TY - JOUR
T1 - Relationship between Marteilioides chungmuensis infection and reproduction in the Pacific oyster, Crassostrea gigas
AU - Tun, Kay Lwin
AU - Endo, Naoki
AU - Ueki, Noriyuki
AU - Yoshinaga, Tomoyoshi
AU - Ogawa, Kazuo
PY - 2007/11/1
Y1 - 2007/11/1
N2 - Marteilioides chungmuensis, a protozoan paramyxean parasite, infects the oocytes of the Pacific oyster, Crassostrea gigas. The effects of infection on the reproductive cycle of C. gigas were investigated over two consecutive years at Okayama Prefecture, Japan. In male oysters, gonadal development began during February/March, maturity was achieved in June and spawning activity extended from July to September. In November and December, male oysters were not seen, probably because their gonads regressed to connective tissue and they transformed into undifferentiated oysters. By contrast, female oysters, in which parasite spore formation occurred, were still carrying oocytes until the following March and the spawning process of female oysters took 5 months longer than that of males in epizootic areas. The prevalence of M. chungmuensis infection increased from July to September, when most female oysters had their spawning period, and declined from October to the following April when oysters were at the spent stage. The prevalence of infection increased again in May of the following year and high prevalence was observed in the following July. When prevalence was compared between oysters of different age classes, higher prevalence was detected in older than in younger oysters. Histological examination showed that infected oysters produced oocytes continuously and spawned repeatedly from October to March, during which period healthy oysters were reproductively inactive. Parasites can infect the oocytes of infected oysters throughout the longer spawning period. These observations suggest that M. chungmuensis extends the reproductive period of infected oysters for its own reproductive benefit.
AB - Marteilioides chungmuensis, a protozoan paramyxean parasite, infects the oocytes of the Pacific oyster, Crassostrea gigas. The effects of infection on the reproductive cycle of C. gigas were investigated over two consecutive years at Okayama Prefecture, Japan. In male oysters, gonadal development began during February/March, maturity was achieved in June and spawning activity extended from July to September. In November and December, male oysters were not seen, probably because their gonads regressed to connective tissue and they transformed into undifferentiated oysters. By contrast, female oysters, in which parasite spore formation occurred, were still carrying oocytes until the following March and the spawning process of female oysters took 5 months longer than that of males in epizootic areas. The prevalence of M. chungmuensis infection increased from July to September, when most female oysters had their spawning period, and declined from October to the following April when oysters were at the spent stage. The prevalence of infection increased again in May of the following year and high prevalence was observed in the following July. When prevalence was compared between oysters of different age classes, higher prevalence was detected in older than in younger oysters. Histological examination showed that infected oysters produced oocytes continuously and spawned repeatedly from October to March, during which period healthy oysters were reproductively inactive. Parasites can infect the oocytes of infected oysters throughout the longer spawning period. These observations suggest that M. chungmuensis extends the reproductive period of infected oysters for its own reproductive benefit.
KW - Crassostrea gigas
KW - Gonadal development
KW - Marteilioides chungmuensis
KW - Oocyte
KW - Pacific oyster
KW - Parasite
KW - Prevalence
UR - http://www.scopus.com/inward/record.url?scp=35348839014&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=35348839014&partnerID=8YFLogxK
U2 - 10.1016/j.jip.2007.06.001
DO - 10.1016/j.jip.2007.06.001
M3 - Article
C2 - 17643446
AN - SCOPUS:35348839014
VL - 96
SP - 205
EP - 212
JO - Journal of Invertebrate Pathology
JF - Journal of Invertebrate Pathology
SN - 0022-2011
IS - 3
ER -