PNAS nexus最新文献

Humans are remarkably good at understanding spoken language, despite the huge variability of the signal as a function of the talker, the situation, and the environment. This success relies on having access to stable representations based on years of speech input, coupled with the ability to adapt to short-term deviations from these norms, e.g. accented speech or speech altered by ambient noise. In the last two decades, there has been a robust research effort focused on a possible mechanism for adjusting to accented speech. In these studies, listeners typically hear 15 - 20 words in which a speech sound has been altered, creating a short-term deviation from its longer-term representation. After exposure to these items, listeners demonstrate "lexically driven phonetic recalibration"-they alter their categorization of speech sounds, expanding a speech category to take into account the recently heard deviations from their long-term representations. In the current study, we investigate such adjustments by bilingual listeners. French-English bilinguals were first exposed to nonstandard pronunciations of a sound (/s/ or /f/) in one language and tested for recalibration in both languages. Then, the exposure continued with both the original type of mispronunciation in the same language, plus mispronunciations in the other language, in the opposite direction. In a final test, we found simultaneous recalibration in opposite directions for the two languages-listeners shifted their French perception in one direction and their English in the other: Bilinguals can maintain separate adjustments, for the same sounds, when a talker's speech differs across two languages.

It is advantageous for maternally transmitted endosymbionts to skew the sex ratio of their hosts toward females. Some endosymbiotic bacteria, such as Wolbachia, cause their insect hosts to exclusively produce female offspring through male killing (MK) or feminization. In some lepidopteran insects, MK is achieved by affecting the sex-determining process in males, and a unique mechanism of MK and its functional link with feminization have been implicated. However, comparative analysis of these phenotypes is often difficult because they have been analyzed in different host-symbiont systems, and transinfection of Wolbachia across different hosts is often challenging. In this study, we demonstrated the effects of nine Wolbachia strains on the splicing of sex-determining genes in Lepidoptera by fixing the host genetic background using a cell culture system. Cell transinfection assays confirmed that three MK-inducing Wolbachia strains and one feminization-inducing Wolbachia strain increased the female-type splicing products of the core sex-determining genes doublesex, masculinizer, and zinc finger protein 2. Regarding Wolbachia strains that do not induce MK/feminization, three had no effect on these sex-determining genes, whereas two strains induced female-type splicing of masculinizer and doublesex but not zinc finger protein 2. Comparative genomics confirmed that homologs of oscar, the Wolbachia gene responsible for MK in Ostrinia, were encoded by four MK/feminizing Wolbachia strains, but not by five non-MK/nonfeminizing strains. These results support the conserved effects underlying MK and feminization induced by oscar-bearing Wolbachia and suggested other potential mechanisms that Wolbachia might employ to manipulate host sex.

The vertical distribution of ozone (O₃) within the boundary layer (BL) and its ground-level effects have been extensively studied. However, observational limitations in obtaining high-resolution, real-time data on O₃ and its precursors, especially volatile organic compounds (VOCs), have led to a scarcity of research on O₃ formation sensitivity and mechanisms. Online measurements for O₃, nitrogen oxides (NO _x ), and VOCs were made on the mountainside of Mount Tai (∼550 m a.s.l.) in China during the summer of 2022 and were compared with the data from a ground-level site. The Master Chemical Mechanism (V3.3.1) was used to uncover a positive correlation between NO _x and photochemical reaction rates on the mountainside, marking it as a NO _x -limited regime in contrast to the VOC-limited regime identified at surface. On the mountainside, lower NO levels limited hydroxyl radicals (OH) recycling reactions, resulting in earlier O₃ peaks and higher concentrations of hydroperoxy radicals (HO₂) and organic peroxy radicals (RO₂). The arrival of fresh air masses rich in NO accelerated OH radical cycling, enhanced atmospheric oxidization, and significantly impacted surface O₃ concentrations though vertical transport. Moreover, NO _x reduction scenario simulations show that when considering vertical transport, the peak O₃ production rate at the surface is lower due to differences in O₃ formation sensitivity vertically. This study highlights the significant sensitivity of O₃ formation to NO within the BL, underscoring the potential impact of vertical in situ O₃ formation above the ground on surface-level O₃ concentrations through vertical exchange, particularly in cities with mountainous terrain.

The majority of the eukaryotic cell surface is decorated with a layer of membrane-attached polysaccharides and glycoproteins collectively referred to as the glycocalyx. While the formation of a bulky glycocalyx has been associated with the cancer progression, the mechanisms by which the glycocalyx regulates cancer invasiveness are incompletely understood. We address this question by first documenting subtype-specific expression of the major glycocalyx glycoprotein Mucin-1 (MUC1) in breast cancer patient samples and breast cancer cell lines. Strikingly, glycocalyx disruption led to inhibition of 2D motility, loss of 3D invasion, and reduction of clonal scattering in breast cancer cells at the population level. Tracking of 2D cell motility and 3D invasiveness of MUC1-based sorted subpopulations revealed the fastest motility and invasiveness in intermediate MUC1-expressing cells, with glycocalyx disruption abolishing these effects. While differential sensitivity in 2D motility is attributed to a nonmonotonic dependence of focal adhesion size on MUC1 levels, higher MUC1 levels enhance 3D invasiveness via increased traction generation. In contrast to inducing cell rounding on collagen-coated substrates, high MUC1 level promotes cell adhesion and confers resistance to shear flow on substrates coated with the endothelial surface protein E-selectin. Collectively, our findings illustrate how MUC1 drives cancer invasiveness by differentially regulating cell-substrate adhesion in a substrate-dependent manner.

People ubiquitously smile during brief interactions and first encounters, and when posing for photos used for virtual dating, social networking, and professional profiles. Yet not all smiles are the same: subtle individual differences emerge in how people display this nonverbal facial expression. We hypothesized that idiosyncrasies in people's smiles can reveal aspects of their personality and guide the personality judgments made by observers, thus enabling a smiling face to serve as a valuable tool in making more precise inferences about an individual's personality. Study 1 (N = 303) supported the hypothesis that smile variation reveals personality, and identified the facial-muscle activations responsible for this leakage. Study 2 (N = 987) found that observers use the subtle distinctions in smiles to guide their personality judgments, consequently forming slightly more accurate judgments of smiling faces than neutral ones. Smiles thus encode traces of personality traits, which perceivers utilize as valid cues of those traits.

There is an accumulation of evidence that the human gut microbiota plays a role in maintaining health, and that an altered gut microbiota (sometimes called dysbiosis) associates with risk for many noncommunicable diseases. However, the dynamics of disease-linked bacteria in the gut and other body sites remain unclear. If microbiome alterations prove causative in particular diseases, therapeutic intervention may be possible. Furthermore, microbial signature taxa have been established for the diagnosis of some diseases like colon cancer. We identified 163 disease-enriched and 98 disease-depleted gut microbiome signature taxa at species-level resolution (signature species) from 10 meta-analyses of multiple diseases such as colorectal cancer, ulcerative colitis, Crohn's disease, irritable bowel syndrome, pancreatic cancer, and COVID-19 infection. Eight signature species were enriched and nine were depleted across at least half of the diseases studied. Compared with signature species depleted in diseases, a significantly higher proportion of disease-enriched signature species were identified as extra-intestinal (primarily oral) inhabitants, had been reported in bacteremia cases from the literature, and were aerotolerant anaerobes. These findings highlight the potential involvement of oral microbes, bacteremia isolates, and aerotolerant anaerobes in disease-associated gut microbiome alterations, and they have implications for patient care and disease management.

Exceptionally preserved feathers from the Mesozoic era have provided valuable insights into the early evolution of feathers and enabled color reconstruction of extinct dinosaurs, including early birds. Mounting chemical evidence for the two key components of feathers-keratins and melanins-in fossil feathers has demonstrated that exceptional preservation can be traced down to the molecular level. However, the chemical changes that keratin and eumelanin undergo during fossilization are still not fully understood, introducing uncertainty in the identification of these two molecules in fossil feathers. To address this issue, we need to examine their taphonomic process. In this study, we analyzed the structural and chemical composition of fossil feathers from the Jehol Biota and compared them with the structural and chemical changes observed in modern feathers during the process of biodegradation and thermal degradation, as well as the structural and chemical characteristics of a Cenozoic fossil feather. Our results suggest that the taphonomic process of feathers from the Cretaceous Jehol Biota is mainly controlled by the process of thermal degradation. The Cretaceous fossil feathers studied exhibited minimal keratin preservation but retained strong melanin signals, attributed to melanin's higher thermal stability. Low-maturity carbonaceous fossils can indeed preserve biosignals, especially signals from molecules with high resistance to thermal degradation. These findings provide clues about the preservation potential of keratin and melanin, and serve as a reference for searching for those two biomolecules in different geological periods and environments.

Formation of the gluten network depends on glutenin crosslinking via disulfide bonds, and wheat protein disulfide isomerase (wPDI) plays an important role in this process. Here, we identify a substrate gluten protein of wPDI and the mechanism underlying wPDI-promoted glutenin crosslinking. Farinographic, rheologic, and alveographic analysis unambiguously proves that wPDI improves gluten network formation, which is directly observed by 3D reconstruction of the gluten network. Protein analysis and LC-MS/MS reveal that glutenin subunit 1Dx5 is primarily recruited by wPDI to participate in gluten network formation, and its cysteine-containing N-terminal domain (1Dx5-NTD), which harbors three cysteine residues for crosslinking, is purified. 1Dx5-NTD interacts with wPDI in both redox states, possibly folded by reduced wPDI and then catalyzed by oxidized wPDI, as further evidenced by wPDI-promoted self-crosslinking. Consistent with macroscopic observations, our results suggest that wPDI folds 1Dx5-NTD into β-strand structure that favors disulfide bond formation.

Isolation of symptomatic infectious persons can reduce influenza transmission. However, virus shedding that occurs without symptoms will be unaffected by such measures. Identifying effective isolation strategies for influenza requires understanding the interplay between individual virus shedding and symptom presentation. From 2017 to 2020, we conducted a case-ascertained household transmission study using influenza real-time RT-qPCR testing of nasal swabs and daily symptom diary reporting for up to 7 days after enrolment (≤14 days after index onset). We assumed real-time RT-qPCR cycle threshold (Ct) values were indicators of quantitative virus shedding and used symptom diaries to create a score that tracked influenza-like illness (ILI) symptoms (fever, cough, or sore throat). We fit phenomenological nonlinear mixed-effects models stratified by age and vaccination status and estimated two quantities influencing isolation effectiveness: shedding before symptom onset and shedding that might occur once isolation ends. We considered different isolation end points (including 24 h after fever resolution or 5 days after symptom onset) and assumptions about the infectiousness of Ct shedding trajectories. Of the 116 household contacts with ≥2 positive tests for longitudinal analyses, 105 (91%) experienced ≥1 ILI symptom. On average, children <5 years experienced greater peak shedding, longer durations of shedding, and elevated ILI symptom scores compared with other age groups. Most individuals (63/105) shed <10% of their total shed virus before symptom onset, and shedding after isolation varied substantially across individuals, isolation end points, and infectiousness assumptions. Our results can inform strategies to reduce transmission from symptomatic individuals infected with influenza.

Advancing the synergetic control of climate change and environmental crisis is crucial for achieving global sustainable development goals. This study evaluates synergetic governance levels over climate change and four environmental issues at the provincial level in China from 2009 to 2020. Our findings reveal significant progress in China's coordinated efforts to mitigate carbon emissions, reduce air pollutants, and conserve water resources. However, there remains room for improvement in managing solid waste and protecting ecological systems and overall progress in synergetic governance has slowed since 2015. Employing a random forest model, we identify socio-economic factors with great influence on synergetic climate change and environmental governance, such as energy intensity, service sector development, electronic equipment manufacturing, and transportation. Additionally, we reveal nonlinear relationships between some factors and performance of environmental subsystems, including both plateau effects (e.g. output in the smelting of ferrous metals) and U-shaped patterns (e.g. output in the manufacturing of metal products), possibly attributed to constraints in end-of-pipe treatment capacities and complexities in supply chain networks. Furthermore, through hierarchical clustering analysis, we classify provinces into four groups and provide tailored recommendations for policymakers to enhance synergetic governance levels in their respective regions. The framework established in this study also serves as a valuable reference for countries seeking to develop practical and context-specific solutions to mitigate climate and environmental risks.