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排序方式: 共有92条查询结果,搜索用时 78 毫秒
1.
Hafezparast M Klocke R Ruhrberg C Marquardt A Ahmad-Annuar A Bowen S Lalli G Witherden AS Hummerich H Nicholson S Morgan PJ Oozageer R Priestley JV Averill S King VR Ball S Peters J Toda T Yamamoto A Hiraoka Y Augustin M Korthaus D Wattler S Wabnitz P Dickneite C Lampel S Boehme F Peraus G Popp A Rudelius M Schlegel J Fuchs H Hrabe de Angelis M Schiavo G Shima DT Russ AP Stumm G Martin JE Fisher EM 《Science (New York, N.Y.)》2003,300(5620):808-812
Degenerative disorders of motor neurons include a range of progressive fatal diseases such as amyotrophic lateral sclerosis (ALS), spinal-bulbar muscular atrophy (SBMA), and spinal muscular atrophy (SMA). Although the causative genetic alterations are known for some cases, the molecular basis of many SMA and SBMA-like syndromes and most ALS cases is unknown. Here we show that missense point mutations in the cytoplasmic dynein heavy chain result in progressive motor neuron degeneration in heterozygous mice, and in homozygotes this is accompanied by the formation of Lewy-like inclusion bodies, thus resembling key features of human pathology. These mutations exclusively perturb neuron-specific functions of dynein. 相似文献
2.
Bats of the family Vespertilionidae enmit strong ultrasonic pulses for echolocation. If such sounds directly stimulate their ears, the detection of echoes from short distances would be impaired. The responses of lateral lemniscal neurons to emitted sounds were found to be much smaller than those to playback sounds, even when the response of the auditory nerve was the same to both types of sounds. Thus, responses to self-vocalized sounds were attenuated between the cochlear nerve and the inferior colliculus. The mean attenuation was 25 decibels. This neural attenuating mechanism is probably a part of the mechanisms for effective echo detection. 相似文献
3.
Rolf Schlegel 《Genetic Resources and Crop Evolution》1990,38(1):67-78
Zusammenfassung Basierend auf experimentellen Ergebnissen wird demonstriert, daß chromosomale Manipulationen effektiv zur gezielten Übertragung von Fremdgenen in den hexaploiden Weizen genutzt werden können und zu züchterisch bzw. agronomisch verwertbaren Produkten führten. Die Stabilität der Integration von Chromosomen oder Chromosomensegmenten und die Expression der übertragenen Gene hängt von einer Vielzahl von cytologischen und genetischen Faktoren ab. Homöologe Austauschereignisse erweisen sich als besonders geeignet, obwohl auch nichthomöologe Substitutionen und Translokationen toleriert sowie beständig vererbt werden können. Die Vorteile unterschiedlicher Transferverfahren und die dabei auftretenden Probleme werden diskutiert.
The efficiency and stability of interspecific chromosome and gene transfer in hexaploid wheat,Triticum aestivum L.
Summary The transfer of alien chromosomes and genes into wheat can be efficiently achieved by cytogenetic manipulations. They contributed to several substitution and translocation lines with improved resistance against diseases and abiotic stress, which are utilized in breeding programs. The stability of the insertion of alien chromosomes/segments and the expression of the alien genes is depending on numerous cytological and genetical factors. When an alien segment is transferred, the natural organisation of the genes is usually maintained intact. The genes not only can compensate for most of the replaced wheat genes, but they also interact well with their neighbouring recipient genes. Although nonhomoeologous recombinations occured, the homoeologous exchanges are the most dominating. If dosage effects are desired, the target segment can be introduced to additional homoeologous chromosomes. The advantages of different procedures of transfer and their limitations are discussed.
,Triticum aestivum L.
, . . , (). .相似文献
4.
Hydrogen peroxide induced oxidative stress damage and antioxidant enzyme response in Caco-2 human colon cells 总被引:1,自引:0,他引:1
Wijeratne SS Cuppett SL Schlegel V 《Journal of agricultural and food chemistry》2005,53(22):8768-8774
Studies were conducted to evaluate the cell damage caused by exposing human colon carcinoma cells, Caco-2, to hydrogen peroxide at concentrations varying from 0 to 250 microM for 30 min. Evaluation of cell viability, as measured by trypan blue dye exclusion test, showed that the loss of viability was < 5% at concentrations up to 250 microM hydrogen peroxide. Cell membrane damage and DNA damage as measured by the leakage of lactate dehydrogenase and the comet assay, respectively, were significantly high at concentrations >100 microM hydrogen peroxide compared to those of the control. Antioxidant mechanisms in Caco-2 cells were evaluated by measuring catalase, superoxide dismutase, and glutathione peroxidase activities. Catalase activities remained constant in cells treated with 50-250 microM hydrogen peroxide. Superoxide dismutase activity decreased, whereas glutathione peroxidase activity increased in cells treated with H(2)O(2) concentrations of >50 microM. This study showed that with increasing hydrogen peroxide concentration, cell membrane leakage and DNA damage increased, whereas the three antioxidant enzymes responded differently, as shown by mathematical models. 相似文献
5.
Summary Hexaploid wheat varieties are often differentiated by reciprocal translocations. The chromosomes involved are frequently identified after crossing and F1 analysis. The hybrids show in meiosis multivalent configurations of 14, 24, 34, 16, 18, 14+16, and 24+16 with different frequencies. For several studies the knowledge about interchanges is required. Therefore, a list was compiled summarizing available data from 270 wheat combinations on the presence and number of translocations, on configurations observed and on chromosomes involved.
Ein Kompendium reziproker Translokationen beim hexploiden Weizen
Zusammenfassung Sorten und Linien des hexaploiden Weizens unterscheiden sich sehr häufig durch die Präsenz reziproker chromosomaler Translokationen. Sie können in F1-Hybriden durch die Bildung von multivalenten Chromosomenkonfigurationen identifiziert werden. Unter etwa 270 analysierten Kombinationen wurden Assoziationen von 14, 24, 34, 16, 18, 14+16 und 24+16 mit unterschiedlichen Frequenzen beobachtet. Für verschiedenartige genetische und cytogenetische Experimente ist die Kenntnis über das Vorkommen derartiger Strukturaberrationen erforderlich. Es wurde daher eine Liste verfügbarer Literaturdaten zusammengestellt, die die karyologischen Befunde die Sortenangaben und deren Herkunft sowie die in die Translokation involvierten Chromosomen bzw. Chromosomenarme beinhaltet. Die Ergebnisse werden diskutiert.
. . 270 14, 24, 34, 16, 18, 16+14 24+16 . ¶rt; . , , , , . .相似文献
6.
Using young fruits or fruit segments, rates of penetration of 45CaCl2 across apple fruit cuticles (Malus x domestica) were studied during fruit development in two consecutive years (’?Golden Delicious’ in 2000, ’?Cox Orange Pippin’ and ’?Boskoop’ in 2001). The aqueous donor solutions contained 5 g l—1 CaCl2 and 0.2 g l—1 Glucopon 215 CSUP as wetter. A droplet (5 μl) was applied to each fruit disc and allowed to dry within 1 h. Amounts penetrated were estimated immediately after droplet drying (0 h) and after 6 and 24 h penetration, respectively. Temperature during penetration was 20 ?C and 100 % humidity was maintained throughout the experiment, once the droplet had dried. Rates of penetration were greatly affected by the stage of fruit development. With all varieties tested, highest rates were measured during the early stages of fruit development (before June drop) when approx. 100 % of the CaCl2 applied penetrated within 24 h. After June drop, when trichomes had vanished and most stomata developed into lenticels, penetration rates decreased rapidly and large variability among the samples developed. This pattern was similar with all three varieties. The involvement of trichomes, stomata, and lenticels as preferential sites of penetration of calcium chloride across the apple fruit cuticles is discussed. Using a model calculation, it is argued that ten or more spray applications are needed to significantly increase calcium contents of apples. This has two causes: Only a small fraction of the spray liquid is intercepted by the fruits, and penetration can be rather slow. 相似文献
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