Bio-Med Roundup

This month in Bio-Med Roundup:
  • Teixeiro et al. and Bannard et al. shed light on how the distinct subsets of T cells that mediate acute versus long-term protection to infection can arise from a single precursor.
  • McMeniman et al. found that infection of the mosquito vector of dengue with the Wolbachia bacterium, shortens the mosquitoes’ lives and reduces disease transmission.
  • Giraudo et al. and Maximov et al. revealed new insight into the role of the protein complexin during membrane fusion.
  • Mihola et al. and Phadnis et al. identified genes in the mouse and fruit fly that cause hybrid sterility -- an important isolating mechanism in the formation of new species.
Jump to:
Sponsored by:



 CELL/DEVELOPMENTAL BIOLOGY
 
Signal Sequences Activate the Catalytic Switch of SRP RNA (2 January 2009)
N. Bradshaw, S. B. Neher, D. S. Booth, P. Walter
Newly made proteins destined to be inserted into membranes trigger an RNA switch that promotes initiation of this process.

Drosophila Stem Cells Share a Common Requirement for the Histone H2B Ubiquitin Protease Scrawny (9 January 2009)
M. Buszczak, S. Paterno, A. C. Spradling
Stem cells in the germ line, epithelium, and intestine all require a particular modification of histone H2B to repress key differentiation genes and maintain pluripotency.
See related Perspective.

The Aryl Hydrocarbon Nuclear Translocator Alters CD30-Mediated NF-κB–Dependent Transcription (9 January 2009)
C. W. Wright and C. S. Duckett
Signals from a cancer-associated receptor that activate a key pathway in the immune system are modulated by its binding to a stress-responsive transcription factor.

HDAC4 Regulates Neuronal Survival in Normal and Diseased Retinas (9 January 2009)
B. Chen and C. L. Cepko
An enzyme that deacetylates histones in the nucleus also functions in the cytoplasm to promote the survival of retinal neurons in mice.

Electron Cryomicroscopy of E. coli Reveals Filament Bundles Involved in Plasmid DNA Segregation (23 January 2009)
J. Salje, B. Zuber, J. Löwe
The actin-like filaments that power movement of DNA during bacterial cell division form small bundles of three to five filaments near the nucleoid.
See related Perspective.

Alternative Zippering as an On-Off Switch for SNARE-Mediated Fusion (23 January 2009)
C. G. Giraudo et al.
A structural motif in the protein complexin may act as a switch during membrane fusion.
See related Review.

Complexin Controls the Force Transfer from SNARE Complexes to Membranes in Fusion (23 January 2009)
A. Maximov, J. Tang, X. Yang, Z. P. Pang, T. C. Südhof
The protein complexin may act as a force-transferring switch during membrane fusion.
See related Review.

The Sphingolipid Transporter Spns2 Functions in Migration of Zebrafish Myocardial Precursors (23 January 2009)
A. Kawahara et al.
Normal heart development in zebrafish requires the function of a lipid transporter in a membrane surrounding the yolk, a tissue outside of the embryo proper. 

Mechanically Activated Integrin Switch Controls α5β1 Function (30 January 2009)
J. C. Friedland, M. H. Lee, D. Boettiger
Myosin contraction and extracellular matrix stiffness drive a tension-induced cell-surface integrin switch that regulates cell signaling.
See related Perspective.

A Human Telomerase Holoenzyme Protein Required for Cajal Body Localization and Telomere Synthesis (30 January 2009)
A. S. Venteicher et al.
Telomerase Cajal body protein 1 (TCAB1) is the fourth discovered subunit of the chromosome end-capping enzyme telomerase.


GENETICS

A Mouse Speciation Gene Encodes a Meiotic Histone H3 Methyltransferase (16 January 2009)
O. Mihola, Z. Trachtulec, C. Vlcek, J. C. Schimenti, J. Forejt
A gene responsible for sterility in the offspring of two mouse species, and therefore important in speciation, regulates gene expression via methylation in chromation.
See related Perspective.

A Single Gene Causes Both Male Sterility and Segregation Distortion in Drosophila Hybrids (16 January 2009)
N. Phadnis and H. A. Orr
A Drosophila gene that causes sterility in the offspring of two species and may be important for speciation causes increased transmission of itself to progeny. 
See related Perspective.

The Dynamics and Time Scale of Ongoing Genomic Erosion in Symbiotic Bacteria (16 January 2009)
N. A. Moran, H. J. McLaughlin, R. Sorek
Comparisons of strains of obligate symbionts reveal stepwise evolutionary changes leading to gene inactivation and DNA loss.

A Polymorphism in npr-1 Is a Behavioral Determinant of Pathogen Susceptibility in C. elegans (16 January 2009)
K. C. Reddy, E. C. Andersen, L. Kruglyak, D. H. Kim
Mutations in neuropeptide receptors prevent nematode worms from swimming away to avoid bacterial pathogens.

Genetic Interactions Between Transcription Factors Cause Natural Variation in Yeast (23 January 2009)
J. Gerke, K. Lorenz, B. Cohen
Adaptive differences in yeast sporulation arise from single-nucleotide mutations in transcription factors regulating sex.

Divergent Evolution of Duplicate Genes Leads to Genetic Incompatibilities Within A. thaliana (30 January 2009)
D. Bikard et al.
The divergent evolution of a duplicated gene results in genetic incompatibilities between strains of the plant Arabidopsis.


BIOCHEMISTRY

Real-Time DNA Sequencing from Single Polymerase Molecules (2 January 2009)
J. Eid et al.
Arrays of narrow waveguides can record the action of a DNA polymerase stepping along a primer template, potentially providing a way to sequence DNA molecules. 

Structure of a Type IV Secretion System Core Complex (9 January 2009)
R. Fronzes et al.
The structure of a bacterial secretion complex suggests how Gram-negative bacteria might regulate the transfer of certain virulence factors. 

The Structure of Rat Liver Vault at 3.5 Angstrom Resolution (16 January 2009)
H. Tanaka et al.
The large, ribonucleotide proteins involved in resisting infection have domains that bind to lipid-raft regions of the cell membrane. 

Survival from Hypoxia in C. elegans by Inactivation of Aminoacyl-tRNA Synthetases a (30 January 2009)
L. L. Anderson, X. Mao, B. A. Scott, C. Crowder
Reduced activity of aminoacyl-transfer RNA synthetases allows for survival from hypoxic insult in the nematode C. elegans.

Ligand-Dependent Equilibrium Fluctuations of Single Calmodulin Molecules (30 January 2009)
J. P. Junker, F. Ziegler, M. Rief
Single-molecule force spectroscopy reveals the equilibrium dynamics of calmodulin folding and how it is modulated by peptide ligands.
See related Perspective.

Stretching Single Talin Rod Molecules Activates Vinculin Binding (30 January 2009)
A. del Rio et al.
Force-induced stretching of proteins can expose previous cryptic binding sites and promote binding to their ligands.
See related Perspective.


MICROBIOLOGY/VIROLOGY

Phage-Mediated Intergeneric Transfer of Toxin Genes (2 January 2009)
J. Chen and R. P. Novick
Viruses may transfer toxin genes among pathogenic bacteria in raw milk, complicating veterinary use of phage therapy as a bacteriacide. 

Stable Introduction of a Life-Shortening Wolbachia Infection into the Mosquito Aedes aegypti (2 January 2009)
C. J. McMeniman et al.
Infection of mosquitoes with a bacterium shortens their lives and reduces disease transmission, without development of resistance.
See related Perspective.

AMPylation of Rho GTPases by Vibrio VopS Disrupts Effector Binding and Downstream Signaling (9 January 2009)
M. L. Yarbrough et al.
A GI-active pathogen destroys intestinal cells, in part by improperly modifying a host signaling protein, causing loss of cell shape and contributing to cell death.

Simpson’s Paradox in a Synthetic Microbial System (9 January 2009)
J. S. Chuang, O. Rivoire, S. Leibler
Stochastic fluctuations in the population structure of microorganisms can allow a disadvantaged subpopulation to be maintained.  

Recombination of Retrotransposon and Exogenous RNA Virus Results in Nonretroviral cDNA Integration (16 January 2009)
M. B. Geuking et al.
With the help of an endogenous retrovirus, RNA virus sequence can be incorporated into mouse chromosomes.

Molecular Mechanisms of HipA-Mediated Multidrug Tolerance and Its Neutralization by HipB (16 January 2009)
M. A. Schumacher et al.
A persistence factor similar to a eukaryotic kinase regulates bacterial dormancy and contributes to antibiotic resistance in E. coli.

The Peopling of the Pacific from a Bacterial Perspective (23 January 2009)
Y. Moodley et al.
The geographical distribution of strains of a specific human pathogen helps to define patterns of colonization out of Taiwan.
See related Perspective.

Rapid Membrane Disruption by a Perforin-Like Protein Facilitates Parasite Exit from Host Cells (23 January 2009)
B. F. C. Kafsack et al.
The human and animal parasite that causes toxoplasmosis escapes from host cells by using a perforin-like protein to make holes in the intracellular vacuole in which it resides. |


NEUROSCIENCE/PSYCHOLOGY
 
Regulation of Neuronal Survival Factor MEF2D by Chaperone-Mediated Autophagy (2 January 2009)
Q. Yang et al.
The degradation of a key neuronal survival factor by chaperone-mediated autophagy may contribute to Parkinson’s disease. 

Mispredicting Affective and Behavioral Responses to Racism (9 January 2009)
K. Kawakami, E. Dunn, F. Karmali, J. F. Dovidio
People predict that they will feel worse after witnessing a racist comment than they actually do. 
See related Perspective.

Draxin, a Repulsive Guidance Protein for Spinal Cord and Forebrain Commissures (16 January 2009)
S. M. Islam et al.
A protein cue guides the formation of bundles of nerve fibers that connect the cerebral hemispheres.

Calcineurin/NFAT Signaling Is Required for Neuregulin-Regulated Schwann Cell Differentiation (30 January 2009)
S.-C. Kao et al.
The cell signaling components calcineurin/NFATc and Sox10 control Schwann cell myelination.


IMMUNOLOGY

Different T Cell Receptor Signals Determine CD8+ Memory Versus Effector Development (23 January 2009)
E. Teixeiro et al.
Point mutations in the T cell receptor decide the fate of killer T cells and the development of immunological memory.
See related Perspective.

Secondary Replicative Function of CD8+ T Cells That Had Developed an Effector Phenotype (23 January 2009)
O. Bannard, M. Kraman, D. T. Fearon
Killer T cells that developed during a primary antiviral response can become memory T cells in secondary infections.
See related Perspective.


MOLECULAR BIOLOGY

Genetic Code Supports Targeted Insertion of Two Amino Acids by One Codon (9 January 2009)
A. A. Turanov et al.
One codon can code for two different amino acids within the same gene, with the choice determined by an RNA structure in an untranslated region. 

Chromatin-Associated Periodicity in Genetic Variation Downstream of Transcriptional Start Sites (16 January 2009)
S. Sasaki et al.
The periodic wrapping of DNA around nucleosomes in chromatin determines a periodic variation in mutation type and frequency around transcription start sites in a fish.
See related Perspective.


PLANT SCIENCE

Glucosinolate Metabolites Required for an Arabidopsis Innate Immune Response (2 January 2009)
N. K. Clay, A. M. Adio, C. Denoux, G. Jander, F. M. Ausubel 
A Glucosinolate Metabolism Pathway in Living Plant Cells Mediates Broad-Spectrum Antifungal Defenses (2 January 2009)
P. Bednarek et al.
Plant cells defend against fungal attack through an innate immunity pathway in which infection triggers glucosinolate synthesis, stimulating formation of a protective callose.

Floral Iridescence, Produced by Diffractive Optics, Acts as a Cue for Animal Pollinators (2 January 2009)
H. M. Whitney et al.
The iridescence of tulip petals, as well as their pigmentation, affects foraging behavior by bumblebees.

tasselseed1 Is a Lipoxygenase Affecting Jasmonic Acid Signaling in Sex Determination of Maize (9 January 2009)
I. F. Acosta et al.
A gene that controls male floral development in maize is involved in synthesis of a hormone that suppresses female organ development.

PAN1: A Receptor-Like Protein That Promotes Polarization of an Asymmetric Cell Division in Maize (30 January 2009)
H. N. Cartwright, J. A. Humphries, L. G. Smith
Asymmetric cell division in plants is regulated by a receptor-like kinase, implicating a signaling cascade in cell polarization.
See related Perspective.

Sponsored by: