Production and characterization of monoclonal antibodies against aflatoxin M1.

By using an indirect enzyme-linked immunosorbent assay, four monoclonal antibodies were selected after fusion of mouse P3-NS1-Ag4-1 myeloma cells with spleen cells isolated from BALB/c mice that had been immunized with aflatoxin M1 (AFM1) conjugated to bovine serum albumin. Two of these antibodies were found to be specific for AFM1 and were designated AMW-1 and AMW-4. The specificities of AMW-1, which had higher affinity to AFM1, were determined by a competitive direct enzyme-linked immunosorbent assay with peroxidase-AFM1 as the marker. The relative cross-reactivity of each toxin (relative to AFM1) with AMW-1, as determined by the amount of aflatoxin necessary to cause 50% inhibition of enzyme activity, was 12, greater than 40, 12, and greater than 40 for B1, B2, G1, and G2, respectively.     

Immunologically reactive tryptic fragments of human prostatic acid phosphatase.

Three peptide fragments (designated II, III and IV) of human prostatic acid phosphatase (PAP) were isolated to homogeneity from a limited tryptic hydrolysate of PAP by gel filtration on Sephadex G-100, followed by chromatography on DEAE-cellulose and Sephadex G-75. The homogeneity was confirmed by disc poly-acrylamide-gel electrophoresis. The Mr values were 32 500, 25 000 and 11 000 as estimated by gel filtration and sodium dodecyl sulphate/polyacrylamide-gel electrophoresis. Immunoprecipitation study revealed that only fragment II formed an immune precipitate with anti-PAP antibodies. Fragment II exhibited 45% of maximum inhibitory activity on the reaction between PAP and goat anti-PAP IgG (immunoglobulin G) antibodies (or rabbit anti-PAP antibodies), whereas fragments III and IV demonstrated 24% (or 23%) and 29% (or 27%) inhibition respectively. A mixture of these three tryptic fragments of PAP result in 96% (for goat anti-PAP antibodies) and 94% (for rabbit anti-PAP antibodies) inhibitory activities, which were equivalent to the sum of maximum inhibitory activity of the three fragments individually. The results demonstrated that these three tryptic peptide fragments carried all the antigenic active sites of the native PAP, and suggested that the entire molecule of human PAP comprised a minimum of four distinguishable, nonoverlapping antigenic determinants. These three fragments also were shown to retain all the disulphide bonds of the native PAP, and thus were useful reagents for the elucidation of PAP molecular structure.     

Production of antibody against T-2 toxin.

Antibody against T-2 toxin was obtained after immunization of rabbits with bovine serum albumin-T-2 hemisuccinate conjugate. The antibody had greatest binding efficiency for T-2 toxin, less efficiency for HT-2, and least for T-2 triol. Cross-reaction of antibody with neosolaniol, T-2 tetraol, and 8-acetyl-neosolaniol was very weak. Diacetoxyscirpenol, trichodermin, vomitoxin, and verrucarin A essentially gave no cross-reaction with the antibody. The sensitivity of the binding assay for T-2 toxin detection was in the range of 1 to 20 ng per assay. Detailed methods for the preparation of the conjugate and the production of immune serum and methods for antibody determination are described.     

Comparison of antibody production against aflatoxin B1 in goats and rabbits.

Bacteria were found that are capable of producing good yields of β-amylase in unrefined media. The culture filtrates are free of α-amylase and isoamylase.     

Ultrastructural neurohistochemical evidence for a neuro-endocrine link in the regulation of the extra-hepatic biliary dynamics.

Electron microscopical neurohistochemical studies of the choledocho-duodenal junction of the cat revealed acetylcholinesterase-positve nerve terminals closely abutting on ("ectopic"), mono-amine(s)-containing alpha-cells (of the islets of Langerhans) scattered in small clusters between bundles of the sphincteric smooth muscle (of Oddi). The cell membrane of the alpha-cells at and near the site of the neuro-effector contacts was reactive, too. This finding may be considered as some evidence for cholinergic innervation of cholinoceptive neuro-endocrine cells, and obviously represents one of the neuro-endocrine links involved in the regulation of the extra-hepatic biliary dynamics, demonstrated earlier in physiological and pharmacological studies.     

A gene involved in the metabolic control of ppGpp synthesis

Summary A genetic locus has been identified which controls the basal synthesis of ppGpp in growing E. coli. Cells carrying a recessive allele of the relX gene have a very low concentration of ppGpp during balanced growth, and fail to accumulate ppGpp in response to carbon/energy source downshift. Moreover, the recessive relX allele renders the cells unable to grow at 42° C and, when coupled with relA, makes the cells sensitive to the presence of leucine in minimal medium. RelX is cotransduced with fuc and relA and located at approximately 59.4 min on the E. coli genetic map.     

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.     

Primary structure of the S-peptide formed by digestion of rabbit liver fructose 1,6-biphosphatase with subtilisin.

Digestion of rabbit liver fructose 1,6-bisphosphatase with subtilisin followed by denaturation of the protein yields a peptide containing 60 amino acid residues, including the blocked NH₂-terminus. This peptide has the following sequence: Ac-Ala-Asp-Lys-Ala-Pr o-Phe-Asp-Thr-Asp-Ile-Ser-Thr-Met-Thr-Arg-Phe-Val-Met-Glu-Glu-Gly-Arg-Ly s-Ala-Gly-Gly-Thr-Gly-Glu-Met-Thr-Gln-Leu-Leu-Asn-Ser-Leu-Cys-Thr-Ala-Va l-Lys-Ala-Ile-Ser-Thr-Ala-Val-Arg-Lys-Ala-Gly-Ile-Ala-His-Leu-Tyr-Gly-Ile-Ala.