Long term exposure to cadmium: Pathological effects on kidney tubules cells in Sparus aurata juveniles.

The effects of an exposure to cadmium chloride 0.47µM for 150days were studied in kidneys of juveniles Sparus aurata by a multidisciplinary approach so to correlate uptake and detoxification potential to changes in brush border and glycocalyx sugar composition. Results demonstrated that cadmium concentration in kidney significantly increased from day 30 reaching a plateau on day 120 while metallothioneins reached a peak on day 90 and by day 120 were already decreasing to control values. Cytological damage was extensive on day 90, clearly detectable at both structural and ultrastructural levels, in tubular cells and brush-border. Staining with a panel of four lectins revealed a significant increase in N-Ac-Gal and a decrease in mannose in the glycocalyx and the tubular basal membranes. From day 120, when cadmium concentration was high and metallothionein concentration decreasing, a clear recovery was observed in tubular cells morphology and sugar composition. Possible significance of these apparently contrasting data are discussed.

Caspase 3 in molluscan tissues: localization and possible function.

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.

Responses to cadmium intoxication in the liver of the wall lizard Podarcis sicula.

This study examined the cytological and molecular effects of cadmium, a toxic heavy metal, in the liver of the Italian wall lizard Podarcis sicula. Cadmium was administered in single dose, by diet, to induce a concentration comparable with that measured in animals living in contaminated sites. For comparison, cadmium was also administered in multiple doses by food (chronic) or in a single dose intraperitoneally (i.p.); the effects were followed at regular time intervals up to 30 days post treatments. Atomic absorption spectrometry analysis demonstrated cadmium ion uptake and accumulation in the parenchyma with an estimated half-life of approximately 8 days. Cytological analyses revealed that the metal induced oedema, activated metallothionein expression in Kupffer cells and extracellular matrix production in fat storing cells. It also caused swelling and alteration in lipid and sugar metabolism in hepatocytes. In conclusion, in the wall lizard cadmium is toxic to the liver even at very low concentrations, the response is not strictly dose and time dependent and almost no recovery occurs in short (30 days) time periods.

cGnRH II involvement in pyriform cell apoptosis.

We have investigated whether gonadotrophin-releasing hormone (GnRH) is involved in triggering the apoptotic death of pyriforms, the nurse cells that cooperate in oocyte growth during mid- to late previtellogenesis in the lizard Podarcis sicula. Our immunocytochemical analyses demonstrate that pyriforms express GnRH receptors and that, in late previtellogenesis, they are up-regulated by cGnRH II. The hormone however does not trigger receptor synthesis and activation, events that therefore must be under the control of other regulatory factors. Our results also indicate that in vitro treatment of pyriforms with cGnRH II induces DNAse I activation and DNA laddering, clear cytological evidence of apoptosis, but not Fas/Fas-L synthesis or caspase activation. We conclude that cGnRH II is pro-apoptotic to pyriform cells and that it exerts its effects by activating an alternative cell death pathway, probably involving calcium as first messenger and DNase I as first executioner.

The immunomodulatory protein SV-IV protects serum-deprived cells against apoptosis but not against G0/G1 arrest: possible implications for the survival of implanting embryo.

Serum deprivation induced in human lymphoblastoid Raji cells oxidative stress-associated apoptotic death and G0/G1 cell cycle arrest. Addition into culture medium of the immunomodulatory protein Seminal vesicle protein 4 (SV-IV) protected these cells against apoptosis but not against cycle arrest. The antiapoptotic activity was related to: (1) decrease of endocellular reactive Oxygen species (ROS) (2) increase of mRNAs encoding anti-oxidant enzymes (catalase, G6PD) and antiapoptotic proteins (survivin, cox-1, Hsp70, c-Fos); (3) decrease of mRNAs encoding proapoptotic proteins (c-myc, Bax, caspase-3, Apaf-1). The biochemical changes underlaying these effects were probably induced by a protein tyrosine kinase (PTK) activity triggered by the binding of SV-IV to its putative plasma membrane receptors. The ineffectiveness of SV-IV to abrogate the cycle arrest was accounted for by its downregulating effects on D1,3/E G1-cyclins and CdK2/4 gene expression, ppRb/pRb ratio, and intracellular ROS concentration. In conclusion, these experiments: (1) prove that SV-IV acts as a cell survival factor; (2) suggest the involvement of a PTK in SV-IV signaling; (3) point to cell cycle-linked enzyme inhibition as responsible for cycle arrest; (4) provide a model to dissect the cycle arrest and apoptosis induced by serum withdrawal; (5) imply a possible role of SV-IV in the survival of hemiallogenic implanting embryos.