Effect of interferon on the course of experimental E coli-induced pyelonephritis

The effect of the type I interferon on the development and process of experimental pyelonephritis caused by E. coli was studied on mice weighing 12 to 14 g. Interferon was administered intraperitoneally in a dose of 1000 units on days 3 and 7 of the disease. It was shown that the administration of the type I interferon to the mice with experimental pyelonephritis promoted rapid elimination of bacteria from the kidneys, prevented their penetration to the contralateral (intact) kidney, prevented marked macro- and microscopic damages in the kidneys, lowered the intensity of the inflammatory reaction, and increased the phagocytic activity of neutrophils and the number of the E-rosette-forming lymphocytes in the thymus. The data provided experimental grounding for clinical trials of interferon preparations in treatment of bacterial pyelonephritis.     

用定点突变技术研究转录终止——rpoBC操纵子上~tL7茎环结构的作用研究

 E.coli RNA聚合酶ββ'亚单位编码的基因rpoBC与核糖核蛋白基因rplJL共同构成rpoBC操纵子。rpl-rpo间区转录终止信号~tL7的转录产物RNA有两组富含C-G的反向对称结构及一串寡聚U;反向对称区可形成1:2和3:4茎环或单一5:6茎环。 用M13mp11噬菌体插入~tL7的112bp片段重组M13mp11-490,在此基础上用定点突变技术建立~tL7的七核苷酸缺失突变体,从而破坏1:2茎环,建成M13mp11-85。 分别把原型~tL7及缺失型~tL7~v克隆到表达质粒pHR24中,构建成pHR37(P_ftsQ~tL7-galk)及pHR24-9(p_ftsQ-~tL7~v-galk)。测定galk基因产物半乳糖激酶活性,推算转录的终止效率。结果表明:~tL7终止效率为50％,~tL7~v为20％。说明仅有3:4茎环及寡聚U,即具终止作用; 1:2茎环通过某种方式加强3:4茎环从而提高终止效率。     

Microbial transformation of azacarbazoles X: Regioselective hydroxylation of 5,11-dimethyl-5H-indolo [2,3-b]quinoline, a novel DNA topoisomerase II inhibitor, by Rhizopus arrhizus

Summary Microbial transformation of cytotoxic 5,11-dimethyl-5H-indolo[2,3-b]quinoline (a compound displaying antitumor activity and affecting the activity of calf thymus DNA topoisomerase II) was performed by the Rhizopus arrhizus strain and yielded a 9-hydroxy derivative. The metabolite obtained displayed a stronger cytotoxity against KB cells than the parent compound (ID₅₀=0.001 mol/mL), and stimulated also the formation of calf thymus topoisomerase II mediated pSP65 DNA cleavage in vitro at the concentration of 3 M. Being analogous to 9-hydroxyellipticine (which is an antitumor alkaloid), this novel indolo[2,3-b] quinoline derivative can be regarded as a novel potential antitumor agent.     

Bacteriochlorophyll organization and energy transfer kinetics in chlorosomes from Chloroflexus aurantiacus depend on the light regime during growth

We have used measurements of fluorescence and circular dichroism (CD) to compare chlorosome-membrane preparations derived from the green filamentous bacterium Chloroflexus aurantiacus grown in continuous culture at two different light-intensities. The cells grown under low light (6 mol m^–2 s^–1) had a higher ratio of bacteriochlorophyll (BChl) c to BChl a than cells grown at a tenfold higher light intensity; the high-light-grown cells had much more carotenoid per bacteriochlorophyll.The anisotropy of the Q_Y band of BChl c was calculated from steady-state fluorescence excitation and emission spectra with polarized light. The results showed that the BChl c in the chlorosomes derived from cells grown under high light has a higher structural order than BChl c in chlorosomes from low-light-grown cells. In the central part of the BChl c fluorescence emission band, the average angles between the transition dipole moments for BChl c molecules and the symmetry axis of the chlorosome rod element were estimated as 25° and 17° in chlorosomes obtained from the low- and high-light-grown cells, respectively.This difference in BChl organization was confirmed by the decay associated spectra of the two samples obtained using picosecond single-photon-counting experiments and global analysis of the fluorescence decays. The shortest decay component obtained, which probably represents energy-transfer from the chlorosome bacteriochlorophylls to the BChl a in the baseplate, was 15 ps in the chlorosomes from high-light-grown cell but only 7 ps in the preparation from low-light grown cells. The CD spectra of the two preparations were very different: chlorosomes from low-light-grown cells had a type II spectrum, while those from high-light-grown cells was of type I (Griebenow et al. (1991) Biochim Biophys Acta 1058: 194–202). The different shapes of the CD spectra confirm the existence of a qualitatively different organization of the BChl c in the two types of chlorosome.Abbreviations BChl bacteriochlorophyll - CD circular dichroism - DAS decay associated spectrum - PMSF phenylmethylsulfonyl fluoride     

Keratinolytic fungi in sewage sludge

Sewage sludge from the Upper Silesia Region of Poland were surveyed for keratinolytic fungi. Out of 100 Petri dishes examined, 89 were positive for these micro-organisms. Altogether, 185 fungal appearances belonging to 10 species were observed. Trichophyton terrestre with its teleomorph Arthroderma quadrifidum, T. ajelloi with A. uncinatum, Microsporum gypseum with Arthroderma sp., and Chrysosporium keratinophilum with Aphanoascus keratinophilus prevailed in the sludges. The sewage treatment technologies together with the sludge structure, humidity and pH were found to be critical factors determining the occurrence of keratinolytic fungi in the sludge environment. The qualitative and quantitative composition of keratinolytic fungi could be a useful tool in evaluation of sludge treatment processes.     

丝孢酵母高甲硫氨酸突变株的选育及营养调控

以丝孢酵母(Trichosporon Behr)ST851为原始菌株,经紫外线诱变,在含乙硫氨酸的双层平板上筛选到多株抗乙硫氨酸突变株。其中ST851-10株抗乙硫氨酸浓度达到350μg/ml,其菌体蛋白质含量由40.5％提高到44.3％,菌体甲硫氨酸含量由20.45mg/g-DCW增加到29.32mg/g-DCW。在以苹果渣为碳源、尿素为氮源、硫酸镁作硫源的最适培养条件下,固态发酵24h后,蛋白质和甲硫氨酸含量较原始菌株分别提高了15.8％和44.9％。培养基中C/N值低有利于甲硫氨酸的合成,C/N值高则适合于菌体生长。在苹果渣固态发酵过程中,适当补加氮源既有利于菌体生长和甲硫氨酸的合成,又可起到调节培养基pH值的作用。     

Analysis of Lactobacillus phages and bacteriocins in American dairy products and characterization of a phage isolated from yogurt.

Yogurt and acidophilus milk that contain Lactobacillus acidophilus could promote human health because L. acidophilus can inhibit enteric and food-borne microbial pathogens. To evaluate the stability of diary L. acidophilus cultures, we studied whether some diary lactobacilli could be inhibited by phages or bacteriocins released by other dairy lactobacilli. From 20 yogurts and two acidophilus milks purchased at local food markets, 38 Lactobacillus strains were isolated. Eight Lactobacillus type strains were used as controls. With mitomycin induction and agar spot assay, phages and bacteriocins were isolated from these strains and their activities were analyzed. Lactobacillus strains from 11 yogurts released phages, while the strains from most of the remaining products released bacteriocins. One phage, designated phi y8, was characterized. It was spontaneously released from its host strain L. acidophilus Y8, at a rate of about 10(4)/ml. This phage lysed nine other dairy Lactobacillus strains tested. It had a burst size of 100, an elongated prolate head of 39 by 130 nm, a long, flexible but noncontractile tail of 300 nm, and a 54.3-kb linear double-stranded DNA. DNA fingerprinting analysis indicated that L. acidophilus phages of nine yogurts in this study belonged to the same type as phi y8. Although they may be sensitive to bacteriocins, all lysogens resisted further phage attacks, whereas most nonlysogens were sensitive to both phages and bacteriocins. Therefore, Lacotbacillus cultures of some American yogurts and acidophilus milks may be unstable or unsafe because they can either be inhibited by phages or bacteriocins or release them to inhibit lactobacilli or other diary products.     

Lead as an inductor of some morphological and functional changes in synaptosomes from rat brain

Summary 1. The effect of lead (in vivo) on the uptake of GABA, dopamine, and histidine as a precursor of histamine in synaptosomes obtained from chronically lead-treated rats was studied.2. Lead decreased the uptake of GABA, increased the uptake of dopamine, and did not change the uptake of histidine. These effects were independent of calcium concentration.3. Lead administration to the rat changed the morphology of the synaptosomes, as manifested in the decreased number of synaptic vesicles and disturbed mitochondrial structure.4. The results suggest the existence of several mechanisms of lead toxicity on uptake, related to individual neurotransmitters, which are not necessarily connected with a Pb²⁺/Ca²⁺ interaction.