Search for a relationship between molecular anomalies of the mutant erythrocyte pyruvate kinase variants and their pathological expression

Summary Anomalies of the mutant pyruvate kinase variants and clinical symptoms have been compared in 22 unrelated patients with congenital red cell pyruvate kinase deficiency. This study suggests that some characteristics of the mutant enzymes could play a role in the intensity of haemolysis, namely residual activity, affinity for the substrate phosphoenolpyruvate and for the allosteric activator fructose 1,6 diphosphate and inhibition by ATP.     

Isolation and partial characterization of phages infectingCitrobacter intermedius C3

Several new bacteriophages infecting strain C3 ofCitrobacter intermedius have been isolated from fresh waters. The physicochemical properties, plaque morphology, growth characteristics, virion structure, and immunology of eight bacteriophage isolates are reported. The phages are classified into three groups according to their characteristics.     

Distribution of intermediate filaments in amphibian oxyntic cells

Summary Intermediate filaments of toad oxyntic cells were isolated and analysed by SDS-PAGE. The major proteins of the residue were identified as actin and a 51,000 dalton polypeptide. Immunological crossreactivity between toad oxyntic cell intermediate filament components and anti-prekeratin, was shown by double immunodiffusion tests and indirect immunofluorescence. The immunofluorescent decoration of oxyntic cells and the electron microscope images are coincident in locating the intermediate filaments mainly at the cortical and perinuclear basal zones. Furthermore, the cortical zone appears especially rich in prekeratin-like material at its adluminal third. This results in a cup-like structure that encloses the cell portion occupied by the tubulovesicular system, which does not contain intermediate filaments. The translocation of membranes occurring during the secretory cycle of the oxyntic cell, has been attributed to a system of contractile proteins. The disposition of the prekeratin-like material suggests a role for intermediate filaments in the generation of movement, produced by actin and myosin interaction, by providing a fixed plane for the anchoring of actin microfilaments.     

Surface-decontaminating action of glutaraldehyde in the gas-aerosol phase.

The surface disinfectant effect of glutaraldehyde in the gas-aerosol phase was investigated at different relative humidities and temperatures. At a gas-aerosol concentration of 15 to 20 mg/m3 and a relative humidity of about 80%, glutaraldehyde had a good disinfectant effect against both vegetative bacteria (decimal reduction time, less than 5 min) and bacterial spores (decimal reduction time, less than 45 min). In spite of its low volatility, glutaraldehyde was more effective than formaldehyde when the two substances were compared on an "added amount" basis.     

1,3-β-Glucan synthase from Citrus phloem

1,3-β-Glucan synthase activity has been demonstrated in particulate fractions of bark extracts from Mexican lime. With respect to substrate, the enzyme kinetics did not conform to the Michaelis-Menten equation. The value of the Hill coefficient was 1.2 and S_0.5 is 1.1 mM. The enzyme had an optimum pH of 7.5. Maltose, sucrose, and especially cellobiose and glucose, were enzyme activators when tested at physiological concentrations. In the presence of 15 mM MgCl₂ the enzymic activity was stimulated at 10 μM UDP-glucose but decreased at 1 mM UDP-glucose, suggesting a minor 1,4-β-glucan synthase activity.     

Nonsense and insertion mutants in the relA gene of E. coli: cloning relA.

We have made use of lysogens of a specialized transducing bacteriophage, lambdapyrG+ relA+, to select nonsense (relAnon) and insertion (relAins) mutations in the relA gene. Three independent relAnon mutants were isolated on the phage. In all three, the relaxed phenotype was suppressed by supD, supE, supF or sup6. Three independent relAins mutants were isolated, all containing an insertion element (probably IS2) in an apparently identical location in the relA gene. Polyacrylamide gel electrophoretic analysis of peptides synthesized by the phages in ultraviolet lightkilled host cells revealed that no stringent factor was coded for by either the relAins or relAnon phages (the latter in a sup+ cell); stringent factor was detected when the relAnon phages were used in a similar experiment with supD or supE host cells. The relAnon and relAins mutations could be crossed in haploid form in the E. coli chromosome. These recombinants grew with a normal doubling time, had a ppGpp pool which was between 70 and 100% compared with the classical relA strain, and underwent a normal carbon source shift-down. A restriction endonuclease map of the pyrG relA region of the specialized transducing phage is presented in which the position of the insertion element (recognized by a novel Hind III-cut site) defines the position of the relA gene. This position was verified by an analysis of the structure of five plasmids formed by cloning portions of the region in the pBR322 cloning vehicle. Our results indicate that the relA gene is not an essential cellular function, that there might be a second mechanism for the synthesis of basal level ppGpp in the cell and that the sole function of the relA gene is apparently the high level ppGpp synthesis triggered in response to deacylated tRNA.     

A thermodynamic analysis of the interaction between the mitochondrial coupling adenosine triphosphatase and its naturally occurring inhibitor protein

1. The naturally occurring ATPase (adenosine triphosphatase)-inhibitor protein, from bovine heart mitochondria, was obtained as a single pure protein. It was not identical with any of the five subunits (alpha-epsilon) of the isolated ATPase, and appeared to be a single polypeptide chain. 2. The inhibitor combined with the ATPase in a 1:1 molar ratio, producing a completely inhibited ATPase molecule. The affinity of the ATPase for its inhibitor is high; the K(d) is of the order of 10(-8)m. 3. The enthalpy of the ATPase-inhibitor complex-formation is positive, the value of K(d) decreasing as the temperature is raised. This suggests that the forces involved are largely hydrophobic in nature. 4. Hydrolysis of a nucleoside triphosphate promoted formation of the ATPase-inhibitor complex, although the equilibrium position was almost unaffected by the rate of hydrolysis. At low salt concentration, less than 200 turnovers of the ATPase suffice for the ATPase to combine with the inhibitor protein. At higher salt concentrations, a larger number of turnovers is required. It is suggested that the inhibitor binds to a form of the ATPase that is produced transiently during hydrolysis. 5. In the presence of 75mm-K(2)SO(4), the rates of association and dissociation are slow enough to allow their kinetics to be studied. Association is first-order in inhibitor concentration, but fractional order in ATPase concentration. Dissociation is first-order in ATPase-inhibitor complex concentration. The temperature coefficients of the ;on' and ;off' processes were also measured. 6. A simple kinetic model for the ATPase-inhibitor interaction is proposed that can be extended to take into account release of inhibitor protein under energized conditions on the membrane. 7. The isolated ATPase is inhibited by preincubation with Mg(2+), reversible by subsequent addition of EDTA, and by ADP, reversible by subsequent addition of ATP. These effects are not found on the membrane-bound ATPase. The mechanism of these effects is discussed.     

Ergasiophygophytes and xenophytes of East Asiatic origin in Adjaria a stimulus to new terminology,especially for ergasiophygophytes

Studies of the Adjarian flora resulted in a detailed classification of the ergasiophygophytes, based mainly on the degree of their naturalization: (1) The ephemeroergasiophygophytes display unstable naturalization both in artificial and natural habitats, and disappear after only a few growing seasons. (2) The deuteroergasiophygophtes show stable naturalization in anthropogenic habitats. (3) The protoergasiophygophytes are distinguished by uncertain stability of naturalization in natural habitats, and, if firmly naturalized on a certain spot, they lack any tendency to further spreading. (4) The autergasiophygophytes tend to spread in natural habitats. (5) The aggressive ergasiophygophytes transform natural vegetation in new plant communities, and can become dominant species in these communities. New terms, viz. emphemeroxenophytes, protoneophytes, non-aggressive neophytes, slightly aggressive neophytes, and postneophytes with vegetative reproduction have also been introduced to express diverse features of the xenophytes.     

中国晚期旧石器的碳-14断代和问题

根据已公布的47个碳-14数据,进而分析10处中国晚期遗址的年代和问题,并提出不同的看法。文中强调:露天遗址中碳-14数据的异常现象,往往与各种原因形成的再次堆积有关。因此必须注意样品的采集和避免引用孤零的碳-14数据,同时还要结合地层和文化性质的分析,才可能保证断代的准确性。