Research Of YR-cohesion Chromosome Model By Signal-processing Method

Carrying DNA, the chromosome controls the heredity of a cell. The eukaryotic chromosome, which composes of DNA, protein and RNA, has a multi-level structure. Through this structure the genome DNA in a human cell, which is 1.8 meters long, is condensed to survive in a nucleus which length is only several microns. So the chromosome structure is full of mystery.In the fisrt level of chrosmome structure, 146bp DNA wrapped around a histone octamer and forms an 11nm nucleosome. Then many nucleosomes coil to form a 30nm solenoid. How the solenoid packs into chromosome is still unkown. There are many chromosome models proposed, such as super-solenoid model, center-scaffold model and YR-cohesion chromosome model. The YR-cohesion chromosome model is a five degree chromosome model. In this model, the solenoid is bended by YR-structure to form JW-ladder, then the JW-ladder is foldover by WYR-structure to form 300nm chromonema, which at last coils to form chromosome. The YR-cohesion model is rational in structure. It can successfully explain a lot of phenomena of genetics, such as synaptonemal complex's forming and polytene chromosome.Based on published sequences of human chromosomes by Human Genome Project, a signal model of chromosome was established and signal-processing method was used to analysis sequence's characteristics, to evaluate its correlationship with chromosome structure and to search for evidence of YR-cohesion model. In the signal model, double strand of DNA was used to calculate the signal value. FFT(Fast Fourier Transform) was used to analysis the spectrum of chromosome signal, followed by period analysis with spectrum.In the analysis of random sequences, a set of sequences is proved to be correlated to chromosome structure and it is also accord with parameters of YR-cohesion model, which show a sequence evidence of YR-cohesion model. Some human promoter sequences are also correlated with YR-structure but not WYR-structure.In the sequences above, the proportion of base combination AG and TC is major.