Bio-Med Roundup

This month in Bio-Med Roundup:
  • Ehrsson and Lenggenhager et al. reported methods for inducing elements of an out-of-body experience in healthy volunteers.
  • Liu et al. and Brack et al. demonstrated a connection between augmented Wnt signaling and stem cell senescence and aging.
  • Clantin et al. and Kim et al. offered insights into the structures and transport of outer membrane proteins.
  • Fellay et al. identified immune gene variants that are associated with differences in viral load during the early stages of HIV infection.
Jump to:

 


This month’s Bio-Med Roundup is sponsored by:
The AAAS Member-Get-a-Member Program

No one knows the value of AAAS better than our members. That’s why we
are asking you to refer a friend or colleague to help AAAS do even more
to advance science and serve society. Bring in just one new member, and
receive a AAAS/Science umbrella. Three members equal a travel bag; five
members, a USB memory stick; 10 members, an iPod Shuffle; 50 members, a
trip for two to the AAAS Annual Meeting; 100 members, an iMac computer.

Start earning your rewards through our newest member benefit program. Go
to promo.aaas.org/mgam. For details, visit promo.aaas.org/mgamtc. Promotion ends 31 December 2008.




NEUROSCIENCE/PSYCHOLOGY
 
Defusing the Childhood Vocabulary Explosion (3 August 2007)
B. McMurray
Toddlers express a burst of new words as a result of their parallel acquisition of words of varying complexity, not because they acquire a new cognitive skill.

High-Speed Imaging Reveals Neurophysiological Links to Behavior in an Animal Model of Depression (10 August 2007)
R. D. Airan, L. A. Meltzer, M. Roy, Y. Gong, H. Chen, K. Deisseroth
Neural activity in the hippocampi of rats with depression-like symptoms reflects the degree of abnormal behavior, providing a clue to the brain circuits underlying depression.
See related Perspective.

Characterizing the Limits of Human Visual Awareness (10 August 2007)

L. Huang, A. Treisman, H. Pashler
Briefly examining a scene visually, humans can pay attention to only one color at a time but may be able to see it in multiple locations.

Spatial Regulation of an E3 Ubiquitin Ligase Directs Selective Synapse Elimination (17 August 2007)
M. Ding, D. Chao, G. Wang, K. Shen
In developing worms, the pruning of excess synapses requires proteosome-mediated protein degradation and is selectively prevented by a neural adhesion molecule.
See related Perspective.

Rapid Erasure of Long-Term Memory Associations in the Cortex by an Inhibitor of PKMζ (17 August 2007)
R. Shema, T. C. Sacktor, Y. Dudai
Even long after consolidation of a stable memory in rats, the activity of a particular protein kinase isoform is required in the cortex for its persistence.

When Fear Is Near: Threat Imminence Elicits Prefrontal–Periaqueductal Gray Shifts in Humans (24 August 2007)
D. Mobbs, P. Petrovic, J. L. Marchant, D. Hassabis, N. Weiskopf, B. Seymour, R. J. Dolan, C. D. Frith
Brain activity in fearful humans occurs in the cognitively advanced prefrontal cortex when the threat is far away but switches to the midbrain as the threat draws near.
See related Perspective.

Astrocytes Potentiate Transmitter Release at Single Hippocampal Synapses (24 August 2007)
G. Perea and A. Araque
Certain synapses strengthen upon coincident secretion of the neurotransmitter glutamate from a neighboring astrocyte, suggesting that astrocytes contribute to learning.

The Experimental Induction of Out-of-Body Experiences (24 August 2007)
H. H. Ehrsson
Visual and sensory stimuli that mimic subjects viewing themselves from a distance produced a center of awareness (or sense of self) outside their bodies.

Video Ergo Sum: Manipulating Bodily Self-Consciousness (24 August 2007)
B. Lenggenhager, T. Tadi, T. Metzinger, O. Blanke
Visual and sensory stimuli that mimic subjects viewing themselves from a distance produced a center of awareness (or sense of self) outside their bodies.

Localization of a Stable Neural Correlate of Associative Memory (31 August 2007)
L. G. Reijmers, B. L. Perkins, N. Matsuo, M. Mayford
The neurons activated in the amygdala when a mouse learns to fear a particular location are also activated when the mouse recalls that fear.


GENETICS

Genome Transplantation in Bacteria: Changing One Species to Another (3 August 2007)
C. Lartigue, J. I. Glass, N. Alperovich, R. Pieper, P. P. Parmar, C. A. Hutchison, III, H. O. Smith, J. C. Venter
The intact DNA genome was isolated from one Mycoplasma species and transferred to another, replacing the recipient’s genome and conferring its own phenotype.

Divergence of Transcription Factor Binding Sites Across Related Yeast Species (10 August 2007)
A. R. Borneman, T. A. Gianoulis, Z. D. Zhang, H. Yu, J. Rozowsky, M. R. Seringhaus, L. Y. Wang, M. Gerstein, M. Snyder
In yeast, gene regulatory elements evolve much more rapidly than the genes they control and so may be responsible for much of the diversity among species.
See related Perspective.

Human Genome Ultraconserved Elements Are Ultraselected (17 August 2007)
S. Katzman, A. D. Kern, G. Bejerano, G. Fewell, L. Fulton, R. K. Wilson, S. R. Salama, D. Haussler
Ultraconserved DNA sequences, unchanged in vertebrates for 300 million years, are maintained by selection four times as strong as that for coding genes.

A Whole-Genome Association Study of Major Determinants for Host Control of HIV-1 (17 August 2007)
J. Fellay, K. V. Shianna, D. Ge, S. Colombo, B. Ledergerber, M. Weale, K. Zhang, C. Gumbs, A. Castagna, A. Cossarizza et al.
A survey of the whole human genome identifies variants in immune genes that are associated with differences in viral load during the early stages of HIV infection.


CELL BIOLOGY

Quantitative Mass Spectrometry Identifies Insulin Signaling Targets in C. elegans (3 August 2007)
M.-Q. Dong, J. D. Venable, N. Au, T. Xu, S. K. Park, D. Cociorva, J. R. Johnson, A. Dillin, J. R. Yates, III
Identifying the genetic and protein targets of the insulin signaling athway in C. elegans reveals mechanisms that potentially control
the aging process.
See related Perspective.

Forced Unfolding of Proteins Within Cells (3 August 2007)
C. P. Johnson, H.-Y. Tang, C. Carag, D. W. Speicher, D. E. Discher
Fluorescent labeling of cysteines in living cells reveals how mechanical stress can cause force-induced conformational changes in cellular proteins.

Augmented Wnt Signaling in a Mammalian Model of Accelerated Aging (10 August 2007)
H. Liu, M. M Fergusson, R. M. Castilho, J. Liu, L. Cao, J. Chen, D. Malide, I. I. Rovira, D. Schimel, C. J. Kuo et al.
Increased Wnt Signaling During Aging Alters Muscle Stem Cell Fate and Increases Fibrosis (10 August 2007)
A. S. Brack, M. J. Conboy, S. Roy, M. Lee, C. J. Kuo, C. Keller, T. A. Rando
In older mice, overexpression of a signaling pathway may inhibit muscle regeneration by accelerating stem cell senescence while decreasing their proliferation.

Effects of Aneuploidy on Cellular Physiology and Cell Division in Haploid Yeast (17 August 2007)
E. M. Torres, T. Sokolsky, C. M. Tucker, L. Y. Chan, M. Boselli, M. J. Dunham, A. Amon
Yeast cells containing any extra chromosome all exhibit a similar phenotype despite the presence of supernumerary genes.
See related Perspective.

Detection of Near-Atmospheric Concentrations of CO2 by an Olfactory Subsystem in the Mouse (17 August 2007)
J. Hu, C. Zhong, C. Ding, Q. Chi, A. Walz, P. Mombaerts, H. Matsunami, M. Luo
Mice can sense near-atmospheric concentrations of CO2 using a subset of olfactory neurons that may utilize the catabolic enzyme carbonic anhydrase.


BIOCHEMISTRY/STRUCTURAL BIOLOGY
 

Mechanism of Na+/H+ Antiporting (10 August 2007)
I. T. Arkin, H. Xu, M. Ø. Jensen, E. Arbely, E. R. Bennett, K. J. Bowers, E. Chow, R. O. Dror, M. P. Eastwood, R. Flitman-Tene et al.
Molecular dynamics simulations of a Na+/H+ antiporter allow the proposal of an atomically detailed model for the mechanism of ion transport, pH regulation, and cation selectivity.

Structure of the Membrane Protein FhaC: A Member of the Omp85-TpsB Transporter Superfamily (17 August 2007)
B. Clantin, A.-S. Delattre, P. Rucktooa, N. Saint, A. C. Méli, C. Locht, F. Jacob-Dubuisson, V. Villeret

Structure and Function of an Essential Component of the Outer Membrane Protein Assembly Machine (17 August 2007)
S. Kim, J. C. Malinverni, P. Sliz, T. J. Silhavy, S. C. Harrison, D. Kahne
Two structures of bacterial outer membrane proteins reveal how the polypeptide transport–associated domain can bind and transport diverse cellular proteins.
See related Perspective.

Anatomy and Dynamics of a Supramolecular Membrane Protein Cluster (24 August 2007)
J. J. Sieber, K. I. Willig, C. Kutzner, C. Gerding-Reimers, B. Harke, G. Donnert, B. Rammner, C. Eggeling, S. W. Hell, H. Grubmüller, T. Lang
Clusters of about 75 molecules of the membrane protein syntaxin result from weak attraction among the proteins balanced by steric repulsion induced by crowding.
See related Perspective.

Domain Architecture of Pyruvate Carboxylase, a Biotin-Dependent Multifunctional Enzyme (24 August 2007)
M. St. Maurice, L. Reinhardt, K. H. Surinya, P. V. Attwood, J. C. Wallace, W. W. Cleland, I. Rayment
Biotin activation of the enzyme pyruvate carboxylase decreases the distance between the two active sites, facilitating the transfer of a carboxyl group from one to the other.

Replication Origin Recognition and Deformation by a Heterodimeric Archaeal Orc1 Complex (31 August 2007)
E. L. C. Dueber, J. E. Corn, S. D. Bell, J. M. Berger
Structural Basis of DNA Replication Origin Recognition by an ORC Protein (31 August 2007)
M. Gaudier, B. S. Schuwirth, S. L. Westcott, D. B. Wigley
The DNA-bound structures of two protein factors that initiate DNA replication in archaea show how they dramatically deform the DNA duplex, priming it for unwinding.
See related Perspective.

Structure of a Tyrosine Phosphatase Adhesive Interaction Reveals a Spacer-Clamp Mechanism (31 August 2007)
A. R. Aricescu, C. Siebold, K. Choudhuri, V. T. Chang, W. Lu, S. J. Davis, P. A. van der Merwe, E. Y. Jones
Between adhering cells, pairs of tyrosine phosphatases, one protruding from each cell and equal in length to the space between them, position each phosphatase near its substrate.


IMMUNOLOGY
 

Monitoring of Blood Vessels and Tissues by a Population of Monocytes with Patrolling Behavior (3 August 2007)
C. Auffray, D. Fogg, M. Garfa, G. Elain, O. Join-Lambert, S. Kayal, S. Sarnacki, A. Cumano, G. Lauvau, F. Geissmann
Immune cells that reside in endothelial tissues remain attached to the walls of blood vessels and survey for signs of damage and infection.

Regulation of Homeostatic Chemokine Expression and Cell Trafficking During Immune Responses (3 August 2007)
S. N. Mueller, K. A. Hosiawa-Meagher, B. T. Konieczny, B. M. Sullivan, M. F. Bachmann, R. M. Locksley, R. Ahmed, M. Matloubian
During the immune response to a pathogen, lymph nodes temporarily block the entry of new immune cells, thereby optimizing the ongoing immune reaction.

Negative Regulation of Toll-Like Receptor Signaling by NF-κB p50 Ubiquitination Blockade (3 August 2007)
R. J. Carmody, Q. Ruan, S. Palmer, B. Hilliard, Y. H. Chen
In mice, the innate immune response to microbes is controlled by blocking degradation of a transcriptional inhibitor, dampening an otherwise potentially dangerous response.

Immune-like Phagocyte Activity in the Social Amoeba (3 August 2007)
G. Chen, O. Zhuchenko, A. Kuspa
The sluglike assemblies formed by social amoebae contain specialized cells that function like the phagocytes of animal immune systems, suggesting an evolutionary connection.

Immunization by Avian H5 Influenza Hemagglutinin Mutants with Altered Receptor Binding Specificity (10 August 2007)
Z.-Y. Yang, C.-J. Wei, W.-P. Kong, L. Wu, L. Xu, D. F. Smith, G. J. Nabel
Mutations in a surface protein of the avian flu virus affect how it binds to host cells, information that can help generate protective vaccines for evolving flu viruses.


MOLECULAR BIOLOGY

CHD1 Motor Protein Is Required for Deposition of Histone Variant H3.3 into Chromatin in Vivo (24 August 2007)
A. Y. Konev, M. Tribus, S. Y. Park, V. Podhraski, C. Y. Lim, A. V. Emelyanov, E. Vershilova, V. Pirrotta, J. T. Kadonaga, A. Lusser, D. V. Fyodorov
A motor protein known to remodel chromatin is also required for histone assembly on the paternal genome during early development in Drosophila.

A MicroRNA Feedback Circuit in Midbrain Dopamine Neurons (31 August 2007)
J. Kim, K. Inoue, J. Ishii, W. B. Vanti, S. V. Voronov, E. Murchison, G. Hannon, A. Abeliovich
MicroRNAs are required for the maturation and function of midbrain dopamine neurons, and loss of a particular miRNA may underlie Parkinson’s disease.
See related Perspective.

Cap-Independent Translation Is Required for Starvation-Induced Differentiation in Yeast (31 August 2007)
W. V. Gilbert, K. Zhou, T. K. Butler, J. A. Doudna
Upon starvation, instead of translating mRNA from one end to the other, yeast translate some mRNAs from internal entry sites, generating an invasive growth phenotype.

Strand-Biased Spreading of Mutations During Somatic Hypermutation (31 August 2007)
S. Unniraman and D. G. Schatz
The mutations that underlie antibody diversity are created by error-prone DNA repair triggered in the nontemplate DNA strand but not in the template strand.


MICROBIOLOGY
 

Adaptive Mutations in Bacteria: High Rate and Small Effects (10 August 2007)
L. Perfeito, L. Fernandes, C. Mota, I. Gordo
The beneficial mutation rate for bacteria appears to be 1000-fold greater than classical estimates.

Blue-Light–Activated Histidine Kinases: Two-Component Sensors in Bacteria (24 August 2007)
T. E. Swartz, T.-S. Tseng, M. A. Frederickson, G. Paris, D. J. Comerci, G. Rajashekara, J.-G. Kim, M. B. Mudgett, G. A. Splitter, R. A. Ugalde et al.
A light-activated enzyme with a flavin chromophore is found in several bacterial species, and in one of these it regulates light-stimulated macrophage infection.
See related Perspective.

Temporal Fragmentation of Speciation in Bacteria (24 August 2007)
A. C. Retchless and J. G. Lawrence
Unlike eukaryotes, bacteria can be considered to form new species when lineage-specific genes no longer recombine, long before recombination at other genes ceases completely.


PLANT SCIENCE
 

The FERONIA Receptor-like Kinase Mediates Male-Female Interactions During Pollen Tube Reception (3 August 2007)
J.-M. Escobar-Restrepo, N. Huck, S. Kessler, V. Gagliardini, J. Gheyselinck, W.-C. Yang, U. Grossniklaus
In plants, a female-specific kinase senses the arrival of the pollen tube, setting the stage for the next stages of fertilization and potentially controlling reproductive compatibility.
See related Perspective.

The Evolution of Selfing in Arabidopsis thaliana (24 August 2007)
C. Tang, C. Toomajian, S. Sherman-Broyles, V. Plagnol, Y.-L. Guo, T. T. Hu, R. M. Clark, J. B. Nasrallah, D. Weigel, M. Nordborg
An analysis of sex genes shows that at several times throughout its history—-including about 1 million years ago—-Arabidopsis has developed the ability to self-fertilize.


This month’s Bio-Med Roundup is sponsored by:
The AAAS Member-Get-a-Member Program

No one knows the value of AAAS better than our members. That’s why we
are asking you to refer a friend or colleague to help AAAS do even more
to advance science and serve society. Bring in just one new member, and
receive a AAAS/Science umbrella. Three members equal a travel bag; five
members, a USB memory stick; 10 members, an iPod Shuffle; 50 members, a
trip for two to the AAAS Annual Meeting; 100 members, an iMac computer.

Start earning your rewards through our newest member benefit program. Go
to promo.aaas.org/mgam. For details, visit promo.aaas.org/mgamtc. Promotion ends 31 December 2008.