Lingbin Sun

Chronic Exposure to Phenanthrene Influences the Spermatogenesis of Male Sebastiscus marmoratus: U-Shaped Effects and the Reason for Them

Phenanthrene (PHE) is one of the most abundant polycyclic aromatic hydrocarbons in the aquatic environment. This study was conducted to investigate the effects of PHE at environmentally relevant concentrations on testicular development in male Sebastiscus marmoratus. After 50 days exposure, the gonadosomatic indices and percentage of sperm produced showed a U-shaped dose response. The levels of salmon-type gonadotropin releasing hormone, follicle-stimulating hormone, luteinizing hormone mRNA, 17β-estradiol, and γ-glutamyl transpeptidase activity all showed a U-shaped dose response, which clearly demonstrated the U-shaped effects of PHE exposure on spermatogenesis and also elucidated the action pathway. This result would bring a difficulty and a challenge to any risk assessment of PHE exposure to the reproductive health of fishes. Thus far, there has been no ready explanation for a U-shaped dose-response curve, which is well recognized as a hormetic phenomenon for many hormones, drugs, and toxic compounds. In the present study, PHE accumulation in the brain showed an inverse U-shaped increase compared to the control. Glutathione S-transferase activity in the brain showed a U-shaped dose-response, which was related with the PHE accumulation. These results have given a reasonable explanation for the U-shaped dose-response via alteration of biotransformation enzyme activity in the brain.

Pyrene exposure influences the thyroid development of Sebastiscus marmoratus embryos

Thyroid hormones play crucial roles in regulating development, morphogenesis, growth, and behavior in fishes. Some environmental pollutants have adverse effects on either development or function of the thyroid gland in fish. However, there are few reports on the effects of polycyclic aromatic hydrocarbons (PAHs) on fish thyroid. In the present study, rockfish (Sebastiscus marmoratus) embryos were exposed to pyrene (Py) for 5 days at the concentrations of 0.5, 5, and 50 nmol/L. The results showed that Py exposure decreased the expression of thyroid primordium markers, Pax2.1 and Nk2.1a as detected by quantitative PCR and in situ hybridization, and reduced the concentration of T(3), but not T(4). Thyroid receptor genes (TRα and TRβ) expression was down-regulated by Py. At the same time, Py exposure impaired the expression of thyroid development related genes, Fgfr2 and Hoxa3a expression, and altered the mRNA levels of thyroid function related genes, Deio1, Ttr, and Tg. In conclusion, the results demonstrated Py exposure inhibited thyroid development and influenced the function of thyroid system in rockfish embryos.

Association of Serum Heavy Metals and Trace Element Concentrations with Reproductive Hormone Levels and Polycystic Ovary Syndrome in a Chinese Population

To investigate the serum concentrations of 11 heavy metals and trace elements in patients with polycystic ovary syndrome (PCOS). A total of 369 women (including 96 patients with PCOS) were studied. No differences with statistical significance in the median barium, cadmium, lead, arsenic, chromium, gallium, strontium, and vanadium concentrations were observed between the patients with PCOS and the control group. Serum nickel (Ni) (P = 0.000) and copper (Cu) (P = 0.000) levels were significantly higher, but zinc (Zn) levels (P = 0.009) were significantly lower in patients with PCOS compared with the control group. The results of the association between metal levels and hormone levels indicated that Ni, Cu, and Zn may play a role in the pathogenesis of PCOS related with reproductive hormone levels. The findings in the present study should be investigated with further trials in order to obtain new insights into PCOS.

Reproductive and transgenerational toxicities of phenanthrene on female marine medaka (Oryzias melastigma).

Phenanthrene (PHE) is one of the most abundant polycyclic aromatic hydrocarbons in the aquatic environment and often results from oil spills. To assess the effects of PHE on fish, marine medaka (Oryzias melastigma) was exposed to PHE at 0.06, 0.6, 6 and 60 μg/L. The reproductive functions and transgenerational effects were investigated. After 80 days exposure, the percentage of previtellogenic and vitellogenic oocytes in the ovary showed a significant decrease in the 0.06 and 60 μg/L groups. The mRNA levels of salmon-type gonadotropin releasing hormone, the follicle-stimulating hormone FSHβ, and the luteinizing hormone LHβ in the brain; the cytochrome P450 aromatase gene CYP19A and the estrogen receptor α (ERα) in the ovary; and ERα and vitellogenin VTG1 and 2 in the liver all exhibited significant down-regulation in the 0.06 and 60 μg/L groups, but did not significantly change in the 6 μg/L group compared to the control, which was quite consistent with development of the oocytes. A significant elevation of PHE accumulation in the brain in the 0.06 and 60 μg/L groups gave a reasonable explanation for the nonmonotonic dose-response and also elucidated the action pathway via the brain-pituitary-gonadal axis. The reduction of the time to hatch and the increased cardiac rhythm of embryos were in accord with the PHE accumulative levels in the eggs. The results demonstrated that exposure to PHE at both low and high concentrations can inhibit ovary development. In addition, PHE can be maternally transferred to embryos and influence the health and sustainability of the next generation.

Influence of triphenyltin exposure on the hypothalamus-pituitary-gonad axis in male Sebastiscus marmoratus.

Both triphenyltin (TPT) and tributyltin (TBT) have been used as ingredients of antifouling biocides. However, far fewer studies addressing the reproductive toxicity of TPT on fishes are available than for TBT. The present study was conducted to investigate the effects of TPT at environmentally relevant concentrations on testicular development in male rockfish Sebastiscus marmoratus and to gain insight into its mechanism of action. After exposure for 48 days, the gonadosomatic index had decreased, and there was a reduced number of mature sperm and an abundance of the late stages of spermatocysts in the testes. Although the testosterone levels in the testes were elevated and the 17β-estradiol levels were decreased, spermatogenesis was suppressed. The activity of γ-glutamyl transpeptidase (which is used as a Sertoli cell marker) was decreased after TPT exposure, and serious interstitial fibrosis was observed in the interlobular septa of the testes exposed to TPT. The increased expression of cGnRH-II (chicken-II type gonadotropin-releasing hormone) and sGnRH (salmon-type GnRH), and the decreased expression of LHβ (luteinizing hormone) in the fish brains were detected. The expression of FSHβ (follicle-stimulating hormone) was decreased at day 21, while was increased slightly at day 48. The changes of cGnRH-II, sGnRH, FSHβ and LHβ mRNA levels might have mainly resulted from the alteration of the sex steroids via feedback mechanisms. The decrease of the FSHβ mRNA might have been one of the reasons causing the dysfunction of Sertoli cells, which play a critical role during spermatogenesis. The results suggested that TPT could perturb the function of hypothalamus-pituitary-gonad axis, and inhibiting the spermatogenesis.

Chronic exposure to paclobutrazol causes hepatic steatosis in male rockfish Sebastiscus marmoratus and the mechanism involved

Paclobutrazol (PBZ) is a triazole-containing fungicide which is widely used in agriculture. Acute toxicity can follow its extensive use but it is generally weaker than traditional pesticides such as organochlorine and organophosphorus. However, its adverse effects on aquatic organisms need to be investigated. This study was conducted to investigate the effect of PBZ exposure on the hepatic lipid metabolism of Sebastiscus marmoratus. After PBZ exposure for 50 days, hepatic lipid droplets were enlarged and the hepatic total lipid, triglyceride, total cholesterol and free fatty acid content had increased in a dose dependent manner compared to the control. The mRNA expression of lipid metabolism associated genes such as peroxisome proliferator-activated receptors (PPARs), androgen receptor, acetyl-CoA carboxylase 1, fatty acid synthesis, fatty acid bing protein 4, liver X receptor α (LXRα) and stearoyl-CoA desaturase were up-regulated by PBZ exposure. These results indicated that triazole-containing fungicides might affect the metabolism and health of fish via the multi-signal pathways of nuclear receptors such as PPARs and LXR.

Exposure to paclobutrazol disrupts spermatogenesis in male Sebastiscus marmoratus

Paclobutrazol (PBZ) is triazole-containing fungicides and widely used in agriculture as an efficient plant growth retardant. However, far fewer studies addressing the reproductive toxicity of PBZ on fishes are available. The present study was conducted to investigate the effects of PBZ at environmentally relevant concentrations on testicular development in male rockfish Sebastiscus marmoratus and to gain insight into its mechanism of action. After exposure to 10, 100 and 1000 ng/L PBZ for 50 d, although the gonadosomatic index did not show a significant alteration, there was a reduced number of mature sperm and an abundance of the late stages of spermatocysts in the testes. The activity of γ-glutamyl transpeptidase (which is used as a Sertoli cell marker) was decreased in a dose-dependent manner after PBZ exposure, which might be a result of the reduction in FSHβ expression in the brain. The toxicity induced by accumulation of PBZ in the brain might be primary cause impacting the spermatogenesis via brain-pituitary-gonad pathway.

Transcriptome Analysis of Male and Female Sebastiscus marmoratus

Background The rockfish Sebastiscus marmoratus, which is widely distributed in the East Sea and the South Sea of China, is a sensitive model for the toxic effects and mechanisms of marine contaminants. To gain a global view of the molecular mechanism(s) whereby gene expression may influence sexual dimorphism in S. marmoratus, and to develop a database for further toxicological studies, we performed a large-scale transcriptome study. Methodology/Principal Findings The Illumina DNA sequencing platform was employed to obtain 27,559,578 and 25,821,126 reads from two cDNA libraries generated from adult male and female S. marmoratus, respectively. Transcriptome de novo assembly was carried out with the short reads assembling program–SOAPdenovo. The reads assembled into 78,675 unigenes, of which 38,677 showed homology to existing protein sequences. Clusters of orthologous groups, gene orthology, and the Kyoto Encyclopedia of Genes and Genomes annotations were performed to better understand the functions of these unigenes. There were 1,209 potential sex differentially expressed unigenes, with 1,049 predicted to be differentially expressed in females and 160 in males. Fifteen randomly chosen unigenes were confirmed using real-time PCR as female or male predominantly expressed genes. Conclusions/Significance This is the first report of an annotated transcriptome of S. marmoratus and identification of sex differentially expressed genes. These data will be of interest to researchers using this model. This work also provides an archive for future studies in molecular mechanisms of sexual dimorphism and evolution and can be used in comparative studies of other fish.

Modulation of the DNA repair system and ATR-p53 mediated apoptosis is relevant for tributyltin-induced genotoxic effects in human hepatoma G2 cells

The toxic effects of tributyltin (TBT) have been extensively documented in several types of cells, but the molecular mechanisms related to the genotoxic effects of TBT have still not been fully elucidated. Our study showed that exposure of human hepatoma G2 cells to 1-4 μmol/L TBT for 3 hr caused severe DNA damage in a concentration-dependent manner. Moreover, the expression levels of key DNA damage sensor genes such as the replication factor C, proliferating cell nuclear antigen and poly (ADP-ribose) polymerase-1 were inhabited in a concentration-dependent manner. We further demonstrated that TBT induced cell apoptosis via the p53-mediated pathway, which was most likely activated by the ataxia telangiectasia mutated and rad-3 related (ATR) protein kinase. The results also showed that cytochrome c, caspase-3, caspase-8, caspase-9, and the B-cell lymphoma 2 were involved in this process. Taken together, we demonstrated for the first time that the inhibition of the DNA repair system might be more responsible for TBT-induced genotoxic effects in cells. Then the generated DNA damage induced by TBT initiated ATR-p53-mediated apoptosis.

Laparoscopic temporary bilateral uterine artery occlusion with silicone tubing to prevent hemorrhage during vacuum aspiration of cesarean scar pregnancies

The aim of this study was to determine the feasibility and effects of temporary bilateral uterine artery occlusion with silicone tubing on blood loss during vacuum aspiration of cesarean scar pregnancies (CSP).