Astrocyte-specific regulation of hMeCP2 expression in \u3ci\u3eDrosophila\u3c/i\u3e

Alterations in the expression of Methyl-CpG-binding protein 2 (MeCP2) either by mutations or gene duplication leads to a wide spectrum of neurodevelopmental disorders including Rett Syndrome and MeCP2 duplication disorder. Common features of Rett Syndrome (RTT), MeCP2 duplication disorder, and neuropsychiatric disorders indicate that even moderate changes in MeCP2 protein levels result in functional and structural cell abnormalities. In this study, we investigated two areas of MeCP2 pathophysiology using Drosophila as a model system: the effects of MeCP2 glial gain-of-function activity on circuits controlling sleep behavior, and the cell-type specific regulation of MeCP2 expression. In this study, we first examined the effects of elevated MeCP2 levels on microcircuits by expressing human MeCP2 (hMeCP2) in astrocytes and distinct subsets of amine neurons including dopamine and octopamine (OA) neurons. Depending on the celltype, hMeCP2 expression reduced sleep levels, altered daytime/ nighttime sleep patterns, and generated sleep maintenance deficits. Second, we identified a 498 base pair region of the MeCP2e2 isoform that is targeted for regulation in distinct subsets of astrocytes. Levels of the full-length hMeCP2e2 and mutant RTT R106W protein decreased in astrocytes in a temporally and spatially regulated manner. In contrast, expression of the deletion D166 hMeCP2 protein was not altered in the entire astrocyte population. qPCR experiments revealed a reduction in full-length hMeCP2e2 transcript levels suggesting transgenic hMeCP2 expression is regulated at the transcriptional level. Given the phenotypic complexities that are caused by alterations in MeCP2 levels, our results provide insight into distinct cellular mechanisms that control MeCP2 expression and link microcircuit abnormalities with defined behavioral deficits

Cell-specific regulation of MeCP2 expression in Drosophila Astrocytes

Sporadic mutations in methyl-CpG-binding protein 2 (MeCP2) cause Rett Syndrome a severe, neurodevelopmental disorder characterized by loss of motor and language skills, unusual stereotyped movements, autistic features, anxiety, and aggression. Duplication of the MeCP2 gene in males results in mental retardation, autistic behaviors, stereotyped hand movements and anxiety-related behaviors. The population prevalence of MeCP2 mutations is unknown. In addition, the mechanism by which mutations in the MeCP2 protein, MeCP2 protein levels, or whether neuronal or glial MeCP2 expression changes cause disease phenotypes is unclear. Astrocytes are a type of glia found throughout the brain. Astrocytes provide neurons with nutrients, guide their development, and maintain signaling conditions at synapses. Because interactions between glia and neurons are essential for many critical brain functions, we proposed that MeCP2 activity in astroctyes causes gene expression changes that alter the function of neighboring neurons. Using the UAS-Gal4 binary expression system we can express wildtype and mutant human MeCP2 (hMeCP2) protein in Drosophila astrocytes. We demonstrated that wildtype hMeCP2 causes sleep and aggression behavioral changes. Using MeCP2 antibody labeling, we can visualize MeCP2 expression in specific neurons and glial cells in the adult brain. High levels of MeCP2 expression were expected in astrocytes throughout the brain. Instead, expression was reduced and restricted to the subesophageal ganglion (SOG) region. The reduction was present in brains expressing the wildtype and mutant MeCP2R106W allele, but not the MeCP2Δ166 allele. The MeCP2Δ166 allele lacks the N-terminus and methyl-binding domain. We utilized qPCR on transcripts of whole brains expressing different hMeCP2 forms. Wildtype MeCP2 mRNA was present in brains exhibiting reduced expression indicating that reduced MeCP2 protein expression is not due to a transcription defect. A mechanism that regulates MeCP2 expression would be clinically relevant to MeCP2 disorders. My results may be extrapolated to human beings via conserved cellular mechanisms

Parent preferences and school segregation

Thesis: M.C.P., Massachusetts Institute of Technology, Department of Urban Studies and Planning, 2018.Cataloged from PDF version of thesis.Includes bibliographical references.Schools in New York City are deeply segregated by both race and class. The confluent forces of residential segregation and family school preference have led to increasingly segregated schools since the 1980s. The New York City Department of Education (DOE) has taken steps to desegregate schools since a 2014 report by the UCLA Civil Rights Project named New York State the state with the most segregated schools. Though the DOE is doing more to address segregation than most districts, their efforts are still cautious, careful not to alienate the high status families it sees as necessary for racial and economic integration. Additionally, the Department of Education is working towards school 'diversity' but their policy fails to adequately address the closely linked issue of ongoing education inequality. This project explores how parent choice impacts school segregation, provides recommendations for how the DOE should address parent choice in its diversity policy and develops a framework for moving beyond desegregation to build deep and stable integration in city schools.by Megan Hess-Homeier.M.C.P

Tracking Growth and Movement of the Slave River Log Jam

Large wood accumulations in rivers, called log jams, influence channel morphology and flow processes. My research investigates a large log jam on a side channel of the Slave River. The Slave River flows north through northern Alberta and the Northwest Territories where it empties into the Great Slave Lake. The Slave River is 3km wide, and has average peak summer flows of 6,000m3/s. The objective of my research is to map the growth of the log jam in the upstream direction as logs float downstream from their origin and get trapped in the log jam on the upstream end. I am using field data including tree cores, log lengths and diameters, vegetation data, and aerial imagery spanning from 1930-2015. Through aerial imagery analysis using ArcGIS, I have determined an average rate of upstream log jam growth of 2.4 meters per year. However, this growth does not happen at an average rate, but rater through yearly episodic influxes of wood. I have observed morphological changes in the channel meanders downstream of the log jam including the formation of new islands and channel banks from vegetation growing out of decaying log jam materials. I have collected tree cores from Spruce trees growing out of decaying log jam material at the downstream end of the log jam, as well as one from the upstream end of the log jam. The Spruce at the downstream end average 40 years old, while the Spruce at the upstream end is 3 years old. Since it takes roughly three years for vegetation to sprout in deposited logs, this indicates at least a 43 year timespan for the deposition of 103 meters of log jam between the downstream tree cores and the upstream tree core, confirming the rate of episodic log jam growth of roughly 2.4 meters per year

Cell-specific effects of MeCP2 on aggression using Drosophila as a model organism

Rett Syndrome is a severe neurodevelopmental disorder characterized by a loss or reduction in methyl-CpG-binding protein 2 (MeCP2) expression. Symptoms include loss of motor function, social problems, increased aggression, unusual stereotyped movements, and learning disability. When the MeCP2 gene is duplicated in males, MeCP2 duplication disorder results. The symptoms of MeCP2 duplication disorder include mental retardation, hypotonia, recurrent respiratory infections, epilepsy, limited or absent speech, progressive spasticity, and stereotyped movements of hands. MeCP2 is expressed in nearly all the cells of the nervous system. In this study, we are testing if human MeCP2 expression in octopamine neurons (invertebrate equivalent to norepinephrine) and specific glial cells causes changes in male aggressive behavior. We are using octopamine neurons since the behavioral changes associated with MeCP2 related disorders in humans suggest changes to neurons which affect behavior such as dopamine, serotonin, and norepinephrine neurons. To answer this question, we are using the model organism, Drosophila melanogaster, as male aggression in fruit flies is a robust, easily observed innate behavior. In order to test aggression, we place two males of the same genotype into a fight chamber where they compete for food at territory. After the fight is finished, the aggressive behaviors are quantified as latency to lunge (aggressive behavior), latency to encounter, and total number of lunges. Drosophila males expressing MeCP2 in octopamine neurons take nearly 1000 seconds longer to first encounter and first lunge, and lunge significantly less than control males. When expressing MeCP2 in astrocytes, latency to encounter and latency to aggression are also significantly increased indicating it takes longer for the experimental males to start fighting. Our results demonstrate that MeCP2 expressed in either astrocytes or octopamine neurons affect aggressive behaviors in Drosophila

Effects of cell-specific MeCP2 expression on aggression using Drosophila as a model system for human disease

Sporadic mutations in methyl-CpG-binding protein 2 (MeCP2) cause Rett Syndrome a severe, neurodevelopmental disorder characterized by loss of motor and language skills, unusual stereotyped movements, autistic features, anxiety, and an increase in aggression. Duplication of the MeCP2 gene in males results in multiple symptoms including mental retardation, autistic behaviors, stereotyped hand movements and anxiety-related behaviors. Although MeCP2 protein is found at high levels in essentially all cells in the nervous system, changes in neuronal or glial (support) cell MeCP2 expression may be responsible for the disease phenotypes. The heightened anxiety or aggression seen in people with MeCP2 disorders suggests neurons regulating moods such as serotonin, dopamine, or noradrenaline neurons may be involved. Using the UAS-Gal4 binary expression system we are able to express MeCP2 in both Drosophila octopamine neurons (the invertebrate equivalent of noradrenaline) and astrocytes (glial cells) separately. I am examining the effects of MeCP2 on the function of octopamine neurons in aggressive behavior. In Drosophila, aggression is a robust innate behavior comprised of reproducible, easily identifiable behavioral patterns. Two male flies of the same genotype are placed in a fight chamber, to compete for territory and food. After the fight, aggression is quantified by scoring the latency to aggression (time to first encounter), number of lunges (the predominant aggressive behavior), and percentage of trials that exhibit aggressive behavior. Because interactions between glia and neurons are essential for many critical brain functions, we propose that MeCP2 activity in astroctyes causes gene expression changes that change the function of neighboring neurons. I have observed increased latency to aggression and decreased lunges in flies expressing MeCP2 in OA neurons and in flies expressing MeCP2 in astrocytes. My results may be extrapolated to human beings via conserved cellular mechanisms

Astrocyte-specific regulation of hMeCP2 expression in Drosophila

Alterations in the expression of Methyl-CpG-binding protein 2 (MeCP2) either by mutations or gene duplication leads to a wide spectrum of neurodevelopmental disorders including Rett Syndrome and MeCP2 duplication disorder. Common features of Rett Syndrome (RTT), MeCP2 duplication disorder, and neuropsychiatric disorders indicate that even moderate changes in MeCP2 protein levels result in functional and structural cell abnormalities. In this study, we investigated two areas of MeCP2 pathophysiology using Drosophila as a model system: the effects of MeCP2 glial gain-of-function activity on circuits controlling sleep behavior, and the cell-type specific regulation of MeCP2 expression. In this study, we first examined the effects of elevated MeCP2 levels on microcircuits by expressing human MeCP2 (hMeCP2) in astrocytes and distinct subsets of amine neurons including dopamine and octopamine (OA) neurons. Depending on the cell-type, hMeCP2 expression reduced sleep levels, altered daytime/nighttime sleep patterns, and generated sleep maintenance deficits. Second, we identified a 498 base pair region of the MeCP2e2 isoform that is targeted for regulation in distinct subsets of astrocytes. Levels of the full-length hMeCP2e2 and mutant RTT R106W protein decreased in astrocytes in a temporally and spatially regulated manner. In contrast, expression of the deletion Δ166 hMeCP2 protein was not altered in the entire astrocyte population. qPCR experiments revealed a reduction in full-length hMeCP2e2 transcript levels suggesting transgenic hMeCP2 expression is regulated at the transcriptional level. Given the phenotypic complexities that are caused by alterations in MeCP2 levels, our results provide insight into distinct cellular mechanisms that control MeCP2 expression and link microcircuit abnormalities with defined behavioral deficits