Atmospheric CO2 concentrations over the last glacial termination

A record of atmospheric carbon dioxide (CO2) concentration during the transition from the Last Glacial Maximum to the Holocene, obtained from the Dome Concordia, Antarctica, ice core, reveals that an increase of 76 parts per million by volume occurred over a period of 6000 years in four clearly distinguishable intervals. The close correlation between CO2 concentration and Antarctic temperature indicates that the Southern Ocean played an important role in causing the CO2 increase. However, the similarity of changes in CO2 concentration and variations of atmospheric methane concentration suggests that processes in the tropics and in the Northern Hemisphere, where the main sources for methane are located, also had substantial effects on atmospheric CO2 concentrations.     

模拟大气中不同CO2含量对水稻生长发育的影响

将水稻种子培养在不同CO2含量的模拟大气玻璃罩内，研究水稻种子萌发期和水稻生长发育的生理变化。结果表明：模拟大气中CO2含量在350-450mg／L范围内，随着大气中CO2含量增加，水稻种子萌发时酸性磷酸酯酶、过氧化氢酶和三磷酸腺苷含量分别提高12．0％、20．5％和24．3％，即水稻种子活力增强，代谢旺盛；随着大气中2含量的增加，水稻幼苗对氮、磷养分的吸收利用能力增强，硝酸还原酶活性有所提高，有利于幼苗生长；水稻苗期以大气CO2含量为500mg／L时光合能力最强，拔节期和孕穗期以大气CO2含量为450mg／L时水稻光合能力最强；水稻经济产量以大气CO2含量为500mg／L时增产幅度最大，比对照(CO2含量为350mg／L)增产10．2％。     

Negative feedback regulation ensures the one receptor-one olfactory neuron rule in mouse

In the mouse olfactory system, each olfactory sensory neuron (OSN) expresses only one odorant receptor (OR) gene in a monoallelic and mutually exclusive manner. Such expression forms the genetic basis for OR-instructed axonal projection of OSNs to the olfactory bulb of the brain during development. Here, we identify an upstream cis-acting DNA region that activates the OR gene cluster in mouse and allows the expression of only one OR gene within the cluster. Deletion of the coding region of the expressed OR gene or a naturally occurring frame-shift mutation allows a second OR gene to be expressed. We propose that stochastic activation of only one OR gene within the cluster and negative feedback regulation by that OR gene product are necessary to ensure the one receptor-one neuron rule.     

生态温室系统中作物冠层的CO2分布

将生态温室系统室内环境划分为主体环境与微环境两部分,在主体环境的基础上系统研究了生态温室系统中作物冠层的CO2微环境.以成行的单个植株描述冠层,以空心圆柱体描述植株的简化方法,在考虑冠层内空气运动的基础上,对冠层的每一层建立CO2的物质平衡方程,建立了CO2动态分析模型.以一山东的生态温室为例,利用实测试验数据对模型模拟结果进行了验证.     

Food for thought: lower-than-expected crop yield stimulation with rising CO2 concentrations

Model projections suggest that although increased temperature and decreased soil moisture will act to reduce global crop yields by 2050, the direct fertilization effect of rising carbon dioxide concentration ([CO2]) will offset these losses. The CO2 fertilization factors used in models to project future yields were derived from enclosure studies conducted approximately 20 years ago. Free-air concentration enrichment (FACE) technology has now facilitated large-scale trials of the major grain crops at elevated [CO2] under fully open-air field conditions. In those trials, elevated [CO2] enhanced yield by approximately 50% less than in enclosure studies. This casts serious doubt on projections that rising [CO2] will fully offset losses due to climate change.     

超临界CO2萃取山豆根氧化苦参碱最佳条件的研究

通过4因素3水平的响应曲面试验设计,采用分步萃取的试验操作,对超临界CO2萃取山豆根氧化苦参碱最佳条件进行研究.结果表明,在不同萃取阶段,萃取物质量和氧化苦参碱含量有所差异,综合考虑,第1步萃取的条件为萃取温度30℃,萃取压力45MPa,携带剂乙醇浓度100%,携带剂用量80mL·100g-1;第2步萃取的条件为萃取温度55℃,萃取压力35MPa,不使用携带剂.提取条件经试验验证,切实可行.原料中氧化苦参碱的萃取率为98%左右.     

Temperature sensing by an olfactory neuron in a circuit controlling behavior of C. elegans

Temperature is an unavoidable environmental cue that affects the metabolism and behavior of any creature on Earth, yet how animals perceive temperature is poorly understood. The nematode Caenorhabditis elegans "memorizes" temperatures, and this stored information modifies its subsequent migration along a temperature gradient. We show that the olfactory neuron designated AWC senses temperature. Calcium imaging revealed that AWC responds to temperature changes and that response thresholds differ depending on the temperature to which the animal was previously exposed. In the mutant with impaired heterotrimeric guanine nucleotide-binding protein (G protein)-mediated signaling, AWC was hyperresponsive to temperature, whereas the AIY interneuron (which is postsynaptic to AWC) was hyporesponsive to temperature. Thus, temperature sensation exhibits a robust influence on a neural circuit controlling a memory-regulated behavior.     

A Large Northern Hemisphere Terrestrial CO2 Sink Indicated by the 13C/12C Ratio of Atmospheric CO2

Measurements of the concentrations and carbon-13/carbon-12 isotope ratios of atmospheric carbon dioxide can be used to quantify the net removal of carbon dioxide from the atmosphere by the oceans and terrestrial plants. A study of weekly samples from a global network of 43 sites defined the latitudinal and temporal patterns of the two carbon sinks. A strong terrestrial biospheric sink was found in the temperate latitudes of the Northern Hemisphere in 1992 and 1993, the magnitude of which is roughly half that of the global fossil fuel burning emissions for those years. The challenge now is to identify those processes that would cause the terrestrial biosphere to absorb carbon dioxide in such large quantities.     

棚内释放CO2对草莓生长的影响

通过在大棚内草莓的释放CO2的试验，结果表明：棚内释放CO2能增强作物的光合作用，使草莓长势好，提高草莓早期产量，且释放CO2气肥比颗粒剂CO2效果明显，经济效益均比对照显著。     

超临界CO_2萃取燕麦麸油的工艺研究

采用超临界CO2流体萃取技术从燕麦麸皮中萃取燕麦麸油,考察了萃取压力、温度、时间对麸油提取率的影响.结果表明:3因素对麸油萃取率影响的主次顺序依次为:萃取温度>萃取压力>萃取时间。通过正交试验确定了萃取燕麦麸油的最佳工艺条件:萃取压力30 MPa,萃取温度40℃,萃取时间2 h,在此工艺条件下燕麦麸油提取率为5.45%,且其理化指标优于米糠油.     

CO2加富和CPPU处理对提高瓠瓜果实产量的增效作用

研究了不同浓度CO2及CPPU处理对瓠瓜(Lagenaria leucantha Rusby)光合作用及果实产量的影响,并探讨了CO2加富对瓠瓜果实产量影响的作用机理.结果表明:提高大棚中的CO2浓度(1 000 μl/L,2 000 μl/L)增强了CPPU对瓠瓜果实增产的效果,但不同浓度CO2对自然授粉株的果实产量影响不大.CPPU处理提高了植株光合速率,增加了瓠瓜座果数,达到增产增收的效果.     

PCR方法检测猪园环病毒2型感染

参考GenBank已发表的PCV-2基因序列,根据PCV-2(AFff27217)和PCV-1(U49186)全基因序列设计合成-对引物,进行PCR扩增,产物经琼脂糖凝胶电泳,呈现一条大小约1 154 bp的特异条带,经条件优化,建立了猪病料中PCV-2感染的PCR检测方法.采用建立的PCR方法对江西各地猪场133份猪的病料进行PCV-2检测,结果表明,受检猪的组织及血清样品中PCV-2的总检出率为53.38%,证实江西各地猪场存在PCV-2感染.     

温室内CO2浓度变化的影响因素及增施CO2的生物效应

对温室内CO2浓度变化的基本规律及影响CO2浓度的主要因素进行了综述;总结了温室内增施CO2的生物学效应,温室内增强CO2有利于作物生长发育,提高抗寒力,增加产量,改善品质。     

超临界CO2流体提取法提取川楝子中的川楝素

[目的]优选超临界CO2流体提取法提取川楝子中的川楝素的最佳提取工艺条件。[方法]以乙醇为提取剂,采用单因素试验考察了乙醇浓度、浸泡时间、提取压力和提取时间等参数对川楝素提取率的影响,并采用正交试验优选出最佳提取工艺条件。[结果]优选出的最佳提取工艺条件为:温度为45℃、压力为30 MPa、时间为4 h、原料粒径为24目,夹带剂为浓度75%乙醇;在此条件下,川楝素的提取率为0.522%。[结论]该方法筛选出了川楝子中的川楝素的最佳提取工艺条件,为川楝子的提取利用提供了理论依据。     

超临界CO2流体萃取印楝种子中印楝素的研究

建立了用超临界流体从印楝种子中萃取印楝素的方法，用正交试验优化设计选择萃取条件，最佳萃取条件为：温度35℃，压力30MPa，夹带剂用量每克印楝种子干粉1．5mL甲醇，提取率明显优于溶剂法。     

超临界CO_2萃取分离高纯度辣椒碱化合物的研究

辣椒红色素厂的副产物辣椒精(辣椒碱含量2.1%)经过酒精溶液萃取、CO2超临界萃取、硅胶柱层析、重结晶等方法,从中分离出浅色的高纯度辣椒碱产品(辣椒碱含量90%),并对各分离操作的工艺条件进行了研究。采用紫外分光光度法和高效液相色谱法对辣椒精和高纯度产品做了检测,得到相应图谱。研究表明,上述分离步骤的组合是可行的、有效的。     

Nitrogen Deficiency Limited the Improvement of Photosynthesis in Maize by Elevated CO2 Under Drought

Global environmental change affects plant physiological and ecosystem processes. The interaction of elevated CO₂, drought and nitrogen (N) deficiency result in complex responses of C₄ species photosynthetic process that challenge our current understanding. An experiment of maize (Zea mays L.) involving CO₂ concentrations (380 or 750 µmol mol⁻¹, climate chamber), osmotic stresses (10% PEG-6000, −0.32 MPa) and nitrogen constraints (N deficiency treated since the 144th drought hour) was carried out to investigate its photosynthesis capacity and leaf nitrogen use efficiency. Elevated CO₂ could alleviate drought-induced photosynthetic limitation through increasing capacity of PEPC carboxylation (V_pmax) and decreasing stomatal limitations (SL). The N deficiency exacerbated drought-induced photosynthesis limitations in ambient CO₂. Elevated CO₂ partially alleviated the limitation induced by drought and N deficiency through improving the capacity of Rubisco carboxylation (V_max) and decreasing SL. Plants with N deficiency transported more N to their leaves at elevated CO₂, leading to a high photosynthetic nitrogen-use efficiency but low whole-plant nitrogen-use efficiency. The stress mitigation by elevated CO₂ under N deficiency conditions was not enough to improving plant N use efficiency and biomass accumulation. The study demonstrated that elevated CO₂ could alleviate drought-induced photosynthesis limitation, but the alleviation varied with N supplies.