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Full-Text Articles in Molecular Biology

Alternative Use Of Dna Binding Domains By The Neurospora White Collar Complex Dictates Circadian Regulation And Light Responses, Bin Wang, Xiaoying Zhou, Jennifer J. Loros, Jay C. Dunlap Dec 2015

Alternative Use Of Dna Binding Domains By The Neurospora White Collar Complex Dictates Circadian Regulation And Light Responses, Bin Wang, Xiaoying Zhou, Jennifer J. Loros, Jay C. Dunlap

Dartmouth Scholarship

In the Neurospora circadian system, the White Collar complex (WCC) of WC-1 and WC-2 drives transcription of the circadian pacemaker gene frequency (frq), whose gene product, FRQ, as a part of the FRQ-FRH complex (FFC), inhibits its own expression. The WCC is also the principal Neurospora photoreceptor; WCC-mediated light induction of frq resets the clock, and all acute light induction is triggered by WCC binding to promoters of light-induced genes. However, not all acutely light-induced genes are also clock regulated, and conversely, not all clock-regulated direct targets of WCC are light induced; the structural determinants governing the shift …


Cell Type–Dependent Mechanisms For Formin-Mediated Assembly Of Filopodia, Lorna E. Young, Ernest G. Heimsath, Henry N. Higgs Oct 2015

Cell Type–Dependent Mechanisms For Formin-Mediated Assembly Of Filopodia, Lorna E. Young, Ernest G. Heimsath, Henry N. Higgs

Dartmouth Scholarship

Filopodia are finger-like protrusions from the plasma membrane and are of fundamental importance to cellular physiology, but the mechanisms governing their assembly are still in question. One model, called convergent elongation, proposes that filopodia arise from Arp2/3 complex-nucleated dendritic actin networks, with factors such as formins elongating these filaments into filopodia. We test this model using constitutively active constructs of two formins, FMNL3 and mDia2. Surprisingly, filopodial assembly requirements differ between suspension and adherent cells. In suspension cells, Arp2/3 complex is required for filopodial assembly through either formin. In contrast, a subset of filopodia remains after Arp2/3 complex inhibition in …


Coupling Between Cytoplasmic Concentration Gradients Through Local Control Of Protein Mobility In The Caenorhabditis Elegans Zygote, Youjun Wu, Huaiying Zhang, Erik E. Griffin Jun 2015

Coupling Between Cytoplasmic Concentration Gradients Through Local Control Of Protein Mobility In The Caenorhabditis Elegans Zygote, Youjun Wu, Huaiying Zhang, Erik E. Griffin

Dartmouth Scholarship

Cell polarity is characterized by the asymmetric distribution of factors at the cell cortex and in the cytoplasm. Although mechanisms that establish cortical asymmetries have been characterized, less is known about how persistent cytoplasmic asymmetries are generated. During the asymmetric division of the Caenorhabditis elegans zygote, the PAR proteins orchestrate the segregation of the cytoplasmic RNA-binding proteins MEX-5/6 to the anterior cytoplasm and PIE-1, POS-1, and MEX-1 to the posterior cytoplasm. In this study, we find that MEX-5/6 control the segregation of GFP::PIE-1, GFP::POS-1, and GFP::MEX-1 by locally increasing their mobility in the anterior cytoplasm. Remarkably, PIE-1, POS-1, and MEX-1 …


Ploidy Variation In Multinucleate Cells Changes Under Stress, Cori A. Anderson, Samantha Roberts, Huaiying Zhang, Courtney M. Kelly, Alexxy Kendall, Changhwan Lee, John Gerstenberger, Aaron B. Koenig, Ruth Kabeche, Amy S. Gladfelter Jan 2015

Ploidy Variation In Multinucleate Cells Changes Under Stress, Cori A. Anderson, Samantha Roberts, Huaiying Zhang, Courtney M. Kelly, Alexxy Kendall, Changhwan Lee, John Gerstenberger, Aaron B. Koenig, Ruth Kabeche, Amy S. Gladfelter

Dartmouth Scholarship

Ploidy variation is found in contexts as diverse as solid tumors, drug resistance in fungal infection, and normal development. Altering chromosome or genome copy number supports adaptation to fluctuating environments but is also associated with fitness defects attributed to protein imbalances. Both aneuploidy and polyploidy can arise from multinucleate states after failed cytokinesis or cell fusion. The consequences of ploidy variation in syncytia are difficult to predict because protein imbalances are theoretically buffered by a common cytoplasm. We examined ploidy in a naturally multinucleate fungus, Ashbya gossypii. Using integrated lac operator arrays, we found that chromosome number varies substantially …