抑制黄瓜疫病生防菌株LY-38的发酵条件优化

为了对防治黄瓜疫病的生防菌株LY-38的产业化生产提供参考,通过单因子试验和正交试验,对培养基组分中最佳碳源、氮源和无机盐进行筛选,在确定适合该菌株的培养基组分基础上,对其培养条件进行优化。结果表明:适合枯草芽孢杆菌生防菌株LY-38拮抗物质产生的最佳碳源为葡萄糖和玉米淀粉,最佳氮源为蛋白胨和黄豆粉,含量为葡萄糖1.0%、玉米淀粉0.5%、蛋白胨1.0%和黄豆粉2.0%;最佳无机盐为MgSO4·7H2O和CaCO3;最佳培养温度为32℃、培养时间为44h、初始pH 7.2、接种量为3.0%(体积分数)、转速为150r/min。在优化后的培养基成分和培养条件下,LY-38菌株发酵滤液的拮抗圈直径可达21.2mm,比基础培养基的拮抗圈直径提高41.3%。     

肌注和口灌氟苯尼考在吉富罗非鱼体内的药代动力学

通过肌内注射、口灌两种给药方式,研究氟苯尼考在罗非鱼体内的药物代谢动力学特征。把吉富罗非鱼(GIFT Oreochromis niloticus)随机分成2组,控制水温在30℃,以15 mg/kg分别单剂量肌内注射、口灌给药。经高效液相色谱法(HPLC)测定血浆中氟苯尼考浓度,用Win Nonlin药动学软件分析药动学参数。结果表明:肌内注射氟苯尼考后,药物吸收较慢,消除较快,达峰时间(T_(max))=4 h,峰浓度(C_(max))=4.64μg/mL,消除半衰期(T_(1/2λ)z L)=10.45 h,药-时曲线下面积(AUC)=91.06μg·h/mL。口灌氟苯尼考后,药物吸收较快,消除较慢,T_(max)=1 h,C_(max)=5.92μg/mL,T_(1/2λ)z L=13.13 h,AUC=61.96μg·h/mL。肌内注射、口灌氟苯尼考后,二者的药动学参数差异显著,这一差异表明肌内注射给药吸收相对较慢,但更为完全(肌内注射氟苯尼考的AUC明显较大),消除相对较快。     

酶制剂在水产养殖饲料中的应用

1 酶制剂(酶、酵素)的概念 酶制剂是由一种或多种可以分解饲料营养分子链的生物活性物质组成的微量添加剂.它可降解饲料中各营养组分的分子链,或者改变动物消化道内酶系的组成,促进消化,大幅度提高饲料效率,促进动物生长.酶制剂的探索性应用已有多年,但是作为商品酶制剂应用到实际生产上只是近年的事.     

亚硝态氮胁迫下凡纳滨对虾体内亚硝态氮的积累与能量代谢响应

为探究亚硝态氮胁迫下凡纳滨对虾[体长为(6.8±0.3) cm,体质量为(4.0±0.6) g]体内亚硝态氮的时空分布与能量代谢相关酶活性的响应,实验设置0(对照组)、0.8、4.0和8.0 mmol/L 4个处理组,进行持续96 h的亚硝态氮胁迫实验和12 h的恢复实验。结果显示,凡纳滨对虾死亡率与胁迫浓度呈现显著的正相关性。胁迫6 h内,亚硝态氮在凡纳滨对虾鳃、血淋巴、肠道、肝胰腺和肌肉组织中明显积累,且积累量与胁迫浓度呈现正相关。相同胁迫浓度组,亚硝态氮在对虾鳃中积累最多,肌肉中最少,鳃中的积累量约为肌肉的3倍。Na⁺-K⁺-ATP酶活性在0.8和4.0 mmol/L组对虾肝胰腺和肌肉中显著升高,而在8.0 mmol/L组的肌肉中显著降低。胁迫各组对虾肝胰腺AMPK活性显著上升,且与胁迫浓度呈现正相关性。恢复期间,除血淋巴(8.0 mmol/L组)外,各组织中亚硝态氮1 h恢复效率均超过50%,且肝胰腺和鳃的恢复效率最高,达到74%以上。血淋巴、鳃、肠道中亚硝态氮恢复到对照组水平的时间最短,均在6 h以内,而水体中亚硝态氮含量显著升高。...     

小熊猫源犬瘟热病毒株H、F基因的克隆及序列分析

为了解1株圈养小熊猫源犬瘟热病毒(CDV) GD-1的遗传变异情况,通过RT-PCR方法对该株CDV进行H、F基因的克隆、测序及序列分析.结果 显示:该分离株的H基因序列与GenBank中丹麦报道的登录号为GU266280的犬源CDV毒株的核苷酸序列相似性最高,为96％;F基因序列与巴西报道的登录号为KY057355的...     

不同施氮量下干旱胁迫对棉花生长及种内关系的影响

土壤水分和氮肥是影响荒漠绿洲区作物生长和种内关系的主要因素。为明确不同施氮量下干旱胁迫对棉花产量以及种内关系的影响,本研究以集群栽培(1穴3株)下棉花为研究对象,设置3种施氮量[300 kg(N)·hm~(-2)、225 kg(N)·hm~(-2)、150 kg(N)·hm~(-2)]和3种水分处理(正常水分、中度干旱胁迫、重度干旱胁迫),测定了不同处理下棉花的生长指标和棉花产量,分析了不同处理下棉花种内关系的变化。结果表明:1)同一施肥条件下,2016年和2017年棉花株高在重度干旱胁迫下显著降低,而茎粗随干旱胁迫加剧显著降低,但叶面积随干旱胁迫加剧却有所增加,且在中度干旱胁迫下的叶面积最大。2)同一施肥条件下,与正常水分相比,中度和重度干旱胁迫下棉花的茎秆生物量均显著下降;叶片生物量和籽棉产量在中度干旱胁迫下最高,在重度干旱胁迫下却降低。3)在当地施氮量300kg·hm~(-2)下,随着干旱胁迫的加剧,相对邻体效应(relativeneighbor effect, RNE)数值从正值变为负值;在氮肥减少处理(225 kg·hm~(-2))下,随着干旱胁迫的加剧, RNE数值先升高后降低,而在施氮量为150 kg·hm~(-2)处理下, RNE数值随着干旱的加剧逐渐降低,且均为负值。总之,在当地施氮量和中度干旱胁迫下棉花能够获得较高的籽棉产量,且在此处理下棉花的种内关系为助长关系;其他处理均降低了棉花的产量,并使得棉花的种内关系转变为竞争关系。     

Inhibitory effect of ischemic postconditioning on autophagy induced by focal cerebral ischemia reperfusion in rats

AIM: To investigate the effect of ischemic postconditioning (IPC) on autophagy induced by focal cerebral ischemia reperfusion (I/R) in rats. METHODS: Healthy male SD rats were assigned randomly into sham-operation (sham) group, I/R group and IPC group with 10 rats in each group. The rats in sham group were only exposed the right common, internal and external carotid artery surgically. The rats in I/R group were subjected to right middle cerebral artery occlusion (MCAO) by the modified Longa suture method for 2 h followed by 24 h of reperfusion. The rats in IPC group were subjected to MCAO for 2 h followed by reperfusion of the ipsilateral common carotid artery occlusion for 10 s for 5 episodes, and then reperfusion for 24 h. Autophagy was obeserved by transmission electron microscopy (TEM). The protein levels of mammalian target of rapamycin (mTOR), p-mTOR and microtubule associated protein light chain 3 (LC3)-II in brain tissue of the rats were determined by Western blot. Pathological changes of brain tissue were observed by HE staining. RESULTS: The protein levels of mTOR and p-mTOR in IPC group were significantly higher than those in I/R group (P<0.05). The expression of LC3-II in IPC group was significantly lower than that in I/R group (P<0.01). The cerebral infarction area and brain water content in IPC group were significantly lower than those in I/R group (P<0.01). HE staining showed that neurons degeneration and necrosis in IPC group were significantly alleviated compared with I/R group. TEM observation showed that IPC revealed fewer autophagosomes, with much less severe cell damage than that in I/R group. CONCLUSION: IPC reduces brain ischemia reperfusion damage by decreasing autophagy of brain cells, which might be related to the activation of mTOR.     

间接ELISA检测禽多杀性巴氏杆菌抗体中包被抗原的选择

间接ELISA已在抗体检测中广泛应用,而抗原包被作为间接ELISA中必不可少的一步可直接影响试验的准确性。本试验分别使用超声波裂解抗原、脂多糖蛋白抗原和全茵抗原作为包被抗原,建立相应的检测方法并进行重复性试验。试验证明全菌抗原建立的禽多杀性巴氏杆菌ELISA检测方法在敏感度、特异性、稳定性方面均优于其他两种抗原。     

模糊控制的半主动空气悬架

首先搭建了空气悬架1/4车辆模型试验台,通过比较悬架3个性能指标的试验和仿真,其结果基本吻合,说明建立的1/4车辆模型是正确的。然后建立1/4半主动空气悬架的模糊控制模型,并对其进行仿真分析,结果表明模糊控制的半主动空气悬架在提高车辆乘坐舒适性和降低轮胎动载荷方面效果明显。     

Promoting effects of activated Nodal signal pathway on definitive endoderm induction from mouse embryonic stem cells

AIM: To study the process of promoting mouse embryonic stem cells (ESC) to specify to definitive endoderm by up-regulating of Nodal signal pathway in order to find the best cultivated systems of differentiation of mouse ESC to definitive endoderm cells. METHODS: The cells were divided into different groups based on the culture medium: ESC group (serum-free medium + LIF), natural differentiation group (serum-free medium) and activin A group (serum-free medium +50μg/L activin A). The cells and the sterilized coverslips with cells were collected at 1, 3, 5 and 7 d of the cultivation. The proportion of CXCR4⁺ cells was detected by flow cytometry. The expression of CXCR4 was determined by immunocytochemical method, and the protein expression of OCT4 and CXCR4 was detected by Western blot. RESULTS: The proportion of CXCR4⁺ cells showed no dramatic change in ESC group along with the extending of cultivation day, while there were gradually increased in natural differentiation group and activin A group and the highest level was observed at 5 d. Among the 3 groups, the proportion of CXCR4⁺ cells at 5 d was the highest in activin A group. The brown or tan staining in the cells observed under microscope was considered as positive CXCR4 by immunocytochemistry. The protein levels of OCT4 and CXCR4 in ESC group along with the extending of cultivation days was observed. The expression levels of OCT4 were gradually decreased in the cells in natural differentiation group and activin A group, while those of CXCR4 were gradually increased with the highest level at 5 d. It was highest in the cells in activin A group. CONCLUSION: The proportion of definitive endoderm was the highest at 5 d of the induction during in vitro mouse ESC differentiation. Up-regulation of Nodal signal pathway by adding activin A at the early stage of mouse ESC differentiation promotes mouse ESC to specify to definitive endoderm with CXCR4 molecular marker.