This month in Bio-Med Roundup:
- Gibson et al. reported the complete chemical synthesis and assembly of a bacterial genome.
- Feng et al. provided evidence that a rare, but highly aggressive form of human skin cancer may be caused by a virus.
- Marchiori and Warglien showed that a simple neural network model that incorporates regret accurately predicts human behavior in economic games.
- Ryu et al. showed that a fruit fly gene important in development also inhibits the production of harmful antimicrobial peptides that could kill off beneficial gut microbes.
- Genetics
- Medicine
- Psychology/Neuroscience
- Cell/Developmental Biology
- Molecular Biology
- Immunology
- Biochemistry
- Physiology
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GENETICS
Widespread Genetic Incompatibility in C. elegans Maintained by Balancing Selection (1 February 2008)
H. S. Seidel, M. V. Rockman, L. Kruglyak
Strong natural selection is maintaining multiple alleles of a gene in wild populations of the nematode C. elegans, despite their negative effect on fitness.
An Association Between the Kinship and Fertility of Human Couples (8 February 2008)
A. Helgason, S. Pálsson, D. F. Guðbjartsson, þ. Kristjánsson, K. Stefánsson
The extensive genealogies of the Icelandic people show that couples who are 3rd or 4th cousins have more children and grandchildren than couples whose relationships are more or less distant.
Mutations in the Pericentrin (PCNT) Gene Cause Primordial Dwarfism (8 February 2008)
A. Rauch et al.
In humans, an inherited condition with small brain size and near-normal intelligence is caused by mutations that disrupt chromosome separation during cell division.
See related Perspective.
A Mouse Model of Mitochondrial Disease Reveals Germline Selection Against Severe mtDNA Mutations (15 February 2008)
W. Fan et al.
Developing mouse oocytes that harbor highly deleterious mitochondrial DNA mutations are eliminated, minimizing negative impact on population fitness.
See related Perspective.
Worldwide Human Relationships Inferred from Genome-Wide Patterns of Variation (22 February 2008)
J. Z. Li et al.
Analysis of variation in 51 human populations reveals details of European subpopulations and confirms that humans formed a chain of colonies as they radiated out from Africa.
Complete Chemical Synthesis, Assembly, and Cloning of a Mycoplasma genitalium Genome (29 February 2008)
D. G. Gibson et al.
A complete bacterial genome is synthesized, assembled, and cloned, providing a method that will be useful for generating large DNA molecules de novo.
See related Perspective.
MEDICINE
Profiling Essential Genes in Human Mammary Cells by Multiplex RNAi Screening (1 February 2008)
J. M. Silva et al.
Cancer Proliferation Gene Discovery Through Functional Genomics (1 February 2008)
M. R. Schlabach et al.
Systematic inhibition of gene expression with RNA interference screening reveals genes essential for growth and survival of tumor cells, potentially leading to new cancer drugs.
A Heme Export Protein Is Required for Red Blood Cell Differentiation and Iron Homeostasis (8 February 2008)
S. B. Keel et al.
A mouse cell-surface protein exports excess heme, which is toxic when free in the cytoplasm, ensuring normal red blood cell maturation and systemic iron balance.
Identification of Host Proteins Required for HIV Infection Through a Functional Genomic Screen (15 February 2008)
A. L. Brass et al.
An RNAi screen identified 237 new and 38 known human proteins required for HIV infection, including ones used in Golgi transport and in viral integration and transcription.
Metal Chelation and Inhibition of Bacterial Growth in Tissue Abscesses (15 February 2008)
B. D. Corbin et al.
An immune cell–derived protein binds metal ions in infected abscesses, depriving the bacteria of the essential nutrients magnesium and zinc and reducing their growth.
See related Perspective.
Clonal Integration of a Polyomavirus in Human Merkel Cell Carcinoma (22 February 2008)
H. Feng, M. Shuda, Y. Chang, P. S. Moore
A rare, but highly aggressive, form of human skin cancer may be caused by a previously uncharacterized human polyomavirus.
See related Perspective.
PSYCHOLOGY/NEUROSCIENCE
The Critical Importance of Retrieval for Learning (15 February 2008)
J. D. Karpicke and H. L. Roediger III
Students recalled words they had learned the previous week more effectively if they were tested repeatedly in the interim than if they spent the time studying.
Spine-Type–Specific Recruitment of Newly Synthesized AMPA Receptors with Learning (22 February 2008)
N. Matsuo, L. Reijmers, M. Mayford
Mushroom-shaped synaptic spines activated during learning preferentially capture newly synthesized glutamate receptors, which may contribute to memory storage.
Rapid Neural Coding in the Retina with Relative Spike Latencies (22 February 2008)
T. Gollisch and M. Meister
In salamanders, ganglion cells, which project from the retina to the brain, use the relative timing of single spikes in each cell to quickly encode a visual scene.
Predicting Human Interactive Learning by Regret-Driven Neural Networks (22 February 2008)
D. Marchiori and M. Warglien
An unexpectedly simple neural network model that includes feedback driven by regret predicts human behavior in strategic games and outperforms existing models of learning.
See related Perspective.
Synaptic Protein Degradation Underlies Destabilization of Retrieved Fear Memory (29 February 2008)
S.-H. Lee et al.
Upon recollection, mouse memories of fearful situations become labile, as postsynaptic proteins are degraded by proteosomes and are then reconsolidated via protein synthesis.
Hybrid Neurons in a MicroRNA Mutant Are Putative Evolutionary Intermediates in Insect CO2 Sensory Systems (29 February 2008)
P. Cayirlioglu et al.
Loss of a microRNA in Drosophila leads to misexpression of CO2-sensing neurons in the mouthparts, creating a possible evolutionary hybrid between the fruit fly and mosquito.
Transgenic Inhibition of Synaptic Transmission Reveals Role of CA3 Output in Hippocampal Learning (29 February 2008)
T. Nakashiba, J. Z. Young, T. J. McHugh, D. L. Buhl, S. Tonegawa
Blockade of neural activity in the CA3 region of the hippocampus with a reversible, inducible transgenic method inhibits rapid learning but spares certain spatial tasks.
BOLD Responses Reflecting Dopaminergic Signals in the Human Ventral Tegmental Area (29 February 2008)
K. D’Ardenne, S. M. McClure, L. E. Nystrom, J. D. Cohen
In humans, activity measurements in a small midbrain region show that resident dopamine-containing neurons accurately predict rewards in a learning task.
CELL/DEVELOPMENTAL BIOLOGY
Oocyte-Specific Deletion of Pten Causes Premature Activation of the Primordial Follicle Pool (1 February 2008)
P. Reddy et al.
In mice, a tumor suppressor commonly mutated in human cancers prevents premature activation of ovarian follicles, allowing them to form oocytes throughout life.
The Maternal Nucleolus Is Essential for Early Embryonic Development in Mammals (1 February 2008)
S. Ogushi et al.
After fertilization or somatic cell nuclear transfer, the oocyte’s nucleolus but not the sperm’s is essential for subsequent development.
The Premetazoan Ancestry of Cadherins (15 February 2008)
M. Abedin and N. King
A close unicellular relative of metazoans unexpectedly contains 23 genes for a cell adhesion protein, suggesting a role for the protein in the evolution of multicellularity.
Juvenile Hormone Regulates Butterfly Larval Pattern Switches (22 February 2008)
R. Futahashi and H. Fujiwara
In swallowtail butterflies, a hormone regulates a dramatic developmental shift as the young caterpillars, which mimic bird droppings, grow into the green cryptic larva.
Differential Regulation of Dynein and Kinesin Motor Proteins by Tau (22 February 2008)
R. Dixit, J. L. Ross, Y. E. Goldman, E. L. F. Holzbaur
When molecular motors move along microtubules, they encounter the bound protein tau; the dynein motor then reverses direction, whereas the kinesin motor detaches.
Local Positive Feedback Regulation Determines Cell Shape in Root Hair Cells (29 February 2008)
S. Takeda, C. Gapper, H. Kaya, E. Bell, K. Kuchitsu, L. Dolan
Accumulation of an oxidase enzyme at one end of Arabidopsis root hair cells generates reactive oxygen species, which in turn trigger calcium entry and directional growth.
Ceramide Triggers Budding of Exosome Vesicles into Multivesicular Endosomes (29 February 2008)
K. Trajkovic et al.
Endosomes, membrane-bound vesicles later released from cells, are filled by a lipid-controlled budding of certain membrane regions into the lumen.
See related Perspective.
Membrane Proteins of the Endoplasmic Reticulum Induce High-Curvature Tubules (29 February 2008)
J. Hu et al.
Integral membrane proteins from the endoplasmic reticulum induce the development of tubular structures in vitro by forming oligomers in the plane of the membrane.
MOLECULAR BIOLOGY
Reciprocal Binding of PARP-1 and Histone H1 at Promoters Specifies Transcriptional Outcomes (8 February 2008)
R. Krishnakumar et al.
At certain genes regulated by the nucleosome-binding protein PARP-1, the presence of a linker histone at the promoter prevents PARP-1 binding, inhibiting gene activation.
NADP Regulates the Yeast GAL Induction System (22 February 2008)
P. R. Kumar, Y. Yu, R. Sternglanz, S. A. Johnston, L. Joshua-Tor
The structure of a repressor-activator complex for galactose metabolism shows that its assembly is controlled by the ratio of two cofactors that reflect the cell’s metabolism.
A Shared Docking Motif in TRF1 and TRF2 Used for Differential Recruitment of Telomeric Proteins (22 February 2008)
Y. Chen et al.
Two similar members of the protein complex that protects the free ends of chromosomes have distinct binding sites for other complex members and accessory proteins.
IMMUNOLOGY
Cathepsin K–Dependent Toll-Like Receptor 9 Signaling Revealed in Experimental Arthritis (1 February 2008)
M. Asagiri et al.
A lyosomal enzyme normally associated with osteoclasts of the bone has further function in signaling through an innate receptor in immune cells.
See related Perspective.
Systemic Leukocyte-Directed siRNA Delivery Revealing Cyclin D1 as an Anti-Inflammatory Target (1 February 2008)
D. Peer, E. J. Park, Y. Morishita, C. V. Carman, M. Shimaoka
Small RNAs are packaged in lipid nanoparticles with antibodies that direct them to specific gut immune cells, where they suppress inflammation by inhibiting a cell-cycle protein.
See related Perspective.
Innate Immune Homeostasis by the Homeobox Gene Caudal and Commensal-Gut Mutualism in Drosophila (8 February 2008)
J.-H. Ryu et al.
A Drosophila gene important in development also inhibits the production of harmful antimicrobial peptides that could kill off beneficial gut microbes.
See related Perspective.
Repression of the Transcription Factor Th-POK by Runx Complexes in Cytotoxic T Cell Development (8 February 2008)
R. Setoguchi et al.
A key cell-fate decision—to become a cytotoxic rather than a helper T cell—is controlled by repression of the helper T cell transcription factor by a second transcription factor.
BIOCHEMISTRY
Direct Observation of Hierarchical Folding in Single Riboswitch Aptamers (1 February 2008)
W. J. Greenleaf, K. L. Frieda, D. A. N. Foster, M. T. Woodside, S. M. Block
Optical trapping reveals that activation by adenine stabilizes the weakest helix in a riboswitch, after which secondary and tertiary structures are formed sequentially.
Three-Dimensional Super-Resolution Imaging by Stochastic Optical Reconstruction Microscopy (8 February 2008)
B. Huang, W. Wang, M. Bates, X. Zhuang
Three-dimensional fluorescence images of cellular structures in fixed cells are realized at 20- to 30-nanometer lateral and 50-nanometer axial resolution, without scanning.
Axle-Less F1-ATPase Rotates in the Correct Direction (15 February 2008)
S. Furuike et al.
A molecular rotary motor continues to rotate in the correct direction even when its shaft is deleted, leaving only the rotor head sitting on top of the shaft housing.
Atomic-Level Models of the Bacterial Carboxysome Shell (22 February 2008)
S. Tanaka et al.
Pentameric proteins around the carboxysome, an organelle involved in carbon fixation, fit together with hexagonally packed proteins to form the organelle’s icosahedral shell.
PHYSIOLOGY
Experienced Saxophonists Learn to Tune Their Vocal Tracts (8 February 2008)
J. M. Chen, J. Smith, J. Wolfe
To play the high range of the saxophone, players learn to tune the second resonance of their vocal tract to the desired note.
Biomechanical Energy Harvesting: Generating Electricity During Walking with Minimal User Effort (8 February 2008)
J. M. Donelan et al.
A knee-mounted device can generate several watts of power at the end of each leg swing in a process similar to regenerative braking in hybrid cars.
Leading-Edge Vortex Improves Lift in Slow-Flying Bats (29 February 2008)
F. T. Muijres et al.
Flying bats generate high lift forces similar to those used by insects, creating a vortex of air that stays attached to the wing on the downward stroke.
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