Muscarinic acetylcholine receptors of the developing retina

Six- and 13-day chicken embryo retinas contain 10 and 320 fmol per mg of protein of specific binding sites for 3-[3H]quinuclidinyl benzilate, a ligand of muscarinic acetylcholine receptors. Most of the receptors of 13-day embryo retina were found, by autoradiography, to be localized in two sharp bands within the inner synaptic layer of the retina. In the adult, the receptors were found almost exclusively in three bands in the inner synaptic layer of the retina. A possible mechanism for generating sets of stratified or columnar neurons and relating one set to another is proposed.

Inhibition of Clostridium botulinum types A and B hemagglutinins by sugars

Chromatographically isolated hemagglutinins of Clostridium botulinum types A and B are serologically related but not identical. Of the sugars (5, 6, 12, 18 carbons, some derivatives, L and D forms) tested, only D-galactose and some of tis derivatives were inhibitors of these hemagglutinins. O-Nitrophenyl-beta-D-galactopyranoside and isopropyl-beta-D-thiogalactoside were the most potent inhibitors. The two hemagglutinins were bound tightly by p-aminophenyl-beta-D-thiogalactopyranoside coupled to CH-Sepharose 4B. The ligands to which these hemagglutinins bind were determined as the sugars which inhibited the hemagglutinating activity.

Improved procedure for crystallization of Clostridium botulinum type A toxic complexes

A modified protocol for the preparation of botulinum type A toxic crystals is decribed. The essential change was the substitution of chromatography on diethylaminoethyl-Sephadex for the step in which toxin was precipitated with ethanol. Colored materials and nucleic acids were removed by the chromatography so that crystal lots of greater uniformity could be produced. Significantly more of toxin in the starting culture was recovered as crystals. The lots of crystals obtained initially by either the original or the modified method contained an antigen that was eliminated when the lots were recrystallized.

Molecular forms of neurotoxins in proteolytic Clostridium botulinum type B cultures

A modified purification method was used to isolate the neurotoxin of proteolytic Clostridium botulinum type B strain Lamanna. The preparation was found to be a mixture of two protein forms. They were of molecular weight 152,000 and could not be separated by ion-exchange chromatography or electrophoresis in polyacrylamide gel. One was a single polypeptide chain, and the other was a dichain molecule (nicked toxin) held together by an interchain disulfide bond(s). Trypsinization increased the toxicity of the toxin preparation and converted the single-chain molecules into dichain forms that were indistinguishable from the endogenously generated nicked toxin. A protease of the type B culture, with substrate specificity similar to that of trypsin, did not change detectably the molecular form of unnicked type E toxin, although toxicity was increased. Higher toxicity was obtained when unnicked type E was trypsinized; the resulting preparation contained only nicked toxin molecules.

Growth potential of Clostridium botulinum in fresh mushrooms packaged in semipermeable plastic film

Fresh mushrooms (Agaricus bisporus) were inoculated in the stem, gill, or cap with Clostridium botulinum spores. They were placed with uninoculated mushrooms in paper board trays, which were then covered and sealed in a polyvinyl chloride stretch film to simulate prepackaged mushrooms available at retail stores. When incubated at 20 C, botulinum toxin could be detected as early as day 3, or 4, when the mushrooms still appear edible. Mushrooms inoculated in the stem with 1,000 type A spores frequently became botulinogenic; higher spore levels were needed if gills or caps were inoculation sites. Type B spores were less apt to produce toxic mushrooms. Respiration of the fresh mushrooms used up O2 more rapidly than could enter through the semipermeable wrapping film, so that the equilibrium O2 concentration became low enough for growth of C. botulinum. Inoculated mushrooms did not become botulinogenic when held at 4 C.

Detection of Clostridium botulinum toxin by local paralysis elicited with intramuscular challenge

Clostridium botulinum toxin can be identified by a characteristic, acute local paralysis that follows its injection into the gastrocnemius ("calf" muscle) of mice. The local botulism can be elicited with slightly less than one-tenth the toxin amount that is needed to kill mice by the intraperitoneal (i.p.) challenge route. The practical sensitivities of the intramuscular (i.m.) versus i.p. tests are about equal, however, because maximum sample volume injectable i.m. is 0.1 ml as compared to the 0.5-ml range that can be given i.p. i.m. injection of 10 or more mouse i.p. mean lethal doses causes paralysis in about 1 h, and an i.m. injection of about 0.5 i.p. mean lethal doses causes paralysis in 3 to 4 h. Toxin neutralization by homologous type of antitoxin only can be demonstrated with an incubated mixture of toxin and antitoxin. Although not as convenient as the i.p. method for routine use to detect botulinum toxin, the i.m. method has characteristics which could make it a useful supplement to the presently accepted i.p. procedure.

Interconversion between different states of affinity for acetylcholine of the cholinergic receptor protein from Torpedo marmorata

In receptor-rich membrane fragments from Torpedo, acetylcholine binds, in the presence of 70 muM Tetram, to a homogeneous population of high-affinity sites with Kd = (3.4 +/- 0.8) x 10(08) M. Dissolution of these membrane fragments by sodium cholate causes a decrease of affinity associated with the appearance of medium-affinity (Kd approximately 10(-7) M) and low-affinity (Kd greater than or equal to 10(-6) M) sites. Dissolution by neutral detergents Triton X-100 or Emulphogene preserves the high affinity of the acetylcholine binding sites. In all the soluble states of the receptor protein, Ca2+ ions and local anaesthetics no longer enhance the affinity for acetylcholine. Elimination of sodium cholate by dilution leads to the reassociation of the receptor protein, the recovery of high-affinity sites and the control by Ca2+ ions and local anaesthetics. Purification by affinity chromatography of the receptor protein in Triton X-100 is accompanied by a conversion of a majority of the acetylcholine sites into their state of low affinity. High-affinity sites can no longer be recovered by detergent dilution from these low-affinity ones.

Structural determination of glucans from Streptococcus mutans JC-2 (dental caries bacterium) by carbon-13 nuclear magnetic resonance

The 13C NMR spectra of glucans from Streptococcus mutans JC-2 show that those glucans have alpha-(1,3) and alpha-(1,6) linkages.

Purification and properties of Clostridium botulinum type F toxin

Clostridium botulinum type F toxin of proteolytic Langeland strain was purified. Toxin in whole cultures was precipitated with (NH4)2SO4. Extract of the precipitate was successively chromatographed on diethylaminoethyl-cellulose at pH 6,0, O-(carboxymethyl) cellulose at pH 4.9, and finally diethylaminoethyl-cellulose at pH 8.1. The procedure recovered 14 percent of the toxin assayed in the starting culture. The toxin was homogeneous by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, double gel diffusion serology, and isoelectric focusing. Purified toxin had a molecular weight of 150,000 by gel filtration and 155,000 by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Specific toxicity was 9.6 X 10-6 mean lethal doses per absorbancy (278 nm) unit. Sub-units of 105,000 and 56,000 molecular weight are found when purified toxin is treated with a disulfide reducing agent and electrophoresed on sodium dodecyl sulfate-polyacrylamide gels. Reciprocal cross neutralizations were demonstrated when purified type F and E toxins were reacted with antitoxins which were obtained with immunizing toxoids prepared with purified toxins.

A field trial, using killed-Mycoplasma gallisepticum vaccine to protect against chicken respiratory mycoplasmosis

In a field trial with chickens, the efficacy of killed Mycoplasma gallisepticum vaccine against respiratory mycoplasmosis was determined. Broiler chickens were vaccinated by aerosol administration at 3, 14, and 25 days of age, and observations were made of survival rate, body weight gain ratio, macroscopic lesion grade of airsacculitis, isolation of organisms, serologic test results, histopathologic changes, and clinical signs. Inhalation of the vaccinal aerosol did not influence livability and body weight gain ratios. In the control group, M gallisepticum, M synoviae, or both, wereisolated in 6 of 10 chickens at age 84 days and in 1 of 10 chickens at age 134 days. In all of the vaccinated groups (10 broilers each), however, results of bacteriologic cultural examination during the observation period were negative. The killed M gallisepticum vaccine also suppressed increase of antibody titers in the tube agglutination and the hemagglutination-inhibition tests at different intervals. Both the histopathologic changes and the clinical signs appeared minimal in the vaccinated group.

Evaluation of type A botulinal toxin assays that use antitoxin to crystalline toxin

The type A botulinal toxin assay by the reverse passive hemagglutination procedure which uses antitoxin to crystalline toxin was examined for specificity. The analysis was based on the fact that crystalline type A toxin is a complex of neurotoxic protein (Aalpha) and a nontoxic protein (Abeta). By using these components, obtained in essentially pure forms, it was shown that the antitoxin to crystalline toxin has a significantly higher titer to Abeta than to Aalpha. When Formalin-treated red blood cells were sensitized with this antitoxin, the antibodies coupled to the cells were, for practical results, only anti-Abeta. When the suspension is reacted with dilutions of type A toxic solutions, the limiting dilutions are determined by Abeta and not by the neurotoxin, which should be the determinant if the assay is to measure toxicity. These observations may be pertinent to the development of serological assays for other botulinal toxin types.

Role of a protease in natural activation of Clostridium botulinum neurotoxin

All tested proteolytic Clostridium botulinum type A, B, and F strains and certain non-proteolytic B and F cultures produced a protease having trypsin-like substrate specificity; none of the tested type E (non-proteolytic) strains produced the enzyme. Progenitor toxin (toxic form whose specific toxicity is increased by treatment with trypsin) was found in culture fluid concentrates of all strains not producing the protease; it was also present in some concentrates that had the enzyme. Activation of highly purified type E progenitor toxin (molecular weight 150,000) by essentially pure protease from a proteolytic type B culture was always less than that obtained with trypsin. The product of the type E progenitor toxin-protease reaction increased in toxicity when further treated with trypsin. Results suggest that at least two bonds are cleaved by trypsin during activation of type E progenitor toxin to toxin (form manifesting maximal possible specific toxicity). Natural activation of progenitor toxin of proteolytic strains may also involve cleavage of more than one bond.

FACTORS IN SURVIVAL OF CLOSTRIDIUM BOTULINUM TYPE E SPORES THROUGH THE FISH SMOKING PROCESS

Fish, experimentally inoculated with 1 ×106 Clostridium botulinum type E spores, were given heat treatments equivalent to those used in commercial smoking (180 F for 30 min following come-up time of 2.5 – 3 hr). The percentages of such fish containing viable type E spores were significantly lower among fish heated in an environment of high moisture than among those heated in atmospheres of low moisture. Type E spores heated in raw fish mince were more heat resistant than those heated in mince that was previously autoclaved. A similar difference was observed for spores in raw and cooked egg white, another substrate which coagulates rapidly at the temperature of thermal death time studies (82.5 C). Spores in the drippings of fish hung for heating survived heat processing and could be a source of cross contamination.

Boticinogeny and actions of the bacteriocin

The bacteriocin, boticin E, was produced by only a few strains of those clostridia which are nontoxigenic but otherwise identical to Clostridium botulinum type E. Boticin preparations from four different strains had identical spectra against indicator cultures. Experiments with bacterial lawns showed boticin to be sporostatic for all tested nonproteolytic C. botulinum (types B, E, and F) and nontoxigenic type E-related strains which included the producing strains as well as those different from type E in the fermentation of one to three carbohydrates. Boticin had no detectable effect on vegetative cells of boticinogenic strains but killed those of all other strains whose spores were sensitive. Cultures that were growing in an agar medium were more sensitive to the bacteriocin than those growing in broth. Vegetative cells of indicator strains adsorbed boticin, but cells of a boticin-resistant mutant did not. Boticin did not lyse suspensions of vegetative cells which had been killed previously by exposure to air but lysed actively growing protoplasts and L-forms of a strain whose normal vegetative cells are susceptible to lysis. Sporostasis resulted from inhibition of germination rather than of outgrowth. Proteolytic strains of C. botulinum (types A, B, and F) were resistant to boticin E.