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41.
The present study analyzed binding of Cu2+ to tetrapeptides in water solution at several levels of theoretical approximation. The methods used to study the energetic
and structural properties of the complexes in question include semiempirical hamiltonians, density functional theory as well
as ab initio approaches including electron correlation effects. In order to shed light on the character of interactions between
Cu2+ and peptides, which are expected to be mainly electrostatic in nature, decomposition of interaction energy into physically
meaningful components was applied. 相似文献
42.
Iwona Żur Andrzej Skoczowski Sebastian Pieńkowski Franciszek Dubert 《Acta Physiologiae Plantarum》2002,24(1):11-17
The uptake rate of 14C-labelled sucrose, myo-inositol and PC was studied in callus cultures of two oilseed rape cultivars, characterized by different in vitro regeneration ability. Transfer of calli onto regeneration stimulating medium resulted in changes of examined substances uptake
rate, which were depended on tissue morphogenic potential. Non-regenerating calli of both cultivars increased uptake rate
of sucrose whereas changes in incorporation of other compounds were under genome control. Significant increase of uptake rate
of all tested compounds was observed as result of organogenesis initiation. Such differences, in the responses of organogenic
and non-organogenic tissue indicate that this parameter could be useful as marker of organogenesis
A correlation was observed between the rate of sucrose uptake and its concentration in the medium, which suggests an advantage
to passive transport through the callus cell membrane. Lack of such correlation in the case of other labels indicates that
this processes are selective and under cell control. 相似文献
43.
Żur Iwona Skoczowski Andrzej Niemczyk Elżbieta Dubert Franciszek 《Acta Physiologiae Plantarum》2002,24(1):3-10
Changes in the membrane lipid and sterols content and composition were studied during induction and differentiation in callus
cultures of Brassica napus var. oleifera. Callus induction was associated with an increase of DGDG content, significant changes in fatty acids composition of all
lipid fractions and increased degree of lipid unsaturation. The membrane lipid composition of tissue at different degrees
of differentiation was found to vary significantly, particularly two weeks after transfer of callus to regeneration medium.
The main differences concerned the content and composition of galactolipids. Curiously in many cases, these differences declined
during subsequent culture, in spite of the morphogenesis process which was in progress. Another result of differentiation
was the change in free sterol composition: in shoot regenerating calli the content of stigmasterol had rose whereas the accumulation
of campesterol decreased. Even though observed changes in membrane properties may not play a role in morphogenesis they are
nevertheless useful as developmental markers and can be invaluable in understanding biochemical basis of morphogenesis. 相似文献
44.
Does a heavy fruit crop reduce the tree ring increment? Results from a 12-year study in a subalpine zone 总被引:1,自引:0,他引:1
Life history theory posits that an increased investment in reproduction should result in decreased vegetative investment. Switching resources from growth to reproduction are also expected in species experiencing selection pressure for high variation of seed crops. In this study, we tested whether the reproductive effort of trees, measured as the number of fruits produced, is related to their radial growth increment. We examined a population of Sorbus aucuparia, a fleshy-fruited tree species with highly variable interannual individual fruit production growing in the subalpine zone and under strong selection pressure from pre-dispersal seed predators. We used 12-year data to test the relationship between fruit crop and radial growth increments in current, previous and subsequent years, and found no trade-off between growth and reproduction. For almost all trees, there was no correlation between fruit crop and radial growth increment in the same year or next year. Only a few trees showed a positive correlation between fruit crop and previous-year growth. In the statistics, we took advantage of the high variability of individual fruit crops in high production years. In four heavy crop years, we compared the radial growth increments of trees with heavy crops with those of trees with low fruit crops. Current and next-year radial growth did not differ between trees with low and high fruit crops. In all those years, however, trees having heavy fruit crops had higher previous-year growth increments. We suggest that the harsh subalpine weather conditions account for the lack of a trade-off between growth and reproduction in the studied population. 相似文献
45.
46.
M. Kubacka N. Szkaradek S. Mogilski K. Pańczyk A. Siwek A. Gryboś B. Filipek P. Żmudzki H. Marona A.M. Waszkielewicz 《Bioorganic & medicinal chemistry》2018,26(13):3773-3784
A series of aminoisopropanoloxy derivatives of xanthone has been synthesized and their pharmacological properties regarding the cardiovascular system has been evaluated. Radioligand binding and functional studies in isolated organs revealed that title compounds present high affinity and antagonistic potency for α1-(compound 2 and 8), β-(compounds 1, 3, 4, 7), α1/β-(compounds 5 and 6) adrenoceptors. Furthermore, compound 7, the structural analogue of verapamil, possesses calcium entry blocking activity. The title compounds showed hypotensive and antiarrhythmic properties due to their adrenoceptor blocking effect. Moreover, they did not affect QRS and QT intervals, and they did not have proarrhythmic potential at tested doses. In addition they exerted anti-aggregation effect. The results of this study suggest that new compounds with multidirectional activity in cardiovascular system might be found in the group of xanthone derivatives. 相似文献
47.
48.
Tissue culture of Dianthus caryophyllus L. (cv. William Sim.) obligatory requiring N6-benzyladenine for greening provides a good system to study the interactions between cytokinins and polyamines. Polyamines
were analyzed as dansyl derivatives which are separated by thin layer chromatography and detected by fluorescence spectrophotometry.
Green callus growing on benzyladenine — containing medium showed decrease in the contents of free, conjugated and bound putrescine
and spermidine in comparison to chlorophyll-less callus (control callus) growing on cytokinin-free medium. The level of spermine
free, conjugated and bound forms increased about 6 %, 77 % and 28 % respectively in tissue culture growing in the presence
of cytokinin.
Spermidine was dominant polyamine bound to chromatin isolated from control callus. Chromatin isolated from green callus was
characterized by a lower level of each polyamine in comparison to chlorophyll-less callus.
Polyamines were found in plastid membrane fraction isolated from chlorophyll-less and green callus. A significant increase
the levels of polyamines (putrescine, spermidine and spermine) bound to plastid membranes in green callus (+ benzyladenine)
in comparison to chlorophyll-less callus (− benzyladenine) was observed. Additionaly, methylglyoxal-bis(guanylhydrazone) an
inhibitor of S-adenosylmethionine decarboxylase depressed the greening process.
Our results suggest that cytokinin-induced chloroplast differentiation in carnation tissue culture may be partly mediated
through the polyamines bound to thylakoid membranes. A possible role of polyamines during cytokinin-induced formation of photosynthetic
apparatus is discussed. 相似文献
49.
50.
Daughter yield deviations (DYDs) of bulls and yield deviations (YDs) of cows, besides estimated breeding values (EBVs), are standard measures of animals' genetic merits in routine genetic evaluations worldwide. In this contribution, we first point out differences and similarities between DYDs and EBVs calculated for milk, fat and protein yields. While the latter measure represents the additive polygenic value of an animal, the former consists of both the additive polygenic and residual components. Then, a summary of DYDs and YDs calculated for the Polish population of dairy cattle is presented. The estimated correlations between DYDs and EBVs are generally high, but vary considerably depending on the minimum number of daughters used for calculation of DYDs and on the accuracy of calculated DYDs. Using DYDs estimated for each production year for 16 452 bulls, we demonstrate how to use DYDs for the validation of genetic trend estimated in the model used for genetic evaluation. Based on genotypic data of 252 bulls, we show that DYDs can be used for the estimation of candidate gene effects. For each of the yield traits, the within-bull genetic trend was relatively high, ranging between 1.39% of genetic standard deviation per production year for milk and 7.67% of genetic standard deviation per production year for fat, both in the 2nd lactation. Out of 8 polymorphisms tested, 5 showed a significant correlation with DYD, with the highest effect attributed to the polymorphism within the leptin receptor gene, whose additive effect was estimated as 247.33 kg of milk at 2nd parity. 相似文献