小鼠胚胎脑特异表达的新基因bsg3的克隆及初步研究

通过消减差异筛选的方法克隆到一个在小鼠胚胎脑特异表达的基因bsg3(brain specific gene 3).它编码的蛋白与人的KIAA0961具有80.3%的同源性.bsg3基因包含一个1644bp的完整阅读框,编码一个含548个氨基酸,具有1个KRAB结构域(kruppel-associated box)和13个C2H2型锌指结构域的蛋白.该基因定位在小鼠第7号染色体上,包含5个外显子,4个内含子.以bsg3基因全长编码区为探针的原位杂交结果显示,bsg3在小鼠胚胎脑及鸡胚脑特异表达.半定量反转录聚合酶链式反应(RT-PCR)的结果表明,在成体小鼠的组织中,bsg3基因脑中表达也较强.这提示bsg3基因可能在小鼠脑发育中起着重要的作用.对bsg3基因时间和空间的表达模式的分析将有助于进一步揭示它在脑发育及功能维持中的作用.     

Distal-less encodes a homoeodomain protein required for limb development in Drosophila

The spatial organization of the Drosophila embryo depends on the activity of three axial pattern-forming systems. In addition to the anterior-posterior and dorsal-ventral systems that organize the segmented body plan, a proximal-distal pattern-forming system is required to provide positional information for the developing limbs. The development of both the larval and adult limbs depends directly on the activity of the Distal-less gene. Genetic analysis has shown that Distal-less functions as a developmental switch that is required to promote the development of limb structures above the evolutionary ground-state of body wall. Here we provide genetic evidence that indicates a graded requirement for Distal-less activity during limb development. Reduction of this activity has a global effect on pattern formation in the limb. The molecular structure of the Distal-less locus indicates that the gene encodes a homoeodomain-containing protein which is therefore likely to specify limb development through differential regulation of subordinate genes.     

拟南芥雄性不育基因ds254的定位及其表达模式

通过Ac／Ds转座子系统的诱变，得到拟南芥突变体DS254．它的发育进程比野生型慢，植株比野生型矮小，连座叶柄比野生型的短，花苞数目比野生型的多，分枝的数量比野生型的多，且雄性不育．遗传分析表明突变体属于隐性单基因突变，稳定遗传，并且与Ds是紧密连锁的。可能是Ds插入直接引起的突变．TAIL—PCR的方法将该基因定位在第4条染色体上．Ds上携带的GUS基因表迭的初步分析表明，GUS基因在突变体的花药和连座叶中表达，说明该基因也可能在这些部位表达．突变体的表型分析结果说明该基因可能在植物的许多发育过程中起作用．     

Control of leaf morphogenesis by microRNAs

Plants with altered microRNA metabolism have pleiotropic developmental defects, but direct evidence for microRNAs regulating specific aspects of plant morphogenesis has been lacking. In a genetic screen, we identified the JAW locus, which produces a microRNA that can guide messenger RNA cleavage of several TCP genes controlling leaf development. MicroRNA-guided cleavage of TCP4 mRNA is necessary to prevent aberrant activity of the TCP4 gene expressed from its native promoter. In addition, overexpression of wild-type and microRNA-resistant TCP variants demonstrates that mRNA cleavage is largely sufficient to restrict TCP function to its normal domain of activity. TCP genes with microRNA target sequences are found in a wide range of species, indicating that microRNA-mediated control of leaf morphogenesis is conserved in plants with very different leaf forms.     

Suitable internal control genes for qRT-PCR normalization in cotton fiber development and somatic embryogenesis

The mechanisms of cotton fiber development and somatic embryogenesis have been explored sys-tematically with microarray and suppression subtractive hybridization. Real-time RT-PCR provides the simultaneous measurement of gene expression in many different samples,with which the data from microarray or others can be confirmed in detail. To achieve accurate and reliable gene expression re-sults,normalization of real-time PCR data against one or several internal control genes is required,which should not fluctuate in different tissues during various stages of development. We assessed the gene expression of 7 frequently used housekeeping genes,including 18S rRNA,Histone3,UBQ7,Actin,Cyclophilin,Gbpolyubiquitin-1 and Gbpolyubiquitin-2,in a diverse set of 21 cotton samples. For fiber developmental series the expression of all housekeeping genes had the same down tendency after 17 DPA. But the expression of the AGP gene(arabinogalactan protein) that has high expression level at the later fiber development stage was up-regulated from 15 to 27 DPA. So the relative absolute quanti-fication should be an efficient and convenient method for the fiber developmental series. The expres-sion of nonfiber tissues series varied not so much against the fiber developmental series. And three best control genes Histone3,UBQ7 and Gbpolyubiquitin-1 have to be used in a combinated way to get better normalization.     

A transgene containing lacZ inserted into the dystonia locus is expressed in neural tube

The site of integration of transgenes in the host genome can affect levels of expression and occasionally confer ectopic patterns of expression on otherwise tissue-specific genes. We describe here a line of mice in which an hsp68-lacZ transgene is expressed in unstressed developing neural tissue and where the transgene insertion has caused a mutation of a neural tissue-specific gene, dystonia musculorum (dt). This coincidence suggests that expression of the hsp68-lacZ construct may be controlled directly by cis-acting regulatory sequences that normally control the developmental expression of the dt gene. Such constructs may serve as useful tools for identifying new tissue-specific enhancers and their associated genes.     

Ephrin Bs are essential components of the Reelin pathway to regulate neuronal migration

Coordinated migration of neurons in the developing and adult brain is essential for its proper function. The secreted glycoprotein Reelin (also known as RELN) guides migration of neurons by binding to two lipoprotein receptors, the very-low-density lipoprotein receptor (VLDLR) and apolipoprotein E receptor 2 (ApoER2, also known as LRP8). Loss of Reelin function in humans results in the severe developmental disorder lissencephaly and it has also been associated with other neurological disorders such as epilepsy, schizophrenia and Alzheimer's disease. The molecular mechanisms by which Reelin activates its receptors and controls cellular functions are largely unknown. Here we show that the neuronal guidance cues ephrin B proteins are essential for Reelin signalling during the development of laminated structures in the brain. We show that ephrin Bs genetically interact with Reelin. Notably, compound mouse mutants (Reln(+/-); Efnb3(-/-) or Reln(+/-); Efnb2(-/-)) and triple ephrin B1, B2, B3 knockouts show neuronal migration defects that recapitulate the ones observed in the neocortex, hippocampus and cerebellum of the reeler mouse. Mechanistically, we show that Reelin binds to the extracellular domain of ephrin Bs, which associate at the membrane with VLDLR and ApoER2 in neurons. Clustering of ephrin Bs leads to the recruitment and phosphorylation of Dab1 which is necessary for Reelin signalling. Conversely, loss of function of ephrin Bs severely impairs Reelin-induced Dab1 phosphorylation. Importantly, activation of ephrin Bs can rescue the reeler neuronal migration defects in the absence of Reelin protein. Together, our results identify ephrin Bs as essential components of the Reelin receptor/signalling pathway to control neuronal migration during the development of the nervous system.     

Differential display of carrot radicle genes in different developmental states

mRNA differential display was used in analyzing the expression of carrot somatic embryo radicle gene in different developmental stages brought about by controlled cultivation. As shown by experiment, marked differences in electrophoresis patterns of DNA exist between the normally developing carrot radicle and those with their development inhibited. 12 series of specific bands have been cloned, and structural analysis of them is under way.     

Specific expression of a foreign beta-globin gene in erythroid cells of transgenic mice

The globin gene family represents an attractive system for the study of gene regulation during mammalian development, as its expression is subject to both tissue-specific and temporal regulation. While many aspects of globin gene structure and expression have been described extensively, relatively little is known about the cis-acting DNA sequences involved in the developmental regulation of globin gene expression. To begin to experimentally define these regulatory sequences, we have taken the approach of introducing cloned globin genes into the mouse germ line and examining their expression in the resulting transgenic animals. Here we describe a series of transgenic mice carrying a hybrid mouse/human adult beta-globin gene, several of which express the gene exclusively or predominantly in erythroid tissues. These studies demonstrate that regulatory sequences closely linked to the beta-globin gene are sufficient to specify a correct pattern of tissue-specific expression in a developing mouse, when the gene is integrated at a subset of foreign chromosomal positions.     

水稻bHLH转录因子Os11g39000的功能研究

水稻Os11g39000为非典型的bHLH家族成员,其功能尚不清楚.酵母双杂交实验表明,转录因子Os11g39000可以形成同源蛋白聚合体.随机结合位点筛选实验表明,转录因子Os11g39000可以与DNA结合,并且其结合位点初步确定为TT/CG/CACC/GT/C.Os11g39000基因的组织表达模式分析发现,Os11g39000基因主要在叶片和根中表达,推测该基因可能在叶和根的发育调控中发挥作用.水培实验发现,该基因功能缺陷型转基因株系的根长显著短于野生型,表现出明显的根部发育缺陷,表明Os11g39000在水稻根的发育中起调控作用.Q-PCR分析进一步证明,功能缺陷型转基因植株体内生长素合成和信号转导相关基因表达量显著上升,表明转录因子Os11g39000参与了水稻生长素的合成和信号转导的调控.     

营造滨湖概念构建生态合肥

由于城市防洪能力的提高,规模不断扩大,使合肥城市东南侧留作风道的建设控制区以其靠近市中心的区位优势和滨临巢湖的优势,正在吸引大量的投资,城市空间形态表现出对合肥历史上已经形成的非常具有特点的风扇状城市形态的重构趋势.这一地区如何发展,将对合肥未来的发展定位和城市特色起决定性作用.该文从行政区划的调整,城市发展的趋势分析,明确了这一地区的功能定位和下一步的开发建设目标.     

SPL转录因子调控植物花发育及其分子机制研究进展

SPL(squamosa promoter-binding protein-like)转录因子是植物所特有的一类基因家族,广泛存在于绿色植物中,在植物生长发育中具有重要作用。花发育是植物生殖发育中最为重要的一个过程,涉及不同发育方式的转变,即开花决定、花的发端和花器官发生与发育。简要综述了SPL基因的结构与功能并着重阐述了SPL基因在植物花发育过程中的分子机制及生物学功能。最后总结出: SPL转录因子可直接或间接通过参与光周期途径,赤霉素途径及年龄途径来调控植物的开花时间; SPL基因可通过直接激活下游花分生组织特异基因,如LEAFY(LFY),从而调控植物的成花转变; SPL基因可通过与下游花器官特征基因相互作用来调控花器官及其育性的发育,如调控花序、花柄的长度与外形及花器官的大小; SPL基因可调控植物大小孢子发生及雌雄配子体发育。据拟南芥的相关研究结果,初步构绘出拟南芥开花调控中的分子机制。     

安徽省特殊教育学校课余体育训练思考

运用文献资料、调查、数理统计、逻辑分析等研究方法,对安徽省特殊教育学校课余体育训练现状进行调查,并对影响其发展的因素作出思考与分析,在此基础上提出相应的发展对策:营造有利于开展特殊教育学校课余体育训练的社会环境;提高参训残障学生对残疾人体育功能的认识;逐步改善特殊教育学校体育物质条件;改进训练方法、提高训练水平等,旨在为特殊教育学校课余体育训练工作的改革与发展提供参考.     

BH3-only Bcl-2 family member Bim is required for apoptosis of autoreactive thymocytes

During lymphocyte development, the assembly of genes coding for antigen receptors occurs by the combinatorial linking of gene segments. The stochastic nature of this process gives rise to lymphocytes that can recognize self-antigens, thereby having the potential to induce autoimmune disease. Such autoreactive lymphocytes can be silenced by developmental arrest or unresponsiveness (anergy), or can be deleted from the repertoire by cell death. In the thymus, developing T lymphocytes (thymocytes) bearing a T-cell receptor (TCR)-CD3 complex that engages self-antigens are induced to undergo programmed cell death (apoptosis), but the mechanisms ensuring this 'negative selection' are unclear. We now report that thymocytes lacking the pro-apoptotic Bcl-2 family member Bim (also known as Bcl2l11) are refractory to apoptosis induced by TCR-CD3 stimulation. Moreover, in transgenic mice expressing autoreactive TCRs that provoke widespread deletion, Bim deficiency severely impaired thymocyte killing. TCR ligation upregulated Bim expression and promoted interaction of Bim with Bcl-XL, inhibiting its survival function. These findings identify Bim as an essential initiator of apoptosis in thymocyte-negative selection.     

Neural cell adhesion molecules and myelin-associated glycoprotein share a common carbohydrate moiety recognized by monoclonal antibodies L2 and HNK-1

Cell surface molecules have been implicated in cell interactions which underlie formation of the nervous system. The analysis of the functional properties of such molecules has profited from the combined use of antibodies and cell culture systems. It has been suggested that the interplay between these molecules modulates cell-to-cell interaction at critical developmental stages. In the mouse, N-CAM and L1 antigen have been shown to mediate Ca2+-independent adhesion among neural cells. N-CAM plays a role in fasciculation of neurites and formation of neuromuscular junction. L1 is apparently not involved in synaptogenesis, but in migration of granule cell neurones in the developing mouse cerebellar cortex. The two antigens are distinct molecular and functional entities which act synergistically in aggregation of neuroblastoma and early postnatal cerebellar cells. In view of a certain similarity in function between the two groups of molecules, it was not surprising to find that structural similarities are detectable by the monoclonal antibody L2. We show here that a carbohydrate moiety recognized by L2 and HNK-1 monoclonal antibodies, is present in mouse N-CAM and L1. The L2 epitope appears on all major neural cell types but not all N-CAM molecules express it. This heterogeneity points to a previously undetected molecular diversity which may have functional implications for modulating cell adhesion during development.     

Caudal is the Hox gene that specifies the most posterior Drosophile segment.

The homeobox gene caudal (cad) has a maternal embryonic function that establishes the antero-posterior body axis of Drosophila. It also has a conserved late embryonic and imaginal function related to the development of the posterior body region. Here we report the developmental role of cad in adult Drosophila. It is required for the normal development of the analia structures, which derive from the most posterior body segment. In the absence of cad function, the analia develop like the immediately anterior segment (male genitalia), following the transformation rule of the canonical Hox genes. We also show that cad can induce ectopic analia development if expressed in the head or wing. We propose that cad is the Hox gene that determines the development of the fly's most posterior segment. cad acts in combination with the Hedgehog (Hh) pathway to specify the different components of the analia: the activities of cad and of the Hh pathway induce Distal-less expression that, together with cad, promote external analia development. In the absence of the Hh pathway, cad induces internal analia development, probably by activating the brachyenteron and even-skipped genes.