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PubMed1989

The distribution of endocrine cells in the mucosa of the gastrointestinal tract of the house musk shrew, Suncus murinus (Insectivora).

The distribution of endocrine cells in the gastrointestinal tract of the house musk shrew, Suncus murinus (Family Soricidae, Order Insectivora) was studied immunohistochemically. The hormones investigated were gastrin, cholecystokinin (CCK), somatostatin, secretin, glucagon, gastric inhibitory polypeptide (GIP), motilin and neurotensin. In the gastric mucosa, gastrin and somatostatin cells were only found in the pyloric regions, and no other hormonal cell-types were observed. In the intestinal mucosa, the largest number of endocrine cells belonged to the gastrin and glucagon/glicentin cell-types, whereas CCK-33/39 and secretin cells were the least numerous. Numbers of other cell-types were intermediate between these two groups. The gastrin and GIP cells were mostly localized in the proximal portion of the intestine, decreasing in number towards the distal portion. The motilin and CCK-33/39 cells were restricted to the proximal half. The glucagon/glicentin and neurotensin cells were most abundant in the middle portion. The somatostatin and secretin cells, although only present in small numbers, were randomly distributed throughout the intestine. This characteristic distribution of gastrointestinal endocrine cells is discussed in comparison with the distribution patterns of other mammals.

Animals↗
PubMed1988

Electron-microscopic and microprobe analyses on the pigmented and unpigmented enamel of Sorex (Insectivora).

Sorex belongs to the Insectivora and has a pigmented tooth enamel due to iron. The pigmented enamel (PE) has a mean Ca/P weight ratio, analyzed by quantitative electronprobe X-ray microanalysis, of about 1.9 (mean molar Ca/P ratio 1.46), and the unpigmented enamel (UE) a Ca/P weight ratio of about 2.0 (mean molar Ca/P ratio 1.59). The PE has a higher iron content (with a value of about 8%) than the UE, as shown by microanalysis of ultrathin sections. Laser microprobe mass analysis (LAMMA) has shown that the carbonate content in the UE is higher than in the PE. In the LAMMA spectrum of the negatively charged ions the carbonate lines could be compared directly with those of negatively charged iron ions. The pigmentation is associated with a low Ca/P ratio but may transfer mechanical strength and acid resistance strength to the PE.

Animals↗
PubMed2006

Cross-species chromosome painting unveils cytogenetic signatures for the Eulipotyphla and evidence for the polyphyly of Insectivora.

Insectivore-like animals are traditionally believed among the first eutherian mammals that have appeared on the earth. The modern insectivores are thus crucial for understanding the systematics and phylogeny of eutherian mammals as a whole. Here cross-species chromosome painting, with probes derived from flow-sorted chromosomes of human, was used to delimit the homologous chromosomal segments in two Soricidae species, the common shrew (Sorex araneus, 2n = 20/21), and Asiatic short-tailed shrew (Blarinella griselda, 2n = 44), and one Erinaceidae species, the shrew-hedgehog (Neotetracus sinensis, 2n = 32), and human. We report herewith the first comparative maps for the Asiatic short-tailed shrew and the shrew-hedgehog, in addition to a refined comparative map for the common shrew. In total, the 22 human autosomal paints detected 40, 51 and 58 evolutionarily conserved segments in the genomes of common shrew, Asiatic short-tailed shrew, and shrew-hedgehog, respectively, demonstrating that the common shrew has retained a conserved genome organization while the Asiatic short-tailed shrew and shrew-hedgehog have relatively rearranged genomes. In addition to confirming the existence of such ancestral human segmental combinations as HSA 3/21, 12/22, 14/15 and 7/16 that are shared by most eutherian mammals, our study reveals a shared human segmental combination, HSA 4/20, that could phylogenetically unite the Eulipotyphlan (i.e., the core insectivores) species. Our results provide cytogenetic evidence for the polyphyly of the order Insectivora and additional data for the eventual reconstruction of the ancestral eutherian karyotype.

Animals↗
PubMed2006

Unique regulation of thyroid hormone metabolism during fasting in the house musk shrew (Suncus murinus, Insectivora: Soricidae).

The active hormone, 3,3',5-triiodothyronine (T3) is derived from thyroxine (T4) by the action of iodothyronine 5'-deiodinases (5'-D). By now two types of 5'-D have been identified; Type 1 (D1) and type 2 (D2). A relative contribution of these isotypes to the circulating T3 levels in the human remains to be determined whereas a number of reports indicate that, under physiological conditions, D1 plays a major role in maintaining circulating T3 levels in rodents. In both human and rodents, sickness and starvation reduce serum T3 concentration mainly through decrease in D1 activity. Recently, we found that the house musk shrew (Suncus murinus, Insectivora: Soricidae) has a different tissue distribution of D1 activity. Because compared to rodents D1 activity in the shrew was found only in liver at a much reduced level, D2 rather than D1 may play a role in the maintenance of serum T3. Therefore, we questioned how D1 and D2 activities change in fasted shrews and how these changes affect circulating thyroid hormone levels. We thus starved shrews for 24, 48 or 72 h and measured changes in serum concentration of T3, T4, and 3,3',5'-triiodothyronine (reverse T3, rT3) and D1 activities as well as its mRNA expression in liver. D2 activities were also measured in brown adipose tissue (BAT) and cerebral cortex of shrews. Unlike in human and rodents, T3 levels in shrews remained constant during fasting while T4 levels tended to decrease, resulting in an increase in its T3/T4 ratio. On the other hand, changes in rT3 levels were similar to those in human and rodents, being elevated with fasting. D1 mRNA and its activity were significantly reduced in the liver whereas D2 activities in BAT and cerebral cortex were increased by fasting. These results indicated that fasting in shrews also reduced hepatic D1 activity but it did not affect circulating T3 levels. The increased T3/T4 ratio together with increased D2 activity in BAT and cerebral cortex with fasting suggest that D2 rather than D1 is responsible for the maintenance of T3 levels in the house musk shrew.

Adipose Tissue, Brown↗
PubMed2002

Type 1 iodothyronine deiodinase in the house musk shrew (Suncus murinus, Insectivora: Soricidae): cloning and characterization of complementary DNA, unique tissue distribution and regulation by T(3).

The house musk shrew Suncus murinus (Insectivora: Soricidae) has been reported as having low thyroxine to 3,3'5-triiodothyronine (T(3)) converting activity in liver and kidney homogenates and was assumed to be type 1 iodothyronine deiodinase (D1)-deficient. To study whether this is due to structural abnormality of shrew D1, we cloned the cDNA and characterized the enzyme. The deduced amino acid sequence of shrew D1 was found to be highly homologous to other known D1s and the enzyme itself to have similar catalytic activity. However, unlike in other species, the D1 activity was detected only in liver. Moreover, the D1 activity in liver of the shrew was less than half of that in rat liver and its expression was not up-regulated by T(3). In contrast, a very high activity of D2 was demonstrated in brain and brown adipose tissue. The present study also revealed that the serum level of T(3) in the shrew was in the same range as these in other mammals. These results suggest that D2 contributes to the production and maintenance of T(3) levels in the house musk shrew.

Adipose Tissue, Brown↗
PubMed2005

Phylogeny and life histories of the 'Insectivora': controversies and consequences.

The evolutionary relationships of the eutherian order Insectivora (Lipotyphla sensu stricto) are the subject of considerable debate. The difficulties in establishing insectivore phylogeny stem from their lack of many shared derived characteristics. The grouping is therefore something of a 'wastebasket' taxon. Most of the older estimates of phylogeny, based on morphological evidence, assumed insectivore monophyly. More recently, molecular phylogenies argue strongly against monophyly, although they differ in the extent of polyphyly inferred for the order. I review the history of insectivore phylogenetics and systematics, focussing on the relationships between the six extant families (Erinaceidae--hedgehogs and moonrats, Talpidae - moles and desmans, Soricidae - shrews, Solenodontidae--solenodons, Tenrecidae--tenrecs and otter-shrews and Chrysochloridae--golden moles). I then examine how these various phylogenetic hypotheses influence the results of comparative analyses and our interpretation of insectivore life-history evolution. I assess which particular controversies have the greatest effect on results, and discuss the implications for comparative analyses where the phylogeny is controversial. I also explore and suggest explanations for certain insectivore life-history trends: increased gestation length and litter size in tenrecs, increased encephalization in moles, and the mixed fast and slow life-history strategies in solenodons. Finally, I consider the implications for comparative analyses of the recent strongly supported phylogenetic hypothesis of an endemic African clade of mammals that includes the insectivore families of tenrecs and golden moles.

Animals↗
PubMed1986

[Description of Hymenolepis cerberensis n. sp. (Cestoda: Hymenolepididae) and first general considerations on the fauna of cestode parasites of the pygmy shrew Suncus etruscus (Savi, 1822) (Insectivora: Soricidae)].

Description and differentiation of the adult stage of Hymenolepis cerberensis n. sp. (Cestoda: Hymenolepididae), an intestinal parasite of the Pygmy white-toothed shrew, Suncus etruscus (Savi, 1822) (Insectivora: Soricidae: Crocidurinae) in the region of Banyuls-sur-Mer and Cerbère (Oriental Pyrenees, France). The new species is characterized by the size of the gravid specimens and by the presence of 18-21 rostellar hooks of 18.5-20 micron and of filaments around the embryophore. The general composition of the fauna of Cyclophyllidea parasitizing S. etruscus is analysed. There are three less specialised Hymenolepis species with a scolex of the same type and one Pseudhymenolepis species, with the absence of unarmed species lacking a rostrum. The oioxenous character of the Cestodes parasitizing Suncus species sustains the validity of the genus Suncus. The resemblance of the Cestodefaunas suggests a narrow phyletic relationship between the genera Suncus and Crocidura.

Animals↗
PubMed1991

Induction of tumors in the Japanese house musk shrew, Suncus murinus (Insectivora), by dimethylbenz[a]anthracene.

The carcinogenic effect of 7,12-dimethylbenz[a]anthracene (DMBA) was examined in the virgin female Japanese house musk shrew, Suncus murinus (family: Soricidae, order: Insectivora). Leukemia, musk gland tumors, pilosebaceous tumors and sarcomas were induced in the DMBA-treated shrews, whereas none of the controls developed any tumors up to 50 weeks of age. DMBA emulsion was administered i.p. at a dose of 1.25 or 2.5 mg once a week, with either four or eight doses being given from 8 weeks of age. Leukemia developed in 100% (9/9), 50% (5/10), 56% (5/9) and 0% (0/10) of the animals treated with a total dose of 20 mg (8 x 2.5 mg), 10 mg (8 x 1.25 mg), 10 mg (4 x 2.5 mg) and 5 mg (4 x 1.25 mg) of DMBA respectively. Leukemia was of the lymphatic and/or mast cell type, and the spleen was the organ invariably involved. A dose-dependent effect of DMBA was not observed for pilosebaceous and musk gland tumors. When 1 mg of DMBA powder was dusted into the subcutaneous tissue at 4 weeks of age, sarcomas developed at the dusted site (69%; 9/13).

9,10-Dimethyl-1,2-benzanthracene↗
PubMed1984

Acidic glycolipids from kidney of suncus (Insectivora).

Lipids were extracted from the kidney of house musk shrew (Suncus murinus), which belongs to the order Insectivora. Acidic glycosphingolipids were purified from lipid extracts by mild alkaline methanolysis followed by column chromatographies on DEAE-Sephadex and silica beads (Iatrobeads). Purified glycolipids were analyzed by thin-layer chromatography, mild acid hydrolysis, gas liquid chromatography of the methyl glycosides after methanolysis and gas chromatography-mass spectrometry of the partially methylated alditol acetates. The kidney of suncus was unique in that it contained ganglioside GM2 (NeuAc type, 28.7 nmol and NeuGc type, 15.8 nmol/g tissue) as the major ganglioside. GM4 (NeuAc) (2.6 nmol/g), and GM3 (NeuAc type, 11.5 nmol and NeuGc type, 8.7 nmol/g) were also present. The content (298.9 nmol/g) of galactosyl sulfatide (GalCer-I3-sulfate) was higher than the values reported previously for other animal species. The total amount of acidic groups in glycolipids of suncus kidney was compared with the values for the kidney of 4 placental mammals to obtain an allometric correlation: log Y = 0.266 + 0.780 log X where X designates body weight, kg and Y, total acidic groups, mumol. A highly significant correlation (r = 0.999) was obtained among values from 5 representative placental mammals which live in mesic environments, suggesting that acidic glycosphingolipids are essential for the kidney function.

Animals↗
PubMed1998

Meiotic drive favors Robertsonian metacentric chromosomes in the common shrew (Sorex araneus, Insectivora, mammalia).

Meiotic drive has attracted much interest because it concerns the robustness of Mendelian segregation and its genetic and evolutionary stability. We studied chromosomal meiotic drive in the common shrew (Sorex araneus, Insectivora, Mammalia), which exhibits one of the most remarkable chromosomal polymorphisms within mammalian species. The open question of the evolutionary success of metacentric chromosomes (Robertsonian fusions) versus acrocentrics in the common shrew prompted us to test whether a segregation distortion in favor of metacentrics is present in female and/or male meiosis. Performing crosses under controlled laboratory conditions with animals from natural populations, we found a clear trend toward a segregation distortion in favor of metacentrics during male meiosis, two chromosome combinations (gm and jl) being significantly preferred over their acrocentric homologs. Apart for one Robertsonian fusion (hi), this trend was absent in female meiosis. We propose a model based on recombination events between twin acrocentrics to explain the difference in transmission ratios of the same metacentric in different sexes and unequal drive of particular metacentrics in the same sex. Pooled data for female and male meiosis revealed a trend toward stronger segregation distortion for larger metacentrics. This is partially in agreement with the frequency of metacentrics occurring in natural populations of a chromosome race showing a high degree of chromosomal polymorphism.

Animals↗
PubMed2001

Comparative FISH mapping of human cDNA clones to chromosomes of the musk shrew (Suncus murinus, Insectivora).

Forty-one cDNA clones of human functional genes were newly mapped to chromosomes of the musk shrew (Suncus murinus, Insectivora) by fluorescence in situ hybridization, and a comparative cytogenetic map of 51 genes, including 10 genes reported in our previous study, was constructed between human (HSA) and musk shrew (SMU) chromosomes. In this comparative map, the 51 genes localized to human autosomes, except HSA 8, 16, and 20, were mapped to 15 shrew autosomes, except SMU 4, 16, 17 and 18. Twelve conserved segments were identified between human and shrew chromosomes, and six segments among the musk shrew, human, and mouse. Our results defined the presence of at least one inversion and several interchromosomal rearrangements that occurred during evolution after the two species diverged from a common ancestor. Localization of three major histocompatibility complex (MHC) genes to shrew chromosome 3 suggested that the MHC genes of the musk shrew are located in a cluster on chromosome 3. The cytogenetic map constructed in this study is the first cytogenetic map with many functional genes in insectivore species. This approach provides clues for clarifying the chromosomal evolution in this order.

Animals↗
PubMed1990

Synaptonemal complex analysis of spermatocytes of Talpa occidentalis (Insectivora, Mammalia): autosomal synapsis and substaging of zygonema and pachynema.

Spermatocytes from the mole, Talpa occidentalis, a species that includes both XX males and intersexes, were surface-spread and silver-stained to substage meiotic prophase from early zygonema through pachynema. In zygonema, only the Z2 and Z3 substages were found. This stage differed in comparison with such species as the Chinese hamster, laboratory mouse, and deer mouse, which belong to orders other than Insectivora. Pachynema, in which five substages were established (P1-P5), seems to be a more homogeneous stage, and remarkable differences with respect to the above-mentioned species were not found. Synaptic adjustment was demonstrated in X-Y pairing. Nonhomologous pairing was evident at the Y-centromeric region and considered likely in the proximal arm of this chromosome. In addition to sequencing the events taking place during zygonema and pachynema in males from a wild population in which some members show sex reversal, our finding represents the first attempt to substage zygonema and pachynema in an Insectivore species, thus contributing to current knowledge of the nature and degree of variability in the mammalian synaptic process.

Animals↗
PubMed1995

Development of the chondrocranial base of the musk shrew, Suncus murinus (Insectivora).

To reveal the developmental process of the chondrocranial base of the musk shrew, Suncus murinus (Insectivora), light microscopic observation of serial sections and macroscopic observation with whole-mount differential staining of bone and cartilage were performed on day-17 to -22 embryos. The following unusual findings were obtained: (1) The sphenoethmoidal commissure formed a part of the posterior edge of the tectum nasi, implying that the posterior portion of the paries nasi in the mammalian nasal capsule shares a common origin with the neurocranium. (2) The processus alaris arose independently from the hypophysial cartilage and also contributed to formation of the carotid foramen. (3) The hypophysial cartilage consisted of one medial and a pair of lateral cartilage nodules. The homology of the pair of cartilages with polar cartilages in lower vertebrates is discussed.

Animals↗
PubMed2003

Eimeria species from Cryptotis shrews (Insectivora: Soricidae) with description of a new species.

Fresh fecal samples from 12 shrews, 10 Cryptotis goodwini Jackson, 1933, and 2 Cryptotis merriami Thomas, 1898, were collected between December 1994 and May 1998; 11 (92%) were positive for eimeriid coccidia, including 8 of 8 C. goodwini and 2 of 2 C. merriami from Honduras and 1 of 2 C. goodwini from Guatemala. Two Eimeria species were found: 1 is consistent with the description of Eimeria whitakeri Upton and McAllister, 1991, and 1 is described in this study as new. Sporulated oocysts of the new species are subspheroidal, 16.8 x 15.7 (14-20 x 15-19) microm, with a length-width (L/W) ratio of 1.1 (1.0-1.2); they lack a micropyle and oocyst residuum, but 1-2 polar granules are always present. Sporocysts are elongate and ovoidal, 8.4 x 6.0 (6-10 x 4.5-7.5) microm, with a L/W ratio of 1.4 (1.2-1.7) and have a Stieda body and sporocyst residuum. This is the 49th Eimeria species described from all Insectivora but only the third from Cryptotis species.

Animals↗
PubMed2004

Description of Brachylecithum mackoi n. sp. (Digenea: Dicrocoeliidae) from the European hedgehog, Erinaceus europaeus (Insectivora: Erinaceidae).

A new hepatic dicrocoeliid species, Brachylecithum mackoi n. sp. (Digenea, Dicrocoeliidae), is described from the European hedgehog, Erinaceus europaeus (L.) (Insectivora, Erinaceidae). An infected host was found in the Mediterranean island of Elba (Italy), and more than 60 individuals were isolated from the biliary ducts. The holotype and 55 paratypes were examined. Brachylecithum mackoi n. sp. differs from congeneric species found in mammal hosts by having well-developed lappets in the ventral sucker, a sloping uterus between anterior testis and acetabulum, no overlap between vitellaria, and metrical features in the body size, sucker diameters, cirrus sac, and size of eggs. The only other Brachylecithum species of erinaceids in Europe and Africa, Brachylecithum aetechini Dollfus, 1951, differs from the new species in the above-mentioned morphological characters, greater dimensions of the body, and oral sucker, pharynx, cirrus sac, and egg dimensions. The presence of B. mackoi n. sp. in Elba Island is discussed in the light of apparent host specificity of erinaceid dicrocoeliids and geographical distribution of Palearctic and Ethiopian Erinaceidae.

Animals↗
PubMed1989

Scanning electron microscopic study on the lingual papillae of the Japanese insectivora.

The tongue and lingual papillae of the Japanese Insectivora, the Shinto shrew (Sorex caecuiens saevus), the long-clawed shrew (S. unguiculatus), the dsinezumi shrew (Crocidura dsinezumi dsinezumi) and the Japanese water shrew (Chimarrogale himalyica platycephala), were observed by scanning electron microscope. The tongue of these animals had two vallate papillae. In two species of the Sorex a papilla in the vallate papilla was surrounded by two separated trenches, but in the other species it was surrounded by only a continuous trench and a clear vallum. The fungiform papillae in the Sorex were less developed than those of the other species. In the Sorex and Crocidura, there was no filiform papilla on the lingual apex. These genera, however, have papillary projections in the margin of the lingual apex. The results of this investigation suggest that the Sorex and Crocidura indicate an ancient form of the mammalian tongue. These characters, furthermore, were compared among seven species in six genera added three species observed by Kobayashi et al. (1983) to this study.

Animals↗
PubMedDate not supplied

DMBA-induced intestinal tumors in the Japanese house musk shrew, Suncus murinus (Insectivora).

Intestinal tumors were induced in the Japanese house musk shrew, Suncus murinus (Family: Soricidae, Order: Insectivora) with 7,12-dimethylbenz(a)anthracene (DMBA). The animals were divided into 10 groups: groups 1-4 received gastric intubation of DMBA, groups 5-8 received intraperitoneal (i.p.) injections of this agent, and groups 9 (female) and 10 (male) were untreated and served as controls. Group 1 (females) and group 2 (males) received 10 mg DMBA at 50 days of age; group 3 (females) and group 4 (males) received 2 x 10 mg doses at 50 and 55 days of age; groups 5 and 6 (females) received weekly i.p. administration of 1.25 mg (group 5) and 2.5 mg (group 6) for 4 weeks; and groups 7 and 8 (females) received weekly i.p. administration of 1.25 mg (group 7) and 2.5 mg (group 8) for 8 weeks from 8 weeks of age. Intestinal tumors developed in 3/8 (38%) animals in group 1, 2/6 (33%) in group 2, 5/11 (45%) in group 3, 5/10 (50%) in group 4, 3/6 (50%) in group 5, 2/4 (50%) in group 6, 5/8 (63%) in group 7, and 5/6 (83%) in group 8, but not in untreated shrews up to 50 weeks of age. The induced tumors, which began to appear by 15 weeks after the initial treatment, were randomly distributed throughout the intestine. Histologically, the lesions were classified as adenocarcinomas similar to those found in humans. BrdU immunohistochemistry indicated an extension of the proliferative zone and labeling of many neoplastic cells. Local invasion was seen but no metastasis was observed.(ABSTRACT TRUNCATED AT 250 WORDS)

9,10-Dimethyl-1,2-benzanthracene↗
PubMed2004

Small mammals (Insectivora, Rodentia) as a potential source of chlamydial infection in East Slovakia.

The presence of antibodies against Chlamydophila (Chlamydia) psittaci in small mammals (Insectivora, Rodentia) in the region of East Slovakia are presented. The hosts were caught in several areas of Slovakia in habitats with different levels of anthropogenic disturbance. Research was carried out during 2000-2002. The authors examined 1,947 sera coming from 4 insectivore and 10 rodent species. Each serum was examined by micromethod of complement binding reactions using antigen Chlamydophila (Chlamydia) psittaci. Chlamydial infections were found in 251 individuals (prevalence 12.9 %) of 8 mammal species. The antichlamydial antibodies were proved at levels ranging from 1:32-1:1024. The highest prevalence of antibodies was detected in the most abundant rodent species Apodemus microps (14.8 %), Apodemus agrarius (13.9 %), Apodemus flavicolis (12.4 %), Microtus arvalis (12 %), and Clethrionomys glareolus (10.9 %). Positive hosts were registered in all studied localities. Testing of prevalence values in the individual research years confirmed significant changes. Our results showed that small mammals probably play an important role in the circulation of chlamydiae in nature.

Animals↗