Gene expression profiles in the testis associated with testis-ova in adult Japanese medaka (Oryziaslatipes) exposed to 17α-ethinylestradiol

The occurrence of oocytes in the testis (testis-ova) of several fish species is often associated with exposure of estrogenic chemicals. However, induction mechanisms of the testis-ova remain to be elucidated. To develop marker genes for detecting testis-ova in the testis, adult male medaka were exposed to nominal concentration of 100 ng L⁻¹ of 17α-ethinylestradiol (EE2) for 3-5 weeks, and 800 ng estradiol benzoate (EB) for 3 weeks (experiment I), and a measured concentration of 20 ng L⁻¹ EE2 for 1-6 weeks (experiment II). Histological analysis was performed for the testis, and microarray analyses were performed for the testis, liver and brain. Microarray analysis in the estrogen-exposed medaka liver showed vitellogenin and choriogenin as estrogen responsive genes. Testis-ova were induced in the testis after 4 weeks of exposure to 100 ng L⁻¹ EE2, 3 weeks of exposure to 800 ng EB, and 6 weeks of exposure to 20 ng L⁻¹ EE2. Microarray analysis of estrogen-exposed testes revealed up-regulation of genes related to zona pellucida (ZP) and the oocytes marker gene, 42Sp50. Using quantitative RT-PCR we confirmed that Zpc5 gene can be used as a marker for the detection of testis-ova in male medaka.     

二噁英暴露对成年男性血清类固醇激素的影响

为了解二噁英（PCDD/DFs）对成年男性类固醇激素水平的影响,采用高分辨气相色谱法/高分辨质谱联用法（HRGC/HRMS）及液相色谱-质谱联用法（LC-MS/MS）分析二噁英污染地区成年男性（n=50）及非污染地区成年男性（n=48）血清中9种类固醇激素水平和17种二噁英同类物浓度.结果显示成年男性血清中双氢睾酮、睾酮、雌二醇的水平与部分二噁英同类物浓度存在显著性相关.污染地区成年男性双氢睾酮、睾酮、雌二醇的水平与年龄呈显著性正相关.以上结果表明二噁英暴露导致成年男性类固醇激素中的性激素变化异常.     

Benefit of suites of defensive behavior induced by predator chemical cues on anuran tadpoles, Hyla japonica

When predator chemical cues are present, low activity of prey is a commonly seen defensive behavior. However, few studies have explored the functional implications of the defensive behaviors and, thus, elucidated the possible linkages between behavioral responses and its consequences. In this study, we experimentally investigated how behavioral responses of Hyla japonica tadpoles to predator chemical cues affect vulnerability to a dragonfly nymph Anax parthenope julius. The frequency of tadpoles attacked by dragonfly nymphs was lower with chemical cues of predator was present than without chemical cues, and most of attacks occurred when tadpoles were mobile. When tadpoles were exposed to chemical cues, on the other hand, their swimming speed was quicker and swimming distance was longer, respectively, and the rates of being approached of the swimming tadpoles by dragonfly nymph was lower than those not exposed to chemical cues. We found that the tadpoles are induced by predator chemical cues not only to generally lower activity but also to swim in bursts as additional behavior and that the suite of their behavioral responses reduce the vulnerability against dragonfly nymph. Tadpoles can receive information about the predation risks by chemical cues and adjust their defensive behavior accordingly.     

围产期二英暴露对学龄前儿童类固醇激素的影响

为揭示围产期二噁英(PCDD/DFs)暴露对学龄前儿童类固醇激素水平的影响.采用液相色谱-质谱联用法(LC-MS/MS)及高分辨气相色谱法/高分辨质谱联用法(HRGC/HRMS)分析二噁英污染地区5岁儿童(n=37)及非污染地区5岁儿童(n=44)血清中8种类固醇激素水平及母乳中17种二噁英同系物浓度.结果显示污染地区男孩血清中睾酮、双氢睾酮、脱氢表雄酮的水平明显低于非污染地区(p0.05).污染地区女孩血清中睾酮、双氢睾酮、脱氢表雄酮、17α-羟孕酮、孕酮的水平明显低于非污染地区(p0.05).上述类固醇激素与部分二噁英同系物浓度存在显著性负相关.以上结果表明围产期二■英暴露导致学龄前儿童类固醇激素水平降低.     

Residual congener pattern of dioxins in human breast milk in southern Vietnam

This study evaluated residual congener patterns of dioxin/furan (=PCDD/DF) related to tactical herbicides aerially sprayed over the regions of southern Vietnam through Operation Ranch Hand. The study focused on Cam Chinh (CC) commune, Quang Tri province (an area sprayed with tactical herbicides), and the Cam Phuc (CP) commune, Ha Tinh province (a non-sprayed area). Breast milk samples for analysis were collected in September 2002 and July 2003 from lactating primiparous and multiparous mothers born after the war (<31 years old). We found the levels of each congener in the CC commune were higher than in the CP commune, and determined specificity in the PCDD/DF congener pattern in CC commune samples by cluster analysis. The congener pattern is characterized by higher (the hexa-, the hepta-, and the octa-) chlorinated PCDD/DFs; this appears to be the same profile as that presented by pentachlorophenol (PCP), rather than 2,4,5-trichlorophenoxy acid (2,4,5-T) contaminated with 2,3,7,8-TCDD. A GC/MS study in the 1970s detected the chlorophenols 2,4-di and 2,4,6-trichlorophenol in some Agent Orange samples, which contained, like PCP, a wide variety of PCDD/DF congeners. In this context, it may be expected that certain tactical herbicides contaminated with various chlorophenol impurities, have a unique congener pattern when compared with pure 2,4,5-T formulations.     

Dioxin levels in the breast milk and estradiol and androgen levels in the saliva of Vietnamese primiparae

Human exposure to polychlorinated dibenzodioxins (PCDD) and dibenzofurans (PCDF), especially 2,3,7,8 tetrachlorodibenzo-p-dioxin (TCDD), was investigated in Vietnam since initial severe adverse health effects were reported in the late 1970s. The purpose of this study was to determine the effects of dioxin exposure on steroid hormones of primiparae in an Agent Orange/dioxin hot-spot and a non-exposed area in Vietnam. Sixteen primiparae (8 at each site), all of whom were aged between 20 and 30 years with infants aged between 4 and 16 weeks, agreed to participate in this study. The mean dioxin levels in breast milk of primiparae from the hot-spot area, in terms of PCDD, PCDF, and PCDD?+?PCDF toxic equivalents (TEQ), were significantly higher than those for the non-exposed area. PCDD TEQ, PCDF TEQ, and PCDD?+?PCDF TEQ levels showed a significant correlation with dehydroepiandrosterone (DHEA), androstenedione (A-dione), and estradiol (E2) in the saliva of primiparae in a combination of hot-spot and non-exposed areas in Vietnam. The dose–response curve between salivary E2 or A-dione levels and dioxin levels was U-shaped in humans. This study provides an overview of studies regarding dioxin hot-spots and effects on human health and steroid hormone levels in particular, with a focus on the toxicity attributed to dioxins and furans. Furthermore, causal evidence regarding the effects of dioxins on endocrine disruption in humans is provided.