Lacandonia granules are present in the cell nucleus of Welwitschia mirabilis

Abstract

<p><strong>Background:</strong> <em>Lacandonia</em> granules are extranucleolar ribonucleoprotein (RNPs) particles, 32 nanometers in diameter that were first described in the nucleus of <em>Lacandonia schismatica</em>. Cytochemical and immunocytochemical studies suggest that these particles are equivalent to perichromatin and Balbiani ring granules described in mammals and salivary glands cells of the insect <em>Chironomus tentans, </em>respectively. <em>Lacandonia</em> granules are also present in the related <em>Triuris</em> <em>brevystilis</em>,<em> </em>and they were later described in the gymnosperm <em>Ginkgo biloba</em>. These findings suggest that <em>Lacandonia </em>granules have a wider distribution in the plant kingdom. </p><p><strong>Species study:</strong> The plant <em>Welwitschia mirabilis, </em>a gymnosperm of the order Gnetales.</p><p><strong>Hyphotesis: </strong><em>Lacandonia</em> granules are present in the cell nucleus of <em>W. mirabilis</em>.<strong> </strong></p><p><strong>Methods:</strong> Plants were cultivated<strong> </strong>in a germination chamber and samples of leaves were processed for transmission electron microscopy. Thin sections were stained with the EDTA technique preferential for ribonucleoproteins and osmium amine specific for DNA and observed with a microscopy.</p><p><strong>Results:</strong> Light, electronic and atomic force microscopy revealed that cell nuclei of <em>W. mirabilis</em> display a reticulated arrangement of chromatin. Moreover, granules of 32.17 ± 1.7 nm in diameter were observed among strands of reticulated chromatin.</p><p><strong>Conclusions:</strong> Our results indicate that <em>Lacandonia</em> granules are present in the nuclei of the gnetal <em>W. </em> <em>mirabilis.</em></p>