GLORIA

GEOMAR Library Ocean Research Information Access

X
feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    Electronic Resource
    Electronic Resource
    Demonstration of β-N-acetyl-D-glucosaminidase and β-N-acetyl-D-hexosaminidase in Drosophila Kc-cells (1991)
    New York, NY [u.a.] : Wiley-Blackwell
    Archives of Insect Biochemistry and Physiology 17 (1991), S. 3-13 
    Details
    ISSN: 0739-4462
    Keywords: intra- and extracellular enzymes ; kinetic properties ; inhibition ; Chemistry ; Food Science, Agricultural, Medicinal and Pharmaceutical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Kc-cells from Drosophila melanogaster, grown under serum-free conditions, produce two β-hexosaminidases and secrete these enzymes into the medium. The two enzymes were separated by DEAE-exchange chromatography. According to their substrate specificities one enzyme is a β-N-acetyl-D-glucosaminidase (E.C.3.2.1.30), the other one a β-N-acetyl-D-hexosaminidase (E.C.3.2.1.52). The β-N-acetyl-D-glucosaminidase is predominant in the medium, the β-N-acetyl-D-hexosaminidase within the cells. The Km values for the substrates pNP-GlcNAc, pNP-GalNAc, and (GlcNAc)2 are 0.8, 16.73, and 1.67 mM for the β-N-acetyl-D-glucosaminidase and 0.24, 0.44, and 0.2 mM for the β-N-acetyl-D-hexosaminidase. Both enzymes are inhibited by the products and the β-N-acetyl-D-glucosaminidase is also inhibited stereospecifically by the substrates pNP-GlcNAc and (GlcNAc)2. Both enzymes are inhibited in a partial competitive way by acetamidolactones, the Kis being as low as 0.1 μM.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/arch.940170103
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    Physical properties of β-N-acetyl-D-glucosaminidase and β-N-acetyl-D-hexosaminidase from Drosophila Kc-cells (1991)
    New York, NY [u.a.] : Wiley-Blackwell
    Archives of Insect Biochemistry and Physiology 18 (1991), S. 45-53 
    Details
    ISSN: 0739-4462
    Keywords: molecular mass ; pH and temperature optima ; thermal stability ; influence of ionic strength ; Chemistry ; Food Science, Agricultural, Medicinal and Pharmaceutical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Kc-cells from Drosophila produce two different β-D-hexosaminidases, a β-N-acetyl-D-glucosaminidase (E.C.3.2.1.30) and a β-N-acetyl-D-hexosaminidase (E.C.3.2.1.52), which are also secreted into the medium. The Mr of both enzymes is about 126,000 ± 9,700; the S-values are 8.37 ± 0.44. Both enzymes have about the same pH optima at 5.5 and the same thermal stability. The temperature optima are identical (50°C) for both enzymes if p-nitrophenyl-N-acetylglucosaminide is used as a substrate. However, when p-nitrophenyl-N-acetylgalactoseaminide is used as the substrate the β-N-acetyl-D-hexosaminidase has a temperature optimum about 10°C higher. With higher salt concentrations, the activity of the β-N-acetyl-D-glucosaminidase increases, whereas β-N-acetyl-D-hexosaminidase is inhibited. Both enzymes also differ in their sensitivity to urea, the β-N-acetyl-D-hexosaminidase being less sensitive than the β-N-acetyl-D-glucosaminidase.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/arch.940180105
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 3
    facet.materialart.
    Unknown
    Propagule banks, herbivory and nutrient supply control population development and dominance patterns in macroalgal blooms (2000)
    Wiley-Blackwell
    In:  Oikos, 85 . pp. 46-58.
    Details
    Publication Date: 2017-01-31
    Description: Destructive macroalgal mass blooms threaten estuarine and coastal ecosystems worldwide. We asked which factors regulate macroalgal bloom intensity, distribution and species composition. In field experiments in the Baltic Sea, we analyzed the relative effects of nutrients, herbivores and algal propagule banks on population development and dominance patterns in two co-occurring bloom-forming macroalgae, Enteromorpha intestinalis and Pilayella littoralis. Both species were highly affected by the combined effects of a propagule bank, herbivory and nutrients. The magnitude of effects varied with season. The propagule bank was an important overwintering mechanism for both algae, and allowed for recruitment two months earlier than recruitment via freshly dispersed propagules. This provided a seasonal escape from intense herbivory and nutrient limitation later in the year. Favored by massive recruitment from the propagule bank, Enteromorpha was the superior space occupier in early spring, thereby reducing recruitment of Pilayella. Elimination of the propagule bank and recruitment via freshly dispersed propagules favored Pilayella. Strong and selective herbivory on Enteromorpha supported Pilayella in the presence, but not in the absence of the propagule bank. Nutrient enrichment in summer counteracted herbivore pressure on Enteromorpha, thereby negatively affecting Pilayella. Herbivore and nutrient effects were more pronounced for early life stages than adult algae. These results show that recruitment processes and forces affecting early life stages at the beginning of the vegetation period determine development and dominance patterns of macroalgal blooms. Herbivores naturally suppress blooms but increasing nutrient enrichment can override this important control mechanism. The propagule bank plays a previously unrecognized role for population and community dynamics.
    Type: Article , PeerReviewed
    Format: text
    DOI: 10.1034/j.1600-0706.2000.890106.x
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 4
    facet.materialart.
    Unknown
    Impacts of multiple stressors on biodiversity and ecosystem functioning: The role of species co-tolerance (2004)
    Wiley-Blackwell
    In:  Oikos, 104 . pp. 451-457.
    Details
    Publication Date: 2019-09-23
    Description: Ecosystem resistance to a single stressor relies on tolerant species that can compensate for sensitive competitors and maintain ecosystem processes, such as primary production. We hypothesize that resistance to additional stressors depends increasingly on species tolerances being positively correlated (i.e. positive species co-tolerance). Initial exposure to a stressor combined with positive species co-tolerance should reduce the impacts of other stressors, which we term stress-induced community tolerance. In contrast, negative species co-tolerance is expected to result in additional stressors having pronounced additive or synergistic impacts on biologically impoverished functional groups, which we term stress-induced community sensitivity. Therefore, the sign and strength of the correlation between species sensitivities to multiple stressors must be considered when predicting the impacts of global change on ecosystem functioning as mediated by changes in biodiversity.
    Type: Article , PeerReviewed
    Format: text
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    OceanRep: Article in a Scientific Journal - peer-reviewed
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...