Undergraduate Quantitative Biology Impact on Biology Preservice Teachers.

Quantitative biology is a rapidly advancing field in the biological sciences, particularly given the rise of large datasets and computer processing capabilities that have continually expanded over the past 50 years. Thus, the question arises, How should K-12 biology teachers incorporate quantitative biology skills into their biology curriculum? The teaching of quantitative biology has not been readily integrated into undergraduate biology curricula that impact preservice teachers. This has potential to cascade effects downward into the quality of learning about quantitative biology that can be expected in K-12 contexts. In this paper, we present the perspectives of a mathematics educator, a science educator, and two biologists, and discuss how we have personally incorporated aspects of quantitative reasoning into our courses. We identify some common challenges relevant to expanding implementation of quantitative reasoning in undergraduate biology courses in order to serve the needs of preservice teachers-both in their disciplinary courses and methods courses. For example, time constraints, math pedagogical content knowledge, and personal views about the relevance of quantitative principles in biology teaching and learning can impact how and to what extent they become implemented in curricula. In addition, although national standards at the K-12 level do address quantitative reasoning, the emphasis and guidance provided are sparser than for other content standards. We predict that both K-12 standards and guidelines for undergraduate education will only increase in their emphasis on quantitative skills as computation, "big data," and statistical modeling are increasingly becoming requisite skills for biologists.

Impaired in vivo binding of MeCP2 to chromatin in the absence of its DNA methyl-binding domain.

MeCP2 is a methyl-CpG-binding protein that is a main component of brain chromatin in vertebrates. In vitro studies have determined that in addition to its specific methyl-CpG-binding domain (MBD) MeCP2 also has several chromatin association domains. However, the specific interactions of MeCP2 with methylated or non-methylated chromatin regions and the structural characteristics of the resulting DNA associations in vivo remain poorly understood. We analysed the role of the MBD in MeCP2-chromatin associations in vivo using an MeCP2 mutant Rett syndrome mouse model (Mecp2(tm1.1Jae)) in which exon 3 deletion results in an N-terminal truncation of the protein, including most of the MBD. Our results show that in mutant mice, the truncated form of MeCP2 (ΔMeCP2) is expressed in different regions of the brain and liver, albeit at 50% of its wild-type (wt) counterpart. In contrast to the punctate nuclear distribution characteristic of wt MeCP2, ΔMeCP2 exhibits both diffuse nuclear localization and a substantial retention in the cytoplasm, suggesting a dysfunction of nuclear transport. In mutant brain tissue, neuronal nuclei are smaller, and ΔMeCP2 chromatin is digested faster by nucleases, producing a characteristic nuclease-resistant dinucleosome. Although a fraction of ΔMeCP2 is found associated with nucleosomes, its interaction with chromatin is transient and weak. Thus, our results unequivocally demonstrate that in vivo the MBD of MeCP2 together with its adjacent region in the N-terminal domain are critical for the proper interaction of the protein with chromatin, which cannot be replaced by any other of its protein domains.

Demonstration of vertebral and disc mechanical torsion in adolescent idiopathic scoliosis using three-dimensional MR imaging.

This study was designed to demonstrate and measure mechanical torsion in patients with adolescent idiopathic scoliosis using three-dimensional magnetic resonance (MR) imaging. Ten patients with adolescent idiopathic scoliosis were imaged with three-dimensional MR imaging, and the data post-processed through multiplanar reconstruction to produce images angled through individual endplates. Transverse rotation was measured at each endplate and these measurements used to calculate the amount of vertebral and disc mechanical torsion present. A test object was imaged in order to validate the measurement technique. Mechanical torsion was demonstrated within the vertebral bodies and discs of the imaged subjects, with vertebral mechanical torsion contributing on average 45% of the overall transverse plane deformity. It is concluded that deformation occurs in the transverse plane within the vertebrae and discs of subjects with idiopathic scoliosis, and a significant proportion of the rotation present in the scoliotic spine occurs as a result of plastic deformation within the vertebrae themselves. We believe that this is the first systematic demonstration of mechanical torsion in idiopathic scoliosis.