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At least 325 records · Page 18Linked to original sources
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↗
PubMed1978

Comparative analysis of karyotypes in European shrew species. I. The sibling species Sorex araneus and S. gemellus: Q-bands, G-bands, and position of NORs.

The karyotypes of two closely related species of the genus Sorex (Mammalia, Insectivora) were compared with each other by G- and Q-banding techniques and by Ag-AS staining (GOODPASTURE and BLOOM, 1975). By comparing the G-banded karyotypes, it could be ascertained that the basic differences in karyotype between the two species lie in three pericentric inversions, three paracentric inversions, and one reciprocal translocation. This is in near agreement with FORD and HAMERTON (1970), who assumed that both species differ by three pericentric inversions and one tandem translocation. Furthermore, the karyotype of S. araneus (race C) presented by HALKKA et al. (1974) has been compared with the S. araneus of the present report. Considering the species with respect to karyotypic evolution, it is supposed that S. araneus and S. gemellus derive from a common ancestor.

Animals↗
PubMed1997

Localization of the genes for major ribosomal RNA on chromosomes of the house musk shrew, Suncus murinus, at meiotic and mitotic cells by fluorescence in situ hybridization and silver staining.

The genes for major ribosomal RNA were localized on chromosomes 5pter-p15, 9q64-qter, and 13q38-qter of the house musk shrew, Suncus murinus (Insectivora, Soricidae) by silver staining of mitotic metaphase and meiotic pachytene spreads and fluorescence in situ hybridization using the human 28S-RNA genes as a probe to mitotic metaphase spreads. The data presented indicate a correlation between sites of in situ hybridization and silver staining. The finding of nuclear materials in mitosis was in a good agreement with observation in meiosis: same chromosomes carried active NORs in both meiotic and mitotic cells.

Animals↗
PubMed1999

Sequence variation and evolution of the mitochondrial DNA control region in the musk shrew, Suncus murinus.

The complete mitochondrial DNA (mtDNA) control region was cloned and sequenced in the musk shrew, Suncus murinus, Insectivora. The general aspect was similar to that found in other mammals. We have found in two locations of this region the presence of arrays of tandem repeats like those in other shrew species. One array was located in the left domain containing the termination-associated sequences (TAS) and the length of a copy was 77 bp. The other repeats were situated upstream from the recognition site for the end of H-strand replication in the right domain and were 20 bp long. The left halves of the control region containing the former repeats were sequenced and compared in several laboratory lines and wild animals from different localities, variations in copy number of repeated sequences were found both among individuals and within an individual. A comparative study of repeated sequences provides useful indication for the origin and evolution of tandem repeated sequences. Strand slippage and mispairing during replication of mtDNA with concerted manner is currently regarded as a dominant theory to account molecular mechanism for tandemly repeated sequences, and the pattern of sequence and length variation in our study supports this theory. Our results, however, suggest that the evolution of the repeated sequences containing the TAS in the musk shrew might go through the process of two steps; at the first step one complete repeated and several incomplete repeated sequences had reproduced in common ancestor of the shrew, and the second stage step-up of complete repeated sequences occurred with concerted evolution after differentiation into continental and insular groups.

Animals↗
PubMed1996

Discovery of mammalian hosts to Gnathostoma nipponicum larvae and prevalence of the larvae in rodents and insectivores.

From September 1993 to November 1995, to clarify the natural infection of Gnathostoma nipponicum (G.n.) larvae in small wild mammals, a total of 313 animals consisted of three species of rodents and two species of insectivores, collected from an endemic area of this nematode in Aomori Prefecture, were investigated. Two species, Rattus norvegicus (R.n.) and Chimarrogale himalayica (C.h.) were infected with G.n. larvae, and the infection rate was extremely high with 27.2% and 72.7% in the former and latter. The infected animals harbored the larvae of 2-10 (mean: 6.0) in R.N. and 2-40 (10.6) in C.h., and a total of 273 larvae was recovered. The all larvae (18) from R.n. and the vast majority of the larvae (216/255: 82.4%) from C.h. were recovered from the musculature, and many encapsulated larvae were found in these portions of C.h. Taxonomically, all the larvae were identified as the advance third-stage larvae (AdL3) of G.n. The body length was 1,056-2,110 microns, and was larger than those of the naturally-infected AdL3 reported from cold-blooded animals. No morphological alterations or death of the larva was observed. From these results, it would seem that R.n. and C.h. are highly susceptible to G.n. larvae, and has very suitable characteristics as the hosts. Furthermore, a hypothesis is advanced that these mammals serves as the plausible paratenic hosts in the life cycle of G.n. This report is the first record of R.n. (Rodentia) and C.h. (Insectivora) naturally-infected with AdL3 of G.n.

Animals↗
PubMed2001

Cycle of the seminiferous epithelium in the Java fruit bat (Pteropus vampyrus) and the Japanese lesser horseshoe bat (Rhinolophus cornutus).

The cycle of the seminiferous epithelium in the Java fruit bat, Pteropus vampyrus, and the Japanese lesser horseshoe bat, Rhinolophus cornutus, was investigated by light microscopy and the characteristics of spermiogenesis were compared between these two species. In the Java fruit bat, the cycle of the seminiferous epithelium was divided into 11 stages and developing spermatids were subdivided into 13 steps. While in the Japanese lesser horseshoe bat, the cycle of the seminiferous epithelium was divided into 10 stages and developing spermatids were subdivided into 13 steps. Excepting slight morphological differences, the characteristics of acrosomal formation in both species were almost similar with each other. In the Java fruit bat after stage VII, the acrosome gradually elongated, flattened and finally became scoop-like in shape. In the Japanese lesser horseshoe bat after stage VIII, the acrosome elongated, flattened and then slightly shortened. Before spermiation, the acrosome became long spatula-like in shape. The elongation and flattening of spermatids in these two species were similar to those in insectivores. The finding may reflect the fact that the order Chiroptera is phylogenetically close to the order Insectivora.

Acrosome↗
PubMed1999

Reproductive features of the eastern mole (Scalopus aquaticus) and star-nose mole (Condylura cristata).

Since moles are closely related to shrews, the gametes and reproductive tracts of the star-nose mole (Condylura cristata) and the eastern mole (Scalopus aquaticus) were examined to gain further insight into unusual reproductive traits of the Soricidae. Moles display many of these soricid traits, but with some important differences. The cumulus oophorus of Scalopus, ovulated about 16 h after hCG injection, was largely dispersed by hyaluronidase and, though quite dense, was nevertheless more similar to that of higher mammals than to the compact 'ball of the soricid cumulus. Within the female tract in these moles, approximately 85% of the length of the oviduct comprises a narrow ampulla with numerous differentiated crypts that, in shrews, house spermatozoa. However, in contrast to shrews, moles produce considerably larger numbers of spermatozoa, which challenges the proposal that, in shrews, oviductal sperm crypts specifically permit lower sperm production by the males. In the sperm head of these two moles, the acrosome displays the long rostrum that is typical of other Insectivora, and the perforatorium has the barbs by which soricid spermatozoa probably bind to the zona pellucida. Perhaps allied to this, immunoblots indicated that the immunoreactive acrosomal matrix of Scalopus spermatozoa is simpler than the polypeptide complex of the bovine and hamster acrosomal matrix.

Animals↗
PubMed2000

Reproductive characteristics of the african pygmy hedgehog, atelerix albiventris.

To obtain further perspective on reproduction and particularly gamete function among so-called primitive mammals presently grouped in the Order Insectivora, we have examined the African hedgehog, Atelerix albiventris, in light of unusual features reported in shrews and moles. Atelerix proves to share many but not all of the characteristics seen in these other insectivores. The penis of Atelerix has a 'snail-like' form, but lacks the surface spines common in insectivores and a number of other mammals. Hedgehog spermatozoa display an eccentric insertion of the tail on the sperm head, and they manifest the barbs on the perforatorium that, in shrews, probably effect the initial binding of the sperm head to the zona pellucida. As a possible correlate, the structural matrix of the hedgehog acrosome comprises only two main components, as judged by immunoblotting, rather than the complex of peptides seen in the matrix of some higher mammals. The Fallopian tube of Atelerix is relatively simple; it displays only minor differences in width and in the arborized epithelium between the isthmus and ampulla, and shows no evidence of the unusual sperm crypts that characterize the isthmus or ampulla, depending on the species, in shrews and moles. In common with other insectivores, Atelerix appears to be an induced ovulator, as judged by the ovulation of some 6-8 eggs by about 23 h after injection of hCG. The dense cumulus oophorus appeared to have little matrix, in keeping with the modest dimensions of the tubal ampulla and, while it was not quite as discrete as that of soricids, it did show the same insensitivity to 0.5% (w/v) ovine or bovine hyaluronidase.

Acrosome↗
PubMed1995

Fine structure of the parotid gland in tree shrew (Tupaia glis).

The parotid glands of Tupaia glis were examined by light and transmission electron microscopy. The acinar cells were seromucous in nature, and contained many acidophilic granules with strong affinity for periodic acid-Schiff (PAS) and weak affinity for alcian blue (AB). These granules consisted of a fine granular matrix of moderate density in which a denser corpuscles or semilunar materials were present. Intercalated duct cells had a few fine vesicles, vacuoles and very few dense granules in the apical region. In occasional epithelial cells, acidophilic, PAS-positive and AB-negative bodies with moderate density were observed in the supranuclear region. The striated ducts consisted of columnar light and dark cells containing round or small ovoid granules of moderate density and did not show the granular duct as seen in the parotid glands of kobe mole and tenrec which are placed in the order insectivora.

Alcian Blue↗
PubMed2003

Detection and identification of pathogens and host DNA in unfed host-seeking Ixodes ricinus L. (Acari: Ixodidae).

In this study, we have developed molecular methods for the identification of reservoir hosts of sylvatic tick-borne zoonoses. The methods are based on the analysis of the blood meal remnant in the tick gut and include detection of pathogens and identification of the host origin of the blood meal. For host identification, a universal primer pair was used to amplify part of the vertebrate 18S rRNA gene followed by reverse line blot hybridization using subgroup-specific probes. Analyses of DNA from whole blood of vertebrates identified the correct subgroup of a broad range of vertebrate species (e.g., Ruminantia, Leporidea, Canidae, Murinae, Arvicolinae, Insectivora, Galliformes, Passeriformes) using probes based on the 18S rDNA sequences. Host DNA in the remnants of larval blood meals was detected in the gut of Ixodes ricinus nymphs maintained under natural conditions up to 9 mo after molting. For pathogen identification, a multiplex polymerase chain reaction was used that targeted parts of the 18S rRNA gene of piroplasm protozoa, the 16S rRNA gene of bacteria, and the intergenic spacer of the Borrelia burgdorferi genospecies complex. The utility of both methods was demonstrated under laboratory conditions by detecting Babesia microti (Franca) and gerbil DNA in 3-mo-old I. ricinus nymphs that had fed on B. microti-infected gerbils as larvae, and under field conditions by analyzing unfed ticks that were collected in a forest. The field study showed that the majority of ticks had fed on ruminants or birds and few on rodents, which is in accord with our knowledge of the fauna in this forest. Few pathogens were detected but the discovery of Borrelia valaisiana and B. burgdorferi s.s. in ticks that had fed on deer and Borrelia afzelii in a tick that had fed on a bird raises questions about the mode of transmission of these spirochetes and possibly about their host specificity.

Animals↗
PubMed2005

The morphological and histological characters of the male external genitalia of the house musk shrew, Suncus murinus.

External genitalia are the reproductive organs necessary for efficient copulation and internal fertilization in various mammalian species. Their morphogeneses display significant morphological and developmental differences among species. The house musk shrew, Suncus murinus (hereafter described as suncus) is a species of the order Insectivora, which has been considered as primitive and one of the earliest eutheria phylogenetically. Comparative anatomical analyses of phylogenetically different mammals will contribute to the better understanding of morphological diversity of external genitalia. This study performed various anatomical and histological analyses concerning the organization of the external genitalia of male suncus. It was shown that the external genitalia of suncus possessed a muscular structure, which we proposed as musculus ischiocavernosus dorsalis of suncus. The musculus ischiocavernosus dorsalis is originated from the inner surface of the tuber ischiadicum and was allocated adjacent to the corpus cavernosum penis. In addition, a pair of alpha-smooth muscle actin positive muscles was located bilaterally to the urethra. This unique morphology of the external genitalia of suncus males may provide a unique model system to investigate genital morphogenesis.

Anatomy, Comparative↗
PubMed1989

On the distribution of elastic fibers in the filiform papillae of Suncus murinus.

The distribution of elastic fibers in the filiform papillae of 1, 2, 3, 4 and 5 week-old and 6 month-old Suncus (Suncus murinus; insectivora) was examined by both Weigert's resorcin-fuchsin method and ultrastructural means. In the adult Suncus (6 months old), elastic fibers in the connective tissue core of the papillae were aligned perpendicularly to the epithelial surface and formed a palisade-like structure which encircled the margin of each connective tissue core. This characteristic structure was restricted to the filiform papillae in the anterior half of the lingual dorsum. In the filiform papillae of the posterior half, elastic fibers were markedly reduced and the palisade-like structure was not present. This characteristic pattern of elastic fiber distribution was established by 3 weeks of age. These observations reveal a characteristic structure consisting of elastic fibers in the connective tissue core of the filiform papillae and the regional distribution of this structure in the tongue. This suggests that the function of the structure in the connective tissue core is to protect against mechanical stress in mastication. The regional distribution of this structure may reflect the difference of mechanical strength between the anterior and posterior of the tongue caused by tongue movement during mastication.

Animals↗
PubMed1992

Distribution of cortical neurons projecting to dorsal column nuclear complex and spinal cord in the hedgehog tenrec, Echinops telfairi.

Using retrograde axonal flow and wheatgerm agglutinin conjugated to horseradish peroxidase, we studied the distribution of cortical neurons giving rise to spinal and dorsal column nuclear projections, and correlated the regions involved in the projections with the cytoarchitectonic areas recently identified in the lesser hedgehog tenrec, Echinops telfairi (Insectivora). Labeled cortical neurons were most numerous following injections of tracer into higher cervical segments, whereas almost none were found following thoracic injections. The cortical labeling appeared more prominent ipsilaterally than contralaterally after spinal injections, although it was more prominent on the contralateral side after injection into the dorsal column nuclear complex. The majority of labeled neurons found in lamina V occupied the neocortex adjacent to the interhemispheric fissure along the rostrocaudal extent of the small corpus callosum. This location corresponded to an intermediate rostrocaudal portion of the hemisphere, and particularly to area 2 of Rehkämper. In some cases, adjacent portions of areas 1 and 3 were also involved, as well as neocortical regions of the lateral hemisphere. The present data did not suggest a somatotopic organization of the projections; likewise, evidence for the presence of more than one somatosensorimotor representation was sparse.

Animals↗
PubMed1976

The distribution of leptospires in the kidney tubules of some British wild mammals.

Histological examination of 69 pairs of infected kidneys from 12 species of Rodentia, Lagomorpha, Carnivora and Insectivora revealed that leptospires were confined mainly to the proximal and distal convoluted tubule, were less often found in the thick loop of Henle and only rarely in the collecting duct. On no occasion were the organisms present in the thin loop of Henle. Preliminary observations on the relationship of leptospires to tubule epithelium indicate some degree of physical attachment. It is suggested that the avoidance of the thin loop of Henle might be a reflection of its structural properties.

Animals↗
PubMed1976

Trypanosomes of small mammals in Iran.

Trypanosomes in the subgenera Herpetosoma, Schizotrypanom and Megatrypanum were found in 31 small mammals representing nine species of the orders Rodentia, Insectivora and Chiroptera in Iran.

Animals↗
PubMed1996

Serological survey of small mammals in a vesicular stomatitis virus enzootic area.

Small mammals were captured in a Costa Rican dairy farm located in a vesicular stomatitis virus (VSV) enzootic focus, in order to determine which species were naturally infected by this virus. Monthly captures were performed from March 1989 to February 1990. Eighty-four individuals belonging to the orders Rodentia (n = 52), Insectivora (n = 31) and Marsupialia (n = 1) were captured. Only Sigmodon hispidus had neutralizing antibodies to VSV; among 21 animals, six had antibodies to Indiana, one to New Jersey, and two to both serotypes. In addition, groups of 40 sentinel mice (Mus musculus, strain C3H) were placed in cages distributed throughout the farm. Each group was exposed for 1 mo over a period of 1 yr. None of 312 sentinel mice developed antibodies against either VSV serotype. Based on these results, we believe that S. hispidus might be part of the natural cycle of VSV in this enzootic focus. Caged Mus musculus do not seem appropriate for monitoring VSV activity in this area.

Animals↗
PubMed1976

[Study of correlations linking the volumes of the hypophyseal lobes and the epiphysis to body and brain weights in Chiroptera].

Study of the correlations binding the different lobes of the hypophysis and the pineal gland to body weight and brain weight in Chiroptera shows that the hypophysis is better correlated to body and brain weight than the pineal gland, fact that we already observed in Rodents and Primates. The allometry coefficient (M.R.A.) related to body weight varies from 0,80 to 0,98 for the hypophyseal lobes. The value of this coefficient for the pineal gland (1,60) is greater than that found (1,009) in another group of Mammals (Insectivora, Lemurians and Primates). It is less sure as the important variations in volume of this gland determine a lower correlation coefficient.

Animals↗
PubMed1979

"The diencephalon of Ptilocercus lowii (pen-tailed tree-shrew)".

The pen-tailed tree-shrew (Ptilocercus lowii) has been regarded by Le Gros Clark (1926), and Martin (1968) to possess more primitive morphological and to a certain extent, neuro-anatomical characteristics than the other tree-shrew species belonging to the sub-family Tupaiinae. Investigations have been carried out on the diencephalon of Ptilocercus lowii which has not been completely done by Le Gros Clark and other workers since 1926, to find out whether the diencephalon has actually undegone any phylogenetic changes that should be more advanced than those of the Insectivora or remain more primitive than that of the Tupaiinae. The diencephalic structure that show the most significant phylogenetic features which differe Ptilocerecus from Tupaia are observed in the anterior, dorsolateral and ventrolateral thalamic groups, and the geniculate bodies. The nucleus anteroventralis is, by comparison, much smaller and poorly differentiated from the nucleus anteromedialis. The nucleus anterodorsalis is also comparably large and does not reach the dorsal surface of the thalamus as it does in the primates. The midline nuclei do not show any significant differences, except the notably larger size of nucleus parataenialis in Ptilocercus. The nucleus mediodoralis is small and indifferentiated although it does show some incipient signs of cellular differentiation. The nucleus centralis lateralis is well developed; its inferior (ventral) part is larger than its superior part which is the better developed of the two parts in the tupaiids and primates. The nucleus centrum medianum appears to be very small and forms only a lateral extension of the nucleus parafascicularis. The ventrolateral thalamic group basically consists of nuclei ventrales anterior, lateralis and posterior without intermediate or transitional zones as found in Tupaia and Primates. The nucleus pretectalis is the largest and the best developed of all the elements of the posterior thalamic nuclear group. The lateral geniculate nucleus is not differentiated into laminae like that in Tupaia and Primates; it is merely a homogeneous structure that appears to be smaller in size that the pregeniculate and medial geniculate nuclei. The medial geniculate nucleus is large in proportional size of the whole thalamus and appears to be well differentiated cellularly into several small parts. No remarkable changes are noted in the epithalamus, subthalamus and hypothalamus. However, the nucleus ventromedialis appears to be the most outstanding structure in the infundibular region of the hypothalamus. The mammillary region is of a simpler construction in Ptilocercus than in Tupaia; it does not protrude from the ventral surface of the hypothalamus. In the light of these findings, the phyletic status of Ptilocercus in the family Tupaiidae is discussed.

Animals↗