Microtubules are organized independently of the centrosome in Drosophila neurons

<p>Abstract</p> <p>Background</p> <p>The best-studied arrangement of microtubules is that organized by the centrosome, a cloud of microtubule nucleating and anchoring proteins is clustered around centrioles. However, noncentrosomal microtubule arrays are common in many differentiated cells, including neurons. Although microtubules are not anchored at neuronal centrosomes, it remains unclear whether the centrosome plays a role in organizing neuronal microtubules. We use <it>Drosophila </it>as a model system to determine whether centrosomal microtubule nucleation is important in mature neurons.</p> <p>Results</p> <p>In developing and mature neurons, centrioles were not surrounded by the core nucleation protein γ-tubulin. This suggests that the centrioles do not organize functional centrosomes in <it>Drosophila </it>neurons <it>in vivo</it>. Consistent with this idea, centriole position was not correlated with a specific region of the cell body in neurons, and growing microtubules did not cluster around the centriole, even after axon severing when the number of growing plus ends is dramatically increased. To determine whether the centrosome was required for microtubule organization in mature neurons, we used two approaches. First, we used <it>DSas-4 </it>centriole duplication mutants. In these mutants, centrioles were present in many larval sensory neurons, but they were not fully functional. Despite reduced centriole function, microtubule orientation was normal in axons and dendrites. Second, we used laser ablation to eliminate the centriole, and again found that microtubule polarity in axons and dendrites was normal, even 3 days after treatment.</p> <p>Conclusion</p> <p>We conclude that the centrosome is not a major site of microtubule nucleation in <it>Drosophila </it>neurons, and is not required for maintenance of neuronal microtubule organization in these cells.</p

Evolutionary tracks for Betelgeuse

We have constructed a series of non-rotating quasi-hydrostatic evolutionary models for the M2 Iab supergiant Betelgeuse ($\alpha~Orionis$). Our models are constrained by multiple observed values for the temperature, luminosity, surface composition and mass loss for this star, along with the parallax distance and high resolution imagery that determines its radius. We have then applied our best-fit models to analyze the observed variations in surface luminosity and the size of detected surface bright spots as the result of up-flowing convective material from regions of high temperature in the surface convective zone. We also attempt to explain the intermittently observed periodic variability in a simple radial linear adiabatic pulsation model. Based upon the best fit to all observed data, we suggest a best progenitor mass estimate of $20 ^{+5}_{-3} M_\odot$ and a current age from the start of the zero-age main sequence of $8.0 - 8.5$ Myr based upon the observed ejected mass while on the giant branch.Comment: 27 pages, 11 figures, Revised per referee suggestions, Accepted for publication in the Astrophysical Journa

Respiration rate and volume measurements using wearable strain sensors.

Current methods for continuous respiration monitoring such as respiratory inductive or optoelectronic plethysmography are limited to clinical or research settings; most wearable systems reported only measures respiration rate. Here we introduce a wearable sensor capable of simultaneously measuring both respiration rate and volume with high fidelity. Our disposable respiration sensor with a Band-Aid© like formfactor can measure both respiration rate and volume by simply measuring the local strain of the ribcage and abdomen during breathing. We demonstrate that both metrics are highly correlated to measurements from a medical grade continuous spirometer on participants at rest. Additionally, we also show that the system is capable of detecting respiration under various ambulatory conditions. Because these low-powered piezo-resistive sensors can be integrated with wireless Bluetooth units, they can be useful in monitoring patients with chronic respiratory diseases in everyday settings

Protein Delivery of an Artificial Transcription Factor Restores Widespread Ube3a Expression in an Angelman Syndrome Mouse Brain.

Angelman syndrome (AS) is a neurological genetic disorder caused by loss of expression of the maternal copy of UBE3A in the brain. Due to brain-specific genetic imprinting at this locus, the paternal UBE3A is silenced by a long antisense transcript. Inhibition of the antisense transcript could lead to unsilencing of paternal UBE3A, thus providing a therapeutic approach for AS. However, widespread delivery of gene regulators to the brain remains challenging. Here, we report an engineered zinc finger-based artificial transcription factor (ATF) that, when injected i.p. or s.c., crossed the blood-brain barrier and increased Ube3a expression in the brain of an adult mouse model of AS. The factor displayed widespread distribution throughout the brain. Immunohistochemistry of both the hippocampus and cerebellum revealed an increase in Ube3a upon treatment. An ATF containing an alternative DNA-binding domain did not activate Ube3a. We believe this to be the first report of an injectable engineered zinc finger protein that can cause widespread activation of an endogenous gene in the brain. These observations have important implications for the study and treatment of AS and other neurological disorders

Functional genomics with a comprehensive library of transposon mutants for the sulfate-reducing bacterium Desulfovibrio alaskensis G20.

UnlabelledThe genomes of sulfate-reducing bacteria remain poorly characterized, largely due to a paucity of experimental data and genetic tools. To meet this challenge, we generated an archived library of 15,477 mapped transposon insertion mutants in the sulfate-reducing bacterium Desulfovibrio alaskensis G20. To demonstrate the utility of the individual mutants, we profiled gene expression in mutants of six regulatory genes and used these data, together with 1,313 high-confidence transcription start sites identified by tiling microarrays and transcriptome sequencing (5' RNA-Seq), to update the regulons of Fur and Rex and to confirm the predicted regulons of LysX, PhnF, PerR, and Dde_3000, a histidine kinase. In addition to enabling single mutant investigations, the D.&nbsp;alaskensis G20 transposon mutants also contain DNA bar codes, which enables the pooling and analysis of mutant fitness for thousands of strains simultaneously. Using two pools of mutants that represent insertions in 2,369 unique protein-coding genes, we demonstrate that the hypothetical gene Dde_3007 is required for methionine biosynthesis. Using comparative genomics, we propose that Dde_3007 performs a missing step in methionine biosynthesis by transferring a sulfur group to O-phosphohomoserine to form homocysteine. Additionally, we show that the entire choline utilization cluster is important for fitness in choline sulfate medium, which confirms that a functional microcompartment is required for choline oxidation. Finally, we demonstrate that Dde_3291, a MerR-like transcription factor, is a choline-dependent activator of the choline utilization cluster. Taken together, our data set and genetic resources provide a foundation for systems-level investigation of a poorly studied group of bacteria of environmental and industrial importance.ImportanceSulfate-reducing bacteria contribute to global nutrient cycles and are a nuisance for the petroleum industry. Despite their environmental and industrial significance, the genomes of sulfate-reducing bacteria remain poorly characterized. Here, we describe a genetic approach to fill gaps in our knowledge of sulfate-reducing bacteria. We generated a large collection of archived, transposon mutants in Desulfovibrio alaskensis G20 and used the phenotypes of these mutant strains to infer the function of genes involved in gene regulation, methionine biosynthesis, and choline utilization. Our findings and mutant resources will enable systematic investigations into gene function, energy generation, stress response, and metabolism for this important group of bacteria

Epithelial laminin α5 is necessary for distal epithelial cell maturation, VEGF production, and alveolization in the developing murine lung

AbstractLaminin α5 is prominent in the basement membrane of alveolar walls, airways, and pleura in developing and adult lung. Targeted deletion of laminin α5 in mice causes developmental defects in multiple organs, but embryonic lethality has precluded examination of the latter stages of lung development. To identify roles for laminin α5 in lung development, we have generated an inducible lung epithelial cell-specific Lama5 null (SP-CLama5fl/−) mouse through use of the Cre/loxP system, the human surfactant protein C promoter, and the reverse tetracycline transactivator. SP-CLama5fl/− embryos exposed to doxycycline from E6.5 died a few hours after birth. Compared to control littermates, SP-CLama5fl/− lungs had dilated, enlarged distal airspaces, but basement membrane ultrastructure was preserved. Distal epithelial cell differentiation was perturbed, with a marked reduction of alveolar type II cells and a virtual absence of type I cells. Cell proliferation was reduced and apoptosis was increased. Capillary density was diminished, and this was associated with a decrease in total lung VEGF production. Overall, these findings indicate that epithelial laminin α5, independent of its structural function, is necessary for murine lung development, and suggest a role for laminin α5 in signaling pathways that promote alveolar epithelial cell differentiation and VEGF expression

Tears in your beer: Gender differences in coping drinking motives, depressive symptoms and drinking

This study evaluates associations between coping drinking motives (CDM; drinking to regulate negative affect), depressive symptoms, and drinking behavior and extends the literature by also taking into account gender differences. Two hundred forty-three college students (Mean age = 22.93, SD = 6.29, 82% female) participated. Based on previous research, we expected that CDM would be positively associated with drinking and problems, particularly among those higher in depressive symptoms, as individuals experiencing higher levels of negative affect (i.e. depressive symptoms) and who drink to cope are likely to drink more and experience more alcohol-related problems. Lastly, based on established gender differences, we expected that CDM would be positively associated with drinking and problems, especially among females higher in depressive symptoms. Unexpectedly, findings suggested that CDMs were positively related to peak drinking, especially among those lower in depressive symptoms. Results further revealed a significant three-way interaction between CDM, depressive symptoms, and gender when predicting alcohol-related problems and drinking frequency. Specifically, we found that CDM were more strongly associated with problems among women who were lower in depressive symptoms; whereas CDM were more strongly associated with problems among men who were higher in depressive symptoms. These findings offer a more comprehensive depiction of the relationship between depressive symptoms, CDM, and drinking behavior by taking into account the importance of gender differences. These results provide additional support for considering gender when designing and implementing alcohol intervention strategies

Mice Lacking Gpr37 Exhibit Decreased Expression of the Myelin-Associated Glycoprotein Mag and Increased Susceptibility to Demyelination

GPR37 is an orphan G protein-coupled receptor that is predominantly expressed in the brain and found at particularly high levels in oligodendrocytes. GPR37 has been shown to exert effects on oligodendrocyte differentiation and myelination during development, but the molecular basis of these actions is incompletely understood and moreover nothing is known about the potential role(s) of this receptor under demyelinating conditions. To shed light on the fundamental biology of GPR37, we performed proteomic studies comparing protein expression levels in the brains of mice lacking GPR37 and its close relative GPR37-like 1 (GPR37L1). These studies revealed that one of the proteins most sharply decreased in the brains of Gpr37/Gpr37L1 double knockout mice is the myelin-associated glycoprotein MAG. Follow-up Western blot studies confirmed this finding and demonstrated that genetic deletion of Gpr37, but not Gpr37L1, results in strikingly decreased brain expression of MAG. Further in vitro studies demonstrated that GPR37 and MAG form a complex when expressed together in cells. As loss of MAG has previously been shown to result in increased susceptibility to brain insults, we additionally assessed Gpr37-knockout (Gpr37−/−) vs. wild-type mice in the cuprizone model of demyelination. These studies revealed that Gpr37−/− mice exhibit dramatically increased loss of myelin in response to cuprizone, yet do not show any increased loss of oligodendrocyte precursor cells or mature oligodendrocytes. These findings reveal that loss of GPR37 alters oligodendrocyte physiology and increases susceptibility to demyelination, indicating that GPR37 could be a potential drug target for the treatment of demyelinating diseases such as multiple sclerosis