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At least 289 records · Page 16Linked to original sources

PubMed1997

Thermal relations of metabolic rate reduction in a hibernating marsupial.

We tested whether the reduction of metabolic rate (MR) in hibernating Cercartetus nanus (Marsupialia, 36 g) is better explained by the reduction of body temperature (Tb), the differential (delta T) between Tb and air temperature (Ta), or thermal conductance (C). Above the critical Ta during torpor (Ttc) of 4.8 +/- 0.7 degrees C where the Tb was not regulated, the steady-state MR was an exponential function of Tb (r2 = 0.92), and the overall Q10 was 3.3. However, larger Q10 values were observed at high Tb values during torpor, particularly within the thermoneutral zone (Q10 = 9.5), whereas low Q10 values were observed below Tb 20 degrees C (Q10 = 1.9). The delta T did not change over Ta 5-20 degrees C, although MR fell, and therefore the two variables were not correlated. Below the Ttc, Tb was regulated at 6.1 +/- 1.0 degrees C and MR increased proportionally to delta T. Our study suggests that MR in torpid C. nanus is largely determined by temperature effects and metabolic inhibition. In contrast, delta T explains MR only below the Ttc and C appears to affect MR only indirectly via changes of Tb, suggesting that delta T and C play only a secondary role in MR reduction during hibernation.

Animals↗

PubMed2006

Cross-species clues of an epigenetic imprinting regulatory code for the IGF2R gene.

The epigenetic marks on the IGF2R gene that encodes a receptor responsible for IGF-II degradation consist of differentially methylated DNA in association with multiple modifications on the associated histones. We review these epigenetic marks across various species during the evolution of IGF2R imprinting. Both IGF2 and IGF2R genesare imprinted in the mammal lineage that diverged from Monotremata approximately 150 million years ago. While IGF2 is consistently imprinted in all mammals following its divergence, IGF2R imprinting disappears in the Euarchonta lineage, including human species, approximately 75 million years ago. Differential DNA methylation marks on the two parental alleles correlate with imprinting in all imprinted genes including IGF2R. While the DNA methylation marks in the IGF2R promoter region 1 (DMR1) correlate with IGF2R allelic expression, the DNA methylation marks in the intron region 2 (DMR2) fail to correlate with IGF2R imprinting status in a number of species. Human IGF2R and mouse neuronal Igf2r are not imprinted despite the presence of DMR2. We have noted that human IGF2R is not imprinted in more than 100 informative samples including various tumor tissues. Furthermore, opossum (Marsupialia) IGF2R is consistently imprinted despite the absence of DMR2. These lines of evidence indicate that DNA methylation marks in DMR2 are neither necessary nor sufficient for consistent imprinting of IGF2R across species. Histone modification marks, however, correlate more consistently with the tissue-specific and species-specific imprinting status of IGF2R in human and mouse. Acetylated histone H3 and H4 and methylated lysine 4 of H3 (H3-K4Me) associate with transcriptionally active alleles while tri-methylated lysine 9 of H3 (H3-K9Me3) marks the silenced alleles. In the mouse, an antisense non-coding transcript called Air is transcribed from DMR2 on the paternal allele, and this imprinted transcript plays a central role in Igf2r imprinting. Mouse Igf2r imprinting depends on an Air RNA while the existence of AIR in other species is unknown. Overall, DNA methylation, histone acetylation, and histone methylation play a vital role in coordinating IGF2R allelic expression across all species. Rare monoallelic or skewed allelic expression of human IGF2R and their biological importance warrants further rigorous study.

Animals↗

PubMed2005

Cost of transport is increased after cold exposure in Monodelphis domestica: training for inefficiency.

Monodelphis domestica (Didelphidae: Marsupialia) lacks brown adipose tissue and thus relies on skeletal muscle as its primary thermogenic organ. Following cold exposure, the aerobic capacity of skeletal muscle in these animals is greatly increased. We investigated the effects of this plastic response to thermogenesis on locomotion and muscle mechanics. In cold-exposed animals, cost of transport was 15% higher than in controls but was unaffected by exercise training. Twitch kinetics in isolated semitendinosus muscles of cold-exposed animals were characteristic of slow-oxidative fiber types. Both time-to-peak tension and half-relaxation time were longer and maximal shortening velocity was slower following cold exposure compared to either thermoneutral controls or exercise-trained animals. Further, muscles from the cold-exposed animals had greater fatigue resistance than either control or exercise-trained animals, indicating greater oxidative capacity. Finally, we identified an uncoupling protein 3 homologue, whose gene expression was upregulated in skeletal muscle of cold-exposed Monodelphis domestica. Cold exposure provided a potent stimulus for muscle plasticity, driving a fast-to-slow transition more effectively than exercise training. However, linked to the dramatic shift in muscle properties is an equally dramatic increase in whole animal muscle energetics during locomotion, suggesting an uncoupled state, or 'training for inefficiency'.

Adaptation, Physiological↗

PubMed1994

Eutherian phylogeny as inferred from mitochondrial DNA sequence data.

The phylogenetic relationships among Primates, Artiodactyla, Cetacea, Carnivora, and Rodentia were estimated from the amino acid sequences of proteins encoded by the mitochondrial genomes, for which entire nucleotide sequence data are available, using Marsupialia, Aves, and Amphibia as outgroups. The overall evidence of the maximum likelihood, as well as maximum parsimony, analyses strongly suggests that Rodentia is an outgroup to the other four eutherian orders, and that Cetacea and Artiodactyla form a clade with Carnivora as a sister taxon, consistently with the molecular phylogenetic studies of previous authors. However, analyses of individual proteins do not necessarily conform to this conclusion, and some of the proteins reject the putatively correct tree with nearly 5% significance. Furthermore, the 12S mitochondrial ribosomal RNA sequences do not give the putatively correct tree irrespective of the alignments and of the phylogenetic methods, although the tree is not rejected with a statistical significance. The 16S ribosomal RNA sequences give the putatively correct tree with our sequence alignment when the ML method is used, but the result depends on the alignment and on the choice of outgroup species. These results illustrate the limitation of the ribosomal RNA data alone in phylogenetic inference, and suggest that we must analyze as many genes as possible and synthesize the results to draw a reliable conclusion.

Amino Acid Sequence↗

PubMed2000

A survey of hemoparasite infections in free-ranging mammals and reptiles in French Guiana.

Blood smears of 1,353 free-ranging mammals (35 species) and 112 reptiles (31 species) from French Guiana were examined for hemoparasites. Parasites from 3 major groups were recorded: Apicomplexa (including hemogregarines, piroplasms, and Plasmodium spp.), Trypanosomatidae, and Filaroidea. Fifty percent of the individuals (86% of the species) were infected by parasites from at least 1 group. Hemogregarines, identified as Hepatozoon sp., infected numerous snakes with high prevalences (30-100%); infection is reported for the first time in 5 host genera of snakes: Clelia, Oxybelis, Pseustes, Rhinobotryum, and Bothriopsis. Infections were also observed in 4 marsupial species and 1 rodent. Hepatozoon spp. recorded in Didelphis albiventris (Marsupialia) and Coendou prehensilis (Rodentia) may be new species. Plasmodium sp. were observed in 2 snake species, Dipsas indica (Colubridae) and Bothrops atrox (Viperidae). Plasmodium brasilianum was recorded in all 5 primate species examined. Piroplasms were observed in all mammal orders except primates. Large terrestrial rodents were the main hosts of members of the Babesidae; 42% of Myoprocta acouchy, 36% of Dasyprocta agouti, and 44% of Agouti paca were infected. Trypanosomes were common in mammals and were recorded in 70% of the examined genera. Trypanosoma cruzi-like infections were reported in 21 mammal species, including sloths, rodents, carnivores, and primates. Microfilariae were also widespread, with higher prevalences in sloths, anteaters, and porcupines (>40% of the individuals infected) and in tamarins (95% infected). This survey highlights some potential anthropozoonotic risks due to the recent further evidence of Plasmodium brasilianum and P. malariae as a single species and to the increased diversity of hosts for Trypanosoma cruzi.

Animals↗

PubMed2001

Thaumasioscolex didelphidis n. gen., n. sp. (Eucestoda: Proteocephalidae) from the black-eared opossum Didelphis marsupialis from Mexico, the first proteocephalidean tapeworm from a mammal.

Thaumasioscolex didelphidis n. gen., n. sp. is described from the intestine of the black-eared opossum Didelphis marsupialis L. (Marsupialia: Didelphidae) from Los Tuxtlas, Veracruz, Mexico. The new genus differs from all proteocephalidean genera in the morphology of the scolex that is formed by 4 well separated lobes each containing 1 noncircular sucker opening laterally inside the exterolateral cavity, a large-sized body (length up to 1 m), a large number of testes, the shape of gravid proglottids that are inversely craspedote (the anterior border of a proglottid overlaps the posterior border of a preceding proglottid), eggs in groups mostly of 4-6 eggs each, and an embryophore bearing digitiform projections on its external surface. This is the first tapeworm of the Proteocephalidea, the members of which were previously reported exclusively from poikilotherm vertebrates (freshwater fishes, amphibians, and reptiles), found in a homoiotherm vertebrate.

Animals↗

PubMed2003

A new species of Mathevotaenia (Cestoda: Anoplocephalidae) and other tapeworms from marsupials in Argentina.

Cestodes are reported from Didelphis albiventris Lund, 1840 and Micoureus cinereus Temminck, 1824 (Marsupialia: Didelphidae) in Argentina. These include a new species of Mathevotaenia Akhumyan, 1946 (Cestoda: Anoplocephalata) as well as M. bivittata (Janicki, 1904) and an unknown hymenolepidid cestode. Mathevotaenia argentinensis n. sp. is characterized by a relatively narrow strobila, 18-37 mm in total length and 1.0-1.5 mm in maximum width, 135-163 craspedote proglottids, 19-27 testes, and a muscular genital atrium. This species differs from M. didelphidis (Rudolphi, 1819) in the disposition of the genital ducts between the excretory canals and in the entrance of the vagina into the genital atrium posterior to the cirrus pouch; from M. paraguayae Schmidt and Martin, 1978 in the disposition of the genital ducts, absence of a seminal receptacle, and presence of an armed cirrus; and from M. boliviana Sawada and Harada, 1986 and M. pennsylvanica Chandler and Melvin, 1951 in the presence of an armed cirrus. Linstowiines appear to be the dominant cestodes in New World marsupials, with M. bivittata representing the most prevalent and widely distributed species. The hymenolepidid is the first record of this family in Neotropical marsupials.

Animals↗

PubMed1989

[Incidence of the spirochete Borrelia burgdorferi in arthropods (Arthropoda) and antibodies in vertebrates (Vertebrata)].

The paper summarizes data on hitherto assembled findings of Spirochaeta burgdorferi, the causal agent of Lyme disease in arthropods and the incidence of antibodies in birds and mammals. The authors evaluate some vectors and reservoir animals, incl. possible carriers. Borrelia burgdorferi was found so far in 30 species of Arthropoda, 13 species of mites (Acarina), 15 species of flies(Diptera), two species of fleas (Siphonaptera). The role of insects as vectors was not proved so far. Antibodies were detected in eight species of birds (Aves, Passeriformes) and in 22 mammalian species: one species of marsupiales (Marsupialia), 3 species of carnivores (Carnivora), seven species of rodents (Rodentia), two species of rabbits and hares (Lagomorpha), in 8 species of even-toed ungulates (Artiodactyla) and one species of odd-toed ungulates (Perissodactyla). The great majority of species comes from the non-arctic area.

Animals↗

PubMed1989

Trypanosoma (Herpetosoma) leeuwenhoeki in Choloepus hoffmanni and Didelphis marsupialis of the Pacific Coast of Colombia.

Trypanosoma (Herpetosoma) leeuwenhoeki, originally described in Panamanian sloths, was isolated from Didelphis marsupialis (Marsupialia) and Choloepus hoffmanni (Edentata) inhabiting the Pacific coast of Colombia. Trypanosomes were characterized by their large blood forms (total length 51-53 microns), poor infectivity for mice, and lack of development in Rhodnius prolixus. Isoenzyme studies, with either strains or clones, revealed homogeneous profiles clearly distinct from Trypanosoma cruzi and Trypanosoma rangeli reference strains. The present report extends the geographical distribution of T. leeuwenhoeki to South America and broadens its known host range to another order of mammals.

Animals↗

PubMed1986

[Upright posture of the human and the morphologic evolution of the musculi extensores digitorum pedis with reference to evolutionary myology].

A brief literature review is made of the morphological changes in the bones of the lower limbs of man, which are the result of his upright walk. The author's task has been to study the morphological changes of Mm. extensores digitorum pedis from the viewpoint of evolutionary myology. The following material has been studied: Lower limbs of adults, 151 less than or equal to N less than or equal to 358. Pelvic limbs of Marsupialia, Insectivora, and non-hominide primates; N = 122. Lower limbs of human embryos and fetuses; N = 71. The following acknowledgements are the author's own studies. They begin with an evolutionary-myological study of m. extensor hallucis longus and of m. extensor digitorum longus, together with m. peroneus tertius.

Biological Evolution↗

PubMed1977

[Carpal bones of the Chiroptera in the comparative-anatomical and functional aspects].

Data on investigation of hand sceletal bones carried out in eight genera of three families of bats were subjected to comparative-anatomical and functional analysis. Quantitatively, the hand sceletal bones of Chiroptera preserve constructive pattern general for the hand of terrestrial mammalians Pentadactilus. It has rudiments of the prefirst (Pp) and the seventh (Pm) rays. The latter is situated on the volar surface of the base Mc5. Scaphoid, semilunar and central carnal bones of Chiroptera, like those of Mototremata, some Marsupialia, Insectivorona and Carnivora merge together into one large bone--os lunatum. At the same time, the hand of Chiropter is a highly specialized structure, that is evident from the presence of articular restricotrs of anterior sagging of the wrist, crests and grooves directing movements in a strictly definite plane, from fan-like spreading and bringing together the rays, from very long metacarpal bones and proximal phalanges, from reduction of distal phalangs of the 3d and 5th fingers. Thus, the hand of Chiroptera is a unique example of combination of primitive, initial for pentadactule plantigrades wrist with signs of narrow specialization resembling, to some extent, those of Ungulata; only in Ungulata those signs developed on the base of digitigrades wrist.

Anatomy, Comparative↗

PubMed1981

[Sublingual structures of primates. II. Hominoidea, review, summary and literature].

1. In Homo and the great apes (Pongidae) there occurs, besides the plica sublingualis a plica fimbriata at the ventral surface of the tongue. This duplicature of the mucosa does not occur in the Hylobytidae and in the other primates. 2. Some taste buds could be found in the epithelium of the plica sublingualis of the Pongidae. 3. There are many taste buds in the epithelium of the plica fimbriata of the Pongidae. On this sublingual structure there were counted 1776 taste buds in Pongo, 592 in Gorilla and 280 in Pan. A few taste buds could also be found on the plica fimbriata of a human newborn. 4. A glandula apicis linguae occurs in Homo, Pan, Gorilla and Pongo. 5. The fresh saliva of the glandula apicis linguae and the saliva on the floor of the mouth can be tested by the taste buds in the epithelium of the plica fimbriata, of papillae lenticulares and of areae gustatoriae at the ventral surface of the tongue. 6. It might be the function of the sublingual taste buds to taste the fresh saliva as a gradient for the central nervous comparison with the taste of the saliva on the dorsal surface of the tongue. 7. Because of the complete absence of a sublingua in the Platyrrhini and in the Cercopithecinae it is unlikely that the plica fimbriata of Homo and the great apes can be interpreted as a homalogon of the sublingua in the prosimians. 8. Because of the absence of a sublingua in other ordines of the Mammalia (Insectivora, Carnivora, Rodentia, Chiroptera, Ungulata) it is unlikely as well that the sublingua in the prosimians can be interpreted as a homologon of the tongues of the lower vertebrates. The sublingual structures occuring in the Marsupialia have to be investigated. 9. Because of these reasons the new development of the sublingua in the prosimians and the plica fimbriata in the Hominoidea, in complete independence from one another, seems to be a better explanation of the 2 structures and less contradictionary to anatomical and phylogenetic arguments. The different function of both structures in the recent primates gives a hint for the possible reason for their development during the process of evolution.

Animals↗

PubMed1994

Evolution of alanine:glyoxylate aminotransferase 1 peroxisomal and mitochondrial targeting. A survey of its subcellular distribution in the livers of various representatives of the classes Mammalia, Aves and Amphibia.

As part of a wider study on the molecular evolution of alanine:glyoxylate aminotransferase 1 (AGT1) intracellular compartmentalization, we have determined the subcellular distribution of immunoreactive AGT1, using postembedding protein A-gold immunoelectron microscopy, in the livers of various members of the classes Mammalia, Aves, and Amphibia. As far as organellar distribution is concerned, three categories could be distinguished. In members of the first category (type I), all, or nearly all, of the immunoreactive AGT1 was concentrated within the peroxisomes. In the second category (type II), AGT1 was found more evenly distributed in both peroxisomes and mitochondria. In the third category (type III), AGT1 was localized mainly within the mitochondria with much lower, but widely variable, amounts in the peroxisomes. Type I animals include the human, two great apes (gorilla, orangutan), two Old World monkeys (anubis baboon, Japanese macaque), a New World monkey (white-faced Saki monkey), a lago, morph (European rabbit), a bat (Seba's short-tailed fruit bat), two caviomorph rodents (guinea pig, orange-rumped agouti), and two Australian marsupials (koala, Bennett's wallaby). Type II animals include two New World monkeys (common marmoset, cotton-top tamarin), three prosimians (brown lemur, fat-tailed dwarf lemur, pygmy slow loris), five rodents (a hybrid crested porcupine, Colombian ground squirrel, laboratory rat, laboratory mouse, golden hamster), an American marsupial (grey short-tailed opossum), and a bird (raven). Type III animals include the large tree shrew, three insectivores (common Eurasian mole, European hedgehog, house shrew), four carnivores (domestic cat, ocelot, domestic dog, polecat ferret), and an amphibian (common frog). In addition to these categories, some animals (e.g. guinea pig, common frog) possessed significant amounts of cytosolic AGT1. Whereas the subcellular distribution of AGT1 in some orders (e.g. Insectivora and Carnivora) did not appear to vary markedly between the different members, in other orders (e.g. Primates, Rodentia and Marsupialia) it fluctuated widely between the different species. Phylogenetic analysis indicates that the subcellular distribution of AGT1 has changed radically on numerous occasions during the evolution of mammals. The new observations presented in this paper are compatible with our previous demonstration of a relationship between AGT1 subcellular distribution and either present or putative ancestral dietary habit, and our previous suggestion that the molecular evolution of the AGT gene has been markedly influenced by dietary selection pressure.

Alanine Transaminase↗

PubMedDate not supplied

[The mammalian Harderian gland (its structural characteristics)].

The Harderian gland is located in the eye orbit and is part of orbital glands complex. The gland is present in almost all vertebrates, i.e., amphibians (except the completely aquatic ones), reptiles, birds, mammals, but not in fish. Among mammals it was described in the Marsupialia and most Eutheria. This review includes data on the Harderian gland structure and cytology of its secretory epithelium. Location of the gland in the eye orbit, its structure and relative size vary in different mammals. Ultrastructural characteristics of its epithelial cells also vary. There are structural differences not only between protein-, mucus- and lipid-synthesizing cells, but within each of these groups too. The chemical nature of the Harderian gland secretory product is species specific.

Animals↗

PubMed1965