Direct action of endocrine disrupting chemicals on human sperm

Synthetic endocrine disrupting chemicals (EDCs), omnipresent in food, household, and personal care products, have been implicated in adverse trends in human reproduction, including infertility and increasing demand for assisted reproduction. Here, we study the action of 96 ubiquitous EDCs on human sperm. We show that structurally diverse EDCs activate the sperm‐specific CatSper channel and, thereby, evoke an intracellular Ca²⁺ increase, a motility response, and acrosomal exocytosis. Moreover, EDCs desensitize sperm for physiological CatSper ligands and cooperate in low‐dose mixtures to elevate Ca²⁺ levels in sperm. We conclude that EDCs interfere with various sperm functions and, thereby, might impair human fertilization.     

Analysis of the Role of Interleukin 6 Receptor Haplotypes in the Regulation of Circulating Levels of Inflammatory Biomarkers and Risk of Coronary Heart Disease

Variants at the interleukin 6 receptor (IL6R) gene regulate inflammation and are associated with risk of coronary heart disease (CHD). The aim of the present study was to investigate the effects of IL6R haplotypes on circulating levels of inflammatory biomarkers and risk of CHD. We performed a discovery analysis in SHEEP, a myocardial infarction (MI) case control study (n = 2,774) and replicated our results in two large, independent European populations, PROCARDIS, a CHD case control study (n = 7,998), and IMPROVE (n = 3,711) a prospective cardiovascular cohort study. Two major haplotype blocks (rs12083537A/G and rs4075015A/T—block 1; and rs8192282G/A, rs4553185T/C, rs8192284A/C, rs4240872T/C and rs7514452T/C—block 2) were identified in the IL6R gene. IL6R haplotype associations with C-reactive protein (CRP), fibrinogen, IL6, soluble IL6R (sIL6R), IL6, IL8 and TNF-α in SHEEP, CRP and fibrinogen in PROCARDIS and CRP in IMPROVE as well as association with risk of MI and CHD, were analyzed by THESIAS. Haplotypes in block 1 were associated neither with circulating inflammatory biomarkers nor with the MI/CHD risk. Haplotypes in block 2 were associated with circulating levels of CRP, in all three study populations, with fibrinogen in SHEEP and PROCARDIS, with IL8 and sIL6Rin SHEEP and with a modest, non significant, increase (7%) in MI/CHD risk in the three populations studied. Our results indicate that IL6R haplotypes regulate the circulating levels of inflammatory biomarkers. Lack of association with the risk of CHD may be explained by the combined effect of SNPs with opposite effect on the CHD risk, the sample size as well as by structural changes affecting sIL6R stability in the circulation.     

Eggshell Bacterial Load Is Related to Antimicrobial Properties of Feathers Lining Barn Swallow Nests

The use of feathers to line bird’s nests has traditionally been interpreted as having a thermoregulatory function. Feather-degrading bacteria growing on feathers lining nests may have antimicrobial properties, which may provide an additional benefit to lining nests with feathers. We test the hypothesis that the production of antimicrobial substances by feather bacteria affects the microbiological environment of the nest, and therefore the bacterial density on eggshells and, indirectly, hatching success. These effects would be expected to differ between nests lined with pigmented and white feathers, because bacteria grow differently on feathers of different colors. We experimentally manipulated the composition of pigmented and unpigmented feathers in nests of the barn swallow (Hirundo rustica) and studied the antimicrobial properties against the keratin-degrading bacterium Bacillus licheniformis of bacteria isolated from feathers of each color. Analyzed feathers were collected at the end of the incubation period, and antimicrobial activity was defined as the proportion of bacteria from the feathers that produce antibacterial substances effective against B. licheniformis. Our experimental manipulation affected antimicrobial activity, which was higher in nests with only white feathers at the beginning of incubation. Moreover, white feathers showed higher antimicrobial activity than black ones. Interestingly, antimicrobial activity in feathers of one of the colors correlated negatively with bacterial density on feather of the opposite color. Finally, antimicrobial activity of white feathers was negatively related to eggshell bacterial load. These results suggest that antimicrobial properties of feathers in general and of white feathers in particular affect the bacterial environment in nests. This environment in turn affects the bacterial load on eggshells, which may affect hatching success.     

Exclusion by interference competition? The relationship between red and arctic foxes

The distribution of many predators may be limited by interactions with larger predator species. The arctic fox in mainland Europe is endangered, while the red fox is increasing its range in the north. It has been suggested that the southern distribution limit of the arctic fox is determined by interspecific competition with the red fox. This has been criticised, on the basis that the species co-exist on a regional scale. However, if the larger red fox is superior and interspecific competition important, the arctic fox should avoid close contact, especially during the breeding season. Consequently, the distribution of breeding dens for the two species would be segregated on a much smaller spatial and temporal scale, in areas where they are sympatric. We tested this hypothesis by analysing den use of reproducing arctic and red foxes over 9 years in Sweden. High quality dens were inhabited by reproducing arctic foxes more often when no red foxes bred in the vicinity. Furthermore, in two out of three cases when arctic foxes did reproduce near red foxes, juveniles were killed by red foxes. We also found that breeding arctic foxes occupied dens at higher altitudes than red foxes did. In a large-scale field experiment, red foxes were removed, but the results were not conclusive. However, we conclude that on the scale of individual territories, arctic foxes avoid areas with red foxes. Through interspecific interference competition, the red fox might thus be excluding the arctic fox from breeding in low altitude habitat, which is most important in years when food abundance is limited and competition is most fierce. With high altitude refuges being less suitable, even small-scale behavioural effects could scale up to significant effects at the population level.     

Developmental Instability and Sexual Selection in Stag Beetles from Chernobyl and a Control Area

Radioactivity may have both phenotypic and genetic effects through its disruption of physiological processes and mutations. I studied the size and asymmetry of secondary sexual and ordinary morphological characters of stag beetles ( Lucanus cervus ) in two areas in the Ukraine: near Chernobyl, where levels of radiation are high, and in a control area with low background radiation. Developmental instability of morphological characters was estimated from the degree of fluctuating asymmetry using the restricted maximum likelihood parameter estimation (REML) method to partition measurement error from asymmetry. The degree of asymmetry estimated from unsigned differences in size of right and left secondary sexual character was similar to estimates based on the REML method. Beetles from the contaminated area had a significantly elevated level of fluctuating asymmetry in the secondary sexual character compared with animals from the control area. Male stag beetles found with a female had significantly lower asymmetry than males found alone. While mated males did not differ in asymmetry between areas, unmated males from Chernobyl were much more asymmetric than unmated males from the control area. These findings provide evidence for radiation disrupting developmental homeostasis, and thereby affecting the mating status of free-living beetles.     

The influence of early protein-calorie malnutrition on neuronal and glial protein synthesis

The effect of pre- and postnatal undernutrition, produced according to the method of Chow and Lee (3), on the rate of protein synthesis in the brains of rats 11, 21, 34 and 90 days of age was studied by measuring the incorporation ofl-[¹⁴C]valine in vivo andl-[³H]lysine in vitro. Both in vivo and in vitro experiments were performed with high concentration of the precursor to decrease the effects of pool variations and protein degradation. Particular interest was given to the effects of this form of early protein-calorie malnutrition (PCM) on neuronal and glial cells which were isolated from the brains by gradient centrifugation. Brain protein synthesis measured in vivo which showed a peak at 21 days in both animal series, was depressed by PCM at 11 days but stimulated at 34 days of animal age. Small effect was observed in the 90-day-old animals. A similar response as in whole brain was seen for neuronal cells, while glial cells showed a different reaction. Studies of in vitro protein synthesis did not reveal appreciable effects of undernutrition in whole brain. Both neuronal and glial cells showed a moderate but not statistically significant elevation of protein synthesis in animals subjected to early PCM.     

Activation of rat liver microsomal glutathione S-transferase by hydrogen peroxide: role for protein-dimer formation.

The mechanism of oxygen radical-dependent activation of hepatic microsomal glutathione S-transferase by hydrogen peroxide was studied. Glutathione S-transferase activity in liver microsomes was increased 1.5-fold by incubation with 0.75 mM hydrogen peroxide at 37 degrees C for 10 min, and the increase in activity was reversed by incubation with dithiothreitol. Purified glutathione S-transferase was also activated by hydrogen peroxide after incubation at room temperature, and the increase in the activity was also reversed by dithiothreitol. Immunoblotting with anti-microsomal glutathione S-transferase antibodies after sodium dodecyl sulfate-polyacrylamide gel electrophoresis of hydrogen peroxide-treated microsomes or purified glutathione S-transferase revealed the presence of a glutathione S-transferase dimer. These results indicate that the hydrogen peroxide-dependent activation of the microsomal glutathione S-transferase is associated with the formation of a protein dimer.     

Prostasomes from four different species are able to produce extracellular adenosine triphosphate (ATP)

Background

Prostasomes are extracellular vesicles. Intracellularly they are enclosed by another larger vesicle, a so called “storage vesicle” equivalent to a multivesicular body of late endosomal origin. Prostasomes in their extracellular context are thought to play a crucial role in fertilization.

Methods

Prostasomes were purified according to a well worked-out schedule from seminal plasmas obtained from human, canine, equine and bovine species. The various prostasomes were subjected to SDS-PAGE separation and protein banding patterns were compared. To gain knowledge of the prostasomal protein systems pertaining to prostasomes of four different species proteins were analyzed using a proteomic approach. An in vitro assay was employed to demonstrate ATP formation by prostasomes of different species.

Results

The SDS-PAGE banding pattern of prostasomes from the four species revealed a richly faceted picture with most protein bands within the molecular weight range of 10–150 kDa. Some protein bands seemed to be concordant among species although differently expressed and the number of protein bands of dog prostasomes seemed to be distinctly fewer. Special emphasis was put on proteins involved in energy metabolic turnover. Prostasomes from all four species were able to form extracellular adenosine triphosphate (ATP). ATP formation was balanced by ATPase activity linked to the four types of prostasomes.

Conclusion

These potencies of a possession of functional ATP-forming enzymes by different prostasome types should be regarded against the knowledge of ATP having a profound effect on cell responses and now explicitly on the success of the sperm cell to fertilize the ovum.

General significance

This study unravels energy metabolic relationships of prostasomes from four different species.     

Removal of virus from boar semen spiked with porcine circovirus type 2

The virus porcine circovirus type 2 (PCV2) is associated with different disease entities, including reproductive failure. The objective of this study was to investigate the use of a semen processing technique for the elimination of infectious PCV2 in semen. PCV2 was chosen as a model virus because of its small size, high resistance to inactivation and as a known risk factor for boar semen contamination. Aliquots of ejaculates were spiked with PCV2 and processed by a double processing technique, consisting of Single Layer Centrifugation on Androcoll?-P followed by a "swim-up" procedure. Samples were collected from the resulting fractions during the selection process and analyzed for the presence of infectious PCV2. Virus titres were determined by performing a 50% tissue culture infective dose assay (TCID(50)) by end point dilution and with the use of an indirect peroxidise monolayer assay technique. With an initial infectious virus titre of 3.25-3.82 (TCID(50))/50μL the two-step sperm selection method eliminated 2.92±0.23 logs of infectious PCV2, corresponding to more than 99% reduction. Sperm quality was not affected by the selection procedure.