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Start Over Coverage 75-84

1. An application of the generalized Bessel function

Creator:
Darwish, Hanan, Lashin, Abdel Moneim, and Hassan, Bashar
Format:
bez média and svazek
Type:
model:article and TEXT
Subject:
Bessel operator, starlike function, convex function, and close-to-convex function
Language:
English
Description:
We introduce and study some new subclasses of starlike, convex and close-to-convex functions defined by the generalized Bessel operator. Inclusion relations are established and integral operator in these subclasses is discussed.
Rights:
http://creativecommons.org/publicdomain/mark/1.0/ and policy:public

3. Combined effects of irradiance and first autumn frost on CO2 assimilation and selected parameters of chlorophyll a fluorescence in Norway spruce shoots

Creator:
Kalina, J., Marek, M.V., and Špunda, V.
Format:
print
Type:
model:internalpart and TEXT
Language:
Multiple languages
Description:
The state of some parameters of photosynthetic activity in Norway spruce (Picea abies [L.] Karst.) seedlings during the first autumn temperature transition to frost was monitored in October 1991. The trees were grown under field conditions of the Beskydy Mts. (North Moravia, The Czech Republic). Simultaneous measurements of Chi a fluorescence and C02 gas exchange revealed two phases in the functional transition of the assimilatory apparatus. Immediately upon the temperature transition to frost a distinct decrease in the radiant energy saturated rate of C02 uptake was observed and radiationless dissipation was indicated by higher values of the nonphotochemical quenching coefficient. The second period of the transition, a period with prolonged influence of frost together with a higher level of irradiance, was connected with a decrease of photosynthetic efficiency. The overwhelming capacity for protective non-photochemical energy dissipation and the complete reduction of acceptor QA occurred especially at medium and high incident irradiance documenting photoinhibitory damage to the photosynthetic apparatus.
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

4. Differential inhibition of photosynthesis under drought stress in Flaveria species with different degrees of development of the C4 syndrome

Creator:
Dias, M. C. and Brüggemann, W.
Format:
bez média and svazek
Type:
model:article and TEXT
Subject:
bundle sheath cells, C3, C4 metabolism, CO2 compensation concentration, malic enzyme, NADP-malate dehydrogenase, phosphoenolpyruvate carboxylase, pyruvate-orthophosphate dikinase, RuBP, RuBPCO, stromal fructose 1,6-bisphosphatase, and water potential
Language:
Multiple languages
Description:
The effect of drought stress (DS) on photosynthesis and photosynthesis-related enzyme activities was investigated in F. pringlei (C3), F. floridana (C3-C4), F. brownii (C4-like), and F. trinervia (C4) species. Stomatal closure was observed in all species, probably being the main cause for the decline in photosynthesis in the C3 species under ambient conditions. In vitro ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBPCO) and stromal fructose 1,6-bisphosphatase (sFBP) activities were sufficient to interpret the net photosynthetic rates (PN), but, from the decreases in PN values under high CO2 (C a = 700 µmol mol- 1) it is concluded that a decrease in the in vivo rate of the RuBPCO reaction may be an additional limiting factor under DS in the C3 species. The observed decline in the photosynthesis capacity of the C3-C4 species is suggested to be associated both to in vivo decreases of RuBPCO activity and of the RuBP regeneration rate. The decline of the maximum PN observed in the C4-like species under DS was probably attributed to a decrease in maximum RuBPCO activity and/or to decrease of enzyme substrate (RuBP or PEP) regeneration rates. In the C4 species, the decline of both in vivo photosynthesis and photosynthetic capacity could be due to in vivo inhibition of the phosphoenolpyruvate carboxylase (PEPC) by a twofold increase of the malate concentration observed in mesophyll cell extracts from DS plants. and M. C. Dias, W. Brüggemann.
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

6. Photosynthesis, energy partitioning, and metabolic adjustments of the endangered Cistaceae species Tuberaria major under high temperature and drought

Creator:
Osório, M. L., Osório, J., and Romano, A.
Format:
bez média and svazek
Type:
model:article and TEXT
Subject:
botanika, botany, anthocyanins, chlorophyll fluorescence imaging, energy partitioning, malondialdehyde, proline, soluble sugars, 2, and 58
Language:
Multiple languages
Description:
In view of predicted climatic changes for the Mediterranean region, study of high temperature and drought impacts on physiological responses of endangered species regains relevance. In this context, micropropagated plants of Tuberaria major, a critically endangered species, endemic of Algarve, were transferred to a controlled-environment cabinet with day/night temperatures set at 25/18°C (Reference) or 32/21°C (HT). After 15 days of HT acclimation, some plants were subjected to progressive drought followed by rewatering. The enhancement of temperature alone did not affect water relations and photosynthetic rates (PN) but the stomatal conductance (gs) exhibited a 3-fold increase in comparison with reference plants. The maximum quantum yield of photosystem (PS) II (Fv/Fm), the effective quantum yield of PSII photochemistry (ΦPSII), carotenoid (Car) and anthocyanin content enhanced, whereas the quantum yields of regulated (ΦNPQ) and nonregulated (ΦNO) energy dissipation decreased. Drought combined with HT reduced predawn leaf water potential to values of about -1.3 MPa, which had adverse effects on gas exchange and PSII activity. Values of PN and gs were 71 and 79% lower than those of HT plants. An impairment of photochemical activity was also observed: the decrease in ΦPSII and the increase of ΦNPQ. However, an irreversible photoinhibitory damage had not occurred. Carotenoid and anthocyanin content remained elevated and soluble sugars (SS) increased twice, whereas proline and MDA accumulation was not detected. On the first 24 h after water-stress relief, gs, PN, ΦPSII, and ΦNPQ did not recover, but SS returned to the reference level. Overall, T. major acquired an adequate capacity for a protection against the development of oxidative stress during drought and water recovery under HT. These findings suggest that T. major is prepared to deal with predicted climate changes., M. L. Osório, J. Osório, A. Romano., and Obsahuje bibliografii
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public