AbstractsBiology & Animal Science

Study of the human Y chromosome in the interphase nucleus by light microscopy, quinacrine fluoromicroscopy and autoradiography

by Herman Edwin Wyandt




Institution: Oregon State University
Department: Zoology
Degree: PhD
Year: 1971
Keywords: Y chromosome
Record ID: 1488775
Full text PDF: http://hdl.handle.net/1957/45432


Abstract

Part of the Y chromosome in humans is detectable as a brightly fluorescing body in interphase nuclei stained with quinacrine dyes. This fluorescent body when stained with quinacrine mustard dihydrochloride, in cells from some 15 human subjects, was seen to manifest a variable morphology which appeared to be related to the stage of the nucleus in the cell cycle. The variable morphology was seen particularly in cultured fibroblasts and in peripheral blood lymphocytes undergoing blastic transformation induced by PHA, but was not observed in buccal mucosa or hair root sheath cells. The morphology of the Y-body ranged from a highly condensed configuration in small non-transformed nuclei to increased degrees of dispersion which appeared to show direct relationship to size of the transformed nucleus. In nuclei which appeared to be in preprophase (G-2), the Y-body appeared to partially recondense. Lymphocyte cultures, which were serially harvested, showed an increase in percent of nuclei with a dispersed Y-body, proportional to time in culture, and generally an increase in nuclear diameter. Nuclei studied from serially cultured skin fibroblasts showed the highest percent of nuclei with a dispersed Y-body during the log phase of cell growth, and a decline in the frequency of dispersed morphology in the post-log phase. Percent dispersion also showed a direct relationship to mitotic index. Continuous terminal and pulse-labeling studies of the Y-body revealed increased incorporation of tritiated thymidine with increased dispersion. The labeling studies suggested that the observed morphological configurations were sequential, and that the Y-body while condensed generally lagged in DNA-synthesis, but that the rate of DNA-synthesis of the Y-body was more rapid than the rest of the nucleus as it became more dispersed. The studies indicate that the different morphologies of the Y-body represent stages in the cell cycle, and suggest that portions of the Y-body may be uncoiling during the time it is actively synthesizing DNA.