@article {4377, title = {Characterisation of the mantle transcriptome and biomineralisation genes in the blunt-gaper clam, Mya truncata}, journal = {Marine Genomics}, volume = {27}, year = {2016}, pages = {47 - 55}, abstract = {

Abstract Members of the Myidae family are ecologically and economically important, but there is currently very little molecular data on these species. The present study sequenced and assembled the mantle transcriptome of Mya truncata from the North West coast of Scotland and identified candidate biomineralisation genes. RNA-Seq reads were assembled to create 20,106 contigs in a de novo transciptome, 18.81\% of which were assigned putative functions using \{BLAST\} sequence similarity searching (cuttoff E-value 1E {\quotesinglbase}{\`a}{\'\i} 10). The most highly expressed genes were compared to the Antarctic clam (Laternula elliptica) and showed that many of the dominant biological functions (muscle contraction, energy production, biomineralisation) in the mantle were conserved. There were however, differences in the constitutive expression of heat shock proteins, which were possibly due to the M. truncata sampling location being at a relatively low latitude, and hence relatively warm, in terms of the global distribution of the species. Phylogenetic analyses of the Tyrosinase proteins from M. truncata showed a gene expansion which was absent in L. elliptica. The tissue distribution expression patterns of putative biomineralisation genes were investigated using quantitative PCR, all genes showed a mantle specific expression pattern supporting their hypothesised role in shell secretion. The present study provides some preliminary insights into how clams from different environments {\quotesinglbase}{\"A}{\`\i} temperate versus polar {\quotesinglbase}{\"A}{\`\i} build their shells. In addition, the transcriptome data provides a valuable resource for future comparative studies investigating biomineralisation.

}, keywords = {shell}, issn = {1874-7787}, doi = {http://dx.doi.org/10.1016/j.margen.2016.01.003}, url = {http://www.sciencedirect.com/science/article/pii/S1874778716300034}, author = {Victoria A. Sleight and Michael A.S. Thorne and Lloyd S. Peck and Arivalagan, Jaison and Berland, Sophie and Marie, Arul and Melody S. Clark} } @article {3490, title = {Characterisation and expression of the biomineralising gene Lustrin A during shell formation of the European abalone Haliotis tuberculata}, journal = {Comparative Biochemistry and Physiology , Part B}, volume = {169}, year = {2014}, month = {2014}, pages = {1-8}, type = {Research article}, abstract = {

The molluscan shell is a remarkable product of a highly biomineralisation process, and is composed of calcium carbonate most commonly in the form of calcite or aragonite. The exceptional mechanical properties of this biomaterial are imparted by the embedded organic matrix which is secreted by the underlying mantle tissue. While many shell-matrix proteins have already been identified within adult molluscan shell, their presence and role in the early developmental stages of larval shell formation are not well understood. In the European abalone Haliotis tuberculata, the shell first forms in the early trochophore larva and develops into a mineralised protoconch in the veliger. Following metamorphosis, the juvenile shell rapidly changes as it becomes flattened and develops a more complex crystallographic profile including an external granular layer and an internal nacreous layer. Among the matrix proteins involved in abalone shell formation, Lustrin A is thought to participate in the formation of the nacreous layer. Here we have identified a partial cDNA coding for the Lustrin A gene in H. tuberculata and have analysed its spatial and temporal expression during abalone development. RT-PCR experiments indicate that Lustrin A is first expressed in juvenile (post-metamorphosis) stages, suggesting that Lustrin A is a component of the juvenile shell, but not of the larval shell. We also detected Lustrin A mRNAs in non-nacre forming cells at the distal-most edge of the juvenile mantle as well as in the nacre-forming region of the mantle. Lustrin A was also expressed in 7-day-old post-larvae, prior to the formation of nacre. These results suggest that Lustrin A plays multiple roles in the shell-forming process and further highlight the dynamic ontogenic nature of molluscan shell formation.

}, keywords = {biomineralisation, Haliotis tuberculata, larval development, Lustrin A, mollusc, organic matrix, shell}, author = {Gaume, B{\'e}atrice and Denis, Fran{\c c}oise and Van Wormhoudt, Alain and Huchette, Sylvain and Jackson, Daniel and Avignon, Sol{\`e}ne and St{\'e}phanie Auzoux-Bordenave} }