ANTHERIDIAL CHROMATIN CONDENSATION FACTOR FROM MALE SEX ORGANS OF CHARA TOMENTOSA

Incubation of roots (Melandrium noctiflorum) in crude extracts obtained from maturing male sex organs of Chara tomentosa results in supercondensation of mitotic chromosomes. The observed changes, including a number of ‘secondary effects’, confirm precisely with all those kinds of alterations which are typical of M-phase cells in antheridial filaments during their progression from the proliferative period of development towards terminal differentiation into sperm cells. Biological assays performed with proteinaceous extracts of maturing antheridia indicate that the activity is confined merely to a fraction containing low molecular (4.5kDa) peptides, termed as ACCF (antheridial chromatin condensation factor). Microchemical tests showed the acidic character of ACCF and its apparent ability to form cross-links with histones and DNA-histone complexes, mediated presumably by disulfide bridges. The characteristic punctate distribution of vesicles within the cytoplasm suggests the internalization of rhodamine-isothiocyanate labelled ACCF (ACCF-TRITC) by endocytosis, implying possible sequestering and nuclear translocation upon release from the endosomal/lysosomal compartment of the cell.