• Genetics
• Molecular Biology
• Cell Biology
• Neuroscience/Psychology
• Immunology
• Medicine
• Biochemistry
• Plant Science

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.

GENETICS
 
The Physcomitrella Genome Reveals Evolutionary Insights into the Conquest of Land by Plants (4 January 2008)
S. A. Rensing et al.
Comparison of the moss genome sequence with those of other plants reveals hallmarks of colonization of land, including genes to manage terrestrial stresses such as dehydration.

Polymorphic Y Chromosomes Harbor Cryptic Variation with Manifold Functional Consequences (4 January 2008)
B. Lemos, L. O. Araripe, D. L. Hartl
Unexpectedly, the Y chromosome exerts strong regulatory effects on X-linked and autosomal genes in Drosophila.
See related Perspective.

Natural Genetic Variation in Lycopene Epsilon Cyclase Tapped for Maize Biofortification (18 January 2008)
C. E. Harjes et al.
Identification of the gene that controls vitamin A levels in maize will allow production of varieties that can improve global health without using transgenic methods.

A Localized Negative Genetic Correlation Constrains Microevolution of Coat Color in Wild Sheep (18 January 2008)
J. Gratten et al.
Although the fitness of wild sheep increases with size, large, dark sheep are becoming rarer because color is genetically linked to genes that decrease fitness.

Alignment Uncertainty and Genomic Analysis (24 January 2008)
K. M. Wong, M. A. Suchard, J. P. Huelsenbeck
Comparative evolutionary genomics can be improved by taking into account the uncertainties inherent in aligning genes from organism to organism.
See related Perspective.


MOLECULAR BIOLOGY

Heterochromatin and RNAi Are Required to Establish CENP-A Chromatin at Centromeres (4 January 2008)
H. D. Folco, A. L. Pidoux, T. Urano, R. C. Allshire
Formation of the centromere, the specialized region by which chromosomes are pulled apart during cell division, requires the presence of RNAi-induced heterochromatin.

DNA Oxidation as Triggered by H3K9me2 Demethylation Drives Estrogen-Induced Gene Expression (11 January 2008)
B. Perillo et al.
Estrogens trigger histone demethylation, which elicits a local DNA oxidative burst that guides initial assembly of the transcription/repair complex.

Control of Genic DNA Methylation by a jmjC Domain-Containing Protein in Arabidopsis thaliana (24 January 2008)
H. Saze, A. Shiraishi, A. Miura, T. Kakutani
A plant demethylase checks the spread of DNA methylation from silenced transposons and repetitive DNA to nearby genes, preventing their inappropriate inhibition.

Concurrent Fast and Slow Cycling of a Transcriptional Activator at an Endogenous Promoter (24 January 2008)
T. S. Karpova et al.
A yeast transcription factor binds onto and off its promoter rapidly, controlling initiation, but also shows a 30-min cycle as the number of accessible promoters varies.


CELL/DEVELOPMENTAL BIOLOGY

Assembly Mechanism of the Contractile Ring for Cytokinesis by Fission Yeast (4 January 2008)
D. Vavylonis, J.-Q. Wu, S. Hao, B. O’Shaughnessy, T. D. Pollard
The contractile ring of cell division is powered by myosin motors on the cell equator, which capture and pull actin filaments growing randomly from the equator.

Membrane Phosphatidylserine Regulates Surface Charge and Protein Localization (11 January 2008)
T. Yeung, G. E. Gilbert, J. Shi, J. Silvius, A. Kapus, S. Grinstein
A fluorescent tag specific for a negatively charged lipid shows that its higher concentration in endosomes and lysosomes attracts cationic proteins within the cell.

β-Catenin Defines Head Versus Tail Identity During Planarian Regeneration and Homeostasis (18 January 2008)
K. A. Gurley, J. C. Rink, A. S. Alvarado
Smed-βcatenin-1 Is Required for Anteroposterior Blastema Polarity in Planarian Regeneration (18 January 2008)
C. P. Petersen and P. W. Reddien
After the head or tail of a planarian is severed, the signal intensity of a prominent developmental signaling pathway controls whether a new head or tail regenerates.

Dual Positive and Negative Regulation of Wingless Signaling by Adenomatous Polyposis Coli (18 January 2008)
C. M. Takacs et al.
An important developmental signaling molecule known to be a tumor suppressor can also activate growth, possibly explaining the responses of some cancers.

Centromeric Aurora-B Activation Requires TD-60, Microtubules, and Substrate Priming Phosphorylation (24 January 2008)
S. E. Rosasco-Nitcher, W. Lan, S. Khorasanizadeh, P. T. Stukenberg
A kinase that regulates chromosome segregation to daughter cells during metaphase is confined to the inner centromere through its interactions with other centromeric proteins.

The Frequency Dependence of Osmo-Adaptation in Saccharomyces cerevisiae (24 January 2008)
J. T. Mettetal, D. Muzzey, C. Gómez-Uribe, A. van Oudenaarden
Modeling the dynamics of the osmotic stress response in yeast reveals an unexpected, rapid nontranscriptional mechanism that may involve glycerol transport.
See related Perspective.


NEUROSCIENCE/PSYCHOLOGY

Ongoing in Vivo Experience Triggers Synaptic Metaplasticity in the Neocortex (4 January 2008)
R. L. Clem, T. Celikel, A. L. Barth
During continuous sensory stimulation, NMDA receptors in the mouse cortex switch from enhancing synaptic potentiation to opposing it.
See related Perspective.

Small Circuits for Large Tasks: High-Speed Decision-Making in Archerfish (4 January 2008)
T. Schlegel and S. Schuster
Archerfish shoot their insect prey with a stream of water and then use sensory information and just a few neurons to calculate how to retrieve their food.

The Limits of Counting: Numerical Cognition Between Evolution and Culture (11 January 2008)
S. Beller and A. Bender
Several Pacific-island languages with few words for numbers may be derived from more sophisticated and abstract counting systems rather than being their precursors.

Lhx2 Selector Activity Specifies Cortical Identity and Suppresses Hippocampal Organizer Fate (18 January 2008)
V. S. Mangale et al.
The brain’s cortex begins as a one-cell-thick sheet of stem cells, whose ultimate identity is specified by a gene that suppresses noncortical cell fates.
See related Perspective.


IMMUNOLOGY
 
Dendritic Cell-Induced Memory T Cell Activation in Nonlymphoid Tissues (11 January 2008)
L. M. Wakim, J. Waithman, N. van Rooijen, W. R. Heath, F. R. Carbone
Immune cells, normally produced in lymphoid organs, can also be activated in the nervous system in response to a viral challenge.

Recognition of a Ubiquitous Self Antigen by Prostate Cancer-Infiltrating CD8⁺ T Lymphocytes (11 January 2008)
P. A. Savage et al.
In mice, a common histone protein that coats DNA is unexpectedly detected within prostate tumors by the immune system, suggesting a potential therapeutic approach.
See related Perspective.

NFAT Binding and Regulation of T Cell Activation by the Cytoplasmic Scaffolding Homer Proteins (24 January 2008)
G. N. Huang et al.
Signals coming into the T cell are coordinated by two scaffolding proteins, which determine whether the cell will be activated or permanently shut down.


MEDICINE

Endothelial Progenitor Cells Control the Angiogenic Switch in Mouse Lung Metastasis (11 January 2008)
D. Gao et al.
Experiments in mice show that certain bone marrow cells promote the development of lung cancers by helping blood vessels form within the tumors.
See related Perspective.

Initiating and Cancer-Propagating Cells in TEL-AML1-Associated Childhood Leukemia (18 January 2008)
D. Hong et al.
Identical twins each carry preleukemic cells containing the characteristic chromosomal translocation, but only one undergoes further genetic changes and develops leukemia.


BIOCHEMISTRY

Designed Protein-Protein Association (11 January 2008)
D. Grueninger et al.
A few changes in the side chains of amino acids at the contact interfaces of natural enzymes may suffice to induce higher-order oligomers.
See related Perspective.

Effects of Molecular Memory and Bursting on Fluctuations in Gene Expression (18 January 2008)
J. M. Pedraza and J. Paulsson
A theory of stochastic gene expression suggests that noise can be modulated without feedback loops, complicating interpretation of single-cell experiments.


PLANT SCIENCE

Arabidopsis CLV3 Peptide Directly Binds CLV1 Ectodomain (18 January 2008)
M. Ogawa, H. Shinohara, Y. Sakagami, Y. Matsubayashi
Peptides that maintain the stem cells in the shoot apical meristem of Arabidopsis act by binding to the extracellular portion of a receptor-like kinase.

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
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.