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PubMed1982

Morphological and biological features of Trypanosoma (Herpetosoma) mariae Mello, 1978 in experimentally infected Calomys callosus.

In this paper some observations on the biology of Trypanosoma (Herpatosoma) mariae, Mello, 1978 are presented. The experiments were carried out in Calomys callosus (Rodentia), reservoir of this parasite. The prepatent period varied from 6.6-10.5 days and the patent infection varied from 38-141 days. Amastigote forms in divisions were seen mainly among the cellular spaces of the spleen. Only trypomastigote forms were seen in the blood stream. Measurements of these forms showed that the total length varied with the course of the infection.

Animals↗
PubMed1986

[Two trichostrongyloid nematodes in an African murid. 1. Description of the adults].

Two new trichostrongyloids are described Neoheligmonella dossoi n. sp. and N. tranieri n. sp. concomitant parasites in the intestine of Uranomys ruddi (Rodentia-Muridae) from the Ivory Coast. N. dossoi differs from N. pseudospira and N. houini parasites of Arvicanthis abyssinicus in Ethiopia, by the length of the vestibule (longer than two thirds of the length of the infundibulum). N. tranieri is closely related to N. dossoi but can be differentiated by its longer uncoiled body and a characteristic synlophe.

Animals↗
PubMed1994

[Contribution to the study of Microphallidae travassos, 1920 (Trematoda). XLVI. Description of Floridatrema heardi n. gen., n. sp., parasite of Oryzomys palustris (Mammalia) of the United States].

The authors describe the adult of the trematode Floridatrema heardi n. gen, n. sp., parasite of the intestine of Oryzomys palustris (Mammalia:Rodentia) in Florida (USA). The new genus is placed among the Microphallidae, Maritrematidi, Maritrematinae, Maritrematini; near the genus Maritrema Nicoll, it is characterised by vitellaria in the form of a horseshoe and the anterior extension of two symmetrical uterine loops as far as the level of the pharynx, the left anterior uterine loop proceeding from the uterus proximally. The species lacks a spiny atrio-acetabular plate and concentric rings in the afferent sub-tegumentary musculature. The anotomical phenomenon of the anterior extension of the uterus in the Microphallidae is discussed.

Animals↗
PubMed2003

First record of Mastophorus muris (Gmelin, 1790) (Nematoda: Spiruroidea) from a wild host in South America.

Mastophorus muris (Gmelin, 1790) (Nematoda: Spiruroidea) is reported parasitizing the grey leaf-eared mouse Graomys griseoflavus (Waterhouse, 1837) (Rodentia: Sigmodontinae) from the province of La Pampa, Argentina. The distinct position of Mastophorus (Spirocercidae: Mastophorinae) and Protospirura (Spiruridae), sometimes still confused, is again confirmed. The pattern of pseudolabial teeth (a large central tooth with smaller teeth on each side), which seems to be rather stable in all known descriptions, is here confirmed with the aid of scanning electron microscopy. The finding represents the first record of the species in Argentina, but also from a wild host in South America. This indicates an expansion of the distribution range of the species, which, in the subcontinent, was hitherto restricted to domestic rodents.

Animals↗
PubMed1988

Evolutionary and developmental aspects of two hemoglobin beta-chain genes (epsilon M and beta M) of opossum.

A series of gene duplications that began in a stem species of Mammalia and led to five developmentally regulated hemoglobin beta-chain loci (epsilon, gamma, eta, delta, and beta) in a common ancestor of eutherian orders Artiodactyla, Rodentia, Lagomorpha, and Primates had important consequences in mammalian evolution. Findings reported here indicate that two progenitors of the five linked genes existed by the time of the eutherian (placental mammal)-metatherian (marsupial mammal) split and that these two genes were already differentiated with respect to their promoter regions and developmental expression. Southern blot and sequence analyses of the hemoglobin beta-chain genes of the opossum (Didelphis virginiana) revealed only two genes, one with coding and promoter sequences similar to eutherian prenatally expressed epsilon, gamma, and eta genes and the other coding for adult opossum hemoglobin beta-chains and having eutherian adult beta-type promoters. The most parsimonious arrangement of greater than 80 beta-globin exon sequences depicts the opossum embryonic-type gene as orthologously related to eutherian epsilon, gamma, and eta genes and the opossum adult-type gene as orthologously related to delta and beta genes. These data further indicate that after the initial beta duplication in the stem of Mammalia, the locus that became developmentally delayed in its expression evolved at a faster rate than the locus that became embryonically expressed.

Amino Acid Sequence↗
PubMed1990

Evolution of spatial cognition: sex-specific patterns of spatial behavior predict hippocampal size.

In a study of two congeneric rodent species, sex differences in hippocampal size were predicted by sex-specific patterns of spatial cognition. Hippocampal size is known to correlate positively with maze performance in laboratory mouse strains and with selective pressure for spatial memory among passerine bird species. In polygamous vole species (Rodentia: Microtus), males range more widely than females in the field and perform better on laboratory measures of spatial ability; both of these differences are absent in monogamous vole species. Ten females and males were taken from natural populations of two vole species, the polygamous meadow vole, M. pennsylvanicus, and the monogamous pine vole, M. pinetorum. Only in the polygamous species do males have larger hippocampi relative to the entire brain than do females. Two-way analysis of variance shows that the ratio of hippocampal volume to brain volume is differently related to sex in these two species. To our knowledge, no previous studies of hippocampal size have linked both evolutionary and psychometric data to hippocampal dimensions. Our controlled comparison suggests that evolution can produce adaptive sex differences in behavior and its neural substrate.

Animals↗
PubMed1999

Phylogenetic assessment of molecular and morphological data for eutherian mammals.

The interordinal relationships of eutherian (placental) mammals were evaluated by a phylogenetic analysis of four published data sets (three sequences and one morphological). The nature and degree of support and conflict for particular groups were assessed by separate bootstrap and homogeneity tests, which were followed by combined analyses of the sequence and morphological data. Between orders, strong support (i.e., > or = 95% bootstrap scores) was found for a paraphyletic Artiodactyla (relative to Cetacea) and a monophyletic Cetartiodactyla (Artiodactyla and Cetacea) and Paenungulata (Hyracoidea, Proboscidea, and Sirenia). In turn, some reasonable to strong evidence (> or = 85%) was obtained for Hyracoidea with Sirenia, Dermoptera with Scandentia, Glires (Lagomorpha with Rodentia), and Afrotheria (Amblysomus, Macroscelidea, Paenungulata, and Tubulidentata). Otherwise, no other interordinal clades were supported at these reasonable to strong levels. This overall lack of resolution for eutherian interordinal clusters agrees with other studies that suggest further progress will continue to be slow and difficult. Further resolution will require the integration of more recently published data, the continued sampling of taxa and characters, and the use of more powerful methods of data analysis.

Animals↗
PubMed1999

Additional support for Afrotheria and Paenungulata, the performance of mitochondrial versus nuclear genes, and the impact of data partitions with heterogeneous base composition.

We concatenated sequences for four mitochondrial genes (12S rRNA, tRNA valine, 16S rRNA, cytochrome b) and four nuclear genes [aquaporin, alpha 2B adrenergic receptor (A2AB), interphotoreceptor retinoid-binding protein (IRBP), von Willebrand factor (vWF)] into a multigene data set representing 11 eutherian orders (Artiodactyla, Hyracoidea, Insectivora, Lagomorpha, Macroscelidea, Perissodactyla, Primates, Proboscidea, Rodentia, Sirenia, Tubulidentata). Within this data set, we recognized nine mitochondrial partitions (both stems and loops, for each of 12S rRNA, tRNA valine, and 16S rRNA; and first, second, and third codon positions of cytochrome b) and 12 nuclear partitions (first, second, and third codon positions, respectively, of each of the four nuclear genes). Four of the 21 partitions (third positions of cytochrome b, A2AB, IRBP, and vWF) showed significant heterogeneity in base composition across taxa. Phylogenetic analyses (parsimony, minimum evolution, maximum likelihood) based on sequences for all 21 partitions provide 99-100% bootstrap support for Afrotheria and Paenungulata. With the elimination of the four partitions exhibiting heterogeneity in base composition, there is also high bootstrap support (89-100%) for cow + horse. Statistical tests reject Altungulata, Anagalida, and Ungulata. Data set heterogeneity between mitochondrial and nuclear genes is most evident when all partitions are included in the phylogenetic analyses. Mitochondrial-gene trees associate cow with horse, whereas nuclear-gene trees associate cow with hedgehog and these two with horse. However, after eliminating third positions of A2AB, IRBP, and vWF, nuclear data agree with mitochondrial data in supporting cow + horse. Nuclear genes provide stronger support for both Afrotheria and Paenungulata. Removal of third positions of cytochrome b results in improved performance for the mitochondrial genes in recovering these clades.

Animals↗
PubMed1998

Cloning and sequencing of the cDNA coding for pig pre-uteroglobin/Clara cell 10 kDa protein.

Using reverse transcription-polymerase chain reaction (RT-PCR) on pig lung mRNAs, we have cloned and sequenced an almost full-length complementary DNA (cDNA) coding for pig pre-uteroglobin/Clara cell 10 kDa protein (UG/CC10), a major secretory protein of lung Clara cells. The deduced amino acid sequence indicated a preprotein of 91 residues, 21 of which corresponded to the signal peptide. Comparison of the sequence with those of known pre-UG/CC10 from other species indicated that the pig protein resembles the structure shared by human and Lagomorpha pre-UG/CC10 but differ from the proteins from Rodentia that are composed of 96 aminoacids and contain signal peptides of 19 residues. Some amino acids, that form part of a hydrophobic pocket inside the mature protein, are well conserved in all UG/CC10 suggesting an important function of this cavity. Northern analysis indicated that pig UG/CC10 mRNA is abundant in lung but is not detectable in liver, uterus or epididymis. The results are discussed in relation to a possible physiological function of UG/CC10.

Animals↗
PubMed2000

Rates of nucleotide substitution and mammalian nuclear gene evolution. Approximate and maximum-likelihood methods lead to different conclusions.

Rates and patterns of synonymous and nonsynonymous substitutions have important implications for the origin and maintenance of mammalian isochores and the effectiveness of selection at synonymous sites. Previous studies of mammalian nuclear genes largely employed approximate methods to estimate rates of nonsynonymous and synonymous substitutions. Because these methods did not account for major features of DNA sequence evolution such as transition/transversion rate bias and unequal codon usage, they might not have produced reliable results. To evaluate the impact of the estimation method, we analyzed a sample of 82 nuclear genes from the mammalian orders Artiodactyla, Primates, and Rodentia using both approximate and maximum-likelihood methods. Maximum-likelihood analysis indicated that synonymous substitution rates were positively correlated with GC content at the third codon positions, but independent of nonsynonymous substitution rates. Approximate methods, however, indicated that synonymous substitution rates were independent of GC content at the third codon positions, but were positively correlated with nonsynonymous rates. Failure to properly account for transition/transversion rate bias and unequal codon usage appears to have caused substantial biases in approximate estimates of substitution rates.

Animals↗
PubMed2001

Divergent evolution in M6P/IGF2R imprinting from the Jurassic to the Quaternary.

M6P/IGF2R imprinting first appeared approximately 150 million years ago following the divergence of prototherian from therian mammals. Although M6P/IGF2R is clearly imprinted in opossums and rodents, its imprint status in humans remains ambiguous. It is also still unknown if M6P/IGF2R imprinting was an ancestral mammalian epigenotype or if it evolved convergently. We report herein that M6P/IGF2R is imprinted in Artiodactyla, as it is in Rodentia and Marsupialia, but that it is not imprinted in Scandentia, Dermoptera and Primates, including ringtail lemurs and humans. These results are most parsimonious with a single ancestral origin of M6P/IGF2R imprinting followed by a lineage-specific disappearance of M6P/IGF2R imprinting in Euarchonta. The absence of M6P/IGF2R imprinting in extant primates, due to its disappearance from the primate lineage over 75 million years ago, demonstrates that imprinting at this locus does not predispose to human disease. Moreover, the divergent evolution of M6P/IGF2R imprinting predicts that the success of in vitro embryo procedures such as cloning may be species dependent.

Animals↗
PubMed2005

Genome sizes in afrotheria, xenarthra, euarchontoglires, and laurasiatheria.

Topical literature and Web site databases provide genome sizes for approximately 4,000 animal species, invertebrates and vertebrates, 330 of which are mammals. We provide the genome size for 67 mammalian species, including 51 never reported before. Knowledge of genome size facilitates sequencing projects. The data presented here encompassed 5 Metatheria (order Didelphimorphia) and 62 Eutheria: 15 Xenarthra, 24 Euarchontoglires (Rodentia), as well as 23 Laurasiatheria (22 Chiroptera and 1 species from Perissodactyla). Already available karyotypes supplement the haploid nuclear DNA contents of the respective species. Thus, we established the first comprehensive set of genome size measurements for 15 Xenarthra species (armadillos) and for 12 house-mouse species; each group was previously represented by only one species. The Xenarthra exhibited much larger genomes than the modal 3 pg DNA known for mammals. Within the genus Mus, genome sizes varied between 2.98 pg and 3.68 pg. The 22 bat species we measured support the low 2.63 pg modal value for Chiroptera. In general, the genomes of Euarchontoglires and Laurasiatheria were found being smaller than those of (Afrotheria and) Xenarthra. Interspecific variation in genome sizes is discussed with particular attention to repetitive elements, which probably promoted the adaptation of extant mammals to their environment.

Animals↗
PubMed2006

Housekeeping genes for phylogenetic analysis of eutherian relationships.

The molecular relationship of placental mammals has attracted great interest in recent years. However, 2 crucial and conflicting hypotheses remain, one with respect to the position of the root of the eutherian tree and the other the relationship between the orders Rodentia, Lagomorpha (rabbits, hares), and Primates. Although most mitochondrial (mt) analyses have suggested that rodents have a basal position in the eutherian tree, some nuclear data in combination with mt-rRNA genes have placed the root on the so-called African clade or on a branch that includes this clade and the Xenarthra (e.g., anteater and armadillo). In order to generate a new and independent set of molecular data for phylogenetic analysis, we have established cDNA sequences from different tissues of various mammalian species. With this in mind, we have identified and sequenced 8 housekeeping genes with moderately fast rate of evolution from 22 placental mammals, representing 11 orders. In order to determine the root of the eutherian tree, the same genes were also sequenced for 3 marsupial species, which were used as outgroup. Inconsistent with the analyses of nuclear + mt-rRNA gene data, the current data set did not favor a basal position of the African clade or Xenarthra in the eutherian tree. Similarly, by joining rodents and lagomorphs on the same basal branch (Glires hypothesis), the data set is also inconsistent with the tree commonly favored in mtDNA analyses. The analyses of the currently established sequences have helped examination of problematic parts in the eutherian tree at the same time as they caution against suggestions that have claimed that basal eutherian relationships have been conclusively settled.

Animals↗
PubMed1997

Phylogenetic relationships of artiodactyls and cetaceans as deduced from the comparison of cytochrome b and 12S rRNA mitochondrial sequences.

A data set of complete mitochondrial cytochrome b and 12S rDNA sequences is presented here for 17 representatives of Artiodactyla and Cetacea, together with potential outgroups (two Perissodactyla, two Carnivora, two Tethytheria, four Rodentia, and two Marsupialia). We include seven sequences not previously published from Hippopotamidae (Ancodonta) and Camelidae (Tylopoda), yielding a total of nearly 2.1 kb for both genes combined. Distance and parsimony analyses of each gene indicate that 11 clades are well supported, including the artiodactyl taxa Pecora, Ruminantia (with low 12S rRNA support), Tylopoda, Suina, and Ancodonta, as well as Cetacea, Perissodactyla, Carnivora, Tethytheria, Muridae, and Caviomorpha. Neither the cytochrome b nor the 12S rDNA genes resolve the relationships between these major clades. The combined analysis of the two genes suggests a monophyletic Cetacea +Artiodactyla clade (defined as "Cetartiodactyla"), whereas Perissodactyla, Carnivora, and Tethytheria fall outside this clade. Perissodactyla could represent the sister taxon of Cetartiodactyla, as deduced from resampling studies among outgroup lineages. Cetartiodactyla includes five major lineages: Ruminantia, Tylopoda, Suina, Ancodonta, and Cetacea, among which the phylogenetic relationships are not resolved. Thus, Suiformes do not appear to be monophyletic, justifying their split into the Suina and Ancodonta infraorders. An association between Cetacea and Hippopotamidae is supported by the cytochrome b gene but not by the 12S rRNA gene. Calculation of divergence dates suggests that the Cetartiodactyla could have diverged from other Ferungulata about 60 MYA.

Animals↗
PubMed1998

The "five-sites" rule and the evolution of red and green color vision in mammals.

Amino acid changes S180A (S-->A at site 180), H197Y, Y277F, T285A, and A308S are known to shift the maximum wavelength of absorption (lambda max) of red and green visual pigments toward blue, essentially in an additive fashion. To test the generality of this "five-sites" rule, we have determined the partial amino acid sequences of red and green pigments from five mammalian orders (Artiodactyla, Carnivora, Lagomorpha, Perissodactyla, and Rodentia). The result suggests that cat (Felis catus), dog (Canis familiaris), and goat (Capra hircus) pigments all with AHYTA at the five critical sites have lambda max values of approximately 530 nm, whereas rat (Rattus norvegicus) pigment with AYYTS has a lambda max value of approximately 510 nm, which is accurately predicted by the five-sites rule. However, the observed lambda max values of the orthologous pigments of European rabbit (Oryctolagus cuniculus), white-tailed deer (Odocoileus virginianus), gray squirrel (Sciurus carolinensis), and guinea pig (Cavia procellus) are consistently more than 10 nm higher than the predicted values, suggesting the existence of additional molecular mechanisms for red and green color vision. The inferred amino acid sequences of ancestral organisms suggest that the extant mammalian red and green pigments appear to have evolved from a single ancestral green-red hybrid pigment by directed amino acid substitutions.

Amino Acid Sequence↗
PubMed1993

A major difference between the divergence patterns within the lines-1 families in mice and voles.

L1 retroposons are represented in mice by subfamilies of interspersed sequences of varied abundance. Previous analyses have indicated that subfamilies are generated by duplicative transposition of a small number of members of the L1 family, the progeny of which then become a major component of the murine L1 population, and are not due to any active processes generating homology within preexisting groups of elements in a particular species. In mice, more than a third of the L1 elements belong to a clade that became active approximately 5 Mya and whose elements are > or = 95% identical. We have collected sequence information from 13 L1 elements isolated from two species of voles (Rodentia: Microtinae: Microtus and Arvicola) and have found that divergence within the vole L1 population is quite different from that in mice, in that there is no abundant subfamily of homologous elements. Individual L1 elements from voles are very divergent from one another and belong to a clade that began a period of elevated duplicative transposition approximately 13 Mya. Sequence analyses of portions of these divergent L1 elements (approximately 250 bp each) gave no evidence for concerted evolution having acted on the vole L1 elements since the split of the two vole lineages approximately 3.5 Mya; that is, the observed interspecific divergence (6.7%-24.7%) is not larger than the intraspecific divergence (7.9%-27.2%), and phylogenetic analyses showed no clustering into Arvicola and Microtus clades.

Animals↗
PubMed1985

Location of enzymes of androgen and estrogen biosynthesis in the testis of the ground squirrel (Citellus lateralis).

The intratesticular localization of enzymes of androgen and estrogen biosynthesis was studied in the ground squirrel (Citellus lateralis). In mature animals, interstitium and tubules were isolated by manual dissection. Microsomes were prepared and enzymes assayed by analysis of product formation after incubation with appropriate 3H-labeled substrates. In the immature testis, tubules and interstitium are not readily separable; thus, distribution was inferred after analysis of whole testicular microsomes from control, follicle-stimulating hormone (FSH)-treated, and luteinizing hormone (LH)-treated animals. To verify the cellular composition of tissues and the status of steroidogenic organelles in Leydig and Sertoli cells, samples were also analyzed by light and electron microscopy. In mature squirrels, enzymes of androgen biosynthesis were concentrated in the interstitium; however, levels present in the tubules were sufficient to account for a substantial fraction of whole testicular activity (1/3 to 1/5). By contrast, virtually all of the testicular aromatase was accounted for by that in the seminiferous tubules. The purity of these fractions was checked by light microscopy; they showed little cross-contamination. In whole testicular microsomes of immature squirrels, androgen biosynthetic enzymes had a much lower specific activity than in mature animals; however, the opposite was true for aromatase, its activity being approximately 5-fold higher in prepubertal animals. Luteinizing hormone treatment markedly stimulated hydroxylase and lyase but not aromatase. Luteinizing hormone also induced an increase in Leydig cell size and a dramatic proliferation of smooth endoplasmic reticulum. These changes were correlated with increased serum testosterone. As shown previously in rats, 3 beta-hydroxysteroid dehydrogenase was independent of LH control. Follicle-stimulating hormone had no effect on any of the enzymes studied, but induced some increase of agranular reticulum in Sertoli cells. Results from immature squirrels thus corroborate data from mature animals, showing a predominant interstitial location of androgen biosynthetic enzymes. While we cannot explain the absence of FSH stimulation of aromatase activity, the data do not refute the findings in mature animals showing a predominant tubular location of this enzyme. We conclude that the distribution of steroidogenic enzymes in the testis of squirrels differs in several important respects from rats, although both are members of the order Rodentia.

3-Hydroxysteroid Dehydrogenases↗
PubMedDate not supplied

Expression of vascular endothelial growth factor in the lower urinary tract in rats after castration and estrogen administration.

OBJECTIVE: To evaluate quantitatively, by means of immune histochemistry, the expression of the vascular endothelial growth factor (VEGF) in the bladder, vesicourethral junction, and urethra in normal, castrated adult rats and under estrogen administration. DESIGN: Sixty adult virgin rats (Rattus norvergicus albinus, Rodentia, Mammalia) from the CEDEME-UNIFESP Animal House were used. Rats were divided into three groups. Group I comprised noncastrated rats, group II comprised oophorectomized rats, and group III comprised castrated rats administered 17beta-estradiol in the form of subcutaneous implants at the dose of 0.18 mg/implant for 30 days. After performing standard immunohistochemistry procedures, the intensity of the dark-brown color was used as the cytoplasmic protein expression of VEGF. Cells without this coloration or weakly stained were considered negative. percentile of VEGF expression was obtained by counting 1,000 cells per slide and establishing the ratio between positive and total cells. RESULTS: The VEGF expression was uniform and similar along the urinary tract in group I. After castration, protein expression was almost absent in the bladder and was low in the vesicourethral junction and urethra. With estrogen replacement, very little of the expression was recovered in the bladder, and the reaction became evident in the vesicourethral junction and urethral sections. CONCLUSIONS: The present study implies a potential relationship between VEGF and urinary tract physiology. The results suggest that there are quantitative differences in VEGF expression in these tissues depending on steroid hormone status.

Animals↗