• Journal of Plant Biotechnology
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• v.33 no.1
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• pp.65-73
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• 2006

Regulatory mechanism for endogenous levels of castasterone (CS) and its biosynthetic precursors in shoots of maize was investigated by the use of enzyme solution prepared from the plant tissue. When [$^2H_0$]- and [$^2H_6$]-CS was used as substrates, [$^2H_0$]-26-norCS and [$^2H_3$]-28-norCS were identified as products, indicating that [$^2H_0$]- and [$^2H_6$]-CS are differently metabolized into [$^2H_0$]-26-norCS and [$^2H_3$]-28-norCS by C-26 and C-28 demethylation, respectively. This suggests that both C-26 and C-28 demethylation can be involved in CS catabolism. In fact that C-28 demethylation only occurred when isotope labeled substrate was used, however, C-26 demethylation is thought be a natural reaction occurred in the maize shoots. When 6-deoxoteasterone (6-deoxoTE) was used, 6-deoxo-26-norTE and 3-dehydro-6-deoxo-26-norTE as well as 6-deoxo-3-dehydroTE and 6-deoxotyphasterol (6-deoxoTY) were identified as enzyme products. When 6-deoxoTY was added, 6-deoxo-26-norTY as well as 6-deoxo-3-dehydroTE and 6-deoxoTE was identified as products. These indicate that C-26 demethylation of 6-deoxoTE, 6-deoxo-3-dehydroTE and 6-deoxoTY as well as a reversible C-3 epimerization from 6-deoxoTE to 6-deoxoTY intermediated by 6-deoxo-3-dehydroTE are operative in the maize shoots, demonstrating that endogenous levels of biosynthetic precursors of CS are also controlled by C-26 demethylation. Therefore, it is thought that C-26 demethylation is an important and a common deactivation process which functions to maintain steady state levels of endogenous brassinosteroids in the maize shoots.

• Sijohaknonchong
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• v.22
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• pp.27-55
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• 2005

Visual media are taken the highest position in modem society, Modern poems also have been changed into visual poems, This aspect is the result of considering only individual talents ignoring traditions. Now, new Sigo should be concentrated on the mythological and historical voice from true nature and the body of human being, That is. ut should be converted into an ecological world view resolutely and restored a form of expression granted specific characteristics of our language. Advantages the computer media have brought. that is. equality freedom. human rights. harmony. pro-environmental value. can be maximized by positively accepting an ecological world view of Sijo which had included daily lives and spirits of the nation. Moreover. these all changes of new Sijo have to be established and recreated in the traditional expressions of Sijo. Aesthetic value of Sijo should be found in the expression forms such as phonetic harmony, rules of versification, rhythm, and etc. Then, we can overcome modern society's pathological phenomena such as severance, separation, dissolution, estrangement, psychiatric syndrome and etc. which visual media superiority brought. At the same time. it will cure ills of modern poems, Sijo and writing epochally and can establish true happiness and development.