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21. The salinity tolerance of freshwater cyanobacterium Synechococcus sp. PCC 7942 is determined by Its ability for osmotic adjustment and presence of osmolyte sucrose

Creator:
Ladas, N. P. and Papageorgiou, G. C.
Format:
bez média and svazek
Type:
model:article and TEXT
Subject:
absorption spectra, cell doubling, chlorophyll content and fluorescence, cytoplasmic osmolality, glucose, NaCl, saccharose, and sugars
Language:
Multiple languages
Description:
We investigated the factors that impose an upper limit of salinity tolerance to the unicellular freshwater cyanobacterium Synechococcus sp. PCC 7942. Above approx. 0.4 M NaCl, Synechococcus cells cease to proliferate, after having accumulated 0.3 M sucrose. Cells that pre-accumulated sucrose could tolerate up to 0.5 M NaCl, but not 0.6 M NaCl. After exposure to 0.5 M NaCl or higher, the cells were irreversibly modified becoming unable for osmotic volume adjustments. and N. P. Ladas, G. C. Papageorgiou.
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

22. The substrate utilization and concentration of 14C photosynthates in citronella under Fe deficiency

Creator:
Srivastava, N. K., Misra, A., and Sharma, S.
Format:
bez média and svazek
Type:
model:article and TEXT
Subject:
acetate, amino acids, 14CO2, Cymbopogon winterianus, oil, organic acids, primary and secondary metabolites, sugars, and [U-14C]; [U-14C] saccharose incorporation
Language:
Multiple languages
Description:
Changes in the utilization pattern of primary substrate, viz. [U-14C] acetate, 14CO2 and [U-14C] saccharose, and the contents of 14C fixation products in photosynthetic metabolites (sugars, amino acids, and organic acids) were determined in Fe-deficient citronella in relation to the essential oil accumulation. There was an overall decrease in photosynthetic efficiency of the Fe-deficient plants as evidenced by lower levels of incorporation into the sugar fraction and essential oil after 14CO2 had been supplied. When acetate and saccharose were fed to the Fe-deficient plants, despite a higher incorporation of label into sugars, amino acids, and organic acids, there was a lower incorporation of these metabolites into essential oils than in control plants. Thus, the availability of precursors and the translocation to a site of synthesis/accumulation, severely affected by Fe deficiency, is equally important for the essential oil biosynthesis in citronella. and N. K. Srivastava, A. Misra, S. Sharma.
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

23. Utilization of exogenously supplied 14C-saccharose into primary metabolites and alkaloid production in Catharanthus roseus

Creator:
Srivastava, N. K. and Srivastava, A. K.
Format:
bez média and svazek
Type:
model:article and TEXT
Subject:
amino acids, assimilate partioning, leaf, organic acids, roots, stem, and sugars
Language:
Multiple languages
Description:
Partitioning of exogenously supplied U-14C-saccharose into primary metabolic pool as sugars, amino acids, and organic acids was analyzed and simultaneous utilization for production of alkaloid by leaf, stem, and root in twigs and rooted plants of Catharanthus roseus grown in hydroponic culture medium was determined. Twigs revealed comparable distribution of total 14C label in leaf and stem. Stems contained significantly higher 14C label in sugar fraction and in alkaloids [47 kBq kg-1(DM)] than leaf. In rooted plants, label in 14C in metabolic fractions in root such as ethanol-soluble, ethanol-insoluble, and chloroform-soluble fractions and in components such as sugars, amino acids, and organic acids were significantly higher than in stems and leaves. This was related with significantly higher content of 14C in alkaloids in stems and leaves. 14C contents in sugars, amino acids, and organic acids increased from leaf to stem and roots. Roots are the major accumulators of metabolites accompanied by higher biosynthetic utilization for alkaloid accumulation. and N. K. Srivastava, A. K. Srivastava.
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

24. Utilization of photosynthetically fixed 14CO2 into alkaloids in relation to primary metabolites in developing leaves of Catharanthus roseus

Creator:
Srivastava, N. K., Misra, A., Srivastava, A. K., and Sharma, S.
Format:
bez média and svazek
Type:
model:article and TEXT
Subject:
amino acids, chlorophyll, leaf area and dry mass, leaf ontogeny, net photosynthetic rate, organic acids, sugars, terpenoids, and total alkaloids
Language:
Multiple languages
Description:
Partitioning of current photosynthates towards primary metabolites and its simultaneous incorporation in leaf alkaloids was investigated in developing leaves of medicinally important Catharanthus roseus. Of the total 14CO2 assimilated, the leaves at positions 1-6 fixed 8, 22, 25, 19, 13, and 8 %, respectively, and stem 3 %. Leaf fresh mass, chlorophyll content, and CO2 exchange rate increased up to the third leaf. The total alkaloid content was highest in young actively growing leaves, which declined with age. Total 14C fixed and its content in ethanol soluble fraction increased up to the third leaf and then declined. The 14C content in primary metabolites such as sugars and organic acids was also highest in the 3rd leaf. The utilization of 14C assimilates into alkaloids was maximum in youngest leaf which declined with leaf age. Hence the capacity to synthesize alkaloids was highest in young growing leaves and metabolites from photosynthetic pathway were most efficiently utilized and incorporated into alkaloid biosynthetic pathway by young growing leaves. and N. K. Srivastava ... [et al.].
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public