Inbreeding Coefficient and Distance in MHC Genes of Parents as Predictors of Reproductive Success in Domestic Cat

Simple Summary

Inbreeding and low diversity in MHC (major histocompatibility complex) genes can have a significant impact on the survival and quality of offspring in mammals. At the same time, a decrease in genetic diversity can be disastrous for animals at individual and species level. For felines, studies of the effects of inbreeding and low variety in MHC genes are conducted on populations with a low number of animals, where there is a high probability of a shortage of available partners, and, accordingly, their choice. The use of model species, especially domestic cats, allows us to identify the main consequences of inbreeding and the lack of a choice of partners for future offspring. The survival of offspring in a domestic cat is primarily affected by the degree of similarity/difference in the genes of the parents’ MHC. Parents with the maximum distance in MHC genes have a larger proportion of surviving kittens, and this effect is most pronounced immediately after birth. In parents with the minimum distance in MHC genes, a significant percentage of kittens are either stillborn or die on the first day after birth. However, inbreeding and the similarity of parents in MHC genes in domestic cats did not affect the body mass of kittens.

Abstract

Inbreeding and low diversity in MHC genes are considered to have a negative effect on reproductive success in animals. This study presents an analysis of the number and body mass of offspring in domestic cat, depending on the inbreeding coefficient and the degree of similarity in MHC genes of class I and II in parents. Inbred partners had a lower number of live kittens at birth than outbred ones. At the same time, the inbreeding coefficient did not affect the litter size and the number of offspring who survived until the period of transition to solid food. The most significant predictor for the number of surviving offspring was the degree of parental similarity in MHC genes: the parents with the maximum distance in MHC genes had more survived kittens. Moreover, this effect was most pronounced immediately after birth. A significant percentage of kittens from parents with a minimum distance in MHC genes were either stillborn or died on the first day after birth. By the age of transition to solid food, this effect is no longer so pronounced. Furthermore, neither the inbreeding coefficient nor the distance in MHC genes of parents had any effect on the body mass of kittens.

TNFα is responsible for the canonical offspring number-size trade-off

There is a canonical life-history trade-off between quantity and quality of offspring, but molecular determinants for this are unknown. Here, we show that knockout of tumor necrosis factor (TNF-KO) in mice switched a relation between the number and size of developing embryos from expectedly negative to unexpectedly positive. Depletion of TNFα imbalanced humoral and trophic maintenance of embryo growth during gestation with respect to the litter size. The levels of embryotrophic GM-CSF cytokine and placental efficiency attained positive correlations with the number and size of embryos in TNF-KO females. Thus, TNFα oversees mother’s resource allocations to balance embryo growth with the number of offspring. Consequently, this suggests an intricate link between the number-size trade-off and immunity given a pivotal role of TNFα in immune homeostasis.

[The role of the vomeronasal system in the formation of the human sexual behaviour]

This review deals with the structure and function of the vomeronasal system and evaluation of its influence on the sexual sphere of humans and animals. Special attention is given to the role of pheromones in the regulation of the sexual behaviour. The data concerning the function of the vomeronasal organ following surgical interventions in the nasal cavity are discussed.

Modulation of embryonic development due to mating with immunised males

The modification of pre- and postnatal development conferred by immunogenic stimulation of mothers provides a population-level adaptation mechanism for non-genetic transfer of maternal experiences to progeny. However little is known about the transmission of paternal immune experiences to offspring. Here, we show that immune priming of males 3–9 days before mating affects the growth and humoral environment of developing embryos of outbred (ICR) and inbred (C57BL and BALB/c) mice. Antigenic stimulation of fathers caused a significant increase in embryonic bodyweight as measured on Day 16 of pregnancy and altered other gestation parameters, such as feto–placental ratio. Pregnant females mated with immunised males were also characterised by changes in humoral conditions as shown by measurements of blood and amniotic progesterone, testosterone and granulocyte–macrophage colony-stimulating factor (GM-CSF) cytokine concentrations. These results emphasise the role of paternal effects of immune priming on the in utero environment and fetal growth.

Antigen-induced changes in odor attractiveness and reproductive output in male mice

Modulation of social signals by antigen-induced immunoenhancement is a significant component of behavioral and reproductive adaptations of a host population to parasitic pressure. To investigate this concept, we studied odor attractiveness and reproductive output of ICR male mice treated with keyhole limpet hemocyanin (KLH) as an antigenic stimulus. We collected urine samples for olfactory preference tests (control vs. KLH administration) on different days following treatment. We found that the differences in odor attractiveness between control and immunized males, which were observed on the 3rd day, disappeared soon afterwards. Odor attractiveness of male mice positively correlated with their immunoresponsiveness, which was assessed by the sum of anti-KLH IgG1 and anti-KLH IgG2a titers. According to the hypothesis of terminal investment, antigen-treated males had higher reproductive output in comparison with control males and produced more progeny as a result.

Attractiveness of illness-associated odorant cues in female rats is modulated by ovarian hormones, but not associated with pro-inflammatory cytokine levels

Odorant cues released by rodents play a key role in mate preference/selection. The goal of the following series of studies was to determine the impact of acute illness, and the potential role of the inflammatory response, on the release of illness-associated odor cues from female rats. Adult female Sprague-Dawley rats were injected with lipopolysaccharide (LPS, 100 μg/kg) and their soiled bedding was used as a stimulus to naïve male odor recipients. While odored bedding from sick males elicited a robust avoidance response evidenced by decreased sniffing, avoidance and burying behavior, odored bedding from sick females elicited only a reduction in sniffing, indicating a reduction in odor attractiveness. Odor cues from ovariectomized, but not sham-operated females decreased sniffing behavior and increased avoidance in male odor recipients. Acute estradiol benzoate (EB, 20 μg/kg) replacement into ovariectomized females restored the investigatory response of male recipients toward odor cues, while LPS administration into ovariectomized oil or EB treated females had little impact on odor attractiveness. Measurement of cytokines in both brain (the paraventricular nucleus of the hypothalamus) and blood from female odor donors indicated increased expression of TNF-α, IL-1β, and IL-6 following LPS, which was not affected by EB treatment. These findings illustrate a critical sexual dimorphism by demonstrating that acute illness reduces the attractiveness of female odor, whereas odor cues from sick males are highly aversive. Moreover, the attractiveness of female odor appears to be associated with circulating ovarian hormone levels, but not central or peripheral inflammatory cytokines.

The human brain is a detector of chemosensorily transmitted HLA-class I-similarity in same- and opposite-sex relations

Studies on subjective body odour ratings suggest that humans exhibit preferences for human leucocyte antigen (HLA)-dissimilar persons. However, with regard to the extreme polymorphism of the HLA gene loci, the behavioural impact of the proposed HLA-related attracting signals seems to be minimal. Furthermore, the role of HLA-related chemosignals in same- and opposite-sex relations in humans has not been specified so far. Here, we investigate subjective preferences and brain evoked responses to body odours in males and females as a function of HLA similarity between odour donor and smeller. We show that pre-attentive processing of body odours of HLA-similar donors is faster and that late evaluative processing of these chemosignals activates more neuronal resources than the processing of body odours of HLA-dissimilar donors. In same-sex smelling conditions, HLA-associated brain responses show a different local distribution in male (frontal) and female subjects (parietal). The electrophysiological results are supported by significant correlations between the odour ratings and the amplitudes of the brain potentials. We conclude that odours of HLA-similar persons function as important social warning signals in inter- and intrasexual human relations. Such HLA-related chemosignals may contribute to female and male mate choice as well as to male competitive behaviour.

Social correlates of stress in adult males of the great gerbil, Rhombomys opimus, in years of high and low population densities

The great gerbil, Rhombomys opimus, is the most social species in the Gerbillinae. The social structure consists of family groups that occupy isolated systems of burrows consisting of one breeding male, from one to seven females, and juveniles. During a year of peak density and one of density decline, we studied the influence of group size, group composition, local density, and distance to the nearest groups on fecal corticosterone and testosterone concentrations in breeding males. We also examined the relationship of hormone concentrations to the survival of males during the summer drought between the spring and the fall. We found that males differed in concentrations of steroid hormones. Concentrations of testosterone were lower whereas those of corticosterone tended to be higher in a year of high population densities compared with higher testosterone and lower corticosterone in a year with a lower density. This finding suggests that stress may be greater in higher densities because of increased social contact. Stepwise regression analysis revealed a positive and significant influence of the number of adult females in a family group on concentrations of fecal corticosterone and testosterone in adult males. Concentrations of corticosterone were also significantly higher in males that disappeared from family groups between the spring and the fall compared with males still alive in family groups in the fall. There was no change in concentrations of testosterone. These results suggest that social interactions within large family groups may be an important source of stress for adult males.