盐碱土壤放线菌的研究概况

盐碱土壤放线菌是极端微生物的重要组成部分,也是一类极具应用前景的微生物资源.讨论了盐碱土壤放线菌的分离问题,并对其分类的发展与现状进行了概述,同时还就筛选抗生素高产菌株作了介绍.     

Effects of different fresh-cut forages and their hays on feed intake, digestibility, heat production, and ruminal methane emission by Boer x Spanish goats

Twenty-four yearling Boer × Spanish wethers were used to assess effects of different forages, either fresh (Exp. 1) or as hay (Exp. 2), on feed intake, digestibilities, heat production, and ruminal methane emission. Treatments were: 1) Sericea lespedeza (SER; Lespedeza cuneata), a legume high in condensed tannins (CT; 20% and 15% in fresh forage and hay, respectively), 2) SER supplemented with polyethylene glycol (SER-PEG; 25 g/d), 3) alfalfa (Medicago sativa), a legume low in CT (ALF), and 4) sorghum-sudangrass (Sorghum bicolor), a grass low in CT (GRASS). Experiments were 22 d, which included 16 d for acclimatization followed by a 6-d period for fecal and urine collection, and gas exchange measurement (last 2 d). Intake of OM was 867, 823, 694, and 691 g/d (SEM = 20.1) with fresh forage, and 806, 887, 681, and 607 g/d with hay for SER, SER-PEG, ALF, and GRASS, respectively (SEM = 46.6). Apparent total tract N digestion was greater for SER-PEG vs. SER (P < 0.001) with fresh forage (46.3%, 66.5%, 81.7%, and 73.2%; SEM = 1.71) and hay (49.7%, 71.4%, 65.4%, and 54.8% for SER, SER-PEG, ALF, and GRASS, respectively; SEM = 1.57). Intake of ME was similar among treatments with fresh forage (8.24, 8.06, 7.42, and 7.70 MJ/d; SEM = 0.434) and with hay was greater for SER-PEG than ALF (P < 0.03) and GRASS (P < 0.001) (8.63, 10.40, 8.15, and 6.74 MJ/d for SER, SER-PEG, ALF, and GRASS, respectively; SEM = 0.655). The number of ciliate protozoa in ruminal fluid was least for SER with fresh forage (P < 0.01) (9.8, 20.1, 21.0, and 33.6 × 10(5)/ml; SEM = 2.76) and hay (P < 0.02) (6.3, 11.4, 13.6, and 12.5 × 10(5)/ml for SER, SER-PEG, ALF, and GRASS, respectively; SEM = 1.43). Methane emission as a percentage of DE intake was lower (P < 0.01) for SER vs. ALF and GRASS with fresh forage (6.6, 8.3, 9.4, and 9.2%; SEM = 0.64) and hay (4.3, 4.9, 6.4, and 6.7% for SER, SER-PEG, ALF, and GRASS, respectively; SEM = 0.38). In summary, methane emission in this short-term experiment was similar between a legume and grass low in CT as fresh forage and hay. The CT in SER markedly decreased N digestibility and elicited a moderate decline in ruminal methane emission. Supplementation with PEG alleviated the effect of CT on N digestibility but not ruminal methane emission, presumably because of different modes of action. In conclusion, potential of using CT-containing forage as a means of decreasing ruminal methane emission requires further study, such as with longer feeding periods.     

生态毒理学工具在评价石油化工厂区土地耕作适宜性中的运用

The demand for simple and rapid bioassays in ecotoxicological evaluations is of paramount importance in order to speed up environmental monitoring programs. In this study we performed bioassays with lettuce seeds and two species of terrestrial isopods （Armadillidium vulgare and Porcellio dilatatus） for the ecotoxicological assessment of a landfarming soil from a petrochemical complex area. The solubilized content of test soil demonstrated a concentration-response type toxic effect on seed germination rate, and a delay on germination, but showed toxic effect on seedlings wet weight only at the highest concentration. Toxic effects were also observed in mortality rate and avoidance behavior of the two woodlice species. These results demonstrated the sensitiveness of the organisms studied, and highlighted the possibility to use these bioassays in environmental monitoring programs in areas contaminated with fossil fuels.     

蒙古羊BMP15基因外显子1位点多态性与产羔性能关系分析

采用PCR-SSCP技术对蒙古羊BMP15基因外显子1位点的单核苷酸多态性(SNP)进行了检测,并对其与产羔性能关系进行了分析.结果表明,在所检测的116个蒙古羊个体中,BMP15 基因在该位点均呈现多态性,具有 、A 和AA 3种基因型.测序分析表明,该段DNA序列中存在3个碱基的缺失,即编码区第28,29,30位碱基缺失,这个突变使野生型( )氨基酸序列上相应的10号氨基酸残基亮氨酸(L)缺失,变成了突变基因型(AA),形成B1突变体;群体遗传学分析表明,B1突变在双羔系中的发生频率高于单羔系中发生的频率,χ2适合性检验结果表明,两品系在该位点具有中度多态性并处于Hardy-Weinberg平衡状态(p＞0.05);与产羔性能关系分析表明B1突变对蒙古羊产羔数无显著影响(p＞0.05).     

陕北黄土洼聚湫类型划分与侵蚀产沙模拟研究

为了揭示泥沙沉积与降水的关系,重建淤地坝水成黄土的沉积环境,选择陕北黄土洼的天然聚湫为研究对象,通过野外多次多点位打钻采样和样品测定,利用近60年降雨数据与剖面粒度的对比分析和数学模拟等方法,划分了黄土洼聚湫类型,建立了标准聚湫侵蚀产沙模型。结果表明:(1)将黄土洼的侵蚀性雨量标准定为9.2mm能更好地反映黄土洼的土壤侵蚀状况;(2)依据降雨数据,黄土洼年均最大日降雨量52.7mm以下的降雨总量占88.1%,利用52.7mm以下降雨量产生的泥沙分布范围,可以确定非标准聚湫的范围;(3)通过对库容曲线的模拟将1 058.03m定为零库容高程点,并基于黄土洼的分形维数对岔巴沟流域建立的次降雨侵蚀输沙模型进行了修订,建立了适用于本地区的侵蚀产沙模型;(4)对各剖面沉积物粒度旋回规律进行对比分析,并结合模型计算数据,确定了黄土洼标准聚湫在近坝地剖面点附近,坝地至沟口附近之间为非标准聚湫,沿沟至沟头以上均为非聚湫沉积区。     

Soil texture prediction through stratification of a regional soil spectral library

Knowing the spatial distribution of soil texture,which is a physical property,is essential to support agricultural and environmental decision making.Soil texture can be estimated using visible,near infrared,and shortwave infrared(Vis-NIR-SWIR)spectroscopy.However,the performance of spectroscopic models is variable because of soil heterogeneity.Currently,few studies address the effects of soil sample variability on the performance of the models,especially for larger spectral libraries that include soils that are more heterogeneous.Therefore,the objectives of this study were to:i)apply Vis-based color parameters on the stratification of a regional soil spectral library;ii)evaluate the performance of the predictive models generated from the spectral library stratification;iii)compare the performance of stratified models(SMs)and the model without stratification(WSM),and iv)explain possible changes in prediction accuracy based on the SMs.Thus,a regional soil spectral library with 1535 samples from the State of Santa Catarina,Brazil was used.Soil reflectance data were obtained by Vis-NIR-SWIR spectroscopy in the laboratory using a spectroradiometer covering the 350–2500 nm spectral range.Sand,silt,and clay fractions were determined using the pipette method.Twenty-two components of color parameters were derived from the Vis spectrum using the colorimetric models.A cubist regression algorithm was used to assess the accuracy of the applicability of the initial models(SMs and WSM)and of the validation between the clusters.Fractional order derivatives(FODs)at 0.5,1.5,and 2 intervals were used to explain possible changes in the performance of the SMs.The SMs with higher contents of clay and iron oxides obtained the highest accuracy,and the most important spectral bands were identified,mainly in the 480–550 and 850–900 nm ranges and the 1400,1900,and 2200 nm bands.Therefore,stratification of soil spectral libraries is a good strategy to improve regional assessments of soil resources,reducing prediction errors in the qualitative determination of soil properties.     

采用全自动在线固相萃取-高效液相色谱法检测畜禽产品中氟喹诺酮类药物残留量

为建立畜产品中6种氟喹诺酮全自动在线固相萃取-高效液相色谱的检测方法,实验采用全自动在线固相萃取-高效液相色谱替代了前处理使用固相萃取小柱净化过程,净化效果较好。实现了恩诺沙星、环丙沙星、洛美沙星、培氟沙星、诺氟沙星和丹诺沙星6种氟喹诺酮类药物同时检测。本方法采用1%乙酸乙腈溶液提取,稀释后使用全自动在线固相萃取-高效液相色谱仪检测。6种氟喹诺酮平均回收率为81.9%~106.8%;相对标准偏差小于3.52%;定量限均为2.5μg/kg。该方法操作简单、经济、灵敏度高,结果准确可靠。     

玉米脱皮性及其方法研究

利用一种纯天然、无污染溶液处理玉米籽粒来除去外果皮是将玉米籽粒装入打了孔的尼龙袋中,放入90-95℃的溶液中处理,然后用亚甲基兰-曙红染液染色.我们测定了来自三个地区的三个品种果皮去除的难易度.玉米果皮去除的难易度受品种特性和生长环境的影响,而品种遗传影响是最明显的.该方法最适于在育种计划中以少量样品筛选大量样品.