Bio-Med Roundup

This month in Bio-Med Roundup:
  • Liu et al. showed that a drug for controlling cholesterol may be useful as an antibiotic for multidrug-resistant Staphylococcus aureus.
  • Mongillo et al. proposed a new neural mechanism of working memory that is based on plasticity in synaptic connections.
  • Bashor et al. introduced new regulatory properties into a yeast signaling pathway by engineering a key scaffolding protein.
  • Coop et al. and Kong et al. examined variation in the rates and patterns of genome-wide recombination among humans.
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GENETICS
 
High-Resolution Mapping of Crossovers Reveals Extensive Variation in Fine-Scale Recombination Patterns Among Humans (7 March 2008)
G. Coop, X. Wen, C. Ober, J. K. Pritchard, M. Przeworski
High-density genotyping of individuals from 82 families shows unexpected variation in the number of meiotic crossovers and in the relative activity of recombination hotspots.

Sequence Variants in the RNF212 Gene Associate with Genome-Wide Recombination Rate (7 March 2008)
A. Kong et al.
A variant of a human gene associated with high rates of recombination in males and low rates in females is an ortholog of a nematode gene essential for recombination.

A Retrotransposon-Mediated Gene Duplication Underlies Morphological Variation of Tomato Fruit (14 March 2008)
H. Xiao, N. Jiang, E. Schaffner, E. J. Stockinger, E. van der Knaap
The gene causing elongated tomatoes arose from an unusual, transposon-mediated duplication that provided a new regulatory environment that increased its expression.

Evidence for Karyogamy and Exchange of Genetic Material in the Binucleate Intestinal Parasite Giardia intestinalis (14 March 2008)
M. K. Poxleitner et al.
The unusual lack of accumulated mutations in asexual Giardia can be explained by the exchange of plasmid DNA between its two nuclei during the cyst phase.



MEDICINE

Neurokinin 1 Receptor Antagonism as a Possible Therapy for Alcoholism (14 March 2008)
D. T. George et al.
A drug that inhibits a neural signaling pathway linked to behavioral stress may be a useful therapy in preventing relapse in alcoholics.

TDP-43 Mutations in Familial and Sporadic Amyotrophic Lateral Sclerosis (21 March 2008)
J. Sreedharan et al.
Mutations in a gene that encodes a protein that aggregates in several neurodegenerative disorders are linked to amyotrophic lateral sclerosis (Lou Gehrig’s disease).

Oncogenic CARD11 Mutations in Human Diffuse Large B Cell Lymphoma (21 March 2008)
G. Lenz et al.
One type of non-Hodgkin’s lymphoma is caused by mutations in a scaffolding protein that inappropriately activate an inflammatory signaling pathway.


MICROBIOLOGY

A Cholesterol Biosynthesis Inhibitor Blocks Staphylococcus aureus Virulence (7 March 2008)
C.-I. Liu et al.
A drug for controlling cholesterol may be useful as an antibiotic for multi–drug-resistant Staphylococcus because of unexpected structural similarities among critical proteins.

Coiled-Coil Irregularities and Instabilities in Group A Streptococcus M1 Are Required for Virulence (7 March 2008)
C. McNamara et al.
Mutating a cell-surface virulence protein on strep bacteria stabilizes its structure, minimizing its inflammatory side effects and potentially making it a better vaccine.

Direct Visualization of Horizontal Gene Transfer (14 March 2008)
A. Babic, A. B. Lindner, M. Vulic, E. J. Stewart, M. Radman
Visualization of DNA exchange between two bacteria reveals that the process is highly efficient, is mediated by the pilus, and occurs about once per replication cycle.

A Nitric Oxide–Inducible Lactate Dehydrogenase Enables Staphylococcus aureus to Resist Innate Immunity (21 March 2008)
A. R. Richardson, S. J. Libby, F. C. Fang
Staphylococcus aureus
is a particularly successful pathogen because it responds to antimicrobial defenses of its host by producing more lactate to maintain its redox balance.


NEUROSCIENCE

Synaptic Theory of Working Memory (14 March 2008)
G. Mongillo, O. Barak, M. Tsodyks
Stronger synapses induced by calcium currents are responsible for working memory rather than the more metabolically expensive action potential firing, as had been thought.
See related Perspective.

Pattern Separation in the Human Hippocampal CA3 and Dentate Gyrus (21 March 2008)
A. Bakker, C. B. Kirwan, M. Miller, C. E. L. Stark
High-resolution imaging of the human brain reveals that, as seen in rodents, recognition of small differences in similar memories requires a particular region of the hippocampus.
See related Perspective.

Drosophila Egg-Laying Site Selection as a System to Study Simple Decision-Making Processes (21 March 2008)
C. Yang, P. Belawat, E. Hafen, L. Y. Jan, Y.-N. Jan
Experiments show how flies make complex decisions when laying eggs, choosing surfaces containing sucrose only when other options are not available.

Protein Synthesis and Neurotrophin-Dependent Structural Plasticity of Single Dendritic Spines (21 March 2008)
J. Tanaka et al.
Pairing of stimuli in hippocampal cells induces secretion of the growth factor BDNF, causing enlargement of individual spines and strengthening of synapses.
See related Perspective.

Insect Odorant Receptors Are Molecular Targets of the Insect Repellent DEET (28 March 2008)
M. Ditzen, M. Pellegrino, L. B. Vosshall
The widely used insect repellent DEET acts by inhibiting olfactory neurons that respond to odors such as those that attract insects to their hosts.

Aversive Learning Enhances Perceptual and Cortical Discrimination of Indiscriminable Odor Cues (28 March 2008)
W. Li, J. D. Howard, T. B. Parrish, J. A. Gottfried
After association of negative stimuli to one of a pair of initially indistinguishable odors, human participants learn to tell the two odors apart and show altered brain representations.

Electric Fields Due to Synaptic Currents Sharpen Excitatory Transmission (28 March 2008)
S. Sylantyev et al.
The electrical field set up by currents within the synaptic cleft can influence diffusion of negatively charged neurotransmitters, such as glutamate, and prolong excitatory events.

Rule Learning by Rats (28 March 2008)
R. A. Murphy, E. Mondragón, V. A. Murphy
Rats can learn the rules governing simple sequences of stimuli and then unexpectedly can generalize these rules to new situations.


PSYCHOLOGY
 

Antisocial Punishment Across Societies (7 March 2008)
B. Herrmann, C. Thöni, S. Gächter
Retaliation against those who enforce the social norms of civic cooperation and rule of law varies among cultures and is more pronounced where social norms are weaker.
See related Perspective.

Preparing and Motivating Behavior Outside of Awareness (21 March 2008)
H. Aarts, R. Custers, H. Marien
Encouraging words flashed on a screen so briefly that they are only perceived unconsciously can, nevertheless, increase the effort put into a subsequent test of strength.

Spending Money on Others Promotes Happiness (21 March 2008)
E. W. Dunn, L. B. Aknin, M. I. Norton
A survey, a study of windfall spending, and a lab experiment all indicate that spending money on others results in more happiness than does spending money on oneself.


CELL BIOLOGY

Hepatic Glucose Sensing via the CREB Coactivator CRTC2 (7 March 2008)
R. Dentin, S. Hedrick, J. Xie, J. Yates III, M. Montminy
Competing glycosylation and phosphorylation of a single amino acid in a transcriptional coactivator regulate nutrient- and energy-sensing pathways and may contribute to diabetes.
See related Perspective.

Using Engineered Scaffold Interactions to Reshape MAP Kinase Pathway Signaling Dynamics (14 March 2008)
C. J. Bashor, N. C. Helman, S. Yan, W. A. Lim
A yeast signaling pathway acquires new regulatory properties (such as adaptation) when additional protein-protein interaction sites are engineered into a scaffolding protein.
See related Perspective.

Activation of FOXO1 by Cdk1 in Cycling Cells and Postmitotic Neurons (21 March 2008)
Z. Yuan et al.
A cell cycle–associated kinase phosphorylates the transcription factor FOXO1, which activates transcription of a regulator of mitosis.


BIOCHEMISTRY/STRUCTURAL BIOLOGY

De Novo Computational Design of Retro-Aldol Enzymes (7 March 2008)
L. Jiang et al.
A computationally designed enzyme acts as a retro-aldolase that splits a carbon-carbon bond in a nonnatural substrate.

Amyloid Fibrils of the HET-s(218–289) Prion Form a β Solenoid with a Triangular Hydrophobic Core (14 March 2008)
C. Wasmer et al.
A structural model of a yeast prion shows that the amyloid fibrils form a left-handed β solenoid stabilized by hydrophobic and polar interactions and salt bridges.

The Flavivirus Precursor Membrane-Envelope Protein Complex: Structure and Maturation (28 March 2008)
L. Li et al.
Structure of the Immature Dengue Virus at Low pH Primes Proteolytic Maturation (28 March 2008)
I-M. Yu et al.
Dengue and West Nile viruses mature when the envelope protein precursor is cleaved at low pH, and then the cleavage product dissociates outside the cell, allowing infection.


MOLECULAR BIOLOGY

TOPLESS Mediates Auxin-Dependent Transcriptional Repression During Arabidopsis Embryogenesis (7 March 2008)
H. Szemenyei, M. Hannon, J. A. Long
A transcriptional co-repressor is part of the protein complex that inhibits developmental gene activation in Arabidopsis until the growth hormone auxin triggers its degradation.

Nutritional Control of Reproductive Status in Honeybees via DNA Methylation (28 March 2008)
R. Kucharski, J. Maleszka, S. Foret, R. Maleszka
Epigenetic modifications that involve methylation cause female honeybee larvae to become queens rather than workers when they are fed royal jelly.