Additionally and besides direct targeting to mitochondria, apoptotic cell death is also Crenolanib mw induced by bile acids through receptor-dependent-mechanisms which could explain why A. planci did not attack corals in the
tank and showed minimal movement 1 h after injection. On the other hand, high concentrations of bile also cause a bioenergetic catastrophe culminating in the disruption of plasma membrane integrity. Mitochondrial calcium homeostasis is severely impaired ( Palmeira and Rolo, 2004 and Rolo et al., 2004). Both necrosis and apoptosis could be the mechanisms involved in the induction of disease and death of COTS after bile injections. Necrosis is evident in A. planci tissues 24 h after injection with oxbile. Apoptosis could be also involved in the induction of disease because is the mechanism normally triggered by low concentrations of bile salts as those used in this study. There is a direct relationship between sodium chloride concentration and bile salts cytotoxicity. It has
been shown that increasing NaCl concentrations lowers the critical micellar concentration (CMC) of bile salts http://www.selleckchem.com/products/LBH-589.html and increase bile toxicity (Morgan et al., 1998) which could explain why very small doses of oxbile are required to kill A. planci. We hypothesize that a synergistic effect between seawater (high NaCL concentration) and bile salts (unnatural proteins) could trigger a fulminating allergic reaction (cytotoxicity) inducing apoptosis
and necrosis of A. planci tissues, but this needs to be confirmed by analysis of sea star tissues through histology (HandE and Gram stains), SEM and TEM to confirm that injection of bile do not induce a transmissible bacterial disease. There is however, always the possibility that there will be secondary infection induced by opportunistic pathogens once the immune system collapses. Effectiveness of peptones varied greatly between the different types of peptones tested, and rarely caused high mortality of injected A. planci even at 20× concentration based on TCBS standard concentration of 10 g l−1, except for bacteriological peptone. Aside from the dose-dependent nature of the effectiveness of peptone in killing A. planci ( Rivera-Posada et al., 2012), peptone Y-27632 2HCl commonly exhibits batch-to-batch variability in chemical composition and culture performance even between the same brand ( Taylor, 1981 and Murakami et al., 1982) which could lead to inconsistent results. In addition, peptones are produced from many different sources such as plants (cotton seed, soya beans), meat (bovine and porcine, heart, liver, brain, meat), casein (milk of mammals) all of which have different properties. Other parameters that influence the final product are the raw materials used in the preparation of the media (i.e. materials contaminated with copper ions show a very low growth rate of microorganisms).