Of Molluscs and Men: Identification and phylogenetic analysis of nuclear receptors in Gastropod Molluscs

Program: Abstracts - Orals, Featured Poster Presentations, and Posters
Session: SUN 338-365-Metabolic & Stress Receptors in Energy Homeostasis
Sunday, June 16, 2013: 1:45 PM-3:45 PM
Expo Halls ABC (Moscone Center)

Poster Board SUN-363
Satwant Kaur*1, Alice Baynes1, Catherine Jones2, Leslie Noble2, Edwin Routledge1, Susan Jobling1 and Anne Lockyer1
1Brunel University, Uxbridge, United Kingdom, 2University of Aberdeen, Aberdeen, United Kingdom
Molluscs represent one of the most species-rich phyla and, from an evolutionary point of view, are key representatives of the Lophotrochozoans; however, almost nothing is known about the endocrine function in molluscs. This knowledge is significant for understanding the origin and evolutionary development of endocrine systems, as well as investigating fundamental biological questions concerning molluscs, from their role as intermediate hosts for parasitic diseases, through to ecological and toxicological issues. Traditional physiological and toxicological studies indicate commonalities of morphological features of the reproductive system of molluscs and mammals, and comparative studies into functional conservation of genes and genomes also offer the opportunity to develop invertebrate models for endocrine systems. The nuclear receptors (NRs) of molluscs are of particular interest, since NRs are key components of mammalian endocrine systems, controlling a variety of functions, from embryonic development to metabolism.

The growing wealth of sequenced genomes and comparative genomic approaches provide us with opportunities to successfully explore non-vertebrate models to elucidate the genetic elements of endocrine diseases. Here we investigate the utility of the tropical freshwater snail, Biomphalaria glabrata and the marine owl limpet, Lottia gigantea, as alternative invertebrate systems to study endocrine diseases by identifying and analyzing the complete set of NR genes in their recently sequenced genomes. We identified 42 putative NRs in B. glabrata and 35 from L. gigantia, based on the presence of conserved regions. Many of the identified molluscan NRs have vertebrate orthologs. However, some NRs found in vertebrates are absent from these mollusc genomes, notably the members of subfamily 3C which includes some of the “vertebrate” steroid hormone targets, suggesting that these two molluscs may be inappropriate models for steroid hormone mediated mammalian endocrine function. Differences were also found between the two molluscs, including the thyroid hormone receptor of Group 1A, which, although absent in B. glabrata, was identified in L. gigantea, indicating that further investigation of molluscs as models of thyroid disease/dysfunction is warranted.  The mollusc genomes also contain NR orthologs that are present in insects and nematodes but not in vertebrates, such as subfamily 1J and a 2DNA-binding domain NR. Phylogenetic analyses also revealed the presence of a unique and atypical subset of four NRs in B. glabrata. The presence of other vertebrate NR orthologs, however, raises the exciting possibility of shared significant pathways which could give an insight into mechanistic read-across between molluscs and mammals and provided insight into the evolutionary development of endocrine systems.

Nothing to Disclose: SK, AB, CJ, LN, ER, SJ, AL

*Please take note of The Endocrine Society's News Embargo Policy at http://www.endo-society.org/endo2013/media.cfm

Sources of Research Support: National Centre for the Replacement, Refinement and Reduction of Animals in Research Grant (NC3Rs)