非结构性碳水化合物与水稻颖花形成关系的研究进展

为了深入研究水稻幼穗分化发育及颖花形成过程中非结构性碳水化合物(NSC)作用机理,本文综合分析了水稻颖花形成的特点,总结了幼穗分化发育与同化物代谢的关系和幼穗发育与非结构性碳水化合物的关系,并探讨糖信号与激素信号的相互关系及其对幼穗发育的调节作用及机理。认为大穗型水稻二次颖花易退化、穗粒数不稳定与NSC关系密切,可溶性糖与植物激素调节及其相互作用对幼穗的分化发育有重要调控作用,提出通过深入研究NSC代谢特征及穗分化发育阶段各可溶性糖组分的积累与分解规律,以及幼穗分化发育过程中内源激素水平、蛋白表达及代谢关键酶活性,探寻NSC糖信号-激素及激素间的平衡-相关蛋白表达和代谢酶活性-颖花数形成之间的内在联系,以期通过调节NSC代谢,构建促进颖花分化、减少退化为目标的栽培调控技术。     

哺乳动物毛囊发生发育调控机制研究进展

胚胎期毛囊的发生发育是决定毛囊数量、毛被类型和毛品质的关键阶段,挖掘该阶段的重要基因是育种工作者的重要内容之一。近年来,关于毛囊发生发育相关重要基因的鉴定方面有一定的研究进展,但由于毛囊结构复杂、细胞组成多样且细胞分化快等问题致使研究人员在完整毛囊细胞系的建立、主效基因的挖掘和基因功能的确定等方面进展缓慢。因此,了解毛囊的基本结构、发育过程以及在该过程中发挥重要作用的信号途径/基因,是解决以上问题关键所在。本文对哺乳动物毛囊形态结构及其在胚胎期发生发育过程（以小鼠为例）进行了系统的介绍,归纳总结了与毛囊发生发育相关的关键信号通路以及目前已发现的重要遗传因子。结果表明：1）胚胎期真皮成纤维细胞、上皮细胞可进一步分化为各类毛囊细胞,因此适时诱导/阻滞其分化是成功构建细胞群的关键。2）在毛囊发生发育调控过程中,同一信号通路中不同信号途径存在不同程度的偏向,如Wnt信号通路偏向于Wnt/β-catenin信号途径、Edar信号通路偏向于Eda-A1/Edar/Edaradd信号途径,而TGF-β/BMP信号通路则偏向于Smads依赖性信号途径。3）毛囊发生发育过程中涉及多条信号通路和多个遗传因子共同调控,其中Wnt、Edar信号是毛囊基板正常形成过程中不可或缺的信号通路,而TGF-β信号通路是毛囊各类细胞分化和毛囊向下生长过程关键信号通路之一。综上,对哺乳动物毛囊发生发育过程和机制有清晰地认识和理解,是进一步挖掘与毛囊发育相关重要基因的重要基础,其可为提高毛用型经济动物的生产性能提供重要理论依据。     

斑马鱼胰腺发育的研究进展

准确理解发育过程中的分子事件从而调控胰腺发育,对临床医学相关的糖尿病、肥胖、胰腺癌和疾病有着重要影响。1996年以前,胰腺发育和分化研究的主要动物模型是老鼠和与早期发育相关的鸡和爪蟾。斑马鱼作为一个新的研究模型,通过参与功能基因组学、遗传学和体内全胚胎观察,斑马鱼已经大范围应用和基因功能的多维度定义在胰腺的形成和分化过程中。主要介绍了模式动物斑马鱼早期胰腺发育和形态建成。     

植物维管组织形态建成的分子调控机制

在植物个体发育过程中,维管组织形态建成受多种外源及內源因子的共同影响。研究表明:植物激素、CLE 短肽信号分子、多种转录因子、热精胺、NO 等均在维管组织形态建成中发挥重要调控作用。AUX、CTK、ET、BRs、 GA 等共同参与调节原形成层与形成层细胞的增殖和分化;CLE 短肽信号分子可促进(原)形成层细胞增殖并抑制 木质部分化;HD-ZIP Ⅲ基因家族,KAN、NAC、MYB 转录因子及木质形成素与木质部、韧皮部的布局排列及发育相 关;热精胺与NO 影响着木质部细胞的分化。多种调节因子相互关联构建形成复杂的调控网络,作用于植物维管组 织的形态建成过程。      

miRNA在动物毛囊发育中的研究进展

microRNA (miRNA)是一类长度约20～25个核苷酸的内源性非编码小分子RNA,通过作用于靶基因mRNA的非翻译区抑制其翻译进而参与基因转录后调控,从而影响生物发育和疾病发生过程等。miRNA通过调节Wnt信号通路、BMP信号通路和细胞因子等表达参与动物毛囊的周期性生长发育、毛囊干细胞的增殖分化和凋亡以及被毛颜色的形成等。本研究从miRNA生物合成、miRNA对毛囊发育作用和对动物毛囊发育调控机制等方面进行详细阐述,旨在为深入了解miRNA调控动物毛囊的发育机制,并为今后指导毛用和皮用动物选育和提高生产性能提供参考。     

南瓜花芽分化解剖结构的研究

以美洲南瓜(Cucurbita pepoL.)品种金辉二号为试材,采用石蜡切片法对其花芽分化过程进行形态学观察.结果表明,雌、雄花的分化和成熟的顺序都是由外而内,雄花可分为花芽未分化期、花芽分化初期、花萼原基分化期、花冠原基分化期、雄蕊分化期.在雄蕊发育过程中形成两大一小的3个雄蕊,没有观察到雌蕊的发育;雌花的发育过程...     

稻瘟病菌附着胞发育相关信号传递研究进展

附着胞的分化、形成和成熟是稻瘟病菌成功侵入寄主的前提.稻瘟病菌识别不同的胞外信号,可通过环化腺苷酸(cAMP)信号途径、丝分裂原激活蛋白激酶(Mitogen-activated protein kinase,MAPK)信号转导途径和Ca2+信号途径等不同的信号途径来调控附着胞发育.结合这些信号传递途径相关基因及其信号途径间关系的研究论述了调控稻瘟病菌附着胞分化和发育的信号传递的分子机理.     

牛和小鼠早期胚胎发育过程中细胞谱系发育调控的比较

高产奶牛繁殖效率低是世界性难题，其中早期胚胎死亡率高是主要原因之一。当前对牛早期胚胎发育的研究有限，而对于小鼠这种模式动物的早期胚胎发育研究已相当深入。因此，本文从胚胎形态、转录因子以及信号通路3方面对牛和小鼠早期胚胎发育过程进行比较，以加深对牛早期胚胎发育的认识。经比较发现，受精后，牛和小鼠早期胚胎在不同时期发生母源因子降解、合子基因组激活、细胞极性建立和不对称分裂，最终使得胚胎形态发生变化，形成具有3个胚层（滋养外胚层、上胚层和原始内胚层）的囊胚。此外，牛和小鼠早期胚胎发育过程中，多个转录因子及信号通路形成复杂网络调控细胞谱系分化。综上所述，在牛和小鼠早期胚胎发育过程中，相似的生物学事件陆续发生，但是细胞谱系分化的调控呈现差异性，提示我们将小鼠早期胚胎作为研究模型的局限性，该领域的研究对提高奶牛繁殖效率以及促进牛遗传改良工作具有重要意义。     

小麦高产品种幼穗分化发育特性的研究

对关中，黄淮麦区大面积种的几个高产小麦品种和具有高产性状几个品系的穗分化发育特性的研究表明，在幼穗分化过程中，提高单棱分化速率，增加单棱分化数目，延长二棱分化时期，是形成大穗（多小穗）的发育基础，促进分蘖穗与主茎穗在小花原基分化期达到同步分化，是形成穗匀发育基础，也可做为育种实践的相关选择指标。     

白杜花序和花的形态发生

利用石蜡切片及电镜扫描技术,对白杜(Euonymus maackii)花序及花的发生过程进行观察。白杜花序为二歧聚伞花序,从花芽分化到雌蕊形成,整个过程可分为花序原基分化期、苞片分化期、小花原基分化期、花萼分化期、花瓣分化期、雄蕊分化期、雌蕊分化期7个时期。白杜花序可能通过败育达到结构上的简化;大量小花的雄蕊发育异常是影响白杜结实率和观赏性的重要原因之一。     

Semaphorin 3E and plexin-D1 control vascular pattern independently of neuropilins

The development of a patterned vasculature is essential for normal organogenesis. We found that signaling by semaphorin 3E (Sema3E) and its receptor plexin-D1 controls endothelial cell positioning and the patterning of the developing vasculature in the mouse. Sema3E is highly expressed in developing somites, where it acts as a repulsive cue for plexin-D1-expressing endothelial cells of adjacent intersomitic vessels. Sema3E-plexin-D1 signaling did not require neuropilins, which were previously presumed to be obligate Sema3 coreceptors. Moreover, genetic ablation of Sema3E or plexin-D1 but not neuropilin-mediated Sema3 signaling disrupted vascular patterning. These findings reveal an unexpected semaphorin signaling pathway and define a mechanism for controlling vascular patterning.     

Regulation of blood and lymphatic vascular separation by signaling proteins SLP-76 and Syk

Lymphatic vessels develop from specialized endothelial cells in preexisting blood vessels, but the molecular signals that regulate this separation are unknown. Here we identify a failure to separate emerging lymphatic vessels from blood vessels in mice lacking the hematopoietic signaling protein SLP-76 or Syk. Blood-lymphatic connections lead to embryonic hemorrhage and arteriovenous shunting. Expression of slp-76 could not be detected in endothelial cells, and blood-filled lymphatics also arose in wild-type mice reconstituted with SLP-76-deficient bone marrow. These studies reveal a hematopoietic signaling pathway required for separation of the two major vascular networks in mammals.     

H2S as a physiologic vasorelaxant: hypertension in mice with deletion of cystathionine gamma-lyase

Studies of nitric oxide over the past two decades have highlighted the fundamental importance of gaseous signaling molecules in biology and medicine. The physiological role of other gases such as carbon monoxide and hydrogen sulfide (H2S) is now receiving increasing attention. Here we show that H2S is physiologically generated by cystathionine gamma-lyase (CSE) and that genetic deletion of this enzyme in mice markedly reduces H2S levels in the serum, heart, aorta, and other tissues. Mutant mice lacking CSE display pronounced hypertension and diminished endothelium-dependent vasorelaxation. CSE is physiologically activated by calcium-calmodulin, which is a mechanism for H2S formation in response to vascular activation. These findings provide direct evidence that H2S is a physiologic vasodilator and regulator of blood pressure.     

Myeloperoxidase,a leukocyte-derived vascular NO oxidase

Myeloperoxidase (MPO) is an abundant mammalian phagocyte hemoprotein thought to primarily mediate host defense reactions. Although its microbicidal functions are well established in vitro, humans deficient in MPO are not at unusual risk of infection. MPO was observed herein to modulate the vascular signaling and vasodilatory functions of nitric oxide (NO) during acute inflammation. After leukocyte degranulation, MPO localized in and around vascular endothelial cells in a rodent model of acute endotoxemia and impaired endothelium-dependent relaxant responses, to which MPO-deficient mice were resistant. Altered vascular responsiveness was due to catalytic consumption of NO by substrate radicals generated by MPO. Thus MPO can directly modulate vascular inflammatory responses by regulating NO bioavailability.     

LRP: role in vascular wall integrity and protection from atherosclerosis

Vascular smooth muscle cell (SMC) proliferation and migration are important events in the development of atherosclerosis. The low-density lipoprotein receptor-related protein (LRP1) mediates suppression of SMC migration induced by platelet-derived growth factor (PDGF). Here we show that LRP1 forms a complex with the PDGF receptor (PDGFR). Inactivation of LRP1 in vascular SMCs of mice causes PDGFR overexpression and abnormal activation of PDGFR signaling, resulting in disruption of the elastic layer, SMC proliferation, aneurysm formation, and marked susceptibility to cholesterol-induced atherosclerosis. The development of these abnormalities was reduced by treatment with Gleevec, an inhibitor of PDGF signaling. Thus, LRP1 has a pivotal role in protecting vascular wall integrity and preventing atherosclerosis by controlling PDGFR activation.     

Elementary Ca2+ signals through endothelial TRPV4 channels regulate vascular function

Major features of the transcellular signaling mechanism responsible for endothelium-dependent regulation of vascular smooth muscle tone are unresolved. We identified local calcium (Ca(2+)) signals ("sparklets") in the vascular endothelium of resistance arteries that represent Ca(2+) influx through single TRPV4 cation channels. Gating of individual TRPV4 channels within a four-channel cluster was cooperative, with activation of as few as three channels per cell causing maximal dilation through activation of endothelial cell intermediate (IK)- and small (SK)-conductance, Ca(2+)-sensitive potassium (K(+)) channels. Endothelial-dependent muscarinic receptor signaling also acted largely through TRPV4 sparklet-mediated stimulation of IK and SK channels to promote vasodilation. These results support the concept that Ca(2+) influx through single TRPV4 channels is leveraged by the amplifier effect of cooperative channel gating and the high Ca(2+) sensitivity of IK and SK channels to cause vasodilation.     

Cytokinin signaling and its inhibitor AHP6 regulate cell fate during vascular development

The cell lineages that form the transporting tissues (xylem and phloem) and the intervening pluripotent procambial tissue originate from stem cells near the root tip. We demonstrate that in Arabidopsis, cytokinin phytohormones negatively regulate protoxylem specification. AHP6, an inhibitory pseudophosphotransfer protein, counteracts cytokinin signaling, allowing protoxylem formation. Conversely, cytokinin signaling negatively regulates the spatial domain of AHP6 expression. Thus, by controlling the identity of cell lineages, the reciprocal interaction of cytokinin signaling and its spatially specific modulator regulates proliferation and differentiation of cell lineages during vascular development, demonstrating a previously unrecognized regulatory circuit underlying meristem organization.     

重瓣野迎春花部维管束系统的解剖学观察

运用石蜡制片技术对重瓣野迎春的花部维管束进行解剖学研究,以探索其花部维管束分布与延伸,明确野迎春的花部重瓣来源的解剖学证据。结果表明:野迎春的花梗维管束为外韧型,密集地分布于花梗中央;心皮背束2束,隔膜束1束;子房壁维管束中的外轮维管束和内轮维管束,向上延伸发展为萼片维管束和花瓣维管束;同时,隔膜束和心皮背束继续向内移动,并产生分支;隔膜束延伸成花瓣维管束和雄蕊维管束,心皮背束发展成为雄蕊维管束和花柱维管束。重瓣野迎春的两轮花瓣维管束的来源为隔膜束和子房壁,故其重瓣的演化类型属于重复起源。     

何首乌幼苗的解剖学及过渡区的初生维管系统

采用石蜡制片方法,对何首鸟幼苗进行了解剖学研究.结果表明:何首鸟幼苗类型为木兰型.根为四原型,通常无髓部.子叶和初生叶的上表皮无气孔器分布,表皮细胞垂周壁平直;下表皮的表皮细胞垂周壁波浪状,有较多的气孔器,气孔器属无规则型.子叶柄中有3个维管束,初生叶的叶柄中有6个维管柬.何首鸟幼苗的过渡区位于下胚轴,根的4个放射维管...