中华齿刺甲和黄粉虫抗冻蛋白基因3'-UTR序列的克隆及其差异性比较

Cloning and Sequence Comparison of 3'-UTRs of Antifreeze Protein Genes from Oodescelis chinensis and Tenebrio molitor

真核基因的3’-非翻译区(untranslated region,UTR)对转录后调控具有重要作用。抗冻蛋白(antifreeze protein,AFP)是变温生物抵御环境低温胁迫的重要物质。昆虫抗冻蛋白基因3’-UTR的序列变异性可能与昆虫的环境适应性相关,为验证这一假设,通过3’-末端快速扩增法(3’-RACE)克隆了生境条件极端差异的拟步甲科昆虫中华齿刺甲(Oodescelis chinensis)和黄粉虫(Tenebrio molitor)成虫及幼虫的抗冻蛋白基因(afp)的3’-UTR,并进行序列比较。结果表明,通过克隆获得两种昆虫的众多afp 3’-UTR c DNA序列。生境条件单一的黄粉虫afp 3’-UTR的长度几乎没有变异,变异系数为零,序列一致性达90%以上,而野生昆虫中华齿刺甲的afp 3’-UTR序列在长度和组成上变异巨大,长度变异系数为0.26~0.32,序列一致性只有29%。黄粉虫afp3’-UTR序列含有两个AAUAAA多聚腺苷酸化信号和两个富U/GU元件;中华齿刺甲afp 3’-UTR一般仅含一个AAUAAA信号和一个富U/GU元件,有些序列没有可识...

3'-untranslated regions(3'-UTRs) in eukaryotic genes play important roles in posttranscriptional regulation of gene expression. Antifreeze protein(AFP) is one of the important substances that help ectotherms resist low temperature stress. The variability of 3'-UTR sequences of insect antifreeze protein genes may relate to environmental adaption of insect. To test this hypothesis, 3'-UTRs of afps from adults and larvae of beetles Oodescelis chinensis and Tenebrio molitor that have quite different inhibit conditions were cloned by using rapid amplification of c DNA 3' ends(3'-RACE). These sequences were analyzed and compared between the two insects.The results showed that numerous 3'-UTR c DNAs of afps from these insects were obtained. The length of afp3'-UTRs from Tenebrio molitor which lives in less changed environment was invariant with coefficient of variation of zero, and the sequence identity was 90%. Whereas, afp 3'-UTRs from Oodescelis chinensis which lives in wild field with changeable environment showed great variation both in length and in sequence composition, the coefficient of variation in length ranged from 0.26 to 0.32, and the sequence identity was only 29%. 3'-UTRs from T. molitor afps contained two AAUAAA polyadenylation signals and two U/GU rich elements; while afp 3'-UTRs from O. chinensis usually contained one AAUAAA signal and one U/GU rich element. Some of the sequences showed no recognizable AAUAAA signal and U/GU rich element. In conclusion, cloning and sequence analysis of afp 3'-UTRs from two insects which have quite different living environmental conditions showed that sequence variability of 3'-UTRs of insect antifreeze protein genes is related to the variability of their living environments.Environmental selective pressure promotes evolution of antifreeze protein genes and their 3'-UTRs.