Phagocytosis inhibition of clam and mussel haemocytes by Perkinsus atlanticus secretion products.

Effects of high temperatures on functional responses of haemocytes in the clam Chamelea gallina

“…In the present study, significant inhibition of phagocytic activity was found in clams kept at 30 C. Similarly, phagocytosis decreased significantly in C. virginica subjected to a sudden increase in temperature from 20 to 28 C for 1 week [40]. Conversely, Carballal et al [42] found that the percentage of phagocytic haemocytes from M. galloprovincialis was lower at 10 C than at 20 C and 30 C. Ordas et al [43] observed no differences between phagocytosis at 15 and 21 C in both the clam, R. decussatus, and the mussel, M. galloprovincialis. In the present study, increased THC did not correspond to an increase in phagocytic activity in animals kept at 30 C. Presumably, as proposed by Alvarez et al [44] and Chu and La Peyre [45], temperatures above a certain threshold may result in stress conditions for haemocytes, so that they are less responsive.…”

Modulation of the chemiluminescence response of Mediterranean mussel (Mytilus galloprovincialis) haemocytes

“…These two routes for generating ROIs could be complementary since PMA-activated haemocytes increased its zymosan-induced luminol-augmented CL. M. galloprovincialis haemocytes have been reported to phagocytose the clam pathogen Vibrio tapetis (Carballal et al, 1997a;Ordás et al, 1999). The lack of mussel haemocyte CL stimulation by V. tapetis may be explained by the bacterial release of acid phosphatase (Borrego et al, 1996).…”

“…This supports the above explanation of the active scavenge of ROIs by certain pathogens, bacteria or parasites. Thus, the inhibition of the CL response of mussel haemocytes by high concentrations of P. tapetis cells could be due to the acid phosphatase secreted by the parasite (Ordás et al, 1999). Parasite cells had been washed before their addition to the haemocytes in order to eliminate the products secreted to the medium.…”

“…However, they could have released the acid phosphatase during the time of CL measurement or preincubation with haemocytes. In fact, this enzyme is secreted so rapidly that is reaches high concentrations only 3 days after the medium had been renewed (Ordás et al, 1999). To obtain the ECP, the culture medium was concentrated 10 times, so it could be assumed that in this ECP the acid phosphatase content was 10 times higher than in normal medium.…”

Phenoloxidase activity in three commercial bivalve species. Changes due to natural infestation with Perkinsus atlanticus

“…trophozoites have been associated with mass mortalities of commercially important clams of the genus Tapes [16,17], a fact that underlines the interest of studying the immune status of naturally or experimentally infected mollusc specimens. In this sense, the inflammatory reaction caused by trophozoites of this parasite has been studied [18], as have several cellular (haemocyte density and phagocytic activity) and humoral (lysozyme and anti-bacterial activities, protein concentration and agglutination titre) immune parameters, in clams collected from enzootic areas for Perkinsus atlanticus [19,20]. However, the effect of such parasitization on PO activity has not yet been determined.…”