请教畸胎瘤和四倍体补偿

zhaoyan1983

请教为什么用畸胎瘤实验和四倍体补偿实验可以用来证明ES的全能性？希望高手们可以说的详细一点，我是新手，说的太简略我理解起来比较吃力，谢谢！) m% L8 f( \1 \5 K
另外畸胎瘤在有关ES的实验中主要是用来证明什么的？

flydayzhu

畸胎瘤实验的话是说明ES能够分化成三个胚层的细胞，具有多向分化能力，四倍体互补的话是用四倍体支持ES的发育，使其能发育成一个完整的个体，证明其具有全能性

zhaoyan1983

回复 2# flydayzhu ! a# b9 B. c$ z8 v: l7 B

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3 l3 f" e: G. i' y% n+ j    能说的具体点吗

lixiaodong

Nagy和Rossant的一篇较早文章对四倍体补偿实验的原理和背景资料有较好的介绍。Introduction部分就讲解了很多问题。参考文献里也有很好的早期工作。另篇93年PNAS文章介绍了ES细胞的tetraploid complementation（是关于ES的类似实验的较早报道，）0 r5 g5 t  y/ T8 [% z7 V
Embryonic stem cells alone are able to support fetal development in the
) |) f( d% I# j8 Hmouse
7 U! E: `! X% mANDRAS NAGY1-2. ELEN GOCZA2. ELIZABETH MERENTES DIAZ2. VALERIE R. PRIDEAUX1; F5 o$ `6 }/ }, S
ESZTER IVANYI2. MERJA MARKKL'LA2 and JANET ROSSANT1 3% s9 ?0 U8 a, K3 Y1 f4 W
Introduction
2 `, Q4 S% c& R7 T" j1 c6 X; v! wMouse embryonic stem (ES) cells are the most7 X! e0 \6 ~: i9 Q' q# `
pluripotent cultured animal cells known. When ES cells
7 I6 m. b/ c2 J/ ^& o$ j3 Mare injected into host blastoeysts they are capable of
4 {  C  ^* [9 k) K( j; q" N/ scontributing to a wide variety of somatic tissues and the! V" ?& D. B9 W4 c' O
eermline in resulting chimeras. However, their contributions4 V5 [  B/ L; r3 H7 _2 V
to different lineages are not necessarily equal.6 @% |* T& Z  B7 g  P! D
ES cells are able to contribute extensively to the fetus
1 b0 a6 k; E' P0 |" ]: Sand extraembryonic mesoderm. but their ability to! K8 j6 W. p+ Z) z8 V' c6 H% i* G
colonize primitive endoderm and trophectoderm derivatives
" j% L3 j1 K; d8 B- _is poor (Beddington and Robertson. 1989). ES
* c$ F; N7 x' z9 r; ]. Tcells may thus have restricted potential in certain) }9 f4 D: N6 p6 q. ]
extraembryonic lineages, suggesting that functional
" J, _4 m2 a1 x/ ]- w' d% j5 Xcomplementation by host cells is required during early: S+ d% G  I4 E* p
staues of development in chimeras. In this study, we9 p7 P! V8 t. J3 m
asked whether this functional complementation is
. M  e' i2 D5 I2 S# i" i1 Wrequired at later stages within the embryonic lineages,( l1 |7 J) F& \4 E: H- B: y
or whether ES cells can support complete fetal and
- b# i1 n" t# d# epostnatal development. To test the full developmental
' o3 y7 p3 U: D! I6 Lpotential of ES cells, they were aggregated with5 b2 E% g& Q5 j7 |$ p
cleavage stage embryos that had been placed at a
+ q! F: z0 Z1 U. n# edevelopmental disadvantage by doubling their ploidy.
2 S& d4 _9 y8 V( h  BThe development of these aggregates was compared
$ t. m* D8 g6 E9 H9 H  fwith similar aggregates made with ICV1 cells.
: K9 u8 }  \& M! p; T2 ~0 B8 c/ k3 `Tetraploid embryos can implant at high frequency,
' ~# V$ f* c7 i+ @$ ?( l, q  [1 mbut rarely form embryonic structures (Snow. 1975.
9 h0 _6 w" a/ u  E1 }- e+ m1976; Tarkowski et a!. 1977). although occasional
, C$ P9 J( q: P+ f" ?7 C& n( ]) M; Kembryos proceed through organogenesis and reach
) O9 J" ~# b0 T" z! C, gterm (Snow. 1973). Postnatal survival of tetraploid2 ?* J! _& M) r8 U5 H5 S: X- `$ s
embryos has not been reported. If blaslomere stage
- F( Z" s& |- s6 O' J: Q: l4 ^tetraploid embryos are aggregated with diploid embryos,
, Y3 [/ M7 H* D: ^' Dthe tetraploid cells are selected against durinti, X; ]& Q! B5 @0 _. L# z3 R5 z
development of fetal tissues in most cases (Lu and+ t$ j; f* w5 I/ y
Markert. 19X0). but persist in extraembryonal membranes
) Z: r: \- r; q' V; ]' o(Tarkowski et al. 1977). Thus, we reasoned thai
! v# h" P. [! u7 _! xtetraploid cells might complement the deficient4 i2 M# R  I$ r3 |
extraembryonal differentiation of ES cells while allowing; Z7 w$ m( U  }6 J* D( v8 v: v
full expression of their potential for fetal development.! I! V: u4 S' n/ [: ]3 z) F
Production of live fetuses that were entirely ES in$ w! l7 z: ?. L5 b, h, \( h# X
genotype was achieved from such aggregates, showinu, Y2 s1 V( O9 S
that ES cells have the potential to form all fetal cell
  h- u* o9 a" x0 X) WI incases.

cony

粗略来说，四倍体只能发育成胎盘组织，不能发育成个体，而将ES注入四倍体胚胎后，如能产生个体，这个个体是完全从ES发育而来，从而证明ES的发育全能性。

懵懂干细胞

回复 5# cony * h( p- p1 n, A& a) z& V. ?
简短明了！谢谢

flydayzhu

回复 3# zhaoyan1983 - f6 t$ z4 y; ~- v; O

& o7 N1 C2 x4 K0 h7 {3 r! s) g, Z( B
7 ?' v3 Q8 N; x; y* B# W    关于四倍体互补，可参考http://www.stemcell8.cn/viewthre ... 6%CC%E5%BB%A5%B2%B9

zhaoyan1983

回复 2# flydayzhu / G) p: r3 h- ]' c; i0 O' r
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  X6 ^4 g- W3 y3 g& N' R  B- p    那畸胎瘤实验呢？一定要让ES成瘤才能证明它能够分化成三个胚层吗？我只是不明白为什么很多实验都涉及到畸胎瘤的部分，有点晕。

flydayzhu

回复 8# zhaoyan1983
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( b- }4 o% G1 [7 M! x/ q: q1 ]  s4 ^! q    体内注射后会形成畸胎瘤，畸胎瘤在体内能分化形成来自三个胚层的多种分化细胞，说明其具有亚全能性，因为这样才被拿来证明全能性，全能性的一个特点是能够分化成三个胚层的衍生物

张也行

这两个实验都是证明ES的多能性的。所谓多能性就是说ES必须要能分化为各种胚层才行，就像体内的ICM将来分化整个个体一样。他们具体的机制前面说的很好了，我就不赘述了。) Q. d- z; \' Z1 k& ?: d2 h: C! |

/ X" [! D% J& y2 ?' {/ R+ p畸胎瘤和四倍体补偿都是证明多能性的方法，但是显然后者更严谨一些，更有说服力一些。还可以用已经建立的体外诱导为多种细胞的方法证明多能性，但严谨性又比畸胎瘤弱一些，因为体外诱导的细胞种类有限。还有一种证明多能性的方法就是嵌合体（特别是生殖性嵌合）了。比畸胎瘤更严谨，比四倍体弱些。但一般做成生殖性嵌合体就足够了。