Kissinger J C, Raff R A
Indiana Molecular Biology Institute, and Department of Biology, Indiana University, Bloomington, IN 47405, USA.
Dev Genes Evol. 1998 Apr;208(2):82-93. doi: 10.1007/s004270050157.
We describe an evolutionary comparison of expression of the actin gene families of two congeneric sea urchins. Heliocidaris tuberculata develops indirectly via a planktonic feeding pluteus that forms a juvenile rudiment after a long period of larval development. H. erythrogramma is a direct developer that initiates formation of a juvenile rudiment immediately following gastrulation. The developmental expression of each actin isoform of both species was determined by in situ hybridization. The observed expression patterns are compared with known expression patterns in a related indirect-developing sea urchin, Strongylocentrotus purpuratus. Comparisons reveal unexpected patterns of conserved and divergent expression. Cytoplasmic actin, CyIII, is expressed in the aboral ectoderm cells of the indirect developers, but is an unexpressed pseudogene in H. erythrogramma, which lacks aboral ectoderm. This change is correlated with developmental mode. Two CyII actins are expressed in S. purpuratus, and one in H. erythrogramma, but no CyII is expressed in H. tuberculata despite its great developmental similarity to S. purpuratus. CyI expression differs slightly between Heliocidaris and Strongylocentrotus with more ectodermal expression in Heliocidaris. Evolutionary changes in actin gene expression reflect both evolution of developmental mode as well as a surprising flexibility in gene expression within a developmental mode.
我们描述了两种同属海胆肌动蛋白基因家族表达的进化比较。瘤海胆通过浮游摄食的长腕幼虫间接发育，在长时间的幼虫发育后形成幼体原基。红斑海胆是直接发育者，在原肠胚形成后立即开始形成幼体原基。通过原位杂交确定了这两个物种每种肌动蛋白同工型的发育表达。将观察到的表达模式与相关间接发育海胆紫球海胆已知的表达模式进行比较。比较揭示了保守和分歧表达的意外模式。细胞质肌动蛋白CyIII在间接发育者的反口外胚层细胞中表达，但在缺乏反口外胚层的红斑海胆中是一个未表达的假基因。这种变化与发育模式相关。紫球海胆中有两种CyII肌动蛋白表达，红斑海胆中有一种，而瘤海胆尽管与紫球海胆在发育上有很大相似性，但却没有CyII表达。瘤海胆和紫球海胆之间的CyI表达略有不同，瘤海胆的外胚层表达更多。肌动蛋白基因表达的进化变化既反映了发育模式的进化，也反映了发育模式内基因表达的惊人灵活性。
