Effect of 6059-S,a novel oxacephem,on cross-linking reaction of peptidoglycan biosynthesis in Escherichia coli,Pseudomonas aeruginosa and Serratia marcescens

The effect of 6059-S, a novel 1-oxacephem, on peptidoglycan synthesis was investigated using ether-treated cells of Escherichia coli K 12, Pseudomonas aeruginosa KM 338 and Serratia marcescens IFO 12648. The cross-linking reaction of peptidoglycan synthesis in these organisms was inhibited by markedly low concentration of 6059-S.Non-standard abbreviations PBP penicillin binding protein - MIC minimum inhibitory concentration - ETB ether treated bacterial cells - SDS sodium dodecylsulfate     

Effect of indole-3-acetic acid on cell wall loosening: Changes in mechanical properties and noncellulosic glucose content of Avena coleoptile cell wall

The effect of indole-3-acetic acid on cell wall loosening andchemical modifications of noncellulosic components of the cellwall in Avena coleoptile segments was studied and the followingresults were obtained. (1) Auxin decreased both the minimum stress-relaxation time(T_o) and the noncellulosic glucose content of the cell wall. (2) Decreases were observed in the absence or presence of mannitolsolution at concentrations lower than 0.20 M which osmoticallysuppressed auxin-induced extension, while at concentrationshigher than 0.25 M, there was little auxin effect, indicatingthat it is turgor-dependent. (3) The decrease in T_o of the cell wall and that in the noncellulosicglucose content caused by auxin in the presence of mannitolsolutions of various concentrations paralleled each other (thecorrelation coefficient was 0.897). (4) Both decreases in T_o and glucose content caused by auxinwere inhibited by nojirimycin (5-amino-5-deoxy-D-glucopyranose)in the presence of mannitol. The results suggest that auxin-induced cell wall loosening iscaused by the degradation of noncellulosic rß-glucanin the cell wall. (Received December 24, 1976; )     

Radioimmunoassay of ursodeoxycholic acid in serum

A sensitivie and specific radioimmunoassay for the measurement of serum ursodeoxycholic acid has been developed. Ursodeoxycholic acid bound to bovine serum albumin was used as an antigen, and antiserum to this antigen was raised in the rabbit. [11, 12-3h2]Ursodeoxycholic acid was used as the radioactive tracer, and the radioimmunoassay was carried out by the method of Simmonds et al. (1973. Gastroenterology. 65: 705-711). The percentage of bound radioactivity decreased linearly with a logarithmic increase in unlabeled ursodeoxycholic acid from 10 to 200 pmol. The antiserum showed extremely high specificity for ursodeoxycholic acid (free and conjugated), and the values determined by radioimmunoassay indicated a close correlation with those found by gas-liquid chromatography. In normal Japanese subjects, a small amount of ursodeoxycholic acid in serum was detected, and the level was detected, and the level was 0.15 +/- 0.11 nmol/ml. This convenient radioimmunoassay will provide useful information about the metabolism of ursodeoxycholic acid in man.     

Auxin-indnced changes in barley coleoptile cell wall composition

Auxin induces extension growth of barley coleoptile segments,causing cell extension and cell wall loosening represented bya change in mechanical properties of the cell wall. This responsedecreased after the segments were starved for more than 12 hrin buffer solution. Auxin decreased the noncellulosic glucosecontent of the cell wall of the segments starved for 0 and 6hr, but very little that of segments starved for 12 and 18 hr.The contents of arabinose, xylose and galactose, among noncellulosicpolysaccharides, and -cellulose of the cell wall increased duringthe starvation, but auxin did not affect them. The auxin-induceddecrease in glucose content was inhibited by nojirimycin, apotent inhibitor of ß-glucanase, which inhibited auxin-inducedextension and changes in mechanical properties of the cell wall,suggesting that cell wall loosening, and thus cell extension,resulted from partial degradation of ß-glucan of thecell wall. (Received April 20, 1978; )     

Induction of diabetes by PolyI:C and anti-RT6.1 antibody treatment in DR-BB rats.

To determine whether environmental factors could affect the incidence of diabetes in RT6.1+ lymphocytes-depleted diabetes resistant (DR) BB rats, we tested polyinosinic-polycytidylic acid (Poly I:C), as an immune activator, in conjunction with anti-RT6.1 antibody in DR-BB rats which were bred in a specific pathogen free (SPF) condition. Diabetes was induced by the combined administration of poly I:C and anti-RT6.1 antibody. The use of poly I:C or anti-RT6.1 antibody alone did not cause diabetes. These results suggest that RT6.1+ T lymphocytes regulate autoimmune diabetes and that non-specific immune activation caused by environmental factors plays a key role in inducing diabetes in DR-BB rats.     

The Pro to glycine mutation of staphylococcal nuclease simplifies the unfolding—folding kinetics

Kinetics of unfolding and refolding of a staphylococcal nuclease mutant, in which Pro¹¹⁷ is replaced by glycine, have been investigated by stopped-flow circular dichroism, and the results are compared with those for the wild-type protein. In contrast to the biphasic unfolding of the wild-type nuclease, the unfolding of the mutant is represented by a single-phase reaction, indicating that the biphasic unfolding for the wild-type protein is caused by cis-trans isomerization about the prolyl peptide bond in the native state. The proline mutation also simplifies the kinetic refolding. Importance of the results in elucidating the folding mechanism is discussed.     

Geographical distribution of Polycelis (Seidlia) auriculata in Japan

Polycelis (Seidlia) auriculata is endemic to mountain districts of Japan, from the central part of Honshû to the area of the Daisetsu Mts of Hokkaidô. In northern Japan, it sometimes occurs in cold-water biotopes of lowland areas. The progenitor of P. auriculata appears to have been the oldest immigrant into northern Japan among the Japanese Polycelis species, entering through a northern route as a preglacial faunal element. P. auriculata now shows a discontinious distribution in northern Japan. By virtue of its geographical and vertical distribution, ecological niche, variation in anatomy of the copulatory apparatus, and cytodemes, this species appears to be in the process of transformation.     

Molecular analysis of the cryptic and functional phn operons for phosphonate use in Escherichia coli K-12.

We cloned the cryptic phn operon of a K-12 strain, phn(EcoK), and analyzed the nucleotide sequence of the phn region (11,672 bp). An mRNA start site upstream of the phnC gene was identified by S1 nuclease mapping. The pho regulon activator PhoB protects a pho box region near the mRNA start in DNase I footprinting and methylation protection experiments. The sequence of the cryptic phn(EcoK) operon was very similar to that of the functional phn operon of an Escherichia coli B strain, phn(EcoB) (C.-M. Chen, Q.-Z. Ye, Z. Zhu, B. L. Wanner, and C. T. Walsh, J. Biol. Chem. 265:4461-4471, 1990). The phnE(EcoK) gene has an 8-bp insertion, absent from the phnE(EcoB) gene, which causes a frameshift mutation. The spontaneous activation of the cryptic phn(EcoK) operon is accompanied by loss of this additional 8-bp insertion. Studies of the structure, regulation, and function of the phn region suggest that the phosphate starvation-inducible phn operon consists of 14 cistrons from phnC to phnP.     

Identification and characterization of a coronavirus packaging signal.

Previously, a mouse hepatitis virus (MHV) genomic sequence necessary for defective interfering (DI) RNA packaging into MHV particles (packaging signal) was mapped to within a region of 1,480 nucleotides in the MHV polymerase gene by comparison of two DI RNAs. One of these, DIssF, is 3.6 kb in size and exhibits efficient packaging, whereas the other, DIssE, which is 2.3 kb, does not. For more precise mapping, a series of mutant DIssF RNAs with deletions within this 1,480-nucleotide region were constructed. After transfection of in vitro-synthesized mutant DI RNA in MHV-infected cells, the virus product was passaged several times. The efficiency of DI RNA packaging into MHV virions was then estimated by viral homologous interference activity and by analysis of intracellular virus-specific RNAs and virion RNA. The results indicated that an area of 190 nucleotides was necessary for packaging. A computer-generated secondary structural analysis of the A59 and JHM strains of MHV demonstrated that within this 190-nucleotide region a stable stem-loop of 69 nucleotides was common between the two viruses. A DIssE-derived DI DNA which had these 69 nucleotides inserted into the DIssE sequence demonstrated efficient DI RNA packaging. Site-directed mutagenic analysis showed that of these 69 nucleotides, the minimum sequence of the packaging signal was 61 nucleotides and that destruction of the secondary structure abolished packaging ability. These studies demonstrated that an MHV packaging signal was present within the 61 nucleotides, which are located on MHV genomic RNA 1,381 to 1,441 nucleotides upstream of the 3' end of gene 1.