On the evolution of the bacterial major sigma factors

Summary The existence of internal sequence homologies between the N-terminal halves of the gram-negative bacterial major sigma factors and their C-terminal halves, which correspond to minor factors, is reported. In the case of Escherichia-Salmonella sigma-70, an apparent homology was even found between the C-terminal helix-turn-helix DNA-binding motif and the corresponding region of the peptide N half, which, however, is not directly engaged in promoter recognition. It is proposed that major sigma factors may have originated by duplication and fusion of a DNA unit related to the ancestral gene for the whole sigma family. Coevolution of major sigma structures and complex promoters is suggested.     

Genetic polymorphism of erythrocyte histone H1 in Japanese quail

Histone H1 from erythrocytes of Japanese quail was resolved in a sodium dodecyl sulfate (SDS)-polyacrylamide gel into five fractions differing in apparent molecular weights. A polymorphism of histone H1.1, H1.2, and H1.3 bands was detected among quail individuals. While some birds possessed either a high (phenotype .3+) or a low (phenotype .3+/.3-) level of H1.3, at least half of the quail population lacked this H1 band (phenotype .3-). Appropriate genetic crosses demonstrated that H1.3 behaved as though it was coded by a gene with two codominant alleles at an autosomal locus. Using two-dimensional polyacrylamide gel electrophoresis (acid-urea followed by SDS gels), it was found that birds .3+ contained polypeptides H1.b1 and H1.b'1; birds .3-, polypeptides H1.b2 and H1.b'2 with lower apparent molecular weights; and birds .3+/.3-, both types of polypeptides in equal proportions. The H1.b2 + H1.b'2 complement was not discernible in SDS gels, for it migrated together with H1.c' within band H1.4. It was found that a small number of birds lacking the H1.2 band in SDS gels failed to express histone H1.a. Since birds with phenotype .2- with a defective allele of the gene H1.a were simultaneously lacking the H1.3 band, it seems that the imperfect allele of the H1.a gene might be closely linked to the alleles producing H1.b2 + H1.b'2.     

Tetracyclic triterpenes. Part VI [1] . The synthesis of 4,4,14α-Trimethyl-19 ( 10 → 9β) abeo-steroids. Synthons for the preparation of cucurbitacins

The effective synthesis of 4,4,14α-trimethyl-19 (10 → 9β) abeo-steroids (iv), (v), and (Vl) with two- and five-carbon side chains from lanosterol is described. Their structures were proved on the basis of spectral data. The title compounds are the first synthetic synthons for the preparation of 4,4,14α-trimethyl-steroids with an unnatural configuration.     

Microfluorometric filter determination of DNA in sucrose density gradients

A simple filter method for the fluorometric estimation of DNA in alkaline and neutral sucrose gradient fractions with DABA·2HCl is discussed. Alpha-450 membrane filters of regenerated cellulose (Gelman Instrument Co., Ann Arbor, Michigan) were used. In the proposed method washing of the DNA precipitate as well as the reaction with DABA·2HCl were performed directly on the filters, thus avoiding repeated washing and centrifugations of DNA precipitates applied hitherto in analogous fluorometric techniques. A good coincidence of the results concerning localization of DNA sedimentation profiles determined by radioisotopic and fluorometric methods was obtained. The method is very convenient for DNA estimation in alkaline and neutral sucrose density gradient fractions obtained by ultracentrifugation of DNA of nonproliferating cells where DNA labeling is very difficult, and in the case of human lymphocytes even impossible without stimulation for blastic transformation. Its other advantages are a considerably simplified procedure and a higher precision with respect to other fluorometric methods for determination of DNA.     

Uptake of immune RNA by normal mouse spleen cells

Summary Normal mouse spleen cells take up in vitro radioactively labeled immune RNA. RNA taken up is present in nuclei, polysomes, membranes and cytoplasm. About 20–40% of immune RNA is nonspecifically associated with cell surface. 45% of RNA taken up is degraded and reutilized inside the cells within 2 hours.This work was supported by the Polish Academy of Sciences within the project 09.7.4.1.1.     

Effect of photoperiod on development and fecundity in the flour moth, Ephestia kuehniella

Examination was made of the effect of alternating light and darkness (LD 12:12) and constant light (LL) conditions on length of development and fecundity of the moth, Ephestia kuehniella. It was found the conditions applied cause acceleration of larval development on an average by 3 days in comparison with development under constant darkness conditions (DD). The fecundity of the insects examined decreases considerably under the experimental conditions.When pharate adults are kept in light for 18 hr per 24-hr period on the 6th to 7th day of their development, males incapable of fertilizing females are produced.