Association of short-term exposure to ambient fine particulate matter and ozone with outpatient visits for anxiety disorders: A hospital-based case-crossover study in South China.

BACKGROUND: The short-term adverse effects of ambient fine particulate matter (PM2.5) and ozone (O3) on anxiety disorders (ADs) remained inconclusive. METHODS: We applied an individual-level time-stratified case-crossover study, which including 126,112 outpatient visits for ADs during 2019-2021 in Guangdong province, China, to investigate the association of short-term exposure to PM2.5 and O3 with outpatient visits for ADs, and estimate excess outpatient visits in South China. Daily residential air pollutant exposure assessments were performed by extracting grid data (spatial resolution: 1 km × 1 km) from validated datasets. We employed the conditional logistic regression model to quantify the associations and excess outpatient visits. RESULTS: The results of the single-pollutant models showed that each 10 µg/m3 increase of PM2.5 and O3 exposures was significantly associated with a 3.14 % (95 % confidence interval: 2.47 %, 3.81 %) and 0.88 % (0.49 %, 1.26 %) increase in odds of outpatient visits for ADs, respectively. These associations remained robust in 2-pollutant models. The proportion of outpatient visits attributable to PM2.5 and O3 exposures was up to 7.20 % and 8.93 %, respectively. Older adults appeared to be more susceptible to PM2.5 exposure, especially in cool season, and subjects with recurrent outpatient visits were more susceptible to O3 exposure. LIMITATION: As our study subjects were from one single hospital in China, it should be cautious when generalizing our findings to other regions. CONCLUSION: Short-term exposure to ambient PM2.5 and O3 was significantly associated with a higher odds of outpatient visits for ADs, which can contribute to considerable excess outpatient visits.

Association between central obesity and semen quality: A cross-sectional study in 4513 Chinese sperm donation volunteers.

BACKGROUND: General obesity classified by body mass index has been linked to a reduction in semen quality; however, evidence on the adverse effect of central obesity on semen quality remains limited. OBJECTIVES: To investigate the association between central obesity and semen quality. MATERIALS AND METHODS: We conducted a cross-sectional study of 4513 sperm donation volunteers in Guangdong Provincial Human Sperm Bank during 2018-2021. Three central obesity indicators, including waist circumference, waist-to-hip ratio, and waist-to-height ratio, were measured using a multi-frequency bioelectrical impedance analysis for each subject. Semen analysis was conducted according to the World Health Organization laboratory manual for the examination and processing of human semen 5th edition. Linear regression models and unconditional logistic regression models were used to quantify the association between central obesity and semen parameters. RESULTS: With adjustment for age, race, education level, marital status, fertility status, occupation, year of semen collection, abstinence period, ambient temperature, and relative humidity, central obesity defined as waist circumference ≥90 cm, waist-to-hip ratio ≥0.9, or waist-to-height ratio ≥0.5 was significantly associated with a 0.27 (95% confidence interval: 0.15, 0.38) mL, 14.47 (3.60, 25.34) × 106 , 7.06 (0.46, 13.76) × 106 , and 6.80 (0.42, 13.18) × 106 reduction in semen volume, total sperm number, total motile sperm number, and total progressive motile sperm number, respectively, and a 53% (10%, 112%) increase in odds of below the World Health Organization 2010 reference value for semen volume. These associations did not significantly vary across age. Similar results were observed for central obesity defined using each of the three indicators, except that subjects with a waist circumference ≥90 cm had a slightly higher total motility (estimated change: 1.30%; 95% confidence interval: 0.27%, 2.34%) and progressive motility (estimated change: 1.27%; 95% confidence interval: 0.23%, 2.31%). DISCUSSION AND CONCLUSION: We found that central obesity was significantly associated with a reduction in semen volume, total sperm number, total motile sperm number, and total progressive motile sperm number. Future studies are warranted to confirm our results in other regions and populations.

Long-term exposure to ambient fine particulate matter-bound polycyclic aromatic hydrocarbons and cancer mortality: A difference-in-differences approach.

The association of ambient fine particulate matter (PM2.5) exposure with cancer mortality was controversial, which may ascribe to the difference in PM2.5 constituents. Polycyclic aromatic hydrocarbons (PAHs) are carcinogenic constituents in PM2.5, which are suspected to account for PM2.5-induced cancer mortality but are yet to be investigated. We aimed to assess the association between long-term exposure to PM2.5-bound PAHs and cancer mortality and estimate the attributable mortality. A difference-in-differences approach was used to investigate the causal effect of long-term exposure to PM2.5-bound PAHs on cancer mortality. We divided Jiangsu province, China into 53 spatial units and summarized the annual number of cancer deaths in each spatial unit during 2016-2020. Annual population-weighted exposure to PM2.5-bound PAHs of each spatial unit was assessed by an inverse distance weighting method. The association between PM2.5-bound PAHs exposures and cancer mortality was evaluated by controlling spatial differences, temporal trends, PM2.5 mass exposures, temperatures, and socioeconomic status. Records of 793,269 cancer deaths were identified among 84.7 million population. Each ln-unit increase of exposure to total benzo[a]pyrene equivalents (∑BaPeq), total carcinogenic PAHs (∑PAH7c), and total PAHs (∑PAHs) was significantly associated with a 3.21%, 3.48%, and 2.64% increased risk of cancer mortality, respectively; the risk increased monotonically at low-level exposures but attenuated or flattened afterward (all p for nonlinearity <0.05). Similar exposure-response associations were identified for specific PAHs except that the associations for both fluoranthene and benzo[a]anthracene were linear. We estimated that exposure to ∑BaPeq, ∑PAH7c, and ∑PAHs contributed to 5.73%, 8.73%, and 7.33% of cancer deaths, respectively. In conclusion, long-term exposure to PM2.5-bound PAHs was associated with an increased risk of cancer mortality and contributed to substantial cancer deaths. Our findings highlight the importance to prevent deaths from cancer by reducing PM2.5-bound PAHs exposures and the necessity to take into consideration specific constituents in particulate pollution management in future.

Long-term exposure to fine particulate matter and site-specific cancer mortality: A difference-in-differences analysis in Jiangsu province, China.

BACKGROUND: Accumulating studies have reported that chronic exposure to ambient fine particulate matter (PM2.5) can lead to adverse effects on lung cancer mortality; however, such chronic effects are less clear for mortality from other site-specific cancers. OBJECTIVE: To explore the causal effect of long-term PM2.5 exposure on mortality from all-site and a variety of site-specific cancers in Jiangsu province, China during 2015-2020 using a difference-in-differences analysis. METHODS: For each of 53 county-based spatial units in Jiangsu province, we calculated annual death counts for all-site cancer and 23 site-specific cancers. Using a validated high-resolution PM2.5 grid dataset, long-term PM2.5 exposure of a spatial unit within a given year was evaluated as the average of population-weighted annual concentrations during recent 10 years. Conditional Poisson regression models were employed to evaluate exposure-response associations adjusting for spatial and temporal variables, seasonal temperatures, relative humidity, and gross domestic product (GDP). RESULTS: During the study period, we identified 947,337 adult cancer deaths in Jiangsu province. Each 1 µg/m3 increment in PM2.5 exposure was significantly associated with a 2.7% increase in the risk of all-site cancer mortality. PM2.5-mortality associations were also observed in cancer of lip, oral cavity and pharynx, stomach, colorectum, pancreas, lung, bone and joints, ovary, prostate, and lymphoma (all adjusted P < 0.05), with the relative risks ranging from 1.028 (95% confidence interval [CI]: 1.011, 1.046) for stomach cancer to 1.201 (95% CI: 1.120, 1.308) for bone and joints cancers. Exposure-response curves showed that these associations were close to linearity, though most of them had increasing slopes at high exposure levels. Overall, women and subjects in low GDP regions were more vulnerable to PM2.5 exposures. CONCLUSIONS: Long-term exposure to ambient PM2.5 contributes to a higher risk of mortality from multiple site-specific cancers.

Differential roles of the fish chitinous membrane in gut barrier immunity and digestive compartments.

The chitin-based peritrophic matrix (PM) is a structure critical for both gut immunity and digestion in invertebrates. PM was traditionally considered lost in all vertebrates, but a PM-like chitinous membrane (CM) has recently been discovered in fishes, which may increase the knowledge on vertebrate gut physiology and structural evolution. Here, we show that in zebrafish, the CM affects ingestion behavior, microbial homeostasis, epithelial renewal, digestion, growth, and longevity. Young mutant fish without CM appear healthy and are able to complete their life cycle normally, but with increasing age they develop gut inflammation, resulting in gut atrophy. Unlike mammals, zebrafish have no visible gel-forming mucin layers to protect their gut epithelia, but at least in young fish, the CM is not a prerequisite for the antibacterial gut immunity. These findings provide new insights into the role of the CM in fish prosperity and its eventual loss in tetrapods. These findings may also help to improve fish health and conservation, as well as to advance the understanding of vertebrate gut physiology and human intestinal diseases.

Association between ambient temperature and semen quality among sperm donation volunteers in South China.

BACKGROUND: Potential adverse effects of non-optimum temperatures on human semen quality have drawn much concern worldwide; however, the exposure-response relationship remains less understood. OBJECTIVES: To quantitatively assess the association between exposure to ambient temperature and semen quality in South China, and to identify potential critical exposure windows. METHODS: We conducted a longitudinal study to investigate 11,050 volunteers who lived in Guangdong province, China and intended to donate sperm in the Guangdong provincial human sperm bank during 2016-2021. Exposure to ambient temperature during 0-90 days before semen collection was assessed by extracting daily temperatures from a validated grid dataset at each subject's residential address. Linear mixed models and linear regression models were used to perform exposure-response analyses. RESULTS: During the study period, the 11,050 subjects underwent 44,564 semen analyses. Each 5 °C increase of lag 0-90 day exposure to ambient temperature was approximately linearly associated with a 3.11 (95 % confidence interval [CI]: 2.08, 4.14) × 106/ml, 9.31 (4.83, 13.80) × 106, 1.27 % (0.91 %, 1.62 %), 8.20 (5.33, 11.08) × 106, 1.37 % (1.01 %, 1.74 %), 8.29 (5.52, 11.06) × 106, 0.67 % (0.28 %, 1.05 %), and 4.50 (2.20, 6.80) × 106 reduction in sperm concentration, total sperm number, total motility, total motile sperm number, progressive motility, total progressive sperm number, normal forms, and total normal form sperm number, respectively (all p < 0.001), which was not significantly modified by age (all p for effect modification > 0.05). We identified a critical exposure period of 10-14 days before semen collection for sperm motility, and 70-90 days before semen collection for sperm count and morphology. CONCLUSIONS: Our study provides consistent evidence that higher ambient temperature was significantly associated with a reduction in semen quality in South China. The findings highlight the needs to reduce high temperature exposures during 3 months before ejaculation to maintain better semen quality.

Asthma mortality attributable to ambient temperatures: A case-crossover study in China.

BACKGROUND: Whether ambient temperature exposure contributes to death from asthma remains unknown to date. We therefore conducted a case-crossover study in China to quantitatively evaluate the association and burden of ambient temperature exposure on asthma mortality. METHODS: Using data from the National Mortality Surveillance System in China, we conducted a time-stratified case-crossover study of 15 888 individuals who lived in Hubei and Jiangsu province, China and died from asthma as the underlying cause in 2015-2019. Individual-level exposures to air temperature and apparent temperature on the date of death and 21 days prior were assessed based on each subject's residential address. Distributed lag nonlinear models based on conditional logistic regression were used to quantify exposure-response associations and calculate fraction and number of deaths attributable to non-optimum ambient temperatures. RESULTS: We observed a reverse J-shaped association between air temperature and risk of asthma mortality, with a minimum mortality temperature of 21.3 °C. Non-optimum ambient temperature is responsible for substantial excess mortality from asthma. In total, 26.3% of asthma mortality were attributable to non-optimum temperatures, with moderate cold, moderate hot, extreme cold and extreme hot responsible for 21.7%, 2.4%, 2.1% and 0.9% of asthma mortality, respectively. The total attributable fraction and number was significantly higher among adults aged less than 80 years in hot temperature. CONCLUSIONS: Exposure to non-optimum ambient temperature, especially moderate cold temperature, was responsible for substantial excess mortality from asthma. These findings have important implications for planning of public-health interventions to minimize the adverse respiratory damage from non-optimum ambient temperature.

Association between short-term exposure to ambient air pollution and dementia mortality in Chinese adults.

BACKGROUND: Short-term exposure to ambient air pollution has been linked to an increased risk of mortality from a variety of causes, but its effects on mortality from dementia remain largely unknown. OBJECTIVES: To investigate the association between short-term exposure to ambient air pollution and dementia mortality, and quantitatively assess the excess mortality. METHODS: In this time-stratified case-crossover study, 47,108 dementia deaths were identified in Jiangsu province, China during 2015-2019. Exposure to particulate matter with an aerodynamic diameter ≤ 2.5 µm (PM2.5), PM10, sulfur dioxide (SO2), nitrogen dioxide (NO2), carbon monoxide (CO), and ozone (O3) was assessed by extracting daily concentrations from a validated grid dataset based on each subject's residential address. Conditional logistic regression models were applied for exposure-response analyses. RESULTS: There were 47,108 case days and 159,852 control days during the study period. Each 10 µg/m3 increase of lag 04-day exposure to PM2.5, PM10, and NO2 was significantly associated with a 1.43 % (95 % CI: 0.77, 2.09 %), 1.06 % (0.59, 1.54 %), and 2.80 % (1.51, 4.10 %) increase in odds of dementia mortality, corresponding to an excess mortality of 4.87 %, 5.50 %, and 6.43 %, respectively. We estimated that reducing ambient air pollutant exposures to the WHO air quality guidelines would avoid up to 4.17 % of the dementia deaths, while the ambient air quality standards in China would only help avoid up to 0.39 %. CONCLUSIONS: This study provides consistent evidence that short-term exposure to PM2.5, PM10, and NO2 is associated with increased odds of dementia mortality, which can be translated to a considerable excess mortality. Our findings highlight a potential approach to prevent deaths from dementia by reducing individual exposures to ambient air pollution, especially in areas with high levels of ambient air pollution.

Association of short-term exposure to ambient air pollution with mortality from ischemic and hemorrhagic stroke.

BACKGROUND: Short-term exposure to ambient air pollution has been linked to increased risk of stroke mortality, but its adverse effects on mortality from specific types of stroke including ischemic stroke and hemorrhagic stroke remain poorly understood. METHODS: Using the China National Mortality Surveillance System, we conducted a time-stratified case-crossover study among 412,567 stroke deaths in Jiangsu province, China during 2015-2019. Residential daily PM2.5 , PM10 , SO2 , NO2 , CO, and O3 exposure concentrations were extracted from the ChinaHighAirPollutants dataset for each subject. Conditional logistic regression models were performed to conduct exposure-response analyses. RESULTS: Each 10 µg/m3 increase of PM2.5 , PM10 , SO2 , NO2 , CO, and O3 was respectively associated with a 1.44%, 0.93%, 5.55%, 2.90%, 0.148%, and 0.54% increase in odds of mortality from ischemic stroke, which was significantly stronger than that from hemorrhagic stroke (percent change in odds: 0.74%, 0.51%, 3.11%, 1.15%, 0.090%, and 0.10%). The excess fraction of ischemic stroke mortality associated with PM2.5 , PM10 , SO2 , NO2 , CO, and O3 exposure was 6.90%, 6.48%, 8.21%, 8.61%, 9.67%, and 4.76%, respectively, which was also significantly higher than that of hemorrhagic stroke mortality (excess fraction: 3.49%, 3.48%, 4.69%, 3.48%, 5.86%, and 0.88%). These differences in adverse effects generally remained across sex, age, and season. CONCLUSIONS: Short-term exposure to ambient air pollution was significantly associated with increased risk of both ischemic and hemorrhagic stroke mortality and posed considerable excess mortality. Our results suggest that air pollution exposure may lead to substantially greater adverse effects on mortality from ischemic stroke than that from hemorrhagic stroke.

Association of short-term exposure to air pollution with recurrent ischemic cerebrovascular events in older adults.

The acute effects of ambient air pollution on recurrence of ischemic cerebrovascular events (ICEs) remains largely unknown. We therefore conducted a time-stratified case-crossover study of 43,896 patients who were 60 years or older and were admitted to hospital for recurrent ICEs including ischemic stroke and transient ischemic attack in Guangzhou, China during 2016-2019. Based on each patient's home address and pollutant data from its neighboring air quality monitoring stations, we used an inverse distance weighting method to assess exposures to particulate matter with an aerodynamic diameter ≤2.5 µm (PM2.5), particulate matter with an aerodynamic diameter ≤10 µm (PM10), sulfur dioxide (SO2), nitrogen dioxide (NO2), carbon monoxide (CO) and ozone (O3). Conditional logistic regression models were used to quantify exposure-response associations. During the study period, there were 43,896 case days and 149,131 control days. In single-pollutant models, each 10 µg/m3 increase in exposure to PM10, NO2 and CO (mean exposure on date of admission and 1 day prior) was significantly associated with a 0.74% (95% confidence interval [CI]: 0.13-1.36%), 2.15% (1.38-2.93%) and 0.14% (0.07-0.21%) increase in odds of hospital admissions for recurrent ICEs, respectively, and no significant departures from linearity were detected. The association for NO2 exposure remained consistent in 2-pollutant models, while the associations for PM10 and CO disappeared or changed materially with adjustment for other pollutants. Stronger association for NO2 exposure was observed in cool season than that in warm season. We found that short-term exposure to ambient air pollutants, especially NO2, was associated with increased risk of hospital admissions for recurrent ICEs in older adults.

Association of malignant neoplasms with semen quality in Guangdong province, China: A propensity score matching analysis.

BACKGROUND: Previous studies have reported lower semen quality in malignant neoplasm patients before antineoplastic treatments, but the adverse effects of malignant neoplasms on semen quality have rarely been quantitatively evaluated. In addition, due to the lack of a comparable control group and limited types of studied malignant neoplasms, the results remain inconsistent and inconclusive. OBJECTIVES: To quantitatively evaluate the potential adverse effects of specific malignant neoplasms on semen quality. MATERIALS AND METHODS: We conducted a cross-sectional study to investigate 445 malignant neoplasm patients undergoing sperm cryopreservation for fertility preservation in Guangdong province, China during 2016-2019. A propensity score matching method was used to select a comparable control group from 9170 sperm donation volunteers. Each subject was analyzed for semen quality. Multivariate linear regression models were employed to assess the association between malignant neoplasm and semen quality. RESULTS: Using the propensity score matching method, 413 (92.8%) malignant neoplasm patients were successfully matched with 798 sperm donation volunteers. Overall, malignant neoplasms were significantly associated with a 0.3 ml, 17.1 × 106 /ml, 67.6 × 106 , 9.8%, 10.2%, and 6.4% reduction in semen volume, sperm concentration, total sperm number, total motility, progressive motility, and normal forms, respectively. Malignant neoplasm of testis, nasopharynx and digestive organs, Hodgkin lymphoma, non-Hodgkin lymphoma, and leukemia were significantly associated with a reduction in sperm motility and normal forms, while malignant neoplasm of testis, Hodgkin lymphoma, and leukemia were also significantly associated with reduced sperm concentration and/or total sperm number. The reduction in sperm concentration and total sperm number associated with malignant neoplasms was significantly greater in subjects < 30 years. DISCUSSION AND CONCLUSION: We found that malignant neoplasms were significantly associated with a reduction in semen quality, which varied across the type of malignant neoplasms. Our results highlight the needs to examine semen quality for young malignant neoplasm patients, especially those who are expected to conceive.

Ambient air pollution and hospitalization for chronic obstructive pulmonary disease: Benefits from Three-Year Action Plan.

BACKGROUND: Chronic obstructive pulmonary disease (COPD) hospitalization has been linked with ambient air pollution. However, the evidence on respiratory health benefits from air pollution control policy in China is limited. OBJECTIVE: To investigate benefits from the Three-Year Action Plan to Win the Battle for a Blue Sky (TYAP) for tackling COPD hospitalization due to ambient air pollution. METHODS: We conducted a time-stratified case-crossover study of 138,015 COPD hospitalizations aged ≥ 60 years in Guangdong province, China during 2016-2019 to investigate respiratory health benefits from TYAP. Inverse distance weighting method was used to assess daily individual-level exposures to ambient air pollutants including particulate matter with an aerodynamic diameter ≤ 2.5 µm (PM2.5), particulate matter with an aerodynamic diameter ≤ 10 µm (PM10), sulfur dioxide (SO2), nitrogen dioxide (NO2), carbon monoxide (CO), and ozone (O3). Conditional logistic regression model was applied to analyze the associations between ambient air pollutants and COPD hospitalization. RESULTS: TYAP can modify the associations. Each 10 µg/m3 increase of exposure to PM2.5, PM10, and NO2 and 1 mg/m3 increase of exposure to CO were significantly associated with 2.5%, 2.0%, 3.0%, and 14.4% increase in odds of COPD hospitalization before TYAP, respectively; while 1.0%, 0.9%, 1.5%, and 5.8% increase in odds during TYAP. We found prominent declines in health burden of COPD hospitalizations due to air pollution among the elderly after TYAP implication when compared with that before TYAP. CONCLUSION: Reduced levels of ambient air pollutants by TYAP can effectively lower the risk for COPD hospitalization among the elderly, which provides evidence on the respiratory health benefits from consistent and effective air pollution control policy.

Two Amphioxus ApeC-Containing Proteins Bind to Microbes and Inhibit the TRAF6 Pathway.

The apextrin C-terminal (ApeC) domain is a class of newly discovered protein domains with an origin dating back to prokaryotes. ApeC-containing proteins (ACPs) have been found in various marine and aquatic invertebrates, but their functions and the underlying mechanisms are largely unknown. Early studies suggested that amphioxus ACP1 and ACP2 bind to bacterial cell walls and have a role in immunity. Here we identified another two amphioxus ACPs (ACP3 and ACP5), which belong to the same phylogenetic clade with ACP1/2, but show distinct expression patterns and sequence divergence (40-50% sequence identities). Both ACP3 and ACP5 were mainly expressed in the intestine and hepatic cecum, and could be up-regulated after bacterial challenge. Both prokaryotic-expressed recombinant ACP3 and ACP5 could bind with several species of bacteria and yeasts, showing agglutinating activity but no microbicidal activity. ELISA assays suggested that their ApeC domains could interact with peptidoglycan (PGN), but not with lipoteichoic acid (LTA), lipopolysaccharides (LPS) and zymosan A. Furthermore, they can only bind to Lys-type PGN from Staphylococcus aureus, but not to DAP-type PGN from Bacillus subtilis and not to moieties of PGN such as MDPs, NAMs and NAGs. This recognition spectrum is different from that of ACP1/2. We also found that when expressed in mammalian cells, ACP3 could interact with TRAF6 via a conserved non-ApeC region, which inhibited the ubiquitination of TRAF6 and hence suppressed downstream NF-κB activation. This work helped define a novel subfamily of ACPs, which have conserved structures, and have related yet diversified molecular functions. Its members have dual roles, with ApeC as a lectin and a conserved unknown region as a signal transduction regulator. These findings expand our understanding of the ACP functions and may guide future research on the role of ACPs in different animal clades.

Association of exposure to residential greenness with semen quality: A retrospective longitudinal study of sperm donation volunteers in Guangdong province, China.

BACKGROUND: Exposure to residential greenness has been associated with benefits on certain reproductive health outcomes. However, its potential benefits on semen quality remain unknown. OBJECTIVES: To quantitatively explore the association between exposure to residential greenness and semen quality. METHODS: We investigated 9142 sperm donation volunteers who underwent 38,682 semen examinations at Guangdong provincial human sperm bank in China during 2016-2019. Exposure to residential greenness was assessed using mean daily Normalized Difference Vegetation Index (NDVI) at each subject's residential address with a 400 m buffer during 0-90 days before each semen collection. Multivariate linear mixed models and linear regression models were used to assess the association between exposure to residential greenness and semen quality. RESULTS: An interquartile range increase in exposure to residential greenness was significantly associated with a 0.034 (95% confidence interval [CI]: 0.005, 0.063) ml, 4.06 (95% CI: 0.76, 7.37) × 106, and 0.32% (95% CI: 0.22%, 0.41%) increase in semen volume, total sperm number, and normal forms, respectively; similar trends were observed across quartiles of exposure to residential greenness (all p-values for liner trend <0.05 except for semen volume). The association of greenness exposure with semen volume and total sperm number was stronger in subjects 18-25 years, while the association with normal forms was stronger in subjects 26 years or older. The association for sperm concentration, total sperm number, and normal forms were stronger in cool season, while the association for semen volume was stronger in warm season. CONCLUSION: We found that exposure to residential greenness was significantly associated with higher semen quality. Further studies are warranted to determine the causality of the association and its underlying mechanisms.

The family of amphioxus chitin synthases offers insight into the evolution of chitin formation in chordates.

Chitin is a very important and widely-used biopolymer in fungi and lower metazoans, but mysteriously disappears in mammals. Recent studies reveal that at least lower vertebrates have chitin synthases (CS) and use them to synthesize endogenous chitin. Amphioxus, a basal chordate, therefore becomes critical to understand the evolution of CS, as it occupies the transitional position from invertebrates to vertebrates, and is considered as a good proxy to the chordate ancestor. Here, by exploiting multiple genome assemblies, high-depth RNA-seq data and synteny relations, we identify 11-12 CS genes for each amphioxus species. It represents the largest CS gene pool ever found in eukaryotes so far. As comparison, most metazoans have one or two CSs. Amphioxus is the only chordate that has both the very ancient type-I CS family and the more broadly distributed type-II CS family. Specifically, amphioxus has only one type-II CS but 10-11 type-I CSs, which means that amphioxus is the only metazoan with a greatly expanded type-I CS family. Further analysis suggests that the chordate ancestor have at least one type-II CS and an expanded of type-I CS family. We hypothesize that: these ancient CSs are mostly retained in amphioxus; but the whole type-I CS family was lost in urochordates and vertebrates; the type-II CS was later duplicated into two lineages in vertebrates and followed by stochastic losses, till all type-II CSs were eventually lost in birds and mammals. Finally, our expression profiling and preliminary gene knockout analysis suggest that amphioxus CSs could have highly diverse but mildly overlapping functions in various tissues and organs. Taken together, these findings not only provide insights into the evolution of chordate CSs, lay a foundation for further functional study of the chordate CSs. After all, it is mysterious that our chordate ancestor needed so many isoenzymes for chitin formation.

Aquivion-Carbon Composites with Tunable Amphiphilicity for Pickering Interfacial Catalysis.

A key demand in biomass conversion is how to achieve high reactivity with immiscible reagents with the use of neither cosolvents nor additives. Pickering interfacial catalysis encompassing the design of amphiphilic catalysts behaving concomitantly as emulsifiers offers an elegant solution. In this study, we prepared a systematic series of amphiphilic Aquivion-carbon composites by the hydrothermal carbonization of guar gum with Aquivion perfluorosulfonic superacid. By tuning the Aquivion-carbon composition, materials with tunable hydrophilic-lipophilic properties could be prepared, showing high versatility for conducting biphasic reactions without stirring. In particular, an optimal formulation based on 5:1 Aquivion-carbon could be developed, showing high activity in the transesterification reaction of glyceryl trioleate with methanol at 100 °C with good reusability due to the genesis of stable Pickering emulsions.

Aquivion Perfluorosulfonic Superacid as an Efficient Pickering Interfacial Catalyst for the Hydrolysis of Triglycerides.

Rational design of the surface properties of heterogeneous catalysts can boost the interfacial activity in biphasic reactions through the generation of Pickering emulsions. This concept, termed Pickering interfacial catalysis (PIC), has shown promising credentials in acid-catalyzed transesterification, ester hydrolysis, acetalization, etherification, and alkylation reactions. PIC has now been applied to the efficient, solvent-free hydrolysis of the triglyceride glyceryl trilaurate to lauric acid, catalyzed by Aquivion perfluorosulfonic superacid at mild conditions (100 °C and ambient pressure).

Dynamics of Pickering Emulsions in the Presence of an Interfacial Reaction: A Simulation Study.

Pickering emulsions combining surface-active and catalytic properties offer a promising platform for conducting interfacial reactions between immiscible reagents. Despite the significant progress in the design of Pickering interfacial catalysts for a broad panel of reactions, the dynamics of Pickering emulsions under reaction conditions is still poorly understood. Herein, using benzene hydroxylation with aqueous H2O2 as a model system, we explored the dynamics of benzene/water Pickering emulsions during reaction by dissipative particle dynamics. Our study points out that the surface wettability of the silica nanoparticles is affected to a higher extent by the degree of polymer grafting rather than an increase of the chain length of hydrophobic polymer moieties. A remarkable decline of the oil-in-water (O/W) interfacial tension was observed when increasing the yield of the reaction product (phenol), affecting the emulsion stability. However, phenol did not alter to an important extent the distribution of immiscible reagents around the nanoparticles sitting at the benzene/water interface. A synergistic effect between phenol and silica nanoparticles on the O/W interfacial tension of the biphasic system could be ascertained.

Tunable catalysts for solvent-free biphasic systems: pickering interfacial catalysts over amphiphilic silica nanoparticles.

Stabilization of oil/oil Pickering emulsions using robust and recyclable catalytic amphiphilic silica nanoparticles bearing alkyl and propylsulfonic acid groups allows fast and efficient solvent-free acetalization of immiscible long-chain fatty aldehydes with ethylene glycol.

Pickering Interfacial Catalysts for solvent-free biomass transformation: physicochemical behavior of non-aqueous emulsions.

A key challenge in biomass conversion is how to achieve valuable molecules with optimal reactivity in the presence of immiscible reactants. This issue is usually tackled using either organic solvents or surfactants to promote emulsification, making industrial processes expensive and not environmentally friendly. As an alternative, Pickering emulsions using solid particles with tailored designed surface properties can promote phase contact within intrinsically biphasic systems. Here we show that amphiphilic silica nanoparticles bearing a proper combination of alkyl and strong acidic surface groups can generate stable Pickering emulsions of the glycerol/dodecanol system in the temperature range of 35-130°C. We also show that such particles can perform as Pickering Interfacial Catalysts for the acid-catalyzed etherification of glycerol with dodecanol at 150°C. Our findings shed light on some key parameters governing emulsion stability and catalytic activity of Pickering interfacial catalytic systems. This understanding is critical to pave the way toward technological solutions for biomass upgrading able to promote eco-efficient reactions between immiscible organic reagents with neither use of solvents nor surfactants.