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  • 1
    Electronic Resource
    Electronic Resource
    Alternative Splicing of the Neurotrophin-3 Gene Gives Rise to Different Transcripts in a Number of Human and Rat Tissues (2000)
    Oxford UK : Blackwell Science Ltd.
    Journal of neurochemistry 75 (2000), S. 0 
    Details
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract : The mouse neurotrophin-3 (NT-3) gene has been shown to contain two exons (exon 1A and exon 1B) upstream of the single coding exon (exon 2). These upstream exons are alternatively spliced to the coding exon, generating two different NT-3 transcripts. We investigated whether alternative splicing of two upstream exons also occurs in the human and rat NT-3 gene. It was found that the human and rat NT-3 gene also contains two exons upstream of the main coding exon and that alternative splicing of these upstream exons generates two different NT-3 transcripts : transcript 1A and transcript 1B (TR1B). These two transcripts were widely expressed in several human and rat tissues. Also, a third transcript, transcript 1A1C, derived from splicing of exon 1A to exon 1B before splicing to the coding exon was seen in a small number of rat tissues. Previous quantification of neurotrophin-3 mRNA has not been transcript-specific. Here we describe a transcript-specific semiquantitative RT-PCR method allowing the quantification of TR1B in human tissues. We show that this is the major NT-3 transcript and that expression of this transcript was much higher in the adult when compared with the corresponding fetal tissues.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1471-4159.2000.0750041.x
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  • 2
    Electronic Resource
    Electronic Resource
    Effects of livestock grazing on benthic invertebrates from a native grassland ecosystem (2003)
    Oxford, UK : Blackwell Science Ltd
    Freshwater biology 48 (2003), S. 0 
    Details
    ISSN: 1365-2427
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: SUMMARY 1. The effects of cattle grazing on stream bank stability, biomass of riparian vegetation, instream vegetation cover, biomass of coarse particulate organic matter (CPOM) and epilithon and benthic invertebrate community structure were investigated over a 2-year period using: (i) enclosures containing different cattle grazing treatments and (ii) by comparing streams with different grazing intensities in the Cypress Hills Provincial Park, Alberta, Canada.2. Livestock enclosure experiments comprised four treatments of: (1) early season cattle grazing (June–August), (2) late season cattle grazing (August–September), (3) all season cattle grazing (June–September) and (4) cattle-absent controls. All four treatments were replicated in two streams while two treatments (i.e. cattle-absent controls, early season cattle grazing) were established in a third stream.3. Bank stability, estimated visually based on sediment inputs to the stream channel, increased significantly in cattle-absent treatments compared with cattle-present enclosures over the 2-year study period.4. Epilithic chlorophyll a was significantly affected by time, but neither cattle nor the interaction of time and treatment were significant.5. At the end of the experiment, total invertebrate biomass in the late and all-season treatment exceeded that in the early and cattle-absent treatments. However, excluding cattle from the streams, at any of the different treatments, had little clear impact on the total benthic invertebrate abundance or the abundance of the predominant functional feeding groups over the 2-year study period.6. In contrast, comparisons of benthic assemblages from streams with different grazing intensities showed that the non-grazed reach of Storm Creek contained significantly higher biomass of CPOM and shredders compared with the cattle-absent enclosures in Battle, Graburn and Nine Mile creeks. Redundancy analysis showed that benthic communities from all enclosures and Storm Creek in summer and autumn 2000 were affected primarily by CPOM biomass, pH, nitrate, turbidity and benthic chlorophyll a. Construction of a 99% probability ellipse from enclosure sites showed that invertebrate communities from livestock enclosures differed from that in the non-grazed Storm Creek.7. Results from stream-scale comparisons indicate that current livestock grazing practices in the Cypress Hills significantly impact riparian zones, stream channels and benthic invertebrate community structure and that alternative practices, such as rotational grazing, need to be developed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2427.2003.00978.x
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  • 3
    Electronic Resource
    Electronic Resource
    The Mycobacterium tuberculosis ino1 gene is essential for growth and virulence (2004)
    Oxford, UK : Blackwell Science Ltd
    Molecular microbiology 51 (2004), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: Inositol is utilized by Mycobacterium tuberculosis in the production of its major thiol and of essential cell wall lipoglycans. We have constructed a mutant lacking the gene encoding inositol-1-phosphate synthase (ino1), which catalyses the first committed step in inositol synthesis. This mutant is only viable in the presence of extremely high levels of inositol. Mutant bacteria cultured in inositol-free medium for four weeks showed a reduction in levels of mycothiol, but phosphatidylinositol mannoside, lipomannan and lipoarabinomannan levels were not altered. The ino1 mutant was attenuated in resting macrophages and in SCID mice. We used site-directed mutagenesis to alter four putative active site residues; all four alterations resulted in a loss of activity, and we demonstrated that a D310N mutation caused loss of the active site Zn2+ ion and a conformational change in the NAD+ cofactor.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2958.2003.03900.x
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  • 4
    Electronic Resource
    Electronic Resource
    The Mycobacterium tuberculosis sigJ gene controls sensitivity of the bacterium to hydrogen peroxide (2004)
    Oxford, UK : Blackwell Publishing Ltd
    FEMS microbiology letters 237 (2004), S. 0 
    Details
    ISSN: 1574-6968
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Sigma factors are important global regulators which control bacterial gene expression during growth and in response to stress. Previous work showed that mRNA of the sigJ gene was up-regulated in late stationary-phase and after rifampicin treatment. In order to verify the function of SigJ, we constructed a Mycobacterium tuberculosis mutant lacking the sigJ gene. In a microaerophilic stationary-phase model, the sigJ mutant showed the same growth pattern as the wild-type strain. In an immune stasis murine model in which the bacterial number plateaued between the second and the 15th week, the mutant showed a similar growth curve to the wild-type strain. However, the sigJ mutant was more susceptible to killing by H2O2 than its parental strain. The parental level of sensitivity to H2O2 was recovered in the sigJ complemented strain. These data suggest that the SigJ protein is not essential for survival in long-term stationary phase or in bacterial stasis in mice. However, the sigJ gene may control an alternative H2O2 resistance pathway.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1574-6968.2004.tb09725.x
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  • 5
    Electronic Resource
    Electronic Resource
    Comparisons among colonization of artificial substratum types and natural substratum by benthic macroinvertebrates (1996)
    Springer
    Hydrobiologia 341 (1996), S. 57-64 
    Details
    ISSN: 1573-5117
    Keywords: Macroinvertebrates ; colonization ; artificial substrates ; natural substrate ; sediment ; lotic
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A field study was designed to concurrently evaluate differences in colonization by benthic macroinvertebrates on a range of artificial substratum types (single particles of natural rock or clay brick and baskets of natural substratum) after three colonization periods (1, 8 and 29 days). Fauna on the artificial substrata were compared to natural substratum and the effect of natural epilithic cover on colonization by zoobenthos was determined. Densities of total number of organisms and the seven most abundant taxa, total number of taxa and quantity of organic material were greater on the natural substratum than on the artificial substratum types. Relative abundances of taxa on pairs of the artificial substratum types, unlike pairs of each artificial substratum type and the natural substratum, were statistically correlated. Among the artificial substratum types densities of total number of organisms and about one-half of the most abundant taxa, total number of taxa and quantity of organic material were greatest in the substratum baskets. Natural epilithic cover on the single rock particles and substratum baskets affected the densities of total number of organisms and two of the seven most abundant taxa. These taxonomic groups were at approximately two to six-fold greater densities on the substrata with fine sediment. consistent patterns in densities of the zoobenthos on the substrata were found after each colonization period. In our study all measures of the macroinvertebrate assemblages (densities of each taxon, total number of organisms, total number of taxa and relative abundances of taxa), with few exceptions, were different between each artificial substratum type and natural substratum. This result showed the abundance and composition of the macroinvertebrate fauna on artificial substratum types were different from the natural substratum. Therefore, the choice of using artificial substrata instead of direct sampling of the natural substratum should be carefully made. Among the artificial substratum types relative abundances of taxa were similar on the single substratum particles and substratum baskets indicating single particles instead of baskets might be used to sample the zoobenthos. Investigators should consider the potential effect of the natural epilithic cover of substratum particles on colonization by zoobenthos when choosing the type of artificial substratum.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00012303
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