Zafarullah M, Olsson P E, Gedamu L
Department of Biological Sciences, University of Calgary, Alberta, Canada.
Biochim Biophys Acta. 1990 Jul 30;1049(3):318-23. doi: 10.1016/0167-4781(90)90104-a.
Exposure of a trout gonadal fibroblast (RTG-2) cell line to ZnCl2, CdCl2 and CuCl2 resulted in differential levels of accumulation of metallothionein (MT) mRNA. ZnCl2 being the most effective agent induced MT mRNA in 3 h, with 172-fold induction after 48 h and continued accumulation up to 144 h. Following CdCl2 treatment, mRNA could be detected after 24 h, reaching peak levels at 72 h. Furthermore, trout MT mRNA could be detected up to 8 days after withdrawal of extraneous ZnCl2. Using a novel technique of primer extension and DNA sequencing with total RNA as template, specificity of the trout MTa and MTb gene-specific primers was established. Primer extension studies revealed a higher response of MTa to ZnCl2 and CdCl2 compared to MTb. Insensitivity of MT mRNA induction to cycloheximide suggested that induction by the metals was independent of de novo protein synthesis. However, simultaneous exposure of cells to actinomycin D and metals completely inhibited MT mRNA synthesis implying control at the transcriptional level.
将虹鳟性腺成纤维细胞（RTG - 2）细胞系暴露于氯化锌、氯化镉和氯化铜中，导致金属硫蛋白（MT）mRNA的积累水平存在差异。氯化锌是最有效的试剂，在3小时内诱导MT mRNA表达，48小时后诱导倍数达172倍，并持续积累至144小时。经氯化镉处理后，24小时可检测到mRNA，在72小时达到峰值水平。此外，在去除外源氯化锌后长达8天仍可检测到虹鳟MT mRNA。以总RNA为模板，采用引物延伸和DNA测序新技术，确定了虹鳟MTa和MTb基因特异性引物的特异性。引物延伸研究表明，与MTb相比，MTa对氯化锌和氯化镉的反应更高。MT mRNA诱导对环己酰亚胺不敏感，表明金属诱导与从头合成蛋白质无关。然而，细胞同时暴露于放线菌素D和金属中会完全抑制MT mRNA合成，这意味着在转录水平上受到调控。
