Instructional Models for Course-Based Research Experience (CRE) Teaching.

The course-based research experience (CRE) with its documented educational benefits is increasingly being implemented in science, technology, engineering, and mathematics education. This article reports on a study that was done over a period of 3 years to explicate the instructional processes involved in teaching an undergraduate CRE. One hundred and two instructors from the established and large multi-institutional SEA-PHAGES program were surveyed for their understanding of the aims and practices of CRE teaching. This was followed by large-scale feedback sessions with the cohort of instructors at the annual SEA Faculty Meeting and subsequently with a small focus group of expert CRE instructors. Using a qualitative content analysis approach, the survey data were analyzed for the aims of inquiry instruction and pedagogical practices used to achieve these goals. The results characterize CRE inquiry teaching as involving three instructional models: 1) being a scientist and generating data; 2) teaching procedural knowledge; and 3) fostering project ownership. Each of these models is explicated and visualized in terms of the specific pedagogical practices and their relationships. The models present a complex picture of the ways in which CRE instruction is conducted on a daily basis and can inform instructors and institutions new to CRE teaching.

A Conserved Role of the Unconventional Myosin 1d in Laterality Determination.

Anatomical and functional asymmetries are widespread in the animal kingdom [1, 2]. In vertebrates, many visceral organs are asymmetrically placed [3]. In snails, shells and inner organs coil asymmetrically, and in Drosophila, genitalia and hindgut undergo a chiral rotation during development. The evolutionary origin of these asymmetries remains an open question [1]. Nodal signaling is widely used [4], and many, but not all, vertebrates use cilia for symmetry breaking [5]. In Drosophila, which lacks both cilia and Nodal, the unconventional myosin ID (myo1d) gene controls dextral rotation of chiral organs [6, 7]. Here, we studied the role of myo1d in left-right (LR) axis formation in Xenopus. Morpholino oligomer-mediated myo1d downregulation affected organ placement in >50% of morphant tadpoles. Induction of the left-asymmetric Nodal cascade was aberrant in >70% of cases. Expression of the flow-target gene dand5 was compromised, as was flow itself, due to shorter, fewer, and non-polarized cilia at the LR organizer. Additional phenotypes pinpointed Wnt/planar cell polarity signaling and suggested that myo1d, like in Drosophila [8], acted in the context of the planar cell polarity pathway. Indeed, convergent extension of gastrula explant cultures was inhibited in myo1d morphants, and the ATF2 reporter gene for non-canonical Wnt signaling was downregulated. Finally, genetic interference experiments demonstrated a functional interaction between the core planar cell polarity signaling gene vangl2 and myo1d in LR axis formation. Thus, our data identified myo1d as a common denominator of arthropod and chordate asymmetry, in agreement with a monophyletic origin of animal asymmetry.

Complete Genome Sequences of Cluster A Mycobacteriophages BobSwaget, Fred313, KADY, Lokk, MyraDee, Stagni, and StepMih.

Seven mycobacteriophages from distinct geographical locations were isolated, using Mycobacterium smegmatis mc2155 as the host, and then purified and sequenced. All of the genomes are related to cluster A mycobacteriophages, BobSwaget and Lokk in subcluster A2; Fred313, KADY, Stagni, and StepMih in subcluster A3; and MyraDee in subcluster A18, the first phage to be assigned to that subcluster.

Developmental expression of Xenopus myosin 1d and identification of a myo1d tail homology that overlaps TH1.

Xenopus laevis myosin 1d (XlMyo1d) is a member of the myosin I class, subclass 4. Members of this class are single headed, bind calmodulin light chains and have lipid binding domains in their tails. The rat myo1d homologue has been implicated in endosome vesicle recycling in epithelial cells. Mutations in the Drosophila myosin 1d homologue cause situs inversus in the abdomen. The XlMyo1d cDNA has been cloned and the derived amino acid sequence is 80% identical to the rat and human homologues. Sequence comparison revealed a novel isoform-specific tail homology embedded in the Tail Homology 1 (TH1) domain characteristic of myosin I isoforms. Western blot analysis using a polyclonal antibody raised against an isoform-specific peptide showed that the protein is present in eggs and levels increase at early neurula through tadpole stages. Whole mount in situ hybridization using a probe containing the 5'UTR (untranslated region) showed that XlMyo1d mRNA is expressed in neural tube, pre-somitic mesoderm, somites and all three segments of cranial neural crest cells during their migration. Sections of the in situ hybridizations revealed that during somitogenesis, XlMyo1d mRNA was localized to a stripe overlapping the nuclear region of somites during early tadpole stages.

The lift pool method for isolation of cDNA clones from lambda phage libraries

A PCR based strategy was developed to screen a Xenopus oocyte ëgt10 cDNA library. The PCR-based lift pool (LP) method follows the same two tiered strategy as conventional screening of phage libraries by filter hybridization. Two rounds of plating, one at high density to detect the clone, and one at low density to purify the clone to homogeneity, are performed. In the first round, lysates from high density plates, termed plate pools (PP), serve as template for PCR. In the second round, phage particles adhering to plaque lifts of low density plates are washed off nitrocellulose filters to create LPs, which are used as template for PCR. The integrity of the plaques on the low-density plates is preserved. Once a positive LP has been identified, plaques on the corresponding plate are screened individually by PCR. Using isoform specific primer pairs for Xenopus myosin 7a and myosin 1d, two lambda clones were isolated. Subsequent DNA sequence analysis confirmed their identities as myosin isoforms (GenBank accession numbers: DQ100353 and AF540952). This method offers a time saving, cost-effective alternative to other hierarchical pooling strategies for the repeated screening by PCR of an arrayed lambda phage library.