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Larval RNAi in Drosophila? 总被引:2,自引:0,他引:2
RNA interference (RNAi) has become a common method of gene knockdown in many model systems. To trigger an RNAi response, double-stranded RNA (dsRNA) must enter the cell. In some organisms such as Caenorhabditis elegans, cells can take up dsRNA from the extracellular environment via a cellular uptake mechanism termed systemic RNAi. However, in the fruit fly Drosophila melanogaster, it is widely believed that cells are unable to take up dsRNA, although there is little published data to support this claim. In this study, we set out to determine whether this perception has a factual basis. We took advantage of traditional Gal4/upstream activation sequence (UAS) transgenic flies as well as the mosaic analysis with a repressible cell marker (MARCM) system to show that extracellular injection of dsRNA into Drosophila larvae cannot trigger RNAi in most Drosophila tissues (with the exception of hemocytes). Our results show that this is not due to a lack of RNAi machinery in these tissues as overexpression of dsRNA inside the cells using hairpin RNAs efficiently induces an RNAi response in the same tissues. These results suggest that, while most Drosophila tissues indeed lack the ability to uptake dsRNA from the surrounding environment, hemocytes can initiate RNAi in response to extracellular dsRNA. We also examined another insect, the red flour beetle Tribolium castaneum, which has been shown to exhibit a robust systemic RNAi response. We show that virtually all Tribolium tissues can respond to extracellular dsRNA, which is strikingly different from the situation in Drosophila. Our data provide specific information about the tissues amenable to RNAi in two different insects, which may help us understand the molecular basis of systemic RNAi. 相似文献
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Theodosius Dobzhansky 《Chromosoma》1956,8(1):691-698
Summary The crossDrosophila insularis ×Drosophila tropicalis produces viable but completely sterile hybrids. Chromosomes have been studied in the cells of the salivary glands in hybrid larvae. The euchromatic sections of the chromosomes of the two species remain completely unpaired in the hybrid, despite the obvious similarities of the disc patterns in many portions of these chromosomes. A common chromocenter is nevertheless formed, owing to a mutual attraction of the heterochromatic sections adjacent to the centromeres in all the chromosomes. The condition of the chromosomes in the female and male cells is represented schematically in Fig. 1. The X-chromosomes show a remarkable difference in behavior in the cells of the two sexes. The euchromatic strands representing the X-chromosome are appreciably greater in width but somewhat paler in staining in male than in female larvae. This is a visible counterpart of the genetic phenomenon of dosage compensation.The work reported in this article has been supported in part under Contract No. AT-(30-1)-1151, U. S. Atomic Energy Commission 相似文献
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果蝇immigrans种组中的curviceps种亚组是1992年新建立的中国特有果蝇类群。该种亚组中的物种主要分布在中国大陆和台湾。目前除了形态学水平的研究外,还没有其他证据支持建立该种亚组的合理性及其起源和种系发生地位。为了在DNA分子水平上探讨果蝇curviceps种亚组在果蝇immigrans种组中的种系发生地位,从而为今后更深入地研究中国特有果蝇,甚至为果蝇亚属的进化遗传学提供理论依据,测定了immigrans种组5个种亚组(nasuta、immigrans、hypocausta、quadrilineata、curviceps)中12个代表物种的rDNA的ITS1和部分Adh基因的序列。其中ITS1序列的长度为513-587bp,共有191个信息位点;Adh基因片段的长度在714-747bp之间,共99个信息位点。考虑到单个分子提供的信息较少,将两个分子的序列综合起来,组成一个较长的复合序列。分别根据ITS1,Adh和两个分子的复合序列排比(Alignment)结果,和最大简约法和邻接法构建分子系统树,其中根据复合序列构建的系统树与形态学研究结果最为一致。分子树显示curviceps种亚组的特种确定单独形成一个分枝,为种亚组级的分类阶元,支持了形态学将其建立为一个新种亚组。根据Kimura距离,估算了复合分子的替换速率约为每百万年1.48%,进而计算出5个种亚组的分 歧年代。结合各物种的地理分布,推测了immigrans种组的进化历史:curviceps种亚组与quadrilineata种亚组的亲缘关系最近,主要分布在中国南部的温带地区。它们之间的分歧时间大约为3.4百万年,是最年轻的两个种亚组。主要分布在苏门答腊及附近的热带地区的hypocausta种亚组的物种是最早分化出来的,与其他种亚组的分歧时间约为9.2百万年。该结果与形态学和生物地理学研究相吻合。值得一提是的,目前归属仍存在争议的物种D.neohypocausta,在分子系统树中与hypocausta种亚组的物种相距较远,而与immiagrasn种亚组的关系较近,但分枝置信度较低(<50%)。由于还缺乏其他方面的证据,因此D.neohypocausta的归属有待今后的研究来作定论。 相似文献
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J. I. Izquierdo 《Entomologia Experimentalis et Applicata》1991,59(1):51-58
In temperate regions low temperatures seem to be the most restrictive factor for survival of Drosophila natural populations, which depends on the capacity of one or more developmental stages to resist unfavourable winter conditions. In this study we have attempted to answer the question of how D. melanogaster overwinters under natural temperature conditions. Only adults overwintered and no diapause was observed in any developmental stage. Thus, developmental duration becomes a decisive component with respect to overwintering potential and, therefore, the preadult stages are unlikely to overwinter. Possible evolutionary steps in adaptation to cold regions are discussed. 相似文献
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Tina Dancau Tanya L. M. Stemberger Peggy Clarke David R. Gillespie 《Biocontrol Science and Technology》2017,27(1):3-16
Drosophila suzukii and Drosophila melanogaster coexist with different but overlapping resource use in the field. When forced to completely or partially share resources in the laboratory, D. melanogaster outcompetes D. suzukii. Adult D. suzukii and D. melanogaster females were allowed to compete for access to a common oviposition resource in pairwise and population scale experiments. We tracked the offspring emergence to explore the factors across life stages that might affect the success of D. suzukii in the laboratory compared to a closed field simulation cage experiment with a generalist Drosophila parasitoid, Pachycrepoideous vindemmiae. When in competition as adults, D. melanogaster produced more offspring that survived to pupation than D. suzukii. In addition, D. melanogaster produced more offspring when in competition with a conspecific than when in competition with D. suzukii. Competitor identity did not affect the number of D. melanogaster offspring in pairwise and cage experiments. However, in the presence of D. melanogaster, the number of D. suzukii offspring in both pairwise and cage experiments was dramatically reduced than in cages without this competitor. In the presence of both D. melanogaster and P. vindemmiae, there were marginally more D. suzukii than when only D. melanogaster was present. These results suggest that competition was an important factor limiting D. suzukii numbers. Limiting D. suzukii numbers through interspecies competition may eventually be an exploitable method of biocontrol in the field. 相似文献
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《Fly》2013,7(4):238-241
The sensation of touch, gravity, and sound all rely on dedicated ion channels that transduce mechanical stimulus forces into electrical response signals. The functional workings and molecular identities of these mechanotransducer channels are little understood. Recent work shows that the mechanotransducers for fly and vertebrate hearing share equivalent gating mechanisms, whereby this mechanism can be probed non-invasively in the mechanics of the Drosophila ear. Here, we describe how this mechanics can be used to evaluate the roles of identified proteins in the process of mechanosensation and, specifically, their contributions to mechanotransduction. 相似文献
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Dopamine-containing neurons are widespread in the fly brain and have been implicated in negatively reinforced memory. Current technology allows the investigator to watch dopaminergic neurons in action in the brain of a learning fly. 相似文献
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K. Hagele 《Chromosoma》1973,41(2):231-236
In D. melanogaster salivary gland chromosomes continuous and discontinuous labeling patterns have been described. Arcos-Terán (1972) has devided those of the X-chromosome in into a 6 class sequence beginning with continuous labeling and ending with labeling restricted to a few heavy bands. Labeling patterns reverse to the described ones have not been reported. — In the present communication new types of discontinuous labeling patterns are described for the X of melanogaster females. One type shows unlabeling of the majority of heavy bands and of the chromocenter whereas interbands and faint bands are labeled. In other types the number of unlabeled heavy bands is decreased and the chromosome is nearly totally labeled. These new labeling patterns are the reverse of Arcos-Terán's patterns II, IV, and V. It must therefore be assumed that the continuous pattern of labeling corresponds to the (early) middle of the replication cycle and that replication in melanogaster females starts with the labeling patterns described here. 相似文献
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Agaisse H 《Cell host & microbe》2007,1(2):91-93
The ability to mount an adaptive immune response is thought to be an attribute restricted to vertebrates. A new study conducted in Drosophila demonstrates that invertebrate immunity can adapt to an immune challenge and mount a specific immune response. 相似文献
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P. S. Ruban E. P. Cunningham P. M. Sharp 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1988,76(1):136-142
Summary The relationship between heterozygosity and the expression of heterosis at two different nutrition levels was investigated using Drosophila melanogaster. Average daily egg production and egg hatchability were measured in two parental strains and in F1, F2 and reciprocal backcross generations. Heterosis was more pronounced in the poor nutritional conditions. Two electrophoretic markers used to estimate the level of heterozygosity in F2 and backcrosses revealed an excess of heterozygous genotypes. Quantitative genetic effects (an additive line effect and individual and maternal heterosis) were estimated for both traits in the two environments. Although this model gave a reasonable fit in most cases, some epistatic interaction would have to be invoked in order to explain fully the results. 相似文献
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《Current biology : CB》2001,11(22):1788-1793
To assess the role of γ-tubulin in spindle assembly in vivo, we have followed meiosis progression by immunofluorescence and time-lapse video microscopy in γTub23CPI mutant spermatocytes. We have found that centrosomes associate with large numbers of astral microtubules even though γ-tubulin is severely depleted; bipolar meiotic spindles are never assembled; and later in meiosis, the microtubules get organized into a conical structure that is never observed in wild-type cells. Several lines of evidence suggest that these cones may be related to wild-type central spindles. First, they are assembled midway through meiosis and elongate during anaphase. Second, they are constricted during late meiosis, giving rise to a pointed end similar to those that form in each half of the wild-type spindle midzone. Third, Klp3A and Polo, two markers of the wild-type central spindle are also found around the pointed end of the mutant cones. Finally, ectopic cytokinesis furrows are often formed at the distal end of the cone. Our results suggest that microtubule polymerization or stabilization from the centrosome may be possible in a γ-tubulin-independent manner in Drosophila spermatocytes. However, γ-tubulin seems to be essential for spindle assembly in these cells. Finally, our results show that at least part of the central spindle and constriction-ring assembly machinery can operate on microtubule bundles that are not organized as bipolar spindles. 相似文献
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Thermal stability of -glycerophosphate dehydrogenase-1 (-Gpdh-1) in nine Drosophila species was studied at pH's ranging from 6.4 to 8.5. This was done by measuring the changes in the activity of enzymes during the heat denaturation process. In addition to temperature, the rate of denaturation is highly dependent on the pH of the incubation buffer. The results of this study show that the thermal stability of enzyme molecules is different in different species. This holds true also in the species in which the enzymes have been found to be identical by other means. The differences between species of the Drosophila virilis group are discussed.This study was supported by funds from the National Research Council of Sciences of Finland. 相似文献
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Dr. Karl Georg Götz 《Biological cybernetics》1965,2(5):215-221
Summary The transfer properties of the optical system in the arthropod compound eye are determined by the interommatidial angle , influencing the resolving power, and by the width of the visual fields of single ommatidia , influencing the response at high spatial frequencies of brightness distributions in the object space. The energy transfer/ receptor is proportional to ( )2 and decreases with in-inreasing approximation of the perfect-imaging condition: gD 0; 0. However, a value > 0 has to be maintained in order to overcome the threshold of nervous excitation at a certain minimum-brightness level. Theoretical treatment yields /=0.62 to 0.88 as the corresponding optimum-imaging relation. The actual ratio can be derived from measurements of the optomotor reactions to the movement of periodic brightness patterns. The approximate value 0.76 is obtained from the fruitfly Drosophila with normal and mutant eye pigmentation. As a result, the parameters of this imaging system are found to be established in a way that enables optimum performance at sufficient illumination. An dieser Stelle möchte ich Dr. W. Reichardt für sein eingehendes Interesse und manche anregende Diskussion über die Sehvorgänge im Komplexauge meinen Dank sagen. Dr. K. Kirschfeld verdanke ich ebenfalls wertvolle Hinweise. Herrn E. Freiberg bin ich für die Anfertigung der Abbildungen sehr verbunden. 相似文献