Construction and biological characterization of a Proteus mirabilis strain with modABC gene deletion / 南方医科大学学报

OBJECTIVE@#To construct a modABC gene knockout strain of Proteus mirabilis and explore the effect of modABC gene deletion on biological characteristics of Proteus mirabilis.@*METHODS@#Fusion PCR was used to obtain the fusion gene of modABC and the kanamycin-resistant gene Kn, which was ligated with the suicide vector pCVD442 and transduced into Proteus mirabilis. The modABC gene knockout strain of Proteus mirabilis was obtained after homologous recombination with the suicide vector. PCR and Sanger sequencing were used to identify genomic deletion of modABC gene in the genetically modified strain. The concentration of molybdate in the wild-type and gene knockout strains was determined using inductively coupled plasma mass spectrometry (ICP-MS), and their survival ability in LB medium was compared under both aerobic and anaerobic conditions.@*RESULTS@#PCR and sanger sequencing confirmed genomic deletion of modABC gene in the obtained Proteus mirabilis strain. The concentration of intracellular molybdenum in the modABC gene knockout strain was 1.22 mg/kg, significantly lower than that in the wild-type strain (1.46 mg/kg, P < 0.001). Under the aerobic condition, the modABC gene knockout strain grown in LB medium showed no significant changes in survival ability compared with the wild-type strain, but its proliferation rate decreased significantly under the anaerobic condition and also when cultured in nitrate-containing LB medium under anaerobic condition.@*CONCLUSION@#Homologous recombination with the suicide vector can be used for modABC gene knockout in Proteus mirabilis. modABC gene participates in molybdate uptake and is associated with anaerobic growth of Proteus mirabilis in the presence of nitrate.

Adsorption of molybdenum by melanin

BACKGROUND@#Melanin is detectable in various sense organs including the skin in animals. It has been reported that melanin adsorbs toxic elements such as mercury, cadmium, and lead. In this study, we investigated the adsorption of molybdenum, which is widely recognized as a toxic element, by melanin.@*METHODS@#Molybdenum level of the mouse skin was measured by inductively coupled plasma mass spectrometry. The pigmentation level of murine skin was digitalized as the L* value by using a reflectance spectrophotometer. An in vitro adsorption assay was performed to confirm the interaction between molybdenum and melanin.@*RESULTS@#Our analysis of hairless mice with different levels of skin pigmentation showed that the level of molybdenum increased with an increase in the level of skin pigmentation (L* value). Moreover, our analysis by Spearman's correlation coefficient test showed a strong correlation (r = - 0.9441, p < 0.0001) between L* value and molybdenum level. Our cell-free experiment using the Langmuir isotherm provided evidence for the adsorption of molybdenum by melanin. The maximum adsorption capacity of 1 mg of synthetic melanin for molybdenum was 131 μg in theory.@*CONCLUSION@#Our in vivo and in vitro results showed a new aspect of melanin as an adsorbent of molybdenum.

A selectivity study of the examination of radionuclides Cesium-1 37 for foods based on different detection conditions / 预防医学

Objective Aselectivitystudywasconductedthroughtheexaminationofradionuclides137Cs(Cesium-137)for foodbasedondifferentdetectionconditions.Methods Atotalof48foodsampleswereselectedfromthreeareasincluding Qinshan nuclear power plant,Sanmen nuclear power plant and Hangzhou and Zhoushan respectively.1 37 Cs of these samples were determined by γspectrometry and Phosphoric acid ammonium molybdate method.The level of 48 foods were statistically analyzed,and then the time consuming,sample size requirements,influence factors were comprehensively discussed,thustheselectionreferenceproposaloftheexaminationmethodcouldbeprovided.Results Therewereno significant difference for the data of two examination method (P>0.05 ).The limit of detection of the γspectrometry was lower (P <0.05 ).Compared with Phosphoric acid ammonium molybdate method,γspectrometry had lower limit of detection,and could detect a variety of radionuclides at a time,but need more sample and time-consuming when multi-sample were detected.The limit of detection of the Phosphoric acid ammonium molybdate method was high,and the chemicalprocessingstepswerecumbersomeandwaseasytobeinterferedby134Cs.Conclusion Thelimitofdetectionof the γspectrometry is low,and the sensitivity of the Phosphoric acid ammonium molybdate method is high.Most food are recommended to be detected by γspectrometry in the practical work,and the food which were difficult collected,less ash or low content,are recommended to be detected by Phosphoric acid ammonium molybdate method.

Molibdênio via semente e nitrogênio em cobertura no feijoeiro irrigado em solo de cerrado / Molybdenum applied to seeds and sidedressing nitrogen on irrigated common bean in cerrado soil

O nitrogênio é o nutriente mais exigido pelo feijoeiro e seu metabolismo pode ser seriamente prejudicado pela deficiência de molibdênio. Conduziu-se este trabalho, com o objetivo de avaliar o efeito da aplicação de molibdênio via semente e nitrogênio em cobertura nas características agronômicas e produtividade do feijoeiro 'BRS Pontal' irrigado, cultivado em Neossolo Quartzarênico, no município de Cassilândia, MS. O delineamento experimental utilizado foi o de blocos casualizados, no esquema fatorial 4x2, com quatro repetições. Os tratamentos foram constituídos pela aplicação ou não de Mo (80 g ha-1) via semente e quatro doses de N (0, 30, 60 e 120 kg ha-1), em cobertura aos 16 dias, após a emergência, na forma de uréia. A aplicação de Mo via semente aumentou o índice relativo de clorofila, o número de vagens por planta, a massa e a produtividade de grãos no feijoeiro, principalmente com o uso de altas doses de N em cobertura. O índice relativo de clorofila, o número de vagens por planta, a massa e a produtividade de grãos do feijoeiro foi aumentada linearmente pela aplicação de até 120 kg ha-1 de N em cobertura. O fornecimento de Mo via tratamento de semente aumentou a eficiência de utilização do N pelo feijoeiro.

Nitrogen is the most required nutrient by common bean and its metabolism depends on the molybdenum supply. The objective of this work was to evaluate the effect of the molybdenum applied to seeds as well as the effect of sidedressing nitrogen on agronomic characteristics of irrigated common bean, cultivar BRS Pontal, grown on Typic Quartzipsamment, in Cassilância county, Mato Grosso do Sul State, Brazil. A randomized complete block design was used, in a 4x2 factorial array with four replications. The treatments were constituted of absence or presence of Mo (80g ha-1) applied to seeds, and four N doses (0, 30, 60, and 120 kg ha-1) applied 16 days after emergence, as urea. Molybdenum applied to seeds increased the relative chlorophyll index, number of pods per plant, mass of grains, and grain yield, mainly with high N-sidedressing rates. The N-sidedressing application up to the highest dose (120 kg ha-1) promoted a linear increase in the relative chlorophyll index, number of pods per plant, mass of grains and grain yield. Molybdenum applied to seeds increased the efficiency of N use by common bean.

Reduction of Mo(VI) by the bacterium Serratia sp. strain DRY5.

The need to isolate efficient heavy metal reducers for cost effective bioremediation strategy have resulted in the isolation of a potent molybdenum-reducing bacterium. The isolate was tentatively identified as Serratia sp. strain DRY5 based on the Biolog GN carbon utilization profiles and partial 16S rDNA molecular phylogeny. Strain DRY5 produced 2.3 times the amount of Mo-blue than S. marcescens strain Dr.Y6, 23 times more than E. coli K12 and 7 times more than E. cloacae strain 48. Strain DRY5 required 37 oC and pH 7.0 for optimum molybdenum reduction. Carbon sources such as sucrose, maltose, glucose and glycerol, supported cellular growth and molybdate reduction after 24 hr of static incubation. The most optimum carbon source that supported reduction was sucrose at 1.0% (w/v). Ammonium sulphate, ammonium chloride, glutamic acid, cysteine, and valine supported growth and molybdate reduction with ammonium sulphate as the optimum nitrogen source at 0.2% (w/v). Molybdate reduction was optimally supported by 30 mM molybdate. The optimum concentration of phosphate for molybdate reduction was 5 mM when molybdate concentration was fixed at 30 mM and molybdate reduction was totally inhibited at 100 mM phosphate. Mo-blue produced by this strain shows a unique characteristic absorption profile with a maximum peak at 865 nm and a shoulder at 700 nm. Dialysis tubing experiment showed that 95.42% of Mo-blue was found in the dialysis tubing suggesting that the molybdate reduction seen in this bacterium was catalyzed by enzyme(s). The characteristics of isolate DRY5 suggest that it would be useful in the bioremediation of molybdenum-containing waste.

Characterization of the 90 kDa heat shock protein (HSP90)-associated ATP/GTPase.

The 90 kDa heat shock protein (HSP90) is an ATP-binding molecular chaperone with an associated ATPase activity having nucleoplasmin and HSP70-binding homology domains and containing Ca-binding EF-hands and a nuclear localization signal. Here we characterize the HSP90-associated ATPase and show that it is (i) a P-type ATPase inhibited by molybdate and vanadate, (ii) able to hydrolyze methylfluorescein phosphate with a 5–6-fold higher affinity, (iii) a 3-times better GTPase than ATPase in the presence of calcium and (iv) HSP27 and F-actin, but not HSP10 can “convert” the HSP90-associated ATPase activity to HSP90 autokinase activity. The HSP90-associated ATP/GTPase may participate in the regulation of complex formation of HSP90 with other proteins, such as F-actin, tubulin and heat shock proteins.

STUDIES ON THE PHOSPHOLIPIDS AND FATTY ACIDS IN TRADITIONAL CHINESE MEDICINAL MATERIALS HIPPOCAMPUS AND SYNGNATHUS / 中国海洋药物

This paper deals with the analysis of the phospholipids and fatty acids in Hippocomnpus kelloggi Jordan et Synder, H. Histrix Kaup, II. trimaculalus Leach, II. kuda Bleeder, II. japonicus Kaup, Solenognathus hardwickii(Gray), Syngnathoides biacufcatus(Bloch) and Tracliyrliamphus serralus (Temminck &. Schlegel).The total phospholipids were extracted with Folch solvent and determined by molybdate blue spec-trophotometric method. The result showed that the contents of total phospholipids in these spccimins were 2. 56-7. 82mg/g.The nine kinds of phospholipid standards of absorbance proportional coefficient were detected in this paper. The phospholipid components were separated and determined by using thin - layer chro-matographic method and Vaskovsky solvent as a specific spray reagent. The quantitative analysis of the distribution of various phospholipids components in these specimen ts were carried out, by using TLC scanning and the corrective method of absorbance proportional coefficient. The resut showed that the Hippocampus contains about five phospholipids: lysophosphatidylcholine, sphingornyelin, phophatidylcholine, phosphatidylinositol, and phosphatidylethanolamine. The phosphatidylserine , phosphatidylglycerol, diphosphatidylglycerol and phosphatidic acid were more in Syugnathus than in Hippocampus, But in all these specimens, the main phospholipid components were lysophos- phatidylcholine, sphingornyelin and phosphatidylcholine.Fourteen fatty acid compositions in these specimens were analysed by GC -MS -DS. The result showed that the main fatty acid were hexadecanoic acid, 9 - octadecenoic acid, 8,11- octadeca-dienoic acid and 1,7,10,13,16,19 - docosahexaenoic acid.

Primary Study on Co-inoculum of Peanut Bradyrhizobium and Molybdate and Boron / 微生物学通报

Aiming at molybdate and boron deficient acid purple soil from main peanut cultivated areas in Sichuan,and Mo and B requirement of peanut growth,the feasibility of Co-inoculum of peanut Bradyrhizobium and molybdate and boron was studied.The tolerance to molybdate and boron of the tested strains Spr2-9,Spr4-5 was inspected.The result indicated that the two tested strains could tolerate higher concentration of molybdate than that of boron.The compound inoculum of Bradyrhizobial strain and trace element Mo was developed.The optimum concentration of Mo was 0.4%.