Search

Recent molecular evidence of genetically distinct hantaviruses in shrews, captured in widely separated geographical regions, corroborates decades-old reports of hantavirus antigens in shrew tissues. Apart from challenging the conventional view that rodents are the principal reservoir hosts, the recently identified soricid-borne hantaviruses raise the possibility that other soricomorphs, notably talpids, similarly harbor hantaviruses. In analyzing RNA extracts from lung tissues of the Japanese shrew mole (Urotrichus talpoides), captured in Japan between February and April 2008. a hantavirus genome, designated Asama virus (ASAV), was detected by RT-PCR. Pairwise alignment and comparison of the S-, M-, and L-segment nucleotide and amino acid sequences indicated that ASAV was genetically more similar to hantaviruses harbored by shrews than by rodents. However, the predicted secondary structure of the ASAV nucleocapsid protein was similar to that of rodent- and shrew-borne hantaviruses, exhibiting the same coiled- coil helix at the amino terminus. Phylogenetic analyses, using the maximum-likelihood method and other algorithms, consistently placed ASAV with recently identified soricine shrew-borne hantaviruses, suggesting a possible host-switching event in the distant past. The discovery of a mole-borne hantavirus enlarges our concepts about the complex evolutionary history of hantaviruses. [ABSTRACT FROM AUTHOR]

We investigated the genetic structure of Sorex unguiculatus and Sorex caecutiens populations in Hokkaido, Japan, using hypervariable microsatellite DNA markers. We used five microsatellite loci to type 475 S. unguiculatus individuals from 20 localities on the Hokkaido mainland and four localities from each of four offshore islands (and 11 shrews from one locality in southern Sakhalin for a particular analysis). We used six microsatellite loci to type 240 S. caecutiens individuals from 13 localities on the Hokkaido mainland. Genetic variation was high in mainland populations of both species and low in the island populations of S. unguiculatus. Allelic richness and island size were positively correlated for S. unguiculatus, suggesting that genetic drift occurred on those islands due to small population size. In addition, four insular populations of S. unguiculatus were genetically differentiated from the mainland populations, although clear phylogeographic clustering was not confirmed among populations on the Hokkaido mainland for either S. unguiculatus or S. caecutiens. Heterozygosity excess was observed in more than half of the populations including the mainland populations of the two species, suggesting recent bottleneck events in these populations. Population dynamics of the shrews might be explained by a metapopulation scheme. According to autocorrelation analysis, the extent of non-random spatial genetic structure was approximately 100 km. Isolation by distance was observed in S. unguiculatus, but not in S. caecutiens although there is a positive trend. The lack of correlation for S. caecutiens might have been due to small sample size. Thus, no obvious differences in population genetic structure were found between the two species on the Hokkaido mainland in the present study, while previous investigations using mitochondrial DNA sequences inferred that these two species might have rather different biogeographic histories. [ABSTRACT FROM AUTHOR]

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 . [ABSTRACT FROM AUTHOR]

Phylogenetic relationships among 8 species of white-toothed shrews (Crocidurinae, Mammalia) in East and Central Asia were evaluated based on mitochondrial cytochrome-b gene sequences. The taxon formerly regarded as Crocidura suaveolens in East Asia phylogenetically is distinct from that of true C. suaveolens in Europe, suggesting that specimens in East Asia should be considered a distinct species, C. shantungensis. All shrews from Central Asia were regarded as C. sibirica, although phylogenetic comparison with the unsampled C. gmelini is needed to confirm its taxonomic status. C. shantungensis, C. suaveolens, and C. sibirica formed a well-supported monophyletic group. C. dsinezumi, C. lasiura, C. kurodai, and C. watasei also formed a well-supported monophyletic group. Within C. dsinezumi, there were 2 clusters, referable to western and eastern Japan. Based on low genetic divergence, C. dsinezumi on Cheju and Hokkaido islands appear to be the result of a recent introduction from western Japan and northern-eastern Honshu, respectively. [ABSTRACT FROM AUTHOR]

Venomous mammals are rare, and their venoms have not been characterized. We have purified and characterized the blarina toxin (BLTX), a lethal mammalian venom with a tissue kallikrein-like activity from the submaxillary and sublingual glands of the short- tailed shrew Blarina brevicauda. Mice administered BLTX i.p. developed irregular respiration, paralysis, and convulsions before dying. Based on the amino acid sequence of purified protein, we cloned the BLTX cDNA. It consists of a prosequence and an active form of 253 aa with a typical catalytic triad of serine proteases, with a high identity with tissue kallikreins. BLTX is an N-linked microheterogeneous glycoprotein with a unique insertion of 10 residues, L106TFFYKTFLG115. BLTX converted kininogens to kinins, which may be one of the toxic pathogens, and had dilatory effects on the blood vessel walls. The acute toxicity and proteolytic activity of BLTX were strongly inhibited by aprotinin, a kallikrein inhibitor, suggesting that its toxicity is due to a kallikrein-like activity of the venom. [ABSTRACT FROM AUTHOR]

A letter to the editor is presented in response to the article on a novel bat-borne hantavirus in Vietnam.

The horse (Equus caballus) varieties from Skyros and Rhodes islands (Greece) in the Aegean archipelago are extremely small, reaching shoulder heights of only about 1 m. Furthermore, the Japanese archipelago is home to eight small, native horse breeds. We investigated the evolutionary morphology and provided a review of historical documentations of these horses of cultural interest in Greece and Japan, thus providing a comparison of the independent evolution of small size in islands. We integrate cranial data from historical literature with data from newly gathered and curated skulls and analyse a measurement dataset featuring various domestic and mainland horse breeds and varieties. We use non-invasive imaging to study and measure 3D models of the bony labyrinth, housing the inner ear, and the braincase endocast. When considering the effects of allometry by regressing each PC1 scores (for each set of measurements) with the cranial geometric mean from linear measurements as a body size proxy, we show that size explains a large amount of the shape variation in horse crania, the bony labyrinths and brain endocasts. We found high intrabreed variation in all the analysed datasets. Globally, there are at least 30 distinct horse populations on islands, offering the chance to further study processes of convergence in morphological divergence and evaluate the effect of drift and the environment. [ABSTRACT FROM AUTHOR]