Esterases in mycobacteria

Esterases ofMycobacterium phlei isolated by means of Sephadex G-100 chromatography could be temporarily activated by adding calcium ions. This activation could not be brought about in crude enzyme preparations from cells or in crude extracts from the culture filtrate. It was demonstrated that compounds (or a compound) without the esterase activity isolated after the separation of crude enzyme preparations on Sephadex G-100 (peak C) are responsible for the above difference. It was found that the suppression by compounds from the “C peak” of the temporary activation of esterases with calcium ions depends most probably on the ratio of these compounds to the quantity of the enzyme rather than on their concentration. In addition, the compounds of the C peak themselves were found to activate esterases. The activation was lower than the temporary activation with calcium ions. The possible mechanisms of the temporary activation of esterases and the importance of these findings, from the point of view of regulation of the activity of esterases during submerged cultivation ofMycobacterium phlei, are discussed.     

The mechanism of pathogenicity ofPseudomonas aeruginosa

Extra-cellular proteinases ofPseudomonas aeruginosa toxic for larvae of the greater wax moth were separated from the culture filtrate by means of ammonium sulphate precipitation, chromatography on DEAE cellulose, gel filtration on Sephadex G-75 and preparative disc-electrophoresis respectively. The five proteinases isolated were characterized by pH optima, molecular weights, elastase and collagenase activities.     

The dynamics of the formation of virus-neutralizing,complement-fixing and immunofluorescent antibodies to the rabies virus in guinea pigs

The aim of the present work was to establish the dynamics of the formation of virus-neutralizing (VN), complement-fixing (CF) and immunofluorescent (IF) antibodies in guinea pig antisera or fractions (IgM, IgG, 7S γ-2 7S γ-1 and F-fraction) obtained by gel filtration on a G-200 Sephadex column, or by chromatography on DEAE cellulose. It was shown that (I) there exists a correlation between the development and titres of VN and IF antibodies. This correlation was observed in both whole serum and its fractions IgG, 7S γ-2 and 7S γ-1 during the whole experimental period. (2) The formation of CF antibodies, followed a different pattern in comparison with VN and IF antibodies. (3) VN, IF and CF antibodies were found to be bound to the IgG fraction, and most of the activity was found in subfraction 7S γ-2. The subfraction 7S γ-1 possessed approximately one half of the activity of fraction 7S γ-2 as regards VN and IF antibodies, and almost no activity of CF antibodies. (4) Both VN and CF antibodies, present in the IgM fraction, reached the maximum in the second blood sample, i.e. 14 days after the first dose of virulent virus. In the further course of the antibody response in guinea pigs, the curve of VN, IF and CF antibodies showed a reversed trend in the whole serum rather than in the IgM fraction.     

Presence of allotypic determinants on polypeptide subunits of rabbit gamma globulin

Inhibition of passive haemagglutination showed the presence of the allotypic specificities Aa1 Aa2, Aa3, Ab4, Ab5 and Ab6 on polypeptide subunits of rabbit IgG belonging to the phenotypes Aa1-3/Ab4-4 Aa2-2/Ab4-4, Aa3-3/Ab4-4, Aa3-3/Ab4-5 and Aa3-3/Ab4-6, prepared by oxidative sulphitolysis followed by isolation on Sephadex G-100 in 6m urea and 0.05m formic acid. The determinants Aa1, Aa2 and Aa3 were found only on H chains and Ab4, Ab5 and Ab6 only on L chains. Of the latter, Ab4 and Ab5 were found in both fractions, i.e. L₁ and L₂, of the light chains, while Ab6 was found only in fraction L₁.     

Changes in DNA-dependent RNA polymerase in sporulating yeast

Diploid yeast cells can be made to undergo sporulation and meiosis in a relatively synchronous fashion. Earlier studies on this process showed that the rate of RNA synthesis reaches a maximum at 6 hr and has declined drastically by 10 hr [5]. Starting at about 6 hr a new peak of RNA polymerase activity appears between polymerases Ib and II upon DEAE Sephadex chromatography. This peak appears to reach a maximum at 8.5 hr and to have decreased by 10 hr. The new peak is intermediate between polymerases Ib and II in its sensitivity to α-amanitin. It does not appear in a non-sporulating (αα) diploid grown under sporulating conditions.     

Neutralization of bacterial viruses by antibodies of young animals

The cofactor activity of complement of precolostral newborn pig serum was compared with the haemolytic and bactericidal activity. Using current decomplementation treatment it was found that all three types of activity are destroyed in parallel i.e. haemolytic, bactericidal and cofactor (heat inactivation, EDTA, ammonia, trypsin, adsorption to zymosan or immune precipitate). In an ultracentrifugation analysis the haemolytic, bactericidal and cofactor activities showed the same sedimentation pattern. Using gel filtration on a Sephadex G 200 column, the cofactor activity was found in the fraction which contained all basic complement components. On the basis of these results it can be concluded that the complement of piglet serum acts as a factor which potentiates the neutralization of bacteriophage by the sera of the newborn.     

Solid-phase synthesis of ragweed allergen Ra5

A two-stage strategy was used to synthesize the 45-residue, four-disulfide-bonded ragweed protein allergen Ra5: (i) the protected linear chain was prepared by solid-phase, stepwise synthesis according to the sequence of the fully reduced protein; (ii) after removal from the resin and deprotection by hydrogen fluoride, the reduced chain was purified by gel filtration on Sephadex G-50 and allowed to fold “spontaneously” in the presence of oxidized dithiothreitol to form the disulfide links. The product (synthetic Ra5) was purified to disc-electrophoretic homogeneity by cycling through Sephadex G-50 and CM-Sephadex (overall yield: 6% theoretical). Synthetic Ra5 was closely similar in structure to the natural protein by amino acid analysis. polyacrylamide gel electrophoresis, tryptic peptide mapping, and circular dichroism spectra, as well asin vitro andin vivo immunoassays of antigenic/allergenic activities.     

Immune response in human subjects at high altitude

Levels of immunoglobulins were determined in persons exposed to high altitude. The individuals studied included high altitude natives, sea level residents at high altitude for 2 years, and recent arrivals at high altitude. Increased IgG and IgA levels were found in high altitude natives and sea level residents at high altitude for 2 years when compared with sea level residents. In recent arrivals marked increase of IgG and IgG levels and slight rise in IgM was seen. Recent arrivals who suffered from high altitude pulmonary oedema showed marked elevation of IgG, IgM, and IgA. Immunoglobulin responses to both primary and secondary TAB inoculation were of a higher magnitude and more sustained at high altitude than at sea level.     

The role of homoeologous group 1 chromosomes in the control of rRNA genes in wheat

The presence of rRNA genes on homoeologous chromosomes 1A, 1B, and 1D of hexaploid wheat was investigated by rRNA/DNA hybridization, using DNA purified from aneuploid and substitution line derivatives of the variety Chinese Spring. Doubling the number of 1B chromosomes increased the number of rRNA genes by 31–49% but deleting the 1B chromosomes decreased the number by only 15–23%. This suggests that changes may occur in rRNA gene multiplicity at other nucleolar organizer sites to partially compensate for a deficiency of rRNA genes. There was no unequivocal evidence of rRNA genes on Chinese Spring chromosome 1A or 1D, but other varieties were shown to have rRNA genes on chromosome 1A. These results are consistent with the cytological observations that chromosomes 1A and 1B but not 1D possess nucleolar organizers.     

NaturalMycoplasma arthritidis infection in mice

B6C3F₁ mice from a hybrid production colony frequently were serologically positive by enzyme-linked immunosorbent assay (ELISA) and consistently negative by culture forMycoplasma pulmonis. Subsequently, 162 mice were obtained and intensively studied using an expanded group of cultural procedures, ELISA, and histopathology. Lesions attributable to mycoplasma infection were not found, butMycoplasma arthritidis was isolated from 20 mice. TheM. pulmonis ELISA was positive (IgM, IgG, or both) in 113 mice. Selected sera were tested simultaneously in both theM. pulmonis ELISA and in an ELISA usingM. arthritidis antigen, and were found to be positive in both the IgM and IgG classes in both ELISAs. Thus, cross-reacting antibody was produced in mice naturally infected withM. arthritidis, confirming previous observations based on experimental infections. To our knowledge, this is the first report of naturalM. arthritidis infection in laboratory mice.