Fitness costs and benefits of personality disorder traits

Extreme personality traits in humans often have detrimental life consequences, so they have long been supposed to be diseases. However, many other species display personality variants that are maintained due to their fitness advantages; in this case, they are construed as strategies. To examine the fitness costs and benefits of pathological personality traits in humans, we measured features of the A (socially odd, distrustful), B (incentive-seeking, selfish) and C (fearful, inhibited) clusters with the Personality Diagnostic Questionnaire-4 + (PDQ-4 +) in a sample of 738 outpatients. Fitness relevant parameters like mating success, reproductive output, self preservation, and access to status were assessed with the Life Outcome Questionnaire. No fitness advantages were found for high-A subjects. In contrast, high-B subjects tripled low-B subjects with regard to mating success and had 39% more offspring. Further, high-C subjects outperformed low-C subjects in attaining status and avoiding risks. These findings help explain the commonness of some extreme personality traits in humans, and suggest that they should be seen as evolutionary strategies rather than as diseases.     

The influence of maternal thermal environments on reproductive traits and hatchling traits in a Lacertid lizard,Takydromus septentrionalis

The thermal environment can induce substantial variation in important life-history traits. Experimental manipulation of the thermal environment can help researchers determine the contribution of this factor to phenotypic variation in life-history traits. During the reproductive season, we kept female northern grass lizards, Takydromus septentrionalis (Lacertidae), in three temperature-controlled rooms (25, 28 and 32 °C) to measure the effect of the maternal thermal environment on reproductive traits. Maternal thermal environment remarkably affected reproductive frequency and thereby seasonal reproductive output, but had little effect on reproductive traits per clutch or hatchling traits. Females kept at 32 °C produced more clutches and thus had shorter clutch intervals than females from 28 to 25 °C. Clutch size, clutch mass, relative clutch mass, egg size and hatchling traits did not vary among the three treatments. The eggs produced by the females were incubated at 27 °C and the traits of hatchlings were measured. The result that egg (offspring) size was independent of maternal thermal environments is consistent with the prediction of the optimal egg size (offspring) theory. The eggs produced by low temperature females (28 and 25 °C) took longer time to complete their post-oviposition development than did eggs produced by high temperature females (32 °C). This suggests that the eggs from low temperatures might have been laid when the embryos were at relatively early stages. Therefore, maternal thermal environment prior to oviposition could affect post-oviposition development in T. septentrionalis.     

Normal intellectual development in children born from women with hypothyroxinemia during their pregnancy

Proper maternal thyroid function is known to be essential for neural differentiation and migration in the fetus during the first half of pregnancy. The objectives of this study were to assess the relationship between thyroxin levels, in pregnant women with no thyroid disease and the intellectual development of their offspring in a non-iodine-deficient area, and to know specifically whether or not isolated hypothyroxinemia during pregnancy was associated with a lower intelligence in the offspring.Previously we had publicated values TSH, FT4, free T3 (FT3), anti-thyroid peroxidase antibodies (TPO Abs) and urinary iodine concentration (UIC) in 1322 pregnant women in our hospital area. Now we presented results of intelligence quotient in children born from these pregnancies. We assessed 455 children at one year of age using Brunet-Lezine scale. Of these, 289 children were evaluated again at 6–8 years of age using the WISC-IV. From the total group of children recruited, we established as control subgroup, children born of rigorously normal pregnancies (women with UIC > 150 μg/L, FT4 > 10th percentile and TPO-Ab negative in both trimesters). The remaining children were divided into two subgroups: those born to mothers with FT4 below the 10th percentile and the rest. No correlation was found between FT4 maternal levels, in either of trimesters studied, and the intellectual scores of offspring. No differences were found in intellectual scores comparing children born to mothers with hypothyroxinemia and those whose mothers were euthyroxinemic in both trimesters, or with the control subgroup.As conclusions we did not find any association between the levels of maternal FT4 during pregnancy and the subsequent intellectual development the offspring from these pregnancies. We attribute this result to the fact that all the pregnant women included had normal thyroid function.     

The evolutionary fitness of personality traits in a small-scale subsistence society

The maintenance of personality variation remains an unexplained puzzle in evolutionary biology. Despite evidence among non-humans that personality variation affects fitness, few data exist to assess the personality–fitness relationship in humans. Among Tsimane forager–horticulturalists (n = 632), we test whether personality traits (assessed using a 43-item Big Five Inventory administered orally in native language) predict fertility, offspring survivorship, age of first reproduction, and other fitness correlates (extramarital affairs, conflicts, social visitation, food production, and several health measures). Among men, several personality factors associate with higher fertility, more time spent producing food and social visitation. Among women, the relationship between personality and fitness varies across regions of Tsimane territory. The only case of an intermediate personality level associated with highest fitness was found for Industriousness in men. We find that personality factors positively associated with fitness do not associate with greater health costs, although greater Extraversion and Openness may lead to more conflicts among men. Factor heritability ranges from 60% for Prosociality and Extraversion to 8% for Neuroticism. We interpret our results in light of evolutionary models that explain maintenance of personality variation, including incomplete directional selection, mutation–selection balance, condition-dependent reaction norms and fluctuating selection based on sex or spatial variability in selection pressures.     

BDNF serum concentrations in first psychotic episode drug-naïve schizophrenic patients: Associations with personality and BDNF Val66Met polymorphism

AimsTo investigate the relationship among brain derived neurotrophic factor (BDNF) serum concentrations, BDNF Val66Met polymorphism and personality profile in drug-naïve schizophrenic patients with first-episode psychosis (FEP) and healthy participants.Main methodsThis cross-sectional study included fifty FEP patients and fifty healthy participants who served as controls. To study their personality profile the standardized Greek version of the Alternative Five-Factor Zuckerman–Kuhlman Personality Questionnaire (ZKPQ) was administered. Serum BDNF levels were measured and genotyping of BDNF Val66Met polymorphism was performed in patients and healthy subjects.Key findingsFEP patients presented lower BDNF serum concentrations (P = 0.002) and higher scores in ZKPQ Neuroticism (P = 0.001) and Aggression–Hostility (P = 0.002) scales while lower scores in the ZKPQ Sociability scale (P < 0.001) than healthy participants. Multivariate analysis revealed that the odds of being assessed with FEP were 0.4 times lower in those with higher BDNF values (P < 0.001) and 1.8 times greater in those with higher Neuroticism scores (P < 0.001). There were no significant differences with respect to the Val66Met polymorphism between patients and healthy participants.SignificanceReduced BDNF serum concentrations along with higher Neuroticism scores might be associated with FEP. A complex interplay between BDNF serum concentrations, personality traits, BDNF Val66Met polymorphism, and psychotic symptomatology has been arisen but further investigation is needed to better clarify the observed associations.     

Prenatal exposure to medicines and the risk of childhood brain tumor

Background: Childhood brain tumors are associated with high mortality and morbidity but little is known about its causes. About half of women use medicines when pregnant and some of the medicines commonly used might be carcinogenic. Objective: The aim with this population-based case–control study was to analyze associations between specific groups of medicines taken during pregnancy and the risk of brain tumor in the offspring. Methods: All children, up to 15 years of age, born in Sweden between 1975 and 1984 were eligible for the study. Cases (N = 512) were children diagnosed with brain tumor and controls (N = 525) were randomly selected from the Medical Birth Register. Exposure data on medicines was extracted blindly from antenatal medical records and grouped according to Anatomical Therapeutic Chemical (ATC) code. Information on maternal reproductive history was received from the Medical Birth Register. We used logistic regression to estimate associations between fetal exposure to medicines and childhood brain tumor. Results: No significant changes in risk were noted after exposure to iron supplementation, antiemetics, analgesics, antibiotics or any other main ATC group. A tendency of protective effect was seen for prenatal exposure to folic acid (adjusted OR 0.6, 95% CI 0.3–1.1). Ten children with a diagnosis of brain tumor had been exposed to β-blocking agents in fetal life as compared to two children without brain tumor (adjusted OR 5.3, 95% CI 1.2–24.8). Conclusions: In this case–control study, an increased risk of brain tumor was seen in children exposed to β-blocking agents during fetal life. However, due to the low number of exposed the interpretation of this finding should be made with caution.     

Parental effects on fertilization and hatching success and development of Atlantic halibut (Hippoglossus hippoglossus L.) embryos and larvae

The parental effects on fertilization and early life history traits were studied in Atlantic halibut, Hippoglossus hippoglossus L. Sperm from 12 different males were used to fertilize eggs of two females in separate crosses. The fertilization success were generally high, above 80% of developing embryos at 16-cell stage in 20 of 24 crosses with an average of 85.9 ± 17.6% and 87.2 ± 16.5% for female A and female B, respectively. Corresponding hatching success was 74.8 ± 17.7% and 41.6 ± 20.1%, respectively. The relationship between fertilization success and hatching success was positive. The parental influence on hatching was dominated by a strong and significant (p < 0.001) maternal effect; however, the paternal effect was also significant (p < 0.001). Furthermore, there was no relationship between fertilization success, hatching success and larvae viability as a high number of larvae developed locked jaws (i.e., were not functional). There was a significant (p < 0.01) difference in yield of functional larvae of female A (43%) and female B (56%), and also between crosses sired by different males. The standard length of offspring of female A (12.4 ± 0.5 mm) and B (12.6 ± 0.6 mm) were significantly (p < 0.001) different, and also significantly influenced by both the female (p < 0.001) and the male (p < 0.001). The present paper provides strong indications that not only the female, but also the male parent influences quantitative features of early development of their offspring.     

Mixing aggression intensity is associated with age at first service and floor type during gestation,with implications for sow reproductive performance

Aggression resulting from mixing to establish a dominance hierarchy is a major welfare concern for group-housed sows. The associated stress can negatively impact aspects of reproductive performance. Objectives of this study were to investigate associations between 1) age at first service (AFS) and mixing aggression intensity in first parity sows, 2) mixing aggression intensity and reproductive performance within and between parity one and parity two, and 3) mixing aggression intensity, floor type during gestation and reproductive performance. Gilts (n = 160, hereafter referred to as sows) were mixed into stable groups of eight unfamiliar individuals approximately 4 days after artificial insemination, housed on fully slatted concrete (CON; n = 80) floor uncovered or covered with rubber slat mats (RUB; n = 80), and followed through two parities. Skin lesions (SLMIX; a proxy for the intensity of mixing aggression), were scored post mixing in each parity according to severity (0 = no lesions to 5 = severe lesions) on five body regions (ear, neck, hindquarter, rump, and belly) on the left and right sides, and at the tail/anogenital region. Total SLMIX score was calculated for each sow. Data on reproductive performance traits were acquired retrospectively from farm records for both parities. Two analyses were performed: 1) data from each parity were analysed separately and 2) SLMIX score in parity one was used to predict reproductive performance in parity two. Lower AFS was associated with a lower SLMIX score in parity one (P = 0.031). There was no association between SLMIX score and reproductive performance in parity one, while sows with higher SLMIX score in parity two had a higher proportion of piglets dead during lactation (P = 0.027) and a longer cycle length (P = 0.003) in parity two. Sows with higher SLMIX scores in parity one had more non-productive days (P < 0.001) in parity two. Concrete sows had a higher SLMIX score than RUB sows in parity one (P = 0.015), but not in parity two. In addition, CON sows had a higher proportion of piglets born dead (P = 0.013) compared with RUB sows in parity two. Mixing aggression has a negative influence on reproductive performance within parities, and it may also have a long-term negative carry-over effect on reproductive performance in subsequent parities. Serving gilts at younger ages could help to minimize the intensity of aggression at mixing, while housing on rubber flooring has beneficial implications for their reproductive performance.     

Agro-morphological characterization and assessment of variability,heritability, genetic advance and divergence in bacterial blight resistant rice genotypes

Genetic based knowledge of different growth traits including morphological, physiological and developmental plays fundamental role in the improvement of rice. Genetic divergence allows superior recombinants which are essential in any crop development project. Forty-one rice genotypes including bacterial blight (BB) resistant and susceptible checks were assessed for 13 morphological traits. Among the genotypes, almost all the traits exhibited highly significant variation. The higher extent of genotypic (GCV) as well as phenotypic coefficients of variation (PCV) were noticed for number of tillers hill^− 1, total number of spikelets panicle^− 1, number of filled grains panicle^− 1, and yield hill^− 1. High heritability together with high genetic advance was observed for total number of spikelets panicle^− 1, number of filled grains panicle^− 1, and yield hill^− 1 indicating dominant role of additive gene action in the expression of these traits. Number of filled grains panicle^− 1 exhibited positive correlation with most of the traits. Yield hill^− 1 showed a good number of highly significant positive correlations with number of filled grain panicle^− 1, total number of spikelets panicle^− 1, 1000 grain weight hill^− 1, number of panicle hill^− 1, and panicle length. The UPGMA dendrogram divided all the genotypes in to six major clusters. The PCA showed 13 morphological traits generated about 71% of total variation among all the genotypes under this study. On the basis of 13 morphological traits, genotypes such as IRBB2, IRBB4, IRBB13, IRBB21, and MR263 could be hybridized with genotypes MR84, MR159, MRQ50, MRQ74, PH9 and IR8 in order to develop suitable BB resistant rice genotypes.     

Plant functional traits and community assembly along interacting gradients of productivity and fragmentation

Quantifying the association of plant functional traits to environmental gradients is a promising approach for understanding and projecting community responses to land use and climatic changes. Although habitat fragmentation and climate are expected to affect plant communities interactively, there is a lack of empirical studies addressing trait associations to fragmentation in different climatic regimes.In this study, we analyse data on the key functional traits: specific leaf area (SLA), plant height, seed mass and seed number. First, we assess the evidence for the community assembly mechanisms habitat filtering and competition at different spatial scales, using several null-models and a comprehensive set of community-level trait convergence and divergence indices. Second, we analyse the association of community-mean traits with patch area and connectivity along a south–north productivity gradient.We found clear evidence for trait convergence due to habitat filtering. In contrast, the evidence for trait divergence due to competition fundamentally depended on the null-model used. When the null-model controlled for habitat filtering, there was only evidence for trait divergence at the smallest sampling scale (0.25 m × 0.25 m). All traits varied significantly along the S–N productivity gradient. While plant height and SLA were consistently associated with fragmentation, the association of seed mass and seed number with fragmentation changed along the S–N gradient.Our findings indicate trait convergence due to drought stress in the arid sites and due to higher productivity in the mesic sites. The association of plant traits to fragmentation is likely driven by increased colonization ability in small and/or isolated patches (plant height, seed number) or increased persistence ability in isolated patches (seed mass).Our study provides the first empirical test of trait associations with fragmentation along a productivity gradient. We conclude that it is crucial to study the interactive effects of different ecological drivers on plant functional traits.     

Breast cancer susceptibility loci in association with age at menarche,age at natural menopause and the reproductive lifespan

Background: Genome-wide association studies have identified single nucleotide polymorphisms (SNPs) associated with breast cancer risk. Some of these loci have unknown functional significance and may mediate the effects of hormonal exposures on breast cancer risk. We examined relationships between breast cancer susceptibility variants and menstrual/reproductive factors using data from two population-based studies. Methods: The first analysis was based on a sample of 1328 women age 20–74 who participated as controls in a case–control study of breast cancer conducted in three U.S. states. We evaluated the associations between age at menarche, age at natural menopause and the reproductive lifespan with 13 previously identified breast cancer variants. Associations were also examined with a genetic score created as the sum of at-risk alleles across the 13 variants. For validation, significant results were evaluated in a second dataset comprised 1353 women age 43–86 recruited as part of a cohort study in Wisconsin. Results: Neither the genetic score nor any of the 13 variants considered individually were associated with age at menarche or reproductive lifespan. Two SNPs were associated with age at natural menopause; every increase in the minor allele (A) of rs17468277 (CASP8) was associated with a 1.12 year decrease in menopause age (p = 0.02). The minor allele (G) of rs10941679 (5p12) was associated with a 1.01 year increase in age at natural menopause (p = 0.01). The results were not replicated in the validation cohort (B = −0.61, p = 0.14 and B = −0.01, p = .0.98, respectively). Conclusions: The evaluated variants and reproductive experiences may work through separate pathways to influence breast cancer risk.     

Embryo production in superstimulated llamas pre-treated to inhibit follicular growth

Llamas are monotocous and the length of their gestation period varies between 342 and 350 days. Thus the average number of offspring any female can produce throughout her reproductive life is very limited to spread a desired genome. The multiple ovulation and embryo transfer (MOET) technique allows an alternative to this limitation and reduces the generation interval. The objective of this study was to evaluate embryo recovery in superstimulated llamas which had previously been hormone-treated to inhibit follicular growth. A total of 50 female llamas were monitored daily via rectal palpation and ultrasound and divided according to their ovarian follicular growth into four phases. The females in each phase were then randomly divided into two groups: A (n = 20) received a single dose of 1 mg of estradiol benzoate (EB) on the first day of the treatment + 100 mg of progesterone (P4) i.m. for 5 days with 5 animals per phase and B (n = 20) received 1 mg EB at onset + 150 mg P4 i.m. for a period of 5 days with 5 animals per phase. Group C (n = 10) or control did not receive any prior hormonal treatment and the females were in follicular phase I. All groups were monitored daily and, in the presence of ovarian follicles smaller than the dominant size at the end of treatment, all were superstimulated with 1000 IU eCG. For plasma progesterone concentration recording, daily blood samples were collected from days ?1 to 5 in the treated females in Group A and B. No significant differences were observed regarding the inhibition of follicle growth and in the plasma progesterone concentrations between Group A and B. The ovarian response to superstimulation was 56.2%, 71.4% and 90%, with the average number of dominant follicles produced per female being 4.4 ± 0.9; 4.8 ± 0.7 and 4.6 ± 0.6 in Groups A, B and C, respectively. The embryo recovery rate was 77.7%; 90% and 66.7% and the average number of embryos recovered per female was 2.9 ± 0.9; 2.6 ± 0.9 and 2.4 ± 0.8 for Groups A, B and C, respectively. In Groups A and B, the static follicular phase (III) seemed to be ideal for initiating the assisted reproductive technique of MOET. Although prior administration of P4 + EB seems to have no effect on the number of females that responded to the superstimulation treatments, the number of embryos recovered showed a tendency to be higher when ovarian follicle growth inhibition was performed beforehand.     

Everyday discrimination and diurnal cortisol during adolescence

PurposeTo examine the associations of the frequency and type of everyday discrimination with diurnal cortisol and whether those associations depend upon adolescents' ethnicity and gender.MethodsAdolescents (N = 292, M_age = 16. 39 years, SD = 0.74; 58% female) reported the frequency of perceived everyday discrimination and whether they attributed that discrimination to race, gender, age, or height and weight. Five saliva samples were collected per day across 3 days and assayed for cortisol.ResultsHigher frequency of everyday discrimination was associated with greater total daily cortisol output (area under the curve; AUC), lower wake and bedtime levels of cortisol, and less of a decline in cortisol across the day. These associations generally did not depend upon ethnicity or gender and attributions for the discrimination were not as consequential as the actual frequency of any type of unfair treatment.ConclusionEveryday discrimination, regardless of its type, may contribute to heightened HPA activity among adolescents of different ethnic backgrounds and genders.     

Cancer risks in children with congenital malformations in the nervous and circulatory system—A population based cohort study

AimWe estimated the age and organ-specific cancer risk for children with a congenital malformation (CM) in the nervous or in the circulatory system.MethodsWe identified 1,709,456 live born singletons in Denmark between 1 January 1977 and 31 December 2007 and excluded children with chromosomal birth defects. Information on CMs was obtained from the Danish National Hospital Register. Information on cancer occurrence was obtained from the Danish Cancer Registry. We applied Cox proportional hazards regression model to estimate hazard ratios (HR) for cancer. Children entered into the CM cohort on the day of birth regardless of when the CM was diagnosed or on the day of CM diagnosis in an alternative analysis.ResultsOverall, 4484 (0.26%) and 24,643 (1.44%) children were diagnosed with a CM in the nervous and in the circulatory system, respectively. Compared with children without any CM, children with a CM in the nervous system had a 5.97 fold (95%CI [confidence interval]: 4.66–7.64) higher risk of cancer, including cancer in the central nervous system (HR = 18.84, 95%CI: 12.67–28.01), in the mesothelial and soft tissue (HR = 15.64, 95%CI: 7.99–30.60), in the skin (HR = 4.91, 95%CI: 2.19–11.0). The associations were stronger early in life. Children with a CM in the circulatory system had a 2.64 fold (95%CI: 2.21–3.16) higher risk of cancer, including cancer in the lymphatic and haematopoietic tissues (HR = 3.22, 95%CI: 2.43–4.27) and cancer in the CNS (HR = 2.40, 95%CI: 1.43–4.02). Some of these associations were weaker in the alternative analysis. Children with subtypes of CM in the two systems showed a higher cancer risk.ConclusionsChildren who were diagnosed with a CM in the nervous system had a substantially higher cancer risk especially early in life. Children diagnosed with a CM in the circulatory system had a moderately higher cancer risk.     

Reproductive factors and breast cancer risk among BRCA1 or BRCA2 mutation carriers: Results from ten studies

Although reproductive factors are among the most well-established risk factors for breast cancer in the general population, it is still a matter for debate whether these factors act as risk modifiers among BRCA1 or BRCA2 mutation carriers. This meta-analysis is the first to be performed to determine the relationship between reproductive factors and breast cancer risk among BRCA1 and BRCA2 mutation carriers. We searched the PubMed database up to February 2013. A total of ten studies met the inclusion criteria. The results showed that the reproductive factors may be associated with breast cancer risk only among BRCA1 mutation carriers. No association was found between parity and breast cancer risk. Compared with women at the youngest age in the first-birth category, women in the oldest age category were at a 38% lower risk of breast cancer (RR = 0.62, 95%CI = 0.45–0.85). Breastfeeding for at least 1 or 2 years was associated with a 37% reduction in breast cancer risk (RR = 0.63, 95%CI = 0.46–0.86). Women at the oldest age in the menarche category were at a 34% lower risk of breast cancer (RR = 0.66, 95%CI = 0.53–0.81) than women in the youngest age category. However, none of the reproductive factors were associated with breast cancer risk among BRCA2 mutation carriers. In conclusion, late age at first birth, breastfeeding, and late age at menarche protect against breast cancer in BRCA1 mutation carriers only. Further studies are needed to explore the mechanisms.     

Effects of maternal l-citrulline supplementation on renal function and blood pressure in offspring exposed to maternal caloric restriction: The impact of nitric oxide pathway

Maternal undernutrition can cause reduced nephron number and glomerular hypertrophy, consequently leading to adult kidney disease. We intended to elucidate whether NO deficiency evolves to kidney disease vulnerability in offspring from mothers with caloric restriction diets and whether maternal l-citrulline (l-Cit) supplementation can prevent this. Using a rat model with 50% caloric restriction, four groups of 3-month-old male offspring were sacrificed to determine their renal outcome: control, caloric restriction (CR), control treated with 0.25% l-citrulline solution during the whole period of pregnancy and lactation (Cit), and CR treated in the same way (CR + Cit group). The CR group had low nephron numbers, increased glomerular diameter, and an increased plasma creatinine level compared with the control group. Maternal l-Cit supplementation prevented these effects. The CR + Cit and Cit groups developed hypertension beginning at 4 and 8 weeks of age, respectively. Plasma asymmetric and symmetric dimethylarginine (ADMA and SDMA) levels were increased, but l-arginine/ADMA ratios (AAR) were decreased in the CR group vs the control group. This was prevented by maternal l-Cit supplementation. Renal cortical neuronal NOS-α (nNOSα) protein abundance was significantly decreased in the Cit and CR + Cit groups. Collectively, reduced nephron number, reduced renal nNOSα expression, increased ADMA, and decreased AAR contribute to the developmental programming of adult kidney disease and hypertension. Although maternal l-Cit supplementation prevents caloric restriction-induced low nephron number and renal dysfunction, it also induces hypertension.     

The risk of cancer in the offspring and parental length of life

BackgroundWe investigated if cancer onset in offspring is related to having short-lived parents for different cancer types and to see if there was a difference in smoking- and non-smoking related cancers.MethodsOur study included 524,391 individuals born in Norway 1940–1950. All children were followed up for cancer from the age of 20 until they were between 59 and 69 years. Parental longevity was examined by grouping parental age of death into parents dying before 75 years of age and parents dying at 75 years of age or older.ResultsAn increased risk of 1.14 (95%CI = 1.10–1.19) among male offspring and 1.08 (95%CI = 1.04–1.12) among female offspring was observed for total cancer when both parents died before the age of 75 compared to offspring with two long-lived parents. The highest increase was found for cancer in the lungs and trachea for both male (HR = 1.67, 95%CI = 1.50–1.86) and female offspring (HR = 1.53, 95%CI = 1.33–1.76). For other smoking-related cancers, the risk was lower. No increased risk was observed for non-smoking-related cancers.ConclusionOffspring of long-lived parents have lower risk of developing cancer compared with offspring of short-lived parents. Intergenerational transmission of risk factors from parents to offspring may play an important role, especially for tobacco-related cancers. However, genetic factors cannot be ruled out, since consistent evidence has implicated genetic factors in smoking behaviour.     

Male mice ultrasonic vocalizations enhance female sexual approach and hypothalamic kisspeptin neuron activity

Vocal communication in animals is important for ensuring reproductive success. Male mice emit song-like “ultrasonic vocalizations (USVs)” when they encounter female mice, and females show approach to the USVs. However, it is unclear whether USVs of male mice trigger female behavioral and endocrine responses in reproduction. In this study, we first investigated the relationship between the number of deliveries in breeding pairs for 4 months and USVs syllables emitted from those paired males during 3 min of sexual encounter with unfamiliar female mice. There was a positive correlation between these two indices, which suggests that breeding pairs in which males could emit USVs more frequently had more offspring. Further, we examined the effect of USVs of male mice on female sexual behavior. Female mice showed more approach behavior towards vocalizing males than devocalized males. Finally, to determine whether USVs of male mice could activate the neural system governing reproductive function in female mice, the activation of kisspeptin neurons, key neurons to drive gonadotropin-releasing hormone neurons in the hypothalamus, was examined using dual-label immunocytochemistry with cAMP response element-binding protein phosphorylation (pCREB). In the arcuate nucleus (Arc), the number of kisspeptin neurons expressing pCREB significantly increased after exposure to USVs of male as compared with noise exposure group. In conclusion, our results suggest that USVs of male mice promote fertility in female mice by activating both their approaching behavior and central kisspeptin neurons.     

Semen production in two rabbit lines divergently selected for 63-d body weight

Thirty-one bucks from two lines divergently selected for 63-d body weight (low, L and high, H) were solicited every week (twice at a 15 min interval) during 18 weeks resulting in 482 ejaculates. While differing markedly on adult body weight (L: 4650 g versus H: 5925 g), both lines had the same testis weight. Libido did not differ between the lines. The proportion of ejaculates suitable for insemination was markedly higher in the L line (66.5% versus 44.2%). Mass motility and the volume of the ejaculates were higher in the L line while the sperm concentration was higher in the H line. Overall, the total number of spermatozoa per ejaculate was similar in both lines but the efficient number of spermatozoa per ejaculate, a synthetic criterion taking into account the ability of the ejaculate for insemination was higher in the L line (229 versus 170 × 10⁶). The L line had higher values of average path velocity, linearity and curvilinear velocity but a lower value of beat cross frequency. In the L line, both ejaculates had the same concentration, while in the H line, the first ejaculate was more concentrated than the second one. Some male reproductive traits are therefore genetically related to body weight.     

Social and biological determinants of reproductive success in Swedish males and females born 1915–1929

Studying biological and social determinants of mortality and fertility provides insight into selective pressures in a population and the possibility of trade-offs between short- and long-term reproductive success. Limited data is available from post-demographic transition populations. We studied determinants of reproductive success using multi-generational data from a large, population-based cohort of 13,666 individuals born in Sweden between 1915 and 1929. We studied the effects of birthweight for gestational age, preterm birth, birth multiplicity, birth order, mother's age, mother's marital status and family socioeconomic position (SEP) upon reproductive success, measured as total number of children and grandchildren. We further tested the hypothesis that number of grandchildren would peak at intermediate family size, as predicted by some life history explanations for fertility limitation. Reproductive success was associated with both social and biological characteristics at birth. In both sexes, a higher birthweight for gestational age, a term birth and a younger mother were independently associated with a greater number of descendants. A married mother and higher family SEP were also associated with a greater number of descendants in males (but not in females), while higher birth order was associated with a greater number of descendents in females (but not males). These effects were mediated by sex-specific effects upon the probability of marriage. Marriage was also affected by other early life characteristics including birthweight, indicating how ‘biological’ characteristics may operate via social pathways. Number of grandchildren increased with increasing number of children in both sexes, providing no evidence for a trade-off between quantity of offspring and their subsequent reproductive ‘quality’.