Experimentally induced variation in hemocyte density for Ruditapes philippinarum and R. decussatus (Mollusca, Bivalvia) (original) (raw)
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Morphological Characterization of the Hemocytes of the Clam,Ruditapes decussatus(Mollusca: Bivalvia)
Journal of Invertebrate Pathology, 1997
Josef Berger and Klára Slavíčková (2008) Morphological characterization of hemocytes in the adult linden bug, Pyrrhocoris apterus (L.) (Heteroptera). Zoological Studies 47(4): xxx-xxx. The morphology of hemocytes of the adult linden bug, Pyrrhocoris apterus (L.) (Heteroptera) was characterized via light (both classical and confocal) and transmission electron microscopy. Based on this characterization, we classified hemocytes into 4 distinct types: prohemocytes, granulocytes, plasmatocytes, and spherulocytes. Differential hemocyte counts are described. We propose using the Pappenheim panoptic stain to identify different hemocyte populations of P. apterus. These results are the beginning building blocks of a knowledge base for our ongoing studies of the function of P. apterus hemocytes. As certain morphological characteristics are similar to mammalian blood cells which are used in hemotoxicological safety screening, the use of P. apterus as a new hematotoxicological biomodel is suggested.
Helgoländer Meeresuntersuchungen, 1984
Hemocytes represent one of the most important defense mechanisms against foreign material in Mollusca. The morphology, hematological parameters and behaviour of hemolymph cells were studied in the southern quahog Mercenaria campechiensis, the eastern oyster Crassostrea virginica, and the blood ark Anadara ovalis challenged with the bacteria Vibrio vulnificus and V. anguillarum. Two general classes of hemocytes (granular and agranular) exist in C. virginica and M. campechiensis. In contrast, A. ovalis possesses 3 general classes (granular, agranular and erythrocytes). Three types of granules were identified by light microscopy. When hemolymph cells were studied by transmission electron microscopy, the cytoplasm of hemolymph cells was noted to contain many organelles, including electron dense granules. Both agranular and granular hemolymph cells were capable of colchicine-sensitive pseudopodial movement and spreading. The results indicate that marine bivalves possess hemolymph blood cells which may play a role in the internal defense paralleling mammalian phagocytes. The morphology of these cells, as determined by light, scanning and transmission electron microscopy, showed some similarity to mammalianmononuclear phagocytes. The sub-cellular events of molluscan hemocyte phagocytosis of V. vulnificus and V~ anguillarum were studied by both scanning and transmission electron microscopy. The role of these cells and the factors which govern their behavior are of economic and public health importance.
Diseases of Aquatic Organisms, 1997
Phagocytosis of foreign materials by haemocytes is an important aspect of the internal defence of bivalve molluscs. Two main haemocyte types can be distinguished in the haemolymph of the clam Ruditapes decussatus: granulocytes and hyalinocytes. The ability of clam haemocytes to phagocytose zymosan particles, Vibrio P1 cells and trophozoites of the protistan parasite Perkinsus atlant~cus was demonstrated by means of in vitro assays. However, clam haemocytes did not phagocytose atlanticus zoospores in the assays. Granulocytes showed the highest phagocytic capacity in each assay. Phagocytic capacity of haemocytes was not significantly affected by clam age. An ultrastructural study of phagocytosis showed the following sequence of events: engulfment of particles by pseudopods, formation of a phagocytic vacuole, fusion of lysosomes with the phagocytic vacuole, and digestion of the particles giving rise to residual bodies that might be discharged.
Fish & Shellfish Immunology, 2011
Most experimental procedures on molluscs are done after acclimatization of wild animals to lab conditions. Similarly, short-term acclimation is often unavoidable in a field survey when biological analysis cannot be done within the day of sample collection. However, acclimatization can affect the general physiological condition and particularly the immune cell responses of molluscs. Our aim was to study the changes in the hemocyte characteristics of the Pacific oyster Crassostrea gigas and the carpet shell clam Ruditapes decussatus acclimated 1 or 2 days under emersed conditions at 14 AE 1 C and for 1, 2, 7, or 10 days to flowing seawater conditions (submerged) at 9 AE 1 C, when compared to hemolymph withdrawn from organisms sampled in the field and immediately analyzed in the laboratory (unacclimated). The hemocyte characteristics assessed by flow cytometry were the total (THC) and differential hemocyte count, percentage of dead cells, phagocytosis, and reactive oxygen species (ROS) production. Dead hemocytes were lower in oysters acclimated both in emersed and submerged conditions (1%e5%) compared to those sampled in the field (7%). Compared to oysters, the percentage of dead hemocytes was lower in clams (0.4% vs. 1.1%) and showed a tendency to decrease during acclimatization in both emersed and submerged conditions. In comparison to organisms not acclimated, the phagocytosis of hemocytes decreased in both oysters and clams acclimated under submerged conditions, but was similar in those acclimated in emersed conditions. The ROS production remained stable in both oysters and clams acclimated in emersed conditions, whereas in submerged conditions ROS production did not change in both the hyalinocytes and granulocytes of oysters, but increased in clams. In oysters, the THC decreased when they were acclimated 1 and 2 days in submerged conditions and was mainly caused by a decrease in granulocytes, but the decrease in THC in oysters acclimated 2 days in emersed conditions was caused by a decrease in hyalinocytes and small agranular cells. In clams, the THC was significantly lower in comparison to those not acclimated, regardless of the conditions of the acclimatization. These findings demonstrate that hemocyte characteristics were differentially affected in both species by the tested conditions of acclimatization. The phagocytosis and ROS production in clams and phagocytosis in oysters were not different in those acclimated for 1 day under both conditions, i.e. emersed and submerged, and those sampled in the field (unacclimated). The THC was significantly affected by acclimatization conditions, so the differences between clams and oysters should be considered in studies where important concentrations of hemocytes are required. The difference in the immune response between both species could be related to their habitat (epifaunal vs. infaunal) and their ability of resilience to manipulation and adaptation to captivity. Our results suggest that functional characteristics of hemocytes should be analyzed in both oysters and clams during the first 1 or 2 days, preferably acclimated under emersed rather than submerged conditions.
Characterization of hemocytes from different body fluids of the eastern oyster Crassostrea virginica
Fish & shellfish immunology, 2017
Bivalve hemocytes are involved in a variety of physiological and immunological functions. Circulating hemocytes in the hemolymph represent the main component of the internal self-defense system while hemocytes present in the extrapallial space (between the mantle and the shell) are actively involved in biomineralization and shell formation. This study focused on the characterization of hemocytes from different body fluids of the eastern oyster Crassostrea virginica. Hemocytes present in the hemolymph were compared to those contained in the extrapallial fluid. Hemocytes associated with the mucus layer covering pallial organs (mantle, gills, body wall) were also investigated because of their potential role as sentinel cells. Hemocytes were characterized using flow cytometry in conjunction with fluorescent epitope markers (clusters of differentiation, lectins) as well as functional assays (i.e. phagocytosis and reactive oxygen species -ROS). Compared with the hemolymph, there was a sig...
Aquaculture, 2007
High variability among individuals is often encountered when hemocyte characteristics are measured in bivalves. Such variability is suspected to result partly from genetic factors. In this study, hemocyte characteristics of six families of Crassostrea gigas were compared by flow cytometry at one sampling date in October 2001. These families were obtained from a nested, half-sibling cross design, and reared from July to October 2001 at three sites distributed along the French Atlantic coast from north to south: Baie des Veys (Normandy), Rivière d'Auray (Brittany) and Ronce (Marennes-oléron Basin, Poitou Charentes). Among the 15 measured hemocyte characteristics, production of reactive oxygen species (ROS) of untreated hemocytes (maintained in filtered sterile seawater) and treated hemocytes (zymosan at 20 particles per hemocyte, and with Vibrio sp. S322 at 50 bacteria per hemocytes) was the most notably different between families. This supports the existence of a genetic basis, at least partly, for the hemocyte characteristics of oysters, and especially for ROS production. Among the six families analyzed, three have shown high survival during summer (named as "resistant", mean mortality 5.2 %) and three experienced high mortality during summer (named as "susceptible", 30.6% mean mortality). Families showing high or low survival to summer mortality had similar hemocyte characteristics, regardless of the environmental conditions or reproductive state. Resistant families were observed to have higher total hemocyte counts and lower production of ROS than susceptible families. Moreover, ROS production of hemocytes from susceptible families was diminished significantly more by pathogenic Vibrio than that of resistant families. However, this study demonstrates also that rearing site strongly affected the hemocyte characteristics of all families of oysters, most notably hemocyte concentration and morphology (size and granularity), production of reactive oxygen species (ROS), and susceptibility to the cytotoxic activity of the pathogenic Vibrio sp. S322 (50 bacteria/ hemocyte). Food availability and reproductive state are the most probable explanations for the site differences observed. Finally, it appeared difficult to link oyster survival during summer mortality to hemocyte profiles evaluated at one sampling date; other relevant indicators would probably help explaining oyster survival during summer mortality events.
… Journal of Fisheries …, 2003
In the last few years, the Manila clam (Tapes philippinarum) has been subjected to intense fishing effort in the Lagoon of Venice owing to their commercial importance. Because of the lack of data concerning fishing-induced immunomodulation in bivalves, the consequences of fishing impact on functional responses of clam haemocytes were investigated. Clams were seasonally collected from September 2000 to July 2001 from three sites: S. Angelo, a freefishing area, and Chioggia, inside a licensed area for clam culture, in two zones characterised by fishing and nonfishing, respectively. Haematocrit, phagocytosis, Neutral Red retention time, and lysozyme and superoxide dismutase activities were evaluated. No clear fishing effect was recorded, whereas a seasonal pattern of the cell parameters analysed was revealed. Alterations in functional responses of haemocytes seem to be more closely dependent on seasonal variations in both environmental parameters and physiological status of clams than on stress caused by fishing, and they may also be related to adaptation strategies of bivalves.
… on Invertebrate and …, 1991
The chief importance of J'hemocytes as immune effectors in molluscs has led to develop researches for in vitro culture. The chemiluminescence technique has been used to estimate the phagocytosis capacity of Crassostrea gigas hemocytes according to different culture media and times. Sea water was used as a basic medium. Additives, such as antibiotics or glucose and buffers, such as Tris or Hepes, were tested as weIl as artificial sea water. Hemocyte chemiluminescence activities were recorded at t=o in relation to the medium composition. The highest values were observed when hemocytes were kept in sea water without any modification. Whichever medium, chemiluminescence activity was substantially decreased when hemocytes were previously kept in vitro for a few hours. Thus, chemiluminescenee~techniquecould be a well-adapted method to estimate the funetional capaeity of mollusc hemocytes and to study medium composition in prospect of long-term molluscan cell cultures. Despite present limitations of short-term hemocyte primarycultures, they were used to study in vitro the interactions between hemocytès and some mollusc-specific pathogens. The hemoeyte recognition and entry mechanisms of Bonamia ostreae (Protozoa: Ascetospora), an intrahaemocytic parasite of fIat oyster Ostrea edulis, were investigated. Moreover, it was demonstrated that hemocyte respiratory burst was not triggered during parasite phagocytosis. Similar experiments were performéd wi th St-Jacques scallop (Pecten maximus) hemocytes and a host-specifie gill Rickettsialeslike organism, leading to evidenee some pathogen adaptation for escaping host-immune response. These first in vitro models extrapolated to other pathogens anti-infectious immune response of
Aquatic Toxicology, 2007
This study assessed the possible combined effects of harmful algae and parasite infection on hemocyte and hemolymph parameters of a bivalve mollusc. Manila clams Ruditapes philippinarum, were exposed for 1 week, under controlled laboratory conditions, to bloom concentrations of two cultured dinoflagellates: Karenia selliformis, and Karenia mikimotoi, with demonstrated, sub-lethal, pathological effects upon these bivalves. Each dinoflagellate treatment was added to a basal diet of Chaetoceros neogracile; controls consisted of clams fed only C. neogracile.