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Laws KM, Natale E, Waddell EA, Shuda JR, Bashaw GJ. DrosoPHILA: A Partnership between Scientists and Teachers That Begins in the Lab and Continues into City Schools. eNeuro 2023; 10:ENEURO.0263-22.2022. [PMID: 36746638 PMCID: PMC9927510 DOI: 10.1523/eneuro.0263-22.2022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2022] [Revised: 12/09/2022] [Accepted: 12/13/2022] [Indexed: 02/08/2023] Open
Abstract
Here, we describe the development, structure, and effectiveness of an outreach program, DrosoPHILA, that leverages the tools of our fly neurodevelopmental research program at the University of Pennsylvania to reinforce the biology curriculum in local public schools. DrosoPHILA was developed and is sustained by a continued collaboration between members of the Bashaw lab, experienced outreach educators, and teachers in the School District of Philadelphia. Since the program's inception, we have collaborated with 18 teachers and over 2400 students. Student outcome data indicates significant positive attitude shifts around science identity and grade-appropriate knowledge gains.
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Affiliation(s)
- Kaitlin M Laws
- Department of Neuroscience, Perelman School of Medicine, University of Pennsylvania, Philadlephia, PA 19104
| | - Ent Natale
- Institute for Regenerative Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104
| | - Edward A Waddell
- Department of Neuroscience, Perelman School of Medicine, University of Pennsylvania, Philadlephia, PA 19104
| | - Jamie R Shuda
- Institute for Regenerative Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104
| | - Greg J Bashaw
- Department of Neuroscience, Perelman School of Medicine, University of Pennsylvania, Philadlephia, PA 19104
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Barrett M, Godfrey RK, Sterner EJ, Waddell EA. Impacts of development and adult sex on brain cell numbers in the Black Soldier Fly, Hermetia illucens L. (Diptera: Stratiomyidae). Arthropod Struct Dev 2022; 70:101174. [PMID: 35809527 DOI: 10.1016/j.asd.2022.101174] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/25/2022] [Revised: 04/28/2022] [Accepted: 05/06/2022] [Indexed: 06/15/2023]
Abstract
The Black Soldier Fly (Hermetia illucens, Diptera: Stratiomyidae) has been introduced across the globe, with numerous industry applications predicated on its tremendous growth during the larval stage. However, basic research on H. illucens biology (for example, studies of their central nervous system) are lacking. Despite their small brain volumes, insects are capable of complex behaviors; understanding how these behaviors are completed with such a small amount of neural tissue requires understanding processing power (e.g. number of cells) within the brain. Brain cell counts have been completed in only a few insect species (mostly Hymenoptera), and almost exclusively in adults. This limits the taxonomic breadth of comparative analyses, as well as any conclusions about how development and body size growth may impact brain cell populations. Here, we present the first images and cell counts of the H. illucens brain at four time points across development (early, mid, and late larval stages, and both male and female adults) using immunohistochemistry and isotropic fractionation. To assess sexual dimorphism in adults, we quantified the number of cells in the central brain vs. optic lobes of males and females separately. To assess if increases in body size during development might independently affect different regions of the CNS, we quantified the larval ventral nerve cord and central brain separately at all three stages. Together, these data provide the first description of the nervous system of a popular, farmed invertebrate and the first study of brain cell numbers using IF across developmental stages in any insect.
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Affiliation(s)
- Meghan Barrett
- Department of Biology, Drexel University, 3245 Chestnut St, Philadelphia, PA, 19104, USA.
| | - R Keating Godfrey
- Department of Neuroscience, University of Arizona, 1200 E. University Blvd, Tucson, AZ, 85721, USA
| | - Emily J Sterner
- Department of Biology, Drexel University, 3245 Chestnut St, Philadelphia, PA, 19104, USA
| | - Edward A Waddell
- Department of Biology, Holy Family University, 9801 Frankford Ave, Philadelphia, PA, 19114, USA
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Waddell EA, Ruiz-Whalen D, O’Reilly AM, Fried NT. Flying in the Face of Adversity: a Drosophila-Based Virtual CURE (Course-Based Undergraduate Research Experience) Provides a Semester-Long Authentic Research Opportunity to the Flipped Classroom. J Microbiol Biol Educ 2021; 22:e00173-21. [PMID: 34880963 PMCID: PMC8631315 DOI: 10.1128/jmbe.00173-21] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/02/2021] [Accepted: 10/26/2021] [Indexed: 06/13/2023]
Abstract
A call for the integration of research experiences into all biology curricula has been a major goal for educational reform efforts nationally. Course-based undergraduate research experiences (CUREs) have been the predominant method of accomplishing this, but their associated costs and complex design can limit their wide adoption. In 2020, the COVID-19 pandemic forced programs to identify unique ways to still provide authentic research experiences while students were virtual. We report here a complete guide for the successful implementation of a semester-long virtual CURE that uses Drosophila behavioral assays to explore the connection between pain and addiction with the use of an at-home "lab-in-a-box." Individual components were piloted across three semesters and launched as a 100-level introductory course with 19 students. We found that this course increased science identity and successfully improved key research competencies as per the Undergraduate Research Student Self-Assessment (URSSA) survey. This course is ideal for flipped classrooms ranging from introductory to upper-level biology/neuroscience courses and can be integrated directly into the lecture period without the need for building a new course. Given the low cost, recent comfort with virtual learning environments, and current proliferation of flipped classrooms following the 2020 pandemic, this curriculum could serve as an ideal project-based active-learning tool for equitably increasing access to authentic research experiences.
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Affiliation(s)
- Edward A. Waddell
- Department of Biology, Holy Family University, Philadelphia, Pennsylvania, USA
- Department of Neuroscience, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | | | | | - Nathan T. Fried
- Department of Biology, Rutgers University, Camden, New Jersey, USA
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Barrett M, Fiocca K, Waddell EA, McNair C, O'Donnell S, Marenda DR. Larval mannitol diets increase mortality, prolong development and decrease adult body sizes in fruit flies ( Drosophila melanogaster). Biol Open 2020; 8:bio.047084. [PMID: 31822472 PMCID: PMC6955208 DOI: 10.1242/bio.047084] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
The ability of polyols to disrupt holometabolous insect development has not been studied and identifying compounds in food that affect insect development can further our understanding of the pathways that connect growth rate, developmental timing and body size in insects. High-sugar diets prolong development and generate smaller adult body sizes in Drosophila melanogaster We tested for concentration-dependent effects on development when D. melanogaster larvae are fed mannitol, a polyalcohol sweetener. We also tested for amelioration of developmental effects if introduction to mannitol media is delayed past the third instar, as expected if there is a developmental sensitive-period for mannitol effects. Both male and female larvae had prolonged development and smaller adult body sizes when fed increasing concentrations of mannitol. Mannitol-induced increases in mortality were concentration dependent in 0 M to 0.8 M treatments with mortality effects beginning as early as 48 h post-hatching. Larval survival, pupariation and eclosion times were unaffected in 0.4 M mannitol treatments when larvae were first introduced to mannitol 72 h post-hatching (the beginning of the third instar); 72 h delay of 0.8 M mannitol introduction reduced the adverse mannitol effects. The developmental effects of a larval mannitol diet closely resemble those of high-sugar larval diets.This article has an associated First Person interview with the first author of the paper.
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Affiliation(s)
- Meghan Barrett
- Department of Biology, Drexel University, Philadelphia, PA, USA 19104
| | - Katherine Fiocca
- Department of Biology, Drexel University, Philadelphia, PA, USA 19104
| | - Edward A Waddell
- Department of Biology, Drexel University, Philadelphia, PA, USA 19104
| | - Cheyenne McNair
- Department of Biodiversity, Earth and Environmental Science, Drexel University, Philadelphia, PA, USA 19104
| | - Sean O'Donnell
- Department of Biology, Drexel University, Philadelphia, PA, USA 19104.,Department of Biodiversity, Earth and Environmental Science, Drexel University, Philadelphia, PA, USA 19104
| | - Daniel R Marenda
- Department of Biology, Drexel University, Philadelphia, PA, USA 19104 .,Department of Neurobiology and Anatomy, Drexel University College of Medicine, Philadelphia, PA, USA, 19104
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Waddell EA, Viveiros JM, Robinson EL, Sharoni MA, Latcheva NK, Marenda DR. Cover Image. Dev Neurobiol 2019. [DOI: 10.1002/dneu.22724] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Waddell EA, Viveiros JM, Robinson EL, Sharoni MA, Latcheva NK, Marenda DR. Extramacrochaetae promotes branch and bouton number via the sequestration of daughterless in the cytoplasm of neurons. Dev Neurobiol 2019; 79:805-818. [PMID: 31581354 DOI: 10.1002/dneu.22720] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2019] [Revised: 09/18/2019] [Accepted: 09/28/2019] [Indexed: 11/09/2022]
Abstract
The Class I basic helix-loop-helix (bHLH) proteins are highly conserved transcription factors that are ubiquitously expressed. A wealth of literature on Class I bHLH proteins has shown that these proteins must homodimerize or heterodimerize with tissue-specific HLH proteins in order to bind DNA at E-box consensus sequences to control tissue-specific transcription. Due to its ubiquitous expression, Class I bHLH proteins are also extensively regulated posttranslationally, mostly through dimerization. Previously, we reported that in addition to its role in promoting neurogenesis, the Class I bHLH protein daughterless also functions in mature neurons to restrict axon branching and synapse number. Here, we show that part of the molecular logic that specifies how daughterless functions in neurogenesis is also conserved in neurons. We show that the Type V HLH protein extramacrochaetae (Emc) binds to and represses daughterless function by sequestering daughterless to the cytoplasm. This work provides initial insights into the mechanisms underlying the function of daughterless and Emc in neurons while providing a novel understanding of how Emc functions to restrict daughterless activity within the cell.
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Affiliation(s)
- Edward A Waddell
- Department of Biology, Drexel University, Philadelphia, Pennsylvania
| | | | - Erin L Robinson
- Department of Biology, Drexel University, Philadelphia, Pennsylvania
| | - Michal A Sharoni
- Department of Biology, Drexel University, Philadelphia, Pennsylvania
| | - Nina K Latcheva
- Department of Biology, Drexel University, Philadelphia, Pennsylvania
| | - Daniel R Marenda
- Department of Biology, Drexel University, Philadelphia, Pennsylvania.,Department of Neurobiology and Anatomy, Drexel University College of Medicine, Philadelphia, Pennsylvania
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Fiocca K, Barrett M, Waddell EA, Viveiros J, McNair C, O’Donnell S, Marenda DR. Mannitol ingestion causes concentration-dependent, sex-biased mortality in adults of the fruit fly (Drosophila melanogaster). PLoS One 2019; 14:e0213760. [PMID: 31150400 PMCID: PMC6544200 DOI: 10.1371/journal.pone.0213760] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2019] [Accepted: 05/16/2019] [Indexed: 01/19/2023] Open
Abstract
Mannitol, a sugar alcohol used in commercial food products, has been previously shown to induce sex-biased mortality in female Drosophila melanogaster when ingested at a single concentration (1 M). We hypothesized that sex differences in energy needs, related to reproductive costs, contributed to the increased mortality we observed in females compared to males. To test this, we compared the longevity of actively mating and non-mating flies fed increasing concentrations of mannitol. We also asked whether mannitol-induced mortality was concentration-dependent for both males and females, and if mannitol's sex-biased effects were consistent across concentrations. Females and males both showed concentration-dependent increases in mortality, but female mortality was consistently higher at concentrations of 0.75 M and above. Additionally, fly longevity decreased further for both sexes when housed in mixed sex vials as compared to single sex vials. This suggests that the increased energetic demands of mating and reproduction for both sexes increased the ingestion of mannitol. Finally, larvae raised on mannitol produced expected adult sex ratios, suggesting that sex-biased mortality due to the ingestion of mannitol occurs only in adults. We conclude that sex and reproductive status differences in mannitol ingestion drive sex-biased differences in adult fly mortality.
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Affiliation(s)
- Katherine Fiocca
- Department of Biology Drexel University, Philadelphia, PA, United States of America
| | - Meghan Barrett
- Department of Biology Drexel University, Philadelphia, PA, United States of America
| | - Edward A. Waddell
- Department of Biology Drexel University, Philadelphia, PA, United States of America
| | - Jennifer Viveiros
- Department of Biology Drexel University, Philadelphia, PA, United States of America
| | - Cheyenne McNair
- Department of Biodiversity, Earth and Environmental Science, Drexel University, Philadelphia, PA, United States of America
| | - Sean O’Donnell
- Department of Biology Drexel University, Philadelphia, PA, United States of America
- Department of Biodiversity, Earth and Environmental Science, Drexel University, Philadelphia, PA, United States of America
| | - Daniel R. Marenda
- Department of Biology Drexel University, Philadelphia, PA, United States of America
- Department of Neurobiology and Anatomy, Drexel University College of Medicine, Philadelphia, PA
- * E-mail:
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Latcheva NK, Viveiros JM, Waddell EA, Nguyen PTT, Liebl FLW, Marenda DR. Epigenetic crosstalk: Pharmacological inhibition of HDACs can rescue defective synaptic morphology and neurotransmission phenotypes associated with loss of the chromatin reader Kismet. Mol Cell Neurosci 2017; 87:77-85. [PMID: 29249293 DOI: 10.1016/j.mcn.2017.11.007] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2017] [Revised: 10/20/2017] [Accepted: 11/06/2017] [Indexed: 12/25/2022] Open
Abstract
We are beginning to appreciate the complex mechanisms by which epigenetic proteins control chromatin dynamics to tightly regulate normal development. However, the interaction between these proteins, particularly in the context of neuronal function, remains poorly understood. Here, we demonstrate that the activity of histone deacetylases (HDACs) opposes that of a chromatin remodeling enzyme at the Drosophila neuromuscular junction (NMJ). Pharmacological inhibition of HDAC function reverses loss of function phenotypes associated with Kismet, a chromodomain helicase DNA-binding (CHD) protein. Inhibition of HDACs suppresses motor deficits, overgrowth of the NMJ, and defective neurotransmission associated with loss of Kismet. We hypothesize that Kismet and HDACs may converge on a similar set of target genes in the nervous system. Our results provide further understanding into the complex interactions between epigenetic protein function in vivo.
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Affiliation(s)
- Nina K Latcheva
- Department of Biology, Drexel University, Philadelphia, PA, United States; Program in Molecular and Cellular Biology and Genetics, Drexel University College of Medicine, Philadelphia, PA, United States
| | | | - Edward A Waddell
- Department of Biology, Drexel University, Philadelphia, PA, United States
| | - Phuong T T Nguyen
- Department of Biology, Drexel University, Philadelphia, PA, United States
| | - Faith L W Liebl
- Department of Biological Sciences, Southern Illinois University Edwardsville, Edwardsville, IL, United States
| | - Daniel R Marenda
- Department of Biology, Drexel University, Philadelphia, PA, United States; Program in Molecular and Cellular Biology and Genetics, Drexel University College of Medicine, Philadelphia, PA, United States; Department of Neurobiology and Anatomy, Drexel University College of Medicine, Philadelphia, PA, United States.
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Robinson EL, Waddell EA, D'Rozario M, Marenda DR. Novel role of bHLH proteins in synaptogenesis: Class I bHLH proteins TCF4 and Daughterless restrict synaptic branching and bouton formation via Neurexin repression in postmitotic neurons. FASEB J 2017. [DOI: 10.1096/fasebj.31.1_supplement.936.16] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
| | | | - Mitchell D'Rozario
- Department of BiologyDrexel UniversityPhiladelphiaPA
- Department of Developmental BiologyWashington University School of MedicineSt. LouisMO
| | - Daniel R. Marenda
- Department of BiologyDrexel UniversityPhiladelphiaPA
- Department of Neurobiology and AnatomyDrexel University College of MedicinePhiladelphiaPA
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D'Rozario M, Zhang T, Waddell EA, Zhang Y, Sahin C, Sharoni M, Hu T, Nayal M, Kutty K, Liebl F, Hu W, Marenda DR. Type I bHLH Proteins Daughterless and Tcf4 Restrict Neurite Branching and Synapse Formation by Repressing Neurexin in Postmitotic Neurons. Cell Rep 2016; 15:386-97. [PMID: 27050508 DOI: 10.1016/j.celrep.2016.03.034] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2015] [Revised: 01/22/2016] [Accepted: 03/09/2016] [Indexed: 11/17/2022] Open
Abstract
Proneural proteins of the class I/II basic-helix-loop-helix (bHLH) family are highly conserved transcription factors. Class I bHLH proteins are expressed in a broad number of tissues during development, whereas class II bHLH protein expression is more tissue restricted. Our understanding of the function of class I/II bHLH transcription factors in both invertebrate and vertebrate neurobiology is largely focused on their function as regulators of neurogenesis. Here, we show that the class I bHLH proteins Daughterless and Tcf4 are expressed in postmitotic neurons in Drosophila melanogaster and mice, respectively, where they function to restrict neurite branching and synapse formation. Our data indicate that Daughterless performs this function in part by restricting the expression of the cell adhesion molecule Neurexin. This suggests a role for these proteins outside of their established roles in neurogenesis.
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Affiliation(s)
| | - Ting Zhang
- Department of Neuroscience, Temple University School of Medicine, Philadelphia, PA 19140, USA
| | - Edward A Waddell
- Department of Biology, Drexel University, Philadelphia, PA 19104, USA
| | - Yonggang Zhang
- Department of Neuroscience, Temple University School of Medicine, Philadelphia, PA 19140, USA
| | - Cem Sahin
- Department of Electrical and Computer Engineering, Drexel University, Philadelphia, PA 19104, USA
| | - Michal Sharoni
- Department of Biology, Drexel University, Philadelphia, PA 19104, USA
| | - Tina Hu
- Department of Biology, Drexel University, Philadelphia, PA 19104, USA
| | - Mohammad Nayal
- Department of Biology, Drexel University, Philadelphia, PA 19104, USA
| | - Kaveesh Kutty
- Department of Biology, Drexel University, Philadelphia, PA 19104, USA
| | - Faith Liebl
- Department of Biological Sciences, Southern Illinois University Edwardsville, Edwardsville, IL 62026, USA
| | - Wenhui Hu
- Department of Neuroscience, Temple University School of Medicine, Philadelphia, PA 19140, USA.
| | - Daniel R Marenda
- Department of Biology, Drexel University, Philadelphia, PA 19104, USA; Department of Neurobiology and Anatomy, Drexel University College of Medicine, Philadelphia, PA 19104, USA.
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Leo L, Yu W, D'Rozario M, Waddell EA, Marenda DR, Baird MA, Davidson MW, Zhou B, Wu B, Baker L, Sharp DJ, Baas PW. Vertebrate Fidgetin Restrains Axonal Growth by Severing Labile Domains of Microtubules. Cell Rep 2015; 12:1723-30. [PMID: 26344772 PMCID: PMC4837332 DOI: 10.1016/j.celrep.2015.08.017] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2015] [Revised: 07/17/2015] [Accepted: 08/05/2015] [Indexed: 12/27/2022] Open
Abstract
Individual microtubules (MTs) in the axon consist of a stable domain that is highly acetylated and a labile domain that is not. Traditional MT-severing proteins preferentially cut the MT in the stable domain. In Drosophila, fidgetin behaves in this fashion, with targeted knockdown resulting in neurons with a higher fraction of acetylated (stable) MT mass in their axons. Conversely, in a fidgetin knockout mouse, the fraction of MT mass that is acetylated is lower than in the control animal. When fidgetin is depleted from cultured rodent neurons, there is a 62% increase in axonal MT mass, all of which is labile. Concomitantly, there are more minor processes and a longer axon. Together with experimental data showing that vertebrate fidgetin targets unacetylated tubulin, these results indicate that vertebrate fidgetin (unlike its fly ortholog) regulates neuronal development by tamping back the expansion of the labile domains of MTs.
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Affiliation(s)
- Lanfranco Leo
- Department of Neurobiology and Anatomy, Drexel University College of Medicine, Philadelphia, PA 19129, USA
| | - Wenqian Yu
- Department of Neurobiology and Anatomy, Drexel University College of Medicine, Philadelphia, PA 19129, USA
| | | | - Edward A Waddell
- Department of Biology, Drexel University, Philadelphia, PA 19104, USA
| | - Daniel R Marenda
- Department of Neurobiology and Anatomy, Drexel University College of Medicine, Philadelphia, PA 19129, USA; Department of Biology, Drexel University, Philadelphia, PA 19104, USA
| | - Michelle A Baird
- National High Magnetic Field Laboratory and Department of Biological Science, Florida State University, Tallahassee, FL 32310, USA
| | - Michael W Davidson
- National High Magnetic Field Laboratory and Department of Biological Science, Florida State University, Tallahassee, FL 32310, USA
| | - Bin Zhou
- Department of Genetics, Albert Einstein College of Medicine, Bronx, NY 10461, USA
| | - Bingro Wu
- Department of Genetics, Albert Einstein College of Medicine, Bronx, NY 10461, USA
| | - Lisa Baker
- Department of Physiology and Biophysics, Albert Einstein College of Medicine, Bronx, NY 10461, USA
| | - David J Sharp
- Department of Physiology and Biophysics, Albert Einstein College of Medicine, Bronx, NY 10461, USA
| | - Peter W Baas
- Department of Neurobiology and Anatomy, Drexel University College of Medicine, Philadelphia, PA 19129, USA.
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Abstract
Fabrication of microfluidic devices by excimer laser ablation under different atmospheres may provide variations in polymer microchannel surface characteristics. The surface chemistry and electroosmotic (EO) mobility of polymer microchannels laser ablated under different atmospheres were studied by X-ray photoelectron spectroscopy and current monitoring mobility measurements, respectively. The ablated surfaces of PMMA were very similar to the native material, regardless of ablation atmospheres due to the negligible absorption of 248-nm light by that polymer. The substrates studied that exhibit nonnegligible absorption at this energy, namely, poly(ethylene terephthalate glycol), poly(vinyl chloride), and poly(carbonate), showed significant changes in surface chemistry and EO mobility when the ablation atmospheres were varied. Ablation of these three polymer substrates under nitrogen or argon resulted in low EO mobilities with a loss of the well-defined chemical structures of the native surfaces, while ablation under oxygen yielded surfaces that retained native chemical structures and supported higher EO mobilities.
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Affiliation(s)
- D L Pugmire
- National Institute of Standards and Technology, Gaithersburg, Maryland 20899, USA.
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