Cross reactive antigens of Acholeplasma laidlawii and L-form of Staphylococcus aureus]

We demonstrated that the membrane of Acholeplasma laidlawii PG8 and L-form of Staphylococcus aureus, both of which induce cellular immunity in BALB/c mice, were antigenically related each other. Foodpad responses of the mice immunized with a mixture of either antigen and Freund's complete adjuvant showed clearly a cross reaction when challenged with the other antigen. Cross responses to incorporate 3H-thymidine to the spleen lymphocytes of the mice immunized with either antigen occurred in the presence of the other antigen. Furthermore, the purified T cells, but not B cells, of the spleen were activated in the presence of antigen-presenting cells. These antigens existing in the membrane fractions of both microorganisms were purified by Razin's method. Finally, these membrane components of A. laidlawii and L-form of S. aureus were subjected to gel electrophoresis and transferring to nitrocellulose membrane and used to stimulate the spleen lymphocytes of the mice immunized with A. laidlawii or of non-immunized mice. The fractions representing molecular weights of approximately 45 kD, 25 kD, and 13 kD of both microorganisms consistently stimulated the lymphocytes of the immunized mice but not those of non-immunized mice.     

Estimation of transport distance of fine particulate organic matter in relation to channel morphology in tailwaters of the Lake Biwa and reservoir dams

Knowledge on transport and deposition of fine particulate organic matter (FPOM) from reservoir dams is increasingly required for habitat management and restoration of dam tailwater ecosystems. Variations in the transport distance of FPOM, however, have never been studied well, particularly in relation to channel morphology, due to channel size restrictions of artificial tracers such as corn pollen when applied to larger river channels. This study aims to show the relations between FPOM retention efficiency and channel morphology in dam tailwaters using lentic plankters as tracers. We estimated the mean transport distance, S _p, by calculating downstream reduction ratios of lentic tracer plankters and calculated the deposition velocity, v _dep. Suspended FPOM samples were collected in tailwaters of two river channels below reservoir dams and two artificial canals below Lake Biwa in the Yodo River system. The longest S _p (19.2 km) and the shortest one (2.2 km) were recorded in the deep canal and shallow canal, respectively, showing a positive correlation with channel hydraulic radius. The values of v _dep were 4.7–6.4 times higher in river channels than in artificial canals. These results indicate that increasing complexity of bed morphology can minimize S _p, whereas bed degradation and armored bed materials may lead to increased S _p. Advantages of lentic plankters as tracers for estimating distance ranges of reservoir dam impact on river ecosystems are also discussed.     

Structure-activity relationships in human interleukin-1 alpha: identification of key residues for expression of biological activities.

To identify the sites important for the different biological activities of human interleukin-1 alpha (hIL-1 alpha), 56 single-amino acid-substituted mutants of hIL-1 alpha were produced in Escherichia coli using site-directed mutagenesis, and were examined for their biological activities such as mouse lymphocyte activating factor activity (LAF activity), cytostatic activity against human melanoma cells A-375 (A375 activity) and prostaglandin E2 (PGE2) inducing activity in human osteosarcoma cells MG-63 (PEI activity). Two amino acid residues, Asp26 and Asp151, were found to be important for these activities. The replacement of Asp26 by Val caused a decrease in LAF and PEI activities by one or two orders of magnitude and a slight decrease in A375 activity. The Tyr or Phe substitution for Asp151 caused decreases in LAF and A375 activities by one or two orders of magnitude and complete loss of PEI activity. The change from Asp151 to Lys or Arg resulted in marked decrease in LAF activity and complete loss of A375 and PEI activities. Since Asp26 and Asp151 are close to each other in the three-dimensional structure, the region involving these amino acids seems to be important for the biological activities of hIL-1 alpha.     

Prophages integrating into prophages: A mechanism to accumulate type III secretion effector genes and duplicate Shiga toxin-encoding prophages in Escherichia coli

Bacteriophages (or phages) play major roles in the evolution of bacterial pathogens via horizontal gene transfer. Multiple phages are often integrated in a host chromosome as prophages, not only carrying various novel virulence-related genetic determinants into host bacteria but also providing various possibilities for prophage-prophage interactions in bacterial cells. In particular, Escherichia coli strains such as Shiga toxin (Stx)-producing E. coli (STEC) and enteropathogenic E. coli (EPEC) strains have acquired more than 10 prophages (up to 21 prophages), many of which encode type III secretion system (T3SS) effector gene clusters. In these strains, some prophages are present at a single locus in tandem, which is usually interpreted as the integration of phages that use the same attachment (att) sequence. Here, we present phages integrating into T3SS effector gene cluster-associated loci in prophages, which are widely distributed in STEC and EPEC. Some of the phages integrated into prophages are Stx-encoding phages (Stx phages) and have induced the duplication of Stx phages in a single cell. The identified attB sequences in prophage genomes are apparently derived from host chromosomes. In addition, two or three different attB sequences are present in some prophages, which results in the generation of prophage clusters in various complex configurations. These phages integrating into prophages represent a medically and biologically important type of inter-phage interaction that promotes the accumulation of T3SS effector genes in STEC and EPEC, the duplication of Stx phages in STEC, and the conversion of EPEC to STEC and that may be distributed in other types of E. coli strains as well as other prophage-rich bacterial species.     

Simultaneous Determination of Oxidized and Reduced Forms of Plastoquinone A in Spinach Chloroplasts by High-Performance Liquid Chromatography with an Electrochemical Detector

A method for determination of the redox level of plastoquinoneA in spinach chloroplasts is described. Plastoquinone A andits reduced form plastoquinol A were extracted from chloroplastson a sample-preparation cartridge (SEP-PAK C₁₈ Cartridge, WatersAssoc. Inc.) with a mixture of ethanol and diethyl ether ( 1: 1, vv). Extracts were separated by reversed-phase high-performanceliquid chromatography and examined with an electrochemical detectorequipped with dual electrodes. Plastoquinone A was determinedby its reductive current on one electrode, and plastoquinolA by its oxidative current on the other electrode. This method was applied to the determination of the redox potentialof plastoquinone A in chloroplasts. The midpoint potential atpH 7.8 of plastoquinone A was +20 mV with an n number of 2. (Received March 30, 1987; Accepted August 3, 1987)     

An NAD:cysteine ADP-ribosyltransferase is present in human erythrocytes

A novel enzymatic activity, i.e., the catalysis of the formation of ADP-ribosylcysteine, was found in the cytosol of human erythrocytes. The NAD:cysteine ADP-ribosyltransferase was partially purified by sequential chromatographic steps on phenyl-Sepharose, phosphocellulose, and Sepharose CL-6B. The enzyme has an apparent molecular weight of 27,000 +/- 3,000, as determined by gel permeation. The formation of ADP-ribosylcysteine was associated with the stoichiometric release of nicotinamide from NAD. The enzyme was found to be highly specific toward cysteine and cysteine methyl ester as ADP-ribose acceptors. S-Benzoyl-L-cysteine, cystine, histidine, glutamic acid, arginine, arginine methyl ester, and agmatine were ineffective as acceptors for this enzyme.