Rodrigues Sofia, Santos Joana, Palmeirim Isabel
Instituto Gulbenkian de Ciência, Centro de Biologia do Desenvolvimento, Oeiras, Portugal.
Gene Expr Patterns. 2006 Oct;6(7):673-7. doi: 10.1016/j.modgep.2006.01.004. Epub 2006 Feb 20.
Segmentation consists on the progressive formation of repetitive embryonic structures, named somites, which are formed from the most rostral part of the presomitic mesoderm. Somites are subdivided into anterior and posterior compartments and several genes are differentially expressed in either compartment. This has provided evidence for the importance of establishing the anterior-posterior polarity within each somite, which is critical for the correct segmented pattern of the adult vertebrate body. Although all somites appear morphologically similar, fate map studies have shown that the first 4 somites do not give rise to segmented structures, in contrast to more posterior ones. Moreover, in several somitogenesis-related mutants the anterior somites are not affected while posterior somites present clear defects or do not form at all. Altogether these data suggest relevant differences between rostral and caudal somites. In order to check for molecular differences between anterior and posterior somites, we have performed a detailed expression pattern analysis of several Notch signalling related genes. For the first time, we show that the somitic expression pattern profile is not the same along the anterior-posterior axis and that the differences are not observed always at the same somite level.
体节形成包括重复性胚胎结构即体节的逐步形成，体节由前体节中胚层的最头端部分形成。体节可分为前部和后部区域，并且有几个基因在这两个区域中差异表达。这为在每个体节内建立前后极性的重要性提供了证据，这对于成年脊椎动物身体正确的分节模式至关重要。尽管所有体节在形态上看起来相似，但命运图谱研究表明，与更靠后的体节不同，最初的4个体节不会产生分节结构。此外，在一些与体节发生相关的突变体中，前部体节不受影响，而后部体节则出现明显缺陷或根本不形成。这些数据表明头端和尾端体节之间存在显著差异。为了检测前部和后部体节之间的分子差异，我们对几个Notch信号相关基因进行了详细的表达模式分析。我们首次表明，体节的表达模式沿前后轴并不相同，并且差异并不总是在相同的体节水平上观察到。
