Search

Mastering the art of stopping initiated actions is vital when playing video games. However, what characteristics make up the perfect warning or stop-signal remains unclear. In the present study we compared performance in a basic and a gamified stop-signal task depending on different stop-signal modalities: auditory, haptic and audio-haptic. Data from a complete within-subjects design (N = 24), revealed an advantage of haptic or audio-haptic stop-signals as compared to purely auditory ones. Further, results show an overall slower performance in the game-version compared to the basic version. With regards to the subjective experience, the results revealed higher motivation to perform in the gamified task, but a somewhat deeper flow experience in the basic task. In sum, these results confirm that stop-signal modality influences reactive response inhibition in both basic and gamified tasks. Future research may extend and generalize these findings to other cross-modal and more complicated gaming setups. Game developers may draw on these findings to optimize the communication of stop signals via vibrations in a handheld controller. [ABSTRACT FROM AUTHOR]

Establishment of arbuscular mycorrhiza relies on a plant signaling pathway that can be activated by fungal chitinic signals such as short-chain chitooligosaccharides and lipo-chitooligosaccharides (LCOs). The tomato LysM receptor-like kinase SlLYK10 has high affinity for LCOs and is involved in root colonization by arbuscular mycorrhizal fungi (AMF); however, its role in LCO responses has not yet been studied. Here, we show that SlLYK10 proteins produced by the Sllyk10-1 and Sllyk10-2 mutant alleles, which both cause decreases in AMF colonization and carry mutations in LysM1 and 2, respectively, have similar LCO-binding affinities compared to the WT SlLYK10. However, the mutant forms were no longer able to induce cell death in Nicotiana benthamiana when co-expressed with MtLYK3, a Medicago truncatula LCO co-receptor, while they physically interacted with MtLYK3 in co-purification experiments. This suggests that the LysM mutations affect the ability of SlLYK10 to trigger signaling through a potential co-receptor rather than its ability to bind LCOs. Interestingly, tomato lines that contain a calcium (Ca2+) concentration reporter [genetically encoded Ca2+ indicators (GECO)], showed Ca2+ spiking in response to LCO applications, but this occurred only in inner cell layers of the roots, while short-chain chitooligosaccharides also induced Ca2+ spiking in the epidermis. Moreover, LCO-induced Ca2+ spiking was decreased in Sllyk10-1 * GECO plants, suggesting that the decrease in AMF colonization in Sllyk10-1 is due to abnormal LCO signaling. [ABSTRACT FROM AUTHOR]

ABSTRACTNative dispersion, the terminal stage in biofilm development, is characterized by the active escape of cells from a biofilm, leaving behind central voids or hollow structures. However, much of what is known about the dispersion mechanism stems from results obtained in experiments using exogenously added dispersion cues such as nitric oxide (NO) and glutamate. To begin exploring the mechanism of native (endogenous) dispersion by Pseudomonas aeruginosa PAO1 biofilms, we examined the similarities between dispersion exogenously induced with NO and the previously reported native dispersion inducer, cis-2-decenoic acid (cis-DA), as well as native dispersion. Induction of dispersion with cis-DA was similar to induction with NO, with a significant reduction in cyclic dimeric guanosine monophosphate levels compared with uninduced cells but increased expression of pelA, pslG, endA, and eddA. Of those factors known to contribute to P. aeruginosa biofilm dispersion induced by glutamate and NO, only BdlA, AmrZ, RbdA, and DipA were shown to contribute to dispersion induced with cis-DA. The above factors were also shown to contribute to dispersion when no exogenous inducer was added, as indicated by microcolony void formation, a hallmark of native (endogenous) biofilm dispersion. Interestingly, phosphodiesterase PA2133, the previously reported dispersion sensors (NbdA, MucR, and NicD), and a predicted cis-DA sensor PA4892 played no detectable role in native or cis-DA-dependent dispersion. Instead, we show that cis-DA signal sensing by P. aeruginosa required the sensor/response regulator hybrid DspS (PA4112), with inactivation of dspS impairing cis-DA-induced and native dispersion in two P. aeruginosa strains, PAO1 and PA14. Overall, our findings indicate that while sensing of cis-DA and dispersion cues such as NO and glutamate are distinct, the downstream mechanisms leading to the liberation of biofilm cells and, thus, dispersion rely on a shared pathway.IMPORTANCEDispersion is an essential stage of the biofilm life cycle resulting in the release of bacteria from a biofilm into the surrounding environment. Dispersion contributes to bacterial survival by relieving overcrowding within a biofilm and allowing dissemination of cells into new habitats for colonization. Thus, dispersion can contribute to biofilm survival as well as disease progression and transmission. Cells dispersed from a biofilm rapidly lose their recalcitrant antimicrobial-tolerant biofilm phenotype and transition to a state that is susceptible to antibiotics. However, much of what is known about this biofilm developmental stage has been inferred from exogenously induced dispersion. Our findings provide the first evidence that native dispersion is coincident with reduced cyclic dimeric guanosine monophosphate levels, while also relying on at least some of the same factors that are central to the environmentally induced dispersion response, namely, BdlA, DipA, RbdA, and AmrZ. Additionally, we demonstrate for the first time that cis-DA signaling to induce dispersion is attributed to the two-component sensor/response regulator DspS, a homolog of the DSF sensor RpfC. Our findings also provide a path toward manipulating the native dispersion response as a novel and highly promising therapeutic intervention.

In the context of partial autonomy, where autonomous vehicles and humans share control of the vehicle, bringing out-of-the-loop drivers back into the loop is a significant challenge. While warning signal design guidelines are commonly used to provide alerts, few studies have examined each signal in depth with an emphasis on the autonomous environment. This study aims to fill this gap by investigating visual, auditory, and tactile stimuli and modifying their sub-attributes to explore variations related to age, gender, and other individual backgrounds. For this objective, the research examined the correlations between age, gender, and individual backgrounds with reaction times to TOR signals, investigating the effects of sub-attribute variations on participants' responses and exploring the subjective evaluations of the signals. A driving simulator was utilized to create a realistic driving environment and measure participants' reaction times in takeover request situations. Analysis of the data revealed correlations between age and reaction times for auditory and tactile signals, with interaction effects observed between age and sub-attribute intensity. Additionally, participants exhibited varying reaction time patterns in response to different sub-attribute intensities. By evaluating individual differences in perception based on modality characteristics, often overlooked in prior research, this study serves as a foundational contribution to future research in the field. [ABSTRACT FROM AUTHOR]

In the context of partial autonomy, where autonomous vehicles and humans share control of the vehicle, bringing out-of-the-loop drivers back into the loop is a significant challenge. While warning signal design guidelines are commonly used to provide alerts, few studies have examined each signal in depth with an emphasis on the autonomous environment. This study aims to fill this gap by investigating visual, auditory, and tactile stimuli and modifying their sub-attributes to explore variations related to age, gender, and other individual backgrounds. For this objective, the research examined the correlations between age, gender, and individual backgrounds with reaction times to TOR signals, investigating the effects of sub-attribute variations on participants’ responses and exploring the subjective evaluations of the signals. A driving simulator was utilized to create a realistic driving environment and measure participants’ reaction times in takeover request situations. Analysis of the data revealed correlations between age and reaction times for auditory and tactile signals, with interaction effects observed between age and sub-attribute intensity. Additionally, participants exhibited varying reaction time patterns in response to different sub-attribute intensities. By evaluating individual differences in perception based on modality characteristics, often overlooked in prior research, this study serves as a foundational contribution to future research in the field.

• Gonadal steroid hormones often modulate signal production and perception. • Steroid-related genes are expressed in electrosensory brain regions. • Androgen and estrogen receptor and aromatase gene expression varied across species. • Steroids have the potential to modulate species-specific electrosensory processing. The production of communication signals can be modulated by hormones acting on the brain regions that regulate these signals. However, less is known about how signal perception is regulated by hormones. The electrocommunication signals of weakly electric fishes are sexually dimorphic, sensitive to hormones, and vary across species. The neural circuits that regulate the production and perception of these signals are also well-characterized, and electric fishes are thus an excellent model to examine the neuroendocrine regulation of sensorimotor mechanisms of communication. We investigated (1) whether steroid-related genes are expressed in sensory brain regions that process communication signals; and (2) whether this expression differs across sexes and species that have different patterns of sexual dimorphism in their signals. Apteronotus leptorhynchus and Apteronotus albifrons produce continuous electric organ discharges (EODs) that are used for communication. Two brain regions, the electrosensory lateral line lobe (ELL) and the dorsal torus semicircularis (TSd), process inputs from electroreceptors to allow fish to detect and discriminate electrocommunication signals. We used qPCR to quantify the expression of genes for two androgen receptors (ar1 , ar2), two estrogen receptors (esr1 , esr2b), and aromatase (cyp19a1b). Four out of five steroid-related genes were expressed in both sensory brain regions, and their expression often varied between sexes and species. These results suggest that expression of steroid-related genes in the brain may differentially influence how EOD signals are encoded across species and sexes, and that gonadal steroids may coordinately regulate central circuits that control both the production and perception of EODs. [ABSTRACT FROM AUTHOR]

In contrast to most autotrophic plants, which produce carbohydrates from carbon dioxide using photosynthesis, parasitic plants obtain water and nutrients by parasitizing host plants. Many important crop plants are infested by these heterotrophic plants, leading to severe agricultural loss and reduced food security. Understanding how host plants perceive and resist parasitic plants provides insight into underlying defense mechanisms and the potential for agricultural applications. In this review, we offer a comprehensive overview of the current understanding of host perception of parasitic plants and the pre-attachment and post-attachment defense responses mounted by the host. Since most current research overlooks the role of organ specificity in resistance responses, we also summarize the current understanding and cases of cross-organ parasitism, which indicates nonconventional haustorial connections on other host organs, for example, when stem parasitic plants form haustoria on their host roots. Understanding how different tissue types respond to parasitic plants could provide the potential for developing a universal resistance mechanism in crops against both root and stem parasitic plants. [ABSTRACT FROM AUTHOR]

• Modality-dependent signal perception was analyzed in a naturalistic cycling setting. • Participants responded significantly less often to visual signals than to both other signal types. • Participants responded to only 65.1% of the transmitted visual signals. • The response rates to auditory and tactile signals are similar except on bumpy roads. • The environment within which the signal is transmitted affects signal perception. Cyclists are considered to be amongst the most vulnerable road users and the number of cyclists involved in crashes is increasing. One possibility to improve bicycle safety is the implementation of assistance systems, for instance by providing the information needed to avoid critical situations. However, it is not known how and what kind of signals can reliably be transmitted to cyclists, in particular as warnings. This study has the objective to investigate which signal type dependent of the modality and the route type can be perceived during the cycling task. Therefore, we conducted a semi-naturalistic cycling study with 56 participants where a 10 km long, pre-defined route was individually cycled while 36 signals (visual, auditory and vibro-tactile) were transmitted. The participants signalled the perception of a signal by pressing a button. Response rates differed significantly between signal modalities. While auditory signals performed best closely followed by vibro-tactile signals, visual signals were frequently missed. The route type had an effect on the perception of the signals. The influence of the route segments with haptic interference was not expected to be this large on the perception of vibro-tactile signals. The obtained results indicate how and in which situations the different modalities are suited to transmit information to cyclists. [ABSTRACT FROM AUTHOR]

Territoriality is a widespread behavioral phenomenon that functions for partitioning space and defending resources. Birds tend to defend territories against homospecific individuals through long-distance acoustic signals, but some species also exhibit interspecific territoriality. Two main hypotheses could explain interspecific territoriality mediated by long-distance acoustic signals: (1) misidentification of heterospecifics as homospecifics (misdirected aggression), or (2) recognition of heterospecifics as threats (purposeful aggression). The sympatric Red-and-white crake (Laterallus leucopyrrhus) and the Rufous-sided crake (L. melanophaius) are reciprocally territorial, but the mechanism underlying this interspecific territoriality is not known. We assessed the similarity of territorial long-distance acoustic signals (duet trills) between these crakes in comparison to more closely related species: Red-and-white vs. Rufous-faced crake (L. xenopterus) and Rufous-sided vs. White-throated crake (L. albigularis). Duet trills are two-parted, beginning with soft initial notes audible at close range and followed by a loud-trilled portion audible at long range. We ran univariate comparisons (Kruskal–Wallis), assessed overlap in multivariate acoustic space (PCA), and calculated vocal similarities (cluster analysis; Euclidean distances). The loud-trilled portions of the interspecifically territorial Red-and-white and Rufous-sided crakes occupied completely non-overlapping acoustic spaces, and were not grouped together by vocal similarity. Their territorial signals were more similar to those of their closest relatives, than between them. Soft initial notes of duet trills were in general very different between species, and their general structure matched the phylogenetic relationships. We found no evidence for strong character convergence and partial phylogenetic conservatism in signal explained overall similarities in vocalizations among species. The highly divergent vocalizations of Red-and-white and Rufous-sided crakes in conjunction with their interspecific territorial responses suggest that recognition of heterospecifics as threats, and not misidentification of heterospecifics as homospecifics, mediates their vocal responses. Our study adds evidence showing that interspecific territoriality represents purposeful heterospecific aggression and is not the product of misdirected homospecific aggression. [ABSTRACT FROM AUTHOR]

For decades, acoustic insects have been used as model organisms for behavioural neurobiologists to understand mate choice or predator avoidance, because behaviour can easily and reliably be elicited in the laboratory, and behaviourally relevant, identified nerve cells be studied under these conditions. However, signalling often takes place in complex environments, in which the signal perceived by the receiver may differ greatly from the one broadcast due to the biotic and abiotic properties of the sound transmission channel. Thus, the key challenge is to transfer the insights of these laboratory‐oriented experiments to more natural settings.Signal detection, identification and discrimination, as well as localization, are complicated by the transmission channel in several ways. Here, I review the empirical evidence from outdoor studies, demonstrating how excess attenuation reduces the active space and the information of a signal at some distance from the sender. At the same time, these frequency‐dependent processes allow to maintain acoustic distances to neighbours in a population.Insects often communicate within choruses of signallers of the same and different species, giving rise to high levels of acoustic masking interference. I discuss the evidence found for temporal or spatial partitioning of species in multispecies assemblages, and I show that solutions to the masking problem are based on a combination of adaptations in the behaviour of signallers and in the sensory system of receivers.Whether or not the perceived signal elicits a behaviour in receivers will depend on the design of the sensory system and the brain. I give examples for active mechanical processes in insect sensory receptors that influence the responses to external stimuli. In addition, neuronal filters in the frequency, intensity or time domain, and even the memory of individual receivers, provide the basis for adaptive receiver decision‐making in mate choice scenarios.Finally, I describe the advantages of having access to the relatively simple nervous systems of insects and how this access, combined with the use of a variety of behavioural tests, allows new insights into acoustic communication and its evolution. A free Plain Language Summary can be found within the Supporting Information of this article. [ABSTRACT FROM AUTHOR]

Cold stress, including freezing stress and chilling stress, is one of the major environmental factors that limit the growth and productivity of plants. As a temperate dicot model plant species, Arabidopsis develops a capability to freezing tolerance through cold acclimation. The past decades have witnessed a deep understanding of mechanisms underlying cold stress signal perception, transduction, and freezing tolerance in Arabidopsis. In contrast, a monocot cereal model plant species derived from tropical and subtropical origins, rice, is very sensitive to chilling stress and has evolved a different mechanism for chilling stress signaling and response. In this review, the authors summarized the recent progress in our understanding of cold stress response mechanisms, highlighted the convergent and divergent mechanisms between Arabidopsis and rice plasma membrane cold stress perceptions, calcium signaling, phospholipid signaling, MAPK cascade signaling, ROS signaling, and ICE-CBF regulatory network, as well as light-regulated signal transduction system. Genetic engineering approaches of developing freezing tolerant Arabidopsis and chilling tolerant rice were also reviewed. Finally, the future perspective of cold stress signaling and tolerance in rice was proposed.

The strigolactone (SL) receptor in plants is unusual in that it both binds and hydrolyses SL molecules. Landmark studies had proposed that a product of hydrolysis irreversibly binds the receptor and then activates signalling. However, recent breakthrough articles (Seto et al. Nat. Commun. 2019;10:191 and Shabek et al. Nature 2018;563:652–656) have revealed a new model based on inhibition of hydrolysis by protein conformation. [ABSTRACT FROM AUTHOR]

Clinicians have long used self-report methods to assess hearing aid benefit. However, there are fewer data as to whether self-report instruments can be used to compare differences between signal processing settings. This study examined how self-perceived performance varied as a function of modifications in signal processing using two self-report measures. Data were collected as part of a double-blind randomised crossover clinical trial. Participants were fit with two fittings: mild processing (slow time constants, disabled frequency lowering) and strong processing (fast time constants, frequency lowering enabled). The speech, spatial, and qualities of hearing (SSQ) questionnaire and the Effectiveness of Auditory Rehabilitation (EAR) questionnaire were collected at multiple time points. Older adults with sensorineural hearing loss who had not used hearing aids within the previous year participated (49 older adults were consented; 40 were included in the final data analyses). Findings show that listeners report a difference in perceived performance when hearing aid features are modified. Both self-report measures were able to capture this change in perceived performance. Self-report measures provide a tool for capturing changes in perceived performance when hearing aid processing features are modified and may enhance provision of an evidence-based hearing aid fitting. [ABSTRACT FROM AUTHOR]

Ant queen pheromones (QPs) have long been known to affect colony functioning. In many species, QPs affect important reproductive functions such as diploid larvae sexualization and egg-laying by workers, unmated queens (gynes), or other queens. Until the 1990s, these effects were generally viewed to be the result of queen manipulation through the use of coercive or dishonest signals. However, in their seminal 1993 paper, Keller and Nonacs challenged this idea, suggesting that QPs had evolved as honest signals that informed workers and other colony members of the queen’s presence and reproductive state. This paper has greatly influenced the study of ant QPs and inspired numerous attempts to identify fertility-related compounds and test their physiological and behavioral effects. In the present article, we review the literature on ant QPs in various contexts and pay special attention to the role of cuticular hydrocarbons (CHCs). Although the controversy generated by Keller and Nonacs’ (Anim Behav 45:787-794, 1993) paper is currently less intensively debated, there is still no clear evidence which allows the rejection of the queen control hypothesis in favor of the queen signal hypothesis. We argue that important questions remain regarding the mode of action of QPs, and their targets which may help understanding their evolution. [ABSTRACT FROM AUTHOR]

As fixed organisms, plants are especially affected by changes in their environment and have consequently evolved extensive mechanisms for acclimation and adaptation. Initially considered by-products from aerobic metabolism, reactive oxygen species (ROS) have emerged as major regulatory molecules in plants and their roles in early signaling events initiated by cellular metabolic perturbation and environmental stimuli are now established. Here, we review recent advances in ROS signaling. Compartment-specific and cross-compartmental signaling pathways initiated by the presence of ROS are discussed. Special attention is dedicated to established and hypothetical ROS-sensing events. The roles of ROS in long-distance signaling, immune responses, and plant development are evaluated. Finally, we outline the most challenging contemporary questions in the field of plant ROS biology and the need to further elucidate mechanisms allowing sensing, signaling specificity, and coordination of multiple signals. [ABSTRACT FROM AUTHOR]

Transient gene expression in protoplasts has been applied to the analysis of gene expression, promoter activity, subcellular localization of proteins, and genome editing. Its advantages have been realized in recent years in various physiological, biochemical, genetic, and molecular biological studies. The omics and systems biology studies of plant development and their interactions with the environment have revitalized this approach. Early plant-pathogen interaction represents one of the most unique signalling research areas. Here, we try to discuss some developments and current applications of the protoplast system. It is for sure that the system will significantly bridge the gap between high throughput approaches and functional analysis in the study of plant-pathogen interactions in the omics era. [ABSTRACT FROM AUTHOR]

Strigolactones (SLs), a recently discovered class of phytohormones, are important regulators of plant growth and development. While the biosynthetic pathway of these molecules is well documented, until recently there was not much known about the molecular mechanisms underlying SL perception and signal transduction in plants. Certain aspects of their perception and signalling, including the hormone-mediated interaction between receptor and F-box protein, degradation of suppressor proteins and activation of transcription factors, are also found in other phytohormones. However some of SL signalling features seem to be specific for the SL signalling pathway. These include the enzymatic activity of the SL receptor and its destabilisation caused by SLs. This review summarizes the current knowledge about SL signalling pathway in plants.

Brassinosteroids (BRs) are plant steroids essential for the normal growth and development, which carry an oxygen moiety at C-3 and additional ones at one or more of the C-2, C-6, C-22 and C-23 carbon atoms. In the past few years, application of molecular genetics allowed significant progress on the understanding of the BRs biosynthetic pathway regulation and on the identification of several components of their signal transduction pathway, as well. Search in eletronic databases show dozens of records for brassinosteroid-related genes for the last twelve months, demonstrating the big efforts being carried out in this field. This review highlights the recent advances on the characterization of genes and mutations that are helping to unravel the molecular mechanisms involved in the BRs synthesis/metabolism, perception and response, with especial emphasis on their role in plant cell elongation. Aspects of the involvement of BRs on the regulation of cell cycle-controlling proteins are discussed as well.Brassinoesteróides são esteróides vegetais, essenciais para o crescimento e o desenvolvimento, que apresentam um oxigênio no carbono C-3 e oxigênios adicionais em um ou mais dos átomos de carbono C-2, C-6, C-22 e C-23. Nos últimos anos, a aplicação de técnicas de genética molecular possibilitou progresso significativo no entendimento da regulação da via biossintética e na identificação de vários componentes da via de transdução de sinal de brassinoesteróides. Buscas em bases de dados eletrônicas mostram dúzias de registros para genes relacionados a brassinoesteróides nos últimos doze meses, demonstrando os grandes esforços desenvolvidos neste campo. Esta revisão destaca os recentes avanços na caracterização de genes e mutações que estão auxiliando na elucidação dos mecanismos moleculares envolvidos na síntese/metabolismo, e percepção e resposta de brassinoesteróides, com ênfase especial no seu papel no alongamento de células vegetais. Aspectos do envolvimento de BRs na regulação de proteínas que controlam o ciclo cellular também são discutidos.

Nt-Sd- RLK encodes an S-domain lectin receptor-like kinase that is induced in response to microbe-associated molecular pattern molecules ( MAMPs) such as lipopolysaccharide ( LPS). In this study, we investigated the alternative splicing of Nt-Sd- RLK in response to LPS stimulation. Our data indicate that in nonstimulated cells, a shorter transcript of Nt-Sd- RLK is generated and that in response to LPS, alternative splicing produces the full-length transcript. We propose that the extracellular domain of Nt-Sd- RLK encoded by the shorter transcript functions in pathogen surveillance. Once this domain binds LPS, alternative splicing generates the kinase domain-containing Nt-Sd- RLK that activates downstream signalling leading to a defence response. Thus, our findings suggest that plant defence signalling may be regulated through the alternative splicing of receptor-like kinases involved in pathogen recognition. [ABSTRACT FROM AUTHOR]

Strigolactones (SLs), a recently discovered class of phytohormones, are important regulators of plant growth and development. While the biosynthetic pathway of these molecules is well documented, until recently there was not much known about the molecular mechanisms underlying SL perception and signal transduction in plants. Certain aspects of their perception and signaling, including the hormone-mediated interaction between receptor and F-box protein, degradation of suppressor proteins and activation of transcription factors, are also found in other phytohormones. However, some of SL signaling features seem to be specific for the SL signaling pathway. These include the enzymatic activity of the SL receptor and its destabilization caused by SLs. This review summarizes the current knowledge about SL signaling pathway in plants. [ABSTRACT FROM AUTHOR]

In plants, fluctuation of the redox balance by altered levels of reactive oxygen species (ROS) can affect many aspects of cellular physiology. ROS homeostasis is governed by a diversified set of antioxidant systems. Perturbation of this homeostasis leads to transient or permanent changes in the redox status and is exploited by plants in different stress signalling mechanisms. Understanding how plants sense ROS and transduce these stimuli into downstream biological responses is still a major challenge. ROS can provoke reversible and irreversible modifications to proteins that act in diverse signalling pathways. These oxidative post-translational modifications (Ox-PTMs) lead to oxidative damage and/or trigger structural alterations in these target proteins. Characterization of the effect of individual Ox-PTMs on individual proteins is the key to a better understanding of how cells interpret the oxidative signals that arise from developmental cues and stress conditions. This review focuses on ROS-mediated Ox-PTMs on cysteine (Cys) residues. The Cys side chain, with its high nucleophilic capacity, appears to be the principle target of ROS. Ox-PTMs on Cys residues participate in various signalling cascades initiated by plant stress hormones. We review the mechanistic aspects and functional consequences of Cys Ox-PTMs on specific target proteins in view of stress signalling events. [ABSTRACT FROM AUTHOR]

We investigate the theoretically proposed link between judgmental overconfidence and trading activity. In addition to applying classical measures of miscalibration, we introduce a measure to capture misperception of signal reliability, which is the relevant bias in the theoretical overconfidence literature. We relate the obtained overconfidence measures to trading activity in call and continuous experimental asset markets. Our results confirm prior findings that classical miscalibration measures are not related to trading activity. Misperception of signal reliability is positively related to trading volume in the continuous market for one of two treatments. In the other one, no relation is found except that highly overconfident subjects trade less. In addition, we find that men trade more than women at high levels of risk aversion, but the gender trading gap vanishes as risk aversion lessens. The reason is that the trading activity of women seems to be more sensitive to risk attitudes than that of men. [ABSTRACT FROM AUTHOR]

Background The ColRS two-component system has been shown to contribute to the membrane functionality and stress tolerance of Pseudomonas putida as well as to the virulence of Pseudomonas aeruginosa and plant pathogenic Xanthomonas species. However, the conditions activating the ColRS pathway and the signal(s) sensed by ColS have remained unknown. Here we aimed to analyze the role of the ColRS system in metal tolerance of P. putida and to test whether ColS can respond to metal excess. Results We show that the ColRS system is necessary for P. putida to tolerate the excess of iron and zinc, and that it also contributes to manganese and cadmium tolerance. Excess of iron, zinc, manganese or cadmium activates ColRS signaling and as a result modifies the expression of ColR-regulated genes. Our data suggest that the genes in the ColR regulon are functionally redundant, as several loci have to be deleted to observe a significant decrease in metal tolerance. Site-directed mutagenesis of ColS revealed that excess of iron and, surprisingly, also zinc are sensed by a conserved ExxE motif in ColS's periplasmic domain. While ColS is able to sense different metals, it still discriminates between the two oxidation states of iron, specifically responding to ferric and not ferrous iron. We propose a signal perception model involving a dimeric ColS, where each monomer donates one ExxE motif for metal binding. Conclusions Several transition metals are essential for living organisms in certain amounts, but toxic in excess. We show that ColRS is a sensor system which detects and responds to the excess of physiologically important metals such as zinc, iron and manganese. Thus, the ColRS system is an important factor for metal homeostasis and tolerance in P. putida. [ABSTRACT FROM AUTHOR]

Histidine kinases are sensory proteins involved in the perception of environmental changes. Here, we characterized one of three essential histidine kinases, Hik2, in the cyanobacterium Synechocystis sp. PCC 6803 by constructing a fused sensor, Hik2n- Hik7c, which has the signal input domain of Hik2 and the kinase domain of the phosphate-deficiency sensor Hik7. The coding region of the hik7 gene was replaced with the fused sensor to evaluate the signalling activity in vivo as the activity of alkaline phosphatase ( AP), which is regulated by Hik7. Cells expressing Hik2n- Hik7c had weak AP activities under standard growth conditions. Saline stress by NaCl induced AP activity in a dose-dependent manner. Analysis of the effects of several salt compounds on induction of AP activity indicated that Hik2n- Hik7c responded to Cl− concentration. Amino acid substitution in the signal input domain of Hik2 resulted in loss of this responsiveness. These results suggest that the signal input domain of Hik2 responds to environmental Cl− concentration in Synechocystis. [ABSTRACT FROM AUTHOR]

Histidine kinase Hik33 responds to a variety of stress conditions and regulates the expression of stress-inducible genes in the cyanobacterium Synechocystis sp. PCC 6803. However, the mechanisms of response and regulation remain unknown. Generally, a histidine kinase perceives a specific signal via its N-terminal region. Hik33 has two transmembrane helices, a periplasmic loop, and HAMP and PAS domains in its N-terminal region, all of which might be involved in signal perception. To investigate the functions of these subdomains in vivo, we expressed a chimeric histidine kinase (Hik33n–SphSc) by fusing the N-terminal region of Hik33 with the C-terminal region of a sensory histidine kinase that is activated under phosphate-deficient conditions, SphS. Hik33n–SphSc responded to several stimuli that are perceived by intact Hik33 and regulated expression of the phoA gene for alkaline phosphatase, which is normally regulated under phosphate-deficient conditions by SphS. We introduced genes for modified versions of Hik33n–SphSc into Synechocystis and monitored expression of phoA under standard and stress conditions. Hik33n–SphSc lacking either the transmembrane helices or both the HAMP and PAS domains had no kinase activity, whereas Hik33n–SphSc lacking the HAMP or the PAS domain enhanced expression of phoA. Moreover, variants of Hik33n–SphSc, in which the membrane-localizing region was replaced by those of other histidine kinases, also responded to stress conditions. Thus, transmembrane helices, regardless of sequence, appear to be essential for the function of Hik33, while the HAMP and PAS domains play important roles in regulating kinase activity in vivo. [ABSTRACT FROM PUBLISHER]

Abstract: The isolation, characterization and regulation of the first lipopolysaccharide (LPS)-responsive S-domain receptor-like kinase (RLK) in Nicotiana tabacum are reported. The gene, corresponding to a differentially expressed LPS-responsive EST, was fully characterised to investigate its involvement in LPS-induced responses. The full genomic sequence, designated Nt-Sd-RLK, encodes for a S-domain RLK protein containing conserved modules (B-lectin-, S- and PAN-domains) reported to function in mediating protein–protein and protein–carbohydrate interactions in its extracellular domain, as well as the molecular architecture to transduce signals intracellularly through a Ser/Thr kinase domain. Phylogenetic analysis clustered Nt-Sd-RLK with S-domain RLKs induced by bacteria, wounding and salicylic acid. Perception of LPS induced a rapid, bi-phasic response in Nt-Sd-RLK expression with a 17-fold up-regulation at 3 and 9h. A defence-related W-box cis element was found in the promoter region of Nt-Sd-RLK and the transient induction of Nt-Sd-RLK in cultured cells by LPS exhibited a pattern typical of early response defence genes. Nt-Sd-RLK was also responsive to salicylic acid induction and was expressed in differentiated leaf tissue, where LPS elicited local as well as systemic up-regulation. The results contribute new knowledge about the potential role that S-domain RLKs may play within interactive signal transduction pathways associated with immunity and defence. [Copyright &y& Elsevier]

Apart from water availability, low temperature is the most important environmental factor limiting the productivity and geographical distribution of plants across the world. To cope with cold stress, plant species have evolved several physiological and molecular adaptations to maximize cold tolerance by adjusting their metabolism. The regulation of some gene products represents an additional mechanism of cold tolerance. A consequence of these mechanisms is that plants are able to survive exposure to low temperature via a process known as cold acclimation. In this review, we briefly summarize recent progress in research and hypotheses on how sensitive plants perceive cold. We also explore how this perception is translated into changes within plants following exposure to low temperatures. Particular emphasis is placed on physiological parameters as well as transcriptional, post-transcriptional and post-translational regulation of cold-induced gene products that occur after exposure to low temperatures, leading to cold acclimation. [ABSTRACT FROM AUTHOR]

Abstract: Confronted to changes in temperatures, plants readjust their biochemical makeup to adapt and survive. The fact that temperature changes can induce cellular responses indicates that temperature is sensed and that the temperature signal is transduced into the cell. While the signalling pathways triggered temperature changes are well described, the way plants sense temperature is often considered as elusive. This review is focused on the mechanisms by which plants sense temperature. We show that plants have no internal thermometer as such, but that the very alterations in cellular equilibria triggered by temperature changes act as networked thermostats to sense heat and cold. Amongst these temperature-sensitive devices, we identified membrane fluidity, protein conformation, cytoskeleton depolymerization, and metabolic reactions. Besides, other molecular switches are proposed. A model of the temperature sensing “machinery” is proposed. Finally, we discuss the specificities of temperature sensing, showing that signalling events can feed-back perception steps. [Copyright &y& Elsevier]