Comparison of Leptospira species isolated from environmental water and soil in Japan

Leptospira was isolated from environmental water in central Japan using selective medium comprising five antibiotics, namely sulfamethoxazole, trimethoprim, amphotericin B, fosfomycin, and 5‐fluorouracil. Of 100 water samples 57 (57%) were culture‐positive and 50 pure cultures were isolated. Of the 50 cultures isolated from water 48 were classified into a saprophytic clade on the basis of 16S ribosomal RNA gene sequences. However, it was previously reported that isolates from soil in Japan belonged to pathogenic, intermediate, and saprophytic clades, the current findings suggest less diversity of Leptospira species in environmental water than that in soil in Japan.     

Molecular and phenotypic characterization of Leptospira johnsonii sp. nov., Leptospira ellinghausenii sp. nov. and Leptospira ryugenii sp. nov. isolated from soil and water in Japan

In a previous study, 50 of 132 soil samples collected throughout Japan were found to be Leptospira‐positive. In the present study, three strains identified in the collected specimens, three, E8, E18 and YH101, were found to be divergent from previously described Leptospira species according to 16S ribosomal RNA gene sequence analysis. These three strains have a helical shape similar to that of typical Leptospira and were not re‐isolated from experimental mice inoculated with the cultured strains. Upon 16S ribosomal RNA gene sequence analysis, E8 was found to belong to the intermediate Leptospira species clade and E18 and YH101 to belong to the saprophytic Leptospira species clade. Based on analyses of genome‐to‐genome distances and average nucleotide identity in silico using whole genome sequences and DNA–DNA hybridization in vitro, these isolates were found to be distinct from previously described Leptospira species. Therefore, these three isolates represent novel species of the genus Leptospira for which the names Leptospira johnsonii sp. nov., (type strain E8 ^T, = JCM 32515 ^T = CIP111620 ^T), Leptospira ellinghausenii sp. nov., (type strain E18 ^T, = JCM 32516 ^T = CIP111618 ^T) and Leptospira ryugenii sp. nov., (type strain YH101 ^T, = JCM 32518 ^T = CIP111617 ^T) are proposed.     

Distribution of Plasmids in Distinct Leptospira Pathogenic Species

Leptospirosis, caused by pathogenic Leptospira, is a worldwide zoonotic infection. The genus Leptospira includes at least 21 species clustered into three groups—pathogens, non-pathogens, and intermediates—based on 16S rRNA phylogeny. Research on Leptospira is difficult due to slow growth and poor transformability of the pathogens. Recent identification of extrachromosomal elements besides the two chromosomes in L. interrogans has provided new insight into genome complexity of the genus Leptospira. The large size, low copy number, and high similarity of the sequence of these extrachromosomal elements with the chromosomes present challenges in isolating and detecting them without careful genome assembly. In this study, two extrachromosomal elements were identified in L. borgpetersenii serovar Ballum strain 56604 through whole genome assembly combined with S1 nuclease digestion following pulsed-field gel electrophoresis (S1-PFGE) analysis. Further, extrachromosomal elements in additional 15 Chinese epidemic strains of Leptospira, comprising L. borgpetersenii, L. weilii, and L. interrogans, were successfully separated and identified, independent of genome sequence data. Southern blot hybridization with extrachromosomal element-specific probes, designated as lcp1, lcp2 and lcp3-rep, further confirmed their occurrences as extrachromosomal elements. In total, 24 plasmids were detected in 13 out of 15 tested strains, among which 11 can hybridize with the lcp1-rep probe and 11 with the lcp2-rep probe, whereas two can hybridize with the lcp3-rep probe. None of them are likely to be species-specific. Blastp search of the lcp1, lcp2, and lcp3-rep genes with a nonredundant protein database of Leptospira species genomes showed that their homologous sequences are widely distributed among clades of pathogens but not non-pathogens or intermediates. These results suggest that the plasmids are widely distributed in Leptospira species, and further elucidation of their biological significance might contribute to our understanding of biology and infectivity of pathogenic spirochetes.     

咸水灌溉条件下土壤水盐分布特征

通过设置3种灌水量水平（100%ET_c、80%ET_c、60%ET_c）和3种灌水水质水平（0.7、3和6 g·L^-1）,研究了咸水灌溉条件下春小麦120 cm土层内水分动态和盐分累积特征.结果表明：水分在农田土壤中的分布主要受灌水量和土壤质地的影响,充分灌溉使水分存贮在较深土层中,而非充分灌溉则使水分存贮在表层;在相同灌水量的条件下,土体内的盐分积累程度随着灌溉水矿化度的增大而加剧;在相同矿化度条件下,土体内的盐分含量及积盐深度随着灌水量的增加而增大.在作物整个生育期内,连续使用咸水灌溉将导致土壤积盐,且非充分灌溉较充分灌溉更易使土壤表层积盐.     

Distribution and conservation of mobile elements in the genus Drosophila

Essentially nothing is known of the origin, mode of transmission, and evolution of mobile elements within the genus Drosophila. To better understand the evolutionary history of these mobile elements, we examined the distribution and conservation of homologues to the P, I, gypsy, copia, and F elements in 34 Drosophila species from three subgenera. Probes specific for each element were prepared from D. melanogaster and hybridized to genomic DNA. Filters were washed under conditions of increasing stringency to estimate the similarity between D. melanogaster sequences and their homologues in other species. The I element homologues show the most limited distribution of all elements tested, being restricted to the melanogaster species group. The P elements are found in many members of the subgenus Sophophora but, with the notable exception of D. nasuta, are not found in the other two subgenera. Copia-, gypsy-, and F-element homologues are widespread in the genus, but their similarity to the D. melanogaster probe differs markedly between species. The distribution of copia and P elements and the conservation of the gypsy and P elements is inconsistent with a model that postulates a single ancient origin for each type of element followed by mating-dependent transmission. The data can be explained by horizontal transmission of mobile elements between reproductively isolated species.      

Characterization of Leptospira species isolated from soil collected in Japan

Leptospira were isolated from soil obtained from Hokkaido, the northernmost island, to Okinawa, the southernmost island, of Japan using sulfamethoxazole, trimethoprim, amphotericin B, fosfomycin, and 5‐ fluorouracil. Fifty of 132 soil samples (37.9%) were culture‐positive. On the basis of 16S‐rDNA sequences, 12 of the isolated Leptospira were classified into a pathogenic species clade that is closely associated with L. alstonii and L. kmetyi. Nine isolates were classified as intermediate species and were found to be similar to L. licerasiae. Twenty‐seven isolates were classified as non‐pathogenic species, of which 23 were found to be related to L. wolbachii. Non‐pathogenic Leptospira are commonly distributed in environmental soil.     

Distribution of alditols in the genus Bostrychia

Several species of the red algal genus Bostrychia were investigated for the presence of low-molecular weight carbohydrates constituting their specific assimilate pattern. All species were found to contain remarkable amounts of two hexitols, dulcitol and sorbitol. The results are discussed with emphasis on the chemotaxonomic implications.     

Distribution of hobo transposable elements in the genus Drosophila

This study describes the distribution of hobo-hybridizing sequences in the genus Drosophila. Southern blot analysis of 134 species revealed that hobo sequences are limited to the melanogaster and montium subgroups of the melanogaster-species group. Of the hobo-bearing species, only D. melanogaster and two of its sibling species, D. simulans and D. mauritiana, were found to contain potentially complete hobo elements. The distribution of hobo sequences is one of the narrowest distributions thus far described for any Drosophila transposable element.     

Survival rate of Leptospira pomona in the soil at a natural leptospirosis focus

At the area of a natural focus of leptospirosis (caused by L. pomona) in the Mozdok region of the North Occetic ASSR leptospires were detected by the method of dark field microscopy in 22% of intact soil samples. The presence of pathogenic leptospires in this soil was not confirmed by the method of the biological assay on Syrian golden hamsters. In controlled tests lasting 1-277 days, in 30.4% of cases L. pomona retained their viability, pathogenic and antigenic properties for as long as 74 days, while staying in the soil at the focus of infection with humidity being 15.2-31.4% and pH = 6.7-7.2. 11 Leptospira cultures isolated after staying in the soil retained their pathogenic properties and the death of the animals used in the bioassay from the acute form of leptospiral infection.     

Distribution and molecular phylogeny of the dinoflagellate genus Ostreopsis in Thailand

The toxic benthic dinoflagellate genus Ostreopsis has been connected to the production of palytoxin and its analogs in many tropical and temperate areas. Although the type species, O. siamensis, was originally described from the Gulf of Thailand in 1901, little is known about the species composition and distribution of the genus Ostreopsis in Thailand. In this study, a total of 64 Ostreopsis strains isolated from the Andaman Sea as well as the Gulf of Thailand were investigated by analyzing the nucleotide sequences of the LSU rDNA D1/D2, D8/D10 and ITS-5.8S rDNA regions. Phylogenetic analyses (BI and ML) resulted in some of the strains being assigned to previously described clades, O. cf. ovata and Ostreopsis sp. 6, and revealed the existence of a novel clade named Ostreopsis sp. 7, which exhibited large genetic distances from the other clades. Among O. cf. ovata, several strains from Thailand were formed into a new subclade, the Thailand subclade, whereas a few strains belonged to the South China Sea subclade. Morphometric characteristics such as the cell sizes of the two O. cf. ovata subclades and those of Ostreopsis sp. 7 were not significantly different from each other (p > 0.05). Their characteristics were similar but slightly different from those of O. ovata and were significantly different from those of Ostreopsis sp. 6 (p < 0.05). Toxicities of Ostreopsis from Thailand were evaluated using mouse bioassay. Strains of Ostreopsis sp. 6 and Ostreopsis sp. 7 tested were highly toxic, while the two subclades of O. cf. ovata strains seemed to be nontoxic. This study suggests that toxic Ostreopsis sp. 7 is distributed in the Andaman Sea, whereas the two subclades of O. cf. ovata and toxic Ostreopsis sp. 6 are distributed in the Gulf of Thailand.     

Distribution and evolution of two satellite DNAs in the genus Beta

Summary EcoRI monomers of a highly repetitive DNA family of Beta vulgaris have been cloned. Sequence analysis revealed that the repeat length varies between 157–160 bp. The percentage of AT-residues is 62% on average. The basic repeat does not show significant homology to the BamHI sequence family of B. vulgaris that was analyzed by us earlier. Both the EcoRI and BamHI sequences are investigated and compared to each other with respect to their genomic organization in the genus Beta. Both repeats were found to be tandemly arranged in the genome of B. vulgaris in a satellite-like manner. The EcoRI satellite DNA is present in three sections (Beta, Corollinae and Nanae) of the genus, whereas the BamHI satellite DNA exists only in the section Beta. The distribution of the EcoRI and BamHI satellite families in the genus is discussed with respect to their evolution.     

Distribution and strain-dependent formation of volatile metabolites in the genus Ceratocystis

The accumulation of volatile metabolites in cultures of 34 strains comprising ten species of the genus Ceratocystis (Ascomycetes) has been investigated under defined culture conditions. The identified compounds include short-chain alcohols and esters, lower terpenes, terpenoids, and 2-phenylethyl acetate. Certain species can be recognized by a number of common volatiles traced in all strains, although the quantities of these constituents may vary enormously (up to a factor 1:1000) within one species. The formation of some metabolites is restricted to a few strains.     

Distribution and typology of glucose oxidase activity in the genus Penicillium

Glucose oxidase (GOD) production by 84 strains of the genus Penicillium was studied in order to define the distribution of the activity among and within the species. Plate screening and sub-screening in shake culture showed a rather homogeneous behaviour of strains belonging to the same species. Penicillium chrysogenum, P. expansum, P. italicum and P. variabile had a concomitant good production of GOD and catalase activity; peroxidase and polyphenol oxidase were never present. The capability of the culture filtrates to oxidase substrates other than glucose was also studied.     

Distribution of teichoic acids in cultures of the genus Actinomadura

The occurrence of teichoic acids in cultures of Actinomadura genus was studied. All 30 strains examined in this survey contained alditol phosphate polymers. Most of the cultures had poly(glycerol phosphate) teichoic acids. Some of the poly(glycerol phosphate) chains bear madurose as a glycosyl substituent. In seven cultures glycerol teichoic acids with an unusual localization of the phosphodiester linkage were detected. Ribitol teichoic acids were found in six organisms.