This month in Bio-Med Roundup:
- Dantas et al. found that a wide range of bacteria in the environment are both resistant to antibiotics and consume them as their only source of carbon for growth.
- Darland-Ransom et al. and Mercer and Helenius revealed roles of phosphatidylserine in normal cell function and viral infection.
- Russel et al. tracked the global circulation of seasonal influenza A (H3N2) viruses during 2002-2007.
- Gallarda et al. showed that ephrin signaling is important for segregating developing motor and sensory pathways.
This month’s Bio-Med Roundup is sponsored by:
Harvard Business School
Leadership and Strategy in Pharmaceuticals and Biotech, June
1–6, 2008
Leading Science-Based Enterprises, June 15–20, 2008
Consider it “innovation amplification.” When it
comes to science-based businesses, the only true way to achieve competitive
advantage is by managing innovation. But identifying scientific breakthroughs
today that will have the most commercial appeal tomorrow is no easy
feat. In response to this challenge, Harvard Business School has developed
two highly targeted programs that help leaders of science-based businesses
advance scientific knowledge and capture its value. Please visit www.exed.hbs.edu/category/sci.html
to learn more.
BIOCHEMISTRY
Crystal Structure of a Self-Spliced Group II Intron (4 April 2008)
N. Toor, K. S. Keating, S. D. Taylor, A. M. Pyle
The autocatalytic group II intron contains a network of unusual tertiary RNA interactions that form a metalloribozyme active site with parallels to eukaryotic spliceosomes.
See related Perspective.
Single-Molecule DNA Sequencing of a Viral Genome (4 April 2008)
T. D. Harris et al.
The M13 viral genome has been resequenced by a single-molecule method that allows simultaneous sequencing of 280,000 DNA strands of 25 bases with 100 percent coverage.
Deconstruction of Iterative Multidomain Polyketide Synthase Function (11 April 2008)
J. M. Crawford et al.
A eukaryotic polyketide natural product is synthesized by assembling seven malonyl building blocks on a specialized protein template where a cyclization cascade is initiated.
See related Perspective.
Reconstitution of Pilus Assembly Reveals a Bacterial Outer Membrane Catalyst (18 April 2008)
M. Nishiyama, T. Ishikawa, H. Rechsteiner, R. Glockshuber
The cell-free formation of the protruberant pilus of a pathogenic bacterium is accelerated by a protein that catalyzes supramolecular assembly without input of cellular energy.
Structural Basis of Toll-Like Receptor 3 Signaling with Double-Stranded RNA (18 April 2008)
L. Liu et al.
Two horseshoe-shaped monomers of an innate immunity receptor bind to viral RNA through carboxyl-terminal dimerization, ultimately triggering inflammation.
Divergence of Quaternary Structures Among Bacterial Flagellar Filaments (18 April 2008)
V. E. Galkin et al.
Flagellar proteins from two bacterial species diverge in their coiled-coil regions; only one triggers an immune response, which may have driven their evolutionary divergence.
Efficient Inhibition of the Alzheimer’s Disease β-Secretase by Membrane Targeting (25 April 2008)
L. Rajendran et al.
Tethering an inhibitor to a membrane anchor renders it effective against a membrane enzyme that creates the amyloid fragments deposited in Alzheimer’s disease, even in vivo.
NEUROSCIENCE
Entrainment of Neuronal Oscillations as a Mechanism of Attentional Selection (4 April 2008)
P. Lakatos, G. Karmos, A. D. Mehta, I. Ulbert, C. E. Schroeder
In monkeys that are paying attention to a rhythmic stimulus, brain oscillations become tuned to the stimulus so that the response in the visual cortex is enhanced.
Episodic-Like Memory in Rats: Is It Based on When or How Long Ago? (4 April 2008)
W. A. Roberts et al.
Unlike humans, who can place past events within a temporal framework, rats can only remember when an event happened by tracking the time elapsed since its occurrence.
Surface Mobility of Postsynaptic AMPARs Tunes Synaptic Transmission (11 April 2008)
M. Heine et al.
Desensitized glutamate receptors are exchanged for functional ones through lateral movement within membranes to help maintain fast excitatory neurotransmission.
See related Perspective.
Segregation of Axial Motor and Sensory Pathways via Heterotypic Trans-Axonal Signaling (11 April 2008)
B. W. Gallarda et al.
In mice, axons carrying signals from spinal cord to muscle are kept separate from those going in the opposite direction by ephrin signaling between them.
See related Perspective.
A Model for Neuronal Competition During Development (18 April 2008)
C. D. Deppmann et al.
Modeling and experiments show that neurons survive during development when neuronal sensitization to survival signals outweighs antagonistic signals for cell death.
The Antidepressant Fluoxetine Restores Plasticity in the Adult Visual Cortex (18 April 2008)
J. F. Maya Vetencourt et al.
An antidepressant drug increases growth factors and reduces inhibitory activity in the visual cortex of adult rats, thereby restoring the plasticity seen only during development.
CELL BIOLOGY
Reversible Compartmentalization of de Novo Purine Biosynthetic Complexes in Living Cells (4 April 2008)
S. An, R. Kumar, E. D. Sheets, S. J. Benkovic
The enzymes needed for purine biosynthesis cluster in the cytoplasm when cells are depleted of purine but dissociate when the demand for purine is low.
Leiomodin Is an Actin Filament Nucleator in Muscle Cells (11 April 2008)
D. Chereau et al.
The de novo assembly of the thin filaments in muscle cells is initiated by a newly described protein that efficiently nucleates actin polymer formation.
Video-Rate Far-Field Optical Nanoscopy Dissects Synaptic Vesicle Movement (11 April 2008)
V. Westphal et al.
Sequential subdiffraction resolution images of fluorescently labeled synaptic vesicles in live cells reveal that they exhibit several distinct movement patterns.
See related Perspective.
Wnt5a Control of Cell Polarity and Directional Movement by Polarized Redistribution of Adhesion Receptors (18 April 2008)
E. S. Witze, E. S. Litman, G. M. Argast, R. T. Moon, N. G. Ahn
A developmental signal causes clustering of membrane-associated proteins (including its receptor) at one end of the cell, marking the cell’s polarity for directional movement.
See related Perspective.
Role of C. elegans TAT-1 Protein in Maintaining Plasma Membrane Phosphatidylserine Asymmetry (25 April 2008)
M. Darland-Ransom et al.
A phospholipid translocase enzyme keeps a critical membrane lipid localized to the inner leaflet of the cell membrane so it does not trigger engulfment by immune cells.
See related Perspective.
Encoding Gender and Individual Information in the Mouse Vomeronasal Organ (25 April 2008)
J. He, L. Ma, S. Kim, J. Nakai, C. R. Yu
Mice can recognize the pheromones from individual mice through unique patterns of receptor activation in the vomeronasal organ.
MEDICINE
An Agonist of Toll-Like Receptor 5 Has Radioprotective Activity in Mouse and Primate Models (11 April 2008)
L. G. Burdelya et al.
A drug that triggers the pathway that cancer cells use to avoid death can protect healthy cells from the harmful effects of radiation treatment.
The Global Circulation of Seasonal Influenza A (H3N2) Viruses (18 April 2008)
C. A. Russell et al.
Recent seasonal flu strains constantly evolved in overlapping epidemics in Asia, then erupted to periodically sweep the world, ending in South America 6 to 18 months later.
Recapitulation of IVIG Anti-Inflammatory Activity with a Recombinant IgG Fc (18 April 2008)
R. M. Anthony et al.
By identifying the sugar modifications responsible for the therapeutic, anti-inflammatory effect of immunoglobulin, an improved recombinant version can be formulated.
Plastin 3 Is a Protective Modifier of Autosomal Recessive Spinal Muscular Atrophy (25 April 2008)
G. E. Oprea et al.
Expression of a protein that promotes axonal growth can compensate for the gene deletion in spinal muscular atrophy, indicating that axonal growth deficiencies cause the disease.
GENETICS
The Chemical Genomic Portrait of Yeast: Uncovering a Phenotype for All Genes (18 April 2008)
M. E. Hillenmeyer et al.
Exposing yeast cultures to an extensive variety of small molecules and environmental stresses indicates that almost all genes have a demonstrable biological function.\
Rare Structural Variants Disrupt Multiple Genes in Neurodevelopmental Pathways in Schizophrenia (25 April 2008)
T. Walsh et al.
Patients with schizophrenia carry multiple small deletions and duplications in their DNA that are associated nonrandomly with neuronal signaling and brain development pathways.
Metabolic Diversification—Independent Assembly of Operon-Like Gene Clusters in Different Plants (25 April 2008)
B. Field and A. E. Osbourn
Through strong selection, similar clusters of genes for triterpene biosynthesis have arisen independently through gene duplication and neofunctionalization in several plant lines.
Mechanism of Self-Sterility in a Hermaphroditic Chordate (25 April 2008)
Y. Harada et al.
The sea squirt prevents self-fertilization with two genetic loci, each of which encodes a tightly linked sperm-egg receptor-ligand pair, a system similar to that of flowering plants.
MICROBIOLOGY
Bacteria Subsisting on Antibiotics (4 April 2008)
G. Dantas, M. O. A. Sommer, R. D. Oluwasegun, G. M. Church
A wide range of bacteria in the environment, many related to human pathogens, are both resistant to antibiotics and consume them as their only source of carbon for growth.
Convergence of Campylobacter Species: Implications for Bacterial Evolution (11 April 2008)
S. K. Sheppard, N. D. McCarthy, D. Falush, M. C. J. Maiden
A survey of two related human pathogens shows that they are merging, probably as a result of their proximity in a new ecological niche—the intestines of farmed animals.
VIROLOGY
Evidence for Editing of Human Papillomavirus DNA by APOBEC3 in Benign and Precancerous Lesions (11 April 2008)
J.-P. Vartanian, D. Guétard, M. Henry, S. Wain-Hobson
A cellular enzyme that defends against infection by causing mutations in retroviruses can also mutate the genome of a DNA virus associated with benign and precancerous cells.
Vaccinia Virus Uses Macropinocytosis and Apoptotic Mimicry to Enter Host Cells (25 April 2008)
J. Mercer and A. Helenius
To infect host cells, vaccinia virus exposes phosphatidylserine on its surfaces, which signals host cells to recognize the virus as cellular debris and take it up for clearance.
See related Perspective.
MOLECULAR BIOLOGY
Selective Blockade of MicroRNA Processing by Lin-28 (4 April 2008)
S. R. Viswanathan, G. Q. Daley, R. I. Gregory
A protein necessary for reprogramming skin fibroblasts to pluripotent stem cells is an RNA-binding protein that normally inhibits microRNA processing in embryonic cells.
See related Perspective.
This month’s Bio-Med Roundup is sponsored by:
Harvard Business School
At Harvard Business School’s Leading Science-Based Enterprises
program,
you will discover what it takes to successfully advance products from
the
research lab to the marketplace. From identifying commercially viable
technology and financing its development to attracting top scientific
talent
and allocating resources across projects, you will emerge with the enterprise
models and business strategies you need to identify and commercialize
breakthroughs. Come explore the business behind the science. Please
visit www.exed.hbs.edu/programs/lsbe/
to learn more.
At Harvard Business School’s Leadership and Strategy in Pharmaceuticals
and
Biotech program, you will discover what it takes to gain a competitive
edge in
an ever-shifting marketplace. From understanding global implications
and
innovating new business models to mitigating risk and analyzing intellectual
property issues, you will emerge with the tools and skills you need
to develop
your own personal leadership model—one that positions you and
your
organization for a world of change. Become part of the new paradigm.
Please
visit www.exed.hbs.edu/programs/lspb/
to learn more.