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PubMed2004

Salmonella isolates from wild birds and mammals in the Basque Country (Spain).

The authors investigated the prevalence of Salmonella spp. in 205 wild birds and mammals belonging to 45 species during the years 2001 and 2002 in the Basque Country (Spain). Salmonella was isolated from 16 (7.8%) animals. The prevalence was 8.5% (7/82) in birds, and 7.2% (9/123) in mammals. Nine serotypes, all of them belonging to the species Salmonella enterica, were identified: two isolates of Typhimurium (from 1/3 griffon vultures [Gyps fulvus], and 1/5 sparrowhawks [Accipiter nisus]); one of 6,14:z4, z23: (subsp. houtenae, 1/1 common kestrel [Falco tinnunculus]); one of Muenchen (1/1 captive Harris's hawk [Parabuteo unicinctus]); two of Enteritidis (1/5 tawny owls [Strix aluco], and 1/14 foxes [Vulpes vulpes]); one of Give, Newport and Umbilo and one untyped islolate (4/22 badgers [Meles meles]); two of Worthington and one of 38:IV:z35 (subsp. arizonae, 3/40 wild boars [Sus scrofa]); and three other untyped isolates (1/1 northern fulmar [Fulmarus glacialis], 1/11 buzzards [Buteo buteo], 1/4 genets [Genetta genetta]). Salmonella isolation was never associated with macroscopic or microscopic lesions. The results of this study confirm the importance of wildlife as a Salmonella reservoir and as a potential risk for humans and livestock.

Animals↗
PubMed2004

Resetting mechanism of central and peripheral circadian clocks in mammals.

Almost all organisms on earth exhibit diurnal rhythms in physiology and behavior under the control of autonomous time-measuring system called circadian clock. The circadian clock is generally reset by environmental time cues, such as light, in order to synchronize with the external 24-h cycles. In mammals, the core oscillator of the circadian clock is composed of transcription/translation-based negative feedback loops regulating the cyclic expression of a limited number of clock genes (such as Per, Cry, Bmal1, etc.) and hundreds of output genes in a well-concerted manner. The central clock controlling the behavioral rhythm is localized in the hypothalamic suprachiasmatic nucleus (SCN), and peripheral clocks are present in other various tissues. The phase of the central clock is amenable to ambient light signal captured by the visual rod-cone photoreceptors and non-visual melanopsin in the retina. These light signals are transmitted to the SCN through the retinohypothalamic tract, and transduced therein by mitogen-activated protein kinase and other signaling molecules to induce Per gene expression, which eventually elicits phase-dependent phase shifts of the clock. The central clock controls peripheral clocks directly and indirectly by virtue of neural, humoral, and other signals in a coordinated manner. The change in feeding time resets the peripheral clocks in a SCN-independent manner, possibly by food metabolites and body temperature rhythms. In this article, we will provide an overview of recent molecular and genetic studies on the resetting mechanism of the central and peripheral circadian clocks in mammals.

Animals↗
PubMed2001

Selective brain cooling in mammals and birds.

Artiodactyls and felids have a carotid rete that can cool the blood destined for the brain and consequently the brain itself if the cavernous sinus receives cool blood returning from the nose. This condition is usually fulfilled in resting and moderately hyperthermic animals. During severe exercise hyperthermia, however, the venous return from the nose bypasses the cavernous sinus so that brain cooling is suppressed. This is irreconcilable with the assumption that the purpose of selective brain cooling (SBC) is to protect the brain from thermal damage. Alternatively, SBC is seen as a mechanism engaging the thermoregulatory system in a water-saving economy mode in which evaporative heat loss is inhibited by the effects of SBC on brain temperature sensors. In nonhuman mammals that do not have a carotid rete, no evidence exists of whole-brain cooling. However, the surface of the cavernous sinus is in close contact with the base of the brain and is the likely source of unregulated regional cooling of the rostral brain stem in some species. In humans, the cortical regions next to the inner surface of the cranium are very likely to receive some regional cooling via the scalp-sinus pathway, and the rostral base of the brain can be cooled by conduction to the nearby respiratory tract; mechanisms capable of cooling the brain as a whole have not been found. Studies using conventional laboratory techniques suggest that SBC exists in birds and is determined by the physical conditions of heat transfer from the head to the environment instead of physiological control mechanisms. Thus except for species possessing a carotid rete, neither a coherent pattern of SBC nor a unifying concept of its biological significance in mammals and birds has evolved.

Adaptation, Physiological↗
PubMed1976

Panamanian forest mammals as carriers of Salmonella.

Enteric bacteria pathogenic to man were sought in a total of 974 forest mammals collected from a variety of sites in rural and jungle areas of Panamá. The highest incidence of infection among the mammals was observed during the Panamanian dry season, which normally extends from January through April. A minimum of 10 Salmonella serotypes including, three of the Arizona group and Ewardsiella tarda, was isolated. Opossums of the genera Philander, 11 of 54 (20.1%), and Didelphis, 12 of 102 (11.8%) demonstrated high infection rates. One sloth of the genus Choloepus and specimens of two genera of rodents also were infected to varying degrees: 1(11.1%) of 9 Choloepus, 8 (1.1%) of 704 Proechimys and 1 (16.7%) of 6 Diplomys.

Animals↗
PubMed1987

Lyme disease ecology in Wisconsin: distribution and host preferences of Ixodes dammini, and prevalence of antibody to Borrelia burgdorferi in small mammals.

Lyme disease recently has been recognized in Wisconsin. Trapping studies were conducted at four geographically separate and ecologically distinct regions in Wisconsin to elucidate the distribution and host preferences of Ixodes dammini on small and medium sized mammals, and the occurrence of antibodies to Borrelia burgdorferi in these wild mammals. Peak I. dammini larval activity occurred from June-September. Nymphs were most active from May-August. White-footed mice (Peromyscus leucopus) and chipmunks (Tamias striatus) were important hosts for immature ticks. Mean numbers of I. dammini per mouse were highest in regions of high prevalence of Lyme disease. Antibody to B. burgdorferi was detected in sera of 60/371 (16%) white-footed mice, 5/104 (5%) chipmunks, 3/5 (60%) gray squirrels (Sciurus carolinensis), 0/8 raccoons (procyon lotor), and 0/12 opossum (Didelphis virginiana); antibody prevalence correlated positively with I. dammini occurrence, and seropositive animals were not detected in areas where I. dammini were not found. Two of 15 recaptured P. leucopus had greater than or equal to 4-fold changes in antibody titer. B. burgdorferi was cultured from blood of a P. leucopus captured in west-central Wisconsin, and was observed by direct immunofluorescence in 9/23 (39%) I. dammini nymphs. In Wisconsin, I. dammini has increased in numbers and has significantly expanded its range since its first recognition in 1968.

Animals↗
PubMed1994

Modifications of a cholinesterase method for determination of erythrocyte cholinesterase activity in wild mammals.

A method to determine erythrocyte cholinesterase (ChE) activity was modified for use in wild mammals. Erythrocyte ChE of California voles (Microtus californicus) was primarily acetylcholinesterase (AChE), which was similar to the brain and unlike plasma which was primarily butyrylcholinesterase (BChE). Triplicate erythrocyte AChE analyses from individual animals of several species of wild rodents revealed a mean coefficient of variation of 8.7% (SD = 4.3%). Erythrocyte ChE activity of several wild mammals of California revealed that mule deer (Odocoileus hemionus) had the highest erythrocyte AChE activity (1,514.5 mU/ml) and dusky-footed woodrats (Neotoma fuscipes) had the lowest activity (524.3 mU/ml). No ChE activity was found in erythrocytes of several species of birds and fish.

Animals↗
PubMed1995

Prevalence of antibodies to Toxoplasma gondii in wild mammals of Missouri and east central Kansas: biologic and ecologic considerations of transmission.

Sera from 273 wild mammals from Missouri and Kansas (USA), collected between December 1974 and December 1987, were tested for the presence of antibodies to Toxoplasma gondii using the Sabin-Feldman dye test. Sixty-five (24%) had antibodies at titers of > or = 1:8, including 38 (66%) of 58 carnivores, 14 (15%) of 94 omnivores, 13 (11%) of 117 herbivores, and none of four insectivores. The prevalence of antibodies in mice (Mus musculus and Peromyscus spp.) and rats (Rattus norvegicus and Sigmodon hispidus) was low (3%), while medium sized herbivores such as squirrels (Sciurus spp.), rabbits (Sylvilagus floridanus), and muskrats (Ondatra zibethicus) had prevalences of about 18%. Red foxes (Vulpes fulva) and mink (Mustela vison) had the highest prevalence of antibodies with frequencies of 90 and 66%, respectively. In 32 attempts to isolate Toxoplasma gondii from wild mammals with positive (> or = 1:4) titers, only six (19%) were successful: a gray squirrel (Sciurus carolinensis), a beaver (Castor canadensis), an opossum (Didelphis marsupialis), a red fox and two mink. These findings are consistent with the hypothesis that the probability of infection with Toxoplasma gondii, and therefore prevalence of antibodies in wildlife, is greatest in carnivores.

Animals↗
PubMed1996

Antibodies to arthropod-borne encephalitis viruses in small mammals from southern Florida.

From 1987 through 1991, blood samples were collected from 10 species of small mammals in Indian River Country, Florida (USA). Sera from 1,347 animals were analyzed for hemagglutination-inhibition (HI) antibody to St. Louis encephalitis (SLE) and eastern equine encephalitis (EEE) viruses. Of these, 75 (5.6%) were positive for HI antibody to SLE virus and 121 (9.0%) were positive for EEE antibody. Sera from five mammalian species were tested for neutralizing (NT) antibody to SLE, EEE, Highlands J (HJ a member of the western equine encephalitis virus complex), or Everglades (EVE, a member of the Venezuelan equine encephalitis complex) viruses. By serum neutralization tests, 26 (46%) of 57 had SLE antibodies, 14 (24%) of 58 had EEE antibodies, two (3.2%) of 63 had HJ antibodies, and 9 (14%) of 63 had EVE antibodies. One Sigmodon hispidus and one Peromyscus gossypinus had NT antibodies both to EEE and HJ viruses. Blood samples from 512 mammals were tested for virus. Isolations of one EVE virus and two unidentified arenaviruses were made from P. gossypinus and one EVE virus isolate was made from a S. hispidus.

Animals↗
PubMed1975

Viruses other than arenaviruses from West African wild mammals. Factors affecting transmission to man and domestic animals.

At least thirty-seven different viruses have been isolated from wild mammals in West Africa since 1962. Some of these, including Lassa virus, are already known to cause serious human morbidity and mortality. Crimean haemorrhagic fever-Congo virus, Dugbe virus, Mokola virus, and a smallpox-like agent from a gerbil in Dahomey are briefly discussed. An account of social and ecologic factors affecting man, domestic animals, and their interaction with wild mammals is given.

Africa, Western↗
PubMedDate not supplied

[The genetic sequelae of irradiation in mammals (a review of the literature)].

The problem of hereditary effects of mammal exposure to ionizing radiation has a 95-year history but to date, no simple final solution has been available. Many papers on this problem specify the dependence of the hereditary effects on dose rate, regime, physical nature of radiation exposure, type, line and age of mammals that were studied. Over many years it was studied mainly as an aspect of hereditary radiation effects in progeny of one irradiated and the second non-irradiated parents. Recently due to the large-scale expansion of ionizing irradiation, it has turned out urgent to study hereditary radiation effects in progeny of both irradiated parents. However, the original studies on this problem are not numerous, and in the summarized articles, the problem practically had no specified presentation.

Animals↗
PubMed2000

Germ line transformation of mammals by pronuclear microinjection.

The most popular approach for generating transgenic mammals is the direct injection of transgenes into one pronucleus of a fertilized oocyte. In the past 15 years microinjection has been successfully applied in laboratory as well as in farm animals. The frequency of transgenic founders, although highly different between the species, is efficient enough to render this technique applicable to a wide range of mammals. The expression levels and patterns of a transgene are initially influenced by the construction of the transgene. However, the overall phenotype of a transgenic organism is influenced by several genetic and environmental factors. Due to the features of this technique not all of the genetic factors can be experimentally controlled by the scientist. In this article we will emphasize some peculiarities which have to be taken into account for the successful performance of transgenesis by pronuclear microinjection.

Animals↗
PubMed2001

[Genomic imprinting in mammals].

A review of the data on the mechanisms and effects of genomic imprinting, an epigenetic phenomenon regulating the development in placentate mammals, is presented. In contrast to the majority of gene loci with biallelic expression, the expression of imprinted loci is monoallelic. In humans and mice, more than 300 imprinted loci have been identified, in which maternal or paternal alleles may either be expressed or be found in a repressed state during ontogeny. Imprinting is established during gametogenesis, and the repression of an allele of the imprinted locus is determined by methylation of the key regulatory element of this allele. Both the maternal and paternal chromosome sets are required for normal development in mammals. This is why parthenogenesis and androgenesis in these animals are impossible in nature. As a result of differential gene expression of many imprinted loci, the balance of gene activity is established, which is necessary for normal proliferation and differentiation of various cell clones in embryogenesis. Many human developmental abnormalities and syndromes are determined by defective genomic imprinting. In particular, the loss of imprints, which is followed by the occurrence of biallelic expression of some imprinted loci, may cause malignant tumors.

Alleles↗
PubMedDate not supplied

Detection of pathogenic Leptospira spp. infections among mammals captured in the Peruvian Amazon basin region.

To identify potential zoonotic reservoirs of pathogenic leptospires in the Peruvian Amazon basin, wild mammals were trapped from July 1997 to December 1998 near the city of Iquitos. After extraction of nucleic acids from animal kidneys, DNA of pathogenic leptospires was identified by polymerase chain reaction (PCR) assays using one of two primer sets, one amplifying a region of the 23S rRNA gene, and the other amplifying a gene fragment specific for Leptospira spp (G1/G2 primers). Overall, 29% (40 of 136) of the mammals tested showed evidence of renal infection by Leptospira spp., including 20% (13 of 64) of the rodents, 39% (20 of 51) of the marsupials, and 35% (7 of 20) of the chiropterans (bats). Marsupials and chiropterans were implicated as more significant reservoir hosts of leptospires pathogenic to humans than previously recognized.

Animals↗
PubMed2001

[Comparative evaluation of the muscular coat of the esophagus from fish and mammals].

Light optic analysis revealed that morphological parameters of fish and mammals oesophageal parameters are conditioned functionally. Combination of respiratory and transport functions in anterior portion of digestive systems in fish determines insignificant length of the esophagus and developed muscular coat which excludes disorders of gas exchange. Heterodonteal dentition, pulmonary type of respiration and long esophagus of mammals provide factors that unable to prevent gas exchange. Electron microscopic study of oesophageal fibres of these animals demonstrated that they are alike in their structure with skeletal muscular fibres.

Animals↗
PubMed2001

[Somatic cloning in mammals].

Somatic cloning in mammals became possible due to refinement of the nuclear transfer technique consisting of using nuclear donor cells in GO or activating reconstituted oocytes few hours after nuclear transfer (post-activation). Sheep, goats, pigs, cattle and mice have been cloned this way; the latter two species - of both sexes. Cloning of transgenic mammals producing human therapeutic proteins in milk (or urine) can find application in pharmacology and medicine. Somatic cloning of a goat producing human antithrombine III in its milk has already been achieved.

Animals↗
PubMed2002

Analysis of hepatic vitamins A1, A2, their fatty acyl esters, and vitamin E for biomonitoring mammals feeding on freshwater fish.

In tissues of freshwater fish-feeding mammals, 3,4-didehydroretinol (A2) is a major form of vitamin A. In mink liver, with organochlorine exposure, this analog has been found to decrease more than retinol (A1) and thus has potential as a sensitive freshwater biomarker. The presence of the analogs A1 and A2 as alcohol and different fatty acyl esters, which react to polychlorinated biphenyls differently, necessitates detailed analyses achieved by using direct extraction of tissue homogenate. In direct hexane extraction, compared to total levels of the vitamins obtained in the saponification procedure, a large proportion of the vitamins was released only after repeated and long-time vortex mixing with the extraction solvent. Thus, in tissue extraction, the use of internal standardization alone can lead to a rough underestimation of the levels of these fat-soluble vitamins. For analyses of vitamins A1 and A2 in liver, we applied the argentation high-performance liquid chromatography, which provided good separation of individual A1 and A2 fatty acyl esters. We report retention times for numerous esters of A1 and A2 and, to aid identification, the change in their retention properties after adding AgNO3 to the mobile phase. The argentation did not affect the recoveries of any forms of the retinoids studied but destroyed half the vitamin E. Despite selective acylation of fatty acids into the vitamin A esters, the fatty acids of the esters were the same as those found to be the major fatty acids in the gas-liquid chromatography of total lipids. The goal of this work was to create a methodology that is suitable for biomonitoring alcoholic and esterified vitamins A1 and A2 in tissues of freshwater fish-feeding mammals.

Animals↗
PubMedDate not supplied

[Acoustic analysis of signals in mammals].

Spectral-prosodic characteristics of signals were analyzed synchronously with the main frequency for 32 mammals and one reptile using a KAZ-01 complex sound analyzer. The method of phoneme analysis was adapted for analysis of the signals. The main features of signaling in mammals have been revealed, which differed from those in birds and humans: low frequency range, low fundamental frequency, small number of local maxima, small frequency distance between them, and a significant amount of local maxima with zero energy.

Animal Communication↗