3,134 publications from this institution
We report an assay of egg‐to‐adult viability in full‐sibling mutation accumulation (MA) lines derived from a completely homozygous population of Drosophila melanogaster and maintained for 210 generations. A simultaneous evaluation was also made of a large population derived from the same origin and maintained as a control for the same period. We also present computer simulations to explore the possible decline in viability of the control population due to mutation accumulation and the possible effect of selection within and between MA lines. For this purpose, we used two mutational models independent from the data analyzed and based on radically different assumptions. The first model implies a large number of mutations of small effect, whereas the second implies a much smaller number of mutations with much larger effects. The observed rate of decline in mean viability was very small but significant (0.077%). The rate of increase in among line variance (0.189 X 10∼3) was similar to those obtained previously in the same lines. The simulation results indicated that a model of many mutations of small effect is incompatible with the evolution of the mean viability of the control and MA lines over generations, the distribution of line means after 210 generations of mutation accumulation, and the pattern of line extinction over generations. Basically, this model predicted a large drop in viability, both in the control and particularly the MA lines, that is not observed empirically. It also predicted a rate of line extinction too low in the early generations and too high in the later ones. In contrast, the model based on few mutations of large effect was generally consistent with all the observations.
In molecular evolution, computer simulations have been commonly used to understand the interactions among evolutionary processes, for hypothesis testing, to evaluate and compare different analytical methods, or to estimate evolutionary parameters. This chapter describes simulation algorithms for the evolution of coding sequences under different evolutionary scenarios, potential uses of these simulations, and current simulation software. In particular, it discusses forward-time simulations, simulation of coalescent histories, and simulation of codon substitutions.
Chaetominine is a cytotoxic alkaloid that has been demonstrated to promote apoptotic cell death in human leukemia K562 cells. In the present study, chaetominine inhibited K562 (IC<sub>50</sub> 34 nM) and SW1116 (IC<sub>50</sub> 46 nM) cell growth. However, it remains unclear whether the inhibition of cell growth is associated with the cell cycle. To assess this potential relationship, the effect of chaetominine on the cell cycle of K562 and SW1116 cells was examined. Chaetominine treatment caused cell apoptosis and G<sub>1</sub>-phase arrest in SW1116 cells. Conversely, K562 cells underwent S-phase arrest according to flow cytometric analysis. The present study also aimed to elucidate the molecular mechanisms underpinning cell cycle regulation following the incubation of the associated cells with chaetominine. Western blot and reverse transcription-quantitative polymerase chain reaction analyses suggested that chaetominine treatment facilitated the expression of p53, p21, checkpoint kinase 2 (Chk2) and phosphorylated ataxia telangiectasia mutated (p-ATM) and caused a reduction in the mRNA levels of cyclin E and cyclin-dependent kinases (CDKs) 2 and 4. These results suggest that chaetominine may be involved in the regulation of p53/p21 and ATM and Rad3-related (ATM)/Chk2 signaling in SW1116 cells. Previous studies have demonstrated that these signaling pathways are responsible for G<sub>1</sub>-phase arrest. Results of the present study demonstrated that the expression of p-ATR and Chk1 were increased in K562 cells. Additionally, cdc25A levels were decreased, while protein and gene expression levels of cyclin A and CDK2 were repressed. These results elucidated the role of chaetominine in in the regulation of ATR/cdc25A/Chk1 expression in K562 cells. These proteins are thus important determinants in the initiation of S-phase arrest. These data support the hypothesis that chaetominine is a potential anti-cancer therapeutic agent that targets the cell cycle.
Water is a matter of vital importance for all developed countries due to the strong impact on human health and aquatic, wetlands and terrestrial environments. Therefore, the monitoring of water quality is of tremendous importance. The enormous advantages that Surface-enhanced Raman scattering (SERS) spectroscopy offers, such as fingerprint recognition, multiplex capabilities, high sensitivity, and selectivity or non-destructive testing, make this analytical tool very attractive for this purpose. This minireview aims to provide a summary of current approaches for the implementation of SERS sensors in monitoring organic and inorganic pollutants in water. In addition, we briefly highlight current challenges and provide an outlook for the application of SERS in environmental monitoring.
Abstract Vielfarbig fluoreszierende Container : Multifluoreszierende farbstoffmarkierte Zeolith‐L‐Kristalle mit lumineszierenden anisotropen Kernen und isotropen Hüllen wurden durch Beschichten mit Kieselgel erhalten. Dazu wurde der Aufbau von Polyelektrolytschichten mit einer Stöber‐Synthese kombiniert (siehe Schema, TEM‐Bild und fluoreszenzmikroskopische Aufnahmen). magnified image
Citrus is an important genus in the Rutaceae family, with high medicinal and economic value, and includes important crops such as lemons, orange, grapefruits, limes, etc. The Citrus species is rich sources of carbohydrates, vitamins, dietary fibre, and phytochemicals, mainly including limonoids, flavonoids, terpenes, and carotenoids. Citrus essential oils (EOs) consist of several biologically active compounds mainly belonging to the monoterpenes and sesquiterpenes classes. These compounds have demonstrated several health-promoting properties such as antimicrobial, antioxidant, anti-inflammatory, and anti-cancer properties. Citrus EOs are obtained mainly from peels, but also from leaves and flowers, and are widely used as flavouring ingredients in food, cosmetics, and pharmaceutical products. This review focused on the composition and biological properties of the EOs of Citrus medica L. and Citrus clementina Hort. Ex Tan and their main constituents, limonene, γ-terpinene, myrcene, linalool, and sabinene. The potential applications in the food industry have been also described. All the articles available in English or with an abstract in English were extracted from different databases such as PubMed, SciFinder, Google Scholar, Web of Science, Scopus, and Science Direct.
Data communication plays a very important role in the hardware in the loop simulation system. The system architecture of periscope semi-physical simulation system is proposed at first. Then the data communication method based on FINS between PLC and PC is introduced, the user's interaction of scene is achieved by PLC. The communication based on TCP between 2D chart console and scene simulation system is also introduced. The 6-DOF motion model and the scene simulation system is connected by TCP, and a DR method is introduced in solving the data amount problem. The test shows that the simulation system has no error package and no missing in a simulation circle. And can meet the requirements of training, also shows good performance in reliability and real-time.
Inbreeding depression for fitness traits is a key issue in evolutionary biology and conservation genetics. The magnitude of inbreeding depression, though, may critically depend on the efficiency of genetic purging, the elimination or recessive deleterious mutations by natural selection after they are exposed by inbreeding. However, the detection and quantification of genetic purging for nonlethal mutations is a rather difficult task. Here, we present two comprehensive sets of experiments with Drosophila aimed at detecting genetic purging in competitive conditions and quantifying its magnitude. We obtain, for the first time in competitive conditions, an estimate for the predictive parameter, the purging coefficient (d), that quantifies the magnitude of genetic purging, either against overall inbreeding depression (d ≈ 0.3), or against the component ascribed to nonlethal alleles (dNL ≈ 0.2). We find that competitive fitness declines at a high rate when inbreeding increases in the absence of purging. However, in moderate size populations under competitive conditions, inbreeding depression need not be too dramatic in the medium to short term, as the efficiency of purging is also very high. Furthermore, we find that purging occurred under competitive conditions also reduced the inbreeding depression that is expressed in the absence of competition.
