55 research outputs found
Direct visualization of the reaction transformation and signal amplification in a DNA molecular machine with total internal reflection fluorescence microscopy
No full textIn this study, as a proof of concept, the signal amplification in an artificial DNA molecular machine was directly visualized via total internal reflection fluorescence microscopy (TIRFM). The molecular machine brought about obvious morphology change in DNA nanostructures as well as signal amplifications. On one hand, through a triggered and autonomically repeated RCA, a DNA nano-complex featuring a locked circular DNA template (serving as raw feed) was converted into a long periodically repeated strand, i.e. the RCA products. Furthermore, this RCA was repeated in three controllable reaction phases, bring about progressive signal amplification. It was testified that the RCA products (presented as long thread-like fluorescent objects) can be easily distinguished from the inputted DNA probes (presented as fluorescent dots), thus the transformation in reaction can be visualized. Also, by quantitive counting of the aforementioned fluorescence objects, the progress of the reaction through the phases, along with time, and over the lysozyme concentration can be demonstrated through TIRFM visualization. Overall, it was demonstrated that TIRFM is an efficient approach to quantitively visualize the biochemical processes at single-molecule level
Physiological and metabolic changes of purslane (Portulaca oleracea L.) in response to drought, heat and combined stresses
No full textPurslane (Portulaca oleracea L.) is a fleshy herbaceous plant. So far, little information is available on the response of this plant to combined drought and heat stress. In this study, changes in physiological and metabolic levels were characterized after treatments with drought, heat and combined stresses. Both individual and combined stress treatments increased malondialdehyde (MDA), electrolyte leakage (EL), O2•− and activities of superoxide dismutase (SOD), peroxidase (POD), while declined chlorophyll content. No significant differences were found between control and treatments in leaf water content (LWC) and catalase (CAT) activity. Additionally, 37 metabolic compounds were detected in purslane. Through pathway analysis, 17 metabolites were directly involved in the glycolysis metabolic pathway. The present study indicated that combined drought and heat stress caused more serious damage in purslane than individual stress. To survive, purslane has a high capability to cope with environmental stress conditions through activation of physiological and metabolic pathways
Criteria for assessing the cooperative extension program planning process in the West central district of Virginia
No full textThe success of cooperative extension depends on the knowledge of how to apply the principles of extension education to situations where the activities are to be performed. The cooperative extension services dynamic localized approach to the solution of the common persons problem has stood the test of time. It is not necessary to establish a new system, but what is needed is to increase accountability and efficiency in the way programs are planned and developed.
The overall purpose of this study was to develop criteria for assessing the local cooperative extension program planning process in Virginia. Specific objectives that served as a basis for accomplishing the overall purpose of the study were:
1. To identify principles that are basic for planning an effective local extension program.
2. To verify these principles with a panel of experts.
3. To formulate criteria, based on the verified principles, to assess if on-going local extension programs were developed following the accepted programming principles.
4. To field test the criteria to determine the degree to which the criteria are used as guides during the local extension program planning process.
This study was a qualitative study. The principles identified and the criteria developed were reviewed by a panel of eight experts, then field tested in randomly selected extension units in the West Central Extension District of Virginia. Using personal interview methodology, unit directors of the randomly selected units were used for the field testing stage of this study.
Six of the seven principles identified as basic for planning/developing effective local extension programs were accepted by the panel of experts. Eighteen criteria were formulated based on the accepted principles. Criteria as used in this study implies an overall description of a set of related actions and/or operations which will be called standards of the planning process. It was found that most of the unit directors in the West-Central Extension District of Virginia interviewed for this study use the criteria as guides during their respective programming process. The panel of experts and unit directors agreed that the criteria were important as guides for local extension programming processes.
Based on the findings the author concluded that: (a) there are six essential principles for planning effective social extension programs; (b) that there are 18 criteria that can be used as guides for assessing if local extension programs are planned/developed using the essential extension program planning principles; and (c) that it is possible to assess local program planning activities in extension.
A recommendation made from the study that the process of assessing local program planning activities be tested statewide to increase the usability potential of the criteria and give possible directions for statewide in-service needs of unit directors and extension agents.Ed. D.incomplete_metadat
Trichinella spiralis, potential model nematode for epigenetics and its implication in metazoan parasitism
No full textThe recent discovery of DNA methylation in the nematode T. spiralis may raise the possibility of using it as a potential model organism for epigenetic studies instead of C. elegans, which is deficient in this important epigenetic modification. In contrast to the free-living nematode C. elegans, T. spiralis is a parasitic worm that possesses a complicated life cycle and undergoes a complex developmental regulation of genes. We emphasise that the differential methylomes in the different life-history stages of T. spiralis can provide insight on how DNA methylation is triggered and regulated. In particular, we have demonstrated that DNA methylation is involved in the regulation of its parasitism-related genes. Further computational analyses indicated that the regulatory machinery for DNA methylation can also be found in the T. spiralis genome. By a logical extension of this point, we speculate that comprehensively addressing the epigenetic machinery of T. spiralis may help to understand epigenetics in invertebrates. Furthermore, considering the implication of epigenetics in metazoan parasitism, using T. spiralis as an epigenetic model organism may further contribute to drug development against metazoan parasites
Negative modulation of NMDA receptor channel function by DREAM/calsenilin/KChIP3 provides neuroprotection?
No full textN-methyl D-aspartate receptors (NMDARs) are glutamate-gated ion channels highly permeable to calcium and essential to excitatory neurotransmission. The NMDARs have attracted much attention because of their role in synaptic plasticity and excitotoxicity. Evidence has recently accumulated that NMDARs are negatively regulated by intracellular calcium binding proteins. The calcium-dependent suppression of NMDAR function serves as a feedback mechanism capable of regulating subsequent Ca2+ entry into the postsynaptic cell, and may offer an alternative approach to treating NMDAR-mediated excitotoxic injury. This short review summarizes the recent progress made in understanding the negative modulation of NMDAR function by DREAM/calsenilin/KChIP3, a neuronal calcium sensor protein
Frequency-dependent brain regional homogeneity alterations in patients with mild cognitive impairment during working memory state relative to resting state
No full textSeveral studies have reported working memory deficits in patients with mild cognitive impairment (MCI). However, previous studies investigating the neural mechanisms of MCI have primarily focused on brain activity alterations during working memory tasks. No study to date has compared brain network alterations in the working memory state between MCI patients and normal control subjects. Therefore, using the index of regional homogeneity (ReHo), we explored brain network impairments in MCI patients during a working memory task relative to the resting state, and identified frequency-dependent effects in separate frequency bands.Our results indicate that, in MCI patients, ReHo is altered in the posterior cingulate cortex in the slow-3 band (0.073–0.198 Hz), and in the bottom of the right occipital lobe and part of the right cerebellum, the right thalamus, a diffusing region in the bilateral prefrontal cortex, the left and right parietal-occipital regions, and the right angular gyrus in the slow-5 band (0.01–0.027 Hz). Furthermore, in normal controls, the value of ReHo in clusters belonging to the default mode network decreased, while the value of ReHo in clusters belonging to the attentional network increased during the task state. However, this pattern was reversed in MCI patients, and was associated with decreased working memory performance. In addition, we identified altered functional connectivity of the abovementioned regions with other parts of the brain in MCI patients.This is the first study to compare frequency-dependent alterations of ReHo in MCI patients between resting and working memory states. The results provide a new perspective regarding the neural mechanisms of working memory deficits in MCI patients, and extend our knowledge of altered brain patterns in resting and task-evoked states
Maternal separation produces alterations of forebrain brain-derived neurotrophic factor expression in differently aged rats
No full textEarly postnatal maternal separation (MS) can play an important role in the development of psychopathologies during ontogeny. In the present study, we investigated the effects of repeated MS (4 h per day from postnatal day [PND] 1–21) on the brain-derived neurotrophic factor (BDNF) expression in the medial prefrontal cortex (mPFC), the nucleus accumbens (NAc) and the hippocampus of male and female juvenile (PND 21), adolescent (PND 35) and young adult (PND 56) Wistar rats. The results indicated that MS increased BDNF in the CA1 and the dentate gyrus (DG) of adolescent rats as well as in the DG of young adult rats. However, the expression of BDNF in the mPFC in the young adult rats was decreased by MS. Additionally, in the hippocampus, there was decreased BDNF expression with age in both the MS and socially reared rats. However, in the mPFC, the BDNF expression was increased with age in the socially reared rats; nevertheless, the BDNF expression was significantly decreased in the MS young adult rats. In the NAc, the BDNF expression was increased with age in the male NMS rats, and the young adult female MS rats had less BDNF expression than the adolescent female MS rats. Th
Identification of Rubisco rbcL and rbcS in Camellia oleifera and Their Potential as Molecular Markers for Selection of High Tea Oil Cultivars
No full textTea oil derived from seeds of Camellia oleifera Abel. is a high-quality edible oil in China. This study isolated full-length cDNAs of Rubisco subunits rbcL and rbcS from C. oleifera. The rbcL has 1,522 bp with a 1,425 bp coding region, encoding 475 amino acids; and the rbcS has 841 bp containing a 528 bp coding region, encoding 176 amino acids. The expression level of the two genes, designated as Co-rbcL and Co-rbcS, was determined in three C. oleifera cultivars: Hengchong 8, Xianglin 1, and Xianglin 14 whose annual oil yields were 546.9, 591.4, and 657.7 kg ha-1, respectively. The Co-rbcL expression in ‘Xianglin 14’ was significantly higher than ‘Xianglin 1’, and ‘Xianglin 1’ was greater than ‘Hengchong 89’. The expression levels of Co-rbcS in ‘Xianglin 1’ and ‘Xianglin 14’ were similar but were significantly greater than in ‘Hengchong 89’. The net photosynthetic rate of ‘Xianglin 14’ was significantly higher than ‘Xianglin 1’, and ‘Xianglin 1’ was higher than ‘Hengchong 89’. Pearson’s correlation analysis showed that seed yields and oil yields were highly correlated with the expression level of Co-rbcL at P 0.001 level, and the expression of Co-rbcS was correlated with oil yield at P 0.01 level. Net photosynthetic rate was also correlated with oil yields and seed yields at P 0.001 and P 0.01 levels, respectively. Our results suggest that Co-rbcS and Co-rbcL in particular could potentially be molecular markers for early selection of high oil yield cultivars. In combination with the measurement of net photosynthetic rates, the early identification of potential high oil production cultivars would significantly shorten plant breeding time and increase breeding efficiency
Selection and validation of appropriate reference genes for quantitative real-time PCR analysis of gene expression in Lycoris aurea
No full textLycoris aurea (L' Hér.) Herb, a perennial grass species, produces a unique variety of pharmacologically active Amaryllidaceae alkaloids. However, the key enzymes and their expression pattern involved in the biosynthesis of Amaryllidaceae alkaloids (especially for galanthamine) are far from being fully understood. Quantitative real-time polymerase chain reaction (qRT-PCR), a commonly used method for quantifying gene expression, requires stable reference genes to normalize its data. In this study, to choose the appropriate reference genes under different experimental conditions, 14 genes including YLS8 (mitosis protein YLS8), CYP2 (Cyclophilin 2), CYP 1 (Cyclophilin 1), TIP41 (TIP41-like protein), EXP2 (Expressed protein 2), PTBP1 (Polypyrimidine tract-binding protein 1), EXP1 (Expressed protein 1), PP2A (Serine/threonine-protein phosphatase 2A), β-TUB (β-tubulin), α-TUB (α-tubulin), EF1-α (Elongation factor 1-α), UBC (Ubiquitin-conjugating enzyme), ACT (Actin) and GAPDH (Glyceraldehyde 3-phosphate dehydrogenase) were selected from the transcriptome datasets of L. aurea. And then, expressions of these genes were assessed by qRT-PCR in various tissues and the roots under different treatments. The expression stability of the 14 candidates was analyzed by three commonly used software programs (geNorm, NormFinder, and BestKeeper), and their results were further integrated into a comprehensive ranking based on the geometric mean. The results show the relatively stable genes for each subset as follows: (1) EXP1 and TIP41 for all samples; (2) UBC and EXP1 for NaCl stress; (3) PTBP1 and EXP1 for heat stress, polyethylene glycol (PEG) stress and ABA treatment; (4) UBC and CYP2 for cold stress; (5) PTBP1 and PP2A for sodium nitroprusside (SNP) treatment; (6) CYP1 and TIP41 for methyl jasmonate (MeJA) treatment; and (7) EXP1 and TIP41 for various tissues. The reliability of these results was further enhanced through comparison between part qRT-PCR result and RNA sequencing (RNA-seq) data. In summary, our results identified appropriate reference genes for qRT-PCR in L. aurea, and will facilitate gene expression studies under these conditions
Honey's ability to counter bacterial infections arises from both bactericidal compounds and QS inhibition
No full textThe ability of honey to kill bacterial pathogens in vitro and quickly clear even chronic or drug-resistant infections has been demonstrated by several studies. Most current research is focused on identifying the bactericidal compounds in honey, but the action of the compounds discovered is not sufficient to explain honey’s activity. By diluting honey to sub-inhibitory levels, we were able to study its impact on bacterial behavior, and discovered that honey inhibits bacterial quorum sensing (QS). Experiments to characterize and quantify honey’s effect on the QS networks of Pseudomonas aeruginosa revealed that low concentrations of honey inhibited the expression of MvfR, las and rhl regulons, including the associated virulence factors. This research also establishes that inhibition of quorum sensing is associated with honey’s sugar content. Therefore, honey combats infections by two independent mechanisms acting in tandem: bactericidal components, which actively kill cells and disruption of QS, which weakens bacterial coordination and virulence
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