Developmental regulation, induction, and embryonic tissue specificity of sea urchin metallothionein gene expression.
Developmental regulation, induction, and embryonic tissue specificity of sea urchin metallothionein gene expression.
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DOI：
10.1016/0012-1606(84)90212-4
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发表时间：
1984-04
影响因子：
2.7
通讯作者：
M. Nemer;Elizabeth C. Travaglini;Edson Rondinelli;Jill D'Alonzo
中科院分区：
文献类型：
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作者：
M. Nemer;Elizabeth C. Travaglini;Edson Rondinelli;Jill D'Alonzo
金属硫蛋白（MT）是一种半胱氨酸含量极高的小蛋白质（6-7 Da），其生物合成容易被重金属诱导，因此MT存在于海胆胚胎中。Zn ~（2+）诱导后，MT蛋白、0.8kb的MT mRNA和2.9kb的核RNA积累。MT mRNA的量在胚胎发生到pluteus阶段的过程中受到内在的调节：母体MT mRNA是poly（A）缺陷的，并且在受精后被聚腺苷酸化。新的MT mRNA开始积累之间的第七和第八次细胞分裂，间充质囊胚阶段达到最大值，原肠胚形成过程中减少，并再次上升，在早期pluteus阶段。在早期胚胎发生过程中，用Zn 2+“动物化”胚胎导致MT mRNA持续积累，达到正常量的25倍以上。MT mRNA是目前在大量的外胚层的pluteus，但几乎检测不到中胚层-内胚层组织部分。无论是pluteus或其分离的组织组分与Zn 2+的处理结果在中胚层-内胚层，但不是在已经MT mRNA富集的外胚层中的MT mRNA的积累的诱导。此外，MT基因在囊胚和原肠胚中的Zn 2+诱导的差异与MT基因表达在外胚层中维持在高水平而在中胚层-内胚层组织中维持在低水平的发育模式是一致的，然而，这是由Zn 2+优先诱导的。
Metallothionein (MT) is shown to be present in sea urchin embryos on the basis of its characteristic properties as a small protein (6–7 Da) of extraordinarily high cysteine content, whose biosynthesis is readily induced by heavy metals. Induction by Zn2+results in the accumulation of the cysteine-rich MT protein, a 0.8 kb MT mRNA and a 2.9 kb nuclear RNA. The amount of MT mRNA is regulated intrinsically through the course of embryogenesis to the pluteus stage: A maternal MT mRNA is poly(A)-deficient and is polyadenylated after fertilization. New MT mRNA begins to accumulate between the seventh and eighth cell cleavage, reaches a maximum at the mesenchyme blastula stage, decreases during gastrulation, and rises again in the early pluteus stage. “Animalizing” embryos with Zn2+during early embryogenesis causes a sustained accumulation of MT mRNA to levels greater than 25 times the normal amount. MT mRNA is present in high amount in the ectoderm of the pluteus, but is barely detectable in the mesoderm-endoderm tissue fraction. Treatment of either the pluteus or its isolated tissue fractions with Zn2+results in the induction of MT mRNA accumulation in the mesoderm-endoderm but not in the already MT mRNA-enriched ectoderm. Furthermore, differences in Zn2+induction of the MT gene in the blastula and gastrula are consistent with a developmental pattern in which MT gene expression is maintained constitutively at a high level in the ectoderm and at a low level in the mesoderm-endoderm tissues, which are, however, preferentially inducible by Zn2+.