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51.
52.
弱光胁迫对不同基因型玉米生长发育和产量的影响 总被引:54,自引:5,他引:54
以不同基因型玉米为材料,在玉米生长发育的3个主要阶段(苗期、穗期、粒期)进行分期遮光试验,研究不同时期弱光胁迫对不同基因型玉米生长发育和产量的影响。结果表明,遮光延缓了玉米叶片的出生速度,使叶片变薄;遮光可以延缓叶片的衰老,但遮光解除后则加速叶片的衰老;遮光造成植株高度增加,但恢复正常光照后,其株高却逐渐低于对照;遮光使干物质积累下降,抽雄吐丝日期推迟,尤其是吐丝日期推迟更多,并使产量降低,但不同基因型玉米不同遮光处理下降程度不同。试验的4个品种中,掖单2 2和豫玉2号受遮光影响较小,而掖单36 38和丹玉13受影响较大,即不同基因型玉米对弱光胁迫的敏感性不同 相似文献
53.
P-Selectin-mediated acute inflammation can be blocked by chemically modified heparin, RO-heparin 总被引:5,自引:0,他引:5
Selectins are carbohydrate-binding cell adhesion molecules that play a major role in the initiation of inflammatory responses. Heparin can bind to P-selectin, and its anti-inflammatory property is mainly due to inhibition of P-selectin. However, the strong anticoagulant activity of heparin limits its clinical use. We prepared periodate-oxidized, borohydride-reduced heparin (RO-heparin) by chemical modification and tested its anticoagulant and anti-inflammatory activities. Activated partial thromboplastin time (aPTT) assays showed that, compared with heparin, RO-heparin had greatly reduced anticoagulant activity. Intravenous administration of this compound led to reduction in the peritoneal infiltration of neutrophils in a mouse acute inflammation model. In vitro cell adhesion experiments demonstrated that the effect of RO-heparin on inflammatory responses was mainly due to inhibiting the interaction of P-selectin with its ligands. These results indicate that RO-heparin may be a safer treatment for inflammation than heparin, especially when selectin is targeted. 相似文献
54.
现代农业中化学农药在提高作物产量中发挥着重要的作用,但是我国普遍存在过量用药现象,导致环境污染和危害食品安全.基于2012年的全国性农户问卷调查,本研究分析了2011年我国水稻、小麦和玉米使用农药现状,并估算了它们的温室气体排放.结果表明: 这3种作物至少使用了54种杀虫剂、24种杀菌剂和50种除草剂,其中32%的水稻种植农户使用了生物农药.全国3种作物使用了30.8 kt杀虫剂、16.5 kt杀菌剂和58.3 kt除草剂,它们的温室气体排放总量为1.5 Tg Ce,杀虫剂、杀菌剂和除草剂的排放分别占23.8%、16.9%和59.3%.南方区的农药用量占全国用量的51%;全国水稻、小麦和玉米的单位产量农药用量分别是0.22、0.18和0.24 g·kg-1粮食,3种作物用药总量分别为44.4、21.4和39.7 kt,温室气体排放分别为665.5、250.1和547.5 Gg Ce;在不同农药种类中,有机磷类杀虫剂占我国所用杀虫剂总量的69%,苯丙咪唑类、有机磷类、唑类和有机硫类等杀菌剂占杀菌剂总量的87%,酰胺类、有机杂环类和有机磷类等除草剂占除草剂总量的85%.因此,减少农药用量,对于我国粮食安全和环境安全及减少农业温室气体排放都具有重要意义. 相似文献
55.
采用随机区组试验设计,对引进的8个冷季型牧草品种进行产草量和营养成分的比较分析.结果表明:4次刈割的总鲜重和总干重在品种间差异极显著,且以蓝天堂黑麦草(7号)最高.品种间的粗蛋白含量差异显著,其中第1次刈割以奇可利(3号)最高,蓝天堂黑麦草(7号)居第2位;第2次仍以奇可利(3号)最高,特高黑麦草(1号)和蓝天堂黑麦草(7号)居其次;第3次以紫花苜蓿(8号)最高,其次是多年生黑麦草(4号);第4次以奇可利(3号)最高,多年生黑麦草(4号)居第2位;粗纤维、粗脂肪和粗灰分在品种间的差别较小.综合产草量和品质两方面考虑,蓝天堂黑麦草(7号)可作为本地首选推广的冷季型牧草品种,奇可利(3号)和多年生黑麦草(4号)可作为备选推广的牧草品种. 相似文献
56.
Acetylcholine is an important neurotransmitter, and the habenulo-interpeduncular projection is a major cholinergic pathway in the brain. To study the physiological properties of cholinergic transmission in the interpeduncular nucleus (IPN), we used a transgenic mouse line in which the light-gated cation channel ChannelRhodopsin-2 is selectively expressed in cholinergic neurons. Cholinergic axonal terminals were activated by light pulses, and postsynaptic responses were recorded from IPN neurons. Surprisingly, brief photostimulation produces fast excitatory postsynaptic currents that are mediated by ionotropic glutamate receptors, suggesting wired transmission of glutamate. By contrast, tetanic photostimulation generates slow inward currents that are largely mediated by nicotinic acetylcholine receptors, suggesting volume transmission of acetylcholine. Finally, vesicular transporters for glutamate and acetylcholine are coexpressed on the same axonal terminals in the IPN. These results strongly suggest that adult brain "cholinergic" neurons can corelease glutamate and acetylcholine, but these two neurotransmitters activate postsynaptic neurons via different transmission modes. 相似文献
57.
58.
Jing Jin Fei Yuan Min-qian Shen Yi-fan Feng Qi-liu He 《Molecular and cellular biochemistry》2013,381(1-2):267-272
Vascular endothelial growth factor (VEGF) is a hypoxia-induced angiogenic protein that exhibits a broad range of biological and pathological effects in wet age-related macular degeneration and proliferative diabetic retinopathy. However, its specific mechanism is still not fully understood. Here, we examined the effects of VEGF on choroid-retinal endothelial cells (RF/6A) proliferation and tube formation, and the underlying signal pathways responsible in this process. RF/6A cells were pretreated with MEK inhibitor or PI3K inhibitor, and then incubated in a hypoxia chamber. Real-time PCR and Western blot analysis were carried out to explore VEGF expression on mRNA and protein levels. Hypoxia inducible factor-1α (HIF-1α) and VEGFR2 expression levels were also investigated in the presence and absence of hypoxic conditions. CCK-8 analysis and tube formation assay were tested under hypoxia, exogenous recombinant VEGF, and different signal pathway inhibitors, respectively. Mean while, the PI3K/Akt and MEK/ERK pathways in this process were also investigated. Our results showed that VEGF, HIF-1α, VEGFR2, p-ERK, and p-Akt were up-regulated in RF/6A cells under hypoxic conditions. MEK inhibitor (PD98059) and PI3K inhibitor (LY294002) decreased ERK and Akt activity, respectively, and reduced VEGF expression. VEGF-induced RF/6A proliferation and tube formation requires MEK/ERK and PI3K/Akt signaling, and both of the two pathways were needed in regulating VEGF expression. These suggest that VEGF plays an important role in RF/6A proliferation and tube formation, and MEK/ERK and PI3K/Akt pathway may be responsible for this process. 相似文献
59.
目的:分析皮质酮快速抑制高钾诱导PC12细胞内钙升高的机制。方法:使用荧光影像系统,实时检测细胞内钙变化。结果:①在预处理PC12细胞5min后,皮质酮可呈量-效关系抑制高钾诱导的PC12细胞内钙升高。②牛血清白蛋白耦联的皮质酮(B-BSA)可模拟皮质酮快速抑制高钾诱导PC12细胞内钙升高的作用,并呈现量-效关系。③糖皮质激素的细胞内受体拮抗剂RU38486对皮质酮快速抑制效应无明显拮抗作用。④蛋白合成抑制剂放线菌酮预处理细胞3h后,皮质酮对高钾诱导PC12内钙升高仍有较强抑制作用。结论:①皮质酮的作用点位于细胞膜上。②皮质酮的快速作用不直接依赖细胞内蛋白合成和不依赖细胞内糖皮质激素受体。③皮质酮对高钾诱导PC12内钙升高的快速抑制作用属非基因组作用。 相似文献
60.
为验证视觉信息在松墨天牛Monochamus alternatus Hope成虫寄主选择中的作用,并探索其对寄主健康状况的偏好,本文通过林间对寄主云南松针叶的色彩比对,选取国际标准色卡对应卡色作为视觉信号源,对松墨天牛雌、雄成虫的视觉选择进行了研究。研究表明,松墨天牛雌虫选择最多的颜色分别是:棕红色(选择率26.67%),赭石棕(选择率20.00%),栗棕色(选择率16.67%);松墨天牛雄虫选择最多的颜色为:信号褐(选择率26.67%),棕红色(选择率23.33%),栗棕色(选择率20.00%)。雌、雄成虫均偏好选择棕褐色系,对应于林间衰弱和濒死寄主针叶呈现的颜色,说明松墨天牛成虫通过视觉判断偏好攻击长势衰弱的林木,属于次期性蛀干害虫。 相似文献