Search

Pronuclear migration and formation of the first mitotic spindle depend upon assembly of a functional zygotic centrosome. For most animals, this involves both paternal and maternal contributions as sperm basal bodies are converted into centrosomes competent for microtubule nucleation through recruitment of egg proteins. Nek2B is a vertebrate NIMA-related protein kinase required for centrosome assembly, as its depletion from egg extracts delays microtubule aster formation from sperm basal bodies. Using Xenopus as a model system, we now show that protein expression of Nek2B begins during mid-oogenesis and increases further upon oocyte maturation. This is regulated, at least in part, at the level of protein translation. Nek2B protein is weakly phosphorylated in mitotic egg extracts but its recruitment to the sperm basal body, which occurs independently of its kinase activity, stimulates its phosphorylation, possibly through sequestration from a phosphatase present in mitotic egg cytoplasm. Importantly, although Nek2B is not required to organize acentrosomal microtubule asters, we show that addition of either active or kinase-dead recombinant Nek2B can restore centrosome assembly in a dose-dependent manner to a depleted extract. These results support a model in which maternal Nek2B acts to promote assembly of a functional zygotic centrosome in a kinase-independent manner. Keywords: Nek2; Cell cycle; Centrosome; Centriole: Mitosis; Oogenesis; Kinase; NIMA; Xenopus

Highlights • Males possess higher androgen (AR) expression than females. • AR content phosphorylation of AR is higher in females than males. • Glucocorticoid receptor (GR) phosphorylation is higher in males than females. • Skeletal muscle AR & GR may adjust phosphorylation based on circulating hormones. Abstract Purpose To determine if there is differential expression and phosphorylation of the androgen receptor (AR), glucocorticoid receptor (GR), and mitogen-activated protein kinases (MAPK) in skeletal muscle at rest between males and females. Methods Ten college-aged males (mean ± SD; age = 22 ± 2.4 yrs, ht = 175 ± 7 cm, body mass = 84.1 ± 11.8 kg) and ten females (mean ± SD; age = 20 ± 0.9 yrs; ht = 169 ± 7 cm; body mass = 67.1 ± 8.7 kg) reported to the laboratory following an overnight fast. Resting muscle biopsies were collected from the vastus lateralis and analyzed for total and phosphorylated GR (ser134, ser211, and ser226), total and phosphorylated AR (ser81, ser213, ser515, ser650), and total and phosphorylated MAPK (ERK, JNK, p38) via western blotting. A phosphorylation index (PI) was calculated to determine phosphorylated receptor expression after accounting for differences in total receptor content. Results Males had more total AR compared to females (+42 ± 4%; p < 0.001). Females had higher phosphorylation of ARser81 (+87 ± 11%; p = 0.001) and ser515 (+55 ± 13%; p = 0.019). However, when the phosphorylated ratios were corrected for differences in total AR expression (i.e. our PI), the overall phosphorylation at these sites were similar between sexes (ser515, males = 100% vs females 92%; ser81, males = 100% vs females = 107%). pGRser134 was higher in males compared to females (+50 ± 15%; p = 0.016). Phospho-p38 was higher in females compared to males (+5050 ± 16%; p < 0.001). Conclusion At rest, ARs and GRs are differentially phosphorylated at some, but not all sites when comparing males and females. Differential regulation of phosphorylated AR, GR, and p38 between males and females may have implications for the degree of muscle adaptations observed following resistance or endurance training. [ABSTRACT FROM AUTHOR]

Abstract Woody biomass cofiring with coal at existing pulverized-coal boilers is known to be a green energy source and is a low-expense alternative for pure coal combustion. Co-milling woody biomass particles (15 wt%) with coal particles (85 wt%) before burning at a boiler is a complex problem because large woody biomass particles (>300 μm) exit the milling system along with the fine particles. A Computational Particle Fluid Dynamics (CPFD) is used in this paper to present a novel analysis about the behavior of woody biomass particles as they are mixed with coal particles inside the classifier. To meet this objective, a model of SolidWorks of the milling system is defined using the Barracuda VR 17.1.0 software package. We made a C# programming code to analyze the post processing files of this simulation (base simulation); it showed that approximately none of the large particles of woody biomass nor any of the coal particles that exit along with fine particles swirl inside the classifier, and they exit the system in the product stream immediately after getting through the vanes. More importantly, only a few numbers of the exiting particles, regardless of their size, swirl inside the classifier. Manipulation of hardware can improve the classifier performance and leads to changes in the behavior of particles inside the classifier. However, changes in operating conditions cannot improve it significantly. Particle size distribution and the average flow rate of the product stream of the experiment and the base simulation match well. Highlights • Small hardware manipulations of the classifier can improve PSD of the product stream. • Tightening the vane angle will force particles to penetrate deeper into the classifier. • Lengthening the vortex finder makes large particles penetrate deep into the classifier. • Changes in operating conditions do not significantly impact the PSD of the product stream. [ABSTRACT FROM AUTHOR]

The operational performance of a Combustion Engineering 312 Raymond Bowl Mill has been investigated while milling a blend of Utah bituminous coal and prepared Manti-La Sal woody biomass. The research focuses on identifying the differences between the various biomass pretreatment methods regarding to co-milling behavior in a pilot scale bowl mill. Torrefied chips, torrefied pellets and steam exploded pellets were evaluated with a mass ratio of 15% biomass and 85% coal and compared to the measured pure coal mill performance. The milling process was monitored by recording the mill power requirement, inlet and outlet temperatures, fluidization air flow rates, fuel moisture content, milled product particle size distribution and SEM analysis of the particles. It was found that the blend with steam exploded pellets is the most suitable for co-milling due to it shows particle size distribution (PSD) close to the case of 100% coal while the grinding energy significantly decreased. A decreased power requirement was also noticeable when milling the blend with wood chips torrefied at 325 °C and pellets torrefied at 325 °C when compared with pure coal, but the mass fraction of large particles in the product increased for these blends. Co-milling coal with wood chips torrefied at 210 °C was not possible in these experiments. The pretreatment of woody biomass materials has the potential of co-firing at higher biomass rates in existing pulverized coal fired power plants without performing significant modifications. [ABSTRACT FROM AUTHOR]

This paper is concerned with deposition rates of coal ash on a vertical surface in a 100 kW rated down-flow laboratory coal combustor. At that scale, flow in the post flame where deposition occurs, is laminar, and the deposits on a vertical surface are similar to the early, sticky, inner deposits on horizontal surfaces. Therefore the problem addressed has relevance to understanding mechanisms of deposit formation in general. Experimental data presented here consist of particle size distributions of the ash aerosol, and time resolved measurements of the vertical deposit mass, for various controlled surface temperatures, one coal, and two combustion conditions: air-firing and oxy-firing with 50% inlet O 2 . Theory consisted of a transport model in which the criterion on whether an ash particle was captured, depended on a newly introduced “Thermophoresis Number”, Tp, which is the ratio of the time taken for the particle to contact the (cold) surface through thermophoresis, to that for the particle to pass by the surface. If Tp < 1 the particle is captured; otherwise it escapes. It is assumed that only those particles in the sub-micron vaporization mode are both subject to thermophoresis and will stick to the surface. Using calculated velocity and temperature fields in the fluid next to the vertical surface, and the Tp < 1 criterion alluded to above, it was possible to calculate a two-dimensional cross-sectional area that defined the area through which all particles that will contact the vertical surface must pass. Ash deposition rates so calculated were compared to experimental data. Quantitative agreement between theory and experiment was fair, considering the difficulties in accurately measuring deposition rates and in view of simplifications contained in the model. [ABSTRACT FROM AUTHOR]

Deposition of ash on heat transfer surfaces is a major factor in determining boiler performance. Deposits so formed consist of tightly bound “inside” deposits close to the heat transfer surface and loosely bound “outer” deposits that are easily dislodged. This paper describes research focusing on both the composition of inner and outer deposits, and also on the rate of deposition of the inner deposit layer. Presented are selected results from a wide ranging study concerned with mechanisms governing the formation of fouling deposits during air and oxy-coal combustion in a 100 kW test rig. The primary focus is on establishing a relationship between the size segregated composition of the coal ash aerosol, and the spatially resolved composition of the deposit layer, and this is accomplished by experimentation that addresses the impacts of conversion from air-firing to oxy-firing. Experiments involved three different coals (Powder River Basin or PRB, Illinois and a 60/40 Blend of Illinois and PRB), each burned under air- and oxy-coal combustion conditions. Data for the PRB coal suggested that changes in the composition of the inner deposit layer were caused by variations in sub-micron aerosol compositions, but that these occurred only when there were significant changes in flame temperature. An increase of the latter also led to increasing submicron particle concentrations and deposition rates. Although both aerosol and deposit compositions depended greatly on coal compositions, rates of deposition of the inner deposit layer correlate linearly with the concentration of the submicron aerosol in the flue gas, for all three coals, and under all air- and oxy-firing conditions for which data are available. This result suggests the amount rather than the (variable) composition of the submicron aerosol is important. There was no correlation between deposition rates and total ash concentrations. [ABSTRACT FROM AUTHOR]

Fouling and slagging processes are important in oxy-coal combustion processes because they greatly influence heat transfer and boiler performance. Ash partitioning processes are precursors to deposition processes and so in order to predict the latter one must have a good understanding of the former. This work involves a 100 kW rated down-fired oxy-fuel combustor outfitted with sophisticated ash aerosol and ash deposit sampling equipment. The work differs from that previously published, in that here we focus on the effects of changes in the composition and amounts of actual recycled flue gas (RFG) streams used in oxy-coal combustion, not using once through CO 2 , as before. Conditions examined here included oxy-coal combustion with three different RFG cleanup options and two different RFG amounts, and results consist of size segregated compositions of the ash aerosol and spatially resolved compositions within the deposits. In general, results suggested that oxy-combustion conditions did not cause major changes in ash partitioning, fouling and slagging. There are, however, changes in both the compositions of the ultrafine particles and in that of the inner layer of the deposits, and these were due to higher flame temperatures, when these occurred. These results are discussed and interpreted in detail. [ABSTRACT FROM AUTHOR]

Abstract: A two-color laser extinction method was used to collect measurements of soot volume fraction along a line of sight in air- and oxy-coal flames produced by two different burners. One was an Imjuiden block, variable swirl, 150kWth burner in the Burner Flow Reactor (BFR) at Brigham Young University. The second was a fixed-swirl vane (30°), 40kWth burner in the oxy-fuel combustor (OFC) at the University of Utah. In both burners, three stoichiometric ratios (SRs) and three oxygen volume fractions in the secondary oxidizer stream were investigated with measurements collected at three axial positions. In the OFC, two coals were investigated with simulated flue gas recirculation (FGR, O2 in CO2) and warm FGR. In the BFR, two coals were investigated, one with warm recycle (420°F) and the other with cold recycled flue gas. In the BFR, at high swirl (1.36), the flame was attached, and the amount of soot was found to correlate strongly with the secondary mass flow rate. Increasing flow rate produced shorter, more active flames and less soot indicating increased mixing. In the OFC, the flame was lifted. The air-fired flame was more lifted than the two oxy-fired flames (simulated FGR and warm FGR) and produced less soot. Soot for all flames decreased slightly with increased distance from the flame root where soot volume fraction was highest. The bituminous coal produced more soot than the sub-bituminous coal. Measured soot volume fractions ranged from 10 to 200×10−9. The data show that the local SR of the fuel rich region has a more significant impact than the overall SR and the type of oxidant (air, O2/FGR, or O2/CO2). [Copyright &y& Elsevier]

Summary: The purpose of this investigation was to determine if a single set of strenuous squat exercise would result in an acute oxidative stress, as demonstrated previously by a single sprint. Thirteen resistance trained men performed one set of 15 repetitions of barbell squats using 70% of one repetition maximum and a 30s maximal cycle sprint on two different occasions. The total work performed was calculated for each exercise bout. Heart rate, perceived exertion, blood lactate, protein carbonyls, 8-hydroxydeoxyguanosine, and malondialdehyde were measured before and within 1min following exercise. No differences were noted between the squat and sprint tests for total work, heart rate or perceived exertion. An exercise test by time interaction was evident for blood lactate with values greater following sprinting compared to squatting (P =0.0005). Postexercise protein carbonyls were not different between exercise tests but were elevated above rest (P =0.04) by 111% and 74% following sprinting and squatting, respectively, while 8-hydroxydeoxyguanosine and malondialdehyde were relatively unaffected by either exercise test. These data indicate that a single bout of strenuous squatting and sprinting performed by resistance trained men results in elevated protein carbonyls, while having little impact on 8-hydroxydeoxyguanosine or malondialdehyde during the immediate postexercise period. [Copyright &y& Elsevier]

Abstract: This paper presents a mercury oxidation data set suitable for validation of fundamental kinetic models of mercury chemistry and for mechanism development. Experimental facilities include a mercury reactor fitted with a 300-W, quartz-glass burner and a quartz reaction chamber. While operated with a temperature profile representative of a typical boiler, a residence time of 6s was achieved. Participating reacting species (chlorine, mercury) were introduced through the burner to produce a radical pool representative of real combustion systems. Speciated mercury measurements were performed using a Tekran 2537A Analyzer coupled with a conditioning system. Homogeneous mercury reactions involving chlorine have been investigated under two different temperature profiles producing quench rates of −210K/s and −440K/s. The larger quench rate produced 52% greater total oxidation than the lower quench at chlorine concentrations of 200ppm. The effect of reactor surface area on oxidation was also investigated. The quartz surfaces interacted with mercury only in the presence of chlorine and their overall effect was to weakly inhibit oxidation. The extent of oxidation was predicted using a detailed kinetic model. The model predicted the effects of quench rate and chlorine concentration shown in experimentation. [Copyright &y& Elsevier]

Abstract: Aneuploidy and chromosome instability are two of the most common abnormalities in cancer cells. They arise through defects in cell division and, specifically, in the unequal segregation of chromosomes between daughter cells during mitosis. A number of cell cycle dependent protein kinases have been identified that control mitotic progression and chromosome segregation. Some of these localize to the centrosome and regulate mitotic spindle formation. One such protein is Nek2, a member of the NIMA-related serine/threonine kinase family. Data are emerging that Nek2 is abnormally expressed in a wide variety of human cancers. In this review, we summarize current knowledge on the expression, regulation and function of Nek2, consider how Nek2 may contribute to chromosome instability, and ask whether it might make an attractive target for chemotherapeutic intervention in human cancer. [Copyright &y& Elsevier]

• Resistance exercise causes divergent phosphorylation responses at specific sites on the glucocorticoid receptor (GR). • Caffeine containing pre-workout supplementation (SUPP) increases circulating cortisol but did not influence GR phosphorylation. • SUPP lowered total androgen receptor (AR) post-exercise, but increased serine 515 phosphorylation. • Skeletal muscle AR & GR phosphorylation are sensitive to RE, but minimally influenced by SUPP. Consumption of caffeine or caffeine containing pre-workout supplements (SUPP) augments steroid hormone responses to resistance exercise (RE). However, the activation of glucocorticoid (GR) and androgen receptors (AR) following RE SUPP has not been investigated. The purpose of this study was to determine the influence of a pre-workout supplement on AR and GR phosphorylation following RE. Methods: In a randomized, counter-balanced, double-blind, placebo-controlled, within-subject crossover study, ten resistance-trained males ((X ¯ ±SD, age = 22 ± 2.4 yrs, hgt = 175 ± 7 cm, body mass = 84.1 ± 11.8 kg) performed four sets of 8 repetitions of barbell back squats at 75% of their 1-repetition maximum (1-RM) with two minutes of rest between sets and a fifth set of barbell back squats at 60% of 1-RM until concentric failure. A SUPP or flavor and color matched placebo (PL) was consumed 60-minutes prior to RE. Vastus lateralis muscle biopsies were obtained prior to supplementation at rest (BL), and ten minutes post-exercise (POST). Biopsies were analyzed for phosphorylated GR (ser134, ser211, and ser226) and phosphorylated AR (ser81, ser213, ser515, ser650) via western blotting. Results: pGRser134 decreased, and pGRser226 increased following RE (p < 0.05) with no difference between conditions (p > 0.05). pGRser211 was unchanged after RE (p > 0.05). pARser515 increased, and total AR expression decreased after RE (p < 0.05) in SUPP only. Testosterone and cortisol were not different between SUPP and PL at POST (p > 0.05). Conclusion: RE influences AR and GR phosphorylation, and SUPP minimally influences this response in the early recovery period. [ABSTRACT FROM AUTHOR]

Wagner syndrome is a rare inherited vitreoretinopathy. We describe 3 related patients with Wagner syndrome who presented with congenital glaucoma at age 3 months and required multiple surgical interventions to control their intraocular pressure. All experienced visual loss and glaucomatous optic neuropathy. [Copyright &y& Elsevier]

About 18% of all human cancers carry a mutation in the KRAS gene making it among the most sought-after anticancer targets. However, mutant KRas protein has proved remarkably undruggable. The recent approval of the first generation of RAS inhibitors therefore marks a seminal milestone in the history of cancer research. It also raises the predictable challenges of limited drug efficacies and acquired resistance. Hence, new approaches that improve our understanding of the tumorigenic mechanisms of oncogenic RAS within more physiological settings continue to be essential. Here, we have used the near-diploid hTERT RPE-1 cells to generate isogenic cell lines in which one of the endogenous KRAS alleles carries an oncogenic KRAS mutation at glycine 12. Cells with a KRASG12V/+, KRASG12C/+, or KRASG12D/+ genotype, together with WT KRASG12G(WT)/+ cells, reveal that oncogenic KRAS.G12X mutations increase cell proliferation rate and cell motility and reduced focal adhesions in KRASG12V/+ cells. Epidermal growth factor -induced phosphorylation of ERK and AKT was comparable between KRASG12V/+, KRASG12C/+, KRASG12D/+, and KRASG12G(WT)/+ cells. Interestingly, KRASG12X/+ cells showed varying responses to distinct inhibitors with the KRASG12V/+ and KRASG12D/+ cells more sensitive to hydroxyurea and MEK inhibitors, U0126 and trametinib, but more resistant to PI3K inhibitor, PIK-90, than the KRASG12G(WT)/+ cells. A combination of low doses of hydroxyurea and U0126 showed an additive inhibition on growth rate that was greater in KRASG12V/+ than WT cells. Collectively, these cell lines will be a valuable resource for studying oncogenic RAS signaling and developing effective anti-KRAS reagents with minimum cytotoxicity on WT cells. [ABSTRACT FROM AUTHOR]

Echinoderm microtubule-associated protein-like 4 (EML4)– anaplastic lymphoma kinase (ALK) oncogenic fusion proteins are found in approximately 5% of non–small cell lung cancers. Different EML4–ALK fusion variants exist with variant 3 (V3) being associated with a significantly higher risk than other common variants, such as variant 1 (V1). Patients with V3 respond less well to targeted ALK inhibitors, have accelerated rates of metastasis, and have poorer overall survival. A pathway has been described downstream of EML4–ALK V3 that is independent of ALK catalytic activity but dependent on the NEK9 and NEK7 kinases. It has been proposed that assembly of an EML4–ALK V3–NEK9–NEK7 complex on microtubules leads to cells developing a mesenchymal-like morphology and exhibiting enhanced migration. However, downstream targets of this complex remain unknown. Here, we show that the microtubule-based kinesin, Eg5, is recruited to interphase microtubules in cells expressing EML4–ALK V3, whereas chemical inhibition of Eg5 reverses the mesenchymal morphology of cells. Furthermore, we show that depletion of NEK7 interferes with Eg5 recruitment to microtubules in cells expressing EML4–ALK V3 and cell length is reduced, but this is reversed by coexpression of a phosphomimetic mutant of Eg5, in a site, S1033, phosphorylated by NEK7. Intriguingly, we also found that expression of Eg5-S1033D led to cells expressing EML4– ALK V1 adopting a more mesenchymal-like morphology. Together, we propose that Eg5 acts as a substrate of NEK7 in cells expressing EML4–ALK V3 and Eg5 phosphorylation promotes the mesenchymal morphology typical of these cells. [ABSTRACT FROM AUTHOR]

Summary The mammalian neocortex has undergone remarkable changes through evolution. A consequence of such rapid evolutionary events could be a trade-off that has rendered the brain susceptible to certain neurodevelopmental and neuropsychiatric conditions. We analyzed the exomes of 65 patients with the structural brain malformation periventricular nodular heterotopia (PH). De novo coding variants were observed in excess in genes defining a transcriptomic signature of basal radial glia, a cell type linked to brain evolution. In addition, we located two variants in human isoforms of two genes that have no ortholog in mice. Modulating the levels of one of these isoforms for the gene PLEKHG6 demonstrated its role in regulating neuroprogenitor differentiation and neuronal migration via RhoA, with phenotypic recapitulation of PH in human cerebral organoids. This suggests that this PLEKHG6 isoform is an example of a primate-specific genomic element supporting brain development. Graphical Abstract Highlights • Excess variants within basal radial glia transcriptomic signatures in cases of PH • PLEKHG6 primate-specific isoform mutated in a case of PH functions via RhoA • PLEKHG6 isoforms regulate features of neurogenesis • Modulation of the PLEKHG6 primate isoform reproduces features of PH in organoids O'Neill et al. show that variants in patients with PH are enriched within genes that define basal radial glia transcriptomic signatures and provide mechanistic evidence that a primate-specific isoform of one gene, mutated in a patient with PH, regulates neurogenesis. [ABSTRACT FROM AUTHOR]

Abstract A large number of genes encoding for tubulin proteins are expressed in the developing brain. Each is subject to specific spatial and temporal expression patterns. However, most are highly expressed in post-mitotic neurons during stages of neuronal migration and differentiation. The major tubulin subclasses (alpha- and beta-tubulin) share high sequence and structural homology. These globular proteins form heterodimers and subsequently co-assemble into microtubules. Microtubules are dynamic, cytoskeletal polymers which play key roles in cellular processes crucial for cortical development, including neuronal proliferation, migration and cortical laminar organisation. Mutations in seven genes encoding alpha-tubulin (TUBA1A), beta-tubulin (TUBB2A, TUBB2B, TUBB3 , TUBB4A , TUBB) and gamma-tubulin (TUBG1) isoforms have been associated with a wide and overlapping range of brain malformations or "Tubulinopathies". The majority of cortical phenotypes include lissencephaly, polymicrogyria, microlissencephaly and simplified gyration. Well-known hallmarks of the tubulinopathies include dysmorphism of the basal ganglia (fusion of the caudate nucleus and putamen with absence of the anterior limb of the internal capsule), midline commissural structures hypoplasia and/or agenesis (anterior commissure, corpus callosum and fornix), hypoplasia of the oculomotor and optic nerves, cerebellar hypoplasia or dysplasia and dysmorphism of the hind-brain structures. The cortical and extra-cortical brain phenotypes observed are largely dependent on the specific tubulin gene affected. In the present review, all the published data on tubulin family gene mutations and the associated cortical phenotypes are summarized. In addition, the most typical neuroimaging patterns of malformations of cortical development associated with tubulin gene mutations detected on the basis of our own experience are described. [ABSTRACT FROM AUTHOR]

The kinase Plk1 plays multiple roles in regulating mitotic progression, including stabilization of spindle poles, but its substrates are largely unknown. A new study by Yamamoto and coworkers has identified a centrosomal protein, Kizuna (Kiz), as a mitotic substrate of Plk1 (). Phosphorylation of Kiz ensures the integrity of spindle poles in the face of severe pulling forces exerted by the chromosome-attached spindle microtubules. [Copyright &y& Elsevier]

Objectives This study examined the potential for a motivational priming session to buffer the psychophysiological stress response to an ego-involving climate in a physical activity setting. Research in Achievement Goal Perspective Theory (AGPT) suggests that creating a caring/task-involving climate can have beneficial effects on participants in physical activity settings, even buffering the physiological response to stress. However, less is known about how individuals might buffer that response when an ego-involving climate is occurring beyond their control. Design Male college students (N = 38) between the ages of 18 and 30 years ( M age = 20.68 , S D = 2.66 ) were randomly assigned to either a control group with no exposure to AGPT or an experimental (i.e., AGPT motivational priming) group, and took part in an ego-involving juggling session. Psychophysiological stress responses (e.g., cortisol) were assessed. Method Prior to juggling, the experimental group received a motivational priming session that briefly reviewed the body of AGPT literature, while the control group received information on the history of Sport Psychology as a professional field. Cortisol was measured at five time points throughout the study via saliva samples. Participants also completed pre- and post-measures of self-reported anxiety and self-confidence (CSAI-2). Results Results showed a marked increase in cortisol (as measured by percent change from baseline) in the control group, but not the experimental group. Psychological responses were stable across groups. Conclusion Providing athletes and exercisers with nothing more than basic information on AGPT can reduce their physiological markers of psychosocial stress in ego-involving climates. Such education may be a beneficial practice for coaches, physical educators, and trainers. [ABSTRACT FROM AUTHOR]

Objectives The purpose of this study was to investigate whether motivational climates have a differential impact on adolescent psychological and physiological stress responses (i.e., salivary cortisol). It is important to investigate this relationship, as psychological stress and stress-responsive hormones have been implicated in a variety of biochemical processes deleterious to mental and physical health. Although youth consistently respond positively to caring, task-involving (C/TI) physical activity settings, ego-involving (EI) climates remain prevalent in youth sport contexts. Design Middle school students ( N = 47) were separated by gender and randomly assigned to either a C/TI or EI 30 min instructional juggling session. Method Salivary cortisol was measured at four times over the 3 h study, including one baseline ( t = 0 min; juggling session start) and three response measures ( t = +30, t = +45, and t = +60 min). Psychological stress and motivational responses were also examined, including anxiety, affect, enjoyment, and effort. Individual items were utilized to substantiate stress perceptions and assess psychological responses. Results Results revealed EI climate procured a significant rise in salivary cortisol and greater humiliation, self-consciousness, shame, negative affect, and anxiety, relative to the C/TI group, while adolescents in the C/TI group responded more favorably (e.g., greater effort and enjoyment). Conclusions These findings suggest the motivational climate can differentially impact adolescents’ stress responses, with EI climates eliciting both physiological and psychological stress responses in youth. In contrast, C/TI climates may buffer performance related stressors that accompany group achievement settings and yield a protective response. [ABSTRACT FROM AUTHOR]

Abstract: Ash deposition is still an unresolved problem when retrofitting existing air-fired coal power plants to oxy-fuel combustion. Experimental data are quite necessary for mechanism validation and model development. This work was designed to obtain laboratory combustor data on ash and deposits from oxy-coal combustion, and to explore the effects of oxy-firing on their formation. Two bituminous coals (Utah coal and Illinois coal) and one sub-bituminous coal (PRB coal) were burned on a down-fired combustor under both oxy- and air-firing. Two oxy-fired cases, i.e., 27vol% O2/73vol% CO2 and 32vol% O2/68vol% CO2, were selected to match the radiation flux and the adiabatic flame temperature of air combustion, respectively. Once-through CO2 was used to simulate fully cleaned recycled flue gas. The flue gas excess oxygen was fixed at 3vol%. For each case, both size-segregated fly ash and bulk fly ash samples were obtained. Simultaneously, ash deposits were collected on an especially designed un-cooled deposition probe. Ash particle size distributions and chemical composition of all samples were characterized. Data showed that oxy-firing had insignificant impacts on the tri-modal ash particle size distributions and composition size distributions in the size range studied. Bulk ash compositions also showed no significant differences between oxy- and air-firing, except for slightly higher sulfur contents in some oxy-fired ashes. The oxy-fired deposits were thicker than those from air-firing, suggesting enhanced ash deposition rates in oxy-firing. Oxy-firing also had apparent impacts on the deposit composition, especially for those components (e.g., CaO, Fe2O3, SO3, etc.) that could contribute significantly to ash deposition. Based on these results, aerodynamic changes in gas flow and changes in combustion temperature seemed more important than chemical changes of ash particles in determining deposit behavior during oxy-coal combustion. [Copyright &y& Elsevier]

Abstract: The purpose of this study was to investigate the effects of increased oxygen and carbon dioxide concentration on the formation of sulfur trioxide during oxy-coal combustion in two different types of pilot-scale furnaces: a pulverized-coal and a circulating-fluidized-bed-fired system. For pulverized-coal (PC) testing, concentrations of SO3 and SO2 were significantly higher for oxy-fired conditions as compared to air-fired conditions. For a high-sulfur Illinois bituminous coal, SO3 concentrations were 4–6 times greater on average. When firing a low-sulfur Utah Bituminous coal, SO3 concentrations were similar for oxy-firing vs. air-firing, and the overall levels were very low compared to the Illinois coal, consistent with differences in the fuel sulfur contents. PC-fired emissions on a normalized mass basis (mass SO3 per unit energy input) indicated higher SO3 emissions under air-fired conditions vs. oxy-firing, for both the Illinois and Utah coals. Circulating fluidized bed testing was also carried out using the low-sulfur Utah coal, and SO3 concentrations were notably higher for oxy-firing vs. air-firing, in contrast to the similar concentration levels observed for PC-firing. When compared on a normalized mass basis, the emissions were similar for both air- and oxy-firing, which is also in contrast to the PC-fired results for this coal. [Copyright &y& Elsevier]

Abstract: Real-time electrochemical measurements of corrosion rate were performed to evaluate the respective corrosion rates of one boiler waterwall material (SA210) and three boiler superheater materials (T22, P91 and 347H) while firing Utah Western bituminous, Illinois high-sulfur bituminous and Powder River Basin (PRB) sub-bituminous coals in a 1.5MW pulverized coal-fired furnace. The raw average measured corrosion rates were very low, between 0.0003 and 0.016mm/year (0.012 and 0.63mils/year) for most materials under air- and oxy-fired conditions. For some high-sulfur conditions measured corrosion rates were as high as 0.72mm/year (28mils/year). Waterwall corrosion rates decreased consistently when converting from air- to oxy-firing while superheater corrosion rates generally increased, although they were less than twice the air-fired rate under most conditions. Corrosion rates for the lower alloyed materials (SA210 and T22) increased significantly during transients from reducing to oxidizing conditions. Measured increases in the corrosion rate of 347H material under high sulfur and low temperature conditions, and associated decrease in corrosion rate at higher temperatures on this alloy, were consistent with the formation of trisulphates in the superheater deposits. The increase of corrosion rate with increased metal temperatures was demonstrated, as was the consistently repeatable nature of the observed results. [Copyright &y& Elsevier]

Abstract: Experiments were performed in a 1.5MW pilot-scale furnace to investigate the differences between air- and oxy-fired flame behavior from a pulverized coal oxy-research burner designed for flexible operating conditions. The flame behavior was characterized by recording video images of the flames and by measuring radiation intensity along the flame length. Various strategies relating air- and oxy-fired operation of the burner primary register were investigated where the oxy-fired burner primary mass, momentum and velocity were matched to the air-fired conditions. Matching either burner primary mass or momentum under oxy-fired conditions with air-fired conditions resulted in a flame stabilized within the quarl. Matching primary velocity with air-fired conditions resulted in a detached flame indicating a delay in flame ignition for the oxyfired conditions. A decrease in primary velocity of 13% was necessary in order to stabilize a flame within the quarl similar to the air-fired case. Additional experiments also showed a flame could be stabilized with no oxygen enrichment of the primary (∼3vol.%, dry O2 in the primary). Experiments where oxygen was injected at the burner face indicated injection at the boundary of the primary and secondary flow paths strongly attach a flame and injection at the coal rich primary flow path increased the radiative intensity of the flame. [Copyright &y& Elsevier]

This study examined correlations between type I percent myosin heavy chain isoform content (%MHC) and mechanomyographic amplitude (MMGRMS) during isometric muscle actions. Fifteen (age=21.63±2.39) participants performed 40% and 70% maximal voluntary contractions (MVC) of the leg extensors that included increasing, steady force, and decreasing segments. Muscle biopsies were collected and MMG was recorded from the vastus lateralis. Linear regressions were fit to the natural-log transformed MMGRMS-force relationships (increasing and decreasing segments) and MMGRMS was selected at the targeted force level during the steady force segment. Correlations were calculated among type I%MHC and the b (slopes) terms from the MMGRMS-force relationships and MMGRMS at the targeted force. For the 40% MVC, correlations were significant (P<0.02) between type I%MHC and the b terms from the increasing (r=-0.804) and decreasing (r=-0.568) segments, and MMGRMS from the steady force segment (r=-0.606). Type I%MHC was only correlated with MMGRMS during the steady force segment (P=0.044, r=-0.525) during the 70% MVC. Higher type I%MHC reduced acceleration in MMGRMS (b terms) during the 40% MVC and the amplitude during the steady force segments. The surface MMG signal recorded during a moderate intensity contraction provided insight on the contractile properties of the VL in vivo. [ABSTRACT FROM AUTHOR]

• Advanced Sensor Network (ASN) provides real time process data for dynamic operation. • Combustion calculations are performed to estimate fuel heating value from ASN data. • Heating values are also calculated using data-driven methods, showing 24% reduction in Root Mean Square Error (RMSE) when compared to the combustion calculation approach. • ASN data improves the accuracy of the data-driven heating value, reducing RMSE by 7%. • The proposed real-time NUHR method shows higher precision than other methods. Coal-fired utility boilers are being increasingly used as variable electricity generation to resolve the imbalance in the energy market from the expansion of intermittent renewable energy. The frequent transient operation required to meet residual energy demand has created a challenge for coal-fired units to operate efficiently. This work utilizes an advanced sensor network (ASN) to calculate net unit heat rate (NUHR) of a coal-fired boiler in real time through combustion calculations and statistical correlations to provide the tools for optimizing dynamic operation. Real-time heating values that were necessary to determine fuel input energy to calculate accurate NUHR were found using both fundamental and data-driven methods. Real-time NUHR shows distinct shifts that reflect changes in process conditions that will improve the ability to optimize transient operation. Data-driven heating value correlations had 24% lower root mean square error (RMSE) than the fundamental combustion calculation approach when compared to daily retrospective proximate analysis. The data-driven method RMSE improved by 7% with the inclusion of ASN data. Future work is to validate by comparing unit performance with and without the inclusion of NUHR as a control parameter for the dynamic neural network. [ABSTRACT FROM AUTHOR]

Abstract: This study examined the log-transformed mechanomyographic (MMGRMS) and electromyographic (EMGRMS) amplitude vs. force relationships for aerobically-trained (AT), resistance-trained (RT), and sedentary (SED) individuals. Subjects performed isometric ramp contractions from 5% to 90% maximal voluntary contraction. Muscle biopsies were collected and thigh skinfolds, MMG and EMG were recorded from the vastus lateralis muscle. Linear regression models were fit to the log-transformed EMGRMS and MMGRMS vs. force relationships. The slope (b coefficient) and the antilog of the y-intercept (a coefficient) were calculated. The AT group had the highest percentage of type I fiber area, the RT group had the highest percentage of type IIa fiber area, and the SED group had the highest percentage of type IIx fiber area. The a coefficients were higher for the AT group than the RT and SED groups in both the MMGRMS and EMGRMS vs. force relationships, whereas the b coefficients were lower for the AT group than the RT and SED groups only in the MMGRMS vs. force relationship. The group differences among the a coefficients may have reflected subcutaneous fat acting as a filter thereby reducing EMGRMS and MMGRMS. The lower b coefficients for the AT group in the MMGRMS patterns may have reflected fiber area-related differences in motor unit activation strategies. [ABSTRACT FROM AUTHOR]

This work details a model for evaluating the relative ash deposition propensity of various solid fuels without the complicated spatial considerations included in CFD modeling. Four deposition mechanisms are included, namely: inertial impaction, thermophoresis, condensation, and eddy impaction. This model has been validated and shown to effectively predict ash deposit rates for a wide range of solid fuels including coal, biomass, and their blends, burned in a 100 kW rated downflow combustor. Specifically, this work presents and compares two separate models for the sticking efficiency of impacting ash particles on a coupon surface: the melt fraction stickiness model (MFSM), which is developed here and includes a novel approach to determine sticking efficiency, and the kinetic energy stickiness model (KESM), an existing model used for comparison. To apply the MFSM model, the equilibrium composition of vapor species are calculated by thermodynamic modeling using FactSage. By comparing the root-mean-square-errors of the MFSM and KESM over the wide variety of fuels, it is shown that the MFSM is more accurate than the KESM in predicting the ash deposit rate. This shows that NaCl and KCl are expected to be the main alkali vapor species in the flue gas, for the fuels evaluated. • The model helps the operators of utility boilers predict the relative deposition rate. • The condensation creates a sticky layer that enhances the sticking efficiency. • Performace of the MFSM model is much better than the KESM model. • The model is validated with the experimental data of a wide range of solid fuels. • Inertial impaction is the dominant mechanism of ash deposit formation in Ө = 0. [ABSTRACT FROM AUTHOR]

[Display omitted] • Biomass and coal blends were co-fired to study synergistic SO 2 emission reduction. • Calcium and potassium in the biomass ash absorbed the SO 2 from the flue gas. • Sulfur retained in ash was low for pure coal and biomass and high for middle blends. • FactSage thermodynamic simulation results matched well with the experimental results. • Co-firing biomass with coal can lower the flue gas desulfurization costs. The objective of this study was to understand the synergistic effect of sulfur dioxide (SO 2) emission reduction during the combustion of biomass-coal blends in comparison to pure coal by recording the gaseous SO 2 concentrations, analyzing the composition of combustion ash by energy dispersive X-ray spectroscopy (EDS) and X-ray diffraction (XRD), and simulating and verifying the fate of sulfur by a thermodynamic equilibrium software (FactSage). In Set A experiments, five combinations of coal and steam-exploded biomass (100/0, 75/25, 50/50, 25/75, 0/100 in percentages by mass) were co-fired in a 1.5 MW th pilot-scale combustor. In Set B, pure coal (100/0) and an 85/15 percent mass blend of coal and torrefied biomass were co-fired in a 471 MW e utility boiler. Woody biomass contains lower amounts of sulfur compared to coal and the linear lowering of SO 2 emissions as a result of co-firing is called the dilution effect. For Set A tests, FactSage predicted, and ash analysis confirmed that calcium was primarily responsible for the synergistic emission reduction (beyond dilution effect) in all the blends, except in pure biomass, where potassium was responsible. During pure coal combustion, 41.1% of the sulfur in the system was absorbed in the ash, compared to 97.0% during pure biomass testing. In Set B tests, the 85/15 coal-biomass blend, showed a 28.1% reduction in SO 2 emissions along with a 22.1% reduction in the lime slurry utilization at flue gas desulfurization (FGD) towers compared to pure coal, which is equivalent to saving 7.4 L of lime slurry per MW e -hour. The results suggest that blending woody biomass with coal can help coal-fired utility boilers meet environmental emission standards and reduce desulfurization costs. These results are important since the current literature is deficient in research conducted at suspension-fired full-scale boilers to reduce SO 2 emissions by co-firing coal and biomass blends. [ABSTRACT FROM AUTHOR]

Abstract It remains unclear if the sizes of higher-threshold motor units (MU) are associated with muscular strength and power. Therefore, the purpose of this study was to examine sex-related differences in muscle cross-sectional area (mCSA), percent myosin heavy chain (%MHC) isoform expression, and the MU action potential amplitudes (MUAP AMPS)-recruitment threshold (RT) relationships of the vastus lateralis and isometric peak torque, isokinetic peak torque and mean power at 1.05 rad·s−1 of the leg extensors. Surface electromyographic decomposition techniques were used to quantify MUAP AMPS recorded during isometric muscle actions at 70% of maximal voluntary contractions and regressed against RTs with the slopes calculated. Ultrasound images were used to measure mCSA. Males had greater slopes from the MUAP AMP -RT relationship than the females (P < 0.05). The greater slopes likely reflected larger higher-threshold MUs for the males. The mCSAs and slopes from the relationships were strongly correlated with isometric and isokinetic peak torque and isokinetic mean power (r = 0.78–0.82), however, type I %MHC isoform was only moderately correlated with isometric peak torque (r = −0.54). The results indicated that sex-related differences in muscular strength and power were associated more so with the sizes of the higher-threshold MUs (slopes) and mCSA than MHC isoforms. The amount of cross-bridge activity within muscle fibers that comprise higher-threshold MUs may be the primary contributor to muscular strength and power rather than the contractile properties of the muscle. [ABSTRACT FROM AUTHOR]

Utilization of renewable energy sources to minimize the environmental impact of energy production has changed the way utility boilers operate, requiring frequent load cycling between full load and partial loads as low as 30%. Dynamic operation of coal-fired utility boilers significantly reduces boiler efficiency when compared to steady state at full load. Data-driven plant optimization has shown success with coal-fired utility boilers under dynamic operating conditions. The purpose of this work was to create an Advanced Sensor Network (ASN) to provide more extensive real-time data to inform dynamic plant optimization of Net Unit Heat Rate (NUHR). The ASN consists of gas sampling grids in the convective pass of the boiler and downstream of the air heater. These sampling grids allow for quantification of spatial variation of flue gas within the boiler and calculation of mass-weighted composition of flue gas through the combination of composition, velocity, and temperature measurements. The comparison of O 2 between the inlet and outlet of the air heater is used to calculate air leakage in real time. Flue gas composition and air heater leakage are both important factors in boiler efficiency and NUHR. The results of this work support the value of mass-weighted averages for determining flue gas composition accurately. The measurements from the ASN show increased composition stratification during dynamic operation, with an average standard deviation 38% higher than observed during steady-state operation. Air heater leakage was also observed to increase from 2.8% to 5.1% following a load change. Prior to the installation of the ASN, these data would not have been available for dynamic control. These real-time data will be leveraged to calculate and optimize for NUHR during dynamic operation in future work. [Display omitted] • Advanced Sensor Network provides real time process data for dynamic operation. • Sampling grids are used to calculate mass-weighted averages of composition. • Stratification of flue gases is observed to increase during ramping cycles. • Percent air heater leakage increases during load change and at low load. [ABSTRACT FROM AUTHOR]

• First study to estimate myosin heavy chain in females via mechanomyography (MMG). • A combination of MMG variables estimated myosin heavy chain (MHC) with 81% accuracy. • MMG may noninvasively assess MHC of the vastus lateralis in females. This study examined relationships between percent myosin heavy chain (%MHC) expression and mechanomyographic amplitude (MMG RMS). Fifteen females (age ± SD=21.3 ± 5.3 yrs) completed isometric trapezoidal contractions at 30% and 70% maximal voluntary contraction (MVC). MMG was recorded from the vastus lateralis (VL). Participants gave a muscle biopsy of the VL post-testing. MMG RMS -torque relationships during the linearly varying segments were log-transformed and linear regressions were applied to calculate b terms (slopes). For the steady torque segment, MMG RMS was averaged. Correlations were performed for type I%MHC with the MMG variables. Multiple regression was utilized to examine prediction equations for type I%MHC. Type I%MHC was significantly correlated with the b terms during the increasing segment of the 70% MVC (p = 0.003; r = -0.718), and MMG RMS during steady torque at 30% (p = 0.008; r = -0.652) and 70% MVC (p = 0.040; r = -0.535). Type I%MHC reduced the linearity of the MMG RMS -torque relationship during the high-intensity linearly increasing segment, and MMG RMS at a low- and high-intensity steady torque. A combination of MMG variables estimated type I%MHC expression with 81.2% accuracy. MMG recorded during a low- and high-intensity isometric trapezoidal contraction may offer a simple, noninvasive test for estimating type I%MHC expression of the VL in sedentary females. [ABSTRACT FROM AUTHOR]

• Demonstrates a novel control algorithm for a coal power plant under load-following. • Dynamic optimization using long short-term memory with particle swarm optimization. • Machine learning-based optimization of coal-fired power plant. • Increased efficiency in response to more intermittent renewable penetration. • Comparison using simulated physics-based coal-fired power plant model. The increasing fraction of intermittent renewable energy in the electrical grid is resulting in coal-fired boilers now routinely ramp up and down. The current state-of-the-art operation for such boilers is to apply steady-state, neural network-based optimization to make control decisions in real-time, and this work demonstrates the feasibility of extending this to dynamic, neural network-based optimization using a long short-term memory neural network. A simplified numerical simulation of a t-fired coal boiler and supporting equipment is used to represent a real plant subjected to both steady-state, neural network-based optimization and dynamic, neural network-based optimization. Using the same intervals and a particle swarm optimization algorithm, the dynamic optimization outperforms the steady-state optimization and realizes up to 4.58% improvement in thermal efficiency. Dynamic optimization with a long short-term memory neural network is shown to both be feasible and beneficial for operation of a coal-fired boiler under changing load. [ABSTRACT FROM AUTHOR]

Abstract: Introduction: The purpose of this study was to examine possible correlations between skinfold thicknesses and the a terms from the log-transformed electromyographic (EMGRMS) and mechanomyographic amplitude (MMGRMS)-force relationships, EMG M-Waves, and MMG gross lateral movements (GLM). Methods: Forty healthy subjects performed a 6-s isometric ramp contraction from 5% to 85% of their maximal voluntary contraction with EMG and MMG sensors placed on the vastus lateralis (VL) and rectus femoris (RF). A single electrical stimulus was applied to the femoral nerve to record the EMG M-waves and MMG GLMs. Skinfold thickness was assessed at the site of each electrode. Pearson’s product correlation coefficients were calculated comparing skinfold thicknesses with the a terms from the log-transformed EMGRMS-and MMGRMS -force relationships, EMG M-waves, and MMG GLMs. Results: There were no significant cor1relations (p >0.05) between the a terms and skinfold thicknesses for the RF and VL from the EMGRMS and MMGRMS-force relationships. However, there were significant correlations (p <0.05) between skinfold thicknesses and the EMG M-waves and MMG GLMs for the RF (r =−0.521, −0.376) and VL (r =−0.479, −0.484). Discussion: Relationships were only present between skinfold thickness and the amplitudes of the EMG and MMG signals during the non-voluntary muscle actions. [Copyright &y& Elsevier]

Summary: Timely and accurate assembly of the mitotic spindle is critical for the faithful segregation of chromosomes, and centrosome separation is a key step in this process. The timing of centrosome separation varies dramatically between cell types; however, the mechanisms responsible for these differences and its significance are unclear. Here, we show that activation of epidermal growth factor receptor (EGFR) signaling determines the timing of centrosome separation. Premature separation of centrosomes decreases the requirement for the major mitotic kinesin Eg5 for spindle assembly, accelerates mitosis, and decreases the rate of chromosome missegregation. Importantly, EGF stimulation impacts upon centrosome separation and mitotic progression to different degrees in different cell lines. Cells with high EGFR levels fail to arrest in mitosis upon Eg5 inhibition. This has important implications for cancer therapy because cells with high centrosomal response to EGF are more susceptible to combinatorial inhibition of EGFR and Eg5. [Copyright &y& Elsevier]

Leucine zippers are oligomerization domains used in a wide range of proteins. Their structure is based on a highly conserved heptad repeat sequence in which two key positions are occupied by leucines. The leucine zipper of the cell cycle-regulated Nek2 kinase is important for its dimerization and activation. However, the sequence of this leucine zipper is most unusual in that leucines occupy only one of the two hydrophobic positions. The other position, depending on the register of the heptad repeat, is occupied by either acidic or basic residues. Using NMR spectroscopy, we show that this leucine zipper exists in two conformations of almost equal population that exchange with a rate of 17 s-1. We propose that the two conformations correspond to the two possible registers of the heptad repeat. This hypothesis is supported by a cysteine mutant that locks the protein in one of the two conformations. NMR spectra of this mutant showed the predicted 2-fold reduction of peaks in the 15N HSQC spectrum and the complete removal of cross peaks in exchange spectra. It is possible that interconversion of these two conformations may be triggered by external signals in a manner similar to that proposed recently for the microtubule binding domain of dynein and the HAMP domain. As a result, the leucine zipper of Nek2 kinase is the first example where the frameshift of coiled-coil heptad repeats has been directly observed experimentally. [ABSTRACT FROM AUTHOR]

Abstract: Previous studies of methods for stimulating the individual muscles composing the quadriceps femoris have not considered the structural features of a subject''s knee joint. In this study, we compared the ratios of the individual muscles composing the quadriceps between subjects with different knee alignments using magnetic resonance (MR) imaging. A total of 18 healthy males were examined: 6 normal knees (age, 23.0±0.6yr; femorotibial angle (FTA), 176.8±0.4°), 6 genu varum (age, 21.8±2.9 yr; FTA, 181.7±2.6°) and 6 genu valgum (age, 21.0±1.6yr; FTA, 172.3±1.5°). The cross-sectional areas (CSAs) of quadriceps muscles were obtained by MR imaging of the entire left thigh. The CSAs of the vastus lateralis (VL), rectus femoris (RF), vastus medialis (VM) and vastus intermedius (VI) muscles were obtained by MR imaging of the entire left thigh in a supine position. The VM/VL ratio was also obtained by dividing the CSA of the VM by that of the VL and compared among the three groups of subjects with different knee alignments. The genu varum group showed a significantly higher %CSA of VM in the CSA of the quadriceps (VM/Quad) (49.0±2.6%) than values for the other two groups. The genu valgum group showed significantly higher values of RF/Quad (15.2±2.1%) and VL/Quad (40.6±4.0%) than the other groups. The VM/VL ratio was significantly higher in the genu varum than in values for the other two groups. This difference in CSA, in respect to knee alignment, may be considered when devising muscle training programs. [Copyright &y& Elsevier]

Nek2 is a cell cycle-regulated serine/threonine protein kinase that is up-regulated in human cancers. Functionally, it is implicated in control of centrosome separation and bipolar spindle formation in mitotic cells and chromatin condensation in meiotic cells. Two major splice variants have been described in vertebrates, Nek2A and Nek2B, that differ in their non-catalytic C termini. Recently, a third splice variant, Nek2C, was identified that lacks an eight-amino acid internal sequence within the C-terminal domain of Nek2A. This excision occurs at the same position as the Nek2A/Nek2B splice point. As predicted from their high degree of similarity, we show here that Nek2C shares many properties with Nek2A including kinase activity, dimerization, protein phosphatase 1 interaction, mitotic degradation, microtubule binding, and centrosome localization. Unexpectedly, though, the non-centrosomal pool of protein exhibits a marked difference in distribution for the three splice variants. Nek2C is mainly nuclear, Nek2B is mainly cytoplasmic, and Nek2A is evenly distributed within nuclei and cytoplasm. Mutagenesis experiments revealed a functional bipartite nuclear localization sequence (NLS) that spans the splice site leading to Nek2C having a strong NLS, Nek2A having a weak NLS, and Nek2B having no NLS. Finally, we identified a 28-kDa protein in nuclear extracts as a potential novel substrate of Nek2. Thus, alternative splicing provides an unusual mechanism for modulating Nek2 localization, enabling it to have both nuclear and cytoplasmic functions. [ABSTRACT FROM AUTHOR]

The dimeric Ser/Thr kinase Nek2 regulates centrosome cohesion and separation through phosphorylation of structural components of the centrosome, and aberrant regulation of Nek2 activity can lead to aneuploid defects characteristic of cancer cells. Mutational analysis of autophosphorylation sites within the kinase domain identified by mass spectrometry shows a complex pattern of positive and negative regulatory effects on kinase activity that are correlated with effects on centrosomal splitting efficiency in vivo. The 2.2-Å resolution x-ray structure of the Nek2 kinase domain in complex with a pyrrole-indolinone inhibitor reveals an inhibitory helical motif within the activation loop. This helix presents a steric barrier to formation of the active enzyme and generates a surface that may be exploitable in the design of specific inhibitors that selectively target the inactive state. Comparison of this "auto-inhibitory" conformation with similar arrangements in cyclin-dependent kinase 2 and epidermal growth factor receptor kinase suggests a role for dimerization-dependent allosteric regulation that combines with autophosphorylation and protein phosphatase 1c phosphatase activity to generate the precise spatial and temporal control required for Nek2 function in centrosomal maturation. [ABSTRACT FROM AUTHOR]

Mutations in the TRIM8 gene have been described in patients with severe developmental delay, intellectual disability and epilepsy. Only six patients have been described to date. All the previous mutations were truncating variants clustered in the C-terminus of the protein. A previous patient with TRIM8 -related epileptic encephalopathy was reported to have nephrotic syndrome. Here we describe the clinical, radiological and histological features of an 8-year-old male patient with a TRIM8 mutation who, in contrast to previous patients, had only mild intellectual disability and well-controlled epilepsy. The patient was found to have proteinuria at 2 years of age. Renal biopsy findings were suggestive of focal segmental glomerulosclerosis. His kidney function declined and peritoneal dialysis was started at 5 years of age. He underwent renal transplant at 7 years of age. Trio-based whole genome sequencing identified a novel de novo heterozygous frameshift mutation in TRIM8 (NM_030912.2) c.1198_1220del, p.(Tyr400ArgfsTer2). This patient is further evidence that TRIM8 mutations cause a syndrome with both neurological and renal features. Our findings suggest the spectrum of TRIM8 -related disease may be wider than previously thought with the possibility of milder neurodevelopmental problems and/or a more severe, progressive renal phenotype. We highlight the need for proteinuria screening in patients with TRIM8 mutations. [ABSTRACT FROM AUTHOR]