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Transposon-dependent mutant phenotypes at the Notch locus of Drosophila 总被引:10,自引:0,他引:10
Many mutations at complex genetic loci in the fruitfly Drosophila melanogaster are associated with insertions of transposable elements. At the Notch locus, members of one class of insertion-associated mutations, termed glossy-like, produce a recessive viable, smooth-eye phenotype with mottled pigmentation. Members of a second class, facet, produce a recessive viable, rough-eye phenotype with homogeneous pigmentation. Both classes of mutations fail to complement Notch lethal mutations, so they behave as Notch alleles. Here we report that each glossy-like mutation is associated with an insertion of the same transposable element (flea). Each flea insertion occurs in the same orientation, but at different locations within intervening sequences of the Notch locus. In contrast, each facet mutation is associated with insertion of a unique, non-flea, transposable element. Insertions producing a facet phenotype and insertions causing a glossy-like phenotype can break Notch intervening sequences at precisely the same location. This suggests that the type of insertion element rather than its position within an affected gene is the primary determinant of the phenotype observed. 相似文献
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Most of us sleep 7-8 h per night, and if we are deprived of sleep our performance suffers greatly; however, a few do well with just 3-4 h of sleep-a trait that seems to run in families. Determining which genes underlie this phenotype could shed light on the mechanisms and functions of sleep. To do so, we performed mutagenesis in Drosophila melanogaster, because flies also sleep for many hours and, when sleep deprived, show sleep rebound and performance impairments. By screening 9,000 mutant lines, we found minisleep (mns), a line that sleeps for one-third of the wild-type amount. We show that mns flies perform normally in a number of tasks, have preserved sleep homeostasis, but are not impaired by sleep deprivation. We then show that mns flies carry a point mutation in a conserved domain of the Shaker gene. Moreover, after crossing out genetic modifiers accumulated over many generations, other Shaker alleles also become short sleepers and fail to complement the mns phenotype. Finally, we show that short-sleeping Shaker flies have a reduced lifespan. Shaker, which encodes a voltage-dependent potassium channel controlling membrane repolarization and transmitter release, may thus regulate sleep need or efficiency. 相似文献
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The Drosophila eye, a paradigm for epithelial organization, is highly polarized with mirror-image symmetry about the equator. The R3 and R4 photoreceptors in each ommatidium are vital in this polarity; they adopt asymmetrical positions in adult ommatidia and are the site of action for several essential genes. Two such genes are frizzled (fz) and dishevelled (dsh), the products of which are components of a signalling pathway required in R3, and which are thought to be activated by a diffusible signal. Here we show that the transmembrane receptor Notch is required downstream of dsh in R3/R4 for them to adopt distinct fates. By using an enhancer for the Notch target gene Enhancer of split mdelta, we show that Notch becomes activated specifically in R4. We propose that Fz/Dsh promotes activity of the Notch ligand Delta and inhibits Notch receptor activity in R3, creating a difference in Notch signalling capacity between R3 and R4. Subsequent feedback in the Notch pathway ensures that this difference becomes amplified. This interplay between Fz/Dsh and Notch indicates that polarity is established through local comparisons between two cells and explains how a signal from one position (for example, the equator in the eye) could be interpreted by all ommatidia in the field. 相似文献
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Park J Lee SB Lee S Kim Y Song S Kim S Bae E Kim J Shong M Kim JM Chung J 《Nature》2006,441(7097):1157-1161
Autosomal recessive juvenile parkinsonism (AR-JP) is an early-onset form of Parkinson's disease characterized by motor disturbances and dopaminergic neurodegeneration. To address its underlying molecular pathogenesis, we generated and characterized loss-of-function mutants of Drosophila PTEN-induced putative kinase 1 (PINK1), a novel AR-JP-linked gene. Here, we show that PINK1 mutants exhibit indirect flight muscle and dopaminergic neuronal degeneration accompanied by locomotive defects. Furthermore, transmission electron microscopy analysis and a rescue experiment with Drosophila Bcl-2 demonstrated that mitochondrial dysfunction accounts for the degenerative changes in all phenotypes of PINK1 mutants. Notably, we also found that PINK1 mutants share marked phenotypic similarities with parkin mutants. Transgenic expression of Parkin markedly ameliorated all PINK1 loss-of-function phenotypes, but not vice versa, suggesting that Parkin functions downstream of PINK1. Taken together, our genetic evidence clearly establishes that Parkin and PINK1 act in a common pathway in maintaining mitochondrial integrity and function in both muscles and dopaminergic neurons. 相似文献
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Defective processing and presentation of exogenous antigens in mutants with normal HLA class II genes 总被引:7,自引:0,他引:7
Presentation of an exogenous protein antigen to helper (CD4+)T-lymphocytes by antigen presenting cells (APC) generally requires that the APCs degrade the native protein antigen into an immunogenic peptide, a process termed 'antigen processing', and that this peptide bind to a major histocompatibility complex (MHC) class II molecule. The complex of peptide and MHC molecule on the APC surface provides the stimulatory ligand for the alpha beta T cell receptor. The intracellular pathways and molecular mechanisms involved in the generation of the peptide-MHC complex are not well understood. Here, we describe several mutant APCs which are altered in their ability to present native exogenous protein antigens but effectively present immunogenic peptides derived from these proteins. The lesions in these mutants are not in the class II structural genes, but they affect the conformation of mature class II dimers. 相似文献
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Mutations in the human presenilin genes cause the most frequent and aggressive forms of familial Alzheimer's disease (FAD). Here we show that in addition to its role in cell fate decisions in non-neuronal tissues, presenilin activity is required in terminally differentiated neurons in vivo. Mutations in the Caenorhabditis elegans presenilin genes sel-12 and hop-1 result in a defect in the temperature memory of the animals. This defect is caused by the loss of presenilin function in two cholinergic interneurons that display neurite morphology defects in presenilin mutants. The morphology and function of the affected neurons in sel-12 mutant animals can be restored by expressing sel-12 only in these cells. The wild-type human presenilin PS1, but not the FAD mutant PS1 A246E, can also rescue these morphological defects. As lin-12 mutant animals display similar morphological and functional defects to presenilin mutants, we suggest that presenilins mediate their activity in postmitotic neurons by facilitating Notch signalling. These data indicate cell-autonomous and evolutionarily conserved control of neural morphology and function by presenilins. 相似文献
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A G Tatosyan S D Nabirochkin A K Shakhbazyan K G Gazaryan F L Kisseljov 《Nature》1984,311(5984):394-395
The injection of purified Rous sarcoma virus (RSV) (Prague strain) into Drosophila melanogaster (Oregon R line) eggs changes the fly phenotype in certain cases, and RSV-specific sequences can be identified in the Drosophila genome (ref. 1 and preceding paper). Here we have used Southern blotting to analyse in greater detail the proviral DNA present in several mutant lines of D. melanogaster produced by microinjection of intact RSV or plasmid DNA containing the viral insert. In certain populations of flies, RSV provirus was found to be incorporated into cellular DNA, and in one mutant family the unintegrated form of plasmid DNA was identified. Generally, the presence of injected genetic material in fly cells correlated with morphological changes in Drosophila. 相似文献
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Involvement of Notch and Delta genes in spider segmentation 总被引:6,自引:0,他引:6
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Wolbachia在Drosophila auraria复合种和Drosophila simulans中的感染 总被引:2,自引:0,他引:2
用 P C R 方法检测了多种果蝇中共生菌 W olbachia 的感染,发现 Drosophila auraria 复合种以及采集于北京地区的 Drosophila sim ulans为 Wolbachia 所感染, R F L P分析证实为单一感染.克隆了编码 W olbachia 外膜蛋白质的 w sp 基因并进行了序列测定.同时比较了 Drosophila auraria 复合种内 4 个种和采集于北京及美国加州的 Drosophila sim ulans 的线粒体的细胞色素氧化酶 2 亚基基因的部分序列. 进而讨论了 Wolbachia 对 Drosophila auraria 复合种成员之间进化关系的影响. 相似文献
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爆炸载荷作用下刻槽炮孔动态裂纹扩展规律 总被引:5,自引:0,他引:5
基于准静态爆生气体膨胀和岩石断裂力学理论,建立了不耦合装药刻槽爆破时的脆性断裂爆破模型。对刻槽炮孔内爆生气体压力、临界压力和应力强度因子进行了分析计算,从而得出了刻槽炮孔裂缝在扩展过程中,包括启裂、止裂条件、启裂方向、扩展长度和裂缝扩展速度等的变化规律。此外,论文还对刻槽爆破时的动态效应进行了初步探讨,根据分析结果在大理石切割爆破中进行了刻槽试验,并和普通光面爆破效果进行了比较。 相似文献
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Androutsellis-Theotokis A Leker RR Soldner F Hoeppner DJ Ravin R Poser SW Rueger MA Bae SK Kittappa R McKay RD 《Nature》2006,442(7104):823-826
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Many species of the fruitfly Drosophila are either sexually dimorphic for abdominal pigmentation (the posterior segments in males are black and those of females have thin dark stripes) or sexually monomorphic for this pigmentation (both sexes show striping). Kopp et al. report a correlation in two Drosophila clades between the expression of the bric-à-brac (bab) gene, which represses male-specific pigmentation in D. melanogaster females, and the presence of sexually dimorphic pigmentation. They suggest that sexual selection acted to produce sexual dichromatism in Drosophila by altering the regulation of bab, on the grounds that D. melanogaster males show a strong mate preference for females with lightly pigmented abdomens, and that this discrimination helps to maintain sexual dichromatism by preventing males from wasting time by courting other (darkly pigmented) males. Here we show that the mate discrimination observed by Kopp et al. may in fact have resulted from the nature of the strains and comparisons they used in their study and so could be irrelevant to mate choice in nature. 相似文献
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文章采用不同浓度的甘露醇模拟干旱胁迫,以发芽率为筛选指标在拟南芥突变体库中筛选抗旱突变体,筛选出2株候选突变体,最终得到1株稳定突变体vem1,通过表型和生理生化鉴定,确定为抗旱突变体。该研究为抗旱基因克隆及功能分析奠定基础,对于揭示植物抗旱的分子机理具有重要的理论意义。 相似文献
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拟南芥耐硒突变体的筛选和鉴定 总被引:1,自引:0,他引:1
文章采用不同质量浓度的亚硒酸钠(Na2SeO3)对拟南芥突变体库中的2121株拟南芥进行筛选,筛选出29株候选突变体,最终得到2株稳定突变体vsel1和vse2,通过表型鉴定和生理生化鉴定确定是突变体.该研究为耐硒基因克隆及功能分析奠定了基础,对于揭示植物耐硒的分子机理具有重要的理论意义. 相似文献
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Reverberation is significant in shallow water and produces obvious notches in OBC spec-tra. It also degrades the quality of sections and increases the difficulty of processing and interpretation. This ... 相似文献