The alternatively spliced acid box region plays a key role in FGF receptor autoinhibition

Uncontrolled fibroblast growth factor (FGF) signaling can lead to human malignancies necessitating multiple layers of self-regulatory control mechanisms. Fibroblast growth factor receptor (FGFR) autoinhibition mediated by the alternatively spliced immunoglobulin (Ig) domain 1 (D1) and the acid box (AB)-containing linker between D1 and Ig domain 2 (D2) serves as the first line of defense to minimize inadvertent FGF signaling. In this report, nuclear magnetic resonance and surface plasmon resonance spectroscopy are used to demonstrate that the AB subregion of FGFR electrostatically engages the heparan sulfate (HS)-binding site on the D2 domain in cis to directly suppress HS-binding affinity of FGFR. Furthermore, the cis electrostatic interaction sterically autoinhibits ligand-binding affinity of FGFR because of the close proximity of HS-binding and primary ligand-binding sites on the D2 domain. These data, together with the strong amino acid sequence conservation of the AB subregion among FGFR orthologs, highlight the universal role of the AB subregion in FGFR autoinhibition.     

Why does iron abrogate the cytotoxic effect of S-nitrosothiols on human and animal cultured cells?

It was found that dinitrosyl iron complexes (DNIC) with thiol-containing ligands (cysteine or glutathione) of concentrations up to 1 mM produce no cytotoxic effect on cultured cells from human milk gland carcinoma (MCF-7). The cytotoxic action on MCF-7 cells was produced by S-nitrosocysteine: at a concentration of 1 mM, it induced the death of 50% cells. A more stable S-nitrosothiol, S-nitrosoglutathione, did not produce any cytotoxic effect at the same concentration. It is assumed that the negative action of nitrosocysteine is due to its rapid degradation, which results in the accumulation of large amounts of free NO molecules followed by their oxidation by superoxide ions to peroxynitrite, an efficient inhibitor of metabolic processes. These processes seem to be not characteristic of the more stable S-nitrosoglutathione. The cytotoxic effect of nitrosocysteine was completlly abrogated by the addition of 0.2 mM ferrous citrate complex to the medium. When S-nitrosoglutathione NO (0.5 mM) or S-nitrosoglutathione (0.5 mM) + Fe(2+)-citrate (0.2 mM) were added to the medium, protein-bound dinitrosyl iron complexes formed with the involvement of endogenous or exogenous iron were detected in cells. The amount of the complexes in the presence of exogenous iron increased four times, reaching the value of 1.6 nmole/5 x 10(6) cells. Therefore, it was proposed that the blockade of the cytotoxic action of S-nitrosoglutathione by iron complexes is due to Cys-NO transformation of S-nitrosocysteine into dinitrosyl iron complexes. The high stability of these complexes ensures only a gradual accumulation of nitric oxide in cells.     

Micropropagation of ornamental <Emphasis Type="Italic">Prunus</Emphasis> spp. and GF305 peach,a <Emphasis Type="Italic">Prunus</Emphasis> viral indicator

A micropropagation approach was developed for nine ornamental Prunus species, P. americana, P. cistena, P. glandulosa, P. serrulata ‘Kwanzan’, P. laurocerasus, P. sargentii, P. tomentosa, P. triloba, P. virginiana ‘Schubert’, commercially important in North America, and GF305 peach, commonly used for Prunus virus indexing. The micropropagation cycle based on proliferation of vegetative tissues includes establishment of tissue culture through introduction of shoot meristems in vitro, shoot proliferation, root induction and plant acclimatization steps and can be completed in 5 months. A meristem sterilization protocol minimized bacterial and fungal contamination. Multiple shoot formation in ornamental Prunus was obtained through the use of 1 mg l⁻¹ 6-benzyladenine. For GF305 peach, alteration in the sugar composition, fructose instead of sucrose, and addition of 1 mg l⁻¹ ferulic acid had a significant impact on the shoot proliferation rate and maintenance of long-term in vitro culture. Rooting and plant acclimatization conditions were improved using a two-step protocol with a 4-day root induction in indole-3-butiric acid (IBA)-containing media with consequent 3-week root elongation in IBA-free media. One-month incubation of rooted shoots in a vermiculite-based medium resulted in additional shoot and root growth and provided better acclimatization and plant recovery. The micropropagation approach can be used for maintenance of the clonal properties for Prunus spp. as well as a protocol to support meristem therapy against viral infection.     

A Possible Mechanism of Modulation of Slow Sodium Channels in the Sensory Neuron Membrane by Short Peptides

Biophysics - The possible mechanisms of ligand–receptor binding of arginine-containing tetrapeptides with the NaV1.8 channels in the primary sensory neuron were investigated. Ac-RERR-NH2...     

Comparative cytological and molecular analysis of common wheat introgression lines containing genetic material of <Emphasis Type="Italic">Triticum timopheevii</Emphasis> Zhuk

A total of 40 introgression lines of common wheat (2 n = 42) Triticum aestivum L × T. timopheevii Zhuk., resistant to leaf rust and partly to powdery mildew, were examined. Based on cytological analysis of meiosis in pollen mother cells (PMC), hybrid lines were subdivided into two groups characterized by either stable or unstable meiosis. In cytologically stable lines, chromosome configuration at the MI stage of meiosis was mostly bivalent (21II) with small proportion of defect cells (almost 10%), which at most contained two univalents (20II + 2I). Cytologically unstable group was comprised of the lines, containing high proportions of cells with abnormal chromosome pairing in meiotic PMC, as well as the cells with multivalents, and the lines containing aneuploid plants. Localization of the T. timopheevii fragments performed with the use of SSR markers showed that the lines with unstable meiosis were characterized by higher numbers of introgressions compared to stable lines. The influence of certain chromosomes of T. timopheevii on chromosome pairing stability was also demonstrated. In cytologically unstable lines, the increased frequency of 2A substitutions along with the high frequency of introgression of T. timopheevii genetic material into chromosome 7A was observed. Multivalents were scored in all cases of introgression in chromosome 7A. It was suggested that the reason for the genome instability in hybrid forms lied in insufficient compensating ability of certain T. timopheevii chromosomes and/or their parts, involved into recombination processes.     

Production and characteristics of monoclonal antibodies to the diphtheria toxin

Monoclonal antibodies to the diphtheria toxin were produced without cross reactivity with the thermolabile toxin (LT) from Escherichia coli; ricin; choleraic toxin; the SeA, SeB, SeE, SeI, and SeG toxins of staphylococcus; the lethal factor of the anthrax toxin; and the protective antigen of the anthrax toxin. A pair of antibodies for the quantitative determination of the diphtheria toxin in the sandwich variation of enzyme-linked immunosorbent assay (ELISA) was chosen. The determination limit of the toxin was 0.7 ng/ml in plate and 1.6 ng/ml in microchip ELISA. The presence of a secretion from the nasopharynx lavage did not decrease the sensitivity of the toxin determination by sandwich ELISA. The immunization of mice with the diphtheria toxin and with a conjugate of the diphtheria toxin with polystyrene microspheres demonstrated that the conjugate immunization resulted in the formation of hybridoma clones which produced antibodies only to the epitopes of the A fragment of the diphtheria toxin. The immunization with the native toxin caused the production of hybridoma clones which predominantly produced antibodies to the epitopes of the B fragment.     

The role of the medial geniculate bodies in analyzing sounds]

Elaboration and manifestation of motor alimentary conditioned reflexes were studied after a lesion of medial geniculate bodies (MGB) in adult cats. No substantial disturbance were recorded of the capacity for pitch analysis. In the case of more extensive MGB lesions, there were some difficulties in the elaboration of tone differentiations but not in their achievement. Additional temporo-parietal cortical ablation drastically reduced the animals' capacity for anlysing sound frequencies and more profoundly disturbed their capacity for inhibitory reactions.