Food neophobia in wild and laboratory mice (Mus musculus domesticus)

In a conditioned taste aversion procedure we were specifically interested in the topic of food neophobia. Wild and laboratory mice were individually presented with a novel drink (0.1 % saccharin solution). Compared with the daily water consumption, the intake of this was lower. This decrease was greater:(1) in wild than in tame populations ; (2) in random-bred (Swiss-albinos) than in inbred (C57 B1/6, BALB/c) strains ; (3) in F₁-hybrids (either wild x tame or inbred x inbred) than in the parental strains.These results are discussed:(1) in terms of a selective pressure linked to man's fight against rodents, leading to increased neophobia in wild mice ; and (2) by stressing the heterosis an inbreeding depression effects, which suggest that food neophobia is a component of Darwinian fitness.     

Age and brood defence in male CRL:NMRI BR laboratory mice, Mus musculus domesticus

According to Lack's principle, older mice should invest more in their offspring than younger ones. I tested this principle with pairs of CRL:NMRI BR mice protecting their young against an intruder, an unfamiliar same-stock male or female. The intruder was presented within a small wire-mesh cage in an extension, a cage the same size as the pair's home cage. The dam, her mate and the young in the nest were present in all tests. Although both parents had full access to the intruder, only the male interacted with it. Young breeding pairs and young intruders were 6 months old, the old pairs and old intruders 12 months. Each breeding pair was tested with both young and old male intruders. Older males defended their pups more vigorously than younger ones. The old males showed a higher preference to stay near (to interact with) the opponent; they also showed more tail rattling and biting attempts than the young ones. This indicates that older males take greater risks in defending their offspring than younger males. Older intruders also elicited a stronger brood defence in older males and a weaker response in younger ones.     

Social and territorial behaviour of laboratory mice (Mus musculus L.) in small complex areas

Hierarchically organized colonies of five male Mus musculus of strain LACA/CFW were transferred to complex arenas of 1·3, 2·6, 3·8 or 5·2 m². Mice in the 1·3 m² areas subsequently had their living space increased by removal of a partition to 2·6, 3·8 or 5·2 m². Changes in dominance occurred in eight out of thirteen of the colonies; the dominant mouse occupied the majority of the floor area, but some subordinates formed small territories. The number of territories held by subordinates was greater in the larger areas. In colonies in which the living area was expaded, however, there was no increase in the number of territories formed.     

Factors affecting the recognition of territory boundaries by mice (Mus musculus)

Male mice of the LACA strain and from a wild stock were allowed to form territories in 180-cm² enclosures. The clues by which they recognized the position of the territory boundaries were investigated by moving various landmarks or reference objects. The information used was found to be primarily visual, close objects taking precedence over distant ones. Olfactory clues were also used but only when they did not conflict with the visual ones. Cover was found to be necessary for territory formation, but not for maintenance, and the size of the territory apparently influenced the aggressiveness of the mouse holding it.     

Sensory processes in the discrimination of pups by female mice (Mus musculus)

Maternal pup retrieval by house mice (Mus musculus) was studied in an investigation of sensory processes in the discrimination of ‘own’ from ‘alien’ pups. In a control condition, mothers were able to discriminate their own from alien young. This ability seemed to be based on olfactory cues, while visual and auditory cues did not seem to be involved. Furthermore, it is suggested that retrieval consists of: elicitation (probably mediated by auditory cues); location of the pup (auditory and olfactory cues); and recognition of the pup (initially olfactory cues, with subsequent gustatory and tactile cues).     

Ghrelin's quick inhibition of androgen-dependent behaviors of male house mice (Mus musculus)

Ghrelin is a peptide hormone released by the stomach that stimulates hunger. Ghrelin also suppresses reproductive physiology by inhibiting the HPG axis. However, to our knowledge, our results are the first to demonstrate ghrelin's quick suppression of sex-hormone-regulated behaviors. In experiment 1, 2 orexigenic i.p. ghrelin injections (0.165 mg/kg and 0.33 mg/kg) suppressed male courtship behavior (ultrasonic calling to a female) and intermale aggression (latency to attack a stimulus male) 20 min following administration. Experiment 2 (examining only the 0.33 mg/kg dose ) replicated ghrelin's suppression of ultrasonic calling and intermale aggression; however, a third behavior, preference for volatile female odors (20 min following administration), was not significantly inhibited. In experiment 2, ghrelin treatment did not affect general locomotor activity (distance traveled 20 min following injection) or seminal vesicle weight (measured 5 days after completing ghrelin injections). We hypothesize that ghrelin's quick suppression of male aggression and ultrasonic mating calls was mediated through its effects on the brain (rather than indirectly through inhibition of the HPG axis).     

Coevolution of Cryptosporidium tyzzeri and the house mouse (Mus musculus)

Two house mouse subspecies occur in Europe, eastern and northern Mus musculus musculus (Mmm) and western and southern Mus musculus domesticus (Mmd). A secondary hybrid zone occurs where their ranges meet, running from Scandinavia to the Black Sea. In this paper, we tested a hypothesis that the apicomplexan protozoan species Cryptosporidium tyzzeri has coevolved with the house mouse. More specifically, we assessed to what extent the evolution of this parasite mirrors divergence of the two subspecies. In order to test this hypothesis, we analysed sequence variation at five genes (ssrRNA, Cryptosporidium oocyst wall protein (COWP), thrombospondin-related adhesive protein of Cryptosporidium 1 (TRAP-C1), actin and gp60) in C. tyzzeri isolates from Mmd and Mmm sampled along a transect across the hybrid zone from the Czech Republic to Germany. Mmd samples were supplemented with mice from New Zealand. We found two distinct isolates of C. tyzzeri, each occurring exclusively in one of the mouse subspecies (C. tyzzeri-Mmm and C. tyzzeri-Mmd). In addition to genetic differentiation, oocysts of the C. tyzzeri-Mmd subtype (mean: 4.24 × 3.69 μm) were significantly smaller than oocysts of C. tyzzeri-Mmm (mean: 4.49 × 3.90 μm). Mmm and Mmd were susceptible to experimental infection with both C. tyzzeri subtypes; however, the subtypes were not infective for the rodent species Meriones unguiculatus, Mastomys coucha, Apodemus flavicollis or Cavia porcellus. Overall, our results support the hypothesis that C. tyzzeri is coevolving with Mmm and Mmd.     

Effects of litter size on the behaviour of lactating female mice (Mus musculus)

The behaviour of multiparous female C3H mice rearing different sized litters was examined using an observational time-sampling procedure. The results indicate that while animals rearing smaller litters spend more time in the nest, more time licking individual pups, and during most of lactation, more time nursing the litter, animals rearing larger litters spend more time eating and drinking. It is suggested that the observed differences in behaviour may be the outcome of the differential nutritional requirements arising from feeding litters of different sizes. However, in a second experiment providing food and water inside the nest, the differences in nest-attendance and nursing behaviour persisted, suggesting that some aversive factor such as fatigue or discomfort may also be involved.     

Ethological isolation between local populations of house mice (Mus musculus) based on olfaction

Some rodent populations are composed of demes which remain reproductively isolated within the major population. Territoriality has been advanced as a possible isolating mechanism. This research investigated the possible role of olfaction in the isolation of feral house mouse (Mus musculus) demes. When given a choice, male and female mice spent more time with the air-transported odours of members of their own deme than with those of neighbouring deme members. Tests with a fresh-air control showed that mice avoided the odours of members of an adjacent deme. In addition, more time was spent with urine and faeces odours of members of a mouse's own group than with those of the members of an adjacent deme. The production and detection of odorous substances may contribute to the autonomy and relative reproductive isolation of some local populations of mice.     

Relationships of maternal nesting to thermoregulatory nesting in house mice (Mus musculus) at warm and cold temperatures

Thermoregulatory and maternal nesting in Mus musculus (indexed as weight of cotton pulled into the cage) was measured at 5 C and 22 C on mice representing lines from a bidirectional selection experiment for nest size at room temperature. The effects of both selection and temperature were significant across the entire experiment. Nesting on the day of parturition correlated highly with thermoregulatory nesting, and with the number of offspring that survived to weaning, indicating a common genetic basis for maternal and thermoregulatory nesting and a direct correlation of these traits with Darwinian fitness. Amount of cotton used increased soon after mating and remained high with a large amount of variability until about 10 days after parturition, and then decreased sharply. The pattern of changes in nest size during pregnancy resembled changes in progesterone levels reported previously in the literature for mice, and contrasted with models of a smooth symmetric curve peaking at parturition.     

Cymbopogon schoenanthus (Ethkher) ameliorates cadmium induced toxicity in swiss albino mice

Cadmium is among the toxic and hazardous metal widely dispersed in the environment in high levels. Current studies have provided new insights into antioxidant properties of bioflavonoid which have emerged as probable therapeutic and nutraceutical agents. The present study is geared to investigate the possible role of Cymbopogon schoenanthus (L.) Spreng. (or Ethkher) on heavy metal cadmium (Cd) induced oxidative stress in mice. Mice were randomly divided into four groups and treated for 15 days as follows: group 1: normal control-treated (saline); group 2: Ethkher leaves extract-treated (100 mg/kg); group 3: cadmium chloride (CdCl₂) treated; group 4: CdCl₂ plus Ethkher leaves extract. The results showed a significant reduction in hemoglobin, RBC and hematocrit in cadmium-treated mice as compared to control. Exposure to Cd caused a significant increase in the number of white blood cells (P < 0.05) indicating the occurrence of systemic inflammation. The results of this study also revealed that the mice intoxicated with Cd showed a significant increase in bilirubin, aspartate aminotransferase (AST), alanine transaminase (ALT), alkaline phosphatase (ALP) and gamma-glutamyl transpeptidase (GGTP) activities. Cd intoxication leads to suppression in humoral immunity. However, pretreatment with Ethkher extract reversed almost all the abnormalities in the blood parameters showing noteworthy protection against cadmium induced toxicity in mice. The outcome of the present study revealed that the Ethkher possessed significant immunomodulatory activity and had a preventive effect on the hematological alterations in Cd intoxicated mice.     

Copper toxicity and copper tolerance in Enteromorphacompressa (L.) Grev.

The responses of ship-fouling and non-fouling isolates of Enteromorpha compressa (L.) Grev. have been compared in media containing copper at 0.0?9.6 μmol · dm^?3. The responses of each isolate were found to vary, according to the conditions of the original habitat. Thus ship-fouling E. compressa was found to be tolerant of copper concentrations up to 9.6 μmol · dm^?3 showing a maintenance of all of the physiological processes studied during the present research (cell viability, net photosynthesis, intracellular K⁺ and dimethylsulphoniopropionate content). Non-fouling plant material showed symptoms of copper toxicity at all levels of copper from 1.8 μmol · dm^?3 to 9.6 μmol · dm^?3. Copper tolerance in ship-fouling E. compressa appears to be genetically determined, since the progeny from ship-fouling plants are also tolerant to copper concentrations within the range 1.8 to 9.6 μmol · dm^?3. The rate of accumulation of copper in ship-fouling thalli is, however, almost identical to that of non-fouling thalli, suggesting that tolerance may be due primarily to internal detoxification, rather than an exclusion mechanism.     

Dynamics of Na+, K+, and Proline Accumulation in Salttreated Vigna sinensis (L) and Phaseolus aureus (L)

The dynamics of Na⁺, K⁺, and proline accumulation in various organs of non nodulated Vigna sinensis and Phaseolus aureus was followed during their acclimation to two levels of salinities for a period of 35 days and was correlated to the vegetative growth of the two species. The rate of Na⁺ and K⁺ absorption is at a maximum during the first 15 to 20 days of culture. K⁺ absorption is not completely inhibited even at 100 mM NaCl although the endogenous Na⁺ largely surpasses that of K⁺ in certain organs. Low salinity rather accelerates K⁺ absorption in both species. The relative growth rates (RGR) correlate with the rate of Na⁺ and K⁺ accumulation. At low salinity (10 mM NaCl), the RGR of V. sinensis is greater than that of P. aureus. However, at high salinity (100 mM NaCl) the RGR is the same for both species. The growth of the younger parts of the two species is not arrested by salt treatment. Very high accumulation of Na⁺ is avoided in organs with less vacuolated tissues. At no time does the endogenous K : Na ratio in these organs fall below 1.0. Certain organs, especially the roots, hypocotyls, and the lower parts of the stems are capable of storing large quantities of Na⁺. In V. sinensis, the accumulated Na⁺ and K⁺ are evenly distributed among the various organs while in P. aureus they are rather concentrated in the roots. External salinity creates water deficiency in the younger plant parts and as a consequence, proline accumulates especially in the youngest aerial organs - more in P. aureus than in V. sinensis. The accumulation of this amino acid in both the species is dependent on time and correlates directly, not only with the water deficit, but also with the K⁺ contents. In contrast, it does not seem to depend directly on the endogenous Na⁺ content. The relative salt tolerance of the two species and the possible role of K⁺, Na⁺ and proline in the osmotic adjustments of the two species under saline conditions are discussed.     

Effect of intranasal irrigation with zinc sulphate on male-induced oestrus in the wild mouse, Mus musculus domesticus

Adult males of the subtropical house sparrow (Passer domesticus) were subjected to continuous darkness (DD) or short days (8L:16D) after photostimulation (15L:9D) for 30 days. One group was retained on the long day (15L:9D) schedule. Another two groups of photosensitive birds were placed under DD or 8L:16D. The photostimulated birds under DD or 8L:16D showed testicular regression and the rate of regression was similar in both the treatments. The photosensitive birds, on the other hand, did not show any initiation in testicular growth and development in either of the treatments. Long day birds (15L:9D) maintained enlarged testes without regression (the onset of photorefractoriness) during the treatment period. These results conform with the external coincidence model, but could also be explained by a modified internal coincidence model.     

麻疯树鲨烯合酶基因SQS的克隆及生物信息学分析

以麻疯树(Jatropha curcas L.)总RNA为模板,根据已报道的鲨烯合酶基因序列设计简并引物,用RACE方法克隆得到麻疯树鲨烯合酶基因全长cDNA,命名为JcSQS。JcSQS全长1609 bp,包含1个1242 bp的开放阅读框,预测麻疯树鲨烯合酶基因编码的蛋白含有413个氨基酸。JcSQS具有鲨烯合酶类的保守结构域,JcSQS 蛋白与蓖麻、柿、木榄等植物中SQS基因编码的氨基酸序列具有高度同源性。这为研究麻疯树萜烯类物质的生物合成和调控机制奠定了基础。     

Morphometric variation in nearly unstudied populations of the most studied mammal: The non-commensal house mouse (Mus musculus domesticus) in the Near East and Northern Africa

The phenotypic consequences in the house mouse (Mus musculus domesticus) of the transition from an ordinary field-dwelling rodent to a species that is dependent on human populations was studied by investigating the morphometric variation of non-commensal populations of M. m. domesticus from Syria, Jordan, SW Iran, and Libya and comparing them with that of conspecific commensal populations from Eastern Turkey, Greece, and Bulgaria. Commensal populations of M. musculus musculus from the Czech Republic were used as an outgroup. About 849 adult specimens of M. musculus were analysed by multivariate procedures based on standard molar, skull and body measurements. As expected, there was considerable variation among the studied populations and a good correspondence between morphometric and geographic distances. The resulting morphometric tree was consistent with the hypothesis that the original radiation of M. m. domesticus took place somewhere in the Near East. Commensal populations of M. m. domesticus form a single derived branch. Specimens originating from four different sites in eastern Syria showed the greatest similarity to one another and possessed relatively bigger molars than the other studied populations. Commensal populations were characterised by longer tails when compared to non-commensal populations, which suggests an adaptation for living in a more three-dimensionally heterogeneous environment for commensal populations.     

Effects of resource distribution on activity and territory defence in house mice, Mus domesticus

How much an animal invests in defending a territory depends, in part, on the quality, quantity and distribution of resources, but do animals target their investment in defence within the territory according to the location of different resources? We examined whether wild-caught male and female house mice increased aggression towards intruders of the same or opposite sex when in areas containing their food/water or nest site. Pairs of resident mice were established in enclosures consisting of two areas. In split enclosures, food and water were in one area and a nest site in the other, while in clumped enclosures all resources were in one area with no resources in the other. Residents of both sexes were quicker to attack intruders, and were more aggressive, in areas containing resources than in an area containing no resources. There was no difference in aggression between areas containing food/water, a nest site or both. The effect of resources on territorial defence was due largely to changes in aggression against intruders of the opposite sex. Residents, especially males, attacked intruders of their own sex more than those of the opposite sex. This bias was much stronger when no resources were present, owing to low aggression against opposite-sex intruders in the absence of resources. There were no differences in intruder aggression, and the relative size of the intruder (heavier or lighter than the resident) had no effect on resident aggression. Residents also spent less time out of their nest in clumped enclosures owing to low activity in the nonresource area.     

Biochemical toxicity of hexachlorocyclohexane and its gamma-isomer in albino mice

Dietary hexachlorocyclohexane (HCH) and gamma-isomer of HCH produced significant increase in liver weights of mice. Elevated levels of alanine and aspartate aminotransferases and of alkaline phosphatase in the blood of these animals suggested hepatotoxicity. Hepatic soluble enzymes--aspartate aminotransferase and lactate dehydrogenase--were markedly lowered. Among the hepatic lysosomal enzymes, acid phosphatase and acid cathepsin were increased in the experimental animals. Hepatic glucose-6-phosphatase was lowered by HCH while aldolase activity was increased. Hydrolytic enzymes in small intestine, viz., disaccharidases, lipase, amylase, dipeptidase and phosphatases, were also affected by dietary HCH and gamma-HCH. The results suggested cellular toxicity in hepatocytes of HCH and gamma-HCH fed animals, and also interference in gastrointestinal absorption.