Disrupted sex differentiation and feminization of man and domestic animals

Androgen Receptor Gene Variants in New Cases of Equine Androgen Insensitivity Syndrome

In the domestic horse; failure of normal masculinization and virilization due to deficiency of androgenic action leads to a specific disorder of sexual development known as equine androgen insensitivity syndrome (AIS). Affected individuals appear to demonstrate an incoherency between their genetic sex and sexual phenotype; i.e., XY-sex chromosome constitution and female phenotypic appearance. AIS is well documented in humans. Here we report the finding of two novel genetic variants for the AR-gene identified in a Tennessee Walking Horse and a Thoroughbred horse mare; each in individual clinical cases of horse AIS syndrome.

Pesticide-induced decrease in rat testicular steroidogenesis is differentially prevented by lipoate and tocopherol

We have previously demonstrated that the sub-chronic administration of low doses of Toc or α-Toc, glyphosate and zineb to rats (i.p. 1/250 LD50, three times a week for 5 weeks) provoked severe oxidative stress (OS) in testicles. These effects were also reflected in plasma. Lipoic acid (LA) and α-tocopherol are considered as antioxidants due to their ability to neutralize reactive oxygenated species (ROS) and reset endogenous antioxidant levels. To investigate the possible protective effect on reproductive function, LA and Toc (i.p. 25, 50 and 100mg/kg) were administered simultaneously with the pesticide mixture (PM) for 5 weeks. Both drugs prevented OS and the damage to proteins and lipids caused by PM in a dose-dependent manner. The PM-induced increase levels of prostaglandins E2 and F2α was completely restored by LA but not by Toc. Similarly, only LA was able to restore the inhibition of testosterone production, the decrease of 3β- and 17β-hydroxysteroid dehydrogenases activities, and the elevation of gonatropins (FSH and LH) levels produced by PM. Furthermore, LA was more efficient than Toc in normalizing the histological alterations produced by PM administration, suggesting that pesticides act though other mechanisms that generate oxidative stress. In our experimental model LA displayed a higher protective role against pesticide-induced damage than that observed by Toc administration. Our results suggest that LA administration is a promising therapeutic strategy for coping with disorders suspected to be caused by OS generators - such as pesticides - in male reproductive system.

The male mammary gland: a target for the xenoestrogen bisphenol A

Males of some strains of mice retain their mammary epithelium even in the absence of nipples. Here, we have characterized the mammary gland in male CD-1 mice both in whole mounts and histological sections. We also examined the effects of bisphenol A (BPA), an estrogen mimic that alters development of the female mouse mammary gland. BPA was administered at a range of environmentally relevant doses (0.25-250μg/kg/day) to pregnant and lactating mice and then the mammary glands of male offspring were examined at several periods in adulthood. We observed age- and dose-specific effects on mammary gland morphology, indicating that perinatal BPA exposures alter the male mammary gland in adulthood. These results may provide insight into gynecomastia, the most common male breast disease in humans, where proliferation of the mammary epithelium leads to breast enlargement.

Environmentally realistic exposure to the herbicide atrazine alters some sexually selected traits in male guppies

Male mating signals, including ornaments and courtship displays, and other sexually selected traits, like male-male aggression, are largely controlled by sex hormones. Environmental pollutants, notably endocrine disrupting compounds, can interfere with the proper functioning of hormones, thereby impacting the expression of hormonally regulated traits. Atrazine, one of the most widely used herbicides, can alter sex hormone levels in exposed animals. I tested the effects of environmentally relevant atrazine exposures on mating signals and behaviors in male guppies, a sexually dimorphic freshwater fish. Prolonged atrazine exposure reduced the expression of two honest signals: the area of orange spots (ornaments) and the number of courtship displays performed. Atrazine exposure also reduced aggression towards competing males in the context of mate competition. In the wild, exposure levels vary among individuals because of differential distribution of the pollutants across habitats; hence, differently impacted males often compete for the same mates. Disrupted mating signals can reduce reproductive success as females avoid mating with perceptibly suboptimal males. Less aggressive males are at a competitive disadvantage and lose access to females. This study highlights the effects of atrazine on ecologically relevant mating signals and behaviors in exposed wildlife. Altered reproductive traits have important implications for population dynamics, evolutionary patterns, and conservation of wildlife species.

GTG mutation in the start codon of the androgen receptor gene in a family of horses with 64,XY disorder of sex development

Genetic sex in mammals is determined by the sex chromosomal composition of the zygote. The X and Y chromosomes are responsible for numerous factors that must work in close concert for the proper development of a healthy sexual phenotype. The role of androgens in case of XY chromosomal constitution is crucial for normal male sex differentiation. The intracellular androgenic action is mediated by the androgen receptor (AR), and its impaired function leads to a myriad of syndromes with severe clinical consequences, most notably androgen insensitivity syndrome and prostate cancer. In this paper, we investigated the possibility that an alteration of the equine AR gene explains a recently described familial XY, SRY + disorder of sex development. We uncovered a transition in the first nucleotide of the AR start codon (c.1A>G). To our knowledge, this represents the first causative AR mutation described in domestic animals. It is also a rarely observed mutation in eukaryotes and is unique among the >750 entries of the human androgen receptor mutation database. In addition, we found another quiet missense mutation in exon 1 (c.322C>T). Transcription of AR was confirmed by RT-PCR amplification of several exons. Translation of the full-length AR protein from the initiating GTG start codon was confirmed by Western blot using N- and C-terminal-specific antibodies. Two smaller peptides (25 and 14 amino acids long) were identified from the middle of exon 1 and across exons 5 and 6 by mass spectrometry. Based upon our experimental data and the supporting literature, it appears that the AR is expressed as a full-length protein and in a functional form, and the observed phenotype is the result of reduced AR protein expression levels.

17α-Ethinyl estradiol affects anxiety and shoaling behavior in adult male zebra fish (Danio rerio)

Ethinyl estradiol is a potent endocrine disrupting compound in fish and ubiquitously present in the aquatic environment. In this study, we exposed adult zebra fish (Danio rerio) males to 0, 5 or 25 ng Ethinyl estradiol/L for 14 days and analyzed the effects on non-reproductive behavior. Effects of treatment of the exposed males was shown by vitellogenin induction, while brain aromatase (CYP 19B) activity was not significantly altered. Both concentrations of Ethinyl estradiol significantly altered the behavior in the Novel tank test, where anxiety is determined as the tendency to stay at the bottom when introduced into an unfamiliar environment. The effects were, however, opposite for the two concentrations. Fish that were exposed to 5 ng/L had longer latency before upswim, fewer transitions to the upper half and shorter total time spent in the upper half compared with control fish, while 25 ng Ethinyl estradiol treatment resulted in shorter latency and more and longer visits to the upper half. The swimming activity of 25, but not 5 ng-exposed fish were slightly but significantly reduced, and these fish tended to spend a lot of time at the surface. We also studied the shoaling behavior as the tendency to leave a shoal of littermates trapped behind a Plexiglas barrier at one end of the test tank. The fish treated with Ethinyl estradiol had significantly longer latency before leaving shoal mates and left the shoal fewer times. Further, the fish exposed to 5 ng/L also spent significantly less time away from shoal than control fish. Fertilization frequency was higher in males exposed to 5 ng/L Ethinyl estradiol when compared with control males, while no spawning was observed after treatment with 25 ng/L. The testes from both treatment groups contained a normal distribution of spermatogenesis stages, and no abnormality in testis morphology could be observed. In conclusion, we have observed effects on two behaviors not related to reproduction in zebra fish males after treatment with Ethinyl estradiol, adding to the ecological consequences of contamination of aquatic environments with estrogenic substances.

Quantitative determination of bisphenol A from human saliva using bulk derivatization and trap-and-elute liquid chromatography coupled to electrospray ionization mass spectrometry

Endocrine disruptors cause adverse health effects as a result of their ability to shift the hormonal balance that is essential to the body. Bisphenol A (BPA) is an endocrine disruptor that has garnered much attention because of its presence in many consumer materials, which generates a significant risk for exposure. A method is presented for rapid detection of oral exposure to BPA directly from human saliva. Saliva was chosen because it serves as a noninvasive sampling route to detect BPA exposure; however, it is one of many complex biological matrices that have traditionally posed problems in quantitative analysis. Such analyses usually require extensive sample preparation to reduce interferences contributed by the sample matrix. Three validated methods are presented here that feature a streamlined sample-preparation strategy (bulk derivatization) prior to accurate and sensitive analysis by trap-and-elute liquid chromatography coupled to electrospray ionization mass spectrometry. Validated methods include standard addition calibration with variable injection volumes and multiple injection loading, as well as with incorporation of an internal standard. Reported limits of detection reached as low as 49.0 pg/ml (2.9 pg loaded on-column; equivalent to parts per trillion in saliva) among the presented methods with good accuracy and precision throughout. A proof-of-concept study is demonstrated to show that the final validated method has potential application to specific studies for trace-level BPA detection from real samples.

Veterinary cytogenetics: past and perspective

Cytogenetics was conceived in the late 1800s and nurtured through the early 1900s by discoveries pointing to the chromosomal basis of inheritance. The relevance of chromosomes to human health and disease was realized more than half a century later when improvements in techniques facilitated unequivocal chromosome delineation. Veterinary cytogenetics has benefited from the information generated in human cytogenetics which, in turn, owes its theoretical and technical advancement to data gathered from plants, insects and laboratory mammals. The scope of this science has moved from the structure and number of chromosomes to molecular cytogenetics for use in research or for diagnostic and prognostic purposes including comparative genomic hybridization arrays, single nucleotide polymorphism array-based karyotyping and automated systems for counting the results of standard FISH preparations. Even though the counterparts to a variety of human diseases and disorders are seen in domestic animals, clinical applications of veterinary cytogenetics will be less well exploited mainly because of the cost-driven nature of demand on diagnosis and treatment which often out-weigh emotional and sentimental attachments. An area where the potential of veterinary cytogenetics will be fully exploited is reproduction since an inherited aberration that impacts on reproductive efficiency can compromise the success achieved over the years in animal breeding. It is gratifying to note that such aberrations can now be tracked and tackled using sophisticated cytogenetic tools already commercially available for RNA expression analysis, chromatin immunoprecipitation, or comparative genomic hybridization using custom-made microarray platforms that allow the construction of microarrays that match veterinary cytogenetic needs, be it for research or for clinical applications. Judging from the technical refinements already accomplished in veterinary cytogenetics since the 1960s, it is clear that the importance of the achievements to date are bound to be matched or out-weighed by what awaits to be accomplished in the not-too-far future.