Summer Research 2016

Upcoming Summer Research 2016

We are excited to announce that 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!

 

Mitchell Lab Website

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.

Darcy 3

Kelley Lab Website

Darcy Kelley (MBL Research Award)
Columbia University
Department of Biological Sciences

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.

 Wiechmann Lab Website

Allan Wiechmann (MBL Research Award)
University of Oklahoma College of Medicine
Department of Cell Biology

Many biological processes exhibit circadian rhythms of activity which optimally synchronize cellular functions with the predictable daily solar oscillations. Ocular tissues display exceptionally robust circadian rhythms of activity to optimize specific processes which require synchronization with the light-dark cycle. The circadian signaling molecule of darkness, melatonin entrains many aspects of biological clocks via activation of specific G protein-coupled integral membrane receptors. We have been studying the distribution of melatonin receptor subtypes in ocular tissues of the aquatic frog Xenopus laevis, and our laboratory is especially focused on the role of melatonin receptor signaling in the retina of this animal model. A goal of our research is to discern the relative contributions of each melatonin receptor subtype in circadian functions of the diverse retinal cell subpopulations, especially the circadian sensitivity to light exposure. Working with scientists at the National Xenopus Resource at MBL, we will seek to develop novel transgenic Xenopus genome editing models in which melatonin receptor transgene expression is spatially and temporally deactivated, and subsequently analyze the impact of each cell-specific receptor knockout on retinal functions. Synchronization of retinal cellular activities with the solar cycle provides a deceptively subtle yet crucial balance between optimal visual sensitivity and defense against accrued harmful radiant energy that contributes to retinal degenerative disorders. The long-term goal of our research is to develop novel therapeutic strategies for the prevention and treatment of blinding degenerative diseases of the retina that are due in part to dysfunctional circadian signaling and photoentrainment.

 RHeald

Heald Lab Website

Rebecca Heald (MBL Research Award)
University of California, Berkeley
Department of Molecular & Cell Biology

The mitotic spindle is required for chromosome segregation during cell division of all eukaryotes. Our research takes advantage of Xenopus in vitro systems to investigate spindle assembly and size control. Cytoplasmic extracts prepared from eggs of the frog Xenopus laevis reconstitute mitotic chromosome condensation and spindle formation in vitro. We previously found that beads coated with chromatin formed on plasmid DNA can substitute for chromosomes in egg extracts and induce spindle assembly in the absence of centrosomes and kinetochores. Together with Thomas Surrey and Johanna Roostalu, our summer project is to define the minimum set of proteins that can substitute for chromatin in order to further simplify the system, with the long term goal of reconstituting the spindle from purified components. To study mechanisms of spindle size control, we utilize a smaller, related frog, Xenopus tropicalis, to identify factors that scale the spindle between the two species, and extracts prepared from fertilized eggs at different stages of embryogenesis to identify developmental scaling factors. We will take advantage of the genome editing expertise of the NXR to alter spindle scaling factors in vivo and assess the consequences. Altogether our studies aim to elucidate principles underlying spindle assembly and size control, as well as the molecular basis of variation that contributes to genomic instability and evolution.

surrey_thomas

Surrey Lab Website

Thomas Surrey (MBL Research Award)
The Francis Crick Institute, London 
Synthetic & Systems Biochemistry of the Microtubule Cytoskeleton Laboratory

The spatial organization and the dynamic properties of distinct architectures of the microtubule cytoskeleton are critical for cell viability and function. A central question is how different microtubule-based structures that span many micrometers are assembled from small nanometer-scale protein building blocks. Our research aims to decipher the molecular mechanisms of motor-microtubule self-organization by developing reconstituted in vitro systems consisting of purified proteins that replicate fundamental aspects of motor-dependent microtubule organization in cells. An important aim is to understand how mitotic spindles organize. For the summer project in Woods Hole together with Rebecca Heald and Johanna Roostalu, we will study the dynamic properties of reconstituted RCC1-bead spindles in Xenopus laevis egg extract, a setup previously pioneered by the Heald lab, to better understand the importance of microtubule dynamics for spindle stability and bead centering in this minimal spindle assembly system.

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.