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541.
Maria Grazia Galli 《Planta》1984,160(3):193-199
Excised watermelon cotyledons were grown in water and benzyladenine, which greatly promotes growth, breakdown of reserves and development of organelles. In order to investigate the involvement of DNA synthesis in these benzyladenine-induced effects, [3H]thymidine was applied continuously (for 3 d) or administered briefly (5 h) to excised cotyledons at various stages of development. Autoradiographic analysis of squashed and sectioned cotyledons showed that both the cytoplasm (mainly in the region of the plastids) and most of the nuclei were labelled. Both types of labelling were promoted by benzyladenine treatment. The highest percentage of labelled nuclei was found in the early stages of growth (first day after excision of cotyledons), long before the burst of enzymatic activities involved in the germination processes. The possible meaning of the increase of nuclear DNA, apart from the normal replicative synthesis preceding cell division, is discussed.Abbreviations BA
N6-benzyladenine
- DNase
deoxyribonuclease
- EtBr
ethidium bromide
- FUdR
fluorodeoxyuridine
- [3H]T
[methyl-3H]thymidine 相似文献
542.
Cytokinins have two different effects on protonemata of Funaria hygrometrica. They induce branching of unbranched caulonemata and bud formation. Branching occurs after treatment with pico-molar concentrations of cytokinins whereas bud formation requires micro-molar concentrations. Both processes are therefore independently stimulated by cytokinins.Abbreviation BA
N6-benzyladenine 相似文献
543.
Sridevy Sriskandarajah Els Prinsen Václav Motyka Petre Ivanov Dobrev Margrethe Serek 《Journal of Plant Growth Regulation》2006,25(1):79-88
The recalcitrant nature and increased regenerative capacity in relation to in vitro subcultures in two cactus genera Rhipsalidopsis (Easter cactus) and Schlumbergera (Christmas cactus) were studied by examining the endogenous concentrations of several endogenous phytohormones and enzyme
activities. Leaf tissue from greenhouse-grown mother plants, in vitro subcultures 1 and 3, and callus tissues were analyzed and correlated with regenerative ability. The cytokinins present in
the two cacti genera were mainly isopentenyl-type derivatives. The total content of isopentenyl-type cytokinins in greenhouse-grown
leaves of Rhipsalidopsis was more than twice the amount found in greenhouse-grown leaves of Schlumbergera. The total cytokinin content decreased during subculturing. Cytokinin oxidase/dehydrogenase (CKX, EC 1.4.3.18/1.5.99.12)
activity increased during subculturing. In Schlumbergera there is no effect of subculturing on CKX and related cytokinin homeostasis. The total peroxidase (POX, EC 1.11.1.7) activity
in greenhouse-grown leaves of both genera was low, and the activity increased significantly during subculturing, more specifically
in the tissue of Rhipsalidopsis. The results clearly indicated that an enhanced auxin metabolism (biosynthesis, conjugation/deconjugation, and POX activity),
in combination with an enhanced CKX activity, shifts the auxin and cytokinin pool, favoring adventitious shoot formation in
Rhipsalidopsis, whereas the low level of POX activity, together with auxin autotrophy/conjugation, makes Schlumbergera more recalcitrant.
S. S. and E. P. contributed equally to this work 相似文献
544.
Troy A. McDiarmid Alex J. Yu Catharine H. Rankin 《BioEssays : news and reviews in molecular, cellular and developmental biology》2019,41(9)
Recent work indicates that there are distinct response habituation mechanisms that can be recruited by different stimulation rates and that can underlie different components (e.g., the duration or speed) of a single behavioral response. These findings raise the question: why is “the simplest form of learning” so complicated mechanistically? Beyond evolutionary selection for robustness of plasticity in learning to ignore, it is proposed in this article that multiple mechanisms of habituation have evolved to streamline shifts in ongoing behavioral strategy. Then, speculations are offered regarding the implications of this reconceptualization of habituation for approaching the analysis of mechanisms of more complex forms of learning and memory. 相似文献
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546.
《Current biology : CB》2023,33(8):1397-1406.e5
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547.
548.
The white-light-(WL) induced enlargement of dicotyledonous leaf cells is known to occur via an acid-growth mechanism; i.e., WL causes leaf cells to excrete protons which lead to an increase in wall extensibility and thus cell enlargement. Gibberellic acid (GA3) and N6-benzyladenine (BA) also induce leaf cell enlargement. To see if they also act via acid-induced cell wall loosening, a comparison has been made of WL-, GA3-and BA-induced growth of strips, taken from primary leaves of bean (Phaseolus vulgaris L.) plants raised in continuous red light for 10 d. White light, GA3 and BA all increased wall extensibility as measured by the Instron technique, and this change preceded the increase in growth rate. However, whereas WL induced significant proton excretion, neither GA3 nor BA caused any acidification of the apoplast. Furthermore, neutral buffers, which effectively inhibited the growth induced by WL, were without effect on growth promoted by either GA3 or BA. These results indicate that while WL, GA3 and BA all initiate growth in bean leaves by altering cell-wall properties, GA3 and BA do so through some wall loosening mechanism other than wall acidification. Neither gibberellin nor cytokinin is likely to play a major role in light-induced cell enlargement of dicotyledonous leaves.Abbreviations BA
No-benzyladenine
- FC
fusicoccin
- GA3
gibberellic acid
- RL
red light
- SK medium
10 mM sucrose+10mM KCl
- WL
white light 相似文献
549.
550.