DNA content, interphase AgNOR-area, number of 3 HrDNA hybridization signals and the methylation level in coding rDNA sequence in different organs of Lupinus luteus L. |
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Authors: | T. Sakowicz M.J. Olszewska |
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Affiliation: | (1) Department of Plant Cytology and Cytochemistry, University of Lodz, Banacha 12/16, 90-237 Lodz, Poland |
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Abstract: | Nuclear DNA and AgNOR-area quantity have been measured cytophotometrically, the number of silver grains afterin situ3H rDNA/DNA hybridization has been counted, and the level of rDNA methylation has been estimated in root meristems, differentiated root zones, hypocotyls, cotyledons, and leaves of 7-day-old seedlings ofLupinus luteus. DNA content increases by endoreplication, reaching the average DNA C-value of 4.2 in the meristem, 6.6C in hypocotyl, 15.9C in cotyledon, and 3.3C in leaf. The quantity of AgNOR-area, the highest in root meristem, does not follow DNA C-value. Number of grains afterin situ3H rDNA/DNA hybridization corresponds to DNA amount, but their distribution differs, showing in many cases perinucleolar localization in organs displaying low AgNOR-area quantity. Southern hybridization has not demonstrated detectable changes in level rDNA methylation. We suggest that the low level of rDNA expression in non-meristematic tissues could be related to rDNA inactivation caused by its translocation into nucleolus-associated heterochromatin. |
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Keywords: | AgNOR-area DNA endoreplication methylation rDNA amount |
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