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At least 595 records · Page 33Linked to original sources
PubMed2004

Small mammals (Insectivora, Rodentia) as a potential source of chlamydial infection in East Slovakia.

The presence of antibodies against Chlamydophila (Chlamydia) psittaci in small mammals (Insectivora, Rodentia) in the region of East Slovakia are presented. The hosts were caught in several areas of Slovakia in habitats with different levels of anthropogenic disturbance. Research was carried out during 2000-2002. The authors examined 1,947 sera coming from 4 insectivore and 10 rodent species. Each serum was examined by micromethod of complement binding reactions using antigen Chlamydophila (Chlamydia) psittaci. Chlamydial infections were found in 251 individuals (prevalence 12.9 %) of 8 mammal species. The antichlamydial antibodies were proved at levels ranging from 1:32-1:1024. The highest prevalence of antibodies was detected in the most abundant rodent species Apodemus microps (14.8 %), Apodemus agrarius (13.9 %), Apodemus flavicolis (12.4 %), Microtus arvalis (12 %), and Clethrionomys glareolus (10.9 %). Positive hosts were registered in all studied localities. Testing of prevalence values in the individual research years confirmed significant changes. Our results showed that small mammals probably play an important role in the circulation of chlamydiae in nature.

Animals↗
PubMed2005

Serologic evidence of exposure of wild mammals to flaviviruses in the central and eastern United States.

Serosurveys were conducted to obtain flavivirus and West Nile virus (WNV) seroprevalence data from mammals. Sera from 513 small- and medium-sized mammals collected during late summer and fall 2003 from Colorado, Louisiana, New York, Ohio, and Pennsylvania were screened for flavivirus-specific antibodies. Sera samples containing antibody to flaviviruses were screened for WNV-specific antibodies by epitope-blocking enzyme-linked immunosorbent assays and confirmed with plaque reduction neutralization tests. Prevalence of WNV antibodies among study sites ranged from 0% to 42.8% among the mammal communities sampled. High prevalence rates for WNV were noted among raccoons (100%, with a very small sample size, N = 2), Virginia opossums (50.0%), fox squirrels (49.1%), and eastern gray squirrels (48.3%). The high WNV antibody prevalence noted for tree squirrels, the peri-domestic tendencies of several of these species, and their ease of observation could make these species useful sentinels for monitoring WNV activity within urban communities.

Animals↗
PubMed2006

Molecular targets of organotin compounds in endocrine disruption: do organotin compounds function as aromatase inhibitors in mammals?

Tributyltin (TBT) and triphenyltin (TPT) cause masculinization in female mollusks. These compounds may act as potential competitive inhibitors of aromatase, which converts androgens to estrogens, although effective concentrations are high. TBT and TPT may, therefore, increase the levels of unconverted androgens in invertebrates and vertebrates. However, at concentrations effective for aromatase inhibition, they are generally toxic to mammalian cells. These compounds markedly enhance aromatase activity and human chorionic gonadotropin (hCG) production, along with their mRNA expression, at very low concentrations in human choriocarcinoma cells. In ovarian granulosa cells, these compounds suppress aromatase gene expression at the same low concentrations. Therefore, it is suspected that, in mammals, these organotin compounds affect target molecules that regulate the gene expressions of aromatase and hCG, rather than functioning as aromatase inhibitors. Recently, it has been demonstrated that TBT and TPT directly bind to the retinoid X receptor (RXR) and the peroxisome proliferator-activated receptor (PPAR) gamma with high affinity and function as transcriptional activators. These compounds promoted adipocyte differentiation, which is triggered by the PPAR gamma/RXR signaling pathway. They may, therefore, exert their toxic effects through the activation of these pathways in mammals. Here, we review the potential endocrine disruption of organotin compounds via these nuclear receptors in mammals.

Animals↗
PubMed2006

[Peculiarities of regulation of cardiac function in some mammals].

We studied acetylcholine induced changes of action potentials (AP) in ventricles and atria of bat, hedgehog, yakut ground squirrel, and laboratory mice. In atria of all these species of mammals acetylcholine caused pronounced dose dependent shortening of AP. However sensitivity of ventricles of studied animals to acetylcholine was different. Acetylcholine induced AP shortening was 29.4, 42.1, 6.6 and 11% in ventricles of bat, hedgehog, laboratory mice and ground squirrel, respectively. Ventricles of none of previously studied mammals had sensitivity to acetylcholine comparable by magnitude to acetylcholine sensitivity which we found in hedgehog and bat. It is suggested that these animals have unique nervous regulation of cardiac action, principally different from that of other mammals, which do not require parasympathetic regulation of ventricles.

Acetylcholine↗
PubMed1991

Enzymatic control of pigmentation in mammals.

Visible pigmentation in mammals results from the synthesis and distribution of melanin in the skin, hair bulbs, and eyes. The melanins are produced in melanocytes and can be of two basic types: eumelanins, which are brown or black, and phaseomelanins, which are red or yellow. In mammals typically there are mixtures of both types. The most essential enzyme in this melanin biosynthetic pathway is tyrosinase and it is the only enzyme absolutely required for melanin production. However, recent studies have shown that mammalian melanogenesis is not regulated solely by tyrosinase at the enzymatic level, and have identified additional melanogenic factors that can modulate pigmentation in either a positive or negative fashion. In addition, other pigment-specific genes that are related to tyrosinase have been cloned which encode proteins that apparently work together at the catalytic level to specify the quantity and quality of the melanins synthesized. Future research should provide a greater understanding of the enzymatic interactions, processing, and tissue specificity that are important to pigmentation in mammals.

Amino Acid Sequence↗
PubMedDate not supplied

[Respiratory organ lipids in fishes and mammals. A model representation of the area of the lipid component].

Studies have been made on lipid composition of the gills in 19 species of fishes and of the lungs in 8 mammalian species. It was shown that the arbitrary "unit fragment" of the lipid component of the respiratory organs in all the investigated animals exhibits similar qualitative composition, but contains different quantity of lipid molecules, i. e. approximately 19 in fishes and 42 in mammals. Theoretical conformational analysis revealed predominant conformations of phosphatidylcholine, phosphatidylethanolamine, phosphatidylserine, sphingomyelin and cholesterol; projections of these molecules on the surface which is parallel to membrane surface were composed. It was shown that projectional areas for the main phospholipid molecules differ only by 2-3%. These data indicate that the surface of a model of the lipid component in the membranes of respiratory organs in mammals is twice larger than in fishes. These differences presumably account for more effective oxygen transfer in mammals.

Animals↗
PubMed1990

Adaptiveness of tunnel system features in subterranean mammal burrows.

Most moles and mole rats spend their lifetimes within the confines of tunnel walls, constructing, maintaining, and modifying burrow system structure in response to changing external circumstances and changing internal needs. Thus, anatomy, physiology, behavior, and distribution are all greatly affected by the burrow environment, with temperature, humidity, gas concentrations, living space, availability of food and mating partners, and protection from flooding and predation all being influenced by burrow architecture. Regrettably, the burrow structure of almost all subterranean mammals is unknown, or known only from several incomplete excavations. Moreover, existing data is often vague without any mention of particular structures or surrounding habitat, which makes the placing of burrow structure in an adaptive perspective difficult. Reasons for these short-comings are understandable: excavations require laborious excavation which can extend for hundreds of meters, reaching depths in excess of a meter; it is often difficult to remove the occupant prior to excavation which avoids modification of the system by the animal during excavation; particular types of subterranean mammals are limited in distribution to particular continents so that the literature is often localized and a global perspective difficult to obtain; and there is no standardization of terms relating to burrow structure, making intergroup comparison confusing. This paper addresses the above difficulties and encourages further investigation in this central area of study by making obvious the paucity of information for most subterranean mammals, presenting a synopsis of known burrow structures of major groups which will make particular gaps in our knowledge evident, providing a bibliography of major papers on burrow structure with coverage of most moles and mole rats, establishing a checklist of burrow features to better analyze future excavations and facilitate intergroup comparison, and lastly, to indicate possible adaptive significance of various burrow features to promote further observation, speculation and experimentation.

Adaptation, Biological↗
PubMed1990

Morphological evolution of subterranean mammals: integrating structural, functional, and ecological perspectives.

The widely recognized convergence of subterranean mammals offers unique opportunities for the study of patterns, causes and consequences of morphological integration. For example, behavioral and biomechanical observations have revealed a diversity of digging modes among subterranean mammals. In rodents, scratch-digging and chisel-tooth digging, alone or combined, are widespread. This dual nature of the digging apparatus must be understood to avoid erroneous assessments of specializations based on forelimb modifications only. Additionally, bulldozing and disposal of loose soil is performed by head-lifting, by means of the forelimbs, or with the hindlimbs. Insectivores are known to resort to scratch-digging, sand-swimming, or to a unique system known as humeral rotation. Semi-fossorial species among rodents and insectivores are scratch-diggers. In contrast, fully subterranean taxa show further specializations for scratch-digging and/or resort to some of the other digging modes. The ecological correlates of these morphological trends are still poorly known; work in geomyids suggests that scratch-digging specializations are efficient in friable soils, whereas tooth-digging allows the utilization of a much broader spectrum of soil types. This indicates that alternative pathways of morphological specialization are not equivalent in their ecological potentialities. Important morphological features, such as incisor procumbency among tooth-diggers, are shown to be constrained by structural, allometric, and mechanical factors. In geomyids, the same procumbent morphologies may be acquired as a byproduct of size increases, by means of adaptive shifts independent from size, or by a combination of both. Thus, geometric similarity may not be indicative of functional similarity. Further constraints result from the integration of different functions. For instance, it is suggested that mastication imposes limitations upon potential modifications of jaw morphology for tooth-digging. Scratch-digging appears to be less constrained by locomotion, but the effects of integration of various functions in fore- and hind-limbs are largely unexplored. Multiple approaches, combining behavioral, functional, ecological, structural, and phylogenetic data, are necessary for the study of morphological evolution among subterranean mammals.

Animals↗
PubMed1990

The Chrysochloridae: studies toward a broader perspective of adaptation in subterranean mammals.

Earliest chrysochlorids (from the Miocene) resemble contemporary members of the family. Unlike talpids, chrysochlorids have eyes covered with skin; pick-like foreclaws; a blunt, padded rostrum; and no external tail. Golden moles are an ancient lineage of mammals (related to tenrecs) with many unique features; it has been suggested that the Chrysochloridae constitute a separate order, the Chrysochloridea. In contrast, a constancy of structure within the group belies the wide range in habitat of the various species (including grassland, forest, and shifting desert sands), in contrast to the aquatic desmans and shrew-like talpids. Some species of golden mole are able to disperse over large distances, being accomplished swimmers (as are talpids) and having a wide range of diet; nonetheless, populations and species are patchily distributed throughout the range of the family (Africa south of the Sahara whereas talpids occur in the northern hemisphere). Diversity of chrysochlorid species is greatest in Southern Africa, from which emigrations to the north probably occurred. Although solitary, there is little evidence for competitive exclusion between the chrysochlorids, rhizomyids, or the more social and aggressive bathyergid rodent moles to explain the high incidence of endemism. Low litter sizes are indicative of the few predators known to effectively prey on golden moles. Physical factors which might restrict species from an area (such as food shortages and temperature extremes) may be overcome by becoming torpid, an ability unknown for other subterranean mammals. Clustering of largely immobile food resources and friable soils appear to be the major factors influencing chrysochlorid distribution. There is substantial need for basic studies on all aspects of the biology of chrysochlorids for a better understanding of evolutionary processes within the family, which will in turn contribute to a broader understanding and more balanced view of evolutionary processes in all subterranean mammals.

Animals↗
PubMed1988

Serological investigations in Q-fever and listeriosis of wild-living small mammals on the Cape Verde Islands.

Serological investigations of small mammals had been made on the Island Santiago (Cape Verde Islands), to clear up how far synantropic, small mammals are reservoir hosts for pathogens, such as Coxiella burnetti and Listeria monocytogenes. 367 small mammals representing two species (Rattus rattus and Mus musculus) were trapped. Q-fever antibodies were detected in 155 of 350 examined rats and mice (44.29%). 18.89% of all tested sera showed positive results to Listeria-antigen, serovar 4bH, 5.48% to 4b0 and 9.75% to 01.

Animals↗
PubMed1986

Heterogeneity and structure of brain tubulins from cold-adapted Antarctic fishes. Comparison to brain tubulins from a temperate fish and a mammal.

Tubulins purified from brain tissue of Antarctic fishes assemble in vitro to form microtubules at the low temperatures experienced by these extreme psychrophiles (Williams, R. C., Jr., Correia, J. J., and DeVries, A. L. (1985) Biochemistry 24, 2790-2798). We have initiated studies to determine the structural requirements for assembly of Antarctic fish tubulins at low temperatures. As a first step we have compared the heterogeneity, structures, amino acid compositions, and net charge of brain tubulins purified from three Antarctic fishes (Notothenia gibberifrons, Notothenia coriiceps neglecta, and Chaenocephalus aceratus), from the temperate channel catfish (Ictalurus punctatus), and from a mammal (the cow). Each preparation contained the alpha- and beta-tubulins and was free of microtubule-associated proteins. When examined by isoelectric focusing and by two-dimensional electrophoresis, brain tubulins from the Antarctic fishes were found to be highly heterogeneous; each was resolved into approximately 20 isoelectric variants. The distributions of the isotubulins from the cold-adapted fishes were similar but differed significantly from those of tubulins from catfish and cow. The average isoelectric points of the alpha- and beta-tubulins from the Antarctic fishes were more basic than the isoelectric points of the corresponding tubulins from bovine brain. Peptide mapping confirmed that tubulins from the Antarctic fishes and the mammal differed in structure. The amino acid compositions of fish and mammalian tubulins were similar, but Antarctic fish tubulins apparently contained fewer Glx residues than did catfish or bovine tubulins. Finally, native tubulins from an Antarctic fish and the cow differed slightly in net negative charge. Thus, brain tubulins from the cold-adapted fishes differ structurally from the tubulins of a temperate fish and of a mammal.

Acclimatization↗
PubMed1985

Effects of 3-acetylpyridine (3-AP) intoxication on the nervous system of mammals and birds.

The authors studied, for the first time, the effects of 3-acetylpyridine administration on the nervous system of birds. The results were compared with those obtained in a mammal not studied yet. The data achieved from the guinea-pig confirmed substantially those got from other mammals, particularly from the rat. They pointed out the constant toxic action caused by the above drug inoculation on the central nervous system. The effects on birds are quite different: 3-AP administration, even at different doses from those employed in mammals, seldom provokes lesions of the central nervous system and the appearance of alterations does not depend on the considered species.

Animals↗
PubMed1973

First detection of tularaemia in domestic and wild mammals in Iran.

During a study on the ecology of small-mammal-borne infections in Iran, over 4 600 wild mammals were collected at 47 localities. Attempts were made to isolate Francisella tularensis from the spleens of 3 548 of these animals. All were found to be negative. In addition, sera from 200 sheep and cattle and from 39 wild mammals were tested: 8 sheep, 3 oxen, and 1 hedgehog showed evidence of recent infection. This is the first report of tularaemia in Iran. The relationship of these findings to the potential distribution of natural foci in Iran and adjacent countries indicates that the infection in Asia may be more widespread than was previously thought.

Agglutination Tests↗
PubMed1967

The relationship between the tick-borne encephalitis virus and the ticks and mammals of the Tribec mountain range.

The basic problem in the study of tick-borne virus diseases is to establish where the virus is maintained in nature. In general, this focus will be found where there are large and relatively stable populations of ticks, small rodents and insectivores. In the Tribec region the principal vector of tick-borne encephalitis (TBE) is Ixodes ricinus, although other species can circulate the virus under suitable conditions. The virus can persist during winter either in starving nymphs or adults or in non-starving larvae or nymphs. It can also persist in hibernating mammals, but this is a less important mechanism. Among the mammals, the insectivores (hedgehogs, shrews and moles) and certain rodents are hosts of ticks and reservoirs of TBE virus of great importance. During spring, game and farm animals play an important role and birds are important hosts when the number of small mammals is low. Thus the survival of TBE virus depends on a complex interaction of varying populations of tick vectors and vertebrate hosts that occur in different habitats influenced by different environmental conditions.

Animals↗
PubMed1980

Isolates of avian sarcoma virus Bratislava 77 (B77) oncogenic for mammals do not contain an excess of transformation-defective mutants.

Several isolates of the avian sarcoma virus Bratislava 77 (B77), used in tumor induction in rats, hamsters and mice, were tested for the excess of spontaneously segregated transformation-defective mutants (tdB77). The question was asked whether these td mutants could interfere with transforming sarcoma viruses at tumor induction in mammals. It was found that the B77 virus isolates used in successful sarcoma induction in mammals did not contain an excess of td mutants. One virus isolate which had an excess of td mutants did not induce tumors in mammals. The further characterization of the rescued viruses from virogenic mammalian cells showed that all rescued viruses had the same sub-group C specificity as the original isolate of B77 virus. The integration of the viral genome into mammalian cellular genome did not alter transforming ability of the rescued viruses on duck embryo cells. It seems that propagation of B77 virus in conditions in vivo did not support the segregation, and accumulation of an large excess of td mutants in stocks of B77 virus.

Animals↗
PubMed1981

[Adiaspiromycosis in small mammals in large capacity pigsties in the Trebon basin].

From 1977 to 1979 a study on the occurrence of adiaspiromycosis was performed on three animal farms in South Bohemia. In 113 examined small mammals from the farms and their neighbourhoods adiaspiromycosis was detected in M. arvalis living both in the fields in the precincts (7/613, i. e. 1.14%) and in the grassy areas inside the three animal farms (5/221, i. e. 2.3%). By that time no adiaspiromycosis was found in small mammals living in the farm buildings. The obtained results were compared with the results achieved at the control locality Klec, in the same geographical region, where adiaspiromycosis had been followed for 15 years. At the control locality adiaspiromycosis was found in further four species of small mammals: Talpa europaea, Erinaceus europaeus, Apodemus sylvaticus and Ondatra zibethica. The occurrence of adiaspiromycosis inside the farms is a serious epizootological finding. From the viewpoint of maintaining and circulation of pathogen is on the studied farms undoubtedly of major importance M. arvalis, forming here permanently living residential populations.

Animals↗
PubMed1982

Removal of total organic carbon from marine mammal pool water by polymeric resins.

Chlorinated organic compounds comprise a portion of the total organic carbon (TOC) of marine mammal pool water. The long-term effects of these substances on the health of captive marine mammals are unknown, but good husbandry practices should include maintaining TOC at low concentrations. Two polymeric resins (trade names XAD-2 and XAD-4) were tested for their capacity to adsorb TOC from the water of a saline, closed-system marine mammal pool. At a concentration of 588 mg of XAD-2/L, TOC was reduced by approximately 9% after 96 hours; 630 mg of XAD-4/L reduced TOC concentrations by approximately after 77 hours. Equilibrium was not approached in any of the experiments. The 2 materials tested are ineffective in this particular application, but ion exchange resins may perform better.

Adsorption↗
PubMed1980

Effects of tertiary methods on total organic carbon removal in saline, closed-system marine mammal pools.

Organic matter accumulates in marine mammal pools that are not diluted continuously with clean influent water. Some of this material may be carcinogenic or mutagenic. Four tertiary methods were tested for effectiveness in lowering the total organic carbon (TOC) concentration in saline marine mammal pools. The TOC concentration at the start of each trial is shown in parentheses. Ozonation alone in duplicate trials had no effect on TOC during sequential contact periods of 25, 30, and 30 minutes (13.66 mg of TOC/L of sample water) and 30, 30, and 30 minutes (12.85 mg of TOC/L) when the dosage levels were 4.13, 4.03, and 4.52 mg of O3/L, respectively. Contacting marine mammal water with granular activated carbon in a single trial (12.91 mg of TOC/L) removed approximately 37% of the TOC in 10 minutes, but only an additional 11% was removed in 60 minutes. The amount removed in 10 minutes was equivalent to 20 days' accumulation at previously determined rates of increase. Brief ozonation of the water, followed by contact with granular activated carbon, was the most effective method tested. When results of the duplicate trials (12.95 and 12.65 mg of TOC/L) were averaged, the amounts of TOC removed were 60% (5 minutes), 70% (10 minutes), and 78% (30 minutes). Two experiments using superchlorination (114 mg of free available chlorine/L of water contacted for 4.5 hours) reduced the TOC concentration from 15.6 to 11.2 mg/L (28%) reduction), and from 15.6 to 10.2 mg/L (35% reduction).

Adsorption↗