Evolution of the hominoid based on differentiation of constitutive hetrochromatin in chromosomes

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1. Genomic dispersion of 18S rDNA and β-satellite DNA in hominoids and its evolutionary aspects : Chromosomal localization of two repetitive DNAs, rDNA and β-satellite DNA, in the hominoid showed that a cladistic divergence order of these DNAs in the apes, gibbon, siamang, orangutan, gorilla, human, chimpanzee, and bonobo. The dynamic power of the dispersion is postulated to be concerted evolution in terms of the hetero-site crossover after acrocentric formation by centric fission.2. A new interpretation of chiasmate based on chiasma graph analysis and telomere configurarion : Examination of telomere configuration on the bivalents of diakinesis in the meiotic cell division of a mouse (Mus platythric, haploid chromosome number n=13) clarified that the end-end association of two homologues showed a square formation by 4 telomeres, while the crossover in arm showed a rectangle. That is, the former could be a manifestation of telomere-telomere association, being not the genetic recombinati … More on in essential meaning of chiasmata. The latter is a manifestation of crossingover between two sisterchromatids, being real gene shuffling. Therefore, the telomere-telomere association might not be chiasmata.3. Influence of C-band regions for chiasma formation : Chiasma frequency and location were observed using diakinesis chromosomes of the Rehsus monkey and black-capped capuchin. The former species has only centromeric heterochrmatin and the latter has centromeric, teiminal and interstitial heterochromatin. Chiasma graph analysis elucidated that chiasma formation of the capuchin was biased by C-band location in some chromosomes with terminal and interstitial heterochromatin. The chiasma frequency was as follows: Japanese monkey Fxi=23.8 and Fxit=42 ; black-capped capuchin, Fxi=27.2 and Fxit=41.4.4. Chiasmate of chimpanzee : Chasmata of chimpanzee was observed using meiotic chromosomes prepared with seminiferous tubules obtained by biopsy. Though only chiasma frequency was examined at this time, th chromosome preparations will produce valuable results of meiotic cell biology in chimpanzee in terms of molecular cytogenetical analyses in the future.5. Relationships of telomere sequence and constitutive heterochromatin : Chromosomal localization of telomere sequence was made in hominoids using a primed in situ labeling technique. Most of terminal C-band blocks of chimpanzee, bonobo, gorilla and siamang were labeled by telomere sequnce. This could be a manifestation of evolutionary pathway of chromosome differentiation in the hominoid. It will be analyze in more detail. Less