The growth form of the inducing microorganism and chitin addition affect mycolytic enzyme production byTrichoderma harzianum

The effect of the growth form of the inducing microorganism on specificTrichoderma harzianum mycolytic enzyme production was studied. The pelleted form ofRhizopus nigricans gave a better product concerning protoplast formation ability. The maximum yield of protoplasts from the target fungusCochliobolus lunatus was 1×10⁸ ml^–1. Analysis of individual specific enzyme activities inTrichoderma mycolytic enzyme preparations confirms the importance of high chitinase and low protease activity for high protoplast yields. Supplementation of the production medium with chitin increased the chitinase activity in theTrichoderma exoenzyme mixture.     

Organization of telomeric and subtelomeric chromatin in the higher plant Nicotiana tabacum

We have examined the structure and chromatin organization of telomeres in Nicotiana tabacum. In tobacco the blocks of simple telomeric repeats (TTTAGGG)_n are many times larger than in other plants, e.g., Arabidopsis thatiana or tomato. They are resolved as multiple fragments 60–160 kb in size (in most cases 90–130 kb) on pulsed-field gel electrophoresis (PFGE) of restriction endonuclease-digested DNA. The major subtelomeric repeat of the HRS60 family forms large homogeneous blocks of a basic 180 by motif having comparable lengths. Micrococcal nuclease (MNase) cleaves tobacco telomeric chromatin into subunits with a short repeat length of 157±5 bp; the subtelomeric heterochromatin characterized by tandemly repeated sequences of the HRS60 family is cut by MNase with a 180 by periodicity. The monomeric and dimeric particles of telomeric and subtelomeric chromatin differ in sensitivity to MNase treatment: the telomeric particles are readily digested, producing ladders with a periodicity of 7 bp, while the subtelomeric particles appear to be rather resistant to intranucleosomal cleavage. The results presented show apparent similarities in the organization of telomeric chromatin in higher plants and mammals.     

应用流式细胞仪研究抗IL-8单抗对IL-8激活人颗粒细胞活力的中和作用(英文)

以IL-8免疫的BALB/C小鼠脾细胞与Sp2/0或653小鼠骨髓瘤细胞融合构建了淋巴细胞杂交瘤克隆I8-S2和I8-63。ELISA叠加试验(ELISA Additivity Test)表明这两杂交瘤克隆分泌的单抗分别识别IL-8分子的不同表位。IL-8能激活人颗粒细胞,引起细胞内Ca~(2 )浓度([Ca~(2 )]_i)上升。通过流式细胞仪分析[Ca~(2 )]_i的变化,发现两个克隆单抗对IL8激活细胞的活力具有不同的中和作用。克隆I8-S2具有很强的中和作用,而克隆18-63则不然。上述结果提示IL-8的激活细胞活力局限于该分子的某表位。     

Transfer of the broad-host-range IncQ plasmid RSF1010 and other plasmid vectors to the Gram-positive methylotroph Brevibacterium methylicum by electrotransformation

Gram-positive facultative methylotrophic coryneform bacterium Brevibacterium methylicum was efficiently transformed with various plasmids using electroporation of intact cells. In addition to the plasmid vectors pEC71 and pZ6-1 constructed on the basis of cryptic plasmids from coryneform bacteria, broad-host-range plasmids pLS5 (derivative of plasmid pMV158 from Streptococcus agalactiae) and RSF1010 belonging to the incompatibility group IncQ from Gram-negative bacteria were found to be present as autonomous structurally unchanged DNA molecules in B. methylicum transformants. With the exception of pZ6-1, all these plasmids were stably maintained in B. methylicum cells grown under non-selective conditions. When plasmid DNAs isolated from B. methylicum were used, the highest efficiency of transformation (10⁵ transformants/g DNA) was achieved. Correspondence to: J. Nevera     

Correlation between physico-chemical properties of quaternary ammonium salts of heptacaine and their inhibitory activity against photosynthesizing organisms

Photosynthesis inhibition in algae (Chlorella) and plant (spinach) chloroplasts by quaternary ammonium salts of heptacaine {N-[2-(2-heptyloxyphenylcarbamoyloxy)-ethyl]-N-alkylpiperidinium bromides} depended on the alkyl chain length of the alkyl substituent and showed good correlations with theoretical hydrophobic fragment constants as well as with experimentally determined physico-chemical parameters, namely extraction constants and surface activities. Communicated by. Z. ŠESTáK     

A new phage typing scheme forProteus mirabilis andProteus vulgaris strains

A new bacteriophage typing set, composed of 22 phages, was established as a tool for differentiation ofProteus strains. All the phages were tailed and included 4 morphological types (A1, A2, B1 and C1). They were classified into the familiesMyoviridae, Siphoviridae andPodoviridae. From the set, 19 phages had double-stranded DNA and 3 were single-stranded DNA phages.     

Characterization of adhesion associated surface properties of uropathogenicEscherichia coli

Escherichia coli was isolated from the urine of patients with pyelonephritis, with urinary tract infections other than pyelonephritis and with asymptomatic bacteriuria. Surface properties of the strains were analyzed by the salting-out aggregation test (SAT), hydrophobic interaction chromatography (HIC), Congo red binding (Crb), agglutination of erythrocytes (MRHA) and latex particles covered by digalactoside (PF) and by adherence to tissue culture cells. In addition, a DNA probe for thepap gene was used. The DNA probe detected the highest proportion of strains withpap gene in the group of patients with pyelonephritis, lower in the urinary tract infections other than pyelonephritis and the lowest in the group with asymptomatic bacteriuria. Tests for P-fimbriae (PF, MRHA) showed a similar distribution. Hydrophobicity measured by SAT and by HIC did not show differences among the tested groups of strains. The results suggest that factors other than the P-fimbriae and hydrophobicity may contribute to the persistence ofE. coli in the urinary tract.     

Occurrence of genes for P and S fimbriae and hemolysin in urinaryEscherichia coli

Escherichia coli is the common causative agent of urinary tract infections. Sixty-one strains ofE. coli isolated from children with urinary tract infections were tested by colony hybridization for the presence of genes determining P and S fimbriae and hemolysin. Of these strains, 46 possess a gene for hemolysin, 44 for P fimbriae and 28 for S fimbriae. Only 30 strains formed lytic zones around the colonies on plates with sheep erythrocytes. The results indicated that simultaneous occurrence of genes in urinaryE. coli was highest for P fimbriae and hemolysin and lower for other combinations of the tested genes.