共查询到20条相似文献，搜索用时 31 毫秒
1.
J. W. Parks M. A. Olson J. Kim D. Ozcelik H. Cai R. Carrion Jr. J. L. Patterson R. A. Mathies A. R. Hawkins H. Schmidt 《Biomicrofluidics》2014,8(5)
We describe the integration of an actively controlled programmable microfluidic sample processor with on-chip optical fluorescence detection to create a single, hybrid sensor system. An array of lifting gate microvalves (automaton) is fabricated with soft lithography, which is reconfigurably joined to a liquid-core, anti-resonant reflecting optical waveguide (ARROW) silicon chip fabricated with conventional microfabrication. In the automaton, various sample handling steps such as mixing, transporting, splitting, isolating, and storing are achieved rapidly and precisely to detect viral nucleic acid targets, while the optofluidic chip provides single particle detection sensitivity using integrated optics. Specifically, an assay for detection of viral nucleic acid targets is implemented. Labeled target nucleic acids are first captured and isolated on magnetic microbeads in the automaton, followed by optical detection of single beads on the ARROW chip. The combination of automated microfluidic sample preparation and highly sensitive optical detection opens possibilities for portable instruments for point-of-use analysis of minute, low concentration biological samples. 相似文献
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BackgroundThis study aimed to develop an amplification method of urea detection based on pH-sensitive liposomes.ResultsThe urease covalently immobilized on the magnetic particles and the pH-sensitive liposomes encapsulating ferricyanide were added to the cyclic-voltammeter cell solution where urea was distributed. The conversion of urea into carbonic acid seemed to induce a pH decrease that caused a reduction in the electrostatic repulsion between the headgroups of weakly acidic 1,2-dipalmitoyl-sn-glycero-3-succinate. The reduction induced the liposomes to release potassium ferricyanide that was encapsulated inside. The effects of urea concentration and pH value were investigated. A specific concentration (0.5 mg/mL) of the urea solution was set to observe the response. The activity of urease was reversible with respect to the pH change between 7 and 5. The sensitivity of this detection was almost identical to the comparable techniques such as an enzyme-linked immunosorbent assay and a field-effect transistor.ConclusionsIn summary, the methodology developed in this study was feasible as a portable, rapid, and sensitive method.How to cite: Kang MK, Park J-W. Amplification of urea detection based on pH-sensitive liposomes. Electron J Biotechnol 2021;51. https://doi.org/10.1016/j.ejbt.2021.04.005 相似文献
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BackgroundWheat is one of the most important crops cultivated all over the world. New high-yielding cultivars that are more resistant to fungal diseases have been permanently developed. The present study aimed at the possibility of accelerating the process of breeding new cultivars, resistant to eyespot, by using doubled haploids (DH) system supported by marker-assisted selection.ResultsTwo highly resistant breeding lines (KBP 0916 and KBH 4942/05) carrying Pch1 gene were crossed with the elite wheat genotypes. Hybrid plants of early generations were analyzed using endopeptidase EpD1 and two SSR markers linked to the Pch1 locus. Selected homozygous and heterozygous genotypes for the Pch1-linked EpD1b allele were used to produce haploid plants. Molecular analyses were performed on haploids to identify plants possessing Pch1 gene. Chromosome doubling was performed only on haploid plants with Pch1 gene. Finally, 65 DH lines carrying eyespot resistance gene Pch1 and 30 lines without this gene were chosen for the eyespot resistance phenotyping in a field experiment.ConclusionsResults of the experiment confirmed higher resistance to eyespot of the genotypes with Pch1 in comparison to those without this gene. This indicates the efficiency of selection at the haploid level.How to cite: Wiśniewska H, Majka M, Kwiatek M, et al. Production of wheat doubled haploids resistant to eyespot supported by marker-assisted selection. Electron J Biotechnol 2019;37. https://doi.org/10.1016/j.ejbt.2018.10.003 相似文献
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BackgroundCultivated peanut (Arachis hypogaea L.) is a major oilseed crop worldwide. Fatty acid composition of peanut oil may affect the flavor and shelf life of the resulting food products. Oleic acid and linoleic acid are the major fatty acids of peanut oil. The conversion from oleic acid to linoleic acid is controlled by the Δ12 fatty acid desaturase (FAD) encoded by AhFAD2A and AhFAD2B, two homoeologous genes from A and B subgenomes, respectively. One nucleotide substitution (G:C → A:T) of AhFAD2A and an “A” insertion of AhFAD2B resulted in high-oleic acid phenotype. Detection of AhFAD2 mutation had been achieved by cleaved amplified polymorphic sequence (CAPS), real-time polymerase chain reaction (qRT-PCR) and allele-specific PCR (AS-PCR). However, a low cost, high throughput and high specific method is still required to detect AhFAD2 genotype of large number of seeds. Kompetitive allele specific PCR (KASP) can detect both alleles in a single reaction. The aim of this work is to develop KASP for detection AhFAD2 genotype of large number of breeding materials.ResultsHere, we developed a KASP method to detect the genotypes of progenies between high oleic acid peanut and common peanut. Validation was carried out by CAPS analysis. The results from KASP assay and CAPS analysis were consistent. The genotype of 18 out of 179 BC4F2 seeds was aabb.ConclusionsDue to high accuracy, time saving, high throughput feature and low cost, KASP is more suitable for determining AhFAD2 genotype than other methods. 相似文献
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BackgroundRice sheath blight (caused by Rhizoctonia solani) and tobacco mosaic virus are very important plant diseases, causing a huge loss in global crop production. Paenibacillus kribbensis PS04 is a broad-spectrum biocontrol agent, used for controlling these diseases. Previously, extracellular polysaccharides (EPS) from P. kribbensis PS04 had been purified and their structure was inferred to be fructosan. This study aimed to evaluate the effects of exogenous EPS treatment on plant–pathogen interactions.ResultsPlant defense genes such as phenylalanine ammonia-lyase, catalase, chitinase, allene oxide synthase, and PR1a proteins were significantly induced by exogenous EPS treatment. Moreover, subsequent challenge of EPS-pretreated plants with the pathogens (R. solani or tobacco mosaic virus) resulted in higher expression of defense-associated genes. Increased activities of defense-associated enzymes, total phenols, and flavonoids were also observed in EPS pretreated plants. The contents of malondialdehyde in plants, which act as indicator of lipid peroxidation, were reduced by EPS treatment.ConclusionsThis study comprehensively showed that EPS produced from P. kribbensis PS04 enhances disease resistance in plants by the activation of defense-associated genes as well as through the enhancement of activities of defense-related enzymes.How to citeCanwei S, Xiaoyun H, Ahmed N, et al. Fructosan form Paenibacillus kribbensis PS04 enhance disease resistance against Rhizoctonia solani and tobacco mosaic virus. Electron J Biotechnol 2020;47. https://doi.org/10.1016/j.ejbt.2020.07.002 相似文献
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Backgroundβ-Glucosidase assay is performed with purified or semipurified enzymes extracted from cell lysis. However, in screening studies, to find bacteria with β-glucosidase activity among many tested bacteria, a fast method without cell lysis is desirable. In that objective, we report an in vivo β-glucosidase assay as a fast method to find a β-glucosidase producer strain.ResultsThe method consists in growing the strains for testing in a medium supplemented with the artificial substrate p-nitrophenyl-β-glucopyranoside (pNPG). The presence of β-glucosidases converts the substrate to p-nitrophenol (pNP), a molecule that can be easily measured in the supernatant spectrophotometrically at 405 nm. The assay was evaluated using two Bifidobacterium strains: Bifidobacterium longum B7254 strain that lacks β-glucosidase activity and Bifidobacterium pseudocatenulatum B7003 strain that shows β-glucosidase activity. The addition of sodium carbonate during pNP measurement increases the sensitivity of pNP detection and avoids the masking of absorbance by the culture medium. Furthermore, we show that pNP is a stable enzymatic product, not metabolized by bacteria, but with an inhibitory effect on cell growth. The β-glucosidase activity was measured as units of enzyme per gram per minute per dry cell weight. This method also allowed the identification of Lactobacillus strains with higher β-glucosidase activity among several lactobacillus species.ConclusionThis in vivo β-glucosidase assay can be used as an enzymatic test on living cells without cell disruption. The method is simple, quantitative, and recommended, especially in studies screening for bacteria not only with β-glucosidase activity but also with high β-glucosidase activity. 相似文献
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《Electronic Journal of Biotechnology》2014,17(2):95-101
BackgroundWeedy rice (Oryza sativa L.) is a noxious form of cultivated rice (O. sativa L.) associated with intensive rice production and dry seeding. A cost-efficient strategy to control this weed is the Clearfield rice production system, which combines imidazolinone herbicides with mutant imidazolinone-resistant rice varieties. However, imidazolinone resistance mutations can be introgressed in weedy rice populations by natural outcrossing, reducing the life span of the Clearfield technology. Timely and accurate detection of imidazolinone resistance mutations in weedy rice may contribute to avoiding the multiplication and dispersion of resistant weeds and to protect the Clearfield system. Thus, highly sensitive and specific methods with high throughput and low cost are needed. KBioscience’s Allele Specific PCR (KASP) is a codominant, competitive allele-specific PCR-based genotyping method. KASP enables both alleles to be detected in a single reaction in a closed-tube format. The aim of this work is to assess the suitability and validity of the KASP method for detection in weedy rice of the three imidazolinone resistance mutations reported to date in rice.ResultsValidation was carried out by determining the analytical performance of the new method and comparing it with conventional allele-specific PCR, when genotyping sets of cultivated and weedy rice samples. The conventional technique had a specificity of 0.97 and a sensibility of 0.95, whereas for the KASP method, both parameters were 1.00.ConclusionsThe new method has equal accuracy while being more informative and saving time and resources compared with conventional methods, which make it suitable for monitoring imidazolinone-resistant weedy rice in Clearfield rice fields. 相似文献
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BackgroundInfectious Pancreatic Necrosis Virus (IPNV) is the etiological agent of a highly contagious disease that affects salmonids. In Chile, the second worldwide salmon producer, IPNV causes great economic loss and is one of the most frequently detected pathogens. Due to its high level of persistence and the lack of information about the efficiency of its diagnostic techniques, the National Reference Laboratory (NRL) for IPNV in Chile performed the first inter-laboratory ring trial, to evaluate the sensitivity, specificity and repeatability of the qRT-PCR detection methods used in the country.ResultsResults showed 100% in sensitivity and specificity in most of the laboratories. Only three of the twelve participant laboratories presented problems in sensitivity and one in specificity. Problems in specificity (false positives) were most likely caused by cross contamination of the samples, while errors in sensitivity (false negatives) were due to detection problems of the least concentrated viral sample. Regarding repeatability, many of the laboratories presented great dispersion of the results (Ct values) for replicate samples over the three days of the trial. Moreover, large differences in the Ct values for each sample were detected among all the laboratories.ConclusionsOverall, the ring trial showed high values of sensitivity and specificity, with some problems of repeatability and inter-laboratory variability. This last issue needs to be addressed in order to allow harmonized diagnostic of IPNV within the country. We recommend the use of the NRL methods as validated and reliable qRT-PCR protocols for the detection of IPNV. 相似文献
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BackgroundAscorbic acid (Asc) is one of the most abundant antioxidants and it serves as a major contributor to protect plants against oxidative damage. Plants use two enzymes that participate in the metabolic recycling of Asc. One of these two enzymes is dehydroascorbate reductase (DHAR). It directly regenerates Asc from its oxidized state and thus prevents Asc from being irreversibly hydrolyzed to 2, 3-diketogulonic acid. This study aimed to examine whether over-expression of DHAR leads to an enhanced oxidative stress tolerance in tobacco plants.ResultsIn this study, we functionally characterized a novel JcDHAR gene from Jatropha curcas and found via quantitative RT-PCR analysis that JcDHAR can be induced with H2O2, salt and PEG stresses. The DHAR activities of transgenic tobacco plants increased from 2.0 to 5.3 fold compared to wild-type plants. As a result, the transgenic plants displayed enhanced tolerance to oxidative stress.ConclusionsOur results indicate that JcDHAR expression can effectively enhance the tolerance to oxidative stress in plants. 相似文献
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BackgroundAgkistrodon acutus, a traditional Chinese medicine, clinically used in the treatment of rheumatism, tumor, and cardiovascular and cerebrovascular diseases. Due to the unique medicinal value and the difficulty of artificial breeding of Agkistrodon acutus, the supply of Agkistrodon acutus on the market exceeds the demand, and a large number of its adulterants are found on the market. In this study, the cytb gene sequences of Agkistrodon acutus and 9 snakes were compared and analyzed, specific primers were designed, and specific PCR methods were established to detect Agkistrodon acutus medicinal samples on the market.ResultsThis method was successfully applied to distinguish the snake from other adulterated species, and tested 18 Agkistrodon acutus samples randomly purchased from six cities. Twelve samples were counterfeit and six were genuine. The standard reference material of Agkistrodon acutus was cloned by molecular cloning and sequencing, and the gene sequence difference with other species was significant. It shows that the region could be used as the fingerprint region of the target species.ConclusionsThe proposed method can be used as a species-specific marker and can be highly distinguished from other adulterated snake species, which is helpful to effectively avoid the problem of false sale of Agkistrodon acutus.How to cite: Yingnuo L, Yanshuang W, Mingcheng Li, et al. Development of a species-specific PCR assay for authentication of Agkistrodon acutus based on mitochondrial cytochrome b gene. Electron J Biotechnol 2021;49. https://doi.org/10.1016/j.ejbt.2020.07.005 相似文献
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BackgroundBanana (Musa spp.) is an important staple food, economic crop, and nutritional fruit worldwide. Conventional breeding has been seriously hampered by their long generation time, polyploidy, and sterility of most cultivated varieties. Establishment of an efficient regeneration and transformation system for banana is critical to its genetic improvement and functional genomics.ResultsIn this study, a vigorous and repeatable transformation system for banana using direct organogenesis was developed. The greatest number of shoots per explant for all five Musa varieties was obtained using Murashige and Skoog medium supplemented with 8.9 μM benzylaminopurine and 9.1 μM thidiazuron. One immature male flower could regenerate 380–456, 310–372, 200–240, 130–156, and 100–130 well-developed shoots in only 240–270 d for Gongjiao, Red banana, Rose banana, Baxi, and Xinglongnaijiao, respectively. Longitudinal sections of buds were transformed through particle bombardment combined with Agrobacterium-mediated transformation using a promoterless β-glucuronidase (GUS) reporter gene; the highest transformation efficiency was 9.81% in regenerated Gongjiao plantlets in an optimized selection medium. Transgenic plants were confirmed by a histochemical assay of GUS, polymerase chain reaction, and Southern blot.ConclusionsOur robust transformation platform successfully generated hundreds of transgenic plants. Such a platform will facilitate molecular breeding and functional genomics of banana. 相似文献
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病毒检测与防御是计算机安全中的一个很重要的研究课题。目前,计算机病毒的花样不断地翻新,并大量使用了多重加密壳、变形、多态,传统的恶意代码查杀技术很难进行正确的查杀,这是因为病毒代码被感染后,为了躲避检测会对自己本身的代码修改替换。即使是针对未知的恶意代码,如果只是运用简单的模式匹配算法,也会被恶意代码欺骗而逃避检测。本文介绍了一种能够检测以上未知恶意代码的方法。具体来说,首先将病毒的二进制代码进行反汇编,在汇编代码层次上进行检出以及通过汇编层次检测出的模式学习和根据学习结果的分类判定来进行检测。 相似文献
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Qianqian Zhou Tze Ping Loh Tony Badrick Chun Yee Lim 《Biochemia medica : ?asopis Hrvatskoga dru?tva medicinskih biokemi?ara / HDMB》2021,31(2)
IntroductionIt is unclear what is the best strategy for applying patient-based real-time quality control (PBRTQC) algorithm in the presence of multiple instruments. This simulation study compared the error detection capability of applying PBRTQC algorithms for instruments individually and in combination using serum sodium as an example.Materials and methodsFour sets of random serum sodium measurements were generated with differing means and standard deviations to represent four simulated instruments. Moving median with winsorization was selected as the PBRTQC algorithm. The PBRTQC parameters (block size and control limits) were optimized and applied to the four simulated laboratory data sets individually and in combination.ResultsWhen the PBRTQC algorithm were individually optimized and applied to the data of the individual simulated instruments, it was able to detect bias several folds faster than when they were combined. Similarly, the individually applied algorithms had perfect error detection rates across different magnitudes of bias, whereas the error detection rates of the algorithm applied on the combined data missed smaller biases. The performance of the individually applied PBRTQC algorithm performed more consistently among the simulated instruments compared to when the data were combined.DiscussionWhile combining data from different instruments can increase the data stream and hence, increase the speed of error detection, it may widen the control limits and compromising the probability of error detection. The presence of multiple instruments in the data stream may dilute the effect of the error when it only affects a selected instrument. 相似文献
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J. P. Prasad Y. Madhu Arushi Mandhan Payal Garg Anu Prakash Varsha Singh Daud Ali Prdeep Kumar Surinder Singh G. R. Soni Varun Singh 《Indian journal of clinical biochemistry : IJCB》2017,32(2):243-245
Current study is conducted to evaluate method verification of two locally available kits manufactured by DSI & BIORAD for quantitative estimation of Hepatitis B virus antibodies in human normal immunoglobulin by using International standard of National Institute of Biological Standards and Control. Four analyst perform five sets of test in duplicate analysing accuracy, precision, and limit of detection, sensitivity and specificity. Our results suggest that both DSI and BIORAD kits fulfil the validation criteria and are sensitive to detect up to 10 mIU concentration precisely and accurately. DSI kit is more precise at concentration 100 mIU and economically 4–5 times cheaper in local market; on the other hand, BIORAD kits provide larger detection range up to 1000 mIU. 相似文献
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H. Ravi Kumar K. S. Devaraju B. M. Prakash S. Sampath Kumar S. V. Suresh Babu N. Ramachandraswamy H. P. Puttaraju 《Indian journal of clinical biochemistry : IJCB》2009,24(3):275-279
To establish/develop an assay method for measuring Ornithine Aminotransferase (EC.2.6.1.13) activity using rat brain mitochondria
as a source of enzyme in presence and absence of Pyridoxal Phosphate (PLP). The modified method, with the improved sensitivity,
is adopted for the assay of ornithine amino transferase activity in rat brain mitochondria. The enzyme activity was measured
at 620 nm, the study showed that reaction was optimum at 37°C for 30 minutes. The assay is sensitive enough to detect activity
at the order of nanomoles pyrroline-5-carboxylate/mg protein/minute and can be compared as an alternative to the radio isotopic
method which is more cumbersome and aminobenzaldehyde method which is less sensitive. The Km & Vmax shows maximum activity in the presence of Pyridoxal Phosphate (Coenzyme) concentration at 0.05mM when compared with absence
of Pyridoxal Phosphate as higher the concentration of Pyridoxal Phosphate affects the affinity of the enzyme to substrate.
The OAT activity in different tissues of the rat was also studied and highest activity was found in liver and kidney. 相似文献
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BackgroundA protocol for the micropropagation of the grape (Vitis vinifera L.) cultivar ‘Monastrell’ was developed. Initial plant material was obtained from the sanitary selection of grapevine plants performed by real-time RT-PCR to confirm the absence of Grapevine fanleaf virus, Arabis mosaic virus, Grapevine leafroll-associated virus 1, Grapevine leafroll-associated virus 3, and Grapevine fleck virus.ResultsThe effects of the salt composition (comparing Lloyd and McCown woody plant medium and Murashige and Skoog medium 1/2 macronutrients) and the growth regulator benzylaminopurine (BAP), at 0 and 8.9 μM, on plant propagation were evaluated using nodes as explants. The most efficient procedure consisted of bud induction in the medium with Lloyd and McCown woody plant salts and 8.9 μM BAP for 30 d along with elongation in cytokinin-free medium for 60 d, which gave 22 nodes/explant (174 plants/initial plant). A second cycle of propagation in a medium without BAP for another 60 d could give approximately 10,000 nodes, which can be obtained after an additional 2 months of culture. All plants acclimatized after the second cycle of multiplication were successfully transferred to soil.ConclusionWe developed an optimal protocol for V. vinifera cv. ‘Monastrell’ micropropagation, the first described for this cultivar. 相似文献