外源激素ABA影响新疆荒漠盐生植物异子蓬异型种子萌发机制

以新疆荒漠盐生植物异子蓬(Suaeda aralocaspica)异型种子为材料,通过外源ABA直播(长时间)与浸种(短时间)处理分别研究不同浓度(0、0.5、1.0、5.0、10.0μmol/L)ABA对异型种子萌发、幼苗生长的影响,并通过定量PCR技术分析与萌发相关的ABC转运蛋白基因、丝裂原活化蛋白激酶激酶基因和DNA修复和转录因子基因在5.0μmol/L ABA处理下的表达规律,探讨外源ABA影响异子蓬异型种子萌发差异的机制。结果显示:(1)外源ABA直播处理下,褐色种子萌发及幼苗生长均受到明显抑制,黑色种子的萌发和幼苗生长在低浓度被促进,较高浓度被显著抑制;短时间浸种处理,能够同时促进异型种子的萌发及幼苗生长,且随ABA浓度增加促进效应增强。(2)直播萌发后,褐色种子中3个基因的表达量与对照相比均不变或降低表达(除了DNA修复和转录因子基因在8 h显著升高),黑色种子与对照相比均上调表达(除了ABC转运蛋白基因在8h显著下调);短时间浸种萌发后,褐色种子中3个基因的表达量均比对照显著升高,黑色种子中升高不明显。基因表达规律与种子萌发结果趋势一致,暗示ABA浸种可能触发了异子蓬种子萌发内在机制并对随后的萌发过程产生促进作用。而黑色种子对ABA处理表现出较好的萌发响应,可能是其幼苗能抵御荒漠地区逆境环境的重要原因。     

陆地棉GhPYR1基因的克隆和功能分析

植物激素脱落酸(Abscisic acid,ABA)在植物应对干旱、盐碱等逆境胁迫以及植物种子萌发、根伸长、芽休眠等阶段发挥重要作用。PYR/PYL/RCAR蛋白家族是ABA受体,与ABA结合后能够启动ABA信号传导通路,诱导ABA应答基因的表达。利用电子克隆和RT-PCR技术从陆地棉中克隆了Gh PYR1基因,其编码的Gh PYR1蛋白与拟南芥中At PYR1蛋白相似度为73%。将Gh PYR1蛋白序列与拟南芥14个PYR/PYL/RCAR家族成员蛋白序列进行比对并构建进化树,发现它与拟南芥PYR/PYL/RCAR蛋白亚家族III亲缘关系最近。过表达Gh PYR1基因的T3代拟南芥在外源ABA处理下,其种子萌发和初期根生长均滞后于野生型,表现出对ABA更加敏感;高盐和干旱胁迫对转基因种子的萌发抑制更强烈,但苗期胁迫处理下转基因拟南芥的长势却明显优于野生型;同时在外源ABA诱导条件下ABA应答基因RD29A、RAB18的表达量较野生型有明显提高。以上结果说明Gh PYR1基因编码的蛋白是ABA的受体,过表达该基因能够提高植物对ABA的敏感性和增强应对逆境胁迫的能力。     

外源ABA对藜麦种子萌发及ABA相关基因表达的影响

穗发芽会导致藜麦籽粒产量和品质严重受损,而脱落酸(ABA)与种子萌发和休眠密切相关。该研究以易穗发芽的‘大黑藜3’(BBQ3)、‘白藜6’(WQ6)和抗穗发芽的‘小黑藜1’(SBQ1)和‘白藜4’(WQ4)为试验材料,在种子萌发3 d内施加不同浓度ABA和氟啶酮(FL),探究ABA和FL对两种粒色藜麦种子萌发、ABA含量以及ABA合成基因NCED、裂解基因8′OH和信号转导基因ABI3表达的影响。结果表明：(1)各藜麦种子萌发均受到各浓度外源ABA抑制,并以25μmol·L^-1浓度效果最佳,同时受到外源低浓度FL促进,且施用2.5μmol·L^-1浓度即可;外源ABA和FL处理的SBQ1和WQ4发芽率降低和升高幅度分别小于BBQ3和WQ6。(2)对照组SBQ1和WQ4种子内源ABA含量分别显著高于BBQ3和WQ6;外源ABA处理可显著提高藜麦种子内源ABA含量,且WQ4显著高于WQ6,种皮略厚的SBQ1内源ABA含量显著低于BBQ3;外源FL处理下4份材料种子内源ABA含量均有所下降,但只有SBQ1达到显著水平。(3)对照组中,SBQ1和WQ4...     

GA3、ABA对未成熟‘博Ⅱ优15’水稻种子萌发的影响

以未成熟水稻'博II优15'种子为材料,用不同浓度GA3、ABA浸种24 h,研究其对水稻种子萌发的影响.结果表明,GA3 0.10～2.00 g/L处理能极显著促进种子萌发,其中0.50 g/L效果最好,第4天发芽率高于对照(CK)56%;浓度大于0.50 g/L ABA处理显著抑制种子萌发;GA3与ABA协同处理时, GA3/ABA = 1:1(浓度0.05 g/L)和 GA3/ABA = 1:2(浓度0.01 g/L)均能极显著促进种子萌发,第7天种子发芽率分别比CK高30%和20%.进一步研究表明,GA3和ABA对未成熟水稻种子萌发的影响与α-淀粉酶活性相关.     

外源CO和NO对水稻种子萌发过程中干旱胁迫损伤的缓解效应

选用水稻品种‘Ⅱ优128’种子为材料,以1.0μmol.L-1高铁血红素(Hematin,H)和200μmol.L-1硝普钠(sodium nitroprusside,SNP)分别作为CO和NO供体,采用PEG-6000模拟干旱胁迫,研究外源CO和NO对干旱胁迫下水稻种子萌发和萌发过程中抗氧化能力的影响。结果表明:高铁血红素和硝普钠处理可以显著提高干旱胁迫下水稻种子的发芽率、芽长和根长;同时显著提高种子淀粉酶活性,显著增加其可溶性糖、可溶性蛋白和脯氨酸含量;还不同程度地诱导增强超氧化物歧化酶(SOD)、过氧化氢酶(CAT)和过氧化物酶(POD)的活性,同时降低质膜相对透性和丙二醛(MDA)含量。研究证实,外源CO和NO可通过调节渗透调节物质含量和保护酶活性来有效缓解干旱胁迫对萌发水稻种子造成的氧化伤害,促进种子萌发生长。     

干旱胁迫下表观遗传机制对转C4型PEPC基因水稻种子萌发的影响

为探究干旱胁迫下表观遗传机制对高表达玉米(Zea mays) C₄型PEPC转基因水稻(Oryza sativa)种子萌发的影响, 以转C₄型PEPC水稻(PC)和野生型水稻Kitaake (WT)为试材, 采用10% (m/v)聚乙二醇6000 (PEG6000)模拟干旱条件, 通过单独和联合施用PEG6000、DNA甲基化抑制剂5-氮杂胞苷(5azaC)和可变剪接抑制剂大环内酯类(PB)进行种子发芽实验, 测定种子活力、萌发过程中可溶性糖和可溶性蛋白含量、α-淀粉酶活性以及PEPC、糖信号相关基因和部分剪接因子基因的表达。结果表明, 0.25 µmol·L^-1PB处理对2种供试水稻在干旱条件下种子萌发均表现出显著抑制作用, 使干旱条件下种子萌发过程中可溶性总糖、蔗糖、葡萄糖和果糖含量以及可溶性蛋白含量均有所下降, PB也抑制糖信号-蔗糖非发酵1 (SNF1)相关蛋白激酶(SnRKs)家族和剪接因子丝氨酸/精氨酸富集蛋白家族(SR proteins)相关基因的表达以及α-淀粉酶的活性, 但对PC的抑制作用小于WT。5 µmol·L^-15azaC处理对干旱条件下种子萌发的效果与可变剪接抑制剂相反。5 µmol·L ^-1 5azaC联合PEG6000干旱处理部分减缓了干旱对水稻种子发芽率的抑制作用, 使供试材料发芽率升高, 表明DNA甲基化和可变剪接机制参与了水稻芽期干旱耐性, 其中对PC的作用更大。     

Effects of Epigenetic Mechanisms on C4 Phosphoenolpyruvate Carboxylase Transgenic Rice (Oryza sativa) Seed Germination Under Drought Stress

为探究干旱胁迫下表观遗传机制对高表达玉米(Zea mays) C₄型PEPC转基因水稻(Oryza sativa)种子萌发的影响, 以转C₄型PEPC水稻(PC)和野生型水稻Kitaake (WT)为试材, 采用10% (m/v)聚乙二醇6000 (PEG6000)模拟干旱条件, 通过单独和联合施用PEG6000、DNA甲基化抑制剂5-氮杂胞苷(5azaC)和可变剪接抑制剂大环内酯类(PB)进行种子发芽实验, 测定种子活力、萌发过程中可溶性糖和可溶性蛋白含量、α-淀粉酶活性以及PEPC、糖信号相关基因和部分剪接因子基因的表达。结果表明, 0.25 μmol·L^-1PB处理对2种供试水稻在干旱条件下种子萌发均表现出显著抑制作用, 使干旱条件下种子萌发过程中可溶性总糖、蔗糖、葡萄糖和果糖含量以及可溶性蛋白含量均有所下降, PB也抑制糖信号-蔗糖非发酵1 (SNF1)相关蛋白激酶(SnRKs)家族和剪接因子丝氨酸/精氨酸富集蛋白家族(SR proteins)相关基因的表达以及α-淀粉酶的活性, 但对PC的抑制作用小于WT。5 μmol·L^-15azaC处理对干旱条件下种子萌发的效果与可变剪接抑制剂相反。5 μmol·L ^-1 5azaC联合PEG6000干旱处理部分减缓了干旱对水稻种子发芽率的抑制作用, 使供试材料发芽率升高, 表明DNA甲基化和可变剪接机制参与了水稻芽期干旱耐性, 其中对PC的作用更大。     

水稻OsPR10A的表达特征及其在干旱胁迫应答过程中的功能

利用免疫印迹(WB)分析了水稻(Oryza sativa) OsPR10A在其不同生长时期、不同组织部位及多种非生物逆境胁迫下的表达特征, 发现OsPR10A在干旱、盐胁迫以及茉莉酸甲酯(MeJA)和脱落酸(ABA)诱导下表达量明显升高, 表明该蛋白可能在干旱和盐胁迫应答过程中发挥作用。为证明这一推测, 我们构建了OsPR10A超表达载体, 经农杆菌介导转化水稻, 获得超表达OsPR10A的纯合株系。田间表型观察表明, 转基因株系株高变矮、穗长变短、结实率降低。用20% PEG6000在水稻种子萌发过程中进行干旱处理, 结果显示, OsPR10A超表达株系的根长和芽长均显著高于野生型, 证明超表达OsPR10A可增强水稻萌发期耐旱性。该研究有助于增进人们对水稻OsPR10A功能的了解。     

光和GA_3诱导番茄种子萌发过程中内源ABA的变化

外源GA_3和红光都能有效地诱导台湾红番茄种子萌发;外源ABA对光诱导萌发有明显的抑制作用。白光和红光诱导萌发过程中内源ABA水平急剧降低,而在黑暗或远红光下则一直保持在与风干种子中原有的高水平。1 mol/L HCl酸化1h后加100 ppm GA_3诱导萌发时内源ABA含量也随培养时间的延续而明显下降。     

水稻OsPR10A的表达特征及其在干旱胁迫应答过程中的功能

利用免疫印迹(WB)分析了水稻(Oryza sativa) OsPR10A在其不同生长时期、不同组织部位及多种非生物逆境胁迫下的表达特征, 发现OsPR10A在干旱、盐胁迫以及茉莉酸甲酯(MeJA)和脱落酸(ABA)诱导下表达量明显升高, 表明该蛋白可能在干旱和盐胁迫应答过程中发挥作用。为证明这一推测, 我们构建了OsPR10A超表达载体, 经农杆菌介导转化水稻, 获得超表达OsPR10A的纯合株系。田间表型观察表明, 转基因株系株高变矮、穗长变短、结实率降低。用20% PEG6000在水稻种子萌发过程中进行干旱处理, 结果显示, OsPR10A超表达株系的根长和芽长均显著高于野生型, 证明超表达OsPR10A可增强水稻萌发期耐旱性。该研究有助于增进人们对水稻OsPR10A功能的了解。     

Characteristics of the membranes of the pellicle of the ciliatePseudomicrothorax dubius

Summary The membranes of the pellicle of the ciliatePseudomicrothorax dubius are investigated using thin section electron microscopy and freeze-fracture replicas. The plasma membrane is covered by a surface coat and is connected to the outer alveolar membrane by short, sometimes branched, bridges. The inner alveolar membrane is coated on both sides. The epiplasm lies in intimate contact with the cytoplasmic surface of this membrane, and there is a corresponding deposit on the other surface. This deposit is regularly striated.The epiplasmic layer and the alveoli are interrupted at sites of cytotic activity,e.g., the attachment sites of trichocysts, the cytoproct, and the parasomal sacs. The striated deposit ends where the epiplasm ends, indicating a direct relationship between these two epimembranous layers.There is a deposit along the sides of the first part of the tip of the trichocysts, and in this region the trichocyst membrane is free of intramembranous particles.The membrane of the parasomal sacs has a coat on both surfaces. That on the extraplasmic surface is similar to the surface coat of the plasma membrane. The origin of the cytoplasmic coat is unknown. The cytotic activity of these sacs is indicated by their highly irregular profiles.     

The early development of the tail and the transformation of the shape of the nucleus of the spermatid of the domestic fowl,Gallus gallus

Summary The differentiation of the spermatid, especially in reference to the formation of the flagellum, and transformation of the shape of the nucleus was investigated in the domestic fowl.In the early stage of the spermatid, a prominent Golgi apparatus appears around the centrioles. The Golgi vesicles then surround the axial-filament complex which develops from the distal centriole. These vesicles fuse to form continuous membrane at the earliest stage of flagellar formation, and in the succeeding stage Golgi lamellae are attached to the plasma membrane of the developing flagellum. From these observations, it is assumed that Golgi apparatus may be a source of the membrane system of the flagellum.The microtubules distributed around the nucleus form the circular manchette. The anterior region of the nucleus with the manchette is cylindrical in shape and the posterior region without it remains irregular in shape. When the circular manchette has been completed, the whole nucleus acquires a slender cylindrical shape. The circular manchette then changes into the longitudinal manchette. The nuclei of spermatids without a longitudinal manchette are abnormal in shape. In view of these observations it is assumed that the nuclear shaping of the spermatid may be accomplished by circular manchette and the maintenance of shape of the elongated nucleus by longitudinal manchette.The authors wish to thank Mr. Takayuki Mori for his helpful suggestions and technical advices     

Observations on the permeability of the choriocapillaris of the eye

Summary The choriocapillaris is a fenestrated capillary bed located posterior to the retinal pigment epithelium. It serves as the main source of supply to the photoreceptors, retinal pigment epithelium, and other cells of the outer retina. The permeability of these capillaries to intravenously injected ferritin (MW — approx. 480,000; mol. diam. 11 nm) was examined in the mouse, rabbit, and guinea pig, each of which is characterized by a different type of retinal vascularization. In all three species, the bulk of the ferritin remained in the capillary lumina, where it appeared to be blocked at the level of the diaphragmed fenestrae. Some ferritin was present in endothelial cell vacuoles. The results confirm previous work on the rat choriocapillaris and indicate that the barrier function of the choriocapillary endothelium is present even among species in which the retinal circulation differs significantly.Supported by NIH grant EY03418     

Separation of the pineal vesicle from the wall of the third ventricle during the post-hatching development of the chicken

Summary According to light- and electron-microscopic observations the pineal organ of the 3-day-old chicken consists of a prominent end vesicle and a tapering parenchymal stalk. During this stage the pineal lumen is in open communication with the third ventricle. However, in the 40-day-old chicken, which still possesses a well-developed end vesicle, the proximal portion of the pineal stalk displays regressive changes leading to local fragmentation. At this stage the pineal stalk is reduced, and the pineal lumen is missing. In 1-year-old chickens the parenchyma of the proximal portion of the stalk is further diminished, and in 3-year-old domestic fowl is completely displaced by bundles of collagenous fibers, only some nerve fibers being present. This post-hatching pineal development may reflect the sequence of changes leading from pineal sense organs to pineal glands.This work was supported by a grant-in-aid for Scientific Research from the Ministry of Education, Science and Culture of Japan