Central Loop Research Articles

7308 A Case of Thyroid Hormone Resistance Associated With a Novel Mutation in the THRA Gene

Abstract Disclosure: J.A. Siddiqui: None. M. Barbosa: None. V. Fettig: None. C.J. Romero: None. Introduction: Thyroid hormone resistance (THR) is a syndrome leading to decreased response of target organs to thyroid hormone. Normal thyroid hormone action is mediated by thyroid hormone nuclear receptors and is essential for normal development and metabolism. Two isoforms are encoded by the thyroid hormone receptor α and β genes (THRA and THRB). Mutations in THRB are commonly reported with limited cases of THRA mutations. We report a 15-month-old and her mother with a pathogenic variant in the THRα receptor leading to thyroid hormone resistance. CASE: A 15-month-old ex-39-week gestation female was born small for gestational age (birth weight: 2450 grams,3rd %ile and birth length: 17 inches,1st %ile). The newborn screen was normal. She presented with macroglossia, low tone and global developmental delay. She had severe constipation complicated by rectal prolapse that required surgical correction. There are multiple relatives (mother, maternal half-brother and maternal grandparents) with neurodevelopmental issues. The mother’s previous genetic evaluation was non-diagnostic. Mother reports a thyroid condition but without treatment. The patient was initially referred to genetics and whole exome sequencing revealed a heterozygous c.1205 T>C p. (L402P) variant in the THRα gene, which was maternally inherited and reported as a variant of uncertain significance. On physical exam, Heart rate was 112 bpm; height <1%ile (Z-score -3.22 SD), weight 3%ile (Z-score -1.89 SD). Patient has a wide anterior fontanelle (4x3 cm), macroglossia and delayed teeth eruption. Other exam findings: non-palpable thyroid and postaxial polydactyly on the 5th digit of the right toe. Thyroid hormone testing: normal TSH 1.829 uIU/mL, low total T4 4.4 mcg/dL, low Free T4 of 0.58 ng/dL and high free T3 of 4.24 pg/mL. Levothyroxine treatment was initiated(25 mcg daily). After 1 month treatment, TSH level was 0.23 uIU/mL, total T4 was 6.1 mcg/dL and low reverse T3 of 5.8 ng/dL. DISCUSSION: Thyroid hormone resistance due to THRα mutations are rare and under-recognized. The main clinical phenotype includes growth retardation, delayed development, decreased muscle tone, delayed tooth eruption and constipation. Unlike patients with THRβ mutations, the hypothalamus-pituitary-thyroid axis in patients with THRα mutations is minimally affected with a normal TSH level. Total T3 levels are elevated with slightly low total T4 and free T4:T3 ratio is low. Treatment with levothyroxine leads to suppressions of TSH levels, therefore confirming intact central T3 feedback loop. Reports, however, show minor clinical improvements with treatment; therefore further research is needed in these patients to explore more effective therapeutic options. We present a case of a novel congenital THRA mutation leading to a clinical phenotype consistent with THR. She continues care in our clinic with hopes to further study her mutation. Presentation: 6/2/2024

Investigation of Aquifer Zone using Central Loop Time-domain Electromagnetic in Institut Teknologi Bandung

Abstract Time-domain electromagnetic (TDEM) has been widely used to investigate the subsurface aquifer. In this research, the TDEM method with a central loop configuration was employed to define the aquifer zone in the southern area of the Institut Teknologi Bandung (ITB) campus in Bandung, Indonesia. Moreover, TDEM is effective for mapping aquifers due to its sensitivity to subsurface conductivity. The acquisition consists of five sounding points spaced 20 meters apart, along with a W-E profile in the southern area of ITB. The data were interpreted using 1D inversion software (1X1D, Interpex, USA), utilizing weights from a smoothing constraint scheme (Occam) to obtain the resistivity distribution of the subsurface structure. The interpretation results indicate three layers from top to bottom: (a) the topsoil was interpreted as a sand layer with resistivity of 100 to 350 Ωm; (b) beneath it lies a shale layer with resistivity ranging from 5 to 100 Ωm that has good porosity to allow water from the surface to flow into the ground; and (c) further down, there is a clay layer with low resistivity of 1 to 5 Ωm which act as impermeable layer.

The brassinosteroid receptor StBRI1 promotes tuber development by enhancing plasma membrane H+-ATPase activity in potato.

The brassinosteroid (BR) receptor BRASSINOSTEROID-INSENSITIVE 1 (BRI1) plays a critical role in plant growth and development. Although much is known about how BR signaling regulates growth and development in many crop species, the role of StBRI1 in regulating potato (Solanum tuberosum) tuber development is not well understood. To address this question, a series of comprehensive genetic and biochemical methods were applied in this investigation. It was determined that StBRI1 and Solanum tuberosum PLASMA MEMBRANE (PM) PROTON ATPASE2 (PHA2), a PM-localized proton ATPase, play important roles in potato tuber development. The individual overexpression of StBRI1 and PHA2 led to a 22% and 25% increase in tuber yield per plant, respectively. Consistent with the genetic evidence, in vivo interaction analysis using double transgenic lines and PM H+-ATPase activity assays indicated that StBRI1 interacts with the C-terminus of PHA2, which restrains the intramolecular interaction of the PHA2 C-terminus with the PHA2 central loop to attenuate autoinhibition of PM H+-ATPase activity, resulting in increased PHA2 activity. Furthermore, the extent of PM H+-ATPase autoinhibition involving phosphorylation-dependent mechanisms corresponds to phosphorylation of the penultimate Thr residue (Thr-951) in PHA2. These results suggest that StBRI1 phosphorylates PHA2 and enhances its activity, which subsequently promotes tuber development. Altogether, our results uncover a BR-StBRI1-PHA2 module that regulates tuber development and suggest a prospective strategy for improving tuberous crop growth and increasing yield via the cell surface-based BR signaling pathway.

A small-loop double-coil decoupling TEM device for high sensitivity near surface detection

Small loop transient electromagnetic (TEM) devices, several meters in size, are increasingly applied to near-surface geophysical exploration in space-limited environment. But the transmitter (TX) coil significantly affects the early time data acquisition of the receiver (RX) coil during current turn-off, resulting in the loss of shallow signals and creating a significant blind zone problem. We report a double-coil decoupling TEM (DCDTEM) device to solve this problem. The novel DCDTEM device ensures a weak primary magnetic flux region between the two coplanar transmitter (TX) coils with the same current direction and different radii. Simulation results indicate that the transmitting field of the DCDTEM device is more focused compared to the traditional central loop device, ensuring a stronger coupling with the target. 3-D TEM forward modeling results show that the DCDTEM device has the highest detection sensitivity, together with a relatively high lateral resolution compared to other small-loop TEM devices. We further carry out several physical experiments to test the response characteristics of the DCDTEM device with reference to both the offset and the ratio of turns between the TX and RX coils. The experimental results ensure that the position of the zero magnetic flux point can be accurately calibrated and mitigate interference from TX coils. The proposed DCDTEM device is also applied in a field test on water pipe detection, demonstrating its practicality in near-surface detection.

Recovering induced polarization effects from 1-D coupled inversion of transient electromagnetic data

SUMMARY Induced polarization (IP) effects can significantly affect and superimpose the inductive earth response, leading to heavily distorted data and, if overlooked, false geological interpretation. In this paper, we implemented the Levenberg–Marquardt (LM) and very fast simulated annealing (VFSA) algorithms to recover IP effects from central loop transient electromagnetic (TEM) data. To incorporate the IP effect in the TEM response, we used the Cole–Cole parametrization, maximum phase angle (MPA), maximum imaginary conductivity (MIC) and Jeffrey transform of Cole–Cole parameters. The result of 1-D forward calculation and inversion of synthetic TEM data revealed that the Cole–Cole parametrization is more robust and reliable than MPA, MIC and Jeffrey transform, and that the synthetic data were well fitted and IP parameters well recovered using this model. However, the incorporation of the IP effect leads to a highly nonlinear and non-unique inverse problem which requires an accurate starting model, especially for LM inversion. To evaluate the performance of our algorithm using field data, we carried out a 1-D inversion of TEM data acquired along a profile that traverses a waste site located near Cologne, Germany. Furthermore, to obtain a priori information and validate the result of TEM data modelling, we conducted an electrical resistivity tomography (ERT) and time-domain IP (TDIP) survey along the TEM profile. A 2-D inversion was used to retrieve the Cole–Cole parameters as input for TEM interpretation. By including the IP information, the TEM field data can be explained quantitively, and a consistent and improved interpretation of the waste body is achieved.

MTIR-SCP nuclear safety concept

The MTIR-SCP reactor is a research reactor with a light-water coolant having a fast neutron spectrum in nominal operation. None of the existing or projected reactors has a set of these features, therefore, special attention should be paid to the choice of the design of control rods and their location. The article considers various designs of control rods characteristic of the VVER-SCP power reactor currently under development, as well as existing research reactors with a liquid metal coolant having a fast neutron spectrum, taking into account the features of the MTIR-SCP: a seven-element control rod assembly design, as well as a ring-type absorbing element. Efficiency calculations are carried out for each of the structures under consideration and it was determined that the design of a control rod with an annular type of absorbing element has the highest specific efficiency. This design is chosen as the main one for the MTIR- SCP reactor. Criteria are proposed and optimization of the placement of control rods in the reactor core is carried out in order to reduce the uncertainty of obtaining neutron-physical characteristics in the central autonomous loop channel and increase the flow density in it. When optimizing the placement of control rods in the research reactor, their influence on the main neutron-physical characteristics, and especially on their distribution during operation under nominal conditions, is taken into account. Emergency protection and compensating rods that compensate for temperature and density effects when the reactor reaches the nominal power level have been removed, therefore their effect on the neutron-physical characteristics of the reactor and the loop channel during operation at power is not significant, and the compensating rods are located in the core and are removed as the fuel burns out, therefore their effect on the spatial The distribution of neutron-physical characteristics will be significant. To reduce this effect, burnout compensators and automatic regulators are proposed to be moved outside the core into the reflector. For various reactor conditions, the efficiency of the control and protection system was evaluated. It is shown that in various states, the control rods transfer the reactor to the required level of subcriticality, in accordance with NP-009-17.

Emergence of Complex Network Topologies from Flow-Weighted Optimization of Network Efficiency

Transportation and distribution networks are a class of spatial networks that have been of interest in recent years. These networks are often characterized by the presence of complex structures such as central loops paired with peripheral branches, which can appear both in natural and manmade systems, such as subway and railway networks. In this study, we investigate the conditions for the emergence of these nontrivial topological structures in the context of human transportation in cities. We propose a simple model for spatial networks generation, where a network lattice acts as a planar substrate and edge speeds define an effective temporal distance which we aim to optimize and quantifies the efficiency in exploring the urban space. Complex network topologies can be recovered from the optimization of edges’ speeds and we study how the interplay between a flow probability between two nodes in space and the associated travel cost influences the resulting optimal network. In the perspective of urban transportation we simulate these flows by means of human mobility models to obtain origin-destination matrices. We find that when using simple lattices, the obtained optimal topologies transition from treelike structures to more regular networks, depending on the spatial range of flows. Remarkably, we find that branches paired to large loops structures appear as optimal structures when the network is optimized for an interplay between heterogeneous mobility patterns of small range travels and longer-range ones typical of commuting. Moreover, when congestion dynamics in traffic routing is considered, we study the emergence of additional edges from the tree structure to mitigate temporal delays. Finally, we show that our framework is able to recover the statistical spatial properties of the Greater London area subway network. Published by the American Physical Society 2024

Clock gene homologs lin-42 and kin-20 regulate circadian rhythms in C. elegans

Circadian rhythms are endogenous oscillations in nearly all organisms, from prokaryotes to humans, allowing them to adapt to cyclical environments for close to 24 h. Circadian rhythms are regulated by a central clock, based on a transcription-translation feedback loop. One important protein in the central loop in metazoan clocks is PERIOD, which is regulated in part by Casein kinase 1ε/δ (CK1ε/δ) phosphorylation. In the nematode Caenorhabditis elegans, period and casein kinase 1ε/δ are conserved as lin-42 and kin-20, respectively. Here, we studied the involvement of lin-42 and kin-20 in the circadian rhythms of the adult nematode using a bioluminescence-based circadian transcriptional reporter. We show that mutations of lin-42 and kin-20 generate a significantly longer endogenous period, suggesting a role for both genes in the nematode circadian clock, as in other organisms. These phenotypes can be partially rescued by overexpression of either gene under their native promoter. Both proteins are expressed in neurons and epidermal seam cells, as well as in other cells. Depletion of LIN-42 and KIN-20, specifically in neuronal cells after development, was sufficient to lengthen the period of oscillating sur-5 expression. Therefore, we conclude that LIN-42 and KIN-20 are critical regulators of the adult nematode circadian clock through neuronal cells.

EARLY MEDIEVAL MIRRORS WITH A CENTRAL LOOP FROM THE SUMTSOV KHARKIV MUSEUM OF HISTORY COLLECTION

The archaeological collection of the Sumtsov Kharkiv History Museum contains 69 mirrors with a central loop on the reverse side, which were discovered by museum expedition in 1982—2021 at the Verkhnii Saltiv (VS), Staryyi Saltiv (SS) and Rubizhne burial grounds. 63 mirrors were unearthed in the burial assemblages of the big Verkhnii Saltiv necropolis: 26 mirrors come from 22 catacombs of the burial ground (VS 1), 14 mirrors from 12 catacombs of the third burial ground (VS III), 23 mirrors from 21 catacombs of the fourth burial ground (VS IV). One more mirror comes from the burials of the Rubizhne burial ground and 5 mirrors from the catacombs of the Verkhnii Saltiv necropolis. Most of the mirrors were found intact. Only catacombs 70 (VS 1) and 110 (VS IV) contained the mirrors that were deliberately broken in antiquity. Mirror fragments with traces of being in the fire were found in catacomb 19 of VS III. A half of mirror was found in catacomb 6 of VS III, while a whole mirror was also found in the same assemblage. In all cases, mirrors were part of the grave goods of adult women of reproductive age. Mirrors in most cases were lying face downwards and were located not far from the head of their owner. Mirrors from the museum’s collection are quite diverse in terms of ornamental motifs on the reverse side of HX. There are mirrors in the collection, which according to the classification of V. B. Kovalevska belong to taxa 1, 4a, 4g, 4z, 9b, 10a, 13, 14b, 17v, 20d, 22v, 23b, 27, 31v. The catacomb grave goods shows that mirrors of taxa 1, 4a, 4g, 4z, 96, 13, 22v were widespread among the Alan population throughout the entire existence of the Saltiv culture. Mirrors of taxa 10a, 14v, 17c, 20d, 22v, 23v, 27, 31v, and mirrors with lotus-shaped ornament are more typical of the Saltiv assemblages of the 1st century. At the same time, during this period the most popular the mirrors of 17в taxon were, which numerically prevail over mirrors of all other types. Imported (Chinese) mirrors in the Saltiv assemblages are represented in the form of replicas, which were made too far from the original. All replicas of imported mirrors were found in burials belonging to representatives of the social and property upper class of the Saltiv society in the region.

Specific Amino Acid Residues in the Three Loops of Snake Cytotoxins Determine Their Membrane Activity and Provide a Rationale for a New Classification of These Toxins.

Cytotoxins (CTs) are three-finger membrane-active toxins present mainly in cobra venom. Our analysis of the available CT amino acid sequences, literature data on their membrane activity, and conformational equilibria in aqueous solution and detergent micelles allowed us to identify specific amino acid residues which interfere with CT incorporation into membranes. They include Pro9, Ser28, and Asn/Asp45 within the N-terminal, central, and C-terminal loops, respectively. There is a hierarchy in the effect of these residues on membrane activity: Pro9 > Ser28 > Asn/Asp45. Taking into account all the possible combinations of special residues, we propose to divide CTs into eight groups. Group 1 includes toxins containing all of the above residues. Their representatives demonstrated the lowest membrane activity. Group 8 combines CTs that lack these residues. For the toxins from this group, the greatest membrane activity was observed. We predict that when solely membrane activity determines the cytotoxic effects, the activity of CTs from a group with a higher number should exceed that of CTs from a group with a lower number. This classification is supported by the available data on the cytotoxicity and membranotropic properties of CTs. We hypothesize that the special amino acid residues within the loops of the CT molecule may indicate their involvement in the interaction with non-lipid targets.

Mapping the membrane orientation of auxin homeostasis regulators PIN5 and PIN8 in Arabidopsis thaliana root cells reveals their divergent topology

PIN proteins establish the auxin concentration gradient, which coordinates plant growth. PIN1-4 and 7 localized at the plasma membrane (PM) and facilitate polar auxin transport while the endoplasmic reticulum (ER) localized PIN5 and PIN8 maintain the intracellular auxin homeostasis. Although an antagonistic activity of PIN5 and PIN8 proteins in regulating the intracellular auxin homeostasis and other developmental events have been reported, the membrane topology of these proteins, which might be a basis for their antagonistic function, is poorly understood. In this study we optimized digitonin based PM-permeabilizing protocols coupled with immunocytochemistry labeling to map the membrane topology of PIN5 and PIN8 in Arabidopsis thaliana root cells. Our results indicate that, except for the similarities in the orientation of the N-terminus, PIN5 and PIN8 have an opposite orientation of the central hydrophilic loop and the C-terminus, as well as an unequal number of transmembrane domains (TMDs). PIN8 has ten TMDs with groups of five alpha-helices separated by the central hydrophilic loop (HL) residing in the ER lumen, and its N- and C-terminals are positioned in the cytoplasm. However, the topology of PIN5 comprises nine TMDs. Its N-terminal end and the central HL face the cytoplasm while its C-terminus resides in the ER lumen. Overall, this study shows that PIN5 and PIN8 proteins have a divergent membrane topology while introducing a toolkit of methods for studying membrane topology of integral proteins including those localized at the ER membrane.

Explicit observation of tertiary magnetic field in TDEM transients; plausible explanation towards induced polarization effect in geophysical prospecting

In time domain electromagnetic central loop sounding or coincidence loop measurements often a sign reversal is observed in the recorded decay transients. These negative decay transients are generally attributed to induced polarization effect. We observed a similar sign reversal in the decay transients recorded with SQUID as a receiver in central loop sounding measurements at later decay times. The magnitude of the secondary magnetic field observed in the negative decay transients is considerably high and the SQUID output never reaches its noise floor even at decay times of >155 ms. This observation stimulated us to record the current flow in the transmitter loop and therefore a small resistor is connected in series with the transmitter loop. Decay transients have been recorded simultaneously across the resistor and the SQUID which is located at the centre of the transmitter loop. To our surprise, the time at which the sign reversal occurred in the recorded decay transients with SQUID and across the resistor confirmed that the SQUID is recording the magnetic field produced by the flow of the induced current in the transmitter loop in addition to the decay of the secondary magnetic field from the ground. A novel hypothesis has been proposed to explain the flow of induced current in the transmitter loop and extensive laboratory experimental simulations have been performed to prove it. The proposed novel hypothesis explains the occurrence of sign reversal in TEM systems not only in single loop but also in coincidence loop and central loop TEM configurations. In all cases, the sign reversal is due to the self induced tertiary magnetic fields. In this work, a set of transient measurements have been carried out with different targets and different thicknesses. The experiments have been repeated by locating the targets at different depths in order observe the response of the tertiary magnetic field in the decay transients. The experimental data and subsequent analysis confirmed our hypothesis that the self induced tertiary magnetic field is responsible for the sign reversals rather than the induced polarization effects.

Control of leaf development in the water fern Ceratopteris richardii by the auxin efflux transporter CrPINMa in the CRISPR/Cas9 analysis

BackgroundPIN-FORMED genes (PINs) are crucial in plant development as they determine the directionality of auxin flow. They are present in almost all land plants and even in green algae. However, their role in fern development has not yet been determined. This study aims to investigate the function of CrPINMa in the quasi-model water fern Ceratopteris richardii.ResultsCrPINMa possessed a long central hydrophilic loop and characteristic motifs within it, which indicated that it belonged to the canonical rather than the non-canonical PINs. CrPINMa was positioned in the lineage leading to Arabidopsis PIN6 but not that to its PIN1, and it had undergone numerous gene duplications. CRISPR/Cas9 genome editing had been performed in ferns for the first time, producing diverse mutations including local frameshifts for CrPINMa. Plants possessing disrupted CrPINMa exhibited retarded leaf emergence and reduced leaf size though they could survive and reproduce at the same time. CrPINMa transcripts were distributed in the shoot apical meristem, leaf primordia and their vasculature. Finally, CrPINMa proteins were localized to the plasma membrane rather than other cell parts.ConclusionsCRISPR/Cas9 genome editing is feasible in ferns, and that PINs can play a role in fern leaf development.

Abstract 1682 Role of Central Loop Region in Apolipoprotein AI in Lipid Binding

Abstract 1682 Role of Central Loop Region in Apolipoprotein AI in Lipid Binding

A sodium/potassium switch for G4-prone G/C-rich sequences.

Metal ions are essential components for the survival of living organisms. For most species, intracellular and extracellular ionic conditions differ significantly. As G-quadruplexes (G4s) areion-dependent structures, changes in the [Na+]/[K+] ratio may affect the folding of genomic G4s. More than 11000 putative G4 sequences in the human genome (hg19) contain at least two runs of three continuous cytosines, and these mixed G/C-rich sequences may form a quadruplex or a competing hairpin structure based on G-C base pairing. In this study, we examine how the [Na+]/[K+] ratio influences the structures of G/C-rich sequences. The natural G4 structure with a9-nt long central loop, CEBwt, was chosen as a model sequence, and the loop bases were gradually replaced by cytosines. The series of CEB mutations revealed that the presence of cytosines in G4 loops does not prevent G4 folding or decrease G4 stability but increases the probability of forming a competing structure, either a hairpin or an intermolecular duplex. Slow conversion to the quadruplex in vitro (in a potassium-rich buffer) and cells was demonstrated by NMR. 'Shape-shifting' sequences may respond to [Na+]/[K+] changes with delayed kinetics.

SYNTHETIC PEPTIDE FRAGMENTS OF THE TOXIN WTX REDUCE BLOOD PRESSURE IN RATS UNDER GENERAL ANESTHESIA

Previously, it was shown that the non-conventional toxin WTX from the venom of the cobra Naja kaouthia, when administered intravenously, caused a decrease in blood pressure (BP) and an increase in heart rate (HR) in rats (Ogay et al., 2005). To identify the site of the toxin molecule responsible for these effects, we studied the influence of synthetic peptide fragments of the WTX on BP and HR in normotensive male Sprague Dawley rats under general anesthesia induced by Telazol and Xylazine. It was found that peptides corresponding to the WTX central polypeptide loop, stabilized by a disulfide bond, at intravenous injection at concentrations from 0.1 to 1.0 mg/ml caused a dose-dependent decrease in BP, the HR increasing only in the first 5–10 minutes after administration. Thus, WTX fragments corresponding to the central polypeptide loop reproduce the decrease in blood pressure caused by the toxin.

Light rare earth elements stabilize G-quadruplex structure in variants of human telomeric sequences

Recently, light rare earth elements (LREEs) are gaining importance in modern-day technologies. Thus, the entry of LREEs into biochemical pathways cannot be ignored, which might affect the conformation of biomacromolecules. Herein, for the first time, we discover the G-quadruplex formation in the human telomeric variants in presence of micromolar concentrations of LREEs. Thermal melting show that the LREE-induced unimolecular G-quadruplex structure. Isothermal titration calorimetry, UV–vis, and CD spectroscopy results suggest the binding stoichiometry of lanthanide ions to telomeric variants is 2:1. The data confirms that the LREE ions coordinate between adjacent G-quartets. The excess LREE ions are most likely binding to quadruplex loops. The CD spectra revealed that the LREE-induced quadruplex in human telomere and its variant have antiparallel orientation. The binding equilibria of LREEs have been studied both in the presence and absence of competing metal cations. Addition of LREEs to the Na+ or K+-induced G-quadruplexes led to conformational change, which may be ascribed to the displacement of K+ or Na+ ions by LREE ions and formation of a more compact LREE-induced G-quadruplex structure in human telomeric variant. Moreover, the thymine in the central loop of the human telomeric sequence stabilizes LREE induced G-quadruplex.

Synthetic Peptide Fragments of the Wtx Toxin Reduce Blood Pressure in Rats under General Anesthesia

Previously, it was shown that the non-conventional toxin WTX from the venom of the cobra Naja kaouthia, when administered intravenously, caused a decrease in blood pressure (BP) and an increase in heart rate (HR) in rats [13]. To identify the site of the toxin molecule responsible for these effects, we studied the influence of synthetic peptide fragments of the WTX on BP and HR in normotensive male Sprague–Dawley rats under general anesthesia induced by Telazol and Xylazine. It was found that peptides corresponding to the WTX central polypeptide loop, stabilized by a disulfide bond, at intravenous injection at concentrations from 0.1 to 1.0 mg/mL caused a dose-dependent decrease in BP, with the HR increasing only in the first 5–10 min after administration. Thus, WTX fragments corresponding to the central polypeptide loop reproduce the decrease in blood pressure caused by the toxin.

Liver factor B silencing to cure C3 glomerulopathy: Evidence from a mouse model of complement dysregulation

Uncontrolled activation of the alternative pathway (AP) of complement, due to genetic and/or acquired defects, plays a primary pathogenetic role in C3 glomerulopathy (C3G), a rare and heterogeneous disease characterised by predominant C3 fragment deposition within the glomerulus, as well as glomerular damage. There are currently no approved disease-specific treatments for C3G, but new drugs that directly counteract AP dysregulation, targeting components of the pathway, have opened promising new perspectives for managing the disease.Complement factor B (FB), which is primarily synthesised by hepatocytes, is a key component of the AP, as it drives the central amplification loop of the complement system. In this study we used a GalNAc (N-Acetylgalactosamine)-conjugated siRNA to selectively target and suppress liver FB expression in two mouse models characterised by the complete (Cfh-/- mice) or partial (Cfh+/-) loss of function of complement factor H (FH). Homozygous deletion of FH induced a severe C3G phenotype, with strong dysregulation of the AP of complement, glomerular C3 deposition and almost complete C3 consumption. Mice with a heterozygous deletion of FH had intermediate C3 levels and exhibited slower disease progression, resembling human C3G more closely.Here we showed that FB siRNA treatment did not improve serum C3 levels, nor limit glomerular C3 deposition in Cfh-/- mice, while it did normalise circulating C3 levels, reduce glomerular C3 deposits, and limit mesangial electron-dense deposits in Cfh+/- mice. The present data provide important insights into the potential benefits and limitations of FB-targeted inhibition strategies and suggest RNA interference-mediated FB silencing in the liver as a possible therapeutic approach for treating C3G patients with FH haploinsufficiency.

MxMPK6-2-mediated phosphorylation enhances the responseof apple rootstocks to Fe deficiency by activating PM H+ -ATPase MxHA2.

Iron (Fe) deficiency significantly affects the growth and development, fruit yield and quality of apples. Apple roots respond to Fe deficiency stress by promoting H+ secretion, which acidifies the soil. In this study, the plasma membrane (PM) H+ -ATPase MxHA2 promoted H+ secretion and root acidification of apple rootstocks under Fe deficiency stress. H+ -ATPase MxHA2 is upregulated in Fe-efficient apple rootstock of Malus xiaojinensis at the transcription level. Fe deficiency also induced kinase MxMPK6-2, a positive regulator in Fe absorption that can interact with MxHA2. However, the mechanism involving these two factors under Fe deficiency stress is unclear. MxMPK6-2 overexpression in apple roots positively regulated PM H+ -ATPase activity, thus enhancing root acidification under Fe deficiency stress. Moreover, co-expression of MxMPK6-2 and MxHA2 in apple rootstocks further enhanced PM H+ -ATPase activity under Fe deficiency. MxMPK6-2 phosphorylated MxHA2 at the Ser909 site of C terminus, Thr320 and Thr412 sites of the Central loop region. Phosphorylation at the Ser909 and Thr320 promoted PM H+ -ATPase activity, while phosphorylation at Thr412 inhibited PM H+ -ATPase activity. MxMPK6-2 also phosphorylated the Fe deficiency-induced transcription factor MxbHLH104 at the Ser169 site, which then could bind to the promoter of MxHA2, thus enhancing MxHA2 upregulation. In conclusion, the MAP kinase MxMPK6-2-mediated phosphorylation directly and indirectly regulates PM H+ -ATPase MxHA2 activity at the protein post-translation and transcription levels, thus synergistically enhancing root acidification under Fe deficiency stress.