You are here:
STAGE-SPECIFIC DAMAGE TO SYNAPTONEMAL COMPLEXES AND METAPHASE CHROMOSOME INDUCED BY X RAYS IN MALE MOUSE GERM CELLS
Citation:
Backer, L., M. Sontag, AND J.W. Allen. STAGE-SPECIFIC DAMAGE TO SYNAPTONEMAL COMPLEXES AND METAPHASE CHROMOSOME INDUCED BY X RAYS IN MALE MOUSE GERM CELLS. U.S. Environmental Protection Agency, Washington, D.C., EPA/600/J-91/040.
Description:
Synaptonemal complexes (SCs) reveal mutagen-induced effects in germ cell meiotic chromosomes. his study was aimed at characterizing relationships between SC and metaphase I chromosome damage following radiation exposure at various stages of spermatogenesis. Male mice were irradiated with doses of 0, 2, or 4 Gy, and spermatocytes were harvested at time consistent with earlier exposures as spermatogonial stem cells, preleptotene cells (premeiotic DNA synthesis), or meiotic prophase cells. fter stem-cell exposure, twice as any rearrangements were observed in SCs as in metaphase I chromosomes. rradiation during premeiotic DNA synthesis resulted in dose-related increases in SC breakage and rearrangements (including novel forms) and.in metaphase chromosomal aberrations. ollowing prophase exposure, various types and levels of SC and metaphase damage were observed. rradiation of zygotene cells led to high frequencies of chromosome multivalents in metaphase I without a correspondingly high level of damage in preceding prophase SCs. hus, irradiation of premeiotic and meiotic cells results in variable relationships between SC nd metaphase chromosome damage. nterpretations of these relationships are based upon hat is known about both radiation clastogenesis and the structural/temporal relationships between SCs at prophase and chromosomes at metaphase I of meiosis.