Endocrine Disruption throughout the Hypothalamus-Pituitary-Gonadal-Liver (HPGL) Axis in Marine Medaka (Oryzias melastigma) Chronically Exposed to the Antifouling and Chemopreventive Agent, 3,3'-Diindolylmethane (DIM).

Despite being proposed as a promising antifouling and chemopreventive agent, the environmental risks of 3,3'-diindolylmethane (DIM) are scarcely investigated. Therefore, this study used adult marine medaka (Oryzias melastigma) as a model organism to examine the toxicological effects and underlying mechanism of DIM throughout the hypothalamus-pituitary-gonadal-liver (HPGL) axis following 28 days of exposure to low DIM concentrations (0 and 8.46 µg/L). The results showed that altered gene transcription in the hypothalamus, pituitary, and gonads contributed to the great imbalance in hormone homeostasis. The lowered estradiol (E2)/testosterone (T) and E2/11-keto-testosterone (11-KT) ratios in female plasma resulted in decreased synthesis and levels of vitellogenin (VTG) and choriogenin in the liver and plasma, and vice versa in males. Subsequently, VTG and choriogenin deficiency blocked the reproductive function of the ovary as indicated by decreased fecundity and offspring viability, whereas in male medaka, DIM mainly targeted the liver and induced severe vacuolization. Proteomic profiling of plasma revealed that the sex-specific susceptibility to DIM could be attributed to the increased detoxification and oxidative defense in males. Overall, this study identified the endocrine disruption and reproductive impairment potency of DIM and first elucidated its mechanisms of action in medaka. The differential responses to DIM (estrogenic activities in the male but antiestrogenic activities in the female) provided sensitive biomarkers characteristic of each sex. Considering the chemical stability and potent endocrine disturbance at low concentration, the application of DIM either as an antifouling or chemopreventive agent should be approached with caution in marine environments.

Water column monitoring of the biological effects of produced water from the Ekofisk offshore oil installation from 2006 to 2009.

The Norwegian water column monitoring program investigates the biological effects of offshore oil and gas activities in Norwegian waters. In three separate surveys in 2006, 2008, and 2009, bioaccumulation and biomarker responses were measured in mussels (Mytilus edulis) and Atlantic cod (Gadus morhua) held in cages at known distances from the produced water (PW) discharge at the Ekofisk oil field. Identical monitoring studies performed in all three years have allowed the biological effects and bioaccumulation data to be compared, and in addition, enabled the potential environmental benefits of a PW treatment system (CTour), implemented in 2008, to be evaluated. The results of the 2009 survey showed that caged animals were exposed to low levels of PW components, with highest tissue concentrations in mussels located closest to the PW discharge. Mussels located approximately 1-2 km away demonstrated only background concentrations of target compounds. Concentrations of polycyclic aromatic hydrocarbons (PAH) and alkyl phenol (AP) metabolites in the bile of caged cod were elevated at stations 200-250 m from the discharge. There was also a signal of exposure relative to discharge for the biomarkers CYP1A in fish and micronuclei in mussels. All other fish and mussel biomarkers showed no significant exposure effects in 2009. The mussel bioaccumulation data in 2009 indicated a lower exposure to the PW effluent than seen previously in 2008 and 2006, resulting in an associated general improvement in the health of the caged mussels. This was due to the reduction in overall discharge of PW components (measured as oil in water) into the area in 2009 compared to previous years as a result of the improved PW treatment system.

Effect of selection for increased body weight and increased plasma yolk precursor on developmental stability in Japanese quail.

Developmental stability of several Japanese quail lines was measured by bilateral asymmetry. Lines included in the study were as follows: a randombred control (R1), sublines of R1 selected for increased (HW line) and decreased (LW line) 4-wk BW, and sublines of R1 selected for increased (HP line) or decreased (LP line) total plasma phosphorus (TPP; a measure of yolk precursor in the blood) at the beginning of lay. In sublines of the HW line, the males were selected for increased 4-wk BW and the females for increased (HW-HP line) or decreased (HW-LP line) TPP. The HW, LW, HP, and LP lines were in their 41st generation of selection and the HW-HP and HW-LP lines in their 31st generation of selection. The number of birds in each line and sex subgroup was 30. The adult breeders (28 to 32 wk of age) were weighed and killed, and bilateral measurements were made of shank length, width (laterally at the dew claw), and depth (perpendicular to the dew claw), face length, and pectoralis major and p. minor weights. Data on asymmetry was expressed for the right side minus the left side as signed and absolute differences. In order to correct for the correlation between trait size and asymmetry, relative asymmetry (RA) was obtained by dividing the absolute differences between sides by the average value of both sides and multiplying by 100. All lines differed in BW at 4 wk of age with the ranking HW > HW-LP > HW-HP > LP > R1 > HP > LW. Line rankings of adult breeders were similar, except the HP and LP lines did not differ from the R1 line and the order of ranking of the HW-HP and HW-LP lines was opposite that at 4 wk of age. Line differences in signed and absolute differences were significant for most bilateral traits. However, after adjustment for trait size, line differences in RA were less frequent. In general, there were few significant differences in RA for the R1 line versus the selected lines, even though inbreeding of the R1 line (19%) was less than half that of the selected lines (44 to 57%), suggesting that homozygosity did not influence developmental stability. Selection for increased or decreased BW had little influence on RA. Developmental stability tended to be higher in the lines (LP and HW-LP) selected for decreased TPP. The data indicated that bilateral asymmetry was not a good measure of developmental stability in the current study.

Divergent selection for body weight and yolk precursor in Coturnix coturnix japonica. 12. Heterosis in reciprocal crosses between divergently selected lines.

A selection experiment was started using Japanese quail to study the genetics of BW and plasma yolk precursor (measured by total plasma phosphorus; TPP). Lines were divergently selected for 4-wk BW (HW and LW) or plasma TPP (HP and LP). Sublines of HW were developed by continuing to select the males for increased 4-wk BW while selecting the females for increased (HW-HP line) or decreased (HW-LP line) TPP. The purpose of the present study was to determine the inheritance of traits associated with growth and reproduction in reciprocal crosses between the divergently selected lines and sublines. Reciprocal crosses were made between the HW and LW, HP and LP, and HW-HP and HW-LP lines. Traits measured included BW at various ages, age at sexual maturity, egg production, ovarian follicular development, egg weight, TPP, wet and dry liver weights, and occurrence of smooth muscle tumors in the ligaments of the oviduct. The HW line differed from the LW line in all traits measured except TPP and weight of smooth muscle tumors. No offspring were obtained from the HW x LW matings (male listed first). In the LW x HW cross, heterosis was negative for BW through sexual maturity and age at sexual maturity. Positive heterosis was observed for egg production, egg weight, and occurrence of smooth muscle tumors. Differences between the HP and LP lines were observed in the selected trait (TPP) and some correlated traits (BW at some ages, age at sexual maturity in females, egg production, and number and total weight of ovarian follicles). Positive heterosis in the HP and LP crosses was observed for BW, egg production, egg weight, and number of ovarian follicles whereas negative heterosis was observed for TPP and age at sexual maturity in females. The HW-HP and HW-LP lines differed in the selected traits and some correlated traits (egg weight and weights of the liver and smooth muscle tumors). Positive heterosis in the crosses was observed for BW, egg production, and liver weights whereas negative heterosis was evident for age at sexual maturity and TPP.

Riboflavin-binding protein. Concentration and fractional saturation in chicken eggs as a function of dietary riboflavin.

The concentration of riboflavin and riboflavin-binding protein were determined in the plasma, egg yolk and albumen from hens fed a riboflavin-deficient diet (1.2 mg/kg) supplemented with 0, 1, 2, 3, 10 and 40 mg of riboflavin/kg. We observed that the deposition of riboflavin in egg yolk and albumen is dependent on dietary riboflavin and reaches half-maximal values at about 2 mg of supplemental riboflavin/kg. The maximal amount of riboflavin deposited in the yolk is limited stoichiometrically by the amount of riboflavin-binding protein, whereas the maximum amount of riboflavin deposited in albumen is limited by other factors before saturation occurs. The amount of riboflavin-binding protein in yolk and albumen is independent of dietary riboflavin. If there is a specific oocyte receptor for riboflavin-binding protein, it cannot distinguish between the apo and holo forms of the protein. Riboflavin-binding protein is about six times more concentrated in yolk than in plasma.