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1.
Superfluids such as helium II consist of two interpenetrating fluids: the normal fluid and the superfluid. The helium II vortex ring has generally been considered merely as a superfluid object, neglecting any associated motion of the normal fluid. We report a three-dimensional calculation of the coupled motion of the normal-fluid and superfluid components, which shows that the helium II vortex ring consists of a superfluid vortex ring accompanied by two coaxial normal-fluid vortex rings of opposite polarity. The three vortex rings form a coherent, dissipative structure. 相似文献
2.
Edna Sharon Ilan Chet Ada Viterbo Meira Bar-Eyal Harel Nagan Gary J. Samuels Yitzhak Spiegel 《European journal of plant pathology / European Foundation for Plant Pathology》2007,118(3):247-258
Trichoderma (T.
asperellum-203, 44 and GH11; T. atroviride-IMI 206040 and T. harzianum-248) parasitism on Meloidogyne javanica life stages was examined in vitro. Conidium attachment and parasitism differed beween the fungi. Egg masses, their derived
eggs and second-stage juveniles (J2) were parasitized by Trichoderma
asperellum-203, 44, and T. atroviride following conidium attachment. Trichoderma
asperellum-GH11 attached to the nematodes but exhibited reduced penetration, whereas growth of T. harzianum-248 attached to egg masses was inhibited. Only a few conidia of the different fungi were attached to eggs and J2s without
gelatinous matrix; the eggs were penetrated and parasitized by few hyphae, while J2s were rarely parasitized by the fungi.
The gelatinous matrix specifically induced J2 immobilization by T.
asperellum-203, 44 and T. atroviride metabolites that immobilized the J2s. A constitutive-GFP-expressing T. asperellum-203 construct was used to visualize fungal penetration of the nematodes. Scanning electron microscopy revealed the formation
of coiling and appressorium-like structures upon attachment and parasitism by T. asperellum-203 and T. atroviride. Gelatinous matrix agglutinated T. asperellum-203 and T. atroviride conidia, a process that was Ca2+-dependent. Conidium agglutination was inhibited by carbohydrates, including fucose, as was conidium attachment to the nematodes.
All but T. harzianum could grow on the gelatinous matrix, which enhanced conidium germination. A biomimetic system based on gelatinous-matrix-coated
nylon fibers demonstrated the role of the matrix in parasitism: T. asperellum-203 and T. atroviride conidia attached specifically to the gelatinous-matrix-coated fibers and parasitic growth patterns, such as coiling, branching
and appressoria-like structures, were induced in both fungi, similarly to those observed during nematode parasitism. All Trichoderma isolates exhibited nematode biocontrol activity in pot experiments with tomato plants. Parasitic interactions were demonstrated
in planta: females and egg masses dissected from tomato roots grown in T. asperellum-203-treated soil were examined and found to be parasitized by the fungus. This study demonstrates biocontrol activities of
Trichoderma isolates and their parasitic capabilities on M. javanica, elucidating the importance of the gelatinous matrix in the fungal parasitism. 相似文献
3.
工能基因组学:T-DNA介导的基因诱捕和植物基因鉴定(英文) 总被引:2,自引:0,他引:2
拟南芥菜、水稻、蕃茄、土豆、玉米、小麦和大豆的全基因组测序为植物细胞和发育生 物学研究提供了许多有用的信息。基因组学的中心任务是利用这些信息去探索蛋白质的功能 和鉴定与发育有关的重要基因。尽管依赖于毁坏基因和产生可识别的突变表型的经典遗传学 方法仍然是极为成功的基因鉴定方法,借助于报告基因结构,随机插入植物基因组的T-DNA 介导的基因诱捕正发展成为植物细胞和发育生物学研究的极强有力的技术。本文描述了基因 诱捕、启动子诱捕和增强子诱捕在植物生物学中的应用,并且希望这些基因鉴定方法有助于 植物分子生物学家和生物技术工作者的研究。 相似文献
4.
Preparation on the basis of Trichoderma asperellum in the system of biological protection of wheat from Fusarium ear scab 下载免费PDF全文
During the last century, as the area of wheat grown under advanced grain husbandry has increased worldwide, so too has the importance of Fusarium ear scab (FES) (synonym, Fusarium head blight) caused by several species of the fungus Fusarium. Yield losses due to FES can total 20%-40% and more depending on climatic conditions. During the last twenty years epidemics of FES in cereals have become chronic all over the world, including the United States and Russia. The most destructive of t… 相似文献
5.
L S Freedman S Samuels I Fish S A Schwartz B Lange M Katz L Morgano 《Science (New York, N.Y.)》1980,207(4433):902-904
Rates of tyrosine and lysine transport and incorporation into protein were measured in control and undernourished weanling rats. Undernutrition was induced by feeding lactating dams a low protein diet (12 percent casein) from birth to day 21. At weaning, body and brain weights of undernourished rats were 50 percent and 88 percent, respectively, of control values. Lysine and tyrosine transport rates into skeletal muscle were reduced by over 75 percent, more than twice the reduction seen in brain. Rates of amino acid incorporation into muscle protein were reduced by approximately 50 percent; the change in rate of incorporation into brain protein was not statistically significant. These data indicate that, in spite of marked retardation of amino acid transport into brain, the brain seems fully capable of maintaining normal rates of protein synthesis. 相似文献
6.
7.
Sparrow AH 《Science (New York, N.Y.)》1973,181(4101):700-701
8.
Solomon DA Kim T Diaz-Martinez LA Fair J Elkahloun AG Harris BT Toretsky JA Rosenberg SA Shukla N Ladanyi M Samuels Y James CD Yu H Kim JS Waldman T 《Science (New York, N.Y.)》2011,333(6045):1039-1043
Most cancer cells are characterized by aneuploidy, an abnormal number of chromosomes. We have identified a clue to the mechanistic origins of aneuploidy through integrative genomic analyses of human tumors. A diverse range of tumor types were found to harbor deletions or inactivating mutations of STAG2, a gene encoding a subunit of the cohesin complex, which regulates the separation of sister chromatids during cell division. Because STAG2 is on the X chromosome, its inactivation requires only a single mutational event. Studying a near-diploid human cell line with a stable karyotype, we found that targeted inactivation of STAG2 led to chromatid cohesion defects and aneuploidy, whereas in two aneuploid human glioblastoma cell lines, targeted correction of the endogenous mutant alleles of STAG2 led to enhanced chromosomal stability. Thus, genetic disruption of cohesin is a cause of aneuploidy in human cancer. 相似文献
9.
A knowledge of the nutrient dynamics that occur with land use changes, e.g., in clearing forests for farmland, is useful in choosing the most efficient soil and fertilizer management practices. To determine net in situ P and N mineralization and nitrification rates of forest floor materials and their nutrient value for agricultural crops, plastic bags containing different materials (moss, O horizon, and A horizon) collected from a subarctic black spruce (Picea mariana Mill.) forest were incubated for 2 years in their respective forest horizons and at 7.5 cm depth in a nearby fallow field. Net amounts of P and N mineralized were highest in moss and were similar in forest and field when the temperature and moisture content were similar, but smaller in forest when the water content was higher. Net nitrification was negligible in O and A horizon material but significant in moss during the 2nd year, occurring sooner and producing higher NO
inf3
sup-
levels in the field (171 mg ha-1) than in the forest (13 mg ha-1). Moss P and N mineralization rates were correlated in the fallow field. Temperature, moisture content, and substrate quality were important factors controlling P and N dynamics of forest floor materials in a subarctic fallow field and native forest. In subarctic regions, incorporation and mineralization of forest floor materials could provide an early source of N and P (70 and 17 kg ha-1, respectively) for succeeding agricultural crops. 相似文献
10.