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Full-Text Articles in Biology

Mir319a Targeting Of Tcp4 Is Critical For Petal Growth And Development In Arabidopsis, Anwesha Nag, Stacey King, Thomas Jack Dec 2009

Mir319a Targeting Of Tcp4 Is Critical For Petal Growth And Development In Arabidopsis, Anwesha Nag, Stacey King, Thomas Jack

Dartmouth Scholarship

In a genetic screen in a drnl-2 background, we isolated a loss-of-function allele in miR319a (miR319a129). Previously, miR319a has been postulated to play a role in leaf development based on the dramatic curled-leaf phenotype of plants that ectopically express miR319a (jaw-D). miR319a129 mutants exhibit defects in petal and stamen development; petals are narrow and short, and stamens exhibit defects in anther development. The miR319a129 loss-of-function allele contains a single-base change in the middle of the encoded miRNA, which reduces the ability of miR319a to recognize targets. Analysis of the expression patterns of the …


Ceramide Kinase Regulates Phospholipase C And Phosphatidylinositol 4, 5, Bisphosphate In Phototransduction, Ujjaini Dasgupta, Takeshi Bamba, Salvatore Chiantia, Pusha Karim, Ahmad N. Abou Tayoun Nov 2009

Ceramide Kinase Regulates Phospholipase C And Phosphatidylinositol 4, 5, Bisphosphate In Phototransduction, Ujjaini Dasgupta, Takeshi Bamba, Salvatore Chiantia, Pusha Karim, Ahmad N. Abou Tayoun

Dartmouth Scholarship

Phosphoinositide-specific phospholipase C (PLC) is a central effector for many biological responses regulated by G-protein-coupled receptors including Drosophila phototransduction where light sensitive channels are activated downstream of NORPA, a PLCbeta homolog. Here we show that the sphingolipid biosynthetic enzyme, ceramide kinase, is a novel regulator of PLC signaling and photoreceptor homeostasis. A mutation in ceramide kinase specifically leads to proteolysis of NORPA, consequent loss of PLC activity, and failure in light signal transduction. The mutant photoreceptors also undergo activity-dependent degeneration. Furthermore, we show that a significant increase in ceramide, resulting from lack of ceramide kinase, perturbs the membrane microenvironment of …


Manipulating Testosterone To Assess Links Between Behavior, Morphology, And Performance In The Brown Anole Anolis Sagrei, Robert M. Cox, Derek S. Stenquist, Justin P. Henningsen, Ryan Calsbeek Aug 2009

Manipulating Testosterone To Assess Links Between Behavior, Morphology, And Performance In The Brown Anole Anolis Sagrei, Robert M. Cox, Derek S. Stenquist, Justin P. Henningsen, Ryan Calsbeek

Dartmouth Scholarship

Survival and reproductive success are determined by the complex interplay between behavior, physiology, morphology, and performance. When optimal trait combinations along these various phenotypic axes differ between sexes or across seasons, regulatory mechanisms such as sex steroids can often facilitate sex‐specific and/or seasonal trait expression. In this study, we used surgical castration and replacement of exogenous testosterone in adult male brown anoles (Anolis sagrei) to simultaneously examine the effects of testosterone on a suite of morphological (dewlap area, body size), physiological (immune function), behavioral (dewlap, head bob, and push‐up displays), and performance (stamina, sprint speed, bite force) traits. …


Overexpression Of Mazfsa In Staphylococcus Aureus Induces Bacteriostasis By Selectively Targeting Mrnas For Cleavage, Zhibiao Fu, Sandeep Tamber, Guido Memmi, Niles P. Donegan, Ambrose L. Cheung Jan 2009

Overexpression Of Mazfsa In Staphylococcus Aureus Induces Bacteriostasis By Selectively Targeting Mrnas For Cleavage, Zhibiao Fu, Sandeep Tamber, Guido Memmi, Niles P. Donegan, Ambrose L. Cheung

Dartmouth Scholarship

The role of chromosomally encoded toxin-antitoxin (TA) loci in bacterial physiology has been under debate, with the toxin proposed as either an inducer of bacteriostasis or a mediator of programmed cell death (PCD). We report here that ectopic expression of MazFSa, a toxin of the TA module from Staphylococcus aureus, led to a rapid decrease in CFU counts but most cells remained viable as determined by differential Syto 9 and propidium iodide staining after MazFSa induction. This finding suggested that the toxin MazFSa induced cell stasis rather than cell death. We also showed that MazFSa selectively cleaves cellular mRNAs in …