Numerical variations and spontaneous malformations in the early embryos of the Korean salamander, Hynobius leechii, in the farmlands of Korea.

Embryo sacs of the Korean salamander, Hynobius leechii, were collected from nine farmlands in Gyeongsangnam-Do, Korea, in early spring of 2002 and 2004. The variations in the number of embryos within each embryo sac and the mortality and abnormality rates among the embryos were investigated. We also analyzed the patterns of spontaneous embryonic malformations and the residual chemicals in the soil of the habitats using multiple-residue GC/MS. A total of 79,195 embryos were obtained from 1933 embryo sacs. There were regional variations in the length of individual embryo sacs and the number of embryos in each. The longest embryo sac averaged by region measured 20.67 cm ± 3.51 and was obtained from 2-Banseong in 2002. Of the embryos collected, 13.71% either died or stopped developing, and 3.54% of the hatched embryos developed abnormally; the latter were classified according to the patterns of malformation. External gill dysplasia was the most frequent malformation, and caudal dysplasia, abdominal blisters, and dysplasia of the fin were also observed frequently. Histopathological analysis showed neural tube abnormalities, acrania, curved notochords, thyroid teratoma, and various other kinds of endodermal developmental abnormalities. In the analysis of the residual pesticides in the soil, carbofuran, endosulfan-sulfate, and endosulfan-ß were detected in the regions with high mortality and malformation rates. These results indicate that various agricultural chemicals and other unknown factors may cause the aforementioned forms of spontaneous malformations in the embryos of Hynobius leechii.

[Expression of Cdx-2 homeobox gene in intestinal metaplasia and gastric adenocarcinoma].

BACKGROUND/AIMS: The Cdx-1 and Cdx-2 genes are intestinal transcription factors that may be involved in the regulation of proliferation and differentiation of intestinal epithelial cells. The Cdx-1 and Cdx-2 are expressed in the epithelium of the small intestine and colon but not in the normal epithelium of the esophagus and stomach. Conversely, aberrant Cdx-2 expression is often observed in the esophagus and stomach. We investigated the expression and role of Cdx-2 in intestinal metaplasia and gastric adenocarcinoma. METHODS: The gastric tissues obtained endoscopically were analyzed by the reverse transcriptase-polymerase chain reaction and histology. The Cdx-1 and Cdx-2 mRNA expression was confirmed and analyzed according to updated Sydney classification. Then, immunohistochemical study with monoclonal anti-Cdx-2 antibody was performed with gastric adenocarcinoma obtained by surgical resection. RESULTS: The prevalence of Cdx-1 and Cdx-2 mRNA expression was significantly higher in mucosa with intestinal metaplasia than mucosa without intestinal metaplasia. In immunohistochemical study, nuclear staining of Cdx-2 was strong in metaplastic mucosa, but weak in adjacent normal gastric mucosa (p<0.001). The expression of Cdx-2 in gastric adenocarcinoma was lower than in metaplastic mucosa (p<0.001). The Cdx-2 expression was also detected in 97% of intestinal type gastric adenocarcinoma and 61.5% of diffuse type gastric adenocarcinoma (p=0.003). CONCLUSIONS: Aberrant expression of Cdx-2 is observed in intestinal metaplasia and a subset of gastric adenocarcinoma, which is predominant in intestinal-type gastric adenocarcinoma. Therefore, Cdx-2 may play an important role in gastric carcinogenesis, especially in intestinal type adenocarcinoma.