Distribution of splicing proteins and putative coiled bodies during pollen development and androgenesis in Brassica napus L.

Abstract

Small nuclear ribonucleoprotein particles (snRNPs) are subunits of splicing complexes, which show a transcription-dependent localization pattern. We have analyzed the labelling pattern of snRNPs during pollen development and microspore and pollen embryogenesis in Brassica napus with an antibody which recognizes protein D of U1, U2, U4, U5, and U6 snRNPs. It was found that nuclei were labelled almost uniformly for snRNPs in microspores and young bicellular pollen. In the generative nuclei of late-bicellular pollen and in the vegetative nuclei and sperm nuclei of mature pollen no snRNPs could be detected. The snRNP-positive nuclei contained mostly one or two brightly labelled nuclear bodies, most likely coiled bodies, often closely related to the nucleolus. These nuclear bodies increased in size from 0.5 micron in nuclei of young microspores up to 2 microns in nuclei of late microspores and the vegetative nucleus of early-bicellular pollen. Also their number increased during these developmental stages. After induction of embryogenesis the size of the coiled bodies decreased to about 0.5 micron and in several occasions the coiled body was found free in the nucleoplasm, away from the nucleolus. The results support the idea that the size and number of coiled bodies coincide with changes in general nuclear activity. They also indicate that, in nuclei of Brassica napus, at least assembly and disassembly of coiled bodies takes place in the nucleoplasm, whereas mature coiled bodies are located adjacent to the nucleolus.

Periodic expression of Sm proteins parallels formation of nuclear Cajal bodies and cytoplasmic snRNP-rich bodies

“…We used the mouse mAb 7.13, which recognizes the SmD protein of the Ul, U2, U4, U5, and U6 snRNPs in plants (Billings et al 1982, 1985; Pálfi et al 1989; Testillano et al 1993; Straatman and Schel 2001). Immunoprecipitation and western blot analyses demonstrated that the mouse monoclonal anti-SmD antibody recognized a band with a molecular mass of about 55 kDa (Fig.…”

“…Moreover, it has been shown that the number of CBs in plant cells changes during the cell cycle and differentiation (Boudonck et al 1998; Straatman and Schel 2001; Seguí-Simarro et al 2006; Zienkiewicz and Bednarska 2009). …”

Changes in poly(A) RNA and TMG snRNA distribution in the embryo sac of Hyacinthus orientalis L. before and after fertilization

“…Our knowledge about the state of the cellular splicing machinery organization in germ line cells of angiosperms still remains poor. Few and fragmentary data concerning the localization of splicing molecules came from studies on pollen cells (Concha et al 1995;Straatman and Schel 2001;Fang et al 2004;Zienkiewicz et al 2006) and pollen tubes (Zienkiewicz et al 2008). So far, there are no reports about the spatial organization of gene expression in flowering plant female gametophyte cells.…”

Differentiating plant cells switched to proliferation remodel the functional organization of nuclear domains

“…These splicing factors accumulate in Cajal bodies (Raska et al, 1990;Ferná ndez et al, 2002). Antibodies to splicing factors revealed these nuclear bodies as small bright spots (Moreno Díaz de la Espina et al, 1982;Testillano et al, 1993;Straatman and Schel, 2001).…”

“…Nuclear bodies and specifically Cajal bodies are apart from the nucleolus and heterochromatin masses, one of the most evident nuclear substructures which have been found in numerous differentiated and proliferating animal cells (reviewed in Gall, 2000), as well as in some plant cells (Moreno Díaz de la Espina et al, 1982;Straatman and Schel, 2001). Cajal bodies (CBs) are rounded structures ranging from 0.1 to 2.0 Ìm, related to interchromatin granules, and showing an ultrastructure, in most cell types, of packed coiled threads (Raska et al, 1990;Lafarga et al, 1998).…”