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Undergraduate research experiences are excellent opportunities to engage students in science alongside experienced scientists, but at large institutions, it is challenging to accommodate all students. To address and engage a larger number of students, we developed a modular laboratory course based on the course-based undergraduate research experiences model. This new course was integrated with the scientific aims of a research laboratory studying the cellular and molecular mechanisms underlying tissue regeneration in planarians. In this course, students were asked to identify genes with roles in planarian biology. Students analyzed and cloned an assigned gene, determined its expression pattern in situ and examined its function in regeneration. Additionally, we developed critical thinking and scientific communication skills by incorporating activities focused on critical concepts. Students obtained high quality primary data and were successful in completing and mastering the course learning outcomes. They benefitted by developing basic research skills, learning to perform, trouble-shooting experiments, reading and critically analyzing primary literature, and using the information to defend and explain their experimental results. Through this course, students also increased their confidence and ability to perform independent scientific research. The course was designed to make it accessible to the community to implement and adapt as appropriate in diverse institutions. © 2019 International Union of Biochemistry and Molecular Biology, 47(5):547-559, 2019.

Research indicates that insulin-like growth factor I (IGF-I) regulates sodium-potassium-adenosinetriphosphate pump activity in rat aortic vascular smooth muscle cells. IGF-I induced activity increases with concentration, time. It also shows a marked increase in activity if sodium-hydrogen exchange is prevented, but only for a short period of time. After this, it appears to operate using a pathway other than RNA transcription or translocation. It may also be responsible for other physiological responses including hypertension.

Germ cells are required for the successful propagation of sexually reproducing species. Understanding the mechanisms by which these cells are specified and how their totipotency is established and maintained has important biomedical and evolutionary implications. Freshwater planarians serve as fascinating models for studying these questions. They can regenerate germ cells from fragments of adult tissues that lack reproductive structures, suggesting that inductive signaling is involved in planarian germ cell specification. To study the development and regeneration of planarian germ cells, we have functionally characterized an ortholog of nanos, a gene required for germ cell development in diverse organisms, from Schmidtea mediterranea. In the hermaphroditic strain of this species, Smed-nanos mRNA is detected in developing, regenerating, and mature ovaries and testes. However, it is not detected in the vast majority of newly hatched planarians or in small tissue fragments that will ultimately regenerate germ cells, consistent with an epigenetic origin of germ cells. We show that Smed-nanos RNA interference (RNAi) results in failure to develop, regenerate, or maintain gonads in sexual planarians. Unexpectedly, Smed-nanos mRNA is also detected in presumptive testes primordia of asexual individuals that reproduce strictly by fission. These presumptive germ cells are lost after Smed-nanos RNAi, suggesting that asexual planarians specify germ cells, but their differentiation is blocked downstream of Smed-nanos function. Our results reveal a conserved function of nanos in germ cell development in planarians and suggest that these animals will serve as useful models for dissecting the molecular basis of epigenetic germ cell specification. [ABSTRACT FROM AUTHOR]

Planarians are an excellent model for investigating molecular mechanisms necessary for regenerating a functional nervous system. Numerous studies have led to the generation of extensive genomic resources, especially whole-animal single-cell RNA-seq resources. These have facilitated in silico predictions of neuronal subtypes, many of which have been anatomically mapped by in situ hybridization. However, our knowledge of the function of dozens of neuronal subtypes remains poorly understood. Previous investigations identified that polycystic kidney disease (pkd)-like genes in planarians are strongly expressed in sensory neurons and have roles in mechanosensation. Here, we examine the expression and function of all the pkd genes found in the Schmidtea mediterranea genome and map their expression in the asexual and hermaphroditic strains. Using custom behavioral assays, we test the function of pkd genes in response to mechanical stimulation and in food detection. Our work provides insight into the physiological function of sensory neuron populations and protocols for creating inexpensive automated setups for acquiring and analyzing mechanosensory stimulation in planarians.

Efforts to elucidate mechanisms of regeneration in the planarian Schmidtea mediterranea have included the application of immunocytochemical methods to detect specific molecules and label cells and tissues in situ. Here we describe methods for immunofluorescent labeling of whole mount planarians. We outline protocols for fixation and steps for processing animals prior to immunolabeling, incorporating commonly utilized reagents for mucus removal, pigment bleaching, tissue permeabilization, and antigen retrieval. Because processing steps can mask or degrade antigens, we also recommend protocol parameters that can be tested simultaneously to optimize sample preparation for novel antibodies.

Planarians have a long history in the fields of developmental and regenerative biology. These animals have also sparked interest in neuroscience due to their neuroanatomy, spectrum of simple behaviors, and especially, their almost unparalleled ability to generate new neurons after any type of injury. Research in adult planarians has revealed that neuronal subtypes homologous to those found in vertebrates are generated from stem cells throughout their lives. This feat is recapitulated after head amputation, wherein animals are capable of regenerating whole brains and regaining complete neural function. In this review, we summarize early studies on the anatomy and function of the planarian nervous system and discuss our present knowledge of the molecular mechanisms governing neurogenesis in planarians. Modern studies demonstrate that the transcriptional programs underlying neuronal specification are conserved in these remarkable organisms. Thus, planarians are outstanding models to investigate questions about how stem cells can replace neurons in vivo. WIREs Dev Biol 2017, 6:e266. doi: 10.1002/wdev.266 For further resources related to this article, please visit the WIREs website., (© 2017 Wiley Periodicals, Inc.)