Jupiter's X-Ray and UV Dark Polar Region.

We present 14 simultaneous Chandra X-ray Observatory (CXO)-Hubble Space Telescope (HST) observations of Jupiter's Northern X-ray and ultraviolet (UV) aurorae from 2016 to 2019. Despite the variety of dynamic UV and X-ray auroral structures, one region is conspicuous by its persistent absence of emission: the dark polar region (DPR). Previous HST observations have shown that very little UV emission is produced by the DPR. We find that the DPR also produces very few X-ray photons. For all 14 observations, the low level of X-ray emission from the DPR is consistent (within 2-standard deviations) with scattered solar emission and/or photons spread by Chandra's Point Spread Function from known X-ray-bright regions. We therefore conclude that for these 14 observations the DPR produced no statistically significant detectable X-ray signature.

Comparison of sporadic and familial behavioral variant frontotemporal dementia (FTD) in a North American cohort.

INTRODUCTION: Behavioral variant frontotemporal dementia (bvFTD) may present sporadically or due to an autosomal dominant mutation. Characterization of both forms will improve understanding of the generalizability of assessments and treatments. METHODS: A total of 135 sporadic (s-bvFTD; mean age 63.3 years; 34% female) and 99 familial (f-bvFTD; mean age 59.9; 48% female) bvFTD participants were identified. f-bvFTD cases included 43 with known or presumed chromosome 9 open reading frame 72 (C9orf72) gene expansions, 28 with known or presumed microtubule-associated protein tau (MAPT) mutations, 14 with known progranulin (GRN) mutations, and 14 with a strong family history of FTD but no identified mutation. RESULTS: Participants with f-bvFTD were younger and had earlier age at onset. s-bvFTD had higher total Neuropsychiatric Inventory Questionnaire (NPI-Q) scores due to more frequent endorsement of depression and irritability. DISCUSSION: f-bvFTD and s-bvFTD cases are clinically similar, suggesting the generalizability of novel biomarkers, therapies, and clinical tools developed in either form to the other.

Valley Subband Splitting in Bilayer Graphene Quantum Point Contacts.

We report a study of one-dimensional subband splitting in a bilayer graphene quantum point contact in which quantized conductance in steps of 4e^{2}/h is clearly defined down to the lowest subband. While our source-drain bias spectroscopy measurements reveal an unconventional confinement, we observe a full lifting of the valley degeneracy at high magnetic fields perpendicular to the bilayer graphene plane for the first two lowest subbands where confinement and Coulomb interactions are the strongest and a peculiar merging or mixing of K and K^{'} valleys from two nonadjacent subbands with indices (N,N+2), which are well described by our semiphenomenological model.

The effect of obesity on adverse outcomes and metabolism in pediatric burn patients.

HYPOTHESIS: Obesity influences metabolism and increases the incidence of clinical complications and worsens outcomes in pediatric burn patients. DESIGN: Retrospective, single-center study. SUBJECTS: In all, 592 severely burned pediatric patients who had burns covering more than 30% of the total body surface area and who were treated between 2001 and 2008 were enrolled in this study. Patients were divided into ≥85th percentile (n=277) and normal (n=315) weight groups based on body mass index (BMI) percentiles. RESULTS: Patients stratified below (normal) and ≥85th percentile had similar age, gender distribution and total burn size. No significant differences were detected in the incidence of sepsis (11% for obese vs 10% for normal), the incidence of multiple organ failure (MOF) (21% for obese and 16% for normal) or mortality (11% for obese vs 8% for normal). Compared with the normal group, the ≥85th percentile group had low levels of constitutive proteins (α2macroglobulin and Apolipoprotein A1) (P<0.05 for both) as well as high levels of triglycerides and the acute-phase protein, C-reactive protein (P<0.05 for both) up to 60 days after injury. Patients ≥85th percentile showed a significant higher loss of bone mineral density and lipolysis compared with normal individuals. Stepwise logistic regression analysis revealed that BMI had a positive predictive value towards the maximum DENVER2 score, an index of organ failure (P<0.001). CONCLUSIONS: BMI≥85th percentile altered the post-burn acute phase and catabolic response but did not increase the incidence of sepsis, MOF or mortality in pediatric burn patients. Our results suggest that impaired metabolism and an altered inflammatory response already exists in patients starting at the 85th percentile BMI.

Comparing Jupiter's Equatorial X-Ray Emissions With Solar X-Ray Flux Over 19 Years of the Chandra Mission.

We present a statistical study of Jupiter's disk X-ray emissions using 19 years of Chandra X-Ray Observatory (CXO) observations. Previous work has suggested that these emissions are consistent with solar X-rays elastically scattered from Jupiter's upper atmosphere. We showcase a new pulse invariant (PI) filtering method that minimizes instrumental effects which may produce unphysical trends in photon counts across the nearly two-decade span of the observations. We compare the CXO results with solar X-ray flux data from the Geostationary Operational Environmental Satellites X-ray Sensor for the wavelength band 1-8 Å (long channel), to quantify the correlation between solar activity and Jovian disk counts. We find a statistically significant Pearson's Correlation Coefficient of 0.9, which confirms that emitted Jovian disk X-rays are predominantly governed by solar activity. We also utilize the high spatial resolution of the High Resolution Camera Instrument on-board the CXO to map the disk photons to their positions on Jupiter's surface. Voronoi tessellation diagrams were constructed with the Juno Reference Model through Perijove 9 internal field model overlaid to identify any spatial preference of equatorial photons. After accounting for area and scattering across the curved surface of the planet, we find a preference of Jovian disk emission at 2-3.5 Gauss surface magnetic field strength. This suggests that a portion of the disk X-rays may be linked to processes other than solar scattering: the spatial preference associated with magnetic field strength may imply increased precipitation from the radiation belts, as previously postulated.

The base of the proteasome regulatory particle exhibits chaperone-like activity.

Protein substrates of the proteasome must apparently be unfolded and translocated through a narrow channel to gain access to the proteolytic active sites of the enzyme. Protein folding in vivo is mediated by molecular chaperones. Here, to test for chaperone activity of the proteasome, we assay the reactivation of denatured citrate synthase. Both human and yeast proteasomes stimulate the recovery of the native structure of citrate synthase. We map this chaperone-like activity to the base of the regulatory particle of the proteasome, that is, to the ATPase-containing assembly located at the substrate-entry ports of the channel. Denatured but not native citrate synthase is bound by the base complex. Ubiquitination of citrate synthase is not required for its binding or refolding by the base complex of the proteasome. These data suggest a model in which ubiquitin-protein conjugates are initially tethered to the proteasome by specific recognition of their ubiquitin chains; this step is followed by a nonspecific interaction between the base and the target protein, which promotes substrate unfolding and translocation.

The signal sequence receptor has a second subunit and is part of a translocation complex in the endoplasmic reticulum as probed by bifunctional reagents.

Bifunctional cross-linking reagents were used to probe the protein environment in the ER membrane of the signal sequence receptor (SSR), a 24-kD integral membrane glycoprotein (Wiedmann, M., T. V. Kurzchalia, E. Hartmann, and T. A. Rapoport. 1987. Nature [Lond.]. 328:830-833). The proximity of several polypeptides was demonstrated. A 22-kD glycoprotein was identified tightly bound to the 34-kD SSR even after membrane solubilization. The 34-kD polypeptide, now termed alpha SSR, and the 22-kD polypeptide, the beta SSR, represent a heterodimer. We report on the sequence of the beta SSR, its membrane topology, and on the mechanism of its integration into the membrane. Cross-linking also produced dimers of the alpha-subunit of the SSR indicating that oligomers of the SSR exist in the ER membrane. Various bifunctional cross-linking reagents were used to study the relation to ER membrane proteins of nascent chains of preprolactin and beta-lactamase at different stages of their translocation through the membrane. The predominant cross-linked products obtained in high yields contained the alpha SSR, indicating in conjunction with previous results that it is a major membrane protein in the neighborhood of translocating nascent chains of secretory proteins. The results support the existence of a translocon, a translocation complex involving the SSR, which constitutes the specific site of protein translocation across the ER membrane.

Distinct patterns of brain activity evoked by histamine-induced itch reveal an association with itch intensity and disease severity in atopic dermatitis.

BACKGROUND: Little is known about brain mechanisms supporting the experience of chronic puritus in disease states. OBJECTIVES: To examine the difference in brain processing of histamine-induced itch in patients with active atopic dermatitis (AD) vs. healthy controls with the emerging technique of functional magnetic resonance imaging (fMRI) using arterial spin labelling (ASL). METHODS: Itch was induced with histamine iontophoresis in eight patients with AD and seven healthy subjects. RESULTS: We found significant differences in brain processing of histamine-induced itch between patients with AD and healthy subjects. Patients with AD exhibited bilateral activation of the anterior cingulate cortex (ACC), posterior cingulate cortex (PCC), retrosplenial cingulate cortex and dorsolateral prefrontal cortex (DLPFC) as well as contralateral activation of the caudate nucleus and putamen. In contrast, healthy subjects activated the primary motor cortex, primary somatosensory cortex and superior parietal lobe. The PCC and precuneus exhibited significantly greater activity in patients vs. healthy subjects. A significant correlation between percentage changes of brain activation was noted in the activation of the ACC and contralateral insula and histamine-induced itch intensity as well as disease severity in patients with AD. In addition, an association was noted between DLPFC activity and disease severity. CONCLUSIONS: Our results demonstrate that ASL fMRI is a promising technique to assess brain activity in chronic itch. Brain activity of acute itch in AD seems to differ from that in healthy subjects. Moreover, the activity in cortical areas involved in affect and emotion correlated to measures of disease severity.

Two different subunits of importin cooperate to recognize nuclear localization signals and bind them to the nuclear envelope.

BACKGROUND: Selective protein import into the cell nucleus occurs in two steps: binding to the nuclear envelope, followed by energy-dependent transit through the nuclear pore complex. A 60 kD protein, importin, is essential for the first nuclear import step, and the small G protein Ran/TC4 is essential for the second. We have previously purified the 60kD importin protein (importin 60) as a single polypeptide. RESULTS: We have identified importin 90, a 90 kD second subunit that dissociates from importin 60 during affinity chromatography on nickel (II)-nitrolotriacetic acid-Sepharose, a technique that was originally used to purify importin 60. Partial amino-acid sequencing of Xenopus importin 90 allowed us to clone and sequence its human homologue; the amino-acid sequence of importin 90 is strikingly conserved between the two species. We have also identified a homologous budding yeast sequence from a database entry. Importin 90 potentiates the effects of importin 60 on nuclear protein import, indicating that the importin complex is the physiological unit responsible for import. To assess whether nuclear localization sequences are recognized by cytosolic receptor proteins, a biotin-tagged conjugate of nuclear localization signals linked to bovine serum albumin was allowed to form complexes with cytosolic proteins in Xenopus egg extracts; the complexes were then retrieved with streptavidin-agarose. The pattern of bound proteins was surprisingly simple and showed only two predominant bands: those of the importin complex. We also expressed the human homologue of importin 60, Rch1p, and found that it was able to replace its Xenopus counterpart in a functional assay. We discuss the relationship of importin 60 and importin 90 to other nuclear import factors. CONCLUSIONS: Importin consists of a 60 and a 90 kD subunit. Together, they constitute a cytosolic receptor for nuclear localization signals that enables import substrates to bind to the nuclear envelope.

Amino acid sequence analysis of the beta- and gamma-subunits of eukaryotic initiation factor eIF-2. Identification of regions interacting with GTP.

By affinity labelling using two different GTP photoaffinity analogues we previously demonstrated that both the beta- and gamma-subunits of eukaryotic initiation factor eIF-2 are involved in GTP binding (Bommer, U.-A. and Kurzchalia, T.V. (1989) FEBS Lett. 244, 323-327). We have now applied the same method in combination with CNBr cleavage and microsequence analysis in order investigate which part of the polypeptide chain of eIF-2 beta is in close contact to the bound GTP. From the three main CNBr fragments of eIF-2 beta, the C-terminal one was found to be labelled by the applied GTP photoaffinity analogue, Guo(2',3'-TDBH)ppp. Because the cDNA sequence of the gamma-subunit of eIF-2 has not yet been published and because cDNA sequence analysis of eIF-2 beta revealed only two out of three consensus sequence elements of a GTP-binding domain, we also sequenced the CNBr fragments of eIF-2 gamma. In this way, sequences containing about 50 amino acid residues were obtained. Taken together with the recently published N-terminal sequences of tryptic peptides of eIF-2 gamma from pig liver (Suzuki et al. 1990, J. Biochem. 108, 635-641), about 30% of the total sequence is now known. One of the CNBr fragments from rabbit eIF-2 gamma contains a sequence (AXXAXXGK) which in several respects resembles that of the consensus sequence element absent from the beta-subunit.

Chemical modification of cytochrome P-450 LM4. Identification of functionally linked tyrosine residues.

Cytochrome P-450 LM4 (RH, reduced flavoprotein:oxygen oxidoreductase (RH-hydroxylating), EC 1.14.14.1) from rabbit liver microsomes was chemically modified with tetranitromethane. Nitration of two tyrosine residues inhibits the p-nitrophenetole O-deethylase activity of the enzyme by about 80%. Sequencing the 3-nitrotyrosine-containing peptides after HPLC tryptic peptide mapping reveals that mainly Tyr-243 and Tyr-271 are nitrated, whereas Tyr-71, Tyr-188 and Tyr-365 are modified to a lower extent. Nitration of tyrosine residues affects the complex formation with p-nitrophenetole, alpha-naphthoflavone and metyrapone as indicated by an increased affinity towards p-nitrophenetole and by a decreased affinity for the latter compounds. Furthermore, nitration interferes with the electron transfer from NADPH-cytochrome P-450-reductase to cytochrome P-450 LM4 resulting in a slowed down reduction reaction. The results suggest that Tyr-243 and Tyr-271 of cytochrome P-450 LM4 are functionally involved in the interaction with NADPH-cytochrome P-450 reductase.

The Rossmann fold of glyceraldehyde-3-phosphate dehydrogenase (GAPDH) is a nuclear docking site for antisense oligonucleotides containing a TAAAT motif.

The subcellular localisation of oligodeoxynucleotides (ODN) is a major limitation for their use against nuclear targets. In this study we demonstrate that an antisense ODN directed against cytosolic phospholipase A(2) (cPLA2) mRNA is efficiently taken up and accumulates in the nuclei of endothelial cells (HUVEC), human monocytes and HeLa cells. Gel shift experiments and incubation of cells with oligonucleotide derivatives show that the anti-cPLA2 oligo binds a 37 kDa protein in nuclear extracts. The TAAAT sequence was identified as the major binding motif for the nuclear protein in competition experiments with mutated ODNs. Modification of the AAA triplet resulted in an ODN which failed to localise in the nucleus. Moreover, inserting a TAAAT motif into an ODN localising in the cytosol did not modify its localisation. The 37 kDa protein was purified and identified after peptide sequencing as glyceraldehyde-3-phosphate dehydrogenase (GAPDH). It was shown by confocal microscopy that GAPDH co-localises with anti-cPLA2 ODN in the nucleus and commercial GAPDH effectively binds the oligo. Competition experiments with increasing concentration of NAD(+) co-factor indicate that the GAPDH Rossmann fold is a docking site for antisense oligonucleotides containing a TAAAT motif.

Characterisation of the newly identified human Ump1 homologue POMP and analysis of LMP7(beta 5i) incorporation into 20 S proteasomes.

Biogenesis of mammalian 20 S proteasomes occurs via precursor complexes containing alpha and unprocessed beta subunits. A human homologue of the yeast proteasome maturation factor Ump1 was identified in 2D gels of 16 S precursor preparations and designated as POMP (proteasome maturation protein). We show that POMP is detected only in precursor fractions and not in fractions containing mature 20 S proteasome. Northern blot experiments revealed that expression of POMP is induced after treatment with interferon gamma. To analyse the role of the beta 5 propeptide for proper maturation and incorporation of the beta 5 subunit into the complex, human T2 cells, which highly express derivatives of the beta 5i subunit (LMP7), were studied. In contrast to yeast, the presence of the beta 5 propeptide is not essential for incorporation of LMP7 into the proteasome complex. Mutated LMP7 subunits either carrying the prosequence of beta 2i (LMP2) or containing a mutation in the active threonine site are incorporated like wild-type LMP7, while a LMP7 derivative lacking the prosequence completely is incorporated to a lesser extent. Although the absence of the prosequence does not affect incorporation of LMP7, its deletion leads to delayed proteasome maturation and thereby to an accumulation of precursor complexes. As a result of the precursor accumulation, an increased amount of the POMP protein can be detected in these cells.

Full-length rat alpha and beta cardiac myosin heavy chain sequences. Comparisons suggest a molecular basis for functional differences.

The two cardiac myosin heavy chain isoforms, alpha and beta, differ functionally, alpha Myosin exhibits higher actin-activated ATPase than does beta myosin, and hearts expressing alpha myosin exhibit increased contractility relative to hearts expressing beta myosin. To understand the molecular basis for this functional difference, we determined the complete nucleotide sequence of full-length rat alpha and beta myosin heavy chain cDNAs. This study represents the first opportunity to compare full-length fast ATPase and slow ATPase muscle myosin sequences. The alpha and beta myosin heavy chain amino acid sequences are more related to each other than to other sarcomeric myosin heavy chain sequences. Of the 1938 amino acid residues in alpha and beta myosin heavy chain, 131 are non-identical with 37 non-conservative changes. Two-thirds of these non-identical residues are clustered, and several of these clusters map to regions that have been implicated as functionally important. Some of the regions identified by the clusters of non-identical amino acid residues may affect actin binding, ATP hydrolysis and force production.

Sequence information within proteasomal prosequences mediates efficient integration of beta-subunits into the 20 S proteasome complex.

The maturation of proteases is governed by prosequences. During the biogenesis of the highly oligomeric eukaryotic 20 S proteasome five different prosequence-containing subunits have to be integrated and processed either by autocatalysis or by neighbouring subunits. To analyse the functional impact of proteasomal prosequences during complex formation, the propeptide of the facultative subunit beta1i/LMP2 was truncated to nine amino acid residues or completely deleted. Additionally, the charged residues within the truncated beta1i/LMP2 version were replaced by neutral residues. While deletion did not affect subunit incorporation, the presence of charged residues within the truncated version of the LMP2 propeptide diminished incorporation efficiency, an effect that was restored upon replacement of the charged amino acids against neutral components. During immunoproteasome formation, incorporation and processing of inducible proteasome beta-subunits are cooperative processes. We demonstrate a linear correlation of the levels of beta2i/MECL1 and beta1i/LMP2 within 20 S proteasomes, suggesting a physical interaction to be the molecular basis for the biased incorporation of both subunits. In the absence of beta5i/LMP7, precursor complexes containing unprocessed beta1i/LMP2 accumulated. The contribution of beta5i/LMP7 on the cooperative formation of a homogeneous population of immunoproteasome is therefore most likely based on an acceleration of the beta1i/LMP2 and potentially of beta2i/MECL1 processing kinetics.

Repetitive nucleotide sequence insertions into a novel calmodulin-related gene and its processed pseudogene.

A gene containing a transposon-like human repeat element, called THE 1, has been isolated and characterized. The gene, termed T+, encodes a polypeptide resembling known calcium-binding proteins. The THE 1 element is present in the 3'-untranslated region of its message. The cDNA clone corresponding to the gene's mRNA product led to the identification of this gene. A processed RNA pseudogene related to the authentic gene has also been isolated. In addition to intron processing, this pseudogene differs from the gene in that it contains an interspersed Alu repeat instead of a THE 1 element in the 3'-untranslated region. Thus, we compare a site containing a THE 1 element to an ancestrally related transposon-less target site. The comparison suggests a retroviral-related mechanism of THE 1 insertion. This system is unusual in that the parent gene is associated with three distinct retrotransposition events: the parent gene was converted to a processed RNA pseudogene, an Alu repeat inserted into the pseudogene, and a THE 1 element inserted into the parent gene.

Selective chemical modification of Cys264 with diiodofluorescein iodacetamide as a tool to study the membrane topology of cytochrome P450scc (CYP11A1).

Cys264 of cytochrome P450scc (CYP11A1) was selectively labelled with diiodofluorescein iodacetamide in solution and in proteoliposomes. The labelling affected the interaction of P450scc with adrenodoxin and significantly inhibited the side-chain cleavage activity of the soluble and membrane-bound hemeprotein in the reconstituted system. In proteoliposomes both the labelled and unlabelled hemeproteins were susceptible to trypsin and split into F1 and F2, two fragments corresponding to the two main domains of P450scc. These results suggest that the hinge connecting the two domains in the region Arg250-Asn257 is exposed to the surface of the membrane and involved in the interaction of P450scc with adrenodoxin.

20S proteasome from LMP7 knock out mice reveals altered proteolytic activities and cleavage site preferences.

20S proteasomes of tissues from LMP7 knock out mice which show reduced MHC class I restricted antigen presentation were analyzed with regard to their subunit composition, peptide hydrolyzing activity and their ability to cleave a synthetic 25-mer polypeptide. LMP7 deficiency results in an enhanced incorporation of subunit MB1 and in a 2-3.8-fold increase in Vmax for the Suc-LLVY-MCA hydrolyzing activity. Since LMP7 deficiency also affects the cleavage site preference of 20S proteasomes the reduced MHC class I antigen presentation of LMP7 knock out mice is most likely due to an impairment in peptide generation.

The effect of sex, laterality and familial handedness on intellectual abilities.

This study assessed the relationship of sex, familial handedness and laterality to the intellectual abilities of 116 right-handed 12-14-yr-old subjects. Verbal scores were predicted by an interaction between familial handedness and the subject's own laterality. A strong right ear advantage for verbal stimuli and a large lateral difference between the ear advantage for verbal and nonverbal stimuli predicted high Verbal Intelligence scores for the strong right hand-eye preference subjects with family histories of dextrality. Conversely, attenuated ear advantage scores for verbal stimuli predicted high Verbal Intelligence scores for the strong right hand-eye familial sinistral subjects. Although the results were less consistent for Performance Intelligence scores, they were significantly and positively related to assessed hand-eye preference, and a significant interaction between familial handedness and the subject's own laterality was observed for the Object Assembly subtest. A strong left ear advantage for nonverbal stimuli predicted high scores for the strong right-preference familial dextral subjects and attenuated ear advantage for nonverbal stimuli predicted high scores for the strong right-preference familial sinistral subjects.

Lateral specialization and verbal/spatial ability in preschool children: age, sex and familial handedness differences.

One hundred and fifty-five preschool children between 2 1/2 and 5 1/2 yr of age were administered two dichotic tests (digit and nonverbal sound) and three Wechsler Intelligence subtests (vocabulary, geometric design and block design). The familial dextral (FD) children around 4 yr and older demonstrated a greater degree of absolute ear laterality than the FD children under 4 yr of age. There were also age-related changes in the relationship between children's ability scores and their ear laterality scores. For older FD children a greater right-ear advantage for verbal stimuli and a left-ear advantage for nonverbal stimuli was associated with higher vocabulary scores. Under 4 yr of age, however, a strong right-ear advantage for verbal stimuli was associated with relatively higher spatial than vocabulary ability. For these younger FD children, less marked laterality predicted higher vocabulary scores. It is hypothesized that a cortical organizational transition is occurring around 4 yr of age and that this transition involves a shift from reliance on subcortical to cortical mediation, accompanied by increasing callosally mediated inhibition and integration of hemispheric function. Furthermore, there were sex differences observed in the relationship between lateral specialization and spatial ability. As young as 2 1/2 yr of age, the FD boys' spatial ability scores were positively associated with having a left-ear advantage for nonverbal sound stimuli. The FD girls' spatial ability scores were not significantly related to their ear advantage scores for nonverbal sounds but were associated with their ear advantage scores for verbal stimuli. In addition, around 4 yr of age a shift was observed in the relationship between the boys' absolute laterality scores and the difference between their spatial and vocabulary ability scores which was not found for the girls' scores. It it suggested that the maturation of right hemispheric spatial mediation may be delayed or inhibited in girls.