Numerous studies have investigated reproductive mechanisms in mollusc species at the biochemical and physiological levels; however, few have described these mechanisms at the molecular level.
In this respect, investigating the DV-patterning mechanism in molluscs, which develop similar to annelids but, unlike annelids, have retained chordin in their genomes, will be particularly interesting.
This effect could occur because C1q up-regulation is a very fast mechanism in molluscs as suggested by Gestal et al. [ 41].
The high and low salinity source oysters each expressed a subset of genes unique to that group, and the functions for these annotated genes were consistent with known molecular mechanisms for osmotic regulation in molluscs.
Yet despite the association of carotenoids, porphyrins, carbohydrates and polyenes with some molluscan shell pigments [ 22- 25], there exists no example of a complete molecular understanding of any shell pigmentation mechanism in any mollusc.
In order to gain insights into the mechanism of sex steroid signaling in molluscs, we have, therefore, tried to isolate molluscan estrogen receptors from the prosobranch mollusc Thais clavigera.
This supports the hypothesis that any mechanism of sex steroid actions in molluscs does not operate in a similar way to those in vertebrates and is not mediated via the NR3 group of nuclear receptors [ 125, 136].
The induction of heat shock or stress proteins represents a homeostatic defence mechanism of cells to metabolic and environmental insults, and this response has previously been demonstrated in molluscs, for example in oyster haemocytes in response to environmental stimulus [ 46].
Fig. 1 Schematic drawing of two common eye types found in molluscs.
However, GAD has rarely been reported in invertebrates, and never in molluscs.
