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Full-Text Articles in Life Sciences

The Caenorhabditis Elegans Heterochronic Regulator Lin-14 Is A Novel Transcription Factor That Controls The Developmental Timing Of Transcription From The Insulin/Insulin-Like Growth Factor Gene Ins-33 By Direct Dna Binding., Marta Hristova, Darcy Birse, Yang Hong, Victor R. Ambros Nov 2005

The Caenorhabditis Elegans Heterochronic Regulator Lin-14 Is A Novel Transcription Factor That Controls The Developmental Timing Of Transcription From The Insulin/Insulin-Like Growth Factor Gene Ins-33 By Direct Dna Binding., Marta Hristova, Darcy Birse, Yang Hong, Victor R. Ambros

Victor R. Ambros

A temporal gradient of the novel nuclear protein LIN-14 specifies the timing and sequence of stage-specific developmental events in Caenorhabditis elegans. The profound effects of lin-14 mutations on worm development suggest that LIN-14 directly or indirectly regulates stage-specific gene expression. We show that LIN-14 can associate with chromatin in vivo and has in vitro DNA binding activity. A bacterially expressed C-terminal domain of LIN-14 was used to select DNA sequences that contain a putative consensus binding site from a pool of randomized double-stranded oligonucleotides. To identify candidates for genes directly regulated by lin-14, we employed DNA microarray hybridization to compare …


Developmental Biology. Encountering Micrornas In Cell Fate Signaling., Xantha Karp, Victor Ambros Nov 2005

Developmental Biology. Encountering Micrornas In Cell Fate Signaling., Xantha Karp, Victor Ambros

Victor R. Ambros

Comment on: LIN-12/Notch activation leads to microRNA-mediated down-regulation of Vav in C. elegans. [Science. 2005]


Silencing Of Retrotransposons In Dictyostelium By Dna Methylation And Rnai., Markus Kuhlmann, Branimira E. Borisova, Markus Kaller, Pontus Larsson, Dirk Stach, Jianbo Na, Ludwig Eichinger, Frank Lyko, Victor R. Ambros, Fredrik Soderbom, Christian Hammann, Wolfgang Nellen Nov 2005

Silencing Of Retrotransposons In Dictyostelium By Dna Methylation And Rnai., Markus Kuhlmann, Branimira E. Borisova, Markus Kaller, Pontus Larsson, Dirk Stach, Jianbo Na, Ludwig Eichinger, Frank Lyko, Victor R. Ambros, Fredrik Soderbom, Christian Hammann, Wolfgang Nellen

Victor R. Ambros

We have identified a DNA methyltransferase of the Dnmt2 family in Dictyostelium that was denominated DnmA. Expression of the dnmA gene is downregulated during the developmental cycle. Overall DNA methylation in Dictyostelium is approximately 0.2% of the cytosine residues, which indicates its restriction to a limited set of genomic loci. Bisulfite sequencing of specific sites revealed that DnmA is responsible for methylation of mostly asymmetric C-residues in the retrotransposons DIRS-1 and Skipper. Disruption of the gene resulted in a loss of methylation and in increased transcription and mobilization of Skipper. Skipper transcription was also upregulated in strains that had genes …


Mesodermally Expressed Drosophila Microrna-1 Is Regulated By Twist And Is Required In Muscles During Larval Growth., Nicholas S. Sokol, Victor R. Ambros Sep 2005

Mesodermally Expressed Drosophila Microrna-1 Is Regulated By Twist And Is Required In Muscles During Larval Growth., Nicholas S. Sokol, Victor R. Ambros

Victor R. Ambros

Although hundreds of evolutionarily conserved microRNAs have been discovered, the functions of most remain unknown. Here, we describe the embryonic spatiotemporal expression profile, transcriptional regulation, and loss-of-function phenotype of Drosophila miR-1 (DmiR-1). DmiR-1 RNA is highly expressed throughout the mesoderm of early embryos and subsequently in somatic, visceral, and pharyngeal muscles, and the dorsal vessel. The expression of DmiR-1 is controlled by the Twist and Mef2 transcription factors. DmiR-1KO mutants, generated using ends-in gene targeting, die as small, immobilized second instar larvae with severely deformed musculature. This lethality is rescued when a DmiR-1 transgene is expressed specifically in the mesoderm …


Glycemic Index, Glycemic Load, And Pancreatic Cancer Risk (Canada), Stephanie A. Navarro Silvera, Thomas E. Rohan, Meera Jain, Paul D. Terry, Geoffrey R. Howe, Anthony B. Miller May 2005

Glycemic Index, Glycemic Load, And Pancreatic Cancer Risk (Canada), Stephanie A. Navarro Silvera, Thomas E. Rohan, Meera Jain, Paul D. Terry, Geoffrey R. Howe, Anthony B. Miller

Department of Public Health Scholarship and Creative Works

There is some evidence that plasma insulin and post-load plasma glucose may be associated with the risk of pancreatic cancer. Glycemic index and glycemic load are measures, which allow the carbohydrate content of individual foods to be classified according to their postprandial glycemic effects and hence their effects on circulating insulin levels. Therefore, we examined pancreatic cancer risk in association with a glycemic index (GI), glycemic load (GL), and intake of dietary carbohydrate and sugar in a prospective cohort of 49,613 Canadian women enrolled in the National Breast Screening Study (NBSS) who completed a self-administered food frequency questionnaire between 1980 …


Morphological And Molecular Defects In Zebrafish Embryos (Danio Rerio) After Chromated Copper Arsenate Exposure, Kerry Jean Lee Apr 2005

Morphological And Molecular Defects In Zebrafish Embryos (Danio Rerio) After Chromated Copper Arsenate Exposure, Kerry Jean Lee

Biological Sciences Theses & Dissertations

This investigation identified the morphological defects caused by different concentrations of chromium, copper, and arsenic (CCA) on the developing zebrafish embryo; in addition to defects caused by the three combined components (complete CCA). A change in the DNA of the developing embryos in response to the three components of CCA and complete CCA was also determined. Early Dania rerio embryos were cultured for five days with various concentrations of CCA components and complete CCA. Morphological defects were assessed with light microscopy and DNA fragmentation was determined by agarose gel electrophoresis. Embryonic exposure of D. rerio to sub lethal concentrations of …


Response To Selection Of Peromyscus Leucopus: Response Of Spermatogenesis And Reproductive Behavior To Selection On Gonadal Development In An Outbred Population Of White-Footed Mice (Peromyscus Leucopus), Kathleen Rathbun Sharp Jan 2005

Response To Selection Of Peromyscus Leucopus: Response Of Spermatogenesis And Reproductive Behavior To Selection On Gonadal Development In An Outbred Population Of White-Footed Mice (Peromyscus Leucopus), Kathleen Rathbun Sharp

Dissertations, Theses, and Masters Projects

No abstract provided.