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Search Results: 1 - 10 of 201186 matches for " Michelle N. Arbeitman "
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Genomic and Functional Studies of Drosophila Sex Hierarchy Regulated Gene Expression in Adult Head and Nervous System Tissues
Thomas D Goldman,Michelle N Arbeitman
PLOS Genetics , 2007, DOI: 10.1371/journal.pgen.0030216
Abstract: The Drosophila sex determination hierarchy controls all aspects of somatic sexual differentiation, including sex-specific differences in adult morphology and behavior. To gain insight into the molecular-genetic specification of reproductive behaviors and physiology, we identified genes expressed in the adult head and central nervous system that are regulated downstream of sex-specific transcription factors encoded by doublesex (dsx) and fruitless (fru). We used a microarray approach and identified 54 genes regulated downstream of dsx. Furthermore, based on these expression studies we identified new modes of DSX-regulated gene expression. We also identified 90 and 26 genes regulated in the adult head and central nervous system tissues, respectively, downstream of the sex-specific transcription factors encoded by fru. In addition, we present molecular-genetic analyses of two genes identified in our studies, calphotin (cpn) and defective proboscis extension response (dpr), and begin to describe their functional roles in male behaviors. We show that dpr and dpr-expressing cells are required for the proper timing of male courtship behaviors.
Chromatin Regulation and Gene Centrality Are Essential for Controlling Fitness Pleiotropy in Yeast
Linqi Zhou,Xiaotu Ma,Michelle N. Arbeitman,Fengzhu Sun
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0008086
Abstract: There are a wide range of phenotypes that are due to loss-of-function or null mutations. Previously, the functions of gene products that distinguish essential from nonessential genes were characterized. However, the functions of products of non-essential genes that contribute to fitness remain minimally understood.
Evolution of Sex-Specific Traits through Changes in HOX-Dependent doublesex Expression
Kohtaro Tanaka,Olga Barmina,Laura E. Sanders,Michelle N. Arbeitman,Artyom Kopp
PLOS Biology , 2012, DOI: 10.1371/journal.pbio.1001131
Abstract: Almost every animal lineage is characterized by unique sex-specific traits, implying that such traits are gained and lost frequently in evolution. However, the genetic mechanisms responsible for these changes are not understood. In Drosophila, the activity of the sex determination pathway is restricted to sexually dimorphic tissues, suggesting that spatial regulation of this pathway may contribute to the evolution of sex-specific traits. We examine the regulation and function of doublesex (dsx), the main transcriptional effector of the sex determination pathway, in the development and evolution of Drosophila sex combs. Sex combs are a recent evolutionary innovation and show dramatic diversity in the relatively few Drosophila species that have them. We show that dsx expression in the presumptive sex comb region is activated by the HOX gene Sex combs reduced (Scr), and that the male isoform of dsx up-regulates Scr so that both genes become expressed at high levels in this region in males but not in females. Precise spatial regulation of dsx is essential for defining sex comb position and morphology. Comparative analysis of Scr and dsx expression reveals a tight correlation between sex comb morphology and the expression patterns of both genes. In species that primitively lack sex combs, no dsx expression is observed in the homologous region, suggesting that the origin and diversification of this structure were linked to the gain of a new dsx expression domain. Two other, distantly related fly lineages that independently evolved novel male-specific structures show evolutionary gains of dsx expression in the corresponding tissues, where dsx may also be controlled by Scr. These findings suggest that changes in the spatial regulation of sex-determining genes are a key mechanism that enables the evolution of new sex-specific traits, contributing to some of the most dramatic examples of phenotypic diversification in nature.
Somatic sex-specific transcriptome differences in Drosophila revealed by whole transcriptome sequencing
Peter L Chang, Joseph P Dunham, Sergey V Nuzhdin, Michelle N Arbeitman
BMC Genomics , 2011, DOI: 10.1186/1471-2164-12-364
Abstract: The sex hierarchy consists of a pre-mRNA splicing cascade that directs the production of sex-specific transcription factors that specify nearly all sexual dimorphism. We have used deep RNA sequencing to gain insight into how the Drosophila sex hierarchy generates somatic sex differences, by examining gene and transcript isoform expression differences between the sexes in adult head tissues.Here we find 1,381 genes that differ in overall expression levels and 1,370 isoform-specific transcripts that differ between males and females. Additionally, we find 512 genes not regulated downstream of transformer that are significantly more highly expressed in males than females. These 512 genes are enriched on the × chromosome and reside adjacent to dosage compensation complex entry sites, which taken together suggests that their residence on the × chromosome might be sufficient to confer male-biased expression. There are no transcription unit structural features, from a set of features, that are robustly significantly different in the genes with significant sex differences in the ratio of isoform-specific transcripts, as compared to random isoform-specific transcripts, suggesting that there is no single molecular mechanism that generates isoform-specific transcript differences between the sexes, even though the sex hierarchy is known to include three pre-mRNA splicing factors.We identify thousands of genes that show sex-specific differences in overall gene expression levels, and identify hundreds of additional genes that have differences in the abundance of isoform-specific transcripts. No transcription unit structural feature was robustly enriched in the sex-differentially expressed transcript isoforms. Additionally, we found that many genes with male-biased expression were enriched on the × chromosome and reside adjacent to dosage compensation entry sites, suggesting that differences in sex chromosome composition contributes to dimorphism in gene expression. Taken together,
Somatic, germline and sex hierarchy regulated gene expression during Drosophila metamorphosis
Matthew S Lebo, Laura E Sanders, Fengzhu Sun, Michelle N Arbeitman
BMC Genomics , 2009, DOI: 10.1186/1471-2164-10-80
Abstract: The temporal gene expression patterns during metamorphosis were determined for all predicted genes, in both somatic and germline tissues of males and females separately. Temporal changes in transcript abundance for genes of known functions were found to correlate with known developmental processes that occur during metamorphosis. We find that large numbers of genes are sex-differentially expressed in both male and female germline tissues, and relatively few are sex-differentially expressed in somatic tissues. The majority of genes with somatic, sex-differential expression were found to be expressed in a stage-specific manner, suggesting that they mediate discrete developmental events. The Sex-lethal paralog, CG3056, displays somatic, male-biased expression at several time points in metamorphosis. Gene expression downstream of the somatic, sex determination genes transformer and doublesex (dsx) was examined in two-day old pupae, which allowed for the identification of genes regulated as a consequence of the sex determination hierarchy. These include the homeotic gene abdominal A, which is more highly expressed in females as compared to males, as a consequence of dsx. For most genes regulated downstream of dsx during pupal development, the mode of regulation is distinct from that observed for the well-studied direct targets of DSX, Yolk protein 1 and 2.The data and analyses presented here provide a comprehensive assessment of gene expression during metamorphosis in each sex, in both somatic and germline tissues. Many of the genes that underlie critical developmental processes during metamorphosis, including sex-specific processes, have been identified. These results provide a framework for further functional studies on the regulation of sex-specific development.In Drosophila melanogaster, metamorphosis is the period in development when the male and female larval forms, which display little morphological sexual dimorphism, are transformed into the reproductive male and
Evolution of Sex-Specific Traits through Changes in HOX-Dependent doublesex Expression
Kohtaro Tanaka,Olga Barmina,Laura E. Sanders,Michelle N. Arbeitman,Artyom Kopp
PLOS Biology , 2011, DOI: 10.1371/journal.pbio.1001131
Abstract: Almost every animal lineage is characterized by unique sex-specific traits, implying that such traits are gained and lost frequently in evolution. However, the genetic mechanisms responsible for these changes are not understood. In Drosophila, the activity of the sex determination pathway is restricted to sexually dimorphic tissues, suggesting that spatial regulation of this pathway may contribute to the evolution of sex-specific traits. We examine the regulation and function of doublesex (dsx), the main transcriptional effector of the sex determination pathway, in the development and evolution of Drosophila sex combs. Sex combs are a recent evolutionary innovation and show dramatic diversity in the relatively few Drosophila species that have them. We show that dsx expression in the presumptive sex comb region is activated by the HOX gene Sex combs reduced (Scr), and that the male isoform of dsx up-regulates Scr so that both genes become expressed at high levels in this region in males but not in females. Precise spatial regulation of dsx is essential for defining sex comb position and morphology. Comparative analysis of Scr and dsx expression reveals a tight correlation between sex comb morphology and the expression patterns of both genes. In species that primitively lack sex combs, no dsx expression is observed in the homologous region, suggesting that the origin and diversification of this structure were linked to the gain of a new dsx expression domain. Two other, distantly related fly lineages that independently evolved novel male-specific structures show evolutionary gains of dsx expression in the corresponding tissues, where dsx may also be controlled by Scr. These findings suggest that changes in the spatial regulation of sex-determining genes are a key mechanism that enables the evolution of new sex-specific traits, contributing to some of the most dramatic examples of phenotypic diversification in nature.
A Versatile Method for Cell-Specific Profiling of Translated mRNAs in Drosophila
Amanda Thomas, Pei-Jung Lee, Justin E. Dalton, Krystle J. Nomie, Loredana Stoica, Mauro Costa-Mattioli, Peter Chang, Sergey Nuzhdin, Michelle N. Arbeitman, Herman A. Dierick
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0040276
Abstract: In Drosophila melanogaster few methods exist to perform rapid cell-type or tissue-specific expression profiling. A translating ribosome affinity purification (TRAP) method to profile actively translated mRNAs has been developed for use in a number of multicellular organisms although it has only been implemented to examine limited sets of cell- or tissue-types in these organisms. We have adapted the TRAP method for use in the versatile GAL4/UAS system of Drosophila allowing profiling of almost any tissue/cell-type with a single genetic cross. We created transgenic strains expressing a GFP-tagged ribosomal protein, RpL10A, under the control of the UAS promoter to perform cell-type specific translatome profiling. The GFP::RpL10A fusion protein incorporates efficiently into ribosomes and polysomes. Polysome affinity purification strongly enriches mRNAs from expected genes in the targeted tissues with sufficient sensitivity to analyze expression in small cell populations. This method can be used to determine the unique translatome profiles in different cell-types under varied physiological, pharmacological and pathological conditions.
Dynamic, mating-induced gene expression changes in female head and brain tissues of Drosophila melanogaster
Justin E Dalton, Tanvi S Kacheria, Simon RV Knott, Matthew S Lebo, Allison Nishitani, Laura E Sanders, Emma J Stirling, Ari Winbush, Michelle N Arbeitman
BMC Genomics , 2010, DOI: 10.1186/1471-2164-11-541
Abstract: We determined the temporal gene expression changes in female head tissues 0-2, 24, 48 and 72 hours after mating. Females from each time point had a unique post-mating gene expression response, with 72 hours post-mating having the largest number of genes with significant changes in expression. At most time points, genes expressed in the head fat body that encode products involved in metabolism showed a marked change in expression. Additional analysis of gene expression changes in dissected brain tissues 24 hours post-mating revealed changes in transcript abundance of many genes, notably, the reduced transcript abundance of genes that encode ion channels.Substantial changes occur in the regulation of many genes in female head tissues after mating, which might underlie aspects of the female post-mating response. These results provide new insights into the physiological and metabolic changes that accompany changes in female behaviors.Successful reproduction in Drosophila melanogaster requires the interplay of behavioral repertoires performed by males and females, which include male courtship, female receptivity, copulation, and female post-mating responses. Females are biochemically poised to respond to sperm, proteins, and other molecules transferred during copulation, which induce the post-mating response. This response, which lasts about a week, includes reduced receptivity to mating, metabolic changes, increased immunity and the physiological changes that accompany sperm storage, fertilization and egg-laying [reviewed in [1,2]].Accessory gland proteins (Acps), which are synthesized in the male accessory gland and transferred to females in the seminal fluid during copulation, act together to induce the post-mating response (reviewed in [1-3]). Of the Acps identified, sex peptide (SP) appears to be one of the primary triggers of the post-mating response. Injection of biochemically purified SP or ectopic expression of the gene that encodes SP in virgin females induces
Interpolating Socioeconomic Data for the Analysis of Deforestation: A Comparison of Methods  [PDF]
Michelle Farfán, Jean Fran?ois Mas, Laura Osorio
Journal of Geographic Information System (JGIS) , 2012, DOI: 10.4236/jgis.2012.44041
Abstract: This study compares local-level socioeconomic variables interpolated with three different methods: 1) Thiessen polygons, 2) Inverse distance weighting, and 3) Areas of influence based on cost of distance. The main objective was to determine the interpolation technique capable of generating the most efficient variable to explain the distribution of deforestation through two statistical approaches: generalized linear models and hierarchical partition. The study was conducted in two regions of western Mexico: Coyuquilla River watershed, and the Sierra de Manantlan Biosphere Reserve (SMBR). For SMBR it was found that the Thiessen polygons and areas of influence were the techniques that interpolated variables with greatest explanatory power for the deforestation process, in Coyuquilla it was inverse distance weighting. These differences are related to the distribution and the spatial correlation of the values of the variables.
Health Promotion in Cardiac Rehabilitation Patients through the Use of a High-Intensity Interval Training Protocol  [PDF]
Michelle Tinkham
World Journal of Cardiovascular Diseases (WJCD) , 2014, DOI: 10.4236/wjcd.2014.410059
Abstract: According to the American Heart Association’s (AHA) recent statistical update, over 2150 Americans die each day from cardiovascular disease (CVD), which equals approximately 1 death every 40 seconds; many of which were under the age of 65 years old [1]. In 2009, 386,324 people, 1 in 6 Americans, died as a result of coronary artery disease (CAD) alone [1]. They also estimate 150,000 people have “silent” heart attacks each year [1]. Even though the number of cardiovascular disease deaths has declined in the last 10 years, they still accounted for 32.3% of American deaths [1]. As a result, the AHA updated their 2020 goals to improve the nation’s cardiovascular health by 20% [1]. One of these methods is through the use of cardiac rehabilitation. Cardiac rehabilitation (CR) is a health promotion strategy to help return cardiac patients to their previous level of functioning, increase health, decrease comorbidities and promote education and lifestyle change. For select patients, another alternative exercise plan may exist to gain even better results. High intensity interval training (HIIT) has shown positive training results for athletes and many studies show that it may also be an effective exercise modality for many cardiac patients instead of the traditional circuit training method. This article will review current literature on the effects of HIIT on CR patients as well as a sample HIIT protocol for instituting this treatment with appropriate patients.
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