Of Dinucleotide Ssr And The Silkworm Genome Of Trinucleotide Ssr Polymorphism

Microsatellites or simple sequence repeats(SSRs) which are simple,tandemly repeated one to six nucleotide sequence motifs are ubiquitous in eukaryotic genomes.They are very useful as genetic markers,and so applied to genetic mapping,detection of genetic diversity.identification of varieties and genotypes,gene tagging,QTL analysis,marker-assisted selection and so on.The silkworm,Bombyx mori.,is one of important economic insects and an ideal model organism for biologj' study. With four diverse silkworm strains the paper reports the polymorphism of dimer SSRS and trimer microsatellites in genomes,compares them and investigates the relation between their DNA loci number and genetic reliable information by PAGE-AgNO₃ staining.1 Research on DNA polymorphism of dimer SSRsWithin forty-eight samples representing four silkworm strains ,twenty-three dimer SSR primers are used for the PCR amplification of genomic DNA.and a total of 106 bands are amplified. On average,4.61 bands are amplified by each primer.In length the majority(62) of bands are 100bp 500bp,part(37) of bands are short of 100bp,and the minority(7) of bands are longer than 500bp.In them 63 bands with an average of 2.74 bands from each primer are polymorphic.The polymorphism of each strain is 36.5%(J115),6.9%(Yil6),36.05%(Dazao),38.3%(Yuhangerhua(jia)),and it among different strains is 59.43%.These show dimer SSRs can offer abundant polymorphism,furthermore, the polymorphism among different strains is more than among individuals in the same strain.lt is suggested that dimer SSRs are approximate an effective molecular technique for systematics study of the silkworm by cluster analysis.2 Research on DNA polymorphism of trimer SSRsWithin forty-eight samples representing four silkworm strains,twenty-three trimer SSR primers are used for the PCR amplification of genomic DNA,and a total of 107 bands are amplified.On average,4.65 bands are amplified by each primer. In length the majority(66)of bands are 100bp 500bp,part(29)of bands are short of 100bp,and the minority(12) of bands are longer than 500bp.In them 60 bands with an average of 2.61 bands from each primer are polymorphic.The polymorphism of each strain is 41.58%(J115))20.45%(Yil6),26.14%(Dazao),34.74%(Yuhangerhua(jia)),and it among different strains is 56.07%. These show trimer SSRs can offer abundant polymorphism,furthermore, the polymorphism among different strains is more than among individuals in the same strain. By cluster analysis it is suggested that dimer SSRs are an effective molecular technique for systematics study of the silkworm.3 Polymorphic comparison between dimer SSRs and trimer SSRsIn the paper three indexes(poiymorphism ratio,mean gene diversity and mean Shannon index)which are taken for standard evaluating polymorphism are calculated. Three indexes of dimer SSRs are 59.43%(polymorphism ratio),0.2199(mean gene diversity),0.3258(mean Shannon index),and of trimer SSRs are 56.07%(polymorphism ratio),0.1987(mean gene diversity),0.2960(mean Shannon index).Three indexes show the polymorphism of dimer SSRs is more than trimer SSRs together.4 The correlation between the number of two-kind SSR-loci and genetic reliable information We study the correlation between the number of two-kind SSR-loci and genetic reliable...