Preparation and Properties of Antibodies to GD3 and GM1 Gangliosides

Abstract: Gangliosides G_D3 and G_M1 were coupled to proteins by their car-boxyl groups and antisera were raised against the complexes. Anti-ganglioside antibodies were isolated by affinity chromatography on ganglioside-amino-propyl silica gel columns and the specificity of the antibodies was determined by a quantitative microcomplement fixation assay. Antibodies to G_D3 were highly specific and did not crossreact with G_M3, lactosyl ceramide, or other glycolipids. Purified antibodies to G_M1, in contrast, crossreacted with asialo-G_M1, G_D1b and to a lesser extent, G_M2 and asialo-G_M2. A derivative of G_M1, containing a C-7 sialic acid residue produced by periodate oxidation, reacted with the anti-G_M1 antibodies almost as readily as with G_M1. The specificities of anti-G_M1 antibodies elicited by the covalent ganglioside-protein complexes were similar to those produced by immunization with noncovalent complexes of G_M1 and methylated bovine serum albumin. The ganglioside-protein complexes described here should be useful for preparing antibodies to polysialo-gangliosides that contain neuraminidase-sensitive linkages.     

On the evolutionary significance of Mendel's ratios

Length of time in polymorphism is investigated as a possible evolutionary criterion for Mendel's laws in the case of two alleles at one locus and finite population. Deterministic models with constant and random segregation schemes are investigated. In deterministic models the optimum segregation system depends on the zygotic selection and is Mendelian only in symmetric models. In finite population models the initial gene frequencies interact with the segregation to determine mean time to fixation. In deterministic models with random distortion reduction of the variance of the distortion is more likely to produce polymorphism.     

Polyribosome Isolation in the Presence of Diethyl Pyrocarbonate

Isolation of polyribosomes from wheat embryos and corn root tips in the presence of diethyl pyrocarbonate showed this reagent to have a protective effect on polyribosome structure. In addition, the use of diethyl pyrocarbonate allowed initial homogenization to be performed under less stringent conditions than those normally employed for polyribosome isolation. The use of the reagent is however limited, in that it is deleterious to in vitro ribosomal amino acid incorporation.     

Escherichia coli Field Contamination of Pecan Nuts

More pecan samples collected from grazed orchards were contaminated with Escherichia coli than were samples from nongrazed orchards. No differences in frequency of contamination between mechanically and manually harvested nuts occurred. Nutmeats from whole uncracked pecans that were soaked for 24 h in a lactose broth solution containing E. coli did not become contaminated. Twentyfour percent of the whole pecans soaked in water for 48 h to simulate standing in a rain puddle developed openings along shell suture lines which did not completely close when the nuts were redried.     

Noninvolvement of Acyl Carrier Protein with Citrate Synthase and Malate Synthase

Acyl carrier protein (ACP coli) was isolated from commercially grown Escherichia coli B and was acetylated by chemical methods. Biological activity of the synthesized acetyl-ACP coli was checked in an in vitro fatty acid-synthesizing system isolated from E. coli B. Since acetyl-ACP is preferred over acetyl-coenzyme A (CoA) as a substrate in these reactions, the possibility that it may substitute for acetyl-CoA in biosynthetically and oxidatively important cellular pathways (glyoxylate and Krebs cycles, respectively) was examined. Acetyl-ACP was tested for substrate activity with the enzyme of each cycle which has been found to utilize acetyl-CoA. Crystalline citrate synthase (EC 4.1.3.7) of porcine origin (Calbiochem) was found to be inactive with acetyl-ACP coli, which acted neither as a substrate nor as an inhibitor in the presence of acetyl-CoA. Malate synthase (EC 4.1.3.2) of the acetate type was isolated from acetate-grown cells of a mutant of E. coli K-12 (VGD(3)H(5)) and was also found to be inactive with acetyl-ACP coli. The significance of these results and of the recent discovery of another phospho-pantetheine-containing protein are discussed.     

DYNAMICS OF ACRIDINE ORANGE-CELL INTERACTION : I. Interrelationships of Acridine Orange Particles and Cytoplasmic Reddening

The in vitro localization of acridine orange (AO) in living cells was monitored by means of fluorescence microscopy, quantitative cell viability studies, and photofluorimetric measurements following dye-cell interaction. The parameters, pH, time, dye concentration, and the metabolic state of the cell were found to exert a profound influence on the time course and distribution of staining. The parameters studied are mutually interdependent, and intracellular dye localization may be predictably altered by their appropriate manipulation. Conditions are defined whereby two morphologically distinct but physiologically interrelated reactions, namely, acridine orange particle (AOP) formation and cytoplasmic reddening (CR) may be caused, prevented, reversed, or modified. These results are explained in terms of the facilitation or inhibition of an intracytoplasmic dye-segregating mechanism, in turn affected by the rate of dye ingress and the physiological state of the cell. Whereas the accumulation of AO in AOP is compatible with cell viability, the appearance of CR is correlated with cell death. It is pointed out that meaningful interpretation of vital staining requires precise regulation of many parameters in the extracellular milieu. A scheme of cell compartmentalization with respect to AO is proposed to satisfactorily account for the effects of environmental variations on the distribution and ultimate fate of intracellular dye. The AOP are viewed as normally present acid phosphatase-positive multivesicular bodies.     

Studies on Bacterial Pyrogenicity: III. Specificity of the United States Pharmacopeia Rabbit Pyrogen Test

The specificity of the first or “presumptive” portion of the USP rabbit pyrogen test was investigated by use of a new absolute standard of reference. The reference standard was a 0.9% sodium chloride solution prepared to be pyrogen-free. Details of the preparation were described. The hypothesis was explored that the temperature response of rabbits after intravenous injection of the standard solution was independent of exogenous pyrogen. Reactions observed among the rabbits in our colony allowed a classification of these animals ranging from “consistently reliable” to “consistently unreliable.” Details of the experimental results and implications for pyrogen testing are discussed. The recommendation was made that all rabbit test animals be “screened” in sham and actual tests before being used for pyrogen testing.