Development of a Safe and Effective Bacillus thuringiensis-Based Nanobiopesticide for Controlling Tea Pests.

Mg(OH)2 was used as the nanocarrier of the Bacillus thuringiensis (Bt) Cry1Ac protein, and the synthesized Cry1Ac-Mg(OH)2 composites were regular and uniform nanosheets. Nano-Mg(OH)2 could effectively improve the insecticidal effect of the Cry1Ac protein toward Ectropis obliqua. It could enhance the damage degree of the Cry1Ac protein to intestinal epithelial cells and microvilli, induce and enrich the production of reactive oxygen species (ROS) in the midgut, and enhance the degradation of the Cry1Ac protein into active fragments. Furthermore, an anti-rinsing assay showed that the Cry1Ac-Mg(OH)2 composites were bound to the notch structure of the tea leaf surface. The retention of the Cry1Ac protein increased by 11.45%, and sprayed nano-Mg(OH)2 was rapidly absorbed by different tissues of tea plants. Moreover, nano-Mg(OH)2 and composites did not significantly affect non-target organisms. These results show that nano-Mg(OH)2 can serve as a safe and effective biopesticide carrier, which provides a new approach for stable and efficient Bt preparation.

Urea Cycle of Bacillus thuringiensis Affects Its Survival under UV Stress.

Bacillus thuringiensis (Bt) is widely used to produce biological pesticides. However, its persistence is limited because of ultraviolet (UV) rays. In our previous study, we found that exogenous intermediates of the urea cycle were beneficial to Bt for survival under UV stress. To further explore the effect of the urea cycle on the resistance mechanism of Bt, the rocF/argG gene, encoding arginase and argininosuccinate synthase, respectively, were knocked out and recovered in this study. After the target genes were removed, respectively, the urea cycle in the tested Bt was inhibited to varying degrees. The UV stress test showed that the urea cycle disorder could reduce the resistance of Bt under UV stress. Meanwhile, the antioxidant enzyme activities of Bt were also decreased to varying degrees due to the knockout of the target genes. All of these results revealed that the urea cycle can metabolically regulate the stress resistance of Bt.

N-Terminal α-Helices in Domain I of Bacillus thuringiensis Vip3Aa Play Crucial Roles in Disruption of Liposomal Membrane.

Bacillus thuringiensis Vip3 toxins form a tetrameric structure crucial for their insecticidal activity. Each Vip3Aa monomer comprises five domains. Interaction of the first four α-helices in domain I with the target cellular membrane was proposed to be a key step before pore formation. In this study, four N-terminal α-helix-deleted truncations of Vip3Aa were produced and, it was found that they lost both liposome permeability and insecticidal activity against Spodoptera litura. To further probe the role of domain I in membrane permeation, the full-length domain I and the fragments of N-terminal α-helix-truncated domain I were fused to green fluorescent protein (GFP), respectively. Only the fusion carrying the full-length domain I exhibited permeability against artificial liposomes. In addition, seven Vip3Aa-Cry1Ac fusions were also constructed by combination of α-helices from Vip3Aa domains I and II with the domains II and III of Cry1Ac. Five of the seven combinations were determined to show membrane permeability in artificial liposomes. However, none of the Vip3Aa-Cry1Ac combinations exhibited insecticidal activity due to the significant reduction in proteolytic stability. These results indicated that the N-terminal helix α1 in the Vip3Aa domain I is essential for both insecticidal activity and liposome permeability and that domain I of Vip3Aa preserved a high liposome permeability independently from domains II-V.

Impacts of UV radiation on Bacillus biocontrol agents and their resistance mechanisms.

Bacillus biocontrol agent(s) BCA(s) such as Bacillus cereus, Bacillus thuringiensis and Bacillus subtilis have been widely applied to control insects' pests of plants and pathogenic microbes, improve plant growth, and facilitate their resistance to environmental stresses. In the last decade, researchers have shown that, the application of Bacillus biocontrol agent(s) BCA(s) optimized agricultural production yield, and reduced disease risks in some crops. However, these bacteria encountered various abiotic stresses, among which ultraviolet (UV) radiation severely decrease their efficiency. Researchers have identified several strategies by which Bacillus biocontrol agents resist the negative effects of UV radiation, including transcriptional response, UV mutagenesis, biochemical and artificial means (addition of protective agents). These strategies are governed by distinct pathways, triggered by UV radiation. Herein, the impact of UV radiation on Bacillus biocontrol agent(s) BCA(s) and their mechanisms of resistance were discussed.

Bo's abdominal acupuncture improves disordered metabolism in obese type 2 diabetic rats through regulating fibroblast growth factor 21 and its related adipokines.

OBJECTIVE: To investigate the effect of Bo's abdominal acupuncture (BOAA) on fibroblast growth factor 21 (FGF21) and its related adipokines in type 2 diabetes mellitus (T2DM) rats. METHODS: This study established obese T2DM rat model by high-fat diet (HFD) with a dose of streptozotocin (STZ, 30 mg/kg). Obese T2DM rats were randomly subdivided into four groups (n = 10): negative, BOAA, conventional acupuncture (COA group) and metformin group (Met group) groups. The biochemical parameters, mRNAs, and proteins were analyzed using enzyme-lined immunoassays kits, quantitative polymerase chain reaction and Western blot. RESULTS: Treatment with BOAA attenuated the histopathological changes in visceral fat and restored the alterations in the levels of body weight, fasting blood glucose (FBG), homeostasis model assessment for insulin resistance (HOMA-IR). BOAA treatment significantly decreased the levels of triglyceride, total cholesterol, low density lipoprotein cholesterol, leptin, and increased the serum levels of high-density lipoprotein cholesterol, fibroblast growth factor 21 (FGF21), adiponectin (ADP), peroxisome proliferator-activated receptor γ (PPAR-γ), C-peptide (C-P) in obese T2DM rats. Furthermore, BOAA treatment significantly increased the mRNA expressions of FGF21, ADP, leptin, PPAR-γ, PPAR-α and adenosine 5'-monophosphate (AMP)-activated protein kinase (AMPK). Besides, BOAA treatment upregulated the protein expressions of fibroblast growth factor receptors3 (FGFR3), PPAR-α, extracellular signal-regulated kinase (ERK), phosphorylated ERK (p-ERK), AMPK, p-AMPK, Liver kinase B1 (LKB1), phosphorylated LKB1 (p-LKB1), acetyl-CoA carboxylase (ACC) and phosphorylated ACC (p-ACC), while downregulated the protein expressions of FGF21 and PPAR-γ in visceral fat. CONCLUSIONS: BOAA treatment reduced FBG and body weight, and improved insulin sensitivity through regulating FGF21 signaling pathway and its related adipokine in obese T2DM rats.

Design, Synthesis and Antifungal Activities of Novel Pyrazole Analogues Containing the Aryl Trifluoromethoxy Group.

On the basis of the three-component synthetic methodology developed by us, a total of twenty-six pyrazole compounds bearing aryl OCF3 were designed and synthesized. Their chemical structures were characterized by 1H and 13C nuclear magnetic resonance and high-resolution mass spectrometry. These compounds were evaluated systematically for antifungal activities in vitro against six plant pathogenic fungi by the mycelium growth rate method. Most of the compounds showed some activity against each of the fungi at 100 µg/mL. Compounds 1t and 1v exhibited higher activity against all the tested fungi, and 1v displayed the highest activity against F. graminearum with an EC50 value of 0.0530 µM, which was comparable with commercial pyraclostrobin. Structure-activity relationship analysis showed that, with respect to the R1 substituent, the straight chain or cycloalkyl ring moiety was a key structural moiety for the activity, and the R2 substituent on the pyrazole ring could have significant effects on the activity. Simple and readily available pyrazoles with potent antifungal activity were obtained, which are ready for further elaboration to serve as a pharmacophore in new potential antifungal agents.

[Application of meridian and acupoint diagnosis of three yin meridians of foot in the treatment for gynecological diseases with acupuncture and moxibustion].

With three representative types of gynecological diseases (dysmenorrhea, pelvic inflammation, polycystic ovary syndrome) as examples, the application methods of meridian and acupoint diagnosis for gynecological diseases treated with acupuncture and moxibustion are discussed. During clinical diagnosis and treatment, it is recommended to examine the patient's leg segment along the three yin meridians of foot, aiming to explore the positive reactions of the meridians and acupoints (color, shape, skin temperature, sensory abnormalities, etc.). Acupuncture and moxibustion treatment at this positive reaction place can improve the clinical efficacy. Meridian and acupoint diagnosis could provide basis for meridian syndrome differentiation, thus guiding the selection of acupoint prescriptions; it is also helpful to clarify the deficiency, excess, cold and heat of the disease nature, thus guiding the selection of acupuncture and moxibustion methods. In addition, it is an auxiliary method to estimate the prognosis and outcome of the disease.

ROS-mediated TCA cycle is greatly related to the UV resistance of Bacillus thuringiensis.

Bacillus thuringiensis (Bt) is a popular and environment-friendly biopesticide. However, similar to other microbial pesticides, Bt is limited by ultraviolet (UV) radiation during its application, which greatly reduces its toxicity and persistence. To further know the mechanism of Bt against UV radiation, metabolomic profiles between Bt LLP29 and its UV-resistant mutant LLP29-M19 were compared, analyzed, and annotated in this study, and then a total of 61 metabolites with different abundances were detected. With P < 0.05 as the standard, a total of 12 metabolic pathways were enriched, including the TCA cycle. According to the result of RT-qPCR, the expression levels of the TCA cycle key genes in Bt LL29-M19, such as icd1 citZ, citB, sdhA, sdhB, sdhC, fumA, and mdh, were found down-regulated for 85.58%, 37.02%, 70.87%, 85.97%, 76.33%, 83.15%, 87.28%, and 35.77% than those in Bt LLP29. It was consistent with the down-regulation trend of the TCA cycle key enzymes activity in Bt LLP29-M19. Consistently, the enzyme activities of ICDH, SDH, and PDH in LLP29-M19 were detected 86.28%, 43.93%, and 83.03% lower than those in Bt LLP29. It was revealed that the reduced TCA cycle was required for Bt UV radiation resistance, which was also demonstrated by the addition of inhibitors furfural and malonic acid, respectively. Based on the result of RT-qPCR, the gene transcription levels of the main reactive oxygen species (ROS) generation pathways were down-regulated, such as EMP, however, the activity of the main degrading enzymes was up-regulated, which showed the reduction of ROS generation rate was a way for the TCA cycle to regulate the anti-ultraviolet resistance of Bt. All of these provide solid evidence for reprogramming metabolomics to strengthen Bt UV radiation resistance.

Whole Genome Resequencing Revealed the Effect of Helicase yqhH Gene on Regulating Bacillus thuringiensis LLP29 against Ultraviolet Radiation Stress.

Bacillus thuringiensis (Bt) is a widely used microbial pesticide. However, its duration of effectiveness is greatly shortened due to the irradiation of ultraviolet rays, which seriously hinders the application of Bt preparations. Therefore, it is of great importance to study the resistance mechanism of Bt to UV at the molecular level to improve the UV-resistance of Bt strains. In order to know the functional genes in the UV resistance, the genome of UV-induced mutant Bt LLP29-M19 was re-sequenced and compared with the original strain Bt LLP29. It was shown that there were 1318 SNPs, 31 InDels, and 206 SV between the mutant strain and the original strain Bt LLP29 after UV irradiation, which were then analyzed for gene annotation. Additionally, a mutated gene named yqhH, a member of helicase superfamily II, was detected as an important candidate. Then, yqhH was expressed and purified successfully. Through the result of the enzymatic activity in vitro, yqhH was found to have ATP hydrolase and helicase activities. In order to further verify its function, the yqhH gene was knocked out and complemented by homologous recombinant gene knockout technology. The survival rate of the knockout mutant strain Bt LLP29-ΔyqhH was significantly lower than that of the original strain Bt LLP29 and the back-complemented strain Bt LLP29-ΔyqhH-R after treated with UV. Meanwhile, the total helicase activity was not significantly different on whether Bt carried yqhH or not. All of these greatly enrich important molecular mechanisms of Bt when it is in UV stress.

[Acupuncture for prevention of moderate to severe seasonal allergic rhinitis: a randomized controlled trial].

OBJECTIVE: To observe the clinical efficacy of acupuncture for prevention of moderate to severe seasonal allergic rhinitis. METHODS: A total of 105 patients with moderate to severe seasonal allergic rhinitis were randomly divided into an observation group (53 cases, 3 cases dropped off) and a control group (52 cases, 4 cases dropped off). The patients in the observation group were treated with acupuncture at Yintang (GV 24+), Yingxiang (LI 20), Hegu (LI 4), Zusanli (ST 36), Fengchi (GB 20), Feishu (BL 13), etc. 4 weeks before the seizure period, once every other day, 3 times a week for 4 weeks. The patients in the control group were not given any intervention before the seizure period. Emergency drugs can be given appropriately during the seizure period in both groups. After seizure period, the seizure rate was recorded in the two groups; before treatment and on week 1, 2, 4, 6 of seizure period after treatment, the rhinoconjunctivitis quality of life questionnaire (RQLQ) score and total nasal symptom score (TNSS) were observed in the two groups; the rescue medication score (RMS) was recorded on week 1-6 of seizure period in the two groups. RESULTS: The seizure rate of the observation group was 84.0% (42/50), which was lower than 100.0% (48/48) in the control group (P<0.05). After treatment, the scores of RQLQ and TNSS at each time point of seizure period were decreased compared with before treatment in the observation group (P<0.01), which were lower than the control group (P<0.01). The RMS score at each time point of seizure period in the observation group was lower than the control group (P<0.05, P<0.01). CONCLUSION: Acupuncture can reduce the incidence of moderate to severe seasonal allergic rhinitis, relieve the symptoms, improve the quality of life and reduce the use of emergency drugs.

Towards Sustainable Green Adjuvants for Microbial Pesticides: Recent Progress, Upcoming Challenges, and Future Perspectives.

Microbial pesticides can be significantly improved by adjuvants. At present, microbial pesticide formulations are mainly wettable powders and suspension concentrations, which are usually produced with adjuvants such as surfactants, carriers, protective agents, and nutritional adjuvants. Surfactants can improve the tension between liquid pesticides and crop surfaces, resulting in stronger permeability and wettability of the formulations. Carriers are inert components of loaded or diluted pesticides, which can control the release of active components at appropriate times. Protective agents are able to help microorganisms to resist in adverse environments. Nutritional adjuvants are used to provide nutrients for microorganisms in microbial pesticides. Most of the adjuvants used in microbial pesticides still refer to those of chemical pesticides. However, some adjuvants may have harmful effects on non-target organisms and ecological environments. Herein, in order to promote research and improvement of microbial pesticides, the types of microbial pesticide formulations were briefly reviewed, and research progress of adjuvants and their applications in microbial pesticides were highlighted, the challenges and the future perspectives towards sustainable green adjuvants of microbial pesticides were also discussed in this review.

Mesoporous Silica Nanoparticles Induce Intracellular Peroxidation Damage of Phytophthora infestans: A New Type of Green Fungicide for Late Blight Control.

Nanopesticides are considered to be a promising alternative strategy for enhancing bioactivity and delaying the development of pathogen resistance to pesticides. Here, a new type of nanosilica fungicide was proposed and demonstrated to control late blight by inducing intracellular peroxidation damage to Phytophthora infestans, the pathogen associated with potato late blight. Results indicated that the structural features of different silica nanoparticles were largely responsible for their antimicrobial activities. Mesoporous silica nanoparticles (MSNs) exhibited the highest antimicrobial activity with a 98.02% inhibition rate of P. infestans, causing oxidative stress responses and cell structure damage in P. infestans. For the first time, MSNs were found to selectively induce spontaneous excess production of intracellular reactive oxygen species in pathogenic cells, including hydroxyl radicals (•OH), superoxide radicals (•O2-), and singlet oxygen (1O2), leading to peroxidation damage in P. infestans. The effectiveness of MSNs was further tested in the pot experiments as well as leaf and tuber infection, and successful control of potato late blight was achieved with high plant compatibility and safety. This work provides new insights into the antimicrobial mechanism of nanosilica and highlights the use of nanoparticles for controlling late blight with green and highly efficient nanofungicides.

Effect of yhfS gene on Bt LLP29 antioxidant and UV ray resistance.

BACKGROUND: Bacillus thuringiensis (Bt) is a widely used microbial insecticide. However, its persistence is limited because of ultraviolet (UV) rays or other environmental factors. The yhfS gene, which encodes acetyl-CoA acyltransferase, plays an important role in lipid transport and metabolism in many organisms. To explore whether it is related to the stress resistance of Bt LLP29, the yhfS gene knockout strain LLP29 Δ-yhfS and the complementary strain LLP29 R-yhfS were generated successfully by homologous recombination technology, and the related phenotypic changes were compared in this study. RESULTS: Gene yhfS was found to be functional in response to UV radiation in Bt by comparing the survival rates of Bt LLP29 harboring yhfS or not under UV light. Enzyme activity assays of key enzymes showed the the Embden-Meyerhof-Parnas pathway was enhanced yet the tricarboxylic acid cycle as well as butanoate synthesis were repressed when the gene was deleted. At the same time, the amino acid content was decreased, but reduced nicotinamide adenine dinucleotide (NADH) and reactive oxygen species (ROS) content were increased. Most noteworthy, antioxidase (such as superoxide dismutase and peroxidase) activities and contents of some potent antioxidants (such as pyruvate, carotenoids and NADPH) were lower in LLP29 Δ-yhfS than in LLP29. CONCLUSION: These tests revealed that the loss of the yhfS gene led to metabolic disorders and reduction of the antioxidant ability of Bt. Higher ROS level and lower anti-oxidative capacity might be responsible for the reduced UV resistance when the gene was deleted. These results not only greatly enrich understanding of the mechanism of Bt UV resistance, but also provide an important theoretical basis for Bt application. © 2023 Society of Chemical Industry.

Removal of an Aminopeptidase N From Midgut Brush Border Does Not Affect Susceptibility of Spodoptera litura (Lepidoptera: Noctuidae) Larvae to Four Insecticidal Proteins of Bacillus thuringiensis (Bacillales: Bacillaceae).

Spodoptera litura is one of the most destructive lepidopteran insects of cabbages and cauliflowers in the world. Cry1 and Vip3 toxins from Bacillus thuringiensis have been reported to show toxicity in multiple lepidopteran insects. Binding of toxic molecules to specific receptors on the midgut epithelial cells is known to be a key step in the action mode of Bt toxins. Aminopeptidase N (APN) -like proteins have been reported to be binding sites of multiple Cry toxins in the midgut of Cry susceptible insects. In the present study, we identified six midgut APNs by analysis of the genome and midgut transcriptome of S. litura. CRISPR/Cas9 mediated gene-knockout system was utilized to mutate the GPI-anchor signal peptide at the C terminus of SlAPN1. SlAPN1 was verified to be removed from the midgut brush border membrane vesicles of a homozygous knockout strain of S. litura (SlAPN1-KO). Bioassay results indicated that susceptibility of the SlAPN1-KO strain to Cry1Aa, Cry1Ac, Cry1Ca, and Vip3Aa toxins was close to that of the wild-type strain of S. litura. RT-qPCR results showed that the transcriptional level of SlAPN2-6 was not up-regulated after knockout of the SlAPN1. Results in this study indicated that the SlAPN1 did not play a critical role in the pathway of toxicity of Cry1Aa, Cry1Ac, Cry1Ca, and Vip3Aa toxins in S. litura.

Acupuncture for prevention of moderate to severe seasonal allergic rhinitis: a randomized controlled trial / 中国针灸

OBJECTIVE@#To observe the clinical efficacy of acupuncture for prevention of moderate to severe seasonal allergic rhinitis.@*METHODS@#A total of 105 patients with moderate to severe seasonal allergic rhinitis were randomly divided into an observation group (53 cases, 3 cases dropped off) and a control group (52 cases, 4 cases dropped off). The patients in the observation group were treated with acupuncture at Yintang (GV 24+), Yingxiang (LI 20), Hegu (LI 4), Zusanli (ST 36), Fengchi (GB 20), Feishu (BL 13), etc. 4 weeks before the seizure period, once every other day, 3 times a week for 4 weeks. The patients in the control group were not given any intervention before the seizure period. Emergency drugs can be given appropriately during the seizure period in both groups. After seizure period, the seizure rate was recorded in the two groups; before treatment and on week 1, 2, 4, 6 of seizure period after treatment, the rhinoconjunctivitis quality of life questionnaire (RQLQ) score and total nasal symptom score (TNSS) were observed in the two groups; the rescue medication score (RMS) was recorded on week 1-6 of seizure period in the two groups.@*RESULTS@#The seizure rate of the observation group was 84.0% (42/50), which was lower than 100.0% (48/48) in the control group (P<0.05). After treatment, the scores of RQLQ and TNSS at each time point of seizure period were decreased compared with before treatment in the observation group (P<0.01), which were lower than the control group (P<0.01). The RMS score at each time point of seizure period in the observation group was lower than the control group (P<0.05, P<0.01).@*CONCLUSION@#Acupuncture can reduce the incidence of moderate to severe seasonal allergic rhinitis, relieve the symptoms, improve the quality of life and reduce the use of emergency drugs.

Application of meridian and acupoint diagnosis of three yin meridians of foot in the treatment for gynecological diseases with acupuncture and moxibustion / 中国针灸

With three representative types of gynecological diseases (dysmenorrhea, pelvic inflammation, polycystic ovary syndrome) as examples, the application methods of meridian and acupoint diagnosis for gynecological diseases treated with acupuncture and moxibustion are discussed. During clinical diagnosis and treatment, it is recommended to examine the patient's leg segment along the three yin meridians of foot, aiming to explore the positive reactions of the meridians and acupoints (color, shape, skin temperature, sensory abnormalities, etc.). Acupuncture and moxibustion treatment at this positive reaction place can improve the clinical efficacy. Meridian and acupoint diagnosis could provide basis for meridian syndrome differentiation, thus guiding the selection of acupoint prescriptions; it is also helpful to clarify the deficiency, excess, cold and heat of the disease nature, thus guiding the selection of acupuncture and moxibustion methods. In addition, it is an auxiliary method to estimate the prognosis and outcome of the disease.

Topical Application of Chinese Formula Yeliangen Promotes Wound Healing in Streptozotocin-Induced Diabetic Rats.

Diabetic wound is one of the most severe complications of diabetes mellitus (DM). Despite the associated risks of wound healing impairment in diabetes, treatment strategies remain limited. Yeliangen (YLG) is a Chinese formulation mainly composed of the rhizome of Coptis chinensis, the root of Isatis tinctoria, and the leaf of Isatis indigotica. We investigated the wound healing effects of YLG in type 2 diabetic (T2DM) rats, which were induced by intraperitoneal administration of streptozotocin after a high-fat diet for four weeks. 3 × 3 cm2 full-thickness excisional wounds were created on the dorsal surface of rats and then divided to control (DC), negative (DPJ), positive (DPC), and YLG-treated (DYLG) groups. Rat's wounds were treated twice daily for 21 days. Wound area and wound contraction were detected on days 0, 3, 7, 14, and 21. Histopathological examinations were performed by H&E staining and immunohistochemistry (IHC). The biochemical parameters, mRNAs, and protein expressions were analyzed through enzyme-linked immunoassays (ELISA), qPCR, and western blot, respectively. Compared with other groups, the histological changes of wound tissue in the DYLG group were improved, and the expressions of CD31, eNOS, and PCNA were significantly upregulated. Besides, YLG significantly reduced the inflammatory factors' expressions of TNF-α, NF-κB, MMP-9, and IL-1B on days 7, 14, and 21 postwounding. Moreover, YLG induced angiogenesis and neovascularization by significantly increasing the levels of VEGF, TGF-ß1, EGF, PDGF, and SDF-1α on days 3, 7, and 14. In conclusion, YLG improved wound healing by reducing inflammation and increasing angiogenesis which may provide an alternative and effective approach for diabetic wound therapy.

Cloning and Characterization of a Novel Endo-Type Metal-Independent Alginate Lyase from the Marine Bacteria Vibrio sp. Ni1.

The applications of alginate lyase are diverse, but efficient commercial enzymes are still unavailable. In this study, a novel alginate lyase with high activity was obtained from the marine bacteria Vibrio sp. Ni1. The ORF of the algB gene has 1824 bp, encoding 607 amino acids. Homology analysis shows that AlgB belongs to the PL7 family. There are two catalytic domains with the typical region of QIH found in AlgB. The purified recombinant enzyme of AlgB shows highest activity at 35 °C, pH 8.0, and 50 mmol/L Tris-HCl without any metal ions. Only K+ slightly enhances the activity, while Fe2+ and Cu2+ strongly inhibit the activity. The AlgB preferred polyM as substrate. The end products of enzymatic mixture are DP2 and DP3, without any metal ion to assist them. This enzyme has good industrial application prospects.

Function of CTLGA9 Amino Acid Residue Leucine-6 in Modulating Cry Toxicity.

Aedes aegypti is a crucial vector for many arboviral diseases that cause millions of deaths worldwide and thus is of major public health concern. Crystal (Cry) proteins, which are toxins produced by Bacillus thuringiensis, are structurally organized into three-domains, of which domain II is the most variable in terms of binding towards various toxin receptors. The binding of Cry11Aa to putative receptor such as aminopeptidase-N (APN) is explicitly inhibited by midgut C-type lectins (CTLs). The similarity between the domain II fold of Cry11Aa toxin and the carbohydrate recognition domain in the CTLs is a possible structural basis for the involvement of Cry domain II in the recognition of carbohydrates on toxin receptors. In this study, a site-directed point mutation was introduced into the A. aegypti CTLGA9 gene on the basis of molecular docking findings, leading to substitution of the Leucine-6 (Leu-6) residue in the protein with alanine. Subsequently, functional monitoring of the mutated protein was carried out. Unlike the amino acid residues of wild-type CTLGA9, none of the residues of mutant (m) CTLGA9 were competed with Cry11Aa for binding to the APN receptor interface. Additionally, ligand blot analysis showed that both wild-type and mutant CTLGA9 had similar abilities to bind to APN and Cry11Aa. Furthermore, in the competitive ELISA in which labeled mutant CTLGA9 (10 nM) was mixed with increasing concentrations of unlabeled Cry11Aa (0-500 nM), the mutant showed no competition with Cry11Aa for binding to APN., By contrast, in the positive control sample of labeled wild type CTLGA9 mixed with same concentrations of Cry11Aa competition between the two ligands for binding to the APN was evident. These results suggest that Leucine-6 may be the key site involved in the competitive receptor binding between CTLGA9 and Cry11Aa. Moreover, according to the bioassay results, mutant CTLGA9 could in fact enhance the toxicity of Cry11Aa. Our novel findings provide further insights into the mechanism of Cry toxicity as well as a theoretical basis for enhancing the mosquitocidal activity of these toxin through molecular modification strategies.

WWP2 overexpression inhibits the antitumor effects of doxorubicin in hepatocellular carcinoma.

Hepatocellular carcinoma (HCC) is a common liver cancer that accounts for 90% of cases. Doxorubicin exhibits a broad spectrum of antitumor activity and is one of the most active agents in HCC. WW domain-containing protein 2 (WWP2) is highly expressed in HCC tissues and activates protein kinase B (AKT) signaling pathway to enhance tumor metastasis. However, the role of WWP2 in the glycolysis and antitumor effects of doxorubicin and the epigenetic alterations of WWP2 in HCC remain to be elucidated. The levels of WWP2 and N6-methyladenosine methyltransferase-like 3 (METTL3) in clinical samples and cells were investigated. WWP2 were silenced or overexpressed to study the role of WWP2 in regulating cell proliferation, colony formation, and glycolysis. RNA immunoprecipitation was performed to test m6 A levels. Quantitative reverse-transcription polymerase chain reaction (RT-PCR) and Western blot were used to measure mRNA and protein, respectively. WWP2 silencing inhibits cell proliferation, colony formation, and glycolysis, while WWP2 overexpression has the inverse effects via the AKT signaling pathway. Silencing WWP2 enhances doxorubicin's antitumor effect, while WWP2 overexpression suppresses doxorubicin's antitumor effect. Data also support that METTL3 mediates WWP2 m6A modification, and m6A reader, IGF2BP2, binds to the methylated WWP2 to promote the stability of WWP2, leading to upregulation of WWP2. METTL3 mediates WWP2 m6A modification, which can be recognized and bound by IGF2BP2 to increase the stability of WWP2, leading to WWP2 overexpression which inhibits the antitumor effects of doxorubicin through METTL3/WWP2/AKT/glycolysis axis.