Bio-Med Roundup

This month in Bio-Med Roundup:
  • Morrow et al. identified genes associated with susceptibility to autism by studying families in which parents share ancestors.
  • Bass et al. investigated the neural circuitry underlying vertebrate vocal abilities.
  • Shima et al. resolved the structure of a novel hydrogenase enzyme, thus providing insight into how molecular hydrogen can be activated for use in biological processes.
  • Guang et al. identified a protein that shuttles small regulatory RNA molecules into the nucleus, where they participate in RNA-based nuclear silencing.
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BIOCHEMISTRY
 
Myosin I Can Act As a Molecular Force Sensor (4 July 2008)
J. M. Laakso, J. H. Lewis, H. Shuman, E. M. Ostap
Myosin I, a motor protein that plays a role in hearing, is a sensitive tension sensor, reacting to small loads (less than 2 picoNewtons) by binding for much longer times to actin.

Micelles Protect Membrane Complexes from Solution to Vacuum (11 July 2008)
N. P. Barrera, N. Di Bartolo, P. J. Booth, C. V. Robinson
Gas-phase lipid micelles protect a large complex of membrane proteins, allowing its subunit composition and ligand binding to be assessed by mass spectrometry.

Structural Basis of Trans-Inhibition in a Molybdate/Tungstate ABC Transporter (11 July 2008)
S. Gerber, M. Comellas-Bigler, B. A. Goetz, K. P. Locher
A class of membrane transporters is subject to product inhibition:The imported substrate binds to a regulatory domain that sterically inhibits further ATP hydrolysis.

The High-Affinity E. coli Methionine ABC Transporter: Structure and Allosteric Regulation (11 July 2008)
N. S. Kadaba, J. T. Kaiser, E. Johnson, A. Lee, D. C. Rees
The structure of the methionine transporter illustrates how increased levels of methionine stabilize an inactive state to inhibit further translocation.

Structural Basis for Specific Substrate Recognition by the Chloroplast Signal Recognition Particle Protein cpSRP43 (11 July 2008)
K. F. Stengel et al.
A protein subunit of the signal recognition particle that directs chlorophyll binding proteins to the chloroplast replaces RNA and causes posttranslational function.

ERdj5 Is Required as a Disulfide Reductase for Degradation of Misfolded Proteins in the ER (25 July 2008)
R. Ushioda et al.
A disulfide reductase found in the endoplasmic reticulum cleaves the disulfide bonds of misfolded proteins so they can be transported into the cytoplasm for degradation.
See related Perspective.

The Crystal Structure of [Fe]-Hydrogenase Reveals the Geometry of the Active Site (25 July 2008)
S. Shima et al.
Three hydrogenases that evolved independently exhibit similar features in their active sites, yielding clues for designing catalysts in hydrogen fuel cells.
See related Perspective.


NEUROSCIENCE

The Spread of Ras Activity Triggered by Activation of a Single Dendritic Spine (4 July 2008)
C. D. Harvey, R. Yasuda, H. Zhong, K. Svoboda
When strengthened, individual synapses on dendritic spines contain an activated small regulatory protein that spreads to nearby spines, possibly altering their sensitivity.

Finite Scale of Spatial Representation in the Hippocampus (4 July 2008)
K. B. Kjelstrup et al.
The rat hippocampus provides a representation of the animal’s entire spatial environment, coding distances up to 1 meter away in the dorsal region and up to 15 meters at the ventral tip.
See related Perspective.

Identification of SLEEPLESS, a Sleep-Promoting Factor (18 July 2008)
K. Koh et al.
A search for genetic modulators of sleep in Drosophila identified a gene encoding a brain protein that is likely secreted and is required for recovery from sleep deprivation.

Bottom-Up Dependent Gating of Frontal Signals in Early Visual Cortex (18 July 2008)
L. B. Ekstrom, P. R. Roelfsema, J. T. Arsenault, G. Bonmassar, W. Vanduffel
Higher brain centers can modulate activity in the cortical regions that directly receive visual input, but only when a visual stimulus is present.

Evolutionary Origins for Social Vocalization in a Vertebrate Hindbrain–Spinal Compartment (18 July 2008)
A. H. Bass, E. H. Gilland, R. Baker
The conserved neural circuitry for vocal communication in fish and other tetrapods suggests that this function may have originated prior to the evolution of bony vertebrates.
See related Perspective.

Orbitofrontal Dysfunction in Patients with Obsessive-Compulsive Disorder and Their Unaffected Relatives (18 July 2008)
S. R. Chamberlain et al.
The abnormally low activation in the frontal cortex of individuals with obsessive compulsive disorder and their close relatives may confer a risk for the disease.


CELL/DEVELOPMENTAL BIOLOGY

Autophagy Is Essential for Preimplantation Development of Mouse Embryos (4 July 2008)
S. Tsukamoto et al.
As fertilized mouse eggs develop into embryos and maternal proteins are eliminated, the degradative process of autophagy is required for proper growth.

Robust, Tunable Biological Oscillations from Interlinked Positive and Negative Feedback Loops (4 July 2008)
T. Y.-C. Tsai et al.
Analysis of known and theoretical oscillatory circuits in cells shows that those with both negative and positive feedback are more robust and allow frequency control independent of amplitude.

Four-jointed Is a Golgi Kinase That Phosphorylates a Subset of Cadherin Domains (18 July 2008)
H. O. Ishikawa, H. Takeuchi, R. S. Haltiwanger, K. D. Irvine
A newly described type of protein kinase found in the Golgi phosphorylates signaling proteins on amino acids that are destined to be within extracellular domains.

Signal-Mediated Dynamic Retention of Glycosyltransferases in the Golgi (18 July 2008)
L. Tu, W. C. S. Tai, L. Chen, D. K. Banfield
Glycosyltransferase enzymes stay in the Golgi in the face of continuing membrane traffic because a receptor links their cytoplasmic tails to a recycling coated vesicle.

Riboswitches in Eubacteria Sense the Second Messenger Cyclic Di-GMP (18 July 2008)
N. Sudarsan et al.
The bacterial second messenger cyclic di–guanosine monophosphate controls a wide variety of cellular functions by acting on a riboswitch motif in numerous messenger RNAs.

Eco1-Dependent Cohesin Acetylation During Establishment of Sister Chromatid Cohesion (25 July 2008)
T. Rolef Ben-Shahar et al.
A Molecular Determinant for the Establishment of Sister Chromatid Cohesion (25 July 2008)
E. Ünal et al.
The pairing of newly replicated chromatids—essential for accurate cell division—is promoted by acetylation of one subunit of the protein cohesin by another subunit.

BSKs Mediate Signal Transduction from the Receptor Kinase BRI1 in Arabidopsis (25 July 2008)
W. Tang et al.
When a plant membrane receptor is activated by a steroid hormone, two kinases are phosphorylated that ultimately regulate gene expression and development.


IMMUNOLOGY

Modulation of Gene Expression via Disruption of NF-κB Signaling by a Bacterial Small Molecule (11 July 2008)
V. V. Kravchenko et al.
A small molecule produced by common pathogenic bacterium inhibits the activity of a key immune transcription factor.

Anomalous Type 17 Response to Viral Infection by CD8+ T Cells Lacking T-bet and Eomesodermin (18 July 2008)
A. M. Intlekofer et al.
Two transcription factors cooperate to ensure the correct functioning of CD8+ T cells during the response to infection.


GENETICS
 
Phylogenetic Signal in the Eukaryotic Tree of Life (4 July 2008)
M. J. Sanderson
A survey of sequences in GenBank, which represent about 10 percent of described species, shows that the patchy distribution of data is insufficient to build a eukaryotic tree of life.

Identifying Autism Loci and Genes by Tracing Recent Shared Ancestry (11 July 2008)
E. M. Morrow et al.
A genetic analysis of autism in closely related individuals suggests that defects in proteins that control neural activity may produce this cognitive disorder.
See related Perspective.

Genetic Determinants of Self Identity and Social Recognition in Bacteria (11 July 2008)
K. A. Gibbs, M. L. Urbanowski, E. P. Greenberg
The ability of clones of a pathogenic bacterium to distinguish themselves from one another resides in a six-gene locus with interrelated recognition functions.


MEDICINE

Sporadic Autonomic Dysregulation and Death Associated with Excessive Serotonin Autoinhibition (4 July 2008)
E. Audero et al.
In young mice, expression of higher than normal levels of a type of serotonin receptor causes sporadic death with features reminiscent of sudden infant death syndrome.

Drug Target Identification Using Side-Effect Similarity (11 July 2008)
M. Campillos, M. Kuhn, A.-C. Gavin, L. J. Jensen, P. Bork
By finding drugs that share similar side effects, several new drug targets were predicted and experimentally confirmed, suggesting a route to identifying new therapeutic agents.


MOLECULAR BIOLOGY

An Argonaute Transports siRNAs from the Cytoplasm to the Nucleus (25 July 2008)
S. Guang et al.
A protein similar to one that binds small cytoplasmic RNAs transports small RNAs into the nucleus, where they participate in RNA-based nuclear silencing processes.
See related Perspective.

DNA Events Manipulating the Metazoan Mitochondrial Genome with Targeted Restriction Enzymes (25 July 2008)
H. Xu, S. Z. DeLuca, P. H. O’Farrell
Flies with mutant mitochondria—generated by introduction of restriction enzymes—show many of the same phenotypes as humans with mitochondrial mutations.


SOCIOLOGY

Electronic Publication and the Narrowing of Science and Scholarship (18 July 2008)
J. A. Evans
As journals become available electronically, scientists and scholars have more articles at their fingertips but cite relatively fewer, and these tend to be more recent.


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