The Distribution And Organizational Form Of Non-Histone Proteins In The Chromosome Structure Of Higher Plants

Chromatin and chromosome are the same material and they exist in the cell cycle by the two different forms. It is the main carrier of genetic material and is composed of DNA, histone, non-histone proteins and a small amount of RNA. The research about it has been one foundational topic of cell biology for years. However, there is no clear understanding about chromosome higher order structure and the relationship between the structure and non-histone proteins. In this paper, taking higher plants as materials, we researched chromosome structure and distribution of non-histone proteins in chromosome structure by electron microscopy and silver nitrate staining method. It is helpful to further expound chromosome higher order structure and the role of non-histone proteins in the structure. The research conclusions are as follows:1. Under electron microscope, observing metaphase chromosomes of higher plants Wheat and Onion, there were no significant differences between them looking from their overall structure. Viewing from longitudinal sections of chromosome and by calculating, we could judge that there were higher compression levels between 30nm chromatin fibers and metaphase chromosome, and these chromatin fibers should be form metaphase chromosome by a helical coiling manner. Therefore we support the helical coiling model of chromosome.2. In chromosomal peripherals of the two plants we saw the outer sheath structure of large silver staining granules by overall observation after silver nitrate staining. This was consistent with the results which were seen in other organisms by some scholars. Therefore our experiment plays a supporting role in proving the structural universality in plants and this structure probably participates in maintaining chromosome higher order structure.3. There were no obvious differences about the distribution of non-histone proteins between the two plants by overall observation after silver nitrate staining. It was an evenly distribution relatively. We could not see a obvious longitudinal axis in chromosome which was composed by non-histone proteins. Thus we does not approve the viewpoint that there is a axis skeleton structure in the chromosome. Therefore we also disagree with the radial loop model based on the hypothesis of existing a chromosome axis skeleton structure.4. By observing, non-histone proteins could be divided into several categories of different sizes in chromosome. We further surmise the organizational form of non-histone proteins. It may be that smaller non-histone proteins linear link to participate in the formation of chromatin fibers of different levels, and the bigger non-histone proteins distribute uniformly in these smaller non-histone proteins to join chromatin fiber spiral rings by a scarf joint manner between the chromatin fibers. Thus non-histone proteins assist the chromotin fibers to coil to formation metaphase chromosome and are likely to maintain the morphological structure of metaphase chromosome. Therefore through interworking, different kinds of non-histone proteins probably play an important role in the formation and maintenance of chromosome structure.5. We consider that the distribution of non-histone proteins is a weblike state in the whole chromosome and it may be a true reflection of chromosome skeleton structure. Combining with previous research results about their existent periods and components, we can infer that the chromosome skeleton probably have a certain relation to nuclear matrix.