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Cell and Developmental Biology

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1999

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Full-Text Articles in Life Sciences

The Lin-4 Regulatory Rna Controls Developmental Timing In Caenorhabditis Elegans By Blocking Lin-14 Protein Synthesis After The Initiation Of Translation, Philip Olsen, Victor Ambros Dec 1999

The Lin-4 Regulatory Rna Controls Developmental Timing In Caenorhabditis Elegans By Blocking Lin-14 Protein Synthesis After The Initiation Of Translation, Philip Olsen, Victor Ambros

Victor R. Ambros

lin-4 encodes a small RNA that is complementary to sequences in the 3' untranslated region (UTR) of lin-14 mRNA and that acts to developmentally repress the accumulation of LIN-14 protein. This repression is essential for the proper timing of numerous events of Caenorhabditis elegans larval development. We have investigated the mechanism of lin-4 RNA action by examining the fate of lin-14 mRNA in vivo during the time that lin-4 RNA is expressed. Our results indicate that the rate of synthesis of lin-14 mRNA, its state of polyadenylation, its abundance in the cytoplasmic fraction, and its polysomal sedimentation profile do not …

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The Correlation Of Profiles Of Surface Ph And Elongation Growth In Maize Roots, Winfried Peters, Hubert Felle Oct 1999

The Correlation Of Profiles Of Surface Ph And Elongation Growth In Maize Roots, Winfried Peters, Hubert Felle

Winfried S. Peters

High-resolution profiles of surface pH and growth along vertically growing maize (Zea mays) primary root tips were determined simultaneously by pH-sensitive microelectrodes and marking experiments. Methodological tests were carried out that proved the reliability of our kinematic growth analysis, while questioning the validity of an alternative technique employed previously. A distal acidic zone around the meristematic region and a proximal one around the elongation zone proper were detected. This pattern as such persisted irrespective of the bulk pH value. The proximal acidic region coincided with maximum relative elemental growth rates (REGR), and both characters reacted in a correlated …

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The Timing Oflin-4rna Accumulation Controls The Timing Of Postembryonic Developmental Events Incaenorhabditis Elegans, Rhonda Feinbaum, Victor Ambros May 1999

The Timing Oflin-4rna Accumulation Controls The Timing Of Postembryonic Developmental Events Incaenorhabditis Elegans, Rhonda Feinbaum, Victor Ambros

Victor R. Ambros

The lin-4 gene encodes a small RNA that is required to translationally repress lin-14 toward the end of the first larval stage of Caenorhabditis elegans development. To determine if the timing of LIN-14 protein down-regulation depends on the temporal profile of lin-4 RNA level, we analyzed the stage-specificity of lin-4 RNA expression during wild-type development and examined the phenotypes of transgenic worms that overexpress lin-4 RNA during the first larval stage. We found that lin-4 RNA first becomes detectable at approximately 12 h of wild-type larval development and rapidly accumulates to nearly maximum levels by 16 h. This profile of …

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Cell Cycle-Dependent Sequencing Of Cell Fate Decisions In Caenorhabditis Elegans Vulva Precursor Cells, Victor Ambros Apr 1999

Cell Cycle-Dependent Sequencing Of Cell Fate Decisions In Caenorhabditis Elegans Vulva Precursor Cells, Victor Ambros

Victor R. Ambros

In Caenorhabditis elegans, the fates of the six multipotent vulva precursor cells (VPCs) are specified by extracellular signals. One VPC expresses the primary (1 degrees ) fate in response to a Ras-mediated inductive signal from the gonad. The two VPCs flanking the 1 degrees cell each express secondary (2 degrees ) fates in response to lin-12-mediated lateral signaling. The remaining three VPCs each adopt the non-vulval tertiary (3 degrees ) fate. Here I describe experiments examining how the selection of these vulval fates is affected by cell cycle arrest and cell cycle-restricted lin-12 activity. The results suggest that lin-12 participates …

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Xet-Related Genes And Growth Kinematics In Barley Leaves, Winfried Peters, Wieland Fricke, Peter Chandler Apr 1999

Xet-Related Genes And Growth Kinematics In Barley Leaves, Winfried Peters, Wieland Fricke, Peter Chandler

Winfried S. Peters

Recently Schünmann et al. (1997; Plant, Cell and Environment 20, 1439–1450) investigated the correlation of spatial patterns of xyloglucan-endotransglycosylase (XET) activity, XET-related mRNAs, and growth in elongating barley (Hordeum vulgare L.) leaves. Here, methodological difficulties in the kinematic growth analysis are discussed, and it is concluded that the role that XET-related gene activity plays in the control of spatial growth patterns remains undetermined.

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