一株从片烟中分离的纤维素酶产生菌B.Pumilus培养条件优化研究

[目的]优化短小芽孢杆菌(B.Pumilus)菌株TX3产纤维素酶条件,为其降解片烟中所含纤维素提供理论依据.[方法]应用单因子试验考察碳源种类、烟梗粉末添加量、硫酸铵浓度和pH对菌株TX3发酵产纤维素酶的影响,在此基础上选取烟梗粉末添加量、硫酸铵浓度、pH作为显著因子,采用响应面分析法对此3种显著因子进行优化和分析.[结果]菌株TX3最适产酶条件为发酵初始pH6.93,烟梗粉末添加量1.24％,硫酸铵浓度0.35％,以此条件进行摇瓶发酵72 h,其纤维素酶活力达到9.91 U/ml,比优化前高了31.4％.[结论]烟梗粉末添加量、硫酸铵浓度、pH对菌株TX3产纤维素酶单个及交互影响均显著.     

用免疫抑制小鼠快速培育抗苏拉明伊氏锥虫

将伊氏锥虫克隆ＪＧｍｃ５用环磷酰胺处理的免疫抑制小鼠频繁地连续传代，并予以亚治疗剂量的苏拉明治疗，连续传代１４次，历时８８日，即获得对苏拉明具有高水平抗药性的伊氏锥虫群体。在用免疫活性正常的健康小鼠测定抗药性时，此抗苏拉明锥虫群体仍保持高水平的抗药性，ＣＤ１００＞４００ｍｇ／ｋｇ。在以体外药敏试验测定时，其ＩＣ５０为１２３．２μｇ／ｍｌ。实验结果表明，宿主免疫系统的损害，在实验条件下，可导致伊氏锥虫迅速产生抗药性。在野外条件下，机体免疫系统的损害对锥虫抗药性的产生可能也起一定作用。     

岩溶地区开挖隧道对水资源的影响--以渝合高速公路隧道为例

中梁山位于重庆市的近郊区,是净化城区污染空气,调节主城区气候环境的重要地带。渝合高速公路隧道横穿中梁山,破坏了地下水的循环过程,引起泉水和地表水的枯竭。水源枯竭面积7.2 km2。隧洞每年渗漏水量283.9万m3,有21个泉(井)受到影响,其中17个泉(井)完全干枯,有5口堰塘全年都无水可蓄。造成4个自然村、748户居民、2 247人失去了饮用水,143 hm2耕地失去灌溉用水。     

The influence of different factors on selenium levels in dairy cow herds in the central-eastern region of Poland

Selenium has been recognised as a basic bioelement that determines normal development and health of animals and humans alike. Studies of many authors revealed the influence of selenium deficiency on immunity, health, reproduction and production of dairy cows. Selenium deficiency have been reported in a number of countries, for example in different regions of Poland. The aim of the study was to determine the Se levels in blood serum of dairy cows in the Lublin region. In the periods: autumn 2003, winter 2003 and autumn 2004 selenium concentrations were investigated in serum samples from 180 dairy cows. The samples were obtained from 11 farms. The selenium concentrations were estimated with the ASA method. The monitoring studies have found that Se serum levels are dependent on season of the year, physiological period, maintenance systems and methods of feeding. Mean selenium serum levels observed in the study were between 0.21-0.92 micromol/l, especially (micromol/l): lactation 0.74 +/- 0.13, drying-off period 0.67 +/- 0.15, autumn 2003 0.38 +/- 0.17, winter 2003 0.48 +/- 0.16, autumn 2004 0.69 +/- 0.18. These results suggest that selenium should be supplemented, especially in high-producing dairy cow herds.     

Physiological mechanisms for antagonistic interaction of manganese and aluminum in barley

In a previous study, we found that the combined addition of Al and Mn in the culture solution could alleviate the inhibition of barley growth by addition of Al or Mn alone. The current experiment was conducted in a greenhouse to investigate the physiological mechanisms of the antagonistic interaction using two barley genotypes, XZ16 (both Al and Mn tolerant) and ZU9 (both Al and Mn sensitive). The treatments consisted of three Al levels (0, 0.1, and 0.5?mM) and three Mn levels (0, 0.2, and 1.0?mM) and their combinations, and a completely randomized block design was used with three replications. The combined treatments had larger plant biomass, lower Al and Mn concentrations and accumulation in plant tissues, lower malondialdehyde content, and higher root ATPases activities, compared with Al or Mn alone treatment. The two genotypes had the similar trend in the antagonistic interaction, with ZU9 being more predominant than XZ16.     

含气率对小流量下混流式混输泵轴系振动的影响

振动是反映混输泵运行稳定性的关键指标,液体含气率对混输泵的振动强度有重要影响.为探究小流量工况下含气率变化对混输泵轴系振动的影响规律,该研究以某3级混流式气液混输泵为研究对象,采用建立的多通道振动测试系统采集小流量工况下混输泵输送不同含气率的水时主轴和轴承座的振动信号,然后分析水中含气率对主轴和轴承座振动特性的影响规律...     

In vitro inhibition of epithelial cell invasion by Aeromonashydrophila Vibrio species by fish Aeromonas hydrophila major adhesin

A virulent strain of Aeromonas hydrophila (PPD 134/91) was obtained from the Primary Production Department, Singapore. Its major adhesin was isolated and purified by potassium thiocyanate extraction and Bio-Gel P-100 gel filtration. The ability of the protein in peak 1, termed major adhesin, to inhibit bacteria from adhering to and invading host cells was studied in vitro using epithelioma papillosum cells of carp (EPC). Results showed that a concentration of 10 μg ml^–1 of this major adhesin could competitively inhibit 28% of A. hydrophila PPD 134/91 from invading EPC cells in vitro. When the concentration was increased to 40 μg ml^–1, the major adhesin significantly cross-inhibited nine other virulent or weakly virulent strains of A. hydrophila. In addition, the major adhesin significantly inhibited not only another bacterial strain from the same family, Aeromonas sobria, but also strains of Vibrio spp. tested. Therefore, we suggest that the major adhesin of this virulent A. hydrophila strain has the potential to be used as a vaccine against the heterogeneous Aeromonas and Vibrio species.     

三峡库区土地利用与土壤质量演化的关系研究--以重庆万州为例

在三峡库区有代表性的重庆万州地区选择4种典型利用方式,运用土壤质量演化指数法,研究土地利用方式对三峡库区土壤质量演化的影响。计算结果表明,旱地转变成其他利用方式后,土壤质量均向良性方向演化,而且果园改善最大,菜地次之,撂荒地也有所恢复。     

近10年农牧交错区生态环境变化分析——以内蒙古太仆寺旗为例

利用2000年和2009年2个时期的Landsat 5的4,3,2(RGB)波段合成影像的解译结果,分析研究区近10年的景观格局变化,并结合气象数据,探讨景观格局在气候背景下的演变规律,揭示生态环境变化与气候变化的关系。结果表明:10年来研究区林地和草地面积有所增加,但区域整体生态环境还是呈退化趋势,表现为水域及低湿地草甸的大量减少和低地盐化草甸的增加;在全球气候变暖背景下,研究区气温上升趋势明显,加上降水量季节分布不均,持续的干旱使生态环境变得更差,农牧业生产受到极大影响。基于分析结果,指出在气候变化背景下,应加强生态环境保护的力度,限制或取消引起生态退化的各种干扰因子,充分利用系统的自我修复功能,达到恢复和改善生态环境的目的,实现区域的可持续发展。     

The Tolerance Index and Translocation Factor were Used to Identify the Barley Genotypes with High Arsenic Stress Tolerance

Ninety-four barley genotypes were used to investigate the genotypic differences in arsenic (As) uptake and translocation and their relationships with As tolerance index (TI) and translocation factor (TF). Two As treatments (300 µM and 500 µM) were applied in the initial screening and the confirmatory experiments, respectively. The results showed significant (p < 0.05) differences in tissue biomass, shoot height, root length, As TI and TF among genotypes. Based on As TI, 11 barley genotypes were selected and divided into 3 groups, i.e. tolerant, mildly tolerant and sensitive. There was more As uptake in the roots of the As tolerant genotypes, while the As sensitive genotypes contained more As in shoots, which was further proved by the greater TF. Significantly negative correlation was observed between shoot and root As concentration. The results showed that As tolerant genotypes are able to restrict the upward movement of As, thus developing their tolerance.