Detection and elimination of trace d-lactic acid in lignocellulose biorefining chain: Generation, flow, and impact on chiral lactide synthesis.

High chiral purity of lactic acid is a crucial indicator for the synthesis of chiral lactide as the primary intermediate chemical for ring-open polymerization of high molecular weight polylactic acid (PLA). Lignocellulose biomass is the most promising carbohydrate feedstock for commercial production of PLA, but the presence of trace d-lactic acid in the biorefinery chain adversely affects the synthesis and quality of chiral lactide. This study analyzed the fingerprint of trace  d-lactic acid in the biorefinery chain and found that the major source of  d-lactic acid comes from lignocellulose feedstock. The naturally occurring lactic acid bacteria and water-soluble carbohydrates in lignocellulose feedstock provide the necessary conditions for  d-lactic acid generation. Three strategies were proposed to eliminate the generation pathway of  d-lactic acid, including reduction of moisture content, conversion of water-soluble carbohydrates to furan aldehydes in pretreatment, and conversion to  l-lactic acid by inoculating engineered  l-lactic acid bacteria. The natural reduction of lactic acid content in lignocellulose feedstock during storage was observed due to the lactate oxidase-catalyzed oxidation of  l- and  d-lactic acids. This study provided an important support for the production of cellulosic  l-lactic acid with high chiral purity.

Effects of chemical factors on the infectivity of Decapod iridescent virus 1 (DIV1).

The effects of chemical factors on the infectivity of DIV1 have not been fully accessed yet. In order to investigate the stability of DIV1 to strong brine, pH, and other chemical conditions, we conducted a bioassay using clinically healthy Penaeus vannamei individuals. DIV1 inoculum was exposed to various chemical conditions, and the infectivity of DIV1 was determined through intramuscular injection. The results showed that DIV1 lost its infectivity when exposed to strong brine, specifically in a 3 mol/L NaCl solution for a duration of 1 h. Moreover, DIV1 was found to be inactivated within 1 h when subjected to pH levels below 3.1 or above 9.6. Additionally, both Triton X-100 and 1 % formaldehyde demonstrated the ability to inactivate DIV1. These results provide valuable insights into the tolerance of DIV1 towards certain chemical factors, serving as a reference for the establishment of biosecurity measures against DIV1.

Prolonged administration of total glucosides of paeony improves intestinal immune imbalance and epithelial barrier damage in collagen-induced arthritis rats based on metabolomics-network pharmacology integrated analysis.

Rheumatoid arthritis (RA) is a chronic systemic autoimmune disease characterized by synovial inflammation and joint damage with complex pathological mechanisms. In recent years, many studies have shown that the dysregulation of intestinal mucosal immunity and the damage of the epithelial barrier are closely related to the occurrence of RA. Total glucosides of paeony (TGP) have been used clinically for the treatment of RA in China for decades, while the pharmacological mechanism is still uncertain. The purpose of this study was to investigate the regulatory effect and mechanism of TGP on intestinal immunity and epithelial barrier in RA model rats. The results showed that TGP alleviated immune hyperfunction by regulating the ratio of CD3+, CD4+ and CD8+ in different lymphocyte synthesis sites of the small intestine, including Peyer's patches (PPs), intraepithelial lymphocytes (IELs), and lamina propria lymphocytes (LPLs). Specially, TGP first exhibited immunomodulatory effects on sites close to the intestinal lumen (IELs and LPLs), and then on PPs far away from the intestinal lumen as the administration time prolonged. Meanwhile, TGP restores the intestinal epithelial barrier by upregulating the ratio of villi height (V)/crypt depth (C) and expression of tight junction proteins (ZO-1, occludin). Finally, the integrated analysis of metabolomics-network pharmacology was also used to explore the possible regulation mechanism of TGP on the intestinal tract. Metabolomics analysis revealed that TGP reversed the intestinal metabolic profile disturbance in CIA rats, and identified 32 biomarkers and 163 corresponding targets; network pharmacology analysis identified 111 potential targets for TGP to treat RA. By intersecting the results of the two, three key targets such as ADA, PNP and TYR were determined. Pharmacological verification experiments showed that the levels of ADA and PNP in the small intestine of CIA rats were significantly increased, while TGP significantly decreased their ADA and PNP levels. In conclusion, purine metabolism may play an important role in the process of TGP improving RA-induced intestinal immune imbalance and impaired epithelial barrier.

Stability and ecological risk assessment of nickel (Ni) in phytoremediation-derived biochar.

Improper treatment of heavy metal-enriched biomass generated after phytoremediation might cause secondary pollution in soil and water. At present, the pyrolysis process is an effective method for the treatment of phytoremediation residue. In this study, Ni-enriched biomass was prepared using hydroponics method and further pyrolyzed at different temperatures (300-700 °C). At low pyrolysis temperatures (below 500 °C), carbonate precipitation was the main reason of Ni stabilization in biochar. Nevertheless, the formed phosphate and aluminosilicate were important factors for immobilizing Ni in biochar at high pyrolysis temperatures (above 500 °C). Moreover, the oxidizable (F3) and residual (F4) components of Ni in biochar increased with increasing pyrolysis temperature, which indicated that higher pyrolysis temperature could effectively reduce the bioavailability of Ni in biochar. The results of deionized water, acidification, oxidation, and toxic characteristic leaching procedure (TCLP) experiments showed that pyrolysis temperature was the dominant factor for Ni stabilization in biochar. The ecological risk assessments further proved that pyrolyzed Ni-enriched biochar could reduce the environmental toxicity and potential ecological risks of Ni. In the soil simulated experiment, the soil microenvironment gradually promoted the transformation of Ni in BCNiX from bioavailable fraction to stable fraction. Overall, this study would expose more reasonable reference for the long-term storage of phytoremediation residues.

Postharvest Calcium Chloride Treatment Strengthens Cell Wall Structure to Maintain Litchi Fruit Quality.

Litchi (Litchi chinensis Sonn.) fruit deterioration occurs rapidly after harvest and is characterized by pericarp browning, pulp softening, and decay. In this study, we found that calcium chloride (CaCl2) treatment (5 g L-1 CaCl2 solution vacuum infiltration for 5 min) affected the cell wall component contents and cell wall-degrading enzyme activities of litchi fruit during storage at room temperature. CaCl2 treatment significantly increased the contents of Ca2+ and cellulose, while it decreased the water-soluble pectin content, and the activities of polygalacturonase, ß-galactosidase, and cellulase in the litchi pericarp. Meanwhile, the treatment resulted in significantly increased contents of Ca2+, water-soluble pectin, ionic-soluble pectin, covalent-soluble pectin and hemicellulose, and upregulated activities of pectinesterase and ß-galactosidase, while significantly decreasing the activities of polygalacturonase and cellulase in litchi pulp. The above results indicate that CaCl2 treatment strengthened the cell wall structure of litchi fruit. More importantly, the enzymatic browning of the pericarp, softening of the pulp, and disease incidence were delayed. The treatment had a more pronounced effect on the pericarp than on the pulp. We consider CaCl2 treatment to be a safe and effective treatment for maintaining the postharvest quality of litchi fruit.

GA3 Treatment Delays the Deterioration of 'Shixia' Longan during the On-Tree Preservation and Room-Temperature Storage and Up-Regulates Antioxidants.

Gibberellic acids had been proven to improve the fruit quality and storability by delaying deterioration and maintaining the antioxidant system. In this study, the effect of GA3 spraying at different concentrations (10, 20, and 50 mg L-1) on the quality of on-tree preserved 'Shixia' longan was examined. Only 50 mg L-1 GA3 significantly delayed the decline of soluble solids (22.0% higher than the control) and resulted in higher total phenolics content (TPC), total flavonoid content (TFC), and phenylalanine ammonia-lyase activity in pulp at the later stages. The widely targeted metabolome analysis showed that the treatment reprogrammed secondary metabolites and up-regulated many tannins, phenolic acids, and lignans during the on-tree preservation. More importantly, the preharvest 50 mg L-1 GA3 spraying (at 85 and 95 days after flowering) led to significantly delayed pericarp browning and aril breakdown, as well as lower pericarp relative conductivity and mass loss at the later stages of room-temperature storage. The treatment also resulted in higher antioxidants in pulp (vitamin C, phenolics, and reduced glutathione) and pericarp (vitamin C, flavonoids, and phenolics). Therefore, preharvest 50 mg L-1 GA3 spraying is an effective method for maintaining the quality and up-regulating antioxidants of longan fruit during both on-tree preservation and room-temperature storage.

Individual- and group-level sex ratios under local mate competition: consequences of infanticide and reproductive dominance.

Extremely female-biased sex ratios of parasitoid wasps in multiple-foundress groups challenges evolutionary theory which predicts diminishing bias as foundress numbers increase. Recent theory based on foundress cooperation has achieved qualitative rather than quantitative success in explaining bias among parasitoids in the genus Sclerodermus. Here, we develop an explanation, expanding the theory of local mate competition, based on the observation that male production seems dominated by some foundresses within groups. Two sex ratio effects arise from such reproductive dominance: an immediate effect via suppression of male production, and a long-term evolutionary response to reproductive skew. We analyze the outcome of these effects at the individual and group level, the latter being more readily observable. Three model scenarios are analyzed: (1) random killing of developing sons in a group by all foundresses, without reproductive skew, (2) the development of reproductive dominance by some foundresses after sex allocation decisions by all foundresses have been implemented, and (3) reproductive dominance within foundress groups before sex allocation decisions are implemented. The 3 scenarios have subtly different implications for sex ratio evolution, with Models 2 and 3 being novel additions to theory, showing how reproductive dominance can alter the outcome of sex ratio evolution. All models match observations in their outcomes better than other recently proposed theory, but Models 2 and 3 are closest to observations in their underlying assumptions. Further, Model 2 shows that differential offspring mortality after parental investment can influence the primary sex ratio even when random with respect to parental and offspring characters, but targeted at entire clutches. The novel models are solved for both diploid and haplodiploid genetic systems, and confirmed with simulations. Overall, these models provide a feasible explanation for the extremely female-biased sex ratios produced by multi-foundress groups and expand the scope of local mate competition theory to consider reproductive dominance.

Meta-Transcriptomic Analysis Reveals Novel RNA Viruses in Hippocampus erectus.

Lined seahorse, Hippocampus erectus, is an important aquatic animal due to its medicinal and ornamental purposes. However, our understanding of the viral spectrum in H. erectus is still limited. Here, we studied the viruses in H. erectus using meta-transcriptomic sequencing. A total of 213,770,166 reads were generated and assembled de novo into 539 virus-associated contigs. Three novel RNA viruses from the Astroviridae, Paramyxoviridae, and Picornaviridae families were finally identified. In addition, we identified a strain of nervous necrosis virus from H. erectus. In particular, the unhealthy group showed a higher viral diversity and abundance than the normal group. These results revealed the diversity and cross-species transmission of viruses in H. erectus and highlighted the threat of viral infections to H. erectus.

CRISPR/Cas genome editing system and its application in potato.

Potato is the largest non-cereal food crop worldwide and a vital substitute for cereal crops, considering its high yield and great nutritive value. It plays an important role in food security. The CRISPR/Cas (clustered regularly interspaced short palindromic repeats/CRISPR-associated) system has the advantages of easy operation, high efficiency, and low cost, which shows a potential in potato breeding. In this paper, the action mechanism and derivative types of the CRISPR/Cas system and the application of the CRISPR/Cas system in improving the quality and resistance of potatoes, as well as overcoming the self-incompatibility of potatoes, are reviewed in detail. At the same time, the application of the CRISPR/Cas system in the future development of the potato industry was analyzed and prospected.

Dietary fish oil improves autistic behaviors and gut homeostasis by altering the gut microbial composition in a mouse model of fragile X syndrome.

Fragile X syndrome (FXS) is the most common inherited intellectual disability, caused by a lack of the fragile X mental retardation protein (FMRP). Individuals with neurodevelopmental disorders frequently experience gastrointestinal problems that are primarily linked to gut microbial dysbiosis, inflammation, and increased intestinal permeability. Omega-3 polyunsaturated fatty acids (omega-3 PUFAs) are non-pharmacological agents that exert potential therapeutic effects against neurological disorders. However, it is unclear whether omega-3 PUFAs improve autistic behaviors in fragile X syndrome (FXS) by altering the gut microbial composition. Here, we describe gastrointestinal problems in Fmr1 knockout (KO) mice. FMRP deficiency causes intestinal homeostasis dysfunction in mice. Fish oil (FO) as a source of omega-3 PUFAs reduces intestinal inflammation but increases the mRNA and protein levels of TJP3 in the colon of juvenile Fmr1 KO mice. Fecal microbiota transplantation from FO-fed Fmr1 KO mice increased the gut abundance of Akkermansia and Gordonibacter in recipient Fmr1 KO mice and improved gut homeostasis and autistic behaviors. Our findings demonstrate that omega-3 PUFAs improve autistic behaviors and gut homeostasis in FMRP-deficient mice by suppressing gut microbiota dysbiosis, thereby presenting a novel therapeutic approach for juvenile FXS treatment.

The Microbiota-Dependent Treatment of Wuzhuyu Decoction for Chronic Migraine Model Rat Associated with Anxiety-Depression Like Behavior.

We previously found that Wuzhuyu Decoction (WZYD) could affect central and peripheral 5-HT to relieve hyperalgesia in chronic migraine (CM) model rats, possibly related to gut microbiota. However, the exact role of gut microbiota has not been elucidated. Accumulating evidence points to the possibility of treating central nervous system disease via the gut-brain axis. In our study, the inflammatory soup-induced CM model rats presented depression- and anxiety-like behaviors which both related to insufficient 5-HT. It was found that antibiotic administration caused community dysbiosis, and proteobacteria became the main dominant bacteria. The bacteria related to short-chain fatty acids and 5-HT generation were reduced, resulting in reduced levels of 5-HT, tryptophan hydroxylase, and secondary bile acids. Functional prediction-revealed sphingolipid signaling pathway in CM rats was significantly decreased and elevated after WZYD treatment. The effect of WZYD could be weakened by antibiotics. The CM rats exhibited anxiety- and depression-like behavior with 5-HT and number of neurons decreased in the CA1 and CA2 regions of hippocampal. The treatment of WZYD could recover to varying degrees. Antibiotics combined with WZYD attenuate the effect of WZYD on increasing the 5-HT content and related protein expression in the brain stem, plasma and colon, reducing CGRP, c-Fos, and inflammatory factors. And antibiotics also led to colon length increasing and stool retention, so that the antimigraine effect was weakened compared with WZYD. This experiment revealed that gut microbiota mediated WZYD treatment of CM rats with anxiety-depression like behavior.

AntDAS-DDA: A New Platform for Data-Dependent Acquisition Mode-Based Untargeted Metabolomic Profiling Analysis with Advantage of Recognizing Insource Fragment Ions to Improve Compound Identification.

Data-dependent acquisition (DDA) mode in ultra-high-performance liquid chromatography-high-resolution mass spectrometry (UHPLC-HRMS) can provide massive amounts of MS1 and MS/MS information of compounds in untargeted metabolomics and can thus facilitate compound identification greatly. In this work, we developed a new platform called AntDAS-DDA for the automatic processing of UHPLC-HRMS data sets acquired under the DDA mode. Several algorithms, including extracted ion chromatogram extraction, feature extraction, MS/MS spectrum construction, fragment ion identification, and MS1 spectrum construction, were developed within the platform. The performance of AntDAS-DDA was investigated comprehensively with a mixture of standard and complex plant data sets. Results suggested that features in complex sample matrices can be extracted effectively, and the constructed MS1 and MS/MS spectra can benefit in compound identification greatly. The efficiency of compound identification can be improved by about 20%. AntDAS-DDA can take full advantage of MS/MS information in multiple sample analyses and provide more MS/MS spectra than single sample analysis. A comparison with advanced data analysis tools indicated that AntDAS-DDA may be used as an alternative for routine UHPLC-HRMS-based untargeted metabolomics. AntDAS-DDA is freely available at http://www.pmdb.org.cn/antdasdda.

Auxin and CmAP1 regulate the reproductive development of axillary buds in Chinese chestnut (Castanea mollissima).

KEY MESSAGE: Auxin accumulation upregulates the expression of APETALA1 (CmAP1) and subsequently activates inflorescence primordium development in axillary buds of chestnut. The architecture of fruiting branches is a key determinant of chestnut yield. Normally, axillary buds at the top of mother fruiting branches develop into flowering shoots and bear fruits, and the lower axillary buds develop into vegetative shoots. Decapitation of the upper axillary buds induces the lower buds to develop into flowering shoots. How decapitation modulates the tradeoff between vegetative and reproductive development is unclear. We detected inflorescence primordia within both upper and lower axillary buds on mother fruiting branches. The level of the phytohormones 3-indoleacetic acid (IAA) and trans-zeatin (tZ) increased in the lower axillary buds in response to decapitation. Exogenous application of the synthetic analogues 1-naphthylacetic acid (NAA) or 6-benzyladenine (6-BA) blocked or promoted, respectively, the development of the inflorescence primordia in axillary buds. The transcript levels of the floral identity gene CmAP1 increased in axillary buds following decapitation. An auxin response element TGA-box is present in the CmAP1 promoter and influenced the CmAP1 promoter-driven expression of ß-glucuronidase (GUS) in floral organs in Arabidopsis, suggesting that CmAP1 is induced by auxin. We propose that decapitation releases axillary bud outgrowth from inhibition caused by apical dominance. During this process, decapitation-induced accumulation of auxin induces CmAP1 expression, subsequently promoting the reproductive development of axillary buds.

Design, Synthesis and Molecular Docking of 1,3,4-Oxadiazole-2(3H)-thione Derivatives Containing 1,4-Benzodioxane Skeleton as Potential FabH Inhibitors.

Fatty acid biosynthesis is essential for bacterial survival. Of these promising targets, ß-ketoacyl-acyl carrier protein (ACP) synthase III (FabH) is the most attractive target. A series of novel 1,3,4-oxadiazole-2(3H)-thione derivatives containing 1,4-benzodioxane skeleton targeting FabH were designed and synthesized. These compounds were determined by 1 H-NMR, 13 C-NMR, MS and further confirmed by crystallographic diffraction study for compound 7m and 7n. Most of the compounds exhibited good inhibitory activity against bacteria by computer-assisted screening, antibacterial activity test and E. coli FabH inhibitory activity test, wherein compounds 7e and 7q exhibited the most significant inhibitory activities. Besides, compound 7q showed the best E. coli FabH inhibitory activity (IC50 =2.45 µΜ). Computational docking studies also showed that compound 7q interacts with FabH critical residues in the active site.

RNA G-quadruplex in live cells lighted-up by a thiazole orange analogue for SCA36 identification.

SCA36 is a neurodegenerative disease mainly caused by the abnormal expansion of the GGGCCT repeat sequence in intron 1 of NOP56. The RNA sequences of this gene are expected to form large amounts of G-quadruplexes in the cytoplasm, which may be a potential intervention and detection target for SCA36. Here, we have developed a small-molecular compound named TCB-1, which shows good selectivity to the G-quadruplex structure, and its fluorescence can be enhanced by hundreds of folds. Interestingly, TCB-1 can avoid lysosome capture, evenly disperse in the cytoplasm, and selectively light up the cytoplasmic RNA G-quadruplexes. This property allows TCB-1 to sensitively detect the increased formation of cytoplasmic RNA G-quadruplexes in SCA36 model cells. This work not only provides new ideas for the design of small-molecule compounds targeting RNA G-quadruplexes in living cells, but also intuitively demonstrates the increased formation of RNA G-quadruplexes caused by NOP56 gene mutation, providing a possible tool for the detection of SCA36.

A Comprehensive Analysis of Physiologic and Hormone Basis for the Difference in Room-Temperature Storability between 'Shixia' and 'Luosanmu' Longan Fruits.

Although the effects of phytohormones (mainly salicylic acid) on the storability of longan fruit have been reported, the relationship between postharvest hormone variation and signal transduction and storability remains unexplored. The basis of physiology, biochemistry, hormone content and signalling for the storability difference at room-temperature between 'Shixia' and 'Luosanmu' longan fruit were examined. 'Luosanmu' longan exhibited faster pericarp browning, aril breakdown and rotting during storage. 'Luosanmu' pericarp exhibited higher malondialdehyde but faster decreased total phenolics, flavonoid, glutathione, vitamin C, catalase activity and gene expression. Higher H2O2 and malondialdehyde but lower glutathione, glutathione-reductase and peroxidase activities, while higher activities and gene expressions of polygalacturonase, ß-galactosidase and cellulose, lower covalent-soluble pectin, cellulose and hemicellulose but higher water-soluble pectin were observed in 'Luosanmu' aril. Lower abscisic acid and methyl jasmonate but higher expressions of LOX2, JAZ and NPR1 in pericarp, while higher abscisic acid, methyl jasmonate and salicylic acid together with higher expressions of ABF, JAZ, NPR1 and PR-1 in 'Luosanmu' aril were observed. In conclusion, the imbalance between the accumulation and scavenging of active oxygen in 'Luosanmu' longan might induce faster lipid peroxidation and senescence-related hormone signalling and further the polymerization of phenolics in pericarp and polysaccharide degradation in aril.

Network Pharmacology and Molecular Docking Analysis Explores the Mechanisms of Cordyceps sinensis in the Treatment of Oral Lichen Planus.

Objective: Oral lichen planus (OLP) is the most common potentially malignant disorder of the oral cavity. This study aimed to investigate the mechanism of action of Cordyceps sinensis in the treatment of OLP and provides a theoretical support for improving current treatment regimens for OLP. Methods: The active components and therapeutic targets of Cordyceps sinensis were predicted and screened using the TCMSP, SymMap, PubMed, HIT 2.0, and PharmMapper databases, while the relevant OLP targets were predicted and screened using the DisGeNET and GeneCards databases. Protein-protein interactions (PPI) were examined using the String database, and Cytoscape was used to combine and illustrate the findings. GO and KEGG pathway enrichment analyses were carried out using RStudio, and AutoDock Vina and Pymol were used for molecular docking and visualization, respectively. Results: A total of 404 potential target genes were discovered after evaluating 21 active compounds from Cordyceps sinensis. Potential therapeutic targets included 67 targets that matched and overlapped with OLP, including TNF, IL-6, CD4, EGFR, and IL1B. Key targets were predominantly engaged in the PI3K-Akt signaling pathway and the MAPK signaling pathway, according to the GO and KEGG analyses. These targets have a connection to biological processes including apoptosis signaling pathway regulation, T cell activation, and oxidative stress response. The molecular docking results showed that TNF, IL-6, CD4, EGFR, and IL1B could bind to their corresponding active components. Conclusions: Cordyceps sinensis contains multiple components and acts on multiple targets and multiple pathways. Particularly, Cordyceps sinensis targets TNF, IL-6, CD4, EGFR, and IL1B, regulates PI3K-Akt and MAPK signaling pathways, as well as takes part in biological processes including apoptosis, T cell activation, and oxidative stress. Cordyceps sinensis could be a crucial choice in the therapy of OLP.

Novel perspectives on the therapeutic role of cryptotanshinone in the management of stem cell behaviors for high-incidence diseases.

Cryptotanshinone (CTS), a diterpenoid quinone, is found mostly in Salvia miltiorrhiza Bunge (S. miltiorrhiza) and plays a crucial role in many cellular processes, such as cell proliferation/self-renewal, differentiation and apoptosis. In particular, CTS's profound physiological impact on various stem cell populations and their maintenance and fate determination could improve the efficiency and accuracy of stem cell therapy for high-incidence disease. However, as much promise CTS holds, these CTS-mediated processes are complex and multifactorial and many of the underlying mechanisms as well as their clinical significance for high-incidence diseases are not yet fully understood. This review aims to shed light on the impact and mechanisms of CTS on the actions of diverse stem cells and the involvement of CTS in the many processes of stem cell behavior and provide new insights for the application of CTS and stem cell therapy in treating high-incidence diseases.

Is port state control influenced by the COVID-19? Evidence from inspection data.

Maritime transport plays a key role in global trade. The safeguard of maritime transport is the Port State Control (PSC) inspection implemented all over the world. The outbreak of the Coronavirus disease (COVID-19) in 2020 presents new and unprecedented impacts on global supply chains and the ports as well as the entire shipping industry. Various measures were adopted by the countries and regions to halt the spread of the pandemic, mainly by reducing face-to-face interactions. As PSC inspections involve getting onboard vessels and in-person communications between the inspectors and the crew, its procedure and results are highly likely to be influenced by the COVID-19. This study aims to explore whether, how, and why the global and regional PSC inspection statuses are influenced by the pandemic through analyzing real inspection data. Specifically, three general indicators, namely inspection number, average deficiency number per inspection, and detention rate, are considered. Moreover, a detailed and comprehensive analysis of the inspection data at the Hong Kong port is conducted, including the number of inspections conducted, the average deficiency number and detention rate, the types of inspections conducted and ships inspected, the detailed deficiency and detention conditions, the relationship between the local pandemic situation and the PSC inspection status, and regression analysis on the influencing factors on inspection outcome. It is found that the COVID-19 pandemic indeed has an impact on PSC. Meanwhile, pragmatic and flexible measures are adopted by the port states, and the PSC has always been acting as a 'safety net' to guarantee maritime safety, promote the marine environment, and protect the seafarers' rights even under the difficult times during the COVID-19 pandemic.