1,720,962 research outputs found
Sequence of the gene encoding an alkaline serine protease of thermophilic Bacillus smithii
No full textThe complete nucleotide sequence of the gene encoding an alkaline serine protease from Bacillus smithii has been determined. Degenerate oligodeoxyribonucleotide primers were used to prime the amplification of a 507-bp sequence of the gene. This sequence was successively used for constructing new primers applied in inverse polymerase chain reaction, using as template self-ligated DNA fragments. The deduced amino-acid sequence is compared to serine proteases from B. amyloliquefaciens, B. licheniformis, B. subtilis and Thermus aquaticus
Cloning, sequencing and expression of the ilvBNC gene cluster from Streptomyces avermitilis
No full textThe metabolism of the branched-chain amino acids (BCAA) isoleucine, leucine and valine is correlated to the production of polyketide antibiotics in many streptomycetes. Despite its significance, this biosynthetic pathway is poorly understood in Streptomyces. In order to develop a better understanding of Streptomyces BCCA biosynthesis, two genes, ilvBN and ilvC, encoding acetohydroxy acid synthase (AHS) and acetohydroxy acid isomeroreductase (IR), respectively, were cloned from Streptomyces avermitilis, a strain producing avermectins, potent antiparasitic compounds. The genes were isolated by applying a combination of PCR and genomic library screening. The deduced amino-acid sequences revealed significant homology to the AHS and IR proteins from other bacterial species. The ilvBN gene, expressed in Escherichia coli (Ec) by using the expression vector pGEX-4T-1, complemented the ilv- mutation of Ec PS1283. Ec transformants produced high levels of AHS, whose activity was feedback inhibited by valine
Lactobacillus helveticus heterogeneity in natural cheese starters: The diversity in phenotypic characteristics
No full textThe study of wild strains from natural habitats is a useful means of understanding better the heterogeneity within a species of biotechnological importance, and of obtaining atypical isolates with unknown capabilities. In the present research carried out on different Lactobacillus helveticus strains isolated from natural cheese starters, it was observed that several biotechnologically important characteristics can differ greatly between strains. Biotypes were found which differ in terms of fructose, maltose and trehalose fermentation, acidifying activity, proteolytic and peptidase activity, and antibiotic and lysozyme resistance. The possibility of choosing Lact. heleveticus strains with specific biotechnological profiles will influence the quality and the variety of dairy products
Detection and characterization of naturally occurring plasmids in Bacillus licheniformis
No full textTwenty-two Bacillus licheniformis strains, freshly isolated from pasture-land, were studied for the presence of plasmid DNA. Among these strains, 14 were shown to harbor one or more plasmids of different size. Southern-hybridization experiments showed a high homology between all plasmids investigated and a 2.2-kb PvuII/HindIII fragment of pBL1, a B. licheniformis plasmid previously isolated. Three fragments of pBL1, including the 2.2-kb PvuII/HindIII region, were cloned into pJH101 vector. The resulting chimeras were able to transform Bacillus subtilis. The fragment with high homology probably contains the region with the replicative functions of plasmids from B. licheniformis species
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
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