An Antarctic molluscan biomineralisation tool-kit

Acknowledgements VAS was funded by a NERC DTG studentship (Project Reference: NE/J500173/1) to the British Antarctic Survey. MSC was financed by NERC core funding to the British Antarctic Survey. We would like to thank Jeremy Skepper for advising us on TEM procedures and processing the mantle tissue samples prior to TEM, Elizabeth M. Harper for advice on Laternula elliptica mantle anatomy for the schematic, Jamie Oliver for technical help with digitising the schematic, Deborah M. Power for in situ hybridisation advice, Valerie J. Smith for advice on immunology and histology, Lloyd S. Peck for vesicle discussions and critical reading of the manuscript and the dive team at Rothera research station, Antarctica for support in animal collection. Diving oversight was provided by the NERC National Facility for Scientific Diving, Oban.Peer reviewedPublisher PD

Unusual tissue distribution of carcinin, an antibacterial crustin, in the crab, Carcinus maenas, reveals its multi-functionality

Funding was provided by a scholarship to SS by the Syrian Ministry of Higher Education, administered by the British Council. The Alumni Fund of Heriot-Watt University and the British Council also provided additional financial support to SS.Crustins are whey acidic four-disulphide core (WFDSC) domain-containing proteins in decapods that are widely regarded as antimicrobial agents that contribute to host defence. Whilst there have been many analyses of crustin gene expression in tissues, few studies have been made of the distribution of the natural proteins. Here we report an immunostaining investigation of carcinin, a native crustin from Carcinus maenas, in the body organs. The results show that the protein is largely confined to the haemocytes with only a weak signal detected in the heart, hepatopancreas and midgut caecum where it is restricted to the outer surfaces. Importantly, carcinin was seen to be deposited by the haemocytes on these surfaces. Higher levels of staining were detected in the gonads with carcinin particularly abundant in the capsule of ovary as well as some oocytes. Conspicuous staining was further evident in the cuticle of the eyestalk peduncles. Ablation of the eyestalks resulted in a reduction of carcinin in the maturing ovary with the mature eggs rarely displaying a strong signal for the protein. Interestingly, the degree of carcinin also strongly increased in the healing peduncle, indicating that the protein may be associated with wounding, cell damage and/or tissue regeneration.PostprintPostprintPeer reviewe

New Insights into the Apoptotic Process in Mollusks: Characterization of Caspase Genes in Mytilus galloprovincialis

Apoptosis is an essential biological process in the development and maintenance of immune system homeostasis. Caspase proteins constitute the core of the apoptotic machinery and can be categorized as either initiators or effectors of apoptosis. Although the genes encoding caspase proteins have been described in vertebrates and in almost all invertebrate phyla, there are few reports describing the initiator and executioner caspases or the modulation of their expression by different stimuli in different apoptotic pathways in bivalves. In the present work, we characterized two initiator and four executioner caspases in the mussel Mytilus galloprovincialis. Both initiators and executioners showed structural features that make them different from other caspase proteins already described. Evaluation of the genes’ tissue expression patterns revealed extremely high expression levels within the gland and gills, where the apoptotic process is highly active due to the clearance of damaged cells. Hemocytes also showed high expression values, probably due to of the role of apoptosis in the defense against pathogens. To understand the mechanisms of caspase gene regulation, hemocytes were treated with UV-light, environmental pollutants and pathogen-associated molecular patterns (PAMPs) and apoptosis was evaluated by microscopy, flow cytometry and qPCR techniques. Our results suggest that the apoptotic process could be tightly regulated in bivalve mollusks by overexpression/suppression of caspase genes; additionally, there is evidence of caspase-specific responses to pathogens and pollutants. The apoptotic process in mollusks has a similar complexity to that of vertebrates, but presents unique features that may be related to recurrent exposure to environmental changes, pollutants and pathogens imposed by their sedentary nature