Life Sciences Commons^™

Micrornas: Tiny Regulators With Great Potential, Victor Ambros

Victor R. Ambros

Animal genomes contain an abundance of small genes that produce regulatory RNAs of about 22 nucleotides in length. These microRNAs are diverse in sequence and expression patterns, and are evolutionarily widespread, suggesting that they may participate in a wide range of genetic regulatory pathways.

An Extensive Class Of Small Rnas In Caenorhabditis Elegans, Rosalind Lee, Victor Ambros

Victor R. Ambros

The lin-4 and let-7 antisense RNAs are temporal regulators that control the timing of developmental events in Caenorhabditis elegans by inhibiting translation of target mRNAs. let-7 RNA is conserved among bilaterian animals, suggesting that this class of small RNAs [microRNAs (miRNAs)] is evolutionarily ancient. Using bioinformatics and cDNA cloning, we found 15 new miRNA genes in C. elegans. Several of these genes express small transcripts that vary in abundance during C. elegans larval development, and three of them have apparent homologs in mammals and/or insects. Small noncoding RNAs of the miRNA class appear to be numerous and diverse.

Cloning Of Canine Γ-Tubulin (Tubg1) Cdna And Mapping To Cfa9, Duska J. Sidjanin, F Xue, J Mcelwee, Jennifer L. Johnson, C Holmgren, Cathryn S. Mellersh, Elaine A. Ostrander, Gregory M. Acland, Gustavo D. Aguirre

Gustavo D. Aguirre, VMD, PhD

No abstract provided.

Development. Dicing Up Rnas, Victor Ambros

Victor R. Ambros

Comment on: A cellular function for the RNA-interference enzyme Dicer in the maturation of the let-7 small temporal RNA. [Science. 2001]

Molecular Identification Of Smg-4, Required For Mrna Surveillance In C.Elegans, Rachel Aronoff, Renee Baran, Jonathan Hodgkin

Renee Baran

Premature termination codons trigger a process in eukaryotes known as nonsense mediated decay or mRNA surveillance, resulting in the rapid decay of the aberrant transcript. Studies in C.elegans have shown this system is mediated by seven smg genes and can prevent the accumulation of toxic, truncated peptides. Here we report the cloning of smg-4 by physical mapping and functional rescue assays. The minimal rescuing activity is found within a genomic operon, encoding a novel protein. The final exon of the gene is alternatively spliced for expression of two different isoforms. Although no known genes were found to exhibit significant homology …

Reversible Calcium-Regulated Stopcocks In Legume Sieve Tubes, Michael Knoblauch, Winfried Peters, Katrin Ehlers, Aart Van Bel

Winfried S. Peters

Does Growth Correlate With Turgor-Induced Elastic Strain In Stems? A Re-Evaluation Of De Vries' Classical Experiments, Winfried Peters, Maggie Farm, A. Kopf

Winfried S. Peters

Time Course And Temporal Order Of Changes In Movement Kinematics During Motor Learning: Effect Of Joint And Instruction, T. Kempf, D. Corcos, D. Flament

Timothy Kempf

Learning a motor task is associated with specific changes in movement kinematics. Recently, it has been shown that changes in different kinematic parameters occurred with different time courses for subjects who practiced simple, single-joint elbow movements. For example, movement time was seen to decrease and level off in a shorter time than peak velocity, which increased and plateaued later. What is not known, however, is whether the time course and temporal order of these learning-related changes seen at the elbow are similar for movements learned at other joints and with different instructions. In this study, neurologically normal subjects practiced 50°-flexion …

Behavioural Assessment Of Visual Acuity In Bumblebees (Bombus Impatiens), Robert Gegear, Todd Macuda, Terence Laverty, Brian Timney

Robert J. Gegear

measure resolution acuity in bumblebees (Bombus impatiens). Bees were required to discriminate between horizontal and vertical gratings in a Y-maze apparatus. The gratings had a mean luminance of 9 cd m−2 and a Michelson contrast of 84 %. For different bees, either the horizontal or vertical grating was rewarded. Rewarded gratings were associated with a sucrose and water solution (30 % sucrose by volume) and unrewarded gratings with plain water. Acuity estimates were established at several different viewing distances over several sessions using a method of constant stimuli. Visual acuity functions were generated from the performance data, and acuity thresholds …

Developmental Systems, Darwinian Evolution,And The Unity Of Science, Bruce Weber, David Depew

David J Depew

No abstract provided.

The Pattern, Rate, And Range Of Within-Patch Movement Of A Stem-Galling Fly, Warren Abrahamson, J.T. Cronin, K. Hyland

Warren G. Abrahamson, II

No abstract provided.

Temporal Variation In Herbivore Host-Plant Preference And Offspring Performance: Constraints On Host-Plant Adaptation, Warren Abrahamson, J.T. Cronin, T.P. Craig

Warren G. Abrahamson, II

No abstract provided.

Potential Effect Of Anoplophora Glabripennis (Coleoptera: Cerambycidae) On Urban Trees In The United States, David Nowak, Judith Pasek, Ronaldo Sequeira, Daniel Crane, Victor Mastro

Judith E Pasek

Anoplophora glabripennis Motschulsky, a wood borer native to Asia, was recently found in New York City and Chicago. In an attempt to eradicate these beetle populations, thousands of infested city trees have been removed. Field data from nine U.S. cities and national tree cover data were used to estimate the potential effects of A. glabripennis on urban resources through time. For the cities analyzed, the potential tree resources at risk to A. glabripennis attack based on host preferences, ranges from 12 to 61% of the city tree population, with an estimated value of $72 million-$2.3 billion per city. The corresponding …

Gall Flies, Inquilines, And Goldenrods: A Model For Host-Race Formation And Sympatric Speciation, Warren Abrahamson, M.D. Eubanks, C.P. Blair, A.V. Whipple

Warren G. Abrahamson, II

No abstract provided.

Do Parasitoids Diversify In Response To Host-Plant Shifts By Herbivorous Insects?, Warren Abrahamson, J.T. Cronin

Warren G. Abrahamson, II

No abstract provided.

The Temporal Control Of Cell Cycle And Cell Fate In Caenorhabditis Elegans, Victor Ambros

Victor R. Ambros

The nematode Caenorhabditis elegans develops through two major phases: the first phase, embryogenesis, consists of a rapid series of cleavage cell divisions leading to morphogenesis of a first stage larva. The second phase is postembryonic development, which consists of developmentally regulated cell cycles that occur during the four larval stages leading to the adult. Precursor cells set aside during embryogenesis divide through stereotypical cell lineage patterns during the four larval stages to generate larval and adult structures. The precise timing of the postembryonic cell divisions is under strict control, in most cases with a developmentally regulated G1. In certain postembryonic …

Perceptions And Use Of Canada's Food Guide To Healthy Eating By Grocery Shoppers In London, Ontario, Alicia Garcia, Leonard Piché

Leonard Piché

Limited information exists on grocery shoppers' perceptions and use of Canada's Food Guide to Healthy Eating. The main objective of this study was to examine grocery shoppers' perceptions and use of the food guide in London, Ontario. The guide tearsheet and a self-administered questionnaire about food-buying practices were distributed to 2,000 food shoppers in ten London supermarkets. The response rate was 572 of 2,000 shoppers, or 29%; detailed results are reported in a separate paper. Four months later, a follow-up survey on the perceptions and use of the food guide was conducted through the use of a mailed questionnaire. (Both …

Hydraulic Conductance And Mercury-Sensitive Water Transport For Roots Of Opuntia Acanthocarpa In Relation To Soil Drying And Rewetting, P. Martre, Gretchen North, P. Nobel

Gretchen North

Drought-induced changes in root hydraulic conductance (L P) and mercury-sensitive water transport were examined for distal (immature) and mid-root (mature) regions ofOpuntia acanthocarpa. During 45 d of soil drying,L P decreased by about 67% for distal and mid-root regions. After 8 d in rewetted soil,L P recovered to 60% of its initial value for both regions. Axial xylem hydraulic conductivity was only a minor limiter of L P. Under wet conditions, HgCl2 (50 μM), which is known to block membrane water-transport channels (aquaporins), decreasedL P and the radial hydraulic conductance for the stele (L R, S) of the distal root …

Factors Influencing Food-Buying Practices Of Grocery Shoppers In London, Ontario, Leonard Piché, Alicia Garcia

Leonard Piché

We need to understand better the reasons why people choose to buy the foods that they do. The main objective of this study was to obtain information on some of the factors that influence food-buying practices of grocery shoppers in London, Ontario. For this study, a copy of Canada's Food Guide to Healthy Eating tearsheet and a self-administered seven-item postcard-style questionnaire were distributed to 2,000 grocery shoppers in ten London A&P supermarkets; 29% of receptive shoppers (572 of 2,000) completed the survey. Grocery shoppers indicated that price, freshness and health considerations were the top three factors considered important when buying …

Genetic Biotechnology And Evolutionary Theory: Some Unsolicited Advice, David Depew

David J Depew

In his book The Biotech Century Jeremy Rifkin makes arguments about the dangers of market-driven genetic biotechnology in medical and agricultural contexts. Believing that Darwinism is too compromised by a competitive ethic to resist capitalist depredations of the “genetic commons,” and perhaps hoping to pick up anti-Darwinian allies, he turns for support to unorthodox non-Darwinian views of evolution. The Darwinian tradition, more closely examined, contains resources that might better serve his argument. The robust tradition associated with Theodosius Dobzhansky, Ernst Mayr, and others provides an alternative, scientifically sound basis for challenging the rhetoric of genetic reductionism.