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PubMed1989

Ultrastructural features of the developing eosinophils in bone marrow and spleen of the musk shrew, Suncus murinus.

Eosinophilopoiesis in the musk shrew, Suncus murinus, a representative of the order Insectivora, was studied by light and electron microscopy. To examine biochemical features of cytoplasmic granules, extraction with proteolytic enzymes was carried out on ultrathin sections of bone marrow. In this species, eosinophils are produced in the same manner in both spleen and bone marrow. Developing eosinophils were distinguished as belonging to four stages, recognized by ultrastructural changes in cytoplasmic organelles as well as the eosinophilic granules during maturation. Granulogenesis began by budding of vacuoles containing flocculent material from the concave face of the Golgi apparatus, in the promyelocyte to myelocyte stage. The matrix of developing granules transformed into a finely granular structure, and the large spherical granules of mature eosinophils were homogeneous without crystalline cores. It was shown by proteolytic enzyme extraction that the proteinaceous cores of mature granules were uniformly removed; there was no evidence that they contained crystalloid inclusions. These results indicate that shrew eosinophils can be regarded as cells that retain a prototype of eosinophil granules, probably like those of ancestral mammals rather than those of higher living Mammalia.

Animals↗
PubMed1986

Anatomy and histology of the musk shrew (Suncus murinus) prostate.

Gross anatomy and the light and electron microscopic characteristics of the musk shrew (Suncus murinus, Insectivora) prostate are described. The prostate is a pair of compound tubuloalveolar glands with one main excretory duct for each gland. Each gland is divided into ventral and dorsal lobes. The tubuloalveoli are larger in diameter and the secretory cells are lower in the ventral than in the dorsal lobes. Probable spontaneous release of secretory granules and accumulation of secretory material in secretory lumina are only observed in the ventral lobes. Secretory material is often crystallized in the secretory lumina. The epithelium of excretory ducts consists of mucous-type secretory cells and the boundary between this epithelium and the glandular epithelium is complex. The glandular epithelium consists of secretory and clear cells. This report illustrates that the structure of the prostate of musk shrew is unique among mammals.

Animals↗
PubMedDate not supplied

Biochronological implications of the Arvicolidae (Rodentia, Mammalia) from the Lower Pleistocene hominid-bearing level of Trinchera Dolina 6 (TD6, Atapuerca, Spain).

Level TD6 of the Trinchera Dolina Section in the railway cutting of the Sierre de Atapuerca (Trinchera del Ferrocarril) has yielded a rich small mammal assemblage (26 species) in association with fossil human remains of Homo antecessor. The arvicolids of TD6 are identified as: Mimomys savini, Microtus seseae, Stenocranius gregaloides, Terricola arvalidens, Iberomys huescarensis, Allophaiomys chalinei, and Pliomys episcopalis. The rodent association also includes large rodents (i.e., Castor fiber, Marmota sp., and Hystrix refossa) and the small Allocricetus sp., Eliomys helleri, Micromys minutus, and Apodemus aff. flavicollis. The small vertebrate remains also include Insectivora (Beremendia fissidens, Sorex sp, Neomys sp., Crocidura sp., Galemys sp., Talpa sp., Erinaceus sp.), Chiroptera (Miniopterus schreibersii, Myotis sp., Rhinolophus sp.), and Lagomorpha (Oryctolagus sp., Lepus sp.), as well as lizards, birds and amphibians. The H. antecessor remains are derived from a 15 cm thick layer at the top of TD6 (TD6-T36-43), where A. chalinei, H. refossa and Marmota sp. do not occur. The paleomagnetic Matuyama/Brunhes boundary is found in the overlying level TD7 of the Gran Dolina Section. On the basis of the arvicolids, TD6 can be referred to the Biharian biochron. The Matuyama/Brunhes boundary is fixed in the late Biharian (Microtus-Mimomys rodent Superzone). The species M. savini (without M. pusillus), as well as the evolutionary stage of Microtus s.l., are characteristic of the Late Biharian. The evolutionary level of the species M. savini, T. arvalidens, S. gregaloides indicates that TD6 is older than West Runton (type Cromerian). In the Trinchera Dolina Section we are able to calibrate, for the first time, the evolutionary level of important biochronological markers with magnetostratigraphy. We propose that a radiation of Microtus s.l., along with the first appearance of primitive S. gregaloides, T. arvalidens and Iberomys, took place just before the Matuyama/Brunhes boundary. These species can be considered as characteristic elements of early Pleistocene faunas.

Animals↗
PubMed1999

The evolution of the scrotum and testicular descent in mammals: a phylogenetic view.

The adaptive significance of the scrotum and the evolution of the descent of the testicles and epididymis have been a focus of interest among biologists for a long time. In this paper we use three anatomical character states of the scrotum and descensus: (1) testicles descended and scrotal; (2) testicles descended but ascrotal; (3) testicles not descended (testicondy). These states are then mapped on an up to date phylogeny of the Mammalia. Three main points arise out of this mapping procedure: (1) the presence of a scrotum is either primitive in extant Mammalia or primitive within eutherian mammals except Insectivora; (2) evolution has generally proceeded from a scrotal condition to progressively more ascrotal; (3) loss of testicular descensus is less common in mammalian evolution than is loss of the scrotum. In the light of these findings we discuss some current hypotheses regarding the origin and evolution of the scrotum. We find that these are all incomplete in so far as it is not the presence of the scrotum in various mammal groups that requires explaining. Instead, it is the reverse process, why the scrotum has been lost in so many groups, that should be explained. We suggest that the scrotum may have evolved before the origin of mammals, in concert with the evolution of endothermy in the mammalian lineage, and that the scrotum has been lost in many groups because descensus in many respects is a costly process that will be lost in mammal lineages as soon as an alternative solution to the problem of the temperature sensitivity of spermatogenesis is available.

Animals↗
PubMed1998

Highly congruent molecular support for a diverse superordinal clade of endemic African mammals.

A solution to higher level mammalian phylogeny is going to depend on the congruent establishment of superordinal groupings followed by a linking together of these clades. We present congruent and convincing evidence from four disparate nuclear protein coding genes and from a tandem alignment of the 12S-16S mitochondrial region, for a superordinal clade of endemic African mammals that includes elephant shrews, aardvarks, golden mole, elephants, sirenians, and hyraxes. Because of strong support for golden mole as part of this clade, the Insectivora are rendered paraphyletic or polyphyletic, with constrained monophyly of the insectivores judged significantly worse in the vast majority of tests. Branching arrangement within this clade remains highly uncertain; however, a tandem alignment of the protein coding genes suggests elephant shrew is the earliest African lineage. None of the individual data sets or combinations of data sets support the widely held view of a mirorder Tethytheria (Sirenia/Proboscidea), although only a tandem alignment of protein coding and mitochondrial loci significantly rejects this association. The majority of the data sets and analyses provide strong support for Caviomorpha as part of a monophyletic Rodentia.

Africa↗
PubMed1992

Meso-diencephalic regions projecting to spinal cord and dorsal column nuclear complex in the hedgehog-tenrec, Echinops telfairi.

The distribution of neurons projecting to the spinal cord and dorsal column nuclear complex was investigated in the mesodiencephalic regions of the lesser hedgehog-tenrec, Echinops telfairi (Insectivora) by using the retrograde flow technique. While only few neurons projected to the dorsal column nuclear complex, numerous cells were found to give rise to spinal projections. Rubro-spinal neurons of various sizes were distributed over the entire rostrocaudal extent of the contra-lateral nucleus; a few neurons were also located ipsilaterally, Unlike that of the opossum, the projection appeared to be somatotopically organised. Interstitio-spinal neurons were differentiated into several subpopulations according to their location and laterality of projection. In the ipsilateral periventricular grey, in addition, there was a distinct population of cells possibly corresponding to the nucleus of Darkschewitsch. The mesencephalic central grey contained relatively few labeled neurons, the great majority of them being mesencephalic trigeminal, ectopic cuneiform or midline cells. Labeled cuneiform and midline cells, on the other hand, were quite numerous, extending both from a level just caudal to the trochlear nucleus to levels far beyond the rostral tip of the somatic oculomotor nucleus. The discrepancy between the poorly differentiated oculomotor nuclei and the apparently well-developed Edinger-Westphal complex is discussed. Hypothalamo-spinal neurons were essentially restricted to dorsal regions: the hypothalamic paraventricular nucleus (PAV), the dorso-medial (DmHy) and dorso-intermediate cell groups as well as the lateral hypothalamic zone. The latter two cell groups were bilaterally labeled, while the labeled neurons in DmHy and PAV were located predominantly ipsilaterally. Labeled neurons in the amygdala, colliculus superior and mesencephalic trigeminal nucleus were only found following cervical injections; all other mentioned areas and the posterior commissure complex projected to, at least, midthoracic level.

Animals↗
PubMed1988

Retinofugal projections in hedgehog-tenrecs (Echinops telfairi and Setifer setosus).

Using the autoradiographic tracing technique the retinal projections were studied in the tenrecs, Echinops telfairi and Setifer setosus (insectivora, tenrecidae). Bilateral projections were found to the n. suprachiasmaticus, the anterior hypothalamic area, the dorsal and ventral lateral geniculate bodies, the pretectal olivary nucleus and the superior colliculus. The contralateral projections were usually more intense than the ipsilateral ones except the retinohypothalamic connections. A partial segregation of the projection fields from both eyes was present in the dorsal and ventral lateral geniculate bodies. In the superior colliculus retinal fibers predominantly involved the stratum zonale and the upper portion of the stratum griseum superficiale on both sides. The projections to the deeper portion of the colliculi were rather faint, particularly on the ipsilateral side. Target areas receiving contralateral projections exclusively were the periamygdaloid area (labeled only in Setifer), the terminal accessory nuclei including the n. tractus optici and the inferior colliculus. The data are compared with other species. The most striking finding may concern the projection to the medial terminal nucleus being quite prominent in marsupials and most eutherian mammals (including the erinaceomorphous hedgehogs), but greatly reduced in tenrecs and primates.

Animals↗
PubMed1991

Hazardous exposure of ground-living small mammals to cadmium and lead in contaminated terrestrial ecosystems.

The dietary exposure to cadmium and lead of two ground-living species of small mammals, i.e., shrews Sorex araneus (Insectivora) and voles Microtus agrestis (Rodentia), was investigated and related to metal loads in target organs (kidneys and liver). The study was done in two natural areas polluted with cadmium and lead originating from urban and industrial metal sources. The average intake of cadmium by the herbivorous voles varied between 0.1 and 0.4 micrograms/g/day and of lead between 2 and 10 micrograms/g/day. The carnivorous shrews showed a considerably higher metal intake rates, i.e., cadmium 3 to 16 micrograms/g/day and lead 19 to 53 micrograms/g/day, which was largely due to the consumption of contaminated earthworms (Oligochaeta). An average cadmium intake of 15 micrograms/g/day or a lead intake of 20 micrograms/g/day corresponded with critical renal metal loads of 120 micrograms/g for cadmium and 25 micrograms/g for lead, which are indicative of adverse health effects. The renal metal loads in shrews reached the critical level, but they remained far below this level in voles. The results indicate a greater risk of toxic exposure to cadmium and lead in soricine shrews than in microtine rodents.

Animals↗
PubMed1999

Evolution of Mhc-DRB introns: implications for the origin of primates.

Introns are generally believed to evolve too rapidly and too erratically to be of much use in phylogenetic reconstructions. Few phylogenetically informative intron sequences are available, however, to ascertain the validity of this supposition. In the present study the supposition was tested on the example of the mammalian class II major histocompatibility complex (Mhc) genes of the DRB family. Since the Mhc genes evolve under balancing selection and are believed to recombine or rearrange frequently, the evolution of their introns could be expected to be particularly rapid and subject to scrambling. Sequences of intron 4 and 5 DRB genes were obtained from polymerase chain reaction-amplified fragments of genomic DNA from representatives of six eutherian orders-Primates, Scandentia, Chiroptera, Dermoptera, Lagomorpha, and Insectivora. Although short stretches of the introns have indeed proved to be unalignable, the bulk of the intron sequences from all six orders, spanning >85 million years (my) of evolution, could be aligned and used in a study of the tempo and mode of intron evolution. The analysis has revealed the Mhc introns to evolve at a rate similar to that of other genes and of synonymous sites of non-Mhc genes. No evidence of homogenization or large-scale scrambling of the intron sequences could be found. The Mhc introns apparently evolve largely by point mutations and insertions/deletions. The phylogenetic signals contained in the intron sequences could be used to identify Scandentia as the sister group of Primates, to support the existence of the Archonta superorder, and to confirm the monophyly of the Chiroptera.

Animals↗
PubMed2001

Short interspersed elements (SINEs) from insectivores. Two classes of mammalian SINEs distinguished by A-rich tail structure.

Four tRNA-related SINE families were isolated from the genome of the shrew Sorex araneus (SOR element), mole Mogera robusta (TAL element), and hedgehog Mesechinus dauuricus (ERI-1 and ERI-2 elements). Each of these SINEs families is specific for a single Insectivora family: SOR, for Soricidae (shrews); TAL, for Talpidae (moles and desmans); ERI-1 and ERI-2, for Erinaceidae (hedgehogs). There is a long polypyrimidine region (TC-motif) in TAL, ERI-1, and ERI-2 elements located immediately upstream of an A-rich tail with polyadenylation signals (AATAAA) and an RNA polymerase III terminator (T(4-6)) or TCT(3-4)). Ten out of 14 analyzed mammalian tRNA-related SINE families have an A-rich tail similar to that of TAL, ERI-1, and ERI-2 elements. These elements were assigned to class T+. The other four SINEs including SOR element have no polyadenylation signal and transcription terminator in their A-rich tail and were assigned to class T-. Class T+ SINEs occur only in mammals, and most of them have a long polypyrimidine region. Possible models of retroposition of class T+ and T- SINEs are discussed.

Animals↗
PubMed1984

Comparative anatomical study of the tegmentomammillary projections in some mammals: a horseradish peroxidase study.

Mammillary projections from each subnuclei of Gudden 's tegmental nuclei were investigated by retrograde transport of horseradish peroxidase (HRP) in the cat, rat, guinea pig, golden hamster and house shrew (Suncus murinus, Insectivora). The dorsal tegmental nucleus of Gudden (TD) is composed of the pars dorsalis (TDD) and the pars ventralis ( TDV ) in the cat, rat, guinea pig, and golden hamster, but the TD of the house shrew can not be divided. The ventral tegmental nucleus of Gudden (TV) is composed of the pars principalis (TVP) and the pars suprafascicularis ( TVS ) in the golden hamster and house shrew, but the TVS is not recognized in the cat, rat and guinea pig. The TDV projects to the lateral mammillary nucleus, and the TVP projects to the medial mammillary nucleus ipsilaterally in the cat, rat, guinea pig and golden hamster. The TVS of the golden hamster projects to the medial mammillary nucleus. The TVP and TVS of the house shrew project to the medial mammillary nucleus, and the TVS also to the lateral mammillary nucleus. In addition, the pars compacta of the nucleus centralis superior projects to the medial mammillary nucleus in the rat, guinea pig and golden hamster. However, the TDD sends no fibers to the mammillary nuclei in these 5 species of mammals.

Animals↗
PubMed1992

Neuropeptide Y-like immunoreactive neurons in the suprachiasmatic-subparaventricular region in the hedgehog-tenrec.

The distribution of the neuropeptide Y (NPY) was studied in geniculate and peri-chiasmatic regions in the lesser hedgehog-tenrec, Echinops telfairi (Insectivora). Only few neurons demonstrated NPY-like immunoreactivity in the ventral lateral geniculate nucleus. In contrast, NPY-immunoreactive perikarya were clearly present in the suprachiasmatic nucleus (SCh) and dorsal and caudal to it. The latter region might correspond to the subparaventricular zone (SPV), recently identified in the rat as an additional area involved in processing circadian rhythms. While the distribution of a distinct cell population across nuclear boundries in both SCh and SPV might conform to the present idea of processing circadian rhythms, the presence of NPY-like immunoreactive neurons in these areas is rather unusual. In mammals, such neurons have only been demonstrated so far in the mentioned insectivore as well as in man.

Animals↗
PubMed1995

Heart and lung adaptations to pregnancy and lactation in a crocidurine shrew.

Heart and lung mass, rate of oxygen consumption (VO2), respiration rate (fR), tidal volume (VT), and heart rate (fH), were measured at rest and thermoneutrality in the shrew Crocidura russula monacha [(This shrew is claimed to be Crocidura suaveolens (Catzeflis, F., T. Maddalena, S. Hellwing and P. Vogel (1985). Unexpected findings on the taxonomic status of East Mediterranean Crocidura russula auct. (Mammalia, Insectivora). Zeitschrift fur Saugetierkunde 50: 185-201)] in nullipar (N), pregnant (P) and lactating (L) females. The heart mass of N females is large (0.86% of body mass) but fH is slow (70% of that expected by mammalian allometry), while lung mass is small (87% of expected) and fR is high (47% above expected). The 31% higher than expected expired ventilation (VE) matches the 25% higher than expected VO2. In P females the fH of 560 min-1 did not change but it increased in L females to 620 min-1. VE did not change in P females but decreased in L females from 11.3 ml center dot min-1 to 10.1 ml min-1. The normal VT decreased in P and L females from 47.3 mu l to 38.4 mu l and 37.8 mu l respectively. The lower than expected resting fH of N females may provide sufficient scope for increased heart work and oxygen supply during exercise. The large heart may be more efficient. Hyperventilation in N females is indicated by the calculated relatively high fractional concentration of oxygen in expired air (FECO2), and low fractional concentration of CO2 in expired air (FECO2) (17.7% and 3.2% respectively), the high oxygen partial pressure in alveolar gas (PAO2) and low alveolar CO2 (PACO2), 119 and 34 Torr respectively, which facilitate O2 transport through the lung air-blood barrier. The elevated VO2 in P and L females is achieved by increased respiratory efficiency from the normal 15%, to 24% and 29% respectively.

Adaptation, Physiological↗
PubMed1990

Small mammals as biological indicators of radioactive contamination of the environment.

An investigation was carried out in Sweden aimed at studying the contamination of small mammals (orders Rodentia and Insectivora) following the Chernobyl accident. The animals were captured in three differently contaminated areas in Sweden and, for control, in an area with negligible fallout. The results obtained show that the activity in the captured animals was correlated with surface deposition. The differences between the species investigated and the influence of feeding habits on the contamination levels are discussed.

Accidents↗
PubMed1993

The primary structure of pancreatic polypeptide from a primitive insectivorous mammal, the European hedgehog (Erinaceous europaeus).

Pancreatic polypeptide (PP) has been isolated from extracts of the pancreas of the European hedgehog (Erinaceous europaeus) which is a representative of the order Insectivora, deemed to be the most primitive group of placental mammals. Pancreatic tissues were extracted in acidified ethanol and the peptide was purified chromatographically using a PP C-terminal hexapeptide amide specific radioimmunoassay to monitor purification. Two major PP-immunoreactive peptides were baseline-resolved following the final analytical reverse phase HPLC fractionation. Each was separately subjected to plasma desorption mass spectroscopy (PDMS) and gas-phase sequencing. The molecular masses of each peptide were similar: (I) 4237.6 +/- 4 Da and (II) 4238.2 +/- 4 Da. The full primary structures of each peptide were deduced and these were identical: VPLEPVYPGDNATPEQMAHYAAELRRYINMLTRPRY. The peptides were deemed to be amidated due to their full molar cross-reactivity with the amide-requiring PP antiserum employed in radioimmunoassay. The molecular mass (4233.8 Da) calculated from the sequence was in close agreement with PDMS estimates and the reason for the different retention times of each peptide is unknown at present. Hedgehog PP exhibits only 2 unique amino acid substitutions, at positions 1 (Val) and 19 (His), when compared with other mammalian analogues.

Amino Acid Sequence↗
PubMed1994

Identification of chicken GnRH II in brains of metatherian and early-evolved eutherian species of mammals.

Two molecular forms of GnRH (chicken GnRH II and a second variant) are present in the brains of species from all the major vertebrate groups. In mammals, two forms are present in metatherian species and early-evolved eutherian species, but chicken GnRH II has not been identified in more advanced eutherian species. We investigated the nature of GnRH molecular forms in several early-evolved mammalian species, using high performance liquid chromatography and radioimmunoassay with specific GnRH antisera. These chromatographic and immunological data indicate that in the brains of a metatherian species (possum, Trichosurus vulpecula) and in two early-evolved eutherian species (order Insectivora: musk shrew, Suncus murinus and mole, Chrysochloris asiatica), both mammalian and chicken II GnRHs are present, while in another relatively early-evolved eutherian species (order Chiroptera: bat, Miniopterus schreibersii) only mammalian GnRH is present. In the adult possum and mole brains the proportion of chicken GnRH II was lower than that of mammalian GnRH, while in the musk shrew brain chicken GnRH II predominated. A peptide likely to be mammalian proGnRH was detected in the brains of the three eutherian species (musk shrew, mole, and bat). These findings suggest that metatherian and primitive eutherian species of mammals continue to express chicken GnRH II as in the vast majority of nonmammalian vertebrates, while the peptide is apparently not expressed in modern placental mammalian species. The functional significance of chicken GnRH II is not yet clear, but there are indications that it has a neurotransmitter or neuromodulator role in addition to that of regulating pituitary hormone release in certain vertebrate species.

Animals↗
PubMed1993

Accumulation of heavy metals in the mole in Finland.

Metal concentrations (Cu, Ni, Zn, Cd, Cr, Hg, Pb and Mo) were analysed from the liver and kidneys of moles, Talpa europaea L. (Insectivora), trapped in southern Finland on both contaminated and rural areas. In rural areas the concentrations of Cd, Cu, Zn, Pb and Mo were lower in juveniles (individuals in their first summer), except for Zn in the liver, which was lower in adults. When the animals were divided into annual classes (0-6 years), Cd and Mo concentrations in the liver increased significantly with age, while concentrations of Cu, Zn and Cr tended to decrease. Female moles had higher Pb concentrations than males, especially adult females, which also had lower levels of Cu in the liver than adult males. Moles in the metropolitan area of Helsinki clearly differed from those in rural areas in that the concentrations of heavy metals in these moles were higher (especially for the most toxic metals: Cd, Pb and Hg), and their body weight was lower. The renal concentrations of Cd in most of the moles in Helsinki exceeded the threshold that has been shown to have a nephrotoxic effect in mammals. In one subsample from Helsinki, Pb and Zn concentrations in the mole liver decreased as the distance from the highway increased. Concentrations of Pb in earthworms and several heavy metals in soil also decreased similarly in the same area. Our data indicate that Pb accumulates in moles through their diet of earthworms.

Journal Article↗