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  • Articles  (117)
  • 2010-2014  (39)
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  • Biology  (117)
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  • 1
    ISSN: 1095-8649
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Electrophoretic studies of proteins remain a primary source of insight into genetic diversity in many species including the Atlantic salmon Salmo salar, one of the most culturally and economically important fish species of the North Atlantic region. Since 1966, 〉350 scientific papers on protein variation have been published encompassing 25 000+ salmon from over 400 locations in 〉200 river systems across the species’ distribution. Variation has been detected at 30% of the 110 protein loci screened, though most studies examine 〈40. The method has been applied largely to the investigation of population structure and differentiation, but work has also led to the systematic revision of the genus Salmo and remains the primary source of insight into hybridization in the wild with brown trout Salmo trutta. Spatial patterns of differentiation show temporal stability, both within and among river systems, and strongly support structuring of the species into river and tributary specific populations and the designation of European and North American populations as distinct sub-species. They also show widespread regional differentiation within both continents, beyond the marked subcontinental differences between Baltic Sea and Atlantic Ocean populations in Europe. Most of the differentiation probably reflects gene flow and founder events associated with colonization following the retreat of the glaciers from much of the species’ modern range. However, variation at MEP-2* shows strong correlations with environmental temperature, both within and among rivers, and associations with phenotypic performance. This suggests selection is acting on the locus and provides compelling evidence for the local adaptation of populations. Protein studies have led to more population centred management of the species and have been exploited in the discrimination of regional stocks in mixed stock analysis in high seas fisheries, particularly in the Baltic Sea, and as markers for the assessment of stocking success. They have also advanced insight into how the genetic character of populations can be changed in cultivation and the potential impact of salmon aquaculture and stocking on wild populations. The method has been largely superseded by DNA based analyses, but the results remain highly relevant to Atlantic salmon management and conservation and are an irreplaceable data set for studying genetic stability of populations over time.
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  • 2
    Electronic Resource
    Electronic Resource
    Oxford, UK; Malden, USA : Blackwell Science Ltd
    Journal of fish biology 67 (2005), S. 0 
    ISSN: 1095-8649
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: The extent of genetic variation and levels of temporal and spatial heterogeneity was investigated, at six polymorphic protein-coding loci, in wild Atlantic salmon Salmo salar populations from six rivers of Asturias (Northern Spain). Also, stocks from northern Europe that were among those introduced to repopulate Asturian Rivers, and other wild Spanish and European populations were characterized. The lack of temporal variation observed suggests that effective population sizes of Asturian populations are sufficiently large to prevent extreme levels of genetic drift and that the introduced fish had a negligible contribution to the fisheries of Asturian rivers.
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  • 3
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Ecology of freshwater fish 8 (1999), S. 0 
    ISSN: 1600-0633
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract– To assess the levels of gene introgression from cultured to wild brown trout populations, four officially stocked locations and four nonstocked locations were sampled for one to three consecutive years and compared to the hatchery strain used for stocking. Allozyme analysis for 25 loci included those previously described as providing allelic markers distinguishing hatchery stocks and native populations. Different levels of hybridization and introgression with hatchery índividuals were detected in stocked drainages as well as in protected locations. These findings indicate that new policies for stocking and monitoring hatchery fish are needed if gene pools of wild Spanish brown trout populations are to be preserved.
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  • 4
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Biochemical analysis revealed the presence of GTP-binding proteins (G-proteins) in Catharanthus roseus hairy root cultures. In a microsomal fraction, several proteins, with molecular masses of 17, 21, 38, 42, 65, and 79 kDa were substrates for ADP-ribosylation by cholera toxin. Antisera raised against a conserved amino-acid sequence (GTSNSGKSTIVKQMK) of mammalian Gα subunits recognized three proteins of 42, 50, and 79 kDa. Incubation of nitrocellulose blots with [α-32P]-GTP also indicated the presence of several proteins (17, 21, 50, and 79 kDa) that could bind GTP. In this system, we previously identified a phosphatidylinositol 4,5-bisphosphate-phospholipase C (PLC, EC 3.1.4.11) activity. As the activation of PLC by G-proteins was described, we decided to see whether, in our system, G-protein activators, such as guanosine 5-o-(3-thiotriphosphate) (GTPΓS) and sodium fluoride ions, were able to regulate PLC activity in C.roseus transformed roots. Our results show that these agents regulated PLC activity in an inhibitory fashion and that this effect is dose-dependent. GTP was ineffective in producing either stimulation or inhibition of PLC activity. Our results demonstrate that non-hydrolyzable guanine nucleotides and fluoride ions exert an inhibitory effect on membrane PLC activity. In summary, a set of proteins of 17, 21, 38, 42, 50, and 79 kDa present in C.roseus transformed roots possessed at least two of the three main characteristics of a GTP-binding protein, and one of these proteins may be involved in the regulation of PLC activity in C.roseus transformed roots.
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  • 5
    ISSN: 1365-2761
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: Experimental infection of rainbow trout, Oncorhynchus mykiss (Walbaum), juveniles with Loma salmonae at a water temperature of 15 °C yielded detectable parasite DNA within the gills by week 2 post-exposure (PE) and detectable spore-wall antigen within developing xenomas by week 3 PE, as determined by in situ hybridization and monoclonal antibody (Mab) based immunohistochemistry, respectively. The microsporidian was most commonly located within endothelial cells of lamellar basal channels. Whereas the onset of xenoma formation appeared to be relatively synchronous, as expected from previous studies, xenoma dissolution followed an unexpected biphasic pattern with peaks at weeks 4 and 9 PE. The onset of significant growth rate suppression, at week 4 PE in exposed fish, was temporally associated with the appearance of gill lesions which, in turn, were centred about sites of premature xenoma dissolution. The latter was determined by the detection of spore-wall antigen within lesions. Co-habitant control fish began developing xenomas by week 10, indicating the infective potential of those spores released from the principal fish during early xenoma dissolution. Although infection with L. salmonae significantly affects fish growth rates, the time-course of this suppression is limited, and as an unexpected finding, growth rate recovery commences prior to the infection’s resolution.
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  • 6
    ISSN: 1365-2761
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: Twelve tanks of juvenile rainbow trout, Oncorhynchus mykiss (Walbaum), were treated twice weekly for an 11- week period with a one-hour static bath of chloramine-T (10 mg l–1). The morphometric indices of gill damage and the histochemical characteristics of gill mucous cells of fish from treated and paired untreated tanks were compared. The use pattern of chloramine-T in this study evoked a slight increase in mean lamellar width, but it did not induce a greater degree of lamellar oedema, lamellar fusion, tissue infiltration, epithelial hyperplasia, chloride cell metaplasia or thrombosis of pillar channels in treated fish. Treatment caused a trend towards an increased number of mucous cells on lamellae, associated with a significant shift from neutral mucin to acid mucin production based on histochemical characteristics.
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  • 7
    Electronic Resource
    Electronic Resource
    [s.l.] : Nature Publishing Group
    Nature 378 (1995), S. 241-241 
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] SIR - It is generally accepted that sculptures or objets d'art are useless from the scientific point of view. We would like to show here an example of a certain type of sculpture that is of scientific relevance, and which can be related to the recent discovery of the so-called photonic band-gap ...
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  • 8
    ISSN: 1574-6968
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: To monitor changes along the entire Helicobacter pylori vacA gene we carried out full-length single-step PCR amplification in 21 gastritis and gastric cancer isolates. HindIII restriction analysis led us to detect a 〉400-bp internal insertion in vacA subsequently shown to be a direct 451-bp gene duplication. We found HindIII profiles for 16 genes that allowed their grouping into two restriction patterns that were related to theoretical profiles for previously sequenced Western genes. Comparisons with theoretical HindIII patterns for Japanese isolates appear suggestive of geographical H. pylori clonality. Full-length single-step PCR amplification seems suitable for quick restriction pattern assignment and detection of gene size changes.
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  • 9
    ISSN: 1574-6968
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Abstract Mice were immunized with resin-bound peptides whose sequences have been proposed to be part of exposed loops in Salmonella typhi outer membrane protein OmpC. To screen hybridomas for monoclonal antibodies against those epitopes, we designed fusion proteins where the candidate peptide sequence was attached to the amino end of cholera toxin B-subunit (CTB). The constructed fusion proteins allowed the efficient selection of positive clones by GM1-ELISA. Selected antibodies recognized purified OmpC and whole Salmonella bacteria. This suggests a native structure of our genetically attached peptides in agreement with immunological properties reported for previous CTB recombinant fusion proteins. In a more general context, CTB hybrids could be used to screen for antibodies towards immunogenic epitopes in other systems. This might turn out to be particularly useful when producing antibodies against peptide sequences in microorganisms whose handling is difficult or that pose inherent health risks.
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  • 10
    ISSN: 1476-5535
    Keywords: Keywords: biotin production; E. coli bio operon; Agrobacterium/Rhizobium HK4; limiting growth conditions
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: E. coli biotin (bio) operon was modified to improve biotin production by host cells: (a) the divergently transcribed wild-type bio operon was re-organized into one transcriptional unit; (b) the wild-type bio promoter was replaced with a strong artificial (tac) promoter; (c) a potential stem loop structure between bioD and bioA was removed; and (d) the wild-type bioB ribosomal binding site (RBS) was replaced with an artificial RBS that resulted in improved bioB expression. The effects of the modifications on the bio operon were studied in E. coli by measuring biotin and dethiobiotin production, and bio gene expression with mini-cells and two-dimensional polyacrylamide gel electrophoresis. The modified E. coli bio operon was introduced into a broad host-range plasmid and used to transform Agrobacterium/Rhizobium HK4, which then produced 110 mg L−1 of biotin in a 2-L fermenter, growing on a defined medium with diaminononanoic acid as the starting material. Biotin production was not growth-phase dependent in this strain, and the rate of production remained high under limiting (maintenance) and zero growth conditions.
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