Effects of Chinese domestic polychlorinated biphenyls (PCBs) on gonadal differentiation in Xenopus laevis.

Abstract

To determine whether polychlorinated biphenyls (PCBs) influence gonadal differentiation in Xenopus laevis, tadpoles were exposed to two Chinese domestic PCBs (PCB 3 and PCB 5) from Nieuwkoop and Faber stage 46/47 to complete metamorphosis. Gonads were characterized using a dissecting microscope. The control X. laevis had normal ovaries or testes in gross morphology, whereas obviously abnormal testes including ovotestes were found in PCB 3- and PCB 5-exposed groups. Ovotestes were characterized by morphologic ovaries in the cranial and caudal parts and morphologic testes in the middle part. PCBs did not alter the percentage of females but reduced the percentage of males with morphologically normal testes. The histologic structure of gonads was examined by a series of sections. Morphologically normal and abnormal testes from a few frogs exposed to PCBs were interspersed with oocytes in histologic sections. These testes exhibited looser structure with fewer seminiferous tubes, spermatogonia, and spermatozoa than in controls. The findings suggest that PCB 3 and PCB 5 have significant feminization effects on gonadal differentiation in X. laevis and that this species is sensitive to endocrine disruption and may be used as a good model to study endocrine disruption. Key words: endocrine disruptor, gonadal differentiation, ovotestis, PCB 3, PCB 5, polychlorinated biphenyls, Xenopus laevis. Environ Health Perspect 111:553–556 (2003). doi:10.1289/ehp.5620 available vi

Xenopus laevis is a potential alternative model animal species to study reproductive toxicity of phytoestrogens

“…In 1999, Kloas et al reported that bisphenol A and 4-nonylphenol caused a significantly higher number of female phenotypes compared to control X. laevis, which is the first evidence that endocrine disruptor can induce feminization in X. laevis (1999). Since then, there has been increasing data on feminizing effects of endocrine disruptors on X. laevis, such as atrazine, polychlorinated biphenyls and bisphenol A (Hayes et al, 2002;Qin et al, 2003;Levy et al, 2004) despite contrary results reported as well Carr et al, 2003). In this study, we for the first time report that the phytoestrogen quercetin also has influence on the gonadal developemt in X. laevis.…”

“…Miyata et al treated X. laevis with 100 g/L estradiol (E 2 ) and obtained 100% females (1999). There is increasing evidence that endocrine disruptors with estrogenic activities also can induce gonadal feminization in X. laevis and affect sexual hormone homeostasis (Kloas et al, 1999;Hayes et al, 2002;Qin et al, 2003;Levy et al, 2004). In our previous study, X. laevis was suggested to be good model animal for assaying endocrine disruptors (Qin et al, 2003).…”

Levels and Vertical Distributions of PCBs, PBDEs, and OCPs in the Atmospheric Boundary Layer: Observation from the Beijing 325-m Meteorological Tower

“…PCBs. Annual PCB production in China was estimated to be ten thousand tonnes between 1965 and 1974 (20). Because PCBs have been banned, current atmospheric PCB pollution is likely due to emissions from disposal or accidental release of products containing PCBs and volatilization from environmental reservoirs.…”

Evidence for the transfer of polychlorinated biphenyls, polychlorinated dibenzo-p-dioxins, and polychlorinated dibenzofurans from soil into biota

“…The domestic products of technical PCBs were named PCB 3 and PCB 5 , which compositions were almost similar to those of Arochlor 1242 and 1254, respectively (Jang et al, 1997). China's total production was 10,000 t of which 9000 t was PCB 3 and 1000 t was PCB 5 (Qin et al, 2003). Most of PCB 3 products have been used as dielectric fluids in electric capacitors, and most of PCB 5 products as additives in paints (Jang et al, 1997).…”