最下等真核生物

The present authors investigated the incorporations of Arg-3H and thymidine-3H into the nuclei of Gyrodinium sp. in Dinophyceae which is the most primitive eukaryote and were able to take the electron micrographs showing the ultrafine structures of these incorporative sites. In these nuclei, nucleogranules which are DNA double strands with the radii of curvatures from 70 to 80 Å are hardly bound with Arg rich proteins, but changed to be bound with the same proteins when stretched by certain pulling forces through chromonemata extended from nucleofilaments in the chromosomes. The reason was attributed to the almost same length of both atomic arrangements of O-P-O-C-C-C (7.11Å) in a sugar phosphate of the backbone of DNA and N-C-C-N-C-C (7.43Å) in a dipeptide residue of the back bone of protein, consequently, to the easiness of the formation of the ionic bonds between Po4- and NH3+ groups. Individual DNA single chains can not transmit any torque, because the single bonds such as those of 5' carbon in the sugar phosphate possess the nature of free rotation. But these DNA single chains bound with Arg or Lys rich proteins can transmit the torque by producing strands. Through a model test, it was confirmed that if DNA double strand receives a strong sinistral-torque after such proteins were bound, not only the right handed strands of the resulted complex (P-DNA-DNA-P) are unwound, but the hydrogen bonds of the base pairs of this complex are splitted. The divided complexes (P-DNAs) can be Pb2+-unstainable and one of them can be active as a template for transcribing to RNA. However, it was confirmed that a couple of P-DNAs again combine forming nucleosomes, comsequently, liberating RNA synthesized on one P-DNA. The necessary forces for stretching the DNA double strand of nucleogranules to the state of a slow curve and accelerating protein bindings, and for splitting the hydrogen bonds of the base pairs of the complex of P-DNA-DNA-P and inducing the formation of a template P-DNA for transcribing to RNA were confirmed to be generated through the formation of nucleofilaments. Therefore, both DNA and RNA syntheses were concluded to be conjugated with the formations of these nucleosomes and nucleofilament. Therefore, we can say that the new roles of a group of histones have been made clea here, since the behavior of proteins in the nuclei of Gyrodinium sp., the lowest eukaryote, are very similar to those of histones in higher eukaryote.