Adjacent Loops Research Articles

Analyses of epithelial Na+ channel variants reveal that an extracellular β-ball domain critically regulates ENaC gating

Epithelial Na+ channel (ENaC)-mediated Na+ transport has a key role in the regulation of extracellular fluid volume, blood pressure, and extracellular [K+]. Among the thousands of human ENaC variants, only a few exist whose functional consequences have been experimentally tested. Here, we used the Xenopus oocyte expression system to investigate the functional roles of four nonsynonymous human ENaC variants located within the β7-strand and its adjacent loop of the α-subunit extracellular β-ball domain. αR350Wβγ and αG355Rβγ channels exhibited 2.5- and 1.8-fold greater amiloride-sensitive currents than WT αβγ human ENaCs, respectively, whereas αV351Aβγ channels conducted significantly less current than WT. Currents in αH354Rβγ-expressing oocytes were similar to those expressing WT. Surface expression levels of three mutants (αR350Wβγ, αV351Aβγ, and αG355Rβγ) were similar to that of WT. However, three mutant channels (αR350Wβγ, αH354Rβγ, and αG355Rβγ) exhibited a reduced Na+ self-inhibition response. Open probability of αR350Wβγ was significantly greater than that of WT. Moreover, other Arg-350 variants, including αR350G, αR350L, and αR350Q, also had significantly increased channel activity. A direct comparison of αR350W and two previously reported gain-of-function variants revealed that αR350W increases ENaC activity similarly to αW493R, but to a much greater degree than does αC479R. Our results indicate that αR350W along with αR350G, αR350L, and αR350Q, and αG355R are novel gain-of-function variants that function as gating modifiers. The location of these multiple functional variants suggests that the αENaC β-ball domain portion that interfaces with the palm domain of βENaC critically regulates ENaC gating.

Coupled combustion and hydrodynamics simulation of a 1000 MW double-reheat boiler with different FGR positions

Flue gas recirculation (FGR) has been widely adopted as the steam temperature regulation method of choice for double-reheat boilers. In this work, the effect of the FGR position on the hydrodynamic characteristics of a double-reheat boiler is studied. Heat flux distributions of the water-cooled wall are determined through combustion simulation, then hydrodynamic characteristics of the boiler are calculated by user-defined program. The hydrodynamic characteristics including working fluid temperature, average tube temperature, fin-tip temperature, and temperature deviation between adjacent loops under 100% boiler maximum continuous rating (BMCR) and 75% turbine heat acceptance (THA) loads were numerically analyzed. The calculation results show that, under 100% BMCR and 75% THA loads, compared with the case that FGR introduced from the nozzle above the burner, the average tube and fin-tip temperatures at the outlet of water-cooled wall are higher, and the temperature deviation between adjacent loops is more significant, when the FGR is introduced from the nozzle below the burner. Therefore, it is suggested in this work that introducing FGR from the nozzle above the burner is safer for water-cooled walls of the 1000 MW double-reheat boiler.

Dislodged Nephrostomy Catheter: An Unusual Case of Idiopathic Transposition of Nephrostomy Catheter From Transplanted Kidney to Adjacent Small Bowel Loop: A Case Report

A 72-year-old man with a past medical history notable for deceased renal transplant presented to the interventional radiology department for routine right lower quadrant renal transplant nephroureteral catheter exchange. The nephroureteral catheter was placed in 2016 because of the presence of a hematoma causing partial page kidney and hydronephrosis.An antegrade nephrostogram was notable for opacification of the small bowel instead of the renal collecting system. The patient then subsequently developed urinary retention and intractable abdominal pain. Because of the combination of events, it was deemed necessary for laparotomy and surgical repair of the small bowel. Intraoperative findings were notable for small bowel adhesion to the abdominal wall but otherwise no evidence of acute inflammatory changes. In this case report, we describe the first case of an idiopathically dislodged nephrostomy catheter to the small bowel from a transplanted kidney and its successful management.

Structure and Dynamics of the Rhomboid Protease GlpG in Liposomes Studied by Solid-State NMR.

Rhomboid proteases are intramembrane proteases that hydrolyze substrate peptide bonds within the lipid bilayer and are important for a wide range of biological processes. The bacterial intramembrane protease GlpG is one of the model systems for structural investigations of the rhomboid family. Two different models of substrate gating have been proposed, based on crystal structures of GlpG in detergent micelles. Here, we present a detailed investigation of enzymatically active GlpG in a native-like lipid environment using solid-state NMR spectroscopy. Proton-detected experiments confirm the presence of water molecules in the catalytic cavity. A secondary chemical shift analysis indicates a previously unobserved kink in the central part of the gating helix TM5. Dynamics measurements revealed a dynamic hotspot of GlpG at the N-terminal part of TM5 and the adjacent loop L4, indicating that this region is important for gating. In addition, relaxation dispersion experiments suggest that TM5 is in conformational exchange between an open and a closed conformation.

Identification of significant chromatin contacts from HiChIP data by FitHiChIP

HiChIP/PLAC-seq is increasingly becoming popular for profiling 3D chromatin contacts among regulatory elements and for annotating functions of genetic variants. Here we describe FitHiChIP, a computational method for loop calling from HiChIP/PLAC-seq data, which jointly models the non-uniform coverage and genomic distance scaling of contact counts to compute statistical significance estimates. We also develop a technique to filter putative bystander loops that can be explained by stronger adjacent loops. Compared to existing methods, FitHiChIP performs better in recovering contacts reported by Hi-C, promoter capture Hi-C and ChIA-PET experiments and in capturing previously validated promoter-enhancer interactions. FitHiChIP loop calls are reproducible among replicates and are consistent across different experimental settings. Our work also provides a framework for differential HiChIP analysis with an option to utilize ChIP-seq data for further characterizing differential loops. Even though designed for HiChIP, FitHiChIP is also applicable to other conformation capture assays.

Design and Evaluation of a Novel Symmetric Multichannel Transmit/Receive Coil Array for Cardiac MRI in Pigs at 7 T

A dedicated, novel, multichannel transmit/receive (Tx/Rx) coil array was designed, simulated, and tested for cardiac magnetic resonance imaging (cMRI) of pigs at 7 T. The cardiac array was composed of 16 elements with physically independent anterior and posterior parts. The array was connected to the MRI scanner in the parallel transmit (pTx) mode forming an 8-channel transmit and 16-channel receive (8Tx/16Rx) coil configuration. The anterior array was composed of four central octagonal elements, which were decoupled using a common central ring (CCR) and shared decoupling capacitors. The surrounding four triangular elements were decoupled from the central four elements using gaps and capacitive decoupling. In total, the eight elements of the anterior array resembled a coil with a symmetrical circular shape. Due to the advantageous arrangement of the elements in conjunction with the novel decoupling method of a CCR, the coupling between the adjacent loop elements was minimized. The posterior array was built using a 4 × 2 standard rectangular, symmetric element configuration. The dedicated cardiac array was tested in phantom and in ex vivo MR measurements with a female pig of 46 kg. The dedicated coil array enhanced the signal-to-noise ratio (40 ± 27) in ex vivo measurements of the pig heart by about three times compared to a coil prototype for cardiac human imaging (11.8 ± 7). High-resolution, ex vivo cardiac images were acquired with an in-plane resolution of up to 0.3 mm × 0.3 mm using the dedicated pig coil array. The novel cardiac array supports parallel imaging with an acceleration factor (R) of 4 without increasing the mean g-factor within the heart region beyond 1.15.

Investigation of Na+ and K+ Transport in Halophytes: Functional Analysis of the HmHKT2;1 Transporter from Hordeum maritimum and Expression under Saline Conditions.

Control of K+ and Na+ transport plays a central role in plant adaptation to salinity. In the halophyte Hordeum maritimum, we have characterized a transporter gene, named HmHKT2;1, whose homolog HvHKT2;1 in cultivated barley, Hordeum vulgare, was known to give rise to increased salt tolerance when overexpressed. The encoded protein is strictly identical in two H. maritimum ecotypes, from two biotopes (Tunisian sebkhas) affected by different levels of salinity. These two ecotypes were found to display distinctive responses to salt stress in terms of biomass production, Na+ contents, K+ contents and K+ absorption efficiency. Electrophysiological analysis of HmHKT2;1 in Xenopus oocytes revealed distinctive properties when compared with HvHKT2;1 and other transporters from the same group, especially a much higher affinity for both Na+ and K+, and an Na+-K+ symporter behavior in a very broad range of Na+ and K+ concentrations, due to reduced K+ blockage of the transport pathway. Domain swapping experiments identified the region including the fifth transmembrane segment and the adjacent extracellular loop as playing a major role in the determination of the affinity for Na+ and the level of K+ blockage in these HKT2;1 transporters. The analysis (quantitative reverse transcription-PCR; qRT-PCR) of HmHKT2;1 expression in the two ecotypes submitted to saline conditions revealed that the levels of HmHKT2;1 transcripts were maintained constant in the most salt-tolerant ecotype whereas they decreased in the less tolerant one. Both the unique functional properties of HmHKT2;1 and the regulation of the expression of the encoding gene could contribute to H. maritimum adaptation to salinity.

Extending the Phantom Network Theory to Account for Cooperative Effect of Defects

Recent developments in network theory have extended the classical phantom network theory to account for different types of defects. These theories are typically linear and adopt the ideal defect gas approximation, which is valid only in the infinite dilution limit of defects. In this study, the Virial expansion is used to determine the cooperative effects of multiple loops. It was found that in most cases, the Virial coefficients of all order vanish, and adjacent loops have no more negative impact than the individual isolated loops. Furthermore, a general nonlinear theory was developed to calculate the elasticity of phantom networks beyond the dilute limit. It was found that for a tree‐like complete network, the dispersity of network strands does not affect the elasticity of the network. However, for a tree‐like incomplete network, as conversion is lowered, a much slower decrease in the elasticity is predicted by the nonlinear theory. Finally, for loopy networks, the nonlinear theory gave predictions almost identical to that of the linear theory in small loop fraction regime. However, as loop fraction is increased, the nonlinear theory predicts a significant negative deviation from the linear theory. This behavior qualitatively matches with the behavior observed in experiments.

Compact loop-type antenna with ground-mode tuning for dual-band IoT applications

ABSTRACTA compact dual-band loop-type antenna is proposed in a small-sized ground plane for Internet-of-Things (IoT) applications. The antenna element is comprised of two adjacent resonance loops, excited by two feeding loops at the back side of the substrate, to achieve independent control of dual-band IoT applications at 0.92 and 2.45 GHz, respectively. To improve the radiation performance of the lower band, the metal frames are adopted as ground-mode tuning structures to generate a new ground-mode resonance, producing dual-resonance characteristics at 0.9 GHz bands and generating greatly improved bandwidth and radiation efficiency. Therefore, both lower and higher bands with high performances are achieved in simulation and verified in measurement.

Single layer miniaturized ultra-thin FSS with five closely spaced bands

AbstractThis Paper reveals a novel single layer five band frequency selective surface (FSS). Novelties of the proposed FSS lie in its five closely spaced stop bands at 2.4, 3.38, 4.82, 6.32, and 7.75 GHz as well as the reduced single layer structural thickness (0.0016 λ0) and the miniaturized unit cell size (0.0656 λ0) at lower resonant frequency as compared to the existing multiband FSS. The unit cell structure consists of six octagonal concentric interconnected loops. Adjacent loop interconnection technique reduces the cell size by more than 44%. Furthermore, arrow-shaped rings are also introduced on each corner of the outermost octagonal loop, and using this technique approximate 23% cell miniaturization can be achieved. In addition, the proposed FSS exhibits excellent angular stability.

Molecular basis for feedback inhibition of tyrosine-regulated 3-deoxy-d-arabino-heptulosonate-7-phosphate synthase from Escherichia coli

3-Deoxy-d-arabino-heptulosonate-7-phosphate synthase (DAHPS) is responsible for the biosynthesis of essential aromatic compounds in microorganisms and plants. It plays a crucial role in the regulation of the carbon flow into the shikimate pathway. Until now, the crystal structures and regulatory mechanisms of dimeric DAHPS enzymes from type Iα subclass have not been reported. Here, we reported dimeric structures of the tyrosine-regulated DAHPS from Escherichia coli, both in its apo form and complex with the inhibitor tyrosine at 2.5 and 2.0 Å resolutions, respectively. DAHPS(Tyr) has a typical (β/α)8 TIM barrel, which is decorated with an N-terminal extension and an antiparallel β sheet, β6a/β6b. Inhibitor tyrosine binds at a cavity formed by residues of helices α3, α4, strands β6a, β6b and the adjacent loops, and directly interacts with residues P148, Q152, S181, I213 and N8*. Although the small angle X-ray scattering profiles from DAHPS(Tyr) with and without tyrosine shows that tyrosine binding leaves most of DAHPS(Tyr) structures unaffected. The comparison of the liganded and unliganded crystal structures reveals that conformational changes of residues P148, Q152 and I213 initiate a transmission pathway to propagate the allosteric signal from the tyrosine-binding site to the active site, which is different from DAHPS(Phe), a phenylalanine-regulated isozyme from E. coli. In addition, mutations of five tyrosine-binding residues P148, Q152, S181, I213 and N8* leads to tyrosine-resistant DAHPS(Tyr) enzymes. These findings provide a new insight into the regulatory mechanism of DAHPS enzymes and a basis for further engineering studies.

A collage of cholesterol interaction motifs in the serotonin1A receptor: An evolutionary implication for differential cholesterol interaction.

The serotonin1A receptor is a representative member of the G protein-coupled receptor (GPCR) superfamily and acts as an important drug target. In our previous work, we comprehensively demonstrated that membrane cholesterol is necessary in the organization, dynamics and function of the serotonin1A receptor. In this context, analysis of high-resolution GPCR crystal structures in general and in silico studies of the serotonin1A receptor in particular, have suggested the presence of cholesterol interaction sites (hotspots) in various regions of the receptor. In this work, we have identified an evolutionarily conserved collage of four categories of cholesterol interaction motifs associated with transmembrane helix V and the adjacent intracellular loop 3 fragment of the vertebrate serotonin1A receptor. This collage of motifs represents a total of twenty diverse context-dependent cholesterol interaction configurations. We envision that the gamut of cholesterol interaction sites, characterized by sequence plasticity in cholesterol interaction, could be relevant in receptor-cholesterol interaction in membranes of varying cholesterol content and organization, as found in diverse cell types. We conclude that an evolutionarily conserved mechanism of GPCR-cholesterol interaction allows the serotonin1A receptor to adapt to diverse membrane cholesterol levels during natural evolution.

Effects of Ser47-Point Mutation on Conformation Structure and Allergenicity of the Allergen of Der p 2, a Major House Dust Mite Allergen.

PurposeHypoallergenic recombinant Der p 2 has been produced by various genetic manipulations, but mutation of a naturally polymorphic amino acid residue known to affect IgE binding has not been studied. This study aimed to determine the effect of a point mutation (S47W) of residue 47 of Der p 2 on its structure and immunoglobulin (Ig) E binding. Its ability to induce pro-inflammatory responses and to induce blocking IgG antibody was also determined.MethodsS47 of recombinant Der p 2.0110, one of the predominant variants in Bangkok, was mutated to W (S47W). S47W secreted from Pichia pastoris was examined for secondary structure and for the formation of a hydrophobic cavity by 8-Anilino-1-naphthalenesulfonic acid (ANS) staining. Monoclonal and human IgE-antibody binding was determined by enzyme-linked immunosorbent assay. Allergen-induced degranulation by human epsilon receptor expressed-rat basophil was determined. Stimulation of the pro-inflammatory cytokine interleukin (IL)-8 release from human bronchial epithelial (BEAS2B) cells and inhibition of IgE binding to the wild type allergen by S47W-induced IgG were determined.ResultsS47W reduced secondary structure and failed to bind the hydrophobic ANS ligand as well as a monoclonal antibody known to be dependent on the nature of the side chain of residue 114 in an adjacent loop. It could also not stimulate IL-8 release from BEAS2B cells. IgE from house dust mite (HDM)-allergic Thais bound S47W with 100-fold weaker avidity, whereas IgE of HDM-allergic Australians did not. S47W still induced basophil degranulation, although requiring higher concentrations for some subjects. Anti-S47W antiserum-immunized mice blocked the binding of human IgE to wild type Der p 2.ConclusionsThe mutant S47W had altered structure and reduced ability to stimulate pro-inflammatory responses and to bind IgE, but retained its ability to induce blocking antibodies. It thus represents a hypoallergen produced by a single mutation of a non-solvent-accessible amino acid.

Regulation of myelin structure and conduction velocity by perinodal astrocytes

The speed of impulse transmission is critical for optimal neural circuit function, but it is unclear how the appropriate conduction velocity is established in individual axons. The velocity of impulse transmission is influenced by the thickness of the myelin sheath and the morphology of electrogenic nodes of Ranvier along axons. Here we show that myelin thickness and nodal gap length are reversibly altered by astrocytes, glial cells that contact nodes of Ranvier. Thrombin-dependent proteolysis of a cell adhesion molecule that attaches myelin to the axon (neurofascin 155) is inhibited by vesicular release of thrombin protease inhibitors from perinodal astrocytes. Transgenic mice expressing a dominant-negative fragment of VAMP2 in astrocytes, to reduce exocytosis by 50%, exhibited detachment of adjacent paranodal loops of myelin from the axon, increased nodal gap length, and thinning of the myelin sheath in the optic nerve. These morphological changes alter the passive cable properties of axons to reduce conduction velocity and spike-time arrival in the CNS in parallel with a decrease in visual acuity. All effects were reversed by the thrombin inhibitor Fondaparinux. Similar results were obtained by viral transfection of tetanus toxin into astrocytes of rat corpus callosum. Previously, it was unknown how the myelin sheath could be thinned and the functions of perinodal astrocytes were not well understood. These findings describe a form of nervous system plasticity in which myelin structure and conduction velocity are adjusted by astrocytes. The thrombin-dependent cleavage of neurofascin 155 may also have relevance to myelin disruption and repair.

One-dimensional oxalato-bridged heterobimetallic coordination polymers by using [the [Cr(pyim)(C2O4)2]− complex as metalloligand [pyim = 2-(2′-pyridyl)imidazole

Four new coordination polymers based on the use of the [Cr(pyim)(C2O4)2]− species as a metalloligand, namely [LiCr(pyim)(C2O4)2(MeOH)]n (1), {[CaCr2(pyim)2(C2O4)4]·2MeOH}n (2), {[SrCr2(pyim)2(C2O4)4(H2O)]·0.45MeOH·4.55H2O}n (3) and {[CdCr2(pyim)2(C2O4)4]·MeOH}n (4) [pyim = 2-(2′-pyridyl)imidazole] have been synthesized and characterized by elemental analyses, IR spectra and X-ray diffraction on single crystals. Complex 1 is a neutral heterobimetallic chain where the tris(chelated) chromium(III) unit acts as a bis-bidentate ligand towards {Li(MeOH)}+ fragments through its two oxalate ligands, each lithium ion being five-coordinate in a intermediate surrounding between square pyramidal and trigonal bipyramidal. The structure of 2 consists of neutral oxalato-bridged chromium(III)-calcium(II) double chains of single chirality [all the tris(chelated) chromium centres have the same chirality either Λ or λ] and methanol molecules of crystallization. Each calcium ion in 2 exhibits a square antiprism environment which is built by four bidentate oxalate ligands from four [Cr(pyim)(C2O4)2]− units. Neutral oxalato-bridged chromium(III)-strontium(II) double chains also occur in 3 with methanol and water molecules of crystallization, each alkaline-earth cation being nine-coordinate in a monocapped square antiprism environment which is defined by a water molecule and eight oxalate-oxygens from four [Cr(pyim)(C2O4)2]− units. The CrIII2MII2 loops [M = Ca (2) and Sr (3)] within each double chain are planar. The structure of 4 is also made of neutral oxalato-bridged chromium(III)-cadmium(II) double chains but in contrast to 2 and 3, the chirality of the tris(chelated) chromium unit in 4 is alternated in each loop and the adjacent CrIII2CdII2 loops are not planar but form a dihedral angle of 84.8°. The potential use of the [Cr(pyim)(C2O4)2]− entity as a metalloligand in designing heterobimetallic compounds is analyzed and discussed.

Photocrosslinking of G-Quadruplex-Forming Sequences found in Human Promoters.

While is it well known that human telomeric DNA sequences can adopt G-quadruplex structures, some promoters sequences have also been found to form G-quadruplexes, and over 40% of promoters contain putative G-quadruplex-forming sequences. Because UV light has been shown to crosslink human telomeric G-quadruplexes by cyclobutane pyrimidine dimer (CPD) formation between T's on adjacent loops, UV light might also be able to photocrosslink G-quadruplexes in promoters. To investigate this possibility, 15 potentially UV-crosslinkable G-quadruplex-forming sequences found in a search of human DNA promoters were UVB irradiated invitro, and three were confirmed to have formed nonadjacent CPDs by mass spectrometry. In addition to nonadjacent T=T CPDs found in human telomeric DNA, a nonadjacent T=U CPD was discovered that presumably arose from deamination of a nonadjacent T=C CPD. Analysis of the three sequences by circular dichroism, melting temperature analysis and chemical footprinting confirmed the presence of G-quadruplexes that could explain the formation of the nonadjacent CPDs. The formation of nonadjacent CPDs from the sequences invitro suggests that they might be useful probes for the presence of non-B DNA structures, such as G-quadruplexes, invivo, and if they were to form invivo, might also have significant biological consequences.

Conformational changes on substrate binding revealed by structures of Methylobacterium extorquens malate dehydrogenase.

Three high-resolution X-ray crystal structures of malate dehydrogenase (MDH; EC 1.1.1.37) from the methylotroph Methylobacterium extorquens AM1 are presented. By comparing the structures of apo MDH, a binary complex of MDH and NAD+, and a ternary complex of MDH and oxaloacetate with ADP-ribose occupying the pyridine nucleotide-binding site, conformational changes associated with the formation of the catalytic complex were characterized. While the substrate-binding site is accessible in the enzyme resting state or NAD+-bound forms, the substrate-bound form exhibits a closed conformation. This conformational change involves the transition of an α-helix to a 310-helix, which causes the adjacent loop to close the active site following coenzyme and substrate binding. In the ternary complex, His284 forms a hydrogen bond to the C2 carbonyl of oxaloacetate, placing it in a position to donate a proton in the formation of (2S)-malate.

Anti-MAG neuropathy: Role of IgM antibodies, the paranodal junction and juxtaparanodal potassium channels

ObjectiveTo improve understanding of disease pathophysiology in anti-myelin-associated glycoprotein (anti-MAG) neuropathy to guide further treatment approaches. MethodsAnti-MAG neuropathy patients underwent clinical assessments, nerve conduction and excitability studies, and ultrasound assessment. ResultsPatients demonstrated a distinctive axonal excitability profile characterised by a reduction in superexcitability [MAG: −14.2 ± 1.6% vs healthy controls (HC): −21.8 ± 1.2%; p < 0.01] without alterations in most other excitability parameters. Mathematical modelling of nerve excitability recordings suggested that changes in axonal function could be explained by a 72.5% increase in juxtaparanodal fast potassium channel activation and an accompanying hyperpolarization of resting membrane potential (by 0.3 mV) resulting in a 94.2% reduction in discrepancy between anti-MAG data and the healthy control model. Superexcitability changes correlated strongly with clinical and neurophysiological parameters. Furthermore, structural assessments demonstrated a proximal pattern of nerve enlargement (C6 nerve root cross-sectional area: 15.9 ± 8.1 mm2 vs HC: 9.1 ± 2.3 mm2; p < 0.05). ConclusionsThe imaging and neurophysiological results support the pathogenicity of anti-MAG IgM. Widening between adjacent loops of paranodal myelin due to antibodies would expand the pathway from the node to the juxtaparanode, increasing activation of juxtaparanodal fast potassium channels, thereby impairing saltatory conduction. SignificancePotassium channel blockers may prove beneficial in restoring conduction closer to its normal state and improving nerve function in anti-MAG neuropathy.

Effect of heat load on microstructural development in an irradiated low alloy steel

To investigate the influence of heat load on microstructure change, we conducted in-situ experiments of annealing and irradiation for a model alloy (Fe-0.75Mn-0.47Mo-0.45Ni) using a multi-beam high voltage electron microscope. Electron-irradiation resulted in the formation of black dots in the model alloy. It is noted that some of black dots grew and changed to dislocation loops, but some did not. Furthermore, the 500 °C annealing to the electron-irradiated sample resulted in the shrinkage and/or the disappearance of black dots and small loops (<10 nm). It is suggested that the annealing would cause the release of interstitial atoms from small loops, which could flow into adjacent larger loops or diffuse to the surface.

Decoupling of a double‐row 16‐element tight‐fit transceiver phased array for human whole‐brain imaging at 9.4 T

One of the major challenges in constructing multi-channel and multi-row transmit (Tx) or transceiver (TxRx) arrays is the decoupling of the array's loop elements. Overlapping of the surface loops allows the decoupling of adjacent elements and also helps to improve the radiofrequency field profile by increasing the penetration depth and eliminating voids between the loops. This also simplifies the design by reducing the number of decoupling circuits. At the same time, overlapping may compromise decoupling by generating high resistive (electric) coupling near the overlap, which cannot be compensated for by common decoupling techniques. Previously, based on analytical modeling, we demonstrated that electric coupling has strong frequency and loading dependence, and, at 9.4T, both the magnetic and electric coupling between two heavily loaded loops can be compensated at the same time simply by overlapping the loops. As a result, excellent decoupling was obtained between adjacent loops of an eight-loop single-row (1×8) human head tight-fit TxRx array. In this work, we designed and constructed a 9.4-T (400-MHz) 16-loop double-row (2×8) overlapped TxRx head array based on the results of the analytical and numerical electromagnetic modeling. We demonstrated that, simply by the optimal overlap of array loops, a very good decoupling can be obtained without additional decoupling strategies. The constructed TxRx array provides whole-brain coverage and approximately 1.5 times greater Tx efficiency relative to a transmit-only/receive-only (ToRo) array, which consists of a larger Tx-only array and a nested tight-fit 31-loop receive (Rx)-only array. At the same time, the ToRo array provides greater peripheral signal-to-noise ratio (SNR) and better Rx parallel performance in the head-feet direction. Overall, our work provides a recipe for a simple, robust and very Tx-efficient design suitable for parallel transmission and whole-brain imaging at ultra-high fields.