C型肉毒梭菌肉毒毒素的提取与鉴定

[目的]通过对C型肉毒梭菌肉毒毒素的提取与鉴定,为类毒素和抗毒素的制备及抗原性分析奠定基础.[方法]将分离鉴定得到的C型肉毒梭菌通过扩大培养、产毒培养后将产生的肉毒毒素采用除菌过滤、硫酸铵盐盐析、离心、透析、浓缩的方法从产毒培养基中分离提取出来.再将提取的肉毒毒素通过SDS-PAGE鉴定毒素蛋白的分子量.[结果]分离出来的毒素蛋白重链和轻链分别在98和53 KDa左右,与C型肉毒毒素的理论分子量相符.[结论]提取的肉毒毒素是C型肉毒毒素.     

Current status and future prospects of bacterial ring rot testing

The bacterial ring rot disease of potato (Corynebacterium sepedonicum) can be detected in seed potato lots by serological tests with greater accuracy than by visual field inspections. Indexing tests can make use of highly specific immunofiuorescence probes, enzyme-linked immunosorbent assays, and perhaps other procedures. Sensitivity and specificity of these procedures need to be determined in order to estimate the confidence with which ring rot can be detected in a seed lot. In addition to the laboratory tests, the sampling strategy determines the efficacy and sensitivity of the indexing procedure. Samples might consist of stems, leaf petioles, or tubers in single or composite units. Disease incidence and number of plants sampled also determine the confidence level with which ring rot can be detected in a potato seed lot. Although research has been conducted on many aspects of ring rot testing procedures, further work needs to be done. Nevertheless, it is anticipated that indexing potato seed lots for the presence of ring rot will be a significant factor in control and eradication of the disease.     

Charge modifications to improve the emulsifying properties of whey protein isolate

Whey protein isolate was modified by ethylene diamine in order to shift its isoelectric point to an alkaline pH. The extent of the modification was studied using SDS-PAGE and MALDI-TOF mass spectrometry. The modified whey proteins were used as an emulsifier to stabilize oil-in-water emulsions at acidic and neutral pH ranges, and their emulsifying properties were compared with that of the unmodified whey proteins and with the previously studied ethylene diamine modified sodium caseinate. The emulsifying activity of the modified whey proteins was similar to that of the unmodified ones, but the stability of an emulsion at pH 5 was significantly improved after the modification. Charge and coverage of droplet surface and the displacement of the interfacial proteins by surfactant Tween 20 were further studied as a function of pH. As compared with the unmodified whey proteins, the modified ones were proven to cover the interface more efficiently with extensive surface charge at pH 5, although the interfacial layer was less resistant to the surfactant displacement.     

Implementation of an artificial reaction control in a TaqMan method for PCR detection of <Emphasis Type="Italic">Ralstonia solanacearum</Emphasis> race 3 biovar 2

A previously published TaqMan PCR test for R. solanacearum race 3 biovar 2 was modified to enable both the validation of negative results and the confirmation of positive results in a closed-tube system. Negative results were validated through the use of a reaction control plasmid, designated pRB2C2, which was designed to generate a 94bp product using the same amplimers targeting the primary diagnostic 68bp sequence in R. solanacearum race 3 biovar 2 DNA. SYBR Green was included in the reaction mix to facilitate the identification of post-reaction products using melt peak analysis. The 94bp reaction control had a melt peak temperature of about 90°C, while the diagnostic target amplicon had a melt peak temperature of about 83°C; thus positive results could be easily confirmed and distinguished from the reaction control product. Addition of pRB2C2 at 100 copies per reaction had no effect on the sensitivity of the TaqMan assay for R. solanacearum race 3 biovar 2, and the modified assay successfully detected R. solanacearum race 3 biovar 2 in infected, asymptomatic tomato stems and leaves as well as in potato tubers and stems.     

不同类型农药防治枸杞瘿螨的试验研究

利用试验所筛选出2种化学农药,1种植物农药,采用因“瘿”而异的单施,混施防治试验,证明3种农药混施效果最好,不但能够有效降低枸杞瘿螨的为害指数,而且可以延长药剂的持效期。     

The development of the Norwegian wrasse fishery and the use of wrasses as cleaner fish in the salmon aquaculture industry

Norway leads the world aquaculture production of Atlantic salmon Salmo salar and farmed Norwegian Atlantic salmon is currently consumed around the globe. However, sea lice infestation is a major problem faced by the salmon aquaculture industry in Norway and elsewhere. The use of wild-caught cleaner fish, mainly wrasses, has been recommended over the other available methods as the most economical and environmentally friendly option to control sea lice infestation in salmon farming. Here, we review the development of the Norwegian wrasse fishery and the use of wrasses as cleaner fish. In this document, we address the sea lice problem and introduce the main wrasse species employed as cleaner fish, document the cleaning behaviour of wrasses, present the development of a new wrasse fishery associated with the salmon aquaculture industry, and finally, we identify the main challenges associated with the intensive use of wild-caught cleaner wrasses and provide some insight for future directions of the wrasse fishery and further development of aquaculture techniques to supply salmon facilities with domesticated cleaner fish.     

兽药使用环节存在的问题及对策

经过对兽药生产厂家和经营企业几年的整治,尤其是新<兽药管理条例>和<兽药标签和说明书管理办法>出台后,又经过GMP认证,兽药生产经营市场秩序和经营行为得到了一定的规范.但兽药使用环节中却存在诸多的问题,如:违法使用人用药品;违法使用禁用兽药;不执行休药期规定;未建立台帐等等.这些问题的存在,直接导致了动物产品的安全性问题.对此,笔者分析了兽药使用环节存在问题的原因,并对解决这些问题提出了个人观点.     

Relative abundance and activity of melanized hyphae in different soil ecosystems

Here we report on the frequency of melanized fungal hyphae in 323 soils, covering different land use types. The proportion of total hyphae that was melanized averaged 61%. Arable fields with loamy sand, heathlands and city parks on sandy soils had the highest percentage of melanized hyphae. In addition to the frequency determinations, a microcosm study was performed on the role of melanized hyphae in two different ecosystems: an ex-arable field and a forest. Melanized hyphae appeared to be part of the active hyphae in the forest soil but not in the ex-arable soil. In conclusion, our results indicate that (1) melanized hyphae represent a large proportion of the total fungal biomass in soils and that (2) their function might differ between ecosystems.     

Salvinia plants in trade: what species are we actually talking about?

Incorrect labelling of plants in trade and misidentification are widespread. Likewise, in trade numerous names are being used for the ornamental aquatic plant known as ‘Kariba weed’, but rarely the correct scientific name Salvinia molesta Mitch. For inspection services of EPPO member countries, correct identification of S. molesta has become important since the species was added to the EPPO A2 List and the List of Union concern in accordance with EU regulation 1143/2014 based on an EPPO Pest Risk Analysis (PRA) for the species. Inspections and a targetted survey of Salvinia plants in trade in the Netherlands were performed and additional material was obtained from wild sources in South Africa, Hungary and the United States. Specimen identification was verified by comparison with the herbarium collection at Naturalis Biodiversity Center in Leiden and with the sequences available in NCBI GenBank database. This paper provides the tools to correctly identity the relevant Salvinia species.     

Phenoxymethyl penicillin potassium as an in-feed medication for pigs with streptococcal meningitis.

In two separate studies involving 2500 weaner pigs, strategic infeed medication with phenoxymethyl penicillin potassium significantly reduced the incidence of streptococcal meningitis.