Effects of antibiotics on synthesis and persistence of sigma E in sporulating Bacillus subtilis.

A potential regulatory link between the activation of a sporulation-specific sigma factor (sigma E) and forespore septum formation was investigated by treating Bacillus subtilis with inhibitors of protein or peptidoglycan synthesis and monitoring the consequences of these treatments on sigma E activation and septation. Western blot (immunoblot) and electron microscopic analyses revealed that both the formation of sigma E and septation were inhibited to a similar degree when either rifampin or chloramphenicol was added at different times before the second hour into sporulation but that penicillin preferentially blocked septation. We interpret these results as indicating that the syntheses of the gene products for both septation and sigma E activation occur at approximately the same time in development but that synthesis of an intact septum is unlikely to be a prerequisite for the formation of sigma E. We observed that penicillin could not only block septation but, depending on the time of its addition, could also inhibit both the activation of sigma E and the synthesis of its precursor. The basis of this effect is unknown, but it is not due to an overall disruption of protein synthesis. The incorporation of [35S] methionine by the sporulating cultures was unaffected by penicillin treatment. A time course study of the effects of rifampin and chloramphenicol treatments on sigma E levels revealed that both the synthesis of sigma E and its disappearance from sporulating cultures is inhibited by these antibiotics. This suggests that ongoing macromolecular synthesis is required for the turnover of sigma E.     

A simple,rapid assay for cysteamine and other thiols

Cysteamine is under investigation as an aid in radiation therapy and as a treatment for the inherited disorder cystinosis. An assay is presented for its measurement in biological fluids. The specific reaction of thiosulfonates with sulfhydryl compounds is employed to form a radiolabeled derivative of cysteamine which is then isolated by high-voltage electrophoresis on paper. Cysteamine can be measured in aqueous solutions, plasma, and urine with this method.     

The protein-A plaque assay: a new system for the detection of cells secreting a given idiotype

With a modification of the protein-A plaque assay, cells secreting a given idiotype could be detected. Different anti-idiotypic antisera raised against the M-component of macroglobulinemia Waldenstr?m patients were used. The antibodies did not cross-react with cell clones of other patients or normal controls. Spontaneous plaques, without prior cultivation, were mainly shown to be of IgM class, the majority being idiotype specific, in blood and bone marrow lymphocytes from these patients. This is in contrast to the predominance of Ig or IgA found in normal blood donors. A low but recognizable stimulation of the malignant clone may be observed when cells were stimulated by certain polyclonal B cell activators.     

Biologically related iron-sulfur clusters as reaction centers. Reduction of acetylene to ethylene in systems based on [Fe4S4(SR)4]3-

The possibility that clusters containing the Fe4S4 core unit found in a wide variety of proteins can effect reductive transformations of Fe-S enzyme substrates has been investigated using the reduced synthetic clusters [Fe4S4(SPh)4]3- and acetylene, an alternate nitrogenase substrate. The system [Fe4S4(SPh)4]3-/acetic acid/acetic anhydride in N-methylpyrollidinone at approximately 25 degrees was found to reduce acetylene homogeneously to ethylene, and in the presence of a deuterium source to afford as the principal stereochemical product cis-1,2-C2H2D2. No appreciable reduction was found using the oxidized cluster [Fe4S4(SPh)4]2-. The system is not catalytic and departs from the strict stoichiometry of the reaction, 2[Fe4S4(SPh)4]3- + C2H2 + 2H+ leads to 2 [Fe4S4(SPh)4]2- + C2H4, primarily because of a competing cluster oxidation reaction which could not be eliminated. Based on this reaction ca. 60% conversion of acetylene to ethylene was achieved. A reaction sequence based on absorption and 1H nmr spectral observations and product stereo-chemistry is suggested. The results demonstrate that biologically related, reduced Fe4S4 clusters can effect reduction of at least one Fe-S enzyme substrate, and raise the general possibility of substrate transformation with such clusters as reaction sites in biological systems.     

Fragile site long arm chromosome 16

Summary A fragile site at the long arms (q21) of chromosome 16 was found in two persons, each of whom became the parent of a child with a de novo structural chromosome abnormality—a balanced autosomal translocation and an autosomal deletion. The question of an increased risk of structural chromosome abnormalities in the offspring of persons with fragile site long arm 16 is discussed.     

Compound Autosomes in DROSOPHILA MELANOGASTER: The Meiotic Behavior of Compound Thirds

Studies of the meiotic distribution of compound-3 chromosomes in males and females of Drosophila melanogaster provided the following results. (1) From females homozygous for the standard arrangement of all chromosomes other than C(3L) and C(3R), less than 5% of the gametes recovered were nullosomic or disomic for compound-3 chromosomes. The frequency of nonsegregation differed between strains, but within a given strain it remained relatively constant. (2) According to egg-hatch frequencies, C(3L) and C(3R) segregate independently during spermatogenesis. (3) In females, structurally heterozygous second chromosomes occasion a marked increase in the recovery of nonsegregational progeny; in males, rearranged seconds have no apparent influence on the distribution of compound thirds. (4) The highest frequencies of nonsegregational progeny were recovered from C(3L);C(3R) females carrying compound-X (plus free Y) chromosomes. (5) In comparing the recovery of nonsegregating compound thirds to the recovery of rearranged heterologs, a definite nonrandom distribution was realized in several crosses. These results are examined in reference to the concepts of distributive pairing (Grell 1962). Moreover, considering the structural nature of compound autosomes, we propose that nonhomologous (distributive) pairing is a property of the centromeric region and suggest that rearrangements involving breaks in this region possibly alter the effectiveness of distributive pairing forces.     

Isolation and partial characterization of the major apolipoprotein component of bovine serum high density lipoprotein.

The delipidated protein component of bovine serum high density lipoprotein was fractionated by gel filtration on a Sephadex G-150 column (equilibrated with buffer containing 6 M urea) into three fractions: I, II and III. Fractions I and II together constitute 88% of all the protein weight of bovine high density lipoprotein, whereas fraction III accounts for the remaining 12%. Analysis of the fractions by sodium dodecyl sulfate-polyacrylamide electrophoresis reveals that fraction I consists mostly of aggregated forms of fraction II and some higher molecular weight species, probably irreversible aggregates of fraction II. The irreversible aggregates are apparently formed during the delipidation procedure or upon aging of the lipoprotein. The major protein component of the high density bovine lipoprotein is found in fraction II; it has a molecular weight of 27 000 plus or minus 1500 and appears to be homogeneous by several physicochemical criteria. The amino acid composition of fractions I and II are essentially identical; their spectral properties, including absorption, fluorescence, and circular dichroism spectra, are similar; however, fraction I appears to contain traces of oxidized lipid and more secondary alpha-helical organization than fraction II. By comparison with the intact lipoprotein, which contains about 65% of alpha-helical structure, fractions I and II have diminished alpha-helical organization, 55% and 43%, respectively. Fraction III, on sodium dodecyl sulfate-polyacrylamide electrophoresis, separates into two protein bands of equivalent intensity, having molecular weights around 13 000 and 11 000. Fraction III is markedly distinct from the other two, in amino acid composition and spectral properties, especially in its red-shifted fluorescence and very low content of alpha-helical structure. The protein composition of bovine serum high density lipoprotein is compared with recently published results for high density lipoprotein apoproteins of man, chimpanzee, rhesus monkey, pig and rat. Similarities and differences are discussed in terms of possible evolutionary and functional factors.     

Prevalence of Edwards' syndrome. Clustering and seasonal variation?

Summary The incidence of Edwards' syndrome was found to be 1 per 4857 newborn children of 34000 consecutively newborn children in two Danish counties. Six of the 7 cases were born during the months of February through April.The incidence was high compared with the expected incidence of Edwards' syndrome of approximately 1 per 10000. This might be due to clustering in the area studied during the period 1967 to 1973.The finding of variations in incidence of children with Edwards' syndrome in different parts of the world, as well as the finding of seasonal variation in birth of such children, indicates that some of the etiological factors of nondisjunction of chromosome 18 are of an environmental nature.     

Die Hefewuchsstoffe in Maiskeimlingen

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