Defense factors in clam extrapallial fluids
نویسندگان
چکیده
The extrapallial fluid of clams is located between the external epithelium of the mantle and the Inner face of the shell. The pallial line separates the fluid into central and peripheral extrapallial fluids (CEF and PEF, respectively). These fluids are the sites of biomineralization, but th(,ir role in other biological processes, such as defense, remains unknown. A comparative study of some characteristics of the cellular and humoral fractions of the extrapallial fluids and hemolymph of the Manila clam Ruditapesphilippinarum was carried out. Both CEF and PEF contained abundant hemocytes cornparable to those found in hemolymph. Total and viable hemocyte counts were high especially In the CEF. Extrapallial fluid cell lysate and supernatant showed significant bacteriolytic (lysozyme-like) activity. The CEF was found to be bacteriologically sterile. This sterility may result from the presence in the CEF of significant defense factors in the form of numerous macrophage-like cells and high lysozyme activity. These findings are of interest in the case of bivalves susceptible to shell diseases such as R. philippinarum, which is suscept~ble to a bacterial disease caused by Vibrio tapetis.
منابع مشابه
Alterations in hemolymph and extrapallial fluid parameters in the Manila clam, Ruditapes philippinarum, challenged with the pathogen Vibrio tapetis.
In a recent study, we demonstrated the presence of defense factors, competent hemocytes and high enzymatic activities (peptidases, hydrolases, lytic, etc.), in the extrapallial fluid, located between the mantle and the shell, of the Manila clam, Ruditapes philippinarum. In Europe, this species is affected by brown ring disease, an epizootic disease caused by the bacterium Vibrio tapetis. The pr...
متن کاملIsolation of the pathogen Vibrio tapetis and defense parameters in brown ring diseased Manila clams Ruditapes philippinarum cultivated in England.
The Manila clam Ruditapes philippinarum was introduced for aquacultural purposes to Europe in the 1970s. In 1987, brown ring disease (BRD), caused by Vibrio tapetis, appeared in clams cultivated in Brouënou (Finistère, France) and later became increasingly widespread and was reported in cultivated and wild clams existing on the Atlantic coasts of France and Spain. The present study reports, for...
متن کاملDevelopment of a Taqman real-time PCR assay for rapid detection and quantification of Vibrio tapetis in extrapallial fluids of clams
The Gram-negative bacterium Vibrio tapetis is known as the causative agent of Brown Ring Disease (BRD) in the Manila clam Venerupis (=Ruditapes) philippinarum. This bivalve is the second most important species produced in aquaculture and has a high commercial value. In spite of the development of several molecular methods, no survey has been yet achieved to rapidly quantify the bacterium in the...
متن کاملTranscriptional changes in Manila clam (Ruditapes philippinarum) in response to Brown Ring Disease.
Brown Ring Disease (BRD) is a bacterial infection affecting the economically-important clam Ruditapes philippinarum. The disease is caused by a bacterium, Vibrio tapetis, that colonizes the edge of the mantle, altering the biomineralization process and normal shell growth. Altered organic shell matrices accumulate on the inner face of the shell leading to the formation of the typical brown ring...
متن کاملPathogenicity of Vibrio tapetis, the etiological agent of brown ring disease in clams.
Brown ring disease (BRD) causes high mortalities in the introduced Manila clam Ruditapes philippinarum cultured in western Europe. The etiological agent of BRD, Vibrio tapetis, adheres to and disrupts the production of the periostracal lamina, causing the anomalous deposition of periostracum around the inner shell. Because the primary sign of BRD is found outside the soft tissues, the processes...
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