维甲酸对斑马鱼中枢神经系统及软骨发生的影响

脂溶性的维甲酸可通过固醇类激素作用途径启动ＨＯＸ族及ＬＩＭ族调节基因,进而影响脊椎动物胚胎的形态发生、再生组织的分化。本文通过不同浓度系列表明,维甲酸对早期鱼胚发育的影响程度依赖于其作用浓度与作用时间,１０＾－６￣１０＾－７Ｍ的浓度范围为作用敏感区。维甲酸对中枢神经系统前后轴上的影响尤其显著,主要表现为小头畸形、无眼或无心脏。作者首次用Ｂｒｄｕ－Ａｎｔｉ－Ｂｎｄｕ标记处于Ｓ期的细胞核表明,ＲＡ作用     

Mechanics as a Means of Information Propagation in Development

New research demonstrates that mechanics can serve as a means of information propagation in developing embryos. Historically, the study of embryonic development has had a dichotomy between morphogens and pattern formation on the one hand and morphogenesis and mechanics on the other. Secreted signals are the preeminent means of information propagation between cells and used to control cell fate, while physical forces act downstream or in parallel to shape tissue morphogenesis. However, recent work has blurred this division of function by demonstrating that mechanics can serve as a means of information propagation. Adhesive or repulsive interactions can propagate through a tissue as a wave. These waves are rapid and directional and can be used to control the flux of cells through a developmental trajectory. Here, two examples are reviewed in which mechanics both guides and mediates morphogenesis and two examples in which mechanics intertwines with morphogens to regulate cell fate.     

Characterization of Amphioxus AmphiVent, an evolutionarily conserved marker for chordate ventral mesoderm

Structure and developmental expression are described for amphioxus AmphiVent, a homolog of vertebrate Vent genes. In amphioxus, AmphiVent-expressing ventral mesoderm arises at midneurula by outgrowth from the paraxial mesoderm, but in vertebrates, Vent-expressing ventral mesoderm originates earlier, at the gastrula stage. In other embryonic tissues (nascent paraxial mesoderm, neural plate, endoderm, and tailbud), AmphiVent and its vertebrate homologs are expressed in similar spatiotemporal domains, indicating conservation of many Vent gene functions during chordate evolution. The ventral mesoderm evidently develops precociously in vertebrates because their relatively large embryos probably require an early and extensive deployment of the mesoderm-derived circulatory system. The vertebrate ventral mesoderm, in spite of its strikingly early advent, still resembles the nascent ventral mesoderm of amphioxus in expressing Vent homologs. This coincidence may indicate that Vent homologs in vertebrates and amphioxus play comparable roles in ventral mesoderm specification.     

Expression of Brachyury-like T-box transcription factor, Xbra3 in Xenopus embryo

The Xenopus Brachyury-like Xbra3 gene is a novel T-box gene that is closely associated with Xenopus Brachyury. The expression pattern of Xbra3 during development is similar to that of Xbra. During gastrulation Xbra3 is expressed in the marginal zone, with a gradient of increasing expression from ventral to dorsal. In the early neurula stage Xbra3 is expressed in the notochord and posterior mesoderm, but by the tailbud stage its expression is restricted to the forming tailbud and the posterior portion of the notochord.