請教 woth

俺在下麵的貼裏說：

• 水稻葉本身是合成胡蘿卜素的。黃金大米隻是激活了米胚中的胡蘿卜素合成。 - 26484915 - ♂ (688 bytes) (12 reads) 09/04/2014  11:11:27

• 你理解的不對哈 - woth - ♀ (0 bytes) (3 reads) 09/04/2014

俺想請教一下：哪裏理解不對？

Golden Rice technology is based on the simple principle that rice plants possess the whole machinery to synthesise β-carotene, and while this machinery is fully active in leaves, parts of it are turned off in the grain. By adding only two genes, a plant phytoene synthase (psy) and a bacterial phytoene desaturase (crt I), the pathway is turned back on and β-carotene consequently accumulates in the grain.

金稻米技術的產生基於一個簡單的原理，水稻隻能在綠葉組織中合成 β-胡蘿卜素，而在被食用的胚乳中 卻沒有，可是這個兩步的生物合成 途徑確實存在於糧食中。僅僅通過 轉入兩種酶的基因：八氫番茄紅素 合成酶（PSY）和八氫番茄紅素脫氫酶 （crt I），糧食中可以合成β-胡蘿卜素 的途徑就能被重新激活，β-胡蘿卜 素就能因此在被食用的胚乳中製造 並積累。

 

Fig 1: Pathway overview: carotenoid biosynthesis begins with a small (C5) compound, isopentenyl-diphosphate (IPP) and its isomer dimethylally-diphosphate (DMAPP). Chain elongation by C5 units leads to the formation of the C20-compound geranylgeranyl-diphosphate (GGPP). GGPP is a precursor that can enter several biosynthetic routes, as indicated. The head-to-head condensation of two GGPP molecules produces the first,colourless carotene, phytoene. A series of desaturation reactions lead to the coloured chromophore of lycopene, and subsequent cyclization reactions produce the β- and ε-ionone rings. Oxygenation (hydroxylation, epoxidation) reactions lead then to xanthophylls. Several known pathways branch off at this point, forming biologically important molecules, such as abscisic acid and strigolactones

(http://www.goldenrice.org/Content2-How/how1_sci.php)

 

所有跟帖： 

• The science behind Golden Rice -26484915- ♂ (15407 bytes) () 09/04/2014 postreply 16:39:51

• 不要說絕對。便宜的辦法誰出錢？ -26484915- ♂ (0 bytes) () 09/05/2014 postreply 08:05:07

• 一篇情緒性的文章。他的結論沒有事實支持。 -26484915- ♂ (0 bytes) () 09/04/2014 postreply 17:36:06

• 與我說的有什麽矛盾嗎？外源性的基因有害嗎？ -26484915- ♂ (54 bytes) () 09/04/2014 postreply 17:08:06

• 你還是沒有回答我的問題。 -26484915- ♂ (122 bytes) () 09/04/2014 postreply 17:29:40

• 你這種假設有根據嗎？ -26484915- ♂ (75 bytes) () 09/04/2014 postreply 17:31:57

• 理論總是在現實的理想化上產生的，再用來指導實際， 有時候會產生災難性的後果 -littlecat8- ♂ (443 bytes) () 09/04/2014 postreply 18:06:12