Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “INSECTIVORA”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 127 records · Page 7Linked to original sources
PubMed1997

Robertsonian chromosomal variation in the house musk shrew (Suncus murinus, Insectivora:Soricidae) and the colonization history of the species.

A high-resolution G-banding technique was used to identify five metacentrics that characterize Suncus murinus from Sri Lanka. These metacentrics were shown to be the product of Robertsonian fusion of acrocentric chromosomes identical to those in the standard karyotype defined by M.B. Rogatcheva et al. Two of the metacentrics in the Sri Lankan shrews (Rb(10.12) and Rb(14.15)) were the same as those reported by C.H. Sam et al. in Malayan populations of S. murinus. This finding provides strong support for the suggestion of T.H. Yosida that metacentric-carrying shrews colonized Malaya from Sri Lanka and hybridized with individuals of standard karyotype, generating the Robertsonian polymorphism now observed. In addition to the Robertsonian variation in S. murinus, we have used our high resolution technique (G- and C-banding) to characterize variants on chromosome 7, the X chromosome, and the Y chromosome.

Animals↗
PubMed1998

Chromosome pairing in inter-racial hybrids of the house musk shrew (Suncus murinus, Insectivora, Soricidae).

Two chromosome races of the house shrew Suncus murinus that differ from each other for five Robertsonian translocations (8.17, 9.13, 10.12, 11.16, and 14.15), heterochromatic insertions in chromosomes 7 and X, and multiple rearrangements in the Y chromosome were crossed and then intercrossed in captivity to produce a hybrid stock. Electron-microscopic analysis of synaptonemal complexes in fertile and sterile hybrid males was carried out. Meiosis in sterile males did not progress beyond pachytene and was severely disrupted. Meiotic arrest was not determined by structural heterozygosity: heterozygotes for all variant chromosomes distinguishing two parental races were found in both sterile and fertile male hybrids. Fertile hybrids demonstrated an orderly pairing of all chromosomes. In heterozygotes for Robertsonian fusions, completely paired trivalents were formed between the Robertsonian metacentrics and homologous acrocentrics. In heterozygotes for chromosome 7, bivalents with a small buckle were observed in a small fraction of pachytene cells. No differences were found in the morphology and pairing pattern of sex bivalents, composed of the X and Y chromosomes derived from the same or different parental races. Univalents, multivalents, and associations between X and Y chromosomes and autosomal trivalents, as well as associations of autosomal trivalents with each other, were observed in a small fraction of the pachytene cells of fertile males. Our results indicate that the system controlling male sterility in interracial hybrids of S. murinus is of genic rather than of chromosomal type.

Animals↗
PubMed1998

Inheritance of male hybrid sterility in the house musk shrew (Suncus murinus, Insectivora, Soricidae).

Two geographic races of the house musk shrew (Suncus murinus) were crossed and intercrossed in the laboratory. Many cases of male sterility were detected among the hybrids. Segregation analysis of the pedigree data showed that the inheritance of male sterility in interracial hybrids of S. murinus can be described within the framework of monogene polyallele model with sterility of a single allele combination. This model is similar if not identical to that proposed by Dobzhansky and Muller.

Alleles↗
PubMed2000

Cortical organization in insectivora: the parallel evolution of the sensory periphery and the brain.

Insectivores are traditionally described as a primitive group that has not changed much in the course of mammalian evolution. In contrast, recent studies reveal a great diversity of sensorimotor specializations among insectivores adapted to a number of different ecological niches, indicating that there has been significant diversification and change in the course of their evolution. Here the organization of sensory cortex is compared in the African hedgehog (Atelerix albiventris), the masked shrew (Sorex cinereus), the eastern mole (Scalopus aquaticus), and the star-nosed mole (Condylura cristata). Each of these four closely related species lives in a unique ecological niche, exhibits a different repertoire of behaviors, and has a different configuration of peripheral sensory receptors. Corresponding specializations of cortical sensory areas reveal a number of ways in which the cortex has evolved in parallel with changes to the sensory periphery. These specializations include expansion of cortical representations (cortical magnification), the addition or loss of cortical areas in the processing network, and the subdivision of areas into modules (barrels and stripes).

Animals↗
PubMed2002

Alps, genes, and chromosomes: their role in the formation of species in the Sorex araneus group (Mammalia, Insectivora), as inferred from two hybrid zones.

During the Pleistocene glaciations, the Alps were an efficient barrier to gene flow between isolated populations, often leading to allopatric speciation. Afterwards, the Alps strongly influenced the post-glacial recolonization of Europe and represent a major suture zone between differentiated populations. Two hybrid zones in the Swiss and French Alps between genetically and chromosomally well-differentiated species-the Valais shrew, Sorex antinorii, and the common shrew, S. araneus-were studied karyotypically and by analyzing the distribution of seven microsatellite loci. In the center of the Haslital hybrid zone the two species coexist over a distance of 900 m. Hybrid karyotypes, among them the most complex known in Sorex, are rare. F-statistics based on microsatellite data revealed a strong heterozygote deficit only in the center of the zone, due to the sympatric distribution of the two species with little hybridization between them. Structuring within the species (both F(IS) and F(ST)) was low. An hierarchical analysis showed a high level of interspecific differentiation. Results were compared with those previously reported in another hybrid zone located at Les Houches in the French Alps. Genetic structuring within and between species was comparable in both hybrid zones, although chromosomal incompatibilities are more important in Haslital, where a linkage block of the race-specific chromosomes should additionally impede gene flow. Evidence for a more restricted gene flow in Haslital comes from the genetically intermediate hybrid karyotypes, whereas in Les Houches, hybrid karyotypes are genetically identical to individuals of the pure karyotypic races. Genic and chromosomal introgression was observed in Les Houches, but not in Haslital. The possible influence of a river, separating the two species at Les Houches, on gene flow is discussed.

Altitude↗
PubMed1982

[Contribution to the cytotaxonomy of shrews (Mammalia, Insectivora) from West Africa].

Chromosomes analysis of 28 shrews belonging to the genus Crocidura from West Africa allowed the detection of five new karyotypes: C. wimmeri (2n = 50, NF = 84), C. cf. gracilipes (56/86), C. cf. nimbae (46/68), and C. cf. planiceps (44/72). Among the individuals identified morphologically as C. poensis (52/70) a distinct species was recognized on the basis of its chromosome complement, C. nigeriae (50/76). The karyotype of C. occidentalis was confirmed with the study of another subspecies, C. occidentalis manni (50/66). An identical chromosome set characterizes C. odorata giffardi and provides evidence for its relationship with C. occidentalis.

Africa, Western↗
PubMed1990

Synaptonemal complex analysis in Talpa occidentalis spermatocytes (Insectivora, Mammalia). II. Evolution of the X-chromosome self-pairing process.

Zygotene and pachytene configurations of the X chromosome were studied in whole-mount, silver-stained preparations of spermatocytes from XY males from a population of Talpa occidentalis in which sex reversal has been described. The most striking finding in this study was a self-pairing conformation of the axial (differential) element of the X chromosome. This self-pairing was markedly constant in the site of initiation, which invariably involved the distal free end of the X and the region beyond the X-Y pairing segment, so that X-Y synapsis was never disturbed. In addition, self-pairing occurred later than autosomal synapsis and was accompanied by thickening of the axes, although this seemed to occur after the formation of an ordinary synaptonemal complex. The etiology of this phenomenon may be based on residual homology, possibly due to conservation of a primitive isochromosome throughout the karyotypic evolution of this species. However, the possible relationship between self-pairing and sex reversal remains obscure.

Animals↗
PubMed1997

Chromosome location of sixteen genes in the common shrew, Sorex araneus L. (Mammalia, Insectivora).

This report extends the genetic map of the common shrew (Sorex araneus) by use of a clone panel of shrew-Chinese hamster and shrew-mouse hybrid cells (Pack et al., 1995; Matyakhina et al., 1996). This set of hybrid clones made it possible to assign the shrew genes for isocitrate dehydrogenase 2 (IDH2), inorganic pyrophosphatase (PP), glutamicpyruvate transaminase (GPT), adenosine kinase (ADK), glucuronidase 2 (GUSB) and acid phosphatase 2 (ACP2) to chromosome ik; the genes for adenylate kinases 1 and 3 (AK1 and AK3) to chromosome af; the genes for glutamate-oxaloacetate transaminase 2 (GOT2), peptidase D (PEPD) and growth hormone (GH) to chromosome hn; the gene for phosphoglucomutase 2 (PGM2) to chromosome go, the gene for enolase 1 (ENO1) to chromosome ji, the gene for ornithine carbamoyl-transferase (OTC) to chromosome de, the gene for aminoacylase 1 (ACY1) to arm m (chromosome mp), the gene for glutamate-oxaloacetate transaminase 1 (GOT1) to arm q (chromosome qr). Thus, the genetic map of the common shrew now contains 33 genes and it is possible to compare the syntenic associations with other species.

Animals↗
PubMed1989

Ultrastructure of secretory ameloblasts in the house musk shrew, Suncus murinus, Insectivora.

Tooth germs from neonatal house musk shrews, Suncus murinus, were used for the study. The tooth morphogenesis was compared electron microscopically to that of Primates. In the tooth germ at the bell stage, the ameloblast was 3 x 50 microns in size, columnar in shape and had several tubular-type Golgi apparatus which were at the distal end of the cell. Most mitochondria were noted at the proximal end of ameloblasts. Tomes' processes were 1 micron in width, protruded 10 microns from the ameloblast and had many dense bodies and two kinds of vesicles. They were morphologically different from human ameloblasts and enamel rods.

Ameloblasts↗
PubMed1990

Identification of lactotropes (PRL cells), somatotropes (GH cells), corticotropes (ACTH cells) and thyrotropes (TSH cells) in the pituitary gland of the musk shrew, Suncus murinus L. (Insectivora), by immunohistochemistry.

By means of immunohistochemistry, lactotropes, somatotropes, corticotropes and thyrotropes in the pituitary of the male musk shrew, Suncus murinus L., were identified at the electron-microscopic level. Lactotropes were classified into three types: type I containing large (200-450 nm in diameter) round secretory granules, type II with medium-sized (150-250 nm in diameter) ones and type III with small (50-150 nm in diameter) ones. Somatotropes were also classified into type I somatotropes that contain large (450 nm in diameter) spherical secretory granules and type II somatotropes containing comparatively small (300 nm in diameter) round granules. Both type I and II somatotropes were small and sometimes contained rod-shaped granules. Corticotropes were round or oval cells with round secretory granules in various densities and sizes (150-500 nm in diameter) scattered all over the cytoplasm. Thyrotropes were angular or polyhedral cells containing electron-transparent round secretory granules (200-300 nm in diameter) and large irregularly shaped granules with a maximum diameter of about 1,500 nm. Each type of the cells may be distinguished by its respective ultrastructural characteristics alone without the aid of immunohistochemistry.

Adrenocorticotropic Hormone↗
PubMed1986

Immunocytochemical localization of actin in the sperm head of Talpa europaea (Insectivora).

Actin in the sperm head of Talpa europaea was observed by immunofluorescence and immunoelectron microscopy. The indirect immunofluorescence technique, using both anti-actin and DNase anti-DNase methods, showed a shining fluorescent band around the sperm head in some spermatozoa, whereas in others the fluorescence was found in the postacrosomal region. Since no labeling was detected in sperms treated with NBD-phallacidin, it is likely that mature mole sperms contain G-actin but not F-actin. The results of electron microscopy indicated the deposition of the anti-actin antibodies in two places in mole spermatozoa: the postacrosomal region and the nuclear segment of the acrosome. In the first case, the actin was localized in the space between the outer surface of the postacrosomal sheath and the plasma membrane; in the second one, the actin was localized in the space between the outer acrosomal membrane and the plasma membrane. The significance of the presence of actin and its role(s) during fertilization are discussed.

Actins↗
PubMed1999

Contraction parameters, myosin composition and metabolic enzymes of the skeletal muscles of the etruscan shrew Suncus etruscus and of the common European white-toothed shrew Crocidura russula (Insectivora: soricidae).

In the Etruscan shrew, the isometric twitch contraction times of extensor digitorum longus (EDL) and soleus muscles are shorter than in any other mammal, allowing these muscles to contract at outstandingly high contraction frequencies. This species has the highest mass-specific metabolic rate of all mammals and requires fast skeletal muscles not only for locomotion but also for effective heat production and for an extremely high ventilation rate. No differences could be detected in the fibre type pattern, the myosin heavy and light chain composition, or in the activity of the metabolic enzymes lactate dehydrogenase and citrate synthase of the two limb muscles, the EDL and the soleus, which in larger mammalian species exhibit distinct differences in contractile proteins and metabolic enzymes. All properties determined in EDL and soleus muscles of Suncus etruscus, as well as in the larger Crocidura russula, are typical for fast-oxidative fibres, and the same holds for several other skeletal muscles including the diaphragm muscle of S. etruscus. Nevertheless, the EDL and soleus muscles showed different mechanical properties in the two shrew species. Relaxation times and, in C. russula, time to peak force are shorter in the EDL than in the soleus muscle. This is in accordance with the time course of the Ca(2+) transients in these muscles. Such a result could be due to different parvalbumin concentrations, to a different volume fraction of the sarcoplasmic reticulum in the two muscles or to different Ca(2+)-ATPase activities. Alternatively, the lower content of cytosolic creatine kinase (CK) in the soleus compared with the EDL muscle could indicate that the observed difference in contraction times between these shrew muscles is due to the CK-controlled activity of their sarcoplasmic reticulum Ca(2+)-ATPase.

Animals↗
PubMed2000

Robertsonian metacentrics of the house musk shrew (Suncus murinus, Insectivora, Soricidae) lose the telomeric sequences in the centromeric area.

The house musk shrew, Suncus murinus, is polymorphic for five Robertsonian translocations (Rb8.17, 9.13, 10.12, 11.16, 14.15). Fluorescence in situ hybridisation with a biotin-labelled oligonucleotide, (TTAGGG)7, was performed to localise the telomeric DNA sequences at Rb chromosomes of heterozygous shrews. Hybridisation signals were observed at both ends of all chromosomes, but not at the pericentromeric areas of any of the Robertsonian metacentrics. Our results indicate a complete loss of the telomeric sequences at the fusion points of the Rb metacentrics in S. murinus.

Animals↗