CCL28受体在仔猪胃肠道组织中的表达研究

应用RT-PCR的方法,分别检测了CCR10（CCL28受体）在15d和30d仔猪胃肠道组织中的表达。结果表明,CCR10在15d仔猪的十二指肠、空肠、回肠、盲肠、结肠、胃和30d仔猪的十二指肠下段、空肠、回肠、盲肠、结肠、直肠、胃组织有表达;15d仔猪的十二指肠下段、直肠组织中无表达,空肠、盲肠、胃组织表达较少;30d仔猪的十二指肠上段组织无表达,十二指肠下段、直肠和胃组织表达弱。     

水稻瘤矮病毒 P3、P7、P8、Pn9、Pn10、Pn11、Pn12 的酵母双杂交载体的构建及自激活效应检测

将编码水稻瘤矮病毒P3、P7、P8、Pn9、Pn10、Pn11、Pn12的S3,S7,S8,S9,S10,S11和S12基因分别克隆到酵母表达载体pGBKT7和pGADT7中,转化AH109酵母细胞,结果显示:除pGBK-S10转化子可以在SD/-Trp和SD/-His营养缺陷固体培养基上正常生长外,其它转化子均只能在SD/-Trp或SD/-Leu营养缺陷固体培养基上正常生长.通过α-半乳糖苷酶活性分析揭示,除pGBK-S10可以在SD/-Trp/X-α-Gal平板上生长并变蓝外,其它均不变蓝.结果证实:RGDV Pn10在酵母细胞中具有转录激活活性,融合GAL4的RGDV Pn10蛋白可以在酵母细胞内激活HIS3和MEL1报告基因的表达.暗示该蛋白可能在病毒的侵染和复制过程中参与调控病毒或寄主基因的转录表达.     

气温对祁连山不同植被状况土壤呼吸的影响

通过对祁连山不同植被类型2 0 0 3年生长季节土壤呼吸的季节动态、日变化及土壤呼吸对气温变化响应的研究发现,指数模型能够较好地揭示不同植被类型对温度变化的响应,且低温时模型的拟合效果更好;各群落土壤呼吸的季节动态与温度变化不完全同步,表明温度并不是影响土壤呼吸的唯一因子,但能在一定程度上解释土壤呼吸的季节变化;不同植被类型的Q10 值介于2 16～4 92之间,青海云杉林(海拔2 75 0m)群落的Q10 值高于其它植被类型,说明不同的植被覆盖状况会影响到土壤呼吸对温度变化的敏感程度     

红外加热对大豆生态系统CO_2排放的影响

通过田间试验,采用静态箱-气相色谱法测定CO2排放通量,研究红外加热增加叶面温度对土壤、大豆-土壤系统CO2排放的影响。结果表明,红外加热叶面增温2℃促进了土壤CO2的排放,在鼓粒-成熟期对照与增温的排放通量分别为202.09±28.75、378.34±156.17mg·m-2·h-1,增温处理使CO2排放通量增加了87.21%,但未达到显著水平;增温使土壤CO2累积排放量显著增加了39.96%。对照和增温的大豆-土壤系统呼吸的气温敏感性系数Q10值分别为0.68和2.54,土壤呼吸的土壤温度Q10值分别为4.22和1.68。研究表明,增温能促进土壤CO2排放,增加大豆-土壤系统呼吸的Q10值,降低土壤呼吸的Q10值。研究结果可为气候变化条件下估算区域农田温室气体排放提供一定的科学依据。     

Soil physicochemical and microbial drivers of temperature sensitivity of soil organic matter decomposition under boreal forests

Soil organic matter(SOM)in boreal forests is an important carbon sink.The aim of this study was to assess and to detect factors controlling the temperature sensitivity of SOM decomposition.Soils were collected from Scots pine,Norway spruce,silver birch,and mixed forests(O horizon)in northern Finland,and their basal respiration rates at five different temperatures(from 4 to 28℃)were measured.The Q_(10) values,showing the respiration rate changes with a 10℃ increase,were calculated using a Gaussian function and were based on temperature-dependent changes.Several soil physicochemical parameters were measured,and the functional diversity of the soil microbial communities was assessed using the MicroResp?method.The temperature sensitivity of SOM decomposition differed under the studied forest stands.Pine forests had the highest temperature sensitivity for SOM decomposition at the low temperature range(0–12℃).Within this temperature range,the Q_(10) values were positively correlated with the microbial functional diversity index(H'_(mic))and the soil C-to-P ratio.This suggested that the metabolic abilities of the soil microbial communities and the soil nutrient content were important controls of temperature sensitivity in taiga soils.     

Soil CO2 efflux vs. soil respiration: Implications for flux models

In the long term, all CO₂ produced in the soil must be emitted by the surface and soil CO₂ efflux (FCO₂) must correspond to soil respiration (R_soil). In the short term, however, the efflux can deviate from the instantaneous soil respiration, if the amount of CO₂ stored in the soil pore-space (SCO₂) is changing. We measured FCO₂ continuously for one year using an automated chamber system. Simultaneously, vertical soil profiles of CO₂ concentration, moisture, and temperature were measured in order to assess the changes in the amount of CO₂ stored in the soil. R_soil was calculated as the sum of the rate of change of the CO₂ storage over time and FCO₂. The experiment was split into a warm and a cold season. The dependency of soil respiration and soil efflux on soil temperature and on soil moisture was analyzed separately. Only the moisture-driven model of the warm season was significantly different for FCO₂ and R_soil. At our site, a moisture-driven soil-respiration model derived from CO₂ efflux data would underestimate the importance of soil moisture. This effect can be attributed to a temporary storage of CO₂ in the soil pore-space after rainfalls where up to 40% of the respired CO₂ were stored.     

东北农场农作物生长季土壤呼吸对温度和含水量的响应

通过静态碱液吸收法测定了东北典型农场水稻和玉米两种农作物在生长期（4—7月）的土壤呼吸速率及其变化规律,分析了不同深度的土壤呼吸速率对土壤温度和土壤含水量的响应。结果表明:在作物生长期,水稻样地的土壤呼吸速率高于玉米样地。水稻和玉米样地在0—15 cm深度的土壤呼吸速率明显高于15—30 cm和30—60 cm。随着土壤深度的增加,土壤呼吸速率逐渐减小。水稻土壤的呼吸速率最大值为580.6 μg/（kg·h）,最小值为160.4 μg/（kg·h）;而玉米的土壤呼吸速率最大值为565.3 μg/（kg·h）,最小值为137.5 μg/（kg·h）。水稻和玉米样地土壤呼吸速率与土壤温度呈现极显著相关关系（p<0.01）,土壤温度曲线在4月到6月初明显上升,而土壤呼吸速率曲线在这一时段也呈相同态势;6月下旬到7月初土壤温度变化平稳,土壤呼吸速率与土壤温度的同步变化趋势不明显。同时,两种作物的土壤含水量与土壤呼吸速率间的相关性也极为显著（p<0.01）,说明土壤含水量也能够解释生长期水稻和玉米的土壤呼吸速率变化。     

印度芥菜BjJ10-2基因原核表达载体构建及抗盐功能的鉴定

利用RT-PCR技术克隆了印度芥菜核糖体相关膜蛋白RAMP4家族成员BjJ10-2基因的开放读码框,成功构建了pET32a-BjJ10-2原核表达栽体,通过热激法将其转化到原核表达菌株BL21(DE3)plysS中,得到重组大肠杆菌BL21(pET32a-BjJ10-2).SDS-PAGE凝胶电泳检测到在IPTG诱导下...     

Temperature sensitivity of organic matter decomposition in two boreal forest soil profiles

Controversial conclusions from different studies suggest that the decomposition of old soil organic matter (SOM) is either more, less, or equally temperature sensitive compared to the younger SOM. Based on chemical kinetic theory, the decomposition of more recalcitrant materials should be more temperature sensitive, unless environmental factors limit decomposition. Here, we show results for boreal upland forest soils supporting this hypothesis. We detected differences in the temperature sensitivity 1) between soil layers varying in their decomposition stage and SOM quality, and 2) inside the layers during a 495 day laboratory incubation. Temperature sensitivity increased with increasing soil depth and decreasing SOM quality. In the organic layers, temperature sensitivity of decomposition increased during the early part of a 495 day laboratory incubation, after respiration rate and SOM quality had notably decreased. This indicates that decomposition of recalcitrant compounds was more temperature sensitive than that of the labile ones. Our results imply that Q₁₀ values for total heterotrophic soil respiration determined from short-term laboratory incubations can either underestimate or overestimate the temperature sensitivity of SOM decomposition, depending on soil layer, initial labile carbon content and temperature range used for the measurements. Using Q₁₀ values that ignore these factors in global climate models provides erroneous estimates on the effects of climate change on soil carbon storage.     

Biotic and abiotic factors regulating forest floor CO2 flux across a range of forest age classes in the southern Appalachians

We measured forest floor CO₂ flux in three age classes of forest in the southern Appalachians: 20-year-old, 85-year-old, and old-growth. Our objectives were to quantify differences in forest floor CO₂ flux among age classes, and determine the relative importance of abiotic and biotic driving variables. Forest floor CO₂ flux was measured using an openflow infrared gas analyzer measurement system for 24 h periods and samples were taken every 2 months over a 2-year period. Litter/soil interface, soil temperature (5 cm depth), soil moisture (%), forest floor moisture (%), forest floor mass, fine root (2 mm) mass, coarse root mass (>2 mm), forest floor C and N (%), fine root C and N, coarse root C and N, and soil N and C were co-measured during each sample period. Results showed significant nonlinear relationships (r²=0.68 to 0.81) between litter/soil interface temperature and forest floor CO₂ flux for all three forest age classes, but no differences in temperature response parameters. These results indicated no differences in forest floor CO₂ flux among age classes. Considerable temporal variation in abiotic and biotic variables was observed within and among forests. Biotic variables correlated with forest floor CO₂ flux included indices of litter and root quality. Differences in biotic variables correlated with forest floor CO₂ flux among forests may have been related to shifts in the relative importance of heterotrophic and autotrophic respiration components to overall forest floor CO₂ flux.