Lacandonia granules are present in the cell nucleus of Welwitschia mirabilis

<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>

Aquatic silk proteins in Chironomus: A review

Silk proteins secreted by salivary glands in the dipteran insect, Chironomus play a significant role as proteinaceous adhesives for construction of underwater housing nests by larvae. To date, only three Chironomus species, C. tentans Fabricius, C. pallidivittatus Malloch and C. riparius Meigen have been explored for characterization of their aquatic silk protein. Genes coding for silk proteins are located on specific chromosomal ‘puffs’ called Balbiani rings as well as non-Balbiani ring regions. Expression of these genes is closely regulated by developmental and hormonal alterations and environmental factors. Furthermore, pilot studies have postulated that silk proteins probably occur in diverse size classes grouped into large (~1000 kDa), intermediate (100-200 kDa) and small (≤100 kDa). Barring few preliminary reports that date back to the 1990s, the physical and bioproperties of silk from chironomid midges remain largely unknown, leading to paucity of updated information. This review was therefore aimed to compile existing literature database and to highlight the wide possibilities for commercialization of midge larval silk as a novel biopolymer.

POLYTENE CHROMOSOMES OF GLYPTOTENDIPES GLAUCUS MG. (DIPTERA, CHIRONOMIDAE) AS TEST – OBJEKT TO STUDY TOXIC EFFECTS OF LEAD IONS

Results of the analysis of cytogenetic effects of lead ions on polytene chromosomes of Glyptotendipes glaucus Mg are reported. The functional state of polytene chromosomes was determined via computation: chromosome compactness index (CR); coefficient of genetic activity of the nucleolar organizer (NOR) and coefficient of genetic activity of the Balbiani ring (BR). With increase of the lead nitrate solution concentration, the compactness index increases, that is, the chromosomes compactness decreases: medians of CR values (when measuring shoulder E) in the control are 6.05, for the maximum concentration studied they are 7.3. As a result of the of lead ions action, the activity of the nucleolar organizer genes decreases: medians of the NOR values decrease from 2.3 in the control to 2.0 for the highest concentrations used in the experiment. The activity of the Balbiani ring genes increases with the growing concentration of the lead nitrate solution: medians of the BR values in the control are 1.45, for the maximum studied concentration they are 1.95. The G. glaucus genome responds ambiguously to the change in the lead ions concentration in the medium: the coefficient of the nucleolar organizer’s genetic activity decreases, while the genetic activity of the Balbiani ring, on the contrary, increases.