纳豆菌抗菌肽APNT-6对凡纳滨对虾的低温保鲜效果

研究了一种以抗菌脂肽类物质surfactin、iturin和fengycin为主要成分的新型抗菌肽APNT-6的体外溶血和小鼠口服急性毒性, 为食品应用安全性提供初步评估。将抗菌肽作100倍稀释置于兔血琼脂平板上的牛津杯中观察溶血情况; 结果显示, 经100倍稀释的抗菌肽在体外对血细胞有较强的溶血毒性。将60只小鼠按雌雄各半随机分成6组, 分别以8、40、200、1 000、5 000 mg每千克体重剂量的抗菌肽对小鼠进行一次性灌胃, 7 d内观察小鼠毒性体征并测定相关指标。结果表明, 当小鼠被给予该抗菌肽5 000 mg/kg剂量时, 观察7 d无任何毒性反应, 说明高剂量的抗菌肽经口服在小鼠体内不能达到有效溶血浓度, 其口服半数致死剂量(LD50)大于5 000 mg/kg小鼠体质量, 急性毒性评级属实际无毒级。根据以上结果可知, 新型抗菌肽APNT-6在体外有溶血毒性但经口服对小鼠没有急性毒性作用。     

氨氮对红星梭子蟹早期幼体的急性毒性

在盐度30、pH 8.5、温度28.8～29.8℃、投喂扁藻和轮虫的条件下,设置10、20、40、80、160mg/L共5个氨氮梯度和1个对照组(天然海水),进行了氨氮对红星梭子蟹早期幼体(第Ⅰ期溞状幼体,Z1)的急性毒性试验。结果发现,氨氮暴露12～72h,红星梭子蟹早期幼体活力组间差异显著(P<0.05),当氨氮继续暴露至84～96h,早期幼体活力组间差异不显著(P>0.05);氨氮暴露12～96h,红星梭子蟹早期幼体存活率组间差异显著(P<0.05),但对照组与10mg/L试验组差异不显著(P>0.05);红星梭子蟹早期幼体的氨氮暴露12、24、36h时的半致死质量浓度分别为80.94、27.96、14.43mg/L,红星梭子蟹早期幼体暴露36h的氨氮安全质量浓度为1.44mg/L。     

重组犬α干扰素急性毒性试验研究

为观察小鼠体内重组犬α干扰素急性毒性反应,进行重组犬α干扰素临床安全用药试验。结果表明:在连续观察14 d内,各组小鼠外部表现及行为特征均正常,体温和体重的变化也在正常范围之内,内脏病理解剖无器官病变情况,血液生化指标检查;注射1.0×106IU/只雌性小鼠ALT为(85.2±5.2)U/L,较正常对照组高,其他各组生化指标与对照组相比无显著性差异(P>0.05)。可见,该试验设定的最高剂量1.0×106IU/只及其以下剂量对小白鼠均无明显毒性作用,在临床上应用该重组犬α干扰素是安全的。     

恩诺沙星对鲟鱼的急性毒性研究

将鲟鱼暂养于室内玻璃水族箱内7 d后进行试验,分别用恩诺沙星800、1 000、1 300、1 690、2 200和2 860 mg/kg体重对鲟鱼进行口灌给药,给药后连续10 d观察试验鱼的行为及死亡情况。用改进寇氏法计算鲟鱼口灌恩诺沙星LD50为1 590.36 mg/kg体重,95%可信区间范围为1 172.20～1 803.02 mg/kg体重。     

Pesticide residue analysis and its relationship to hazard characterisation (ADI/ARfD) and intake estimations (NEDI/NESTI)

Over 800 pesticides are currently approved for use in one or more EU countries. The maximum residue levels (MRL) for agricultural pesticides are derived from field trials conducted under good agricultural practice (GAP). The MRL is a legally enforceable limit related to GAP. The results from field trials would only be used to establish MRLs if the estimated intake of residues did not exceed the acceptable daily intake (ADI) or acute reference dose (ARfD). However, the MRL is not linked to the ADI or ARfD, and could result in intakes considerably below the ADI/ARfD. This disconnection between hazard characterisation (ADI/ARfD) and potential exposure assessment (MRL) means that risk characterisation of pesticide residues is less transparent than for other chemicals present in human food. Residue levels at or below the MRL would not give intakes that exceed the ADI/ARfD but, despite this, there is public concern over such residues. Residue levels above the MRL have to be analysed on a case-by-case basis to determine if the intake could exceed the health-based limits. Other causes of public concern, such as the presence of multiple residues, are currently under investigation.     

花粉多糖对小鼠急性毒性预试

花粉多糖对昆明小鼠静脉给药 ,2 5g kg剂量时动物即产生呆滞外 ,无其他异常反应及死亡现象。当剂量提高至 5g kg时 ,动物即时产生蹦厥而死亡。预试结果反映花粉多糖的急性毒性剂量介于 2 5～ 5g kg之间。     

Establishment of Double-antibody Sandwich ELISA to Diagnose Acute Toxoplasmosis

The zoonotic protozoa Toxoplasma gondii is an opportunistic pathogen and distributes worldwide. Acute Toxoplasma infection causes serious pathological damages. Dense granule protein 1(GRA1) secreted by dense granule is an important component of Circulating antigen, which is an indication of acute toxoplasmosis. We aimed to use a monoclonal antibody against TgGRA1 to establish an enzyme-linked immunosorbent assay that targets antigen GRA1 in serum for acute toxoplasmosis diagnosis. First, the spleens of TgGRA1-His immunized mice were fused with SP2/0 cells,then we screened hybridomas that can constantly secret monoclonal antibody to the supernatant and injected them into mice to produce a large amount of mAbs. After the identification and purification of ascites, we choose one mAb as a capture antibody, HRP conjugated mouse anti-TgGRA1 polyclonal antibody as a detection antibody to develop sandwich ELISA. This method was used to detect samples from swine and mice artificially infected with Toxoplasma gondii. Besides, the results were compared with that of nPCR and two commercial kits to evaluate the efficiency of sandwich ELISA. We successfully got 4 mAbs with ascitic titers of 10⁶-10⁷, their subtypes are IgG1. Indirect fluorescent assay and Western blot showed that all of them can react specifically with TgGRA1.1G2 mAb and HRP conjugated mouse anti-TgGRA1 polyclonal antibody were used subsequently to establish sandwich ELISA for diagnosing acute infection. After optimization, sandwich ELISA can specifically detect 1.563 ng·mL^-1 GRA1 or 100 ng·mL^-1 ESA in serum. When detecting experimental animal samples, the sandwich ELISA exhibited the high consistency with the results of nPCR and showed higher efficiency than the commercial kits. In summary, we established a sandwich ELISA for acute toxoplasmosis diagnosis that captures one certain toxoplasma antigen GRA1, samples of artificially infected animals can be detected by this method, which makes acute toxoplasmosis diagnosis more reliable. It has guiding significance for clinical treatment of acute toxoplasmosis.     

Research Advances on Porcine Emerging Coronaviruses

Currently, corona virus disease 2019 (COVID-19) caused by SARS-CoV-2 is still raging worldwide, which attracts great concern about coronavirus originated from animal. Porcine deltacoronavirus (PDCoV) and swine acute diarrhea syndrome coronavirus (SADS-CoV) are newly discovered porcine coronaviruses in recent years, they not only damage pig industry severely but also pose potential threats to public health. This article reviews the literature concerning the etiology, origin and evolution, pathogenicity, and diagnostics of PDCoV and SADS-CoV, presenting the prospect of research work. We aim to expand understanding on SARS-CoV-2 and provide references for subsequent research on PDCoV and SADS-CoV.     

马杜拉霉素联合尼卡巴嗪的抗球虫效果与毒性试验

选用２１日龄雏鸡，人工感染柔嫩艾美尔球虫（Ｅｉｍｅｒｉａｔｅｎｅｌａ），用马杜拉霉素尼卡巴嗪按一定比例混合，按６５ｍｇ／ｋｇ比例混入饲料中饲喂。结果表明其推荐剂量的抗球虫指数在两批试验中分别为１９２６８与１９３４２，属高效。急性毒性试验，该混合剂约ＬＤ５０，对小白鼠和鸡分别为７３６ｍｇ／ｋｇ与５１５２８ｍｇ／ｋｇ，均属低毒。     

"棘防E号"的安全性评价

90只小白鼠随机分为9组每组10只。除对照组外,其余8组分别以绵羊每日正常用药量的1．5^u等比级数递增剂量,一次给小白鼠灌服定量“棘防E号”,连续观察14天,以测定“棘防E号”对小白鼠口服的LD50。同时,按最大无作用剂量(101.25mg／BW、正常剂量(20．00mg／kg.BW、最大无作用剂量的1／30(3．375mg／kg．BW)给小白鼠饮用“棘防E号”,观察对小白鼠繁殖机能的影响。结果表明,当小白鼠服用绵羊正常用药量的17倍时,不出现半数死亡,说明“棘防E号”对小白鼠的LD50大于绵羊正常用药量的10倍,是完全安全性的药物;最大无作用剂量、正常剂量、最大无作用剂量的1／30对小白鼠怀孕率和胎儿畸形与对照组没有明显的区别。