Epistasis not needed to explain low dN/dS

An important question in molecular evolution is whether an amino acid that occurs at a given position makes an independent contribution to fitness, or whether its effect depends on the state of other loci in the organism's genome, a phenomenon known as epistasis. In a recent letter to Nature, Breen et al. (2012) argued that epistasis must be "pervasive throughout protein evolution" because the observed ratio between the per-site rates of non-synonymous and synonymous substitutions (dN/dS) is much lower than would be expected in the absence of epistasis. However, when calculating the expected dN/dS ratio in the absence of epistasis, Breen et al. assumed that all amino acids observed in a protein alignment at any particular position have equal fitness. Here, we relax this unrealistic assumption and show that any dN/dS value can in principle be achieved at a site, without epistasis. Furthermore, for all nuclear and chloroplast genes in the Breen et al. dataset, we show that the observed dN/dS values and the observed patterns of amino acid diversity at each site are jointly consistent with a non-epistatic model of protein evolution.Comment: This manuscript is in response to "Epistasis as the primary factor in molecular evolution" by Breen et al. Nature 490, 535-538 (2012

Cryptic t(19;19)(p13.3;q13.2), involving the TCF3/E2A gene, detected and described by molecular cytogenetics in a patient with childhood B-cell progenitor acute lymphoblastic leukemia

Case report on a case of cryptic t(19;19)(p13.3;q13.2), involving the TCF3/E2A gene, detected and described by molecular cytogenetics in a patient with childhood B-cell progenitor acute lymphoblastic leukemia

Patient Experience and Virtual Reality: The Use of an MRI Exam Simulator

Magnetic resonance (MR) imaging is a safe diagnostic method of high accuracy detection and characterization of various pathological conditions. However, due to the very closed aspect of the apparatus, the high sound amplitude emitted and the need to remain motionless for a significant time, some patients experience discomfort and high levels of anxiety, compromising time and image quality management that can impair the clinical outcome of the patient or even give up the performance of this procedure. Therefore, this study aimed to validate, with patients, the use of Virtual Reality (VR) as a humanized practice of exposure to magnetic resonance imaging, to reduce the discomfort often present in the procedure. For this purpose, we used a cross-sectional method of quantitative-qualitative approach, incorporating purposeful sampling and semi-structured interviews of evaluative nature with 303 patients from two health institutions located in the state of Alagoas, Brazil, in which patients immersed in VR before the examination. As a result, exposure to VR led 98.9% of patients to feel more prepared and confident to perform the examination. There was no significant correlation between age, previous contact with technology and gender with the effectiveness of the intervention. However, there was a significant correlation between the form of approach, the quality of information and the level of feeling of relaxation of the patient. Thus, these results highlight the positive impact of VR on the patient\u27s experience in performing the MRI examination and the variety of audiences that can enjoy the benefits that this technology provides