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Search Results: 1 - 10 of 2279 matches for " dosage compensation "
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Problems of Birds Sex Determination  [PDF]
Antonina V. Trukhina, Aleksandr F. Smirnov
Natural Science (NS) , 2014, DOI: 10.4236/ns.2014.615111
Abstract: Sex determination system in birds is characterized by a homo-(Neognatae) and heteromorphic (Paleognatae) sex chromosomes. Heterogametic sex is female (ZZ/ZW system). DMRT1 gene is a gene regarded as a main male sex determining factor in this group of animals. The question remains about the participation of other factors (HEMOGEN, AMH etc.) in appearance of testis, and the role of steroid hormones in formation of ovaries. Complete sex inversion is not typical for species with genotypic sex determination (GSD), although the effect of estrogen metabolites is noted for birds. For birds epigenetic mechanisms of regulation (methylation of DNA and non-coding RNA) have been described for sex controlling genes such as CYP19A1 and DMRT1.
Sequence signatures involved in targeting the male-specific lethal complex to X-chromosomal genes in Drosophila melanogaster
Philge Philip, Fredrik Pettersson, Per Stenberg
BMC Genomics , 2012, DOI: 10.1186/1471-2164-13-97
Abstract: We have extensively examined X chromosome sequence variation within five types of gene features (promoters, 5' UTRs, coding sequences, introns, 3' UTRs) and intergenic sequences, and assessed its potential involvement in dosage compensation. Presented results show that: the X chromosome has a distinct sequence composition within its gene features; some of the detected variation correlates with genes targeted by the MSL-complex; the insulator protein BEAF-32 preferentially binds upstream of MSL-bound genes; BEAF-32 and MOF co-localizes in promoters; and that bound genes have a distinct sequence composition that shows a 3' bias within coding sequence.Although, many strongly bound genes are close to a high affinity site neither our promoter motif nor our coding sequence signatures show any correlation to HAS. Based on the results presented here, we believe that there are sequences in the promoters and coding sequences of targeted genes that have the potential to direct the secondary spreading of the MSL-complex to nearby genes.Drosophila melanogaster males are heterogametic (XY), while females are homogametic (XX). The Y chromosome has gradually lost genes and degenerated, resulting in an increasingly aneuploid condition in males and the evolution of systems that compensate for between-sex differences in doses of genes located on X chromosomes [1-4]. The dosage-compensation system equalizes X-linked gene expression between males and females, thus maintaining an appropriate balance between the expression of genes on X chromosome(s) and the autosomes [5,6].The amount of transcripts from the single X chromosome of male Drosophila individuals is boosted about two-fold relative to levels of each of the two in females, thereby roughly equalizing their overall X chromosome gene expression [7]. This dosage compensation is critical, and loss of required proteins leads to male-specific lethality [8,9]. These proteins include MSL-1 (male-specific lethal 1), MSL-2, MSL-3, MOF (mal
Demasculinization of the Anopheles gambiae X chromosome
Kalle Magnusson, Gareth J Lycett, Antonio M Mendes, Amy Lynd, Philippos-Aris Papathanos, Andrea Crisanti, Nikolai Windbichler
BMC Evolutionary Biology , 2012, DOI: 10.1186/1471-2148-12-69
Abstract: We performed a meta-analysis of sex-biased gene expression in Anopheles gambiae which provides evidence for a general underrepresentation of male-biased genes on the X-chromosome that increased in significance with the observed degree of sex-bias. A phylogenomic comparison between Drosophila melanogaster, Aedes aegypti and Culex quinquefasciatus also indicates that the Anopheles X chromosome strongly disfavours the evolutionary conservation of male-biased expression and that novel male-biased genes are more likely to arise on autosomes. Finally, we demonstrate experimentally that transgenes situated on the Anopheles gambiae X chromosome are transcriptionally silenced in the male germline.The data presented here support the hypothesis that the observed demasculinization of the Anopheles X chromosome is driven by X-chromosome inactivation in the male germline and by sexual antagonism. The demasculinization appears to be the consequence of a loss of male-biased expression, rather than a failure in the establishment or the extinction of male-biased genes.
Measurement of Peasants’ Satisfaction with the Compensation for Land Acquisition in the Chinese Mainland in the Last Thirty Years  [PDF]
Xinliang Wang
Chinese Studies (ChnStd) , 2013, DOI: 10.4236/chnstd.2013.21010
Based on theories and documents, initial quantization table of peasants land acquisition compensation satisfaction has been developed. It consists of compensation standard, compensation procedure, compensation mode, and compensation distribution. Through on-spot interviews and pre-tested questionnaires, the final scale is determined. After the questionnaire surveys and primary component analysis, ultimately, we conclude that compensation degree, compensation procedure, and compensation mode are the main dimensions of the peasants satisfaction with the compensation for land acquisition. This reliable operating tool makes up for the limits of situational specificity and shortcoming of recognition inconsistence of land acquisition compensation from the current bibliography, and promotes in-depth research and theorizations of land-acquisition compensation.
Checks and Balances on Executive Compensation  [PDF]
Mai Iskandar-Datta
Open Journal of Business and Management (OJBM) , 2014, DOI: 10.4236/ojbm.2014.21003
Abstract: Checks and Balances on Executive Compensation
Exploring the useful exposure range limits of three intraoral image receptors for various tube potential, tube current and exposure time settings  [PDF]
Elli Katsoni, Ioannis A. Tsalafoutas, Panagiotis Gritzalis, Evripides Stefanou, Evangelos Georgiou, Emmanouel Yakoumakis
Health (Health) , 2011, DOI: 10.4236/health.2011.35051
Abstract: Objectives: To determine the useful exposure range limits of three intraoral image receptors of different technology when exposed to different X-ray beam spectra, dose and dose rate levels. Study Design: A dental X-ray unit offering a wide range of tube potential, tube current and exposure time settings was used to expose a dental quality control phantom. The receptors that were used to capture the radiographic images of the phantom were: the Kodak Insight, the Kodak RVG-6000 and the Duerr Vistascan system. The images that were produced over a wide range of exposure factor settings were evaluated in terms of diagnostic quality by three experienced radiologists. Results: The number of images with acceptable diagnostic quality was in total 1257; 310 with Insight, 331 with RVG 6000 and 616 with Vistascan. At 60 kV, diagnosable images were produced with doses ranging from 0.44-1.56 mGy for the Insight film 0.44-2.82 mGy for the RVG 6000 and 0.22-4.93 mGy for the Vistascan system. At 70 kV, the respective ranges were 0.39-1.28 mGy for the Insight film 0.31-2.55 mGy for the RVG6000 and 0.30-3.46 mGy for the Vistascan system. Conclusions: The Vistascan exhibited the widest useful exposure range and required the least exposure to produce a diagnosable image at almost all tube potential settings. The RVG 6000 exhibited a slightly wider useful exposure range than the Insight film, with almost the same dose requirements especially in higher Kv settings.
Performance comparison between three intraoral image receptors of different technology at a variety of tube potential, tube current and exposure time settings using a stepwedge phantom  [PDF]
Elli Katsoni, Ioannis A. Tsalafoutas, Panagiotis Gritzalis, Evripidis Stefanou, Evangelos Georgiou, Emmanuel Yakoumakis
Health (Health) , 2011, DOI: 10.4236/health.2011.31011
Abstract: Purpose: To comparatively evaluate the per-formance of three intraoral image receptors of different technology when exposed to different X-ray beam spectra, dose and dose rate levels using a stepwedge phantom. Materials and methods: The intraoral radiographic receptors evaluated were: the Kodak Insight F speed class film, the Kodak RVG 6000, and the Duerr Vis-tascan Combi PSP system. A dental quality control phantom made of Plexiglas, containing an aluminium stepwedge with 12 steps and 7 holes drilled in each step was radiographed using a dental X-ray unit offering a wide range of tube potential, tube current and exposure time settings. The visibility of the holes in the images produced with each one of the three receptors was assessed by three independent observers. For each image the total image quality score (TS) was derived from the summation of the number of visible holes in each step. The numbers of perceptible holes in each experimental condition (TSs) were statistically analyzed through use of analysis of variance. Intraobserver and interobserver agree-ment was also measured. Results: Vistascan ex-hibited the most extended useful exposure range, followed by RVG 6000 and Insight. RVG 6000 exhibited the largest TS values in all tube potential settings except 70 kV where the Vistascan performed better. Insight performed better than Vistascan only at 60 and 63 kV. Vistascan performed better at 66 and 70 kV, Insight at 60 and 66 kV, whereas RVG performed equally well at all tube potential settings, except than at 52 and 70 kV. For the Insight the largest TS values were obtained with the smallest ESAK values whereas with the Vistascan the largest TS were obtained with ESAK values that where the largest observed. Conclusions: The performance of all receptors tested was greatly dependent on the exposure parameters and mainly on the kV settings. Overall, the RVG 6000 offered the best image quality at doses somewhere in between those required by the Insight and the Vistascan.
Withdrawal seizure associated with high dosage of aripiprazole and fluoxetine: a case report  [PDF]
Jian-An Su, Shih-Yong Chou, Ching-Shu Tsai, Tai-Hsin Hung
Open Journal of Psychiatry (OJPsych) , 2011, DOI: 10.4236/ojpsych.2011.12005
Abstract: Aripiprazole, a third-generation antipsychotic, has been considered to have a high safety profile and rare withdrawal symptoms. We reported the case of a schizophrenic patient with a significant obsession, who was treated with a high dosage of aripiprazole and fluoxetine. Generalized tonic-clonic seizure occurred two days after abruptly stopping these two medications. Gradually tapering aripiprazole is suggested in clinical practice, especially when using a high dosage.
Durational Therapeutic Dose of Fansidar: A Functional Index in Its Antidiabetic Properties  [PDF]
E. O. Jimmy
Journal of Biosciences and Medicines (JBM) , 2019, DOI: 10.4236/jbm.2019.71003
Abstract: Effects of fansidar in alloxan-induced diabetes were investigated in thirty (30) male and female albino rats for 28 days. The results showed a steady weekly decrease in blood glucose concentration in induced diabetic rats after fansidar treatment. In week 1, i.e. 7 days, there was significant difference in the blood glucose levels between the control and diabetic rats (P < 0.05) i.e. high glucose concentration, same in week II i.e. 14 days. However, in day 21 i.e. week III there was a significant reduction in the blood glucose concentration compared with control P < 0.05. The same results were obtained in week IV i.e. in 28 days treatment. The result has shown that fansidar has antidiabetic potentials on long term durational administration.
Shareholder Wealth Effects of CEO Succession  [PDF]
Kevin Banning
American Journal of Industrial and Business Management (AJIBM) , 2013, DOI: 10.4236/ajibm.2013.36067
Abstract: Companies often dismiss their chief executive officers (CEOs) when financial performance falters. This study examines why, despite the positive stock market effects, the replacement of the CEO often does little to change a company’s financial performance. Thanks to the agency arrangements in some companies, new CEOs are able to negotiate favorable contracts which benefit the CEO rather than the shareholders. In a sample of 140 publicly-traded firms, we found that compensation systems for new CEOs differed as a function of institutional ownership, with total executive compensation higher and compensation risk lower in firms with lower levels of institutional ownership. Financial performance was also weaker in firms with less institutional ownership.
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