A silent gene (C3-) producing partial deficiency of the third component of human complement

A family is described with 3 members in 3 generations being heterozygous for the silent gene C3-: one girl, her mother and grandfather had half normal C3 levels and were apparently incompatible homozygous. No significant deviation in the total hemolytic complement activity, serum concentration of Bf and C4 component was found in the affected individuals.     

Bacterial induction and inhibition of a fast mecrotic response in Gracilaria conferta (Rhodophyta)

Of 45 bacterial isolates from healthy tips of Gracilaria conferta (Schousboe ex Montagne) J. et G. Feldmann, 29% were identified as ‘conditional inducers’ of an apical necrosis. That is, the isolates induced necrotic tips in G. conferta within 16 h after elimination of most of the resident microflora from the alga. Several disinfectants and antibiotics were screened for their ability to induce algal susceptibility to the bacteria and to suppress uncontrolled appearance of tip necrosis. Treatment with 100 mg L^-1 Cefotaxim + 100 mg L^-1Vancomycin over three days was the least damaging and most efficient. Tip necrosis was related to isolates of the Corynebacterium-Arthrobacter-group and to the Flavobacterium-Cytophaga-group. The damaging effect occurred due to the bacterial excretion of active agents and was not correlated with acapability to degrade agar. The damaging influence of four Cytophaga-likestrains was inhibited by 20 of 40 isolates. This protective effect was caused by very different organisms. In five of six cases examined further, the effect was not cellbound, but due to the excretion of agents. These were not antimicrobially active, but inactivated necrosis-inducing excretions. These results indicate that epiphytic bacterial degradation or inactivation of damaging agents is a protecting factor in Gracilaria, which prevents the alga from being harmed by epiphytes. This revised version was published online in August 2006 with corrections to the Cover Date.     

The survival probability of a mutant in a multidimensional population

We prove a general result about the asymptotic behaviour of the survival probability of a slightly supercritical multitype Bienaymé-Galton-Watson branching process. This is the complete analogue of a result which Ewens (1968) obtained for a Poisson branching process.Research supported by NSERC     

Amino acid sequence of the proteolipid subunit of the proton-translocating ATPase complex from the thermophilic bacterium PS-3

The proteolipid subunit of the ATPase complex was identified in whole membranes of the thermophilic bacterium PS-3 by means of a covalent modification with the 14C-labelled inhibitor dicyclohexylcarbodiimide. The proteolipid could be purified from the membrane in free and carbodiimide-modified form by extraction with chloroform/methanol and subsequent carboxymethylcellulose chromatography in mixtures of chloroform/methanol/water. The complete amino acid sequence of the 72-residue polypeptide could be determined by automated solid-phase Edman degradation of the whole protein, and of fragments obtained after cleavage with cyanogen bromide and N-bromosuccinimide. Chemical cleavages and separations of the resulting fragments by gel chromatography were performed in 80% formic acid. The amino acid sequence shows a concentration of hydrophobic amino acids in two segments of about 25 residues at the amino-terminal and carboxy-terminal ends. The polar residues are clustered in the middle of the polypeptide chain. The bound [14C]dicyclohexylcarbodiimide label is recovered exclusively at position 56, which is occupied by a glutamyl residue. The proteolipid from PS-3 exhibits homology to the corresponding ATPase subunit from mitochondria. The carbodiimide-reactive glutamyl residue occurs at the position as in the mitochondrial proteins.     

Three-dimensional reconstruction and averaging of 30 S ribosomal subunits of Escherichia coli from electron micrographs

From the micrographs of a tilt series, several particles of negatively stained 30 S ribosomal subunits of Escherichia coli were three-dimensionally reconstructed. Three of them showing similar orientation with respect to the supporting foil were averaged after alignment by newly developed three-dimensional correlation methods. As a main result we found a stained channel-like structure inside the particle. We tentatively propose that this corresponds, at least partially, to positively stained segments of the 16 S RNA.     

Secretion of Extracellular Enzymes by Verticillium psalliotae Treschow and Verticillium lecanii (Zimm.) Viégas During Growth on Uredospores of the Soybean Rust Fungus (Phakopsora pachyrhizi Syd.) in Liquid Cultures

Two isolates of the mycoparasite Verticillium psalliotae grew rapidly in liquid cultures on autoclaved uredospores of the soybean rust fungus (Phakopsora pachyrhizi Syd.) as sole carbon source and secreted β-l,3-glucanase, chitinase, and protease activities into the medium. One isolate of Verticillium lecanii grew slowly, failed to produce measurable chitinase activity and secreted lower specific activities of β-l,3-glucanase and protease, compared with V. psalliotae. The tested isolates of V. psalliotae and V. lecanii produced comparable levels of lipolytic activity. Amylolytic activity was secreted by V. lecanii but not by V. psalliotae. The isolates of V. psalliotae and V. lecanii used in our experiments differed clearly in protein and protease pattern, determined by electrophoresis on polyacrylamide gels. The results indicate that the rapid growth of V. psalliotae on autoclaved uredospores in liquid culture and on uredosori is probably based primarily on nutrients made available to the mycoparasite by activities of β-1,3-glucanases, chitinases and proteases.