Apoptosis in Cells of the Initial Leaf and Coleoptile of Wheat Seedlings: Internucleosomal Fragmentation of Genome and Synthesis of "Heavy" Oligonucleosome-Size DNA Fragments

M. D. Kirnos,^1,2 N. I. Alexandrushkina,¹ and B. F. Vanyushin¹

¹Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, 119899 Russia; fax (095) 939-3181; E-mail: vanyushin@moo.genebee.msu.su

²To whom correspondence should be addressed.

Submitted February 10, 1997; revision submitted April 8, 1997.

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Apoptosis-specific oligonucleosome-size nDNA fragmentation (180 ± 10 bp)_n, n >= 1 and intensive incorporation of labeled precursors into the "heavy" (rho = 1.716 g/cm³) DNA fraction were detected in the leaf and coleoptile regions of wheat seedling comprised of non-dividing cells. The distribution pattern of labeled DNA (195 ± 10 bp)_n, n >= 1 in agarose electrophoresis imitates the oligonucleiosomal DNA fragments formed during the apoptoic internucleosomal breakdown of nDNA. Thus, in cells of the initial leaf and coleoptile, growth and development of normal wheat seedlings even during early ontogenesis stages are accompanied by apoptosis-specific internucleosomal DNA fragmentation and intensive synthesis of "heavy" GC-enriched oligonucleosome-size DNA fragments.

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KEY WORDS: apoptosis, oligonucleosome-size DNA fragments, internucleosomal DNA fragmentation, DNA synthesis, wheat.

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