Early maternal investment in mice: no evidence for compatible-genes sexual selection despite hybrid vigor.

Confronting a recently mated female with a strange male can induce a pregnancy block ('Bruce effect'). The physiology of this effect is well studied, but its functional significance is still not fully understood. The 'anticipated infanticide hypothesis' suggests that the pregnancy block serves to avoid the cost of embryogenesis and giving birth to offspring that are likely to be killed by a new territory holder. Some 'compatible-genes sexual selection hypotheses' suggest that the likelihood of a pregnancy block is also dependent on the female's perception of the stud's and the stimulus male's genetic quality. We used two inbred strains of mice (C57BL/6 and BALB/c) to test all possible combinations of female strain, stud strain, and stimulus strain under experimental conditions (N(total) = 241 mated females). As predicted from previous studies, we found increased rates of pregnancy blocks if stud and stimulus strains differed, and we found evidence for hybrid vigour in offspring of between-strain mating. Despite the observed heterosis, pregnancies of within-strain matings were not more likely to be blocked than pregnancies of between-strain matings. A power analysis revealed that if we missed an existing effect (type-II error), the effect must be very small. If a female gave birth, the number and weight of newborns were not significantly influenced by the stimulus males. In conclusion, we found no support for the 'compatible-genes sexual selection hypotheses'.

Sexual dysfunctions among young men: prevalence and associated factors.

PURPOSE: The purposes of this study are to measure the prevalence of premature ejaculation (PE) and erectile dysfunction (ED) among a population of Swiss young men and to assess which factors are associated with these sexual dysfunctions in this age-group. METHODS: For each condition (PE and ED), we performed separate analyses comparing young men suffering from the condition with those who were not. Groups were compared for substance use (tobacco, alcohol, cannabis, other illegal drugs, and medication without a prescription), self-reported body mass index, sexual orientation, physical activity, professional activity, sexual experience (sexual life length and age at first intercourse), depression status, mental health, and physical health in a bivariate analysis. We then used a log-linear analysis to consider all significant variables simultaneously. RESULTS: Prevalence rates for PE and ED were 11% and 30%, respectively. Poor mental health was the only variable to have a direct association with both conditions after controlling for potential confounders. In addition, PE was directly associated with tobacco, illegal drugs, professional activity, and physical activity, whereas ED was directly linked with medication without a prescription, length of sexual life, and physical health. CONCLUSIONS: In Switzerland, one-third of young men suffer from at least one sexual dysfunction. Multiple health-compromising factors are associated with these dysfunctions. These should act as red flags for health professionals to encourage them to take any opportunity to talk about sexuality with their young male patients.

Genetic causes of transitions from sexual reproduction to asexuality in plants and animals.

The persistence of sexual reproduction in the face of competition from asexual invaders is more likely if asexual lineages are produced infrequently or have low fitness. The generation rate and success of new asexual lineages will be influenced by the proximate mechanisms underlying transitions to asexuality. As such, characterization of these mechanisms can help explain the distribution of reproductive modes among natural populations. Here, we synthesize the literature addressing proximate causes of transitions from sexual to asexual reproduction in plants and animals. In cyclical and facultatively asexual taxa, individual mutations can cause obligate asexuality. The evolution of asexuality in obligately sexual groups is more complex, requiring the simultaneous acquisition of two traits generally controlled by different genetic factors: unreduced gamete formation and spontaneous development of unfertilized gametes. At least three 'pre-adaptations' could favour transitions to obligate asexuality in obligate sexuals. First, linkage among loci affecting separate key components of asexuality facilitates its spread, with evidence for these linkage blocks in plants. Second, asexuality should evolve more readily in haplodiploids; support for this hypothesis comes from two examples where a single locus causes transitions to asexuality. Third, standing genetic variation for the production of unreduced gametes could facilitate transitions to asexuality, but whether the ability to produce unreduced gametes contributes to the evolution of obligate asexuality remains unclear. We close by reviewing the associations between asexuality, hybridization and polyploidy, and argue that current data suggest that hybridization is more likely to play a causal role in transitions to asexuality than polyploidy.

Do pornographic websites influence boys' sexual behavior?

Purpose: To compare the sexual behavior of adolescent males who do and do not watch pornographic websites. Methods: This study was presented as a school survey. Data were drawn from the 2002 Swiss Multicenter Adolescent Survey on Health (SMASH02) database, a survey including 7,548 adolescents age 16-20. The setting was post-mandatory schools in Switzerland. A total of 2,891 male students who connected to the internet in the last 30 days were enrolled and distributed into two groups: boys who deliberately watched pornographic websites in the last 30 days (n ¼ 942; 33%) and boys who did not (n ¼ 1,949; 67%). Socio-demographic characteristics; frequency of connection to the internet; sexual behavior parameters (having a girlfriend and if yes, for more or less than 6 months; having had sexual intercourse; age at first sexual intercourse; use of a condom at last sexual intercourse; number of sexual partners; having made a partner pregnant). Results: A logistic regression was performed using STATA 9.2. The only significant socio-demographic variable was having a low socioeconomic status (adjusted odds ratio [AOR] 1.66); no difference was found for age and academic track between the two groups. Boys who watch pornographic websites were also significantly more likely to connect frequently to the internet (one day a week: AOR 1.75; several days a week: AOR 2.36; every day: AOR 3.11), to have had sexual intercourse (AOR 2.06), and to have had their first sexual intercourse before age 15 (AOR 1.48). The stability of the relationship with their girlfriend did not appear to have any influence on the search for pornography on the internet. Conclusions: About one third of boys in our sample report having accessed pornographic websites in the last 30 days, a proportion similar to other studies. Watching such websites increases with the frequency of connection to the internet and seems to be correlated with an earlier sexual activity debut among adolescent males. However, having had first sexual intercourse before age 15 is the only sexual risk behavior that seems to be increased when watching pornographic websites among boys. Further studies should address the causality of this correlation and the factors influencing the search for pornography on the web among boys, in order to explore some new ways of prevention about sexual risk behaviors. Sources of Support: The SMASH02 survey was carried out with the financial support of the Swiss Federal Office of Public Health and the participating cantons.

Alpha1-adrenoceptors are required for normal male sexual function.

BACKGROUND AND PURPOSE: Alpha(1)-adrenoceptor antagonists are extensively used in the treatment of hypertension and lower urinary tract symptoms associated with benign prostatic hyperplasia. Among the side effects, ejaculatory dysfunction occurs more frequently with drugs that are relatively selective for alpha(1A)-adrenoceptors compared with other drugs of this class. This suggests that alpha(1A)-adrenoceptors may contribute to ejaculation. However, this has not been studied at the molecular level. EXPERIMENTAL APPROACH: The physiological contribution of each alpha(1)-adrenoceptor subtype was characterized using alpha(1)-adrenoceptor subtype-selective knockout (KO) mice (alpha(1A)-, alpha(1B)- and alpha(1D)-AR KO mice) since the subtype-specific drugs available are only moderately selective. We analysed the role of alpha(1)-adrenoceptors in the blood pressure and vascular response as well as ejaculation by determining these variables in alpha(1)-adrenoceptor subtype-selective KO mice and in mice with all their alpha(1)-adrenoceptor subtypes deleted (alpha(1)-AR triple-KO mice). KEY RESULTS: The pregnancy rate was reduced by 50% in alpha(1A)-adrenoceptor KO mice, and this reduction was dramatically enhanced in alpha(1)-adrenoceptor triple-KO mice. Contractile tension of the vas deferens in response to noradrenaline was markedly decreased in alpha(1A)-adrenoceptor KO mice, and this contraction was completely abolished in alpha(1)-adrenoceptor triple-KO mice. This attenuation of contractility was also observed in the electrically stimulated vas deferens. CONCLUSIONS AND IMPLICATIONS: These results demonstrate that alpha(1)-adrenoceptors, particularly alpha(1A)-adrenoceptors, are required for normal contractility of the vas deferens and consequent sperm ejaculation as well as having a function in fertility.

Differential DNA extraction of challenging simulated sexual assault samples: a Swiss collaborative study.

ABSTRACT: In sexual assault cases, autosomal DNA analysis of gynecological swabs is a challenge, as the presence of a large quantity of female material may prevent the detection of the male DNA. A solution to this problem is differential DNA extraction, but as there are different protocols, it was decided to test their efficiency on simulated casework samples. Four difficult samples were sent to the nine Swiss laboratories active in the forensic genetics. They used their routine protocols to separate the epithelial cell fraction, enriched with the non-sperm DNA, from the sperm fraction. DNA extracts were then sent to the organizing laboratory for analysis. Estimates of male to female DNA ratio without differential DNA extraction ranged from 1:38 to 1:339, depending on the semen used to prepare the samples. After differential DNA extraction, most of the ratios ranged from 1:12 to 9:1, allowing the detection of the male DNA. Compared to direct DNA extraction, cell separation resulted in losses of 94-98% of the male DNA. As expected, more male DNA was generally present in the sperm than in the epithelial cell fraction. However, for about 30% of the samples, the reverse trend was observed. The recovery of male and female DNA was highly variable depending on the laboratories. Experimental design similar to the one used in this study may help for local protocol testing and improvement.

Unwanted sexual experiences among adolescents: shedding light on the gray zone between consensual and non-consensual sex.

This study aimed at exploring adolescents' perceptions of unwanted sexual experiences (USE) in order to set up definitions, categories, and boundaries on the continuum between consensual and non-consensual sex. METHODS: We conducted a qualitative thematic analysis of four focus group discussions gathering a total of 29 male and female adolescents aged 16-20 years. RESULTS: Analysis of participants' discourse revealed three main characteristics that define USE, namely, regret, as most situations discussed were said to be acceptable or not in terms of whether there were regrets after the fact; misperception of sexual intent; and lack of communication between partners. CONCLUSIONS: Our findings revealed that health professionals should be aware of the subtle aspects identifying USE when screening for situations that can have adverse psychological consequences. Where prevention is concerned, it appears important to address these aspects of USE in sex education classes.

Isolating DNA from sexual assault cases: a comparison of standard methods with a nuclease-based approach.

AbstractText BACKGROUND: Profiling sperm DNA present on vaginal swabs taken from rape victims often contributes to identifying and incarcerating rapists. Large amounts of the victim's epithelial cells contaminate the sperm present on swabs, however, and complicate this process. The standard method for obtaining relatively pure sperm DNA from a vaginal swab is to digest the epithelial cells with Proteinase K in order to solubilize the victim's DNA, and to then physically separate the soluble DNA from the intact sperm by pelleting the sperm, removing the victim's fraction, and repeatedly washing the sperm pellet. An alternative approach that does not require washing steps is to digest with Proteinase K, pellet the sperm, remove the victim's fraction, and then digest the residual victim's DNA with a nuclease. METHODS: The nuclease approach has been commercialized in a product, the Erase Sperm Isolation Kit (PTC Labs, Columbia, MO, USA), and five crime laboratories have tested it on semen-spiked female buccal swabs in a direct comparison with their standard methods. Comparisons have also been performed on timed post-coital vaginal swabs and evidence collected from sexual assault cases. RESULTS: For the semen-spiked buccal swabs, Erase outperformed the standard methods in all five laboratories and in most cases was able to provide a clean male profile from buccal swabs spiked with only 1,500 sperm. The vaginal swabs taken after consensual sex and the evidence collected from rape victims showed a similar pattern of Erase providing superior profiles. CONCLUSIONS: In all samples tested, STR profiles of the male DNA fractions obtained with Erase were as good as or better than those obtained using the standard methods.

Molecular analysis and mating behaviour of the Trichophyton mentagrophytes species complex.

Isolates of the Trichophyton mentagrophytes complex vary phenotypically. Whether the closely related zoophilic and anthropophilic anamorphs currently associated with Arthroderma vanbreuseghemii have to be considered as members of the same biological species remains an open question. In order to better delineate species in the T. mentagrophytes complex, we performed a mating analysis of freshly collected isolates from humans and animals with A. benhamiae and A. vanbreuseghemii reference strains, in comparison to internal transcribed spacer (ITS) and 28S rDNA sequencing. Mating experiments as well as ITS and 28S sequencing unambiguously allowed the distinction of A. benhamiae and A. vanbreuseghemii. We have also shown that all the isolates from tinea pedis and tinea unguium identified as T. interdigitale based on ITS sequences mated with A. vanbreuseghemii tester strains, but had lost their ability to give fertile cleistothecia. Therefore, T. interdigitale has to be considered as a humanized species derived from the sexual relative A. vanbreuseghemii.

Sexual behaviour of men that consulted in medical outpatient clinics in Western Switzerland from 2005-2006: risk levels unknown to doctors?

BACKGROUND: To determine male outpatient attenders' sexual behaviours, expectations and experience of talking about their sexuality and sexual health needs with a doctor. METHODS: A survey was conducted among all male patients aged 18-70, recruited from the two main medical outpatient clinics in Lausanne, Switzerland, in 2005-2006. The anonymous self-administered questionnaire included questions on sexual behaviour, HIV/STI information needs, expectations and experiences regarding discussion of sexual matters with a doctor. RESULTS: The response rate was 53.0% (N = 1452). The mean age was 37.7 years. Overall, 13.4% of patients were defined as at STI risk--i.e. having not consistently used condoms with casual partners in the last 6 months, or with a paid partner during the last intercourse--regarding their sexual behaviour in the last year. 90.9% would have liked their physician to ask them questions concerning their sexual life; only 61.4% had ever had such a discussion. The multivariate analysis showed that patients at risk tended to have the following characteristics: recruited from the HIV testing clinic, lived alone, declared no religion, had a low level of education, felt uninformed about HIV/AIDS, were younger, had had concurrent sexual partners in the last 12 months. However they were not more likely to have discussed sexual matters with their doctor than patients not at risk. CONCLUSION: Recording the sexual history and advice on the prevention of the risks of STI should become routine practice for primary health care doctors.

Factors associated with comorbidity patterns in full and partial PTSD: Findings from the PsyCoLaus study.

Subtypes of comorbid conditions and their associated trauma and clinical characteristics in full and partial PTSD were examined. Data from 289 subjects from the general population that met criteria for full or partial PTSD were analyzed. Latent class analyses (LCA) were performed to derive homogeneous patterns of DSM-IV Axis-I disorders and anti-social personality comorbid to PTSD. Logistic regression models were conducted to characterize these classes by trauma-related and clinical features. The LCA revealed three classes: (1) low comorbidity; (2) high comorbidity with primarily substance-related disorders and a higher proportion of males; and (3) more severe PTSD-symptomatology and higher comorbid anxiety disorders and depression, almost entirely represented by females. Exposure to sexual abuse was more likely in the substance-dependent class and contributed strongly to the distinction between classes. Affective disorders tended to precede the onset of PTSD in the substance-dependent class, whereas phobias were more likely to follow PTSD in the depressed-anxious class. Posttrauma onset of alcohol use disorders in the substance dependent class confirmed the self-medication hypothesis. The three classes of comorbidity and their sequence of onset with PTSD suggest different mechanisms involved in their development. Our findings suggest that PTSD-related comorbidity subtypes also apply to individuals with partial PTSD.

Sexual dimorphism in androdioecious Mercurialis annua, a wind-pollinated herb

Gender-dimorphic species often display a degree of sexual dimorphism in terms of life-history traits, yet little is known about dimorphism in androdioecious plants. Here we investigate sexual dimorphism in an androdioecious population of the wind-pollinated herb Mercurialis annua by comparing the resource allocation strategies of males and hermaphrodites grown under different nutrient-availability and competitive regimes. We found that males displayed smaller aboveground vegetative sizes than did hermaphrodites, but neither soil nutrient availability nor competition had a strong independent effect on their relative sizes. Plants adjusted their relative reproductive investment in response to nutrient availability. Specifically, hermaphrodites increased their reproductive allocation when growing in poor soils, whereas males displayed the opposite response. Finally, hermaphrodites were strongly female biased in their sex allocation, and this was more pronounced in nutrient-poor soils. To conclude, sexual dimorphism in androdioecious M. annua shares many features with dioecious and gynodioecious species, particularly wind-pollinated herbs. However, the direction of sex-allocation reaction norms displayed by hermaphrodites of M. annua differs from that documented for several insect-pollinated gynodioecious species, hinting at the importance of either the pollination mode or the sexual system as a context of selection shaping the reproductive strategy of plants with both male and female functions.