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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Journal of comparative physiology 98 (1975), S. 243-256 
    ISSN: 1432-1351
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Beavers studied under natural conditions near Québec City, Canada, displayed a yearly cycle of patterns of activity rhythms. In winter, the beaver colonies had a free-running circadian rhythm of period length 26.25 to 28.0 h, with or without relative coordination, depending on available light intensity, which in turn depends on ice and snow cover conditions; in summer, their activity rhythm followed a “normal” 24 h period. Transitions between these two patterns suggest that annual variations in the beaver's physiological state affect their reaction towards the presence or absence of a Zeitgeber.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Plant cell reports 15 (1995), S. 222-226 
    ISSN: 1432-203X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Growth inhibition towards Rhizopus nigricans, Fusarium oxysporum f. sp. radicis-lycopersici, Verticillium albo-atrum and Pythium ultimum was observed in vitro using a purified chitosanase from an actinomycete, Streptomyces sp, strain N174. The corresponding gene, with its own signal peptide, was inserted into pBI121.7 shuttle vector to transform tobacco. Transgenic plants were analysed for chitosanase activity by a sodium dodecyl sulfate-polyacrylamide gel electrophoresis assay. Two major and one minor active electrophoretic forms were detected in transgenic tobacco. Some chitosanases were recovered not only in leaf homogenates but also in leaf intercellular fluid extracts. One chitosanase electrophoretic form migrated very closely to the purified Streptomyces mature protein while the others corresponded to molecules of higher molecular mass. The N-terminus sequence was determined for one of the three chitosanase forms. It exhibited a different signal peptide cleavage site when compared to the mature chitosanase from Streptomyces. This is the first report on the expression of an active chitosanase gene with antimicrobial potential in plants.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1530-0358
    Keywords: Colonic carcinogenesis ; Ulcerative colitis ; Ileostomy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract This study was undertaken to determine if the construction of an ileal reservoir induces mucosal changes that can potentiate the effect of a chemical carcinogen (1,2-dimethylhydrazine) on ileal mucosa. Animals were divided into three groups: 1) sham operation (n=19), 2) total colectomy with ileorectal anastomosis (n=20), 3) total colectomy with an ileal reservoir made of terminal ileum sutured to the rectum (n=20). An adaptation period of 12 weeks was allowed to promote fecal stasis and the histologic changes before exposure to weekly subcutaneous injections of DMH (25 mg/kg) for 16 weeks. Sodium butyrate was added to the diet as a tumor promotor. All animals were sacrificed one month later. Fecal stasis, along with enlargement, occurred in all the reservoirs (mean dimensions, 74×58×43 mm). Their mean volume was 88±14 ml. The histologic changes in the ileal reservoirs were: chronic inflammation (14/20), villous atrophy (14/20), and atrophy of the glands (8/20). In group 3, five carcinomas were seen. There were three in the duodenum and two in the reservoirs. In contrast, 21 carcinomas were detected in the control groups. There were 17 in the colon, 3 in the jejunum, and 1 in the ileum. No significant difference in the number of carcinomas was seen in the ileum with and without reservoir. Although it is possible to induce carcinomas in ileal reservoirs, the incidence remained significantly less than in the colon. In conclusion, the histologic changes induced by the construction of an ileal reservoir do not increase the risk of malignant transformation in the DMH model for intestinal carcinogenesis.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1617-4623
    Keywords: Autolysin ; Hydrolase ; In vitro transcription and translation ; Recombinant DNA ; Transcriptional and translational signals
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Several hundred bacterial isolates were screened for bacteriolytic activity by growing them on agar medium containing autoclaved, lyophilized Micrococcus lysodeikticus cells as the substrate. A Bacillus sp. producing the largest lytic zone was selected. A genomic bank of this selected bacterium was constructed in the multi-functional vector pTZ18R, with partial SauIIIA DNA fragments inserted at the SalI restriction site. Screening of 800 colonies of this bank for cell lysis gave 5 recombinants exhibiting lytic activity, as detected by analysis of extracts of sonicated Escherichia coli cells on denaturing polyacrylamide gels containing autoclaved, lyophilized M. lysodeikticus cells as the substrate. One clone (pBH2500), expressed inE. coli strain NM522, was found to code for a lytic enzyme corresponding, in molecular weight, to the 27 kDa Bacillus sp hydrolase. This clone with an insertion of 2.5 kb was then subcloned as a 929 bp EcoRI-SauIIIA fragment in pTZ18R (pBH929) and showed higher cell lytic activity. A unique open reading frame for a protein of 251 amino acids, followed by a putative terminator sequence, was found after a consensus ribosome binding site. A putative leader sequence was identified in the first 37 amino acids. One truncated subclone (pBH703), corresponding to 196 out of 251 residues from the protein N-terminal end, still possessed lytic activity.
    Type of Medium: Electronic Resource
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