Establishment of human cerebral organoid systems to model early neural development and assess the central neurotoxicity of environmental toxins

Human brain development is a complex process,and animal models often have significant limitations.To address this,researchers have developed pluripotent stem cell-derived three-dimensional structures,known as brain-like organoids,to more accurately model early human brain development and disease.To enable more consistent and intuitive reproduction of early brain development,in this study,we incorporated forebrain organoid culture technology into the traditional unguided method of brain organoid culture.This involved embedding organoids in matrigel for only 7 days during the rapid expansion phase of the neural epithelium and then removing them from the matrigel for further cultivation,resulting in a new type of human brain organoid system.This cerebral organoid system replicated the temporospatial characteristics of early human brain development,including neuroepithelium derivation,neural progenitor cell production and maintenance,neuron differentiation and migration,and cortical layer patterning and formation,providing more consistent and reproducible organoids for developmental modeling and toxicology testing.As a proof of concept,we applied the heavy metal cadmium to this newly improved organoid system to test whether it could be used to evaluate the neurotoxicity of environmental toxins.Brain organoids exposed to cadmium for 7 or 14 days manifested severe damage and abnormalities in their neurodevelopmental patterns,including bursts of cortical cell death and premature differentiation.Cadmium exposure caused progressive depletion of neural progenitor cells and loss of organoid integrity,accompanied by compensatory cell proliferation at ectopic locations.The convenience,flexibility,and controllability of this newly developed organoid platform make it a powerful and affordable alternative to animal models for use in neurodevelopmental,neurological,and neurotoxicological studies.

Botulinum toxin type A in treating early-stage patients with small-angle acute acquired comitant esotropia

AIM:To investigate botulinum toxin A(BTXA)efficacy on small-angle(≤25Δ)acute acquired concomitant esotropia(AACE)in early-stage patients.METHODS:The electronic medical record data of AACE patients during March 2019 and June 2023 were collected in this retrospective and hospital-based cohort study.A total of 72 small-angle AACE patients received BTXA extraocular muscle injection.Patients were grouped by onset-to-treatment time(Group A:≤6mo,Group B:>6mo).Deviation of esotropia,eye alignment and stereopsis were analyzed at the period of pre/post-injection(1wk,1,3,and 6mo).Orthophoria rate at 6mo(horizontal deviation<10Δand binocular single vision)were considered as outcome index.RESULTS:There were no significant baseline differences(P>0.05)between two groups except onset-to-treatment time(2mo vs 11mo,P<0.001).Higher orthophoria rates were in Group A at last follow-up(94.74%vs 73.53%,P=0.013).Post-BTXA deviations of two groups at 1mo showed no difference(P>0.05);while in 3 and 6mo Group A was significantly smaller than group B(all P<0.001).No statistically significant differences were observed among all post-BTXA deviations of near and distance in Group A.In Group B,deviation at 3mo(near:2Δvs 0,P<0.001;distance:4Δvs 0,P<0.001)and 6mo(near:6Δvs 0,P<0.001;distance:6Δvs 0,P<0.001)was significant increased compared to deviation at 1wk after treatment.Group A showed better stereopsis recovery in last follow-up compared to Group B(80″vs 200″,P=0.002).Both groups obtained improved stereopsis after treatment(Group A:80″vs 300″,P<0.001;Group B:200″vs 300″,P=0.037).CONCLUSION:BTXA is effective for AACE with small deviation(≤25Δ)in early stage.Delayed treatment(>6mo)may reduce BTXA efficacy.Early BTXA intervention benefits long-term eye alignment and stereopsis recovery.

Betulinic acid protects against ovarian impairment by decreasing F-2 toxin-induced oxidative stress and inflammation associated with the downregulation of p38 expression in mice

F-2 toxin is an estrogenic mycotoxin that causes reproductive disorders in animals.Betulinic acid(BA)is a natural pentacyclic lupane-structure triterpenoid that has diverse pharmacological activities.In this study,the antioxidative and anti-inflammatory effects of BA and its underlying mechanism are explored in F-2 toxin-triggered mouse ovarian damage.We found that BA alleviated the F-2 toxin-induced ovarian impairment by stimulating follicle growth,reducing inflammatory cell infiltration,repairing damaged mitochondria and endoplasmic reticulum.Simultaneously,BA not only reversed F-2 toxin-induced reduction of follicle stimulating hormone(FSH)and luteinizing hormone(LH)levels in the serum,but also restrained the protein expression of the estrogen receptors a(ERa)and ERβ.Moreover,BA restored the balance of F-2 toxin-induced ovarian redox system disorders.Subsequently,we found that 0.25 mg/kg BA played an anti-inflammatory role in the F-2 toxin-induced ovarian impairment by decreasing interleukin-1β(IL-1β).IL-6,and tumor necrosis factor-α(TNF-α)mRNA expression,as well as inhibiting p38 protein expression.These data demonstrated that BA exerts its protective effect on F-2 toxin-induced ovarian oxidative impairment and inflammation by inhibiting p38 expression,which implies a natural product-based medicine to ameliorate F-2 toxin-caused female reproductive toxicity and provides a detoxifying method for food contaminated by mycotoxin.

Clinical effect of botulinum toxin type A combined with autologous fat grafting in patients with nasolabial fold depression

BACKGROUND Nasolabial fold(NLF)depression can affect the facial appearance of patients to some extent and increase their psychological burdens.In recent years,autologous fat grafting(AFG)combined with botulinum toxin A(BTX-A)injection(AFG+BTX-A injection)has been gradually applied in the treatment of patients with NLF depression.Although studies have been conducted on the efficacy and safety of AFG+BTX-A injection in treating NLF depression,the experimental design,observational indicators,and sample enrollment criteria vary remarkably,making it difficult to draw convincing and consistent conclusions.Thus,further relevant research is warranted.AIM To assess the esthetic improvement,efficacy,and safety of AFG+BTX-A injections in patients with NLF depression.METHODS This study included 60 patients with NLF depression who were treated in our hospital from February 2019 to April 2021.These patients were categorized into control(n=30)and observation(n=30)groups.The observation group received AFG+BTX-A injection,whereas the control group underwent AFG only.All patients were evaluated using the wrinkle severity rating scale(WSRS)and global aesthetic improvement scale.The compactness of facial contours,skin evaluation indexes,adverse reactions,and satisfaction of the two groups were evaluated 3 months postoperatively.RESULTS The WSRS scores of the observation group at 1,3,and 6 months postoperatively were lower than those of the control group(P<0.05).Three months postoperatively,facial fine lines and pores showed obvious improvement and the skin index score was higher in the observation group than in the control group(P<0.05).The compactness of facial contours was better in the observation group than in the control group(P<0.05).In addition,no remarkable differences were noted in the incidence of postoperative adverse reactions such as facial stiffness,facial asymmetry,facial bruising,and facial concavity inequality(P>0.05).CONCLUSION AFG+BTX-A injection is a highly safe,cost-effective,effective,and long-lasting treatment for NLF depression with high esthetic value,which should be promoted in the future.

Botulinum toxin type A-targeted SPP1 contributes to neuropathic pain by the activation of microglia pyroptosis

BACKGROUND Neuropathic pain(NP)is the primary symptom of various neurological condi-tions.Patients with NP often experience mood disorders,particularly depression and anxiety,that can severely affect their normal lives.Microglial cells are as-sociated with NP.Excessive inflammatory responses,especially the secretion of large amounts of pro-inflammatory cytokines,ultimately lead to neuroinflam-mation.Microglial pyroptosis is a newly discovered form of inflammatory cell death associated with immune responses and inflammation-related diseases of the central nervous system.METHODS Two models,an in vitro lipopolysaccharide(LPS)-stimulated microglial cell model and a selective nerve injury model using BTX-A and SPP1 knockdown treatments,were used.Key proteins in the pyroptosis signaling pathway,NLRP3-GSDMD,were assessed using western blotting,real-time quantitative polymerase chain reaction,and immunofluorescence.Inflammatory factors[interleukin(IL)-6,IL-1β,and tumor necrosis factor(TNF)-α]were assessed using enzyme-linked immuno-sorbent assay.We also evaluated microglial cell proliferation and apoptosis.Furthermore,we measured pain sensation by assessing the delayed hind paw withdrawal latency using thermal stimulation.RESULTS The expression levels of ACS and GSDMD-N and the mRNA expression of TNF-α,IL-6,and IL-1βwere enhanced in LPS-treated microglia.Furthermore,SPP1 expression was also induced in LPS-treated microglia.Notably,BTX-A inhibited SPP1 mRNA and protein expression in the LPS-treated microglia.Additionally,depletion of SPP1 or BTX-A inhibited cell viability and induced apoptosis in LPS-treated microglia,whereas co-treatment with BTX-A enhanced the effect of SPP1 short hairpin(sh)RNA in LPS-treated microglia.Finally,SPP1 depletion or BTX-A treatment reduced the levels of GSDMD-N,NLPRP3,and ASC and suppressed the production of inflammatory factors.CONCLUSION Notably,BTX-A therapy and SPP1 shRNA enhance microglial proliferation and apoptosis and inhibit microglial death.It improves pain perception and inhibits microglial activation in rats with selective nerve pain.

Botulinum toxin type A injection combined with biofeedback in the treatment of spastic pelvic floor syndrome

BACKGROUND Spastic pelvic floor syndrome(SPFS)is a refractory pelvic floor disease characterized by abnormal(uncoordinated)contractions of the external anal sphincter and puborectalis muscle during defecation,resulting in rectal emptation and obstructive constipation.The clinical manifestations of SPFS are mainly characterized by difficult defecation,often accompanied by a sense of anal blockage and drooping.Manual defecation is usually needed during defecation.From physical examination,it is commonly observed that the patient's anal muscle tension is high,and it is difficult or even impossible to enter with his fingers.AIM To investigate the characteristics of anorectal pressure and botulinum toxin A injection combined with biofeedback in treating pelvic floor muscle spasm syndrome.METHODS Retrospective analysis of 50 patients diagnosed with pelvic floor spasm syndrome.All patients underwent pelvic floor surface electromyography assessment,anorectal dynamics examination,botulinum toxin type A injection 100 U intramuscular injection,and two cycles of biofeedback therapy.RESULTS After the botulinum toxin A injection combined with two cycles of biofeedback therapy,the patient's postoperative resting and systolic blood pressure were significantly lower than before surgery(P<0.05).Moreover,the electromyography index of the patients in the resting stage and post-resting stages was significantly lower than before surgery(P<0.05).CONCLUSION Botulinum toxin A injection combined with biofeedback can significantly reduce pelvic floor muscle tension in treating pelvic floor muscle spasm syndrome.Anorectal manometry is an effective method to evaluate the efficacy of treatment objectively.However,randomized controlled trials are needed.

Dermal thickness,rather than drug concentration and injection speed,influences the effective area of botulinum toxin type A in the dermis

Background:Recently,microbotulinum,a new technique that involves injecting botulinum toxin type A(BoNTA)microdroplets into superficial cutaneous tissue,has gained popularity.The precise distribution of BoNTA in the targeted area profoundly affects outcomes.Many factors may influence the effective area of BoNTA in the dermis.This study aimed to determine the dermal distribution properties of BoNTA to guide microbotulinum injection.Methods:Ten healthy males aged 18–65 years without BoNTA treatment in the previous year were recruited to receive intradermal injections in the chest and back.Ultrasound was used to ensure the intradermal delivery of injections and measure the dermal thickness.The minor iodine starch test was performed at baseline and 3 days,7 days,21 days,1 month,and 2 months after treatment.Results:All participants received intradermal injections.The dermis was thinner on the chest(thickness,0.20±0.03 cm)than on the back(thickness,0.39±0.07 cm)(P<0.05).An injection in the thicker dermis had a significantly smaller effective area at every follow-up visit.The drug concentration did not affect the effective area except at 3 days after treatment.Injection speed did not influence the effective area at any follow-up visits.Conclusion:An injection in a thicker dermis leads to a smaller effective area for intradermal injections.When the BoNTA dose is the same,the drug concentration and injection speed do not matter.

Botulinum toxin type A for treating chronic low back pain:A double blinded randomized control study

BACKGROUND Low back pain(LBP)is a prevalent issue that orthopedic surgeons frequently address in the outpatient setting.LBP can arise from various causes,with stiffness in the paraspinal muscles being a notable contributor.The administration of Botulinum toxin type A(BoNT-A)has been found to alleviate back pain by relaxing these stiff muscles.While BoNT-A is approved for use in numerous conditions,a limited number of randomized clinical trials(RCTs)validate its efficacy specifically for treating LBP.AIM To study the safety and the efficacy of BoNT-A in minimizing pain and improving functional outcomes in patients of chronic LBP(CLBP).METHODS In this RCT,adults aged 18-60 years with mechanical LBP persisting for at least six months were enrolled.Participants were allocated to either the Drug group,receiving 200 Ipsen Units(2 mL)of BoNT-A,or the Control group,which received a 2 mL placebo.Over a 2-month follow-up period,both groups were assessed using the Visual Analog Scale(VAS)for pain intensity and the Oswestry Disability Index(ODI)for disability at the start and conclusion of the study.A decrease in pain by 50%was deemed clinically significant.RESULTS The study followed 40 patients for two months,with 20 in each group.A clinically significant reduction in pain was observed in 36 participants.There was a statistically significant decrease in both VAS and ODI scores in the groups at the end of two months.Nonetheless,when comparing the mean score changes,only the reduction in ODI scores(15 in the placebo group vs 16.5 in the drug group,clinically insignificant)was statistically significant(P=0.012),whereas the change in mean VAS scores was not significant(P=0.45).CONCLUSION The study concludes that BoNT-A does not offer a short-term advantage over placebo in reducing pain or improving LBP scores in CLBP patients.

Severe Botulism after Intragastric Botulinum Toxin-A Injection: A Case Series

Intragastric botulismus toxin-A (BoNT-A) is one of the new approaches in the treatment of obesity. We aimed to contribute to the literature by presenting the clinical features, laboratory findings and treatment responses of iatrogenic botulism cases due to intragastric BoNT-A administered in our clinic. All detailed medical information was obtained by accessing the medical records of the patients who were hospitalized and followed up and treated between September 2022 and December 2022, and the diagnosis of A.05.1 Botulism was entered according to ICD-10, and whose clinical findings were compatible with botulism disease and who underwent intragastric BoNT-A application beforehand. These records were obtained by examining this information. 10 patients who developed botulism after intragastric BoNT-A application between 01/09/2022 and 28/02/2023 were followed up in our clinic. All of the patients were women. The mean age was 35. The mean hospital stay was 9 days. Only 1 of our cases required intensive care. Good response to treatment was accepted as a complete or near-complete improvement in the clinical findings of the patients and all of them had a good response to treatment. Intragastric BoNT-A administration is a procedure that requires careful indication with a profit/loss calculation considering the potential side effects. In addition, attention should be paid to dilution rates and dose amounts.

Increase of β -1, 3-Glucanase and Chitinase Activities in Cotton Callus Cells Treated by Salicylic Acid and Toxin of Verticillium dahliae

The different resistance of cotton (Gossypium hirsutum L.) cultivars to crude toxin of Verticillium dah/iae(VD) was correlated with the activities of chitinase and β-1, 3-glucanase in callus cells. The activities of chitinase and β-1, 3-glucanase in the callus cells treated with the VD-toxin were increased to the higher level at earlier time point in resistant cultivars than these in the susceptible cultivars. Exogenous salicylic acid (SA) induced the accumulation of chitinase and β -1,3-glucanase, which resulted in the resistance of callus cells to the VD. toxin. Western blot using a polyclonal antibody against β -1,3-glucanase identified 28 kD protein that was induced by VD-toxin, SA, or VD-toxin plus SA.

Global Challenges and Solutions in the Early Warning,Monitoring and Toxicity Assessment of Biotoxins in the Food and Feed Chain

There is a massive and urgent need to ensure safety and security of the food supply of the world´s growing population.However,global agriculture and food industries continue to be vulnerable to problems of contamination with biotoxins produced by plants,algae and particularly by fungi;with global warming and extreme weather events making the occurrence of these toxic metabolites even more unpredictable.In this paper we summarize the multidisciplinary,multi-sectoral complementary competencies needed to innovate in various scientific fields and approaches,so strongly needed to develop improved early warning,monitoring and toxicity assessment of biotoxins in the food and feed chain.These include big data approaches using satellite and drone images,portable monitoring devices and(combined)toxicity testing of(emerging)biotoxins using proteomics and transcriptomics.

虾夷扇贝毒素yessotoxins(YTXs),中国沿海贝类中首次发现的一组贝类生物毒素

采用高效液相色谱-串联质谱方法对我国近海贝类中腹泻性贝毒成分进行研究,结果发现采自北黄海大连附近海域的海湾扇贝和虾夷扇贝含有25~41μg/kg的虾夷扇贝毒素（yessotoxin,YTX）,在虾夷扇贝体内还含有37.2μg/kg的45-OH-YTX,并在5种贝中发现微量的Homo-YTX毒素组分,这是首次报道在我国贝中检出此类毒素。虾夷扇贝毒素YTXs是一类含有2个磺酰基的脂溶性多环聚醚类化合物,对小鼠的腹腔注射急性致死毒性很高,毒理作用机制尚不清楚。本研究的结果说明我国贝类体内生物毒素成分复杂,亟需进行毒素成分结构、来源生物、生态毒理效应、分布规律及安全限定标准的研究。

Preliminary Study on the Extraction of Crude Toxin of Rhizoctonia solani and Its Activity

[ Objective] This study was to investigate the pathogenic mechanism of rice sheath blight pathogen （ Rhizoctonia solani） and the bioactive components of toxin. [ Method ] Rice sheath blight pathogen was cultured in the improved Richared medium; the culture filtrate was centrifuged and sterilized, then treated by activated carbon adsorption chromatography, distilled with methanol or water, and all were next concentrated, yielding the crude extracts of culture solution, crude extracts of methanol and crude extracts of water; the activities of these three extracts were determined, [ Result] The three extracts were russet pastes; activity determination showed that they had remarkable inhibitory effects on the growth of rice radicle and plantule, as well as the growth of four-foliage-young seedlings. They could also generate toxic effects on abscisic foliages and spots similar to the symptoms of sheath blight pathogen. [ Conclusion] Bioactive components of rice sheath blight pathogen toxin may be composed of various ingredients.

金黄色葡萄球菌α-toxin(Hla)促进皮肤组织中IL-19表达上调的作用机制研究

目的探究金黄色葡萄球菌α-toxin(Hla)促进皮肤组织中IL-19表达上调的作用机制。方法采用WT S.Aureus、△Hla S.aureus(Hla缺失菌株)以及PBS感染Balb/c小鼠背部皮肤,收集感染后第1、3、7天的皮肤组织,HE染色检测组织炎性病理损伤,q RT-PCR和ELISA分别检测IL-19、IL-1β的m RNA和蛋白水平的表达。分离小鼠骨髓的中性粒细胞,分别用WT S.Aureus、△Hla S.aureus以及meida(不含菌液的培养基)刺激6 h后,q RT-PCR、ELISA和Western blot检测IL-1β的表达。不同浓度IL-1β刺激角质形成细胞PAM 2-12后,q RT-PCR和ELISA分别检测IL-19的表达。结果△Hla S.aureus组与WT S.aureus组相比,其皮肤损伤的面积减小,炎性细胞浸润和脓肿形成减少。同时q RT-PCR和ELISA检测发现,△Hla S.aureus组与WT S.aureus组相比,IL-19的m RNA和蛋白表达水平显著降低(P<0.01)。体外中性粒细胞刺激发现,△Hla S.aureus组与WTS.aureus组相比,IL-1β蛋白表达水平显著降低(P<0.01)。体外IL-1β刺激角质形成细胞PAM 2-12发现,与不刺激组相比,IL-19的m RNA和蛋白表达水平显著增加(P<0.01),并呈剂量依赖性。结论金黄色葡萄球菌分泌的α-toxin能够作用于中性粒细胞,促进了IL-1β的表达,IL-1β的过表达作用于皮肤的角质形成细胞,从而促进了IL-19的上调,可能参与了银屑病的发生与发展。

Gene therapy for human colorectal carcinoma using human CEA promoter controlled bacterial ADP-ribosylating toxin genes:PEA and DTA gene transfer

AIM To establish a tissue-specific gene therapy for colorectal carcinoma using bacterial ADP-ribosylating toxin genes.METHODS Pseudomonas exotoxin A domain Ⅱ+Ⅲ (PEA) was cloned from genomic DNA of Pseudomonas aeruginosa. PEA and diphtheria toxin A chain gene (DTA) were modified to express eukaryotically. After sequencing, the toxin genes under the control of human carcinoembryonic antigen (CEA) promoter were cloned into retroviral vectors to construct CEAPEA and CEADTA respectively. In vitro cotransfection of the constructs with luciferase vectors and in vivo gene transfer in nude mice were subsequently carried out.RESULTS Both CEAPEA and CEADTA specifically inhibited the reporter gene expression in the CEA positive human colorectal carcinoma (CRC) cells in vitro. Direct injection of CEAPEA and CEADTA constructs into the established human tumors in BALB/c nude mice led to significant and selective reductions in CRC tumor size as compared with that in control groups.CONCLUSION The toxin genes, working as therapeutic genes, are suitable for the tissue-specific gene therapy for colorectal carcinoma.

Transfer of Paralytic Shellfish Toxins via Marine Food Chains:A Simulated Experiment

Objective To study the transfer of paralytic shellfish toxins （PST） using four simulated marine food chains： dinoflagellate Alexandrium tamarense→Artemia Artemia salina→Mysid shrimp Neomysis awatschensis; A. tamarense→N. awatschensis; A. tamarense→A, salina→Perch Lateolabrax japonicus; and A. tamarense→L, japonicus. Methods The ingestion of A. tamarense, a producer of PST, by L. japonicus, N. awatschensis, and A. salina was first confirmed by microscopic observation of A. tamarense cells in the intestine samples of the three different organisms, and by the analysis of Chl.a levels in the samples. Toxin accumulation in L. japonicus and N. awatschensis directly from the feeding on A. tamarense or indirectly through the vector of A. salina was then studied, The toxicity of samples was measured using the AOAC mouse bioassay method, and the toxin content and profile of A. tamarense were analyzed by the HPLC method. Results Both A. salina and N. awatschensis could ingest A. tamarense cells. However, the ingestion capability of A. salina exceeded that of N. awatschensis. After the exposure to the culture of A. tamarense （2 000 cells·mL^-1） for 70 minutes, the content of Chl.a in A. salina and N. awatschensis reached 0.87 and 0.024 μg.mg^-1, respectively. Besides, A. tamarense cells existed in the intestines of L. japonicus, N. awatschensis and A. salina by microscopic observation. Therefore, the three organisms could ingest A. tamarense cells directly. A. salina could accumulate high content of PST, and the toxicity of A. salina in samples collected on days 1, 4, and 5 of the experiment was 2.18, 2.6, and 2.1 MU.g^-1, respectively. All extracts from the samples could lead to death of tested mice within 7 minutes, and the toxin content in anemia sample collected on the 1st day was estimated to be 1.65×10 ^5 μg STX equal/individual. Toxin accumulation in L japonicus and N. awatschensis directly from the feeding on A. tamarense or indirectly from the vector ofA. salina was also studied. The mice injected with extracts from L japonicus and N. awatschensis samples that accumulated PST either directly or indirectly showed PST intoxication symptoms, indicating that low levels of PST existed in these samples. Conclusion Paralytic shellfish toxins can be transferred to L. japonicus, N. awatschensis, and A. salina from A. tamarense directly or indirectly via the food chains.

Effect of Antibiotic Treatment on Toxin Production by Alexandrium tamarense

Objective Impact of the presence of bacteria associated with a marine dinoflagellate, Alexandrium tamarense CI01, on the growth and toxin production of the algae in batch culture was investigated. Methods Pronounced changes in the activities of the algal culture were observed when the culture was treated with different doses of a mixture of penicillin and streptomycin. Results In the presence of antibiotics at the initial concentration of 100 u/mL in culture medium, both algal growth and toxin yield increased markedly. When the concentration of antibiotics was increased to 500 u/mL, the microalgal growth was inhibited, but resumed in a few days to eventually reach the same level of growth and toxin production as at the lower dose of the antibiotics. When the antibiotics were present at a concentration of 1 000 u/mL, the algal growth was inhibited permanently. Conclusions The results indicate that antibiotics can enhance algal growth and toxin production not only through their inhibition of the growth and hence competition for nutrients, but also through their effects on the physiology of the algae.

Comparison of T-2 Toxin and HT-2 Toxin Distributed in the Skeletal System with That in Other Tissues of Rats by Acute Toxicity Test

Twelve healthy rats were divided into the T-2 toxin group receiving gavage of 1 mg/kg T-2 toxin and the control group receiving gavage of normal saline. Total relative concentrations of T-2 toxin and HT-2 toxin in the skeletal system（thighbone, knee joints, and costal cartilage） were significantly higher than those in the heart, liver, and kidneys（P 〈 0.05）. The relative concentrations of T-2 toxin and HT-2 toxin in the skeletal system（thighbone and costal cartilage） were also significantly higher than those in the heart, liver, and kidneys. The rats administered T-2 toxin showed rapid metabolism compared with that in rats administered HT-2 toxin, and the metabolic conversion rates in the different tissues were 68.20%-90.70%.

重组蜈蚣抗昆虫神经毒素rScolotoxin-Ssm2b对家蚕的经口急性毒性

以家蚕为模式昆虫,进行重组蜈蚣抗昆虫神经毒素r Scolotoxin-Ssm2b的经口急性毒性试验。采用叶片涂抹法分别给2龄起蚕添食质量浓度为0.625、1.250、2.500、5.000、10.000μg/m L的r Scolotoxin-Ssm2b,添食24 h测定的LC50值为4.84μg/m L。幼虫添食质量浓度为5.000μg/m L的r Scolotoxin-Ssm2b后2~5 min,出现口吐消化液、头胸部左右大幅摇摆、躯体扭曲、胸部膨大、头部突出、侧翻倒地等明显的中毒症状;添食后2 h,约80%的幼虫死亡。研究结果表明r Scolotoxin-Ssm2b对家蚕具有经口急性毒性,证明其有口服杀虫活性。

Establishment and Application of a Real-time PCR Method for Detecting stx2 Gene in Shiga Toxin-producing Escherichia coli(STEC)

[Objective] This study aimed to establish a real-time PCR method for de- tecting stx2 gene in Shiga toxin-producing E. coli （STEC）. [Method] According to the known STEC stx2 gene sequences published in GenBank, PCR primers and probes were designed based on the conserved region to construct recombinant plasmid as a positive template, thus optimizing the reaction conditions and establishing the real- time PCR method. [Result] A standard curve was established based on the opti- mized real-time PCR system, indicting a good linear correlation between the initial template concentration and Ct value, with the correlation coefficient F^e of above 0.995. The established method had a good specificity, without non-specific amplifica- tion for 10 non-STEC intestinal bacterial strains; the detection limit of initial template was 1.0x102 copies/μI, indicating a high sensitivity; furthermore, the coefficients of variation within and among batches were lower than 1% and 5% respectively, sug- gesting a good repeatability. [Conclusion] In this study, a real-time PCR method was successfully established for detecting STEC stx2 gene, which provided technical means for rapid detection of STEC in samples.