C57BL/6J小鼠亚慢性镉中毒模型的建立

为了建立小鼠亚慢性镉中毒模型,本研究将20只C57BL/6J雄性小鼠随机分为4个剂量组和溶剂对照组,每组隔天分别腹腔注射含0.25、0.5、1和2 mg/kg剂量的氯化镉溶液和等量去离子水(溶剂),共染毒4周,观察不同剂量的镉离子对雄性小鼠肝脏、肾脏、睾丸的损伤情况.结果各处理组小鼠体质量增长要比对照组慢,脏器系数与对照组相比也有显著差异,处理组小鼠肝脏、肾脏、睾丸中镉含量显著高于对照组.病理组织切片结果表明,各处理组中小鼠的肝脏、肾脏、睾丸组织均出现不同程度的损伤.氯化镉可以显著地抑制小鼠体质量增长,并对小鼠的脏器系数产生影响,腹腔注射后在肝脏、肾脏、睾丸组织中产生蓄积,并对其造成一定损伤.隔天腹腔注射2 mg/kg剂量的氯化镉,4周可建立较理想的小鼠镉中毒模型.     

C57BL/6J小鼠非酒精性脂肪肝模型的建立

本试验分别采用高脂饲料和高脂饲料复合四氯化碳对C57BL/6J小鼠进行诱导,研究建立非酒精性脂肪肝模型的条件.本试验将C57BL/6J小鼠分成高脂组、高脂复合四氯化碳组(复合组)和正常组.各组分别于饲喂4、6、8周处死5只,称小鼠体重与肝重,采血测血清中生化指标情况,并取肝脏做H.E.染色、油红O染色.通过肝指数、生化与病理检查等指标,评价非酒精性脂肪肝的进程.结果显示,随着饲喂时间加长,高脂组动物肝脏脂肪变性加重;复合组动物除肝脏脂肪变性外,出现纤维化和明显的炎性浸润;4周时,高脂组中脂肪变性比复合组明显.6～8周时高脂组和复合组中生化指标明显高于正常组.本试验经饲喂高脂饲料成功复制了小鼠非酒精性脂肪肝模型.     

C57BL/6J等近交系小鼠精子冷冻研究进展

小鼠精子冷冻方法虽成功建立多年,但C57BL/6J等近交系小鼠的精子在冻融后的成活率和受精率远远低于封闭群和杂交小鼠的精子。C57BL/6J等近交系小鼠的精子冷冻方法已成为当前大量增加转基因小鼠保种的一个瓶颈,同时成为国内、外近来研究的热点。本文系统介绍了近年国外为改进C57BL/6J等近交系小鼠精子冷冻保存所的做努力和探索。研究包括:各种冷冻保存方法;新培养基的改良;各种冷冻试剂组合;冷冻对小鼠精子质膜伤害机理的研究及其保护方法;以及提高冻融后精子获能和提高授精能力等领域。     

对C57BL／6小鼠超排效果的研究

本文以近交系C57BL／6小鼠为实验对象．研究注射不同剂量的PMSG和hCG对小鼠超排效果的影响。取C57BL／6小鼠各30只,按照注射剂量不同分为A、B、C三组,每组10只,A组注射PMSG2．5IU,HCG2．5IU,B组注射PMSG5．0IU,HCG5．0IU,C组注射PMSG7．5IU,HCG7．5IU。每只小鼠腹腔注射PMSG,间隔48h后分别注射HCG进行超数排卵,再与性成熟同系公鼠合笼,次日早上检查阴道栓．有栓雌鼠用颈椎脱臼法处死。在实体显微镜下由输卵管膨大部冲卵．收集卵母细胞置于盛有M2培养液的表面皿中检查计数．分析超排效果。结果表明。C57BU6小鼠B组的平均取卵数极显著高于A组的平均取卵数（P〈0．05）;B组的平均取卵数显著高于C组的平均取卵数（P〈0．05）;C组与A组的平均取卵数差异不显著（P〉0．05）。     

C57BL/6小鼠肠道线虫的分离与鉴定

对某一实验动物养殖场出现大规模消瘦、生长发育不良的C57BL/6小鼠进行诊断。利用饱和生理盐水漂浮法对粪便虫卵进行检测,对小鼠进行剖检,并对不同肠段发现的虫体进行形态学鉴定。为进一步确诊,对发现的不同形态寄生虫分别提取DNA,进行18S rDNA基因片段的扩增、测序、同源比对和进化树分析。根据虫卵及虫体的形态特征,可初步判定从小鼠肠道分离到两种寄生虫,经测序比对进一步确认两种寄生虫分别为隐匿管状线虫和四翼无刺线虫。据形态学观察和分子生物学检测,确诊该起疫情为隐匿管状线虫和四翼无刺线虫混合感染引起。     

C57BL/6J小鼠促性腺激素注射时间对诱导超排卵的影响

目的:确定4周龄C57BL/6J小鼠注射促性腺激素的最佳间隔时间,提高超排效果,从而优化C57BL/6J近交系作为供体鼠的生物净化体系。方法:70只4周龄的C57BL/6J雌鼠随机分为5组,腹腔注射10IU的PMSG,10IU的h CG注射间隔时间分别为47h,47.5h,48h,48.5h,49h,比较超排的卵母细胞数和受精率等数据。结果:第1组与第5组的卵母细胞数有极显著差异,其他数据差异不显著。结论:4周龄C57BL/6J小鼠对PMSG应答产生的内源性黄体生成素(LH)释放量不足以引起排卵,因而h CG注射时间无需严格控制在注射PMSG后46~48h内。     

C57BL/6小鼠胚胎成纤维细胞的分离培养与纯化鉴定

为了建立一种易于操作,能够获得高纯度、高活力C57BL/6小鼠胚胎成纤维细胞的分离培养体系,并对分离提取的细胞进行纯化鉴定,试验在无菌环境下取E12.5胎鼠皮肤,剪碎至1 mm2大小,均匀铺于皿中,用含10%胎牛血清的高糖DMEM培养基连续培养4 d,以胰蛋白酶消化-再贴壁法分离纯化目的细胞,分别以NIH3T3、角质形成性细胞作为阳性与阴性对照,采用免疫荧光、Western-blot检测Vimentin及Keratin的表达情况,以鉴定所分离的细胞及其纯度。结果表明:组织块培养24 h即可见成纤维样细胞爬出,培养96 h细胞生长爬满全皿,经胰酶消化、筛网过滤再贴壁接种后能够获得形态均一、活力旺盛、具有成纤维细胞形态学特征的目的细胞;所分离细胞Vimentin表达阳性率为100%,而Keratin表达阳性率为0;与阴性对照角质形成性细胞相比,C57BL/6分离成纤维细胞和NIH3T3细胞均高表达Vimentin,且差异极显著,有统计学意义。说明以E12.5胎鼠皮肤为材料建立成纤维细胞分离培养体系,所分离培养的成纤维细胞具有更高的细胞活力和细胞纯度。     

抗生素混合使用对C57BL/6J小鼠肠道菌群破坏的研究

为探究抗生素对肠道菌群的破坏作用及肠道菌群失衡对机体的影响。本研究拟以C57BL/6J小鼠为研究对象,建立一个肠道菌群失衡的小鼠模型,并结合空腹血糖、血平板检测结果,通过综合分析实验结果,鉴定抗生素对小鼠肠道菌群的破坏作用,为以后抗生素的合理使用提供理论依据。在抗生素的干预下,小鼠的肠道菌群数量减少,空腹血糖降低。抗生素滥用会导致小鼠肠道菌群遭到破坏,从而致使机体其他机能失衡。     

手足清栓通过抗病毒降低71型肠道病毒(EV71)感染小鼠死亡率

71型肠道病毒(enterovirus 71,EV71)是引起手足口病(hand,foot and mouth disease,HFMD)的主要病原体,在亚太地区流行,至今尚无特效药物。手足清栓作为治疗手足口病的中药方剂因可接受性强、无可见副作用而受到青睐,但治疗效果和作用机理至今尚未见有报道。为阐明手足清栓对手足口病模型的治疗效果和作用机理,本研究测定手足清栓对健康Vero细胞的毒性和对EV71-BJ株感染Vero细胞模型的治疗效果,测定药物作用与否的Vero细胞感染模型的病毒载量;测定手足清栓经灌肠途径对健康小鼠的毒性和对EV71-BJ株感染小鼠模型的治疗效果,重点观察手足清栓药物对EV71-BJ株重症感染小鼠模型死亡率、体质量、临床症状的改善情况,测定手足清栓经灌肠途径给药对EV71-BJ株重症感染小鼠模型靶组织产生的病变程度、病毒载量、炎性分子的变化特征,从而探索手足清栓治疗EV71感染的机制。体外结果显示,在EV71-BJ株感染Vero细胞模型上,于对细胞无肉眼可见毒性质量浓度下(生药60 mg/L),手足清栓通过降低感染细胞的病毒载量显著抑制EV71感染引起的Vero细胞病变;体内结果显示,在无毒质量浓度条件下(生药11.05 g/kg),手足清栓通过降低病毒载量、改善组织病理变化、降低炎性分子浓度机制降低EV71感染小鼠模型的死亡率,改善发病小鼠的临床症状。结果表明,手足清栓可通过抗病毒明显提高小鼠的存活率,能够减轻EV71感染引起的HFMD的临床症状。     

猪链球菌2型、7型及9型小鼠感染模型的初步建立

本实验为了研究猪链球菌2型(SS2)、猪链球菌7型(SS7)及猪链球菌9型(SS9)菌株对BALB/c小鼠的致病性,探究BALB/c小鼠作为猪链球菌动物感染模型的可行性以及作为后续实验的依据的可靠性。本研究通过腹腔注射猪链球菌感染BALB/c小鼠,对死亡小鼠进行无菌解剖分离菌株并培养,对培养的菌株进行革兰氏染色法和PCR鉴定;同时利用荧光定量的方法检测各个脏器细菌的载量和组织切片HE染色观察脏器的病理变化。实验结果显示：攻毒的小鼠出现典型的临床症状并死亡,经过实验验证后确定小鼠是由于感染猪链球菌而致病、致死;测定SS2、SS7及SS9的LD₅₀分别为3.7×10⁷、4.1×10⁷、7.9×10⁷ CFU/mL。因此BALB/c小鼠对猪链球菌易感,可以作为实验室研究猪链球菌良好的实验动物。     

Generation of a uniform thymic malignant lymphoma model with C57BL/6J p53 gene deficient mice

Lymphoma is the third most common cancer diagnosed in children, and T-cell lymphoma has the worst prognosis based on clinical observations. To date, a lymphoma model with uniform penetrance has not yet been developed. In this study, we generated a p53 deficient mouse model by targeting embryonic stem cells derived from a C57BL/6J mouse strain. Homozygous p53 deficient mice exhibited a higher rate of spontaneous tumorigenesis, with a high spontaneous occurrence rate (93.3%) of malignant lymphoma. Because tumor models with high phenotypic consistency are currently needed, we generated a lymphoma model by a single intraperitoneal injection of 37.5 or 75 mg/kg N-methyl-N-nitrosourea to p53 deficient mice. Lymphoma and retinal degeneration occurred in 100% of p53^+/− mice administered with higher concentrations of N-methyl-N-nitrosourea, a much greater response than those of previously reported models. The main anatomic sites of lymphoma were the thymus, spleen, bone marrow, and lymph nodes. Both induced and spontaneous lymphomas in the thymus and spleen stained positive for CD3 antigen, and flow cytometry detected positive CD4 and/or CD8 cells. Based on our observations and previous data, we hypothesize that mice with a B6 background are prone to lymphomagenesis.     

Anti-obesity activity of diglyceride containing conjugated linoleic acid in C57BL/6J ob/ob mice

This study was to investigate the anti-obesity effects of diglyceride (DG)-conjugated linoleic acid (CLA) containing 22% CLA as fatty acids in C57BL/6J ob/ob male mice. There were four experimental groups including vehicle control, DG, CLA, and DG-CLA. The test solutions of 750 mg/kg dose were orally administered to the mice everyday for 5 weeks. CLA treatments significantly decreased mean body weight in the obese mice throughout the experimental period compared to the control (p < 0.01). All test solutions significantly decreased the levels of triglyceride, glucose and free fatty acids in the serum compared with control (p < 0.05). The levels of total cholesterol were also significantly reduced in DG and DG-CLA groups compared with the control group (p < 0.05). CLA significantly decreased weights of renal and epididymal fats compared with the control (p < 0.05). DG and DG-CLA also significantly decreased the epididymal fat weights compared with the control (p < 0.05). A remarkable decrease in the number of lipid droplets and fat globules was observed in the livers of mice treated with DG, CLA, and DG-CLA compared to control. Treatments of DG and CLA actually increased the expression of peroxisome proliferator-activated receptor gamma. These results suggest that DG-CLA containing 22% CLA have a respectable anti-obesity effect by controlling serum lipids and fat metabolism.     

Evaluation of host and bacterial gene modulation during Lawsonia intracellularis infection in immunocompetent C57BL/6 mouse model

BackgroundProliferative enteritis caused by Lawsonia intracellularis undermines the economic stability of the swine industry worldwide. The development of cost-effective animal models to study the pathophysiology of the disease will help develop strategies to counter this bacterium.ObjectivesThis study focused on establishing a model of gastrointestinal (GI) infection of L. intracellularis in C57BL/6 mice to evaluate the disease progression and lesions of proliferative enteropathy (PE) in murine GI tissue.MethodsWe assessed the murine mucosal and cell-mediated immune responses generated in response to inoculation with L. intracellularis.ResultsThe mice developed characteristic lesions of the disease and shed L. intracellularis in the feces following oral inoculation with 5 × l0⁷ bacteria. An increase in L. intracellularis 16s rRNA and groEL copies in the intestine of infected mice indicated intestinal dissemination of the bacteria. The C57BL/6 mice appeared capable of modulating humoral and cell-mediated immune responses to L. intracellularis infection. Notably, the expression of genes for the vitamin B12 receptor and for secreted and membrane-bound mucins were downregulated in L. intracellularis -infected mice. Furthermore, L. intracellularis colonization of the mouse intestine was confirmed by the immunohistochemistry and western blot analyses.ConclusionsThis is the first study demonstrating the contributions of bacterial chaperonin and host nutrient genes to PE using an immunocompetent mouse model. This mouse infection model may serve as a platform from which to study L. intracellularis infection and develop potential vaccination and therapeutic strategies to treat PE.     

Unilateral perinephric pseudocyst secondary to hydronephrosis in a C57BL/6J mouse

A 9-month-old C57BL/6J mouse had progressive abdominal distension over a 1-week period, and a distended left renal capsule was discovered at postmortem examination. Incision of the capsule showed a tan, cloudy fluid that separated the renal capsule and the remnant left kidney. Microscopically, the capsule was significantly separated from the renal parenchyma by clear space and necrotic cellular debris. The majority of the lining of the renal capsule was composed of fibrous connective tissue and lacked an epithelial lining, consistent with a subcapsular perinephric pseudocyst. In addition, attached to intermittent portions of the renal capsule were thin rims of compressed cortical tissue lined by transitional epithelium. The finding of remnant cortical tissue lined by transitional epithelium is consistent with severe hydronephrosis and indicates that the hydronephrosis preceded the formation of the perinephric pseudocyst. To our knowledge, this is the first case report to characterize a perinephric pseudocyst secondary to severe hydronephrosis in a mouse.     

Piebald mutation on a C57BL/6J background

The classic piebald mutation in the endothelin receptor type B (Ednrb) gene was found on rolling Nagoya genetic background (PROD-s/s) mice with white coat spotting. To examine whether genetic background influenced the phenotype in the piebald mutant mice, we generated a congenic strain (B6.PROD-s/s), produced by repeated backcrosses to the C57BL/6J (B6) strain. Although B6.PROD-s/s mice showed white coat spotting, 7% of B6.PROD-s/s mice died between 2 and 5 weeks after birth due to megacolon. The PROD-s/s, s/s and Japanese fancy mouse 1 (JF1) strains, which also have piebald mutations on different genetic backgrounds with B6, showed only pigmentation defects without megacolon. In expression analyses, rectums of B6.PROD-s/s with megacolon mice showed ~5% of the level of Ednrb gene expression versus B6 mice. In histological analyses, aganglionosis was detected in the rectum of megacolon animals. The aganglionic rectum was thought to lead to severe constipation and intestinal blockage, resulting in megacolon. We also observed an abnormal intestinal flora, including a marked increase in Bacteroidaceae and Erysipelotrichaceae and a marked decrease in Lactobacillus and Clostridiales, likely inducing endotoxin production and a failure of the mucosal barrier system, leading ultimately to death. These results indicate that the genetic background plays a key role in the development of enteric ganglion neurons, controlled by the Ednrb gene, and that B6 has modifier gene (s) regarding aganglionosis.     

温氏支原体感染动物模型的建立

为促进温氏支原体的深入研究,本试验建立了温氏支原体感染动物模型。选择6～8周龄健康雄性昆明种小鼠60只,随机分为A、B、C、D 4组,试验组(A、B、C)分别以不同方式感染温氏支原体,D组为对照组。结果表明,腹腔注射一定剂量高感染强度的牛红细胞悬液,同时注射免疫抑制剂地塞米松组(C组)表现为首现期出现早,且高峰期红细胞感染率高。应用悬滴镜检法和PCR诊断方法对感染小鼠血样进行鉴定,均符合温氏支原体特征。选择对照组小鼠和感染率高、临床症状较为明显的C组小鼠各10只,进行血液生理生化指标测定(RBC、WBC、Hb、TP、G、ALT、AST),结果呈现出与牛感染温氏支原体相同的规律。