Microplastics impacts in seven flagellate microalgae: Role of size and cell wall.

The toxicity of microplastic particles (MPs) on aquatic environments has been widely reported; however, their effects on protists are still contradictory. For example, it is unclear if cell size and cell wall have a role in shaping the response of flagellates to MPs. In this study, seven marine flagellated microalgae (six Dinoflagellates and one Raphidophyceae) were incubated with 10 mg L-1 MPs (polystyrene plastic micro-spheres, 1 µm diameter) to address the above question by measuring different response variables, i.e., growth, optimal photochemical efficiency (Fv/Fm), chlorophyll-a (Chl-a) content, superoxide dismutase (SOD) activity, and cell morphology. The effect of MPs on growth and Fv/Fm showed species-specificity effects. Maximum and minimum MPs-induced inhibitions were detected in Karenia mikimotoi (76.43%) and Akashiwo sanguinea (10.16%), respectively, while the rest of the species showed intermediate responses. The presence of MPs was associated with an average reduction of Chl-a content in most cases and with a higher superoxide dismutase activity in all cases. Seven species were classified into two groups by the variation of Chl-a under MPs treatment. One group (Prorocentrum minimum and Karenia mikimotoi) showed increased Chl-a, while the other (P. donghaiense, P. micans, Alexandrium tamarense, Akashiwo sanguinea, Heterosigma akashiwo) showed decreased Chl-a content. The MPs-induced growth inhibition was negatively correlated with cell size in the latter group. SEM images further indicated that MPs-induced malformation in the smaller cells (e.g., P. donghaiense and K. mikimotoi) was more severe than the bigger cells (e.g., A. sanguinea and P. micans), probably due to a relatively higher ratio of the cell surface to cell volume in the former. These results implicate that the effect of MPs on marine flagellated microalgae was related to the cell size among most species but not cell wall. Thus plastic pollution may have size-dependent effects on phytoplankton in future scenarios.

Prevalence and related factors of depression and falls among the elderly living in rural communities of Guangzhou.

Few studies have concentrated on the prevalence and related factors of depression and falls among the elderly living in rural communities of Guangzhou. A total of 335 participants aged ≥60 years were recruited by simple random sampling method. A structural equation model was applied to determine interrelationships between depression, falls and other variables. As high as 27.5% and 23.3% participants had reported depressive symptoms and falls, respectively. The path analysis showed the total effect (ß = -0.58) of depression on quality of life (QOL) consisted of a direct effect (ß = -0.51) and an indirect effect (ß = -0.07), which was mediated by family function and number of falls, and the R2 was 0.36. The model fit indices were χ2/df = 1.096, P > 0.05, Root Mean Square Error of Approximation (RMSEA) = 0.017, Tucker-Lewis Index (TLI) = 0.998 and Comparative Fit Index (CFI) = 0.999. Depression and falls were prevalent among the elderly living in rural communities of Guangzhou city. Pay attention to strengthen family function and prevent falls may prevent depression and improve the QOL among the elderly.

A 2-Hydroxyisoquinoline-1,3-Dione Active-Site RNase H Inhibitor Binds in Multiple Modes to HIV-1 Reverse Transcriptase.

The RNase H (RNH) function of HIV-1 reverse transcriptase (RT) plays an essential part in the viral life cycle. We report the characterization of YLC2-155, a 2-hydroxyisoquinoline-1,3-dione (HID)-based active-site RNH inhibitor. YLC2-155 inhibits both polymerase (50% inhibitory concentration [IC50] = 2.6 µM) and RNH functions (IC50 = 0.65 µM) of RT but is more effective against RNH. X-ray crystallography, nuclear magnetic resonance (NMR) analysis, and molecular modeling were used to show that YLC2-155 binds at the RNH-active site in multiple conformations.

ELABELA/APJ Axis Prevents Diabetic Glomerular Endothelial Injury by Regulating AMPK/NLRP3 Pathway.

ELABELA (ELA), a recently discovered peptide, is highly expressed in adult kidneys and the endothelium system. It has been identified as a novel endogenous ligand for the apelin receptor (APJ). This study aims to investigate the role of ELA in diabetic glomerular endothelial pyroptosis and its underlying mechanism. Initially, a significant decrease in ELA mRNA levels was observed in the renal cortex of db/db mice and high glucose-treated glomerular endothelial cells (GECs). It was also found that ELA deficiency in ELA+/- mice significantly accelerated diabetic glomerular injury, as shown by exacerbated glomerular morphological damage, increased serum creatine and blood urea nitrogen, and elevated 24-h urinary albumin excretion. In addition, in vivo overexpression of ELA prevented diabetic glomerular injury, reduced von Willebrand factor expression, restored endothelial marker CD31 expression, and attenuated the production of adhesive molecules such as intercellular adhesion molecule-1 and vascular cell adhesion molecule-1. Furthermore, in vitro studies confirmed that treatment with ELA inhibited GEC injury by regulating the NOD-like receptor protein 3 (NLRP3) inflammasome, as indicated by blocking NLRP3 inflammasome formation, decreasing cleaved Caspase-1 production, and inhibiting interleukin-1ß and interleukin-18 production. Moreover, in vitro experiments demonstrated that the protective effects of ELA in GECs during hyperglycemia were diminished by inhibiting adenosine monophosphate-activated protein kinase (AMPK) using Compound C or by APJ deficiency. Taken together, this study provides the first evidence that ELA treatment could prevent diabetic glomerular endothelial injury, which is partly mediated by the regulation of the AMPK/NLRP3 signaling pathway. Therefore, pharmacologically targeting ELA may serve as a novel therapeutic strategy for diabetic kidney disease.

The responses of harmful dinoflagellate Karenia mikimotoi to simulated ocean acidification at the transcriptional level.

The HAB-forming, toxic dinoflagellate Karenia mikimotoi, previously found to benefit from ocean acidification (OA), was cultivated to investigate its transcriptional response to simulated OA for 30 generations. Batch cultures were grown under two CO2 concentrations, 450 (control) and 1100 (simulated OA) µatm, and physiological parameters [growth, pigments, catalase (CAT), glutathione reductase (GR), and superoxide dismutase (SOD) activity], as well as transcriptomes (obtained via RNA-seq), were compared. Chlorophyll a (Chl a) and carotenoid (Caro) contents, as well as CAT and GR activities, were significantly increased under OA conditions. Transcriptomic analysis revealed 2,490 differentially expressed unigenes in response to OA, which comprised 1.54% of all unigenes. A total of 1,121 unigenes were upregulated, and 1,369 unigenes were downregulated in OA compared to control conditions. The downregulated expression of bicarbonate transporter and carbonic anhydrase genes was a landmark of OA acclimation. Key genes involved in energy metabolism, e.g., photosynthesis, tricarboxylic acid cycle, oxidative phosphorylation, and nitrogen metabolism, were highly upregulated under OA, contributing to increases in the Chl a (55.05%) and Caro (28.37%). The enhanced antioxidant enzyme activities (i.e. CAT, GR) and upregulated genes (i.e. glutathione peroxidase, ascorbate peroxidase, heat shock protein, 20S proteasome, aldehyde dehydrogenase, and apolipoprotein) benefit cells against the potential lower pH stress condition under OA. In addition, the downregulation of four genes associated with motility suggested that the preserved energy could further boost growth. In conclusion, the present study suggests that K. mikimotoi exhibits efficient gene expression regulation for the utilization of energy and resistance to OA-induced stress. Taken together, K. mikimotoi appeared as a tolerant species in response to OA. Thus, more extensive algal blooms that threaten marine organisms are likely in the future. These findings expand current knowledge on the gene expression of HAB-forming species in response to future OA.

Molecular Characterization and Phylogenetic Analysis of the 2019 Dengue Outbreak in Wenzhou, China.

In 2019, a dengue outbreak occurred with 290 confirmed cases in Wenzhou, a coastal city in southeast China. To identify the origin of the dengue virus (DENV) from this outbreak, viral RNA was extracted from four serum samples and sequenced for whole genome analysis. Then, phylogenetic analysis, gene mutation, secondary structure prediction, selection pressure analysis, and recombination analysis were performed. DENV strains Cam-03 and Cam-11 were isolated from patients traveling from Cambodia, while ZJWZ-18 and ZJWZ-62 strains were isolated from local patients without a record of traveling abroad. The whole genome sequence of all four strains was 10,735 nucleotides long. Phylogenetic tree analysis showed that the four strains belonged to genotype 1 of DENV-1, but the local Wenzhou strains and imported strains clustered in different branches. ZJWZ-18 and ZJWZ-62 were closely related to strain MF033254-Singapore-2016, and Cam-03 and Cam-11 were closely related to strain AB608788-China : Taiwan-1994. A comparison of the coding regions between the local strains and the DENV-1 standard strain (EU848545-Hawaii-1944) showed 82 amino acid mutations between the two strains. A total of 55 amino acid mutations were found between the coding regions of the local and imported strains. The overall secondary structure of the 3' UTR of the local strains had changed: apparent changes in the head and tail position were observed when compared to DENV-1 standard strain. Furthermore, selection pressure analysis and recombination detection using the 4 isolates and 41 reference strains showed two credible positive selection sites and eight credible recombination events, which warrant further studies. This study may enhance the understanding of viral replication, infection, evolution, virulence, and pathogenicity of DENV.

Toxic effects of the dinoflagellate Karenia mikimotoi on zebrafish (Danio rerio) larval behavior.

Karenia mikimotoi is a toxic dinoflagellate that forms harmful blooms in coastal waters, threatening aquaculture worldwide. However, we do not know whether K. mikimotoi has a neurotoxic effect on aquatic animal behavior. Thus, this study investigated potential K. mikimotoi neurotoxicity in zebrafish larvae. Cells of K. mikimotoi were collected at the mid-exponential phase from a batch culture to prepare ruptured cell solutions (RCS). At 6 h post-fertilization (hpf), zebrafish embryos were exposed to different RCS concentrations (0, 102, 103, 104, and 2.5 × 104 cells mL-1). After 120 hpf, treated larvae were collected to analyze locomotor behavior; activities of acetylcholinesterase (AChE), superoxide dismutase (SOD), catalase (CAT); and expression of genes related to neurodevelopment. We found that RCS did not affect survival rate, but significantly decreased larval locomotion, as well as their AChE, SOD, and CAT activity. Additionally, the examination of the day-night behavioral experiment revealed RCS decreased locomotion only at night. Zebrafish larvae were also significantly hypoactive in response to light and sound stimulations. Of the neurodevelopment genes, three (th, neurog1, and neurod1) were downregulated, while two (bdnf and manf) were upregulated. Our study suggests that K. mikimotoi neurotoxicity occurs through causing oxidative damage, as well as disorders in the cholinergic system and nervous system development. The results provide new insight that K. mikimotoi in low abundance did not cause significant lethal effect but still exhibited significant neurotoxicity on aquatic animals.

Novel Hepatitis B Virus Capsid-Targeting Antiviral That Aggregates Core Particles and Inhibits Nuclear Entry of Viral Cores.

An estimated 240 million are chronically infected with hepatitis B virus (HBV), which can lead to liver disease, cirrhosis, and hepatocellular carcinoma. Currently, HBV treatment options include only nucleoside reverse transcriptase inhibitors and the immunomodulatory agent interferon alpha, and these treatments are generally not curative. New treatments with novel mechanisms of action, therefore, are highly desired for HBV therapy. The viral core protein (Cp) has gained attention as a possible therapeutic target because of its vital roles in the HBV life cycle. Several classes of capsid assembly effectors (CAEs) have been described in detail, and these compounds all increase capsid assembly rate but inhibit HBV replication by different mechanisms. In this study, we have developed a thermal shift-based screening method for CAE discovery and characterization, filling a much-needed gap in high-throughput screening methods for capsid-targeting molecules. Using this approach followed by cell-based screening, we identified the compound HF9C6 as a CAE with low micromolar potency against HBV replication. HF9C6 caused large multicapsid aggregates when capsids were assembled in vitro and analyzed by transmission electron microscopy. Interestingly, when HBV-expressing cells were treated with HF9C6, Cp was excluded from cell nuclei, suggesting that this compound may inhibit nuclear entry of Cp and capsids. Furthermore, mutational scanning of Cp suggested that HF9C6 binds the known CAE binding pocket, indicating that key Cp-compound interactions within this pocket have a role in determining the CAE mechanism of action.

The Heteroaryldihydropyrimidine Bay 38-7690 Induces Hepatitis B Virus Core Protein Aggregates Associated with Promyelocytic Leukemia Nuclear Bodies in Infected Cells.

Heteroaryldihydropyrimidines (HAPs) are compounds that inhibit hepatitis B virus (HBV) replication by modulating viral capsid assembly. While their biophysical effects on capsid assembly in vitro have been previously studied, the effect of HAP treatment on capsid protein (Cp) in individual HBV-infected cells remains unknown. We report here that the HAP Bay 38-7690 promotes aggregation of recombinant Cp in vitro and causes a time- and dose-dependent decrease of Cp in infected cells, consistent with previously studied HAPs. Interestingly, immunofluorescence analysis showed Cp aggregating in nuclear foci of Bay 38-7690-treated infected cells in a time- and dose-dependent manner. We found these foci to be associated with promyelocytic leukemia (PML) nuclear bodies (NBs), which are structures that affect many cellular functions, including DNA damage response, transcription, apoptosis, and antiviral responses. Cp aggregation is not an artifact of the cell system used, as it is observed in HBV-expressing HepAD38 cells, in HepG2 cells transfected with an HBV-expressing plasmid, and in HepG2-NTCP cells infected with HBV. Use of a Cp overexpression vector without HBV sequences shows that aggregation is independent of viral replication, and use of an HBV-expressing plasmid harboring a HAP resistance mutation in Cp abrogated the aggregation, demonstrating that the effect is due to direct compound-Cp interactions. These studies provide novel insight into the effects of HAP-based treatment at a single-cell level.IMPORTANCE Despite the availability of effective vaccines and treatments, HBV remains a significant global health concern, with more than 240 million individuals chronically infected. Current treatments are highly effective at controlling viral replication and disease progression but rarely cure infections. Therefore, much emphasis is being placed on finding therapeutics with new drug targets, such as viral gene expression, covalently closed circular DNA formation and stability, capsid formation, and host immune modulators, with the ultimate goal of an HBV cure. Understanding the mechanisms by which novel antiviral agents act will be imperative for the development of curative HBV therapies.

Placental antibody transfer efficiency and maternal levels: specific for measles, coxsackievirus A16, enterovirus 71, poliomyelitis I-III and HIV-1 antibodies.

Maternal antibodies transported across the placenta can provide vital immunity against infectious pathogens for infants. We here examine maternal antibody (MA) levels and their association with neonatal antibody levels. Pregnant women of gestational age ≥35 weeks were enrolled at a Guangzhou China hospital and mother-infant paired sera were collected. Measles IgG antibody was detected using ELISA assay, neutralizing antibodies titers against coxsackievirus A16 (CA16), enterovirus 71 (EV71), PV I-III and HIV-1 were performed. 711 mother-infant pairs were enrolled and positive relationships for paired serums were found (r: 0.683-0.918). 81.6%, 87.0%, and 82.3% of mothers, and 87.3%, 72.7%, and 72.2% of newborns were positive for measles, CA16 and EV71 antibodies respectively. The highest Neonatal: maternal ratio (NMR) was found in measles (1.042) and the ratios for the other pathogens ranged from 0.84 to 1.00. Linear regressions showed that log(NMR) decreased by a factor of 0.04-15.43 as log(MA) levels increased. A second analysis restricted to maternal positive measles sera revealed that MA measles of was still inversely associated with NMR. Low NMR was found in high MA HIV + serums among 22 paired sera. MA levels appear to play a role determining transplacental antibody transfer; further study is needed to reveal the mechanism.

The effects of weather conditions on measles incidence in Guangzhou, Southern China.

BACKGROUND: Few studies were conducted to examine the effects of weather conditions on the incidence of measles. METHODS: We used a distributed lag nonlinear model (DLNM) to analyze the relationship between meteorological factors and measles incidence in Guangzhou, China. RESULTS: Nonlinear effects of temperature and relative humidity on measles incidence were observed. The relative risk (RR) for the measles incidence associated with the 75th percentile of mean temperature (27.9 °C) relative to the median of mean temperature (24.7 °C) was 1.00 (0.86,1.16) for lags 0-10 days. The RR for the measles incidence associated with the 25th percentile of relative humidity (64%) relative to the median of relative humidity (73%) was 1.36 (1.01,1.82) for lags 0-30 days. The wet effects and dry effects were larger in females than in males. The wet effects were generally increased with ages. Significantly negative effects of cold spells on measles incidence were observed. CONCLUSION: Both hot and cold temperatures result in decreases in the incidence of measles, and low relative humidity is a risk factor of measles morbidity. An increased number of measles cases might occur before and after a cold spell. Our findings highlight the need to pay more attention to the weather transformation and improve the immunity of susceptible population for measles elimination. Catch-up vaccination campaigns should be initiated among young adults.

The relationship between meteorological factors and mumps incidence in Guangzhou, China, 2005-2012:.

BACKGROUND: Over the past decade, there have been resurgences and large-scale outbreaks of mumps worldwide. Little evidence is available on the relationship between meteorological factors and the incidence of mumps. We aimed to explore the effects of meteorological factors on mumps incidence. METHODS: A Poisson regression model combined with a distributed lag non-linear model (DLNM) was used to evaluate the association between meteorological factors and the mumps incidence in Guangzhou, China, 2005-2012. RESULTS: Nonlinear relationships between meteorological factors, except sunshine hours, and mumps incidence were observed. The relative risks (RRs) of mean temperature, relative humidity and atmospheric pressure were 1.81 (95% confidence interval (CI), 1.41 to 2.32), 1.28 (95% CI, 1.02 to 1.59), and 0.80 (95% CI, 0.67 to 0.95) comparing the 99th percentile to the median of their own, respectively. For wind velocity, the RR was 0.70 (95%CI, 0.54 to 0.91) comparing the 1st percentile to the median. The hot effect and cold effect were larger in females than in males, and the hot effect increased with age. CONCLUSIONS: Mean temperature, relative humidity, wind velocity and atmospheric pressure might be important predictors of the mumps incidence. Tropical cyclone caused a higher increase in mumps cases. Our findings highlight the need to strengthen the awareness of using protective measures during typhoon days and allocating more attention to the susceptible populations during the summer. The two-dose regimen of mumps vaccine should be included in the National Immunization Program schedule, and the catch-up vaccination campaigns should be promoted among adults.

Effectiveness of seasonal influenza vaccine against clinically diagnosed influenza over 2 consecutive seasons in children in Guangzhou, China: a matched case-control study.

Influenza vaccine has to be reformulated each year due to the ever-changing antigenicity of the influenza virus. However, few post-licensure studies of influenza vaccine are available in China. We aimed to measure the effectiveness of seasonal influenza vaccine during 2 consecutive seasons. Among children in Guangzhou aged 6 to 59 mo in 2010-2012, we matched each child with clinically diagnosed influenza to 3 healthy children. Cases with clinically diagnosed influenza were identified from surveillance system. Healthy controls were randomly sampled from the Children's Expanded Programmed Immunization Administrative Computerized System. Conditional logistic regression was used to calculate vaccine effectiveness (VE). A total of 275 matched sets of subjects were included. VE levels against clinically diagnosed influenza for both seasons combined was 47.4% [95% confidence interval (CI), 8.5-69.8%] for full vaccination for children aged 6-35 mo, 33.6% (95% CI, 5.4-53.5%) for any vaccination for children aged 6-59 mo, respectively. VE by time since vaccination for any vaccination was 34.6% (95% CI, 4.7-55.2%) in 0-5 mo, and no protection was observed in 6-11 mo. Annual, full and timely vaccination should be encouraged for children.

Seasonal influenza vaccine effectiveness among children, 2010-2012.

BACKGROUND: The annual differences in the seasonal influenza vaccine and the circulating strains make it necessary to assess influenza vaccine effectiveness (VE) yearly. We assessed the effectiveness of the trivalent inactivated influenza vaccine for the 2010-2011 and 2011-2012 influenza seasons among children in Guangzhou, China. METHODS: We conducted a 1:2 matched case-control study based on date of birth (±7 days), gender, and area of residence. The influenza cases from surveillance sites in Guangzhou were laboratory-confirmed during the 2010-2012 seasons. The controls were randomly selected from children aged 6-59 months in the Children's Expanded Programmed Immunization Administrative Computerized System. The influenza vaccination information for both cases and controls was retrieved from this system. RESULTS: We analyzed the vaccination information for 1255 influenza cases and 2510 matched controls in 2 influenza seasons in Guangzhou, China. We found that the VE for vaccination during the 2010-2011 and 2011-2012 seasons of virus circulation was 73·2% (95% confidence interval (CI), 52·2-85·0%) and 52·9% (95% CI, 42·1-61·7%), respectively. The VE decreased from 68·9% (95% CI, 57·5-77·2%) in the period between January and March to 48·4% (95% CI, 33·8-59·7%) in the period between April and June. CONCLUSIONS: This post-licensing study of VE found moderate protection against influenza for vaccinated children aged 6-59 months. Although the influenza vaccine strains for the 2010-2011 and the 2011-2012 seasons were the same, our study indicated that annual vaccination is recommended even for those who received the vaccine during the previous season.