慧星试验检测洛克沙胂对CHL细胞的DNA损伤

利用碱性单细胞凝胶电泳技术研究洛克沙胂对中国仓鼠肺细胞(CHL)的DNA损伤影响。洛克沙胂分为10、100、500、1000mg/L剂量组,分别以磷酸盐缓冲液和10mg/L亚砷酸钠为对照组,经3、6、12、24、48h暴露后进行单细胞凝胶电泳。结果表明,慧星试验参数尾DNA含量、慧星全长、慧尾长、尾距和Olive尾距等表现出剂量-效应、时间-效应关系,不同剂量洛克沙胂、不同暴露时间下对CHL细胞有不同程度的DNA损伤。     

Detection of c-kit mutations in canine mast cell tumors using fluorescent polyacrylamide gel electrophoresis.

Mutations consisting of internal tandem duplications (ITDs) in exons 11 and 12 of the proto-oncogene c-kit are found in 30-50% of malignant canine mast cell tumors (MCTs). Traditionally, identification of such mutations in tumor specimens has been undertaken using standard polymerase chain reaction (PCR) and agarose gel electrophoresis. This procedure is limited to the detection of insertions and deletions larger than 9 base pairs in size. The purpose of this study was to compare the efficiency and accuracy of standard agarose gel electrophoresis with fluorescent polyacrylamide gel electrophoresis (PAGE) for the detection of ITDs in canine MCTs. The results of this study demonstrate that PAGE of labeled PCR products accurately predicts the size of the ITD in each tumor. In addition, other small insertions and deletions were not identified, suggesting that if they occur in canine MCTs, they do so infrequently. Because fluorescent and polyacrylamide formats are automated and have better resolution than agarose gels, fluorescent PAGE provides a more accurate, economical, and higher throughput method for the detection of c-kit mutations in canine MCTs.     

绞股蓝总皂甙对衰老小鼠DNA损伤的影响

目的:本试验旨在探讨绞股蓝总皂甙(GPS)对D-半乳糖亚急性衰老模型小鼠DNA损伤的影响。方法:将200只健康昆明系小鼠随机分为5组,每组40只(雌雄各半)。一组为空白对照组,每天每只灌胃和颈背部皮下注射生理盐水0.1ml;二组为D-半乳糖衰老模型组,按120mg/kg每天每只颈背部皮下注射D-半乳糖(用时用生理盐水配成5%的溶液)0.1ml,同时灌胃生理盐水0.1ml;三、四、五组为绞股蓝总皂甙(GPS)组,每天每只灌胃GPS溶液(GPS的剂量分别为180mg/kg、120mg/kg、60mg/kg,用时用生理盐水配成溶液)0.1ml,同时按120mg/kg颈背部皮下注射D-半乳糖(用时用生理盐水配成5%的溶液)0.1ml。分别在动物用药期满2、4、6、8周时处死动物采样,每次采集大脑、肝脏组织,检测大脑、肝脏细胞DNA的损伤。结果:GPS三个剂量组小鼠大脑和肝脏细胞的拖尾率与模型组相比,均有所下降,其中大脑细胞的拖尾率在30%～45%之间,且差异显著(P<0.01或P<0.05);DNA损伤程度也有所减轻,除了低剂量组外,高、中剂量组主要以Ⅱ级损伤为主。结论:GPS可以减轻模型组小鼠大脑和肝脏组织细胞DNA的损伤程度。     

Analysis of serum proteins in clinically healthy goats (Capra hircus) using agarose gel electrophoresis

Background: Electrophoretic patterns of serum proteins provide useful information on pathological conditions in ruminants. Their reference values, however, are dissimilar to those of other species. Reference values for goats using agarose gel as the supporting matrix have not been reported. Objective: The aim of this study was to evaluate serum concentrations of total protein and protein fractions (albumin and globulins) by means of agarose gel electrophoresis (AGE) in goats in order to establish electrophoretic reference intervals and to evaluate potential changes associated with aging. Methods: Blood was collected from 105 clinically healthy Girgentana goats by means of jugular venipuncture. Serum protein concentrations were assessed by AGE. Three age groups were compared: 1–1.5 years, 2–4 years, and 5–12 years. Results: Values (mean ± SD) were determined for concentrations of total protein (72.26 ± 6.40 g/L), albumin (31.80 ± 4.00 g/L), α‐globulins (6.40 ± 1.23 g/L), β₁‐globulins (10.50 ± 2.58 g/L), β₂‐globulins (5.18 ± 1.60 g/L), and γ‐globulins (18.65 ± 5.90 g/L) and for albumin/globulin (A/G) ratio (0.82 ± 0.20). One‐way ANOVA showed statistically significant age‐related differences for total protein and α‐globulin concentrations and A/G ratios. Age influenced protein concentrations with the 5–12‐year‐old group having higher total protein and α‐globulin concentrations and lower albumin concentration and A/G ratios than the 2–4‐year‐old group. Conclusions: This study provides reference values for total protein concentrations and protein fractions obtained by AGE in goats. Some values vary with age. Age‐specific reference intervals are reported in order to provide clinicians with an additional diagnostic aid.     

Quantitative determination of blood-plasma protein fractions using micro-agar gel electrophoresis in highly pregnant dairy cows close to the day of delivery]

Ten clinically intact Jersey dairy cows in advanced pregnancy were examined and tested over a span of three hours before to seven hours after parturition. Blood was sampled from them in intervals of ten tp 20 minutes, and the blood plasma was checked total protein and the "classical" fractions. The average total protein value of the plasma samples was 6.5 g/100 ml. The albumin and alpha 1-fractions were inversely proportional the psi-globulin concentrations before, during, and after parturition. The albumin values were on a declining trend three hours prior to parturition and recommenced to rise ten minutes prior to parturition. They were relatively constant after parturition. The pri-globulins went up slightly prior to parturition, but that rise remained statistically unsecured. It is assumed that in a certain period of time from before to somewhen after parturition change of the fractions is caused by the corticoids and sexual hormones.     

Tracing outbreaks of Streptococcus equi infection (strangles) in horses using sequence variation in the seM gene and pulsed-field gel electrophoresis

Strangles is a serious respiratory disease in horses caused by Streptococcus equi subspecies equi (S. equi). Transmission of the disease occurs by direct contact with an infected horse or contaminated equipment. Genetically, S. equi strains are highly homogenous and differentiation of strains has proven difficult. However, the S. equi M-protein SeM contains a variable N-terminal region and has been proposed as a target gene to distinguish between different strains of S. equi and determine the source of an outbreak. In this study, strains of S. equi (n=60) from 32 strangles outbreaks in Sweden during 1998-2003 and 2008-2009 were genetically characterized by sequencing the SeM protein gene (seM), and by pulsed-field gel electrophoresis (PFGE). Swedish strains belonged to 10 different seM types, of which five have not previously been described. Most were identical or highly similar to allele types from strangles outbreaks in the UK. Outbreaks in 2008/2009 sharing the same seM type were associated by geographic location and/or type of usage of the horses (racing stables). Sequencing of the seM gene generally agreed with pulsed-field gel electrophoresis profiles. Our data suggest that seM sequencing as a epidemiological tool is supported by the agreement between seM and PFGE and that sequencing of the SeM protein gene is more sensitive than PFGE in discriminating strains of S. equi.     

Detection of T-2 toxin in grains using thin layer chromatography with silica gel (TLC)

The TLC method of the detection of T-2 toxin in grains is described. A thin layer of silica gel with a sensitivity of 3 mg/kg is used in this method. In comparison with the biological assay for dermal irritability, the TLC method is 30 times less sensitive. However, it has one great advantage over the bioassay: its specificity. It is recommended for practice to use a screening method based on the test for the dermal irritability of rabbits. When the content of toxins is higher, the analytic method can be used for trying to identify the given mycotoxin of the trichothecene group. T-2 toxin was detected in none of the 33 samples of tested grains (14 samples of barley, 7 wheat, 5 rye, 5 oats, 2 samples of maize).     

Acute bacterial cystitis does not cause deoxyribonucleic acid damage detectable by the alkaline comet assay in urothelial cells of dogs

Considering the high incidence of dogs with acute bacterial cystitis (BC) and the relationship among inflammation, genotoxicity, and carcinogenesis, we conducted a case-control study comparing the frequency of deoxyribonucleic acid (DNA) lesions assessed by the comet assay between disease-free animals (13 males and 13 females) and cytology-confirmed cases of acute BC (12 males and 12 females), which was mainly caused by Staphylococcus sp. (40%) and Escherichia coli (35%). The results show no increase in DNA damage in cells obtained by bladder washings and no influence of age, sex, and breed due to acute BC. In conclusion, DNA damage was seemingly not associated with the infection by specific bacteria.     

Detection of Sarcocystis antigens in the sera of experimentally-infected pigs and mice by an immunoenzymatic assay

Immunoglobulins raised against Sarcocystis miescheriana and Sarcocystis muris cystozoite antigens were isolated from rabbit immune sera by affinity chromatography (using CNBr-activated Sepharose 4B for antigen immobilization). The specific immunoglobulins were incorporated into double-antibody sandwich immuno-enzymatic assays which were firstly quantitated and then used to detect soluble Sarcocystis antigens in the sera of experimentally-infected pigs and mice. Assays employing immunoglobulins attached to the solid-phase at concentrations of 80 micrograms/ml were capable of detecting homologous soluble cystozoite and sporozoite reference antigens at concentrations as low as 8 micrograms/ml. Circulating antigens were detected both in the presence and absence of acute clinical disease in pigs experimentally-infected with high and low doses of S. miescheriana sporocysts. The antigenemia detected was transitory (occurring from 3-20 days post-inoculation: dpi) and coincided well with the sporozoite and merozoite phases of parasite development. Circulating antigens were also detected during subclinical infections in mice (from 4-49 dpi) following their experimental infection with low doses of S. muris sporocysts. Specific immuno-enzymatic assays for circulating Sarcocystis antigens may therefore prove useful in the clinical diagnosis of acute sarcocystosis.     

Detection of animal pathogens by using the polymerasechain reaction (PCR)

The polymerase chain reaction (PCR) is a nucleic acid-based technique that enables the rapid and sensitive detection of specific micro-organisms. Although this technique is widely used in veterinary research, it has not yet found applications in routine microbiological analysis of veterinary clinical samples. However, advances in sample preparation together with the increasing availability of specific gene sequences will probably lead to the more widespread diagnostic use of PCR in the future. PCR is likely to have a strong impact in the epidemiology, treatment and prevention of animal infectious diseases.     

Testicular (Sertoli's cell)-like tumors of the ovary induced by N-ethyl-N-nitrosourea (ENU) in rats

N-ethyl-N-nitrosourea (ENU) administered intraperitoneally or transplacentally to Sprague-Dawley (CD) and BD-IV (Berlin Druckrey IV) rats increased the incidence (26.6%) of an uncommon ovarian tumor with testicular characteristics compared either to controls (3.0%) or rats administered diethylnitrosamine (3.3%). The induced tumors were composed of tubular structures that resembled seminiferous tubules lined by Sertoli's-like cells. The abundant electron-lucent cytoplasm of the tumor cells contained polyribosomes, lipid bodies, and mitochondria but few additional organelles. Sertoli's cell-like tumors appeared to develop from the ovarian stroma in the hilar region of the ovary. They usually were benign and resulted in unilateral enlargement of the ovary. The mean serum concentrations of testosterone, estrone, and estradiol in selected rats with ovarian tumors were elevated above mean serum values in controls. There was not a consistent direct correlation between tumor diameter and circulating hormone level. Ethyl nitrosourea-induced ovarian tumors composed of testicular (Sertoli's-like) cells will provide a reproducible animal model to investigate the histogenesis and hormone secreting properties of this unique gonadal neoplasm.     

铅和（或）镉对体外培养肾细胞的毒性损伤

在培养液中加入不同浓度的Cd（10、20、40μmol／L）、Pb（10、20、40μmol／L）和Pb-Cd联合（分别为5、10、20μmol／L）,来探讨铅镉对肾细胞的作用及可能机制。在显微镜下观察细胞形态、测定细胞凋亡率和细胞周期及上清液脂质过氧化指标。结果表明：20μmol／L以上染毒组细胞皱缩、体积变小,表面有细胞碎片,甚至呈泡沫状或树枝状;铅、镉单独和联合染毒组GSH—Px、SOD活性随染毒剂量的增加,呈逐渐下降趋势（P〈0．05）．而MDA含量和凋亡率则呈升高趋势（P〈0．05）,并存在剂量和时间效应。镉和铅也能使细胞周期停滞。Pb、Cd联合可加剧细胞损伤。     

Detection of Mycoplasma wenyonii in cattle and transmission vectors by the loop-mediated isothermal amplification (LAMP) assay

Mycoplasma wenyonii is a wall-less hemotrophic prokaryote with worldwide distribution. This paper describes the development of a LAMP method targeting 16S rRNA for specific detection of M. wenyonii in its vectors and cattle. The LAMP method is specific for M. wenyonii detection and more sensitive than PCR. A total of 330 blood samples from cattle were tested by LAMP and PCR detection, 71 (21.5 %) samples were positive by the LAMP, while only 62 (18.8 %) were positive by PCR. For detecting transmission vectors, 26 lice, 30 flies, and 26 mosquitoes were collected and 18 lice, 20 flies, and 21 mosquitoes were tested positive by LAMP and PCR. These results indicate that the LAMP assay is a simple and convenient diagnostic tool for M. wenyonii detection and can be used in epidemiological surveys.     

Molecular genotyping by pulsed-field gel electrophoresis of restricted genomic DNA of strains of taylorella equigenitalis isolated in Ireland and in the United States

The profiles, after digestion with ApaI or NotI and pulsed-field gel electrophoresis (PFGE), of genomic DNA from 18 strains of Taylorella equigenitalis isolated in Ireland were of three different types. The 13 strains in one of these types gave PFGE profiles identical to that of an American prototype strain, Kentucky 188, but different from strain NCTC11184^T and from a strain isolated in Japan.Eight additional strains isolated in the United States gave four distinct types of genomic PFGE profiles. All four types were different from that of T. equigenitalis NCTC11184^T or that of the Japanese strain. The profile of three strains of one type was identical to that of Kentucky 188.     

Detection of the K99 antigen of Escherichia coli in calf faeces by enzyme-linked immunosorbent assay (ELISA)

Summary An enzyme-linked immunosorbent assay (ELISA) is presented for the detection of the K99 antigen of Escherichia coli in calf faeces. False-positive reactions were not observed with K99-negative strains and with several viral antigens. Only bovine coronavirus caused slight positive reactions which could be eliminated by a blocking test. As compared with the conventional procedure for the detection of the K99 antigen, ELISA seemed to be at least as sensitive and had the advantage that samples could be stored at -20° C before testing. In addition many samples could be handled at the same time and the results became available quickly. By carrying out the assay as a blocking test, specific antibody against K99 in serum or colostrum could be detected and titrated.     

Proteic boost enhances humoral response induced by DNA vaccination with the dnaK gene of Chlamydophila abortus but fails to protect pregnant mice against a virulence challenge

In order to enhance the quantity and the protective properties of the antibodies induced by DNA vaccination with the heat shock protein dnaK gene of Chlamydophila abortus AB7 as well as to elicit an efficient cellular immune response, we vaccinated mice with a DNA prime followed by a boost with the recombinant DnaK protein. In non-pregnant mice, this strategy induced the same predominance of the IgG2a isotype as DNA immunization alone with a substantial increased antibody level. The induced antibodies had no in vitro neutralizing properties on C. abortus infectivity. Moreover, the proteic boost probably failed to elicit an efficient cellular immune response since the pregnant or non-pregnant mice were not protected against the bacterial challenge.     

Comparison of the Level(s) of DNA Damage Using Comet Assay in Bovine Oocytes Subjected to Selected Vitrification Methods

It was suggested that the cryodamage to oocytes' DNA has been responsible for the compromised developmental competence of cryopreserved oocytes. Vitrification of bovine oocytes affected not only cellular components, but also nuclear material. A significant rate of DNA fragmentation was found in bovine frozen or vitrified oocytes analysed by Comet assay regardless of cryopreservation method. Our method of vitrification using droplet system after gentle pre-equilibration treatment is one of the most effective cryopreservation methods employed for bovine oocytes so far, making it possible to develop 30% blastocyst stage embryos. In this study, the extent of DNA damage in bovine oocytes vitrified using three vitrification methods (droplet system, Open Pulled Straw and traditional vitrification in 0.25 ml insemination straws) was compared using Comet assay. Vitrification in droplet system and Open Pull Straws vitrification did not result in detectable cryoinjuries of DNA of bovine oocytes. On the contrary, DNA fragmentation was found in four of 26 oocytes vitrified in 0.25 ml straws (15.4%, p   ≤ 0.05 in comparison with the other vitrification methods).