3,134 publications from this institution
Abstract AFLP markers are becoming one of the most popular tools for genetic analysis in the fields of evolutionary genetics and ecology and conservation of genetic resources. The technique combines a high-information content and fidelity with the possibility of carrying out genomewide scans. However, a potential problem with this technique is the lack of homology of bands with the same electrophoretic mobility, what is known as fragment-size homoplasy. We carried out a theoretical analysis aimed at quantifying the impact of AFLP homoplasy on the estimation of within- and between-neutral population genetic diversity in a model of a structured finite population with migration among subpopulations. We also investigated the performance of a currently used method (DFDIST software) to detect selective loci from the comparison between genetic differentiation and heterozygosis of dominant molecular markers, as well as the impact of AFLP homoplasy on its effectiveness. The results indicate that the biases produced by homoplasy are: (1) an overestimation of the frequency of the allele determining the presence of the band, (2) an underestimation of the degree of differentiation between subpopulations, and (3) an overestimation or underestimation of the heterozygosis, depending on the allele frequency of the markers. The impact of homoplasy is quickly diminished by reducing the number of fragments analyzed per primer combination. However, substantial biases on the expected heterozygosity (up to 15–25%) may occur with ∼50–100 fragments per primer combination. The performance of the DFDIST software to detect selective loci from dominant markers is highly dependent on the number of selective loci in the genome and their average effects, the estimate of genetic differentiation chosen to be used in the analysis, and the critical bound probability used to detect outliers. Overall, the results indicate that the software should be used with caution. AFLP homoplasy can produce a reduction of up to 15% in the power to detect selective loci.
The protective effects of tea polysaccharides (TPS) and polyphenols (TPP) on skin were investigated. TPS1 (92% TPS), crude TPS2 (20% TPS), and TPP (98%) were tested. The abilities of TPS and TPP to protect the skin were assessed in four aspects: moisture absorption and retention, sunscreen, promoting the proliferation of fibroblast cells, and tyrosinase inhibitory effect. TPS and TPP absorbed and reserved moisture perfectly. TPS with higher purity had better moisture absorption and retention abilities. TPS1 hardly protected the skin from the sun's ultraviolet (UV) rays and had little promoting effect on fibroblasts proliferation. TPP, however, protected skin against UV rays and enhanced proliferation of fibroblast cells significantly. TPP had good tyrosinase inhibitory effects; TPS showed weaker tyrosinase inhibitory effects with the purity increased. The results indicated that TPP and TPS had complementary advantages and they should be appropriately combined to achieve higher performance when applied as active components of cosmetics.
The inhibitory effects of dietary polyphenols against α-amylase have attracted great interest among researchers. The aim of this review is to give an overview of the research reports on the structure-activity relationship of polyphenols inhibiting α-amylase. The molecular structures that influence the inhibition are the following: (1) The hydroxylation of flavonoids improved the inhibitory effect on α-amylase; (2) Presence of an unsaturated 2,3-bond in conjugation with a 4-carbonyl group has been associated with stronger inhibition; (3) The glycosylation of flavonoids decreased the inhibitory effect on α-amylase depending on the conjugation site and the class of sugar moiety; (4) The methylation and methoxylation of flavonoids obviously weakened the inhibitory effect; (5) The galloylated catechins have higher inhibition than nongalloylated catechins; the catechol-type catechins were stronger than the pyrogallol-type catechins; the inhibition activities of the catechins with 2,3-trans structure were higher than those of the catechins with 2,3-cis structure; (6) Cyanidin-3-glucoside showed higher inhibition against than cyanidin and cyanidin-3-galactoside and cyanidin-3,5-diglucoside had no inhibitory activity; (7) Ellagitannins with β-galloyl groups at glucose C-1 positions have higher inhibitory effect than the α-galloyl and nongalloyl compounds and the molecular weight of ellagitannins is not an important element.
Abstract Background Querying cancer genomes at single-cell resolution is expected to provide a powerful framework to understand in detail the dynamics of cancer evolution. However, given the high costs currently associated with single-cell sequencing, together with the inevitable technical noise arising from single-cell genome amplification, cost-effective strategies that maximize the quality of single-cell data are critically needed. Taking advantage of five published single-cell whole-genome and whole-exome cancer datasets, we studied the impact of sequencing depth and sampling effort towards single-cell variant detection, including structural and driver mutations, genotyping accuracy, clonal inference and phylogenetic reconstruction, using recent tools specifically designed for single-cell data. Results Altogether, our results suggest that, for relatively large sample sizes (25 or more cells), sequencing single tumor cells at depths >5x does not drastically improve somatic variant discovery, the characterization of clonal genotypes or the estimation of phylogenies from single tumor cells. Conclusions We demonstrate that sequencing many individual tumor cells at a modest depth represents an effective alternative to explore the mutational landscape and clonal evolutionary patterns of cancer genomes, without the excessively high costs associated with high-coverage genome sequencing.
This paper describes the application of experimental instruction based on the project-oriented work concept, focusing on trace copper determination in cow milks by electrothermal atomic absorption spectrometry as a representative case of trace analysis. The project is suitable for senior students in analytical chemistry/instrumental analysis and is intended to cover relevant issues in trace anlisis: sample pre-treatment (drying, grinding, sieving, mineralization), method development (optimization of thermal programs), calibration, validation, and application to real samples. Experimental work involved in each of those steps serves the purpose of showing error risks inherent in trace analysis, sample dissolution, calibration methods, and validation, and also introduces other important concepts, such as recovery, calibration, procedural blank, and spectral and nonspectral interferences.
Therapeutic strategies in resistant hypertension include adding another drug or changing drugs in search for a better synergic combination. Most patients, however, receive all of their drugs in a single morning dose. We have evaluated the impact on the circadian pattern of blood pressure on modifying the time of treatment without increasing the number of prescribed drugs. We studied 250 hypertensive patients who were receiving 3 antihypertensive drugs in a single morning dose. Patients were randomly assigned to 1 of 2 groups according to the modification in their treatment strategy: changing 1 of the drugs but keeping all 3 in the morning or the same approach but administering the new drug at bedtime. Blood pressure was measured for 48 hours before and after 12 weeks of treatment. There was no effect on ambulatory blood pressure when all of the drugs were taken on awakening. The baseline prevalence of nondipping (79%) was slightly increased after treatment (86%; P =0.131). The ambulatory blood pressure reduction was statistically significant (9.4/6.0 mm Hg for systolic/diastolic blood pressure; P <0.001) with 1 drug at bedtime. This reduction was larger in the nocturnal than in the diurnal mean of blood pressure. Thus, whereas only 16% of the patients in this group were dippers at baseline, 57% were dippers after therapy ( P <0.001). Results indicate that, in resistant hypertension, time of treatment may be more important for blood pressure control and for the proper modeling of the circadian blood pressure pattern than just changing the drug combination.
