Requirement for CD4 T cell help in generating functional CD8 T cell memory

Although primary CD8 responses to acute infections are independent of CD4 help, it is unknown whether a similar situation applies to secondary responses. We show that depletion of CD4 cells during the recall response has minimal effect, whereas depletion during the priming phase leads to reduced responses by memory CD8 cells to reinfection. Memory CD8 cells generated in CD4+/+ mice responded normally when transferred into CD4-/- hosts, whereas memory CD8 cells generated in CD4-/- mice mounted defective recall responses in CD4+/+ adoptive hosts. These results demonstrate a previously undescribed role for CD4 help in the development of functional CD8 memory.     

施肥水平及群体结构对茄子单株和群体效应的影响

研究了不同施肥水平及种植密度对茄子单株和群体效应的影响,结果表明:单株产量随着密度的增加而减少.密度对群体产量的影响与施肥水平有关.在低肥时,密度应小,高肥时可适当提高密度,品种才能获得高产稳产.随着密度的逐步降低,个体补偿效应和群体补偿效应下降,施肥水平越高,补偿效应下降越明显.     

高粱根质膜的纯化和膜蛋白的提取

利用高粱根作为实验材料,用不连续蔗糖密度梯度和Dextran T-500/PEG-3350两相法探讨了纯化质膜的过程,以及去垢剂对K+运输蛋白的增溶效率.结果表明,由6 mL 40%(W/W),4 mL 34%(W/W)和4 mL 22%(W/W)蔗糖组成的不连续蔗糖梯度,经80 000×g离心3 h后,在34%～40%界面处富含质膜.在质膜K+运输蛋白的增溶效果上,6.5 mmol/L CHAPS最为理想.     

Protein conformations in the plasma membrane

Infrared spectroscopy and optical rotatory dispersion have been used to test theories of structure of membrane protein. No evidence has been found to support the view that adjacent to the lipid there is a monolayer of protein in the beta-conformation. The extracted protein appears to be a fairly typical globular protein with a low a-helical content.     

马铃薯需水规律试验研究

对马铃薯各生育阶段需水规律进行研究,结果表明:马铃薯最佳的水分下限指标为苗期65%、块茎形成期75%、块茎增长期80%、淀粉积累期60%～65%;马铃薯不同阶段的需水量不同,呈现前期耗水强度小、中期逐渐变大、后期又减小的近似抛物线的趋势;马铃薯耗水量354.59～372.69 mm是确定经济灌溉定额的主要研究范围;其块茎增长期需水量最多,需水敏感期为开花期。研究马铃薯各生育阶段的需水量和需水规律,科学用水,可为今后种植马铃薯、优化灌溉制度和水量分配提供参考。     

小麦测土配方施肥试验

采用小麦＂3414＂试验不完全实施方案,在济阳县回河镇小麦、玉米一年两熟地上,进行小麦测土配方施肥技术研究。结果表明,每公顷施纯N454.55 kg、P2O5750.00 kg、K2O148.00 kg为最佳施肥方案,小麦产量最高,达7 431.00 kg/hm^2。     

A mechanosensitive ion channel in the yeast plasma membrane

Mechanosensitive ion channels use mechanical energy to gate the dissipation of electrochemical gradients across cell membranes. This function is fundamental to physiological processes such as hearing and touch. In electrophysiological studies of ion channels in the plasma membrane of the yeast Saccharomyces cerevisiae, channels were observed that were activated by, and adapted to, stretching of the membrane. Adaptation of channel activity to mechanical stimuli was voltage-dependent. Because these mechanosensitive channels pass both cations and anions, they may play a role in turgor regulation in this walled organism.     

Hormone-calcium interactions with the plasma membrane of rat liver cells

The binding constants and the number of binding sites for insulin, glucagon, epinephrine, cyclic adenosine monophosphate, and calcium ions for the plasma membrane of rat liver were determined by Scatchard plots. The plots are biphasic or multiphasic, an indication of at least two types of binding sites for each ligand. At least three types of binding sites were found for insulin. In the concentration range of 10(-6) to 10(-8) molar, glucagon, epinephrine, and hydro-cortisone increased calcium ion binding to the plasma membrane, whereas insulin decreased this binding. At hormone concentrations of 10(-6) to 10(-7) molar, glucagon was the most effective in increasing calcium binding, but at a hormone concentration of 10(-8) molar, hydrocortisone was the most effective in stimulating calcium binding. Adenosine triphosphate reversed the effect of insulin and inhibited the effect of the other hormones. These studies suggest a relation between hormones and calcium with respect to membrane structure and function.     

施肥开沟机作业信息远程监测方法与试验

针对目前施肥开沟机缺少作业信息检测装置及其远程监测的需要,基于惯性传感器技术、数据处理技术及网络通讯技术,开发施肥开沟机作业信息远程监测系统。所检测施肥开沟机作业信息包括开沟深度、油耗、作业时间、作业轨迹和作业距离,其中,油耗采用超声波油位传感器检测,作业时间通过设定界限值判断是否为作业段来检测,作业距离和作业轨迹则依赖于GPS定位。由于开沟深度和农作物产量相关,作业信息检测方法重点围绕开沟深度进行研究。采用2个惯性传感器分别检测开沟机和车身的俯仰角,相减得到的倾角差值结合开沟机相关尺寸计算可得开沟深度。基于卡尔曼滤波算法对倾角差值进行滤波以减小机具振动等产生的检测误差。在MATLAB中建立倾角差滤波模型进行仿真,仿真发现:Q/R比值不变,Q、R值变化时,滤波效果基本相同;Q/R比值不同时,随Q/R减小,滤波后倾角差的方差越小,但滞后效果越明显。倾角差滤波试验分为2部分:1)滤波验证试验以模型车为载体,利用不同Q、R参数进行试验,结果与仿真结论一致;2)土槽试验中固定Q、R参数,倾角差经滤波,其方差由4.07减小为0.47,表明滤波有效。田间试验对作业信息进行检测,结果表明:1)开沟深度检测误差在5%以内,结果精确;2)其他作业信息检测准确,检测方法可靠,远程监测系统具有实用价值。     

梨品种需冷量评价模式

为确定梨需冷量适宜的评价模型,2009-2012年对28份梨品种应用≤7.2℃模型、0～7.2℃模型和犹他模型进行测试比较分析。结果表明,以秋季日平均温度稳定低于7.2℃的日期为需冷量测定的起点,以≤7.2℃模型累积低温值作为梨需冷量的评价标准比较适宜;0～7.2℃模型在长需冷量范围内能有效预测休眠的结束,不适宜低需冷量品种的测定;犹他模式不适宜作为梨品种需冷量评价模式。     

作物需水信息系统的研究

掌握准确的作物生长信息和温室内外气候状况,对灌溉决策有着重要的意义.本文采用无损检测对温室作物冠层微气候、土壤环境、室内外气候信息实时采集,利用无线数字传输技术将子站的采集数据发送到主站,主站和PC机之间通过RS232通信对数据进行存储和显示.实践证明:该系统工作稳定,数据传输可靠,基本达到了设计要求.     

Mobility and the restriction of mobility of plasma membrane lectin-binding components

Labeling by ferritin-conjugated agglutinins from Ricinus communis was used to demonstrate the relative mobilities of the agglutinin receptors located in specific regions on plasma membranes of rabbit spermatozoa. The relative mobility of lectin receptors was higher on postacrosomal regions of sperm than on acrosomal and tail regions. Lectin-induced clustering could not be demonstrated in the acrosomal and tail regions, an indication of the existence of localized restraints on the mobilities of lectin receptors. A system of transmembrane restraints may maintain the segregation of plasma membrane components into membrane domains on certain highly differentiated cells.     

农民科技需求与解决途径研究

农民科技需求是市场经济条件下,农民追求利润最大化的必然反映,也是农业科技发展的动力因素之一。通过研究黑龙江省院县共建10个县3 a科技专家大院农民咨询记录,分析了新时期农业生产中农民科技需求总体状况、满足农民科技需求的方式、内容。阐述了黑龙江省通过实施院县科技合作共建,建科技园区、办专家大院、推致富项目、搞科技培训的四位一体科技帮扶模式,有效地实现科研与生产、专家与农民、科技与农业有效对接的新机制。     

糖蔗养分运筹技术研究

通过田间试验研究了不同养分运筹模式对甘蔗产量、效益的影响。结果表明,随着施肥次数的增加,甘蔗株高、单茎重、产量及效益均呈较明显增加趋势。采用一基三追、一基二追、一基一追施肥处理单茎重较一次性施肥分别增加9.0%、6.8%和4.5%,产量分别提高15.7%、12.5%和10.1%,每667m2生产效益较习惯施肥分别提高298、250、227元。说明甘蔗生产适宜采用一基三追或一基二追养分运筹模式。     

秋花生优化施肥研究

运用310拟饱和最优回归设计,在沿海花生主产区(赤砂土)设置秋花生施用氮磷钾肥料试验,采用DPS数据处理系统模拟出留种田秋花生商品产量和施肥利润的氮磷钾肥料效应函数,极值判别结果均为非典型函数,通过频率分析方法寻优,分别获得秋花生较高产量(2 205.89 kg@hm-2)施肥组合为Z1(N)=85.54 kg@hm-2,Z2(P2O5)=39.40 kg@hm-2,Z3(K2O)=93.61 kg@hm-2;较佳利润(8 325.46元@hm-2)施肥组合为Z1(N)=88.10 kg@hm-2,Z2(P2O5)=45.36 kg@hm-2,Z3(K2O)=108.89 kg@hm-2.     

幼建鲤维生素C需要量标识研究

对幼建鲤维生素C需要量的确定标识进行了研究 ,选择初始体重为 12g左右 (P >0 0 5 )的健康幼建鲤 5 76尾 ,平均分成 6组 ,每组 96尾 ,每组设 3个重复 ,每个重复 32尾 ,分别饲喂含维生素C为 10mg/kg、2 5mg/kg、4 5mg/kg、6 0mg/kg、90mg/kg、12 0mg/kg的半纯合饵料 70d。结果表明 :增重、状态系数、肝胰重与饵料维生素C水平呈极显著二次回归关系 (P <0 0 1) ,饵料系数、体长和后肾维生素C含量与饵料维生素C水平呈显著的二次相关(P <0 0 5 ) ,当饵料维生素C分别为 6 6 6 0mg/kg、6 1 74mg/kg、6 1 6 4mg/kg、6 9 5 1mg/kg、6 0 5 6mg/kg和 10 3 73mg/kg时 ,分别达到最佳增重、最佳状态系数、最大肝胰重、最低饵料系数或最佳饲料利用率、最佳体长和最大后肾维生素C含量     

蛋重和蛋形指数对绿头野鸭种蛋孵化率的影响

选取1650枚合格绿头野鸭种蛋,测量蛋重和蛋形指数,研究蛋重和蛋形指数对绿头野鸭种蛋孵化率的影响。试验结果表明,绿头野鸭种蛋在51~55.9 g,蛋的长径在5.4~5.9 cm,短径在4.1~4.4 cm,即蛋形指数在1.30~1.35之间孵化效果较好。     

论数字图书馆对馆员的要求

文章介绍了数字图书馆的特征，以及如何适应数字图书馆的要求，着重论述了数字图书馆馆员所具备的素质及相应的对策。     

农民对市场信息需求的行为分析

在建立社会主义市场经济体制的新形势下,农民迫切需要种植、养殖、农产品加工销售、农资供应等方面的信息.文章分析了现阶段农民究竟需要什么信息;农民获取农业信息有哪几种途径;以及农民对市场信息服务工作的要求.     

A G protein-coupled receptor is a plasma membrane receptor for the plant hormone abscisic acid

The plant hormone abscisic acid (ABA) regulates many physiological and developmental processes in plants. The mechanism of ABA perception at the cell surface is not understood. Here, we report that a G protein-coupled receptor genetically and physically interacts with the G protein alpha subunit GPA1 to mediate all known ABA responses in Arabidopsis. Overexpressing this receptor results in an ABA-hypersensitive phenotype. This receptor binds ABA with high affinity at physiological concentration with expected kinetics and stereospecificity. The binding of ABA to the receptor leads to the dissociation of the receptor-GPA1 complex in yeast. Our results demonstrate that this G protein-coupled receptor is a plasma membrane ABA receptor.