Overcoming research challenges: In vitro cultivation of Ameson portunus (Phylum Microsporidia)

Ameson portunus is an intracellular pathogen that infects marine crabs Portunus trituberculatus and Scylla paramamosain, causing significant economic losses. However, research into this important parasite has been limited due to the absence of an in vitro culture system. To address this challenge, we developed an in vitro cultivation model of A. portunus using RK13 cell line in this study. The fluorescent labeling assay indicated a high infection rate (∼60 %) on the first day post-infection and quantitative PCR (qPCR) detection demonstrated successful infection as early as six hours post-inoculation. Fluorescence in situ hybridization (FISH) and qPCR were used for the detection of A. portunus infected cells. The FISH probe we designed allowed detection of A. portunus in infected cells and qPCR assay provided accurate quantification of A. portunus in the samples. Transmission electron microscopy (TEM) images revealed that A. portunus could complete its entire life cycle and produce mature spores in RK13 cells. Additionally, we have identified novel life cycle characteristics during the development of A. portunus in RK 13 cells using TEM. These findings contribute to our understanding of new life cycle pathways of A. portunus. The establishment of an in vitro culture model for A. portunus is critical as it provides a valuable tool for understanding the molecular and immunological events that occur during infection. Furthermore, it will facilitate the development of effective treatment strategies for this intracellular pathogen.

All-hydrocarbon stapling enables improvement of antimicrobial activity and proteolytic stability of peptide Figainin 2

Figainin 2 is a cationic, hydrophobic, α-helical host-defense peptide with 28 residues, which was isolated from the skin secretions of the Chaco tree frog. It shows potent inhibitory activity against both Gram-negative and Gram-positive pathogens and has garnered considerable interest in developing novel classes of natural antibacterial agents. However, as a linear peptide, conformational flexibility and poor proteolytic stability hindered its development as antibacterial agent. To alleviate its susceptibility to proteolytic degradation and improve its antibacterial activity, a series of hydrocarbon-stable analogs of Figainin 2 were synthesized and evaluated for their secondary structure, protease stability, antimicrobial, and hemolytic activities. Among them, F2-12 showed significant improvement in protease resistance and antimicrobial activity compared to that of the template peptide. This study provides a promising strategy for the development of antimicrobial drugs.

Design, Synthesis, and Anti-Osteoporotic Characterization of Arginine N-Glycosylated Teriparatide Analogs via the Silver-catalyzed Solid-Phase Glycosylation Strategy

In spite of effective antiosteoporosis potency, teriparatide, a bone-building agent approved by the FDA (Food and Drug Administration), was proven to exhibit various side effects. In our previous work, we developed a universal strategy for synthesizing arginine N-glycosylated peptides termed silver-promoted solid-phase glycosylation (SSG) strategy. However, it is unknown whether the SSG strategy can be applied in the peptide drug design. Herein, we first reported the optimization of teriparatide via SSG strategy. Using Arg20 and/or Arg25 as the modifying positions, three series of arginine N-glycosylated teriparatide analogs were successfully synthesized, of which the introduced sugar groups included glucose, galactose, mannose, rhamnose, ribose, 2-acetamino-2-deoxy-glucose, xylose, lactose, and maltose. Among the 27 arginine N-glycosylated derivatives, Arg20-xylose and Arg25-maltose teriparatide analogs, termed PTH-1g and PTH-2i, respectively, indicated enhanced serum stability and significantly improved antiosteoporotic activities in vitro and in vivo compared with the native counterpart. They may serve as effective therapeutic candidates for treating osteoporosis.

Multi-omics insights into the mechanism of the high-temperature tolerance in a thermotolerant Chlorella sorokiniana

Improving high-temperature tolerance of microalgae is crucial to enhance the robustness and economy of microalgae industrial production. Herein, a continuous adaptive laboratory evolution (ALE) system was developed to generate the thermotolerant strain of Chlorella sorokiniana. The resulting thermotolerant strain TR42 exhibited excellent cell growth and biomass production at 42 °C, the temperature that the original strain (OS) could not survive. The high-temperature resistant mechanism of TR42 was investigated by integrating the physiology, transcriptome, proteome and metabolome analyses, which involved enhancing antioxidant capacity, maintaining protein homeostasis, remodeling photosynthetic metabolism, and regulating the synthesis of heat-stress related metabolites. The proof-of-concept high-temperature outdoor cultivation demonstrated that TR42 exhibited 1.15- to 5.72-fold increases in biomass production and 1.62- to 7.04-fold increases in lipid productivity compared to those of OS, respectively, which provided a promising platform for microalgae industrial production. Thus, the multi-system thermotolerant mechanism of TR42 offered potential targets for enhancing high-temperature tolerance of microalgae.

Benzyl stapled modification and anticancer activity of antimicrobial peptide A4K14-Citropin 1.1

A4K14-Citropin 1.1 (GLFAVIKKVASVIKGL-NH2) is a derived antimicrobial peptide (AMP) with a more stable α-helical structure at the C-terminal compared to prototype Citropin 1.1 which was obtained from glandular skin secretions of Australian freetail lizards. In a previous report, A4K14-Citropin 1.1 has been considered as an anti-cancer lead compound. However, linear peptides are difficult to maintain stable secondary structure, resulted in poor pharmacokinetic properties. In this study, we designed and synthesized a series of benzyl-stapled derivatives of A4K14-Citropin 1.1. And their physical and chemical properties, as well as biological activity, were both explored. The result showed that AC-CCSP-2-o and AC-CCSP-3-o exhibited a higher degree of helicity and greater anti-cancer activity compared with the prototype peptide. Besides, there was no significant difference in the hemolytic effect between the stapled peptides and the prototype peptide. AC-CCSP-2-o and AC-CCSP-3-o could serve as promising anti-cancer lead compounds for the novel anti-cancer drug development.

Unleashing the potential of natural biological peptide Macropin: Hydrocarbon stapling for effective breast cancer treatment

The identification of novel candidate molecules with the potential to revolutionize the treatment of breast cancer holds profound clinical significance. Macropin (Mac)-1, derived from the venom of wild bees, emerges as an auspicious therapeutic agent for combating breast cancers. Nevertheless, linear peptides have long grappled with the challenges of traversing cell membranes and succumbing to protease hydrolysis. To address this challenge, the present study employed hydrocarbon stapling modification to synthesize a range of stapled Mac-1 peptides, which were comprehensively evaluated for their chemical and biological properties. Significantly, Mac-1-sp4 exhibited a remarkable set of improvements, including enhanced helicity, proteolytic stability, cell membrane permeability, induction of cell apoptosis, in vivo antitumor activity, and inhibition of tubulin polymerization. This study explores the significant impact of the hydrocarbon stapling technique on the secondary structure, hydrolase stability, and biological activity of Mac-1, shedding light on its potential as a revolutionary and potent anti-breast cancer therapy. The findings establish a strong basis for the development of innovative and highly effective anti-tumor treatments.

Mutations of family with sequence similarity 20-member C gene causing lethal and nonlethal Raine syndrome causes hypophosphatemia rickets

Family with sequence similarity 20-member C (FAM20C) is a kinase specific to most of the secreted phosphoproteome. FAM20C has been identified as the causative gene of Raine syndrome, initially characterized by lethal osteosclerosis bone dysplasia. However, since the identification of the cases of nonlethal Raine syndrome characterized by hypophosphatemia rickets, the previous definition of Raine syndrome has become debatable and raised a question about the role of mutations of FAM20C in controversial skeletal manifestation in the two forms of the disease. In this study, we aimed to investigate the influence of FAM20C mutations on skeletogenesis. We developed transgenic mice expressing Fam20c mutations mimicking those associated with human lethal and nonlethal Raine syndrome. The results revealed that transgenic mice expressing the mutant Fam20c found in the lethal (KO;G374R) and nonlethal (KO;D446N) Raine syndrome exhibited osteomalacia without osteosclerotic features. Additionally, both mutants significantly increased the expression of the Fgf23, indicating that Fam20c deficiency in skeletal compartments causes hypophosphatemia rickets. Furthermore, as FAM20C kinase activity catalyzes the phosphorylation of secreted proteomes other than those in the skeletal system, global FAM20C deficiency may trigger alterations in other systems resulting in osteosclerosis secondary to hypophosphatemia rickets. Together, the findings of this study suggest that FAM20C deficiency primarily causes hypophosphatemia rickets or osteomalacia; however, the heterogeneous skeletal manifestation in Raine syndrome was not determined solely by specific mutations of FAM20C. The findings also implicated that rickets or osteomalacia caused by FAM20C deficiency would deteriorate into osteosclerosis by the defects from other systems or environmental impacts.

Corrigendum: Design, synthesis, and antitumor activity study of all-hydrocarbon-stapled B1-Leu peptides

[This corrects the article DOI: 10.3389/fchem.2022.840131.].

Cyclobutane-bearing restricted anchoring residues enabled geometry-specific hydrocarbon peptide stapling

Stapled peptides are regarded as the promising next-generation therapeutics because of their improved secondary structure, membrane permeability and metabolic stability as compared with the prototype linear peptides. Usually, stapled peptides are obtained by a hydrocarbon stapling technique, anchoring from paired olefin-terminated unnatural amino acids and the consequent ring-closing metathesis (RCM). To investigate the adaptability of the rigid cyclobutane structure in RCM and expand the chemical diversity of hydrocarbon peptide stapling, we herein described the rational design and efficient synthesis of cyclobutane-based conformationally constrained amino acids, termed (E)-1-amino-3-(but-3-en-1-yl)cyclobutane-1-carboxylic acid (E7) and (Z)-1-amino-3-(but-3-en-1-yl)cyclobutane-1-carboxylic acid (Z7). All four combinations including E7-E7, E7-Z7, Z7-Z7 and Z7-E7 were proven to be applicable in RCM-mediated peptide stapling to afford the corresponding geometry-specific stapled peptides. With the aid of the combined quantum and molecular mechanics, the E7-E7 combination was proven to be optimal in both the RCM reaction and helical stabilization. With the spike protein of SARS-CoV-2 as the target, a series of cyclobutane-bearing stapled peptides were obtained. Among them, E7-E7 geometry-specific stapled peptides indeed exhibit higher α-helicity and thus stronger biological activity than canonical hydrocarbon stapled peptides. We believe that this methodology possesses great potential to expand the scope of the existing peptide stapling strategy. These cyclobutane-bearing restricted anchoring residues served as effective supplements for the existing olefin-terminated unnatural amino acids and the resultant geometry-specific hydrocarbon peptide stapling provided more potential for peptide therapeutics.

Discovery of an orally effective double-stapled peptide for reducing ovariectomy-induced bone loss in mice

Stapled peptides with significantly enhanced pharmacological profiles have emerged as promising therapeutic molecules due to their remarkable resistance to proteolysis and performance to penetrate cells. The all-hydrocarbon peptide stapling technique has already widely adopted with great success, yielding numerous potent peptide-based molecules. Based on our prior efforts, we conceived and prepared a double-stapled peptide in this study, termed FRNC-1, which effectively attenuated the bone resorption capacity of mature osteoclasts in vitro through specific inhibition of phosphorylated GSK-3β. The double-stapled peptide FRNC-1 displayed notably improved helical contents and resistance to proteolysis than its linear form. Additionally, FRNC-1 effectively prevented osteoclast activation and improved bone density for ovariectomized (OVX) mice after intravenous injection and importantly, after oral (intragastric) administration. The double-stapled peptide FRNC-1 is the first orally effective peptide that has been validated to date as a therapeutic candidate for postmenopausal osteoporosis (PMOP).

Lc-pPG-612-OmpU-CTB: A promising oral vaccine for protecting Carassius auratus against Vibrio mimicus infection

Vibrio mimicus (V. mimicus) is known to cause severe bacterial diseases with high mortality rates in fish, resulting in significant economic losses in the global aquaculture industry. Therefore, the objective of this study was to develop a safe and effective vaccine for protecting Carassius auratus (C. auratus) against V. mimicus infection. Recombinant Lactobacillus casei (L. casei) strains, Lc-pPG-612-OmpU and Lc-pPG-612-OmpU-CTB (surface-displayed), were constructed using a L. casei strain (ATCC 393) as an antigen delivery carrier and the cholera toxin B subunit (CTB) as an adjuvant. The two recombinant strains of L. casei were administered to C. auratus via oral immunization, and the protective efficacy of the oral vaccines was assessed. The results demonstrated that oral immunization with the two strains significantly increased the levels of nonspecific immune indicators in C. auratus, including alkaline phosphatase (AKP), lysozyme (LYS), acid phosphatase (ACP), complement 3 (C3), complement 4 (C4), lectin, and superoxide dismutase (SOD). Moreover, the experiment groups exhibited significant increases in specific immunoglobulin M (IgM) antibodies against OmpU, as well as the transcription of immune-related genes (ie., IL-1β, TNF-α, IL-10, and TGF-β), when compared to the control groups. Following infection of C. auratus with V. mimicus, the mortality rate of the recombinant L. casei-treated fish was observed to be lower compared to the control group. This finding suggests that recombinant L. casei demonstrates effective protection against V. mimicus infection in C. auratus. Furthermore, the addition of the immune adjuvant CTB was found to induce a more robust adaptive and innate immune response in C. auratus, resulting in reduced mortality after infection with V. mimicus.

Weissella confusa N17 Derived from Loach (Misgurnus anguillicaudatus) Exhibits Promising for Further Applications in Loach Aquaculture

The application of probiotics, in aquaculture, is becoming increasingly widespread and have had positive application effects. However, reports of loach-derived probiotics are quite limited. In this study, two representative strains of lactic acid bacteria with excellent traits, namely, Weissella confusa N17 and Lactobacillus saniviri N19, were screened from the intestine of healthy loaches. W. confusa N17 and L. saniviri N19 could inhibit different common various pathogenic bacteria, especially Aeromonas spp., and were sensitive to the most common antibiotics. The survival rate of the two strains exceeded 50% after 4 h of incubation in 10% loach bile. Moreover, the two strains showed significant tolerance to trypsin. Their autoaggregation capacity and hydrophobicity were greater than 30%. In addition, the aggregation ability of both strains was higher than 30% for both A. veronii TH0426 and A. hydrophila TPS. The two strains had a high biofilm-forming ability and strong adhesion to epithelioma papulosum cyprini (EPC) cells. Scanning electron microscopy results showed that the culture supernatants of the two strains had a significantly destructive effect on A. veronii TH0426 and A. hydrophila TPS. Overall, the traits of W. confusa N17 were better than those of L. saniviri N19. Genome sequencing and analysis demonstrated a lack of virulence factor-related or drug resistance-related genes in genome N17. The diet supplemented with the W. confusa N17 strain significantly improved the resistance of loaches to A. veronii infection, and the protection rate reached 57.1%. Therefore, W. confusa N17 exhibits promising for further applications in loach aquaculture.

Immunological effects of recombinant Lactobacillus casei expressing pilin MshB fused with cholera toxin B subunit adjuvant as an oral vaccine against Aeromonas veronii infection in crucian carp

Aeromonas veronii is a zoonotic agent capable of infecting fish and mammals, including humans, posing a serious threat to the development of aquaculture and public health safety. Currently, few effective vaccines are available through convenient routes against A. veronii infection. Herein, we developed vaccine candidates by inserting MSH type VI pili B (MshB) from A. veronii as an antigen and cholera toxin B subunit (CTB) as a molecular adjuvant into Lactobacillus casei and evaluated their immunological effect as vaccines in a crucian carp (Carassius auratus) model. The results suggested that recombinant L. casei Lc-pPG-MshB and Lc-pPG-MshB-CTB can be stably inherited for more than 50 generations. Oral administration of recombinant L. casei vaccine candidates stimulated the production of high levels of serum-specific immunoglobulin M (IgM) and increased the activity of acid phosphatase (ACP), alkaline phosphatase (AKP) superoxide dismutase (SOD), lysozyme (LZM), complement 3 (C3) and C4 in crucian carp (carassius auratus) compared to the control group (Lc-pPG612 group and PBS group) without significant changes. Moreover, the expression levels of interleukin-10 (IL-10), interleukin-1β (IL-1β), tumour necrosis factor-α (TNF-α) and transforming growth factor-β (TGF-β) genes in the gills, liver, spleen, kidney and gut of crucian carp orally immunized with recombinant L. casei were significantly upregulated compared to the control groups, indicating that recombinant L. casei induced a significant cellular immune response. In addition, viable recombinant L. casei can be detected and stably colonized in the intestine tract of crucian carp. Particularly, crucian carp immunized orally with Lc-pPG-MshB and Lc-pPG-MshB-CTB exhibited higher survival rates (48% for Lc-pPG-MshB and 60% for Lc-pPG-MshB-CTB) and significantly reduced loads of A. veronii in the major immune organs after A. veronii challenge. Our findings indicated that both recombinant L. casei strains provide favorable immune protection, with Lc-pPG-MshB-CTB in particular being more effective and promising as an ideal candidate for oral vaccination.

Design, synthesis and antitumor activity of Ascaphin-8 derived stapled peptides based on halogen-sulfhydryl click chemical reactions

Ascaphin-8 (GFKDLLKGAAKALVKTVLF-NH₂), isolated from the norepinephrine-stimulated skin secretion of the North American-tailed frog Ascaphus truei, is a C-terminal α-helical antimicrobial peptide with potential antitumor activity. However, linear peptides are difficult to be applied directly as drugs because of their inherent defects, such as low hydrolytic enzyme tolerance and poor structural stability. In this study, we designed and synthesized a series of stapled peptides based on Ascaphin-8 via thiol-halogen click chemistry. Most of the stapled peptide derivatives showed enhanced antitumor activity. Among them, A8-2-o and A8-4-Dp had the most improved structural stability, stronger hydrolytic enzyme tolerance and highest biological activity. This research may provide a reference for the stapled modification of other similar natural antimicrobial peptides.

The recent progress of peptide regulators for the Wnt/β-catenin signaling pathway

Wnt signaling plays an important role in many biological processes such as stem cell self-renewal, cell proliferation, migration, and differentiation. The β-catenin-dependent signaling pathway mainly regulates cell proliferation, differentiation, and migration. In the Wnt/β-catenin signaling pathway, the Wnt family ligands transduce signals through LRP5/6 and Frizzled receptors to the Wnt/β-catenin signaling cascades. Wnt-targeted therapy has garnered extensive attention. The most commonly used approach in targeted therapy is small-molecule regulators. However, it is difficult for small-molecule regulators to make great progress due to their inherent defects. Therapeutic peptide regulators targeting the Wnt signaling pathway have become an alternative therapy, promising to fill the gaps in the clinical application of small-molecule regulators. In this review, we describe recent advances in peptide regulators for Wnt/β-catenin signaling.

Chronic Heat Stress Affects Bile Acid Profile and Gut Microbiota in Broilers

Heat stress (HS) can inhibit the growth performance of broilers and cause substantial economic losses. Alterations in bile acid (BA) pools have been reported to be correlated with chronic HS, yet the specific mechanism and whether it is related to gut microbiota remains unclear. In this study, 40 Rugao Yellow chickens were randomly selected and distributed into two groups (20 broilers in each group) when reaching 56-day age: a chronic heat stress group (HS, 36 ± 1 °C for 8 h per day in the first 7 days and 36 ± 1 °C for 24 h in the last 7 days) and a control group (CN, 24 ± 1 °C for 24 h within 14 days). Compared with the CN group, total BAs' serum content decreased, while cholic acid (CA), chenodeoxycholic acid (CDCA), and taurolithocholic acid (TLCA) increased significantly in HS broilers. Moreover, 12α-hydroxylase (CYP8B1) and bile salt export protein (BSEP) were upregulated in the liver, and the expression of fibroblast growth factor 19 (FGF19) decreased in the ileum of HS broilers. There were also significant changes in gut microbial composition, and the enrichment of Peptoniphilus was positively correlated with the increased serum level of TLCA. These results indicate that chronic HS disrupts the homeostasis of BA metabolism in broilers, which is associated with alterations in gut microbiota.

pH/Hyal-Responsive Surface-Charge Switchable Electrostatic Complexation for Efficient Elimination of MRSA Infection

Methicillin-resistant Staphylococcus aureus (MRSA) has become a great threat to human health worldwide, making new effective antibacterial strategies urgently desired. In this study, a cationic pH-responsive delivery system (pHSM) was developed based on poly(β-amino esters)-methoxy poly(ethylene glycol), by which linezolid (LZD) could be encapsulated to form pHSM/LZD. The biocompatibility and stability of pHSM/LZD were further enhanced by adding low-molecular-weight hyaluronic acid (LWT HA) on the surface through electrostatic interaction to form pHSM/LZD@HA, of which the positive surface charges were neutralized by LWT HA under physiological conditions. LWT HA can be degraded by hyaluronidase (Hyal) after arriving at the infection site. In vitro, pHSM/LZD@HA could rapidly change to being positively charged on the surface within 0.5 h under acidic conditions, especially when Hyal was present, thus promoting bacterial binding and biofilm penetration of pHSM/LZD@HA. In addition, the pH/Hyal-dependent accelerated drug release behavior was also observed and it is beneficial for the comprehensive treatment of MRSA infection in vitro and in vivo. Our study provides a novel strategy to develop a pH/Hyal-responsive drug delivery system for the treatment of MRSA infection.

Global prevalence and factors affecting the level of Cryptosporidium contamination in soil: A systematic review, meta-analysis, and meta-regression

Soil contamination with Cryptosporidium is a serious environmental and public health concern. In this systematic review and meta-analysis we estimated the global prevalence of Cryptosporidium contamination in soil and evaluated its association with climatic and hydrometeorological factors. PubMed, Web of Science, Science Direct, China National Knowledge Infrastructure, and Wanfang were searched from database inception up to 24 August 2022. The initial search identified 3220 studies, of which 14 met the inclusion criteria. The results were pooled using a random-effects model, and the statistical heterogeneity among the included studies was examined using Cochrane's Q test and I² statistic. The estimated pooled global prevalence of Cryptosporidium in soil across all studies was 8.13 % (95 % confidence interval, 1.54-18.44). Meta-regression and subgroup analyses showed that Cryptosporidium prevalence in soil was significantly influenced by continent (p = 0.0002; R² = 49.99 %), air pressure (p = 0.0154; R² = 24.01 %), temperature (p = 0.0437; R² = 14.53 %), and detection method (p = 0.0131; R² = 26.94 %). These results highlight the need for increased surveillance of Cryptosporidium in soil and its risk factors to inform future development of environmental control interventions and public health policies.

Efficacy of a recombinant Lactobacillus plantarum Lp-pPG-Malt as an oral vaccine candidate against Aeromonas hydrophila infection in crucian carp

Aeromonas hydrophila (A. hydrophila), a gram-negative bacterium, causes serious diseases with various clinical symptoms in farm raised fish. Thus, different ways to prevent and control A. hydrophila infection need to be explored, including a vaccine. In this study, we evaluated the protective efficacy of an oral vaccine prepared from the A. hydrophila TPS maltoporin (Malt) with Lactobacillus plantarum (L. plantarum) against A. hydrophila infection in crucian carp (Carassius auratus). For the in vivo experiment, the oral vaccine was administered to crucian carp by feeding them fish diets containing Lp-pPG-Malt, Lp-pPG and PBS for 28 days. The enzyme-linked immunosorbent assay (ELISA), leukocyte phagocytosis assay and real-time quantitative polymerase chain reaction (RT-qPCR) were performed to measure the protective efficacy of the Lp-pPG-Malt. ELISA and leukocyte phagocytosis assay confirmed that Lp-pPG-Malt significantly enhanced the IgM level and nonspecific immune response of crucian carp compared with the control groups (Lp-pPG and PBS). The RT-qPCR results showed that the Lp-pPG-Malt increased the relative expression of immune-related genes (IL-10, IL-1β, TNF-α, IFN-γ) of crucian carp in various tissues (liver, spleen, head kidney and hind intestine). Moreover, Lp-pPG-Malt significantly increased the relative percent survival of fish after intraperitoneal injection with A. hydrophila (55%) compared with the Lp-pPG and PBS groups (0%). These findings suggest that Lp-pPG-Malt can serve as an oral vaccine candidate for A. hydrophila infection and that Malt can be used as an effective antigen in crucian carp farming.

Critical roles of VipB protein on virulence and oxidative stress tolerance in Aeromonas veronii

Aeromonas veronii is a zoonotic pathogen capable of causing sepsis and ulceration in freshwater fish. Recently, reports of numerous cases indicate a marked increase in pathogenicity. Nonetheless, little is known about the pathogenesis of A. veronii infections. In this study, an in-frame mutant of the A. veronii vipB gene was generated to investigate its biological function. Deletion of the vipB gene resulted in a significant 204.71-fold decrease in the LD₅₀ of A. veronii against zebrafish and a 2-fold and 4-fold reduction in the toxicity to EPC cells at 1 h and 2 h of infection, respectively. The virulence-related genes of the mutant ΔvipB all showed significantly reduced expression levels compared to the wild strain. In addition, the motility of the mutant ΔvipB decreased significantly, the adhesion ability to EPC cells was 3.25-fold lower than that of the parental strain, and the oxidative stress tolerance was 2.31-fold lower than that of TH0426 strain. In contrast, the biofilm formation amount of ΔvipB strain increased by 1.65-fold at both 12 h and 24 h. Our findings suggest that the vipB gene is associated with flagella stability, virulence, and oxidative stress tolerance and plays critical roles in the pathogenesis of A. veronii infections.

Evenness of soil organic carbon chemical components changes with tree species richness, composition and functional diversity across forests in China

Higher tree species richness generally increases the storage of soil organic carbon (SOC). However, less attention is paid to the influence of varied tree species composition on SOC storage. Recently, the perspectives for the stronger persistence of SOC caused by the higher molecular diversity of organic compounds were proposed. Therefore, the influences of tree species richness and composition on the molecular diversity of SOC need to be explored. In this study, an index of the evenness of diverse SOC chemical components was proposed to represent the potential resistance of SOC to decomposition under disturbances. Six natural forest types were selected encompassing a diversity gradient, ranging from cold temperate to tropical forests. We examined the correlations of tree species richness, composition, and functional diversity, with the evenness of SOC chemical components at a molecular level by ¹³ C nuclear magnetic resonance. Across the range, tree species richness correlated to the evenness of SOC chemical components through tree species composition. The negative correlation of evenness of SOC chemical components with tree species composition, and the positive correlation of evenness of SOC chemical components with tree functional diversity were found. These indicate the larger difference in tree species composition and the lower community functional diversity resulted in the higher heterogeneity of SOC chemical components among the communities. The positive correlation of the evenness of SOC chemical components with the important value of indicator tree species, further revealed the specific tree species contributing to the higher evenness of SOC chemical components in each forest type. Soil fungal and bacterial α-diversity had effect on the evenness of SOC chemical components. These findings suggest that the indicator tree species conservation might be preferrable to simply increasing tree species richness, for enhancing the potential resistance of SOC to decomposition.

Oral vaccination with recombinant Lactobacillus casei with surface displayed OmpK fused to CTB as an adjuvant against Vibrio mimicus infection in Carassius auratus

Vibrio mimicus (V. mimicus) is a pathogenic bacterium that causes diseases in humans and various aquatic animals. A particularly efficient way to provide protection against V. mimicus is through vaccination. However, there are few commercial vaccines against V. mimics, especially oral vaccines. In our study, two surface-display recombinant Lactobacillus casei (L. casei) Lc-pPG-OmpK and Lc-pPG-OmpK-CTB were constructed using L. casei ATCC393 as an antigen delivery vector, outer membrane protein K (OmpK) of V. mimicus as an antigen, and cholera toxin B subunit (CTB) as a molecular adjuvant; furthermore, the immunological effects of recombinant L.casei in Carassius auratus (C. auratus) were assessed. The results indicated that oral recombinant L.casei Lc-pPG-OmpK and Lc-pPG-OmpK-CTB stimulated higher levels of serum-specific immunoglobulin M (IgM) and increased the activity of acid phosphatase (ACP), alkaline phosphatase (AKP), superoxide dismutase (SOD), lysozyme (LYS), lectin, C3, and C4 in C. auratus, compared with control groups (Lc-pPG group and PBS group). Furthermore, the expression of interleukin-1β (IL-1β), interleukin-10 (IL-10), tumor necrosis factor-α (TNF-α), and transforming growth factor-β (TGF-β) in the liver, spleen, head kidney, hind intestine and gills of C. auratus was significantly increased, compared with that in the controls. These results demonstrated that the two recombinant L. casei strains could effectively trigger humoral and cellular immunity in C. auratus. In addition, two recombinant L.casei strains were able to survive and colonize the intestine of C. auratus. Importantly, after being challenged with V. mimicus, C. auratus fed Lc-pPG-OmpK and Lc-pPG-OmpK-CTB exhibited greater survival rates than the controls (52.08% and 58.33%, respectively). The data showed that recombinant L. casei could elicit a protective immunological response in C. auratus. The effect of the Lc-pPG-OmpK-CTB group was better than that of the Lc-pPG-OmpK group, and Lc-pPG-OmpK-CTB was found to be an effective candidate for oral vaccination.

DUCNP@Mn-MOF/FOE as a Highly Selective and Bioavailable Drug Delivery System for Synergistic Combination Cancer Therapy

Heterostructures comprising lanthanide-doped upconversion nanoparticles (DUCNPs) and metal-organic frameworks (MOFs) are emerging as promising nanosystems for integrating medical diagnosis and treatment. Here, the DUCNP@Mn-MOF nanocarrier was developed, which showed good efficiency for loading and delivering a cytotoxic antitumor agent (3-F-10-OH-evodiamine, FOE). The combined advantages of the pH-responsive and peroxidase-like properties of Mn-MOF and the unique optical features of DUCNPs granted the DUCNP@Mn-MOF/FOE system synergistic chemodynamic and chemotherapeutic effects. The DUCNP@Mn-MOF nanocarrier effectively overcame the intrinsic limitations of FOE, such as its unfavorable physicochemical properties and limited in vivo potency. This complexed nanosystem was responsive to the tumor microenvironment and showed excellent tumor targeting capability. Thus, DUCNP@Mn-MOF/FOE exhibited highly selective and bioavailable drug delivery properties and is promising for cancer therapy. In a mouse breast cancer model, DUCNP@Mn-MOF/FOE inhibited tumor growth without significant toxicity. Therefore, the proposed nanosystem represents a promising theragnostic platform for multimodal combination diagnosis and therapy of tumors.

Embryonic thermal manipulation leads growth inhibition and reduced hepatic insulin-like growth factor1 expression due to promoter DNA hypermethylation in broilers

When broilers cannot adapt to a high-temperature environment through self-regulation, it will cause heat stress, resulting in a large number of deaths and substantial economic losses. Studies have shown that thermal manipulation (TM) during the embryonic stage can improve broilers' ability to resist heat stress later. However, different TM strategies produce different results on broilers' growth. In this study, yellow-feathered broiler eggs were selected and randomly divided into 2 groups between E10 and E18, which the control group was incubated at 37.8°C with 56% humidity, and the TM group was subjected to 39°C with 65% humidity. After hatching, all broilers were reared normally until slaughtered at 12 d of age (D12). During D1 to D12, body weight, feed intake, and body temperature were recorded. The results showed that TM significantly decreased (P < 0.05) the final body weight, weight gain, and average daily feed intake of broilers. Meanwhile, the serum levels of Triiodothyronine (T3) and free T3 were significantly decreased in the TM group (P < 0.05). The expressions of hepatic growth regulation-associated genes, growth hormone receptor (GHR), insulin-like growth factor1, and 2 (IGF1 and IGF2) were significantly down-regulated in the TM group (P < 0.05). In addition, TM altered hepatic DNA methylation, resulting in a significant increase (P < 0.05) in the methylation of the IGF1 and GHR promoter regions. The above results indicated that TM during the embryonic stage decreased the serum thyroid hormone level and increased the methylation level of the IGF1 and GHR promoter regions to down-regulate the expression of growth-related genes, resulting in early growth inhibition of broilers.

A systematic review, meta-analysis and meta-regression of the global prevalence of foodborne Vibrio spp. infection in fishes: A persistent public health concern

Human vibriosis, caused by pathogenic Vibrio spp., such as Vibrio parahaemolyticus, Vibrio cholerae and Vibrio vulnificus, has been increasing worldwide, mediated by increasing consumption of seafood. The present study was conducted to examine the global prevalence of V. vulnificus, V. parahaemolyticus and V. cholerae in fishes. We searched PubMed, Web of Science, Scopus, and CNKI for peer-reviewed articles and dissertations prior to December 31, 2021. A total of 24,831 articles were retrieved, and 82 articles contained 61 fish families were included. The global pooled prevalence of V. cholerae, V. parahaemolyticus and V. vulnificus in fishes was 9.56 % (95 % CI: 2.12-20.92), 24.77 % (95 % CI: 17.40-32.93) and 5.29 % (95 % CI: 0.38-13.61), respectively. Subgroup and meta-regression analyses showed that study-level covariates, including temperature, country, continent, origin and detection methods partly explained the between-study heterogeneity. These heterogeneities were underpinned by differences of the three Vibrio spp. in fishes at geographical and climatic scales. These results reveal a high global prevalence of pathogenic Vibrio spp. in fishes and highlight the need for implementation of more effective prevention and control measures to reduce food-borne infection in humans.

Lp-pPG-611.1-LPS as an immune enhancer provides effective protection against Aeromonas veronii infection in Carassius auratus

Aeromonas veronii (A. veronii) is an important zoonotic pathogen that causes substantial economic losses in aquaculture. In this study, we aimed to develop a safe and effective immune enhancer to protect Carassius auratus (C. auratus) from A. veronii infections. With recognized safety, lactic acid bacteria are used as antigen delivery vehicles to present antigens. Lipopolysaccharide (LPS), a protective antigen, induces immune responses in animals. Therefore, we created recombinant Lactobacillus plantarum (L. plantarum) with surface-displayed LPS of A. veronii TH0426 and tested its effects on immune responses in C. auratus. The results showed that recombinant L. plantarum Lp-pPG-611.1-LPS, as an immune enhancer, could improve the innate and adaptive immune responses of C. auratus when it was added to the diet of C. auratus. The challenge test showed that the survival rate of C. auratus fed with L. plantarum Lp-pPG-611.1-LPS was higher than that of the control groups, indicating that the recombinant L. plantarum Lp-pPG-611.1-LPS increased the resistance of C. auratus to A. veronii infection. The present results provide a theoretical basis for the development of recombinant L. plantarum Lp-pPG-611.1-LPS as an immune enhancer in aquaculture.

Crystal structure of 1-(2-iodobenzoyl)-6-methoxy-1H-indole-3-carbaldehyde, C17H12INO3

C17H12INO3, monoclinic, P21/n (no. 14), a = 7.5319(5) Å, b = 7.9745(5) Å, c = 25.1313(17) Å, β = 98.459(7)°, V = 1493.04(17) Å3, Z = 4, R gt (F) = 0.0272, wR ref (F 2) = 0.0595, T = 199.98(10) K.

Regulation of microglia related neuroinflammation contributes to the protective effect of Gelsevirine on ischemic stroke

Stroke, especially ischemic stroke, is an important cause of neurological morbidity and mortality worldwide. Growing evidence suggests that the immune system plays an intricate function in the pathophysiology of stroke. Gelsevirine (Gs), an alkaloid from Gelsemium elegans, has been proven to decrease inflammation and neuralgia in osteoarthritis previously, but its role in stroke is unknown. In this study, the middle cerebral artery occlusion (MCAO) mice model was used to evaluate the protective effect of Gs on stroke, and the administration of Gs significantly improved infarct volume, Bederson score, neurobiological function, apoptosis of neurons, and inflammation state in vivo. According to the data in vivo and the conditioned medium (CM) stimulated model in vitro, the beneficial effect of Gs came from the downregulation of the over-activity of microglia, such as the generation of inflammatory factors, dysfunction of mitochondria, production of ROS and so on. By RNA-seq analysis and Western-blot analysis, the JAK-STAT signal pathway plays a critical role in the anti-inflammatory effect of Gs. According to the results of molecular docking, inhibition assay, and thermal shift assay, the binding of Gs on JAK2 inhibited the activity of JAK2 which inhibited the over-activity of JAK2 and downregulated the phosphorylation of STAT3. Over-expression of a gain-of-function STAT3 mutation (K392R) abolished the beneficial effects of Gs. So, the downregulation of JAK2-STAT3 signaling pathway by Gs contributed to its anti-inflammatory effect on microglia in stroke. Our study revealed that Gs was benefit to stroke treatment by decreasing neuroinflammation in stroke as a potential drug candidate regulating the JAK2-STAT3 signal pathway.

Powered stapling system with gripping surface technology for pulmonary resection of lung cancer: real-world clinical effectiveness

OBJECTIVES

Surgical lung resection involves a critical task of stapled ligation and transection of major vascular structures and tissue, which may lead to bleeding and complications. A newer powered stapling system with Gripping Surface Technology (GST) was introduced to account for tissue movements. This study aimed to examine the real-world effectiveness of GST system on intraoperative and postoperative outcomes of pulmonary resection.

METHODS

A retrospective analysis was conducted using the electronic medical records of Sichuan Provincial People's Hospital between July 2020 and March 2021 in China. Patients who underwent their first procedures of single-port lobectomy or multi-port segmentectomy by video-assisted thoracoscopic surgery were identified and grouped as GST group or manual stapler group (manual group) by the stapler types. The intraoperative outcomes such as bleeding rate, blood loss volume, and intervention rate at the staple line (including intraoperative pressure, suture, and electrocoagulation) were documented by trained nurses during the surgery. Propensity score matching was performed between the two groups, controlling forage, BMI, smoking history, history of surgery, complications, and level of complexity of pneumonectomy.

RESULTS

A total of 108 matched patients were included in the analysis (54 in the GST group and 54 in the manual group). GST group had lower risks for intraoperative bleeding (22.8% vs 51.9%; p = 0.003) and intraoperative interventions (31.5% vs 55.6%; p = 0.02), compared to the manual group. A decrease in the intraoperative blood loss was observed in the GST group, but not statistically significant (134.39 ± 52.82 ml vs 158.11 ± 73.14 ml, p = 0.102). The use of NEOVEIL (reinforcement material to prevent air leakage from the staple line) intraoperatively during surgery was significantly lower in the GST group (24.1%) than in the manual group (50%, p = 0.01).

CONCLUSION

The GST system was associated with better intraoperative outcomes in clinical practice in China.

Terrestrial runoff influences the transport and contamination levels of Toxoplasma gondii in marine organisms

There is a growing concern regarding the potential adverse impact of Toxoplasma gondii contamination of the marine environment on marine wildlife and public health. Terrestrial runoff is a significant route for dissemination of T. gondii oocysts from land to sea. Yet, the influence of terrestrial runoff on T. gondii prevalence in marine animals in China is largely unknown. To address this concern, we examined the presence of T. gondii in marine oysters Crassostrea spp., rockfish Sebastes schlegelii (S. schlegelii), fat greenling fish Hexagrammos otakii (H. otakii), and Asian paddle crab Charybdis japonica (C. japonica) using a PCR assay targeting T. gondii B1 gene. A total of 1920 samples were randomly collected, in Jan-Dec 2020, from terrestrial runoff areas (TRA, TRB, and TRC) and non-terrestrial runoff area (Grape bay) in Weihai, China. T. gondii prevalence in TRB and TRC was 6.04 % and 5.83 %, respectively, which was higher than 2.29 % detected in the non-terrestrial runoff area. The highest prevalence was detected in Crassostrea spp., and a correlation was observed between T. gondii prevalence and weight of Crassostrea spp. The temperature, but not precipitation, significantly correlated with T. gondii prevalence. Understanding the fate of T. gondii delivered to oceans by terrestrial runoff is critical for predicting future disease risks for marine wildlife and humans.

Essential role of ascO for virulence of Aeromonas veronii and inducing apoptosis

Aeromonas veronii is a significant pathogen that is capable of infecting humans, animals, and aquatic animals. The type III secretion system (T3SS) is intimately associated with bacterial pathogenicity. The ascO gene is an important core component of T3SS in A. veronii, but its function is still unclear. The ascO gene of A. veronii TH0426 was deleted by using the pRE112 suicide plasmid to study its function. The study results showed that the ability of ∆ascO to adhere and invade EPC cells was significantly reduced by 1.28 times. The toxicity of the mutant strain ΔascO to EPC cells was consistently significantly lower than wild-type strain TH0426 at 1, 2, and 4 h. The LD50 values of ∆ascO against zebrafish and Carassius auratus (C. auratus) were 53 and 15 times that of the wild-type strain. In addition, the bacterial load of the mutant strain ΔascO in blood, heart, liver, and spleen was lower than wild-type strain TH0426. The Hoechst staining showed that the apoptotic degree of EPC cells induced by the mutant strain ΔascO was lower than that of the wild-type strain TH0426. Furthermore, real-time quantitative PCR (RT-qPCR) analysis revealed lower expression levels of pro-apoptotic genes (including cytC, cas3, cas9, TNF-α, and IL-1β) in C. auratus tissues infected with the mutant strain ΔascO compared to the wild-type strain TH0426. The results of in vivo and in vitro experiments have shown that ascO gene mutation can reduce the adhesion and toxicity of A. veronii to EPC and reduce the level of apoptosis induced by A. veronii. As a result, these insights will help further elucidate the function of the ascO gene and thus contribute to understanding the pathogenesis of A. veronii.

Global proteomic profiling of multiple organs of cats (Felis catus) and proteome-transcriptome correlation during acute Toxoplasma gondii infection

Background

Toxoplasma gondii is a protozoan parasite which can infect almost all warm-blooded animals and humans. Understanding the differential expression of proteins and transcripts associated with T. gondii infection in its definitive host (cat) may improve our knowledge of how the parasite manipulates the molecular microenvironment of its definitive host. The aim of this study was to explore the global proteomic alterations in the major organs of cats during acute T. gondii infection.

Methods

iTRAQ-based quantitative proteomic profiling was performed on six organs (brain, liver, lung, spleen, heart and small intestine) of cats on day 7 post-infection by cysts of T. gondii PRU strain (Genotype II). Mascot software was used to conduct the student’s t-test. Proteins with P values < 0.05 and fold change > 1.2 or < 0.83 were considered as differentially expressed proteins (DEPs).

Results

A total of 32,657 proteins were identified in the six organs, including 2556 DEPs; of which 1325 were up-regulated and 1231 were down-regulated. The brain, liver, lung, spleen, heart and small intestine exhibited 125 DEPs, 463 DEPs, 255 DEPs, 283 DEPs, 855 DEPs and 575 DEPs, respectively. Gene Ontology (GO) annotation and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analyses of all proteins and DEPs in all organs showed that many proteins were enriched in binding, cell part, cell growth and death, signal transduction, translation, sorting and degradation, extracellular matrix remodeling, tryptophan catabolism, and immune system. Correlations between differentially expressed proteins and transcripts were detected in the liver (n = 19), small intestine (n = 17), heart (n = 9), lung (n = 9) and spleen (n = 3).

Conclusions

The present study identified 2556 DEPs in six cat tissues on day 7 after infection by T. gondii PRU strain, and functional enrichment analyses showed that these DEPs were associated with various cellular and metabolic processes. These findings provide a solid base for further in-depth investigation of the complex proteotranscriptomic reprogramming that mediates the dynamic interplays between T. gondii and the different feline tissues.

Supplementary Information

The online version contains supplementary material available at 10.1186/s40249-022-01022-7.

Investigation of urine metabolome of BALB/c mouse infected with an avirulent strain of Toxoplasma gondii

Background

The protozoan parasite Toxoplasma gondii is a major concern for human and animal health. Although the metabolic understanding of toxoplasmosis has increased in recent years, the analysis of metabolic alterations through noninvasive methodologies in biofluids remains limited.

Methods

Here, we applied liquid chromatography-tandem mass spectrometry (LC-MS/MS)-based metabolomics and multivariate statistical analysis to analyze BALB/c mouse urine collected from acutely infected, chronically infected and control subjects.

Results

In total, we identified 2065 and 1409 metabolites in the positive electrospray ionization (ESI +) mode and ESI − mode, respectively. Metabolomic patterns generated from principal component analysis (PCA) and partial least squares discriminant analysis (PLS-DA) score plots clearly separated T. gondii-infected from uninfected urine samples. Metabolites with altered levels in urine from T. gondii-infected mice revealed changes in pathways related to amino acid metabolism, fatty acid metabolism, and nicotinate and nicotinamide metabolism.

Conclusions

This is the first study to our knowledge on urine metabolic profiling of BALB/c mouse with T. gondii infection. The urine metabolome of infected mouse is distinctive and has value in the understanding of Toxoplasmosis pathogenesis and improvement of treatment.

Graphical Abstract

Supplementary Information

The online version contains supplementary material available at 10.1186/s13071-022-05408-2.

Constant light in early life induces fear-related behavior in chickens with suppressed melatonin secretion and disrupted hippocampal expression of clock- and BDNF-associated genes

Background

Light management plays an important role in the growth and behavior of broiler chickens. Constant light in early post hatch stage has been a common practice in broiler industry for improving growth performance, while whether and how constant light in early life affects the behavior of broiler chickens is rarely reported.

Results

In this study, newly hatched chicks were kept in either constant (24 L:0 D, LL) or (12 L:12 D, LD) photoperiod for 7 d and then maintained in 12 L:12 D thereafter until 21 days of age. Constant light increased the average daily feed intake but not the body weight, which led to higher feed conversion ratio. Chickens in LL group exhibited fear-related behaviors, which was associated with higher corticosterone, lower melatonin and 5-HT levels. Concurrently, constant light exposure increased the mRNA expression of clock-related genes and suppressed the expression of antioxidative genes in the hippocampus. Moreover, brain derived neurotrophic factor/extracellular signal-regulated kinase (BDNF/ERK) pathway was suppressed in the hippocampus of chickens exposed to constant light in the first week post hatching.

Conclusions

These findings indicate that constant light exposure in early life suppress melatonin secretion and disrupts hippocampal expression of genes involved in circadian clock and BDNF/ERK pathway, thereby contributing to fear-related behaviors in the chicken.

Supplementary Information

The online version contains supplementary material available at 10.1186/s40104-022-00720-4.

Toxoplasma gondii Infection in Marine Animal Species, as a Potential Source of Food Contamination: A Systematic Review and Meta-Analysis

PURPOSE

Many marine animals are infected and susceptible to toxoplasmosis, which is considered as a potential transmission source of Toxoplasma gondii to other hosts, especially humans. The current systematic review and meta-analysis aimed to determine the prevalence of T. gondii infection among sea animal species worldwide and highlight the existing gaps.

METHODS

Data collection was systematically done through searching databases, including PubMed, Science Direct, Google Scholar, Scopus, and Web of Science from 1997 to July 2020.

RESULTS

Our search strategy resulted in the retrieval of 55 eligible studies reporting the prevalence of marine T. gondii infection. The highest prevalence belonged to mustelids (sea otter) with 54.8% (95% CI 34.21-74.57) and cetaceans (whale, dolphin, and porpoise) with 30.92% (95% CI 17.85-45.76). The microscopic agglutination test (MAT) with 41 records and indirect immunofluorescence assay (IFA) with 30 records were the most applied diagnostic techniques for T. gondii detection in marine species.

CONCLUSIONS

Our results indicated the geographic distribution and spectrum of infected marine species with T. gondii in different parts of the world. The spread of T. gondii among marine animals can affect the health of humans and other animals; in addition, it is possible that marine mammals act as sentinels of environmental contamination, especially the parasites by consuming water or prey species.

Constant light exposure in early life induces m 6A-mediated inhibition of IGF gene family in the chicken

Insulin-like growth factor (IGF) family plays important roles in regulating the development of various organ systems through stimulating cell proliferation and differentiation. Photoperiod is an important factor affecting growth and development in the chicken, yet the effect of constant light exposure in early life on IGF1 and IGF2 expression in the chicken remains unclear. In this study, one-day-old chickens were kept in either constant light (24L:0D, LL) or natural photoperiod (12L:12D, LD) for the first week of life and then maintained in constant light from 8 d to 21 d of age. Constant light exposure in early life reduced mRNA expression of IGF gene family, including mRNA expression of IGF1, IGF2 and IGF2 binding proteins (IGF2BPs), in the hippocampus, hypothalamus and liver of chickens at both 7 d and 21 d of age. Moreover, constant light exposure increased mRNA expression of genes involved in RNA methylation N6-methyladenosine (m 6A) in a tissue-specific manner. Interestingly, higher m 6A on 3'UTR of IGF2 mRNA coincides with lower IGF2 mRNA, indicating a possible role of m 6A in the post-transcriptional regulation of IGF2 expression in the hippocampus, hypothalamus, and liver of chickens. These findings suggest a m 6A-mediated gene regulation of IGF gene family in different organs of chicken and expand our knowledge on mechanism of gene regulation in response to early life experience.

Design, Synthesis, and Antitumor Activity Study of All-Hydrocarbon-Stapled B1-Leu Peptides

B1-Leu peptide is a structural optimization compound derived from the lysine- and phenylalanine-rich antimicrobial peptide Cathelicidin-BF. It has shown promising antibacterial and antitumor biological activity. However, linear peptides are not the best choice for novel drug development due to their poor pharmacokinetic properties. In this study, various all-hydrocarbon stapled B1-Leu derivatives were designed and synthesized. Their secondary structure, protease stability, and antitumor and hemolytic activities were also investigated to evaluate their clinical value for cancer therapy. Among them, B1-L-3 and B1-L-6 showed both damaging the tumor cell membrane stability and antitumor activity, showing that they are promising lead compounds for the development of novel cancer therapeutics.

Investigation of Antiparasitic Activity of Two Marine Natural Products, Estradiol Benzoate, and Octyl Gallate, on Toxoplasma gondii In Vitro

Toxoplasmosis, caused by Toxoplasma gondii, is a common disease worldwide and could be severe and even fatal in immunocompromised individuals and fetuses. Limitation in current available treatment options drives the need to develop novel therapeutics. This study assessed the anti-T. gondii potential of 103 marine natural products. A luminescence-based β-galactosidase activity assay was used to screen the marine natural products library. Afterward, those compounds that displayed over 70% parasite inhibition ratio were further chosen to assess their cytotoxicity. Compounds exhibiting low cytotoxicity (≥80% cell viability) were applied to evaluate the inhibition efficacy on discrete steps of the T. gondii lytic cycle, including invasion, intracellular growth, and egress abilities as well as the cell cycle. We found that both estradiol benzoate and octyl gallate caused >70% inhibition of tachyzoite growth with IC₅₀ values of 4.41 ± 0.94 and 5.66 ± 0.35 μM, respectively, and displayed low cytotoxicity with TD₅₀ values of 34.11 ± 2.86 and 26.4 ± 0.98 μM, respectively. Despite their defects in inhibition of invasion and egress of tachyzoite, the two compounds markedly inhibited the tachyzoite intracellular replication. Flow cytometric analyses further suggested that the anti-T. gondii activity of estradiol benzoate, rather than octyl gallate, may be linked to halting cell cycle progression of tachyzoite from G1 to S phase. Taken together, these findings suggest that both estradiol benzoate and octyl gallate are potential inhibitors for anti-T. gondii infection and support the further exploration of marine natural products as a thinkable source of alternative and active agents against T. gondii.

Response mechanism of microbial community to seasonal hypoxia in marine ranching

Seasonal hypoxia, as an increasingly recognized environmental issue, frequently occurred in marine ranching from northern Yellow Sea, China. Although microorganisms play an important ecological role in marine ecosystems, but little is known on the response mechanism of microbial community to seasonal hypoxia in marine ranching. A total of 132 seawater samples and 47 sediment samples were collected from the marine ranching, both in the death disaster zone of sea cucumbers and the non-disaster zone, and in different months. 16S rRNA gene high-throughput sequencing was used to explore the microbial community and its influencing factors. The results showed that the stratification in community composition and dissolved oxygen content appeared in August. The Alpha diversity in seawater was higher in summer than in winter, and significant differences in Beta diversity appeared between the death disaster zone of sea cucumbers and the non-disaster zone in sediments. In addition, environmental effects explained more of the variation in bacterial community composition in seawater as compared with spatial effects did, whereas, sedimentary bacterial communities were more closely related to spatial effects. The present results could provide fundamental data for understanding the response mechanism of the microbial community to seasonal hypoxia in marine ranching and are of great significance for the management and protection of marine ranching.

Chronic corticosterone disrupts the circadian rhythm of CRH expression and m6A RNA methylation in the chicken hypothalamus

BACKGROUND

Corticotropin-releasing hormone (CRH), the major secretagogue of the hypothalamic-pituitary-adrenal (HPA) axis, is intricately intertwined with the clock genes to regulate the circadian rhythm of various body functions. N6-methyladenosine (m⁶A) RNA methylation is involved in the regulation of circadian rhythm, yet it remains unknown whether CRH expression and m⁶A modification oscillate with the clock genes in chicken hypothalamus and how the circadian rhythms change under chronic stress.

RESULTS

Chronic exposure to corticosterone (CORT) eliminated the diurnal patterns of plasma CORT and melatonin levels in the chicken. The circadian rhythms of clock genes in hippocampus, hypothalamus and pituitary are all disturbed to different extent in CORT-treated chickens. The most striking changes occur in hypothalamus in which the diurnal fluctuation of CRH mRNA is flattened, together with mRNA of other feeding-related neuropeptides. Interestingly, hypothalamic m⁶A level oscillates in an opposite pattern to CRH mRNA, with lowest m⁶A level after midnight (ZT18) corresponding to the peak of CRH mRNA before dawn (ZT22). CORT diminished the circadian rhythm of m⁶A methylation with significantly increased level at night. Further site-specific m⁶A analysis on 3'UTR of CRH mRNA indicates that higher m⁶A on 3'UTR of CRH mRNA coincides with lower CRH mRNA at night (ZT18 and ZT22).

CONCLUSIONS

Our results indicate that chronic stress disrupts the circadian rhythms of CRH expression in hypothalamus, leading to dysfunction of HPA axis in the chicken. RNA m⁶A modification is involved in the regulation of circadian rhythms in chicken hypothalamus under both basal and chronic stress conditions.

A systematic review, meta-analysis and meta-regression of the global prevalence of Toxoplasma gondii infection in wild marine mammals and associations with epidemiological variables

Toxoplasma gondii infection in wild marine mammals is a growing problem and is associated with adverse impacts on marine animal health and public health. This systematic review, meta-analysis and meta-regression estimates the global prevalence of T. gondii infection in wild marine mammals and analyzes the association between T. gondii infection and epidemiological variables. PubMed, Web of Science, Science Direct, China National Knowledge Infrastructure, and Wanfang Data databases were searched until 30 May 2021. Eighty-four studies (n = 14,931 wild marine mammals from 15 families) were identified from literature. The overall pooled prevalence of T. gondii infection was 22.44% (3,848/14,931; 95% confidence interval (CI): 17.29% - 8.04%). The prevalence in adult animals 21.88% (798/3119; 95% CI: 13.40 -31.59) was higher than in the younger age groups. North America had a higher prevalence 29.92% (2756/9243; 95% CI: 21.77 - 38.77) compared with other continents. At the country level, the highest prevalence was found in Spain 44.26% (19/88; 95%CI: 5.21 - 88.54). Regarding climatic variables, the highest prevalence was found in areas with a mean annual temperature >20°C 36.28% (171/562; 95% CI: 6.36 - 73.61) and areas with an annual precipitation >800 mm 26.92% (1341/5042; 95% CI: 18.20 - 36.59). The subgroup and meta-regression analyses showed that study-level covariates, including age, country, continent, and mean temperature, partly explained the between-study heterogeneity. Further studies are needed to investigate the source of terrestrial to aquatic dissemination of T. gondii oocysts, the fate of this parasite in marine habitat and its effects on wild marine mammals. This article is protected by copyright. All rights reserved.

Waterborne protozoan outbreaks: An update on the global, regional, and national prevalence from 2017 to 2020 and sources of contamination

The aim of this review is to identify the worldwide trend of waterborne protozoan outbreaks and how it varies between geographic regions during the period from 2017 to 2020. Data about waterborne protozoan outbreaks were gathered and stratified by continent, country, water source, and protozoan species associated with the outbreak. The highest prevalence of waterborne protozoan outbreaks was reported in developed countries. Out of 251 outbreaks reported worldwide during the studied period, 141, 51 and 24 outbreaks were recorded in the USA, UK, and New Zealand, respectively. These outbreaks were mainly associated with Cryptosporidium (192 outbreaks) and Giardia (48 outbreaks). Cyclospora cayetanensis, Dientamoebafragilis and Toxoplasma gondii were associated with 7 outbreaks. One outbreak was associated with each of Blastocystis hominis, Entamoeba histolytica, Microsporidia or Naegleria fowleri. This data suggests large discrepancies in the number of outbreaks reported between geographic regions, with most outbreaks recorded in developed countries. Differences in the prevalence of outbreaks between countries are likely attributed to the availability of diagnostic capabilities and surveillance programs to monitor water contamination with pathogenic protozoa. More attention and concerted efforts are required to improve water safety and to alleviate the impact of waterborne protozoan infections. Appropriate surveillance of water contamination with protozoa can enable public health officials to identify source of contamination and implement the necessary measures to limit transmission and prevent outbreaks.

Hydrocarbon stapling modification of peptide alyteserin-2a: Discovery of novel stapled peptide antitumor agents

Alyteserin-2a (ILGKLLSTAAGLLSNL.NH₂ ) is isolated from the skin exudates of midwife toad and has a wide range of biological applications. However, the use of alyteserin-2a as an antitumor agent is limited due to its structural flexibility. In this study, a series of stapled peptides were prepared through hydrocarbon stapling modification without destroying the key residues, and their chemical and biological properties were further evaluated for enhancing the application potential of alyteserin-2a in the field of antitumor drugs development. Among them, alyteserin-2a-Sp3 displayed significant improvement in helicity levels, protease resistance, and antitumor activity compared to that of the template peptide alyteserin-2a, indicating that alyteserin-2a-Sp3 had a potential to become a lead compound for the development of novel antitumor drugs. This study confirms the important effect of hydrocarbon stapling strategy on the secondary structure, hydrolase stability and biological activity of alyteserin-2a.

The Coexistence Relationship Between Plants and Soil Bacteria Based on Interdomain Ecological Network Analysis

The relationship between plants and their associated soil microbial communities plays a crucial role in maintaining ecosystem processes and function. However, identifying these complex relationships is challenging. In this study, we constructed an interdomain ecology network (IDEN) of plant–bacteria based on SparCC pairwise associations using synchronous aboveground plant surveys and belowground microbial 16S rRNA sequencing among four different natural forest types along the climate zones in China. The results found that a total of 48 plants were associated with soil bacteria among these four sites, and soil microbial group associations with specific plant species existed within the observed plant–bacteria coexistence network. Only 0.54% of operational taxonomy units (OTUs) was shared by the four sites, and the proportion of unique OTUs for each site ranged from 43.08 to 76.28%, which occupied a large proportion of soil bacterial community composition. The plant–bacteria network had a distinct modular structure (p < 0.001). The tree Acer tetramerum was identified as the network hubs in the warm temperate coniferous and broad-leaved mixed forests coexistence network and indicates that it may play a key role in stabilizing of the community structure of these forest ecosystems. Therefore, IDEN of plant–bacteria provides a novel perspective for exploring the relationships of interdomain species, and this study provides valuable insights into understanding coexistence between above-ground plants and below-ground microorganisms.

Development of novel bone targeting peptide-drug conjugate of 13-aminomethyl-15-thiomatrine for osteoporosis therapy

13-Aminomethyl-15-thiomatrine (M19) previously developed by our research group was a promising candidate for novel anti-osteoporosis drug development. However, the application of M19 was limited by its unsatisfactory druggability including poor chemical stability, excessively broad pharmacological activity and some degree of cytotoxicity. To solve these problems, M19-based bone targeting and cathepsin K sensitive peptide–drug conjugates (BTM19-1, BTM19-2 and BTM19-3) were developed to realize precise drug release in the bone tissue. Subsequent studies showed a rapid drug release process via cathepsin K digestion but sufficient stability over several hours in chymotrypsin. Besides, greatly improved chemical stability and strong hydroxyapatite binding affinity were also demonstrated. In biological evaluation studies, these PDCs showed less cytotoxicity and similar osteoclast inhibitory activity compared with the prototype drug. The optimal BTM19-2 could serve as a suitable candidate for further osteoporosis therapy research.

13-Aminomethyl-15-thiomatrine (M19) previously developed by our research group was a promising candidate for novel anti-osteoporosis drug development.

Stapled Peptides Targeting SARS-CoV-2 Spike Protein HR1 Inhibit the Fusion of Virus to Its Cell Receptor

The pandemic of acute respiratory disease in 2019 caused by highly pathogenic and infectious SARS-CoV-2 has seriously endangered human public safety. The 6-HB (HR1-HR2 complex) formation occurring in the process of spike protein-mediated membrane fusion could serve as a conserved and potential target for the design of fusion inhibitors. Based on the HR2 domain of 6-HB, we designed and synthesized 32 stapled peptides using an all-hydrocarbon peptide stapling strategy. Owing to the improved proteolytic stability and higher helical contents, the optimized stapled peptides termed SCH2-1-20 and SCH2-1-27 showed better inhibitory activities against pseudo and authentic SARS-CoV-2 compared to the linear counterpart. Of note, SCH2-1-20 and SCH2-1-27 were proved to interfere with S protein-mediated membrane fusion. Structural modeling indicated similar binding modes between SCH2-1-20 and the linear peptide. These optimized stapled peptides could serve as potent fusion inhibitors in treating and preventing SARS-CoV-2, and the corresponding SAR could facilitate further optimization.

Projected impacts of climate change on snow leopard habitat in Qinghai Province, China

Assessing species' vulnerability to climate change is a prerequisite for developing effective strategies to reduce emerging climate-related threats. We used the maximum entropy algorithm (MaxEnt model) to assess potential changes in suitable snow leopard (Panthera uncia) habitat in Qinghai Province, China, under a mild climate change scenario. Our results showed that the area of suitable snow leopard habitat in Qinghai Province was 302,821 km2 under current conditions and 228,997 km2 under the 2050s climatic scenario, with a mean upward shift in elevation of 90 m. At present, nature reserves protect 38.78% of currently suitable habitat and will protect 42.56% of future suitable habitat. Current areas of climate refugia amounted to 212,341 km2 and are mainly distributed in the Sanjiangyuan region, Qilian mountains, and surrounding areas. Our results provide valuable information for formulating strategies to meet future conservation challenges brought on by climate stress. We suggest that conservation efforts in Qinghai Province should focus on protecting areas of climate refugia and on maintaining or building corridors when planning for future species management.

Noggin Overexpression Impairs the Development of Muscles, Tendons, and Aponeurosis in Soft Palates by Disrupting BMP-Smad and Shh-Gli1 Signaling

The roles of bone morphogenetic protein (BMP) signaling in palatogenesis were well documented in the developing hard palate; however, little is known about how BMP signaling regulates the development of soft palate. In this study, we overexpressed Noggin transgene via Osr2-cre ^KI allele to suppress BMP signaling in the developing soft palate. We found that BMP-Smad signaling was detected in the palatal muscles and surrounding mesenchyme. When BMP-Smad signaling was suppressed by the overexpressed Noggin, the soft palatal shelves were reduced in size with the hypoplastic muscles and the extroversive hypophosphatasia (HPP). The downregulated cell proliferation and survival in the Osr2-cre ^KI ;pMes-Noggin soft palates were suggested to result from the repressed Shh transcription and Gli1 activity, implicating that the BMP-Shh-Gli1 network played a similar role in soft palate development as in the hard palate. The downregulated Sox9, Tenascin-C (TnC), and Col1 expression in Osr2-cre ^KI ;pMes-Noggin soft palate indicated the impaired differentiation of the aponeurosis and tendons, which was suggested to result in the hypoplasia of palatal muscles. Intriguingly, in the Myf5-cre ^KI ;pMes-Noggin and the Myf5-cre ^KI ;Rosa26R-DTA soft palates, the hypoplastic or abrogated muscles affected little the fusion of soft palate. Although the Scx, Tnc, and Co1 transcription was significantly repressed in the tenogenic mesenchyme of the Myf5-cre ^KI ;pMes-Noggin soft palate, the Sox9 expression, and the Tnc and Col1 transcription in aponeurosis mesenchyme were almost unaffected. It implicated that the fusion of soft palate was controlled by the mesenchymal clues at the tensor veli palatini (TVP) and levator veli palatini (LVP) levels, but by the myogenic components at the palatopharyngeus (PLP) level.