Expression of an extremely acidic β-1,4-glucanase from thermoacidophilic Alicyclobacillus sp. A4 in Pichia pastoris is improved by truncating the gene sequence

<p>Abstract</p> <p>Background</p> <p><it>Alicyclobacillus </it>sp. A4 is thermoacidophilic and produces many glycoside hydrolases. An extremely acidic β-1,4-glucanase (CelA4) has been isolated from <it>Alicyclobacillus </it>sp. A4 and purified. This glucanase with a molecular mass of 48.6 kDa decreases the viscosity of barley-soybean feed under simulated gastric conditions. Therefore, it has the potential to improve the nutrient bioavailability of pig feed. For the study reported herein, the full-length gene, <it>CelA4</it>, of this glucanase (CelA4) was identified using the sequences of six peptides and cloned from strain A4. The gene fragment (<it>CelA4</it>_<it>F</it>) encoding the mature protein was expressed in <it>Pichia pastoris</it>. Sequence truncation and glycosylation were found for recombinant CelA4_F, both of which affected the expression efficiency. The physical properties of various forms of CelA4 as they affected enzymatic activity were characterized.</p> <p>Results</p> <p>We located the full-length 2,148-bp gene for CelA4 (<it>CelA4</it>) in the genome of <it>Alicyclobacillus </it>sp. A4. <it>CelA4 </it>encodes a 715-residue polypeptide with a calculated molecular mass of 71.64 kDa, including an N-terminal signal peptide (residues 1-39), a catalytic domain (residues 39-497), and a C-terminal threonine-rich region (residues 498-715). Its deduced amino acid sequence and that of an <it>Alicyclobacillus acidocaldarius </it>endo-β-1,4-glucanase were identical at 44% of the residue positions. When the experimental molecular mass of CelA4_F--a recombinant protein designed to mimic the CelA4 sequence lacking the N-terminal signal peptide that had been expressed in <it>Pichia pastoris</it>--was compared with its hypothetical molecular mass, it was apparent that CelA4_Fwas truncated, possibly at residue 497. An artificially truncated gene fragment (<it>CelA4</it>_<it>T</it>) without C-terminal threonine-rich region was expressed in <it>P. pastoris</it>, and the expression efficiency of CelA4_Twas substantially greater than that of CelA4_F. Purified CelA4_Fand CelA4_Thad similar molecular masses (~60 kDa) and enzymatic properties (optimum pH, 3.4; optimum temperature, 60°C); they were relatively stable between pH 1.2 and 8.2 at 70°C and resistant to acidic and neutral proteases. However, their molecular masses and thermostabilities differed from those of CelA4 isolated from <it>Alicyclobacillus </it>sp. A4. A deglycosylated form of CelA4 (CelA4_D) had properties similar to that of CelA4 except that it was thermoliable at 60°C.</p> <p>Conclusions</p> <p>Truncation during expression of CelA4_For artificial truncation of its gene--both of which produced a form of CelA4 lacking a threonine-rich region that includes a putative linker--increased the level of enzyme produced in comparison with that produced by cultivation of <it>Alicyclobacillus </it>sp. A4. Glycosylation increased the thermostability of CelA4. Of the four forms of CelA4 studied, CelA4_Twas produced in highest yield and had the most favorable physical properties; therefore, it has potential for use in the feed industry.</p

Metamemory judgments have dissociable reactivity effects on item and interitem relational memory

Making metamemory judgments reactively changes item memory itself. Here we report the first investigation of reactive influences of making judgments of learning (JOLs) on interitem relational memory-specifically, temporal (serial) order memory. Experiment 1 found that making JOLs impaired order reconstruction. Experiment 2 observed minimal reactivity on free recall and negative reactivity on temporal clustering. Experiment 3 demonstrated a positive reactivity effect on recognition memory, and Experiment 4 detected dissociable effects of making JOLs on order reconstruction (negative) and forced-choice recognition (positive) by using the same participants and stimuli. Finally, a meta-analysis was conducted to explore reactivity effects on word list learning and to investigate whether test format moderates these effects. The results show a negative reactivity effect on interitem relational memory (order reconstruction), a modest positive effect on free recall, and a medium-to-large positive effect on recognition. Overall, these findings imply that even though making metacognitive judgments facilitates item-specific processing, it disrupts relational processing, supporting the item-order account of the reactivity effect on word list learning. (PsycInfo Database Record (c) 2023 APA, all rights reserved)

Common and distinct equity preferences in children and adults

Fairness plays a crucial role in children’s social life and has garnered considerable attention. However, previous research and theories primarily examined the development of children’s fairness behaviors in the conflict between self-interest motivation and fairness-complying motivation, neglecting the influence of advantage-seeking motivation. Moreover, despite the well-established role of gain/loss frame in human decision-making, it remains largely unclear whether the framing effect modulates fairness behaviors in children. It was hypothesized that children would exhibit advantage-seeking motivation resulting in more selfish behaviors in the loss context. To examine the hypothesis, we combined an adapted dictator game and computational modeling to investigate various motivations underlying fairness behaviors of children in both loss and gain contexts and to explore the developmental directions by contrasting children and adults. In addition, the current design enabled the dissociation between fairness knowledge and behaviors by asking participants to decide for themselves (the first-party role) or for others (the third-party role). This study recruited a total of 34 children (9–10 years, Mage = 9.82, SDage = 0.38, 16 females) and 31 college students (Mage = 19.81, SDage = 1.40, 17 females). The behavioral results indicated that children behaved more selfishly in first-party and more fairly in third-party than adults, without any significant framing effects. The computational results revealed that both children and adults exhibited aversion to advantageous and disadvantageous inequity in third-party. However, they showed distinct preferences for advantageous inequity in first-party, with advantage-seeking preferences among children and aversion to advantageous inequity among adults. These findings contribute to a deeper understanding of children’s social preferences and their developmental directions

Social Comparison Manifests in Event-related Potentials

Social comparison, a widespread phenomenon in human society, has been found to affect outcome evaluation. The need to belong to a social group may result in distinct neural responses to diverse social comparison outcomes. To extend previous studies by examining how social comparison with hierarchical characteristics is temporally processed, electroencephalography responses were recorded in the current study. Participants played a lottery game with two pseudo-players simultaneously and received both their own and the other two players’ outcomes. Results of three event-related potential components, including the P2, the feedback-related negativity (FRN), and the late positive component (LPC), indicate that social comparison manifests in three stages. First, outcomes indicating a different performance from others elicited a larger P2 than evenness. Second, the FRN showed hierarchical sensitivity to social comparison outcomes. This effect manifested asymmetrically. Finally, large difference between the participant’s outcome and the other two players’ evoked a larger LPC than the medium difference and the even condition. We suggest that during social comparison, people detect if there is any difference between self and others, and then evaluate the information of this difference hierarchically, and finally interpret the situations in which oneself deviates from the group as most motivationally salient

Research progress on degradative solvent extraction of low-rank coals

The degradative solvent extraction of low rank coal is the use of solvents to extract low rank coal under mild conditions, through the dehydration and multi-stage separation of the raw coal： the extraction products with no water content, no ash content, high calorific value properties and excellent thermoplastic properties， and low moisture of the extractive residual coal can be obtained. At the same time, the products have practical application advantages in many fields such as coal coking, advanced fuel and carbon material preparation, which have high added value, and the solvent in this technology has the advantage of being recyclable. Therefore, degradative solvent extraction is one of the effective ways to realize the graded fractionated conversion and utilization of low-rank coal. This review firstly introduces the existing low rank coal upgrading methods, and then reviews the development of degradative solvent extraction, focusing on the various influencing factors, reaction mechanisms, existing processes and product utilization of low rank coal upgrading by degradative solvent extraction. Finally, using the "Web of Science core collection" as the data source, the knowledge graph of coal solvent extraction was carved using CiteSpace scientometric software, and the research themes were analyzed to summarize the research directions and predict the research hotspots, providing some reference value for the research of degradative solution extraction of low-rank coal. The comprehensive analysis shows that: the selection of new low-cost green solvents, structural characterization and high-value utilization of extraction products have high research trends, while in-depth research on extraction mechanism and targeted regulation of extractant properties is needed to further promote the process of large-scale production

Dissociable Early Attentional Control Mechanisms Underlying Cognitive and Affective Conflicts

It has been well documented that cognitive conflict is sensitive to the relative proportion of congruent and incongruent trials. However, few studies have examined whether affective conflict processing is modulated as a function of proportion congruency (PC). To address this question we recorded eventrelated potentials (ERP) while subjects performed both cognitive and affective face-word Stroop tasks. By varying the proportion of congruent and incongruent trials in each block, we examined the extent to which PC impacts both cognitive and affective conflict control at different temporal stages. Results showed that in the cognitive task an anteriorly localized early N2 component occurred predominantly in the low proportion congruency context, whereas in the affective task it was found to occur in the high proportion congruency one. The N2 effects across the two tasks were localized to the dorsolateral prefrontal cortex, where responses were increased in the cognitive task but decreased in the affective one. Furthermore, high proportions of congruent items produced both larger amplitude of a posteriorly localized sustained potential component and a larger behavioral Stroop effect in cognitive and affective tasks. Our findings suggest that cognitive and affective conflicts engage early dissociable attentional control mechanisms and a later common conflict response system

The Time Course of the Influence of Valence and Arousal on the Implicit Processing of Affective Pictures

In the current study, we investigated the time course of the implicit processing of affective pictures with an orthogonal design of valence (negative vs. positive) by arousal (low vs. high). Previous studies with explicit tasks suggested that valence mainly modulates early event-related potential (ERP) components, whereas arousal mainly modulates late components. However, in this study with an implicit task, we observed significant interactions between valence and arousal at both early and late stages over both parietal and frontal sites, which were reflected by three different ERP components: P2a (100–200 ms), N2 (200–300 ms), and P3 (300–400 ms). Furthermore, there was also a significant main effect of arousal on P2b (200–300 ms) over parieto-occipital sites. Our results suggest that valence and arousal effects on implicit affective processing are more complicated than previous ERP studies with explicit tasks have revealed

Neural signatures of social conformity: A coordinate-based activation likelihood estimation meta-analysis of functional brain imaging studies

People often align their behaviors with group opinions, known as social conformity. Many neuroscience studies have explored the neuropsychological mechanisms underlying social conformity. Here we employed a coordinate-based meta-analysis on neuroimaging studies of social conformity with the purpose to reveal the convergence of the underlying neural architecture. We identified a convergence of reported activation foci in regions associated with normative decision-making, including ventral striatum (VS), dorsal posterior medial frontal cortex (dorsal pMFC), and anterior insula (AI). Specifically, consistent deactivation of VS and activation of dorsal pMFC and AI are identified when people&#39;s responses deviate from group opinions. In addition, the deviation-related responses in dorsal pMFC predict people&#39;s conforming behavioral adjustments. These are consistent with current models that disagreement with others might evoke &quot;error&quot; signals, cognitive imbalance, and/or aversive feelings, which are plausibly detected in these brain regions as control signals to facilitate subsequent conforming behaviors. Finally, group opinions result in altered neural correlates of valuation, manifested as stronger responses of VS to stimuli endorsed than disliked by others. (C) 2016 Elsevier Ltd. All rights reserved.</p

Social comparison in the brain: A coordinate-based meta-analysis of functional brain imaging studies on the downward and upward comparisons

Social comparison is ubiquitous across human societies with dramatic influence on people's well-being and decision making. Downward comparison (comparing to worse-off others) and upward comparison (comparing to better-off others) constitute two types of social comparisons that produce different neuropsychological consequences. Based on studies exploring neural signatures associated with downward and upward comparisons, the current study utilized a coordinate-based meta-analysis to provide a refinement of understanding about the underlying neural architecture of social comparison. We identified consistent involvement of the ventral striatum and ventromedial prefrontal cortex in downward comparison and consistent involvement of the anterior insula and dorsal anterior cingulate cortex in upward comparison. These findings fit well with the "common-currency" hypothesis that neural representations of social gain or loss resemble those for non-social reward or loss processing. Accordingly, we discussed our findings in the framework of general reinforcement learning (RL) hypothesis, arguing how social gain/loss induced by social comparisons could be encoded by the brain as a domain-general signal (i.e., prediction errors) serving to adjust people's decisions in social settings. Although the RL account may serve as a heuristic framework for the future research, other plausible accounts on the neuropsychological mechanism of social comparison were also acknowledge