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A spatiotemporal map of phasiRNAs in maize anthers [Plant Biology]

PNAS Early Edition Articles - Mon, 02/23/2015 - 14:05
Maize anthers, the male reproductive floral organs, express two classes of phased small-interfering RNAs (phasiRNAs). PhasiRNA precursors are transcribed by RNA polymerase II and map to low-copy, intergenic regions similar to PIWI-interacting RNAs (piRNAs) in mammalian testis. From 10 sequential cohorts of staged maize anthers plus mature pollen we find...

Intraguild predation and the dilution effect [Ecology]

PNAS Early Edition Articles - Mon, 02/23/2015 - 14:05
Humans are altering biodiversity globally and infectious diseases are on the rise; thus, there is interest in understanding how changes to biodiversity affect disease. Here, we explore how predator diversity shapes parasite transmission. In a mesocosm experiment that manipulated predator (larval dragonflies and damselflies) density and diversity, non-intraguild (non-IG) predators...

Novel primate- and tissue-specific microRNAs [Genetics]

PNAS Early Edition Articles - Mon, 02/23/2015 - 14:05
Two decades after the discovery of the first animal microRNA (miRNA), the number of miRNAs in animal genomes remains a vexing question. Here, we report findings from analyzing 1,323 short RNA sequencing samples (RNA-seq) from 13 different human tissue types. Using stringent thresholding criteria, we identified 3,707 statistically significant novel...

Multicolor CRISPR chromosome labeling [Cell Biology]

PNAS Early Edition Articles - Mon, 02/23/2015 - 14:05
The intranuclear location of genomic loci and the dynamics of these loci are important parameters for understanding the spatial and temporal regulation of gene expression. Recently it has proven possible to visualize endogenous genomic loci in live cells by the use of transcription activator-like effectors (TALEs), as well as modified...

Maternal sounds and auditory brain plasticity [Psychological and Cognitive Sciences]

PNAS Early Edition Articles - Mon, 02/23/2015 - 14:05
Brain development is largely shaped by early sensory experience. However, it is currently unknown whether, how early, and to what extent the newborn’s brain is shaped by exposure to maternal sounds when the brain is most sensitive to early life programming. The present study examined this question in 40 infants...

Functional biomolecule delivery via microvesicles [Cell Biology]

PNAS Early Edition Articles - Mon, 02/23/2015 - 14:05
Extracellular vesicles (EVs), specifically exosomes and microvesicles (MVs), are presumed to play key roles in cell–cell communication via transfer of biomolecules between cells. The biogenesis of these two types of EVs differs as they originate from either the endosomal (exosomes) or plasma (MVs) membranes. To elucidate the primary means through...

Decorrelation of retinal response by eye movements [Neuroscience]

PNAS Early Edition Articles - Mon, 02/23/2015 - 14:05
Under natural viewing conditions the input to the retina is a complex spatiotemporal signal that depends on both the scene and the way the observer moves. It is commonly assumed that the retina processes this input signal efficiently by taking into account the statistics of the natural world. It has...

Unifying approaches to glass formation [Physics]

PNAS Early Edition Articles - Mon, 02/23/2015 - 14:05
The study of glass formation is largely framed by semiempirical models that emphasize the importance of progressively growing cooperative motion accompanying the drop in fluid configurational entropy, emergent elasticity, or the vanishing of accessible free volume available for molecular motion in cooled liquids. We investigate the extent to which these...

Labeling His-tagged proteins in living cells [Cell Biology]

PNAS Early Edition Articles - Mon, 02/23/2015 - 14:05
Small molecule-based fluorescent probes have been used for real-time visualization of live cells and tracking of various cellular events with minimal perturbation on the cells being investigated. Given the wide utility of the (histidine)6-Ni2+-nitrilotriacetate (Ni-NTA) system in protein purification, there is significant interest in fluorescent Ni2+-NTA–based probes. Unfortunately, previous Ni-NTA–based...

Histone titration by DNA triggers the Xenopus MBT [Developmental Biology]

PNAS Early Edition Articles - Mon, 02/23/2015 - 14:05
During early development, animal embryos depend on maternally deposited RNA until zygotic genes become transcriptionally active. Before this maternal-to-zygotic transition, many species execute rapid and synchronous cell divisions without growth phases or cell cycle checkpoints. The coordinated onset of transcription, cell cycle lengthening, and cell cycle checkpoints comprise the midblastula...

Nanomicellar drug to combat drug resistance [Applied Biological Sciences]

PNAS Early Edition Articles - Mon, 02/23/2015 - 14:05
Drug resistance and toxicity constitute challenging hurdles for cancer therapy. The application of nanotechnology for anticancer drug delivery is expected to address these issues and bring new hope for cancer treatment. In this context, we established an original nanomicellar drug delivery system based on an amphiphilic dendrimer (AmDM), which could...

Affective neurons in human subthalamus [Neuroscience]

PNAS Early Edition Articles - Mon, 02/23/2015 - 14:05
Both animal studies and studies using deep brain stimulation in humans have demonstrated the involvement of the subthalamic nucleus (STN) in motivational and emotional processes; however, participation of this nucleus in processing human emotion has not been investigated directly at the single-neuron level. We analyzed the relationship between the neuronal...

Selective transport in a microcompartment [Biochemistry]

PNAS Early Edition Articles - Mon, 02/23/2015 - 14:05
Bacterial microcompartments are widespread prokaryotic organelles that have important and diverse roles ranging from carbon fixation to enteric pathogenesis. Current models for microcompartment function propose that their outer protein shell is selectively permeable to small molecules, but whether a protein shell can mediate selective permeability and how this occurs are...

Modular CRISPR-Cas9 [Biochemistry]

PNAS Early Edition Articles - Mon, 02/23/2015 - 14:05
Cas9, an RNA-guided DNA endonuclease found in clustered regularly interspaced short palindromic repeats (CRISPR) bacterial immune systems, is a versatile tool for genome editing, transcriptional regulation, and cellular imaging applications. Structures of Streptococcus pyogenes Cas9 alone or bound to single-guide RNA (sgRNA) and target DNA revealed a bilobed protein architecture...

Mutations in early follicular lymphoma progenitors [Genetics]

PNAS Early Edition Articles - Mon, 02/23/2015 - 14:05
Follicular lymphoma (FL) is incurable with conventional therapies and has a clinical course typified by multiple relapses after therapy. These tumors are genetically characterized by B-cell leukemia/lymphoma 2 (BCL2) translocation and mutation of genes involved in chromatin modification. By analyzing purified tumor cells, we identified additional novel recurrently mutated genes...

Tetramers reveal U1-70-specific CD4+ T cells [Immunology and Inflammation]

PNAS Early Edition Articles - Mon, 02/23/2015 - 14:05
Antigen-specific CD4+ T cells are implicated in the autoimmune disease systemic lupus erythematosus (SLE), but little is known about the peptide antigens that they recognize and their precise function in disease. We generated a series of MHC class II tetramers of I-Ek–containing peptides from the spliceosomal protein U1-70 that specifically...

Opsin genes in dragonflies [Evolution]

PNAS Early Edition Articles - Mon, 02/23/2015 - 14:05
Dragonflies are colorful and large-eyed animals strongly dependent on color vision. Here we report an extraordinary large number of opsin genes in dragonflies and their characteristic spatiotemporal expression patterns. Exhaustive transcriptomic and genomic surveys of three dragonflies of the family Libellulidae consistently identified 20 opsin genes, consisting of 4 nonvisual...

Cross-language differences in cortical dynamics [Neuroscience]

PNAS Early Edition Articles - Mon, 02/23/2015 - 14:05
How is language processed in the brain by native speakers of different languages? Is there one brain system for all languages or are different languages subserved by different brain systems? The first view emphasizes commonality, whereas the second emphasizes specificity. We investigated the cortical dynamics involved in processing two very...

Evolutionary consequences of heritable symbiosis [Colloquium Paper]

PNAS Early Edition Articles - Mon, 02/23/2015 - 14:05
Many eukaryotes have obligate associations with microorganisms that are transmitted directly between generations. A model for heritable symbiosis is the association of aphids, a clade of sap-feeding insects, and Buchnera aphidicola, a gammaproteobacterium that colonized an aphid ancestor 150 million years ago and persists in almost all 5,000 aphid species....

Regulation of insulin secretion by l-cysteine [Cell Biology]

PNAS Early Edition Articles - Mon, 02/23/2015 - 14:05
Increase in the concentration of plasma l-cysteine is closely associated with defective insulin secretion from pancreatic β-cells, which results in type 2 diabetes (T2D). In this study, we investigated the effects of prolonged l-cysteine treatment on glucose-stimulated insulin secretion (GSIS) from mouse insulinoma 6 (MIN6) cells and from mouse pancreatic...
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