含金地质体表生带中主要微生物类群的研究

通过对16个含金矿区主要微生物类群的分布、生态结构的研究,发现不同类型的金矿具有不同的微生物类群.金矿矿石与金矿酸水中的自养硫细菌和异养菌分布具有明显差异,酸性水中含自养硫细菌较多,含异养菌极少;金矿氧化带中的异氧菌一般多于自氧硫细菌,其优势菌以芽孢杆菌属中蜡状芽孢杆菌为主.研究结果揭示了金矿中存在的主要微生物类群,对阐明表生金的形成、成岩和蚀变作用具有一定的意义,对发掘生物湿法冶金菌种资源具有重要作用.     

mtDNA and Y-chromosome polymorphisms in four Native American populations from southern Mexico.

mtDNA sequence variation was examined in 60 Native Americans (Mixtecs from the Alta, Mixtecs from the Baja, Valley Zapotecs, and Highland Mixe) from southern Mexico by PCR amplification and high-resolution restriction endonuclease analysis. Four groups of mtDNA haplotypes (haplogroups A, B, C, and D) characterize Amerind populations, but only three (haplogroups A, B, and C) were observed in these Mexican populations. The comparison of their mtDNA variation with that observed in other populations from Mexico and Central America permits a clear distinction among the different Middle American tribes and raises questions about some of their linguistic affiliations. The males of these population samples were also analyzed for Y-chromosome RFLPs with the probes 49a, 49f, and 12f2. This analysis suggests that certain Y-chromosome haplotypes were brought from Asia during the colonization of the Americas, and a differential gene flow was introduced into Native American populations from European males and females.     

Pulsed-field fingerprinting of listeriae: identification of genomic divisions for Listeria monocytogenes and their correlation with serovar.

Clamped homogeneous electric field (CHEF) electrophoresis was optimized for genomic analyses of Listeria monocytogenes. Various human, animal, food, and environmental isolates, as well as strains representing other Listeria species, were separately digested with rarely cutting endonucleases. Of 176 L. monocytogenes strains analyzed, the enzymes AscI and ApaI established 63 and 72 unique restriction endonuclease digestion profiles (REDP), respectively. The 22 non-L. monocytogenes strains exhibited 18 AscI and 19 ApaI unique REDP. Statistical analyses of REDP information using the Dice coincidence index and principal component analysis revealed two distinct genomic divisions of L. monocytogenes that also correlated with the flagellar (H) antigen type: division I contained serovar 1/2a, 1/2c, 3a, and 3c stains and division II contained serovar 1/2b, 3b, 4b, 4d, and 4e strains. Division I isolates digested with ApaI were further grouped into cluster IA (serovar 1/2c and 3c) and cluster IB (serovar 1/2a and 3a) strains. Likewise, division II isolates digested with ApaI were further grouped into cluster IIA (serovar 1/2b and 3b) and cluster IIB (serovar 4b, 4d, and 4e) strains. These data indicate that genotypic data generated by CHEF can be directly related to phenotypic data generated by serotyping for establishing the overall relatedness of isolates. Moreover, these data further substantiate that CHEF analysis is a reproducible and highly discriminating method for characterizing L. monocytogenes strains at the molecular level.     

Bone sialoprotein mRNA expression and ultrastructural localization in fetal porcine calvarial bone: comparisons with osteopontin

Summary Bone sialoprotein (BSP) and osteopontin (OPN) are two major non-collagenous proteins in bone that have similar biochemical properties and can mediate cell attachment through an RGD (Arg-Gly-Asp) motif that recognizes the vitronectin receptor. To facilitate evaluations of the biological functions of BSP and OPN in bone formation, affinity-purified rabbit polyclonal antibodies against porcine BSP and OPN were used, together with a high-resolution protein A-gold immunocytochemical technique to reveal the ultrastructural localization of these proteins in undermineralized sections of 50-day fetal porcine calvarial bone. In addition,³⁵S-labelled antisense riboprobes were prepared to demonstrate the cellular expression of BSP and OPN in the same tissues usingin situ hybridization. Immunolocalization for both BSP and OPN revealed the highest density of gold particles associated with electron-dense organic material found at the mineralization front and in ‘cement lines’. Labelling was also observed in the mineralized matrix over electron-dense material between collagen fibrils. In the osteoid of newly-formed bone, immunogold labelling for BSP and OPN was associated with loci of mineralization, which were often characterized by feathery clusters of fine needle-like crystals. Results ofin situ hybridization on the same tissues demonstrated that BSP mRNA expression was restricted to differentiated osteoblasts with particularly strong signals evident at sites ofde novo bone formation. More moderate expression of BSP was observed in ‘older’ osteoblasts and in some of the newly-entrapped osteocytes. Although expression of OPN mRNA was also observed in osteoblasts and osteocytes, the level of hybridization was similar for most bone cells and not markedly stronger than the signal observed in some stromal cells. While it is evident from these and other studies that both BSP and OPN are associated with bone formation, the differences observed in cellular expression indicate distinct roles for these proteins in bone formation.     

<Emphasis Type="Italic">Alona alsafadii</Emphasis> n. sp. from Yemen,a primitive,groundwater-dwelling member of the <Emphasis Type="Italic">A. karua</Emphasis>-group

The effect of algae on the production of musty-smelling compounds by actinomycetes was studied. Streptomyces spp., causing intensive musty odor, were isolated from hypertrophic Lake Kasumigaura and cultured in association with algae from the same lake. Isolate E and I effectively utilized the cyanobacteria, Microcystis aeruginosa and Anabaena spiroides, and the diatom, Synedra acus, as a carbon source and produced a musty-smelling 2-methylisoborneol in the shaken sediment cultures. High populations of algae and actinomycetes, and aerobic condition in the sediment seem responsible for the occurrence of musty odor in Lake Kasumigaura.     

Phylogeny and physiology of Drosophila opsins

Phylogenetic and physiological methods were used to study the evolution of the opsin gene family in Drosophila. A phylogeny based on DNA sequences from 13 opsin genes including representatives from the two major subgenera of Drosophila shows six major, well-supported clades: The blue opsin clade includes all of the Rhl and Rh2 genes and is separated into two distinct subclades of Rhl sequences and Rh2 sequences; the ultraviolet opsin clade includes all Rh3 and Rh4 genes and bifurcates into separate Rh3 and Rh4 clades. The duplications that generated this gene family most likely took place before the evolution of the subgenera Drosophila and Sophophora and their component species groups. Numerous changes have occurred in these genes since the duplications, including the loss and/or gain of introns in the different genes and even within the Rhl and Rh4 clades. Despite these changes, the spectral sensitivity of each of the opsins has remained remarkably fixed in a sample of four species representing two species groups in each of the two subgenera. All of the strains that were investigated had R1-6 (Rhl) spectral sensitivity curves that peaked at or near 480 nm, R7 (Rh3 and Rh4) peaks in the ultraviolet range, and ocellar (Rh2) peaks near 420 nm. Each of the four gene clades on the phylogeny exhibits very conservative patterns of amino acid replacement in domains of the protein thought to influence spectral sen sitivity, reflecting strong constraints on the spectrum of light visible to Drosophila.     

Taxonomy, biology and abundance of icefishes, or noodlefishes (Salangidae), in the Yellow River estuary of the Bohai Sea, China

Four species of icefishes were sampled in the Yellow River estuary of the Bohai Sea from April 1984 to April 1985 and from February 1988 to June 1989. Morphological analysis showed that they belonged to three subfamilies of Salangidae: one species from Protosalangicae, Protosalanx chinensis ; two species from Salanginae, Salanx ariakensis and Salanx prognathus ; and one species, Neosalanx andersoni , from Salangichthyinae, a new subfamily. External morphological characteristics, population composition, growth, maturity, food habits, longevity, fecundity, abundance and distribution of these icefishes are described. Based on these analyses, a clear outline of taxonomy, zoogeography aod biology of icefishes in the Yellow River estuary of the Bohai Sea was established.