Summer Research 2015

Upcoming Summer Research

We are excited to announce we will be hosting 5 different visiting scientists. It’s going to be a busy summer in the NXR!

But don’t forget about visiting year-round. If you have the projects, we have the frogs and the resources!

 

Gorbsky Lab Website

Gary Gorbsky (MBL Research Award)
Oklahoma Medical Research Foundation

My laboratory at the Oklahoma Medical Research Foundation studies cell cycle regulation during mitosis. We are interested in how chromosomes assemble, move and especially how the events of mitosis are timed. We study signaling of the mitotic spindle checkpoint and its regulation of the E3 ubiquitin ligase, the anaphase-promoting complex or cyclosome. We are particularly interested in how defects in the regulation of timing results in chromosome instability which can result in whole chromosome aneuploidy as well as gains, losses, and translocations of large chromosome segments. Chromosome instability is an important factor in tumor evolution, aging, and in human fertility and birth defects. Many of our studies have relied upon the use of a diploid Xenopus laevis cell line, called S3, which was developed in the laboratory of Doug Desimone at the University of Virginia. Our plans for the summer are to develop new diploid cell lines from both X. laevis and X. tropicalis embryos. We will then use CRISPR-Cas9 technology to generate mutant cell lines. Nuclear transfer from these cell lines to eggs in which the endogenous nucleus is inactivated will allow immediate generation of mutant tadpoles and frogs. One of our long term goals is to use this technology to study regeneration in Xenopus tadpoles.

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Furlow Lab Website

David Furlow (MBL Research Award)
UC Davis

Metamorphosis in frogs and toads, as well as in certain insects and crustaceans, represents the most dramatic effect of any hormone in nature. We are studying the molecular mechanisms underlying how thyroid hormone, which also critically regulates brain development and overall metabolism in humans, induces a wide variety of tissue changes that turn the purely aquatic tadpole into the adult frog.  These remarkable changes are mediated by specific thyroid hormone receptor subtypes that act as ligand regulated transcription factors. However, the precise role of each receptor subtype in tissue specific and developmental stage specific responses to the hormone are unclear. We are applying emerging powerful genetic approaches in Xenopus laevis and Xenopus tropicalis available at the Xenopus National Resource at MBL to reduce the expression of each receptor subtype, and test their importance in specific pathways during early development and thyroid hormone dependent metamorphosis. These studies will contribute to our understanding of tissue specific actions of hormones in a developmental context, using this highly evolutionarily conserved endocrine signaling system.Another important aspect of our work is determining the effect of environmental chemicals on proper thyroid hormone signaling in vertebrate development. We are further applying the available genetic technologies now available in the organism to produce tadpoles that express an easily measurable, hormone responsive reporter gene. This will allow us to detect proper temporal and spatial thyroid hormone action in vivo, in response to both endogenous hormones and potential environmental contaminants. Thus, our research is focused on answering basic questions regarding thyroid hormone’s action during development, with clear biomedical and environmental toxicology applications.

 

Brian Mitchell (MBL Research Award)
Northwestern University Feinberg School of Medicine
Department of Cell and Molecular Biology

The ability of ciliated epithelia to generate directed fluid flow is essential to numerous biological and physiological processes.  Our research focuses on the development of multi-ciliated cells using the embryonic skin of Xenopus.  One feature of this development is the requirement of these cells to generate approximately 150 centrioles that will become the basal bodies of their motile cilia.  This centriole biogenesis requires a poorly characterized structure called the deuterosome which is capable of nucleating  de novo centriole formation.  We have identified numerous proteins that localize to the deuterosome, yet how these cells have uncoupled centriole biogenesis from cell cycle progression and how they regulate proper centriole numbers remain unanswered questions.  We will utilize the genome editing expertise of the National Xenopus Resource Center (NXR) housed at the MBL to generate numerous mutants of deuterosome related genes.  Our goal is to perform a systematic characterization of this enigmatic structure to gain insight into mechanisms of centriole biogenesis.

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Kelley Website

Darcy Kelley (MBL Research Award)
Columbia University

Groups of neurons, interconnected in specific ways, form the neural circuits that underlie essential functions of the nervous system including breathing, reproductive behaviors, emotion and cognition. Our goal is to understand the function of neural circuits that produce different vocal patterns, determine how those patterns become different in the sexes, and gain insight into the relation between those circuits and their evolutionary precursors that shape respiration. The Xenopus brain produces fictive vocalizations that match patterns of nerve activity during actual courtship songs. Ex vivo vocal pattern generation allows us to activate specific circuits and determine how they function to produce behaviors. As for reproductive behaviors in mammals, courtship songs require the action of gonadal hormones: androgens and estrogens. We have considerable understanding of neuroendocrine mechanisms for the development of sex differences, but a limited understanding of exactly how steroid-sensitive cells influence the activity of distributed neural networks that generate social behavior. How specific populations of androgen- and estrogen-receptor expressing neurons within heterogeneous brain nuclei actually generate or shape sex behaviors is not known and is the focus of this research. Using the powerful gene editing techniques available at the National Xenopus Resource we will determine how neurons that are sensitive to the hormones required for vocal patterns participate in sex-specific neural circuits for behavior. To activate different groups of hormone responsive neurons in the isolated brain we will use optogenetics, an approach that allows the activation of specific neurons expressing a genetically inserted gene (channelrhodopsin) for an ion channel (essential for neural activity) by light. The steroid receptors are a well-conserved group of proteins that play important roles in human development and disease. The hindbrain circuitry that controls the function of the larynx – and its relation to circuitry that controls breathing – is readily studied in Xenopus. Insights from these studies should thus inform our understanding of vocal communication in many species and illuminate motor speech disorders and congenital central hypoventilation syndrome (Ondine’s Curse) in humans as well as neuroendocrine disorders.

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Erik Zornik (MBL Research Award)
Reed College

Neural rhythms are ubiquitous. They underlie many behaviors—including breathing, chewing, walking, vocalizing, and scratching—in addition to higher-order functions such as sensory processing, attention and memory. Our goal is to identify mechanisms that produce vocal rhythms in Xenopus laevis. Because the Xenopus vocal central pattern generator (CPG) can generate “fictive” vocalizations ex vivo (“brains calling in a dish”) we are able to measure neuronal activity during normal circuit function. Previously, we used whole-cell recordings to identify a functionally important neuron population in the vocal CPG, but other cell types have eluded the use of electrophysiological methods. This summer, we will develop functional imaging techniques to discover novel cell populations in the vocal CPG. Taking advantage of the ability to generate transgenic animals in the NXR, we will also begin to develop transgenic frogs that will ultimately provide a powerful tool for understanding the relations between multiple cell types and CPG activity. Outcomes of this research may identify fundamental network mechanisms that under the generation of coherent rhythms across a wide range of neural circuits.

The NXR will have space available for summer researchers as well as facilities to maintain frog lines during the summer and frogs for sale to use.

If interested in conducting research during the summer or during the rest of the year, please contact Xenopus@mbl.edu for more information.