Ultrasonic vocalizations by male house mice (Mus musculus) to novel odors: Roles of infant and adult experience.

Conducted 2 experiments to examine 70-kHz ultrasonic courtship vocalizations by adult male mice to novel odors following exposure to these odors in infancy and/or adulthood. Exp I, with 72 males, demonstrated that adult males normally do not vocalize to the urine of female rats but would if adult female mice odorized with female rat urine were repeatedly encountered postpubertally. On the other hand, encountering their own mother odorized with female rat urine from birth until weaning did not promote vocalizations to the urine of female rats. Exp II, with 100 males, examined vocalizations to the urine of female mice whose urinary odor was altered by the ingestion of fenugreek, a spice. Greater amounts of vocalization again were seen by males that as adults encountered females that had ingested fenugreek. Again, experience with the novel odor during infancy was not associated with elevated vocalizations during adulthood either to fenugreek-altered urine or to the fenugreek odor itself. Vocalizations to 2 different novel odors occurred only after an adult male had encountered an adult female odorized with the novel odor. (57 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Odor preferences of female Peromyscus maniculatus bairdi for male mouse odors of P. m. bairdi and P. leucopus noveboracensis as a function of estrous state.

Tested 20 sexually naive mature P. m. bairdi female mice for male mouse (P. m. bairdi and P. l. noveboracensis) odor preferences during natural estrous and diestrous conditions in a 2-choice Plexiglas olfactorium. The homospecific odor side was chosen 76% of the time by estrous Ss and 43% of the time by diestrous Ss. Only the estrous group differed significantly from the expected 50:50 distribution. High intratest reliability coefficients suggested stable modes of responding within test sessions. These findings suggest female P. m. bairdi reactions to male mouse odors are influenced by gonadal state, and that olfaction conceivably plays a role in sexual isolation between these species. (29 ref.) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Molecular evolution of two lineages of L1 (LINE-1) retrotransposons in the california mouse, Peromyscus californicus

The large number of L1 [long interspersed elements (LINE)-1] sequences found in the genome is due to the insertion of copies of the retrotransposon over evolutionary time. The majority of copies appear to be replicates of a few active, or "master" templates. A continual replacement of master templates over time gives rise to lineages distinguishable by their own unique set of shared-sequence variants. A previous analysis of L1 sequences in deer mice, Peromyscus maniculatus and P. leucopus, revealed two active L1 lineages, marked by different rates of evolution, whose most recent common ancestor predates the expansion of the Peromyscus species. Here we exploit lineage-specific, shared-sequence variants to reveal a paucity of Lineage 2 sequences in at least one species, P. californicus. The dearth of Lineage 2 copies in P. californicus suggests that Lineage 2 may have been unproductive until after the most recent common ancestor of P. californicus and P. maniculatus. We also show that Lineage 1 appears to have a higher rate of evolution in P. maniculatus relative to either P. californicus or P. leucopus. As a phylogenetic tool, L1 lineage-specific variants support a close affinity between P. californicus and P. eremicus relative to the other species examined.     

Olfactory discrimination of mouse strains (Mus musculus) and major histocompatibility types by humans (Homo sapiens).

Examined, in 5 experiments, whether the olfactory differences apparent to mice are also accessible to humans, using a total of 63 human Ss. In Exp I, Ss were asked to distinguish between the whole-body odors of live mice differing genetically only at the major histocompatibility gene complex (H-2). In Exps II and III, the odor source was mouse fecal pellets, and in Exps IV and V, the odor source was mouse urine. Results reveal that humans can use olfaction to discriminate closely related strains of mice. The possibility that excreted metabolites with characteristic odors may have predated the evolution of an adaptive function for these odors in social communication is suggested. (22 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Intermale fighting affected by home-cage odors of male and female mice.

Conducted 3 experiments to test the hypothesis that male mice can produce an aggression-inhibitory or facilitory odor under varying conditions of social stimulation. In Exp I, 25 male fighter mice fought 25 castrated opponents more vigorously in soiled home cages of either single or stable groups of male mice than they did in clean cages. Fighting was also stimulated in cages briefly occupied by other pairs of fighting mice. It is concluded that the release of aggression-promoting home-cage odors by male mice is not necessarily a consequence of social instability and that they are of urinary, rather than preputial, origin. In Exp II (with 21 fresh Ss) and Exp. III (with 30 Ss from Exp I), odors deposited by either single or groups of female mice greatly reduced fighting, indicating that their urinary aggression-inhibiting pheromone is effective after deposition upon the home environment. Testosterone propionate implants abolished the females' inhibitory pheromone and did so independently of their enlarged preputial glands. (20 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Influence of environmental complexity and space on social interactions of mice (Mus musculus and Peromyscus leucopus).

Examined the effects of environmental space and complexity on social behavior in albino laboratory and wild house mice (M. musculus) and wild white-footed mice (Peromyscus leucopus). Pairs of males or females of each type were introduced into circular arenas of 0.5-, 1-, or 2-m diameter containing 0, 8, or 16 internal barriers. Behavioral characteristics were assessed by multivariate cluster and principal components analyses. Differences between laboratory Ss and the 2 wild groups of Ss reflected the better sensory capabilities and greater reactivity of the wild Ss. M. musculus and P. leucopus were reactive at greater distances, they spent more time freezing and/or grooming, and their behavior was influenced by environmental complexity. The laboratory Ss exhibited reactions only at short distances. M. musculus were more aggressive than P. leucopus, and M. Musculus males were more aggressive than females. Although the amount of space available influenced all 3 types of Ss, effects differed. Laboratory Ss simply encountered each other less often in larger areas, whereas both groups of wild Ss actively used the space to avoid other individuals. Male M. musculus were more aggressive as space decreased; female M. musculus and P. leucopus showed no such change. Behaviors related to orienting toward other mice and moving away from them were more frequent in more open areas. Vision appeared to be the sensory modality used, although audition may have played a role. (36 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Odor preferences of female house mice (Mus domesticus) in seminatural enclosures.

Preferences for male odors by female house mice (Mus domesticus) were examined with respect to age, dominance status, and spatial relationships. Mice were free living in 6 field enclosures. Estrous or nonestrous females were placed in an aquarium with soiled bedding from live traps as the odor source. Females were tested for preferences between (1) adult and juvenile male odors, (2) dominant and subordinate male odors, and (3) "near" and "far" male odors. In dominance odor tests, estrous females preferred odors from dominant males; nonestrous females exhibited no significant preferences. In adult juvenile and spatial odor tests, there were no significant differences between odor preferences of estrous and nonestrous females. However, most females preferred odors from adult and "near" males. Male dominance status appears to be the strongest influence on female odor preference in these seminatural enclosures. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Sex differences in urinary odors produced by young laboratory rats (Rattus norvegicus).

Examined the responses of 75 primiparous Long-Evans rat dams and 20 nonmaternal Long-Evans females to male and female pup urine in 3 experiments. Investigatory sniffing of male and female pup urine deposits by maternal Ss was compared in a series of simultaneous choice tests given at 3-day intervals between Day 2 and Day 17 postpartum. Male urine was consistently preferred. Introduction of male but not female pup urine to the nest was found to significantly elevate maternal licking of anogenital regions of pups. Thus, urine from pups of various ages contains sex-identifying odors that differentially elicit spontaneous maternal interest. The odor of male urine may provide a sufficient stimulus to account for the greater anogenital licking that males of this species normally receive. Nonmaternal, naive, adult Ss behaved like maternal Ss, preferring male urine in the choice test, which indicates that the maternal condition of a dam is not necessary either for the olfactory discrimination or for the male odor preference. (13 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Form and development of predation on crickets in adults of Peromyscus maniculatus bairdi and P. leucopus noveboracensis..

Three experiments compared the similarities and differences in attacks on crickets by two species of laboratory-raised cricetid mice, Peromyscus maniculatus bairdi and P. leucopus noveboracensis. In Experiment 1 moderately prey-experienced 1.5-year-old mice of both species concentrated attacks on the crickets' dorsal head. P. leucopus also produced considerable damage to the thorax and showed a greater effect of sessions on the location and latency of attack. In Experiment 2 prey-naive .4- to .8-year-old mice of both species initially damaged crickets randomly and were slow to attack, but after two sessions both species attacked rapidly and displayed the same focus on the dorsal head shown in Experiment 1. However, P. leucopus did not display the thoracic focus shown by this species in Experiment 1. In Experiment 3 the P. leucopus from Experiment 2 were retested at 1.5 years of age without further predatory experience and showed the thoracic focus of attack found in Experiment 1. Young adults of both species markedly and similarly increased the speed and focus of predatory attacks on crickets after limited experience. The attack characteristics of older P. maniculatus differed very little from those of experienced young adults, whereas the attack characteristics of P. leucopus changed as a function of both age and subsequent test experience. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Tests of preferences of adult deer mice (Peromyscus maniculatus bairdi) for siblings versus nonsiblings.

Seven experiments were conducted to test the performance of adult deer mice (Peromyscus maniculatus bairdi) in discriminating and preferring siblings versus nonsiblings. In two experiments, there was no indication of preferences based on odor alone. Further there was no indication of kin discrimination in a seminatural enclosure. There was some indication that in a test apparatus, estrous females associate preferentially with male siblings rather than nonsiblings. The effect appears dependent on the presence of siblings during development. Although the finding of a preference for siblings in estrous females is counter to expectations from an inbreeding avoidance approach, this is one of a variety of findings to suggest that not all animals avoid inbreeding all of the time. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Sexually dimorphic enhancement by estradiol of male urinary odor detection thresholds in mice.

We asked whether sex and adult estrogen exposure influence the detection thresholds for urinary odors used by mice to guide their social behaviors. Gonadectomized (GDX) male and female mice were trained on a two-choice food-motivated task to determine detection thresholds for male urinary odors. There was no significant sex difference in the detection of these odors by GDX subjects without hormone replacement. However, during treatment with estradiol benzoate (EB), GDX females, but not GDX males, showed an enhanced ability to detect these odors. To investigate a possible mechanism for this effect, the authors measured GDX females' odor-sampling behavior (sniffing) by monitoring intranasal pressure transients during performance of the urinary odor detection task with and without EB treatment. Under both hormone conditions, females decreased their sniffing frequency as the urinary odor concentration decreased, with this decrease being significantly greater while GDX females received EB. Thus, estradiol enhanced detection thresholds for male urine in a sex-specific manner, and this enhanced sensitivity in females was correlated with altered odor-sampling behavior. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Social dominance, reproduction, and release of the maturation-delaying chemosignal in the urine of female house mice (Mus musculus).

Conducted 5 experiments to investigate the effects of social status in groups of female mice on reproduction and on the release of urinary chemosignals that accelerate or delay the onset of sexual maturation. In Exps I and II, using 184 Ss, treatment of young females with urine from bottom-ranking, but not top-ranking, Ss in groups of 5 adult females resulted in delays in puberty comparable to those produced by treatment with urine pooled from females housed at moderate to high densities. In Exps III and IV, using 220 Ss, there was an interaction between the S's social rank and the stages of the estrous cycle with respect to the presence in the urine of chemosignals from grouping that delay puberty and estrus that accelerate puberty. Within groups of 5 Ss, top-ranking Ss were in estrus more frequently than bottom-ranking Ss. Individually caged Ss treated with urine from top-ranking females were in estrus more frequently than those treated with urine from bottom-ranking females. In Exp V, using 100 Ss, when grouped females were separated into individual cages and mated, more top-ranking Ss conceived and bore litters than bottom-ranking Ss. Bottom-ranking Ss produced more female pups than did top- and middle-ranking Ss. (32 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Discrimination among colony mates' anogenital odors by guinea pigs (Cavia porcellus).

Three experiments used an aversively motivated learning task to examine the ability of adult guinea pigs to discriminate among odors from nonspecific anogenital swabbings of colony mates. Exps I and II examined the ability of 8 male (M) and 8 female (F) Ss to discriminate among odors of colony mates controlled for age and sex. Both sexes were able to discriminate among individual Ss on the basis of odor. Since individual Ss could be discriminated, Exp III, examining detection of physiological estrus, tested the ability of 6 Ms and 6 Fs to discriminate preserved odor samples from the same F during conditions of estrus and nonestrus. Both Ms and Fs were able to discriminate between the conditions. Results are discussed with reference to the involvement of odor in the social behavior of guinea pigs. (33 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Social olfaction in male brown lemmings (Lemmus sibiricus?=?trimucronatus) and collared lemmings (Dicrostonyx groenlandicus): II. Discrimination of mated and unmated females.

Four experiments were conducted with 32 brown and 80 collared male lemmings. When tested in a Y-maze olfactometer, both species preferred the odor of unmated receptive females to the odor of females with which they had just copulated. Similarly, sexually satiated Ss preferred the odor of an unmated receptive female to that of a strange female that had recently copulated with another male. Sexually experienced Ss without recent copulatory experience also demonstrated this preference, but sexually naive Ss did not. Sexually satiated collared lemmings preferred the odor of bedding from a novel estrous female to bedding from the female with which they had just copulated even when the bedding was collected before mating occurred. Results suggest that discrimination between prior mates and unmated females may be based on individual recognition as well as recognition of subclasses of females (i.e., mated vs unmated, familiar vs unfamiliar). (22 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Male hamster preference for odors of female hamster vaginal discharges: Studies of experiential and hormonal determinants.

In a study with 21 male hamsters, it was found that Ss approached sources of odors from female hamster vaginal discharges and spend significantly more time around these odor sources than around control locations in the test box. This preference for female vaginal odors appeared in sexually inexperienced as well as experienced males even in Ss isolated from females since the time of weaning. Castration significantly reduced the sex odor preference, and treatment with testosterone propionate partially restored it. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Copulatory behavior of deer mice (Peromyscus maniculatus): I. Normative data, subspecific differences, and effects of cross-fostering.

In Exp I, normative data were collected on copulatory behavior in 16 male–female pairs of Peromyscus maniculatus bairdi, each mated for 5 tests. P. m. bairdi display a pattern with no lock, no intravaginal thrusting, multiple intromissions prerequisite to ejaculation, and multiple ejaculations. They had a mean of 3.6 ejaculations, with the 1st ejaculation preceded by a mean of 6.4 intromissions spaced 72 sec apart. In Exp II, data from 17 male–female pairs of P. m. Blandus were compared with data from 2 samples of P. m. bairdi and a sample of P. m. gambeli from an earlier study. Although there were no qualitative differences among subspecies, significant quantitative differences were found for 11 of the 14 measures considered. In Exp III, data from 17 males cross-fostered to Mus musculus parents on the day of birth were compared with those of deer mice reared by their own parents. Cross-fostering produced no major qualitative alterations of copulatory behavior, with significant differences from normally reared males in 4 of 18 comparisons. (37 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Social stimulation of reproductive development in male deer mice housed on a short-day photoperiod.

Male deer mice (Peromyscus maniculatus), born of mothers housed on a long-day (LD) photoperiod (15:9 hrs light/dark), were either switched to a short-day (SD) photoperiod (6:18 hrs) at birth or continued on their prenatal LD photoperiod. From weaning until 6 wks of age, Ss were housed with an adult female or in social isolation. Ss reared on an SD photoperiod had smaller testes, seminal vesicles, and ventral sebaceous glands that did those reared on LD. Postweaning exposure of SD Ss to females stimulated reproductive organ growth as measured at 6 wks of age. Results indicate that both photic and social stimuli regulate reproductive development in male deer mice and that positive social cues can stimulate maturation even in the presence of negative photic cues. (26 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Progesterone antagonism of androgen-dependent aggression-promoting pheromone in inbred mice (Mus musculus).

Conducted 2 experiments to investigate a possible antagonism between progesterone (P) and testosterone propionate (TP) with regard to the latter's role as a mediator of aggression-promoting pheromone. Ss were a total of 18 male BALB/cJ inbred mice trained as fighters and 64 castrated A/J male mice. Exp I showed that castrated Ss injected with TP were attacked by fighters faster, more often, and for a longer duration than castrates treated with TP and P. Exp II revealed that castrates coated with urine collected from castrated urine donors treated with TP were attacked more often and for longer periods than castrates coated with the urine of donors given TP and P. Thus, P appears to antagonize the effect of TP on aggression pheromone through a urinary pathway. The 2nd part of Exp II replicated and confirmed the results of Exp I. Results may be explained in terms of a peripheral biochemical antagonism with TP or, more likely, by the elicitation of inhibitory cues by P. (34 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Role of ingestion in odor-toxicosis learning in the rat.

Conducted 2 experiments with 32 and 34 male Charles River albino rats, in which Ss evidenced aversions to an odor paired with toxicosis in both drinking and exploratory behavior tests. Ingestion during odor-toxicosis conditioning in Exp I resulted in stronger aversions only in tests involving drinking the same solution as had been ingested during training, despite the absence of enhanced aversions to the flavor of the solution used. This result is interpreted as evidence that Ss drinking during conditioning acquired aversions not only to the CS odor but also to additional cues arising from an interaction of the CS odor and the flavor of the ingested solution. Exp II showed that these interaction cues were not the result of a flavor imparted to the ingested substance by dissolved molecules of the odorizing agent. (15 ref.) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The role of vaginal secretion in hamster sexual behavior: Males' responses to normal and vaginectomized females and their odors.

Two experiments (with 60 adult male hamsters and 4 sexually naive male hamsters) examined the importance of vaginal secretion relative to other feminine odors for attraction of males and elicitation of copulatory behavior by comparing the behavior of males toward normal females with that toward vaginectomized Ss. Males were more attracted to intact females than to vaginectomized Ss when odors were the only cues available and also when auditory, visual, and odor cues were available but contact was prevented. There were no differences in the attractiveness of estrous and diestrous Ss whether intact or vaginectomized. When males and females were allowed to interact, there were no differences in any measures of male sexual behavior toward normal vs vaginectomized females, which indicates that the presence of vaginal secretion is not necessary for male sexual behavior. The significance for conceptions of pheromone action in mammals is discussed. (45 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)