Maturation and secretion of a serine proteinase is associated with events of late microsporogenesis

An antiserum against meiotic proteins which bind to DNA cellulose was generated as a tool to assist the identification and purification of microsporogenesis-specific proteins. In immunoblotting experiments, this antiserum identified three meiotic proteins which are differentially expressed in anthers during microsporogenesis. One of these proteins was purified and characterized by biochemical and immunological techniques. This 82 kDa protein is synthesized as a preproprotein, acquires glycans as it moves through the endoplasmic reticulum and Golgi body, and is secreted into the anther locule. Immunocytochemical experiments demonstrate that the protein is expressed primarily in tapetal cells, and reaches peak concentrations as the microsporocytes reach the tetrad stage. Zymogram analyses and protein sequence comparisons indicate that the protein is a member of the serine proteinase family. The possible roles of the proteinase in microsporogenesis and pollen development are discussed.     

In vitro differentiation of human retinoblastoma cells into neuronal phenotypes

In order to characterize the cell type(s) of origin of human retinoblastoma cells by immunophenotyping, primary cells from seven retinoblastomas and of the corresponding cell lines (RBL lines), as well as four retinoblastoma (RB) lines established by other groups, were compared with rat and human retina cells, and with the adenovirus E1A-transformed human retinoblast cell line HER-Xho1-CC2. Analyses using monoclonal antibodies (Mabs) RB13-2 and RB21-7, originally raised against prenatal rat brain cells and recognizing neural cell surface antigens expressed in a developmental-stage-dependent manner, and three cell-type-specific Mabs (Q211, M501, Mab directed against vimentin) developed by other groups, gave the following results: (i) Retinoblastomas consist of cells expressing differentiated neuronal phenotypes during cultivation in vitro; (ii) All of the newly established RBL lines express neuronal phenotypes; and (iii) Cell lines such as Y79, which have been propagated in vitro for extended periods, do not express antigens specific for the neuronal pathway and cannot, therefore, be considered phenotypically representative of retinoblastoma cells.     

Pulsed-field electrophoresis in contour-clamped homogenous electric fields (CHEF) for fingerprinting of Rhizobium spp

Abstract: A pulsed-field gel electrophoretic method based on contour-clamped homogeneous electric field (CHEF) was developed for the analysis of natural isolates of Rhizobium leguminosarum biovar viciae . The procedure involves the use of 'rare-cutting' endonucleases. The separation of genomic DNA fragments with split runs ( τ = 5 s for 15 h followed by τ = 12 s for 9 h) allows a clear definition of profiles with bands ranging from 20–300-kb pairs. Two and a half days are sufficient to reproducibly accomplish the procedure from cell lysis to gel picture. The method can be used for different fast-growing rhizobia.