White-toothed Shrew Research Articles

Tissue, age, and sex distribution of thallium in shrews from Doñana, a protected area in SW Spain

In 1998, the protected area of Doñana, an important natural region in SW Europe, was affected with great amount of acidic waters and sludge from a pyrite mine loaded with toxic metals such as thallium (Tl). Since this ecological catastrophe, several studies have addressed the effects of this pollution on the flora and fauna in this protected area. However, in contrast to other non-essential metals, scarce information on Tl was available after this disaster, especially in terrestrial environments. This study reported a 3- and 10-fold increase in Tl in liver and kidneys, respectively, of the greater white-toothed shrew, Crocidura russula, in the polluted site in comparison with reference animals. Kidneys showed the highest concentrations of this metal in the polluted site, whereas both organs analysed have similar concentrations in the reference site. Although no significant age-dependent variation was found, adults had higher concentrations than juveniles. Moreover, females showed higher concentrations than males. These results demonstrate the high entrance and transfer of Tl in terrestrial food-chains. To the best of my knowledge, these data constitute the first measurements of Tl in mammals from the protected area of Doñana and are among the few available for insectivorous mammals.

Cytogenetic and Molecular Relationships between Zarudny's Rock Shrew (Crocidura zarudnyi; Mammalia: Soricomorpha) and Eurasian Taxa

We karyotyped and sequenced 1,140 base pairs of the mitochondrial DNA cytochrome b of a specimen of Zarudny's rock shrew (Crocidura zarudnyi) from Baluchestan, southeastern Iran, to clarify its cytogenetic and molecular relationships with other Eurasian species of Crocidura. According to the karyotype (2N = 40, FN = 50), Zarudny's rock shrew belongs to the group of the lesser white-toothed shrew (C. suaveolens), which is different from other known crocidurine karyotypes, considering the combination of the diploid and fundamental number of chromosomes. Molecular results revealed that C. zarudnyi is included in a monophyletic clade with the C. suaveolens group, where it is a sister taxon to the others (mean Kimura 2-parameter distance = 9.7%).

Immunocompetence and helminth community of the white-toothed shrew, Crocidura russula from the Montseny Natural Park, Spain

Host immunocompetence assessed by spleen size and response to phytohaemagglutinin (PHA) injection may give some indications on the control of parasite infection and on host mediation effect, through immunity, on parasite community structure. We investigated the helminth community and immunocompetence of the white-toothed shrew in a small area to test the relationship between immunocompetence and intensity of helminth infection. At the proximate level and if spleen mass and PHA response reflect the level of immunocompetence, we expected that individuals with a large spleen or a high PHA response should harbour a lower parasite load than individuals with relatively small spleen or low PHA response. In addition, we predicted that the structure of the helminth community should be mediated by the host’s immune defence. Spleen mass was linked to helminth infection. Nematodes and cestodes were negatively associated within hosts. PHA response was not related to total helminth intensity of infection but was negatively related to cestode intensity and positively to nematode intensity. This result suggests either a differential modulating effect on immunity by the two groups of worms or the existence of an antagonistic association between nematodes and cestodes mediated by the immune response of the host.

Bioaccumulation of metals and effects of landfill pollution in small mammals. Part I. The greater white-toothed shrew, Crocidura russula

Here we quantified the bioaccumulation of metals (lead, mercury, cadmium, iron, magnesium, zinc, copper, manganese, molybdenum, and chromium) and assessed several morphological (RI, relative weights) and genotoxic parameters as biomarkers of pollution from the landfill of Garraf (Barcelona, NE Spain). Specimens of Crocidura russula (Insectivora, Mammalia) from the landfill site showed increased Pb, Cd, Mg, Zn, Cu, and Cr concentrations in their tissues. Levels of mercury were below detection limits. Concentrations of Cd, Pb, and Cr varied significantly with age and no differences were found between males and females. While no differences were found in morphological parameters between shrews from the two sites, those from the polluted one showed more micronuclei in blood than those from reference site (1.786+/-0.272 vs. 0.088+/-0.045 per thousand; U=46.000, p<0.001). The considerable amounts of potentially toxic metals (Pb till 59.71 and Cd till 56.57microgg(-1) DW in kidneys) and the genotoxic effects indicate the harmful effect on biota. We consider necessary biomonitoring this landfill sited in a partially protected area.

How does the greater white-toothed shrew, Crocidura russula, responds to long-term heavy metal contamination? — A case study

Heavy metals accumulation in parallel with the evaluation of physiological and biochemical effects resulting from continued metal exposure were considered here using for the first time the great white-toothed shrew Crocidura russula as an in vivo model. Shrews were originated from an abandoned lead/zinc mining area and from a reference area, both in Alentejo, southern Portugal. Hepatic contents of nickel, copper, zinc, cadmium, mercury and lead were quantified by Inductively Coupled Plasma Mass Spectrometer (ICP-MS). Haematological parameters (white blood cells, red blood cells, haemoglobin and haematocrit) were obtained in a Coulter Counter Analyser and biochemical markers of the redox balance (glutathione S-transferase, glutathione peroxidase, and glutathione reductase) activities were measured spectrophotometrically using a Duo-50 spectrophotometer. Compared with control animals, significantly higher concentration of hepatic cadmium (9.29 vs. 1.18 micorg/g dry weight) and nickel (1.56 vs. 0.343 microg/g dry weight) were detected in the shrews collected in the mining area. However, no significant changes were observed on haematological or enzymatic parameters in animals exposed to metal pollution. The obtained results show that shrews are good bioaccumulators of toxic heavy metals, but very tolerant to their effects, revealing an interesting long-term adaptation to polluted environments. In addition, this study provides reference values for haematological parameters and antioxidant enzymes levels in C. russula, which may be relevant for comparative purposes in further studies.

Cycle Length of Spermatogenesis in Shrews (Mammalia: Soricidae) with High and Low Metabolic Rates and Different Mating Systems1

The aim of the present study was to establish and compare the durations of the seminiferous epithelium cycles of the common shrew Sorex araneus, which is characterized by a high metabolic rate and multiple paternity, and the greater white-toothed shrew Crocidura russula, which is characterized by a low metabolic rate and a monogamous mating system. Twelve S. araneus males and fifteen C. russula males were injected intraperitoneally with 5-bromodeoxyuridine, and the testes were collected. For cycle length determinations, we applied the classical method of estimation and linear regression as a new method. With regard to variance, and even with a relatively small sample size, the new method seems to be more precise. In addition, the regression method allows the inference of information for every animal tested, enabling comparisons of different factors with cycle lengths. Our results show that not only increased testis size leads to increased sperm production, but it also reduces the duration of spermatogenesis. The calculated cycle lengths were 8.35 days for S. araneus and 12.12 days for C. russula. The data obtained in the present study provide the basis for future investigations into the effects of metabolic rate and mating systems on the speed of spermatogenesis.

A Novel Set of Microsatellite Marker Loci Linkage-Mapped in the House Musk Shrew, Suncus murinus

Ten microsatellite DNA loci developed for the white-toothed shrew (Crocidura russula) were tested for PCR amplification and for utility in linkage studies in the house musk shrew, Suncus murinus. Four primer pairs successfully yielded PCR amplicons and showed polymorphism between two mutant strains, BAN-kc,oeb and WZ. Cloning and sequencing of the PCR amplicons of all the four loci confirmed the presence of microsatellite sequences. Alleles segregating in an F2 resource population constructed from the two strains ranged between two and five. Linkage analysis of the four loci together with 18 other polymorphic markers and three mutant loci resulted in five linkage groups containing three newly mapped microsatellite loci. This study reports the first microsatellite markers being registered in this species.

First evidence of the occurrence of the Pygmy white-toothed shrew, Suncus etruscus (Savi, 1822), on the island of Lipari, Aeolian archipelago (Italy)

The island of Lipari (388299 N–148569 E) is located in the Southern Tyrrhenian Sea, 30 km off of northeast Sicily and 80 km from the southwest coast of Calabria. Lipari is the main island (36.7 km2, 602 m a.s.l.) of the Aeolian Archipelago, a volcanic arc originated during the Middle Pleistocene, which also includes six other islands and several small islets. The climate is typically Mediterranean, with an annual average temperature of 18.38C and an average rainfall of 620 mm/year. At the present time, the vegetation is represented by Mediterranean maquis mainly referred to the Erico arboreae-Arbutetum unedonis Molinier, and some degraded aspects, due to the impact of previous agricultural use of the territory, which covered the ancient man-made terraces widespread on the island (Lo Cascio and Navarra 2003). Despite the fact that several scientific investigations were carried out in the Aeolian Islands even during recent years, no report has ever been obtained on the occurrence of any representatives of the Erinaceomorpha and Soricomorpha taxonomic groups, with the exception of the western hedgehog, Erinaceus europaeus L., 1758, which was introduced in the island of Alicudi around the beginning of the 1980s (cf. Cristaldi et al. 1987, Lo Cascio and Navarra 2003). In particular, the mammalian fauna up to now recorded for Lipari was only represented by Tadarida teniotis (Rafinesque-Schmaltz, 1814), Pipistrellus kuhli (Kuhl, 1819), Oryctolagus cuniculus (L., 1758), Eliomys quercinus liparensis Kahmann, 1960, Rattus rattus (L., 1758) and Mus domesticus (Schwarz and Schwarz, 1943) (cf. Kahmann 1960, Cristaldi and Federici 1980, Cristaldi 1983, Cristaldi et al. 1987, Cristaldi and Amori 1988, Zava and Lo Valvo 1991, Zava et al. 1994, Lo Cascio and Navarra 2003). The aim of this short note is to present for the first time the evidence of the occurrence of the Pygmy white-toothed shrew, Suncus etruscus (Savi, 1822) in the island, which was discovered during the present research.

Habitat associations of small mammals in farmed landscapes: implications for agri-environmental schemes

Abstract The small mammal community in 21 localities of north-western Spain was evaluated in the light of land use composition. The two geomorphologic categories characterising the study area, the main use of the land (arable/pastoral) and main crop types of each sampling locality were used as potential predictors of the relative abundance of five common small mammal species. The Common vole, Microtus arvalis showed a weak relationship with land uses, probably due to the recent colonisation process this species experienced in the study area. The relative abundance of the Algerian mouse, Mus spretus and the Lusitanian pine vole, Microtus lusitanicus was best explained by models built at the broadest regional scale, the former being more abundant in the eastern area, the latter in the western area. The Greater white-toothed shrew, Crocidura russula showed a positive relationship with grassland coverage, whilst the Wood mouse, Apodemus sylvaticus benefited from increasing proportions of fallow lands within the landscape. These two species are then expected to respond positively to those agri-environmental schemes including the increase of fallows and grassy vegetation within the arable landscape (EU recommendations). However, further efforts are needed to predict, at least qualitatively, the response of other small mammal species to the changing farmed landscape. This is especially true for two endemic species occurring at this area: the Cabrera vole, Microtus cabrerae and the Lusitanian pine vole, and for which this kind of information is almost absent.

LIFE CYCLE AND DESCRIPTION OF A NEW SPECIES OF BRACHYLAIMID (TREMATODA: DIGENEA) IN SPAIN

The life cycle of Brachylaima llobregatensis n. sp. (Trematoda: Brachylaimidae) is elucidated. Embryonated, operculated, asymmetric eggs (30.9 x 18.2 microm) are eliminated with feces of natural hosts wood mouse Mus spretus; white-toothed shrew, Crocidura russula; and an experimental host, domestic mouse, Mus musculus var. domesticus. The eggs are ingested by the helicid gastropod Helix (Cornu) aspersa, the only natural and experimental first intermediate host. The miracidium hatches from the egg, infects the snails, and develops into a branched sporocyst in the digestive gland. Microcaudate cercariae emerge from this snail and develop into unencysted metacercariae in the kidney of second intermediate host snails H. (C.) aspersa and Otala punctata (natural hosts) and Theba pisana (experimental host). Ingestion of infected snails leads to the infection of definitive hosts, with the adults inhabiting the middle part of the small intestine. There is a chaetotaxic pattern specific on the acetabular (S(II) 5-6 papillae) and body (papillae absent on P(II)) levels. Three types of cercaria papillae were observed by scanning electron microscopy: argentophilic papillae with fingerlike processes (cephalic, body, and acetabular levels); argentophilic papillae with opening (2 papillae in the M body level); and nonargentophilic dome-shaped papillae (on the cephalic C(II) level, alternating with argentophilic S(II) papillae on the ventral sucker). Suckers are subequal, with the acetabulum located in the posterior part of the anterior third of body. Vitellaria extend from anterior margin of acetabulum to between middle level and anterior margin of anterior testis.

Metal bioaccumulation in the greater white-toothed shrew, Crocidura russula, inhabiting an abandoned pyrite mine site

Hepatic and renal concentrations of iron, magnesium, zinc, lead, copper, manganese, mercury, cadmium, molybdenum, chromium, and nickel were quantified in shrews ( Crocidura russula) inhabiting a pyrite mine site in Portugal. Several morphological parameters (body weight, residual index, and relative weights) were also examined to clarify the physiological effects of pollution. Shrews from the mine showed increased bioavailability of Fe, Pb, Hg, Cd, Mo, and Ni in comparison with reference specimens. Adult shrews had the highest Cd levels while Cr and Ni concentrations diminished. Intersexual differences were found for Mo and Ni. As a consequence of metal pollution, the relative hepatic weight was higher in shrews from the mine site when compared with reference specimens. These data indicate that C. russula is a good bioindicator of metal pollution. We also evaluated the toxic effects of Pb, Hg, Cd, and Ni, because several shrews from the polluted site showed high concentrations of these metals. To approximate at the real biological impact of abandoned mines, after this first step it is necessary to associate the bioaccumulation levels and morphological effects with other physiological, ecological and genetical biomarkers.

Landscape structure affects dispersal in the greater white-toothed shrew: Inference between genetic and simulated ecological distances

Dispersal is often viewed as a process on which the landscape has little effect. This is particularly apparent in populations’ genetic and ecological studies, where isolation by distance is generally tested using a Euclidean distance between populations. However, landscapes can be richly textured mosaics of patches, associated with different qualities (e.g. different costs crossing patches) and different structures (shape, size and arrangement). An important challenge, therefore, is to determine if accounting for this additional complexity enriches our understanding of the dispersal processes. In this study, we quantify the effect of landscape structure on dispersal distances between 15 populations of the greater white-toothed shrew ( Crocidura russula) in a highly fragmented landscape in Switzerland. We use a spatially explicit individual-based model to simulate C. russula dispersal. This model is designed to account for movement behavior in heterogeneous landscapes. We explore the relationship between simulation results and genetic differentiation between actual subpopulations. Finally, we test if simulated dispersal distances are better predictors of genetic differentiation than traditional Euclidean distances. The ecological distances measured by the model show a clear relationship with genetic differentiation between C. russula subpopulations. This relationship is stronger than the one obtained by the usual Euclidean distance.

Bioaccumulation of lead, mercury, and cadmium in the greater white-toothed shrew, Crocidura russula, from the Ebro Delta (NE Spain): Sex- and age-dependent variation

We quantified bioaccumulation of lead, mercury, and cadmium in bones from 105 greater white-toothed shrews ( Crocidura russula) collected at the Ebro Delta, a polluted area, and the Medas Islands, a control site. Lead and mercury levels varied with site, age, and sex, although statistical significances depended on each factor. Globally, shrews from the polluted area exhibited significantly higher concentrations of Pb and Hg. Increment of Pb with age was particularly remarkable in wetland animals and was interpreted in relation to human activities, namely hunting. Unlike males, females from the Ebro Delta maintained low Hg levels, which were associated with gestation and lactation. Cadmium levels did not differ between sites, sexes, or ages. This study provides the first data on heavy metals in mammals from this wetland and suggests that C. russula is a good bioindicator of metal pollution. We concluded that sex and age may represent an important source of variation in the bioaccumulation of these metals in wild populations.

Disentangling Reasons for Low Y Chromosome Variation in the Greater White-Toothed Shrew (Crocidura russula)

Y chromosome variation is determined by several confounding factors including mutation rate, effective population size, demography, and selection. Disentangling these factors is essential to better understand the evolutionary properties of the Y chromosome. We analyzed genetic variation on the Y chromosome, X chromosome, and mtDNA of the greater white-toothed shrew, a species with low variance in male reproductive success and limited sex-biased dispersal, which enables us to control to some extent for life-history effects. We also compared ancestral (Moroccan) to derived (European) populations to investigate the role of demographic history in determining Y variation. Recent colonization of Europe by a small number of founders (combined with low mutation rates) is largely responsible for low diversity observed on the European Y and X chromosomes compared to mtDNA. After accounting for mutation rate, copy number, and demography, the Y chromosome still displays a deficit in variation relative to the X in both populations. This is possibly influenced by directional selection, but the slightly higher variance in male reproductive success is also likely to play a role, even though the difference is small compared to that in highly polygynous species. This study illustrates that demography and life-history effects should be scrutinized before inferring strong selective pressure as a reason for low diversity on the Y chromosome.

Shrews as Reservoir Hosts of Borna Disease Virus

Borna disease virus (BDV) is the causative agent of severe T-cell–mediated meningoencephalitis in horses, sheep, and other animal species in central Europe. Here we report the first unequivocal detection of a BDV reservoir species, the bicolored white-toothed shrew, Crocidura leucodon, in an area in Switzerland with endemic Borna disease.

Pliocene and Pleistocene diversification and multiple refugia in a Eurasian shrew ( Crocidura suaveolens group)

We sequenced 998 base pairs (bp) of mitochondrial DNA cytochrome b and 799 bp of nuclear gene BRCA1 in the Lesser white-toothed shrew ( Crocidura suaveolens group) over its geographic range from Portugal to Japan. The aims of the study were to identify the main clades within the group and respective refugia resulting from Pleistocene glaciations. Analyses revealed the Asian lesser white-toothed shrew ( C. shantungensis) as the basal clade, followed by a major branch of C. suaveolens, subdivided sensu stricto into six clades, which split-up in the Upper Pliocene and Lower Pleistocene (1.9–0.9 Myr). The largest clade, occurring over a huge range from east Europe to Mongolia, shows evidence of population expansion after a bottleneck. West European clades originated from Iberian and Italo-Balkanic refugia. In the Near East, three clades evolved in an apparent hotspot of refugia (west Turkey, south-west and south-east of the Caucasus). Most clades include specimens of different morphotypes and the validity of many taxa in the C. suaveolens group has to be re-evaluated.

Comparative fine structure of the epididymal spermatozoa from three korean shrews with considerations on their phylogenetic relationships

This study examined the fine structures of epididymal spermatozoa on the lesser white-toothed shrew (Crocidura suaveolens), the Japanese white-toothed shrew (C. dsinezumi) and the big white-toothed shrew (C. lasiura) belonging to the subfamily Crocidurinae living in Korea. In the spermatozoa of C. suaveolens, the head has a large acrosome, a smooth inner acrosomal membrane and a wavy, finger-like, electron-dense apical body. The neck has a solid proximal centriole that is filled with electron-dense material. These results showed the spermatozoa of C. suaveolens possess the characteristics of both Crocidurinae and Soricinae. In C. dsinezumi and C. lasiura, the head has a large acrosome, a serrated inner acrosomal membrane and a common apical body. The neck has a fistulous proximal centriole with slightly dense electron granules. These results showed the typical characteristics of Crocidurinae. Although C. suaveolens belongs to the subfamily Crocidurinae, the spermatozoan morphology is different from C. dsinezumi and C. lasiurai because it has conserved characteristics of the subfamily Soricinae.

Phylogeny and systematics of the Crocidura suaveolens species group: corroboration and controversy between nuclear and mitochondrial DNA markers / Phylogénie et systématique du groupe d'espèces Crocidura suaveolens: coordination et contradiction des marqueurs nucléaire et mitochondriaux de l'ADN

AbstractDespite obvious advances in systematic research on Palaearctic white-toothed shrews ( Crocidura ), phylogenetic relationships and species diagnosis of 40-chromosome species ( suaveolens sp. group) remain poorly understood. Phylogenetic relationships of these shrews were analyzed on the basis of two independent molecular markers: interspersed repeat PCR fingerprints (inter-SINE-PCR) and complete (1140 bp) or partial (∼400 bp) sequences of the mtDNA cyt b gene. According to these data, C. suaveolens from Western Europe (Italy) appeared distinct from samples of C. suaveolens from Eastern Europe and Mongolia, as well as a Siberian sample. mtDNA introgression of Eastern European C. suaveolens with C. gueldenstaedtii in their contact zone in the Tuapse region was revealed. Hybrydization between C. gueldenstaedtii and C. suaveolens resulted in the formation of a population, nuclear DNA and morphological characteristics typical for C. gueldenstaedtii , while the mitochondrial genome is assimilated from C. suaveolens . The population of the Talysh region of the Caucasus ( C. caspica ) represents a separate entity that is clearly distinguished from the populations of Georgia and Tuapse ( C. gueldenstaedtii ) and C. suaveolens . Therefore, the position of C. caspica as a full species is supported. The present analysis of both inter-SINE-PCR and cyt b sequence data revealed two major clades in Palaearctic 40-chromosome Crocidura . The eastern clade is formed by true C. suaveolens/C. sibirica , together with C. caspica , and the western clade is formed by Western European C. suaveolens , which should be treated as a distinct species, C. mimula and the closely related C. gueldenstaedtii.

Phylogeny and systematics of the Crocidura suaveolens species group: corroboration and controversy between nuclear and mitochondrial DNA markers / Phylogénie et systématique du groupe d'espèces Crocidura suaveolens: coordination et contradiction des marqueurs nucléaire et mitochondriaux de l'ADN

AbstractDespite obvious advances in systematic research on Palaearctic white-toothed shrews ( Crocidura ), phylogenetic relationships and species diagnosis of 40-chromosome species ( suaveolens sp. group) remain poorly understood. Phylogenetic relationships of these shrews were analyzed on the basis of two independent molecular markers: interspersed repeat PCR fingerprints (inter-SINE-PCR) and complete (1140 bp) or partial (∼400 bp) sequences of the mtDNA cyt b gene. According to these data, C. suaveolens from Western Europe (Italy) appeared distinct from samples of C. suaveolens from Eastern Europe and Mongolia, as well as a Siberian sample. mtDNA introgression of Eastern European C. suaveolens with C. gueldenstaedtii in their contact zone in the Tuapse region was revealed. Hybrydization between C. gueldenstaedtii and C. suaveolens resulted in the formation of a population, nuclear DNA and morphological characteristics typical for C. gueldenstaedtii , while the mitochondrial genome is assimilated from C. suaveolens . The population of the Talysh region of the Caucasus ( C. caspica ) represents a separate entity that is clearly distinguished from the populations of Georgia and Tuapse ( C. gueldenstaedtii ) and C. suaveolens . Therefore, the position of C. caspica as a full species is supported. The present analysis of both inter-SINE-PCR and cyt b sequence data revealed two major clades in Palaearctic 40-chromosome Crocidura . The eastern clade is formed by true C. suaveolens/C. sibirica , together with C. caspica , and the western clade is formed by Western European C. suaveolens , which should be treated as a distinct species, C. mimula and the closely related C. gueldenstaedtii.

Diversification of the white-toothed shrews of the genus Crocidura (Insectivora: Soricidae) in East and Southeast Asia

The genus Crocidura is one of the largest genera among mammals and widely distributed in Eurasia, Africa, and Southeast Asia. We review the recent advances in taxonomic and phylogenetic studies of this genus in East and Southeast Asia. Sympatric distributions of two or more species are known in several localities. Karyotypes of East and Southeast Asian species are divided into several groups. From karyological comparison and molecular phylogeny, those groups are suggested to have formed by geographical isolation in islands and in the continent in East and Southeast Asia. To clarify evolutionary history of East and Southeast Asian species, comprehensive studies with the West Asian and European species from karyological and molecular approaches are desired.