bluuebunny/crossref_metadata_2025 huggingface dataset:
The crucial role of genome-wide genetic variation in conservation
Authors: Kardos Marty , Armstrong Ellie E. , Fitzpatrick Sarah W. , Hauser Samantha , Hedrick Philip W. , Miller Joshua M. , Tallmon David A. , Funk W. Chris
Published: November 2021

The unprecedented rate of extinction calls for efficient use of genetics to help conserve biodiversity. Several recent genomic and simulation-based studies have argued that the field of conservation biology has placed too much focus on conserving genome-wide genetic variation, and that the field should instead focus on managing the subset of functional genetic variation that is thought to affect fitness. Here, we critically evaluate the feasibility and likely benefits of this approach in conservation. We find that population genetics theory and empirical results show that conserving genome-wide genetic variation is generally the best approach to prevent inbreeding depression and loss of adaptive potential from driving populations toward extinction. Focusing conservation efforts on presumably functional genetic variation will only be feasible occasionally, often misleading, and counterproductive when prioritized over genome-wide genetic variation. Given the increasing rate of habitat loss and other environmental changes, failure to recognize the detrimental effects of lost genome-wide genetic variation on long-term population viability will only worsen the biodiversity crisis.
Vaccine-elicited CD4 T cells prevent the deletion of antiviral B cells in chronic infection
Authors: Narr Kerstin , Ertuna Yusuf I. , Fallet Benedict , Cornille Karen , Dimitrova Mirela , Marx Anna-Friederike , Martin Katrin , Abreu Mota Tiago , Künzli Marco , Schreiner David , Brunner Tobias M. , Kreutzfeldt Mario , Wagner Ingrid , Geier Florian , Bestmann Lukas , Löhning Max , Merkler Doron , King Carolyn G. , Pinschewer Daniel D.
Published: November 2021

Significance

Vaccines against persisting viruses such as HIV or hepatitis C virus remain a significant unmet global need. Long-lived memory B cells can be induced by vaccination to form an important pillar of antiviral immunity, yet persisting viruses subvert both primary B cell responses and memory B cell protection. Studying a mouse model of persistent viral infection, we found that CD4 T memory cells averted the deletion of antiviral B cells upon chronic virus challenge. Memory T help promoted germinal center reactions, preventing the B cells’ untimely, interferon-induced end differentiation. These observations indicate that B cell–based vaccination should be paired with potent memory CD4 T cell induction for memory B cells to prevail when confronted with a chronic viral intruder.
La ciudad de Maputo como palimpsesto literario
Authors: Fraticelli Barbara
Published: November 2021

La ciudad de Maputo, capital de Mozambique, se configura desde la segunda mitad del siglo XX como un auténtico palimpsesto literario, en el que las sucesivas escrituras superpuestas durante décadas crean un espacio en ocasiones sugerente y en otras abiertamente hostil ante la mirada del espectador.

Se distinguen, en este proceso de trasformación del espacio real en un espacio imaginario, tres momentos fundamentales. El primero es el periodo colonial, retratado en los versos de Noémia de Sousa, donde la ciudad construida de madera y cinc se reivindica como el germen de su esencia africana. El segundo nace tras la independencia, en un espacio convulso que busca una nueva identidad, como en la narrativa de João Paulo Borges Coelho. El tercero se perfila en los años más recientes, con una ciudad distópica en la que el crimen y la protesta colectiva constituyen la base de la última narrativa mozambiqueña.
Comparative analysis of public opinion and hostage attack victims’ attitudes: evidence from Beslan, September 2004
Authors: Dzutsev Valeriy , Dzutsev Khasan
Published: November 2021

How does an extreme situation, such as a violent attack, impact political opinions of the affected population? Using original data from the hostage crisis in the North Ossetian town of Beslan, this article explores the differences and similarities in attitudes towards the key social and political issues between the directly affected and the general populations of the town. The study was constructed as a quasi-natural experiment of a rare kind, since the attack generated directly affected and unaffected populations living in the same society. Our research shows that despite deep distrust toward both the national and regional government, respondents still indicated a relatively low inclination to engage in civic activity in opposition to the state authorities as a result of the attack. The results of the study throw light on the question of why the Beslan attack did not become a catalyst for change in North Ossetia: absence of political opposition disempowers the general population and prevents social change from happening even under highly stressful circumstances. The inconclusiveness of the official investigation into the Beslan attack may, however, leave these tragic events open to future politicisation.
Russian defence policy in the Caucasus
Authors: Blank Stephen
Published: November 2021

Since the Russo-Georgian war of 2008 Moscow has embarked upon a steady and relentless military buildup across the Caucasus. This buildup actually accelerated after 2010, allegedly on account of Russian expectations that the West would attack Iran and of Iranian retaliation against US-Israeli interests and allies in the Caucasus. Such unrealistic pretexts are more likely to be justifications for Moscow’s determination to assert through military means a continuing neo-imperial project in the Caucasus. Russian policies and military deployments make clear that Russia still cannot accept the independence and sovereignty of the South Caucasus states and aims at having a completely free hand to use force in the region as it sees fit. This can only detract from the region’s security. These developments are the focus of this article.
The missing “fifth column”: the effects of North Caucasus resettlement and deportations in the late 1800s on North Caucasians’ participation in the First World War
Authors: Schaefer Robert W.
Published: November 2021

At the outbreak of the First World War, Sultan Mehmet V of the Ottoman Empire issued two fatwas at Germany’s behest, calling for all Muslims to unite in global jihad against their Christian oppressors. Yet despite Russia’s designation as an “arch-enemy” after a series of wars spanning centuries, the Ottoman Sultan excused the Chechens, Dagestanis, and Circassians from conducting jihad against Russia. This was an extraordinary omission, especially given Ottoman concerns about a “Russian fifth column” (the Ottoman Armenians), and the general effectiveness of religion as a unifying and mobilizing mechanism in this era. Why did the Ottomans not attempt to foment the very same kind of unrest in Russia that they feared from Armenians in Anatolia? This article addresses the historical mystery of the “missing Ottoman fatwa” against the Russians, through exploration of the preceding 50 years of conflict in the Caucasus and the over-arching context of Russo-Ottoman military rivalry and war. The article argues that the devastation of the Russian deportations and resettlement of North Caucasus populations prior to the 1877-78 Russo-Ottoman War led the Sultan to believe that the Caucasus Muslims were too weak to be used as an effective fighting force. This resulted in their excusal from armed jihad, while the perceived effectiveness of such programs simultaneously influenced the Ottoman adoption of similar programs contributing ultimately to the Armenian Genocide.
Bidzina Ivanishvili, a man who plays according to Russian rules?
Authors: Gente Regis
Published: November 2021

When in October 2011 the Georgian billionaire Bidzina Ivanishvili announced that he was going into politics, discussions focused on whether he is a “Kremlin project” or not. Even if there were evidence of that, it would not be enough to explain Ivanishvili’s eruption into Georgian politics. This biographical sketch charts the rise of Ivanishvili and explores his previous business career in Russia, his professional relationships and key transactions, and his views on the future of Georgian-Russian relations.
Fieldnotes from a war zone: South Ossetia, September 2008
Authors: Sotieva Larisa
Published: November 2021

Editors’ note: Immediately following the August 2008 war in and around South Ossetia, two London-based peacebuilding organisations active in the South Caucasus, Conciliation Resources and International Alert, commissioned Larisa Sotieva to conduct research into the situation on the ground in the aftermath of the war. Sotieva, who grew up in South Ossetia and has a long track record in humanitarian and peacebuilding work in the South Caucasus, was in an unusual position to be able to conduct research within the area. She did not, however, have access to territory controlled by the Georgian side during a fortnight of fieldwork and was therefore only able to cover those areas under the control of the Russian military at that time. This paper, which is based on that research, is not an academic article, but an eye-witness account documenting the general situation and fate of the people whom the researcher was able to contact, as well as particular examples offering insights into the situation in South Ossetian society at the time of writing (September-October 2008). Research findings were circulated to a limited policy-oriented audience in March 2009 and have now been edited into this paper for publication. The editors thank International Alert and Conciliation Resources for permission to publish this material.
Power, knowledge, and pipelines: understanding the politics of Azerbaijan’s foreign policy
Authors: Ismayilov Murad
Published: November 2021

This article examines the ways in which Azerbaijan’s energy abundance and the energy diplomacy the latter made possible—combined with inherent weaknesses attending the state’s young post-colonial polity—conditioned the limits of the desirable by which the country’s post-independence elite was guided and, as such, limited the range of directions—cognitive and spatial—in which Azerbaijan’s foreign policy evolved during the first decade following independence. The study then examines how energy-induced growth in state capacity on the one hand, and the perceived failure of the state’s previous practices to help resolve outstanding security problems on the other, coupled with the effects of a number of endogenous and exogenous shocks (particularly, the colour revolutions in Georgia and Ukraine; Kosovo’s recognition by the West; the Russia-Georgia 2008 war; global economic crisis; and Turkey’s short-lived attempt at rapprochement with Armenia) and the perceptual shifts those shockwaves worked to engender, served to broaden the spatial and conceptual boundaries within which Azerbaijan’s foreign policy practices were conceived and effected, including by virtue of the energy resources the country has got in possession. The paper concludes by tracing the particular ways in which the broadening and deepening of the country’s foreign policy practices have occurred.
Astral microtubule cross-linking safeguards uniform nuclear distribution in the Drosophila syncytium
Authors: Deshpande Ojas , de-Carvalho Jorge , Vieira Diana V. , Telley Ivo A.
Published: November 2021

The early insect embryo develops as a multinucleated cell distributing the genome uniformly to the cell cortex. Mechanistic insight for nuclear positioning beyond cytoskeletal requirements is missing. Contemporary hypotheses propose actomyosin-driven cytoplasmic movement transporting nuclei or repulsion of neighbor nuclei driven by microtubule motors. Here, we show that microtubule cross-linking by Feo and Klp3A is essential for nuclear distribution and internuclear distance maintenance in Drosophila. Germline knockdown causes irregular, less-dense nuclear delivery to the cell cortex and smaller distribution in ex vivo embryo explants. A minimal internuclear distance is maintained in explants from control embryos but not from Feo-inhibited embryos, following micromanipulation-assisted repositioning. A dimerization-deficient Feo abolishes nuclear separation in embryo explants, while the full-length protein rescues the genetic knockdown. We conclude that Feo and Klp3A cross-linking of antiparallel microtubule overlap generates a length-regulated mechanical link between neighboring microtubule asters. Enabled by a novel experimental approach, our study illuminates an essential process of embryonic multicellularity.
Exercise-activated Ca2+ entry and enhanced risk of heat stroke
Authors: Girolami Barbara , Serano Matteo , Michelucci Antonio , Pietrangelo Laura , Protasi Feliciano
Published: November 2021

Exertional/environmental heat strokes (EHSs) are hyperthermic crises triggered by strenuous physical exercise and/or exposure to environmental heat, and are caused by an altered intracellular Ca2+ homeostasis in muscle. We recently demonstrated that a single bout of exercise on treadmill leads to formation of calcium entry units (CEUs), intracellular junctions that promote interaction between STIM1 and Orai1, the two proteins that mediate store-operated Ca2+ entry (SOCE). SOCE is a mechanism that is activated during muscle fatigue and that allows for recovery of extracellular Ca2+ during prolonged activity. The hypothesis underlying this work is that assembly of CEUs during prolonged exercise may predispose to EHSs when exercise is performed in challenging environmental conditions. To test this hypothesis, 4-mo-old mice were (1) divided into three experimental groups: control, trained-1m (1 mo of voluntary running in wheel cages), and exercised-1h (1 h of incremental treadmill run); and (2) subjected to an exertional stress (ES) protocol consisting of an incremental 45-min treadmill run at 34°C and 40% humidity. We then (a) measured the internal temperature of mice, which was higher in the two pre-exercised groups (trained-1m: 38.9°C ± 0.33; exercised-1h: 38.7°C ± 0.40) compared with control animals (37.9°C ± 0.17); (b) applied an ex vivo ES protocol to isolated EDL muscles (tetanic stimulation performed at 30°C) and verified that samples from trained-1m and exercised-1h mice generated a tension significantly greater than control samples; and (c) analyzed CEUs by electron microscopy (EM) and verified that EDL muscles of trained-1m and exercised-1h mice contained a greater number of membranes elements forming CEUs. The data collected indicates that the presence of CEUs correlates with a greater increase in body temperature and could, in principle, predispose to EHS when exercise is performed in challenging environmental conditions.
Piezo1 is a mechanosensor channel in CNS capillaries
Authors: Harraz Osama F. , Klug Nicholas R. , Senatore Amanda , Koide Masayo , Nelson Mark T.
Published: November 2021

Cerebral blood flow (CBF) is exquisitely controlled to meet the ever-changing demands of active neurons in the brain. Brain capillaries are equipped with sensors of neurovascular coupling agents released from neurons/astrocytes onto the outer wall of a capillary. While capillaries can translate external signals into electrical and Ca2+ changes, control mechanisms from the lumen are less clear. The continuous flux of red blood cells and plasma through narrow-diameter capillaries imposes mechanical forces on the luminal (inner) capillary wall. Whether—and, if so, how—the ever-changing CBF could be mechanically sensed in capillaries is not known. Here, we propose and provide evidence that the mechanosensitive Piezo1 channels operate as mechanosensors in CNS capillaries to ultimately regulate CBF. Patch clamp electrophysiology confirmed the expression and function of Piezo1 channels in brain cortical and retinal capillary endothelial cells. Mechanical or pharmacological activation of Piezo1 channels evoked currents that were sensitive to Piezo1 channel blockers. Using genetically encoded Ca2+ indicator (Cdh5-GCaMP8) mice, we observed that Piezo1 channel activation triggered Ca2+ signals in endothelial cells. An ex vivo pressurized retina preparation was employed to further explore the mechanosensitivity of capillary Piezo1-mediated Ca2+ signals. Genetic and pharmacologic manipulation of Piezo1 in endothelial cells had significant impacts on CBF, reemphasizing the crucial role of mechanosensation in blood flow control. In conclusion, this study shows that Piezo1 channels act as mechanosensors in capillaries, and that these channels initiate crucial Ca2+ signals. We further show that Piezo1 modulates CBF, an observation of profound significance for the control of brain blood flow in health and in disorders where hemodynamic forces are disrupted, such as hypertension.
Biophysical characteristics of TRIC-A and TRIC-B channels and their regulation of RYR2
Authors: Hu Jianshu , Venturi Elisa , Sigalas Charalampos , Murayama Takashi , Nishi Miyuki , Takeshima Hiroshi , Sitsapesan Rebecca
Published: November 2021

Trimeric intracellular cation channels (TRIC-A and TRIC-B), found in the sarco/endoplasmic reticulum (SR/ER) and nuclear membranes, are thought to provide countercurrents to balance Ca2+-movements across the SR, but there is also evidence that they physically interact with ryanodine receptors (RYR). We therefore investigated if TRIC channels could modulate the single-channel function of RYR2 after incorporation of vesicles isolated from HEK293 cells expressing TRIC-A or TRIC-B with RYR2 into artificial membranes under voltage clamp. We also examined the gating and conductance properties of TRIC channels. Co-expression of RYR2 with either TRIC-A or TRIC-B significantly altered the gating behavior of RYR2; however, co-expression with TRIC-A was particularly effective at potentiating the activating effects of cytosolic Ca2+. Fusing membrane vesicles containing TRIC-A or TRIC-B together with RYR2 into bilayers produced large currents of rapidly gating current fluctuations of multiple amplitudes. In 740 cytosolic/210 luminal mM KCl gradient, current-voltage relationships of macroscopic currents revealed average reversal potentials (Erev) of −13.67 ± 9.02 (n = 7), −2.11 ± 3.84 (n = 11), and 13.19 ± 3.23 (n = 13, **, P = 0.0025) from vesicles from RYR2 only, RyR2 + TRIC-A, or RyR2 + TRIC-B cells, respectively. Thus, with the incorporation of TRIC channels, the Erevs depart further from the calculated Erev for ideally selective cation channels than occurs when vesicles from RYR2-only cells are incorporated, suggesting that TRIC channels are permeable to both K+ and Cl−. In conclusion, our results indicate that both TRIC-A and TRIC-B regulate the gating of RYR2, but that TRIC-A has greater capacity to stimulate the RYR2 opening. The results also suggest that TRIC channels may be relatively nonselective ion channels being permeable to both cations and anions. This property would enable TRIC channels to be versatile providers of counter-ion current throughout the SR of many cell types.
Acute exposure to the chemotherapy cisplatin has a biphasic effect in cardiac contractility
Authors: Savio Florencia , Cardozo Romina , Benitez Milagros , Costa Carlos , Ferreira Gonzalo
Published: November 2021

Cancer and cardiovascular diseases are the main causes of death in Uruguay and developed countries. In clinical practice, there is often the need to administrate chemotherapy with cisplatin (CTP) to patients with cardiovascular comorbidities. The aim of this work is to characterize the possible detrimental effects in cardiac function by the acute exposition to CPT using isolated heart and cardiomyocytes from guinea pigs (Cavia porcellus). All the procedures regarding animal experimentation were performed following approved protocols by the university ethics committee. Isolated hearts were placed in a Langendorff system and perfused with Tyrode 1.8 mM Ca2+ as control medium, or with extracellularly added CPT (0–100 µM). Tension was recorded with a gauge force transducer attached to the papillary muscle and electrical responses were measured with Ag-AgCl electrodes placed in surface extremes near the papillary muscle. Cardiomyocytes were isolated by enzymatic methods. Data were obtained by patch clamp and confocal microscopy with Rhodamine and Fluo dyes sensitive to Ca2+ binding. Non-parametric t tests were used for data comparison. The best fit of Hill’s equation to dose–response curves was done using nonlinear regression methods. In isolated hearts, CPT showed a biphasic effect over the development of tension, increasing up to 5–10 µM to decrease at higher concentrations. In isolated cardiomyocytes, Ca2+ currents were stimulated and inhibited by CPT in a similar dose. Confocal microscopy showed an increment and a reduction of relative fluorescence of the calcium-sensitive dyes with CPT as well. Our results suggest that CPT may affect cardiac contraction and automatism upon acute exposure of the heart, presumably by blocking L-type (Cav1.2) calcium channels and interference with molecules involved in maintaining the homeostasis of intracellular Ca2+.
Increased basal metabolic rate in mice susceptible to malignant hyperthermia and heat stroke
Authors: Serano Matteo , Pietrangelo Laura , Paolini Cecilia , Guarnier Flavia A. , Protasi Feliciano
Published: November 2021

Ryanodine receptor type-1 (RYR1) and Calsequestrin-1 (CASQ1) proteins, located in the sarcoplasmic reticulum (SR), are two of the main players in skeletal excitation–contraction (EC) coupling. Mutations in the human RYR1 gene (encoding for the SR Ca2+ release channel) and ablation in mice of CASQ1 (a SR Ca2+ binding protein) cause hypersensitivity to halogenated anesthetics (malignant hyperthermia [MH] susceptibility) and to heat (heat stroke; HS). As both MH and HS are characterized by excessive cytosolic Ca2+ levels and hypermetabolic responses, we studied the metabolism of 4-mo-old mice from two different lines that are MH/HS susceptible: knock-in mice carrying a human MH mutation (RYR1YS) and CASQ1-knockout (ko) mice. RYR1YS and, to a lesser degree, CASQ1-null mice show an increased volume of oxygen consumption (VO2) and a lower respiratory quotient (RQ) compared with WT mice (indicative of a metabolism that relies more on lipids). This finding is accompanied by a reduction in total body fat mass in both Y522S and CASQ1-null mice (again, compared with WT). In addition, we found that RYR1YS and CASQ1-null mice have an increased food consumption (+26.04% and +25.58% grams/day, respectively) and higher basal core temperature (+0.57°C and +0.54°C, respectively) compared with WT mice. Finally, Western blots and electron microscopy indicated that, in hyperthermic mice, (1) SERCA (used to remove myoplasmic Ca2+) and UCP3 (responsible for a thermogenic process that dissipates mitochondrial H+ gradient) are overexpressed, and (2) mitochondrial volume and percentage of damaged mitochondria are both increased. In conclusion, the MH/HS phenotype in RYR1YS and CASQ1-null mice is associated with an intrinsically increased basal metabolism.
Intrinsic contractile dysfunction in a surgical model of muscle hypertrophy
Authors: Tokuda Nao , Watanabe Daiki , Ashida Yuki , Kimura Iori , Naito Azuma , Yamauchi Nao , Yamada Takashi
Published: November 2021

Synergistic ablation (SA) is widely used to induce muscle hypertrophy in rodent studies. However, it has been demonstrated that SA-induced compensatory hypertrophy induces increases in maximum isometric force that are smaller in magnitude than the increase in muscle cross-sectional area, suggesting a reduction in the specific force production due to intrinsic contractile dysfunction in the hypertrophied fibers. Here, by using the mechanical skinned fibers, we investigated the mechanisms behind the reduction in specific force in the compensatory hypertrophied muscles. Rats had unilateral surgical ablation of the gastrocnemius and soleus muscles to induce the compensatory hypertrophy in the plantaris muscles. Two wk after surgery, the mean fiber diameter was increased by 19% in the SA group compared with the contralateral control (CNT) group. In contrast, compared with the CNT group, both the depolarization-induced force (−51%) and the Ca2+-activated maximum specific force (−32%) were markedly reduced in skinned fibers from the SA group. These deleterious functional alterations were accompanied by decreases in the amount of DHPRα1, RYR, junctophilin 1, and SH3 and cysteine-rich domain 3 (STAC3) in SA muscles. Thus, these data clearly show that SA induces not only an increase in skeletal muscle fiber hypertrophy but also leads to a reduction in the intrinsic contractile dysfunction due to the excitation–contraction uncoupling and impaired force-generating capacity.
Effects of dihydropyridine receptor signal on sarcoplasmic reticulum Ca2+ leakage after muscle contractions in rats
Authors: Watanabe Daiki , Wada Masanobu
Published: November 2021

The purpose of this study is to investigate the mechanism underlying sarcoplasmic reticulum (SR) Ca2+ leakage at recovery phase after in vivo contractions. Rat gastrocnemius muscles were electrically stimulated in vivo, and then mechanically skinned fibers were prepared from the muscles excised 30 min after repeated high-intensity contractions. SR Ca2+ leakage was increased in the skinned fibers from stimulated muscles. Thereafter, SR Ca2+ leakage in skinned fibers was measured (1) under a continuously depolarized condition and (2) in the presence of nifedipine in the sealed transverse tubular system. In either of the two conditions, SR Ca2+ leakage in the rested fibers reached a level similar to that in the stimulated fibers. Furthermore, 1 mM tetracaine (Tet) treatment, but not 3 mM Mg2+ (3 Mg) treatment, lessened SR Ca2+ leakage in stimulated fibers. Depolarization-induced force in skinned fibers was more greatly decreased by Tet treatment than by 3 Mg treatment (92% reduction in Tet versus 31% reduction in 3 Mg), whereas caffeine-induced force in skinned fibers was similarly decreased by either treatment (73% reduction in Tet versus 75% reduction in 3 Mg). This difference indicates that Tet exerts a greater inhibitory effect on the dihydropyridine receptor (DHPR) signal to ryanodine receptor (RYR) than 3 Mg, although their inhibitory effects on RYR are almost similar. These results suggest that the increased Ca2+ leakage after muscle contractions is mainly caused by the orthograde signal of DHPRs to RYRs.
Isometric training improves fatigue resistance in dystrophin-deficient muscle
Authors: Yamauchi Nao , Kimura Iori , Ashida Yuki , Naito Azuma , Tokuda Nao , Yamada Takashi
Published: November 2021

Eccentric contractions, in which the muscle is stretched during contraction, cause substantially greater damage than isometric (ISO) contractions, in which the length of the muscle does not change during contraction. Here, we tested the hypothesis that ISO training improves fatigue resistance in skeletal muscle from dystrophin-deficient mdx52 mice (15–22 wk old). ISO training (100 Hz stimulation frequency, 0.25-s contractions every 0.5 s, 6 sets of 60 contractions) was performed on the left plantar flexor muscles in vivo with supramaximal electrical stimulation every other day for 4 wk. Compared with the normal control muscle, resistance to fatigue was reduced in the nontrained muscle from mdx52 mice, which was accompanied by a reduction in citrate synthase activity and the LC3BII/I ratio and an increase in the phosphorylation levels of Akt Ser473 and the expression levels of p62. ISO training restored these alterations and markedly increased in vivo fatigue resistance and PGC-1α expression in mdx52 muscles. Moreover, an increased number of Evans Blue dye-positive fibers was significantly reduced by ISO training in mdx52 muscles. In contrast, ISO training did not restore a reduction in the amount of SH3 and cysteine-rich domain 3 in mdx muscles. Thus, our data suggest that mitochondrial function is impaired in dystrophin-deficient muscles, which is likely to be induced by the defective autophagy due to persistent activation of Akt. ISO training inhibits the aberrant activation of Akt presumably by up-regulating the PGC-1α expression, which results in improved mitochondrial function and thus fatigue resistance in dystrophin-deficient muscles.
Insect elementary calcium release events measured in honeybee muscle cells
Authors: Collet Claude , Charreton Mercedes , Szabo Laszlo , Takacs Marianna , Csernoch Laszlo , Szentesi Peter
Published: November 2021

Subcellular calcium variations are involved in physiological and pathological mechanisms. Whereas elementary calcium release events (CREs) have been known for almost three decades in intact muscle cells isolated from vertebrates, they remained not characterized in invertebrates until recently. Dynamic confocal imaging was used on intact skeletal muscle cells isolated enzymatically from the adult honeybee legs to characterize spatio-temporal features of subcellular CREs. The frequency of these insect CREs, measured in x–y time lapse series, was higher than frequencies usually described in vertebrates. Spatial spread at half maximum was larger than in vertebrates and had a slightly ellipsoidal shape, two characteristics that may be related to ultrastructural features specific to invertebrate cells. In line-scan experiments, the histogram of CREs’ duration followed a bimodal distribution, supporting the existence of both sparks and embers. Unlike in vertebrates, embers and sparks had similar amplitudes, a difference that could be related to genomic differences and/or excitation–contraction coupling specificities in honeybee skeletal muscle fibers. Arthropods muscle cells show strong genomic, ultrastructural and physiological differences with vertebrates and a comparative analysis may help to better understanding the roles and regulations of CREs. From a toxicological point of view, such a comparison will lead to better anticipating the myotoxicity of new insecticides targeting ryanodine receptors. Recent studies described the effects of these insecticides on macroscopic calcium homeostasis in bee neurons and muscle cells. Here, cyantraniliprole, the most recently approved anthranilic diamide in Europe, triggers calcium transients in bee muscle cell as well. Cyantraniliprole effects on Ca2+ sparks are currently under study.
CaV1.1 defects in hypokalemic periodic paralysis and harnessing multiple approaches for therapeutic intervention
Authors: Wu Fenfen , Quiñonez Marbella , Difranco Marino , Cannon Stephen
Published: November 2021

The recurrent attacks of weakness in hypokalemic periodic paralysis (HypoPP) are caused by failure to maintain the resting potential, with paradoxical depolarization in low K+. Remarkably, 24 out of 25 HypoPP mutations are R/X substitutions in S4 segments of voltage-sensing domains of CaV1.1 (70% of cases) or NaV1.4 (10% of cases). Expression studies in oocytes and murine muscle show anomalous gating pore leakage currents (ω-pore) for six of eight CaV1.1-HypoPP mutations, with one exception being the charge-conserving R897K. The proposed consensus pathomechanism, whereby a gating pore leak predisposes to paradoxical depolarization in low K+, is now verified by continuous recording of Vm. Selective measurement of voltage-dependent Ca2+ release, in “healthy appearing” HypoPP fibers, shows only a modest decrease in the Ca2+-dependent peak fluorescence (Oregon green 488/EGTA), and supports the notion that stabilizing Vrest will be sufficient to prevent low-K+–induced loss of force. In our knockin mouse models of HypoPP (CaV1.1-R528H and NaV1.4-R669H), pretreatment with K+-channel openers protects against the loss of force with a 2 mM K+ challenge. Alternatively, gene editing offers the possibility of sustained protection from attacks of weakness, and may prevent the late-onset permanent myopathy. In a proof-of-principle study of cultured myoblasts and in vivo electroporation, we show selective editing of the mutant HypoPP allele, without compromise of the WT allele, using CRISPR/Cas-mediated indel formation to destroy the HypoPP allele or a CRISPR/Cas base editor to correct the missense mutation.
Voltage sensor movements of CaV1.1 during an action potential in skeletal muscle fibers
Authors: Banks Quinton , Bibollet Hugo , Contreras Minerva , Bennett Daniel F. , Bannister Roger A. , Schneider Martin F. , Hernández-Ochoa Erick O.
Published: November 2021

In excitation–contraction coupling (ECC), when the skeletal muscle action potential (AP) propagates into the transverse tubules, it modifies the conformational state of the voltage-gated calcium channels (CaV1.1). CaV1.1 serves as the voltage sensor for activation of calcium release from the sarcoplasmic reticulum (SR); however, many questions about this function persist. CaV1.1 α1 subunits contain four distinct homologous domains (I–IV). Each repeat includes six transmembranal helical segments; the voltage-sensing domain (VSD) is formed by S1–S4 segments, and the pore domain is formed by helices S5–S6. Because, in other voltage-gated channels, individual VSDs appear to be differentially involved in specific aspects of channel gating, here we thus hypothesized that not all the VSDs in CaV1.1 contribute equally to calcium-release activation. Yet, the voltage-sensor movements during an AP (the physiological stimulus for the muscle fiber) have not been previously measured in muscle. Reorientation of VSDs I–IV in CaV1.1 during an AP should generate a small but measurable electrical current. Still, neither the voltage-sensor charge movement during the AP nor the contribution of the individual VSDs to voltage-gated calcium release have been previously monitored. Here, we electrically monitor VSD movements using an AP voltage-clamp technique applied to muscle fibers. We introduce AP-fluorometry, a variant of the functional site-directed fluorescence, to track the movement of each VSD via a cysteine substitution on the extracellular region of S4 of each VSD and its labeling with a cysteine-reacting fluorescent probe, which served as an optical reporter of local rearrangements. Independent optical recordings of AP and calcium transients were performed to establish the temporal correlation between AP, AP-elicited charge movement, VSDs conformational changes, and calcium release flux. Our results support the hypothesis that not all VSDs in CaV1.1 contribute to ECC.
Reduced plasticity and microtubule densification in muscular dystrophy-related cardiomyopathy
Authors: Katanosaka Yuki
Published: November 2021

The dystrophin–glycoprotein complex (DGC) links the intracellular cytoskeleton to the extracellular basement membrane, thereby providing structural support for the sarcolemma. Many patients with muscular dystrophies, particularly those with defects in cardiomyopathies with chamber dilation and myocardial dysfunction. Heart failure is the major cause of death for muscular dystrophy patients; however, the molecular pathomechanism remains unknown. Here, I show the detailed molecular pathogenesis of muscular dystrophy–associated cardiomyopathy in mice lacking the fukutin gene (Fktn), the causative gene for Fukuyama muscular dystrophy. Although cardiac Fktn elimination markedly reduced the glycosylation of α-dystroglycan and the expression of DGC proteins in sarcolemma at all developmental stages, cardiac dysfunction was observed only in later adulthood, suggesting that the physiological contribution of DGC proteins in the heart increases after 6 mo of age. In addition, Fktn-deficient mice maintain normal cardiac function at young age, suggesting that membrane fragility is not the sole etiology of cardiac dysfunction. Young Fktn-deficient mice did not show a compensative hypertrophic response to hemodynamic stress and quickly developed heart failure with chamber dilation and contractile dysfunction. In these mice, Ca2+-calcineurin signaling was already elevated under physiological conditions, and MEF2-HDAC axes essential for the hypertrophic response were unable to function under stress conditions. Acute Fktn elimination caused severe cardiac dysfunction and accelerated mortality with myocyte contractile dysfunction and disordered Golgi–microtubule networks, which were ameliorated with colchicine treatment. Microarray analysis in control and Fktn-deficient hearts suggest that elimination of Fktn impacts the expression profile of Golgi-related genes, and that the pathological mechanism of cardiac dysfunction induced by Fktn elimination partly overlaps with that of neurodegenerative disease. These data reveal fukutin is crucial for maintaining myocyte physiology to prevent heart failure, and, thus, the results may lead to strategies for intervention.
Therapeutic effects of novel type 1 ryanodine receptor inhibitor on malignant hyperthermia
Authors: Yamazawa Toshiko
Published: November 2021

Ca2+-induced Ca2+ release (CICR) is mediated by ryanodine receptors, a Ca2+ release channel in the sarcoplasmic/endoplasmic reticulum (SR/ER), and plays an important role in various tissues. Type 1 ryanodine receptor (RYR1) plays a key role during excitation–contraction coupling of skeletal muscle. Mutations in RYR1 overactivate the channel to cause malignant hyperthermia (MH). MH is a serious complication characterized by skeletal muscle rigidity and elevated body temperature in response to commonly used inhalational anesthetics. Thus far, >300 mutations in the RYR1 gene have been reported in patients with MH. Some heat stroke triggered by exercise or environmental heat stress is also related to MH mutations in the RYR1 gene. The only drug approved for ameliorating the symptoms of MH is dantrolene, which has been first developed in the 1960s as a muscle relaxant. However, dantrolene has several disadvantages for clinical use: poor water solubility, which makes rapid preparation difficult in emergency situations, and long plasma half-life, which causes long-lasting side effects such as muscle weakness. Here, we show that a novel RYR1-selective inhibitor, 6,7-(methylenedioxy)-1-octyl-4-quinolone-3-carboxylic acid (compound 1 [Cpd1]), effectively rescues MH and heat stroke in new mouse model (RYR1-p.R2509C) relevant to MH. Cpd1 has great advantages of higher water solubility and shorter plasma half-life compared with dantrolene. Our data suggest that Cpd1 has the potential to be a promising new candidate for effective treatment of patients carrying RYR1 mutations. Finally, we have recently identified that heat directly activates RYR1, which induces Ca2+ release from intracellular stores. Our results provide direct evidence that heat induces Ca2+ release (HICR) from the SR through the mutants rather than wild type RYR1, causing an immediate rise in the cytosolic Ca2+ concentration.
Direct cardiotoxicity of lead
Authors: Chavarría Luisina , Santander Axel , Cardozo Romina , Savio Florencia , Mujica Nicolas , Dominguez Lucia , Nicolson Garth , Ferreira Gonzalo
Published: November 2021

Lead is a heavy metal pollutant that constitutes frequent exposomes. It is nonbiodegradable and has a nonsafe limit of exposure. It has multisystemic effects, and most of the cardiac effects have been discovered to be indirect. There are strong similarities between Ca2+ and Pb2+ in their chemistry. Because cardiac function is dramatically dependent in extracellular Ca2+, as well as in precise control of intracellular Ca2+, we tested if Pb2+ could antagonize Ca2+-dependent effects in a short amount of time. Acute exposure of isolated hearts showed a negative inotropic effect. In guinea pig isolated cardiomyocytes loaded with a Pb2+-specific dye (Leadmium green), our results showed that there was an associated increment in fluorescence related to extracellular stimulation blocked by 1–5 µM DHP. Calcium currents were partially blocked by extracellular Pb2+, though currents seemed to last longer after a fast inactivation. Charge movement from gating currents was slightly hastened over time, giving an appearance of a slight reduction in the Cav1.2 gating currents. Action potentials were prolonged in Pb2+ compared with Ca2+. In isolated cardiomyocytes loaded with Ca2+-sensitive dyes, Ca2+ variations promoted by extracellular stimuli were affected in space/time. As Pb2+ could interfere with Ca2+-sensitive dyes, we measured contraction of isolated cardiomyocytes under extracellular stimuli in Pb2+. In both Ca2+ dye fluorescence and contractions, Pb2+ disorganizes the pattern of contraction and intracellular Ca2+ homeostasis. Our results suggest that (1) Pb2+ enters to cardiomyocytes through Cav1.2 channels, and (2) once it enters the cell, Pb2+ may substitute Ca2+ in Ca2+-binding proteins. In addition to these direct mechanisms related to Pb2+ competition with Ca2+-binding sites, we cannot discard a direct contribution of Pb2+ redox properties.
Emergent role of SARAF and store-operated Ca2+ entry in angiogenesis
Authors: Galeano-Otero Isabel María , Del Toro Raquel , Smani Tarik
Published: November 2021

Angiogenesis is a multistep process that controls endothelial cell (EC) functioning to form new blood vessels from preexisting vascular beds. This process is tightly regulated by pro-angiogenic factors, such as vascular endothelial growth factor (VEGF), which promotes signaling pathways involving the increase in the intracellular Ca2+ concentration ([Ca2+]i). Recent evidence suggests that store-operated Ca2+ entry (SOCE) might play a role in angiogenesis. However, little is known regarding the role of SARAF, SOCE-associated regulatory factor in this process. The aim of this study is to examine the role of SARAF in angiogenesis. In vitro angiogenesis was studied using human umbilical endothelial cells (HUVECs) for tube formation assay and vessel sprouting using rat aortic ring by Matrigel assay supplemented with endothelial cell basal medium enriched with different growth factors (VEGF, FGF, b-EGF, and IGF). HUVECs migration was evaluated by wound healing assay, and HUVECs proliferation using Ki67+ marker. Ex vivo angiogenesis was examined by whole mount mice retina on P6 in neonatal mice injected with increasing concentrations of a SOCE inhibitor, GSK-7975A, on P3, P4, and P5. We observed that SOCE inhibition with GSK-7975A blocks aorta sprouting, as well as HUVEC tube formation and migration. The intraperitoneal injection of GSK-7975A also delays the development of retinal vasculature assessed at postnatal day 6 in mice since it reduces vessel length and the number of junctions while it increases lacunarity. Moreover, we found that knockdown of SARAF using siRNA impairs VEGF-mediated [Ca2+]i increase and HUVEC tube formation, proliferation, and migration. Our data show for the first that SOCE inhibition prevents angiogenesis using different approaches and we provide evidence indicating that SARAF plays a critical role in angiogenesis.
Blue and black phosphorene on metal substrates: a density functional theory study
Authors: Adak Abhishek K , Sharma Devina , Narasimhan Shobhana
Published: November 2021

We have performed density functional theory calculations to study blue phosphorene and black phosphorene on metal substrates. The substrates considered are the (111) and (110) surfaces of Al, Cu, Ag, Ir, Pd, Pt and Au and the (0001) and (10

1

¯

0) surfaces of Zr and Sc. The formation energy E
F is negative (energetically favorable) for all 36 combinations of overlayer and substrate. By comparing values of ΔΩ, the change in free energy per unit area, as well as the overlayer-substrate binding energy E
b, we identify that Ag(111), Al(110), Cu(111), Cu(110) and possibly Au(110) may be especially suitable substrates for the synthesis and subsequent exfoliation of blue phosphorene, and the Ag(110) and Al(111) substrates for the synthesis of black phosphorene. However, these conclusions are drawn assuming the source of P atoms is bulk phosphorus, and can alter upon changing synthesis conditions (chemical potential of phosphorus). Thus, when the source of phosphorus atoms is P4, blue phosphorene is favored only over Pt(111). We find that for all combinations of overlayer and substrate, the charge transfer per bond can be captured by the universal descriptor

D
=
Δ
χ
/
Δ
R

, where Δχ and

Δ
R

are, respectively, the differences in electronegativity and atomic size between phosphorus and the substrate metal.
An approach to energy efficient lighting design for economic residential flats
Authors: Das Subhasish , Mondal Anubrata , Ghosh Kamalika
Published: November 2021

The lighting design in a residential building now-a-days is not only limited to general lighting but also it is focused to provide quality lighting with the help of wide range of available luminaire with different orientations as well as colours with efficient use of energy, that opens up accurate characteristics of specific areas in any room of the building. The affordable housings in many states are some of the examples of residential building where most of the flats in a typical floor are using conventional lighting systems which are not energy efficient and light level is low compared to standards. This paper is mainly focused to provide a budget friendly as well as energy efficient lighting design with the help of new and energy efficient lamps using DIALux Software, which can be proposed to renovate the existing conventional lighting systems. In this paper effort has been made to reduce the power consumption in all rooms and lux levels has been achieved as per standard values along with good amount of energy saving with the use of newer technologies.
Facade control systems for optimal daylighting: A case of Kerala
Authors: Dev Govind , Saifudeen Aysha , Sathish Aparna
Published: November 2021

Indoor environmental quality is one of the most important aspects to be considered while designing buildings. Design decisions taken to ensure indoor environmental quality depends upon the specific location, climate, form, orientation and materials used for the construction of the building. In addition to ensuring comfort and optimal occupant conditions, these design decisions also impact the overall energy consumption of the building. The design of the building envelope is of more importance in regions that receive a huge amount of solar radiation. Kerala, falling in the Tropical belt, have buildings designed (or supposed to be designed) with sufficient roofing/shading overhangs to avoid penetration of solar radiation, and direct glare towards the inside. Well-designed shading devices provide the best shading during overheated periods thus lesser heat gain or cooling load. The form of shading devices influences day-lighting inside the building. This paper intends to explore different types of shading devices and façade control systems, and their impact on daylighting inside a selected commercial building in Kerala. It concludes by identification of the most efficient design of the device in each type identified, through BIM modelling and lighting simulation, specific to the original building location, to ensure optimal daylighting while eliminating the undesirable effects of solar radiation.
Review on Magnetohydrodynamic flow of nanofluids past a Vertical plate under the influence of Thermal Radiation
Authors: ShanthaSheela J , David Maxim Gururaj A , Ismail Mohammed , Dhanasekar S
Published: November 2021

Nanofluids are the fluids containing nano materials, with interesting properties, and the distinctive features have shown unprecedented potential for many Industrial applications. Nano fluids have been receiving great attention in recent years for heat transfer applications in industrial processes. In literature, the highly nonlinear governing equations involved in the study of MHD nanofluids flow with thermal radiation past a vertical plate under varying physical nature are solved using numerical and analytical schemes. It is noted that due to the complexity of the governing equations, numerical schemes are more preferable than analytical schemes. The authors have taken effort in registering various forms of governing equations involved in the above studies, its impact on velocity and temperature field. This paper also tries to identify the research gaps and pave way for future research.