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PubMed2004

Evolutionary strata on the mouse X chromosome correspond to strata on the human X chromosome.

Lahn and Page previously observed that genes on the human X chromosome were physically arranged along the chromosome in "strata," roughly ordered by degree of divergence from related genes on the Y chromosome. They hypothesized that this ordering results from a historical series of suppressions of recombination along the mammalian Y chromosome, thereby allowing formerly recombining X and Y chromosomal genes to diverge independently. Here predictions of this hypothesis are confirmed in a nonprimate mammalian order, Rodentia, through an analysis of eight gene pairs from the X and Y chromosomes of the house mouse, Mus musculus. The mouse X chromosome has been rearranged relative to the human X, so strata were not found in the same physical order on the mouse X. However, based on synonymous evolutionary distances, X-linked genes in M. musculus fall into the same strata as orthologous genes in humans, as predicted. The boundary between strata 2 and 3 is statistically significant, but the boundary between strata 1 and 2 is not significant in mice. An analysis of smaller fragments of Smcy, Smcx, Zfy, and Zfx from seven species of Mus confirmed that the strata in Mus musculus were representative of the genus Mus.

Animals↗
PubMed2004

Ectoparasites of the Pallas squirrel, Callosciurus erythraeus, introduced to Japan.

The squirrel Callosciurus erythraeus (Pallas) (Rodentia: Sciuridae) was intentionally introduced to Japan in 1935 and has become established throughout much of the country. Although they live mainly in forests, Pallas squirrels come into gardens and are frequently fed by people or kept as pets, so their ectoparasites could be of potential medical as well as veterinary importance. During 2001-2003 we conducted the first ectoparasite survey of Pallas squirrels in Japan. From 105 C. erythraeus captured in Kamakura District of Kanagawa Prefecture on Honshu Island, three types of ectoparasite were found: 52 specimens of the sucking louse Neohaematopinus callosciuri Johnson (Anoplura: Haematopinidae), 26 fleas Ceratophyllus (Monopsyllus) anisus Rothschild (Siphonaptera: Ceratophyllidae) and four nymphs of the tick Haemaphysalis flava Neumann (Acari: Ixodidae) on 22, 13 and one squirrels, respectively. Evidently in Japan C. erythraeus carries relatively few ectoparasite species; this may be a contributory factor to their invasive success. Further investigations are needed to assess risks of zoonotic transmission of plague or murine typhus by C. anisus, of louse-borne typhus by N. callosciuri and of tularaemia and especially Japanese spotted fever (Rickettsia japonica) by H. flava.

Animals↗
PubMed2003

Mitochondrial and Wolbachia markers for the sandfly Phlebotomus papatasi: little population differentiation between peridomestic sites and gerbil burrows in Isfahan province, Iran.

In Iran, Phlebotomus papatasi (Scopoli) (Diptera: Psychodidae) is the main vector of Leishmania major Yakimoff & Schokhor (Kinetoplastida: Trypanosomatidae), the causative agent of rural zoonotic cutaneous leishmaniasis. This sandfly is abundant both in villages and in the burrows of the main reservoir host, the gerbil Rhombomys opimus (Licht.) (Rodentia: Gerbillidae). Populations of P. papatasi were sampled from the edges of villages in Isfahan province, using CDC miniature light traps in peridomestic sites and sticky papers placed at the entrances to gerbil burrows. Single peridomestic sites in two northern provinces were also sampled. Individual sandflies were characterized by PCR amplification and sequencing of fragments of their mitochondrial cytochrome b gene and of the wsp gene of endosymbiotic Wolbachia pipientis Hertig (alpha-Proteobacteria: Rickettsiaceae). The distributions of the haplotypes of these two maternally inherited genes were analysed to assess the population differentiation of P. papatasi, knowledge of which will be needed for planning control measures. For the first time these markers were used to characterize P. papatasi from gerbil burrows, and they indicated the absence not only of sympatric cryptic species but also of any long-term differentiation of lineages in different habitats. A single lineage of cytochrome b haplotypes was found, and both sexes in all populations had a high infection rate of the same A-group strain of Wolbachia (wPap). The distributions of cytochrome b haplotypes were consistent with females dispersing more than males, which has been reported for P. papatasi in other countries. The widespread distribution of wPap suggests that Wolbachia could be used to spread transgenes between populations of P. papatasi in different habitats.

Animals↗
PubMed2004

Development of microarray-based diagnostics of voles and shrews for use in biodiversity monitoring studies, and evaluation of mitochondrial cytochrome oxidase I vs. cytochrome b as genetic markers.

Molecular methods are widely used for species identification of mammals. In particular, the mitochondrial cytochrome b gene sequence has proven helpful for this purpose. Microarray technology can now open up new perspectives for biodiversity monitoring. With microarrays, many thousands of genetically based characteristics can be tested on one microscopic glass slide called a 'chip'. A 'Mammalia-Chip', for example, could include redundant diagnostic markers to unambiguously identify all European mammal species. Of broader use, and therefore economically more relevant, could be a 'Biodiversity-Chip', containing diagnostic features to distinguish key species in the taxa of bacteria, lichen, molluscs, insects, fungi, mammals, etc. An important prerequisite for any mixed-phyla chip is a standardization of methods. One of the most promising genes as a universal marker for all eukaryotes is cytochrome oxidase I. We show that cytochrome oxidase I is adequate for the discrimination of different species of voles and shrews with cluster analysis. Based on these results we present a diagnostic microarray-chip using cytochrome oxidase I sequences for the identification of three species of Sorex (Soricidae, Insectivora) and four species of Microtus (Arvicolinae, Rodentia). We conclude that cytochrome oxidase I can be used as an alternative marker to cytochrome b in a mixed-phyla chip, or both genes can be used in combination to enhance redundance and thus robustness of a specific chip including small mammals.

Animals↗
PubMed1983

Dogfish insulin. Primary structure, conformation and biological properties of an elasmobranchial insulin.

Insulin from an elasmobranch, the spiny dogfish (Squalus acanthias) has been purified to near homogeneity by means of acid-ethanol extraction and salt precipitation. The amino acid sequences of the performic-acid-oxidised A and B chains have been determined and exhibit some unusual features. The A chain contains a total of 22 amino acids; only the insulin from coypu (a member of the Rodentia suborder, Hystricomorpha), has previously been reported to contain an extension past the A21 asparagine. The B10 histidine, which is involved in the formation of the insulin hexamers in higher vertebrates through the co-ordination of zinc, is present in this elasmobranch insulin. Several substitutions relative to bovine insulin occur in the proposed receptor binding region (A5Gln leads to His, B21Glu leads to Pro, B22Arg leads to Lys, B25Phe leads to Tyr). In spite of these substitutions, the maximal response in the rat epididymal fat cell assay is the same for bovine and dogfish insulins; the concentration required to produce the half-maximal response is, however, approximately threefold greater for dogfish insulin than that of bovine insulin. The use of interactive computer graphics model-building predicts that the dogfish insulin can attain a three-dimensional structure very similar to that of bovine insulin; circular dichroic spectra are presented which support the model-building studies.

Adipose Tissue↗
PubMed1991

Vitamin A (retinol and retinyl esters), alpha-tocopherol and lipid levels in plasma of captive wild mammals and birds.

Vitamin A (retinol and retinyl esters), vitamin E and lipids were determined in a wide variety of wild mammals and birds held in captivity. In mammals plasma levels of vitamin A were generally below 500 ng/ml and those of vitamin E were highly variable (0.1-2 micrograms/ml). In primates, vitamin E levels were 3 to 8 micrograms/ml. Whereas in Marsupialia, Chiroptera, primates, Rodentia, Proboscidea, Sirenia, Perissodactyla and Artiodactyla only retinol was found, retinyl esters (basically retinol palmitate/oleate) represented 10 to 50% of the total plasma vitamin A in some birds of the order Ciconiiformes and Falconiformes. Retinol levels in birds were higher compared to mammals (500-2,000 ng/ml). The same was true for lipids as well as for vitamin E levels (1-26 micrograms/ml) in the plasma of birds.

Animals↗
PubMed1984

Taxonomy and review of the coccidian genus Cryptosporidium (protozoa, apicomplexa).

Reports of Cryptosporidium in various hosts and cross-transmission experiments are reviewed. Cryptosporidium has been found in mammals (Primates, Artiodactyla, Perissodactyla , Carnivora, Lagomorpha, and Rodentia), birds, reptiles, and fish. The only cross-transmission attempts that have been made have been from mammals to other mammals and to a few birds. Names have been given to 19 "species," but it is concluded that only four of these should be considered valid at present. These are: C. muris Tyzzer, 1907 in mammals, C. meleagridis Slavin , 1955 in birds, C. crotali Triffit , 1925 in reptiles, and C. nasorum Hoover , Hoerr , Carlton , Hinsman & Ferguson, 1981 in fish.

Animals↗
PubMed1989

The behavior during pachynema of a normal and an inverted Y chromosome in Microtus agrestis.

The pachytene behavior of the chromosomes of Microtus agrestis (L.) (Rodentia, Arvicolidae) males carrying either the standard, or the pericentrically inverted Lund Y chromosome have been examined by electron microscopy of microspread spermatocytes. There is no synapsis between the X and either the standard or the Lund Y chromosomes during any substage of pachynema. Since synapsis is generally considered a prerequisite for crossing over, there appears to be no opportunity for crossover or chiasma formation between the X and Y in this species. The G-, C- and NOR-banded mitotic karyotypes of animals carrying the standard and Lund Y are also presented.

Animals↗
PubMed1989

Absence of synapsis during pachynema of the normal sized sex chromosomes of Microtus arvalis.

The pachytene behavior of the chromosomes of males of Microtus arvalis (Pall.) (Rodentia, Arvicolidae) was examined by electron microscopy in microspread preparations of spermatocytes. There was no synapsis between the axes of these two chromosomes during this period. Since synapsis is universally considered a prerequisite for crossing over and chiasmata formation, disjunction of the sex chromosomes in this species prerequisite for crossing over and chiasmata formation, disjunction of the sex chromosomes in this species must be presumed to be achiasmatic. Unlike previously examined species with no synapsis or crossing over between the X and Y, the sex chromosomes of M. arvalis are of normal size: the X chromosome is of an "original" X size and the Y is a small acrocentric. C-band studies of M. arvalis mitotic metaphase reveal no blocks of heterochromatin on the sex chromosomes. The implications of these findings are discussed.

Animals↗
PubMed1981

Multiple paternity in Belding's ground squirrel litters.

Sexually receptive female Spermophilus beldingi (Rodentia: Sciuridae) usually mate with several different males. The paternity of 27 litters born in 1977 and 1978 was ascertained by combining field observations of mating with laboratory paternity exclusion analyses. Most of the litters (78 percent) were multiply sired, usually by two or three males. This may be the highest frequency of multiple paternity ever directly demonstrated in a natural population.

Animals↗
PubMed1985

Specificity of Fc receptors induced by herpes simplex virus type 1: comparison of immunoglobulin G from different animal species.

Cells infected with herpes simplex virus type 1 (HSV-1) express a cell surface receptor able to bind the Fc portion of immunoglobulin G (IgG). Of the four human IgG subclasses, the HSV-1 Fc receptor, like staphylococcal protein A, binds to all except IgG3. In this paper, we describe the binding of a number of animal IgG and IgG subclass molecules to HSV-1-infected cells and compare this binding to that of protein A. Although only few representatives from each animal order were tested, we found that IgG from Carnivora and Rodentia did not bind or bound only slightly to the HSV-1 receptor, whereas IgG from Primates, Lagomorpha, and Artiodactyla bound well. This pattern was clearly different from the species spectrum of IgG binding of protein A. Differences between the two receptors were also found when animal IgG subclasses were tested. The pronounced differences in affinity for the HSV-1 Fc receptor between immunoglobulins from, for example, mouse and rabbit may influence the interpretation of animal studies with this virus.

Animals↗
PubMed1996

Evolutionary rate variation within Mus APRT.

Rodents are thought to have relatively high rates of evolution, twice as fast as the rates for mammals in other orders. However, the uniformly high rates of evolution inferred for the order Rodentia from Mus musculus and Rattus norvegicus are not consistently found for other rodent species. Using a maximum likelihood phylogenetic algorithm (DNAML), we show here that Mus spicilegus has a fivefold different rate of evolution in 1100 bp around the adenine phosphoribosyltransferase gene (APRT) since its divergence from a common ancestor with Mus musculus. A greater than threefold difference in rates is also found in a comparison of the number of evolutionary events directly detected from the APRT sequences of these two closely related Mus species. The evolutionary events can be directly detected, since M. spicilegus, M. musculus, and the four rodent outgroup species used to determine the ancestral sequence are so closely related. One of the major differences between M. spicilegus and M. musculus that might affect evolutionary rate is the degree of commensalism with man. The Mus species therefore provide a useful model for testing various hypotheses for the causes of rate variations between genes, and possibly, between lineages.

Adenine Phosphoribosyltransferase↗
PubMed2003

Comparative analysis of expression and secretion of placental leptin in mammals.

Increased plasma level of leptin appears to be a ubiquitous feature of pregnant mammals. The mechanisms by which leptin levels are increased may be species specific, however, with some species upregulating adipose leptin production and others expressing leptin in the placenta. Placental leptin expression was examined in representative species of the two most abundant mammalian orders, Rodentia and Chiroptera, and in cultured human choriocarcinoma (BeWo) cells. Leptin mRNA was expressed in BeWo cells and in placentas of Myotis lucifugus (little brown bat), Eptesicus fuscus (big brown bat), and Rattus norvegicus (laboratory rat), but not the common laboratory mouse Mus musculus. cAMP stimulated secretion of leptin from BeWo cells and also stimulated leptin mRNA expression in the cells. In addition to adipose and placental tissue, leptin transcript in M. lucifugus was detectable in heart, spleen, and liver, but not in lung, brain, and kidney. Hepatic expression was also observed in E. fuscus, but not in mice or rats, and did not appear to result from hepatic fat deposition. Leptin cDNA was cloned and sequenced from M. lucifugus placenta and shared up to 95% homology with other mammalian leptin cDNAs. It is concluded that 1) placental leptin expression and secretion are species-specific traits, 2) placental leptin production represents one of three major mechanisms for achieving high circulating maternal leptin levels during pregnancy, the others being upregulation of adipose leptin production and production of circulating leptin-binding proteins, and 3) hepatic leptin expression in pregnant insectivorous bats may be an adaptation resulting from the presence of extremely low amounts of subcutaneous fat during pregnancy and lactation in these species.

Adipose Tissue↗
PubMed2006

Comparative mapping of cattle chromosome 19: cytogenetic localization of 19 BAC clones.

Here we present the results of fluorescent in situ hybridization (FISH) mapping of a set of cattle BAC clones preselected for assignment on cattle chromosome 19 (BTA19). The BAC clones were anchored to human chromosome 17 (HSA17) sequences by BLASTn similarity search of cattle BAC-ends against the human genome sequence (NCBI build 33). Five blocks of homologous synteny were defined in the comparative map of BTA19 and HSA17 built with FISH data and the human genome coordinates. The positions for four evolutionary breakpoints in the bovine and human chromosomes were identified. Comparison of the FISH comparative map with previously published comparative RH, physical, and cytogenetic maps of BTA19 did not reveal major conflicts and allowed for the extension of the boundaries of homology between BTA19 and HSA17. Comparative analysis of HSA17, BTA19, and mouse chromosome 11 (MMU11) demonstrates that most likely mice retain the ancestral organization of the synteny group, and both cattle and human chromosomes underwent several major internal rearrangements after the divergence of Primates, Rodentia, and Cetartiodactyla.

Animals↗
PubMed2006

Historical biogeography of the strepsirhine primates of Madagascar.

Lying some 400 km off the coast of southeastern Africa, Madagascar is the world's largest oceanic island. It has been in roughly the same position relative to its parent continent for 120 million years, and as a consequence its mammal fauna is unusual in composition, with a low number of major taxa but a high diversity at lower taxonomic levels. Among Madagascar's native terrestrial mammals, only the orders Primates, Rodentia, Carnivora and Insectivora are represented (plus, until recently, the enigmatic and endemic Bibymalagasia, and Artiodactyla in the form of semiaquatic pygmy hippopotamuses). This reflects the fact that terrestrial mammals are notoriously poor over-water dispersers; yet at the same time the ancestors of all of Madagascar's mammals had to have crossed a wide oceanic barrier to get to the island at various points during the Tertiary. Here I examine the palaeogeographic evidence for potential land bridge or 'stepping-stone' connections with adjacent continents from the Mesozoic through the Cenozoic, and review the fossil records and phylogenies of each of Madagascar's mammalian groups in an attempt to estimate the minimum number of crossings necessary to produce the island's current faunal composition. Probable monophyletic origins for each major group, and thus a smaller rather than a larger number of crossings of the Mozambique Channel, imply that this water barrier has acted as a powerful filter; so powerful that it is unclear whether any crossings would have been possible without some form of subaerial connection, however ephemeral, at least from time to time during the Tertiary. Clarification of how Madagascar's terrestrial mammal fauna may have originated is thus as likely to emerge from the geology of the seafloor surrounding the island as it is to come from the fossil record or from the internal and external relationships of its various components.

Animal Migration↗
PubMed1980

Phylogeny through brain traits. Relation of lateral olfactory tract fibers to the accessory olfactory formation as a palimpsest of mammalian descent.

In mammals the fibers of the dorsal lateral olfactory tract either pass under the accessory olfactory formation, or they penetrate through it separating the internal granule cells from the output cells. The use of this trait as a phylogenetic indicator in 181 specimens representing 131 species of 16 orders yielded evidence for common ancestry of Insectivora, Chiroptera, Dermoptera, Rodentia, and Primates (including Tupaia), since all share the derived trait, their dorsal lateral olfactory tract fibers passing through the accessory olfactory formation. Carnivora (including Pinnipedia), Hyracoidea, Perissodactyla, and most Artiodactyla share the primitive condition (fibers passing under) with the one order of monotremes and three marsupial orders. The Edentata and Lagomorpha may be separate from the two major placental groups and from each other, or they may represent successive stages in the evolution of the derived state through progressive alterations in the relative chronology of development of olfactory system components, or one or both orders may occupy an ancestral position with respect to the dichotomy within placental mammals.

Animals↗
PubMed1988

On the highest chromosome number in mammals.

The mitotic and meiotic chromosomes of the semiaquatic rodent Ichthyomys pittieri (Rodentia, Cricetinae) from Venezuela were analyzed by means of conventional staining and several banding techniques. The diploid chromosome number of this rare species is 2n = 92, which is the highest value known for mammals. It is assumed that this exceptionally high chromosome number is the result of repeated centric fissions. The karyotype of I. pittieri was compared with that of Anotomys leander, for which a diploid number of 2n = 92 has also been reported. The karyological relationships existing within the Neotropical Cricetidae are summarized.

Animals↗
PubMed1989

Synaptonemal complex study in some species of Gerbillidae without heterochromatin interposition.

Synaptonemal complexes were studied in Gerbillus campestris, Meriones libycus, M. shawi, M. crassus, and in two hybrids M. shawi x M. libycus (Gerbillidae, Rodentia). In both the pure species and hybrids, there was no pairing of X and Y chromosomes, as was previously observed in Psammomys obesus and other Gerbillidae species with gonosome-autosome translocations. A pair of autosomes was also located in proximity to the sex chromosomes in pachytene and showed unusual meiotic behavior with no, incomplete, or much delayed pairing. This chromosome pair, composed of late replicating heterochromatin, exists in most Gerbillidae species and is constant in number, but variable in size across the species. Both meiotic and mitotic characteristics indicate that this pair may correspond to a new type of chromosome which is different from B chromosomes. We do not know if there is a relationship between the presence of this chromosome and the unusual behavior of the sex chromosomes. In Gerbillidae species, the lack of pairing of both sex and heterochromatic chromosomes obviously does not prevent their correct meiotic segregation.

Animals↗