绿色荧光蛋白标记解淀粉芽孢杆菌Bam22在油菜体内的定殖

研究GFP标记的解淀粉芽孢杆菌Bam22在油菜植株上的定殖规律,为其开发利用提供科学依据.采用自然转化法将携带绿色荧光蛋白基因的质粒pGFP4412导入Bam22细胞中,构建GFP荧光标记菌株;对比野生型菌株Bam22与标记菌株Bam22-GFP的生长曲线和抑菌能力;通过灌根法,观察标记菌株在油菜体内不同组织部位的定殖...     

植物碳同位素分馏在水分利用效率研究中的应用

稳定碳同位素测量法不受时间、空间限制,测定过程简便准确,为了消除常规传统测定水分利用效率(WUE)方法中的缺陷,可将稳定碳同位素示踪技术引用于指示作物的WUE中。本研究综述了稳定碳同位素分馏的基本原理,从植物器官组织、气候因子和水分条件分析了稳定碳同位素分馏特征与WUE的关系和在植物抗旱节水育种上的应用。通过分析不同光合型植物稳定碳同位素分馏特征得出,WUE与碳同位素比值(δ¹³C)及碳同位素分辨率(Δ¹³C)具有相关性,植物不同部位器官的δ¹³C值均有差异,降雨量、光照强度和时长以及土壤水分都对植物δ¹³C值和WUE产生显著影响。因此,利用δ¹³C和Δ¹³C这两个稳定碳同位素指标能够更好地指示植物高WUE和抗旱性,可为提高植物WUE和选育抗旱性品种提供理论依据。     

水稻早世代稳定特异性的研究

利用9个具有早世代稳定遗传特性的水稻品系和7个栽培稻作为主体亲本杂交配组，在130个组合F2群体963个株系中，发现28个组合中出现73个稳定株系。遗传分析表明水稻早世代稳定既不是质量性状遗传也不是数量性状遗传，是按株群分离的遗传方式，出现稳定株系的组合F1群体发生了分离，F2群体中既有性状不分离的稳定株系又有孟德尔     

堆肥制作中的生物化学变化特征

通过人模拟堆制和同位素交叉标记，研究了以稻草和禽畜类为主体材料的堆肥制作过程中的生物化学变化特征，结果表明：有机物料的分解初期（０～２５ｄ）的快速分解阶段和中后期（２５～９０ｄ）的缓慢分解阶段，不同材料组合中以稻草加鸡粪处理分解最快，堆肥制作过程中全碳，全主Ｃ／Ｎ比值不断下降，但全氮相对含量上升，以稻草加鸡粪处理最明显，堆肥制作过程中，碳，氮的腐殖化作用明显，不同材料组合，氮的微生物同化和矿化作用     

氮肥配施秸秆和厩肥对土壤NH4＋-N和NO3--N转化的影响

设置了7个不同的施肥处理（①不施秸秆、氮肥和厩肥（CK）;②单施氮肥;③麦秸＋氮肥;④麦秸加倍＋氮肥;⑤麦秸＋氮肥＋厩肥;⑥玉米秸秆＋麦秸＋氮肥;⑦玉米秸秆＋麦秸＋氮肥＋厩肥）,研究不同处理对冬小麦季土壤NH4＋-N和NO3--N转化的影响。结果表明,氮肥配施秸秆和厩肥的处理冬小麦季土壤NH4＋-N和NO3-N的数量均以冬前最高,施厩肥处理土壤NH4＋-N和NO3--N的数量明显高于其他处理。     

枸杞岛海藻场角蝾螺夏季摄食选择性及其生态学意义

于2013年夏季对枸杞岛海藻场螺类优势种角蝾螺进行了稳定同位素、摄食选择性、消化代谢物粒径等系列实验.稳定同位素结果显示,角蝾螺是牧食性生物,在藻场中的营养级为2.12,属初级消费者,底栖海藻是角蝾螺的主要食源,贡献率为94.5％;摄食选择性实验结果显示,角蝾螺具有较宽的摄食选择,能够摄食海带、铜藻、粗枝软骨藻等1 1种大型藻类,其中铜藻及蜈蚣藻是枸杞岛潮下带的重要优势种;消化代谢物实验结果显示,角蝾螺的啃食作用能为藻场碎屑提供增量,角蝾螺对海藻场碎屑的增量为(0.016 ～0.094)g/d,经过啃食及消化作用产生的碎屑主要粒级为1Φ(＞ 250 μm).稳定同位素分析—摄食选择偏好实验—螺类消化代谢物粒径分析的系列研究表明,角蝾螺在枸杞岛海藻场的群落食物网中,可以起到连接牧食食物链和碎屑食物链的重要作用.     

Carbon source and trophic position of pelagic fish in coastal waters of south-eastern Izu Peninsula,Japan, identified by stable isotope analysis

ABSTRACT:   It is important to clarify trophic dynamics in marine ecosystems for management of the fishing ground. Organic carbon sources and trophic position of pelagic fishes in the coastal waters of the south-eastern Izu Peninsula, Japan, were examined on the basis of carbon and nitrogen stable isotope distributions. The δ¹³C of the fishes was mostly distributed from −19 to −16‰ for nektonic fishes (13 species of adults and immatures) and planktonic fishes (10 species of larvae and juveniles), close to the δ¹³C values of particulate organic matter and planktonic decapods. These δ¹³C signatures for the inhabitants of the water column were in contrast with the high δ¹³C values (mainly −16 to −13‰) for demersal fishes of Scorpaeniformes and benthic polychaetes collected in the surf zone. These results indicate that nektonic and planktonic fishes depend on phytoplankton for carbon supply. The δ¹⁵N signatures suggest that the trophic position ranged 3.1–4.5 for the nektonic fishes and 2.9–3.7 for the planktonic fishes, premised on trophic level 3 for larval Japanese anchovy Engraulis japonicus . Thus, planktivorous fishes should be mainly assigned to trophic levels 3 and 4 in this area.     

Role of nitrite and nitric oxide in the processes of nitrification and denitrification in soil: Results from N tracer experiments

Recent research has proven soil nitrite to be a key element in understanding N-gas production (NO, N₂O, N₂) in soils. NO is widely accepted to be an obligatory intermediate of N₂O formation in the denitrification pathway. However, studies with native soils could not confirm NO as a N₂O precursor, and field experiments mainly revealed ammonium nitrification as the source of NO. The hypothesis was constructed, that the limited diffusion of NO in soil is the reason for this contradiction. To test this diffusion limitation hypothesis and to verify nitrite and NO as free intermediates in native soils we conducted through-flow (He/O₂ atmosphere) ¹⁵N tracer experiments using black earth soil in an experimental set up free of diffusion limitation. All of the three relevant inorganic N soil pools (ammonium, nitrite, nitrate) were ¹⁵N labelled in separate incubation experiments lasting 81 h based on the kinetic isotope method. During the experiments the partial pressure of O₂ was decreased in four steps from 20% to about 0%. The net NO emission increased up to 3.7 μg N kg⁻¹ h⁻¹ with decreasing O₂ partial pressure. Due to the special experimental set up with little to no obstructions of gas diffusion, only very low N₂O emission could be observed. As expected the content of the substrates ammonium, nitrate and nitrite remained almost constant over the incubation time. The ¹⁵N abundance of nitrite revealed high turnover rates. The contribution of nitrification of ammonium to the total nitrite production was approx. 88% under strong aerobic soil conditions but quickly decreased to zero with declining O₂ partial pressure. It is remarkable that already under the high partial pressure of 20% O₂ 12 % of nitrite is generated by nitrate denitrification, and under strict anaerobic conditions it increases to 100%. Nitrite is present in two separate endogenous pools at least, each one fed by the nitrification of ammonium or the denitrification of nitrate. The experiments clearly revealed that nitrite is almost 100% the direct precursor of NO formation under anaerobic as well as aerobic conditions. Emitted N₂O only originated to about 100% from NO under strict anaerobic conditions (0-0.2% O₂), providing evidence that NO is a free intermediate of N₂O formation by denitrification. To the best of our knowledge this is the first time that NO has been detected in a native soil as a free intermediate product of N₂O formation at denitrification. These results clearly verify the “diffusion limitation” hypothesis.     

利用黄土中碳同位素推断古植被类型

黄河中游黄土高原生态环境十分脆弱,已成为中国乃至世界林业、农业、地质和环境专家关注的热点地区.黄土地层中保存着大陆上最完整、最连续的古气候记录(顾兆炎,1991).黄土沉积以黄土层和古土壤层交互沉积为特征.学者们已从各个角度来挖掘这些记录,以探寻最好的气候指标,提取可靠的古气候、古植被信息.