Genome-wide analysis demonstrates conserved localization of messenger RNAs to mitotic microtubules

RNA localization is of critical importance in many fundamental cell biological and developmental processes by regulating the spatial control of gene expression. To investigate how spindle-localized RNAs might influence mitosis, we comprehensively surveyed all messenger RNAs (mRNAs) that bound to microtubules during metaphase in both Xenopus laevis egg extracts and mitotic human cell extracts. We identify conserved classes of mRNAs that are enriched on microtubules in both human and X. laevis. Active mitotic translation occurs on X. laevis meiotic spindles, and a subset of microtubule-bound mRNAs (MT-mRNAs) associate with polyribosomes. Although many MT-mRNAs associate with polyribosomes, we find that active translation is not required for mRNA localization to mitotic microtubules. Our results represent the first genome-wide survey of mRNAs localized to a specific cytoskeletal component and suggest that microtubule localization of specific mRNAs is likely to function in mitotic regulation and mRNA segregation during cell division

The impact of three evidence-based programmes delivered in public systems in Birmingham, UK

The Birmingham Brighter Futures strategy was informed by epidemiological data on child well-being and evidence on “what works,” and included the implementation and evaluation of three evidence-based programmes in regular children’s services systems, as well as an integrated prospective cost-effectiveness analysis (reported elsewhere). A randomised controlled trial (RCT) of the Incredible Years BASIC parenting programme involved 161 children aged three and four at risk of a social-emotional or behavioural disorder. An RCT of the universal PATHS social-emotional learning curriculum involved children aged four–six years in 56 primary schools. An RCT of the Level 4 Group Triple-P parenting programme involved parents of 146 children aged four–nine years with potential social-emotional or behavioural disorders. All three studies used validated standardised measures. Both parenting programme trials used parentcompleted measures of child and parenting behaviour. The school-based trial used teacher reports of children’s behaviour, emotions, and social competence. Incredible Years yielded reductions in negative parenting behaviours among parents, reductions in child behaviour problems, and improvements in children’s relationships. In the PATHS trial, modest improvements in emotional health and behavioural development after one year disappeared by the end of year two. There were no effects for Triple-P. Much can be learned from the strengths and limitations of the Birmingham experience

RNA Stimulates Aurora B Kinase Activity during Mitosis

Accurate chromosome segregation is essential for cell viability. The mitotic spindle is crucial for chromosome segregation, but much remains unknown about factors that regulate spindle assembly. Recent work implicates RNA in promoting proper spindle assembly independently of mRNA translation; however, the mechanism by which RNA performs this function is currently unknown. Here, we show that RNA regulates both the localization and catalytic activity of the mitotic kinase, Aurora-B (AurB), which is present in a ribonucleoprotein (RNP) complex with many mRNAs. Interestingly, AurB kinase activity is reduced in Xenopus egg extracts treated with RNase, and its activity is stimulated in vitro by RNA binding. Spindle assembly defects following RNase-treatment are partially rescued by inhibiting MCAK, a microtubule depolymerase that is inactivated by AurB-dependent phosphorylation. These findings implicate AurB as an important RNA-dependent spindle assembly factor, and demonstrate a translation-independent role for RNA in stimulating AurB

Drosophila CENP-A Mutations Cause a BubR1- Dependent Early Mitotic Delay without Normal Localization of Kinetochore Components

The centromere/kinetochore complex plays an essential role in cell and organismal viability by ensuring chromosome movements during mitosis and meiosis. The kinetochore also mediates the spindle attachment checkpoint (SAC), which delays anaphase initiation until all chromosomes have achieved bipolar attachment of kinetochores to the mitotic spindle. CENP-A proteins are centromere-specific chromatin components that provide both a structural and a functional foundation for kinetochore formation. Here we show that cells in Drosophila embryos homozygous for null mutations in CENP-A (CID) display an early mitotic delay. This mitotic delay is not suppressed by inactivation of the DNA damage checkpoint and is unlikely to be the result of DNA damage. Surprisingly, mutation of the SAC component BUBR1 partially suppresses this mitotic delay. Furthermore, cid mutants retain an intact SAC response to spindle disruption despite the inability of many kinetochore proteins, including SAC components, to target to kinetochores. We propose that SAC components are able to monitor spindle assembly and inhibit cell cycle progression in the absence of sustained kinetochore localization

The calcium-dependent ribonuclease XendoU promotes ER network formation through local RNA degradation

How cells shape and remodel organelles in response to cellular signals is a poorly understood process. Using Xenopus laevis egg extract, we found that increases in cytosolic calcium lead to the activation of an endogenous ribonuclease, XendoU. A fraction of XendoU localizes to the endoplasmic reticulum (ER) and is required for nuclear envelope assembly and ER network formation in a catalysis-dependent manner. Using a purified vesicle fusion assay, we show that XendoU functions on the surface of ER membranes to promote RNA cleavage and ribonucleoprotein (RNP) removal. Additionally, RNA removal from the surface of vesicles by RNase treatment leads to increased ER network formation. Using human tissue culture cells, we found that hEndoU localizes to the ER, where it promotes the formation of ER tubules in a catalysis-dependent manner. Together, these results demonstrate that calcium-activated removal of RNA from membranes by XendoU promotes and refines ER remodeling and the formation of tubular ER

Xenopus tropicalis egg extracts provide insight into scaling of the mitotic spindle

The African clawed frog Xenopus laevis has been instrumental to investigations of both development and cell biology, but the utility of this model organism for genetic and proteomic studies is limited by its long generation time and unsequenced pseudotetraploid genome. Xenopus tropicalis, which is a small, faster-breeding relative of X. laevis, has recently been adopted for research in developmental genetics and functional genomics, and has been chosen for genome sequencing. We show that X. tropicalis egg extracts reconstitute the fundamental cell cycle events of nuclear formation and bipolar spindle assembly around exogenously added sperm nuclei. Interestingly, X. tropicalis spindles were ∼30% shorter than X. laevis spindles, and mixing experiments revealed a dynamic, dose-dependent regulation of spindle size by cytoplasmic factors. Measurements of microtubule dynamics revealed that microtubules polymerized slower in X. tropicalis extracts compared to X. laevis, but that this difference is unlikely to account for differences in spindle size. Thus, in addition to expanding the range of developmental and cell biological experiments, the use of X. tropicalis provides novel insight into the complex mechanisms that govern spindle morphogenesis

Mixed moments of characteristic polynomials of random unitary matrices

Following the work of Conrey, Rubinstein and Snaith and Forrester and Witte we examine a mixed moment of the characteristic polynomial and its derivative for matrices from the unitary group U(N) (also known as the CUE) and relate the moment to the solution of a Painleve differential equation. We also calculate a simple form for the asymptotic behaviour of moments of logarithmic derivatives of these characteristic polynomials evaluated near the unit circle

Prioritizing improvements to truck driver vision

This report presents the results of a three-part study of truck driver exterior vision and its safety consequences. In part one, crash data are analyzed to document vision-related truck crash issues. About 20% of truck-initiated crashes occur in configurations in which limitations to truck driver vision may have been an important factor contributing to the crash. Right-going lane changes and turns account for more than half of these crashes. On average, right-going truck-initiated crashes are about 4.5 times more likely than left-going crashes. Non-motorists killed in startup and right-turn crashes were nearly all adults and tend to be older the pedestrians struck in other crash modes, suggesting that near-field truck vision analyses should focus on adults rather than children. Over half of pedestrians involved in start-up crashes are over age 65. An experimental study showed that driver performance in detecting lane-change conflicts was directionally consistent with the findings from the crash data. Drivers took longer to detect conflicts on the right side of the vehicle than on the left. The longest reaction times were observed when the target vehicle was directly to the right of the cab, suggesting that detecting a conflict in this area is most difficult for drivers. Drivers also made more errors on the right side of the vehicle, including several failures to detect a vehicle directly to the right of the cab. Based on these findings, a prioritized set of vision zones was developed. The highest priority for improvements to driver vision is the area directly to the right of the truck cab. This area represents the most likely position of a crash partner at the truck driver’s decision point in right lane-change crashes and is also the pre-crash position of many non-motorists involved in right turn and start up crashes. This report presents a new approach to evaluating exterior vision from truck cabs. The method differs from previous approaches, e.g., SAE J1750, by providing an aggregate score that is related to a specific crash-safety issue. The method is based on the visibility of standing adult pedestrians, and hence addresses the specific problem of pedestrian involvement in start up and right turn crashes. The experimental paradigm presented in Section 3 also represents a promising approach to evaluating the quality of exterior vision provided by alternative vision systems. The time drivers require to determine if a conflict exists provides a sensitive measure of the difficulty of the task. The parallels between the findings of the experimental study and the crash data analysis support the validity of the experimental approach. This method could be applied to evaluate alternative mirror systems, camera-based systems, and other technologies that might be developed to address the priorities established in this report.International Truck and Engine Corporationhttp://deepblue.lib.umich.edu/bitstream/2027.42/83927/1/102737.pd

Magnetic ordering above room temperature in the sigma-phase of Fe66V34

Magnetic properties of four sigma-phase Fe_(100-x)V_x samples with 34.4<x<55.1 were investigated by Mossbauer spectroscopy and magnetic measurements in the temperature interval 5-300 K. Four magnetic quantities viz. hyperfine field, Curie temperature, magnetic moment and susceptibility were determined. The sample containing 34.4 at% V was revealed to exhibit the largest values found up to now for the sigma-phase for average hyperfine field, B = 12.1 T, average magnetic moment per Fe atom, m = 0.89 mB, and Curie temperature, TC = 315.5 K. The quantities were shown to be strongly correlated with each other. In particular, TC is linearly correlated with m with a slope of 406.5 K/mB, as well as B is so correlated with m yielding 14.3 T/mB for the hyperfine coupling constant.Comment: 15 pages, 11 figures, 1 tabl

Mixed moments of characteristic polynomials of random unitary matrices

Following the work of Conrey, Rubinstein and Snaith \cite{kn:crs06} and Forrester and Witte \cite{kn:forwit06} we examine some mixed moments of the characteristic polynomial and its derivative for matrices from the unitary group $U(N)$ (also known as the CUE) and relate the moments to solutions of differential equations