Differential immune imprinting by influenza virus vaccination and infection in nonhuman primates.

Immune memory of a first infection with influenza virus establishes a lasting imprint. Recall of that memory dominates the response to later infections or vaccinations by antigenically drifted strains. Early childhood immunization before infection may leave an imprint with different characteristics.

Host-microbe cross-talk governs amino acid chirality to regulate survival and differentiation of B cells.

Organisms use l-amino acids (l-aa) for most physiological processes. Unlike other organisms, bacteria chiral-convert l-aa to d-configurations as essential components of their cell walls and as signaling molecules in their ecosystems. Mammals recognize microbe-associated molecules to initiate immune responses, but roles of bacterial d-amino acids (d-aa) in mammalian immune systems remain largely unknown.

RNA helicase DDX21 mediates nucleotide stress responses in neural crest and melanoma cells.

The availability of nucleotides has a direct impact on transcription. The inhibition of dihydroorotate dehydrogenase (DHODH) with leflunomide impacts nucleotide pools by reducing pyrimidine levels. Leflunomide abrogates the effective transcription elongation of genes required for neural crest development and melanoma growth in vivo.

Structure of the substrate-engaged SecA-SecY protein translocation machine.

The Sec61/SecY channel allows the translocation of many proteins across the eukaryotic endoplasmic reticulum membrane or the prokaryotic plasma membrane. In bacteria, most secretory proteins are transported post-translationally through the SecY channel by the SecA ATPase. How a polypeptide is moved through the SecA-SecY complex is poorly understood, as structural information is lacking.

Structural and Mechanistic Insights into Protein Translocation.

Many proteins are translocated across the endoplasmic reticulum (ER) membrane in eukaryotes or the plasma membrane in prokaryotes. These proteins use hydrophobic signal sequences or transmembrane (TM) segments to trigger their translocation through the protein-conducting Sec61/SecY channel. Substrates are first directed to the channel by cytosolic targeting factors, which use hydrophobic pockets to bind diverse signal and TM sequences.

Chemical screening in zebrafish for novel biological and therapeutic discovery.

Zebrafish chemical screening allows for an in vivo assessment of small molecule modulation of biological processes. Compound toxicities, chemical alterations by metabolism, pharmacokinetic and pharmacodynamic properties, and modulation of cell niches can be studied with this method. Furthermore, zebrafish screening is straightforward and cost effective.

Development: For cloche the Bell Tolls.

A recent publication identifies npas4l as the gene defective in the well-known cloche mutant that lacks most endothelial as well as hematopoietic cells. This work poses intriguing questions as to the genetic and molecular nature of the origin of hemato-vascular lineages during early embryogenesis.

Tissue-specific gene targeting using CRISPR/Cas9.

The zebrafish has been a powerful model in forward genetic screens to identify genes essential for organogenesis and embryonic development. Conversely, using reverse genetics to investigate specific gene function requires phenotypic analysis of complete gene inactivation. Despite the availability and efficacy of morpholinos, the lack of tractable and efficient knockout technologies has impeded reverse genetic studies in the zebrafish, particularly in adult animals.

Crystal structure of a substrate-engaged SecY protein-translocation channel.

Hydrophobic signal sequences target secretory polypeptides to a protein-conducting channel formed by a heterotrimeric membrane protein complex, the prokaryotic SecY or eukaryotic Sec61 complex. How signal sequences are recognized is poorly understood, particularly because they are diverse in sequence and length. Structures of the inactive channel show that the largest subunit, SecY or Sec61α, consists of two halves that form an hourglass-shaped pore with a constriction in the middle of the membrane and a lateral gate that faces lipid.

Data publication with the structural biology data grid supports live analysis.

Access to experimental X-ray diffraction image data is fundamental for validation and reproduction of macromolecular models and indispensable for development of structural biology processing methods. Here, we established a diffraction data publication and dissemination system, Structural Biology Data Grid (SBDG; data.sbgrid.

When attention wanders: how uncontrolled fluctuations in attention affect performance.

No matter how hard subjects concentrate on a task, their minds wander (Raichle et al., 2001; Buckner et al., 2008; Christoff et al.

Chemical screening in zebrafish for novel biological and therapeutic discovery.

Zebrafish chemical screening allows for an in vivo assessment of small molecule modulation of biological processes. Compound toxicities, chemical alterations by metabolism, pharmacokinetic and pharmacodynamic properties, and modulation of cell niches can be studied with this method. Furthermore, zebrafish screening is straightforward and cost-effective.

Attention improves performance primarily by reducing interneuronal correlations.

Visual attention can improve behavioral performance by allowing observers to focus on the important information in a complex scene. Attention also typically increases the firing rates of cortical sensory neurons. Rate increases improve the signal-to-noise ratio of individual neurons, and this improvement has been assumed to underlie attention-related improvements in behavior.

Use of mouse models for the analysis of human disease.

The first half of this unit discusses the two main approaches to developing genetically engineered mouse models of human disease (i.e., transgenesis and gene targeting).

Small molecule screening in the zebrafish.

The zebrafish is an ideal organism for small molecule studies. The ability to use the whole organism allows complex in vivo phenotypes to be assayed and combines animal testing with screening. Embryos are easily treatable by waterborne exposure.

Reduced cross-bridge dependent stiffness of skinned myocardium from mice lacking cardiac myosin binding protein-C.

The role of cardiac myosin binding protein-C (MyBP-C) on myocardial stiffness was examined in skinned papillary muscles of wild-type (WT(+/+)) and homozygous truncated cardiac MyBP-C (MyBP-C(t/t)) male mice. No MyBP-C was detected by gel electrophoresis or by Western blots in the MyBP-C(t/t) myocardium. Rigor-bridge dependent myofilament stiffness, i.

Crystal structure of the bacterial nucleoside transporter Tsx.

Tsx is a nucleoside-specific outer membrane (OM) transporter of Gram-negative bacteria. We present crystal structures of Escherichia coli Tsx in the absence and presence of nucleosides. These structures provide a mechanism for nucleoside transport across the bacterial OM.

Distribution of the presynaptic calcium sensors, synaptotagmin I/II and synaptotagmin III, in the goldfish and rodent retinas.

Synaptic vesicle exocytosis is triggered by rises in calcium up to 100 microM at the site of vesicle fusion. The synaptic vesicle proteins synaptotagmin 1 and 2 (Syt I and Syt II) bind calcium at similarly high concentrations and have been proposed as the calcium sensors for fast neurotransmitter release. However, 1 microM calcium produces tonic transmitter release at photoreceptor and bipolar cell synapses in the goldfish retina, suggesting that these synapses use a higher affinity calcium sensor.

The L-type calcium channel inhibitor diltiazem prevents cardiomyopathy in a mouse model.

Dominant mutations in sarcomere protein genes cause hypertrophic cardiomyopathy, an inherited human disorder with increased ventricular wall thickness, myocyte hypertrophy, and disarray. To understand the early consequences of mutant sarcomere proteins, we have studied mice (designated alphaMHC(403/+)) bearing an Arg403Gln missense mutation in the alpha cardiac myosin heavy chain. We demonstrate that Ca(2+) is reduced in the sarcoplasmic reticulum of alphaMHC(403/+) mice, and levels of the sarcoplasmic reticulum Ca(2+)-binding protein calsequestrin are diminished in advance of changes in cardiac histology or morphology.

Inherited iron overload disorders.

Iron is an essential nutrient that is highly toxic in excess. Normal iron balance is maintained primarily by regulation of intestinal absorption of the metal from the diet. Iron overload generally results from a chronic increase in intestinal absorption.

CHOP gene expression in response to endoplasmic-reticular stress requires NFY interaction with different domains of a conserved DNA-binding element.

The transcription factor CHOP/GADD153 gene is induced by cellular stress and is involved in mediating apoptosis. We report the identification of a conserved region in the promoter of the CHOP gene responsible for its inducibility by endoplasmic reticulum (ER) stress. Deletion mutants of the human CHOP promoter identify a region comprising nucleotides -75 to -104 required for both constitutive and ER-stress-inducible expression.

Dilated cardiomyopathy in homozygous myosin-binding protein-C mutant mice.

To elucidate the role of cardiac myosin-binding protein-C (MyBP-C) in myocardial structure and function, we have produced mice expressing altered forms of this sarcomere protein. The engineered mutations encode truncated forms of MyBP-C in which the cardiac myosin heavy chain-binding and titin-binding domain has been replaced with novel amino acid residues. Analogous heterozygous defects in humans cause hypertrophic cardiomyopathy.

New advances in understanding the molecular mechanisms of thyroid hormone action.

Thyroid hormone regulation o f gene transcription is a complex process. There are multiple thyroid hormone receptors (TRs) encoded on separate genes that bind to thyroid hormone-response elements (TREs) of target genes containing different orientation and spacing of half-sites. Additionally, there are multiple TR complexes-monomers, homodimers, and heterodimers with other related nuclear proteins-which bind to TREs and may play important roles in gene transcription.