The initial,chloramphenicol-sensitive phase in the transduction ofSalmonella typhimurium

Было устновлуено, что клетка в котоpyь вошел трансдуцируьший ?рагмнт дезоксирибонуклеин овой кислототь ?ага, денотипически выраженным признаком Начальный период первым лелением потенпиальный периол после алсорбции ?ага на клетку, перед первым признаком.Начадьнй иериод посде адсорбции ?ага иа клетку, персд пер вым делнием потенпално трансдуцкрванной клетки, зависит от протеосиптетичсско гоили другого чувствмтелыошенико лу процеса, протекышего в бактеривx впериод покоя.-Обсуждаытся оснояные Mеxaнизмы процссса трансдукции.     

The influence of rifampicin resistant mutations on the biosynthesis of exopolysaccharides by strain Escherichia coli K-12 lon

Applied Biochemistry and Microbiology - The influence of RNA polymerase (rif) mutations on the yield of capsular exopolysaccharide— colanic acid (CA) of Escherichia coli K-12 lon strain was...     

柞蚕蛹抗菌肽D对大肠杆菌K_(12)D_(31)的作用

本文报道了不同浓度的柞蚕蛹抗菌肽D,对大肠杆菌K_(12)D_(31)的杀灭作用动力学。在LEG培养液中,抗菌从D的浓度在5微克/毫升时显效。浓度在10微克/毫升以上时,其杀菌速度大于细菌的增殖速度。固定抗菌肽浓度为10微克/毫升,细菌浓度在3×10~7个细菌/毫升,培养在磷酸钾盐缓冲液中,4小时后能全部杀灭。同样浓度细菌在LEG培养液中,4小时后细菌数下降到约为10~2个细菌/毫升,但不能全部杀灭。同时还提供了柞蚕蛹抗菌肽D和B对大肠杆菌K_(12)D_(31)作用不同时间的电镜照片。     

Microscopic picture of lysozyme and glycine spheroplasts ofEscherichia coli exposed to colicin

Сферопласты чувствительного и резистентного штаммов Escherichia coli наблудались под фазовым микроскопом в присутствии колицина и без него. Лизоцимовые сферопласты чувствительного штамма под действием колицина быстро распадаются, глициновые же сравнительно быстро набухают и подвергаются лизису. Ни те ни другие никогда не размножаются и не регенерируют. Лизоцимовые и глициновые сферопласты —так же как и пенициллиновые —будучи приготовлены из штамма, устойчивого к колицину, в его присутствии развиваются так же, как в контрольных препаратах. Итак, можно полагать, что оболочки пенициллиновых, лизоцимовых и глициновых сферопластов постоянно содержат редепторы к применявшимся колицинам.—Попытки вырастить постоянные L-формы Escherichia coli остались безуспешными.     

Quantitative determination of cyanogenesis in plants

V práci je popsána metoda vhodná k sériovým stanovením pro genetické pokusy. Kolorimetrické stanovení HCN (1fenyl-3methyl-5pyrazolonem a pyridinem, fenolftalinem nebo Na-pikrátem) dovoluje zpracovat vzorky uvolňující 0,2μg a? 20 μg HCN. P?ed ?těpením glykosidu mo?no provést stanovení obsahu oleje v semenech. Analysa variance kyanogenních vlastností jednotlivých semen dvou odr?d lnu s pr?měrným obsahem 0,4 a 0,9 μg HCN ukazuje, ?e je mo?no zachytit rozdíly mezi rostlinami i rozdíly mezi tobolkami té?e rostliny.     

产细菌素乳酸菌的筛选及体外抑菌试验

从健康鸡、兔、仔猪肠道内容物及新鲜粪便中分离到4l株乳酸菌,通过单层琼脂平板扩散实验,筛选出5株有明显抑菌活性代谢产物的乳酸菌,其中4株属于乳杆菌属,l株属于链球菌属。排除酸的干扰后,离心发酵液对指示菌仍有抑菌活性,用胰蛋白酶和本瓜蛋白酶处理后抑菌活性明显降低,用过氧化氢酶作用上清液,抑菌效果不变,说明过氧化氢未起作用,从而得知抑菌物质中有蛋白质类细菌素。将离心发酵液分别调pH值为2．0、3．0、4．0、5．0、6．0、7．0,做抑菌试验,试验结果证明：所分离的5株乳酸菌在pH2．0,3．0,4．0时均有较强的抑菌活性,且MD菌株在pH7．0时抑菌活性亦较强,这进一步排除了酸的作用。每周重复一次,抑菌结果完全一致,但至第5周时,抑菌现象完全消失,说明抑菌物质随时间的延长而失活,起抑菌作用的物质不是有机酸。     

Survival of Escherichia coli O157:H7 in ruminal or fecal contents incubated with corn or wheat dried distillers' grains with solubles

Dried distillers' grain with solubles (DDGS) is a by-product of ethanol production, and its use as cattle feed has increased as a result of the expansion of the fuel ethanol industry. However, the inclusion of corn DDGS into feedlot diets may increase the shedding of Escherichia coli O157:H7. This study investigated whether corn or wheat DDGS at 2 concentrations (20% or 40% vs. 100% barley grain) affected the survival of E.?coli O157:H7 in incubations of ruminal digesta and feces. Neither the type nor the level of DDGS had any effect on fermentation or the survival of E. coli O157:H7 in ruminal digesta. However, there was a time by DDGS interaction (p?< 0.05), where the numbers of E.?coli O157:H7 in feces did not differ after 4 or 12?h of incubation but were greater after 24?h in both 40% wheat and 40% corn DDGS as compared with other treatments. Additionally, after 24?h, the numbers of E. coli O157:H7 were greater in fecal incubations with corn DDGS than with wheat DDGS (p?< 0.05). The differences in the numbers of E.?coli O157:H7 were not attributable to changes in pH or in concentrations of volatile fatty acids in the media. These results suggest that the inclusion of high levels of corn or wheat DDGS in feedlot diets of cattle may encourage the survival of E. coli O157:H7 in feces.     

Modeling the Main Physical Processes in Beehives

Biophysics - Abstract—A winter bee community of 15?000 bees housed in wooden beehive boxes with 12 frames was used to analyze the physical processes that occur in beehives. The most...     

Presence of rfe genes in Escherichia coli: their participation in biosynthesis of O antigen and enterobacterial common antigen.

In Salmonella, ilv-linked rfe genes participate in the biosynthesis of the enterobacterial common antigen (CA) as well as of certain types of O antigen (serogroups C1 and L). rff genes, probably in the same cluster with rfe, are required for CA synthesis (P.H. M?kel? et al., in preparation). Several Escherichia coli strains were studied to determine whether they also have rfe-rff genes that are involved in the synthesis of O antigen and CA, or of CA only. In a first approach, E, coli K-12 F-prime factors carrying the genes ilv and argH or argE and presumably rfe-rff genes were introduced into CA-negative Salmonella mutants that are blocked in CA synthesis because of mutated rfe or rff genes. All resulting ilv+ hybrids were CA positive. In recipients with group C1-derived rfb genes, the synthesis of O6,7-specific antigen was also restored. This result shows that E. coli K-12 has rfe and rff genes providing the functions required in the synthesis of CA and Salmonella 6,7-specific polysaccharide. By introduction of defective rfe regions from suitable Salmonella donors into E. coli O8, 09, and O100 strains, the synthesis of CA as well as of the O-specific polysaccharides was blocked. This indicates that in the E. coli strains tested the rfe genes are involved in the synthesis of both O antigen and CA. This suggestion was confirmed by the finding of E. coli rough mutants that had simultaneously become CA negative. In transduction experiments it could be shown that the appearance of the rough and CA- phenotype was due to a defect in the ilv-linked rfe region.     

Der Einfluss von Pyrazon auf die Katalase-Aktivität in den Blättern der Senfpflanze (Sinapsis alba L.) und der Zuckerrübe

Rostliny ho??ice bílé (Sinapis alba L.) a cukrovky (Beta vulgaris L.) byly post?íkány ve fázi prvého páru pravých list? herbicidem pyrazonem (=1-fenyl-4-amino-5-chlor-pyridazonem-6) ve formě subspenzního p?ípravku Pyraminu v 0,4% koncentraci. Za 1 den, 4, 7 a 14 dní po post?iku volumetrikou motodou podle Jermakova a splupracovník? zji??ována aktivita katalázy ve ??ávě z list?. Bylo zji?ěno, ?e aktivita katalázy v listech citlivé rostliny (ho??ice bílé) byla pyrazonem potla?ena ve srovnání se ??ávou z list? neo?et?ených, kde?to v listech odolné rostliny (cukrovky) aktivita katalázy sní?ena nebyla.     

Antimicrobial nectar inhibits a florally transmitted pathogen of a wild Cucurbita pepo (Cucurbitaceae)

? Premise of the study: Floral nectars of many species contain antimicrobial chemicals, but their function in nectar is subject to debate. Previously, we have shown that Erwinia tracheiphila, the causative agent of bacterial wilt disease in cucurbits, can be transmitted via the floral nectaries. ? Methods: We used a disk diffusion assay (DDA) to determine the antimicrobial effects of nectar from a wild gourd on lawns of Escherichia coli and Erwinia tracheiphila. We also used E. tracheiphila to inoculate flowers of wild gourd plants, with and without nectar. ? Key results: The DDA showed that paper disks saturated with 10 μL of nectar inhibited the growth of E. coli on a larger area of the lawn than 40% glucose but a smaller area than 5% ampicillin for 12 h. On lawns of E. tracheiphila, nectar inhibited growth on a larger area than glucose for 24 h and there were no significant differences between ampicillin and nectar for12 h. A significantly larger proportion of the plants inoculated via flowers without nectar contracted wilt disease than plants with nectar. ? Conclusions: These findings indicate that nectar reduces transmission of E. tracheiphila via the nectaries and reveal the potential for florally transmitted pathogens to influence the evolution of floral traits.     

Anthocyanins ofImpatiens holstii

1. 1.
   Byly chromatografovány antokyany t?í typ?Impatiens holstii. Bylo zji?-těno, ?e typ A (f. nana, sorta Záre, s ?arlatovými květy) obsahuje ve stonku—gluko-sidy malvidinu, v petalech—glukosidy pelargonidinu a peonidinu, v sepalech— glukosid malvidinu a cyanidinu, v pylu—glukosidy a snad i xylosidy malvidinu; typ B (f. nana, sorta Zá?e, s ?ervenofialovými květy) obsahuje ve stonku— malvidin, v petalech—peonidin, v sepalech—malvidin a cyanidin, v pylu— malvidin; typ C (vzp?ímený typ, s ?ervenofialovými květy) obsahuje v petalech—malvidin a peonidin, v sepalech—malvidin a cyanidin, v pylu—malvidin. U typ? ? a ? eukry nebyly sledovány.     
   
   

Age and sex of chronic carriers of HBs antigen among 130,000 blood donors]

The frequency of HBs antigen, using radioimmunology is studied in blood donors from Languedoc (70.894 men and 60.760 women are tested, between 18 and 60 years old). The frequency in man is found to be 0,6 %, except between 20 and 30 years whereas it reaches 1,0 %; the frequency in woman is 0,4 % except between 18 and 36 years where it is 0,4 %.     

Relations of Bromine,Iron, Rubidium,Strontium, and Zinc Content to Morphometric Parameters in Pediatric and Nonhyperplastic Young Adult Prostate Glands

The variation with age of the Br, Fe, Rb, Sr, and Zn mass fractions and some histological characteristics of intact prostate glands of 50 subjects aged 0–30 years was investigated by an energy-dispersive X-ray fluorescence and a quantitative morphometric analysis. Mean values?±?standard error of the mean (M?±?SΕΜ) for the mass fractions (in milligrams per kilogram wet-mass basis) of these trace elements in pre-puberty were: Br—10.5?±?1.3, Fe—28.6?±?4.1, Rb—3.05?±?0.27, Sr—0.42?±?0.08, and Zn—32.9?±?3.2. During puberty and postpuberty, when there is a significant increase in circulating androgens, the mean values were: Br—5.60?±?0.57, Fe—19.3?±?1.6, Rb—3.50?±?0.28, Sr—0.24?±?0.03, and Zn—113?±?10. Mean values (M?±?SΕΜ) of percent volumes (%) of the stroma, epithelium, and lumen in the prostate before puberty were 73.4?±?2.6, 20.4?±?1.7, and 4.45?±?0.94, respectively, versus 46.5?±?2.5, 38.5?±?1.9, and 14.9?±?1.2 during puberty and postpuberty. A significant positive correlation between the prostatic Zn and percent volume of both glandular epithelium (r?=?0.573, p?≤?0.001) and glandular lumen (r?=?0.725, p?≤?0.001) was found. For the first time, it has been demonstrated that the glandular lumen is a main pool of Zn accumulation, and that the stroma is a main pool of Br and Fe accumulation in the normal human prostate, for the age range 14 to 30 years. It was concluded that the Zn binds tightly within the prostatic fluid because the volume of glandular lumen reflects the volume of prostatic fluid.     

Geranium robertianum L., plant form adapted to the specific conditions along railway: “railway-wandering plant”

The question of whether any specific plant species are typically growing along railway tracks (the so-called “railway-wandering plants”) has been discussed for many years. This study proves the existence of a form of Geranium robertianum species growing along railway tracks in North–Eastern Poland. Floristic studies have been carried out in 246 areas along railway tracks. This particular species was found in 70 studied areas (28 %). Comparative studies were carried out on 12 plant populations growing in the fieldwork and in glasshouse cultivation. Plants growing along the railway tracks in Wali?y were different from all other studied populations. They were small (smaller by 31 %, max. by 57 % than other plants), with little leaf blades representing different shapes and colour. In studies of light absorption by photosynthetic apparatus (chlorophyll fluorescence) under conditions of exposure to high light intensity, the plants from Wali?y were proved to have a better adaptation capacity to stress conditions. Increased levels of anthocyanins—which provided better protection of the photosynthetic apparatus against insolation—were shown. The protective properties against water deficiencies and excessive insolation were genetically preserved and were found in the second generation of plants cultivated in a glasshouse. For the first time, a new plant form of G. robertianum—a “railway-wandering plant” adapted to the conditions prevailing along railway tracks—was confirmed to exist. The form has developed probably after 1886, when the Bia?ystok–Zubki railway was built, featuring the Wali?y railway station.     

Ex12 helper phage improves the quality of a phage-displayed antibody library by ameliorating the adverse effect of clonal variations

The quality of a phage-displayed antibody library deteriorates with clonal variations, which are caused by differentially expressed Escherichia coli antibody genes. Using the human Fab SP114 against the pyruvate dehydrogenase complex-E2 (PDCE2), we created four E. coli TOP10F' clones with a pCMTG phagemid encoding Fab-pIII (pCMTG-Fab), Fd (V(H)+C(H1))-pIII (pCMTG-Fd), or light chain (L) (pCMTG-L), or the vector only (pCMTG-?Fab) to investigate the effect of clonal variations in a defined manner. Compared to the others, the E. coli clone with pCMTG-Fab was growth retarded in liquid culture, but efficiently produced phage progenies by Ex12 helper phage superinfection. Our results suggest that an antibody library must be cultured for a short duration before helper phage superinfection, and that the Ex12 helper phage helped to alleviate the detrimental effect of clonal variation, at least in part, by preferentially increasing functional phage antibodies during phage amplification.     

E. coli filament formation induced by heterologous S-layer expression

Escherichia coli is a rod-shaped intestinal bacterium which has a size of 1.1-1.5 μm x 2.0-6.0?μm. The fast cell division process and the uncomplicated living conditions have turned E. coli into a widely used host in genetic engineering and into one of the best studied microorganisms of all. We used E. coli BL21(DE3) as host for heterologous expression of S-layer proteins of Lysinibacillus sphaericus JG-A12 in order to enable a fast and high efficient protein production. The S-layer expression induced in E. coli an unusual elongation of the cells, thus producing filaments of > 100 μm in length. In the stationary growth phase, E. coli filaments develop tube-like structures that contain E. coli single cells. Fluorescence microscopic analyses of S-layer expressing E. coli cells that were stained with membrane stain FM (?) 5-95 verify the membrane origin of the tubes. Analyses of DAPI stained GFP-S-layer expressing E. coli support the assumption of a disordered cell division that is induced by the huge amount of recombinant S-layer proteins. However, the underlying mechanism is still not characterized in detail. These results describe the occurrence of a novel stable cell form of E. coli as a result of a disordered cell division process.     

Thermodynamic interactions of a cis and trans benzanilide with Escherichia coli bacterial membranes

The activity of a membrane interactive cis and trans benzanilide against Escherichia coli membrane mimics was investigated using Langmuir monolayers. It was found that in the presence of E. coli lipid mix monolayers, cis-benzanilide induced maximal surface pressure changes of 1?mN?m(-1), whereas a reduced interaction was observed with trans-benzanilide. Compression isotherm analysis of these monolayers showed ?G (mix)?相似文献   

Studies on the Formation and Characteristics of antibodies in frogs

Было установлсно, что — кроме темиературы — вторым решающим Фактором для осуществления образования антител является количестяо антигена и время его введения. Антитела, иолученные у лятушек, были с помощыо крахмалыюго элсктро?ореэа локалиэованы в гамма-и бетаглобулиновоо ?ракции сывороточных белков. Было установлено, что в сыворотке. лятушек и в гамма-глобулиновой ?ракции находятся приблиэиэительно те же тииы молекул, как и в сыворотке млекопитающих с приэнаками болышего количества типа 18S. Гетероагглютинины нины лягушки не теряют под влиянием меркаптоэтанола своэй активности. Было установлено также, что лягушечьи иммунные гетероагглютипины, что касаетсн агглютинации эритроцитов других яидов животных, являются совершенно специ?ическими.