Polyploidy in differentiation and evolution

Abstract

Somatic and generative (germ-line) polyploidy are more widely spread phenomena among living organisms than generally thought. The occurrence of polyploidization and related events in normal and pathological differentiation, their recognized main functions, as well as the structural specificities of polyploid nuclei are reviewed, and the relationship between ontogenetic and phylogenetic events is discussed. The mechanisms leading to the polyploid state, as well as other processes resulting in a genomic condition different from the diploid one (such as DNA under-replication, gene amplification, and chromatin elimination), are briefly sketched. The various changes in chromosomal DNA described are, in conclusion, seen as evidence supporting the paradigm of a "fluid" or dynamic organization of the eukaryotic genome, as being part of a cybernetic feedback regulation system of gene expression. A model is proposed that unifies the aspects of DNA variation, chromatin structure, and diversification in ontogenesis and phylogenesis.

Alisma plantago-aquatica L.: the cytoskeleton of the suspensor development

“…Endoreduplication leads to an increased size of the nucleus and multiplication of the genomic DNA quantity, which can significantly affect the increase in RNA transcription and thus accelerate the metabolism of a cell. Probably, endopolyploid cells are better adapted to uptake the nutrients from surrounding tissues [13,30,31]. It is known that cytoplasmic skeleton in plant cells plays an important role during growth and differentiation.…”

Death through a tragedy: mitotic catastrophe

“…34 Chromosomes during endocycling are highly varied, which lead to the generation of endoploid cells. 88,89 Endocycling has been observed in tumor cells, and specifically in those lacking p53. 90,91 Formation of tetraploid cells is also a prerequisite for initiation of endocycling that in turn can lead to the appearance of polyploid giant cells with nuclear envelopes around clusters of chromosomes or chromosome fragments.…”

Suspensor Development in Gagea Lutea (L.) Ker Gawl., with Emphasis on the Cytoskeleton

“…Endoreduplication is a form of nuclear polyploidization by which cells gain additional copies of genomic DNA. It usually occurs in tissues and organs that actively function for only a short period of ontogenetic development, such as antipodals, the embryo suspensor, synergids, and also endosperm haustoria (Nagl, 1990). Reaching a high degree of endopolyploidy apparently increases the metabolic capacity of such cells.…”