Coccidian parasites (Apicomplexa: Eimeriidae) from insectivores. III. Seven new species in shrews (Soricidae: Soricinae) from Canada, Japan, and the United States

Since May 1979, 458 shrews (Blarina sp. and Sorex spp.) representing 20 species collected in Canada, Japan, and the United States were examined for coccidia; 110 (24%) had oocysts in their feces, including 8 of 21 (38%) B. brevicauda from Massachusetts, Ohio, Pennsylvania, and Vermont; 2 of 7 (29%) S. caecutiens from Hokkaido and Honshu; 14 of 63 (22%) S. cinereus from Colorado, New Mexico, Pennsylvania, Vermont, Manitoba, and Ontario; 3 of 7 (43%) S. fontinalis from Pennsylvania; 11 of 16 (69%) S. fumeus from Massachusetts, Minnesota, Pennsylvania, Vermont, and Ontario; 1 of 4 (25%) S. haydeni from Minnesota; 6 of 8 (75%) S. longirostris from Florida and Virginia; 1 of 2 (50%) S. ornatus from California; 5 of 12 (42%) S. pacificus from California and Oregon; 13 of 41 (32%) S. palustris from California, Colorado, and New Mexico; 1 of 2 (50%) S. tenellus from California; 11 of 105 (10%) S. trowbridgii from California, Oregon, and Washington; 10 of 48 (21%) S. unguiculatus from Hokkaido; and 24 of 112 (21%) S. vagrans from Arizona, California, Colorado, New Mexico, Oregon, and Washington. The following coccidians were identified from infected shrews: Eimeria brevicauda n. sp. from B. brevicauda; Eimeria fumeus n. sp. from S. fumeus, S. pacificus, S. unguiculatus, and S. vagrans; Eimeria inyoni n. sp. from S. tenellus; Eimeria palustris n. sp. from S. cinereus, S. fontinalis, S. fumeus, S. haydeni, S. longirostris, S. ornatus, S. pacificus, S. palustris, S. tenellus, S. trowbridgii, and S. vagrans; Eimeria vagrantis n. sp. from S. fumeus, S. trowbridgii, and S. vagrans; Isospora brevicauda n. sp. from B. brevicauda; and Isospora palustris n. sp. from S. pacificus, S. palustris, S. trowbridgii, S. unguiculatus, and S. vagrans. The world literature on coccidian parasites of shrews (16 eimerians and 3 isosporans exclusive of the 7 new species described here) is reviewed.     

Olfactory mucosa ultrastructure in the short-tailed shrews,Blarina brevicauda and Blarina carolinensis

The olfactory mucosae of the northern short-tailed shrew, Blarina brevicauda, and the southern short-tailed shrew, Blarina carolinensis, were examined by light and electron microscopy. A well-developed olfactory epithelium was observed that included all of the cells necessary to provide for a sensitive olfactory system, suggesting that olfaction plays a major role in the behavior of these animals. There were no significant differences between the olfactory mucosae of these two species. The general features of the olfactory epithelium in these shrews were similar to those reported for several other macrosmatic mammals. A new type of supporting cell, called the light supporting cell, was observed in these shrews. The light supporting cell cytoplasm exhibited very little staining by light microscopy and had low electron density by transmission electron microscopy compared to that of the more common dark supporting cell. The light supporting cell had a convex apical surface with microvilli and lacked the large amounts of smooth endoplasmic reticulum (SER) typical of the apical cytoplasm of the dark supporting cell. In the lamina propria of the mucosa, the Bowman's glands consisted of two cell types, one with electron-lucent, alcian blue-positive granules, and the other with electron-dense PAS-positive granules. The cell with electron-lucent granules contained large amounts of SER and small clumps of rough ER. The cells with electron-dense granules had large amounts of RER and little SER.     

Prevalence of Bordetella bronchiseptica in certain central Iowa

Bordetella bronchiseptica was isolated from 6 of 13 short-tailed shrews (Blarina brevicauda) and 1 of 47 house sparrows (Passer domesticus) trapped in the vicinity of a swine Bordetella rhinitis experimental area. The organism was found in four of 50 foxes (Vulpes fulva), 2 of 36 opossums (Didelphis marsupialis) and 1 of 37 raccoons (Procyon lotor) trapped in the Ames, Iowa area. This bacterium was not culturally isolated from 14 deer mice (Peromyscus maniculatus), 64 house mice (Mus Musculus), 10 masked shrews (Sorex cinereus) and 54 starlings (Sturnus vulgaris).     

Molecular phylogeny of short-tailed shrews, Blarina (Insectivora: Soricidae)

Phylogenetic relationships among the three described species of short-tailed shrews (genus Blarina) were inferred based on mitochondrial DNA sequences of 16S rRNA (506 bp) and cytochrome b (1137 bp) from 38 specimens representing B. brevicauda, B. hylophaga, and B. carolinensis, from across their range in North America. Phylogenetic analyses of both data sets combined followed tests showing lack of incongruence between these fragments. Analysis of substitution patterns indicated saturation of transitions at third codon positions in cytochrome b when Blarina sequences were compared to those of Sorex and Cryptotis, used as outgroups. Maximum-likelihood and weighted parsimony supported the monophyly of the genus and placed B. hylophaga as its basal branch, sister to B. brevicauda + B. carolinensis. Phylogeographic analysis revealed a significant partition between eastern and western populations of B. carolinensis and B. brevicauda, on either side of the Mississippi basin. These results are discussed in relation to cytogenetic, morphological, and fossil data.     

Isolation of the Lyme disease spirochete from mammals in Minnesota

Lyme disease spirochetes were isolated from the kidneys of two Peromyscus spp. trapped in Minnesota in September and October 1983. No spirochetes were isolated from white-tailed deer (Odocoileus virginianus), red backed voles (Clethrionomys gapperi), or shrews (Sorexy cinereus and Blarina brevicauda). This is the first report of the isolation of the Lyme disease spirochete from the midwestern United States and isolations from these animals, which were free of ticks, suggest that the Lyme disease spirochete may persist in animal organs for months.     

Evidence for gene flow in parasitic nematodes between two host species of shrews

We describe the genetic structure of populations of the intestinal nematode Longistriata caudabullata (Trichostrongyloidea: Heligmosomidae), a common parasite of short-tailed shrews (genus Blarina, Insectivora: Soricidae). Parasites and hosts were collected from a transect across a contact zone between two species of hosts, Blarina brevicauda and B. hylophaga, in central North America. An 800-base pairs (bp) fragment of the ND4 mitochondrial DNA (mtDNA) gene was sequenced for 28 worms and a 783-bp fragment of the mtDNA control region was analysed for 16 shrews. Phylogenetic analyses of mtDNA sequences revealed reciprocal monophyly for the shrew species, concordant with morphological diagnosis, and supported the idea that the transect cuts through a secondary contact zone between well-differentiated B. brevicauda and B. hylophaga. In contrast to this pattern, the parasitic nematode mtDNA phylogeny was not subdivided according to host affiliation. Genealogical discordance between parasite and host phylogenies suggests extensive gene flow among parasites across the host species boundary.     

Phylogeny and evolution of African shrews (Mammalia: Soricidae) inferred from 16s rRNA sequences

Current phylogenetic hypotheses on the African Crocidurinae (Soricidae) are based upon morpho-anatomical, karyological, and allozyme studies. The present study attempts to resolve the interrelationships among African Crocidurinae and their relationships to Eurasian Crocidurinae and to the subfamily Soricinae, on the basis of partial mitochondrial 16s rRNA sequences (549 bp). This is the first molecular study to include all but one of the nine currently recognized African shrew genera. In agreement with current views, two major lineages emerge. The first lineage includes Myosorex and Congosorex and supports the existence of a myosoricine taxon. The second lineage includes the six remaining genera. The genus Sylvisorex appears to be polyphyletic, whereas species of the controversial genus Crocidura are monophyletic. The genus Suncus presumably originated in Africa. The monospecific genera Ruwenzorisorex and Scutisorex and the two representatives of Paracrocidura cluster with species of other genera. Grouping patterns of species from different continents suggest that there have been multiple exchanges between Africa and Eurasia. The time estimates of these exchanges, inferred from two independent fossil-based calibrations of a molecular clock, coincide with the time estimates for migration events in other mammalian taxa.     

Phylogeography of the Northern short-tailed shrew,Blarina brevicauda (Insectivora: Soricidae): past fragmentation and postglacial recolonization

Blarina brevicauda is distributed across the northeastern region of North America, in areas previously covered by Pleistocene glaciers. Previous molecular systematic study of the species in the genus Blarina suggested the presence of two distinct eastern and western phylogroups within B. brevicauda, in agreement with traditionally recognized semi-species. To expand the previous work, a collection of 76 individuals from 14 localities collected throughout the range of B. brevicauda was used to assess the mitochondrial (mt) cytochrome b genealogy for this species. Minimum evolution, maximum parsimony, analysis of molecular variance and nested clade analysis each supported the same conclusions of two well-differentiated and monophyletic east-west groups, separated by the Mississippi River. Denser sampling in areas immediately East of the Mississippi basin revealed further subdivision within the eastern phylogroup into an East-Central and an Appalachian clade. The western phylogroup differed from the eastern phylogroup by 2.5% mean absolute DNA sequence difference. About 65% of the genetic variance among samples was explained by the east-west subdivision alone. High haplotype diversities, low nucleotide diversities and unimodal mismatch distributions within subclades suggest recent expansion or diversification within each group. No phylogeographic structure was found within the western phylogroup, but genetic structure because of restricted gene flow and isolation by distance was inferred for the eastern group. The present distribution of B. brevicauda is best explained by past fragmentation and range expansion events during and following the Pleistocene glacial cycles.     

Molecular phylogenetics of soricid shrews (Mammalia) based on mitochondrial cytochrome b gene sequences: with special reference to the Soricinae

Molecular phylogeny of soricid shrews (Soricidae, Eulipotyphla, Mammalia) based on 1140 bp mitochondrial cytochrome b gene (cyt b ) sequences was inferred by the maximum likelihood (ML) method. All 13 genera of extant Soricinae and two genera of Crocidurinae were included in the analyses. Anourosorex was phylogenetically distant from the main groupings within Soricinae and Crocidurinae in the ML tree. Thus, it could not be determined to which subfamily Anourosorex should be assigned: Soricinae, Crocidurinae or a new subfamily. Soricinae (excluding Anourosorex ) should be divided into four tribes: Neomyini, Notiosoricini, Soricini and Blarinini. However, monophyly of Blarinini was not robust in the present data set. Also, branching orders among tribes of Soricinae and those among genera of Neomyini could not be determined because of insufficient phylogenetic information of the cyt b sequences. For water shrews of Neomyini ( Chimarrogale , Nectogale and Neomys ), monophyly of Neomys and the Chimarrogale – Nectogale group could not be verified, which implies the possibility of multiple origins for the semi-aquatic mode of living among taxa within Neomyini. Episoriculus may contain several separate genera. Blarinella was included in Blarinini not Soricini, based on the cyt b sequences, but the confidence level was rather low; hence more phylogenetic information is needed to determine its phylogenetic position. Furthermore, some specific problems of taxonomy of soricid shrews were clarified, for example phylogeny of local populations of Notiosorex crawfordi , Chimarrogale himalayica and Crocidura attenuata .     

Muscle capillary supply in hind limb and diaphragm of the common shrew (Sorex araneus)

Shrew species of the subfamily Soricinae have unusually high metabolic rates when compared to Crocidurinae shrews and other similar-sized mammals. The aim of this study was to clarify whether the high basal metabolic rate of Soricinae shrews is reflected in a high capillary density in their muscles. To this end, the capillary supply of four limb muscles and diaphragm of the common shrew (Sorex araneus) was quantified from cross-sectioned muscles. The capillary densities of the limb muscles were 2575 ± 329, 3111 ± 299, 2812 ± 197 and 2752 ± 173 capillaries mm⁻² fibre area in gastrocnemius lateralis, g. medialis, plantaris and soleus, respectively. Capillary density of the shrew diaphragm (6691 ± 1057) was double that of the limb muscles. This value is among the highest ever measured in mammals. In general, the capillary supply in the hind limb of the common shrew is about 3–4 times higher than commonly found in the leg muscles of the laboratory rat or other bigger mammals, but similar to those in Crocidurinae shrews and some small rodents. Thus the high resting metabolism of the common shrew is not associated with an extraordinarily high capillary density. The apparent disparity between basal metabolic rate and muscle capillary supply in S. araneus is probably due to the small aerobic scope of shrews in the subfamily Soricinae. Accepted: 22 January 1998     

Response to enrichment, type and timing: small mammals vary in their response to a springtime cicada but not a carbohydrate pulse

1. Masting events in the autumn provide a carbohydrate-rich pulse of resources that can influence the dynamics of small mammals and their natural enemies. Similar patterns are observed with the periodical cicada emergence which provides a protein-rich pulse in the spring, but comparisons are confounded by timing and food type. 2. We compared the influence of a naturally occurring spring pulse of cicadas with an experimental spring pulse of carbohydrate-rich seeds. We used a replicated population level field experiment and capture-mark-recapture techniques to record the vital rates, demographics, and abundance of Peromyscus leucopus (the white-footed mouse), as well as other small mammals and their parasites. 3. The density of P. leucopus on grids where cicadas emerged was 55% higher than controls as a consequence of early breeding. This was followed by an increase in the prevalence of the nematode Pterygodermatities peromysci, reduced breeding and decreased recruitment rates. Other small mammals including Tamias striatus (eastern chipmunk) and Blarina brevicauda (short-tailed shrew), increased in density, but there was no affect on Sorex cinereus (masked shrew). 4. In contrast to the presence of cicadas, there was no influence of sunflower seed supplementation on small mammal density, vital rates, or reproduction with the exception of an increase in B. brevicauda density. The response of small mammals to seasonal pulses depends on timing, food type, and species.     

Purification and characterisation of blarinasin, a new tissue kallikrein-like protease from the short-tailed shrew Blarina brevicauda: comparative studies with blarina toxin

A new tissue kallikrein-like protease, blarinasin, has been purified from the salivary glands of the short-tailed shrew Blarina brevicauda. Blarinasin is a 32-kDa N-glycosylated protease with isoelectric values ranging between 5.3 and 5.7, and an optimum pH of 8.5 for enzyme activity. The cloned blarinasin cDNA coded for a pre-pro-sequence and a mature peptide of 252 amino acids with a catalytic triad typical for serine proteases and 43.7-54.0% identity to other mammalian tissue kallikreins. Blarinasin preferentially hydrolysed Pro-Phe-Arg-4-methylcoumaryl-7-amide (MCA) and N-tert-butyloxycarbonyl-Val-Leu-Lys-MCA, and preferentially converted human high-molecular-weight kininogen (HK) to bradykinin. The activity of blarinasin was prominently inhibited by aprotinin (K(i) =3.4 nM). A similar kallikrein-like protease, the lethal venom blarina toxin, has previously been purified from the salivary glands of the shrew Blarina and shows 67.9% identity to blarinasin. However, blarinasin was not toxic in mice. Blarinasin is a very abundant kallikrein-like protease and represents 70-75% of kallikrein-like enzymes in the salivary gland of B. brevicauda.     

Bioenergetics of cross-ice movements by Microtus pennsylvanicus, Peromyscus leucopus and Blarina brevicauda

Laboratory and field experiments were conducted to investigate bioenergetics of winter dispersal and to compare winter (cross-ice) dispersal abilities of three small mammals: Microtus pennsylvanicus, Peromyscus leucopus and Blarina brevicauda . Total metabolic rates increased with running activity and decreased as ambient temperatures increased for all species. Thermal conductance was significantly higher for running than for resting Microtus and Peromyscus , but decreased significantly with activity for Blarina .
Winter dispersal abilities, calculated from treadmill experiments, increased with ambient temperature and with body size of the species. The superior dispersal ability of Microtus in comparison with Peromyscus results from the former's ability to utilize more energy reserves during running. The comparatively low winter dispersal ability of Blarina , which was less than a third of the two rodent species, resulted from its high weight specific cost of transport at winter temperatures and its relatively low energy stores and/or energy utilization during running.     

Ten polymorphic microsatellite loci for the endangered Buena Vista Lake shrew (Sorex ornatus relictus)

The ornate shrew (Sorex ornatus) is restricted to the vanishing wetlands of California, USA and Baja California, Mexico. Several subspecies of ornate shrews are considered ‘mammal species of special concern’ in California by the Department of Fish and Game, and one (Sorex ornatus relictus) has recently been listed as endangered. Populations of shrews around Buena Vista Lake have been diminished or extirpated due to habitat deterioration and human development. In order to study the patterns of genetic variation in isolated populations of Buena Vista Lake shrews, we developed 10 polymorphic microsatellite loci. There were 6–27 alleles per locus, and the loci had heterozygosity values that ranged from 20 to 80%. In addition, we screened 20 different populations of S. ornatus, eight species within two subfamilies of shrews (Soricinae and Crocidurinae), as well as in a mole (Talpidae, Neurotrichus gibbsii), to determine if these loci could be informative in other species as well.     

Molecular phylogenetics of shrews (Mammalia: Soricidae) reveal timing of transcontinental colonizations

We sequenced 2167 base pairs (bp) of mitochondrial DNA cytochrome b and 16S, and 1390 bp of nuclear genes BRCA1 and ApoB in shrews taxa (Eulipotyphla, family Soricidae). The aim was to study the relationships at higher taxonomic levels within this family, and in particular the position of difficult clades such as Anourosorex and Myosorex. The data confirmed two monophyletic subfamilies, Soricinae and Crocidurinae. In the former, the tribes Anourosoricini, Blarinini, Nectogalini, Notiosoricini, and Soricini were supported. The latter was formed by the tribes Myosoricini and Crocidurini. The genus Suncus appeared to be paraphyletic and included Sylvisorex. We further suggest a biogeographical hypothesis, which shows that North America was colonized by three independent lineages of Soricinae during middle Miocene. Our hypothesis is congruent with the first fossil records for these taxa. Using molecular dating, the first exchanges between Africa and Eurasia occurred during the middle Miocene. The last one took place in the Late Miocene, with the dispersion of the genus Crocidura through the old world.     

Das Geruchsorgan des TiefseefischesAphanopus carbo (Percomorphi,Trichiuridae)

The paper deals with the structure of the olfactory organ, its accessory parts and the forebrain in the deep-sea fishAphanopus carbo. On each side of the head only one opening leads to the olfactory chamber. The olfactory folds are arranged in a rosette-like pattern, resembling the 360°-type. Secondary folds on the main folds may serve as an enlargement of the surface of the olfactory epithelium. Most of the surface area of the olfactory folds is covered by the olfactory epithelium, indicating that the receptive area is of optimal extension. The histological structure of the olfactory epithelium is similar to that in other teleost species. The number of olfactory receptors amounts to about 5×10⁶ to 10⁷ for the single organ. Numerous secretory cells of unknown function are located within the olfactory epithelium. The olfactory chamber is enlarged by three accessory sacs: Two ethmoidal sacs and one lacrymal sac (consisting of two parts). These sacs serve as ventilation aparatus which causes a permanent water current within the olfactory chamber and between the olfactory folds. The action of the accessory sacs is induced by the splanchnokinetic. The forebrain ofAphanopus carbo is well developed; its size ranges between that of forebrains in microsmatic and macrosmatic teleost species. A detailed investigation of the forebrain is in preparation. The diagnosis of the different parts of the olfactory apparatus ofAphanopus carbo demonstrates clearly that — in addition to the eye — this sense organ is well developed (relative to that in other teleosts). This fact suggests thatAphanopus carbo is related to a group of teleost species characterized by optical and olfactory orientation mechanisms of high performance.     

The septal organ of the rat during postnatal development

The septal organ of Masera (SO) is a small, isolated patch of olfactory epithelium, located in the ventral part of the nasal septum. We investigated in this systematic study the postnatal development of the SO in histological sections of rats at various ages from the day of birth (P1) to P666. The SO-area increases to a maximum at P66-P105, just as the animals reach sexual maturity, and decreases thereafter, significantly however only in males, indicating a limited neurogenetic capacity for regeneration. In contrast, the main olfactory epithelium area continues to expand beyond P300. The modified respiratory epithelium ('zwischen epithelium') separating the SO and the main olfactory epithelium contains a few olfactory neurons up to age P66. Its length increases postnatally so that the SO becomes more ventral to the OE. Although the position of the SO relative to other anatomical landmarks changes with development it is consistently located just posterior to the opening of the nasopalatine duct (NPAL). Thus, a possible function of the SO is in sensing chemicals in fluids entering the mouth by licking and then delivered to the nasal cavity via the NPAL; therefore the SO may be involved in social/sexual behavior as is the vomeronasal organ (VNO). We suggest that the SO is a separate accessory olfactory organ with properties somewhat different from both OE and VNO and may exist only in species where the NPAL does not open into the VNO.     

Development of Olfactory Behavior in Captive Ring-Tailed Lemurs (Lemur catta)

We conducted a long-term research project (1996–1999) on developmental aspects of olfactory behavior in ring-tailed lemurs to document the ontogenetic sequence of olfactory behavior, including the possible presence of sexual differences, and the maturation of scent-marking. The subjects were a group of 18 lemurs housed in the Pistoia Zoo (Tuscany, Italy), which we observed during 1,735 h via all-occurrences sampling, scan-animal sampling and ad libitum sampling methods. We determined the time sequence of olfactory exploration and of scent-marking patterns, and investigated sexual differences in timing and frequency. We also followed the development of scent-marking through the juvenile and adolescent phases taking into account the two aspects of motor control and of the acquisition of social competence. On the whole, we found that olfactory investigation appears and matures earlier than scent-marking. Moreover, olfactory investigation of conspecifics appeared later than substrate exploration, and seemed to follow a sequence of increasing level of acceptance by the receiver. Social play is very important for the maturation of the gestural component of scent-marking. The olfactory behavioral pattern appeared to mature during the juvenile and adolescent phases. Although sexual maturation had obvious influence on the development of olfactory behavior, the onset of scent-marking patterns was only partially parallel to sexual maturation.     

Diversity in the olfactory epithelium of bony fishes: Development, lamellar arrangement, sensory neuron cell types and transduction components

In this study we use a taxon-based approach to examine previous, as well as new findings on several topics pertaining to the peripheral olfactory components in teleost fishes. These topics comprise (1) the gross anatomy of the peripheral olfactory organ, including olfactory sensory neuron subtypes and their functional parameters, (2) the ultrastructure of the olfactory epithelium, and (3) recent findings regarding the development of the nasal cavity and the olfactory epithelium. The teleosts are living ray-finned fish, and include descendants of early-diverging orders (e.g., salmon), specialized descendants (e.g., goldfish and zebrafish), as well as the Acanthopterygii, numerous species with sharp bony rays, including perch, stickleback, bass and tuna. Our survey reveals that the olfactory epithelium lines a multi-lamellar olfactory rosette in many teleosts. In Acanthopterygii, there are also examples of flat, single, double or triple folded olfactory epithelia. Diverse species ventilate the olfactory chamber with a single accessory nasal sac, whereas the presence of two sacs is confined to species within the Acanthopterygii. Recent studies in salmonids and cyprinids have shown that both ciliated olfactory sensory neurons (OSNs) and microvillous OSNs respond to amino acid odorants. Bile acids stimulate ciliated OSNs, and nucleotides activate microvillous OSNs. G-protein coupled odorant receptor molecules (OR-, V1R-, and V2R-types) have been identified in several teleost species. Ciliated OSNs express the G-protein subunit G_αolf/s, which activates cyclic AMP during transduction. Localization of G protein subunits G_α0 and G_αq/11 to microvillous or crypt OSNs, varies among different species. All teleost species appear to have microvillous and ciliated OSNs. The recently discovered crypt OSN is likewise found broadly. There is surprising diversity during ontogeny. In some species, OSNs and supporting cells derive from placodal cells; in others, supporting cells develop from epithelial (skin) cells. In some, epithelial cells covering the developing olfactory epithelium degenerate, in others, these retract. Likewise, there are different mechanisms for nostril formation. We conclude that there is considerable diversity in gross anatomy and development of the peripheral olfactory organ in teleosts, yet conservation of olfactory sensory neuron morphology. There is not sufficient information to draw conclusions regarding the diversity of teleost olfactory receptors or transduction cascades.