question behind Adam's PhD thesis. Adam is a computer programmer and has a background in bioinformatics. He is currently exploring the evolution of genes whose products function in defense. Using a comparative genomic approach, Adam is investigating the evolution of defense-related genes in invertebrate deuterostomes and invertebrate chordates. He has developed a suite of bioinformatic tools for sequence analyses - you can find out more about these at his website. He is an avid diver and often is part of the marine landscape around Sydney.

Glen Wilkins

PhD student

Glen obtained a Class 1 B.Sc Honours degree. His research project, which was conducted in my lab, explored
the sea urchin genome to discover the genomic basis of diversity-dependent immune responses in this animal. Using algorithms that enhance gene discovery, Glen has discovered high levels of complexity in sea urchin gene structure and organisation. His research has focused on a highly expanded gene family, the Scavenger Receptor Cysteine Rich (SRCR) genes.

For PhD research, Glen is examining genomic diversity in single cells. He is using exome sequencing as a tool toevaluate the level of diversity at the 185/333 loci.

Past members

Mattias Roth

Mattias' research focuses on a highly variable gene family, called 185/333, in sea urchins. The protein products of this family are involved in host defense. It has been estimated that each animal contains many 185/333 genes. Post-transcriptional and post-translation events diversify the repertoire of 185/333 gene products. The sets of 185/333 transcripts and proteins expressed appears depend on the type of immunogen used. Based on their nucleotide sequences, 185/333 polypeptides appear to lack any discernible tertiary structure (generally, they lack cysteines). On polyacrylamide gels, the apparent molecular weights and isoelectric points are very different to those predicted from their nucleotide sequences. Microscopic investigations indicate that 185/333 proteins are displayed on the surfaces of phagocytic blood cells, even though these proteins do not contain transmembrane or membrane-anchor motifs. Taken together, the data suggest that 185/333 gene family and its products are enigmatic molecules involved in immunological defense. Together with other unrelated highly variable gene families involved in invertebrate immunity (e.g. DSCAMs, FREPs, VCBPs), 185/333s are contributing to a changing paradigm in immunology: that there are many different flavours of specific immunity that are based on molecular variability in the animal kingdom.

Sham Nair 2014