脊椎动物身体计划的多样性令人眼花缭乱,然而,他们的许多共同点令人惊叹。从最冷的气候到最温暖的气候,脊椎动物几乎居住在地球的每个地方。他们通过游泳运动,飞行,走路,滑行,或者攀爬,或这些行为的组合。它们存在许多不同的大小,从最小的青蛙,鱼和蜥蜴长颈鹿,大象,还有蓝鲸.尽管存在这些差异,脊椎动物遵循一个非常相似的蓝图来建立他们的身体计划。在完成原肠胚形成所需的相对较小的时间内,三个胚层的过程,外胚层,中胚层,内胚层被创造出来,胚胎也产生它的身体轴,同时被图案化。对于这个轴的长度,区分颈部与胸腔或躯干与骶骨的基因是Hox基因。在脊椎动物中,在生物体中维持这组基因存在进化压力。在过去的几十年里,关于确保这些基因沿主体轴适当表达的调节机制,已经学到了很多。尽管已经学到了很多东西,但遗传功能仍在继续探索。关于Hox蛋白用于转录调控特异性的辅因子的身份,或者哪些下游靶标和途径对图案化事件至关重要,尽管有明显的例外。该领域的当前工作表明,Hox基因在指导早期模式事件后很长时间内继续在许多器官中发挥作用。希望持续的研究将阐明有关这一重要且保守的转录调节因子组使用的机制的剩余问题。
The diversity of vertebrate body plans is dizzying, yet stunning for the many things they have in common. Vertebrates have inhabited virtually every part of the earth from its coldest to warmest climates. They locomote by swimming, flying, walking, slithering, or climbing, or combinations of these behaviors. And they exist in many different sizes, from the smallest of frogs, fish and lizards to giraffes, elephants, and blue whales. Despite these differences, vertebrates follow a remarkably similar blueprint for the establishment of their body plan. Within the relatively small amount of time required to complete gastrulation, the process through which the three germ layers, ectoderm, mesoderm, and endoderm are created, the embryo also generates its body axis and is simultaneously patterned. For the length of this axis, the genes that distinguish the neck from the rib cage or the trunk from the sacrum are the Hox genes. In vertebrates, there was evolutionary pressure to maintain this set of genes in the organism. Over the past decades, much has been learned regarding the regulatory mechanisms that ensure the appropriate expression of these genes along the main body axes. Genetic functions continue to be explored though much has been learned. Much less has been discerned on the identity of co-factors used by Hox proteins for the specificity of transcriptional regulation or what downstream targets and pathways are critical for
patterning events, though there are notable exceptions. Current work in the field is demonstrating that Hox genes continue to function in many organs long after directing early
patterning events. It is hopeful continued research will shed light on remaining questions regarding mechanisms used by this important and conserved set of transcriptional regulators.