Region Of Segment Research Articles

Phosphorylation of GPCR Kinase 2 in Intact Cells: A Proteomic Approach

G protein‐coupled receptor (GPCR) kinases (GRKs) were first discovered by their ability to phosphorylate GPCRs in an agonist‐dependent manner. GRKs belong to the AGC kinase family of kinases. Activation of AGC kinases is often accompanied by phosphorylation of activation loop residues as well as other conformational changes in catalytically important residues. Crystal structures of GRK2 suggest that the activation segment region is in a relatively “active” conformation in the absence of phosphorylation. Nonetheless, a phosphoproteomic study (Oppermann et al., 2009) indicated that GRK2 Ser350 and Thr353 can be phosphorylated in intact cancer cells. Ser350 and Thr353 reside in the activation loop and P+1 site of the peptide‐binding site, respectively. To test the role of Ser350 and Thr353 phosphorylation in GRK2 function, we substituted alanine and aspartate at these two positions and tested the ability to phosphorylate the beta‐adrenergic receptor. We found that Thr353 is particularly important for phosphorylation of beta‐adrenergic receptor by GRK2 in COS‐7 cells, since conversion to Ala or Asp prevented substrate phosphorylation. In cells transfected with both beta‐adrenergic receptor and GRK2, multiple forms of GRK2 were detected in cells treated with agonist. The multiple forms are consistent with various phosphorylation states. Our goal is to assess Ser350/Thr353 phosphorylation in intact cells using phosphoproteomic approaches. To this end, we engineered a hexahistidine tag on GRK2 expressed from a mammalian cell vector to facilitate its purification and have demonstrated that the tagged kinase is fully functional in agonist‐dependent receptor phosphorylation. We are further developing methods to assess GRK2 phosphorylation by isoelectric focusing and mass spectrometry.Support or Funding InformationThis work was funded by the National Science Foundation MCB0744739 and Siena College Center for Undergraduate Research and Creative Activity (CURCA).This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Eater and draper are involved in the periostial haemocyte immune response in the mosquito Anopheles gambiae.

Haemocytes respond to infection by phagocytosing pathogens, producing the enzymes that drive the phenoloxidase-based melanization cascade, secreting lytic factors, and producing other humoral proteins. A subset of haemocytes, called periostial haemocytes, aggregate on the surface of the heart of mosquitoes and kill pathogens in areas of high haemolymph flow. Periostial haemocytes are always present, but an infection induces the recruitment of additional haemocytes to these regions. Here, we tested whether members of the Nimrod gene family are involved in the periostial immune response of the African malaria mosquito, Anopheles gambiae. Using organismal manipulations, RNA interference (RNAi) and microscopy, we show that, following an infection with Escherichia coli, nimrod - the orthologue of Drosophila NimB2 - is not involved in periostial responses. At 4 h postinfection, however, RNAi-based knockdown of draper results in a marginal increase in the number of periostial haemocytes and a doubling of E.coli accumulation at the periostial regions. Finally, at 24 h postinfection, knockdown of eater decreases the number of periostial haemocytes and decreases the phagocytosis of E.coli on the surface of the heart. Phagocytosis of bacteria is more prevalent in the periostial regions of the mid abdominal segments, and knockdown of draper, nimrod or eater does not alter this distribution. Finally, knockdown of Nimrod family genes did not have a meaningful effect on the accumulation of melanin at the periostial regions. This study identifies roles for eater and draper in the functional integration of the mosquito immune and circulatory systems.

Marmota himalayana in the Qinghai–Tibetan plateau as a special host for bi-segmented and unsegmented picobirnaviruses

Wildlife has been considered the main source of novel viruses causing emerging infectious diseases. Marmota himalayana is endemic to the Qinghai–Tibetan Plateau, China. Here, based on a high-throughput method using Illumina RNA sequencing, we studied the RNA virome of M. himalayana and discovered multiple novel viruses, especially picobirnaviruses (PBVs), which have a bi-segmented genome and belong to the family Picobirnaviridae. A total of 63% of the viral contigs corresponded to PBVs, comprising 274 segment 1 and 56 segment 2 sequences. Unexpectedly, four unsegmented PBV genomes were also detected and confirmed by PCR and resequencing. According to the phylogenetic analysis, the following nine PBV assortment types are proposed: C1:GI, C2:GIV, C4:GI, C4:GV, C5:GI, C7:GI, C8:GIV, C8:GV and C8:GII. We hypothesize a model of segmentation for the PBV genome, mediated by a 6-bp direct repeat sequence, GAAAGG. The model is supported by detection of the segmentation-associated sequence GAAAGG not only in the 5′ untranslated regions of segment 1 (221 in 289) and segment 2 (57 in 80) of bi-segmented PBVs but also in the 5′ untranslated regions and junction sequences between the capsid and RdRp genes of unsegmented PBVs. Therefore, with RNA sequencing, we found an unexpected biodiversity of PBVs in M. himalayana, indicating that M. himalayana is a special host for PBVs. We also proposed a putative model of how bi-segmented PBVs could be converted into unsegmented PBVs, which sheds new light on the processes of RNA virus genome evolution.

HYDRONEPHROSIS IN CHILDREN (LOOK THROUGH THE PRISM OF TIME)

Introduction. The introduction of ultrasonic research into everyday perinatal practice in 1980s, the use of radioisotope and radiotherapeutic techniques, as well as minimally invasive methods of surgical correction of hydronephrosis, significantly changed our view of this malformation in a number of ways. The causes of dilatation of the collection system in the fetus and newborn can be both obstructive and non-obstructive in character. Material and methods. A work analyzes modern methods of diagnosis and treatment of hydronephrosis in children. The attitude to radiopaque methods of research (excretory urography, cystography, CT) in newborns and infants is emphasized to have changed also. In this regard, the emphasis was shifted to ultrasound, radioisotope methods of diagnosis and MRI. The antenatal detection of hydronephrosis transformation was noted to contribute also to the early implementation of the surgical correction of the defect. At the same time, there is considered the need for a well-structured approach to the surgical treatment, taking into account a number of factors in children with pyelectasis, visualized in a screening ultrasound examination in pre- and postnatal periods. The modern algorithm of diagnostics and tactics of the management of patients is considered. There is discussed a number of such issues relevant to the children’s urologist as: how probable is spontaneous resolution of obstruction of the ureteropelvic segment? What criteria indicate to the non-obstructive nature of the expansion of the collection system? The prospects of using technique of robotic pyeloplasty in children are analyzed. Is surgery necessary and at what age? What kind of the access and method of prompt correction should be preferred? Will the kidney function be restored after the operation? There are considered questions of laparoscopic and retroperitoneoscopic way of the elimination of hydronephrosis, indications and contraindications to the performance of each type of access. Based on the own experience the necessity and methods of drainage of the collection system of the kidney after the operation are discussed. The prospects of using robotics pyeloplasty in children are analyzed. Conclusion. Obstruction in the region of the ureteropelvic segment will continue to cause discussions in terms of the appropriateness of selection patients which can be observed in dynamics until the main process will be resolved naturally. Laparoscopic pyeloplasty in hydronephrosis is the “gold standard” in the world and its successful implementation in children with the use of endovideosurgical technologies largely depends on the manual skills of the operator, the experience of performing similar operations, teamwork in the person of an assistant, anesthesiologist and operating nurse.

Magnetohydrodynamic flows in a dis-aligned duct system under a uniform magnetic field

In the present study, three-dimensional Magnetohydrodynamic (MHD) Liquid-metal (LM) flows in a dis-aligned duct system under a uniform magnetic field are investigated by numerical method. Computational fluid dynamics (CFD) simulations are carried out to analyzed the characteristics of the MHD flows and to examine the inter-relationship of the LM velocity, current density, electric potential and pressure, using CFX. The duct system consists of two dis-aligned parallel channels (One inflow channel and one outflow channel) and one channel connecting the above channels. In the present study, cases with different lengths of the connecting channel are considered. Because of the inertial force therein, a velocity recirculation is found in the region just after the first turning, resulting in a region of peak value in electric potential together with complex distribution of the current. Also, another velocity recirculation is seen in the region just after the second turning, creating another region of peak value in electric potential. In a situation where the magnetic field is applied in a direction perpendicular to the plane of the main flow in a dis-aligned duct system, until the fluid reaches an edge, the velocity component parallel to the magnetic field converges, with an increasing in the peak value of the side layer velocity, and then, after the fluid passes the edge, the velocity component parallel to the magnetic field diverges, with a decrease in the peak value of the side layer velocity. Oppositely, until the fluid reaches a corner, the velocity component parallel to the magnetic field diverges, with a decrease in the peak value of the side layer velocity, and then, after the fluid passes the corner, the velocity component parallel to the magnetic field converges, with an increase in the peak value of the side layer velocity. It is found that this type of velocity pattern is closely associated with the current distribution in the region of right-angle segments in the sense that the magnitude of the electromotive component of electric current is proportional to the fluid velocity.

Sequencing of FKS Hot Spot 1 from Saprochaete capitata To Search for a Relationship to Reduced Echinocandin Susceptibility.

Saprochaete capitata, formerly known as Geotrichum capitatum, is an emerging fungal pathogen with low susceptibility to echinocandins. Here, we report the nucleotide sequence of the S. capitata hot spot 1 region of the FKS gene (FKS HS1), which codifies for the catalytic subunit of β-1,3-d-glucan synthase, the target of echinocandins. For that purpose, we first designed degenerated oligonucleotide primers derived from conserved flanking regions of the FKS1 HS1 segment of 12 different fungal species. Interestingly, analysis of the translated FKS HS1 sequences of 12 isolates of S. capitata revealed that all of them exhibited the same F-to-L substitution in a position that is highly related to reduced echinocandin susceptibility.

Biomechanical Rigidity and Quantitative Proteomics Analysis of Segmental Regions of the Trabecular Meshwork at Physiologic and Elevated Pressures.

PurposeThe extracellular matrix (ECM) of the trabecular meshwork (TM) modulates resistance to aqueous humor outflow, thereby regulating IOP. Glaucoma, a leading cause of irreversible blindness worldwide, is associated with changes in the ECM of the TM. The elastic modulus of glaucomatous TM is larger than age-matched normal TM; however, the biomechanical properties of segmental low (LF) and high flow (HF) TM regions and their response to elevated pressure, are unknown.MethodsWe perfused human anterior segments at two pressures using an ex vivo organ culture system. After extraction, we measured the elastic modulus of HF and LF TM regions by atomic force microscopy and quantitated protein differences by proteomics analyses.ResultsThe elastic modulus of LF regions was 2.3-fold larger than HF regions at physiological (1×) pressure, and 7.4-fold or 3.5-fold larger than HF regions at elevated (2×) pressure after 24 or 72 hours, respectively. Using quantitative proteomics, comparisons were made between HF and LF regions at 1× or 2× pressure. Significant ECM protein differences were observed between LF and HF regions perfused at 2×, and between HF regions at 1× compared to 2× pressures. Decorin, TGF-β–induced protein, keratocan, lumican, dermatopontin, and thrombospondin 4 were common differential candidates in both comparisons.ConclusionsThese data show changes in biomechanical properties of segmental regions within the TM in response to elevated pressure, and levels of specific ECM proteins. Further studies are needed to determine whether these ECM proteins are specifically involved in outflow resistance and IOP homeostasis.

Parallel Excitatory and Inhibitory Neural Circuit Pathways Underlie Reward-Based Phasic Neural Responses

Phasic activity of dopaminergic (DA) neurons in the ventral tegmental area or substantia nigra compacta (VTA/SNc) has been suggested to encode reward-prediction error signal for reinforcement learning. Recent studies have shown that the lateral habenula (LHb) neurons exhibit a similar response, but for nonrewarding or punishment signals. Hence, the transient signaling role of LHb neurons is opposite that of DA neurons and also that of several other brain nuclei such as the border region of the globus pallidus internal segment (GPb) and the rostral medial tegmentum (RMTg). Previous theoretical models have investigated the neural circuit mechanism underlying reward-based phasic activity of DA neurons, but the feasibility of a larger neural circuit model to account for the observed reward-based phasic activity in other brain nuclei such as the LHb has yet to be shown. Here, we propose a large-scale neural circuit model and show that parallel excitatory and inhibitory pathways underlie the learned neural responses across multiple brain regions. Specifically, the model can account for the phasic neural activity observed in the GPb, LHb, RMTg, and VTA/SNc. Based on sensitivity analysis, the model is found to be robust against changes in the overall neural connectivity strength. The model also predicts that striosomes play a key role in the phasic activity of VTA/SNc and LHb neurons by encoding previous and expected rewards. Taken together, our model identifies the important role of parallel neural circuit pathways in accounting for phasic activity across multiple brain areas during reward and punishment processing.

REXTAL: Regional Extension of Assemblies Using Linked-Reads.

It is currently impossible to get complete de-novo assembly of segmentally duplicated genome regions using genome-wide short-read datasets. Here, we devise a new computational method called Regional Extension of Assemblies Using Linked-Reads (REXTAL) for improved region-specific assembly of segmental duplication-containing DNA, leveraging genomic short-read datasets generated from large DNA molecules partitioned and barcoded using the "Gel Bead in Emulsion" (GEM) microfluidic method (Zheng et al., 2016). We show that using REXTAL, it is possible to extend assembly of single-copy diploid DNA into adjacent, otherwise inaccessible subtelomere segmental duplication regions and other subtelomeric gap regions. Moreover, REXTAL is computationally more efficient for the directed assembly of such regions from multiple genomes (e.g., for the comparison of structural variation) than genome-wide assembly approaches.

Abstract PR02: Mechanisms of NT5C2 activating mutations driving thiopurine resistance in relapsed lymphoblastic leukemia

Abstract Activating mutations in cytosolic 5'-nucleotidase II (NT5C2) drive resistance to 6-mercaptopurine (6-MP) in relapsed acute lymphoblastic leukemia (ALL). These gain-of function alleles encode proteins with increased nucleotidase activity, yet their specific molecular mechanisms are poorly understood. Allosteric activation of NT5C2 is primarily mediated by a marked conformational change in the helix A region, which reconfigures the catalytic center for substrate access and catalysis. Here we demonstrate that constitutively active NT5C2 mutant proteins (K359Q and L375F) adopt active helix A region structures in the absence of allosteric activator. Moreover, crystallographic, structural modeling, genetic, and functional antibody analyses identify a switch-off mechanism mediated by the dynamic mobilization of Asp407 in the tip region of the arm segment which, guided by positively charged residues located in the surface of a basic inter-monomeric cavity exposed upon allosteric activation, turns off NT5C2 by interacting with and disrupting the helical conformation of helix A. Loss of this regulatory mechanism in NT5C2 mutants involving the tip region of the arm segment and the inter-monomeric cavity drives increased nucleotidase activity and allosteric response. Finally, increased allosteric activation by the Q523X mutation results from loss of the NT5C2 C-terminal acidic tail segment, which promotes a closed inactive state in basal conditions. These results uncover dynamic mechanisms responsible for NT5C2 regulation targeted by chemotherapy resistance-driving NT5C2 mutations, with important implications for the development of NT5C2 inhibitor therapies. This abstract is also being presented as Poster 05. Citation Format: Chelsea L. Dieck, Gannie Tzoneva, Farhad Forouhar, Zachary Carpenter, Marta Sanchez-Martin, Alberto Ambesi-Impiombato, Renate Kirschner-Schwabe, Scott Lew, Jayaraman Seetharaman, Liang Tong, Adolfo Ferrando. Mechanisms of NT5C2 activating mutations driving thiopurine resistance in relapsed lymphoblastic leukemia [abstract]. In: Proceedings of the Second AACR Conference on Hematologic Malignancies: Translating Discoveries to Novel Therapies; May 6-9, 2017; Boston, MA. Philadelphia (PA): AACR; Clin Cancer Res 2017;23(24_Suppl):Abstract nr PR02.

El Escondido, a newly identified silicic Quaternary volcano in the NE region of the northern volcanic segment (Central Cordillera of Colombia)

El Escondido (1650m.a.s.l.) is a silicic Quaternary volcano recently identified on the Central Cordillera of Colombian Andes. It is located about 50km NE from the northern segment of active volcanoes. It has been recognized as a polygenetic pyroclastic-dome ring complex structure, whose eruptive products derived from a crater-like semi-circular depression of ~1.7km in diameter. This crater formed at the contact of the Granitic Florencia Stock (54.9±1.8my) with the Paleozoic metamorphic basement, and at the intersection of the NNESSW trending Palestina fault system with an EW trending fault. The preserved volcano morphology and the volcanic succession associated with it were defined as the El Escondido volcanic center. The eruptive products are alternating silicic (mostly dacitic) pyroclastic density current deposits, pumice fall deposits and ballistic projectiles, which suggest high explosiveness. Two 14C radiogenic dates obtained on carbonized wood fragments of the middle part of the eruptive sequence displayed ages of 36,030±380 BP and 33,550±280 BP suggesting two major eruptive episodes of the volcano about 2500years apart. The latest eruptive activity is inferred to be the emplacement of lava domes to the south of the crater-like structure, which are responsible for the partial destruction of the pyroclastic ring in that sector. The products emitted by El Escondido correspond to medium K andesites to dacites of the calc-alkaline series and petrographically to amphibolic andesites. Towards the western and eastern sector of the volcano, there are chlorinated thermal waters with temperatures up to 45°C. The first monitoring of the volcanic activity, carried out by the Colombian Geological Survey (CGS) through the Volcanological and Seismological Observatory of Manizales (VSOM), has not detected so far unusual volcano-seismic activity. The previously unreported El Escondido volcano represents one of the northernmost occurrence of Quaternary volcanism in the whole Andean cordillera, thus, its study may have wide implications regarding the geodynamics of the region and subduction zone, the correct assessment of geologic hazards and the identification of natural resources, like geothermal reservoirs and mineral deposits of economic interest.

Conserved secondary structures predicted within the 5′ packaging signal region of influenza A virus PB2 segment

Infectious particles of influenza A virus (IAV) typically contain eight unique negative-strand viral RNA (vRNA) segments. It has been suggested that the selective packaging of IAV segments occurs through RNA-RNA interactions between different vRNA segments, and that local secondary structures formed within vRNA segments are involved in such interactions. PB2 segment plays a critical role in the viral packaging process and 80–150 bases at the 5′ end of PB2 vRNA sequence are thought to contain packaging signals. Here we show that the 5′ packaging signal region of PB2 segment forms a stem-loop structure specifically in the negative-strand RNA in >97% of 1703 IAV strains analyzed. This stem-loop structure is located at the nucleotide positions where synonymous mutations and partial deletions have been shown to markedly reduce the packaging efficiency of PB2 segment. These observations suggest that the stem-loop structure predicted in the present study is a component of packaging signal in PB2 segment.

Molecular simulations of fragility of linear and ring polymers

Nowadays, investigation on fragility in glass-forming liquids is a hot topic in the field of condensed matter physics, since the understanding of its microscopic mechanism is useful to uncover the underlying mechanism of the glass transition. In the present paper, we performed dynamic Monte Carlo simulations to explore the correlations between fragility index and conformational changes in linear and ring polymer chains. Compared with ring chains, linear chains exhibit a higher fragility index. In addition, for both ring and linear chains, during approaching the glass transition temperature (Tg), the fraction of segments with trans-conformation increased significantly. To reveal the effect of conformational changes on segmental dynamics during relaxation, a new parameter, the aggregation region of segments with trans-conformation (ARST), is proposed. The maximum ARST has the lowest mobility, which determines the relaxation time of polymers. The fragility index has a strong relationship with the maximum ARST. For linear chains, during approaching Tg, the maximum ARST grew more abruptly, resulting in the larger fragility index.

New insights into petrogenesis of Miocene magmatism associated with porphyry copper deposits of the Andean Pampean flat slab, Argentina

The Paramillos de Uspallata mining district located in the backarc region of the Pampean flat-slab segment (28°–33°S) features porphyry-type deposits genetically associated with Middle Miocene volcanics. This mineralizing magmatism comprising hydrothermally altered (sodic-calcic, potassic and phyllic alteration) subvolcanic and pyroclastic rocks of andesite-basaltic andesite and dacite-rhyolite composition with a typical arc signature, represents the eastward broadening of the Farellones arc by ∼17 Ma. Its geochemistry also reveals a residual mineralogy of amphibole ± garnet with limited plagioclase fractionation resulting in an adakitic signal; however, according to the isotopic data collected in our study, the contributions of MASH (melting-assimilation-storage-homogenization) processes in the acquisition of this signal cannot be disregarded.Both the broadening of the Farellones arc and its residual mineralogy – typical of relatively deep magmatic chambers – are consistent with a slab shallowing and outcoming crustal thickening setting. This tectonic scenario could be interpreted as a result of an early effect of the Juan Fernandez Ridge collision that was further to the north by ∼17 Ma. Our findings suggest that magmas were fertile for porphyry type deposits during the early stages of the slab shallowing.

Heterogenic Distribution of Aromatic L-Amino Acid Decarboxylase Neurons in the Rat Spinal Cord.

Aromatic L-amino acid decarboxylase (AADC) is an essential enzyme in the synthesis of serotonin, dopamine, and certain trace amines and is present in a variety of organs including the brain and spinal cord. It is previously reported that in mammalian spinal cord AADC cells (called D-cells) were largely confined to a region around the central canal and that they do not produce monoamines. To date, there has not been a detailed description of their distribution and morphology in mammals. In the present study this issue is systematically investigated using immunohistochemistry. We have found that AADC cells in the rat spinal cord are both more numerous and more widely distributed than previously reported. In the gray matter, AADC neurons immunolabeled for NeuN were not only found in the region around the central canal but also in the dorsal horn, intermediate zone, and ventral horn. In the white matter a large number of glial cells were AADC-immunopositive in different spinal segments and the vast majority of these cells expressed oligodendrocyte and radial glial phenotypes. Additionally, a small number of AADC neurons labeled for NeuN were found in the white matter along the ventral median fissure. The shapes and sizes of AADC neurons varied according to their location. For example, throughout cervical and lumbar segments AADC neurons in the intermediate zone and ventral horn tended to be rather large and weakly immunolabeled, whereas those in comparable regions of sacrocaudal segments were smaller and more densely immunolabeled. The diverse morphological characteristics of the AADC cells suggests that they could be further divided into several subtypes. These results indicate that AADC cells are heterogeneously distributed in the rat spinal cord and they may exert different functions in different physiological and pathological situations.

Detection of Plaque in Coronary Artery in CMRI Images and 3D Visualization of Blood Flow

Detection of blocks in coronary arteries is becoming crucial interest for early detection of heart attacks. In this paper we propose a framework for detection of plaque in coronary arteries from cardio vascular magnetic resonance imaging(CMRI). It is a quantitative tool for the assessment of cardiovascular diseases. First, select a region of interest and segment the region of coronary artery using enhanced region based active contour (ERAC). Secondly the centreline extraction and lumen segmentation are integrated to extract the artery centreline using geometric moments and the vessel direction using Hessian matrix and segment the vessel lumen in each slice using ERAC. A boundary searching method is adapted to fine tune the segmented surface in each slice of CMRI image. Third, the soft plaques in the coronary artery are extracted by thresholding the segmented region. Finally a 3D visualization of blood flow in coronary artery is presented and the volume of blood flow is calculated. In the experiments we have employed 22 datasets of CMRI images. The experimental results show an average accuracy of 97.6% and with a mean and standard deviation of false discovery rate of 2.48 ± 0.002.

The Potential for Reassortment between Oropouche and Schmallenberg Orthobunyaviruses.

A number of viruses within the Peribunyaviridae family are naturally occurring reassortants, a common phenomenon for segmented viruses. Using a minigenome-reporter and virus-like particle (VLP) production assay, we have accessed the potential of Oropouche virus (OROV), Schmallenberg virus (SBV), and other orthobunyaviruses within the Simbu serogroup to reassort. We found that the untranslated region (UTR) in the medium segment is a potential contributing factor for reassortment by the tested viruses. We demonstrate that for promoter activity to occur it was essential that the viral RNA polymerase (L) and nucleocapsid (N) proteins were from the same virus, reinforcing the hypothesis that the large and small segments that encode these proteins segregate together during genome reassortment. Our results indicate that, given the right epidemiological setting, reassortment between SBV and OROV would potentially be feasible and could contribute to the emergence of a new Simbu virus.

Diagnostics of Coronal Bright Points using IRIS, AIA, and HMI Observations

We perform the detailed imaging and spectroscopic analysis of two coronal bright points (CBPs). These CBPs are dominated by bright dots or elongated bright features. Their rapid temporal variations lead to a continuous change in their overall morphology at chromospheric and transition-region (TR) temperatures. A 3D potential magnetic field extrapolation predicts the dominance of magnetic loops in the extent of both CBPs, which are clearly visible at the Si iv 1393.75 A line formation temperature. Short, low-lying magnetic loops or loop segments are the integral parts of these CBPs at TR temperature. A correlation between the various parameters of Mg ii resonance lines (e.g. intensity, Doppler velocity, velocity gradient) is present in the region of magnetic loops or loop segments. However, a quiet-Sun (QS) region does not show any correlation. Doppler velocities as well as the full width at half maximum (FWHM) of these lines are very prominent in the magnetic loops and loop segments compared to the Doppler velocities and FWHM in the QS region. Higher red-shifts and FWHM at TR temperatures are directly related to the dominance of the energy release process in these regions in the framework of the nanoflare model. A magnetogram from the Helioseismic and Magnetic Imager (HMI) onboard the Solar Dynamics Observatory (SDO) reveals the existence of two opposite magnetic polarities in the extent of both CBPs, which is a very well established result. We find that one CBP is formed by the convergence of two opposite magnetic polarities, while the other is triggered by the emergence of a new magnetic field prior to the onset of this CBP.

Mechanisms of noncovalent β subunit regulation of NaV channel gating.

Voltage-gated Na+ (NaV) channels comprise a macromolecular complex whose components tailor channel function. Key components are the non-covalently bound β1 and β3 subunits that regulate channel gating, expression, and pharmacology. Here, we probe the molecular basis of this regulation by applying voltage clamp fluorometry to measure how the β subunits affect the conformational dynamics of the cardiac NaV channel (NaV1.5) voltage-sensing domains (VSDs). The pore-forming NaV1.5 α subunit contains four domains (DI-DIV), each with a VSD. Our results show that β1 regulates NaV1.5 by modulating the DIV-VSD, whereas β3 alters channel kinetics mainly through DIII-VSD interaction. Introduction of a quenching tryptophan into the extracellular region of the β3 transmembrane segment inverted the DIII-VSD fluorescence. Additionally, a fluorophore tethered to β3 at the same position produced voltage-dependent fluorescence dynamics strongly resembling those of the DIII-VSD. Together, these results provide compelling evidence that β3 binds proximally to the DIII-VSD. Molecular-level differences in β1 and β3 interaction with the α subunit lead to distinct activation and inactivation recovery kinetics, significantly affecting NaV channel regulation of cell excitability.

Sexual and Regional Differences in Myosin Heavy Chain Expression in the Rat External Urethral Sphincter.

The external urethral sphincter is a unique striated muscle surrounding the urethra that plays a crucial role in urinary continence, and a comprehensive understanding of its morphology is needed to determine the pathophysiology underlying urinary incontinence and find suitable therapies. Differences between the sexes and among species regarding the fiber types present remain controversial. This study used triple immunofluorescence labeling to visualize one slow (Type 1) and two fast (Types 2A and 2B) myosin isoforms in rat external urethral sphincters from both sexes. Type 2A fibers predominated throughout the sphincter and Type 2B fibers were restricted to the proximal one-third of the external urethral sphincter in the female rats. Type 1 fibers were present adluminally and were concentrated in the proximal and distal segments of the sphincter. While most of the male external urethral sphincter comprised Type 2B fibers, Type 2A fibers intermingled among these fibers in the proximal one-third of the sphincter, and a few Type 1 fibers were present that were restricted to the adluminal region of the proximal segment. The fiber-type compositions and their areal densities changed in both sexes after gonadectomy. The areal density of the Type 1 fibers increased significantly in the ovariectomized females, especially in the distal segment. In the orchidectomized males, the areal densities of the Types 1 and 2A fibers increased significantly, but that of the Type 2B fibers decreased. These results indicate that myosin heavy chain expression in the rat external urethral sphincter is sexually dimorphic and shows regional differences. Anat Rec, 2017. © 2017 Wiley Periodicals, Inc. Anat Rec, 300:2058-2069, 2017. © 2017 Wiley Periodicals, Inc.