Redesign your in-person course for online: Creating connections and promoting engagement for better learning.

This spring, instructors moved their courses online in an emergency fashion as campuses were closed due to the pandemic. As colleges prepare for the next academic year, there is a need to provide flexible instruction that is more intentional for quality online learning. We taught two undergraduate courses online for the first time this spring and surveyed our students' reactions to the course experiences. From our experiences and student feedback, we identified design elements and activities that were beneficial in promoting student engagement, sense of connectivity, and learning. We describe four qualities for a successful transition to online learning: (a) big questions and core concepts; (b) peer groups including reflective writing; (c) outreach to broader scientific community; and (d) instructor's social presence in the class. Our experience gives us confidence that courses can be redesigned for online without compromising rigor or essential learning goals.

Professional societies can play a vital role in career development.

Ph.D.s in the life sciences are seeking nonacademic careers in large numbers, and private sector employment is reaching an all-time high. In this climate, trainees are seeking mentors and opportunities to understand and explore different career paths. Scientific societies such as the Society for Developmental Biology play vital roles in professional development to support members at all stages of their careers and promote a range of employment opportunities. To this end, the Professional Development and Education Committee of the society offers full day workshops and sessions at regional and annual meetings that support constituents throughout their careers. For example, a new GetHIRED! workshop the day before the 2019 annual society meeting was developed as an interactive job skills workshop for postdoctoral fellows to gain insights into the job application process. The committee also aims to advocate for innovative approaches to teaching and science literacy in both the classroom and through outreach activities. The activities offered by scientific societies can reach a broader audience than individual institutions, and have lasting impacts in the quality of their members' careers by augmenting professional development opportunities.

From bench to board-side: Academic teaching careers.

Teaching positions provide a rewarding career pathway for Ph.D.s wishing to stay in academia outside of the research-focused position. The balance of teaching and research expectations on faculty can vary greatly depending on the type of institution. Faculty at primarily undergraduate institutions may be required to be researchactive and mentor undergraduates in the laboratory, while teaching faculty at a research-centered university may not have a research lab. In addition, faculty are expected to actively contribute to the shared governance of the institution, in the name of service. The career in teaching has become highly competitive and offers unexpected rewards and benefits. Considered here are the differences found among teaching positions to serve as a guide when considering teaching as a career option. We include our personal career narratives to illustrate the driving forces that led each of us to this challenging yet fulfilling academic path.

3D morphological analysis of spiral intestine morphogenesis in the little skate, Leucoraja erinacea.

BACKGROUND: The evolution of organ asymmetries is less explored than the field of organ morphology and coiling. The digestive tract of elasmobranchs provides a fascinating model for studying the evolution of morphological asymmetries. Unique to elasmobranchs and all basal fishes is the spiral intestine, which may represent an intermediate morphology in evolution from the straight gut of lamprey to the elongated coils of higher vertebrates. The short spiral allows for a large absorptive surface area that can fit into a restrictive abdominal space. RESULTS: Using histology and high resolution microCT, we provide the first 3D morphometric analysis of the spiral intestine during development in the little skate, Leucoraja erinacea. Spiral formation is initiated by asymmetric growth in the mesenchyme, causing a bulging fold that protrudes into the lumen of the gut. As development proceeds, the fold elongates and spirals into a right-handed helix. Spiraling progresses along the anterior-posterior axis and is likely the result of mechanical forces driven by the asymmetric growth of surrounding tissues. After initial asymmetric growth, radial constraints from within the gut tube create constrictive forces further propagating spiraling. CONCLUSION: We propose a model for potential biophysical mechanisms that direct the morphogenesis of the spiral intestine.

RNA in situ hybridization in whole mount embryos and cell histology adapted for marine elasmobranchs.

Marine elasmobranchs are valued animal models for biomedical and genomic studies as they are the most primitive vertebrates to have adaptive immunity and have unique mechanisms for osmoregulation. As the most primitive living jawed-vertebrates with paired appendages, elasmobranchs are an evolutionarily important model, especially for studies in evolution and development. Marine elasmobranchs have also been used to study aquatic toxicology and stress physiology in relationship to climate change. Thus, development and adaptation of methodologies is needed to facilitate and expand the use of these primitive vertebrates to multiple biological disciplines. Here I present the successful adaptation of RNA whole mount in situ hybridization and histological techniques to study gene expression and cell histology in elasmobranchs. Monitoring gene expression is a hallmark tool of developmental biologists, and is widely used to investigate developmental processes. RNA whole mount in situ hybridization allows for the visualization and localization of specific gene transcripts in tissues of the developing embryo. The expression pattern of a gene's message can provide insight into what developmental processes and cell fate decisions a gene may control. By comparing the expression pattern of a gene at different developmental stages, insight can be gained into how the role of a gene changes during development. While whole mount in situ's provides a means to localize gene expression to tissue, histological techniques allow for the identification of differentiated cell types and tissues. Histological stains have varied functions. General stains are used to highlight cell morphology, for example hematoxylin and eosin for general staining of nuclei and cytoplasm, respectively. Other stains can highlight specific cell types. For example, the alcian blue stain reported in this paper is a widely used cationic stain to identify mucosaccharides. Staining of the digestive tract with alcian blue can identify the distribution of goblet cells that produce mucosaccharides. Variations in mucosaccharide constituents on short peptides distinguish goblet cells by function within the digestive tract. By using RNA whole mount in situ's and histochemical methods concurrently, cell fate decisions can be linked to gene-specific expression. Although RNA in situ's and histochemistry are widely used by researchers, their adaptation and use in marine elasmobranchs have met limited and varied success. Here I present protocols developed for elasmobranchs and used on a regular basis in my laboratory. Although further modification of the RNA in situ's hybridization method may be needed to adapt to different species, the protocols described here provide a strong starting point for researchers wanting to adapt the use of marine elasmobranchs to their scientific inquiries.

Comparison of acid mucin goblet cell distribution and Hox13 expression patterns in the developing vertebrate digestive tract.

The digestive tract of vertebrates is a complex organ system required for the digestion of food and the absorption of nutrients. The colon evolved as a water absorption organ essential for vertebrates to survive on land. In contrast to land vertebrates, the Chondrichthyes (sharks, skates and rays) are nearly iso-osmotic with their ocean environment and do not reabsorb water from food waste. To understand the origin of the vertebrate colon, we examined the distribution of sulfated and sialyated mucus-producing cells in the little skate, Raja erinacea, as an indication of water absorption function in the chondrichthian digestive tract. The percentage of acid mucin producing goblet cells was analyzed in the spiral valve and hindgut of little skate and the small intestine and colon of mouse embryos. Levels of acid mucins in the hindgut of the little skate was comparable to that of the small intestines of terrestrial vertebrates, whereas the distal region of the spiral valve contained high levels of acid mucin producing cells similar to the colon of mouse and chick. The low numbers of acid mucins in the little skate hindgut confirms that a functional colon for water absorption is absent in the Chondrichthyes. Interestingly, the presence of high levels of acid mucins in the posterior spiral valve provides evidence for a possible primordial water-absorbing organ in the elasmobranchs. Hoxd13 patterns acid mucins in the colons of terrestrial vertebrates. Expression of Hoxd13 and Hoxa13 in R. erinacea suggests conserved roles for Hox genes in patterning the early hindgut.

Sox9 and Nkx2.5 determine the pyloric sphincter epithelium under the control of BMP signaling.

The organs of the digestive tract are specified by coordinated signaling between the endoderm and mesoderm during development. These epithelial-mesenchymal interactions lead to the organ-specific morphogenesis and differentiation of regions along the gut tube. In this paper, we show that in the chick, the SRY-related transcription factor Sox9 is a marker for the posterior gizzard. Viral misexpression of Sox9 in the gizzard mesoderm is sufficient to specify epithelium characteristic of the pyloric sphincter. Sox9 expression is normally limited to the region of the posterior gizzard under the regulation of BMP signaling from the adjacent midgut. Misexpression of an activated form of BMPR1b in the gizzard upregulates Sox9 expression, while the BMP antagonist noggin down-regulates Sox9 expression in the gizzard mesoderm. Previously, Nkx2.5 was identified as a marker for the mesoderm of the pyloric sphincter. As with Sox9, BMP signaling appears to regulate Nkx2.5 and its ability to determine the pyloric epithelium. Despite these similarities, our evidence suggests that Sox9 and Nkx2.5 are regulated independently by BMP signaling, and act coordinately to specify the pyloric sphincter.

Wnt signaling during development of the gastrointestinal tract.

Wnt signaling pathways have been demonstrated to play important roles in controlling tissue patterning and cell proliferation. In the gastrointestinal tract, mutations that lead to activation of the canonical Wnt pathway through beta-catenin result in familial and sporadic colon cancers. The downstream transcription factor Tcf4 is required to maintain the proliferative stem cell compartment in the crypts of the small intestine. Activation of TCF-dependent transcription is a good correlate to neoplastic transformation. Despite its association with cancer in the colon, little is known of the role for Wnt signaling during development and patterning of the gut tube. We conducted a comprehensive expression screen for Wnt signaling components during different stages of gut development in the chick. Conserved expression patterns of these genes indicate that they likely play essential roles in gut morphogenesis. Based on the expression profiles of putative components of each pathway, we are able to postulate specific roles for the various pathways during gut development. Predictions of roles for canonical signaling in the developing gizzard, duodenum, and large intestine in chick were tested by viral misexpression of dominant-negative (DN) forms of the downstream cofactors Tcf4 and Lef1. In the chick, Tcf4 is expressed in the posterior gizzard mesoderm. Misexpression of DN-Tcf4 in the splanchnic mesoderm resulted in the failure of the gizzard epithelium to form microvilli. Lef1 is expressed in the chick duodenum and large intestine mesoderm. Viral misexpression of DN-Lef1 resulted in diminished mesoderm and overproliferation of the large intestine endoderm, leading to stenosis of the lumen. The results from these misexpression studies in the chick, together with evidence from colorectal lesions, indicate that the canonical Wnt pathway plays critical roles in balancing cell proliferation versus cell differentiation during gut development. The expression profiles of the Wnt signaling components presented in this paper should prove valuable in deciphering additional roles of the Wnt pathways during patterning of the vertebrate gut tube.