oalib

Publish in OALib Journal

ISSN: 2333-9721

APC: Only $99

Submit

Any time

2019 ( 171 )

2018 ( 241 )

2017 ( 242 )

2016 ( 352 )

Custom range...

Search Results: 1 - 10 of 144550 matches for " Marla B. Sokolowski "
All listed articles are free for downloading (OA Articles)
Page 1 /144550
Display every page Item
A Genetic Screen for Olfactory Habituation Mutations in Drosophila: Analysis of Novel Foraging Alleles and an Underlying Neural Circuit
Mark Eddison, Amsale T. Belay, Marla B. Sokolowski, Ulrike Heberlein
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0051684
Abstract: Habituation is a form of non-associative learning that enables animals to reduce their reaction to repeated harmless stimuli. When exposed to ethanol vapor, Drosophila show an olfactory-mediated startle response characterized by a transient increase in locomotor activity. Upon repeated exposures, this olfactory startle attenuates with the characteristics of habituation. Here we describe the results of a genetic screen to identify olfactory startle habituation (OSH) mutants. One mutation is a transcript specific allele of foraging (for) encoding a cGMP-dependent kinase. We show this allele of for reduces expression of a for-T1 isoform expressed in the head and functions normally to inhibit OSH. We localize for-T1 function to a limited set of neurons that include olfactory receptor neurons (ORNs) and the mushroom body (MB). Overexpression of for-T1 in ORNs inhibits OSH, an effect also seen upon synaptic silencing of the ORNs; for-T1 may therefore function in ORNs to decrease synaptic release upon repeated exposure to ethanol vapor. Overall, this work contributes to our understanding of the genes and neurons underlying olfactory habituation in Drosophila.
Natural Variation in the Thermotolerance of Neural Function and Behavior due to a cGMP-Dependent Protein Kinase
Ken Dawson-Scully, Gary A. B. Armstrong, Clement Kent, R. Meldrum Robertson, Marla B. Sokolowski
PLOS ONE , 2007, DOI: 10.1371/journal.pone.0000773
Abstract: Although it is acknowledged that genetic variation contributes to individual differences in thermotolerance, the specific genes and pathways involved and how they are modulated by the environment remain poorly understood. We link natural variation in the thermotolerance of neural function and behavior in Drosophila melanogaster to the foraging gene (for, which encodes a cGMP-dependent protein kinase (PKG)) as well as to its downstream target, protein phosphatase 2A (PP2A). Genetic and pharmacological manipulations revealed that reduced PKG (or PP2A) activity caused increased thermotolerance of synaptic transmission at the larval neuromuscular junction. Like synaptic transmission, feeding movements were preserved at higher temperatures in larvae with lower PKG levels. In a comparative assay, pharmacological manipulations altering thermotolerance in a central circuit of Locusta migratoria demonstrated conservation of this neuroprotective pathway. In this circuit, either the inhibition of PKG or PP2A induced robust thermotolerance of neural function. We suggest that PKG and therefore the polymorphism associated with the allelic variation in for may provide populations with natural variation in heat stress tolerance. for's function in behavior is conserved across most organisms, including ants, bees, nematodes, and mammals. PKG's role in thermotolerance may also apply to these and other species. Natural variation in thermotolerance arising from genes involved in the PKG pathway could impact the evolution of thermotolerance in natural populations.
The Drosophila foraging Gene Mediates Adult Plasticity and Gene–Environment Interactions in Behaviour, Metabolites, and Gene Expression in Response to Food Deprivation
Clement F. Kent,Tim Daskalchuk,Lisa Cook,Marla B. Sokolowski ,Ralph J. Greenspan
PLOS Genetics , 2009, DOI: 10.1371/journal.pgen.1000609
Abstract: Nutrition is known to interact with genotype in human metabolic syndromes, obesity, and diabetes, and also in Drosophila metabolism. Plasticity in metabolic responses, such as changes in body fat or blood sugar in response to changes in dietary alterations, may also be affected by genotype. Here we show that variants of the foraging (for) gene in Drosophila melanogaster affect the response to food deprivation in a large suite of adult phenotypes by measuring gene by environment interactions (GEI) in a suite of food-related traits. for affects body fat, carbohydrates, food-leaving behavior, metabolite, and gene expression levels in response to food deprivation. This results in broad patterns of metabolic, genomic, and behavioral gene by environment interactions (GEI), in part by interaction with the insulin signaling pathway. Our results show that a single gene that varies in nature can have far reaching effects on behavior and metabolism by acting through multiple other genes and pathways.
Social Environment Influences Performance in a Cognitive Task in Natural Variants of the Foraging Gene
Nancy R. Kohn, Christopher J. Reaume, Celine Moreno, James G. Burns, Marla B. Sokolowski, Frederic Mery
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0081272
Abstract: In Drosophila melanogaster, natural genetic variation in the foraging gene affects the foraging behaviour of larval and adult flies, larval reward learning, adult visual learning, and adult aversive training tasks. Sitters (fors) are more sedentary and aggregate within food patches whereas rovers (forR) have greater movement within and between food patches, suggesting that these natural variants are likely to experience different social environments. We hypothesized that social context would differentially influence rover and sitter behaviour in a cognitive task. We measured adult rover and sitter performance in a classical olfactory training test in groups and alone. All flies were reared in groups, but fly training and testing were done alone and in groups. Sitters trained and tested in a group had significantly higher learning performances compared to sitters trained and tested alone. Rovers performed similarly when trained and tested alone and in a group. In other words, rovers learning ability is independent of group training and testing. This suggests that sitters may be more sensitive to the social context than rovers. These differences in learning performance can be altered by pharmacological manipulations of PKG activity levels, the foraging (for) gene's gene product. Learning and memory is also affected by the type of social interaction (being in a group of the same strain or in a group of a different strain) in rovers, but not in sitters. These results suggest that for mediates social learning and memory in D. melanogaster.
Interaction between Oxytocin Genotypes and Early Experience Predicts Quality of Mothering and Postpartum Mood
Viara Mileva-Seitz, Meir Steiner, Leslie Atkinson, Michael J. Meaney, Robert Levitan, James L. Kennedy, Marla B. Sokolowski, Alison S. Fleming
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0061443
Abstract: Individual differences in maternal behavior are affected by both early life experiences and oxytocin, but little is known about genetic variation in oxytocin genes and its effects on mothering. We examined two polymorphisms in the oxytocin peptide gene OXT (rs2740210 and rs4813627) and one polymorphism in the oxytocin receptor gene OXTR (rs237885) in 187 Caucasian mothers at six months postpartum. For OXT, both rs2740210 and rs4813627 significantly associated with maternal vocalizing to the infant. These polymorphisms also interacted with the quality of care mothers experienced in early life, to predict variation in maternal instrumental care and postpartum depression. However, postpartum depression did not mediate the gene-environment effects of the OXT SNPs on instrumental care. In contrast, the OXTR SNP rs237885 did not associate with maternal behavior, but it did associate with pre-natal (but not post-natal) depression score. The findings illustrate the importance of variation in oxytocin genes, both alone and in interaction with early environment, as predictors of individual differences in human mothering. Furthermore, depression does not appear to have a causal role on the variation we report in instrumental care. This suggests that variation in instrumental care varies in association with a gene-early environment effect regardless of current depressive symptomatology. Finally, our findings highlight the importance of examining multiple dimensions of human maternal behavior in studies of genetic associations.
Epigenetic Regulation of Learning and Memory by Drosophila EHMT/G9a
Jamie M. Kramer,Korinna Kochinke,Merel A. W. Oortveld,Hendrik Marks,Daniela Kramer,Eiko K. de Jong,Zoltan Asztalos,J. Timothy Westwood,Hendrik G. Stunnenberg,Marla B. Sokolowski,Krystyna Keleman,Huiqing Zhou,Hans van Bokhoven,Annette Schenck
PLOS Biology , 2012, DOI: 10.1371/journal.pbio.1000569
Abstract: The epigenetic modification of chromatin structure and its effect on complex neuronal processes like learning and memory is an emerging field in neuroscience. However, little is known about the “writers” of the neuronal epigenome and how they lay down the basis for proper cognition. Here, we have dissected the neuronal function of the Drosophila euchromatin histone methyltransferase (EHMT), a member of a conserved protein family that methylates histone 3 at lysine 9 (H3K9). EHMT is widely expressed in the nervous system and other tissues, yet EHMT mutant flies are viable. Neurodevelopmental and behavioral analyses identified EHMT as a regulator of peripheral dendrite development, larval locomotor behavior, non-associative learning, and courtship memory. The requirement for EHMT in memory was mapped to 7B-Gal4 positive cells, which are, in adult brains, predominantly mushroom body neurons. Moreover, memory was restored by EHMT re-expression during adulthood, indicating that cognitive defects are reversible in EHMT mutants. To uncover the underlying molecular mechanisms, we generated genome-wide H3K9 dimethylation profiles by ChIP-seq. Loss of H3K9 dimethylation in EHMT mutants occurs at 5% of the euchromatic genome and is enriched at the 5′ and 3′ ends of distinct classes of genes that control neuronal and behavioral processes that are corrupted in EHMT mutants. Our study identifies Drosophila EHMT as a key regulator of cognition that orchestrates an epigenetic program featuring classic learning and memory genes. Our findings are relevant to the pathophysiological mechanisms underlying Kleefstra Syndrome, a severe form of intellectual disability caused by mutations in human EHMT1, and have potential therapeutic implications. Our work thus provides novel insights into the epigenetic control of cognition in health and disease.
Epigenetic Regulation of Learning and Memory by Drosophila EHMT/G9a
Jamie M. Kramer,Korinna Kochinke,Merel A. W. Oortveld,Hendrik Marks,Daniela Kramer,Eiko K. de Jong,Zoltan Asztalos,J. Timothy Westwood,Hendrik G. Stunnenberg,Marla B. Sokolowski,Krystyna Keleman,Huiqing Zhou,Hans van Bokhoven ,Annette Schenck
PLOS Biology , 2011, DOI: 10.1371/journal.pbio.1000569
Abstract: The epigenetic modification of chromatin structure and its effect on complex neuronal processes like learning and memory is an emerging field in neuroscience. However, little is known about the “writers” of the neuronal epigenome and how they lay down the basis for proper cognition. Here, we have dissected the neuronal function of the Drosophila euchromatin histone methyltransferase (EHMT), a member of a conserved protein family that methylates histone 3 at lysine 9 (H3K9). EHMT is widely expressed in the nervous system and other tissues, yet EHMT mutant flies are viable. Neurodevelopmental and behavioral analyses identified EHMT as a regulator of peripheral dendrite development, larval locomotor behavior, non-associative learning, and courtship memory. The requirement for EHMT in memory was mapped to 7B-Gal4 positive cells, which are, in adult brains, predominantly mushroom body neurons. Moreover, memory was restored by EHMT re-expression during adulthood, indicating that cognitive defects are reversible in EHMT mutants. To uncover the underlying molecular mechanisms, we generated genome-wide H3K9 dimethylation profiles by ChIP-seq. Loss of H3K9 dimethylation in EHMT mutants occurs at 5% of the euchromatic genome and is enriched at the 5′ and 3′ ends of distinct classes of genes that control neuronal and behavioral processes that are corrupted in EHMT mutants. Our study identifies Drosophila EHMT as a key regulator of cognition that orchestrates an epigenetic program featuring classic learning and memory genes. Our findings are relevant to the pathophysiological mechanisms underlying Kleefstra Syndrome, a severe form of intellectual disability caused by mutations in human EHMT1, and have potential therapeutic implications. Our work thus provides novel insights into the epigenetic control of cognition in health and disease.
Retinal waves are likely to instruct the formation of eye-specific retinogeniculate projections
Marla B Feller
Neural Development , 2009, DOI: 10.1186/1749-8104-4-24
Abstract: A fundamental feature of the developing neural circuits is their ability to change in the presence of altered sensory experience. This phenomenon has been studied particularly in the generation of cortical maps, where altering the pattern of sensory experience alters the spatial organization of sensory representations. The cellular mechanisms that underlie cortical plasticity fall into two categories: those that are based on physiological mechanisms, such as mechanisms by which altered firing patterns alter synaptic strength; and those that are based on morphological changes that are responsible for the physical rewiring of neural circuits. Physiological-based mechanisms that have been implicated in cortical plasticity include synaptic modifications such as long-term potentiation and long-term depression, which are often referred to as Hebbian-based learning rules. In addition, there are several non-Hebbian learning rules that have also been implicated, such as homeostatic plasticity and changes in intrinsic excitability of neurons (for extensive review of these mechanisms see [1] and references therein).There is growing evidence that neural activity plays a role much earlier in development, prior to the maturation of the sensory epithelium. In several developing circuits, including the cochlea [2], spinal cord [3,4], hippocampus and cortex [5,6], there are transient features that cause these circuits to spontaneously generate correlated activity [7,8]. However, the cellular mechanisms that translate these spontaneous activity patterns into mature neural circuits are not well understood. Indeed, application of the physiological-based mechanisms identified during later cortical plasticity may not readily apply in circuits where synapses are first forming and, therefore, are relatively immature [9]. Hebbian-based learning rules are particularly popular for early development because they instruct which synapses stay and which ones go in that strong co-activation of pre
Handling Observations with Low Interrater Agreement Values  [PDF]
Gensheng (Jason) Liu, Mohammad M. Amini, Emin Babakus, Marla B. Royne Stafford
Journal of Analytical Sciences, Methods and Instrumentation (JASMI) , 2011, DOI: 10.4236/jasmi.2011.12002
Abstract: Considerable research has been conducted on how interrater agreement (IRA) should be established before data can be aggregated from the individual rater level to the organization level in survey research. However, little is known about how researchers should treat the observations with low IRA values fail to meet the suggested standard. We seek to answer this question by investigating the impact of two factors (the relationship strength and the overall IRA level of a sample) on the IRA decision. Using both real data from a service industry and simulated data, we find that both factors affect whether a researcher should include or exclude observations with low IRA values. Based on the results, practical guidelines on when to use the entire sample are offered.
Low Temperature Properties of Selected Kramers Rare Earth Oxychlorides
Mat’a? S.,Mihalik M.,Klemke B.,Sokolowski A.
EPJ Web of Conferences , 2013, DOI: 10.1051/epjconf/20134011005
Abstract: In this work, we present low temperature magnetic and electronic properties measured on selected Kramers rare-earth oxychlorides REOCl, RE= Nd, Gd, Dy which adopt the PbFCl-type of structure. Prepared powder samples were characterized by means of standard structural, magnetic and electronic methods as X-ray di raction (300 K), heat capacity (0.3 K - 12 K) and susceptibility measurements (2 K - 300 K, at ambient pressure and hydrostatic pressures up to 0.68 ± 0.01 GPa). Our results indicate new transition to the ordered magnetic state for GdOCl and NdOCl compound at temperatures of 5 K and 1.5 K, respectively. We found small increase of magnetization saturation value of dysprosium oxychloride with an applied hydrostatic pressure, but no remarkable changes occur to antiferromagnetic transition temperature (TN ~ 9.2 K) when a moderate hydrostatic pressure (p ≤ 0.68 ± 0.01 GPa) was applied. Observed deviations from the Curie Weiss behavior below 26 K can be caused by the vicinity of the magnetic ordering temperature, or another magnetic e ects. The single crystal experiments which will solve this opened question are in progress.
Page 1 /144550
Display every page Item


Home
Copyright © 2008-2017 Open Access Library. All rights reserved.