Identification, functional characterization, and estrogen regulation on gonadotropin-releasing hormone in the spotted scat, Scatophagus argus.

Gonadotropin-releasing hormone (GnRH) is a key neuropeptide of the reproductive system. However, little is known about the role of GnRH in the spotted scat (Scatophagus argus). Here, three GnRH subtypes (cGnRH-II, sGnRH, and sbGnRH) were identified in the spotted scat. cGnRH-II and sGnRH were only expressed in the brains and gonads of both male and female fish, exhibiting a tissue-specific expression pattern, while sbGnRH was expressed at different transcription levels in all examined tissues. During ovarian maturation, hypothalamus-associated sbGnRH was upregulated, while the expression of sGnRH was variable and cGnRH-II first increased and then decreased. In vivo experiments showed that sbGnRH significantly promoted the expression of fsh and lh genes in a dose-dependent manner and exhibited a desensitization effect on lh expression at high concentrations. For sGnRH and cGnRH-II, only high concentrations could induce fsh and lh expression. Furthermore, treatment with highly concentrated sbGnRH peptide also induced fsh and lh expression, whereas the sGnRH and cGnRH-II peptides only induced fsh expression in vitro. 17ß-Estradiol (E2) significantly inhibited the expression of sbGnRH mRNA in a dose-dependent manner and did not impact sGnRH and cGnRH-II mRNA levels in vivo or in vitro. The inhibitory effect of E2 on sbGnRH expression was attenuated by the estrogen receptor (ER) broad-spectrum antagonist (fulvestrant) and the ERα-specific antagonist (methyl-piperidinopyrazole), respectively, implying that the feedback regulation on sbGnRH is mediated via ERα. This study provides a theoretical basis for the reproductive endocrinology of the spotted scat by studying GnRH.

[Epidemic situation of schistosomiasis in a provincial surveillance site of Shengzhou City, 2008-2011].

According to "The Scheme of Schistosomiasis Surveillance in Zhejiang Province", the status of Oncomelania snails, and the schistosome infection of permanent residents, floating population, and livestock were surveyed in a provincial surveillance site of Shengzhou City, from 2008 to 2011. In 4 years, the area with residual snails was 3,060 m2, and no infected snails were found among 595 living snails. The positive rate of sero-tests for schistosomiasis of the permanent residents was 0.77%, and that of the floating population was 1.09%. No schistosomiasis cases were found. In conclusion, the area with residual snails is small and its distribution is scattered, and we still should strengthen the surveillance of snail status and imported schistosomiasis cases.