No abstract

No abstract

Perkinsus is the pathogen responsible for mass mortality of the Manila clam Ruditapes philippinarum. Perkinsus sp. isolated from Manila clams collected in Korean waters was assayed by polymerase chain reaction (PCR) to determine its phylogenetic affinity with other congeneric species. Regions of rRNA of Perkinsus sp. isolated from clam haemolymph were cloned and sequenced. Sequences of a non-transcribed spacer (NTS), internal transcribed spacers (ITS 1, 2) and 5.8S rRNA genes were compared to those available from other Perkinsus species. The NTS sequence of Korean Perkinsus was approximately 99.9 to 100% similar to that of P. atlanticus and 98.06 to 98.15% and 73.05 to 73.14% similar to those of P. olseni and P. marinus, respectively. The ITS 1, 5.8S rRNA and ITS 2 sequences of Korean Perkinsus showed 100% similarity to P. atlanticus and Perkinsus sp. reported from Japan. The ITS-5.8S rRNA sequences of Korean Perkinsus were 99.86 and 93.73% similar to those of P. olseni and P. marinus, respectively. The sporulation pattern and morphology of the Korean Perkinsus were very similar to those of P. atlanticus. Our data suggest that the Perkinsus sp. isolated from clams in Korean waters is P. atlanticus, which is currently synonymous with P. olseni reported from Australia. By considering that P. olseni has taxonomic priority, Korean Perkinsus sp. is accepted as P. olseni (atlanticus). KEY WORDS: NTS · ITS · 5.8S rRNA · Perkinsus olseni (atlanticus) · Ruditapes philippinarum · Taxonomy · Korea Resale or republication not permitted without written consent of the publisherDis Aquat Org 66: [255][256][257][258][259][260][261][262][263] 2005 P. qugwadi in the Japanese scallop Patinopecten yessoensis on the west coast of Canada (Blackbourn et al. 1998), and P. andrewsi in the Baltic clam Macoma balthica (Coss et al. 2001) and P. chesapeaki in the softshell clam Mya arenaria (McLaughlin et al. 2000), both in Chesapeake Bay, USA. Casas et al. (2004) recently reported a new species of Perkinsus, P. mediterraneus, from the European flat oyster Ostrea edulis from the Balearic Islands in the Mediterranean Sea.Unidentified Perkinsus species have been isolated from Ruditapes philippinarum along the coasts of Korea and Japan (Choi & Park 1997, Choi et al. 1998, Hamaguchi et al. 1998, Park & Choi 2001, as well as along the north-eastern coast of China, in the Yellow Sea (Liang et al. 2001). Hamaguchi et al. (1998) analysed the nucleotide sequences of 2 internal transcribed spacers (ITS 1 and ITS 2) and 5.8S rRNA of Perkinsus isolated from clams in Kumamoto and Hiroshima, Japan. ITS sequences of Perkinsus from Japanese clams were almost identical to those of P. atlanticus and P. olseni, suggesting that Perkinsus isolated from clams in Japan may be conspecific with, or closely related to P. atlanticus in European waters. Size and microscopic features of hypnospores and trophozoites of Perkinsus isolated from the Manila clam in Korea were very similar to those of P. atlanticus (Park & Choi 2001), suggesting that Perkinsus ...

Abstract. Pyrethroid insecticides are among the most commonly used classes of insecticides worldwide, but their endocrine disrupting activities remain unclear. Therefore, in the present study, we examined the estrogenic activities of pyrethroid insecticides in E-screen and competition binding assays. In addition, we measured estrogen receptor (ER) protein and pS2 mRNA levels in human breast cancer cells (MCF-7 BUS) to clarify the mechanism of their estrogenicity. Seven pyrethroid insecticides (bioallethrine, cypermethrin, deltamethrin, fenvalerate, permethrin, sumithrin, and tetramethrin) were tested because of their worldwide usage. In addition, 17β-estradiol was tested as a positive control. As expected, 17β-estradiol significantly increased MCF-7 BUS cell proliferation at concentrations of 10 -11 M and above. Of the pyrethroid insecticides tested, only sumithrin increased MCF-7 BUS cell proliferation in a dose-dependent manner; the maximum induction of cell proliferation was observed at a dose of 10 -5 M. In the anti-estrogenic activity test, bioallethrin, fenvalerate, and permethrin significantly inhibited 17β-estradiol-induced MCF-7 BUS cell proliferation at 10 -6 M, a concentration comparable to the effective dose (10 -9 M) of ICI 182,780, a pure ER antagonist. However, none of the pyrethroid insecticides competitively inhibited the binding of [ 3 H]estradiol to rat uterus ERs in competition binding assays. Both 17β-estradiol (10 -10 M) and sumithrin (10 -5 M) decreased the levels of cytosolic ERα and ERβ protein expression significantly as compared with the vehicle control. In addition, 17β-estradiol (10 -10 M) increased pS2 mRNA expression markedly, and sumithrin significantly increased pS2 mRNA levels in a dose-dependent manner. The other six compounds tested in the present study did not affect ER protein levels or pS2 mRNA levels. These results suggest that certain pyrethroid insecticides may be considered to be estrogen-like chemicals that act through pathways other than direct ER binding, and may function as endocrine modulators in both wildlife and humans.