Espinoza Ingrid, Gomez Christian R, Galindo Mario, Galanti Norbel
Programa de Biología Celular y Molecular, Instituto de Ciencias Biomédicas (I.C.B.M.), Facultad de Medicina, Universidad de Chile, 8389100 Independencia, Santiago, Chile.
Gene. 2007 Jan 15;386(1-2):35-41. doi: 10.1016/j.gene.2006.07.028. Epub 2006 Aug 17.
In higher eukaryotes, histone gene expression is coupled to DNA replication during the S-phase of the cell cycle. This coupling is primarily controlled at the transcriptional level. Considering the basal phylogenic position of platyhelminthes in the bilateria phylum, we have cloned a partial sequence of the histone H4 gene of Mesocestoides corti and studied its expression during the post larval development of this endoparasitic platyhelminth. In in vitro trypsin-induced tetrathyridia development to segmented adult worm, we found that histone H4 is expressed concomitantly with DNA synthesis throughout all stages of development. DNA synthesis and histone H4 mRNA levels were sharply increased at 24 h after inducing development. Afterwards, tetrathyridia grew in length from days 4 to 12 of development as proliferative cells gradually increased in number. Consequently, during this period of development histone H4 mRNA levels were upregulated. Taken together these results suggest that a replication-dependent expression pattern of histone H4 occurs in ancient bilateria, such as platyhelminthes, as previously observed in higher eukaryotes.
在高等真核生物中，组蛋白基因的表达与细胞周期S期的DNA复制相关联。这种关联主要在转录水平上受到控制。考虑到扁形动物在两侧对称动物门中的基础系统发育地位，我们克隆了猬迭宫绦虫组蛋白H4基因的部分序列，并研究了其在这种内寄生扁形动物幼虫后发育过程中的表达。在体外胰蛋白酶诱导四盘蚴发育为节段性成虫的过程中，我们发现组蛋白H4在整个发育阶段都与DNA合成同时表达。诱导发育后24小时，DNA合成和组蛋白H4 mRNA水平急剧增加。此后，随着发育第4天到第12天四盘蚴长度的增长，增殖细胞数量逐渐增加。因此，在这个发育阶段，组蛋白H4 mRNA水平上调。综合这些结果表明，如先前在高等真核生物中所观察到的那样，组蛋白H4的复制依赖性表达模式发生在古老的两侧对称动物，如扁形动物中。
