Rifomycin: XIII. Fermentation and Production of Rifomycin Complex

Rifomycin complex, a mixture of at least five different antibiotic principles, has been produced by submerged fermentation procedures in the laboratory and on pilot plant scale, using a semisynthetic medium. Difficulties were met with, due to the heterogeneity of the antibiotic principles. Mutation work led to the isolation of a strain that produced fractions C and D in greater amounts.     

Antigen-initiated B lymphocyte differentiation. XIV. Nonspecific effects of antigen stimulation cause proliferation in the "pre-progenitor" subset of primary B cells.

The effect of specific and nonspecific stimuli on the cycle status of subsets of primary B lymphocytes was assessed by preinjecting donor CBA mice 1 to 2 days previously with various substances, and then incubating the isolated spleen cells with high specific activity 3H-TdR before assay. AFC-progenitor activity was assessed as a response to NIP-POL antigen, either by adoptive transfer to irradiated recipients or by cell culture. Previous studies showed these assays reflected the activity of different subsets of B cells, termed "pre-progenitors" (adoptive assay) and "direct progenitors" (culture assay). Most functional primary B cells, whether assayed in culture or by adoptive transfer, were not initially in rapid cell cycle in normal adult mice. However, nonspecific stimulation for 1 day caused NIP-specific adoptive transfer IgM AFC-progenitors to enter rapid cell cycle. This effect was independent of T cells and not related to the antigenicity of the stimulus: particulate peritoneal irritants were the most effective stimulants. In contrast to adoptive transfer results. AFC-progenitors assayed in cell culture were unaffected by nonspecific stimuli, but were activated into cell cycle by specific antigen.     

Production of antibody against aflatoxin B1.

Antibody against aflatoxin B1 was obtained after one multiple-site injection of bovine serum albumin-aflatoxin B1 conjugate into rabbits. The antibody has greatest binding efficiency for aflatoxin B1, less efficiency for B2, G1, and Q1, and least for aflatoxicol, G2, and M1. Sterigmatocystin, coumarin, and 4-hydroxycoumarin did not give a cross-reaction with the antibody. The sensitivity of the binding assay for detection of aflatoxin B1 is in the range of 0.2 to 2.0 ng per 0.5-ml sample. Detailed methods for the preparation of the conjugate, production of immune serum, and methods for antibody titer determination are described.     

Species 39. Cisticola Tinniens. Pl. XIV.

A smallish, rather slender-built bird; quite a typical Cisticola like subruficapilla , which species despite its different coloration is-one of if not the nearest of its allies, about the same size, build and proportions as the Sardinian Warbler (S. melanocephala) and with much moreover in its behaviour which recalls that and other quite differently coloured bush-loving Sylvia Warblers, such as, for instance, the Whitethroat (S. communis).     

Activation of human B lymphocytes. XIV. Characterization of the precursor of the pokeweed mitogen-induced anti-sheep red blood cell plaque-forming cell.

The precursor of the pokeweed mitogen (PWM)-induced anti-sheep red blood cell (SRBC) plaque-forming cell (PFC) in human peripheral blood was characterized. By a variety of purification procedures, it was demonstrated to be a lymphocyte with surface characteristics of a B cell. Furthermore, it was demonstrated to bind to sheep erythrocytes (E) and thus segregated with the E-rosetting T cells when T cell enrichment was performed by differential fractionation of E-rosetting cells. This binding of the PFC precursor to E was blocked by pretreating the lymphocyte with anti-human Ig before E rosetting, indicating that the PFC precursor specifically bound to SRBC by a surface Ig molecule with binding specificity for sheep red blood cell determinants. Hence, the precursor of the PWM-triggered anti-SRBC PFC is a B lymphocyte with surface Ig expressing specificity for SRBC.     

The myosin filament XIV backbone structure.

The substructure of the thick filaments of chemically skinned chicken pectoralis muscle was investigated by electron microscopy. Images of transverse sections of the myosin filaments were determined to have threefold symmetry by cross-correlation analysis, which gives an unbiased determination of the rotational symmetry of the images. Resolution, using the phase residual test (Frank et al. 1981. Science [Wash. DC]. 214:1353-1355), was found to be between 3.2 and 3.6 nm. Three arrangements of nine subfilaments in the backbone were found in all regions of the filament at ionic strengths of 20 and 200 mM. In the average images of two of these, there were three dense central subfilaments and three pairs of subfilaments on the surface of the thick filament. In the average image of the third arrangement, all of the protein mass of the nine subfilaments was on the surface of the filament with three of them showing less variation in position than the others. A fourth arrangement appearing to be transitional between two of these was seen often at 200 mM ionic strength and only rarely at 20 mM. On average, the myosin subfilaments were parallel to the long axis of the filament. The different arrangements of subfilaments appear to be randomly distributed among the filaments in a transverse section of the A-band. Relative rotational orientations with respect to the hexagonal filament lattice, using the three densest subfilaments as reference showed a major clustering (32%) of filaments within one 10 degrees spread, a lesser clustering (15%) at 90 degrees to the first, and the remainder scattered thinly over the rest of the 120 degrees range. There was no obvious pattern of distribution of the two predominant orientations that could define a superlattice in the filament lattice.     

STUDIES ON BIOLUMINESCENCE : XIV. THE SPECIFICITY OF LUCIFERIN AND LUCIFERASE.

Among sixteen groups of luminous forms investigated by the author, in only four (fireflies, Pholas, ostracods, and Odontosyllis) is it possible to demonstrate the luciferin-luciferase reaction. In many groups this is probably due to the small amount of these substances present in the luminescent organism or to their instability. In the medusæ and pennatulids, despite a large amount of luminescent material, luciferin and luciferase cannot be demonstrated. This does not appear to be due to the presence of luciferin and luciferase in equivalent proportion, or to their instability. In fact, one is led to the conclusion that luciferin and luciferase do not exist in these forms, but such a conclusion must be regarded as merely tentative, in view of the fundamental character of the luciferin-luciferase reaction. Luciferin of one form will not luminesce with the luciferase of another form or vice versa, unless very closely related (Cypridina and Pyrocypris). All experiments emphasize the specificity of the light producing substances of Cypridina.