SEARCH · PubMed Health

Results for “INSECTIVORA”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

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

At least 19 recordsLinked to original sources

PubMed1998

Phylogenetic positions of insectivora in eutheria inferred from mitochondrial cytochrome c oxidase subunit II gene.

For the elucidation of the phylogenetic position of insectivora in eutheria, we have sequenced the cytochrome c oxidase subunit II (COII) gene of mitochondria for three insectivoran species [musk screw (Suncus murinus), shrew mole (Urotrichus talpoides), Japanese mole (Mogera wogura)] and analyzed these amino acid sequences with neighbor-joining (NJ) method and maximum likelihood (ML) method. NJ analysis shows polyphyly of Insectivora and Chiroptera. Assuming that each of Primates, Ferungulata, Chiroptera, Insectivora and Rodentia is a monophyletic group, ML analysis suggests that Chiroptera is a sister group of Insectivora and that Ferungulata is the closest outgroup to the (Insectivora and Chiroptera) clade.

Animals↗

PubMed1982

Comparison of brain structure volumes in Insectivora and Primates. I. Neocortex.

Based on volume measurements the total neocortex increases enormously from the lower ('basal') Insectivora, through prosimians, monkeys and apes up to man. In man it is about 132 times larger than in the average basal Insectivora of (theoretical) equal body weight and 232 times larger than in the insectivoran species which has the least developed neocortex. Within the neocortex the white matter increases more markedly than the grey matter. For man the white matter reaches a value 298 times that of the basal Insectivora and the grey matter reaches a value 198 times greater. Within the grey matter the cell dense layers (laminae 2-6) increase distinctly more than the molecular layer (lamina 1). Thus in man the volume of layers 2-6 is 272 times greater than that in basal Insectivora and the molecular layer is 68 times greater. When related to the total grey matter the percentage of the molecular layer clearly decreases from about 32% in the lower Insectivora to 12% in higher primates.

Animals↗

PubMed1990

Comparison of brain structure volumes in Insectivora and primates. IX. Trigeminal complex.

Volumes of the trigeminal complex (TR) were measured in 30 species of Insectivora, 3 species of Scandentia, 18 species of prosimians, 26 species of non-human simians and in man. The relative size showed a definite tendency to decrease from 159 in Insectivora to 56 in simians (expressed as size indices). The difference in the development of the TR between Insectivora and Primates is explained by differences in the role of their oro-facial region in exploratory behavior. The largest size was found in semiaquatic Insectivora (average 283). In semiaquatic forms, the reduction of the olfactory centers is compensated by an increase in TR size. The extremely long vibrissae innervated by the trigeminal nerve seem to have a teletactile function in detecting vibrations in the water produced by potential prey.

Animals↗

PubMed1998

Molecular evidence for multiple origins of Insectivora and for a new order of endemic African insectivore mammals.

The traditional views regarding the mammalian order Insectivora are that the group descended from a single common ancestor and that it is comprised of the following families: Soricidae (shrews), Tenrecidae (tenrecs), Solenodontidae (solenodons), Talpidae (moles), Erinaceidae (hedgehogs and gymnures), and Chrysochloridae (golden moles). Here we present a molecular analysis that includes representatives of all six families of insectivores, as well as 37 other taxa representing marsupials, monotremes, and all but two orders of placental mammals. These data come from complete sequences of the mitochondrial 12S rRNA, tRNA-Valine, and 16S rRNA genes (2.6 kb). A wide range of different methods of phylogenetic analysis groups the tenrecs and golden moles (both endemic to Africa) in an all-African superordinal clade comprised of elephants, sirenians, hyracoids, aardvark, and elephant shrews, to the exclusion of the other four remaining families of insectivores. Statistical analyses reject the idea of a monophyletic Insectivora as well as traditional concepts of the insectivore suborder Soricomorpha. These findings are supported by sequence analyses of several nuclear genes presented here: vWF, A2AB, and alpha-beta hemoglobin. These results require that the order Insectivora be partitioned and that the two African families (golden moles and tenrecs) be placed in a new order. The African superordinal clade now includes six orders of placental mammals.

Africa↗

PubMed2000

The evolution of the thyroid hormone distributor protein transthyretin in the order insectivora, class mammalia.

Thyroid hormones are involved in the regulation of growth and metabolism in all vertebrates. Transthyretin is one of the extracellular proteins with high affinity for thyroid hormones which determine the partitioning of these hormones between extracellular compartments and intracellular lipids. During vertebrate evolution, both the tissue pattern of expression and the structure of the gene for transthyretin underwent characteristic changes. The purpose of this study was to characterize the position of Insectivora in the evolution of transthyretin in eutherians, a subclass of Mammalia. Transthyretin was identified by thyroxine binding and Western analysis in the blood of adult shrews, hedgehogs, and moles. Transthyretin is synthesized in the liver and secreted into the bloodstream, similar to the situation for other adult eutherians, birds, and diprotodont marsupials, but different from that for adult fish, amphibians, reptiles, monotremes, and Australian polyprotodont marsupials. For the characterization of the structure of the gene and the processing of mRNA for transthyretin, cDNA libraries were prepared from RNA from hedgehog and shrew livers, and full-length cDNA clones were isolated and sequenced. Sections of genomic DNA in the regions coding for the splice sites between exons 1 and 2 were synthesized by polymerase chain reaction and sequenced. The location of splicing was deduced from comparison of genomic with cDNA nucleotide sequences. Changes in the nucleotide sequence of the transthyretin gene during evolution are most pronounced in the region coding for the N-terminal region of the protein. Both the derived overall amino sequences and the N-terminal regions of the transthyretins in Insectivora were found to be very similar to those in other eutherians but differed from those found in marsupials, birds, reptiles, amphibians, and fish. Also, the pattern of transthyretin precursor mRNA splicing in Insectivora was more similar to that in other eutherians than to that in marsupials, reptiles, and birds. Thus, in contrast to the marsupials, with a different pattern of transthyretin gene expression in the evolutionarily "older" polyprotodonts compared with the evolutionarily "younger" diprotodonts, no separate lineages of transthyretin evolution could be identified in eutherians. We conclude that transthyretin gene expression in the liver of adult eutherians probably appeared before the branching of the lineages leading to modern eutherian species.

Alternative Splicing↗

PubMed1990

Relation of the insular claustrum to the neocortex in Insectivora.

The claustra of 9 species of Insectivora (Sorex araneus, Sorex minutus, Tenrec ecaudatus, Solenodon paradoxus, Neomys fodiens, Erinaceus europaeus, Talpa europaea, Desmana moschata, Potamogale velox) were investigated. In all examined animals we found two parts of the insular claustrum: the main part called by us the pars principalis and more medially situated lamina profunda claustri. In the "basal" Insectivora the main part is in close contact with the layer VIa of the neocortex. In some more developed "basal" and in all "progressive" Insectivora the area capsularis appears. Dorsolaterally it separates the main part of the insular claustrum from the neocortex and possesses, besides neurons, also numerous fibers of the extreme capsule. The above data strongly suggest that in the phylogenesis the insular claustrum originates from the cortex from which it gets separated by the extreme capsule. Lamina profunda claustri is rather a narrow band of neurons situated on the medial side of the pars principalis and mostly separated from it by a thin lamina of white substance. Lamina profunda is continuous with the layer VIb of the neocortex.

Animals↗

PubMed1984

Comparison of brain structure volumes in insectivora and primates. IV. Non-cortical visual structures.

The relative size of the eyes, optic nerves, chiasms and tracts, and of the dorsal nucleus of the lateral geniculate body is distinctly larger in Primates than in (theoretically) isoponderous Insectivora. Within Insectivora, the relative size is lowest in moles, medium in shrews and hedgehog-like tenrecs, and largest in hedgehogs. Within Primates, all relative sizes are on the average larger in simians than in prosimians: the eyes to a small degree, the lateral geniculate bodies moderately and the optic nerves considerably larger. The ratio between eyes and optic nerves is large in night-active primates and distinctly smaller in day-active forms, with no overlap. The only night-active simian (Aotus trivirgatus) is in line with night-active prosimians. The relative size of the non-cortical visual structures in man is in line with that of day-active simians, whereas two of the great apes (orang-utan and gorilla) are relatively low. The size of the visual structures appears to depend mainly on functional requirements and is not, or is distinctly less, related to differences in the evolutionary level. The size of the visual structures of tree-shrews (Scandentia) shows special features which are not found in Insectivora and Primates and is compatible with their separation from these orders.

Animals↗

PubMed1983

Comparison of brain structure volumes in Insectivora and Primates. III. Main olfactory bulb (MOB).

Volumes of the main olfactory bulb (MOB) in 76 species of Insectivora, Scandentia, Primates and Macroscelidea, and some of the laminar components in 34 species were measured. No statistically significant differences were found (1) between the two sides in the 162 individuals and (2) between males and females in the 19 species in which both sexes were examined. In interspecific comparisons the relative size (expressed by size indices) shows a definite tendency to decrease from Insectivora through prosimians and simians to man. The average indices were 100-64-10-3.6, respectively. Scandentia and Macroscelidea have the highest average MOB indices (135 and 166). The relative MOB size is discussed in relation to feeding and social behaviour. It was shown that MOB development is largely linked to dietary adaptations but that its importance in feeding behaviour is paralleled by a similar importance in social behaviour. Within each dietary type, MOB development is associated with the different characteristics of the occupied niche. Among Insectivora, ground-dwelling species occupy the upper, and semiaquatic species the lower positions in the size scale for the MOB. Among Primates, in closely related species, the nocturnal species have in general better developed MOBs than the diurnal species. The composition of the MOB is relatively stable, i.e. the laminar components (layers 1 + 2, 3, and 4-6) show no clear change in their percentage size from well developed to strongly reduced MOBs. Only in the diurnal simians are layers 4-6 relatively small. This corresponds with the general observation (obtained from light-microscopy) that the granular layer (layer 6) is reduced and decomposed in higher Primates, and especially in man.

Animals↗

PubMed1997

Anatomical study of the abdominal arterial system in soricids (Insectivora, Mammalia): functional and phylogenetic implications.

BACKGROUND: Information on the anatomy of the abdominal arterial system in Insectivora is scarce. We described the origin, distribution, and variations of the visceral abdominal arteries in some Soricidae in order to provide the first comprehensive data on this subject in Insectivora. Results were interpreted from a functional and phylogenetic viewpoint. METHODS: The sample examined consisted of 46 shrews (25 Crocidura russula, 12 Sorex araneus, 5 S. coronatus, 4 S. minutus) captured in the field. Animals were analyzed by injection of coloured latex solution through the left ventricle of the heart and subsequent dissection. RESULTS: The coeliacomesenteric trunk was the first visceral branch of the abdominal aorta. The cranial mesenteric artery supplied those parts of the digestive tract attached to the cranial mesentery and usually gave rise to the colic, the caudal pancreaticoduodenal, and the jejunum-ileumcolic arteries. The coeliac artery mainly vascularized the stomach, the liver and the first portion of the duodenum, and the spleen by means of several branches of the left gastric, the "common" hepatic, and the lienal arteries, respectively. The lienal arteries were double. The renal, gonadal, and median sacral arteries were also branches of the abdominal aorta. The caudal mesenteric artery emerged either from the abdominal aorta or from one of the common iliac arteries. CONCLUSIONS: Differences in the abdominal blood supply between soricids and more advanced mammals are basically focused on the irrigation of the digestive tract. The presence of double lienal arteries and the absence of right gastric artery and left and right gastroepiploic arteries are related to the primitive type of gut presented in the order and are thought to be the plesiomorphic condition in Eutheria.

Abdomen↗

PubMed1998

The size of sebaceous glands in relation to the size of hair follicles on the heads of some small mammals (Insectivora, Chiroptera, Rodentia).

Many large sebaceous glands have been described, and functions such as scent production suggested, but gland size has seldom been studied in relation to the surface area of their hair follicles. However, investigating this relationship is essential for establishing whether glands produce more sebum than would be required for lubricating associated hair alone. Here, the relationship between sebaceous gland size and the surface area of the associated hair follicles has been studied. Glands on the heads of 20 species from three orders were compared with those associated with fur hairs. In all species, the fur hairs had small hair follicles with small sebaceous glands, as had the mystacial and submandibular hairs of Rodentia. Medium-sized glands and hairs were found in the mystacial and submandibular region in Insectivora, and in the circumoral region in Chiroptera and Rodentia. Large glands and hairs were found on a pad in the corner of the mouth in Rodentia. Although the size of glands was not directly proportional to hair size, some gross trends were noted. Vibrissae had either no or very small sebaceous glands. It is likely that sebum has to be provided from elsewhere to lubricate their surfaces. The glands on the snout of Insectivora and Chiroptera are clearly enlarged and could probably produce more sebum than would be required for grooming vibrissae alone. In Rodentia, vibrissae were surrounded by small hair and glands, and the nearest glands large enough to provide sebum were the glands on the pad in the mouth corner.

Animals↗

PubMed1990

Topography and cytoarchitectonics of small-cell nuclei of the tuber cinereum in Insectivora.

Results are presented of the comparative studies on location and cytoarchitectonics of the nuclei in tuber cinereum of hypothalamus in 3 insectivorous mammals: hedgehog, mole and common shrew. Paraffin scraps were stained with the methods of Nissl and Klüver-Barrera. It was found that this part of the brain in Insectivora was characterized by: well developed nucleus infundibularis, less developed nucleus dorsomedialis compared to nucleus ventromedialis, weakly pronounced differentiation of the periventricular part, and lack of nucleus tuberis lateralis. From among the Insectivora under study, cytoarchitectonics of tuber cinereum in mole and common shrew was more or less similar, while it differed from that of hedgehog, in which nucleus dorsomedialis and nucleus hypothalamicus parvocellularis were less developed, nucleus ventromedialis was different, and so was cell structure of nucleus infundibularis.

Animals↗

PubMed1987

Comparison of brain structure volumes in Insectivora and primates. VI. Paleocortical components.

Volumes of the main structures of the 'paleocortical complex' were measured in 2 species of Macroscelidea, 39 species of Insectivora, 3 species of Scandentia, 18 species of prosimians, 26 species of nonhuman simians and man. Changes in the relative size from Insectivora through man (expressed by size indices) showed a definite tendency to decrease in the lateral olfactory tract (TRL), its nucleus (NTO), and in the olfactory cortices (RB, PRPI, TOL) and to increase in the anterior commissure (COA) and substantia innominata (SIN). The reduction in the olfactory cortices is strongest for the retrobulbar region (RB, = anterior olfactory nucleus in Anglo-American terminology), and least for the olfactory tubercle (TOL). In prosimians, the reduction clearly parallels that of the main olfactory bulb (BOL); in simians and especially in man, the indices of PRPI and TOL are clearly larger than those of BOL. Possible reasons for these growing deviations were discussed: (1) increasing difficulties in clearly homologizing and delineating the olfactory cortices in the microsmatic simians, and (2) non-olfactory functional influences.

Animals↗

PubMed1988

Comparison of brain structure volumes in insectivora and primates. VIII. Vestibular complex.

Volumes of the vestibular complex (VC) and its four main components (medial, inferior, lateral and superior nuclei; VM, VI, VL and VS) were measured in 28 species of Insectivora, 3 species of Scandentia, 18 species of prosimians, 26 species of non-human simians and in man. The relative size showed a definite tendency to increase 2-4.5 times from Insectivora through simians (expressed by size indices). The highest increase was found in VS, the lowest in VI and, in Pongidae and man, also in VL. The differences are discussed with respect to differences in the locomotory behavior of the various taxonomic groups and to differences in the fiber connections and thus different functions of the various nuclei. Species which exploit a 3-dimensional environment and execute fast and complicated head and body movements have a larger VC than closely related species confined to the ground or which are less skilled leapers. The great increase of the VS may be related to the predominant role of vision in primates, particularly in simians.

Animals↗

PubMed1987

Comparison of brain structure volumes in Insectivora and primates. VII. Amygdaloid components.

Volumes of the amygdaloid complex (AMY) and some subdivisions were measured in 2 species of Macroscelidea, 39 species of Insectivora, 3 species of Scandentia, 18 species of prosimians, 26 species of simians and man. Changes in the relative size from Insectivora through man (expressed by size indices) showed a definite tendency to increase in the cortico-basolateral subdivision (LAM) and more or less constant relations in the centromedial subdivision (MAM), except for the nucleus tractus olfactorii lateralis (NTO), which becomes distinctly reduced. The reduction of NTO is even stronger than that of the main olfactory bulb (BOL), which in simians and man is small but distinct, whereas NTO is hardly recognizable in most of these forms. In the LAM group the size increase of the large-celled part of the basal nucleus (MCB) is less than that of the small-celled components (including the lateral nucleus). The differences between LAM and MAM groups are discussed with regard to the predominant fiber connections, which in MAM are stronger with conservative brains parts (brainstem), and in LAM with progressive brain parts (e.g. neocortex).

Amygdala↗

PubMed1982

Comparison of brain structure volumes in Insectivora and Primates. II. Accessory olfactory bulb (AOB).

A total of 134 individuals from 75 species were investigated with regard to existence and size of the accessory olfactory bulb (AOB). Based on volume measurements the AOB and its three measured components do not show any uniform trend in size changes from lower Insectivora through higher Primates. The investigated structures are in most prosimians clearly larger than in low Insectivora, in most New World simians clearly smaller, and in Old World simians absent. Even within narrowly related groups there may exist strong differences in size and structural differentiation. In AOBs of large relative size, the inner granular layer (layer 6) is relatively larger than in AOBs of small relative size. The variability in size is especially large in those individuals and species with a relatively small AOB. No differences were found between the AOBs (1) of the two sides within the same individual (brain) and (2) between the two sexes within the same species. There is no interdependency in size between MOB (main olfactory bulb) and AOB. The relative size of the AOB is discussed in relation to various ecological and behavioural considerations. No clear relations could be found between the size of the AOB and dietary specialization. A comparison of the relative size of the AOB with activity cycle, sexual behaviour and the use of pheromones in various species of Primates supports the suggestion that the vomeronasal system may be involved in sexual and/or social interaction.

Animals↗

PubMed1995

Experimental models for carcinogenesis in the house musk shrew, Suncus murinus, Insectivora.

Animal carcinogenicity studies have mainly been performed on rodents. From the phylogenetic point of view, animals closer to humans must be included in these studies. Insectivora are considered to be the most primitive placental mammals and much closer to the early primates than rodents. Among the insectivora, the house musk shrew (Suncus murinus, family Soracidae), has been bred under laboratory condition. This animal is small having a short life span, and a comparatively low incidence of spontaneous tumor provides a useful animal model for tumor induction studies. We have examined the carcinogenicity of several chemicals known to produce tumors in rodents and found shrews, in general, to be sensitive to these chemicals but often showed different targets compared to rodents, and some chemicals tested were demonstrated not to be carcinogenic. Here we describe the carcinogenic studies performed in our laboratory and review other works including the occurrence of spontaneous tumors in shrews. Shrew carcinogenesis may fill up the gap of knowledge existing between the rodents and human beings.

Animals↗

PubMed1996

Females of four mole species of genus Talpa (insectivora, mammalia) are true hermaphrodites with ovotestes.

We studied the anatomical, histological, and genetic features of the sexual tract in four European mole species of the genus Talpa (Insectivora, mammalia): T. occidentalis, T. europaea, T. romana, and T. stankovici. All XY individuals had a normal male phenotype, whereas all XX individuals in all four species had features that identified them as intersexes. These individuals were nonetheless presumed to be functionally fertile females. Intersexuality was manifested mainly as gonadal hermaphroditism, with all females possessing bilateral ovotestes. The gonads were composed of a small portion of histologically normal ovarian tissue and a variably sized, generally large mass of disgenetic testicular tissue, accompanied by a small, rudimentary epididymis. The rest of the sexual tract was typically female, including oviducts, uterus, and vagina of normal appearance. Polymerase chain reaction (PCR) and Southern blotting analyses showed that the mammalian testis-determining gene SRY is present in males but not in females. Part of the conserved sequence of the mole SRY gene was cloned and sequenced after PCR amplification in two of the four mole species (T. occidentalis from Spain and T. romana from Italy). Sequences were identical in these two species and were very similar to those of the human and mouse SRY gene. Our findings constitute the first evidence of the existence of a genus-specific case of true hermaphroditism, probably due to a very ancient mutation that fixed in populations of the ancestral species from which contemporary moles evolved. The possible nature of this mutation is discussed with regard to the cytologic, histologic, and genetic features of the gonads in Talpa females.

Animals↗

PubMed1995

Descriptive kinetics of the seminiferous epithelium cycle and genome size in the mole Talpa occidentalis (Insectivora).

The male germ cell cytodifferentiative process of the mole Talpa occidentalis is described. Cytochemical procedures were used 1) to follow acrosome formation and spermatid differentiation, dividing the seminiferous epithelium cycle into ten stages, each characterized by typical germ cell-to-cell associations, and recognizing 13 steps in spermatid differentiation; 2) to monitor, in situ, histones replacement by protamines at step 11 of the spermiogenic process. The seminiferous epithelium cycle of the mole has the basic histological features present in all mammals and appears rather similar to that of the common shrew (Sorex araneus), the only one so far known among Insectivora. The metabolism of the DNA-associated proteins reveals that protamines replace histones during the late steps (11-13) of spermiogenesis, mRNA for protamines having been synthesized at an earlier step (assuming that in the mole this occurs at the first spermiogenic steps, as in the house mouse). In addition the genome size (5.0 pg) and the AT/GC ratio (1.3) were evaluated.

Acrosome↗