首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 78 毫秒
1.
Thirty-five deer mice, Peromyscus maniculatus, were trapped on Gannet Cluster 2 (GC-2), one of a group of islands numbered by convention in the Gannet Island Archipelago, and examined for ectoparasites. One species each of Acari (Ixodes uriae) and Siphonaptera (Orchopeas leucopus) were recovered. Samples of mice favored males to females (3.4∶1). Twenty-nine percent (10) of the mice were free of ectoparasites. Males were more heavily parasitized than females when both parasites were considered. No ticks were recovered from the female mice, while the males that were parasitized carried adult Ixodes uriae. These 2 ectoparasites parasitizing P. maniculatus, which is a known reservoir host for Lyme disease (Borrelia burgdorferi), may carry B. garinii and their presence would have serious implications for the spread of this human pathogen northward in continental North America.  相似文献   

2.
Scent marking can provide behavioral and physiological information including territory ownership and mate advertisement. It is unknown how mating status and pair cohabitation influence marking by males from different social systems. We compared the highly territorial and monogamous California mouse (Peromyscus californicus) to the less territorial and promiscuous white-footed mouse (P. leucopus). Single and mated males of both species were assigned to one of the following arenas lined with filter paper: control (unscented arena), male scented (previously scent-marked by a male conspecific), or females present (containing females in small cages). As expected, the territorial P. californicus scent marked and overmarked an unfamiliar male conspecific's scent marks more frequently than P. leucopus. Species differences in responses to novel females were also found based on mating status. The presence of unfamiliar females failed to induce changes in scent marking in pair bonded P. californicus even though virgin males increased marking behavior. Pair bonding appears to reduce male advertisement for novel females. This is in contrast to P. leucopus males that continue to advertise regardless of mating status. Our data suggest that communication through scent-marking can diverge significantly between species based on mating system and that there are physiological mechanisms that can inhibit responsiveness of males to female cues.  相似文献   

3.
Cross-transmission experiments were done using sporulated oocysts of Eimeria arizonensis from Peromyscus truei and Peromyscus maniculatus, and oocysts of 2 putative species that resemble E. arizonensis, i.e., Eimeria albigulae from Neotoma albigula, and Eimeria onychomysis from Onychomys leucogaster. Oocysts of each species were inoculated into representatives of P. maniculatus and the latter 2 rodent species. Other experiments were conducted wherein oocysts of Eimeria langebarteli from Peromyscus leucopus were given to P. truei and P. maniculatus. Oocysts of E. arizonensis from P. truei and P. maniculatus could be transmitted only to P. maniculatus; likewise, oocysts of E. albigulae and E. onychomysis produced patent infections only in N. albigula and O. leucogaster, respectively. Oocysts of E. langebarteli from P. leucopus could be transmitted to P. truei, but not P. maniculatus. These results indicate that E. arizonensis, and the morphologically similar E. albigulae and E. onychomysis, are distinct species that are not transmissible between the genera of their respective hosts (Peromyscus, Neotoma, Onychomys), and that some isolates of E. langebarteli, reported from 6 species of Peromyscus and Reithrodontomys megalotis, may not always be infective to P. maniculatus.  相似文献   

4.
Whether a high-unsaturated-fat, high-protein (HFP), and low-carbohydrate (CHO) diet during gestation has long-lasting beneficial effects on lipid metabolism in the offspring was investigated using a mouse model. Female mice were fed either a standard (CHO rich) chow diet or a CHO HFP diet, before and during gestation and lactation. All offspring were weaned onto the same chow until adulthood. Although liver cholesterol concentration and fasting plasma triglyceride (TG), cholesterol, and free fatty acid concentrations were not affected in either male or female HFP offspring, hepatic TG concentration was reduced by approximately 51% (P < 0.05) in the female adult offspring from dams on the HFP diet, compared with females from dams on the chow diet (a trend toward reduced TG concentration was also observed in the male). Furthermore, hepatic protein levels for CD36, carnitine palmitoyltransferase-1 (CPT-1), and peroxisomal proliferator activated receptor-alpha (PPAR-alpha) were increased by approximately 46% (P < 0.001), approximately 52% (P < 0.001), and approximately 14% (P = 0.035), respectively, in the female HFP offspring. Liver TG levels were negatively correlated with protein levels of CD 36 (r = -0.69, P = 0.007), CPT-1 (r = -0.55, P = 0.033), and PPAR-alpha (r = -0.57, P = 0.025) in these offspring. In conclusion, a maternal HFP diet during gestation and lactation reduces hepatic TG concentration in female offspring, which is linked with increased protein levels in fatty acid oxidation.  相似文献   

5.
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.  相似文献   

6.
We address the problem of the possible significance of biological speciation to the magnitude and pattern of divergence of asexually transmitted characters in bisexual species. The empirical data for this report consist of restriction endonuclease site variability in maternally transmitted mitochondrial DNA (mtDNA) isolated from 82 samples of Peromyscus polionotus and P. leucopus collected from major portions of the respective species' ranges. Data are analyzed together with previously published information on P. maniculatus, a sibling species to polionotus. Maps of restriction sites indicate that all of the variation observed can be reasonably attributed to base substitutions leading to loss or gain of particular recognition sites. Magnitude of mtDNA sequence divergence within polionotus (maximum approximately equal to 2%) is roughly comparable to that observed within any of five previously identified mtDNA assemblages in maniculatus. Sequence divergence within leucopus (maximum approximately equal to 4%) is somewhat greater than that within polionotus. Consideration of probable evolutionary links among mtDNA restriction site maps allowed estimation of matriarchal phylogenies within polionotus and leucopus. Clustering algorithms and qualitative Wagner procedures were used to generate phenograms and parsimony networks, respectively, for the between-species comparisons. Three simple graphical models are presented to illustrate some conceivable relationships of mtDNA differentiation to speciation. In theoretical case I, each of two reproductively defined species (A and B) is monophyletic in matriarchal genealogy; the common female ancestor of either species can either predate or postdate the speciation. In case II, neither species is monophyletic in matriarchal genotype. In case III, species B is monophyletic but forms a subclade within A which is thus paraphyletic with respect to B. The empirical results for mtDNA in maniculatus and polionotus appear to conform closely to case III. These theoretical and empirical considerations raise a number of questions about the general relationship of the speciation process to the evolution of uniparentally transmitted traits. Some of these considerations are presented, and it is suggested that the distribution patterns of mtDNA sequence variation within and among extant species should be of considerable relevance to the particular demographies of speciation.   相似文献   

7.
We examined the impact of season and habitat on Sin Nombre virus (SNV) seroprevalence in deer mice (Peromyscus maniculatus) in Utah's Great Basin Desert from May 2002 through summer 2003. Low mouse captures in 2002 limited analysis for that year. In two seasons during 2003, mouse density and sagebrush cover were positively linked (spring: r = 0.8, P = 0.01; summer: r = 0.8, P = 0.04). In the spring, seroprevalence was negatively correlated with density (r = -0.9, P< 0.01); male and female antibody prevalence did not differ; and scarring was unrelated to antibody status. In the summer, density and antibody prevalence were unrelated; male seroprevalence was higher (chi(2) = 3.6, P = 0.05); and seropositive mice had more scars (t = 2.5, P = 0.02). We speculate nesting behavior could maintain SNV over the winter, whereas summer territoriality could be responsible for transmission.  相似文献   

8.
Ectoparasites such as ixodid ticks that remain attached to hosts for several days while feeding on blood are able to overcome the inflammatory and immune responses of some hosts and not others. The immature stages of the deer tick Ixodes dammini are found more frequently on the white-footed mouse, Peromyscus leucopus, than on other rodents. We propose that P. leucopus is more tolerant to I. dammini than is a less common host, the meadow vole, Microtus pennsylvanicus. To test this hypothesis, the distribution patterns and engorgement indices were determined for larval and nymphal I. dammini collected from wild-caught P. leucopus and M. pennsylvanicus. There were more immature ticks, which were more fully engorged, on P. leucopus than on M. pennsylvanicus. There were more and better engorged ticks on male than on female hosts. Laboratory studies on the number and weights of larval I. dammini collected off naive and previously exposed P. leucopus and M. pennsylvanicus support the results of the field study. Fewer larval ticks were recovered from previously exposed M. pennsylvanicus than P. leucopus, and the ticks weighed less. Larval and nymphal ticks aggregated among hosts in the study grid, and higher densities per male P. leucopus were correlated with higher engorgement indices, suggesting that immature I. dammini feed better at higher densities. The feeding success of I. dammini on its preferred host species might be due to its adaptation to the immune and inflammatory reactions of the host.  相似文献   

9.
Boar taint is a major meat-quality defect in pigs and is due to excessive accumulation of skatole and androstenone in adipose tissue. The present work investigated the relationship between carcass weight, levels of skatole and androstenone in adipose tissue, and expression of the hepatic androstenone-metabolising enzyme 3β-hydroxysteroid dehydrogenase (3β-HSD), in 22 entire male and 22 entire female crossbred pigs (Large White (40%) × Landrace (40%) × Duroc (20%)). Animals of each gender were divided into two subgroups (11 pigs in each subgroup): (i) conventional weight (carcass weight 59 to 77 kg) and (ii) heavy weight (carcass weight 84 to 95 kg). No relationship between carcass weight and adipose tissue skatole level was found for entire male pigs (r2 = 0.013, P > 0.05). There was a significant negative relationship between carcass weight and expression of the hepatic 3β-HSD protein (r2 = 0.502, P < 0.001) and a significant negative relationship between 3β-HSD protein expression and androstenone level in adipose tissue (r2 = 0.24, P < 0.05) in entire males. No relationship was found between carcass weight and 3β-HSD protein expression in female pigs (r2 = 0.001, P > 0.05). 3β-HSD expression was 59% higher in conventional-weight male pigs when compared with heavy-weight animals (P < 0.05) and 36% higher in heavy-weight females when compared with heavy-weight males (P < 0.05). It is concluded that an increase in slaughter weight of entire commercial crossbred Large White pigs is accompanied by inhibition of expression of the hepatic 3β-HSD protein, which might result in a reduced rate of hepatic androstenone clearance with its subsequent accumulation in adipose tissue. It is suggested that regulation of pig hepatic 3β-HSD expression is under the control of sex hormones.  相似文献   

10.
Variation at 12 pure-repeat dinucleotide microsatellites from Peromyscus maniculatus was analyzed for samples of all species in the P. maniculatus species group and P. leucopus. Except for one locus (Pml08) that amplified a product only for P. maniculatus, these microsatellites yielded reliable estimates of variation across these species; per-locus polymorphism and allele-size distribution were not significantly different among or between any of the species sampled from mainland populations. Significantly lower levels of variation and the distribution of alleles in the two populations of the insular-endemic P. sejugis were consistent with the expectation of substantial founder effect and suggest a lack of recent gene flow between these populations. Phenetic analyses of genetic distances based on shared allele frequencies uniformly produced well-supported trees that were entirely concordant with the a priori corroborated relationships within the P. maniculatus species group; this result was not obtained with analyses of a genetic distance computed from differences in allele sizes. The microsatellite data do not support the hypothesis that P. sejugis should be considered conspecific with P. maniculatus but yield a strongly supported sister-group association between P. sejugis and P. keeni.  相似文献   

11.
Salivary gland proteins were studied in sandflies (Diptera: Psychodidae: Phlebotominae) by electrophoretic techniques. In Phlebotomus duboscqi Neveu-Lemaire the protein concentration was about 30 times higher in females than in males. SDS PAGE revealed eight major bands of 29-62 kDa in salivary gland extracts (SGE) from females, whereas only one band of 57kDa was detected in males. The number of protein components in SGE gradually increased with the age of females. In P. papatasi (Scopoli) the typical electrophoretic pattern was reached in 3-5 days after imago emergence, depending on the temperature at which females were maintained. All major protein components of the female SGE were present in the content of glands. Female SGE were compared in seven colonies of five Phlebotomus and Lutzomyia species; electrophoretic profiles distinguished between species and even between colonies of different geographical origin. In general, the highest variability of major protein components was observed in the 38-48kDa region. Four colonies of the subgenus Phlebotomus (P. duboscqi and P. papatasi) possessed common mobility polypeptides, the highest similarity was found between two colonies of P. papatasi. Other species tested significantly differed, specific prominent bands of 33, 35 and 38kDa were found in P. halepensis Theodor, P. perniciosus Newstead and Lutzomyia longipalpis (Lutz & Neiva), respectively. Glycoproteins in SGE of Lu. longipalpis and P. duboscqi females were identified and analysed using blotting with five lectin conjugates. Specific reaction of lectins ConA and WGA revealed the complex type of N-glycans in the 48 and 53-54kDa glycoproteins present in both species. Similar glycosylation was detected in species-specific bands of the 57-60 and 65-67 kDa in P. duboscqi and Lu. longipalpis, respectively. The high mannose type of glycosylation was found in the 20 and 39 kDa polypeptides of Lu. longipalpis and the 40-42 kDa polypeptides of P. duboscqi. Innate lectin activity specific for aminosugars was detected in SGE of P. duboscqi females using haemagglutination tests with rabbit erythrocytes.  相似文献   

12.
The relationships between anaerobic glycolysis and the average velocity (v) sustained during running were studied in 17 top level athletes (11 males and 6 females). A blood sample was obtained within 10 min of the completion of major competitions over 400 m, 800 m and 1500 m and the blood lactate concentration [la]b was measured. In both male and female athletes [la]b was related to the relative performance, as expressed as a percentage of the athlete's best v of the season. Over 400 m, r = 0.85 (P less than 0.01) and r = 0.80 (P less than 0.05) in males and females, respectively. Over 800 m, the corresponding values were r = 0.76 (P less than 0.01) and r = 0.91 (P less than 0.01). In male runners [la]b was correlated to v: r = 0.89 (P less than 0.01) and r = 0.71 (P less than 0.02) over 400 m and 800 m, respectively. No relationship to relative performance or v was obtained over 1500 m. Energy expenditure during competition running was estimated in male runners from the [la]b values. This estimate was based mainly on the assumption that a 1 mmol.1-1 increase in [la]b corresponded to the energy produced by the utilization of 3.30 ml.O kg-1. The energy cost of running was estimated, by dividing the estimated total energy expenditure by the race distance, at 0.211 ml.kg-1.min-1 over 800 m and 0.274 ml.kg-1.m-1 over 400 m.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   

13.
14.
Of 198 deermice (Peromyscus spp) collected from various localities in the southwestern United States and northern Mexico, 106 (54%) had eimerian oocysts in their feces when examined. These included 50 of 106 (47%) Peromyscus truei, 34 of 54 (63%) Peromyscus maniculatus, 4 of 17 (24%) Peromyscus leucopus, and 18 of 21 (86%) Peromyscus eremicus. The following Eimeria were identified from infected mice: Eimeria arizonensis and Eimeria langebarteli from P. truei; E. arizonensis, Eimeria peromysci, and Eimeria delicata from P. maniculatus; E. arizonensis and Eimeria lachrymalis n. sp. from P. eremicus; and E. langebarteli from P. leucopus. Of the 106 Peromyscus found positive for Eimeria, 97 (91.5%) harbored only a single eimerian species at the time of examination. Sporulated oocysts of E. lachrymalis n. sp. were ellipsoid, 27-35 X 17-21 (30.8 +/- 1.7 X 19.1-0.9) micron, possessed a smooth wall and one polar granule, but lacked a micropyle and an oocyst residuum. Sporocysts were teardrop-shaped, 9-13 X 6-10 (10.9 +/- 0.9 X 7.9 +/- 0.5) micron, and had a Stieda body and sporocyst residuum, but no substieda body. Prepatent periods in experimental infections were 3-6 days after inoculation (DAI) for E. arizonensis (hosts: P. eremicus, P. maniculatus, P. truei); 4-5 DAI for E. peromysci (host: P. maniculatus); 6-9 DAI for E. langebarteli (hosts: P. truei, P. leucopus); and 8-10 DAI for E. lachrymalis (host: P. eremicus). Patency in these infections lasted 6-11 days for E. arizonensis, 5-10 days for E. peromysci, 14-40+ days for E. langebarteli, and 19-50+ days for E. lachrymalis. Eimeria lachrymalis appears to produce occult infections in P. eremicus that can be reactivated upon inoculation of the host with E. arizonensis.  相似文献   

15.
We studied parental and infanticidal behavior in the field andlaboratory in two ecologically equivalent and sympatric congeners,white-footed mice, Peromyscus leucopus noveboracensis, and deermice,P. maniculatus nubiterrae. Despite their close phylogeneticrelationship and ecological similarity, various aspects of parentaland nesting behavior of the two species were significantly different.P. maniculatus males were more paternal than were P. leucopusmales in that they retrieved pups, nested with pregnant femalesand females with newborn pups, and formed longer associationswith females than did P. leucopus males. Thus, P. m. nubiterraeexhibited more pair-bonding (monogamous) characteristics thandid either P. leucopus or P. m. bairdi, as reported in otherstudies. The behavioral differences may represent the differentevolutionary history of the three subspecies. Infanticidal behavior,however, was similar in both species. Dispersing and unmatedmales killed strange pups placed in experimental test chambersin the field, whereas mated males did not kill pups within theirown home ranges. Resident females of both species were moreinfanticidal than were males, killing pups in 90% of the trials.The results support the sexual selection and resource competitionhypotheses for male and female infanticide, respectively. [BehavEcol 1991; 2: 38-45]  相似文献   

16.
Sex-related differences in lower urinary tract (LUT) activity responding to intravesical infusion of diluted acetic acid (A/A, pH 3.0) were investigated during cystometrograms in decerebrate unanesthetized mice. A/A produced a decrease of intercontraction intervals in both female and male animals, and the extent of the decrease in male mice was much less than in female mice [19 +/- 5% (P = 0.03) vs. 65 +/- 5% (P = 0.03); n = 6 for each], exhibiting a marked difference between the two groups in response to acid irritation of the LUT (P = 0.002). A/A reduced maximal voiding pressure (MVP) (19 +/- 4%, P = 0.03) but had no effect on pressure threshold for inducing voiding contraction (PT) (P = 0.56) in females, whereas A/A did not change MVP (P = 1.00) but increased PT (16 +/- 4%, P = 0.03) in males. A/A decreased bladder compliances of female and male mice in a similar fashion (44 +/- 10% vs. 24 +/- 7%, P = 0.03 for each). In male mice, A/A produced persistent dribbling of fluid after voiding contraction phase, which was virtually not seen in females. The present study demonstrates the differences between female and male mice in response to noxious stimulation in the LUT: the female bladder is more sensitive to the acid irritation, while the male urethra is more irritable to the noxious stimulus. Identification of mechanisms underlying sex-specific characteristics might be helpful for elucidating pathogenesis of painful bladder syndrome.  相似文献   

17.
A major isoenzyme of hepatic androsterone-sulfating sulfotransferase (AD-ST) was purified from adult female rats. The activity was purified 122-fold over that found in the cytosol and showed a single protein band with a subunit molecular mass of 30 kDa after sodium dodecyl sulfate polyacrylamide gel electrophoresis. The purified enzyme exhibited four isoelectric variants of subunits on denaturing isoelectrofocusing gels (pI = 5.8, 6.1, 6.7 and 7.2). Rabbit antiserum raised against the enzyme specifically detected AD-ST polypeptide in rat liver cytosol. Immunoblot analysis of liver cytosol from female and male rats at various ages showed good correlation between the levels of AD-ST activity and AD-ST polypeptide. Significant levels of AD-ST activity and polypeptide were detected in senescent male rats, though normal adult male rats have very low levels of AD-ST activity and protein. The relative content of the isoelectric variants of AD-ST were different in liver cytosol of weanling and adult females, indicating that age- and gender-related alterations of hepatic AD-ST activity are primarily determined by the levels of AD-ST polypeptide and the relative amounts of the four isoelectric variants of the enzyme.  相似文献   

18.
Mating, fertilization, implantation, prenatal mortality, fetal and placental size, and placental ultrastructure were studied in intraspecific and interspecific crosses involving Peromyscus maniculatus and P. polionotus. Failure to mate was a major factor in interspecific crosses and was much more pronounced in crosses between P. polionotus females and P. maniculatus males than in the reciprocal cross. Failure of implantation following mating, however, was more pronounced in crosses between P. maniculatus females and P. polionotus males. Failure of implanted embryos to survive to term was a factor in crosses between P. polionotus females and P. maniculatus males. Comparison of the placental labyrinth of conceptuses from intraspecific and interspecific crosses revealed no differences at the ultrastructural level. The relationship of these observations to the evolution of isolating mechanisms in mammals and to physiological aspects of the developing maternal-fetal relationship are discussed. A model of placental and fetal size inheritance is presented.  相似文献   

19.
Two systems are described for the collection of 24 h urine samples from the common marmoset (Callithrix jacchus). Using 84 adult animals, 1210 24-h samples were collected. Mean urinary excretion was 14.4 +/- 7.5 ml/24 h (n = 1210, mean +/- SD). No differences were observed between sexes (for 52 females, 24 h volume = 15.1 +/- 8.0 ml; for 32 males, 24 h volume = 12.5 +/- 6.0 ml). No significant differences were observed between pregnant and non-pregnant females with respect to 24 h urine volume, and bilateral gonadectomy did not influence subsequent urinary excretion in either sex. For 161 pairs of observations, the intake of drinking water (11.7 +/- 10.2 ml/24 h) and the volume of urine excreted (12.6 +/- 7.1 ml/24 h) showed a positive correlation (r = 0.406 d.f. 159, P less than 0.001: y = 0.558x + 4.247).  相似文献   

20.
The aim of this study was to investigate the relationship between cardiopulmonary fitness as indicated by maximal work rate (Wmax) production and aerobic capacities (WAT), body mass index (BMI) and heart rate reserve. A total of 60 sedentary subjects (30 males, 30 females, aged 18-25 years) were enrolled in the study. Each subject performed an incremental exercise test (15 W/min) to the limit of tolerance on an electromagnetically-braked cycle ergometer. There was a negative correlation between increased BMI to Wmax capacity per kilogram body weight in male (r=-0.846, P=0.0001) and in female (r=-0.896, P=0.0001) subjects. In addition, W(AT) for each kilogram body weight also negatively correlated with increased BMI in male (r=-0.870, P=0.0001) and in females (r=-0.807, P=0.0001). The heart rate reserve correlated negatively with increasing BMI: r=-0.699, P=0.0001 (males) and r=-0.655, P=0.0001 (females). The results of the present study have suggested that, due to the inverse correlation between BMI, Wmax capacity, aerobic fitness and heart rate reserve, it may be useful to consider BMI in establishing cardiopulmonary fitness in various subjects.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号