普通小麦–大赖草易位系T6DL·7LrS的分子细胞遗传学鉴定

大赖草高抗小麦赤霉病,将大赖草抗性基因导入普通小麦,对创新小麦赤霉病抗性种质有重要意义。为了获得普通小麦-大赖草抗赤霉病易位系,采用12 00 R~(60)Co-γ射线处理小麦-大赖草二体附加系DA7Lr花粉,授予已去雄的普通小麦中国春,对其后代(M1)种子根尖细胞有丝分裂中期染色体进行GISH分析,获得了1株具有1条普通小麦-大赖草易位染色体的植株,让其自交,对自交后代中具有2条易位染色体植株的花粉母细胞减数分裂中期I进行观察,发现2条易位染色体形成了稳定的棒状二价体,表明该植株为纯合体。利用顺序GISH-双色FISH分析,结合小麦D组专化探针Oligo-pAs1-2和B组专化探针Oligo-pSc119.2-2,进一步鉴定出该普通小麦-大赖草易位系为T6DL·7LrS,该易位系的育成也为小麦赤霉病遗传改良提供了新种质。     

利用杀配子染色体创造普通小麦-大赖草异易位系

某些山羊草染色体在普通小麦遗传背景中可引起小麦染色体发生断裂、重接从而产生染色体结构变异, 利用这一机制, 用抗赤霉病普通小麦-大赖草Lr2和Lr7染色体二体附加系与普通小麦-柱穗山羊草的2C杀配子染色体二体附加系杂交, 再用中国春回交, 采用染色体C分带技术从BC1中初筛出染色体结构发生变异的植株, 再通过染色体C分带和基因组荧光原位杂交技术, 并结合花粉母细胞减数分裂中期Ⅰ的染色体配对分析, 对其自交后代作细致的细胞学分析, 选育出3个普通小麦-大赖草纯合易位系T1DS-Lr7L(98002, NAU633), T4AL·4AS-Lr7S(98004, NAU634)和T1BL-Lr2S (98048, NAU635), 以及一批尚待鉴定的含小麦与大赖草染色体易位植株. 对杀配子染色体在诱导小麦与外源染色体间易位的可行性和效率, 以及异易位系的利用价值进行了讨论.     

小麦—大赖草易位系的RFLP分析

利用辐射、花药培养及杀配子基因效应已创制出一系列小麦-大赖草易位系.为在其中找出可能的纯合易位系、明确易位所涉及的相关染色体以及易位断裂点的确切位置,利用了已被定位于小麦7个部分同源群染色体长、短两臂上的67个探针进行了RFLP分析,结果鉴定出3个纯合的易位系:T1BL*7Lr#1S、T4BS*4BL-7Lr#1S和T6AL*7Lr#1S.其中,易位系T1BL*7Lr#1S和T6AL*7Lr#1S中染色体7Lr#1的断裂点位于标记MWG808和标记ABG476.1之间,而1B和6A染色体上的断裂点都在着丝粒附近.易位系T4BS*4BL-7Lr#1S中染色体7L#1的断裂点位于标记BCD349和标记CDO595之间,4B染色体断裂点则位于标记CDO541和标记PSR164之间的长臂上.     

利用减数分裂期成株电离辐射选育小麦—大赖草易位系的研究

采用６００１１２５Ｒ剂量的６０Ｃｏγ射线对小麦（ＴｒｉｔｉｃｕｍａｅｓｔｉｖｕｍＬ．）大赖草（Ｌｅｙｍｕｓｒａｃｅｍｏｓｕｓ（Ｌａｍ．）Ｔｚｖｅｌ．）Ｌｒ．７单体异附加系在减数分裂期进行成株辐射处理,经过Ｍ１代根尖细胞有丝分裂中期（ＲＴＣ,Ｍ期）染色体ＧｉｅｍｓａＣ分带粗筛,Ｍ２代ＲＴＣＭ期染色体Ｃ分带和荧光原位杂交鉴定,选育出２个小麦大赖草Ｌｒ．７异易位系。其中Ｔ０２易位系是由Ｌｒ．７染色体绝大部分与一小片段小麦染色体接在一起组成的易位类型（ＴＬｒ．７·Ｌｒ．７Ｗ）;Ｔ０８的易位染色体由小麦４ＡＬ和大赖草Ｌｒ．７某臂组成。     

将大赖草种质转移给普通小麦的研究——Ⅶ.一个普通小麦-大赖草等臂染色体异附加系的选育与鉴定

通过花粉母细胞减数分裂中期Ⅰ染色体配对构型分析、Giemsa C-分带,从普通小麦-大赖草第7条染色体二体异附加系自交后代中选育并鉴定出了93G51-9和93G52-8 2个等臂染色体异附加系。该异附加系在花粉母细胞减数分裂中期Ⅰ,其等臂染色体自身两臂配对频率高,染色体易发生断裂,且又携带有较抗赤霉病的基因,是向小麦转移大赖草赤霉病抗性基因的有用中间材料。     

小麦—冰草T7PL·7AL罗伯逊易位系的分子细胞学鉴定

冰草是小麦遗传改良的重要野生近缘植物之一,有目标的导入冰草外源优异基因是拓宽小麦遗传基础的有效途径。前期研究表明:小麦-冰草衍生系II-23(2n=38W+6P)由19对小麦染色体(缺少4B和7A)和3对冰草染色体(2P、4P和7P)组成。本研究报道从II-23的回交后代中分离鉴定出1个自发易位系7-20。基因组原位杂交(GISH)鉴定表明7-20是一个整臂易位系;经非变性荧光原位杂交(ND-FISH)检测发现,小麦的7A染色体发生易位;进一步利用小麦7A染色体特异SSR标记以及冰草7P染色体特异STS标记对7-20易位系中的外源易位片段大小以及易位染色体的组成进行鉴定,确定7-20为T7PL·7AL罗伯逊易位系(Robertsonian translocation line)。对该易位系与小麦品种Fukuhokomugi构建的BC1F2和BC2F1世代分离群体进行田间农艺性状考察,发现该易位系阳性株系和阴性株系在有效分蘖数和千粒重性状上无显著差异,在株高上表现为阳性材料显著低于阴性材料,但同时出现穗粒数下降的现象。总之,本研究表明易位系7-20为T7PL·7AL罗伯逊易位,该创新材料不仅为后续利用断裂—融合机制创制出更多的补偿易位材料提供了理论依据,而且也为今后向小麦中转移冰草优异基因提供了重要的中间桥梁材料。     

利用离果山羊草3C染色体诱导簇毛麦4V染色体结构变异

通过普通小麦农林26-离果山羊草3C异附加系与普通小麦-簇毛麦4V（4D）代换系杂交,杂交F1代与普通小麦回交,综合运用染色体构型分析、C-分带和荧光原位杂交等技术从BC1F2、BC1F3代中鉴定出涉及簇毛麦4V染色体的易位系、端体、等臂染色体系等变异植株,表明离果山羊草3C染色体可有效诱发簇毛麦4V染色体结构变异,是创造小麦-簇毛麦4V易位系的一种有效途径。     

利用荧光原位杂交技术检测导入普通小麦的大赖草染色质

利用以大赖草基因组ＤＮＡ为探针的荧光原位杂交技术对导入普通小麦的大赖草染色质进行检测。结果：９１）根尖体中花粉母细胞时期均可用于检测大赖草染色质。间期核中杂交信号点数与所含大赖草染色体数目之间的对应关系依染色体显强Ｃ－带末端数不同而不同;（２）利用荧光原位杂交,从普通小麦－大赖草单体异附加系的减数分裂前植株＾６０Ｃｏ－γ射线辐射后代中检测到一批大赖草端着丝粒染色体和小麦－大赖草染色体易位等结构变异     

苏麦3号感赤霉病近等基因系的选育及分子标记

小麦品种苏麦3号高抗由禾谷镰刀菌（Fusarium graminearum Schw.)引起的小麦赤霉病,已成为全世界广泛应用的抗源。为更精确地研究苏麦3号的赤霉病抗性,实验用感病品种川980为供体亲本,苏麦3号为轮回亲本,通过不断回交和自交,把川980的赤霉病感病基因导入苏麦3号,创造了感赤霉病的苏麦3号近等基因系（S016）,并得到以下结果：（1）育成的苏麦3号感赤霉病近等基因系,经两年多点抗赤霉病性状鉴定,表明该近等基因系感赤霉病感病性稳定,而其他形态特征,特性与苏麦3号一致。（2）用RAPD,RFLP分析抗,感苏麦3号近等基因系之间的差异,RFLP分析发现该近等基因系在2D染色体上存在差异。RPAD的随机扩增产物OPH191400可能与近等基因系中的赤霉病感病基因非连锁。（3）用近等基因系验证已报道的与小麦抗霉病基因有关的分子标记,均未发现这些分子标记与导致该近等基因系抗性差异的基因有关。     

利用电离辐射处理整臂易位系成熟雌配子诱导外源染色体小片段易位

簇毛麦（Haynaldia villosa）是小麦（Triticum aestivum）改良的重要遗传资源．培育小片段易位,特别是中间插入易位,有助于更好地利用外源有益基因．已报道的小麦-簇毛麦易位系大多数属于整臂易位或大片段易位．本研究以60Co-γ谢线（剂量率：1．6Gy／min,三种剂量：16．0,19．2和22．4Gy）处理整臂易位系的成熟雌配子,随后选取适龄穗子去雄套袋,2～3天后再用普通小麦品种“中国春”的新鲜成熟花粉授粉．通过M1植株根尖细胞有丝分裂中期染色体基因组原位杂交（genomic in situ hybridization,GISH）,从534株M1材料中检测到97株涉及6V染色体短臂（6VS）的小片段结构变异,包括小片段中间插入易位染色体80条、末端易位染色体57条和6VS缺失55条．在22．4Gy处理中这三种结构变异的诱变频率分别为21．02％,14．01％和14．65％,远远高于已报道的结果．获得了涉及146条6VS小片段结构变异的74株M1材料的回交种子．M1植株中的小片段结构变异可通过回交传递给后代．利用电离辐射处理整臂易位系成熟雌配子是一种高效诱导染色体小片段结构变异、特别是中间插入易位的新方法．     

Paxillus involutus Strains MAJ and NAU mediate K(+)/Na(+) homeostasis in ectomycorrhizal Populus x canescens under sodium chloride stress

Salt-induced fluxes of H(+), Na(+), K(+), and Ca(2+) were investigated in ectomycorrhizal (EM) associations formed by Paxillus involutus (strains MAJ and NAU) with the salt-sensitive poplar hybrid Populus × canescens. A scanning ion-selective electrode technique was used to measure flux profiles in non-EM roots and axenically grown EM cultures of the two P. involutus isolates to identify whether the major alterations detected in EM roots were promoted by the fungal partner. EM plants exhibited a more pronounced ability to maintain K(+)/Na(+) homeostasis under salt stress. The influx of Na(+) was reduced after short-term (50 mm NaCl, 24 h) and long-term (50 mm NaCl, 7 d) exposure to salt stress in mycorrhizal roots, especially in NAU associations. Flux data for P. involutus and susceptibility to Na(+)-transport inhibitors indicated that fungal colonization contributed to active Na(+) extrusion and H(+) uptake in the salinized roots of P. × canescens. Moreover, EM plants retained the ability to reduce the salt-induced K(+) efflux, especially under long-term salinity. Our study suggests that P. involutus assists in maintaining K(+) homeostasis by delivering this nutrient to host plants and slowing the loss of K(+) under salt stress. EM P. × canescens plants exhibited an enhanced Ca(2+) uptake ability, whereas short-term and long-term treatments caused a marked Ca(2+) efflux from mycorrhizal roots, especially from NAU-colonized roots. We suggest that the release of additional Ca(2+) mediated K(+)/Na(+) homeostasis in EM plants under salt stress.     

Embryo and Endosperm Function and Failure inSolanumSpecies and Hybrids

Although the importance of the endosperm as a food store inmany angiosperm seeds is well known, its significance duringearly embryogenesis has been neglected. In many interspecifichybrids, and in some other situations, embryos do not developfully and abort. It has often been stated that this is causedby the endosperm failing to conduct sufficient nutrients tothe embryo, but seldom has it been suggested that the endospermactively controls most of the early stages of morphogenesisof the embryo. Information gleaned from a broad survey of theliterature, combined with additional evidence presented here,obtained fromSolanum incanumand interspecific hybrids, indicatethat the endosperm is dynamic and very active in regulatingearly embryo development. This requires highly integrated geneticcontrol of rapidly changing metabolism in the endosperm. Ininterspecific hybrids, lack of coordination may cause unbalancedproduction of growth regulating substances by the endospermand hence abortion of the embryo, or even unregulated productionof nucleases and proteases resulting firstly in autolysis ofthe endosperm and then digestion of the embryo. The endospermmay thus serve to detect inappropriate hybridization of speciesor ploidy levels and so prevent waste of resources by producingseeds that would result in sterile hybrids or unthrifty subsequentgenerations. This discriminatory function of the endosperm hasdiminished during evolution and domestication of the crop plantSolanummelongenaL.Copyright 1998 Annals of Botany Company Solanum, embryo morphogenesis, endosperm, hybrid, seed development.     

Pragmatic Women and Body Politics and Maternities and Modernities: Colonial and Postcolonial Experiences in Asia and the Pacific

Pragmatic Women and Body Politics. Margaret Lock and Patricia A. Kaufert. eds. Cambridge, UK: Cambridge University Press, 1998. xii +364 pp.
Maternities and Modernities: Colonial and Postcolonial Experiences in Asia and the Pacific. Kalpana Ram and Margaret Jolly. eds. Cambridge, UK: Cambridge University Press, 1998. xiv. 305 pp.     

HIFs and tumors--causes and consequences

For most organisms oxygen is essential fo life. When oxygen levels drop below those required to maintain the minimum physiological oxygen requirement of an organism or tissue it is termed hypoxia. To counter act possible deleterious effects of such a state, an immediate molecular response is initiated causing adaptation responses aimed at cell survival. This response is mediated by the hypoxia-inducible factor-1 (HIF-1), which is a heterodimer consisting of an alpha- and a beta-subunit. HIF-1 alpha protein is stabilized under hypoxic conditions and therefore confers selectivity to this response. Hypoxia is characteristic of tumors, mainly because of impaired blood supply resulting from abnormal growth. Over the past few years enormous progress has been made in the attempt to understand how the activation of the physiological response to hypoxia influences neoplastic growth. In this review some aspects of HIF-1 pathway activation in tumors and the consequences for pathophysiology and treatment of neoplasia are discussed.     

环腺苷酸应答元件结合蛋白与学习记忆

环腺苷酸(cAMP)应答元件结合蛋白(cAMP response element binding protein,CREB)是一种核转录因子,可与cAMP反应元件结合,调节基因转录,具有调节精子生成,昼夜节律,学习记忆等功能.近年来关于其在学习记忆中的作用成为医学研究热点.CREB是神经元内多条信息传递途径的汇聚点,参与长时记忆形成和突触可塑性.长时记忆(long-term memory)形成需依赖CREB介导的基因转录,干扰或抑制CREB活性可破坏长时记忆.长时程增强(long-term potentiation,LTP)是研究学习记忆的理想模型,在LTP诱导和维持过程中均可观察到CREB活性持续升高.但增龄过程中,海马CREB活性下降,影响学习记忆功能,与许多神经退行性疾病发生有关.     

白蚁与动物及微生物的共生类型及其机制

综述了白蚁螱客的主要种类、共生关系及相关机制的研究进展。白蚁螱客中,已报道的动物种类达170种。在与动物的共生关系中存在偏利共生（宾主共栖和异种共栖）、互利共生和无关共生三种;在与微生物的共生关系中,存在与内生菌（原生动物、细菌、真菌和放线菌）和外生菌（蚁巢伞菌等）间的互利关系。指出了白蚁与螱客研究中存在的问题,给出了解决方案,并提出了今后可能的研究热点或方向,为白蚁的综合利用（如纤维素酶）及今后研究物种间的协同进化提供了基础资料。