胶体金免疫技术在猪瘟诊断上的应用进展

胶体金免疫技术是一种新型免疫学检测技术.它具有简便、快速、特异性强、敏感性高、结果判断直观等优点.在猪瘟的快速诊断中得到了广泛应用,显示出了良好的应用前景.论文就胶体金免疫技术及其在猪瘟快速诊断上的应用现状及发展前景作一简要综述.     

应用免疫胶体金标记技术对狂犬病病毒形态发生学的抗原定位研究

利用包埋后免疫胶体金标记技术，通过透射电子显微镜，对感染ＢＨＫ２１细胞的鹿狂犬病病毒进行了形态发生的抗原定位。结果：感染细胞的细胞质内有５种包涵体，其中４种被免疫胶体金特异性标记，这些病毒抗原是多成分的，另一种未被免疫胶体金标记的包涵体可能是病毒核酸；感染细胞的细胞质内大量堆积的病毒前体物质包涵体，其中可能有病毒装配后多余的成分，表明病毒各组分并不是按比例需要而合成的。     

Determination of iron absorption by rat bioassay. Evaluation of methods of dosing59Fe on radioiron absorption from plant diets

We studied the potential of an animal model to predict nonheme iron absorption in humans and tested a feasible and easy technique of dosing⁵⁹Fe to evaluate bioavailability of dietary nonheme iron. Plant diets containing about 20 ppm or 75 ppm iron were the nonheme iron sources with ferrous sulfate (75 ppm) as a reference. Radioiron was administered by (a) gavaging in water, 1 h after a meal; (b) mixing with the meal; and (c) making a slurry with the meal and gavaging. No significant differences were found (P0.05) in⁵⁹Fe absorption among the three methods of administering radioiron. Absorption of⁵⁹Fe was similar to apparent iron absorption for all diets tested, whether the animals consumed the same diet as that of the test meal or a different diet. A high correlation (r=0.88) obtained between the apparent iron absorption and⁵⁹Fe iron absorption for different dosing techniques, indicates that extrinsic iron tag administered by any of these methods is valid to measure nonheme iron absorption. Apparent iron absorption values determined by rats fed 20 ppm or 75 ppm dietary iron from plant sources were similar to reported values for humans. It is concluded that the normal adult rat is an appropriate model to study iron bioavailability of human foods when iron status, maturity, iron intake relative to requirement, and method of measurement are similar to the human situation.     

Rhizodeposition of C and N in peas and oats after C-N double labelling under field conditions

Compounds released by plant roots during growth can make up a high proportion of below-ground plant (BGP) carbon and nitrogen, and therefore influence soil organic matter turnover and plant nutrient availability by stimulating the soil microorganisms. The present study was conducted to examine the amount and fate of C (CdfR) and N rhizodeposits (NdfR), in this study defined as root-derived C or N present in the soil after removal of roots and root fragments, released during reproductive growth. BGP biomass of peas (Pisum sativum L.) and oats (Avena sativa L.) was successfully labelled in situ with a ¹³C-glucose-¹⁵N-urea mixture under field conditions using a stem feeding method. Pea plants were labelled at the beginning of flowering and harvested 36 and 52 days after labelling at pod filling (P_P) and maturity (P_M), respectively. Oat plants were labelled at grain filling and harvested 42 days after labelling at maturity (O_M). CdfR was 24.2% (P_P), 29.6% (P_M) and 30.8% (O_M) of total recovered plant C. NdfR was 32.1% (P_P), 36.4% (P_M) and 30.0% (O_M) of total plant N. Due to higher N assimilation, amounts of NdfR were four times higher in peas in comparison with oats. The results for NdfR in peas were higher than results from other studies. The C-to-N ratio of rhizodeposits was lower under peas (17.3) than under oats (41.9) at maturity. At maturity, microbial CdfR at 0-30 cm soil depth was 37% of the microbial biomass C in peas and 59% in oats. Microbial NdfR was 15% of microbial N in peas and 5% in oats. Furthermore, inorganic NdfR was 34% in peas and 9% in oats at 0-30 cm at maturity. These results show that rhizodeposits of peas provide a more easily available substrate to soil microorganisms, which are incorporated to a greater extent and turned over faster in comparison with oats. Beside the higher amounts of N released from pea roots, this process contributes to the higher N-availability for subsequent crops.     

Fair trade fish: consumer support for broader seafood sustainability

Sustainable seafood initiatives began with efforts to promote and certify seafood sourced from well‐managed stocks caught with a reduced impact on the marine environment. More recently, social equity in fisheries has been the subject of increased concern with suggestions that seafood cannot be certified as sustainable if its production results in social harm, such as unfair wages or the use of forced or child labour. Together with local seafood, which has been promoted as an eco‐friendly and socially conscious alternative to globally sourced seafood, these initiatives signal a growing interest in fisheries as a social–ecological system. However, this increasingly complex landscape of environmental sustainability and social justice may be difficult for the public and seafood consumers to navigate. Here, we investigate consumer understanding of and responsiveness to a range of seafood sustainability initiatives by testing preferences and willingness to pay (WTP) for seafood across the three types of sustainability: ecological sustainability, local origin and social sustainability. More than half of respondents demonstrated good understandings of both ecological sustainability and social sustainability with respect to seafood, and respondents were willing to pay more for all three types of sustainability. However, WTP for social sustainability benefits was the lowest, and consumers perceived a high degree of overlap of these benefits with those from locally sourced seafood. These results indicate that seafood certification taking a system‐wide approach has potential to succeed, but that it will need to emerge in concert with the increased public education about social problems associated with globalized fisheries.     

外源磺胺二甲嘧啶对施用粪肥的菜地土壤中微生物群落多样性的影响

【目的】明确磺胺二甲嘧啶(SM2)随粪便施入土壤对土壤微生物群落造成的影响,为合理进行养殖场周围土壤环境质量评估和施肥管理提供参考依据。【方法】收集养殖场附近未经抗生素污染的粪便和土壤,构建粪便–土壤模型,设置不同SM2添加剂量的处理,分别为对照组(0)、低剂量组(5μg·kg~(-1))、中剂量组(500μg·kg~(-1))和高剂量组(5 000μg·kg~(-1)),并分别于粪便和SM2施入1、7、14和50 d后采集土壤样品,采用Biolog技术以及磷脂脂肪酸(Phospholipid fatty acid,PLFA)标记法对比分析不同处理组土壤微生物群落的碳源利用能力、菌群结构和功能多样性变化。【结果】SM2的施入提高了土壤微生物群落的总体碳源利用能力,中、高剂量组在施入50 d时对除酯类以外的其他碳源利用能力均强于对照组。低剂量组在施入7 d内对各类碳源利用能力增强,中、高剂量SM2的施入可能会影响土壤群落某些优势物种的繁殖和数量分配。随施入时间的延长,土壤微生物群落对不同剂量SM2反应不同,革兰阳性菌、革兰阴性菌以及真菌数量变化显著,放线菌变化不明显。【结论】SM2的施入将长期影响土壤微生物群落的结构与功能多样性。养殖场应及时处理动物排泄物以消除抗生素残留,减少粪肥对土壤环境造成的生态破坏。     

Cotton growth and the fate of N fertilizer as affected by saline water irrigation and N fertigation in a drip-irrigated field

The objective of this two-year field experiment was to study the effects of irrigation amount, N rate, and irrigation water salinity on cotton growth and the fate of N fertilizer. The movement of N through the plant-soil system was traced using ¹⁵N-labeled urea. The study consisted of twelve treatments, including two irrigation amounts (405 and 540?mm, I405 and I540, respectively); two N application rates (240 and 360?kg?N/ha, N240 and N360, respectively); and three irrigation water salinity levels [0.35, 4.61 and 8.04?dS/m, representing fresh water (FW), brackish water (BW), and saline water (SW), respectively]. A randomized complete block design was used with three replications. The results showed that cotton biomass, N uptake, and yield increased as irrigation amount and N amount increased; however, all three variables were significantly less in SW than in FW and BW. Plant ¹⁵N recovery rates were greater (i) in the I540 treatments than in the I405 treatments and (ii) in the N360 treatments than in the N240 treatments. Plant ¹⁵N recovery rates in BW were 7.98% and 30.01% greater than those in FW and SW, respectively. Residual soil ¹⁵N increased as N fertilizer amount increased but declined as irrigation amount increased. Residual soil ¹⁵N in BW and SW was 6.02% and 21.44% greater, respectively, than in FW. Total ¹⁵N recovery was significant greater in BW than in FW and SW. The ¹⁵N leaching losses increased significantly with increases in irrigation amount, irrigation water salinity, and N rate. Our study suggests that if appropriate amounts of irrigation water and N fertilizer are used, then brackish irrigation water (4.61?dS/m) will not affect cotton growth, yield and N recovery. In contrast, saline irrigation water (EC?>?8?dS/m) reduces cotton growth, yield, and N use efficiency.     

Elevated CO2 alters the structure of the bacterial community assimilating plant‐derived carbon in the rhizosphere of soya bean

Elevated CO₂ (eCO₂) increases rhizodeposits, which in turn alters the soil microbial community. However, it is not really known how the microbial community metabolizes plant‐derived carbon (C) in the rhizosphere under eCO₂, especially in agricultural soils. This study used a ¹³CO₂ labelling technique combined with DNA‐stable isotope probing (SIP) to fractionate the ¹³C‐DNA and ¹²C‐DNA from the rhizosphere of soya bean plants (Glycine max (L.) Merr. cv. Suinong 14) grown for 54 days under ambient CO₂ (aCO₂) (390 ppm) or eCO₂ (550 ppm). The DNA fractions were then subjected to Illumina Miseq sequencing. The results showed that eCO₂ decreased the richness and diversity of the ¹³C‐assimilating bacterial community compared to aCO₂ (p < 0.05). Elevated CO₂ decreased the abundances of genera, including Pseudarthrobacter, Gaiellales_uncultured, Microlunatus, Gemmatimonas, Gemmatimonadaceae_uncultured, Ramlibacter, Massilia, Luteimonas, Acidobacteriaceae_uncultured, Bryobacter and Candidatus_Solibacter. These genera were probably fast‐growing bacteria and sensitive to labile C. In contrast, eCO₂ stimulated the growth of genera Novosphingobium, Acidimicrobiales_uncultured, Bacillus, Flavisolibacter and Schlesneria, which were able to assimilate complex C compounds. Moreover, the increased population of Novosphingobium under eCO₂ might have accelerated electron flow from the oxidation of organic C. Correspondingly, eCO₂ did not affect the concentration of the dissolved organic C but increased the plant‐derived ¹³C in the rhizosphere. These results indicated that an eCO₂‐induced increase in non‐labile C in rhizodeposits contributed to the increase in population size of a number of the plant‐C‐metabolizing genera that might become the mechanism for the turnover of fresh C in the rhizosphere, modifying the soil C cycle under eCO₂ environments.     

Differential acquisition of amino acid and peptide enantiomers within the soil microbial community and its implications for carbon and nitrogen cycling in soil

l-isomeric amino acids and oligopeptides are thought to represent a key nitrogen (N) source for plants and soil microorganisms, bypassing the need to take up inorganic N, whilst self-cycling of d-enantiomers within peptidoglycan-containing bacteria may provide a further short circuit within the N cycle. Here we use stable isotope profiling (SIP) to identify the fate of organic N within soil microbial communities. We followed the incorporation of ¹³C-labelled d- or l-labelled amino acids/peptides into phospholipid fatty acids (PLFAs). l-alanine and its peptides were taken up more rapidly than d-enantiomers by Gram-positive bacteria with ¹³C incorporation being predominantly into anteiso- and iso-fatty acids typically associated with Gram-positive bacteria. d-enantiomer uptake was found not to differ significantly between the microbial groups, providing little support for the view that soil bacteria may self-cycle d-forms of amino acids and peptides. There was no consistent association between peptide chain length and incorporation. The concentrations of l- and d-isomeric amino acids in soil solution were 866 nM and 72 nM, respectively. We conclude that Gram-positive bacteria appear to be the primary competitors for l-enantiomeric forms of amino acids and their peptides, but that both d- and l-enantiomers are available N and C sources for bacteria and fungi.