REGULATION OF MEIOTIC CHROMATIN LOOP SIZE BY CHROMOSOMAL POSITION

At meiotic prophase, chromatin loops around a proteinaceous core, with the sizes of these loops varying between species, Comparison of the m orphology of sequence-related inserts at different sites in transgenic mice demonstrates that loop size also varies with chromosomal geograp hy, Similarly, chromatin loop lengths differ dramatically for intersti tially and terminally located hamster telomeric sequences, Sequences, telomeric or otherwise, located at chromosome termini, closely associa te with the meiotic proteinaceous core, forming shorter loops than ide ntical interstitial sequences, Thus, we present evidence that differen t chromatin packaging mechanisms exist for interstitial versus termina l chromosomal regions, which act separately from those operating at th e level of the DNA sequence, Chromosomal position plays the dominant r ole in chromatin packaging.