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

Testimony to the Senate Judiciary Committee by the ERA Project at Columbia Law School and Constitutional Law Scholars on Joint Resolution S.J.Res. 4: Removing the Deadline for the Ratification of the Equal Rights Amendment

The Equal Rights Amendment Project at Columbia Law School (ERA Project) and the undersigned constitutional law scholars provide the following analysis of S.J.Res. 4, resolving to remove the time limit for the ratification of the Equal Rights Amendment (ERA) and declaring the ERA fully ratified

Assessing Retinal Structure In Complete Congenital Stationary Night Blindness and Oguchi Disease

Purpose To examine retinal structure and changes in photoreceptor intensity after dark adaptation in patients with complete congenital stationary night blindness and Oguchi disease. Design Prospective, observational case series. Methods We recruited 3 patients with complete congenital stationary night blindness caused by mutations in GRM6, 2 brothers with Oguchi disease caused by mutations in GRK1, and 1 normal control. Retinal thickness was measured from optical coherence tomography images. Integrity of the rod and cone mosaic was assessed using adaptive optics scanning light ophthalmoscopy. We imaged 5 of the patients after a period of dark adaptation and examined layer reflectivity on optical coherence tomography in a patient with Oguchi disease under light- and dark-adapted conditions. Results Retinal thickness was reduced in the parafoveal region in patients with GRM6 mutations as a result of decreased thickness of the inner retinal layers. All patients had normal photoreceptor density at all locations analyzed. On removal from dark adaptation, the intensity of the rods (but not cones) in the patients with Oguchi disease gradually and significantly increased. In 1 Oguchi disease patient, the outer segment layer contrast on optical coherence tomography was 4-fold higher under dark-adapted versus light-adapted conditions. Conclusions The selective thinning of the inner retinal layers in patients with GRM6 mutations suggests either reduced bipolar or ganglion cell numbers or altered synaptic structure in the inner retina. Our finding that rods, but not cones, change intensity after dark adaptation suggests that fundus changes in Oguchi disease are the result of changes within the rods as opposed to changes at a different retinal locus

ERA Project OLC Letter

The Equal Rights Amendment Project at Columbia Law School (“ERA Project”) and the undersigned scholars submit this letter at the request of your office to provide legal analysis of the January 6, 2020 Department of Justice Office of Legal Counsel Memorandum to the National Archives and Records Administration on the Equal Rights Amendment (“2020 OLC Memo”)

Validation of a liquid chromatography tandem mass spectrometry (LC-MS/MS) method to detect cannabinoids in whole blood and breath.

Background The widespread availability of cannabis raises concerns regarding its effect on driving performance and operation of complex equipment. Currently, there are no established safe driving limits regarding ∆9-tetrahydrocannabinol (THC) concentrations in blood or breath. Daily cannabis users build up a large body burden of THC with residual excretion for days or weeks after the start of abstinence. Therefore, it is critical to have a sensitive and specific analytical assay that quantifies THC, the main psychoactive component of cannabis, and multiple metabolites to improve interpretation of cannabinoids in blood; some analytes may indicate recent use. Methods A liquid chromatography tandem mass spectrometry (LC-MS/MS) method was developed to quantify THC, cannabinol (CBN), cannabidiol (CBD), 11-hydroxy-THC (11-OH-THC), (±)-11-nor-9-carboxy-Δ9-THC (THCCOOH), (+)-11-nor-Δ9-THC-9-carboxylic acid glucuronide (THCCOOH-gluc), cannabigerol (CBG), and tetrahydrocannabivarin (THCV) in whole blood (WB). WB samples were prepared by solid-phase extraction (SPE) and quantified by LC-MS/MS. A rapid and simple method involving methanol elution of THC in breath collected in SensAbues® devices was optimized. Results Lower limits of quantification ranged from 0.5 to 2 μg/L in WB. An LLOQ of 80 pg/pad was achieved for THC concentrations in breath. Calibration curves were linear (R2&gt;0.995) with calibrator concentrations within ±15% of their target and quality control (QC) bias and imprecision ≤15%. No major matrix effects or drug interferences were observed. Conclusions The methods were robust and adequately quantified cannabinoids in biological blood and breath samples. These methods will be used to identify cannabinoid concentrations in an upcoming study of the effects of cannabis on driving

Water Rights in Wilderness: The Influence of Reserved Rights Language on Protection of Wilderness Water in Arizona and Colorado

1 v. (various pagings) : ill. (some color), color maps ; 29 cm Executive summary -- Introduction -- Background and scope -- Compilation and analysis of water rights data -- Protection of wilderness water : federal agency response to statutory language -- Final observations -- Appendix A. Legislative history of Arizona and Colorado wilderness legislation -- Appendix B. State water law : Arizona and Colorado -- Appendix C. Study methods -- Appendix D. Agency policies.https://scholar.law.colorado.edu/books_reports_studies/1015/thumbnail.jp

Morphological and Molecular Characterizations of Psychrophilic Fungus Geomyces destructans from New York Bats with White Nose Syndrome (WNS)

Background: Massive die-offs of little brown bats (Myotis lucifugus) have been occurring since 2006 in hibernation site

Lightcurve analysis and rotation period of 6372 Walker

6372 Walker is a main-belt asteroid discovered in 1985 by C.S. Shoemaker at Palomar Observatory and was last observed in May of 2018 (JPL, 2019). It has a diameter of 42.13 km and orbital period of 5.68 yr.peer-reviewe