IAP insertion in the murine LamB3 gene results in junctional epidermolysis bullosa

The laminin-5 molecule functions in the attachment of various epithelia to basement membranes. Mutations in the laminin-5-coding genes have been associated with Herlitz junctional epidermolysis bullosa (HJEB), a severe and often lethal blistering disease of humans. Here we report the characterization of a spontaneous mouse mutant with an autosomal recessive blistering disease. These mice exhibit sub-epithelial blisters of the skin and mucosal surfaces and abnormal hemidesmosomes lacking sub-basal dense plates. By linkage analysis the genetic defect was localized to a 2-cM region on distal Chromosome (Chr) 1 where a laminin-5 subunit gene, LamB3, was previously localized. LamB3 mRNA and laminin-5 protein were undetectable by Northern blot analysis and immunohistochemical methods, respectively. DNA sequence analysis indicated that the LamB3 genetic defect resulted from disruption of the coding sequence by insertion of an intracisternal-A particle (IAP) at an exon/intron junction. These findings suggest a role for laminin-5 in hemidesmosome formation and indicate that the LamB3 ^IAP mutant is a useful mouse model for HJEB. Received: 27 March 1997 / Accepted: 14 May 1997     

Generation of long-term human cytolytic cell lines with persistent natural killer activity

Human cell lines maintained by in vitro stimulation with the HLA-A, B-negative, DR-positive, Epstein Barr virus-transformed, lymphoblastoid cell line Daudi in the presence of conditioned medium demonstrated significant NK activity for over 6 wk in continuous culture. These cells lyse K562 and a broad panel of lymphoblastoid cell lines but do not lyse normal peripheral blood lymphocytes or pokeweed mitogen blasts. They possess the sheep red blood cell receptor but lack other T cell markers (Lyt-3+, OKT3-). Natural killer activity correlated with the presence of a Mac 1-positive subpopulation of cells present in these long-term lines.     

Natural killer activity in the peritoneal exudates of mice infected with Listeria monocytogenes: characterization of the natural killer cells by using a monoclonal rat anti-murine macrophage antibody (M1/70)

Exudates induced by i.p. injection of five listeria monocytogenes (LM) constituted a rich source of CBA/J murine natural killer (NK) cells. Maximum expression of NK activity was seen from day 2 through day 6 after initial exposure to LM. When nylon wool nonadherent peritoneal exudate cells were examined by a single-cell cytotoxicity assay, the number of cells binding to YAC-1 target cells increased after infection as did their individual lytic capacity. A monoclonal rat anti-murine macrophage antibody (M1/70), previously shown by our group to recognize human NK cells, can also be used as a marker for murine NK cells. Utilizing M1/70 and the fluorescence-activated cell sorter, selection of M1/70-labeled mononuclear cells led to the enrichment of both NK and antibody-dependent cellular cytotoxicity. These M1/70-positive cells had a distinctive morphology and contained granules on Wright-Giemsa staining. They were not phagocytic, did not contain nonspecific esterase, and lacked surface I-Ak, IgM determinants, complement receptors, and high levels of Thy 1.2.     

Effect of Metalaxyl on the incidence and severity of Pearl millet downy mildew disease in Northern Nigeria

Pearl millet downy mildew (DM) incidence, severity and yield losses of two pearl millet varieties (local and improved) due to the disease were determined in the field. Significant differences in the disease incidence and severity were recorded in the plots sown with metalaxyl-treated seeds and those sown with non-treated seeds, indicating the efficacy of the fungicide on the fungus. Yield losses due to non-treatment of seeds with metalaxyl was 40.88 and 45.39% in a local variety and 43.00 and 18.60% in an improved variety in the 2000 and 2001 cropping seasons respectively. Significant differences between plots sown with metalaxyl-treated and those sown with non-treated seeds were obtained for other yield components such as 1000-grains weight, panicle length and weight.     

Gene expression and the evolution of phenotypic diversity in social wasps

Background  

Organisms are capable of developing different phenotypes by altering the genes they express. This phenotypic plasticity provides a means for species to respond effectively to environmental conditions. One of the most dramatic examples of phenotypic plasticity occurs in the highly social hymenopteran insects (ants, social bees, and social wasps), where distinct castes and sexes all arise from the same genes. To elucidate how variation in patterns of gene expression affects phenotypic variation, we conducted a study to simultaneously address the influence of developmental stage, sex, and caste on patterns of gene expression in Vespula wasps. Furthermore, we compared the patterns found in this species to those found in other taxa in order to investigate how variation in gene expression leads to phenotypic evolution.     

The yeast histidine protein kinase, Sln1p, mediates phosphotransfer to two response regulators, Ssk1p and Skn7p.

The Saccharomyces cerevisiae Sln1 protein is a ''two-component'' regulator involved in osmotolerance. Two-component regulators are a family of signal-transduction molecules with histidine kinase activity common in prokaryotes and recently identified in eukaryotes. Phosphorylation of Sln1p inhibits the HOG1 MAP kinase osmosensing pathway via a phosphorelay mechanism including Ypd1p and the response regulator, Ssk1p. SLN1 also activates an MCM1-dependent reporter gene, P-lacZ, but this function is independent of Ssk1p. We present genetic and biochemical evidence that Skn7p is the response regulator for this alternative Sln1p signaling pathway. Thus, the yeast Sln1 phosphorelay is actually more complex than appreciated previously; the Sln1 kinase and Ypd1 phosphorelay intermediate regulate the activity of two distinct response regulators, Ssk1p and Skn7p. The established role of Skn7p in oxidative stress is independent of the conserved receiver domain aspartate, D427. In contrast, we show that Sln1p activation of Skn7p requires phosphorylation of D427. The expression of TRX2, previously shown to exhibit Skn7p-dependent oxidative-stress activation, is also regulated by the SLN1 phosphorelay functions of Skn7p. The identification of genes responsive to both classes of Skn7p function suggests a central role for Skn7p and the SLN1-SKN7 pathway in integrating and coordinating cellular response to various types of environmental stress.