Studies On Cloning And Adaptive Evolution Of The Hemoglobin Gene Of The Mandarin Vole And Brandt's Vole

In the environment of low O₂?hypoxia?and high CO₂ for a long time,the cardiovascular system of the Subterranean rodents has undergone corresponding adaptive evolution,that is,by improving the function of blood oxygenation,enhancing cardiac reserve and improving the ability of tissue uptake and utilization of oxygen.Hemoglobin?Hb,HGB?is a complex allosteric protein containing iron in the red blood cells of vertebrates.It is composed of heme and globin.Its main function is to transport oxygen and carbon dioxide and maintain blood acid-base balance.At present,there is a lack of research on the relationship between the structure of hypoxic hemoglobin and the evolutionary relationship between hypoxic adaptation and evolution of underground rodents.In this study,Lasiopodomys mandarinus was taken as the control object,with L.brandtii as the control.The cloning of two hemoglobin genes and their adaptive evolution were studied in order to reveal the adaptive evolution of underground rodents hemoglobin to hypoxia environment.Use some biological software,such as Oligo7.0,Bioedit,Clustal W,Mega7.0,Paml4 d,using the method of comparative genomics and bioinformatics.The main results are as follows:1)The whole gene sequence of the family of Lasiopodomys mandarinus and L.brandtii hemoglobin was cloned by one generation sequencing technique,with 5 genes of alpha subunit and beta subunit,and alpha subunits mainly include 5 genes,such as HBZ?1685bp?,HBA-T1?700bp?,HBA-T2?700bp?,HBQ1?647bp?and HBQ2?647bp?,and beta subunits mainly includes 5 genes: HBE?1307bp?,HBE/HBG?1664bp?,HBG?1393bp?,HBB-T1?1141bp?and HBB-T2?1141bp?.The gene length of the alpha subunit and the beta subunit of the Lasiopodomys mandarinus and L.brandtii are the same.2)The structure of alpha globin gene and beta globin gene in Lasiopodomys mandarinus and L.brandtii were identical with two generation sequencing data and human exons,in which the structure of alpha globin gene cluster was 5 '-HBZ-HBA-T1-HBQ-T1-HBA-T2-HBQ-T2-3,and the structure of beta globin gene cluster was 5'-HBE-HBE/HBG-HBG-HBB-T1-HBB-T2-3.3)Phylogenetic analysis was carried out using the hemoglobin gene sequences of 11 species.The subterranean rodents hemoglobin gene is relatively conservative in evolution,and there is no convergent evolution.4)The results of selective pressure analysis showed that the positive selective mutations were occurring in the hemoglobin of subterranean rodents,and the positive selective loci of the HBA1,HBB1 and HBG genes of the Nannospalax galili were 12 K,17G,87 A,113I,and the positive selective loci of HBA1,HBB1 and HBG genes of Heterocephalus glaber were 57 K,24V,HBB1,etc.13 S,88S,24 V,117T,74 L,136I are all located in the A,B,E,F and H spiral regions of globin,which may be related to the hypoxia adaptation of the Nannospalax galili and the Heterocephalus glaber.No positive selection sites were detected in the hemoglobin gene family of Lasiopodomys mandarinus,which may be related to their short adaptation time or short evolutionary time.5)The results of hemoglobin amino acid sequence alignment showed that 58 and 59 site of the HBA1 gene amino acid sequences of the Lasiopodomys mandarinus were mutated from histidine to arginine.It is presumed that it may be related to the change of oxygen affinity of hemoglobin.In conclusion,the subterranean rodents hemoglobin gene has an adaptive evolution to its subsurface hypoxia life,which is specific to the multiple loci of the HBB1 and HBG genes of the Nannospalax galili and the Heterocephalus glaber,and these mutation sites are located at the contact site between the hemoglobin subunits and the heme junction area,and may play a heavy role in the hypoxia adaptation.The evolutionary time of Microtus fortis was short.58 and 59 of the amino acid sequences of HBA1 globin were mutated.The length and structure of the hemoglobin gene of the Lasiopodomys mandarinus and L.brandtii were the same.The phylogenetic analysis failed to find the convergence and evolution of the ground mouse,and its topological structure was the same as that of the Cytb.