How Feature Context alters Attentional Template Switching

In real-world tasks visual attention is rarely aimed at a single object. Humans rather“forage” the visual scene for information, dynamically switching attentional templates. Several visual search studies have found that observers often use suboptimal attentional control strategies, possibly to avoid effort. Here, we investigated with a foraging paradigm if observers’ reluctance to switch between attentional templates increases with template specificity. To that end, we manipulated the feature context of displays in which participants “foraged” moving stimuli on a tablet-PC. Experiment 1 (N = 35) revealed a decline in switching tendency and foraging efficiency with increasing feature-space distance between target alternatives. Experiment 2 (N = 36) found even lower flexibility with distractor color close to, and strongest impairments with distractor color in between target colors. Our results demonstrate that visualinformation sampling is most flexible when broad (instead of very specific) templates and relational search strategies are possible (e.g., attending “redder” objects), with implications for both attention research and applications, especially in visual-foraging-like tasks, such as baggage screening or medical image assessment.

When more is more: redundant modifiers can facilitate visual search

According to the Gricean Maxim of Quantity, speakers provide the amount of information listeners require to correctly interpret an utterance, and no more (Grice in Logic and conversation, 1975). However, speakers do tend to violate the Maxim of Quantity often, especially when the redundant information improves reference precision (Degen et al. in Psychol Rev 127(4):591–621, 2020). Redundant (non-contrastive) information may facilitate real-world search if it narrows the spatial scope under consideration, or improves target template specificity. The current study investigated whether non-contrastive modifiers that improve reference precision facilitate visual search in real-world scenes. In two visual search experiments, we compared search performance when perceptually relevant, but non-contrastive modifiers were included in the search instruction. Participants (NExp. 1 = 48, NExp. 2 = 48) searched for a unique target object following a search instruction that contained either no modifier, a location modifier (Experiment 1: on the top left, Experiment 2: on the shelf), or a color modifier (the black lamp). In Experiment 1 only, the target was located faster when the verbal instruction included either modifier, and there was an overall benefit of color modifiers in a combined analysis for scenes and conditions common to both experiments. The results suggest that violations of the Maxim of Quantity can facilitate search when the violations include task-relevant information that either augments the target template or constrains the search space, and when at least one modifier provides a highly reliable cue. Consistent with Degen et al. (2020), we conclude that listeners benefit from non-contrastive information that improves reference precision, and engage in rational reference comprehension. Significance statement This study investigated whether providing more information than someone needs to find an object in a photograph helps them to find that object more easily, even though it means they need to interpret a more complicated sentence. Before searching a scene, participants were either given information about where the object would be located in the scene, what color the object was, or were only told what object to search for. The results showed that providing additional information helped participants locate an object in an image more easily only when at least one piece of information communicated what part of the scene the object was in, which suggests that more information can be beneficial as long as that information is specific and helps the recipient achieve a goal. We conclude that people will pay attention to redundant information when it supports their task. In practice, our results suggest that instructions in other contexts (e.g., real-world navigation, using a smartphone app, prescription instructions, etc.) can benefit from the inclusion of what appears to be redundant information.

When more is more: Redundant modifiers can facilitate visual search

According to the Gricean Maxim of Quantity, speakers provide the amount of information listeners require to correctly interpret an utterance, and no more (Grice, 1975). However, speakers do tend to violate the Maxim of Quantity often, especially when the redundant information improves reference precision (Degen et al., 2020). Redundant (non-contrastive) information may facilitate real-world search if it narrows the spatial scope under consideration, or improves target template specificity. The current study investigated whether non-contrastive modifiers that improve reference precision facilitate visual search in real-world scenes. In two visual search experiments, we compared search performance when perceptually-relevant, but non-contrastive modifiers were included in the search instruction. Participants (NExp. 1=48, NExp. 2=48) searched for a unique target object following a search instruction that contained either no modifier, a location modifier (Experiment 1: on the top left, Experiment 2: on the shelf), or a color modifier (the black lamp). In Experiment 1 only, the target was located faster when the verbal instruction included either modifier, and there was an overall benefit of color modifiers in a combined analysis for scenes and conditions common to both experiments. The results suggest that violations of the maxim of quantity can facilitate search when the violations include task-relevant information that either augments the target template or constrains the search space, and when at least one modifier provides a highly reliable cue. Consistent with Degen et al., (2020), we conclude that listeners benefit from non-contrastive information that improves reference precision, and engage in rational reference comprehension.

Serum cholesterol selectively regulates glucocorticoid sensitivity through activation of JNK

Glucocorticoids (Gc) are potent anti-inflammatory agents with wide clinical application. We have previously shown that increased serum concentration significantly attenuates regulation of a simple Gc-responsive reporter. We now find that glucocorticoid receptor (GR) regulation of some endogenous transactivated but not transrepressed genes is impaired, suggesting template specificity. Serum did not directly affect GR expression, activity or trafficking, implicating GR crosstalk with other signalling pathways. Indeed, a JNK inhibitor completely abolished the serum effect. We identified the Gc modulating serum component as cholesterol. Cholesterol loading mimicked the serum effect, which was readily reversed by JNK inhibition. Chelation of serum cholesterol with methyl-β-cyclodextrin or inhibition of cellular cholesterol synthesis with simvastatin potentiated the Gc response. To explore the effectin vivowe usedApoE−/−mice, a model of hypercholesterolaemia. Consistent with ourin vitrostudies, we find no impact of elevated cholesterol on the expression of GR, or on the hypothalamic–pituitary–adrenal axis, measured by dexamethasone suppression test. Instead we find selective Gc resistance on some hepatic target genes inApoE−/−mice. Therefore, we have discovered an unexpected role for cholesterol as a selective modulator of Gc actionin vivo. Taken together these findings reveal a new environmental constraint on Gc action with relevance to both inflammation and cancer.

Two Distantly Homologous DnaG Primases from Thermoanaerobacter tengcongensis Exhibit Distinct Initiation Specificities and Priming Activities

ABSTRACT Primase, encoded by dnaG in bacteria, is a specialized DNA-dependent RNA polymerase that synthesizes RNA primers de novo for elongation by DNA polymerase. Genome sequence analysis has revealed two distantly related dnaG genes, TtdnaG and TtdnaG 2, in the thermophilic bacterium Thermoanaerobacter tengcongensis. Both TtDnaG (600 amino acids) and TtDnaG2 (358 amino acids) exhibit primase activities in vitro at a wide range of temperatures. Interestingly, the template recognition specificities of these two primases are quite distinctive. When trinucleotide-specific templates were tested, TtDnaG initiated RNA primer synthesis efficiently only on templates containing the trinucleotide 5′-CCC-3′, not on the other 63 possible trinucleotides. When the 5′-CCC-3′ sequence was flanked by additional cytosines or guanines, the initiation efficiency of TtDnaG increased remarkably. Significantly, TtDnaG could specifically and efficiently initiate RNA primer synthesis on a limited set of tetranucleotides composed entirely of cytosines and guanines, indicating that TtDnaG initiated RNA primer synthesis more preferably on GC-containing tetranucleotides. In contrast, it seemed that TtDnaG2 had no specific initiation nucleotides, as it could efficiently initiate RNA primer synthesis on all templates tested. The DNA binding affinity of TtDnaG2 was usually 10-fold higher than that of TtDnaG, which might correlate with its high activity but low template specificity. These distinct priming activities and specificities of TtDnaG and TtDnaG2 might shed new light on the diversity in the structure and function of the primases.

Authentic Replication and Recombination of Tomato Bushy Stunt Virus RNA in a Cell-Free Extract from Yeast

ABSTRACT To study the replication of Tomato bushy stunt virus (TBSV), a small tombusvirus of plants, we have developed a cell-free system based on a Saccharomyces cerevisiae extract. The cell-free system was capable of performing a complete replication cycle on added plus-stranded TBSV replicon RNA (repRNA) that led to the production of ∼30-fold-more plus-stranded progeny RNAs than the minus-stranded replication intermediate. The cell-free system also replicated the full-length TBSV genomic RNA, which resulted in production of subgenomic RNAs as well. The cell-free system showed high template specificity, since a mutated repRNA, minus-stranded repRNA, or a heterologous viral RNA could not be used as templates by the tombusvirus replicase. Similar to the in vivo situation, replication of the TBSV replicon RNA took place in a membraneous fraction, in which the viral replicase-RNA complex was RNase and protease resistant but sensitive to detergents. In addition to faithfully replicating the TBSV replicon RNA, the cell-free system was also capable of generating TBSV RNA recombinants with high efficiency. Altogether, tombusvirus replicase in the cell-free system showed features remarkably similar to those of the in vivo replicase, including carrying out a complete cycle of replication, high template specificity, and the ability to recombine efficiently.