Signals from trunk paraxial mesoderm induce pronephros formation in chick intermediate mesoderm.
Signals from trunk paraxial mesoderm induce pronephros formation in chick intermediate mesoderm.
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来自躯干近轴中胚层的信号诱导雏鸡中间中胚层中原肾的形成。
DOI：
10.1006/dbio.2000.9623
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发表时间：
2000
期刊：
影响因子：
--
通讯作者：
Schoenwolf,GC
中科院分区：
文献类型：
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作者：
Mauch,TJ;Yang,G;Wright,M;Smith,D;Schoenwolf,GC
我们使用Pax-2 mRNA表达和Lim 1/2抗体染色作为鸡中间中胚层（IM）向原肾组织转化的标志物，并使用Lmx-1 mRNA表达作为中肾的标志物。原肾标记强烈表达尾侧第五体节的阶段9。为了确定是否由邻近组织诱导的原肾，如果是的话，以确定诱导组织和诱导的时间，我们显微解剖培养中发育的鸡胚的一侧，然后孵育3天。未受干扰的对侧作为对照。大多数胚胎平行于喙尾轴之间的躯干近轴中胚层和IM阶段8前开发的控制侧上的原肾。在第9阶段后操作的胚胎在两侧都发育了原肾结构，但在切割侧尾侧原肾延伸减弱。这些结果表明，一个中间的信号是必要的原肾的发展，并显示该信号是在一个吻尾序列传播。在卵内培养3天的操作胚胎中，实验侧的中肾和前肾未能发育。与此相反，胚胎之间的脊索和躯干近轴中胚层切割形成原肾结构两侧，无论在该阶段进行操作，表明信号来自近轴中胚层（PM），而不是从轴向中胚层。该切割也用作PM和IM之间的切割的对照，并且表明在先前的实验中信号传导本身被阻断，而不是原肾或中肾前体细胞从原条的迁移。另外的对照实验排除了对来自侧板中胚层、外胚层或内胚层的信号的需要。为了确定在没有与更多的喙部组织接触的情况下，第五体节尾侧的躯干近轴中胚层是否保持其诱导能力，将胚胎横切。那些横切低于预期水平的第五体节表达Pax-2的吻侧和尾侧隔离，而胚胎横切吻侧到这个水平表达Pax-2的尾侧隔离。因此，建立Pax-2表达和原肾形成的正常模式不需要吻侧信号。为了确定近轴中胚层是否足以诱导原肾，将7期或更早的鸡侧板中胚层与尾部8期或9期鹌鹑体节在胶原凝胶中共培养。Pax-2在21/25的鸡胚组织中表达。将4期或5期鹌鹑淋巴结等时移植到鸡尾原条上，可产生异位体节。这些体节诱导了侧板中胚层的异位原肾，而接受来自天然体节和异位体节的信号的IM形成了增大的原肾，并增加了Pax-2的表达。我们的结论是，信号从一个本地化的区域的躯干近轴中胚层都是必要的，足够的诱导的原肾从小鸡IM。目前正在进行研究，以确定诱导的分子性质。
We used Pax-2 mRNA expression and Lim 1/2 antibody staining as markers for the conversion of chick intermediate mesoderm (IM) to pronephric tissue and Lmx-1 mRNA expression as a marker for mesonephros. Pronephric markers were strongly expressed caudal to the fifth somite by stage 9. To determine whether the pronephros was induced by adjacent tissues and, if so, to identify the inducing tissues and the timing of induction, we microsurgically dissected one side of chick embryos developing in culture and then incubated them for up to 3 days. The undisturbed contralateral side served as a control. Most embryos cut parallel to the rostrocaudal axis between the trunk paraxial mesoderm and IM before stage 8 developed a pronephros on the control side only. Embryos manipulated after stage 9 developed pronephric structures on both sides, but the caudal pronephric extension was attenuated on the cut side. These results suggest that a medial signal is required for pronephric development and show that the signal is propagated in a rostral to caudal sequence. In manipulated embryos cultured for 3 days in ovo, the mesonephros as well as the pronephros failed to develop on the experimental side. In contrast, embryos cut between the notochord and the trunk paraxial mesoderm formed pronephric structures on both sides, regardless of the stage at which the operation was performed, indicating that the signal arises from the paraxial mesoderm (PM) and not from axial mesoderm. This cut also served as a control for cuts between the PM and the IM and showed that signaling itself was blocked in the former experiments, not the migration of pronephric or mesonephric precursor cells from the primitive streak. Additional control experiments ruled out the need for signals from lateral plate mesoderm, ectoderm, or endoderm. To determine whether the trunk paraxial mesoderm caudal to the fifth somite maintains its inductive capacity in the absence of contact with more rostral tissue, embryos were transected. Those transected below the prospective level of the fifth somite expressed Pax-2 in both the rostral and the caudal isolates, whereas embryos transected rostral to this level expressed Pax-2 in the caudal isolate only. Thus, a rostral signal is not required to establish the normal pattern of Pax-2 expression and pronephros formation. To determine whether paraxial mesoderm is sufficient for pronephros induction, stage 7 or earlier chick lateral plate mesoderm was cocultured with caudal stage 8 or 9 quail somites in collagen gels. Pax-2 was expressed in chick tissues in 21 of 25 embryos. Isochronic transplantation of stage 4 or 5 quail node into caudal chick primitive streak resulted in the generation of ectopic somites. These somites induced ectopic pronephroi in lateral plate mesoderm, and the IM that received signals from both native and ectopic somites formed enlarged pronephroi with increased Pax-2 expression. We conclude that signals from a localized region of the trunk paraxial mesoderm are both required and sufficient for the induction of the pronephros from the chick IM. Studies to identify the molecular nature of the induction are in progress.