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You searched for +publisher:"Cornell University" +contributor:("Goldberg, Michael Lewis"). Showing records 1 – 3 of 3 total matches.

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Cornell University

1. Krauchunas, Amber. Nature And Regulation Of Protein Phosphorylation Changes During Egg Activation In Drosophila Melanogaster.

Degree: PhD, Molecular and Cell Biology, 2012, Cornell University

Mature oocytes are held in a developmentally-quiescent, arrested state. For development to occur, these oocytes must transition to a new cellular state that can support the processes of embryogenesis. This transition is achieved by the events of egg activation. My studies focused on protein phosphorylation changes that take place during egg activation in Drosophila. Because there is little or no transcription at this time, egg activation is directed by maternal mRNAs and proteins regulated through posttranscriptional and post-translational mechanisms. Phosphorylation is an abundant post-translational modification with a wide array of regulatory effects. In addition, phosphorylation regulators such as CaMKII and calcineurin are required for egg activation in a variety of organisms. We hypothesize that simultaneously changing the phosphorylation states of a large number of proteins is a key contributor to the cellular changes that encompass the oocyte-to-embryo transition. I applied two different proteomic methods, IMAC and 2D-gel electrophoresis, to identify the proteins that change in phosphorylation state between mature oocytes and unfertilized, activated eggs. This led to the identification of 311 proteins that are phospho-modulated during egg activation. I used RNAi to knock down the genes that encode some of these proteins, testing a total of 71 genes for effects on female fertility. I identified multiple candidates for future study including, mrityu, which is required for progression through the early rounds of embryonic mitosis. I also used the phosphorylation changes of two proteins identified from the proteomics experiments, Spindly and Vap-33-1, as "molecular markers" to examine how the egg activation genes sarah, cortex, and prage relate to the phosphorylation changes that take place at egg activation. I showed that all three genes are upstream of Spindly dephosphorylation, but only sarah and cortex are upstream of Vap-33-1 phosphorylation. These data, along with previous findings in the lab, suggest that sarah and cortex act in a common pathway. Overall, my studies have contributed to our understanding of the roles of protein phosphorylation during egg activation. My results show that phosphorylation is an important area of study if we are to discover the proteins and pathways that regulate the oocyte-to-embryo transition. Advisors/Committee Members: Wolfner, Mariana Federica (chair), Goldberg, Michael Lewis (committee member), Clark, Andrew (committee member).

Subjects/Keywords: Egg activation; Phosphorylation; Proteomics

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

Krauchunas, A. (2012). Nature And Regulation Of Protein Phosphorylation Changes During Egg Activation In Drosophila Melanogaster. (Doctoral Dissertation). Cornell University. Retrieved from http://hdl.handle.net/1813/30979

Chicago Manual of Style (16th Edition):

Krauchunas, Amber. “Nature And Regulation Of Protein Phosphorylation Changes During Egg Activation In Drosophila Melanogaster.” 2012. Doctoral Dissertation, Cornell University. Accessed December 05, 2020. http://hdl.handle.net/1813/30979.

MLA Handbook (7th Edition):

Krauchunas, Amber. “Nature And Regulation Of Protein Phosphorylation Changes During Egg Activation In Drosophila Melanogaster.” 2012. Web. 05 Dec 2020.

Vancouver:

Krauchunas A. Nature And Regulation Of Protein Phosphorylation Changes During Egg Activation In Drosophila Melanogaster. [Internet] [Doctoral dissertation]. Cornell University; 2012. [cited 2020 Dec 05]. Available from: http://hdl.handle.net/1813/30979.

Council of Science Editors:

Krauchunas A. Nature And Regulation Of Protein Phosphorylation Changes During Egg Activation In Drosophila Melanogaster. [Doctoral Dissertation]. Cornell University; 2012. Available from: http://hdl.handle.net/1813/30979


Cornell University

2. Chen, Cheng. Pch2 Is A Hexameric Ring Atpase That Remodels The Meiotic Chromosome Axis Protein Hop1.

Degree: PhD, Genetics, 2014, Cornell University

In most organisms, the accurate segregation of chromosomes during the first meiotic division requires at least one crossover between each pair of homologous chromosomes. Crossovers form in meiosis from programmed double-strand breaks (DSBs) that are preferentially repaired using the homologous chromosome as a template. The PCH2 gene of budding yeast is required to establish proper meiotic chromosome structure, and to regulate meiotic DSB repair outcomes. PCH2 was also found to promote meiotic checkpoint functions, and to maintain ribosomal DNA stability during meiosis. The major focus of my thesis research has been to elucidate the molecular mechanism of Pch2 function. Pch2 contains an AAA (ATPases Associated with diverse cellular Activities) domain and is conserved in worms, fruit flies, and mammals. I performed the first detailed biochemical analysis of Pch2, and found that purified Pch2 oligomerizes into single hexameric rings in the presence of nucleotide. In addition, I showed that Pch2 directly binds to Hop1, a critical component of the synaptonemal complex that facilitates DSB repair to form crossovers. Interestingly, Hop1 binding by Pch2 induces large conformational changes in Pch2 hexamers, suggesting that Pch2 hexamers exert mechanical forces on Hop1. Importantly, I demonstrate that Pch2 subunits coordinate their ATP hydrolysis activities to displace Hop1 from large DNA substrates, providing an explanation for the altered localization of Hop1 in pch2[DELTA] mutants that was previously observed. Based on these results and other genetic and cell biological evidences I propose that Pch2 impacts multiple meiotic chromosome functions by directly regulating Hop1 localization. The second part of my thesis involves analyzing the pro-crossover Msh4-Msh5 complex, which facilitates interhomolog crossover formation by stabilizing recombination intermediates. To analyze Msh4-Msh5 function, I assayed spore viability and crossover levels for 57 msh4 and msh5 mutants and identified threshold mutants that showed wild-type spore viability but significantly decreased crossover levels. These findings suggest that a buffering mechanism exists to ensure the obligate crossover when overall crossover levels are reduced. Advisors/Committee Members: Alani, Eric (chair), Peters, Joseph E. (committee member), Goldberg, Michael Lewis (committee member).

Subjects/Keywords: meiosis; AAA proteins; hexameric ATPase

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

Chen, C. (2014). Pch2 Is A Hexameric Ring Atpase That Remodels The Meiotic Chromosome Axis Protein Hop1. (Doctoral Dissertation). Cornell University. Retrieved from http://hdl.handle.net/1813/37032

Chicago Manual of Style (16th Edition):

Chen, Cheng. “Pch2 Is A Hexameric Ring Atpase That Remodels The Meiotic Chromosome Axis Protein Hop1.” 2014. Doctoral Dissertation, Cornell University. Accessed December 05, 2020. http://hdl.handle.net/1813/37032.

MLA Handbook (7th Edition):

Chen, Cheng. “Pch2 Is A Hexameric Ring Atpase That Remodels The Meiotic Chromosome Axis Protein Hop1.” 2014. Web. 05 Dec 2020.

Vancouver:

Chen C. Pch2 Is A Hexameric Ring Atpase That Remodels The Meiotic Chromosome Axis Protein Hop1. [Internet] [Doctoral dissertation]. Cornell University; 2014. [cited 2020 Dec 05]. Available from: http://hdl.handle.net/1813/37032.

Council of Science Editors:

Chen C. Pch2 Is A Hexameric Ring Atpase That Remodels The Meiotic Chromosome Axis Protein Hop1. [Doctoral Dissertation]. Cornell University; 2014. Available from: http://hdl.handle.net/1813/37032


Cornell University

3. Sartain, Caroline. Rna Regulation During Gametogenesis And Triggers Of Egg Activation In Drosophila Melanogaster.

Degree: PhD, Genetics, 2013, Cornell University

One of the most critical transitory periods during development occurs when an oocyte prepares to undergo embryogenesis, in a process called "egg activation". In many organisms, the oocyte has been at rest in the ovary, stored in a dormant state for a period ranging from a number of days (as in flies) to several decades (as in humans). Upon egg activation, this dormant egg must suddenly undergo several major cellular and molecular changes that prepare it for embryogenesis, including restructuring of the vitelline membrane, completion of meiosis, and changes to mRNA and protein pools. Where most organisms require a fertilizing sperm to set off these events, fruitflies are unique in that egg activation occurs prior to requirement of fertilization. I have used Drosophila melanogaster as a model system to dissect apart some key events of egg activation that are driven solely by the maternal components of the oocyte. In most animals, the initial trigger from the sperm sparks a calcium wave that traverses through the oocyte, acting as a message to kick off previously silenced biochemical pathways. For many years, it was unknown whether calcium played a role in egg activation in Drosophila. I have discovered that although Drosophila oocytes do not require a fertilizing sperm, a calcium wave does occur during egg activation. I have characterized the dynamics of this calcium influx using live imaging of Drosophila oocytes undergoing in vitro egg activation. Furthermore, I found that the calcium flux is not dependent upon internal stores but depends on extracellular calcium concentrations. Additionally, I have determined that the extracellular calcium likely enters the oocyte through mechanosensory TRP channels. Downstream of the calcium signal, there is major turnover of the maternallystored mRNAs within the oocyte. I have examined the phenotype and transcriptome changes in eggs from mothers carrying the prage mutation, an allele previously uncharacterized in egg activation. I have also performed microarray analysis of the global set of transcripts that undergo cytoplasmic polyadenylation by WISPY at egg activation. These data taken together give us a big-picture view of the global changes occurring in the mRNA pool during egg activation. Advisors/Committee Members: Wolfner, Mariana Federica (chair), Goldberg, Michael Lewis (committee member), Liu, Jun (committee member).

Subjects/Keywords: Drosophila; egg activation; spermatogenesis

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

Sartain, C. (2013). Rna Regulation During Gametogenesis And Triggers Of Egg Activation In Drosophila Melanogaster. (Doctoral Dissertation). Cornell University. Retrieved from http://hdl.handle.net/1813/34218

Chicago Manual of Style (16th Edition):

Sartain, Caroline. “Rna Regulation During Gametogenesis And Triggers Of Egg Activation In Drosophila Melanogaster.” 2013. Doctoral Dissertation, Cornell University. Accessed December 05, 2020. http://hdl.handle.net/1813/34218.

MLA Handbook (7th Edition):

Sartain, Caroline. “Rna Regulation During Gametogenesis And Triggers Of Egg Activation In Drosophila Melanogaster.” 2013. Web. 05 Dec 2020.

Vancouver:

Sartain C. Rna Regulation During Gametogenesis And Triggers Of Egg Activation In Drosophila Melanogaster. [Internet] [Doctoral dissertation]. Cornell University; 2013. [cited 2020 Dec 05]. Available from: http://hdl.handle.net/1813/34218.

Council of Science Editors:

Sartain C. Rna Regulation During Gametogenesis And Triggers Of Egg Activation In Drosophila Melanogaster. [Doctoral Dissertation]. Cornell University; 2013. Available from: http://hdl.handle.net/1813/34218

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