A new mutant class of soybean lacks urease in leaves but not in leaf-derived callus or in roots

Summary We reported earlier the recovery of two classes of soybean urease mutants in soybean (Glycine max L. Merr. cv. Williams). Class I mutants lack the embryo-specific urease while class II mutants lack the activities of both urease isozymes, the embryo-specific and the ubiquitous urease, the latter found in all tissues examined. We report here the recovery of a true-breeding mutant, aj3, which represents the third phenotypic class: normal levels of embryo-specific urease and little or no ubiquitous urease. Unlike class II mutant plants which lack urease in all tissue, aj3 lacks urease activity only in leaves (ca. 2% normal activity); its roots have near normal urease activity. Callus derived from leaves of aj3 has 14% to 40% the urease activity of Williams 82 callus. This partial reduction in urease activity in aj3 callus is sufficient to reduce growth with urea as sole nitrogen source and to confer resistance to 50 mM urea added to callus maintenance medium. Leaves of aj3 produce more than 40 times the urease antigen expected from their urease activity. The aj3 trait is due to a single recessive lesion which is not allelic with lesions at theEu2, Eu3 (class II) orEu1 (class I) loci. We designate the aj3 genotype aseu4/eu4.     

Sialic acid is a cell surface component of Entamoeba invadens trophozoites

The surface anionic groups of Entamoeba invadens were analysed by cell electrophoresis, by ultrastructural cytochemistry, and by identification of sialic acids using paper and gas-liquid chromatography. Binding of colloidal iron hydroxide (CIH) and of cationized ferritin (CF) particles at pH 1.8 and 7.2, respectively, was observed on the cell surface. E. invadens has a highly negative surface charge (-0.96 microns s-1 V-1 cm). Treatment of the cells with trypsin and neuraminidase significantly reduced the electrophoretic mobility by 24% and 40%, respectively. Treatment of the amoebae with neuraminidase also markedly decreased the binding of CIH to the cell surface. This finding suggests that sialic acid residues are the major anionogenic groups exposed on the surface of E. invadens. Paper and gas-liquid chromatography showed that N-acetylneuraminic acid was the only derivative characterized in E. invadens.     

Inheritance of resistance to bacterial blight in common bean

Summary Inheritance of resistance to common bacterial blight in the trifoliate leaf, plant canopy, and pods was controlled by a single major gene. Additive followed by dominance effects were more important than epistatic interactions. Narrow-sense heritability values ranged from 0.18 to 0.87 for trifoliate leaf, from 0.26 to 0.76 for canopy, and from 0.11 to 0.36 for pods. Observed gains from selection for resistance were higher than expected gains. Implications of these results in breeding for resistance are discussed.     

Isolation of Corynebacterium diphtheriae from sperm fluid

The isolation of toxigenic Corynebacterium diphtheriae from sperm is reported. The organism was identified through the investigation of fluorescence under the UV light, the presence of pirazinecarboxilamidase enzyme (Pyz), in vitro and in vivo and virulence methods (single radial immunodiffusion, cell culture, guinea pig intradermic test). The strain was initially considered nontoxinogenic by single radial immunodiffusion, but its virulence was observed afterwards, when we applied the tests already mentioned. The strain could be considered a "Diphtheroid" without adequate specification.     

Expression and characterization of the tau subunit of phosphorylase kinase

A cDNA encoding the entire tau subunit of rabbit skeletal muscle phosphorylase kinase was reconstructed and inserted into a plasmid containing the Escherichia coli ptac promoter and a constructed plasmid containing the ptac promoter and bacterial chloramphenicol acetyl transferase (CAT) gene, respectively. A significant phosphorylase kinase activity was found, in the first case. In the second case, a fused protein containing 73 amino acids from the CAT protein was obtained. After renaturation, the CAT-tau subunit protein shows enzymatic activity similar to the HPLC-purified and renatured tau subunit.     

The effect of glucose-6-phosphate isomerase genotype onin vitro specific activity andin vivo flux inMytilus edulis

Four samples of the musselMytilus edulis were taken between 1984 and 1987 from Stony Brook, New York, and used to study the glucose-6-phosphate isomerase (GPI) polymorphism in this species.In vitro specific activity andin vivo flux measured in the same animals were found to be significantly correlated. A significant effect of GPI genotype on flux was observed in one of the samples; overall, significant evidence of effect of genotype on enzyme activity was also obtained. GPI activities of common genotypes tend to deviate less from the population mean than those of rare (frequency less than 5%) genotypes. This suggests the possibility that rare GPI genotypes are rare as a consequence of having biochemical properties that deviate from an optimum level and, therefore, having a lower fitness. In support of this hypothesis, we found in one of our samples that shell length is a concave function of GPI activity with an intermediate optimum activity level. The financial support provided to P.J.N.S. by the Luso-American Educational Commission (Fulbright Program), the Instituto Nacional de Investigacao Científica (Portugal), and the Faculdade de Ciências da Universidade de Lisboa during several stages of this research is gratefully acknowledged. Financial support from the Ministerio de Educatión y Ciencia (Spain) in the form of a postdoctoral Fulbright/MEC fellowship to M.S. is also gratefully acknowledged. Research was supported by National Science Foundation Grant BSR-8415060 to R.K.K. This is contribution No. 736 from the Program in Ecology and Evolution, State University of New York at Stony Brook. On leave from Departamento de Biologia Vegetal, Faculdade de Ciências, Universidade de Lisboa, Campo Grande C2, Lisboa, Portugal.     

The major type-1 protein phosphatase catalytic subunits are the same gene products in rabbit skeletal muscle and rabbit liver

The catalytic subunit of protein phosphatase-1 (PP1) isolated from rabbit liver had the same electrophoretic mobility as, and yielded peptide maps identical to those of the 33 kDa form of rabbit skeletal muscle PP1. The predicted amino-acid sequences of PP1 obtained from three rabbit liver cDNA clones were identical to that of PP1 alpha from rabbit skeletal muscle. These findings suggest that the distinctive substrate specificities and regulatory properties of hepatic and skeletal muscle type-1 protein phosphatases are not conferred by the catalytic subunits themselves, but by regulatory subunits that are complexed to the catalytic subunits in vivo.