Genes of the major histocompatibility complex in mouse and man

The genes of the major histocompatibility complex code for cell-surface molecules that play an important role in the generation of the immune response. These genes and molecules have been studied intensively over the last five decades by geneticists, biochemists, and immunologists, but only recently has the isolation of the genes by molecular biologists facilitated their precise characterization. Many surprising findings have been made concerning their structure, multiplicity, organization, function, and evolution.     

Inherited epilepsy: spike-wave and focal motor seizures in the mutant mouse tottering

Mice with the mutant gene tottering (tg, chromosome 8, autosomal recessive) show, in adolescence, abnormal bursts of bilaterally synchronous spike waves as revealed in electrocorticograms recorded over long periods. The spike waves are accompanied by behavioral "absence" attacks and intermittent focal motor seizures showing somatotopic progression. Cerebral metabolic activity during seizures was assayed by autoradiography of brain sections from mice injected intravenously with 14C-labeled 2-deoxyglucose. Metabolic activity was increased bilaterally in selected brainstem structures. Spontaneous electrocorticographic and clinical seizures of this general pattern were recognized hitherto only in humans.     

植物抗旱相关功能基因研究进展

综述了影响植物抗旱性的各相关功能基因的研究进展及其在抗旱基因工程上的应用现状。干旱是影响植物正常生长发育的一个最重要的逆境因子。人们对植物的抗旱性进行了多层次研究,并从各种生物中鉴别和定位了几十种与提高抗旱性相关的基因,为从分子水平上研究植物的抗旱性奠定了基础。近年来,人们发现了更多的抗旱基因,对已知抗旱基因也有了更深入的研究,并成功转化了多种不同类型的植物,提高了其抗旱能力。     

Shadows cast by retinal blood vessels mapped in primary visual cortex

The mammalian eye is a remarkable optical device, but its design is not perfect. The blood vessels that supply the inner retina are located in front of the photoreceptor layer, blocking access to light. Their shadows create a pattern of blindness in the field of vision that corresponds precisely to the location of the largest vessels in the eye. We show here that in squirrel monkeys, focal deprivation by blood vessels leads to rewiring of the eye's geniculocortical projections, imprinting an image of the retinal vascular tree onto the primary visual cortex. This process illustrates vividly that local imbalances in neuronal activity can influence column formation during normal development.     

An active subglacial water system in West Antarctica mapped from space

Satellite laser altimeter elevation profiles from 2003 to 2006 collected over the lower parts of Whillans and Mercer ice streams, West Antarctica, reveal 14 regions of temporally varying elevation, which we interpret as the surface expression of subglacial water movement. Vertical motion and spatial extent of two of the largest regions are confirmed by satellite image differencing. A major, previously unknown subglacial lake near the grounding line of Whillans Ice Stream is observed to drain 2.0 cubic kilometers of water into the ocean over approximately 3 years, while elsewhere a similar volume of water is being stored subglacially. These observations reveal a wide spread, dynamic subglacial water system that may exert an important control on ice flow and mass balance.     

普通小麦多小穗基因定位

普通小麦（ＴｒｉｔｉｃｕｍａｅｓｔｉｖｕｍＬ．）多小穗被认为是小麦高产育种的理想穗型〔８、１２〕,但对多小穗资源的遗传研究甚少〔１３〕。本研究采用的分枝１号是颜济等利用穗分枝普通小麦研制的不分枝多小穗新材料,其小穗数最高可达３４个,它有明显优于１０－...     

小麦ADP-核糖基化因子克隆及序列分析

二磷酸腺苷-核糖基化作用因子(ADP-ribosylation factors,ARFs)是真核细胞囊泡运输通道的关键组成成分,参与细胞运输和信号传导。根据GenBank中已知ARF基因序列设计引物,对小麦及其二倍体供体种基因组DNA进行PCR扩增、克隆、测序。结果表明:从小麦中克隆的ARF基因属于ARF1基因;与其他物种的ARF基因对比发现,该基因的内含子存在特殊的剪切方式。氨基酸序列分析表明,小麦的ARF同其他物种一样,具有保守的GTP结合区域。     

基因芯片技术在水稻抗逆基因表达研究中的应用

水稻是世界上最重要的粮食作物之一,全世界50%以上的人口以水稻为主食,导致水稻减产的主要原因之一是受逆境胁迫的影响。为了提高水稻的抗逆性,目前国内外许多实验室正致力于水稻抗逆机制的研究。与抗逆相关的单一基因较难以揭示植物复杂的抗逆机制,而基因芯片技术却可以揭示大量基因表达和调控的情况,使得多基因的调控研究成为可能。本文主要综述了近年来基因芯片技术在水稻受逆境胁迫条件下基因的表达情况。     

羽衣甘蓝花青素合成途径结构基因的表达特性

羽衣甘蓝红鸽属十字花科云薹属,因其中心部分累积了大量的花青素而呈现深紫色。为了研究其花青素生物合成的机理,以圆叶羽衣甘蓝红鸽系列和白鸽系列为试验材料,通过半定量RT-PCR方法研究了花青素合成代谢途径结构基因的表达特性。结果表明,除苯丙氨酸裂解酶(PAL)和查尔酮合成酶(CHS)在红鸽和白鸽系列中的表达水平基本一致外,其他结构基因在红鸽中的表达水平要明显高于白鸽,尤其二氢黄酮醇还原酶(DFR)和花青素合成酶(ANS),在红鸽中的表达水平显著强于白鸽;红鸽幼叶和老叶中花青素生物合成结构基因的表达水平趋于一致。另外,为了研究温度对羽衣甘蓝花青素合成的影响,通过半定量RT-PCR方法检测了室温和低温环境下生长的红鸽幼叶花青素合成结构基因的表达。结果显示,低温可以诱导CHS,黄烷酮-3-羟化酶(F3H),DFR,ANS,类黄酮-葡萄糖基转移酶(UFGT)基因的过量表达,使羽衣甘蓝红鸽经历低温后,植株中积累大量的花青素而呈现深紫色。     

增强外源基因在转基因植物中表达的策略

在转基因研究和生产应用中,人们往往期待目的基因能在转基因生物中高效表达从而实现相关目的--获得具有对杀虫剂、除草剂高抗性的农作物,或以植物作为生物反应器生产具有高附加值的疫苗、抗生素等医药用品以及工业用蛋白、酶类等。综述了各种用于增强外源基因表达效率的策略,从外源基因的整合、转录水平的调节以及外源基因翻译后的蛋白分选三个水平阐述提高外源基因表达的相关策略的利弊,从而为转基因研究提表达供载体构建方面的参考依据。     

植物抗病基因的研究进展

综合介绍近年来国内外植物抗病基因的研究成果,对植物抗病基因进行归纳、分类,包括抗病基因的克隆方法及分类、抗病基因的结构特点、功能及其进化,并探讨其应用前景。     

Fluorinated molecule as a tracer: difluoroserotonin in human platelets mapped by electron energy-loss spectroscopy

The intracellular distribution of fluorine has been delineated in human platelets incubated with 4,6-difluoroserotonin, utilizing a scanning-transmission electron microscope equipped with an energy-loss spectrometer. Discrete intracellular structures corresponding in location to dense bodies contained high concentrations of fluorine. Electron energy-loss spectroscopy, which apparently can detect less than 10(-20) gram of fluorine in an area of 10 square nonometers, can thus localize fluorinated tracer molecules with biological activity.     

新疆棕色棉纤维色泽决定相关数量性状决定基因的QTL定位

[目的]研究新疆棕色棉纤维色素决定基因的QTL定位,为分子标记辅助选择育种提供理论依据.[方法]通过中棉所41号和彩色棉1号杂交的F2群体作为QTL定位群体,在整个棉花基因组中选择350条引物,应用复合区间做图法,对棕色棉纤维色素决定基因进行QTL定位.[结果]经过亲本筛选后,共得到多态性引物45对.分别用此45对引物对F2代群体的137个单株进行扩增,检测到9个QTL连锁群,其中两个有效QTL位点定位到15号染色体上,分别命名为qFC15-1和qFC15-2,可解释表型变异率分别为16.3和0.5.[结论]筛选获得2个棕色棉纤维色素决定基因QTL位点,为进一步克隆该基因奠定基础.     

A vasculature-associated niche for undifferentiated spermatogonia in the mouse testis

Mammalian spermatogenesis produces numerous sperm for a long period based on a highly potent stem cell system, which relies on a special microenvironment, or niche, that has not yet been identified. In this study, using time-lapse imaging of green fluorescent protein-labeled undifferentiated spermatogonia (A(undiff)) and three-dimensional reconstitution, we revealed a biased localization of A(undiff) to the vascular network and accompanying Leydig and other interstitial cells, in intact testes. Differentiating spermatogonia left these niche regions and dispersed throughout the basal compartment of the seminiferous epithelium. Moreover, rearrangement of A(undiff) accompanied the vasculature alteration. We propose that the mammalian germline niche is established as a consequence of vasculature pattern formation. This is different from what is observed in Drosophila or Caenorhabditis elegans, which display developmentally specified niche structures within polarized gonads.     

Expanded repeat in canine epilepsy

Epilepsy afflicts 1% of humans and 5% of dogs. We report a canine epilepsy mutation and evidence for the existence of repeat-expansion disease outside humans. A canid-specific unstable dodecamer repeat in the Epm2b (Nhlrc1) gene recurrently expands, causing a fatal epilepsy and contributing to the high incidence of canine epilepsy. Tracing the repeat origins revealed two successive events, starting 50 million years ago, unique to canid evolution. A genetic test, presented here, will allow carrier and presymptomatic diagnosis and disease eradication. Clinicopathologic characterization establishes affected animals as a model for Lafora disease, the most severe teenage-onset human epilepsy.