Bio-Med Roundup

This month in Bio-Med Roundup:
  • Core et al., Seila et al., Preker et al., and He et al. described a new class of transcripts that initiate near transcription start sites upstream of protein-encoding sequences.
  • Keizer et al. found that upon observing signs of social disorder, individuals are more likely to disobey a variety of social rules.
  • Mold et al. showed that exposure of the human fetus to maternal cells during pregnancy prompts the development of regulatory T cells that can suppress fetal antimaternal immunity.
  • Singh et al. provided insight into the structure and function of the bacterial protein LeuT, a model for mammalian neurotransmitter transporters.
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 CELL/DEVELOPMENTAL BIOLOGY
 
Dynamic Proteomics of Individual Cancer Cells in Response to a Drug (5 December 2008)
A. A. Cohen et al.
Cells that escape death from a chemotherapy drug express a different array of proteins than do genetically identical cells that die, which may help to inform cancer therapeutics.

A Stress Signaling Pathway in Adipose Tissue Regulates Hepatic Insulin Resistance (5 December 2008)
G. Sabio et al.
In mice, some detrimental effects of a diet high in fat—insulin resistance, for instance—result from hormonal signals sent from fat cells to the liver.
See related Perspective.

Inhibition of Rac by the GAP Activity of Centralspindlin Is Essential for Cytokinesis (5 December 2008)
J. C. Canman et al.
During cell division, a component of the spindle inhibits a small regulatory binding protein, allowing another regulator to constrict a ring between the separating daughter cells.

Dynamic Analyses of Drosophila Gastrulation Provide Insights into Collective Cell Migration (5 December 2008)
A. McMahon, W. Supatto, S. E. Fraser, A. Stathopoulos
Live fluorescence imaging of over 1500 cells within a Drosophila embryo during gastrulation reveals that a fibroblast growth factor coordinates cell migration.

Germ Cell–Intrinsic and –Extrinsic Factors Govern Meiotic Initiation in Mouse Embryos (12 December 2008)
Y. Lin, M. E. Gill, J. Koubova, D. C. Page
Mouse germ cells begin meiosis for sperm or egg production only when they both are stimulated by the hormone retinoic acid and express a particular RNA-binding protein.

A Role for the ESCRT System in Cell Division in Archaea (12 December 2008)
R. Y. Samson, T. Obita, S. M. Freund, R. L. Williams, S. D. Bell
A class of proteins required for membrane trafficking and cytokinesis in eukaryotes is also unexpectedly required in some Archaea for cell division.

De Novo Formation of a Subnuclear Body (12 December 2008)
T. E. Kaiser, R. V. Intine, M. Dundr
The Cajal body, a nuclear structure for small ribonucleoprotein metabolism, can self-assemble from any one of its components immobilized on a substrate.

Human Fetal Hemoglobin Expression Is Regulated by the Developmental Stage-Specific Repressor BCL11A (19 December 2008)
V. G. Sankaran et al.
A way to reactivate a fetal form of ?-globin in adults - by releasing it from repression by an inhibitor - may prove useful for treating certain genetic anemias.
See related Perspective.

Nascent RNA Sequencing Reveals Widespread Pausing and Divergent Initiation at Human Promoters (19 December 2008)
L. J. Core, J. J. Waterfall, J. T. Lis
RNA sequencing identifies antisense transcription immediately upstream of genes with transcriptionally engaged RNA polymerase.
See related Perspective.

Divergent Transcription from Active Promoters (19 December 2008)
A. C. Seila et al.
Active genes produce promoter-localized sense and antisense short RNAs, suggesting frequent transcription by divergently oriented RNA polymerase II complexes at mammalian promoters.
See related Perspective.

RNA Exosome Depletion Reveals Transcription Upstream of Active Human Promoters (19 December 2008)
P. Preker et al.
Highly unstable transcripts exist upstream of active human promoters.
See related Perspective.

The Antisense Transcriptomes of Human Cells (19 December 2008)
Y. He, B. Vogelstein, V. E. Velculescu, N. Papadopoulos, K. W. Kinzler
The abundance and nonrandom genomic origin of antisense transcripts in human cells suggest that these RNAs are an important feature of gene regulation.
See related Perspective.


NEUROSCIENCE

Astroglial Metabolic Networks Sustain Hippocampal Synaptic Transmission (5 December 2008)
N. Rouach, A. Koulakoff, V. Abudara, K. Willecke, C. Giaume
The glial astrocytes that surround neurons supply glucose or lactate to excitatory synapses though gap junctions that open when the neurons are active.

Activation of Pannexin-1 Hemichannels Augments Aberrant Bursting in the Hippocampus (5 December 2008)
R. J. Thompson et al.
Activation of a glutamate receptor in hippocampal cells leads to secondary opening of a gap junction–like channel that can contribute to seizure-like bursting.

Modafinil Shifts Human Locus Coeruleus to Low-Tonic, High-Phasic Activity During Functional MRI (12 December 2008)
M. J. Minzenberg, A. J. Watrous, J. H. Yoon, S. Ursu, C. S. Carter
Brain images of humans treated with a cognitive enhancing drug show increased task-oriented activity in a brainstem nucleus and confirm that this region controls cognition.

Representation of Geometric Borders in the Entorhinal Cortex (19 December 2008)
T. Solstad, C. N. Boccara, E. Kropff, M.-B. Moser, E. I. Moser
A previously unknown cell type in the brain’s cortex encodes geometric boundaries of the nearby environment, perhaps providing a frame of reference.


MOLECULAR BIOLOGY

Photoexcited CRY2 Interacts with CIB1 to Regulate Transcription and Floral Initiation in Arabidopsis (5 December 2008)
H. Liu, X. Yu, K. Li, J. Klejnot, H. Yang, D. Lisiero, C. Lin
Blue light triggers the association of a photoreceptor, transcription factor, and DNA site, thus inducing expression for the gene FT (flowering time) and initiating flowering.

The Air Noncoding RNA Epigenetically Silences Transcription by Targeting G9a to Chromatin (12 December 2008)
T. Nagano et al.
Air, a large noncoding RNA, interacts with chromatin at a particular promoter, recruiting a histone methyltransferase to silence gene expression in an allele-specific manner.

CRISPR Interference Limits Horizontal Gene Transfer in Staphylococci by Targeting DNA (19 December 2008)
L. A. Marraffini and E. J. Sontheimer
The small CRISPR RNAs in Staphylococci bacteria that protect against phage infection are complementary to foreign phage DNA and target it for destruction.


MEDICINE

Genomic Loss of microRNA-101 Leads to Overexpression of Histone Methyltransferase EZH2 in Cancer (12 December 2008)
S. Varambally et al.
In some human prostate cancers, a genomic deletion eliminates a key regulatory microRNA, which results in disruption of gene-silencing mechanisms.

A Null Mutation in Human APOC3 Confers a Favorable Plasma Lipid Profile and Apparent Cardioprotection (12 December 2008)
T. I. Pollin et al.
A mutation resulting in a lifelong decrease in the expression of a protein that inhibits triglyceride hydrolysis may protect against cardiovascular disease.

Label-Free Biomedical Imaging with High Sensitivity by Stimulated Raman Scattering Microscopy (19 December 2008)
C. W. Freudiger et al.
Three-dimensional imaging based on stimulated Raman scattering can detect lipids in living cells and monitor the movement of drugs through the skin.

Leukemic Cells Create Bone Marrow Niches That Disrupt the Behavior of Normal Hematopoietic Progenitor Cells (19 December 2008)
A. Colmone et al.
Cancerous immune cells create abnormal microenvironments in bone marrow that attract normal immune precursor cells, disrupting their function and exacerbating disease.


IMMUNOLOGY
 
Maternal Alloantigens Promote the Development of Tolerogenic Fetal Regulatory T Cells in Utero (5 December 2008)
J. E. Mold et al.
Exposure of the human fetus to maternal cells during pregnancy can prompt development of regulatory T cells that prevent responses to non-inherited maternal antigens.

Regulation of Dendritic Cell Migration by CD74, the MHC Class II–Associated Invariant Chain (12 December 2008)
G. Faure-André et al.
By binding to a myosin, an immune-specific protein known to control antigen processing also regulates the migration of dendritic cells, possibly coordinating the two functions.
See related Perspective.


PSYCHOLOGY/SOCIOLOGY

The Long-Run Benefits of Punishment (5 December 2008)
S. Gächter, E. Renner, M. Sefton
In human social groups, punishment of uncooperative behaviors increases teamwork, but the benefits of cooperation only outweigh the costs of punishment after a long time.

The Spreading of Disorder (12 December 2008)
K. Keizer, S. Lindenberg, L. Steg
Upon observing signs of social disorder (such as littering or graffiti), individuals are more likely to disobey a variety of social rules, including prohibitions against theft.


BIOCHEMISTRY

A Competitive Inhibitor Traps LeuT in an Open-to-Out Conformation (12 December 2008)
S. K. Singh, C. L. Piscitelli, A. Yamashita, E. Gouaux
A bacterial protein similar to mammalian neurotransmitter transporters is blocked when a competitive inhibitor prevents the formation of the normal intermediate state.
See related Perspective.

Traction Dynamics of Filopodia on Compliant Substrates (12 December 2008)
C. E. Chan and D. J. Odde
A model that predicts that substrate/surface stiffness acts through a cellular motor-clutch mechanism to alter retrograde flow rates and traction is confirmed in chick neurons.
See related Perspective.

Structure and Functional Role of Dynein’s Microtubule-Binding Domain (12 December 2008)
A. P. Carter et al.
ATP hydrolysis by the molecular motor dynein transmits a structural change to its microtubule-binding domain, determining movement direction along the microtubule.
See related Perspective.


PLANT SCIENCE

Centromere-Associated Female Meiotic Drive Entails Male Fitness Costs in Monkeyflowers (5 December 2008)
L. Fishman and A. Saunders
Competition between chromosomal homologs causes non-Mendelian meiotic segregation and fitness polymorphism in a natural monkeyflower population.
See related Perspective.

Developing Patterning by Mechanical Signals in Arabidopsis (12 December 2008)
O. Hamant et al.
The growth pattern of plant meristem, the group of stem cells at the tip of a growing shoot, is controlled by a microtubule-based mechanical feedback loop.
See related Perspective.

The Circadian Clock in Arabidopsis Roots Is a Simplified Slave Version of the Clock in Shoots (19 December 2008)
A. B. James et al.
A simpler plant circadian clock, which normally has three interlocking feedback loops, is used in the roots, with one feedback loop regulating only a few genes.

A Conserved Molecular Framework for Compound Leaf Development (19 December 2008)
T. Blein et al.
A family of transcription factors controls the formation of leaflets and lobes in complex leaves in distantly related plants by controlling outgrowth from leaf margins.

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