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At least 883 records · Page 49Linked to original sources
PubMed2004

Viability of X-autosome translocations in mammals: an epigenomic hypothesis from a rodent case-study.

X-autosome translocations are highly deleterious chromosomal rearrangements due to meiotic disruption, the effects of X-inactivation on the autosome, and the necessity of maintaining different replication timing patterns between the two segments. In spite of this, X-autosome translocations are not uncommon. We here focus on the genus Taterillus (Rodentia, Gerbillinae) which provides two sister lineages differing by two autosome-gonosome translocations. Despite the recent and dramatic chromosomal repatterning characterising these lineages, the X-autosome translocated species all display intercalary heterochromatic blocks (IHBs) between the autosomal and the ancestral sexual segments. These blocks, composed of highly amplified telomeric repeats and rDNA clusters, are not observed on the chromosomes of the non-translocated species, nor the Y1 and Y2 of the translocated species. Such IHBs are found in all mammals documented for X-autosome translocation. We propose an epigenomic hypothesis which explains the viability of X-autosome translocations in mammals. This posits that constitutive heterochromatin is probably selected for in X-autosome translocations since it may (1) prevent facultative heterochromatinization of the inactivated X from spreading to the autosomal part, and (2) allow for the independent regulation of replication timing of the sex and autosomal segments.

Animals↗
PubMed1999

Defining the ancestral karyotype of all primates by multidirectional chromosome painting between tree shrews, lemurs and humans.

We used multidirectional chromosome painting with probes derived by bivariate fluorescence-activated flow sorting of chromosomes from human, black lemur (Eulemur macaco macaco) and tree shrew (Tupaia belangeri, order Scandentia) to better define the karyological relationship of tree shrews and primates. An assumed close relationship between tree shrews and primates also assists in the reconstruction of the ancestral primate karyotype taking the tree shrew as an "outgroup" species. The results indicate that T. belangeri has a highly derived karyotype. Tandem fusions or fissions of chromosomal segments seem to be the predominant mechanism in the evolution of this tree shrew karyotype. The 22 human autosomal painting probes delineated 40 different segments, which is in the range found in most mammals analyzed by chromosome painting up to now. There were no reciprocal translocations that would distinguish the karyotype of the tree shrew from an assumed primitive primate karyotype. This karyotype would have included the chromosomal forms 1a, 1b, 2a, 2b, 3/21, 4-11, 12a/22a, 12b/22b, 13, 14/15, 16a, 16b, 17, 18, 19a, 19b, 20 and X and Y and had a diploid chromosome number of 2n=50. Of these forms, chromosomes 1a, 1b, 4, 8, 12a/22a, and 12b/22b may be common derived characters that would link the tree shrew with primates. To define the exact phylogenetic relationships of the tree shrews and the genomic rearrangements that gave rise to the primates and eventually to humans further chromosome painting in Rodentia, Lagomorpha, Dermoptera and Chiroptera is needed, but many of the landmarks of genomic evolution are now known.

Animals↗
PubMed2003

Cuticular Architecture of Hassalstrongylus epsilon (Nematoda: Trichostrongyloidea).

Hassalstrongylus epsilon is a small nematode, whose adult forms are found among the intestinal microvilli of the water rat Nectomys squamipes, Brants 1827 (Rodentia: Muridae). The external appearance of the cuticle, which presents transversal striations and longitudinal ridges, is described using scanning electron microscopy. Transmission electron microscopy of thin sections and replicas of quick-frozen, freeze-fractured, deep-etched and rotatory shadowed samples showed the presence in the cuticle of struts that arise from the fluid median layer, extending outward to the epicuticle. The cuticle showed the presence of five layers: epicuticle, cortical, fibril-rich, fluid median and fibrous. The cuticle layers were made of an assemblage of fibers that create compartments, which were larger in the fluid region than in the fibril-rich median layer.

Animals↗
PubMed2004

Ultrastructure of the spermatozoon of the anoplocephalid cestode Gallegoides arfaai (Mobedi and Ghadirian, 1977) Tenora and Mas-Coma, 1978, an intestinal parasite of the wood mouse (Apodemus sylvaticus Linnaeus, 1758).

The present work involves an ultrastructural study of the mature spermatozoon of the anoplocephalid cestode Gallegoides arfaai (Mobedi and Ghadirian, 1977) Tenora and Mas-Coma, 1978, obtained from the small intestine of naturally infected wood mice, Apodemus sylvaticus Linnaeus, 1758 (Rodentia, Muridae). The mature spermatozoon of G. arfaai is a filiform cell, tapered at both ends and lacking mitochondria. It is characterized by the presence of a 1,000-nm-long apical cone and two 140-nm-thick crest-like bodies in its anterior extremity. The axoneme, of the 9 + '1' trepaxonematan pattern, lacks a periaxonemal sheath, and disorganization occurs at the level of the nuclear region of the sperm cell. The cortical microtubules form two to four fields according to the different regions of the male gamete. They are twisted at an angle of about 35 degrees , becoming parallel towards the posterior extremity of spermatozoon. The nucleus, spiralled around the axoneme, shows an irregular shape in both longitudinal and cross-sections. Numerous electron-dense granules were observed, which transform into an electron-dense material in the posterior extremity of the cell. Moreover, we describe for the first time the total length of the anterior region of sperm containing the helical crest-like bodies. This anterior extremity measures around 15 mum and presents two helical crest-like bodies of different lengths that describe 13-14 turns around the sperm body. Our ultrastructural results on the G. arfaai spermatozoon are compared with the ultrastructural organization of the spermatozoa of other previously studied species, with particular emphasis on the anoplocephalids.

Animals↗
PubMed2005

Disruption of myofibrillar proteins in cardiac muscle of Calomys callosus chronically infected with Trypanosoma cruzi and treated with immunosuppressive agent.

Calomys callosus (Rodentia: Cricetidae) chronically infected with CL strain of Trypanosoma cruzi undergo recrudescence of the acute phase when treated with the immunosuppressor cyclophosphamide. The distribution of cytoskeletal proteins in cardiac tissue of immunosuppressed animals was mapped by immunofluorescence and electron microscopy to evaluate myofibrillar distribution during the intracellular life cycle of T. cruzi. Cardiac muscle sections showed enhancement of myocarditis and parasite proliferation after immunosuppression. Immunofluorescence using monoclonal antibodies against myosin, actin, desmin, titin, tropomyosin, and troponin T demonstrated disruption and loss of contractile proteins, such as myosin and actin. Desmin and titin were irregularly distributed in close proximity to parasite nests. Ultrastructural observations confirmed alterations of cardiac cells with Z-line fragmentation, indistinguishable I-bands and A-bands, and loss of myofibrillar elements. The disruption of the muscle cell architecture was greater as infection progressed, probably as a result of increased myocarditis and physical displacement due to the activity of flagellated parasites.

Animals↗
PubMed2005

Allozymic polymorphism among 14 populations of the house mouse, Mus musculus domesticus, from Greece.

Nineteen loci from 239 individuals of the house mouse Mus musculus domesticus (Rodentia, Muridae) were analyzed by means of thin layer electrophoresis. The mice were collected from 14 localities of Greece mainly confined to the area of NW Peloponnese, where a Robertsonian (Rb) system is observed. The individuals were chromosomally characterized by nine diploid numbers, the 2n = 24, 26, 27, 28, 29, 30, 31, 32, and 40. The statistic elaboration revealed that all 14 populations studied were not characterized by cohesive demic structure and high inbreed levels while the gene flow among them has resulted in low levels of genetic differentiation. The resulting values for Nei's genetic distance corresponded to distances known for the level of geographical populations of M. musculus. Wagner's cladogram for the phylogenetic relations between the populations studied implied that it is the diploid number, rather than the geographical factor, that characterizes or dominates each population, which mainly influences the phylogenetic relationships.

Animals↗
PubMed1992

Cloning and sequencing of mouse collagenase cDNA. Divergence of mouse and rat collagenases from the other mammalian collagenases.

Mouse collagenase cDNA was cloned and sequenced. The deduced amino acid sequence was compared to those of the other mammalian collagenases and related matrix metalloproteinases. These comparisons, as well as those of some enzymatic properties, show that the rodent (mouse and rat) interstitial collagenases are very similar but differ more from the other interstitial collagenases than does human neutrophil collagenase. This supports the hypothesis that the order Rodentia is an outgroup to the other eutherian (placental) mammalian orders.

Amino Acid Sequence↗
PubMed1992

Seasonal variations of androgens and of several sexual parameters in male Meriones shawi in southern Morocco.

Seasonal changes of several parameters related to sexual activity were studied in the gerbil (Rodentia: Gerbillidae). The weight of the testes, seminal vesicles, and adrenals fluctuate throughout the year. Plasma androgen levels and histological aspect of the testes also vary throughout the year. Spermatogonial and steroid activities are synchronous and are maximal in winter and spring. The relationship between these activities and environmental climatic parameters is discussed: the beginning of sexual activity seems correlated with the first rains.

Adrenal Glands↗
PubMed1984

The eta-globin gene. Its long evolutionary history in the beta-globin gene family of mammals.

In phylogenetic reconstructions by the parsimony method, utilizing 62 sequenced globin genes and pseudogenes (including 34 of the beta-globin gene family from eutherian orders Primates, Lagomorpha, Artiodactyla and Rodentia), the branch of primate psi beta pseudogenes and the goat embryonically expressed epsilon II gene group monophyletically together as orthologues of a common ancestral gene (labelled eta) distinct from orthologues of epsilon, gamma, delta and beta. This primate psi eta-goat eta branch is cladistically closer to epsilon and gamma than to delta and beta branches. In each eutherian order gene conversions replaced portions of delta by beta sequences, whereas in descent of Primates epsilon, gamma and eta mostly retained their separate ancient identities predating the radiation of Eutheria in all their exons and non-coding regions. The loci of the ancestral beta-globin gene cluster in basal eutherians and proto-primates, as deduced from beta-clusters representing the four eutherian orders, were linked 5'-epsilon-gamma-eta-delta-beta-3' with epsilon, gamma and eta being embryonically expressed genes, and delta and beta ontogenetically later expressed genes. Through deletions gamma was lost in artiodactyl evolution, eta in lagomorph and rodent evolution, and all DNA between exon 2 3' boundaries of eta and delta in prosimian lemuriform evolution (lemur having the hybrid pseudogene psi eta delta). Simian primates retained intact the five loci of the ancestral cluster. Not only did eta, after it became a pseudogene in the basal primates, persist intact in descent to present-day simians but in the line to hominoids it evolved during the last 40 million years at the decelerated rate of 1 X 10(-9) substitutions/site per year which is one-fifth the expected neutral rate. The possibility is suggested that the psi eta locus situated between fetal and adult chromosomal domains of the simian beta-globin gene cluster might play some role in a mechanism for ontogenetic switches of globin gene expression. However, not enough sequence data on genes and intergenic regions in DNA of species of primates and other mammals as yet exist to know if the slow rate of 1 X 10(-9) reflects the rate of a conserved functional gene or primarily reflects a decelerated neutral rate of hominoid DNA evolution, conceivably from enhanced DNA repair and longer generation times in hominoids. The further possibility is raised that gene correction (repair of damaged DNA that prevents emergence of new alleles) and gene conversion both more often involve strand copying of conserved than of rapidly evolving DNA.

Animals↗
PubMed1993

Lack of potassium-anion interaction in diet selection by captive meadow voles.

An experiment was conducted to test whether selective avoidance of high-potassium diets by captive meadow voles (Rodentia: Microtus pennsylvanicus) depends on the anions with which potassium is associated. Voles were presented simultaneously with a) low- and high-potassium diets formulated with either potassium sulfate, potassium chloride, or a mixture of potassium chloride and potassium citrate; or b) paired combinations of high-potassium diets containing different anions. In the first part of the experiment, voles preferentially selected the low-potassium diets, with the degree of selectivity virtually completely independent of the associated anion. These results confirm previous suggestions that potassium avoidance may be a component in diet selection by herbivores, especially during spring and summer. There is only weak indication that anion content affects selection of diets with fixed potassium content.

Animals↗
PubMed1987

Species specific sensitivity towards the hemorrhagin of Ophiophagus hannah (Elapidae).

The filtration pattern of Ophiophagus hannah venom on Sephadex G-75 shows several peaks. The first peak, S1, includes high molecular weight proteins and contains the hemorrhagic and proteolytic activities. The proteolytic fractions overlap the hemorrhagic fractions, but are not identical with them. The crude venom and the high molecular weight peak have caseinase, benzoyl-L-arginine ethyl ester hydrolase and kallikrein-like activities, but not collagenase, gelatinase, thrombin, plasmin or urokinase-like activities. The hemorrhagin of Ophiophagus hannah shows species specific differences in its hemorrhagic effects: it causes hemorrhages in rabbits and hares (Lagomorpha), but not in rats, mice or guinea-pigs (Rodentia).

Animals↗
PubMed1988

Organization of repetitive DNAs in the guinea pig genome.

Investigation of restriction enzyme families observed in Bam HI and Eco RI digest of guinea pig DNA has led to the demonstration of a 4.0 kb cryptic satellite called MRICp which has 6300 copies and comprises 1% of the total genome. MRICp has been shown to encompass the Eco RI 4.0 kb family, the Bam HI 3.4 kb family and the Bam HI 3.7 kb family. The 1.5 kb Eco RI family is part of an L1 LINE that is present in the guinea pig and in other rodentia. It is part of a larger LINE, probably 6.5 to 7 kb in size, and some copies are embedded in satellite I DNA sequences.

Animals↗
PubMed1983

Identification of fetuin in human and rat fetuses and in other species.

The fetal protein, fetuin, has previously only been identified in species belonging to the order Artiodactyla. Samples of fetal, newborn and adult human (Homo sapiens) and rat (Rattus norvegicus) plasma and tissues have been studied using three techniques: (a) crossed immunoelectrophoresis of plasma against each of four different anti-fetuin antisera (two anti-cattle, one anti-pig and one anti-sheep); (b) the peroxidase-antiperoxidase technique applied to agarose gels containing plasma spots; (c) the indirect immunoperoxidase technique applied to human fetal tissue sections. In human fetal samples all three methods gave evidence for the presence of fetuin except late in gestation and in the newborn. Adult plasma was negative. In rat fetuses only plasma was tested, by methods (a) and (b). Positive reactions were obtained for both fetal and adult samples; the fetal samples cross-reacted with several of the anti-fetuins, adult samples reacted with only one. All the fetal and embryonal plasma samples tested with the peroxidase-antiperoxidase method were positive for fetuin except for the chicken. Thus fetuin appears to be distributed in at least five mammalian orders (Artiodactyla, Primates, Rodentia, Carnivora and Perissodactyla).

Animals↗
PubMed1993

Seasonal changes of blood values in the Andean mouse Abrothrix andinus.

1. Biomonthly measurements of hematological indices were conducted in freshly captured Abrothrix andinus (Rodentia:Cricetidae) over a period of one year. 2. All blood values were in the same range for adult males and females, but juveniles showed lower red blood cell counts (RBC) and erythrocytes of larger size. 3. High RBC numbers, a slight but significant increase of blood hemoglobin concentration (Hb), and a significant decrease in mean cell volume (MCV) were found during the winter months. 4. Hematocrit values (Hct) and the mean cell Hb concentration (MCHC) were relatively constant throughout the year. 5. Plasticity of MCV and an inverse correlation between size and the number of RBC may provide an enlarged diffusion area during winter. This mechanism appears to be a useful seasonal adjustment, since the increase of Hct and the concurrent increase in blood viscosity are avoided.

Animals↗
PubMed1993

Nutritional ecophysiology of the Andean mouse Abrothrix andinus: energy requirements, food quality and turnover time.

1. Abrothrix andinus (Rodentia: Cricetidae) is a small winter active mammal inhabiting the Andes range, enduring seasonal changes in food quality and ambient temperatures. 2. This species responds to seasonal changes in food quality and energy need by seasonal changes in nutrient transport by the small intestine. 3. Here I document significant increased digestive turnover time of individuals maintained under low food quality and high energy needs (Anova, P < 0.001). 4. Contrary to predictions, multifactorial Anova revealed that food quality did not explain the higher than expected turnover time. In this case, increased energy needs (low ambient temperature) appears to be of greatest importance. 5. Exposed to cold environmental conditions and/or under limitations in food quality and abundance, winter active small mammals may enhance their digestive efficiency by retaining food in their digestive tract for as long as possible.

Animal Nutritional Physiological Phenomena↗
PubMed1979

Chondroitin sulfates of the epiphysial cartilages of different mammals.

1. The distribution chondroitin 4- and 6-sulfates in the epiphysial cartilages of several mammals are reported. 2. Chondroitin 6-sulfate is present in higher relative proportion in articular surfaces of young and adult epiphysial cartilages in most of the mammals studied. 3. Exception to this was found in some species of the order Rodentia in which chondroitin 4-sulfate was almost the only chondroitin present in young and adult cartilages. 4. These and other results suggest that chondroitin 4-sulfate may be an important component for the calcification process, whereas chondroitin 6-sulfate seems to be related to the integrity of the articular surfaces.

Aging↗
PubMed1985

Comparative studies on glucose phosphorylating isoenzymes from vertebrates--VIII. Immunochemical studies on mammalian hexokinases A.

An immune serum elicited in a rabbit by injection of homogeneous brain hexokinase A was shown to be specific for the antigen. Other rat hexokinase isoenzymes (hexokinases B, C or D) did not present cross-reaction when tested by immunoinhibition of enzyme activity, double immunodiffusion and immunoadsorbent columns. The enzyme activity of hexokinase A from several mammals (rodents, lagomorphs, artiodactyls) was partially inhibited by the immune serum. In the case of mouse enzyme, the amount of serum required to inhibit 50% of the activity was five-fold higher than in the case of the rat enzyme. Enzymes from cow or sheep brain were only marginally affected. Hexokinases A isolated from various mammals, tested against the rat enzyme, showed faint lines of precipitation and marked spurs in double immunodiffusion plates even when enzymes from closely related rodents were analyzed. Immunoadsorbent columns, on the other hand, were able to retain most of the activity of hexokinases A from the mammals studied. Micro-complement fixation tests showed that hexokinases A from mammals outside the Order Rodentia were only partially recognized by the anti-hexokinase Arat serum. The results suggest that amino acid substitutions on the hexokinase A molecule have occurred at a rather fast rate.

Animals↗
PubMed1989

Species-dependent differences in ATP half-life of glucose deprived crystalline lens.

1. Significant differences were detected by 31P NMR spectroscopic techniques in the intrinsic rate of ATP hydrolysis by crystalline lenses from adult Macaca mulatta, Saimiri sciureus, Felis catus, Sus, Canis familiaris, Cavia rodentia and Oryctalagis cuniculus during exogenous glucose deprivation. 2. These differences were not attributable to differences in endogenous glycogen stores, and appear instead to emanate from comparative species differences in lenticular enzyme activities.

Adenosine Triphosphate↗