Cytoskeletal and DNA synthesis modification by concanavalin A in embryonic fibroblasts maintained in serum-free and serum-added medium

The administration of lectin concanavalin A (Con A) to in vitro cultures of chick embryo fibroblasts caused dose-dependent changes in cell shape, cytoskeleton network and DNA synthesis. After 6 hrs. even a low doses of Con A produced evident effects in serum-free cultures, whereas higher doses were required to cause alterations in cells cultured in serum-added medium. As the sugar competitor mannoside abolishes the effects, it would seem that the lectin acts by binding to transmembrane receptors and that the fibronectin present in the serum engages the receptors so that they are not available to Con A.     

Membrane-modifying properties of the pore-forming peptaibols saturnisporin SA IV and harzianin HA V

Abstract Harzianin HA V and saturnisporin SA IV are α-amino isobutyric-containing peptides with 18- and 20-residue chain length, respectively. They were isolated from in vitro cultures of Trichoderma species and their sequences were determined by the combined use of positive ion FAB mass spectrometry and NMR. In organic solvent solution, both peptides exhibited the same predominant α-helical secondary structure including a hinge at the level of the central Pro residue, as deduced from NMR data. Their interaction with neutral phospholipid bilayers was shown to induce leakage of the material entrapped in small unilamellar vesicles composed of egg phosphatidylcholine/cholesterol (7/3). When incorporated into neutral planar lipid bilayers, they promoted voltage-gated channels. The concentration- and voltage-dependences of the ionic conductances induced by these peptides were studied in macroscopic current-voltage experiments. Single-channel measurements showed that whilst SA IV developed non-integral multi-open states similar to those induced by alamethicins, but with faster kinetics, the shorter analogue, HA V promoted much smaller-sized conducting aggregates in agreement with macroscopic conductance data.     

Combined influence of magnesium concentration and polymerase chain reaction specificity enhancers

Abstract The importance of an optimal magnesium concentration (6.5 mM), as well as the inclusion of a specific polymerase chain reaction enhancer, to obtain the correct fragment after amplification was examined during this study. In contrast to tetramethylammonium chloride, dimethyl sulphoxide did not enhance the specificity of amplification at different magnesium concentrations, but rather altered the specificity, resulting in the amplification of a larger fragment.     

Interleukin-1 alpha: regulation of cellular proliferation and collagen synthesis in cultured human osteoblast-like cells.

In this work the authors studied the effects of interleukin-1 alpha on metabolic activities of human osteoblast-like cells in vitro. The bone nature of the cells was established by assaying for specific bone protein, the osteonectin, and the parathormone receptor, an osteoblast marker. Administration of interleukin-1 alpha to cultured osteoblasts produce an increase in cellular proliferation as suggested by 3H-thymidine incorporation and cell growth studies. Interleukin-1 alpha also affected collagen synthesis confirming its potential role on bone-formation and resorption processes.     

Preliminary scanning electron microscope (SEM) observations of the rat renal parenchyma after microdissection]

Rat kidneys weighting between 250 and 300 g. were treated in HCl. A single nephron observed through SEM shows that the above treatment doesn't interfere with the ultrastructural morphology of nephron.     

Pea-derived vaccines demonstrate high immunogenicity and protection in rabbits against rabbit haemorrhagic disease virus

Vaccines against rabbit haemorrhagic disease virus (RHDV) are commercially produced in experimentally infected rabbits. A genetically engineered and manufactured version of the major structural protein of RHDV (VP60) is considered to be an alternative approach for vaccine production. Plants have the potential to become an excellent recombinant production system, but the low expression level and insufficient immunogenic potency of plant‐derived VP60 still hamper its practical use. In this study, we analysed the expression of a novel multimeric VP60‐based antigen in four different plant species, including Nicotiana tabacum L., Solanum tuberosum L., Brassica napus L. and Pisum sativum L. Significant differences were detected in the expression patterns of the novel fusion antigen cholera toxin B subunit (CTB)::VP60 (ctbvp60_SEKDEL) at the mRNA and protein levels. Pentameric CTB::VP60 molecules were only detected in N. tabacum and P. sativum, and displayed equal levels of CTB, at approximately 0.01% of total soluble protein (TSP), and traces of detectable VP60. However, strong enhancement of the CTB protein content via self‐fertilization was only observed in P. sativum, where it reached up to 0.7% of TSP. In rabbits, a strong decrease in the protective vaccine dose required from 48–400 µg potato‐derived VP60 [ Castanon, S., Marin, M.S., Martin‐Alonso, J.M., Boga, J.A., Casais, R., Humara, J.M., Ordas, R.J. and Parra, F. (1999) Immunization with potato plants expressing VP60 protein protects against rabbit hemorrhagic disease virus. J. Virol. 73 , 4452–4455; Castanon, S., Martin‐Alonso, J.M., Marin, M.S., Boga, J.A., Alonso, P., Parra, F. and Ordas, R.J. (2002) The effect of the promoter on expression of VP60 gene from rabbit hemorrhagic disease virus in potato plants. Plant Sci. 162 , 87–95] to 0.56–0.28 µg antigenic VP60 (measured with VP60 enzyme‐linked immunosorbent assay) of crude CTB::VP60 pea extracts was demonstrated. Rabbits immunized with pea‐derived CTB::VP60 showed anti‐VP60‐specific antibodies, similar to RikaVacc^®‐immunized rabbits, and survived RHDV challenge.