Cytoskeleton Alterations by Tributyltin (TBT) in Tunicate Phagocytes

Hemocyte functions and bacterial clearance affected in vivo by TBT and DBT in the blue mussel Mytilus edulis

“…Our results are consistent with these reports; butyltin-exposed samples showed less aggregation than the controls. Levels of MI were smaller and occurred more slowly in our study than those found in ascidian hemocytes (Cima et al 1998) or human erythrocytes exposed to TBT concentrations much higher than ours. However, various levels of MI have been observed at comparable butyltin concentrations in blood cells of rainbow trout Oncorhynchus mykiss (C. Ribiero, J. Padros & É. Pelletier unpubl.…”

“…Secondly, both organotins, but especially DBT, were also shown to shut down the Ca 2+ pump (Gray et al 1987, Cima et al 1998. Bouchard et al (1999) hypothesized that DBT appears to be a better competitor for calcium sites than TBT because the ionic form of DBT is a double-charged cation like Ca 2+ and is a much smaller moiety than TBT, which brings only 1 positive charge.…”

TBT‐induced apoptosis in tunicate haemocytes

“…This TBT concentration probably represents the threshold value of exposure around which a remarkable variability occurs following an 'all or nothing' behaviour. Therefore, 10 "M TBT was chosen for exposure of haemocytes for 1-4 h, since this concentration constantly and significantly changes cytoskeletal structure and does not cause mortality within 1 h. 9,10 In controls, both viability and apoptotic indexes, detected with Trypan Blue and Acridine Orange respectively, remained unchanged up to 4 h. For this reason, in Fig. 1 the control data are conventionally reported as time = 0.…”

“…10 Accompanying the decrease in cell volume, the plasma membrane of B. schlosseri haemocytes becomes extensively convoluted and acquires a characteristic blebbed appearance, together with phosphatidylserine externalization. The latter is a common event, well described during apoptosis of murine and human cells.…”

“…9 The effect is mediated by an extensive cytosolic calcium increase, resulting in volume loss and morphological changes related to cytoskeletal alterations. 10,11 We stress that, in contrast to the situation for vertebrates, studies on apoptosis generally induced in invertebrates by xenobiotic exposure are still greatly lacking. As tunicates are closely related to vertebrates, they can be chosen as a comparative model for the immunotoxicity.…”