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magy2006

木虫 (著名写手)

[求助] AGL6基因与VP16转录激活

有做拟南芥的同学吗?请教个问题啊:
说AGL6基因与VP16这个转录激活子结合后转入到拟南芥中,结果导致了拟南芥长出了原本没有的苞片组织,作者就说AGL6基因具有抑制苞片组织生长的作用,请问该怎么理解?谢谢
原文:Ectopic bracts and abnormal flowers in gAGL6::VP16 plants
To tease apart the confounding problems of misexpression,
we expressed a fusion of AGL6 to the strong transcriptional
activation domain from the viral transcription factor VP16
(Triezenberg et al., 1988; Cress and Triezenberg, 1991) in the
context of a 5.2 kb genomic fragment that included 2.6 and
0.8 kb of sequences upstream of the start codon and
downstream of the stop codon, respectively. The resulting
gAGL6::VP16 construct contains all important regulatory
elements for AGL6 expression located in both the promoter
region and the large first intron, which have been identified
recently (Schauer et al., 2009), suggesting identical expression
pattern of AGL6 in both wild-type and gAGL6::VP16
plants. In contrast to Pro35S:AGL6 and Pro35S:AGL6::EAR
plants, gAGL6::VP16 plants had normal rosette leaves
(Figure 4a). In addition, flowering time was normal (Table 1).
Striking phenotypes were seen in the inflorescences of
gAGL6::VP16 plants. Most flowers had ectopic organs on the
pedicel (Figure 4b,c). Usually the first flower, designated as
f1 in Figure 4(j), was normal. The second flower already
showed signs of abnormal development, with a filamentous
structure on the pedicel. Subsequently, the ectopic organs
became more fully developed, with sepaloid/bract/leaf-like
identity in the next two to three flowers. Bract-like features
included pointed tips, lack of petioles and delayed senescence
compared with sepals (Dinneny et al., 2004). At the
insertion point of the bract, there was a kink in the pedicel
(Figure 4h) and such a kink was also seen in the secondary
inflorescences (Figure 4i). The ectopic organs became
increasingly carpeloid- and then staminoid-like in laterdeveloping
flowers (Figure 4j–n). Finally, flowers were
completely replaced by staminoid bracts, which were produced
in spiral phyllotaxy (Figure 4d,e,j). The inflorescence
meristem itself was not consumed and stayed indeterminate
(Figure 4e). Together, these phenotypes suggest a role of
AGL6 both in suppressing outgrowth of the cryptic bract and
in organ identity.
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bullfrog325

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137167741: 金币+2, 小木虫交流,共同进步~~ 2013-08-02 08:25:12
说说我的看法, 其实我不太赞同文章的这个结论.
VP16融合的结果是让AGL6强力启动它控制的基因(抑制的, 促进的全都超表达). 所以文章描述苞叶长出的情况也有可能是本身被AGL6促进的基因在有VP16的情况下表达过了头造成的. 在这种情况下, 就不能说AGL6抑制苞叶生长了. 但是也不能说文章写错了, 因为原文用的是"suggest", 还是给自己留了后路的......
真要支持文章结论的话应该再补些实验, 如在长苞叶的突变体里面把AGL6 KO掉, 看看是否苞叶长出会被削弱.
2楼2013-08-01 23:10:13
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magy2006

木虫 (著名写手)

引用回帖:
2楼: Originally posted by bullfrog325 at 2013-08-01 23:10:13
说说我的看法, 其实我不太赞同文章的这个结论.
VP16融合的结果是让AGL6强力启动它控制的基因(抑制的, 促进的全都超表达). 所以文章描述苞叶长出的情况也有可能是本身被AGL6促进的基因在有VP16的情况下表达过了头造 ...

高人,我再请教一下,AGL6基因与VP16融合表达,与单独超量表达AGL6完全不一样么?我没做过这一块,对VP16这个东西不懂,我以为二者融合就是既超量表达AGL6,又强力激活其下游基因呢。谢谢回复。
3楼2013-08-02 08:11:33
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bullfrog325

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magy2006: 金币+10, ★★★很有帮助 2013-08-05 11:05:54
引用回帖:
3楼: Originally posted by magy2006 at 2013-08-02 08:11:33
高人,我再请教一下,AGL6基因与VP16融合表达,与单独超量表达AGL6完全不一样么?我没做过这一块,对VP16这个东西不懂,我以为二者融合就是既超量表达AGL6,又强力激活其下游基因呢。谢谢回复。...

VP16只负责下游基因转录的情况. 至于在这里AGL6-VP16是由前面的启动子负责表达范围的, 文章里用的是gAGL6:VP16, 说明是受AGL6自己的启动子控制. 也就是说本身不表达AGL6的细胞没事, 但是本身表达AGL6的细胞会表达AGL6-VP16. 相对来说如果换成35S:AGL6-VP16, 那么植物全身上下到处都有表达.
4楼2013-08-02 15:51:10
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magy2006

木虫 (著名写手)

引用回帖:
4楼: Originally posted by bullfrog325 at 2013-08-02 15:51:10
VP16只负责下游基因转录的情况. 至于在这里AGL6-VP16是由前面的启动子负责表达范围的, 文章里用的是gAGL6:VP16, 说明是受AGL6自己的启动子控制. 也就是说本身不表达AGL6的细胞没事, 但是本身表达AGL6的细胞会表达A ...

非常感谢哦。
5楼2013-08-05 11:07:55
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