Life Sciences Commons^™

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 …

Time Course And Temporal Order Of Changes In Movement Kinematics During Learning Of Fast And Accurate Elbow Flexions, D. Flament, M. Shapiro, T. Kempf, D. Corcos

Timothy Kempf

Learning of a motor task, such as making accurate goal-directed movements, is associated with a number of changes in limb kinematics and in the EMG activity that produces the movement. Some of these changes include increases in movement velocity, improvements in end-point accuracy, and the development of a biphasic/triphasic EMG pattern for fast movements. One question that has remained unanswered is whether the time course of the learning-related changes in movement parameters is similar for all parameters. The present paper focuses on this question and presents evidence that different parameters evolve with a specific temporal order. Neurologically normal subjects were …

Analysis Of Age And Growth In Two Eastern Pacific Groupers (Serranidae: Epinephelinae), Matthew Craig, Daniel Pondella, John Hafner

Daniel Pondella

In an attempt to characterize species specific-growth rates of two Eastern Pacific groupers, individuals from two sympatric species, Epinephelus labriformis (n = 173), and Cephalopholis panamensis (n = 127), were collected at various localities in Mexico and the Galápagos archipelago in 1997 and 1998. Sagittal otoliths were removed, and age of each individual was determined by direct visual inspection of annuli present following sectioning. Length/weight relationships were determined, and growth curves were generated using the von Bertalanffy growth model. The two species demonstrated similar growth rates, yet, as determined by the von Bertalanffy parameters, E. labriformis tended towards a larger …

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

Winfried S. Peters

Action Of Repeat-Induced Point Mutation On Both Strands Of A Duplex And On Tandem Duplications Of Various Sizes In Neurospora, Michael Watters, Thomas Randall, Brian Margolin, Eric Selker, David Stadler

Michael Watters

In Neurospora crassa, DNA sequence duplications are detected and altered efficiently during the sexual cycle by a process known as RIP (repeat-induced point mutation). Affected sequences are subjected to multiple GC-to-AT mutations. To explore the pattern in which base changes are laid down by RIP we examined two sets of strains. First, we examined the products of a presumptive spontaneous RIP event at the mtr locus. Results of sequencing suggested that a single RIP event produces two distinct patterns of change, descended from the two strands of an affected DNA duplex. Equivalent results were obtained using an exceptional tetrad from …

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 …

The C. Elegans Homeodomain Gene Unc-42 Regulates Chemosensory And Glutamate Receptor Expression, Renee Baran, Rachel Aronoff, Gian Garriga

Renee Baran

Genes that specify cell fate can influence multiple aspects of neuronal differentiation, including axon guidance, target selection and synapse formation. Mutations in the unc-42 gene disrupt axon guidance along the C. elegans ventral nerve cord and cause distinct functional defects in sensory-locomotory neural circuits. Here we show that unc-42 encodes a novel homeodomain protein that specifies the fate of three classes of neurons in the Caenorhabditis elegans nervous system: the ASH polymodal sensory neurons, the AVA, AVD and AVE interneurons that mediate repulsive sensory stimuli to the nematode head and anterior body, and a subset of motor neurons that innervate …

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 …

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

Winfried S. Peters

Oviposition Preference And Offspring Performance Of Eurosta Solidaginis On Genotypes Of Solidago Altissima, Warren Abrahamson, T. Craig, J. Itami, J. Horner

Warren G. Abrahamson, II

No abstract provided.

Episodic Reproduction In Two Fire-Prone Palms, Serenoa Repens And Sabal Etonia (Palmae), Warren Abrahamson

Warren G. Abrahamson, II

No abstract provided.

Influence Of Plant Genotype And Early-Season Water Deficits On Oviposition Preference And Offspring Performance In Eurosta Solidaginis (Diptera: Tephritidae), Warren Abrahamson, J. Horner

Warren G. Abrahamson, II

No abstract provided.

Host-Plant Genotype And Other Herbivores Influence Goldenrod Stem Galler Preference And Performance, Warren Abrahamson, J. Cronin

Warren G. Abrahamson, II

No abstract provided.

Photoreceptor Dysplasia (Pd) In Miniature Schnauzer Dogs: Evaluation Of Candidate Genes By Molecular Genetic Analysis, Qi Zhang, V J. Baldwin, Gregory M. Acland, C J. Parshall, J. Haskell, Gustavo D. Aguirre, Kunal Ray

Gustavo D. Aguirre, VMD, PhD

Overview Of The International Workshop On Canine Genetics, Gustavo D. Aguirre, Kunal Ray, Gregory M. Acland

Gustavo D. Aguirre, VMD, PhD

No abstract provided.