Bio-Med Roundup

This month in Bio-Med Roundup:
  • Blair et al. identified a protein that acts as a clutch to disable bacterial flagella during biofilm formation.
  • Belin et al. found that high impulsivity predicts the development of addiction-like behavior in rats, including compulsive cocaine-taking.
  • Lee et al. discovered that a transcription factor known to participate in the unfolded protein response is also involved in controlling lipid synthesis.
  • Gilbert et al. reported on the mitochondrial genome sequence of a male Paleo-Eskimo who lived in Greenland about 4000 years ago.
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New Science /AAAS Webinar:
CNVs vs SNPs: Understanding Human Structural Variation in Disease July 16, 2008, at 12 noon Eastern Time (9 a.m. Pacific, 4 p.m. GMT ).Improvements in array-based comparative genomic hybridization (CGH) techniques allow for exploration of the genome for sources of variability that could explain the strong genetic component of a number of disorders. Join our expert panelists to learn more about these technologies and how they can be applied in disease research. Ask questions of the speakers live!
Register TODAY: www.sciencemag.org/webinar
Produced by the Science /AAAS Business Office and sponsored by Agilent.




MOLECULAR BIOLOGY
 
Intersection of the RNA Interference and X-Inactivation Pathways (6 June 2008)
Y. Ogawa, B. K. Sun, J. T. Lee
Two noncoding RNAs required for X-chromosome inactivation in female mice form a duplex that is cleaved by the RNA interference machine, indicating a link between X inactivation and RNA interference.

Fission Yeast Pot1-Tpp1 Protects Telomeres and Regulates Telomere Length (6 June 2008)
T. Miyoshi, J. Kanoh, M. Saito, F. Ishikawa
Yeast chromosome ends are protected by a protein complex similar to that in mammals, which prevents end-to-end chromosome fusion and controls telomere length.
See related Perspective.

The Transcriptional Landscape of the Yeast Genome Defined by RNA Sequencing (6 June 2008)
U. Nagalakshmi et al.
A more complete catalog of transcribed DNA of yeast is assembled by shotgun sequencing of messenger RNA and reveals numerous previously unknown transcribed regions.

Regulation of Hepatic Lipogenesis by the Transcription Factor XBP1 (13 June 2008)
A.-H. Lee, E. F. Scapa, D. E. Cohen, L. H. Glimcher
In mice, a transcription factor known to participate in secretion is also necessary for induction of lipid synthesis by carbohydrates in the liver.
See related Perspective.

Activation of the Cellular DNA Damage Response in the Absence of DNA Lesions (13 June 2008)
E. Soutoglou and T. Misteli
Protein complexes that usually assemble on and repair damaged DNA can form at undamaged sites to halt the cell cycle if several of the proteins are first tethered there.

Proliferating Cells Express mRNAs with Shortened Untranslated Regions and Fewer MicroRNA Target Sites (20 June 2008)
R. Sandberg, J. R. Neilson, A. Sarma, P. A. Sharp, C. B. Burge
Dividing immune cells tend to synthesize messenger RNAs with shorter 3’ regulatory regions, possibly because less control is required over RNA functions.

Both Catalytic Steps of Nuclear Pre-mRNA Splicing Are Reversible (27 June 2008)
C.-K. Tseng and S.-C. Cheng
The transesterification splicing reactions performed on RNA by the spliceosome protein complex in eukaryotic cells are reversible.


MICROBIOLOGY

Predictive Behavior Within Microbial Genetic Networks (6 June 2008)
I. Tagkopoulos, Y.-C. Liu, Saeed Tavazoie
Predictable sequences of environmental signals can be exploited by bacteria so that they learn to anticipate future metabolic needs and thereby gain a competitive edge.
See related Perspective.

Evolution of Mammals and Their Gut Microbes (20 June 2008)
R. E. Ley et al.
Genomic sampling of the microbes in the feces of 60 mammals show that herbivores harbor the most diversity and that individuals of the same species have the same flora.

Ankyrin Repeat Proteins Comprise a Diverse Family of Bacterial Type IV Effectors (20 June 2008)
X. Pan, A. Lührmann, A. Satoh, M. A. Laskowski-Arce, C. R. Roy
A microbial protein containing ankyrin repeats is injected into host cells through a specialized secretion system where it prevents microtubule-dependent vesicular fusion.

Virus Attenuation by Genome-Scale Changes in Codon Pair Bias (27 June 2008)
J. R. Coleman et al.
Altering the frequency of the adjacent codons in the poliovirus genome results in an attenuated virus that could form the basis of a vaccine.


CELL BIOLOGY

Subdiffraction Multicolor Imaging of the Nuclear Periphery with 3D Structured Illumination Microscopy (6 June 2008)
L. Schermelleh et al.
Fluorescence tags illuminated through a diffraction grating reveal the structure of nuclear pores, surrounding channels, and chromatin at a resolution of about 100 nanometers.

An in Vivo Map of the Yeast Protein Interactome (13 June 2008)
K. Tarassov et al.
A method that identifies pairs of proteins that are 8 nanometers apart produces a map of interacting proteins in living yeast, finding known and previously unknown networks.

The Rag GTPases Bind Raptor and Mediate Amino Acid Signaling to mTORC1 (13 June 2008)
Y. Sancak et al.
Nutrients, specifically amino acids, are sensed by small guanosine triphosphatases, which bind to a signaling complex, moving it close to the nucleus where it initiates cell growth.

A Molecular Clutch Disables Flagella in the Bacillus subtilis Biofilm (20 June 2008)
K. M. Blair, L. Turner, J. T. Winkelman, H. C. Berg, D. B. Kearns
One bacterial protein synthesized during the production of a biofilm matrix acts as a clutch to disable the flagellum while the microbe is constrained in the biofilm.
See related Perspective.

Bora and the Kinase Aurora A Cooperatively Activate the Kinase Plk1 and Control Mitotic Entry (20 June 2008)
A. Seki, J. A. Coppinger, C.-Y. Jang, J. R. Yates III, G. Fang
Mitosis begins in mammalian cells when a protein accumulates between cell divisions and interacts with a second protein to initiate a cascade of kinase activation.

β-Arrestin–Mediated Localization of Smoothened to the Primary Cilium (27 June 2008)
J. J. Kovacs et al.
β-arrestin, which has several known roles in signaling systems, also links a key receptor to a motor protein so that the receptor can be transported to cilia for sensing environmental cues.
See related Perspective.


DEVELOPMENTAL BIOLOGY

The Transcription/Migration Interface in Heart Precursors of Ciona intestinalis (6 June 2008)
L. Christiaen et al.
In embryonic cells destined to form the heart in a simple chordate, a genetic network activates modules of effector genes for proteins that control cellular migration.

VelB/VeA/LaeA Complex Coordinates Light Signal with Fungal Development and Secondary Metabolism (13 June 2008)
Ö. Bayram et al.
The multiprotein velvet complex in the fungus Aspergillus nidulans coordinates light-responsive development and the generation of secondary metabolites such as antibiotics and toxins.
See related Perspective.

Polarization of the C. elegans Embryo by RhoGAP-Mediated Exclusion of PAR-6 from Cell Contacts (27 June 2008)
D. C. Anderson, J. S. Gill, R. M. Cinalli, J. Nance
Exclusion of a regulatory protein from cell-cell contacts in the developing worm allows it to direct the assembly of an asymmetrical cytoskeleton in preparation for gastrulation.

FGF-Dependent Mechanosensory Organ Patterning in Zebrafish (27 June 2008)
A. Nechiporuk and D. W. Raible
A fish sensory organ develops when a wave of migrating primordial cells cyclically deposits rosettes of differentiated cells under the influence of fibroblast growth factor.


NEUROSCIENCE/PSYCHOLOGY
 

High Impulsivity Predicts the Switch to Compulsive Cocaine-Taking (6 June 2008)
D. Belin, A. C. Mar, J. W. Dalley, T. W. Robbins, B. J. Everitt
Rats that are more impulsive, but not those that seek novelty, tend to compulsively consume cocaine and become addicted.

Patches with Links: A Unified System for Processing Faces in the Macaque Temporal Lobe (6 June 2008)
S. Moeller, W. A. Freiwald, D. Y. Tsao
The six regions of the macaque cortex that respond to faces are strongly and specifically interconnected, indicating hierarchical processing of face stimuli.

Transfer of Learning After Updating Training Mediated by the Striatum (13 June 2008)
E. Dahlin, A. S. Neely, A. Larsson, L. Bäckman, L. Nyberg
Individuals who become better at a letter recognition test through practice also improve at a different task, even without practice, when both tasks utilize the same brain region.

Tuned Responses of Astrocytes and Their Influence on Hemodynamic Signals in the Visual Cortex (20 June 2008)
J. Schummers, H. Yu, M. Sur
Astrocytes in the visual cortex respond to visual stimuli, showing receptive field properties (response kinetics, orientation, and localization) similar to those of neurons.
See related Perspective.

Serotonin Modulates Behavioral Reactions to Unfairness (27 June 2008)
M. J. Crockett, L. Clark, G. Tabibnia, M. D. Lieberman, T. W. Robbins
Individuals with low levels of brain serotonin are less likely to accept an unfair offer of money from other players in a laboratory game.


PLANT SCIENCE

Germination, Genetics, and Growth of an Ancient Date Seed (13 June 2008)
S. Sallon et al.
A 2000-year-old date seed -- recovered from archaeological excavations near the Dead Sea in Israel -- successfully germinated and grew.

Auxin Gradients Are Associated with Polarity Changes in Trees (20 June 2008)
E. M. Kramer et al.
In quaking aspen trees that have been injured, gradients of the hormone auxin redirect the wood grain as the wound heals.


GENETICS

Natural Selection Shapes Genome-Wide Patterns of Copy-Number Polymorphism in Drosophila melanogaster (20 June 2008)
J. J. Emerson, M. Cardoso-Moreira, J. O. Borevitz, M. Long
A high-resolution analysis of gene copy number in Drosphila species shows that most variations are deleterious but a few for resistance to toxins are being positively selected.

Phylogeny-Aware Gap Placement Prevents Errors in Sequence Alignment and Evolutionary Analysis (20 June 2008)
A. Löytynoja and N. Goldman
An algorithm that treats insertions and deletions as distinct events in genomic data improves sequence alignments, allowing more accurate phylogenetic studies.

A Phylogenomic Study of Birds Reveals Their Evolutionary History (27 June 2008)
S. J. Hackett et al.
Nuclear DNA sequences of 19 loci from 169 bird species lead to a revised phylogenetic tree of avian evolution, in which several well-accepted orders are not monophyletic.

Paleo-Eskimo mtDNA Genome Reveals Matrilineal Discontinuity in Greenland (27 June 2008)
M. T. P. Gilbert et al.
Ancient human DNA sequences from Greenland suggest that the earliest inhabitants of the far north were from a lineage distinct from extant Native Americans and Eskimos.


BIOCHEMISTRY

Recognition Dynamics Up to Microseconds Revealed from an RDC-Derived Ubiquitin Ensemble in Solution (13 June 2008)
O. F. Lange et al.
In solution, ubiquitin assumes all conformations seen in crystal structures of its complexes, indicating that it binds by conformational selection rather than induced fit.
See related Perspective.



New Science /AAAS Webinar:
CNVs vs SNPs: Understanding Human Structural Variation in Disease July 16, 2008, at 12 noon Eastern Time (9 a.m. Pacific, 4 p.m. GMT ).Improvements in array-based comparative genomic hybridization (CGH) techniques allow for exploration of the genome for sources of variability that could explain the strong genetic component of a number of disorders. Join our expert panelists to learn more about these technologies and how they can be applied in disease research. Ask questions of the speakers live!
Register TODAY: www.sciencemag.org/webinar
Produced by the Science /AAAS Business Office and sponsored by Agilent.