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Is repetitive DNA involved in male gametogenesis ofNarcissus papyraceus?
Authors:Paola Bassi
Institution:(1) Dipartimento di Biologia Vegetale, Universitá degli Studi ldquoLa Sapienzardquo, Piazzale A. Moro 5, I-00185 Roma, Italy
Abstract:Summary The male gametophyte of the Spermatophyta is of particular interest when studying quantitative modifications of repetitive DNA which accompany plant differentiation. In fact, this well documented system offers the opportunity to investigate the phenomenon at the nuclear level. In particular, it permits comparison between single haploid nuclei which, though derived from the same mitotic division, have different, well-defined morphological and functional processes. The aim of the present work was to investigate the behaviour of repetitive DNA during male gametogenesis inNarcissus papyraceus. By the use of A+T and G+C specific fluorochromes (DAPI and Chromomycin A3), and by in situ DNA digestion with appropriate restriction endonucleases (Eco RIplusb and Hae III), it is shown that during the course of gametogenesis, generative and vegetative nuclei behave differently with respect to particular sections of the genome. Characteristic agglomerations of specific A+T rich DNA sequences can be observed, localized by the two distal ends of the spindle-shaped generative nucleus. The surface area occupied by the agglomerations differs significantly at the ends in all observed cases. The above agglomerations are present in most of the generative nuclei and are probably composed of repetitive DNA sequences. Some embryological questions are discussed in the light of these results.Abbreviations DAPI 4prime,6-diamidino-2-phenylindole - Eco RIplusb Eco RI with ldquostarrdquo activity (N/AATTN) Dedicated to Prof. E. Battaglia on the occasion of his 75th birthday
Keywords:Cell differentiation  Fluorochromes  In situ endonuclease digestion  Male gametogenesis  Narcissus papyraceus  Repetitive DNA
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