Male Odors Research Articles

Immunization of male BALB/c and C57BL/6 mice similar modulates chemical signals detected in both chromatographic and behavioral tests

The odor plays a key role in communication between animals and the choice of a mate. The odor of urine of males becomes less attractive to mature females after infection or activation of the immune system. The development of the immune response in the early stages is related with the production of both pro-inflammatory and anti-inflammatory cytokines. To investigate the chemical basis of the observed differences and examine the influence of female interactions with the odor of antigen-treated males, we immunized males of inbred BALB/c (Th1) and C57BL/6 (Th2) mice with hemocyanin (KLH). For females of both tested strains, the attraction of the odor of male urine collected 3 days after immunization was lower compared with the odor of control males. Herewith, BALB/c females sniffed the urine of immunized males less frequently, and C57BL/6 females demonstrated a shorter duration of grooming in olfactory tests with urine of immunized males. The altered response of females to the odor of male urine collected on day 3 after KLH injection matched with antigen-induced modulation of relative levels of volatile organic compounds (VOCs) detected in urine samples by gas chromatography and mass spectroscopy (GC-MS). In males of both strains, after KLH injection, an increase in the content of nonanal, benzothiazole, as well as 2-sec-butyl-4,5-dihydrothiazole, and [1,4,5]-oxadithiepane was shown. At the same time, no compounds were found, the content of which changes in different directions in the urine of males after immunization, depending on the strain of the animal.

The Context Matters: Women's Experiences of Their Partner's Odor in Intimate and Sexual Encounters.

Research shows that male body odor plays an important role in women's mate choice and that olfactory abilities are associated with women's sexual functioning. What remains unclear is what types of partner's odor actually shape women's experience during intimate activities. This study therefore explored women's experience associated with the partner's various odors and investigated how they affect women's intimate and sexual encounters. We performed semi-structured individual interviews with 20 single women and 20 women in a long-term relationship. Thematic analysis revealed four key natural odor types of the partner: body odor, sweat, genital odor, and semen odor. Further, we have identified three main types of fragrance odor (cologne, shower gel, and laundry agents) and investigated their perception in both intimate (hugging, kissing, cuddling, lying side by side) and sexual (intercourse, oral sex, ejaculation) contexts. Both partner's natural odor and fragrance affected women's emotional state (ranging from pleasant to unpleasant) and behavioral response (ranging from approach to avoidance of partner). Women's odor perception was frequently context-dependent, so that even mostly negatively perceived odors (e.g., semen, genital odor) were often accepted as part of sexual encounter. Finally, women's perception was negatively modified by partner's specific sweat (after workday, workout, or when the partner is ill) during intimate encounters. Our results highlight the complexity and interindividual variability of partner's odor perception.

Effect of dietary phospholipid on the behavior in C57BL/6J mice

Nowadays phospholipids are widely used as hepatoprotective, neuroprotective and anti-stress drugs, as well as the dietary supplements. Besides, lecithin consisting up to 70% of the phospholipids mixture: phosphatidylcholine, phosphatidylethanolamine, phosphatidylinositol and phosphatidic acid, is the often component of food production as an emulsifier. Dose of these biologically active substances in the modern human diet could be quite high. Previously we have shown that chronic intestinal inflammation in Muc2-knockout mice induces behavioral changes along with the significant increase in the content of phospholipids in intestinal epithelial cells, particularly, phosphatidylcholine, phosphatidylserine and phosphatidic acid. Here we investigate the effects of long-term administration of a mixture of these phospholipids, as well as the effects of long-term administration of soy lecithin on the behavioral patterns in laboratory mice. Animals long-term taken a phospholipid mixture shows no normally observed preference towards females in the two intruders test (with female and male). In the social odor preference test, they also did not distinguish female and male odors, while non-social odors discrimination preserved. In addition, we identified a decrease in anxiety, obsessive traits, and schizophrenia-like behavior traits in these animals. Soy lecithin supplementation had similar effects on social behavior and compulsive traits, and increased aggression in males. Thus, long-term perinatal administration of either mixture of phospholipids (phosphatidylcholine, phosphatidylserine and phosphatidic acid) or soy lecithin can influence various aspects of behavior in mice.

Male Body Odor Affects Emotional State, LH, and Cortisol Secretion in Women of Different Age Groups.

Hormone changes across women's menstrual cycles may lead to changes in their perceptions of chemical signals and their hormonal responses to these cues. The aim of the present study was to determine the role of menstrual cycle phase in the response to extracts of male axillary secretions (EMAS) in women. We tested healthy reproductive age and premenopausal women (n = 29). An EMAS/control solution was applied once every two hours during either the follicular or luteal phase, at which point saliva samples for luteinizing hormone (LH) and cortisol monitoring were collected. LH and cortisol concentrations were analyzed using the enzyme immunoassay (EIA) technique. Positive and Negative Affect Schedule (PANAS) and Visual Analogue Scales (VAS) scores were used to assess the participants' moods. For the first time, we showed that EMAS may produce opposite effects on LH secretion depending on the menstrual cycle phase of the recipient. We observed a significant increase in the number of LH peaks (p = 0.0447) and their amplitudes (p = 0.0469) when EMAS was applied during the follicular phase, while the same application in the luteal phase lowered the amplitudes of LH peaks (p = 0.0382). For the first time, we showed that EMAS application increased salivary cortisol levels in reproductive age women relative to premenopausal women (p = 0.0032). PANAS scores revealed changes in positive and negative affect after EMAS application. Our data indicate the significance of the menstrual cycle phase for EMAS' effects on LH secretion and mood, but not on cortisol secretion in women.

La presencia de cuernos determina el rango social de carneros Dorper

The aim was to determine if the presence of horns on rams defines whether they are high-ranking or low-ranking. Dorper rams (n = 20) were evaluated to determine their social rank (SR), either high (HSR) or low (LSR), under intensive management conditions. Upon SR classification, the morphometric variables horns presence (HP) or absence (HA) and distance between them, the height at the withers, body length, thoracic perimeter, and scrotal circumference, male odor, body weight, and body condition score were registered. Afterward, semen evaluations were performed, recording the ejaculated volume, sperm concentration, and mass motility. There were no differences (p > 0.05) for the morphometric variables between the groups. However, HP as well as semen quality were higher (p < 0.05) in HSR males. The presence of horns in the rams determined their social rank and the dominant males showed better semen quality than the subordinate males.

Odour preferred males led to a higher offspring number in the common vole

Very recently, an interesting phenomenon was described in the common vole; vole parents with similar locomotor ability produced significantly larger litters. Positive assortative mating is a tendency to prefer individuals with similar phenotypes. We tested whether this also applies to smell similarity. Odour preference was tested in a T-maze, where each female was presented with two male odours, i.e. shavings together with feces and urine from home boxes. After female preference was established, the female was either paired with a preferred male (chosen) or paired with a non-preferred male (opposite choice). For analysis of the relationship to odour preference, genotyping of major histocompatibility complex (MHC) Class II DRB was done using amplicon sequencing. In the set of 45 individuals from two populations, we recovered 38 nucleotide haplotypes (alleles). Similarity of alleles in parent pairs according to the indexes of Sørensen–Dice (S–D) and Jaccard were calculated. Values of these indexes in parental pairs with preferred males were significantly higher (more similar) than in not preferred. The number of offspring in parental pairs with preferred males were significantly higher than in not preferred males. However, there is no correlation between the mentioned indexes and the number of offspring. The relationship between the success of reproduction and alleles is not clear-cut, this may be influenced by the measure of similarity we used, or by something that we could not detect.

Sensory trap leads to reliable communication without a shift in nonsexual responses to the model cue.

The sensory trap model of signal evolution suggests that males manipulate females into mating using traits that mimic cues used in a nonsexual context. Despite much empirical support for sensory traps, little is known about how females evolve in response to these deceptive signals. Female sea lamprey (Petromyzon marinus) evolved to discriminate a male sex pheromone from the larval odor it mimics and orient only toward males during mate search. Larvae and males release the attractant 3-keto petromyzonol sulfate (3kPZS), but spawning females avoid larval odor using the pheromone antagonist, petromyzonol sulfate (PZS), which larvae but not males, release at higher rates than 3kPZS. We tested the hypothesis that migratory females also discriminate between larval odor and the male pheromone and orient only to larval odor during anadromous migration, when they navigate within spawning streams using larval odor before they begin mate search. In-stream behavioral assays revealed that, unlike spawning females, migratory females do not discriminate between mixtures of 3kPZS and PZS applied at ratios typical of larval versus male odorants. Our results indicate females discriminate between the sexual and nonsexual sources of 3kPZS during but not outside of mating and show sensory traps can lead to reliable sexual communication without females shifting their responses in the original context.

Hair from sexually active bucks strongly activates olfactory sensory inputs but fails to trigger early first ovulation in prepubescent does

Early exposure of does to sexually active bucks triggers early puberty onset correlating with neuroendocrine changes. However, the sensory pathways that are stimulated by the male are still unknown. Here, we assessed whether responses to olfactory stimuli are modulated by social experience (exposure to males or not) and/or endocrine status (prepubescent or pubescent). We used a calcium imaging approach on goat sensory cells from the main olfactory epithelium (MOE) and the vomeronasal organ (VNO). For both cell types, we observed robust responses to active male hair in females under three physiological conditions: prepubescent females isolated from males (ISOL PrePub), pubescent females exposed to males (INT Pub) and isolated females (ISOL Pub). Response analysis showed overall greater proportion of responses to buck hair in ISOL PrePub. We hypothesized that females would be more responsive to active buck hair during the prepubertal period, with numerous responses perhaps originating from immature neurons. We also observed a greater proportion of mature olfactory neurons in the MOE and VNO of INT Pub females suggesting that male exposure can induce plastic changes on olfactory cell function and organization. To determine whether stimulation by male odor can advance puberty, we exposed prepubescent does to active buck hair (ODOR). In both ODOR and females isolated from males (ISOL) groups, puberty was reached one month after females exposed to intact bucks (INT), suggesting that olfactory stimulation is not sufficient to trigger puberty.

Phospholipid supplementation inhibits male and female odor discrimination in mice.

Dietary phospholipids (PLs) are promising supplements that are commonly found as natural food ingredients and emulsifier additives. The present study aimed to evaluate the effect of major PLs found in food supplements on social behavior in mice. In this study, the effect of short-term high dietary PL content was studied in terms of social odor discrimination and social interactions with male and female intruders in male mice. We used odor discrimination and habituation tests to demonstrate that PL-fed male mice tend to lose preference toward female odor and fail to discriminate against socially significant scents. At the same time, test animals recognize non-social odors. We also found that PL affected the social behavior of the test males, who tend to behave indiscriminately toward male and female intruders during direct contact. Brain metabolomic profiling revealed no major changes in the intermediary metabolism or neurotransmitter biosynthesis. At the same time, intranasal PL application resembled the effects of dietary supplementation. These data suggest that certain PL might suppress pheromone perception in the olfactory system and affect the sense of socially important odor cues.

Sexual discrimination and attraction through scents in the water vole, Arvicola terrestris.

In mammals, especially rodents, social behaviours, such as parenting, territoriality or mate attraction, are largely based on olfactory communication through chemosignals. These behaviours are mediated by species-specific chemosignals, including small organic molecules and proteins that are secreted in the urine or in various fluids from exocrine glands. Chemosignal detection is mainly ensured by olfactory neurons in two specific sensory organs, the vomeronasal organ (VNO) and the main olfactory epithelium (MOE). This study aimed to characterise the olfactory communication in the fossorial ecotype of the water voles, Arvicola terrestris. We first measured the olfactory investigation of urine and lateral scent gland secretions from conspecifics. Our results showed that water voles can discriminate the sex of conspecifics based on the smell of urine, and that urinary male odour is attractive for female voles. Then, we demonstrated the ability of the VNO and MOE to detect volatile organic compounds (VOCs) found in water vole secretions using live-cell calcium imaging in dissociated cells. Finally, we evaluated the attractiveness of two mixtures of VOCs from urine or lateral scent glands in the field during a cyclical outbreak of vole populations.

Feeding on the Fruit Waste Orange Bagasse Modifies Immature Protein Content, Body Weight, Scent Bouquet Composition, and Copula Duration in Males of a Tephritid Frugivorous Fly.

Anastrepha ludens is a polyphagous frugivorous tephritid that infests citrus and mango. Here, we report the establishment of a laboratory colony of A. ludens reared on a larval medium that is a waste for the citrus industry, specifically, orange (Citrus × sinensis) fruit bagasse. After 24 generations of rearing on a nutritionally poor orange bagasse diet, pupae weighed 41.1% less than pupae from a colony reared on a nutritionally rich artificial diet. Larvae from the orange bagasse diet had 6.94% less protein content than larvae from the artificial diet, although their pupation rate was similar. Males from the orange bagasse diet produced a scent bouquet with 21 chemical compounds and were sexually competitive, but they had significantly shorter copulations when compared to males from the artificial diet and from the wild host, Casimiroa edulis, which had relatively simple scent bouquets. The chemical complexity in the odors of males from the orange bagasse diet might initially have attracted females to novel scent combinations, but, once in the copula, they may have been able to sense negative characteristics in males, leading them to terminate copulations soon after they began. We conclude that A. ludens can adjust morphological, life history, nutritional, and chemical traits when adapted to a larval environment consisting of fruit bagasse.

Effects of pharmacological castration on endocrinological and chemical profiles in captive red and fallow deer

In wildlife captive management, contraception is highly desirable due to inbreeding risk and needed control of intra- and inter-specific aggressions. Deer, for which surgical castration can cause abnormal growth of the antlers, are suitable candidates for pharmacological castration. The aim of this study was to evaluate the effect of pharmacological castration on the physiological patterns and volatile chemical profiles of two deer species. We placed a subcutaneous implant of deslorelin acetate (4.7 mg) on four male red deer (Cervus elaphus) and two male fallow deer (Dama dama) (N = 6) living together in a mixed-sex and -species group housed at a wildlife rescue centre in Tuscany, Italy. We combined hormone measurements and chemical investigation of metatarsal scent-gland odour secretions to test whether pharmacological castration will influence the volatile chemical profile, potentially modifying the olfactory communication during the rutting season. We used radioimmunoassay technique to determine faecal and plasma testosterone as well as faecal cortisol levels, and solid-phase microextraction coupled to gas chromatography-mass spectrometry to analyse the scent-gland odour secretions. We found that deer testosterone levels decreased after the subcutaneous deposition of the implant. However, castrated red deer exhibited more variability in testosterone concentrations throughout the study period compared to fallow deer, whose testosterone levels remained low after the implant. We detected a total of 124 (red deer) and 88 (fallow deer) volatile compounds in male scent-gland odour secretions, including naturally occurring ketones, alcohols, aldehydes, terpenes, carboxylic acids, esters, volatile fatty acids, and hydrocarbons. Odour richness, but not total abundance or ratios of compounds, changed with testosterone levels in red deer. In conclusion, our preliminary findings suggest that deslorelin acetate, causing a decrease of testosterone level and impacting the chemical profile of odour secretions, could work as a non-invasive contraception approach in human-managed populations of deer.

Microglia phagocytosis mediates the volume and function of the rat sexually dimorphic nucleus of the preoptic area

The sexually dimorphic nucleus of the preoptic area (SDN-POA) is the oldest and most robust sex difference reported in mammalian brain and is singular for its presence across a wide range of species from rodents to ungulates to man. This small collection of Nissl-dense neurons is reliably larger in volume in males. Despite its notoriety and intense interrogation, both the mechanism establishing the sex difference and the functional role of the SDN have remained elusive. Convergent evidence from rodent studies led to the conclusion that testicular androgens aromatized to estrogens are neuroprotective in males and that higher apoptosis (naturally occurring cell death) in females determines their smaller SDN. In several species, including humans, a smaller SDN correlates with a preference for mating with males. We report here that this volume difference is dependent upon a participatory role of phagocytic microglia which engulf more neurons in the female SDN and assure their destruction. Selectively blocking microglia phagocytosis temporarily spared neurons from apoptotic death and increased SDN volume in females without hormone treatment. Increasing the number of neurons in the SDN in neonatal females resulted in loss of preference for male odors in adulthood, an effect paralleled by dampened excitation of SDN neurons as evidenced by reduced immediate early gene(IEG) expression when exposed to male urine. Thus, the mechanism establishing a sex difference in SDN volume includes an essential role for microglia, and SDN function as a regulator of sexual partner preference is confirmed.

Infection with Cryptosporidium parvum Affects Secondary Sexual Characteristics of Male Mice by Altering the Pheromone Content in Preputial Gland

The olfactory acuity of female mice allows them to discriminate the urinary odors of males. Parasitic infection can reduce the odor attractiveness of male mice to females and result in female aversion or avoidance responses in odor selection. However, the chemical signaling changes in the pheromone contents produced by the foreskin gland were not fully revealed after parasitic infection. Cryptosporidium parvum (C. parvum) is a common zoonotic intestinal parasite and has a wide range of hosts, including human, domestic animals, and wild animals. In this study, we immunosuppressed ICR/CD-1 male mice by dexamethasone sodium phosphate treatment. After C. parvum infection, physiological indexes such as body weight and organ weight were significantly decreased. Furthermore, the gene expression level of MUP (major urinary protein) in liver and urine were significantly down-regulated, which could be the reason for the decrease in urine attractiveness to females. GC-MS was performed to analyze the changes in the pheromone produced by the preputial gland before and after parasitic infection, and the results indicated that the levels of different pheromones were significantly reduced after parasitic infection. In summary, this study reveals that C. parvum infection damages the secondary sexual characteristics of male ICR/CD-1 male mice and decreases the pheromone content produced by the foreskin gland.

Efficacy and Safety of 4.7 mg Deslorelin Acetate Implants as a Neutering Option in Male Cats: A Large-Scale Multicentre Randomised Controlled Study.

This multicenter-controlled, double-masked randomized European study was conduc-ted to confirm both the efficacy and safety of a deslorelin implant in controlling fertility and sexual behavior in a large population of tom cats over a 12-month period. Among the 225 screened individuals, a total of 205 privately owned indoor intact male cats, aged 3 months of age or older, were randomly allocated to a deslorelin implant (n = 154) or to a negative control group (n = 51). After the screening visit performed between day (D)-14 and D-7, six additional visits were sche-duled on D0, D45, D93, D186, D279 and D372. Effects on testosterone, sexual behaviors, penile spines, testicular volume and intact male cat urine odor were assessed at every visit under masked conditions as regards to the treatment group. In addition, phone calls from the investigators to the owners were scheduled on D7 and then on a monthly basis whenever no visit was scheduled. Success was defined as an individual serum testosterone concentration below or equal to 0.10 ng/mL and was 77.9% at D45, 83.1% at D93, 84.4% at D186 and D279, and 61.7% at D372 in the deslorelin group, and 3.9% at D45, 5.9% at D93, 3.9% at D186, 7.8% at D279 and 3.9% at D372 in the negative control group. Testing for superiority was made stepwise from D45 to D372 upwards; the difference in success rates was significant from D45 to D372 (p < 0.001 for each time point). The mean testosterone concentration dropped from baseline in the deslorelin group, remaining below the set threshold of 0.1 ng/mL until D372. From D7 onwards, the mean sum score for sexual behaviors (including vocalization, urine marking, aggression and intact male cat urine odor) was significantly lower at each observation time point in the deslorelin group compared to the control group, where no decrease in scores was observed. The mean percent change to baseline of the testicular volume and the percentage of cats with a decreased visibility and adult appearance of penile spines were significantly lower in the deslorelin group as soon as D45. No relevant safety concerns were reported during the course of the study. The deslorelin implant Suprelorin® 4.7 mg (Virbac, Carros, France) is a safe and effective neutering option, inducing infertility over a 12-month period when administered to intact male cats aged between 3 months of age and 11 years of age. The implants also successfully reduced sexual behaviors (i.e., vocalization, urine marking, aggression), intact male cat urine odor, testicular volume and penile spine score for 1 year (372 ± 5 days).

Variation of ewe olfactory secretome during a ram effect.

Under temperate latitudes, reproduction in Ovis aries displays a marked seasonality, governed by the photoperiod. In natural conditions, the transition between sexual rest and sexual activity in both sexes is induced by the decrease of day light. Meanwhile, specific odors emitted by a sexually active male are able to reactivate the gonadotropic axis of anovulatory ewes. This physiological effect is called "male effect", precisely ram effect in the ovine species. We have previously shown that the secreted proteins, namely Olfactory Binding Proteins (OBP), contained in the nasal mucus constitute the olfactory secretome (OS), the composition of which is determined by the status of oestrus cycle of females and differs between sexual rest and sexual activity periods. The objective of this study was to test the hypothesis that exposure to sexually active male can also modify the composition of ewes olfactory secretome during a male effect, as well as hormones produced by the reactivation of the oestrus cycle in sexual activity period under natural conditions. We have set up a new non-invasive protocol of nasal mucus sampling and collected it from 12 ewes at different times during a ram effect. We analyzed the composition of their olfactory secretome by proteomics, mainly SDS-PAGE and MALDI-TOF mass spectrometry. As post-translational modifications of OBPs were a hallmark of ewes' sexual activity period, we were looking for glycosylation by western-blot and mass spectrometry. The efficiency of male effect was low in stimulated ewes as only 3 females displayed elevated progesterone levels in their blood. Besides, half of control ewes (non-stimulated ones) were cycled. We noticed a common OS profile in ewes in anoestrus, versus OS of cycled ones. A very clear and important result was the apparition of O-GlcNAcylation, previously detected only in sexual activity, after only 30 min of male introduction into the flock. This exploratory study paves the way for further experiments with larger flock to confirm and reinforce these results, and for eventually exploiting the nasal mucus as an indicator of females' receptivity to male odors.

Lifespan extension in female mice by early, transient exposure to adult female olfactory cues.

Several previous lines of research have suggested, indirectly, that mouse lifespan is particularly susceptible to endocrine or nutritional signals in the first few weeks of life, as tested by manipulations of litter size, growth hormone levels, or mutations with effects specifically on early-life growth rate. The pace of early development in mice can also be influenced by exposure of nursing and weanling mice to olfactory cues. In particular, odors of same-sex adult mice can in some circumstances delay maturation. We hypothesized that olfactory information might also have a sex-specific effect on lifespan, and we show here that the lifespan of female mice can be increased significantly by odors from adult females administered transiently, that is from 3 days until 60 days of age. Female lifespan was not modified by male odors, nor was male lifespan susceptible to odors from adults of either sex. Conditional deletion of the G protein Gαo in the olfactory system, which leads to impaired accessory olfactory system function and blunted reproductive priming responses to male odors in females, did not modify the effect of female odors on female lifespan. Our data provide support for the idea that very young mice are susceptible to influences that can have long-lasting effects on health maintenance in later life, and provide a potential example of lifespan extension by olfactory cues in mice.

Different armpits under my new nose: Olfactory sex but not gender affects implicit measures of embodiment

Conflicting multisensory signals may alter embodiment to produce self-identification with a foreign body, but the role of olfaction in this process has been overlooked. We studied in healthy participants how sex (male and female sweat odors) and gender (male and female cosmetic scents) olfactory stimuli contribute to embodiment. Participants saw, on a head mounted display, the first-person perspective of a sex mismatching person. Synchronous visuotactile stimulation was applied to enhance illusory embodiment. Simultaneously, they smelled either sex- or gender- congruent or incongruent stimuli. We assessed implicit (skin conductance responses to visual threats) and explicit (questionnaire) measures of embodiment. Stronger responses to threat were found when participants smelled the sex-congruent compared to the sex-incongruent odor, while no such differences were found for the cosmetic scents. According to the questionnaire, embodiment did not differ between conditions. Post-experimental assessment of the presented cues, suggest that while both sweat odors were considered generally male, cosmetic scents were not. The presented scents were generally not associated with the embodied body. Our results suggest that sex-related body odors influence implicit but not explicit aspects of embodiment and are in line with unique characteristics of olfaction in other aspects of cognition.

Male scent but not courtship vocalizations induce estrus in wild female house mice

Exposure to males or male urinary scent can induce and accelerate the rate of female estrous cycling in house mice ("Whitten effect"), and this response has been replicated many times since its discovery over 60 years ago. Here, we tested whether exposing female mice to recordings of male courtship ultrasonic vocalizations (USVs) induces estrous cycling, and whether exposure to both male scent and USVs has a stronger effect than to either of these stimuli alone. We conducted our study with 60 wild-derived female house mice (Mus musculus musculus). After singly housing females for 14 days, we monitored estrous stages via vaginal cytology for two weeks while isolated from males or male stimuli. We continued monitoring estrus for two more weeks during experimental exposure to one of four different types of stimuli: (1) clean bedding and background noise playback (negative control); (2) recordings of male USVs (16 min per day) and clean bedding (male USV treatment); (3) soiled male bedding and background noise playback (male odor treatment; positive control); or (4) male USVs and soiled male bedding (male odor and USV treatment). Females were then paired with males to test whether any of the four treatments influenced female reproduction (especially latency to birth). We confirmed that exposure to male odor increased female cycling, as expected, but exposure to recordings of male USVs had no effect on estrus. Females exposed to both USVs and odor went through more cycles compared to controls, but did not differ significantly from exposure to male odor (and background noise). After pairing females with a male, females showing male odor-induced cycling produced their first litter sooner than controls, whereas USVs did not have such an effect. This is the first study to our knowledge to show that male odor induces estrus in wild house mice and to show functional effects on reproduction. Our results do not support the hypothesis that male vocalizations induce female estrus, although we suggest other approaches that could be used to further test this hypothesis.

Electronic Nose Signals for Analysing Similarity of Male and Female Axillary Odour to Food Material Aroma

Electronic Nose Signals for Analysing Similarity of Male and Female Axillary Odour to Food Material Aroma