Activation of Wnt signaling using lithium chloride: inquiry-based undergraduate laboratory exercises

Open-Ended Inquiry into Zebrafish Nerve Development Using Image Analysis

Open-ended laboratory projects increase student success and retention in the sciences. However, developing organismal-based research projects is a challenge for students with restricted laboratory access, such as those attending courses remotely. Here I describe the use of image analysis of zebrafish neural development for authentic research projects in an introductory biology laboratory course. Zebrafish are a vertebrate model that produce large numbers of externally and rapidly developing embryos. Because zebrafish larvae are transparent, fluorescent reporters marking nervous system structures can be imaged over time and analyzed by undergraduate scientists. In the pilot of this project, remote first-year college students independently developed biological questions based on an image collection comparing zebrafish mutants and wild-type siblings. Students created and mastered techniques to analyze position, organization, and other morphological features of developing neurons and glia in the images to directly test their biological questions. At the end of the course, students communicated their project results in journal article format and oral presentations. Students were able to hone skills in organismal observation and data collection while studying remotely, and they reported excitement at applying lecture-based knowledge to their own independent questions. This module can be adapted by other instructors for both students on- and off-campus to teach principles of neural development, data collection, data analysis, and scientific communication.

Amide-linked local anesthetics preferentially target leukemia stem cell through inhibition of Wnt/β-catenin

The anti-cancer activities of amide-linked local anesthetics have been demonstrated in various types of bulky/differentiated cancer cells. However, whether these anesthetics also affect biological functions of cancer stem cells is largely unknown. In this study, we systematically investigated the effects of three commonly used amide-linked local anesthetics (ropivacaine, lidocaine and bupivacaine) on leukemia stem cell (LSC) derived from two different leukemia diseases (acute myeloid leukemia, n = 8 and chronic myeloid leukemia, n = 8) as well as normal hematopoietic stem cell (HSC) derived from cord blood donors (n = 8) as comparison. We show that all three local anesthetics at clinically achievable concentrations significantly inhibit colony formation and serial replating of LSC in a dose-dependent manner, suggesting their inhibitory effects on LSC differentiation, proliferation and self-renewal. In addition, lidocaine and bupivacaine are more potent than ropivacaine. However, local anesthetics at the same concentrations do not affect LSC and HSC survival, demonstrating the differentiation and self-renewal as the primary effects of local anesthetics on LSC and HSC. Interestingly, local anesthetics display certain selectivity between LSC and HSC by having higher efficacy on LSC than HSC. Mechanism studies using both pharmacological and genetic approaches demonstrate that these local anesthetics target LSC via inhibiting Wnt/β-catenin but not Hedgehog or NF-ĸB signaling. Our work is the first to demonstrate the possible influence of amide-linked local anesthetics on cancer as well as normal stem cells via inhibiting Wnt/β-catenin signaling. Our findings contribute to the comprehensive understanding of potential implication of amide-linked local aesthesis in tumor biology.

Dissection and lateral mounting of zebrafish embryos: analysis of spinal cord development

The zebrafish spinal cord is an effective investigative model for nervous system research for several reasons. First, genetic, transgenic and gene knockdown approaches can be utilized to examine the molecular mechanisms underlying nervous system development. Second, large clutches of developmentally synchronized embryos provide large experimental sample sizes. Third, the optical clarity of the zebrafish embryo permits researchers to visualize progenitor, glial, and neuronal populations. Although zebrafish embryos are transparent, specimen thickness can impede effective microscopic visualization. One reason for this is the tandem development of the spinal cord and overlying somite tissue. Another reason is the large yolk ball, which is still present during periods of early neurogenesis. In this article, we demonstrate microdissection and removal of the yolk in fixed embryos, which allows microscopic visualization while preserving surrounding somite tissue. We also demonstrate semipermanent mounting of zebrafish embryos. This permits observation of neurodevelopment in the dorso-ventral and anterior-posterior axes, as it preserves the three-dimensionality of the tissue.