Certain yeast cells on solid nutrient medium produced colonies surrounded by a light zone of selenite absorption. This screening procedure resulted in the selection of 22 strains out of 200 isolates with different Se4+-absorbing capacity ranging from 16 to 98.8 g Se4+ g–1 l–1 h–1. The highest rate of Se4+ elimination from the Na2SeO3 solution was observed with an oval shaped, cream pigmented fermentative yeast, tentatively called Candida sp. strain MS4. This strain was isolated from wastewater and found to accumulate selenium oxyanions. Se4+ uptake involved both inactive and active phenomena. The amounts of selenium (initial concentration 2 mg Se4+ l–1) removed from aqueous solution by inactive and active phenomena were 667 g Se4+ g–1 l–1, and 1580 g Se4+ g–1 l–1, respectively. The strain also removed selenate inactively (135 g Se6+ g–1 l–1). 相似文献
Methyl tert-butyl ether (MTBE) is widely used as gasoline oxygenate and octane number enhancer for more complete combustion
in order to reduce the air pollution caused by motor vehicle exhaust. The possible adverse effects of MTBE on human health
are of major public concern. However, information on the metabolism of MTBE in human tissues is scarce. The present study
demonstrates that human cytochrome P450 2A6 is able to metabolize MTBE to tert-butyl alcohol (TBA), a major circulating metabolite
and marker for exposure to MTBE. As CYP2A6 is known to be constitutively expressed in human livers, we infer that it may play
a significant role in metabolism of gasoline ethers in liver tissue. 相似文献
Despite continuous improvements in culturing and recovery techniques, high-titer stocks of purified disabled herpes simplex virus type-1 (HSV-1 DIS) vector for drug discovery and use in preclinical and clinical trials are currently difficult to achieve. Efforts to improve their centrifugal recovery have been addressed in this paper. The operation of a swing-out centrifuge rotor was assessed, and its operational conditions were defined for the recovery of viable HSV-1 DIS. 80% virus recovery was achieved after 90 min at 26000g. The 20% loss of virus was attributed to damage to the viral envelope by overcompaction of the pellet and impaction with the base of the centrifuge tube. Virus recovery was increased by a further 10% by using a fixed-angle centrifuge rotor operating at 26000g. Plaque assays of recovered HSV-1 DIS gave values on the order of 10(6) pfu/mL, compared to values typically above 10(9) pfu/mL obtained for the replication-competent HSV-1 viron. 相似文献
Leishmania major is the causative agent and Phlebotomus papatasi is the main vector of rural zoonotic cutaneous leishmaniasis (ZCL) in Iran and elsewhere. Nested PCR protocols were used to amplify a region of the ribosomal RNA amplicon of Leishmania (ITS1-5.8S rRNA gene) in female P. papatasi. In the current investigation, L. major was found in Natanz, Isfahan province in centre of Iran, in a focus of rural ZCL. Ten (1.8%) out of 549 female P. papatasi was found to be infected with L. major based on the PCR detection and sequencing of parasite ITS-rDNA.Nine (1.8%) out of 498 female P. papatasi infected with L. major came from animal shelters, inside houses and yards. And one (1.9%) out of 51 female P. papatasi infected with L. major came from gerbil borrows. Infection rates were higher for females containing red blood meals, large eggs (semi-mature and mature) than for those without either blood meals or eggs. From the 10 infections detected three different haplotypes of L. major were identified. Two haplotypes were found to be novel. The other haplotypes of L. major was found to be identical to that of isolates of L. major from Iran and in elsewhere using GenBank data. Comparisons of infection rates between habitats will be inaccurate when the proportions of blood-fed and gravid flies differ among sandfly samples. 相似文献
MOTIVATION: So far various statistical and machine learning techniques applied for prediction of beta-turns. The majority of these techniques have been only focused on the prediction of beta-turn location in proteins. We developed a hybrid approach for analysis and prediction of different types of beta-turn. RESULTS: A two-stage hybrid model developed to predict the beta-turn Types I, II, IV and VIII. Multinomial logistic regression was initially used for the first time to select significant parameters in prediction of beta-turn types using a self-consistency test procedure. The extracted parameters were consisted of 80 amino acid positional occurrences and 20 amino acid percentages in beta-turn sequence. The most significant parameters were then selected using multinomial logistic regression model. Among these, the occurrences of glutamine, histidine, glutamic acid and arginine, respectively, in positions i, i + 1, i + 2 and i + 3 of beta-turn sequence had an overall relationship with five beta-turn types. A neural network model was then constructed and fed by the parameters selected by multinomial logistic regression to build a hybrid predictor. The networks have been trained and tested on a non-homologous dataset of 565 protein chains by 9-fold cross-validation. It has been observed that the hybrid model gives a Matthews correlation coefficient (MCC) of 0.235, 0.473, 0.103 and 0.124, respectively, for beta-turn Types I, II, IV and VIII. Our model also distinguished the different types of beta-turn in the embedded binary logit comparisons which have not carried out so far. AVAILABILITY: Available on request from the authors. 相似文献
Aim of this study was to evaluate effects of Low-intensity pulsed ultrasound on repair of articular cartilage defects. Low-intensity pulsed ultrasound (Lipus) can induce the differentiation and activation of chondrocytes. This study was designed to evaluate the effect of Lipus on articular cartilage defects in a sheep. Eight sheep were divided in to two groups. The animals received bilateraly, articular cartilage defects 4 mm in diameter and 2 mm in deep on the patellar groove and experimental groups were treated with intensity 200 mW/cm2, 20 min/day with low-intensity pulsed ultrasound for 2 month. Then both knee joints underwent surgery for remove of formed tissue sample from defects.The samples were evaluated by Quantitative real-time polymerase chain reaction (qRT-PCR), Safranin-o staining, Immunofluorescence Staining and Morphological characterization. The best and worst sample per group according to Macroscopic and micriscopic scoring were icentified. The results showed that the operated groups with-Lipus-treatment and without-Lipus treatment had considered statistically significant. Gross photography revealed that the defects in experimental groups were filled with proliferative tissue, while in control groups, a thin layer of proliferative tissue was formed in defects. qRT-PCR results showed the expression of coll2, sox9, aggrecan and Osteocalcin in experimental groups. Intense safranin-O staining show the formation cartilage tissue in ultrasound treated group, while loose safranin-o-staining were observed at the control groups. Immunofluorescence staining showed the type 2 Collagen protein expression. We suggest that low-intensity pulsed ultrasound provide the mechanistic basis force for articular cartilage repair and effective treatment modality for improving of articular cartilage defects.
This article reports on the state-of-the-art technologies that sequence DNA using miniaturized devices. The article considers the miniaturization of existing technologies for sequencing DNA and the opportunities for cost reduction that 'on-chip' devices can deliver. The ability to construct nano-scale structures and perform measurements using novel nano-scale effects has provided new opportunities to identify nucleotides directly using physical, and not chemical, methods. The challenges that these technologies need to overcome to provide a US$1000-genome sequencing technology are also presented. 相似文献