Abstract. A total of 90 tumors from 85 domestic hamsters (70 Djungarian hamsters and 15 Syrian hamsters) were examined by histology. In the Djungarian hamsters, 64 neoplastic and 11 non-neoplastic lesions were identified, whereas 14 Syrian hamsters showed neoplastic disease, and one showed nonneoplastic disease. The Djungarian hamsters showed a high prevalence of neoplastic disease, similarly to laboratory Djungarian hamsters. In the Djungarian hamsters, almost all tumors were integumental, whereas hematopoietic tumors were the most common type in the Syrian hamsters. The most common integumental tumors in the Djungarian hamsters were mammary tumors, atypical fibromas and papillomas, and a spectrum of integumental tumors that have not been reported in laboratory Djungarian hamsters were identified. Most mammary tumors occurred in the females, whereas all atypical fibromas were observed in the males. In the Syrian hamsters, plasmacytomas and lymphomas were the most common tumors. The small number of Syrian hamsters in this study may reflect the low prevalence of spontaneous tumors seen in laboratory Syrian hamsters. The mean age of the affected hamsters was 19.8 months, which is relatively advanced. To our knowledge, this is the first comprehensive study of tumors in domestic hamsters.
A total of 11 strains of moderately halophilic histamine-producing bacteria isolated from fermented squid liver sauce were studied phenotypically, genotypically, and phylogenetically. These strains are considered members of the genus Tetragenococcus based on their physiological, morphological, and chemotaxonomic characteristics. A 16s rRNA gene sequence analysis showed that these strains clustered with, but were separate from, Tetragenococcus halophilus. The results of DNA-DNA hybridization experiments indicated that the new isolates represent a new Tetragenococcus species, for which we propose the name Tetragenococcus muriaticus; strain X-1 (= JCM 10006) is the type strain of this species.Pediococcus halophilus was described as a halophilic lactic acid bacterium which requires sodium chloride (NaC1) for growth and is tolerant of a high NaCl concentration (more than 18%). According to Bergey's Manual of Systematic Bacteriology (6), tetrad cocci which are tolerant of 18% NaCl are members of P. haloThilus. Recently, however, Collins et al. (4) reported that P. halophilus is phylogenetically more closely related to enterococci and lactobacilli than to pediococci on the basis of 16s 16s rRNA sequence data, and thus they proposed that P. halophilus should be reclassified in a new genus, the genus Tetragenococcus, with Tetragenococcus halophilus as the single species recognized in the genus (2).Previous workers have isolated large numbers of T. halophilus as the predominant bacteria (7, 8) from Shottsuru, a Japanese local traditional fermented fish sauce, which contains more than 25% NaC1. In this study, we isolated histamineproducing lactic acid bacteria from Shottsuru-like squid liver sauce. Eleven strains were designated strains X-lT to X-11 and were different from authentic T. halophilus strains in the following characteristics: production of histamine, lack of L-arabinose fermentation, growth at 40°C, and 16s rRNA gene (rDNA) sequence. To precisely identify and phylogenetically place the new isolates, phenotypic characterization, analysis of fatty acid compositions, 16s rDNA sequencing, and DNA-DNA hybridization were performed. On the basis of our results we propose that our isolates should be placed in a new species, Tetragenococcus muriaticus. MATERIALS AND METHODSBacterial strains and growth conditions. A total of 11 strains (X-lT to X-11) were isolated from squid liver sauce, a Japanese local traditional fermented seafood. These strains were maintained on stab cultures in 10% NaCl-GYP agar (lo), which was supplemented with 10% sodium chloride, 1% magnesium sulfate, 0.1% potassium chloride, 0.5% calcium carbonate, and 0.3% agar. The pH was adjusted to 7.0 with 1.0 N NaOH. The cultures were incubated for about 2 days at 30°C. The strains were stored at 4°C and were transferred to fresh medium every third month. Unless indicated otherwise, the inocula used for phenotypic tests were prepared from 48-to 60-h-old cultures in 10% NaCl-GYP broth and incubated at 30°C.Morphology. Cell morphology was observed by using ...
Few studies have analyzed pollen and seed movements at local scale, and genetic differentiation among populations covering the geographic distribution range of a species. We carried out such a study on Cercidiphyllum japonicum; a dioecious broad-leaved tree of cool-temperate riparian forest in Japan. We made direct measurement of pollen and seed movements in a site, genetic structure at the local scale, and genetic differentiation between populations covering the Japanese Archipelago. Parentage analysis of seedlings within a 20-ha study site indicated that at least 28.8% of seedlings were fertilized by pollen from trees outside the study site. The average pollination distance within the study site was 129 m, with a maximum of 666 m. The genotypes of 30% of seedlings were incompatible with those of the nearest female tree, and the maximum seed dispersal distance within the study site was over 300 m. Thus, long-distance gene dispersal is common in this species. The correlation between genetic relatedness and spatial distance among adult trees within the population was not significant, indicating an absence of fine-scale genetic structure perhaps caused by high levels of pollen flow and overlapping seed shadows. Six populations sampled throughout the distribution of C. japonicum in Japan showed significant isolation-by-distance but low levels of genetic differentiation (F ST ¼ 0.043), also indicating long-distance gene flow in C. japonicum. Longdistance gene flow had a strong influence on the genetic structure at different spatial scales, and contributes to the maintenance of genetic diversity in C. japonicum. Heredity (2006) 96, 79-84.
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