KNOTTED1-LIKE HOMEOBOX 3: a new regulator of symbiotic nodule development.

KNOX transcription factors (TFs) regulate different aspects of plant development essentially through their effects on phytohormone metabolism. In particular, KNOX TF SHOOTMERISTEMLESS activates the cytokinin biosynthesis ISOPENTENYL TRANSFERASE (IPT) genes in the shoot apical meristem. However, the role of KNOX TFs in symbiotic nodule development and their possible effects on phytohormone metabolism during nodulation have not been studied to date. Cytokinin is a well-known regulator of nodule development, playing the key role in the regulation of cell division during nodule primordium formation. Recently, the activation of IPT genes was shown to take place during nodulation. Therefore, it was hypothesized that KNOX TFs may regulate nodule development and activate cytokinin biosynthesis upon nodulation. This study analysed the expression of different KNOX genes in Medicago truncatula Gaertn. and Pisum sativum L. Among them, the KNOX3 gene was upregulated in response to rhizobial inoculation in both species. pKNOX3::GUS activity was observed in developing nodule primordium. KNOX3 ectopic expression caused the formation of nodule-like structures on transgenic root without bacterial inoculation, a phenotype similar to one described previously for legumes with constitutive activation of the cytokinin receptor. Furthermore, in transgenic roots with MtKNOX3 knockdown, downregulation of A-type cytokinin response genes was found, as well as the MtIPT3 and LONELYGUY2 (MtLOG2) gene being involved in cytokinin activation. Taken together, these findings suggest that KNOX3 gene is involved in symbiotic nodule development and may regulate cytokinin biosynthesis/activation upon nodule development in legume plants.

[Monoclonal antibodies against human secretory component: epitope specificity and utility for immunoanalysis].

AIM: To develop and characterize by immunochemical methods the panel of monoclonal antibodies (MAbs) recognizing different antigenic determinants ofhuman secretory component (SC) molecule. MATERIALS AND METHODS: sIgA and SC were obtained from colostrum by combination of ion-exchange chromatography and gel filtration. Recombinant SC was expressed in Escherichia coli cells transformed by construction that contained fragment of gene coding extracellular domain of receptor for polymeric Ig. MAbs were produced and studied using hybridoma technologies and different methods of immunoenzyme analysis respectively. RESULTS: Panel comprising 10 MAbs against human SC of which 4 types of antibodies recognize cryptic epitopes of free SC and other 6 types recognize epitopes exposed both on SC and sIgA. MAbs panel contains antibodies interacting with conformational and linear epitopes of antigen. Three from obtained MAbs bind to SC epitopes which structure is determined by presence of carbohydrate residues in the molecule of antigen. Immunometric systems were developed which allow to differentially detect free SC and sIgA. CONCLUSION: Developed and characterized MAbs panel recognizing different epitopes of SC molecule opens new opportunities for laboratory and basic research of human secretory immunity.

[The hemodynamic, humoral and cellular effects of plasmapheresis in a refractory form of hypertension]. / Gemodinamicheskie, gumoral'nye i kletochnye éffekty plazmafereza pri refrakternoi forme gipertonicheskoi bolezni.

Plasmapheresis effects on hemodynamics, neurohumoral, immunological and cell parameters were examined in 48 patients with refractory hypertension. Hypotensive effect of plasmapheresis was found to combine with positive hemodynamics and microcirculatory shifts, pressor factor activity inhibition, slowing of immunocomplex condition progress, reduced red cell deformability in refractory hypertension.