Caspase 3 in molluscan tissues: Localization and possible function

Abstract

The presence and localization of caspase 3, a master enzyme in apoptosis, have been analyzed in tissues of four species of Molluscs: the Bivalves Callista chione and Adamussium colbecki and the Gastropods Helix pomatia and Neobuccinum eatoni. Western blotting and immunocytochemical analyses show that a 32 kDa caspase 3 is present in guts, in gill lamellae and in digestive glands during digestion but not in heart tissue or in resting digestive glands. The enzyme is also found in gonads of both sexes but there are significant differences between Bivalves and Gastropods and between male and female germ cells, especially in late stages of differentiation. In particular, caspase 3 is abundant in Bivalves oocytes and in Gastropods spermatozoa but not in Gastropods oocytes; in Callista spermatozoa it appears only after sea water activation. TUNEL staining and PCNA immunolocalization, carried out on C. chione and H. pomatia tissues, suggest that caspase 3 is primarily associated with degenerative processes in gut, digestive gland and early stage germ cells while in gills, oocytes and mature spermatozoa it is primarily correlated with cell function and/or differentiation.

The complexity of apoptotic cell death in mollusks: An update

“…Apoptosis enables the adequate clearance of damaged, senescent and infected cells without inflammation [8,120,123]. Motta et al [86] analyzed the localization and possible function of the caspase-3 gene in various molluscan tissues. These authors found that caspase-3 is present in gut, gill lamellae and digestive gland during digestion but not in heart tissue or in resting digestive glands.…”

“…The involvement of the apoptotic process in the maintenance of tissue homeostasis, physiology and functionality of each organ in mollusks is well reflected by the analysis of the expression of certain apoptotic genes in different tissues [47,86,109]. In the mussel (M. galloprovincialis) [109], the apoptotic process in the different anatomical parts of the digestive gland appears to be quite important because it is the first entrance for potential pathogens such as the copepod Mytilicola intestinalis [31,133].…”

High rates of apoptosis visualized in the symbiont-bearing gills of deep-seaBathymodiolusmussels

“…However, other mechanisms can lead to DNA fragmentation that would result in a positive TUNEL labelling, and for this reason the TUNEL methodology has been criticized [48][49][50]. It is nevertheless a standard procedure that has already been applied in mollusk tissues, and in association with active caspase-3 immunolocalization to detect apoptosis in the chemosymbiotic bivalve Codakia orbiculata [40,51]. Caspase-3 exists within the cytosol as inactive dimers.…”

A microarray-based analysis of oocyte quality in the European clam Ruditapes decussatus

“…Apoptosis is an intrinsic, genetically controlled process, responsible for destroying redundant, dysfunctional or damaged cells (Motta et al 2013). Among the genes that were more abundant in poor quality oocytes, some appeared to be implicated in cell responses to stress.…”