Joyce J. Fernandes

Professor

250 Pearson Hall  (513) 529-7211
joyce.fernandes@miamioh.edu

Biographical Information

My lab studies development of the adult motor system in Drosophila, where patterning occurs in the context of metamorphosis. Tissues such as the musculature are histolysed to make way for a new set of muscles, whereas in case of the nervous system, a significant restructuring occurs which includes neuronal death, neurogenesis and remodeling of persistent neurons. These events collectively result in the generation of adult specific neural circuits, which are important for executing a new set of adult behaviors, both motor (flight, walking, flexion) and sensory (vision, smell). Remodeling of motor systems is particularly intriguing because the development of two distinct tissues has to be co‐ordinated: muscles and the nervous system. The remodeling of insect motor systems is under hormonal control and is also regulated by reciprocal interactions between neurons and muscle. Both these aspects are absent from the heavily studied embryonic stage and bear a resemblance to vertebrate events.

The three major projects currently underway in my lab are listed below. Undergraduate students participate in all projects and work in teams with graduate student mentors. Project #2 has involved students from the First Year Research Experience (FYRE) program. The first student graduated last summer and has entered an MD/Ph.D program.

(1) Neuroglial mechanisms that underlie restructuring of larval abdominal nerves. 5 pairs of larval abdominal nerves fuse to give rise to one terminal nerve trunk (TNT) in the adult. This fusion occurs at the A4‐A8 level. Nerves at the A1‐A3 level exit the CNS individually. Three glial layers surround each larval peripheral nerve in Drosophila. This project seeks to understand how glial remodeling may drive formation of the TNT. Our recent results indicate that the most external glial layer undergoes extensive proliferation just prior to the initiation of the TNT. Inducing cell death in this layer causes abnormalities in nerve organization. This work has particular relevance for developing invertebrate models of gliomas, and for an understanding of glial remodeling during nerve injury. This project formed the basis of a recent Master’s thesis (manuscript in preparation). Funded by NICHHD, R15 (2012-2015). Future directions include disruptions of the two inner glial layers, the sub-perineurial glia and the wrapping glia. The latter layer is completely removed during metamorphosis, presumably to allow for the retraction of motor neurons that are eliminated, in the context of a shift in motor control to the thorax.

(2) Fate of larval motor neurons during metamorphosis: implications for eclosion behavior. The neuronal identity gene, dHb9 is expressed in a subset of embryonically generated motor neurons. Some of these persist through metamorphosis to innervate adult muscle targets. We have determined the identities of these cells and created maps that connect the cell body positions and muscle targets at embryonic, larval and adult stages. A significant accomplishment of this project was to demonstrate that several of these persistent neurons are required for the adult specific behavior of eclosion. This was achieved by targeting diphtheria toxin to dHb9 expressing cells, which blocks translation. The behavior of eclosion was subsequently examined by video recordings. Some of this work was included in a 2011 Janelia Farm/HHMI conference on neuronal identity, and our images were used for the cover of the conference proceedings. One PhD student graduated this summer and 2 manuscripts papers based on this work will be forthcoming. Future Directions of this work is to identify components of the neural circuit that controls eclosion behavior.


(3) Role of signaling pathways during neuron-founder cell interactions. While it is known that the flight muscle motor neurons, which innervate the muscles of the adult Drosophila, have an important function in myoblast proliferation, the actual nature of the signal released by the neurons is unknown. Our studies test the hypothesis that the EGF signaling pathway regulates adult myogenesis. Genetic manipulations of the signaling pathways are being conducted at the receptor, ligand and intracellular signal level. The effects are examined in the adult muscle pattern, flight ability and developmental patterning events that occur during the pupal phase. Involvement of these pathways is being demonstrated in two phases, corresponding to two intended manuscripts. First, we have shown that targeting dominant negative receptors to founder cells disrupts myoblast proliferation, and subsequent fiber formation. The second phase of the project is underway to demonstrate that the innervating motor neurons are the source of the signals. Preliminary data show that blocking EGF ligand secretion by motor neurons can mimic disruption of signaling in the primary receiving cell, the founder/organizer cells. One Ph.D student will graduate in December 2014. Future directions of this work include a recent collaboration to identify key kinases that regulate the proliferation vs. differentiation switch, such that a balance is maintained to generate an appropriately sized myoblast pool, which in turn is important for regulation of target size.


Science Education

I am interested in understanding the pathways to enhance the success of students in first year biology courses, and underrepresented student groups in particular. As part of an NSF funded project, Undergraduate Research and Mentoring, we developed approaches for involving students in research labs as an approach to enhance retention. We also developed a supplemental course for students taking introductory biology, that emphasizes study skills. One graduate student defended her thesis on this topic in summer 2014.


Recent Publications

Hebbar S* and Fernandes, JJ. (2010). Glial remodeling during metamorphosis influences the stabilization of motor neuron branches in Drosophila. Developmental Biology 340:344-54.

Atreya KB*, Fernandes JJ. (2008) Founder cells regulate fiber number but not fiber formation during adult myogenesis in Drosophila. Developmental Biology. 321:123-40.

Conference Presentations

Kumar Vishal, Lindsay Grainger, Carli Calderone, Zachary Jump, and Joyce Fernandes. Motor neurons act through EGF ligands to regulate adult muscle patterning in Drosophila April 4-7, 2014. 54th Annual Drosophila Conference, Washington DC

Matt Siefert, Soumya Banerjee, Sayantan Mitra, Jack Wilber, Joyce Fernandes. Manipulating the remodeling of glial ensheathment of peripheral nerves during metamorphosis April 4-7, 2014. 54th Annual Drosophila Conference, Washington DC

Soumya Banerjee, Matt Siefert, Marc Toral, Joyce Fernandes. Cell Death influences re-organization of the larval nervous system during metamorphosis. April 4-7, 2014. 54th Annual Drosophila Conference, Washington DC

J. Sanjeevi*, JJ Fernandes, P.Callahan. A supplementary Course design improves student performance in Introductory Biology. Annual Meeting of the Society for Cell Biology (ASCB), New Orleans. Dec 14-18, 2013

J. Fernandes. Group Assignments for a 200-level Cell Biology Class that Integrates the Arts. Annual Meeting of the American Society for Cell Biology, San Francisco, December 15-19, 2012

Joyce Fernandes, Buffy Stoll, Kathy Jicinsky. Developing video scripts about undergraduate research- communicating science to the non-scientist. International Writing across the curriculum Conference, Savannah, June 7-9, 2012