英语僵化现象原因及对策研究

在梳理语言僵化研究基础上,重点探究了僵化现象产生的深层次原因,提出在二语习得过程中,应从提高语言输入质量,适时纠正语言输出,注重学习策略的训练,培养学生跨文化意识等层面出发,以帮助二语习得者缓解,并最终克服语言僵化,以期提高二语习得者的外语水平.     

Comparison of fecal culture and F57 real-time polymerase chain reaction for the detection of Mycobacterium avium subspecies paratuberculosis in Swiss cattle herds with a history of paratuberculosis

Background

Bovine paratuberculosis is an incurable chronic granulomatous enteritis caused by Mycobacterium avium subspecies paratuberculosis (MAP). The prevalence of MAP in the Swiss cattle population is hard to estimate, since only a few cases of clinical paratuberculosis are reported to the Swiss Federal Food Safety and Veterinary Office each year.Fecal samples from 1,339 cattle (855 animals from 12 dairy herds, 484 animals from 11 suckling cow herds, all herds with a history of sporadic paratuberculosis) were investigated by culture and real-time polymerase chain reaction (PCR) for shedding of MAP.

Results

By culture, MAP was detected in 62 of 445 fecal pools (13.9%), whereas PCR detected MAP in 9 of 445 pools (2.0%). All 186 samples of the 62 culture-positive pools were reanalyzed individually. By culture, MAP was grown from 59 individual samples (31.7%), whereas PCR detected MAP in 12 individual samples (6.5%), all of which came from animals showing symptoms of paratuberculosis during the study. Overall, MAP was detected in 10 out of 12 dairy herds (83.3%) and in 8 out of 11 suckling cow herds (72.7%).

Conclusions

There is a serious clinically inapparent MAP reservoir in the Swiss cattle population. PCR cannot replace culture to identify individual MAP shedders but is suitable to identify MAP-infected herds, given that the amount of MAP shed in feces is increasing in diseased animals or in animals in the phase of transition to clinical disease.     

Characterization of culture supernatant proteins from Brucella abortus and its protection effects against murine brucellosis

In this study, we characterized the secreted proteins of Brucella abortus into the enriched media under the bacterial laboratory growth condition and investigated the pathogenic importance of culture supernatant (CS) proteins to B. abortus infection. CS proteins from stationary phase were concentrated and analyzed using 2D electrophoresis. In MALDI TOF/TOF analysis, more than 27 proteins including CuZn SOD, Dps, Tat, OMPs, Adh, LivF, Tuf, SucC, GroEL and DnaK were identified. Cytotoxic effects of CS proteins were found to increase in a dose-dependent manner in RAW 264.7 cells. Upon B. abortus challenge into phagocytes, however, CS proteins pre-treated cells exhibited lower bacterial uptake and intracellular replication compared to untreated cells. Immunization with CS proteins induced a strong humoral and cell mediated immune responses and exhibited significant higher degree of protection against virulence of B. abortus infection compared to mice immunized with Brucella broth protein (BBP). Taken together, these results indicate that B. abortus secreted a number of soluble immunogenic proteins under laboratory culture condition, which can promote antibody production resulted in enhancing host defense against to subsequently bacterial infection. Moreover, further analysis of CS proteins may help to understand the pathogenic mechanism of B. abortus infection and host–pathogen interaction.     

Assessment of Aspergillus fumigatus burden in lungs of intratracheally-challenged turkeys (Meleagris gallopavo) by quantitative PCR,galactomannan enzyme immunoassay,and quantitative culture

Aspergillus fumigatus remains a major respiratory pathogen in birds and treatment is still difficult. We challenged different groups of few-day-old turkeys via intratracheal aerosolisation with increasing concentrations (10⁵ up to 10⁸) of conidia using a MicroSprayer^® device. The fungal burden was assessed by real-time PCR, galactomannan dosage, CFU counting and histopathological evaluation in order to provide a comparison of these results within each inoculum groups. Significant mortality, occurring in the first 96 h after inoculation, was only observed at the highest inoculum dose. Culture counts, GM index and qPCR results on the one hand and inoculum size on the other hand appeared to be clearly correlated. The mean fungal burden detected by qPCR was 1.3 log₁₀ units higher than the mean values obtained by CFU measurement. The new model and the markers will be used to evaluate the efficacy of antifungal treatments that could be used in poultry farms.     

不同培养液中卵形隐藻的生长和主要生化组成的比较

于１９９３年５月￣７月研究了５种培养液中形隐藻的生长及其主要生化成分的组成。结果表明，作者设计的ＦＰＷ培养液培养的卵形隐藻的最大密度和特定生长率均明显高于目前室内研究中普遍使用的ＷＣ培养液培养的相应值；氨基酸及必需氨基酸的比例非常接近；但蛋白质水平及多不饱和脂肪酸比例稍低。ＦＰＷ组成的简单性及由池塘水配制的特点表明，在隐藻规模化培养时，ＦＰＷ较ＷＣ具有更大的实用性。     

美洲黑石斑鱼的品种优势和养殖前景

美洲黑石斑鱼属于鮨科Serranidae,石斑鱼亚科Serraninae,俗名有翡翠斑、珍珠斑等美称,是美国近年成功开发的一个新养殖鱼种。它的养殖和市场潜力巨大,活鱼和加工产品极受美国和加拿大消费者的欢迎。我国从2003年引进,试养效果良好;2006年大规模生产苗种达100余万尾,为在我国推广养殖奠定了基础。本文重点介绍了该品种的生物学特性、养殖潜力、商业价值和在我国推广养殖的可行性,认为该品种很适合我国东部和东南沿海温带和亚热带水域开展深水网箱、工厂、池塘等模式的养殖,预测产品不仅可以内销而且有望远销欧美各国。     

白耙齿菌菌丝培养环境条件的研究

以菌丝干重和菌丝生长速度为考核指标,通过单因素试验,对白耙齿菌菌丝生长的培养基配方、温度、pH值及通气条件进行筛选。试验结果表明,最适培养基为YPAD培养基,最适温度为32℃,最适pH值为7.0,在正常通气培养条件下有利于菌丝生长和干重积累。     

油茶蒲栽培高温香菇的试验研究

为了有效利用我省丰富的油茶蒲资源,缓解近年食用菌栽培原材料上涨压力,研究以油茶蒲部分代替杂木屑栽培高温型香菇,以配方试验方式,探寻利用油茶蒲栽培香菇的配方技术。结果发现,以30％的油茶蒲代替杂木屑栽培香菇是可行的,香菇产量及品质与对照相比无显著差异。     

羊栖菜Sargasum_fusiforme原生质体的分离和培养

本研究多次获得原生质体，明确了酶解原生质体的内在因素与外在条件，诸如酶溶剂的种类及浓度，酶及组成，酶解温度及ｐＨ，采种藻时间及取用部位。分离的原生质体经初步培养，发现少数２分裂，最好的有成６分裂的细胞团，但尚未成株。研究结果为扩大培养打下了良好的基础。此外，还报道了用海洋细菌酶解的试验及意义     

海链藻对氮磷需求量的研究

本实验初步研究了海链藻对氮磷的需求，研究结果表明：以等摩尔氮的NH4Cl、NaNO，和NFLNO3作为氮源时，选择NH4NO3为氮源可以获得较快的生长率并维持较长时间的指数生长期；氮源浓度的最适范围在0．54-1．08mmol／L之间。而2．16mmol／L以上的高浓度NH4NO3则对海链藻的生长有一定的抑制作用；在不同磷浓度(0．015-0．12mmol／L)的条件下，海链藻保持大致相同的生长速率。