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In an earlier paper (Smith & Baldwin, 2015), we explained the basic concepts of the Hardy-Weinberg equilibrium (HWeq) principle needed for meaningful understanding and for good teaching, emphasizing distinctions that are sometimes ignored at the cost of coherent understanding, and identifying nine shortcomings of most available Hardy-Weinberg activities and problem sets. In the present paper, we provide a 5E lesson plan based on that analysis and designed to avoid the shortcomings identified, including providing original data and focusing on understanding and topics that are interesting and meaningful to young people. [ABSTRACT FROM AUTHOR]

Genomic analysis of H. salinarum indicated that the de novo pathway for aromatic amino acid (AroAA) biosynthesis does not follow the classical pathway but begins from non-classical precursors, as is the case for M. jannaschii. The first two steps in the pathway were predicted to be carried out by genes OE1472F and OE1475F, while the 3rd step follows the canonical pathway involving gene OE1477R. The functions of these genes and their products were tested by biochemical and genetic methods. In this study, we provide evidence that supports the role of proteins OE1472F and OE1475F catalyzing consecutive enzymatic reactions leading to the production of 3-dehydroquinate (DHQ), after which AroAA production proceeds via the canonical pathway starting with the formation of DHS (dehydroshikimate), catalyzed by the product of ORF OE1477R. Nutritional requirements and AroAA uptake studies of the mutants gave results that were consistent with the proposed roles of these ORFs in AroAA biosynthesis. DNA microarray data indicated that the 13 genes of the canonical pathway appear to be utilised for AroAA biosynthesis in H. salinarum, as they are differentially expressed when cells are grown in medium lacking AroAA. [ABSTRACT FROM AUTHOR]

In a companion article, I discussed recent developments in genetics and the inadequacies of eight common claims made by biology teachers, followed by suggested replacement language for those statements. In the present article, I address nine more claims, about such topics as whether or not most human characteristics are inherited as simple Mendelian traits (determined by one gene with a dominant and a recessive allele), problems with the Central Dogma of Biology, misunderstandings about the inheritance of traits such as eye color, the relative importance of genetics versus the environment, "genes FOR" language, and junk DNA. [ABSTRACT FROM AUTHOR]

Genetics is perhaps the most rapidly growing field of science today. Recent findings such as those of the Human Genome Project have led to new understandings of basic genetic phenomena and even to increased confusion about some basic genetic ideas, such as the nature of the gene. These developments directly influence how we should teach genetics. This article considers eight claims typically made by introductory biology teachers and considers how they differ from current understandings. [ABSTRACT FROM AUTHOR]

Background: A key stage for all microarray analyses is the extraction of feature-intensities from an image. If this step goes wrong, then subsequent preprocessing and processing stages will stand little chance of rectifying the matter. Illumina employ random construction of their BeadArrays, making feature-intensity extraction even more important for the Illumina platform than for other technologies. In this paper we show that using raw Illumina data it is possible to identify, control, and perhaps correct for a range of spatial-related phenomena that affect feature-intensity extraction. Results: We note that feature intensities can be unnaturally high when in the proximity of a number of phenomena relating either to the images themselves or to the layout of the beads on an array. Additionally we note that beads neighbour beads of the same type more often than one might expect, which may cause concern in some models of hybridization. We highlight issues in the identification of a bead's location, and in particular how this both affects and is affected by its intensity. Finally we show that beads can be wrongly identified in the image on either a local or array-wide scale, with obvious implications for data quality. Conclusions: The image processing issues identified will often pass unnoticed by an analysis of the standard data returned from an experiment. We detail some simple diagnostics that can be implemented to identify problems of this nature, and outline approaches to correcting for such problems. These approaches require access to the raw data from the arrays, not just the summarized data usually returned, making the acquisition of such raw data highly desirable. [ABSTRACT FROM AUTHOR]

College genetics faculty, students, and genetic counselors were asked to organize a group of classical genetics problems based on perceived similarities in problem solution and then to describe their organizational schemes. Like the experts in previous studies, only faculty subjects consistently organized problems around disciplinary principles. Unlike the faculty, the expert counselors resembled the students, placing greater emphasis on the problem knowns and unknowns. The counselors also emphasized solution techniques to be used. Only students emphasized the verbatim wording of the problem statement. Based on these findings, there can be more than one kind of expertise within a discipline, each with differing functional organizations of disciplinary knowledge. The hypothesis is presented that the scheme by which an expert organizes his or her knowledge of a discipline is structured to facilitate the manner in which that knowledge is typically applied by that individual. [ABSTRACT FROM AUTHOR]

Biological experiments involving genomics or other high-throughput assays typically yield a data matrix that can be explored and analyzed using the R programming language with packages from the Bioconductor project. Improvements in the throughput of these assays have resulted in an explosion of data even from routine experiments, which poses a challenge to the existing computational infrastructure for statistical data analysis. For example, single-cell RNA sequencing (scRNA-seq) experiments frequently generate large matrices containing expression values for each gene in each cell, requiring sparse or file-backed representations for memory-efficient manipulation in R. These alternative representations are not easily compatible with high-performance C++ code used for computationally intensive tasks in existing R/Bioconductor packages. Here, we describe a C++ interface named beachmat, which enables agnostic data access from various matrix representations. This allows package developers to write efficient C++ code that is interoperable with dense, sparse and file-backed matrices, amongst others. We evaluated the performance of beachmat for accessing data from each matrix representation using both simulated and real scRNA-seq data, and defined a clear memory/speed trade-off to motivate the choice of an appropriate representation. We also demonstrate how beachmat can be incorporated into the code of other packages to drive analyses of a very large scRNA-seq data set. [ABSTRACT FROM AUTHOR]

Cancer genome sequencing studies have identified numerous driver genes, but the relative timing of mutations in carcinogenesis remains unclear. The gradual progression from premalignant Barrett's esophagus to esophageal adenocarcinoma (EAC) provides an ideal model to study the ordering of somatic mutations. We identified recurrently mutated genes and assessed clonal structure using whole-genome sequencing and amplicon resequencing of 112 EACs. We next screened a cohort of 109 biopsies from 2 key transition points in the development of malignancy: benign metaplastic never-dysplastic Barrett's esophagus (NDBE; n = 66) and high-grade dysplasia (HGD; n = 43). Unexpectedly, the majority of recurrently mutated genes in EAC were also mutated in NDBE. Only TP53 and SMAD4 mutations occurred in a stage-specific manner, confined to HGD and EAC, respectively. Finally, we applied this knowledge to identify high-risk Barrett's esophagus in a new non-endoscopic test. In conclusion, mutations in EAC driver genes generally occur exceptionally early in disease development with profound implications for diagnostic and therapeutic strategies. [ABSTRACT FROM AUTHOR]