Filipin-sterol complexes in molluscan gill ciliated epithelial cell membranes: intercalation into ciliary necklaces and induction of gap junctional particle arrays

Detection of metal induced cytopathological alterations and DNA damage in the gills and hepatopancreas of green mussel Perna viridis from Ennore Estuary, Chennai, India

This study report the impact of heavy metals on cytopathology and DNA damage in the gills and hepatopancreas of Perna viridis collected from Ennore estuary and the Kovalam coastal waters. Principal Component Analysis (PCA) showed significant differences among all variables at the scale of plots. The ultrastructural alterations such as lack of microvilli, distorted mitochondria, electron dense particles and the presence of large mucous droplets were common in the gill and hepatopancreatic cells of mussels from Ennore estuary. However, the gill and hepatopancreatic cells of P. viridis from Kovalam revealed normal compartmentalization of cells. The percentage of tail DNA in the mussels from Ennore estuary was recorded as 12.44 and 10.14% in the gills and hepatopancreas respectively. Overall, it has been demonstrated that the Comet and cytopathological assays are useful biomarkers to assess the level of pollution and it provide reliable information on ecotoxicology and genotoxicology of coastal waters.

Modulation of pumping rate by two species of marine bivalve molluscs in response to neurotransmitters: Comparison of in vitro and in vivo results

Most studies regarding the neuroanatomy and neurophysiology of molluscan ctenidia have focused on isolated ctenidial tissue preparations. This study investigated how bivalve molluscs modulate their feeding rates by examining the effects of a variety of neurotransmitters, including serotonin, dopamine, and the dopamine agonist apomorphine on both isolated ctenidial tissue and in intact members of two commercially important bivalve species: the blue mussel, Mytilus edulis; and the bay scallop Argopecten irradians. In particular, we examined the effect of changes in: 1) beat of the lateral cilia (in vitro), 2) distance between ctenidial filaments and/or plicae (in vivo), and 3) diameter of the siphonal openings (in vivo) on alteration of bulk water flow through the mantle cavity. Important differences were found between isolated tissue and whole animals, and between species. Drugs that stimulated ciliary beat in vitro did not increase water processing rate in vivo. None of the treatments increased water flow through the mantle cavity of intact animals. Results suggest that A. irradians was primarily modulating lateral ciliary activity, while M. edulis appeared to have a number of ways to control water processing activity, signifying that the two species may have different compensatory and regulatory mechanisms controlling feeding activity.

Ciliogenesis in sea urchin embryos--a subroutine in the program of development

One major milestone in the development of the sea urchin embryo is the assembly of a single cilium on each blastomere just before hatching. These cilia are constructed both from pre-existing protein building blocks, such as tubulin and dynein, and from a number of 9 + 2 architectural elements that are synthesized de novo at ciliogenesis. The finite or quantal synthesis of certain key architectural proteins is coincident with ciliary elongation and proportional to ciliary length. Upon deciliation, the synthesis of architectural proteins occurs anew, a new cilium grows, and the stores of various building blocks are replenished. This routine of coordinated ciliary gene expression may be replayed experimentally many times without delaying normal development. The ability to regenerate cilia has allowed elucidation of these various protein synthetic relationships and has led to the discovery of the pathways by which membrane-associated tubulin and axoneme-associated architectural proteins are conveyed into the highly compartmentalized growing cilium. The sea urchin embryo thus provides a very convenient model system for studies of ciliary assembly and maintenance, coordinate gene expression and membrane dynamics.