Sorex Granarius Research Articles

Discordant phylogenies in the Sorex araneus group (Soricidae, Mammalia): Footprints of past reticulations?

AbstractIn the present study, we reconstruct phylogenetic relationships within the chromosomally variable Sorex araneus species group based on 20 nuclear loci and the mitochondrial cyt b gene. In the species tree, Nearctic S. arcticus represents the earliest offshoot of the group followed by Holarctic S. tundrensis and Siberian S. daphaenodon. Five other species distributed mostly in Europe form a well‐supported clade. Coding regions showed stronger phylogenetic signal than introns. The results suggest a high incidence of reticulation in the evolution of the group. The authentic mitochondrial lineage of the Iberian shrew S. granarius was found to be close phylogenetically to S. coronatus, which confirms that some populations of the Iberian shrew S. granarius were introgressed from S. araneus. Footprints of deeper reticulations are revealed for the first time, indicating the potential hybrid origin of the S. arcticus and S. coronatus lineages. Ancient hybridisations are hypothesised to be the source of discordance between molecular‐ and karyotype‐based phylogenetic reconstructions.

Characterising Mitochondrial Capture in an Iberian Shrew.

Mitochondrial introgression raises questions of biogeography and of the extent of reproductive isolation and natural selection. Previous phylogenetic work on the Sorex araneus complex revealed apparent mitonuclear discordance in Iberian shrews, indicating past hybridisation of Sorex granarius and the Carlit chromosomal race of S. araneus, enabling introgression of the S. araneus mitochondrial genome into S. granarius. To further study this, we genetically typed 61 Sorex araneus/coronatus/granarius from localities in Portugal, Spain, France, and Andorra at mitochondrial, autosomal, and sex-linked loci and combined our data with the previously published sequences. Our data are consistent with earlier data indicating that S. coronatus and S. granarius are the most closely related of the three species, confirming that S. granarius from the Central System mountain range in Spain captured the mitochondrial genome from a population of S. araneus. This mitochondrial capture event can be explained by invoking a biogeographical scenario whereby S. araneus was in contact with S. granarius during the Younger Dryas in central Iberia, despite the two species currently having disjunct distributions. We discuss whether selection favoured S. granarius with an introgressed mitochondrial genome. Our data also suggest recent hybridisation and introgression between S. coronatus and S. granarius, as well as between S. araneus and S. coronatus.

Biometría mandibular y dentaria de las musarañas del género Sorex Linnaeus, 1758 en la región central y occidental de los Pirineos

We have measured 98 mandibles and 717 teeth of shrews of Sorex (Soricidae, Eulipotyphla) of the Aragonian, Navarre and Vasc Pyrenees. The material comes from owl pellets recovered between 1967 and 1969 and takes part of the collection of the Instituto Pirenaico de Ecología (IPE-CSIC). The material has been reclassified using osseous criteria, biometrics and discriminant functions, obtaining that these species are Sorex coronatus and Sorex minutus. The study of S. coronatus is interesting because it is similar to S. araneus and Sorex granarius so it is easy to confuse them if we only have bones and teeth. For this reason, people usually group them as Sorex sp. As consequence, the information about them in the Iberian Peninsula is scarce, and especially in Aragón. The analyses of the measurements show that there is a difference among the occidental populations and the oriental zones of the area studied. In general, values decrease to the west; they are larger in the zones with a Mediterranean influence than in the Atlantic ones. The most useful measurements to compare them are the measurements of mandibles. On the other hand, the measurements of teeth allow the comparison with bibliographic data of palaeontological material that consists mainly of incomplete mandibles.

Replication timing of large Sorex granarius (Soricidae, Eulipotyphla) telomeres.

Previously, we described the unique feature of telomeric regions in Iberian shrew Sorex granarius: its telomeres have two ranges of size, very small (3.8kb of telomeric repeats on average) and very large discontinuous telomeres (213kb) interrupted with 18S rDNA. In this study, we have demonstrated extraordinary replication pattern of S. granarius large telomeres that have not been shown before in other studied mammal. Using the ReD-FISH procedure, we observed prolonged, through S period, large telomere replication. Furthermore, revealed ReD-FISH asymmetric signals were probably caused by partial replication of telomeres within an hour of 5-bromodeoxyuridine treatment due to the large size and special organization. We also found that in contrast to the telomeric halo from primary fibroblasts of bovine, mink, and common shrew, telomere halo of S. granarius consists of multiple loops bundled together, some of which contain rDNA. Here, we suggested several replicons firing possibly stochastic in each large telomere. Finally, we performed the TIF assay to reveal DNA damage responses at the telomeres, and along with TIF in nuclei, we found large bodies of telomeric DNA and ɤ-H2AX in the cytoplasm and on the surface of fibroblasts. We discuss the possibility of additional origin activation together with recombination-dependent replication pathways, mainly homologous recombination including BIR for replication fork stagnation overcoming and further S. granarius large telomere replication.

Chromosome Evolution in Eulipotyphla

We integrated chromosome painting information on 5 core-insectivora species available in the literature with new Zoo-FISH data for Iberian shrew (Sorex granarius) and Altai mole (Talpa altaica). Our analysis of these 7 species allowed us to determine the chromosomal features of Eulipotyphla genomes and to update the previously proposed ancestral karyotype for 2 main groups of the Sorex genus. The chromosome painting evidence with human painting probes (HSA) reveals the presence of the 2 unique associations HSA4/5 and 1/10p/12/22b, which support Eulipotyphla. There are a series of synapomorphies both for Erinaceidae (HSA3/1/5, 3/17, 11/15 and 10/20) and for Soricinae (HSA5/9, 6/7/16, 8/3/21 and 11/12/22). We found associations that link Talpidae/Erinaceidae (HSA7/8, 1/5 and 1/19p), Talpidae/Soricidae (HSA1/8/4) and Erinaceidae/Soricidae (HSA4/20 and 2/13). Genome conservation in Eulipotyphla was estimated on the basis of the number of evolutionary breaks in the ancestral mammalian chromosomes. In total, 7 chromosomes of the boreo-eutherian ancestor (BEA8 or 10, 9, 17, 18, 20–22) were retained in all eulipotyphlans studied; among them moles show the highest level of chromosome conservation. The integration of sequence data into the chromosome painting information allowed us to further examine the chromosomal syntenies within a phylogenetic perspective. Based on our analysis we offer the most parsimonious reconstruction of phylogenetic relationships in Eulipotyphla. The cytogenetic reconstructions based on these data do not conflict with molecular phylogenies supporting basal position of Talpidae in the order.

Additional data for nuclear DNA give new insights into the phylogenetic position of Sorex granarius within the Sorex araneus group

Many species contain genetic lineages that are phylogenetically intermixed with those of other species. In the Sorex araneus group, previous results based on mtDNA and Y chromosome sequence data showed an incongruent position of Sorex granarius within this group. In this study, we explored the relationship between species within the S. araneus group, aiming to resolve the particular position of S. granarius. In this context, we sequenced a total of 2447 base pairs (bp) of X-linked and nuclear genes from 47 individuals of the S. araneus group. The same taxa were also analyzed within a Bayesian framework with nine autosomal microsatellites. These analyses revealed that all markers apart from mtDNA showed similar patterns, suggesting that the problematic position of S. granarius is best explained by an incongruent behavior by mtDNA. Given their close phylogenetic relationship and their close geographic distribution, the most likely explanation for this pattern is past mtDNA introgression from S. araneus race Carlit to S. granarius.

The structure of long telomeres in chromosomes of the Iberian shrew

It is shown that the size, localization, and structure of telomeres in the Iberian shrew (Sorex granarius) are not characteristic of mammals. In this species, long telomeres of an average size of 213 kb are localized on the short arms of all 32 acrocentrics; ribosomal blocks and active nucleolus-organizing regions (NORs) were also discovered there. At the remaining chromosome ends the average size of telomeres is 3.8 kb. However, in a closely related species, Sorex araneus, all telomeres have size similar to that of human telomeres, i.e., 6.8-15.2 kb. Despite the fact that some long telomeres contain ribosomal repeats in addition to telomeric ones, the long telomeres have preserved asymmetry of G- and C-rich strands as in functional telomeres. It is probable that long telomeres were formed in meiosis at the stage of chromosome bouquet as a result of global reorganization of the chromosome ends. The provoking factors for such reorganization might be the fission of several metacentrics and the necessity of telomerization of the resulting acrocentrics.

Telomeric DNA allocation in chromosomes of common shrew (Sorex araneus, eulipotyphla)

Recently we have displayed shrew species, Iberian shrew S. granarius, with telomeres of unusual for mammals structure, including long telomeres on the short acrocentrics arms containing 213 kb on average and short telomeres (3.8 kb) on the other chromosomal ends (Zhdanova et al., 2005, 2007). However, it is not clear if such telomeres are characteristic of all shrew species or only of S. granarius. S. granarius and common shrew Sorex araneus are the sibling species. In this investigation by using modified Q-FISH, we demonstrated that telomeres in S. araneus from different chromosomal races differing in the numbers of metacentrics contain 6.8-15.2 kb of telomeric tracts. Thus, the S. araneus telomere lengths appeared to correspond with telomere lengths both in shrews and majority wild mammalian species, and S. granarius has telomeres with unique or scarce structure. Furthermore, using DNA and RNA modified with probe high specificity to telomeric repeats (PNA and LNA) we showed that interstitial telomeric sites in S. araneus chromosomes contained mainly telomeric DNA and their localization coincided with some evolutionary breakpoints. Interstitial telomeric DNA in S. granarius chromosomes was not revealed. Thus, distribution of telomeric DNA can greatly differ even in closely related species whose chromosomes are composed from almost identical chromosomal arms.

Three-dimensional organization of interphase fibroblast nuclei in two closely related shrew species (Sorex granarius and Sorex araneus) differing in the structures of their chromosome termini

A FISH with a probe for telomeric and rDNA repeats and immunofluorescence with ANA CREST and antibodies to nucleolae protein B23 were used to study the three-dimensional (3D) organization of fibroblast interphase nuclei in two shrew twin species, Sorex granarius and Sorex araneus, of the Cordon race. Karyotypes of these species are composed of nearly identical chromosomal arms and differ in the number of their metacentrics and the structures of their terminal chromosome regions. In the short arms of S. granarius, 32 of the acrocentrics have large telomeres that contain an average of 218 kb telomere repeats, which alternate with ribosomal repeats. These regions also contain active nucleolar organizing regions (NORs). In contrast, in active NORs in S. araneus are localized at the terminal regions of 8 chromosomal arms (Zhdanova et al., 2005; 2007b). Here, we show that associations of chromosomes by telomeres and the contact of a part of the telomere clusters with the inner nuclear membrane and nucleolus characterize the interphase nuclei of both Sorex granarius and Sorex araneus. We also reveal the partial colocalization of telomere and ribosomal clusters and the spatial proximity of centomeric and telomeric regions in the interphase nuclei of S. granarius. It appears that only ribosomal clusters containing a sufficient number of active ribosomal genes exhibit a connection with the nucleolus. Nucleolus disassembly during the fibroblastis transition to mitosis and the role of the B23 protein in this process have been studied.

Heavy Metal Transfers Between Trophic Compartments in Different Ecosystems in Galicia (Northwest Spain): Essential Elements

In the present study, we determined the concentrations of Cu, Fe, Mn, and Zn in soil and several trophic compartments at a total of 16 sampling stations. The trophic compartments studied were primary producers, represented by two species of terrestrial mosses (Pseudoescleropodium purum and Hypnum cupressiforme) and oak trees (Quercus robur or Q. pyrenaica); primary consumers, represented by the wood mouse (Apodemus sylvaticus) and the yellow necked mouse (A. flavicollis); secondary consumers, represented by the shrew (Sorex granarius); and finally, detritivores, represented by slugs (Arion ater). Thirteen of the sampling stations were located in mature oak woodlands (Quercus sp.); two of the sampling stations were located in the area surrounding a restored lignite mine dump, and the other in an ultrabasic area. The analytical determinations revealed a lack of significant correlations among trophic compartments, possibly caused by effective regulation of metals by organisms and/or spatial variation in availability of metals from soil or food. Furthermore, the only element that showed a clear pattern of biomagnification was Cu; as for the other elements, there was always some divergence from such a pattern. Finally, the patterns of bioaccumulation in contaminated and woodland sampling stations were very similar, although there was enrichment of the concentrations of Cu, Mn, and Zn in the mice viscera, which, except for Mn, were related to higher edaphic concentrations.

Evaluation of some sources of variability in using small mammals as pollution biomonitors

In the present study the effects of gender, age and nutritional status on tissue concentrations of some trace elements (Zn, Cu, Mn, and Cr) in wood mouse (Apodemus sylvaticus), Spanish shrew (Sorex granarius), and great white-toothed shrew (Crocidura russula) were investigated. Four sampling stations were selected for the study: a restored mine dump, an area characterised by ultrabasic soil and two sites in oak woods in the vicinity of a power plant. Gender had no effect on the tissue concentrations of the metals studied, except for the concentration of Zn in brain tissue from C. russula. The relative age of the individuals was estimated on the basis of crystalline lens weight in mice and dental abrasion in shrews, as body weight was considered a poor indicator of age because of the strong interindividual overlap in the populations. Age was only significantly (and negatively) correlated with the concentration of Cr in livers of mice from one station, a finding that may indicate physiological stress on growth at this site. The nutritional status was estimated from the body mass index; the relationships between this index and metal concentrations for both A. sylvaticus and C. russula were negative, which can be attributed to the weight-specific metabolic rate that leads to a relatively low uptake of metals per unit of body weight. As there was no relation between duration of exposure and concentrations of metals in the organs analysed, age should not be included as a variable factor in the condition index.

Mastofauna del Bosque Nacional de Buçaco, centro de Portugal.

The Buçaco National Forest (a walled area of approximately 105 hectares) is a natural, historical and architectural heritage unique in Portugal and the world. Biologically, it represents one of the best dendrological collections in Europe, and associated with this floristic richness is a little-known fauna. The only faunal study of this site was carried out approximately 100 years ago, consisting of a survey and inventory of the animals present at that time. In this study, we made an inventory and determined the distribution of mammal species (except chiroptera) in the forest using various methods, such as: direct observations, collecting and identifying signs of their presence and corpses, carrying out nocturnal surveys, capturing carnivores and micromammals with box traps and camera traps, and analysing the regurgitations of nocturnal prey. The occurrence of 20 mammal species was confirmed (Insectivora: 4, Rodentia: 8, Carnivora: 7, Artyodactila:1), for which a distribution map was drawn up in the forest. The absence of lagomorphs in the forest is noteworthy, especially the wild rabbit (Oryctolagus cuniculus), a species found throughout continental Portugal, possibly due to the dense and closed vegetation cover of the forest. The occurrence of protected species such as the red-toothed shrew (Sorex granarius) and the otter (Lutra lutra), among others, reinforces the importance of this area in the context of the conservation of the country's mastofauna. Knowing and publicising the biodiversity present in the Buçaco National Forest could help raise awareness among visitors to this area about protecting the natural balance and the ecosystems present, given that it is visited by more than 100,000 people every year.

The distributions of telomeric and ribosomal DNA on the chromosomes of two closely related species, Sorex araneus and Sorex granarius (Soricidae, Eulipotyphla)

The distributions of telomeric and ribosomal DNA on the chromosomes of two closely related species, Sorex araneus and Sorex granarius (Soricidae, Eulipotyphla)

The very long telomeres in Sorex granarius (Soricidae, Eulipothyphla) contain ribosomal DNA

Two closely related shrew species, Sorex granarius and Sorex araneus, in which Robertsonian rearrangements have played a primary role in karyotype evolution, present very distinct telomere length patterns. S. granarius displays hyperlong telomeres specifically associated with the short arms of acrocentrics, whereas telomere lengths in S. araneus are rather short and homogenous. Using a combined approach of chromosome and fibre FISH, modified Q-FISH, 3D-FISH, Ag-NOR staining and TRF analysis, we carried out a comparative analysis of telomeric repeats and rDNA distribution on chromosome ends of Sorex granarius. Our results show that rDNA sequences forming active nuclear organizing regions are interspersed with the long telomere tracts of all short arms of acrocentrics. These observations suggest that the major rearrangements that gave rise to today's karyotype in S. granarius were accompanied by a profound reorganization of chromosome ends, which comprised extensive amplification of telomeric and rDNA repeats on the short arms of acrocentrics and finally contributed to the stabilization of telomeres. This is the first time that such telomeric structures have been observed in any mammalian species.

Unusual distribution pattern of telomeric repeats in the shrews Sorex araneus and Sorex granarius

Sorex araneus and Sorex granarius are sibling species within the Sorex araneus group with karyotypes composed of almost identical chromosome arms. S. granarius has a largely acrocentric karyotype, while, in S. araneus, various of these acrocentrics have combined together by Robertsonian (Rb) fusions to form metacentrics, with the numbers and types of metacentrics differing between chromosomal races. Our studies on telomeric sequences in S. araneus and S. granarius revealed differences between chromosomes and between species. In S. araneus (the Novosibirsk race), hybridization signals were present on the telomeres of all the chromosomes after FISH with a PCR-generated telomeric probe. In addition, hybridization signals were observed at high frequencies in the pericentric regions of some but not all metacentrics formed by Rb fusion. There were fewer signals on those metacentrics formed earlier in the evolution of S. araneus. This suggests that S. araneus chromosomes retain at least some telomeric repeats during Rb fusion, but that these repeats are lost or modified over time. These results are critical for the interpretation of the well-studied hybrid zones between chromosomal races of S. araneus, given that Rb fission has been postulated in such hybrid zones and that the likelihood of Rb fission will relate to presence/absence of telomeric sequences at the centromeres of metacentrics. In S. granarius, there were strong signals at the proximal (centromeric) telomeres of the acrocentrics after FISH with a DNA telomeric probe. FISH with a PNA telomeric probe on S. granarius acrocentrics showed that the proximal telomeres were 213 kb on average, while the length of the distal telomeres was 3.8 kb on average. Two-colour FISH, using a telomeric DNA probe and a microdissected probe generated from the pericentric regions of the S. granarius chromosomes a and b, revealed regions on distinct chromatin fibres where telomeric and microdissected probes were colocalized or localized sequentially. The proximal telomeres of S. granarius are highly unusual both in their large size and their heterogeneous structure relative to the telomeres of other mammals.

647 Applications of eucaryotic microorganisms in comet assay for in vitro genotoxicity evaluation of environmental samples

In the present study the effects of gender, age and nutritional status on tissue concentrations of some trace elements (Zn, Cu, Mn, and Cr) in wood mouse (Apodemus sylvaticus), Spanish shrew (Sorex granarius), and great white-toothed shrew (Crocidura russula) were investigated. Four sampling stations were selected for the study: a restored mine dump, an area characterised by ultrabasic soil and two sites in oak woods in the vicinity of a power plant. Gender had no effect on the tissue concentrations of the metals studied, except for the concentration of Zn in brain tissue from C. russula. The relative age of the individuals was estimated on the basis of crystalline lens weight in mice and dental abrasion in shrews, as body weight was considered a poor indicator of age because of the strong interindividual overlap in the populations. Age was only significantly (and negatively) correlated with the concentration of Cr in livers of mice from one station, a finding that may indicate physiological stress on growth at this site. The nutritional status was estimated from the body mass index; the relationships between this index and metal concentrations for both A. sylvaticus and C. russula were negative, which can be attributed to the weight-specific metabolic rate that leads to a relatively low uptake of metals per unit of body weight. As there was no relation between duration of exposure and concentrations of metals in the organs analysed, age should not be included as a variable factor in the condition index.

Zoo-FISH with region-specific paints for mink chromosome 5q: delineation of inter- and intrachromosomal rearrangements in human, pig, and fox

Comparison of evolutionarily conserved mammalian chromosomes homologous to human chromosome 17, performed with microdissected painting probes, revealed rearrangements inside these chromosomes in mink and pig and a disruption of this conserved region in the fox. Detection of a homologous region on an Iberian shrew chromosome showed the efficiency of microdissected painting probes for delineation of homologous chromosome regions in species belonging to orders that diverged at least 100 million years ago.

CHROMOSOMAL VERSUS MITOCHONDRIAL DNA EVOLUTION: TRACKING THE EVOLUTIONARY HISTORY OF THE SOUTHWESTERN EUROPEAN POPULATIONS OF THE SOREX ARANEUS GROUP (MAMMALIA, INSECTIVORA).

The shrews of the Sorex araneus group have undergone a spectacular chromosome evolution. The karyotype of Sorex granarius is generally considered ancestral to those of Sorex coronatus and S. araneus. However, a sequence of 777 base pairs of the cytochrome b gene of the mitochondrial DNA (mtDNA) produces a quite different picture: S. granarius is closely related to the populations of S. araneus from the Pyrenees and from the northwestern Alps, whereas S. coronatus and S. araneus from Italy and the southern Alps represent two well-separated lineages. It is suggested that mtDNA and chromosomal evolution are in this case largely independant processes. Whereas mtDNA haplotypes are closely linked to the geographical history of the populations, chromosomal mutations were probably transmitted from one population to another. Available data suggest that the impressive chromosome polymorphism of this group is quite a recent phenomenon.

The chromosome complement of Sorex granarius--the ancestral karyotype of the common shrew (Sorex araneus)?

We present the G-band karyotype of Sorex granarius (Miller, 1910). With minor exceptions, each of the acrocentric autosomes in this karyotype is completely homologous to one of the chromosome arms in the karyotype of the common shrew (Sorex araneus L., 1758). If, as is the simplest interpretation, the karyotypic evolution in S. araneus is by repeated Robertsonian fusion, the karyotype in S. granarius represents the ancestral condition. We urge breeding studies to establish whether the designation of S. granarius as a full species is justified.