ALBERT

All Library Books, journals and Electronic Records Telegrafenberg

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
    Gene targeting approaches using positive-negative selection and large flanking regions (1997)
    Springer
    Plant molecular biology 35 (1997), S. 523-530 
    Details
    ISSN: 1573-5028
    Keywords: cytosine deaminase ; homologous recombination ; Lotus japonicus ; negative selection ; plants
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We report here on strategies aimed at improving the frequency of detectable recombination in plants by increasing the efficiency of selecting double-recombinants in transgenic calli. Gene targeting was approached on the Gln1 and the Pzf loci of Lotus japonicus, using Agrobacterium tumefaciens T-DNA replacement vectors. Large flanking regions, up to 22.9 kb, surrounding a positive selection marker were presented as substrates for homologous recombination. For easier detection of putative recombinants the negative selectable marker cytosine deaminase was inserted at the outside borders of the flanking regions offered for cross-over. A combination of positive and negative selection allowing double-recombinants to grow, while counter-selecting random insertions, was used to select putative targeting events. The more than 1000-fold enrichment observed with replacement vectors designed to minimize gene silencing demonstrated the efficiency of the negative selection. Using five different replacement vectors an estimated total of 18974 transformation events were taken through the positive-negative selection procedure and 185 resistant calli obtained. Targeting events could not be verified in the survivors by PCR screening and Southern blot analysis. With this approach the frequency of detectable gene targeting in L. japonicus was below 5.3×10−5, despite the large flanking sequences offered for recombination.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1005865600319
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    Physiological regulation of plant-atmosphere ammonia exchange (2000)
    Springer
    Plant and soil 221 (2000), S. 95-102 
    Details
    ISSN: 1573-5036
    Keywords: ammonia exchange ; apoplast ; atmosphere ; glutamine synthetase ; nitrogen ; photorespiration
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Plants have a compensation point for NH3 which ranges from 0.1 to 20 nmol mol-1, and may be several-fold higher or lower than naturally occurring atmospheric NH3 concentrations. This implies that NH3 fluxes over vegetated surfaces are bi-directional and that ammonia exchange with the atmosphere in many cases contributes significantly to the nitrogen economy of vegetation. Physiological regulation of plant–atmosphere NH3 fluxes is mediated via processes involved in nitrogen uptake, transport and metabolism. A rapid turnover of NH3 + in plant leaves leads to the establishment of a finite NH3 + concentration in the leaf apoplastic solution. This concentration determines, together with that of H+, the size of the NH3 compensation point. Barley and oilseed rape plants with access to NH3 + in the root medium have higher apoplastic NH3 + concentrations than plants absorbing NO3 -. Furthermore, the apoplastic NH3 + concentration increases with the external NH3 + concentration. Inhibition of GS leads to a rapid and substantial increase in apoplastic NH3 + and barley mutants with reduced GS activity have higher apoplastic NH3 + than wild-type plants. Increasing rates of photorespiration do not affect the steady-state NH3 + or H+ concentration in tissue or apoplast of oilseed rape, indicating that the NH3 + produced is assimilated efficiently. Nevertheless, NH3 emission increases due to a temperature-mediated displacement of the chemical equilibrium between gaseous and aqueous NH3 in the apoplast. Sugarbeet plants grown with NO3 - seem to be temporarily C-limited in the light due to a repression of respiration. As a consequence, the activity of chloroplastic GS declines during the day causing a major part of NH3 + liberated in photorespiration to be assimilated during darkness when 2-oxoglutarate is supplied in high rates by respiration.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1004761931558
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...