Search

ABSTRACTThe gut microbiota is shaped by host metabolism. In house mice (Mus musculus), major urinary protein (MUP) pheromone production represents a considerable energy investment, particularly in sexually mature males. Deletion of the Mup gene family shifts mouse metabolism toward an anabolic state, marked by lipogenesis, lipid accumulation, and body mass increases. Given the metabolic implications of MUPs, they may also influence the gut microbiota. Here, we investigated the effect of a deletion of the Mup gene family on the gut microbiota of sexually mature mice. Shotgun metagenomics revealed distinct taxonomic and functional profiles between wild-type and knockout males but not females. Deletion of the Mup gene cluster significantly reduced diversity in microbial families and functions in male mice. Additionally, a species of Ruminococcaceae and several microbial functions, such as transporters involved in vitamin B5 acquisition, were significantly depleted in the microbiota of Mup knockout males. Altogether, these results show that MUPs significantly affect the gut microbiota of house mouse in a sex-specific manner.IMPORTANCEThe community of microorganisms that inhabits the gastrointestinal tract can have profound effects on host phenotypes. The gut microbiota is in turn shaped by host genes, including those involved with host metabolism. In adult male house mice, expression of the major urinary protein (Mup) gene cluster represents a substantial energy investment, and deletion of the Mup gene family leads to fat accumulation and weight gain in males. We show that deleting Mup genes also alters the gut microbiota of male, but not female, mice in terms of both taxonomic and functional compositions. Male mice without Mup genes harbored fewer gut bacterial families and reduced abundance of a species of Ruminococcaceae, a family that has been previously shown to reduce obesity risk. Studying the impact of the Mup gene family on the gut microbiota has the potential to reveal the ways in which these genes affect host phenotypes.

Calorie restriction (CR) extends life span by modulating the mechanisms involved in aging. We quantified the hepatic proteome of male C57BL/6 mice exposed to graded levels of CR (0%–40% CR) for 3 months, and evaluated which signaling pathways were most affected. The metabolic pathways most significantly stimulated by the increase in CR, included the glycolysis/gluconeogenesis pathway, the pentose phosphate pathway, the fatty acid degradation pathway, the valine, leucine, and isoleucine degradation pathway, and the lysine degradation pathway. The metabolism of xenobiotics by cytochrome P450 pathway was activated and feminized by increased CR, while production in major urinary proteins (Mups) was strongly reduced, consistent with a reduced investment in reproduction as predicted by the disposable soma hypothesis. However, we found no evidence of increased somatic protection, and none of the 4 main pathways implied to be linked to the impact of CR on life span (insulin/insulin-like growth factor [IGF-1], nuclear factor-κB [NF-κB], mammalian Target of Rapamycin [mTOR], and sirtuins) as well as pathways in cancer, were significantly changed at the protein level in relation to the increase in CR level. This was despite previous work at the transcriptome level in the same individuals indicating such changes. On the other hand, we found Aldh2 , Aldh3a2 , and Aldh9a1 in carnitine biosynthesis and Acsl5 in carnitine shuttle system were up-regulated by increased CR, which are consistent with our previous work on metabolome of the same individuals. Overall, the patterns of protein expression were more consistent with a "clean cupboards" than a "disposable soma" interpretation. [ABSTRACT FROM AUTHOR]

Major urinary proteins (MUPs), members of the broader lipocalin protein family, are classified as pheromones that are excreted in male rodent urine to define conspecific territoriality. In screening for differentially regulated mRNA transcripts in a mouse model of type 1 experimental diabetes mellitus (DM), we identified an unexpected upregulation of several closely related MUP transcripts within diabetic sensory dorsal root ganglia (DRG). Both sexes expressed overall MUP protein content as identified by an antibody widely targeting these upregulated family members, and immunohistochemistry identified expression within neurons, satellite glial cells, and Schwann cells. In dissociated adult sensory neurons, knockdown by an siRNA targeting upregulated MUP mRNAs, enhanced neurite outgrowth, indicating a growth-suppressive role, an impact that was synergistic with subnanomolar insulin neuronal signaling. While MUP knockdown did not generate rises in insulin signaling transcripts, the protein did bind to several mitochondrial and glial targets in DRG lysates. Analysis of a protein closely related to MUPs but that is expressed in humans, lipocalin-2, also suppressed growth, but its impact was unrelated to insulin. In a model of chronic type 1 DM, MUP siRNA knockdown improved electrophysiological and behavioral abnormalities of experimental neuropathy. MUPs have actions beyond pheromone signaling in rodents that involve suppression of growth plasticity of sensory neurons. Its hitherto unanticipated actions overlap with those of lipocalin-2 and may identify a common and widely mediated impact on neuron growth properties by members of the lipocalin family. Knockdown of MUP supports the trophic actions of insulin as a strategy that may improve features of type 1 experimental diabetic neuropathy. [ABSTRACT FROM AUTHOR]

Male house mice excrete large amounts of protein in their urinary scent marks, mainly composed of Major Urinary Proteins (MUPs), and these lipocalins function as pheromones and pheromone carriers. Here, we review studies on sexually dimorphic MUP expression in house mice, including the proximate mechanisms controlling MUP gene expression and their adaptive functions. Males excrete 2 to 8 times more urinary protein than females, though there is enormous variation in gene expression across loci in both sexes. MUP expression is dynamically regulated depending upon a variety of factors. Males regulate MUP expression according to social status, whereas females do not, and males regulate expression depending upon health and condition. Male-biased MUP expression is regulated by pituitary secretion of growth hormone (GH), which binds receptors in the liver, activating the JAK2-STAT5 signaling pathway, chromatin accessibility, and MUP gene transcription. Pulsatile male GH secretion is feminized by several factors, including caloric restriction, microbiota depletion, and aging, which helps explain condition-dependent MUP expression. If MUP production has sex-specific fitness optima, then this should generate sexual antagonism over allelic expression (intra-locus sexual conflict) selectively favoring sexually dimorphic expression. MUPs influence the sexual attractiveness of male urinary odor and increased urinary protein excretion is correlated with the reproductive success of males but not females. This finding could explain the selective maintenance of sexually dimorphic MUP expression. Producing MUPs entails energetic costs, but increased excretion may reduce the net energetic costs and predation risks from male scent marking as well as prolong the release of chemical signals. MUPs may also provide physiological benefits, including regulating metabolic rate and toxin removal, which may have sex-specific effects on survival. A phylogenetic analysis on the origins of male-biased MUP gene expression in Mus musculus suggests that this sexual dimorphism evolved by increasing male MUP expression rather than reducing female expression. [ABSTRACT FROM AUTHOR]

Male house mice excrete large amounts of protein in their urinary scent marks, mainly composed of Major Urinary Proteins (MUPs), and these lipocalins function as pheromones and pheromone carriers. Here, we review studies on sexually dimorphic MUP expression in house mice, including the proximate mechanisms controlling MUP gene expression and their adaptive functions. Males excrete 2 to 8 times more urinary protein than females, though there is enormous variation in gene expression across loci in both sexes. MUP expression is dynamically regulated depending upon a variety of factors. Males regulate MUP expression according to social status, whereas females do not, and males regulate expression depending upon health and condition. Male-biased MUP expression is regulated by pituitary secretion of growth hormone (GH), which binds receptors in the liver, activating the JAK2-STAT5 signaling pathway, chromatin accessibility, and MUP gene transcription. Pulsatile male GH secretion is feminized by several factors, including caloric restriction, microbiota depletion, and aging, which helps explain condition-dependent MUP expression. If MUP production has sex-specific fitness optima, then this should generate sexual antagonism over allelic expression (intra-locus sexual conflict) selectively favoring sexually dimorphic expression. MUPs influence the sexual attractiveness of male urinary odor and increased urinary protein excretion is correlated with the reproductive success of males but not females. This finding could explain the selective maintenance of sexually dimorphic MUP expression. Producing MUPs entails energetic costs, but increased excretion may reduce the net energetic costs and predation risks from male scent marking as well as prolong the release of chemical signals. MUPs may also provide physiological benefits, including regulating metabolic rate and toxin removal, which may have sex-specific effects on survival. A phylogenetic analysis on the origins of male-biased MUP gene expression in Mus musculus suggests that this sexual dimorphism evolved by increasing male MUP expression rather than reducing female expression.

The gut microbiota is shaped by host metabolism. In house mice ( Mus musculus ), major urinary protein (MUP) pheromone production represents a considerable energy investment, particularly in sexually mature males. Deletion of the Mup gene family shifts mouse metabolism toward an anabolic state, marked by lipogenesis, lipid accumulation, and body mass increases. Given the metabolic implications of MUPs, they may also influence the gut microbiota. Here, we investigated the effect of a deletion of the Mup gene family on the gut microbiota of sexually mature mice. Shotgun metagenomics revealed distinct taxonomic and functional profiles between wild-type and knockout males but not females. Deletion of the Mup gene cluster significantly reduced diversity in microbial families and functions in male mice. Additionally, a species of Ruminococcaceae and several microbial functions, such as transporters involved in vitamin B 5 acquisition, were significantly depleted in the microbiota of Mup knockout males. Altogether, these results show that MUPs significantly affect the gut microbiota of house mouse in a sex-specific manner.IMPORTANCEThe community of microorganisms that inhabits the gastrointestinal tract can have profound effects on host phenotypes. The gut microbiota is in turn shaped by host genes, including those involved with host metabolism. In adult male house mice, expression of the major urinary protein ( Mup ) gene cluster represents a substantial energy investment, and deletion of the Mup gene family leads to fat accumulation and weight gain in males. We show that deleting Mup genes also alters the gut microbiota of male, but not female, mice in terms of both taxonomic and functional compositions. Male mice without Mup genes harbored fewer gut bacterial families and reduced abundance of a species of Ruminococcaceae , a family that has been previously shown to reduce obesity risk. Studying the impact of the Mup gene family on the gut microbiota has the potential to reveal the ways in which these genes affect host phenotypes., Competing Interests: The authors declare no conflict of interest.

Summary: Endothelial nitric oxide synthase (eNOS)‐derived nitric oxide (NO) plays an important role, not only in endothelium‐dependent vasodilation but also in lipid and glucose homeostasis in the liver and exerts beneficial effects on mitochondrial biogenesis and respiration. Thus, the aim of our study was to use iTRAQ‐based quantitative proteomics to investigate the changes in protein expression in the mitochondrial and cytosolic fractions isolated from the liver of the double (apolipoprotein E (apoE) and eNOS) knockout (apoE/eNOS‐DKO) mice as compared to apoE KO mice (apoE−/−) – an animal model of atherosclerosis and hepatic steatosis. Collectively, the deficiency of eNOS resulted in increased expression of proteins related to gluconeogenesis, fatty acids and cholesterol biosynthesis as well as the decreased expression of proteins participated in triglyceride breakdown, cholesterol transport, protein transcription & translation and processing in endoplasmic reticulum (ER). Moreover, one of the most downregulated proteins were major urinary proteins (MUPs), which are abundantly expressed in the liver and were shown to be involved in the regulation of lipid and glucose metabolism. The exact functional consequences of the revealed alterations require further investigation. [ABSTRACT FROM AUTHOR]

House mice (Mus musculus) produce a variable number of major urinary proteins (MUPs), and studies suggest that each individual produces a unique MUP profile that provides a distinctive odor signature controlling individual and kin recognition. This ‘barcode hypothesis’ requires that MUP urinary profiles show high individual variability within populations and also high individual consistency over time, but tests of these assumptions are lacking. We analyzed urinary MUP profiles of 66 wild-caught house mice from eight populations using isoelectric focusing. We found that MUP profiles of wild male house mice are not individually unique, and though they were highly variable, closer inspection revealed that the variation strongly depended on MUP band type. The prominent (‘major) bands were surprisingly homogenous (and hence most MUPs are not polymorphic), but we also found inconspicuous (‘minor’) bands that were highly variable and therefore potential candidates for individual fingerprints. We also examined changes in urinary MUP profiles of 58 males over time (from 6 to 24 weeks of age), and found that individual MUP profiles and MUP concentration were surprisingly dynamic, and showed significant changes after puberty and during adulthood. Contrary to what we expected, however, the minor bands were the most variable over time, thus no good candidates for individual fingerprints. Although MUP profiles do not provide individual fingerprints, we found that MUP profiles were more similar among siblings than non-kin despite considerable fluctuation. Our findings show that MUP profiles are not highly stable over time, they do not show strong individual clustering, and thus challenge the barcode hypothesis. Within-individual dynamics of MUP profiles indicate a different function of MUPs in individual recognition than previously assumed and advocate an alternative hypothesis (‘dynamic changes’ hypothesis).

A new bio-sensing platform based on major urinary proteins (MUPs) from the mouse as chemical recognition elements has been developed. The transducers were surface acoustic devices coated with diamond nanoparticles as an intermediate layer enabling covalent attachment of the proteins. The resulting sensors detected 2,4-Dinitrotoluene, 4-Nitrotoluene, and 2-Isobutyl-3-methoxypyrazine at ppb levels. The best sensor showed a sensitivity of 24000 \text Hz\cdot \text ppm^-1 to 2, 4-DNT when grafted with the protein MUP20. Trends in the sensitivity of the various VOC sensors were compared with the association constant values Ka of the proteins to target ligands measured by competitive assay in liquid phase. The system is able to detect analytes both in liquid as well as vapor phase and indicate that MUPs are robust bio-recognition elements that can be utilized in artificial olfaction applications. [ABSTRACT FROM PUBLISHER]

Social interactions are critical for reproduction in many animals. Since several pathogens are transmitted by social contact, females searching for mating partners should select males that can signal being healthy. Not all signals, however, may be reliable, since males from a number of species can overcome behavioural symptoms of infection when mating opportunities are available. Here, we manipulated sickness status of male house mice, Mus musculus domesticus, by administering an immune challenge (lipopolysaccharide, LPS) and studied the consequences of this manipulation for two signals that function in mate attraction in this species: ultrasonic vocalizations and darcin (a urinary protein). Additionally, we quantified female visits to immune-challenged and control males, and the males' plasma testosterone levels. LPS-injected males had lower darcin and lower regular ultrasonic syllable production than control-injected males, while producing a larger number of high-frequency ultrasonic syllables. We conclude that immune-challenged male mice presented with a receptive female cannot maintain the production of sexually attractive signals. Females might use some of these cues when making mating decisions, since they spent significantly less time near LPS-injected males. Testosterone was reduced in LPS-injected males and could be a unifying mechanism downregulating both of the traits quantified. Darcin and ultrasonic vocalizations produced in the context of courtship may therefore function as reliable indicators of current health status. [ABSTRACT FROM AUTHOR]

The Major Urinary Proteins (MUPs) of the house mouse, Mus musculus domesticus , are 18–19 kDa beta-barrel lipocalins that are involved in chemical communication between individuals. Many of them are excreted in urine where they play multiple roles, including coding of owner identity and transport, and slow release of bound volatile pheromones. One of them, darcin, is a pheromone in its own right and induces long-term memory for the identity and location of the scent mark owner. We have shown that mass spectrometric analysis of intact proteins, and their ion mobility behaviour, is capable of dissecting subtle structural differences between the members of this class of proteins. Moreover, mass spectrometric analysis of the intact proteins can contribute towards molecular phenotyping of MUPs. However, whilst allowing relative quantification, the ionisation propensity or gas phase properties of the individual MUPs may compromise absolute quantification. To solve the challenge of absolute quantification of MUP expression, we have designed and constructed a QconCAT built from endopeptidase LysC peptides that is capable of quantifying MUPs found in laboratory animal strains and some MUPs from wild caught individuals. [ABSTRACT FROM AUTHOR]

Major urinary proteins (MUPs) have been proven to be non-volatile male pheromones in mice. Here, we aimed to elucidate the relationship between MUPs and dominance hierarchy, and the underlying molecular mechanisms. Dominance-submission relationship was established by chronic dyadic encountering. We found that at the urinary protein level and hepatic mRNA level, the expression of major MUPs, including Mup20, was enhanced in dominant males compared with subordinate males, indicating that MUPs might signal the social status of male mice. Meanwhile, the mRNA level of hepatic corticotropin releasing hormone receptor 2 (CRHR2) was higher in subordinate male mice than in dominant male mice. Castration also enhanced the expression of CRHR2, but suppressed that of MUPs. CRHR2 agonist treatment reduced the expression of MUPs in liver. However, male social status failed to exert significant influence on serum testosterone and corticosterone as well as the mRNA expression of their receptors. These findings reveal that some MUPs, especially Mup20, might constitute potential dominance pheromones and could be downregulated by hepatic CRHR2, which is possibly independent of androgen or corticosterone systems. [ABSTRACT FROM AUTHOR]

This article is part of a Special Issue “Chemosignals and Reproduction”. This paper reviews the role of chemosignals in the socio-sexual interactions of female mice, and reports two experiments testing the role of pup-derived chemosignals and the male sexual pheromone darcin in inducing and promoting maternal aggression. Female mice are attracted to urine-borne male pheromones. Volatile and non-volatile urine fractions have been proposed to contain olfactory and vomeronasal pheromones. In particular, the male-specific major urinary protein (MUP) MUP20, darcin, has been shown to be rewarding and attractive to females. Non-urinary male chemosignals, such as the lacrimal protein ESP1, promote lordosis in female mice, but its attractive properties are still to be tested. There is evidence indicating that ESP1 and MUPs are detected by vomeronasal type 2 receptors (V2R). When a female mouse becomes pregnant, she undergoes dramatic changes in her physiology and behaviour. She builds a nest for her pups and takes care of them. Dams also defend the nest against conspecific intruders, attacking especially gonadally intact males. Maternal behaviour is dependent on a functional olfactory system, thus suggesting a role of chemosignals in the development of maternal behaviour. Our first experiment demonstrates, however, that pup chemosignals are not sufficient to induce maternal aggression in virgin females. In addition, it is known that vomeronasal stimuli are needed for maternal aggression. Since MUPs (and other molecules) are able to promote intermale aggression, in our second experiment we test if the attractive MUP darcin also promotes attacks on castrated male intruders by lactating dams. Our findings demonstrate that the same chemosignal, darcin, promotes attraction or aggression according to female reproductive state. [ABSTRACT FROM AUTHOR]

Odors of predators are often co-opted by prey species to serve as warning signals. Perceptual properties of such kairomonal communication are under studied despite their common use in many mammals. We demonstrate that the kairomonal response in mice to rat odors varies monotonically with the volume of rat odor. Moreover, the ability of mice to differentiate between two strengths of rat odors is dependent on the ratio of the two concentrations. These results show that mice can compare kairomonal strength over a large range of values, and that kairomonal communication follows Weber’s law.

Odors of predators are often co-opted by prey species to serve as warning signals. Perceptual properties of such kairomonal communication are under studied despite their common use in many mammals. We demonstrate that the kairomonal response in mice to rat odors varies monotonically with the volume of rat odor. Moreover, the ability of mice to differentiate between two strengths of rat odors is dependent on the ratio of the two concentrations. These results show that mice can compare kairomonal strength over a large range of values, and that kairomonal communication follows Weber’s law.

Within a species, sharing of data about identity, sex, health and hormonal status or feeding resources confers an advantage for survival and is actively pursued by linking signalling molecules to specific behavioural or neurohormonal responses. The proper identification of the signals (morphology), their correct use (grammar) and their meaning (semantics) allow us to understand the link between signals and responses. In mice, Mus musculus , the identification of meaningful molecules has revealed that both small airborne molecules and custom-tailored proteins are involved in chemical signalling. Among them, the major urinary proteins (MUPs) are barrel-like lipocalins excreted in urine. They bind and transport volatile molecules that may have different meanings, yet MUPs participate in transmitting different pieces of information. Therefore, they are not a simple blend of molecules but a communication system with its own rules to produce, transmit and process information. These actions affect both the physiology and the behaviour of sender and receiver. In fact, functional, behavioural and anatomical specializations allow production and emission of chemosignals by the sender, and proper signal detection and response management by the receiver. Moreover, the response to chemosignals may vary in time, according to internal and external conditions. The mechanism of biological chemical signalling is so efficient and versatile that MUPs are now used as molecular traps to develop biomimetic chemical sensors. [ABSTRACT FROM AUTHOR]

Mammalian pheromones control a myriad of innate social behaviors and acutely regulate hormone levels. Responses to pheromones are highly robust, reproducible, and stereotyped and likely involve developmentally predetermined neural circuits. Here, I review several facets of pheromone transduction in mammals, including ( a) chemosensory receptors and signaling components of the main olfactory epithelium and vomeronasal organ involved in pheromone detection; ( b) pheromone-activated neural circuits subject to sex-specific and state-dependent modulation; and ( c) the striking chemical diversity of mammalian pheromones, which range from small, volatile molecules and sulfated steroids to large families of proteins. Finally, I review ( d) molecular mechanisms underlying various behavioral and endocrine responses, including modulation of puberty and estrous; control of reproduction, aggression, suckling, and parental behaviors; individual recognition; and distinguishing of own species from predators, competitors, and prey. Deconstruction of pheromone transduction mechanisms provides a critical foundation for understanding how odor response pathways generate instinctive behaviors. [ABSTRACT FROM AUTHOR]

Odour signals used in competitive and aggressive interactions between males are well studied in the context of sexual selection. By contrast, relatively little is known about comparable signals used by females, despite current interest in the evolution of female ornaments and weaponry. Available evidence suggests that odour signals are important in competitive interactions between female mammals, with reductions or reversals of male-biased sexual dimorphism in signalling where female competition is intense. Scent marking is often associated with conflict between females over access to resources or reproductive opportunities. Female scent marks may therefore provide reliable signals of competitive ability that could be used both by competitors and potential mates. Consistent with this hypothesis, we report that aggressive behaviour of female house mice is correlated with the amount of major urinary protein (MUP) excreted in their urine, a polymorphic set of proteins that are used in scent mark signalling. Under semi-natural conditions, females with high MUP output are more likely to produce offspring sired by males that have high reproductive success, and less likely to produce offspring by multiple different sires, suggesting that females with strong MUP signals are monopolized by males of particularly high quality. We conclude that odour signals are worthy of more detailed investigation as mediators of female competition. [ABSTRACT FROM AUTHOR]

Typically, female rats demonstrate clear mate choice. Mate preference is driven by the evolutionary need to choose males with heritable parasite resistance and to prevent the transmission of contagious diseases during mating. Thus, females detect and avoid parasitized males. Over evolutionary time scales, parasite-free males plausibly evolve to advertise their status. This arrangement between males and females is obviously detrimental to parasites, especially for sexually transmitted parasites. Yet Toxoplasma gondli, a sexually transmitted parasite, gets around this obstacle by manipulating mate choice of uninfected females. Males infected with this parasite become more attractive to uninfected females. The ability of T. gondiito not only advantageously alter the behavior and physiology of its host but also secondarily alter the behavior of uninfected females presents a striking example of the extended phenotype' of parasites. Toxoplasma gondli also abolishes the innate fear response of rats to cat odor; this likely increases parasite transmission through the trophic route. It is plausible that these two manipulations are not two distinct phenotypes, but are rather part of a single pattern built around testosterone-mediated interplay between mate choice, parasitism and predation. [ABSTRACT FROM AUTHOR]

Vomeronasal stem cells are generated throughout the life of a mouse and differentiate into neurons that express one vomeronasal type 1 (V1r), one or two vomeronasal type 2 (V2r), or one olfactory receptor. Vomeronasal stem cells can be induced to differentiate into neurons by treatment with lipocalins from mouse urine or by epigenetic modification following treatment with histone deacetylase inhibitors. An important question is, do chemosensory signals, modify the detection capabilities of the vomeronasal organ and affect behaviour. Rearing mice in the presence of urine (and its pheromonal signals) derived from a different mouse strain, affected the behavioural preference for non-kin which were accompanied by changes in vomeronasal receptor expression. Significant changes in the expression of vomeronasal V1r, V2r and olfactory receptors, major urinary proteins, and a number of genes thought to be involved in transcriptional regulation were also observed following urine treatment. These results suggest that modification of a mouse's urinary environment may exert epigenetic effects on developing vomeronasal neurons, which modify the type of vomeronasal receptors that are expressed. This may provide a mechanism by which environmental changes are able to modify the detection capabilities of the vomeronasal organ to respond optimally to the most likely social environment that a mouse will encounter when mature. [ABSTRACT FROM AUTHOR]

Chemosensory information mediates behavior in many rodent genera. Major Urinary Proteins (MUPs) facilitate chemical communication in some species of mice. We sought to demonstrate the importance of MUPs in chemosignaling across a range of rodent genera that live in different habitats and social structures. We analyzed urine from three subterranean rodent genera from different continents, and with diverse social systems: eusocial Zambian mole-rats ( Fukomys), solitary Israeli blind mole rats ( Spalax), and social Chilean coruros ( Spalacopus). 2D gel electrophoresis revealed low levels of protein, with sequences similar to aphrodisin, in Fukomys mole-rat urine, but no MUPs in urine of any of the studied species. Previous research demonstrated that subjects from the tested genera responded differentially to odors indicating transmission of individuality, family/colony or population, species, and reproductive state in secretions and excretions of conspecifics. This extends, to subterranean rodents, the evidence that rodent species can successfully transmit and receive chemosignals without the necessity of MUPs. [ABSTRACT FROM AUTHOR]

Background Somatostatin inhibits gall bladder contraction. Impaired gall bladder emptying is associated with gall bladder stone formation. The incidence of cholecystolithiasis is high in patients treated with a somatostatin agonist octreotide, which predominantly interacts with somatostatin receptor subtype 2 (SSTR2). Therefore, it is believed that SSTR2 regulates gall bladder contraction; however, evidence has not been provided. Here, we evaluate the effects of SSTR1-SSTR5-selective agonists on egg yolk-induced gall bladder contraction in mice. Methods Homozygous deletion of SSTR2 and SSTR5 was generated by cross-mating of SSTR2−/− with SSTR5−/− mice. Mice of different genotypes were injected with SSTR1-5-selective agonists or octreotide 15 min before induction of gall bladder emptying by egg yolk. One hour later, gall bladders were removed and weighed. Key Results Egg yolk-reduced gall bladder weights in all mice, irrespective of their genotype. Octreotide was the most potent inhibitor of gall bladder emptying in wild-type mice. In contrast, agonists with high selectivity for SSTR2 or SSTR5 inhibited gall bladder emptying by approximately 50–60%, whereas SSTR1-, SSTR3- and SSTR4-selective agonists failed to influence gall bladder contraction. In SSTR2−/− mice, octreotide and an SSTR5-selective agonist inhibited gall bladder emptying by approximately 50%, whereas SSTR2-selective agonists were inactive. Octreotide inhibited gall bladder emptying in SSTR5−/− mice by approximately 50%, without any effect in SSTR2−/− /SSTR5−/− mice. Conclusions & Inferences Our study provides evidence for the role of SSTR2 and SSTR5 in regulating gall bladder emptying in mice. [ABSTRACT FROM AUTHOR]

We investigated the specific pattern of major urinary proteins (MUPs) expression in 3-, 4-, and 12-week old mice of CBA/LacY and C57BL/6JY inbred strains using polyacrylamide gel electrophoresis. Quantitative evaluation of 8 protein fractions A-H with regard to sex, age, and genotype of the animals is presented for the first time. Actual problems of genetic control and neuroendocrine regulation of MUPs expression during ontogenesis are discussed. In the light of current views on MUPs as a key component in intrapopulation information exchange via pheromones, we put forward the idea that the genetically determined structure of the olfactory code of the definitive type is formed at an early ontogenetic stage on the basis of the MUPs combinatorial pattern. [ABSTRACT FROM AUTHOR]

Individual recognition is an important component of behaviors, such as mate choice and maternal bonding that are vital for reproductive success. This article highlights recent developments in our understanding of the chemosensory cues and the neural pathways involved in individuality discrimination in rodents. There appear to be several types of chemosensory signal of individuality that are influenced by the highly polymorphic families of major histocompatibility complex (MHC) proteins or major urinary proteins (MUPs). Both have the capability of binding small molecules and may influence the individual profile of these chemosignals in biological fluids such as urine, skin secretions, or saliva. Moreover, these proteins, or peptides associated with them, can be taken up into the vomeronasal organ (VNO) where they can potentially interact directly with the vomeronasal receptors. This is particularly interesting given the expression of major histocompatibility complex Ib proteins by the V2R class of vomeronasal receptor and the highly selective responses of accessory olfactory bulb (AOB) mitral cells to strain identity. These findings are consistent with the role of the vomeronasal system in mediating individual discrimination that allows mate recognition in the context of the pregnancy block effect. This is hypothesized to involve a selective increase in the inhibitory control of mitral cells in the accessory olfactory bulb at the first level of processing of the vomeronasal stimulus. [Copyright &y& Elsevier]

Mouse major urinary proteins (MUPs) have been proposed to play a role in regulating the release and capture of pheromones. Here, we report affinity measurements of five recombinant urinary MUP isoforms (MUPs-I, II, VII, VIII, and IX) and one recombinant nasal isoform (MUP-IV) for each of three pheromonal ligands, (±)-2- sec-butyl-4,5-dihydrothiazole (SBT), 6-hydroxy-6-methyl-3-heptanone (HMH), and (±)dehydro- exo-brevicomin (DHB). Dissociation constants for all MUP-pheromone pairs were determined by isothermal titration calorimetry, and data for SBT were corroborated by measurements of intrinsic protein fluorescence. We also report the isolation of MUP-IV protein from mouse nasal extracts, in which MUP-IV mRNA has been observed previously. The affinity of each MUP isoform for SBT (Kd ∼ 0.04 to 0.9 μM) is higher than that for DHB (Kd ∼ 26 to 58 μM), which in turn is higher than that for HMH (Kd ∼ 50 to 200 μM). Isoforms I, II, VIII, and IX show very similar affinities for each of the ligands. MUP-VII has approximately twofold higher affinity for SBT but approximately twofold lower affinity for the other pheromones, whereas MUP-IV has ∼23-fold higher affinity for SBT and approximately fourfold lower affinity for the other pheromones. The variations in ligand affinities of the MUP isoforms are consistent with structural differences in the binding cavities of the isoforms. The data indicate that the concentrations of available pheromones in urine may be influenced by changes in the expression levels of urinary MUPs or the excretion levels of other MUP ligands. The variation in pheromone affinities of the urinary MUP isoforms provides only limited support for the proposal that MUP heterogeneity plays a role in regulating profiles of available pheromones. However, the binding data support the proposed role of nasal MUPs in sequestering pheromones and possibly transporting them to their receptors. [ABSTRACT FROM AUTHOR]

Mouse urine contains an abundance of major urinary proteins, lipocalins, whose roles include slow release of semiochemicals. These proteins are highly polymorphic, with small sequence differences between individual members. In this study, we purified to homogeneity four of these proteins from two strains of inbred mice and characterized them by mass spectrometry. This analysis has led to the discovery of another variant in this group of proteins. Three of the polymorphic variants that map to the surface have no effect on the binding of a fluorescent probe in the binding cavity, but the fourth, characterized by a Phe to Val substitution in the cavity, shows a substantially lower affinity and fluorescence yield for the probe. These results are interpreted in light of the known crystal structure of the protein and molecular modeling calculations, which rationalize the experimental findings. This work raises the possibility that the calyx-binding site can show specificity for different ligands, the implications of which on pheromone binding and chemical communication are discussed. [ABSTRACT FROM AUTHOR]

Stimulation of estrus in adult female mice was obtained with major urinary proteins (MUPs) with the natural volatile ligands bound. The MUP threshold concentration for this effect was about 1.8 mg/ml. MUPs without the ligands bound, as purified by organic extraction of hydrophobic compounds, stimulated estrus in mice only when dissolved in carrier urine of juvenile or castrated adult male mouse or ovariectomized female mouse. They did not stimulate estrus when dissolved in water. Mice that had the vomeronasal organ removed were insensitive to MUPs. It is concluded that MUPs are an integral part of the mouse male pheromones that stimulate hormonal activity in females and that the vomeronasal system is involved in the estrus-stimulating effect of the major urinary proteins. [ABSTRACT FROM AUTHOR]

The genome of the laboratory mouse contains about 35 major urinary protein (MUP) genes, many of which are clustered on chromosome 4. We have used distance and parsimony methods to estimate phylogenetic relationships between MUP genes from nucleotide sequence and restriction maps. By analyzing coding sequences we show that the genes fall into four main groups of related sequences (groups 1-4). Comparisons of restriction maps and the nucleotide sequences of hypervariable regions that lie 50 nucleotides 5′ to the cap sites show that the group 1 genes and probably also the group 2 pseudogenes fall into subgroups. The most parsimonious trees are consistent with the evolution of the array of group 1 and 2 genes by mutation accompanied by a process tending toward homogenization such as unequal crossing-over or gene conversion. The phylogenetic grouping correlates with grouping according to aspects of function. The genomes of the inbred strains BALB/c and C57BL contain different MUP gene arrays that we take to be samples from the wild population of arrays. [ABSTRACT FROM AUTHOR]