Experimental modelling of exine self-assembly

Abstract

Living and fossil megaspores produced by &laginella (Lycopsida) and its extinct ancestors form distinctive (and occasionally iridescent) exines. Ultrastructural studies of these spores have provided data that demonstrate a colloidal mode of development which in turn implies a degree of self-assembly in the construction of these exines. We present here experimental evidence in support of the theory of selaginellalean megaspore exine construction by depletion flocculation. Iridescent colloidal flocculations of polystyrene latex particles demonstrate an ultrastructural organization virtually indistinguishable from that of the biological system, and clearly demonstrate that self-assembly of complex Selaginella exines by a relatively simple construction process is plausible. 01996 The Linnean Sociehi of London

Experimental modelling of exine-like structures

“…E-mail: 1906ng@mail.ru (Received 27 February 2013accepted 4 June 2013) structure suggests a genomic key. However, as more facts accumulate, the more suspicions appear that self-assembly processes interfere (Heslop-Harrison, 1972;Gerasimova-Navashina, 1973;Sheldon & Dickinson, 1983;Gabarayeva, 1990Gabarayeva, , 1993Van Uffelen, 1991;Hemsley et al, 1992;Collinson et al, 1993;Southworth & Jernstedt, 1995) and distort the regular work of the genome, making the results unpredictable because of the non-linear character of self-assembly (Hemsley, 1998;. A possibility of the participation of selfassembly in spore and pollen wall development has been discussed in the review of Wellman (2004).…”

Micromorphology of outer exospore coatings inSelaginellamegaspores

“…A significant proportion of published work has concentrated upon micro-and megaspore development (Sievers & Buchen, 1970;Morbelli & Rowley, 1993, spore morphology (Minaki, 1984) and ultrastructure (Kempf, 1970, Buchen & Sievers, 1978aTryon & Lugardon, 1978Taylor, 1989Taylor, , 1991. Recently a number of articles describing the underlying processes of megaspore wall formation have discussed the role of self-assembly in a completely new light (Hemsley et al 1992;Hemsley et al 1994;Hemsley et al 2003). Only Kempf (1970), Tryon & Lugardon (1978), Taylor (1989) and Morbelli (1995) have so far mentioned the presence of silica in Selaginella megaspore walls.…”

Sporoderm development inSwida alba(Cornaceae), interpreted as a self-assembling colloidal system

“…The essence of that hypothesis was the supposition of a considerable role of micelle self-assembly processes in sporoderm development of any species. This hypothesis, in its turn, rests on the previous hypotheses (Hemsley et al, 1992;Collinson et al, 1993;Gabarayeva, 1993Gabarayeva, , 2000.…”