牡蛎味道鲜美，富含锌、牛磺酸、糖原等营养物质，其生长快速、产量高、食物链短、经济效益良好，成为中国乃至世界重要的水产养殖贝类。我国牡蛎主要的养殖品种为长牡蛎（又称太平洋牡蛎，Crassostrea gigas）、福建牡蛎（又称葡萄牙牡蛎，C.angulata）、香港牡蛎（C. hongkongensis）、近江牡蛎（C.ariakensis）、熊本牡蛎（C. sikamea）等。目前养殖实践中出现个体变小、生长速度缓慢、生长周期变长、品质下降等现象，亟需加强牡蛎的品种选育，而多倍体育种技术的发展可以有力促进牡蛎产业向高质量的方向发展。牡蛎三倍体诱导方法包括二倍体与四倍体的生物杂交方法，温度休克、静水压、电休克、渗透压等物理诱导方法，CB、6-DMAP、咖啡因等化学诱导方法。通过本文的综述，以期为牡蛎及其他贝类的多倍体研究提供参考。

A herpes-type virus infection, the first to be found in an invertebrate animal, is reported in the oyster Crassostrea virginica. Intranuclear herpes-type viral inclusions were more prevalent in the oyster at elevated water temperatures of 28 degrees to 30 degrees C than at normal ambient temperatures of 18 degrees to 20 degrees C. The inclusions were associated with a lethal disease at the elevated temperatures.

Concomitant sporadic high mortalities were reported in France in May 1994 among batches of hatchery-reared larval Pacific oysters Crassostrea gigas and European flat oysters Ostrea edulis in 2 hatcheries, and in June and July 1994 among batches of cultured spat of both species in a shellfish nursery. Histological observation showed the presence of cellular abnormalities in moribund animals. Transmission electron microscopy revealed the presence of herpes-like virus particles in infected larvae and spat of both oyster species. This is the first description of a herpes-like virus infection in larval O. edulis. Viruses observed in diseased larvae and spat of both species are similar with respect to ultrastructure and morphogenesis. They were detected simultaneously in C. gigas and O. edulis larvae and spat, indicating possible interspecific transmission. Moreover, these viruses are associated with high mortality rates in both oyster species. An electron microscopic examination revealed hemocytes with condensed chromatin and extensive perinuclear fragmentation of chromatin. These data suggest that herpes-like viruses infecting oysters may induce apoptosis in oyster hemocytes.

High mortality rates are reported in spat and larvae of Pacific oyster Crassostrea gigas and associated with ostreid herpesvirus 1 (OsHV-1) detection in France. Although the viral infection has been experimentally reproduced in oyster larvae and spat, little knowledge is currently available concerning the viral entry and its distribution in organs and tissues. This study compares OsHV-1 DNA and RNA detection and localization in experimentally infected oysters using two virus doses: a low dose that did not induce any mortality and a high dose inducing high mortality. Real time PCR demonstrated significant differences in terms of viral DNA amounts between the two virus doses. RNA transcripts were detected in oysters receiving the highest dose of viral suspension whereas no transcript was observed in oysters injected with the low dose. This study also allowed observing kinetics of viral DNA and RNA detection in different tissues of oyster spat. Finally, viral detection was significantly different in function of tissues (p<0.005), time (p<0.005) with an interaction between tissues and time (p<0.005) for each probe. Copyright © 2015 Elsevier Inc. All rights reserved.

The real-time polymerase chain reaction (PCR) is considered to be a suitable tool for nucleic acid quantitation because it is accurate, rapid and reliable. The reference protocol for quantitation of ostreid herpesvirus 1 in Pacific oysters Crassostrea gigas is based on a Sybr(®) Green real-time PCR developed by the IFREMER laboratory. The Frank Duncombe Departmental Laboratory has developed an alternative protocol based on TaqMan(®) chemistry (alternative technique). The quantitation limits were 1000 and 18UG/mg of tissues for the reference method and alternative protocols, respectively, and the latter protocol has a detection limit of 6UG/mg of tissues. The aim of this study was to compare the two protocols using DNA samples obtained from 210 spat. The kappa index (0.41) indicated a moderate concordance between the protocols, according to the measures of Landis and Koch. All samples that were positive by the reference protocol were also positive by the alternative protocol. Of the 76 samples that were negative by the reference protocol, 49 were positives by the alternative protocol. In conclusion, the alternative protocol is an improvement of the reference protocol in terms of sensitivity, specificity and rapidity (<3h).Copyright © 2010 Elsevier B.V. All rights reserved.

Ostreid Herpesvirus 1 (OsHV-1) was likely detected in Pacific oysters, Crassostrea gigas, at different stages of development. Viral infections were associated with high mortality rates in the spat and larvae. Furthermore, the persistance of OsHV-1 in asymptomatic adults was demonstrated by detection of viral DNA and proteins. In the present study, three successive generations of C. gigas (G0 and G1 parental oysters, G1 and G2 larvae) were screened for OsHV-1 by PCR. Viral DNA was detected in 2-day-old larvae, indicating that infection may take place at very early stages. Although results strengthen the hypothesis of a vertical transmission, it was not possible to predict the issue of a particular type of cross. Indeed, the detection of viral DNA in parental oysters did not systematically correspond to a productive infection or result in a successful transmission to the progeny. However, the infective status of the parents appeared to have an influence on both the infection and the survival rates of the progeny. Crosses involving an OsHV-1 infected male and a non-infected female resulted in hatching and larval survival rates statistically lower than those observed in the other types of cross. These results suggest that OsHV-1-infected females may transmit to their offspring some kind of protection or resistance against viral infection.