Control Of Contraction Research Articles

SOCIAL EXCHANGE APPROACHES TO PROMOTING INTER-ORGANIZATIONAL CITIZENSHIP COLLABORATIVE BEHAVIORS IN THE CONSTRUCTION PROJECT TEAM

Inter-organizational citizenship collaborative behavior (OCCB) is critical for project team members to share information and integrate resources. However, prior studies found that high OCCBs are absent in project teams. This study aims to explore social exchange approaches to promote project team members’ OCCBs in the construction project team from the social exchange perspective. A questionnaire survey was undertaken online. A two-stage SEM was conducted to verify the measurement and structural models. Confirmatory factor analysis was conducted to verify the measurement model’s reliability and validity, the structural model was assessed by examining the model’s fitness, and path coefficients were used to test the hypotheses. The findings showed that relational social exchange is more effective than contractual social exchange for OCCBs. Meanwhile, contractual control and benevolence trust are verified as mediators between competence trust and OCCB. Three pathways are explored to enhance project team members’ OCCBs: relational social exchange dominated strategy (i.e., dominant competence trust strategy and competence trust-benevolence trust strategy) and relational-contractual hybrid strategy (i.e., competence trust-contractual control strategy). This study expands the social exchange theory in the inter-organizational citizenship collaborative behavior in construction project teams and supports project management by verifying the enabling mechanisms.

Skeletal muscle alpha actin (ACTA1) acetylation negatively regulates muscle function in response to obesity

Post‐translational modifications (PTMs) of proteins are an increasingly important area of study that contributes to our understanding for protein function in the control of health and disease. Acetylation, for example, has long been associated with histone modifications to control gene expression, yet emerging omics data demonstrates that acetylation occurs across the proteome. Our most recent work further shows global shifts in non‐histone protein acetylation within the left ventricle (LV) in response to diet‐induced obesity. Despite these advances in omics technologies, our understanding for how non‐histone protein acetylation regulates cardiac biology remains a ‘black box’. In this study, we examined the functional importance for skeletal muscle alpha actin (ACTA1) acetylation in the control of muscle function. For this, we used actin‐motility assays to examine the biophysical changes between acetylated ACTA1 and the other myofibrillar proteins involved in cardiac contraction and relaxation (e.g. myosin, tropomyosin). Here, we show that ACTA1 acetylation increased actin‐myosin binding, decreased actin sliding velocity and increased Ca2+ sensitivity. These data suggest that ACTA1 acetylation significantly alters muscle function. Of note, we previously published that lysine (K) residue 50 (K50) of ACTA1 was acetylated, similar to other proteomics reports. Interestingly, the positively charged K50 on ACTA1 sits juxtaposed to the negatively charged aspartic acid (D) residue 391 of the cardiac myosin binding protein (cMy‐BP). cMy‐BP is essential for actin‐myosin interactions, and this suggests an important role for ACTA1 K50 acetylation in the control of muscle contraction. Thus, we knocked out endogenous actin (Act88F) from the indirect flight muscles (IFMs) of D. melanogaster and inserted an Act88F K50Q mutant, which mimics acetylation specifically at this site. Previous reports have shown that IFMs behave similarly to cardiac muscle. Phenotypically, the K50Q flies behave similar to their wild‐type counterparts. However, current studies are underway to examine changes in flight as well as purify the K50Q actin for actin‐motility assays to examine biophysical changes in myofibrillar proteins. Combined, our data suggests that ACTA1 acetylation negatively impacts muscle function in response to obesity, current work will determine the implications for K50 actin acetylation in this phenotype.

A light-induced small G-protein gem limits the circadian clock phase-shift magnitude by inhibiting voltage-dependent calcium channels.

Calcium signaling is pivotal to the circadian clockwork in the suprachiasmatic nucleus (SCN), particularly in rhythm entrainment to environmental light-dark cycles. Here, we show that a small G-protein Gem, an endogenous inhibitor of high-voltage-activated voltage-dependent calcium channels (VDCCs), is rapidly induced by light in SCN neurons via the calcium (Ca2+)-mediated CREB/CRE transcriptional pathway. Gem attenuates light-induced calcium signaling through its interaction with VDCCs. The phase-shift magnitude of locomotor activity rhythms by light, at night, increases in Gem-deficient (Gem-/-) mice. Similarly, in SCN slices from Gem-/- mice, depolarizing stimuli induce larger phase shifts of clock gene transcription rhythms that are normalized by the application of an L-type VDCC blocker, nifedipine. Voltage-clamp recordings from SCN neurons reveal that Ca2+ currents through L-type channels increase in Gem-/- mice. Our findings suggest that transcriptionally activated Gem feeds back to suppress excessive light-evoked L-type VDCC activation, adjusting the light-induced phase-shift magnitude to an appropriate level in mammals.

N-acetylcholine receptors regulate cytokines expression and neutrophils recruitment via MAPK/ERK signaling in zebrafish

N-acetylcholine receptors (AChRs) are mainly distributed in the postsynaptic membrane and have been widely studied for their control of muscle contraction by regulating neural action potentials. However, the influences of AChRs on immune responses and potential mechanisms remain unclear. Here, we used the advantages of live imaging of zebrafish to explore the regulation process of AChRs on inflammatory responses. Pharmacologically activating of the receptor, we found that the expression of pro-inflammatory cytokines il-1β, il-6, tnf-α and il-8 was significantly up-regulated and neutrophil migration to injury sites was also significantly increased. However, these phenomena were reversed under antagonism of the receptor activity. Results showed that interfering with nAChRs functions did not significantly affect zebrafish motion behavior. Results also showed that activation and antagonism of nAChRs function could regulate the phosphorylation of ERK protein respectively. We further demonstrated that ERK participated in the regulation of AChRs in cytokines expression and neutrophils migration in zebrafish. This study preliminarily revealed the roles of AChRs in inflammatory processes and their potential mechanism, providing additional evidence of peripheral immune regulation by cholinergic receptors.

Proximal and distal spinal neurons innervating multiple synergist and antagonist motor pools.

Motoneurons (MNs) control muscle contractions, and their recruitment by premotor circuits is tuned to produce accurate motor behaviours. To understand how these circuits coordinate movement across and between joints, it is necessary to understand whether spinal neurons pre-synaptic to motor pools have divergent projections to more than one MN population. Here, we used modified rabies virus tracing in mice to investigate premotor interneurons projecting to synergist flexor or extensor MNs, as well as those projecting to antagonist pairs of muscles controlling the ankle joint. We show that similar proportions of premotor neurons diverge to synergist and antagonist motor pools. Divergent premotor neurons were seen throughout the spinal cord, with decreasing numbers but increasing proportion with distance from the hindlimb enlargement. In the cervical cord, divergent long descending propriospinal neurons were found in contralateral lamina VIII, had large somata, were neither glycinergic, nor cholinergic, and projected to both lumbar and cervical MNs. We conclude that distributed spinal premotor neurons coordinate activity across multiple motor pools and that there are spinal neurons mediating co-contraction of antagonist muscles.

Too much is not always good: the inverted U-shaped link between green customer integration and opportunistic behavior

PurposeThe purpose of this study is to explore the inverted U-shaped relationship between green customer integration (GCI) and opportunistic behavior, as well as the moderating effects of contractual control and relational norms.Design/methodology/approachThe authors conducted hierarchical regression analysis using two-waved data from 206 Chinese manufacturing firms to test hypotheses.FindingsThe authors found that GCI has an inverted U-shaped effect on opportunistic behavior. Furthermore, both contractual control and relational norms negatively moderate the inverted U-shaped relationship between GCI and opportunistic behavior.Originality/valueThis study uncovers an inverted U-shaped link between GCI and opportunistic behavior by combining transaction cost economics and social exchange theory. Furthermore, this study reveals contractual control and relational norms can be deemed as two boundary conditions affecting the inverted U-shaped GCI–opportunistic behavior relationship. This study also offers managerial implications for firms curbing opportunistic behavior that may result from GCI.

Managing information asymmetry in public–private relationships undergoing a digital transformation: the role of contractual and relational governance

PurposeInter-organisational governance is an important enabler for information processing, particularly in relationships undergoing digital transformation (DT) where partners depend on each other for information in decision-making. Based on information processing theory (IPT), the authors theoretically and empirically investigate how governance mechanisms address information asymmetry (uncertainty and equivocality) arising in capturing, sharing and interpreting information generated by digital technologies.Design/methodology/approachIPT is applied to four cases of public–private relationships in the Dutch infrastructure sector that aim to enhance the quantity and quality of information-based decision-making by implementing digital technologies. The investigated relationships are characterised by differing degrees and types of information uncertainty and equivocality. The authors build on rich data sets including archival data, observations, contract documents and interviews.FindingsAddressing information uncertainty requires invoking contractual control and coordination. Contract clauses should be precise and incentive schemes functional in terms of information requirements. Information equivocality is best addressed by using relational governance. Identifying information requirements and reducing information uncertainty are a prerequisite for the transformation activities that organisations perform to reduce information equivocality.Practical implicationsThe study offers insights into the roles of both governance mechanisms in managing information asymmetry in public–private relationships. The study uncovers key activities for gathering, sharing and transforming information when using digital technologies.Originality/valueThis study draws on IPT to study public–private relationships undergoing DT. The study links contractual control and coordination as well as relational governance mechanisms to information-processing activities that organisations deploy to reduce information uncertainty and equivocality.

How contract enforcement reduces opportunism? The paradoxical moderating effect of interfirm guanxi

This study investigates the hitherto largely neglected effects of contract enforcement in interfirm relationship. Based on contract functions, we conceptualize contract enforcement as a two-dimensional construct comprising contractual control enforcement and contractual coordination enforcement. We examine how the effects of these two enforcements differ as the level of interfirm guanxi varies. The findings from a survey of 190 buyers in China suggest that both contractual control enforcement and contractual coordination enforcement mitigate sellers' opportunism. Moreover, contractual coordination enforcement is more effective in reducing opportunism when the interfirm guanxi is strong, whereas contractual control enforcement is more effective in reducing opportunism when the interfirm guanxi is weak. Our research contributes to both theory and practice by revealing the complex and paradoxical moderating role of interfirm guanxi.

Enhancing Trust Between PPP Partners: The Role of Contractual Functions and Information Transparency

Contracts are essential for managing the relationship among public–private partnership (PPP) partners. However, the impact of contracts on the trust between partners is unclear, especially in PPP projects. From the multifunctional perspective of contracts, this study aims to investigate how different dimensions of contractual functions affect distinct types of trust and the moderating role of information transparency between them. The empirical results of the data collected from Chinese PPP professionals show that the three dimensions of contractual functions have positive effects on trust, including goodwill trust and competence trust. However, contractual adaptation has the strongest impact. Moreover, information transparency positively moderates the relationship between contractual control, adaptation, and trust. This study provides new insights on contracts and trust in PPP projects. It can guide PPP project partners to value the process of contract design and information disclosure to cultivate specific types of trust.

Influence of Prior Ties on Trust and Contract Functions for BIM-Enabled EPC Megaproject Performance

Drawing on transaction cost theory as well as social exchange perspective, this study investigates the influence of prior ties on trust and contract functions—contractual control, coordination, and contingency adaptability—for improving building information modeling (BIM)–enabled engineering, procurement, and construction (EPC) megaproject performance. This study compares questionnaire data collected from stakeholders in oil and gas megaprojects with and without prior working relationships and uses partial least squares structural equation modeling (PLS-SEM) to analyze the relationship between trust, contract functions, and project performance in prior ties and nonprior ties model. The results reveal that trust influences project performance via contract functions significantly in both models. This study found that parties without a prior working relationship are more willing to rely on contractual control to improve project performance, whereas contracting parties with a prior working relationship are more likely to use contingency adaptability to enhance project performance. The findings of this study expand the theoretical understanding of how the trust engendered from prior ties influences the formation of contract functions to improve the performance of BIM-enabled EPC megaprojects.

023 Sleep in a Brainless Animal - The Relationship Between Centralization and Sleep in the Upside-down Jellyfish

Abstract Introduction Though sleep is pervasive in animals, its fundamental roles, and the processes involved in generating the behavior, remain poorly understood. A key outstanding question in sleep regulation is whether sleep is controlled strictly by a top-down mechanism via activity of specific central nervous system (CNS) neurons or is controlled partially by bottom-up signals from neural and non-neural tissue. Recently, we showed that the upside-down jellyfish Cassiopea sleeps, providing an opportunity to study sleep control, regulation, and function in an animal without a CNS. Methods Cassiopea have a decentralized nervous system (DNS) of radially spaced interconnected ganglia called rhopalia along their bell margin that control muscle contractions. The signal to contract is sent to muscle fibers local to the initiating ganglion, and the contraction propagates outwards as a point source wave. We have developed computer programs to detect the controlling ganglion, which allows us to non-invasively determine ganglia activity, and to understand how a simple network of ganglia controls behavior. We are also using immunofluorescence, in situ hybridization, qPCR, and RNAseq to characterize the effect of sleep deprivation (SD) on the jellyfish nervous system. Results We have discovered a temporally centralized form of behavioral control that changes between day and night, and during SD. A subset of ganglia share behavioral control—while some almost never initiate contractions, others are active both day and night, or are mostly day-active or night-active, and SD drastically changes ganglia usage. Regions that increase activity at night are less active the following day, perhaps evidence of homeostatic regulation. Using RNAseq we found that during SD, one nAChRα subunit increases expression ~3.8-fold and we are studying its role in arousal and sleep. Conclusion We are investigating a different kind of nervous system, one that is morphologically decentralized (a network of discrete ganglia), and yet temporally centralized (a subset of ganglia dominate activity control). Wake, sleep, and SD involve different ganglia activity patterns, different levels of centralization, and different gene expression. Thus, temporal centralization could provide a mechanism to explain how local sleep, via a bottom-up mechanism, can result in organismal sleep behavior. Support (if any) UC Berkeley Miller Postdoctoral Fellowship

The mitochondrial biogenesis signaling pathway is a potential therapeutic target for myasthenia gravis via energy metabolism (Review).

Myasthenia gravis (MG) is an autoantibody-mediated autoimmune disease that is characterized by muscle weakness and fatigue. Traditional treatments for MG target the neuromuscular junction (NMJ) or the immune system. However, the efficacy of such treatments is limited, and novel therapeutic options for MG are urgently required. In the current review, a new therapeutic strategy is proposed based on the mitochondrial biogenesis and energy metabolism pathway, as stimulating mitochondrial biogenesis and the energy metabolism might alleviate myasthenia gravis. A number of cellular sensors of the energy metabolism were investigated, including AMP-activated protein kinase (AMPK) and sirtuin 1 (SIRT1). AMPK and SIRT1 are sensors that regulate cellular energy homeostasis and maintain energy metabolism by balancing anabolism and catabolism. Peroxisome proliferator-activated receptor γ coactivator 1α and its downstream transcription factors nuclear respiratory factors 1, nuclear respiratory factors 2, and transcription factor A are key sensors of mitochondrial biogenesis, which can restore mitochondrial DNA and produce new mitochondria. These processes help to control muscle contraction and relieve the symptoms of MG, including muscle weakness caused by dysfunctional NMJ transmission. Therefore, the present review provides evidence for the therapeutic potential of targeting mitochondrial biogenesis for the treatment of MG.

Neuromuscular junction-specific genes screening by deep RNA-seq analysis

BackgroundNeuromuscular junctions (NMJs) are chemical synapses formed between motor neurons and skeletal muscle fibers and are essential for controlling muscle contraction. NMJ dysfunction causes motor disorders, muscle wasting, and even breathing difficulties. Increasing evidence suggests that many NMJ disorders are closely related to alterations in specific gene products that are highly concentrated in the synaptic region of the muscle. However, many of these proteins are still undiscovered. Thus, screening for NMJ-specific proteins is essential for studying NMJ and the pathogenesis of NMJ diseases.ResultsIn this study, synaptic regions (SRs) and nonsynaptic regions (NSRs) of diaphragm samples from newborn (P0) and adult (3-month-old) mice were used for RNA-seq. A total of 92 and 182 genes were identified as differentially expressed between the SR and NSR in newborn and adult mice, respectively. Meanwhile, a total of 1563 genes were identified as differentially expressed between the newborn SR and adult SR. Gene Ontology (GO) enrichment analyses, Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis and gene set enrichment analysis (GSEA) of the DEGs were performed. Protein–protein interaction (PPI) networks were constructed using STRING and Cytoscape. Further analysis identified some novel proteins and pathways that may be important for NMJ development, maintenance and maturation. Specifically, Sv2b, Ptgir, Gabrb3, P2rx3, Dlgap1 and Rims1 may play roles in NMJ development. Hcn1 may localize to the muscle membrane to regulate NMJ maintenance. Trim63, Fbxo32 and several Asb family proteins may regulate muscle developmental-related processes.ConclusionHere, we present a complete dataset describing the spatiotemporal transcriptome changes in synaptic genes and important synaptic pathways. The neuronal projection-related pathway, ion channel activity and neuroactive ligand-receptor interaction pathway are important for NMJ development. The myelination and voltage-gated ion channel activity pathway may be important for NMJ maintenance. These data will facilitate the understanding of the molecular mechanisms underlying the development and maintenance of NMJ and the pathogenesis of NMJ disorders.

Governance mechanisms and green customer integration in China: The joint effect of power and environmental uncertainty

Drawing on transaction cost economics and social exchange theory, we explore the impact of governance mechanisms on green customer integration and the moderating effects of power and environmental uncertainty. Using data from 206 Chinese manufacturers, we can show that both contractual control and relational norms facilitate green customer integration. Interestingly, the promotional effects of contractual control and relational norms are undermined if manufacturers exert mediated power. Furthermore, the weakened effect of mediated power on the relationship between contractual control and green customer integration is strengthened by demand uncertainty. Conversely, the strengthened impact of non-mediated power on the relational norms–green customer integration relationship is strengthened by demand uncertainty as well as technological uncertainty. This study extends current green supply chain research by revealing that governance mechanisms are antecedent to green customer integration in emerging markets, from the perspective of interfirm relationship management. This study also contributes to transaction cost economics and social exchange theory by revealing how the effectiveness of governance mechanisms on green customer integration varies under different types of power and environmental uncertainty.

The haplolethality paradox of the wupA gene in Drosophila.

Haplolethals (HL) are regions of diploid genomes that in one dose are fatal for the organism. Their biological meaning is obscure because heterozygous loss-of-function mutations result in dominant lethality (DL) and, consequently, should be under strong negative selection. We report an in depth study of the HL associated to the gene wings up A (wupA). It encodes 13 transcripts (A-M) that yield 11 protein isoforms (A-K) of Troponin I (TnI). They are functionally diverse in their control of muscle contraction, cell polarity and cell proliferation. Isoform K transfers to the nucleus where it increases transcription of the cell proliferation related genes CDK2, CDK4, Rap and Rab5. The nuclear translocation of isoform K is prevented by the co-expression of A or B isoforms, which illustrates isoform interactions. The corresponding DL mutations are, either DNA rearrangements clustered towards the gene 3’ end, thus affecting the genomic organization of all transcripts, or CRISPR-induced mutations in one of the two ATG sites which eliminate a subset of wupA products. The joint elimination of isoforms C, F, G and H, however, do not cause DL phenotypes. Genetically driven expression of single isoforms rescue neither DL nor any of the mutants known in the gene, suggesting that normal function requires properly regulated expression of specific combinations, rather than single, TnI isoforms. We conclude that the wupA associated HL results from the combined haploinsufficiency of a large set of TnI isoforms. The qualitative and quantitative normal expression of which, requires the chromosomal integrity of the wupA genomic region. Since all fly TnI isoforms are encoded in the same gene, its HL condition becomes unavoidable. These wupA features are comparable to those of dpp, the only other HL studied to some extent, and reveal a scenario of strict dosage dependence with implications for gene expression regulation and splitting.

Identification and Characterization of a Novel Large-Conductance Calcium-Activated Potassium Channel Activator, CTIBD, and Its Relaxation Effect on Urinary Bladder Smooth Muscle.

The large-conductance calcium-activated potassium channel (BKCa channel) is expressed on various tissues and is involved in smooth muscle relaxation. The channel is highly expressed on urinary bladder smooth muscle cells and regulates the repolarization phase of the spontaneous action potentials that control muscle contraction. To discover novel chemical activators of the BKCa channel, we screened a chemical library containing 8364 chemical compounds using a cell-based fluorescence assay. A chemical compound containing an isoxazolyl benzene skeleton (compound 1) was identified as a potent activator of the BKCa channel and was structurally optimized through a structure-activity relationship study to obtain 4-(4-(4-chlorophenyl)-3-(trifluoromethyl)isoxazol-5-yl)benzene-1,3-diol (CTIBD). When CTIBD was applied to the treated extracellular side of the channel, the conductance-voltage relationship of the channel shifted toward a negative value, and the maximum conductance increased in a concentration-dependent manner. CTIBD altered the gating kinetics of the channel by dramatically slowing channel closing without effecting channel opening. The effects of CTIBD on bladder muscle relaxation and micturition function were tested in rat tissue and in vivo. CTIBD concentration-dependently reduced acetylcholine-induced contraction of urinary bladder smooth muscle strips. In an acetic acid-induced overactive bladder (OAB) model, intraperitoneal injection of 20 mg/kg CTIBD effectively restored frequent voiding contraction and lowered voiding volume without affecting other bladder function parameters. Thus, our results indicate that CTIBD and its derivatives are novel chemical activators of the bladder BKCa channel and potential candidates for OAB therapeutics. SIGNIFICANCE STATEMENT: The novel BKCa channel activator CTIBD was identified and characterized in this study. CTIBD directly activates the BKCa channel and relaxes urinary bladder smooth muscle of rat, so CTIBD can be a potential candidate for overactive bladder therapeutics.

Can joint-contract functions promote PPP project sustainability performance? A moderated mediation model

PurposeThe role of conventional contracts in achieving sustainability goals in public–private partnership (PPP) projects has been questioned. From the multifunctional perspective of contract theory, joint-contract functions that combine contractual control, coordination and adaptation may be a potential approach for improving PPP project sustainability performance. This research intends to investigate the link between the joint-contract functions and PPP project sustainability performance, and their underlying mechanism, by analyzing the mediating role of relationship quality and moderating roles of environmental uncertainty and behavioral uncertainty.Design/methodology/approachBased on 170 valid survey data collected from the Chinese PPP professionals, partial least squares structural equation modeling (PLS-SEM) was adopted to test the hypothesis.FindingsThe results reveal that joint-contract functions are positively associated with the PPP project sustainability performance. This relationship is strengthened by environmental and behavioral uncertainty. Moreover, the relationship between the joint-contract functions and PPP project sustainability performance is mediated by relationship quality.Research limitations/implicationsThis research extends contract governance theory and sustainability research in PPP projects. The research implications are as follows: (1) joint-contract functions are a second-order construct consisting of three first-order dimensions: control, coordination and adaptation and are positively associated with PPP project sustainability performance; (2) joint-contract functions enhance the sustainable benefits of PPP projects during environmental uncertainty and behavioral uncertainty; (3) informal relationships are a critical bridge connecting formal institutions with the sustainability performance of PPP projects.Practical implicationsIn general, these findings guide project participants who aim to achieve sustainable outcomes in PPP projects. (1) Project participants should consider the process of contract design and sign contracts that focus on joint-contract functions. (2) Project participants should investigate the degree of uncertainty of a PPP project before designing contracts, and design the contracts with corresponding complexity. (3) Project participants should work to enhance PPP sustainable benefits by improving the relationship between partners, such as encouraging mutual trust and joint problem-solving.Originality/valueThis research verifies the relationship between joint-contract functions and PPP project sustainability performance, and the boundary and intermediary conditions between them.

A chloride channel blocker prevents the suppression by inorganic phosphate of the cytosolic calcium signals that control muscle contraction

Accumulation of inorganic phosphate (Pi ) may contribute to muscle fatigue by precipitating calcium salts inside the sarcoplasmic reticulum (SR). Neither direct demonstration of this process nor definition of the entry pathway of Pi into SR are fully established. We showed that Pi promoted Ca2+ release at concentrations below 10mm and decreased it at higher concentrations. This decrease correlated well with that of [Ca2+ ]SR . Pre-treatment of permeabilized myofibres with 2mm Cl- channel blocker 9-anthracenecarboxylic acid (9AC) inhibited both effects of Pi . The biphasic dependence of Ca2+ release on [Pi ] is explained by a direct effect of Pi acting on the SR Ca2+ release channel, combined with the intra-SR precipitation of Ca2+ salts. The effects of 9AC demonstrate that Pi enters the SR via a Cl- pathway of an as-yet-undefined molecular nature. Fatiguing exercise causes hydrolysis of phosphocreatine, increasing the intracellular concentration of inorganic phosphate (Pi ). Pi diffuses into the sarcoplasmic reticulum (SR) where it is believed to form insoluble Ca2+ salts, thus contributing to the impairment of Ca2+ release. Information on the Pi entrance pathway is still lacking. In amphibian muscles endowed with isoform 3 of the RyR channel, Ca2+ spark frequency is correlated with the Ca2+ load of the SR and can be used to monitor this variable. We studied the effects of Pi on Ca2+ sparks in permeabilized fibres of the frog. Relative event frequency (f/fref ) rose with increasing [Pi ], reaching 2.54±1.6 at 5mm, and then decreased monotonically, reaching 0.09±0.03 at [Pi ]=80mm. Measurement of [Ca2+ ]SR confirmed a decrease correlated with spark frequency at high [Pi ]. A large [Ca2+ ]SR surge was observed upon Pi removal. Anion channels are a putative path for Pi into the SR. We tested the effect of the chloride channel blocker 9-anthracenecarboxylic acid (9AC) on Pi entrance. 9AC (400µm) applied to the cytoplasm produced a non-significant increase in spark frequency and reduced the Pi effects on this parameter. Fibre treatment with 2mm 9AC in the presence of high cytoplasmic Mg2+ suppressed the effects of Pi on [Ca2+ ]SR and spark frequency up to 55mm [Pi ]. These results suggest that chloride channels (or transporters) provide the main pathway of inorganic phosphate into the SR and confirm that Pi impairs Ca2+ release by accumulating and precipitating with Ca2+ inside the SR, thus contributing to myogenic fatigue.

Owners’ use of contract-based power in construction project transactions: restrictions from process specificity and uncertainty

Little is known about what restrictions make owners unable to use or give up using contract-based power in construction project transactions. To examine this issue, this research explores the effects of process specificity on owners’ contract design and power use during contract execution as well as the moderating role of uncertainty in these effects using empirical data from 327 construction project transactions in China. The results show that owners can use coercive and legitimate powers based on contractual control while using reward and legitimate powers based on contractual coordination. The increase in process specificity (a special version of asset specificity in construction project transactions) encourages owners to intensify ex ante contract design while restricting their ex post coercive power use based on contractual control. Behavioural uncertainty weakens owners’ tendency to intensify contractual control with increasing process specificity, restricting their contractual-control-based power use. However, task uncertainty strengthens (rather than restricts) owners’ tendency to intensify contract design and power use when process specificity increases. These findings can help practitioners understand how the attributes of construction project transactions are related to transaction costs to affect owners’ contract-based power use, thereby avoiding ineffective power use.

Green supplier integration and environmental innovation in Chinese firms: The joint effect of governance mechanism and trust

AbstractDespite the importance of green supplier integration, how different governance mechanisms affect its influence on environmental innovation is still debated. This article explores the moderating effect of governance mechanisms (i.e., relational norms and contractual control) on the effects of green supplier integration and two dimensions of environmental innovation (i.e., environmental incremental and radical innovation), as well as the moderating roles of trust on the above moderating effects. We examine hypothesized relationships using two‐waved survey data from 206 Chinese manufacturing enterprises. Our results suggest that contractual control positively moderates the impact of green supplier integration on environmental incremental innovation, whereas relational norms negatively moderate this impact. However, both relational norms and contractual control fail to moderate the impact of green supplier integration and environmental radical innovation. Further, trust in supplier strengthens the negative moderating effect of relational norms on the impact of green supplier integration on environmental radical innovation, which reveals the “dark side” of trust in supplier.