Trans-synaptic Eph receptor-ephrin signaling in hippocampal mossy fiber LTP

The site of induction of long-term potentiation (LTP) at mossy fiber-CA3 synapses in the hippocampus is unresolved, with data supporting both pre- and postsynaptic mechanisms. Here we report that mossy fiber LTP was reduced by perfusion of postsynaptic neurons with peptides and antibodies that interfere with binding of EphB receptor tyrosine kinases (EphRs) to the PDZ protein GRIP. Mossy fiber LTP was also reduced by extracellular application of soluble forms of B-ephrins, which are normally membrane-anchored presynaptic ligands for the EphB receptors. The application of soluble ligands for presynaptic ephrins increased basal excitatory transmission and occluded both tetanus and forskolin-induced synaptic potentiation. These findings suggest that PDZ interactions in the postsynaptic neuron and trans-synaptic interactions between postsynaptic EphB receptors and presynaptic B-ephrins are necessary for the induction of mossy fiber LTP.     

Comparison of two forms of long-term potentiation in single hippocampal neurons

In invertebrate nervous systems, some long-lasting increases in synaptic efficacy result from changes in the presynaptic cell. In the vertebrate nervous system, the best understood long-lasting change in synaptic strength is long-term potentiation (LTP) in the CA1 region of the hippocampus. Here the process is initiated postsynaptically, but the site of the persistent change is unresolved. Single CA3 hippocampal pyramidal cells receive excitatory inputs from associational-commissural fibers and from the mossy fibers of dentate granule cells and both pathways exhibit LTP. Although the induction of associational-commissural LTP requires in the postsynaptic cell N-methyl-D-aspartate (NMDA) receptor activation, membrane depolarization, and a rise in calcium, mossy fiber LTP does not. Paired-pulse facilitation, which is an index of increased transmitter release, is unaltered during associational-commissural LTP but is reduced during mossy fiber LTP. Thus, both the induction and the persistent change may be presynaptic in mossy fiber LTP but not in associational-commissural LTP.     

Presynaptic kainate receptor mediation of frequency facilitation at hippocampal mossy fiber synapses

Inhibition of transmitter release by presynaptic receptors is widespread in the central nervous system and is typically mediated via metabotropic receptors. In contrast, very little is known about facilitatory receptors, and synaptic activation of a facilitatory autoreceptor has not been established. Here we show that activation of presynaptic kainate receptors can facilitate transmitter release from hippocampal mossy fiber synapses. Synaptic activation of these presumed ionotropic kainate receptors is very fast (<10 ms) and lasts for seconds. Thus, these presynaptic kainate receptors contribute to the short-term plasticity characteristics of mossy fiber synapses, which were previously thought to be an intrinsic property of the synapse.     

Combined analog and action potential coding in hippocampal mossy fibers

In the mammalian cortex, it is generally assumed that the output information of neurons is encoded in the number and the timing of action potentials. Here, we show, by using direct patchclamp recordings from presynaptic hippocampal mossy fiber boutons, that axons transmit analog signals in addition to action potentials. Excitatory presynaptic potentials result from subthreshold dendritic synaptic inputs, which propagate several hundreds of micrometers along the axon and modulate action potential-evoked transmitter release at the mossy fiber-CA3 synapse. This combined analog and action potential coding represents an additional mechanism for information transmission in a major hippocampal pathway.     

陆地棉主要经济性状的遗传相关分析

本研究采用加性-显性与环境互作的遗传模型，分析陆地棉8个杂交亲本和F1代28个组合的12个主要经济性状的两年试验资料，估算各项遗传方差分量和成对性状间各项遗传效应的相关。结果表明，产量性状间的相关受加性、显性和加性与环境互作相关共同影响。皮棉产量与纤维品质间的相关主要是加性效应相关。皮棉产量与纤维长度、麦克隆值呈正相关，与纤维强度、伸长率、整齐度呈负相关。纤维强度与纤维长度、整齐度、麦克隆值呈加性正相关。单铃重与衣分呈负相关。衣分与产量呈正相关，与纤维品质呈负相关。     

复合膳食纤维致大鼠降脂功效研究*

 探讨复合膳食纤维与3种单一膳食纤维对高脂血症大鼠体内脂类含量的影响。建立大鼠高脂血症模型后,在髙脂饲料中分别添加10％的膳食纤维：大豆纤维素(C组)、果胶(D组)、瓜儿豆胶(E组)以及大豆纤维素-果胶-瓜儿豆胶复合物(F组),同时设正常对照组(A组)和单纯高脂饲料对照组(B组)。8周后观察各种膳食纤维对大鼠的生长发育及脂类代谢的影响。结果显示,与B组比,各种膳食纤维皆可不同程度降低大鼠体内脂质水平(P>0.05,P<0.05,P<0.01 ),且以复合物组效果为佳(P<0.01)。研究表明,各种膳食纤维皆可不同程度地降低大鼠体内脂质含量,但复合膳食纤维的效果优于单一膳食纤维。     

基于投影寻踪分类法的甘蔗种质综合评价

基于投影寻踪分类法对40份从法国和菲律宾引进的甘蔗种质进行综合评价。方差分析结果表明,各种质间茎径、单茎质量、蔗糖分等主要工农艺性状均存在显著差异(P0.01),变异系数介于5.68%～51.55%,变异广泛。对各种质的株高、茎径、有效茎、单茎质量、锤度、甘蔗蔗糖分、蔗汁蔗糖分、简纯度和纤维分等9个主要工农艺性状指标进行投影方向和投影值大小分析,结果表明:投影方向以甘蔗蔗糖分的最高,其后依次为锤度、蔗汁蔗糖分、简纯度、单茎质量和茎径等,株高和有效茎的较低;40份种质投影值大小各异,根据投影值大小,结合聚类分析将40份种质划分为5个类群,各类群投影值介于0.00～2.50,其中,第Ⅳ类群的5份种质资源(FR97–127、FR97–53、VMC95–29、VMC96–169和VMC97–30)综合性状表现优良,可供甘蔗杂交利用。综合来看,投影寻踪分类法可作为大量甘蔗种质资源评价的有效途径。     

海陆回交群体主要农艺性状与纤维品质关系的探讨

为了通过农艺性状来预测棉花纤维品质,以新疆陆地棉系9和海岛棉新海16号及其回交自交后代BC4F2∶4群体为研究材料,对165份材料的农艺性状和纤维品质性状进行鉴定,利用相关分析、主成分分析、回归分析和通径分析等方法,探讨群体主要农艺性状与纤维品质的关系.结果 表明,海陆回交群体的表型非常丰富,12个性状的变异系数为0....     

不同限制因子对苎麻纤维细度的影响

根据湖南农学院苎麻研究所近20年的研究,结果表明:a.不同品种的苎麻纤维支数有显著差异,高支数品种与低支数品种间相差可达1500支以上;b.苎麻不同生长期与纤维支数关系很大,最早一期收获与最迟一期收获二者纤维支数相差达1～1.5倍;c.苎麻解剖结构,过氧化物酶同工酶关系密切,单纤维细度和强力受纤维细胞直径和壁厚的共同作用表现为纤维细胞壁截面积大小的制约,优质高产苎麻品种的茎截面解剖特点是单个纤维细胞壁截面积较小,而茎内纤维细胞数目较多,类型I的苎麻品种C区酶带活性强,纤维支数高;d.不同海拔高度与苎麻单纤维支数成正相关,单纤维支数随着栽植密度而增加;e.土壤缓效钾与纤维支数,土壤速效钾与产量均呈显著正相关,纤维支数随着施氮量增加而降低,硼肥和螯合稀土能提高纤维支数;f.种子繁殖显著降低产量和纤维支数;g.提高苎麻纤维支数的措施是,采用无性繁殖、严禁种子繁殖,实行良种区域化,一地一种,以及经济施肥和配方施肥。     

抗虫杂交棉纤维性状与产量性状关系的研究

以中棉29号、湘杂棉3号杂交棉为试验材料,采用关联度分析、偏相关分析、主成分分析、通径分析等方法探讨棉纤维性状与产量性状的关系.结果表明:纤维性状、产量性状之间存在一系列相关关系和关联关系;在品质育种中选择纤维长度同时注重低马克隆值、高比强度材料定向选择与培育,可获得优质棉组合;在产量育种中注重株结铃数、铃重、衣分等性状选择与培育,可获得高产棉组合.     

Spatial variation of fiber quality and associated loan rate in a dryland cotton field

A field study was conducted in 2006 in a dryland cotton field in Texas, USA, to explore the spatial variation of cotton fiber quality and the loan rate associated with it. A total of 66 cotton samples were hand-harvested, and the fiber quality properties investigated included the High Volume Instrument measurements of micronaire, length, uniformity, strength, elongation, reflectance (Rd) and yellowness (+b). Conventional statistics showed a generally low level of variation in fiber quality with coefficients of variation <10%. Variogram analysis showed that all fiber quality properties were spatially correlated. Contour maps of individual fiber quality properties were produced from block kriged estimates. Fiber length, uniformity, strength and Rd were positively correlated, and all of these were negatively correlated with +b. The spatial distribution of most fiber quality properties was similar to that of soil apparent electrical conductivity, suggesting that water holding capacity could be a limiting factor for cotton fiber quality. Maps of individual fiber quality properties were combined with the United State Department of Agriculture—Commodity Credit Corporation Loan Schedule for Upland Cotton to create a loan rate map that is associated with fiber quality. A loan rate difference of 20 cents kg^–1 was observed within the field. This level of difference indicated that fiber quality at the field level can have a large impact on producers’ revenue. A site-specific management system encompassing both lint yields and fiber quality is strongly recommended for cotton production.     

棉花纤维突变体胚珠发育过程中主要生化物质的积累特征

采用4种不同类型的棉花纤维突变体和一个正常对照TM-1,分析比较了胚珠发育过程中,纤维和种皮内纤维素,种仁内脂肪、可溶性糖和蛋白质等成份的积累特征及诸成份与纤维素含量的相关关系.结果表明,棉花纤维突变体的胚珠不仅生化物质动态变化有着较大的差异,而且其生化物质的组成差异也很大.纤维突变体的纤维素含量低,种仁蛋白质含量低,脂肪含量高.纤维素含量与种仁内脂肪含量呈显著或极显著正相关;与纤维可溶性糖,纤维蛋白质有显著的相关性,呈显著负相关.     

短切碳纤维木质复合材料导电性能数值分析

采用施胶木材纤维作为主体材料,加入短切碳纤维制成具有导电性能的短切碳纤维木质复合材料(SCFRW),通过表面电阻率测量实验,得到SCFRW表面电阻率离散数据.数据分析结果显示,碳纤维的加入赋予了复合材料良好的导电特性,且表面电阻率与温度呈现出负效应关系.为了更直观描述SCFRW样板表面电阻率在17～80℃连续的变化规律...     

Synaptic transmission at single glomeruli in the turtle cerebellum

We have recorded from the granular layer of the turtle cerebellum extracellular unitary potentials that appear to reflect pre- and postsynaptic events at the synapse between a single swelling of a mossy fiber and the dendritic tips of several granule cells. The presynaptic component is an all-or-none potential. It can be directly activated by spinal stimulation and is unaltered by repetitive activity or by high concentrations of magnesium. The postsynaptic component is a graded potential. It follows the presynaptic component by approximately 1 millisecond and is depressed by repetitive activity and by high concentrations of magnesium. The recording of large potentials produced by the flow of postsynaptic current within a single glomerulus suggests powerful transmission. Electron micrographs demonstrate large cerebellar glomeruli in the turtle and a substantial accumulation of mitochondria in the dendritic tips of granule cells.     

大豆理化特性与挤压组织化产品特性的关系

 【目的】研究不同大豆品种籽粒理化特性、脱脂大豆粉理化特性与挤压组织化产品特性的关系,探讨用于评价加工挤压组织化大豆产品品种的特性指标。【方法】以东北三省18个大豆品种为原料,以德国Bradender DSE-25型同向啮合双螺杆挤压机为挤压组织化设备,分析不同大豆品种籽粒理化指标、脱脂粉理化指标与挤压组织化加工工艺系统参数、产品特性的相关关系。【结果】大豆籽粒、脱脂粉粗蛋白含量与挤压组织化单位机械能耗、表观黏度呈显著正相关（α=0.05）。籽粒粗蛋白、水溶性蛋白及脱脂粉粗蛋白含量与产品的拉伸强度、抗剪切力呈显著正相关（α=0.05）。脱脂粉粗纤维含量与产品的横切力、组织化度、弹性呈显著负相关（α=0.05）。脱脂粉灰分含量与单位机械能耗、表观黏度呈显著负相关,与产品聚结性呈负相关（α=0.05）。【结论】选择粗蛋白含量高、水溶性蛋白含量高、粗纤维含量较低的原料或大豆品种,可以生产出组织化度较好、弹性、拉伸强度较大的挤压组织化产品。选育适用于挤压组织化加工的大豆品种时,应重点考虑提高粗蛋白含量、水溶性蛋白含量,同时降低粗纤维含量。     

气象因子对湖南省棉花纤维品质的影响

采用灰色系统和逐步回归法探讨了温度、光照时数、空气湿度、降水量等主要气象因子与中棉29号和湘杂棉3号的纤维品质性状的量化关系.结果表明,在湖南气候条件与栽培技术体系下,以伏桃的纤维品质最优,其贡献率达到66.67%,但以麦克隆值的变异系数最大(湘杂棉3号为9.794%,中棉29号为9.295%),平均为9.545%;灰色系统分析表明,温度是影响纤维品质的主导因子;逐步回归法分析表明,温度、光照时数与纤维品质呈正相关,而与降水量、空气湿度呈负相关,并建立了棉纤维品质与气象因子的线性回归模型:Y=-0.838 15 0.015 25X1-0.043 72X2(中棉29);Y=-0.070 65 0.050 38X1-0.037 48X2 0.002 16X3-0.010 43X4(湘杂棉3号).     

早熟陆地棉品种与气候因子互作对棉纤维品质的影响

[目的]研究早熟陆地棉品种与气候因子互作对棉纤维品质的影响,为选择品质优良的早熟陆地棉品种提供理论依据和指导信息.[方法]采用EXCEL 2003和SPSS19.0软件,对参试品系3年的试验数据进行相关性和逐步回归分析,分析棉纤维品质性状与品种特性及气象因子间的相互关系,建立最优回归模型,研究关键影响因子.[结果]出苗...     

大麻纤维产量构成因素的相关分析初报

为促进黑龙江省纤维大麻产业的发展,选用大麻纤维产量(Y)与株高(X1)、茎粗(X2)、单位面积收获株数(X3)、干茎制成率(X4)、全麻率(X5)等因素建立数学模型,其相关方程为Y=12 595.10-1.997 X1-227.931 X2-1.158 X3-128.704 X4+94.927 X5;全麻产量与株高,茎粗呈负相关,与单位面积收获株数呈显著正相关,与干茎制成率呈正相关,与全麻率呈极显著正相关。     

西北内陆早熟陆地棉品种的综合评价及育种演化

【目的】综合评价近30年西北内陆棉区审定的早熟陆地棉品种,阐述该区域育成品种主要性状的育种演变规律,为西北内陆棉花新品种选育和主栽品种推荐提供参考依据。【方法】2020年和2021年分别在甘肃敦煌和新疆石河子对110个1988—2021年西北内陆棉区审定的早熟陆地棉品种与早熟、产量、纤维品质和株型相关的12个主要性状的表型进行鉴定;利用聚类分析、相关性分析和主成分分析等方法,对品种表型特征进行综合评分,筛选优良品种,并对其主要性状进行育种演化分析。【结果】110个早熟陆地棉参试品种的12个主要性状表型值分布范围较大,变异系数由大到小依次为：果枝长度>单株结铃数>吐絮率>单铃重>马克隆值>纤维强度>衣分>纤维长度>开花时间>果枝夹角>伸长率>整齐度。通过聚类分析将110个早熟陆地棉品种分为Ⅰ、Ⅱ、Ⅲ和Ⅳ4个类群,它们分别为优良纤维品质、早熟、松散株型和高产的品种类群。相关性分析表明,早熟性与产量和纤维品质相关性状均呈负相关,产量构成性状与纤维品质性状呈正相关,且多数性状之间达显著或极显著水平。利用主成分分析将12个主要性状...     

2个彩色棉材料的农艺性状和纤维发育特点研究

以常规白色棉 3 3B为对照 ,于 2 0 0 0～ 2 0 0 1年在山东棉花研究中心试验站 (临清 )对大田种植的 2个彩色棉绿色棉和棕色棉材料的农艺性状与纤维发育特点进行了研究。结果显示 ,2个彩色棉材料的营养生长旺盛 ,具有早发早熟的特点 ,但铃重小 ,衣分低 ,皮棉单产仅为对照 3 3B的 5 0 %～ 60 %。彩色棉的纤维品质比对照品种差 ,其中绿色棉的纤维品质最差 ,基本无纺织利用价值。彩色棉的纤维发育过程与对照相比有很多不同之处 ,表现在 2个彩色棉材料的棉纤维在开花后 3 0～ 40天出现颜色 ,纤维伸长期短 ,伸长速率低 ,次生壁加厚慢 ,纤维伸长与次生壁加厚重叠的时间短 ,这可能是彩色棉纤维品质差的主要原因。