The Research On Homoeolgous Expression Pattern In Hybrid Populations Of(Carassius Auratus Red Var.× Cyprinus Carpio) And (Ctenopharyngodon Idellus × Megalobrama Amblycephala),Evolution Research In Culter Alburnus

In the research of evolution,the origin of speices always is the interesting flied.In consensus view,the generated of new populations and species were not only from the external environment factor,but also the new combination of different genomes.The supplement material of evolution is from hybridization and polyploidy.The one of important subjects in evolution studies is about the research on the homoeologs chromosomes in hybrids.As we know,in the theory of systematic biology,homology is the existence of shared ancestry between a pair of structures,or genes,in different species.In genetics,homology is a relationship defined between structures or DNA derived from a common ancestor.The studies of orthology and paralogy are the hot flied of evolution in hybrids.This research is focus on the species in nature and the hybrids by the artificial breeding,the using technology is about the next generation sequencing.The homoeologs expression in different stages of development is our research target.The homoeologs expression level of different hybrid populations was detected by some methods.These researches help us understanding of the effect of hybridization and polyploidy to the speciation.As we know,the change of trait was always made by the regulation of expression level from the hybridization and polyploidy in hybrids.The changes on character of hybrids sometimes show the rapid and random.When the breeding of hybrids were under way,the some different traits were observed in the hybrid populations.We study the expression level pattern in hybrid for the purpose of existence of a large number of individuals in these populations.The evolution in species will not be accompanied with the change of base in genome sequences but also the change on the epigenetic level.Compared with the mutation in base,the change of epigenetic always exhibited the rapid.The introduction of my studies is as follow:1.We collected liver tissue of culter alburnus and megalobrama amblycephala as the research material.By using extracting RNA,illumina sequencing and analyzing,we obtained the coding sequences of two species in transcriptome platform.After the annotation,we collected the information of liver transcriptome in the two species.At the same time,we downloaded the data of Cyprinidae fish zebrafish and common carp annotated coding sequences from the database of Esemble.By using the methods of bioinformatics,we screen the CDS region of genes in transcriptome sequences by comparing with orthologys in three species.Based on the above analysis,we calculated the divergent of two species by the parameter of ka/ks.The result suggest that the four positive selective genes were detected in the compared between zebrafish and Wuchang bream,zebrafish and topmouth culter.These results help us understanding of event of the early divergent in Cyprinidae fish.The analysis of the function of the four positive selective genes will urge us to investigate the special environment in origin of species.2.Under the same breeding condition,we collected the grass carp,Wuchang bream and their triploid hybrid offsprings for the purpose of expression level of triploids.The technology of next generation sequencing have been proved as the rapidly ways to detect the expression level.The triploid individual possesses the two sets of grass carp chromosomes and one set of wuchang bream chromosomes.Based on above results,we pay close attention to the total expression level and homoeologs expression level for research on the epigenetic regulation of gene expression.The total expression level is detected by the software of RSEM and the homoeologs expression level is calculated by the program of bowtie2-samtool-cufflink.Based on the relatively expression lever between the inbred parents and hybrid offsprings,we established the expression level distribution pattern(downregulation,upregulation,BSB-expression level dominance,GC-expression level dominance,Mid-parents and No change).These help us understanding the expression bias in the triploid.the paternal BSB-expression bias is exhibited in the triploids.At the same time,we detect the existence of dosage effect result from the two sets of GC-chromosome.The material of triploid is interested for us to study the silencing mechanism.3.Our research is not only using the next generation sequencing to detect the homoeologs expression level,but also the species-specific SNPs primers are used for assessing the expression level.We collect the three tissues(muscle,liver and goand)to study the tissue-specific expression level.The growth genes(igf1,igf2,ghr,tab1,bmp4,vasa and mstn),and slc25a20 and slc10a3 are the key regulated development genes.We used the species-specific primers to detect the R/C homoeologs expression level in hybrid populations by the real-time RT-PCR.Analysis of mstn gene indicated the existence of R and C homoeolog expression silencing in muscle of G and F18,while C homoeolog expression silencing of that gene was detected in liver of F1 and F18.Furthermore,a comparative study based on CT ratio of R homoeolog to C homoeolog exhibited the existence of the different degrees of maternal expression bias in three hybrids.Additionnally,the deviation of the homoeolog expression bias in allotetraploid F18 larger than that in diploid G and F1 revealed that both of hybridization and polyploidy accelerate the epigenetic change.Our results imply that a bottleneck of instability will be available for adapting and joining the evolutionary fray as efficient competitors of their original diploid parents.4.Homoeologous chromosomes in hybrids influence characteristics that are associated with major changes at the genetic and epigenetic levels.Here,we explored phenomenon of silencing transcripts,novel transcripts and the homoeologous expression bias in different hybrid populations.Furthermore,homoeolog expression bias revealed different degrees of trait differentiation in different hybrids.At present,homoeolog expression analysis in hybrids of various ploidy provides an in-depth understanding of molecular mechanisms underlying the hybridization and polyploidy processes.Moreover,understanding the regulation of individual expression levels of growth genes may be as important as understanding its heterosis.