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151.
152.
A diverse array of wild and weedy crucifers was screened under laboratory conditions for their resistance to Lipaphis erysimi (Kaltenbach) (Homoptera: Aphididae). Among these, Brassica fruticulosa and Brassica montana were found to be the most promising. The availability of a synthetic amphiploid, AD-4(B. fruticulosa × Brassica rapa var. brown sarson) as well as a set of Brassica juncea lines carrying genomic introgressions from B. fruticulosa allowed us to investigate B. fruticulosa resistance in greater detail. This assessment was carried out along with susceptible check B. rapa ssp. brown sarson cv. BSH-1 in a series of choice and no choice experiments. The mustard aphid showed maximum preference
for feeding on BSH-1 while least preference was recorded for B. fruticulosa followed by AD-4 as evidenced by the number of aphids that settled on circular leaf bits of these genotypes 24 and 48 h after
release in a choice experiment. Brassica fruticulosa exhibited strong antibiosis against mustard aphid in no choice experiment and all the released aphids died within 5–8 days
of their release, while the maximum survival (76.7%) was recorded on BSH-1. The survival on AD-4 (40%) was significantly lower
than that on BSH-1. Almost similar trend was observed with respect to other demographic parameters of L. erysimi viz. development time, fecundity and longevity. In the screen house studies, there was no seedling mortality in B. fruticulosa and AD-4 after 30 days of aphid release while 80% mortality was observed on BSH-1. Excellent variation for aphid resistance
was recorded in B. juncea introgression lines, emphasizing heritable nature of fruticulosa resistance. The biochemical analysis suggested the possibility of high concentration of lectins to be associated with low
aphid infestation in B. fruticulosa. 相似文献
153.
Mahipal S. Shekhawat Narpat S. Shekhawat Harish Kheta Ram Mahendra Phulwaria Amit Kumar Gupta 《Journal of Crop Science and Biotechnology》2011,14(2):133-137
An in vitro propagation method for female plants of Momordica dioica (Roxb.) has been established. The nodal segments were harvested and the cut ends of the explants were sealed with wax and
then surface sterilized and cultured. Bud breaking occurred on Murashige and Skoog’s (MS) agar-gelled medium + 2.0 mg L−1 6-Benzylaminopurine (BAP) + 0.1 mg L−1 Indole-3 acetic acid (IAA). The cultures were amplified by passages on MS medium supplemented with 1.0 mg L−1 BAP + 0.1 mg L−1 IAA. Further, shoot amplification (29.2 shoots per vessel) was achieved by subculturing of in vitro regenerated shoot clump on MS medium + 0.5 mg L−1 BAP + 0.1 mg L−1 IAA. The micropropagated shoots were subsequently transferred for root formation on half-strength MS medium + 2.0 mg L−1 Indole-3 butyric acid (IBA) with 89% success rate. The in vitro-regenerated shoots were also rooted ex vitro with 34% success. These plantlets were hardened in the greenhouse and transferred to the field. The established protocol
is suitable for true to type cloning of mature female plant of M. dioica. 相似文献
154.
Protection against malaria by vaccination with sporozoite surface protein 2 plus CS protein. 总被引:23,自引:0,他引:23
S Khusmith Y Charoenvit S Kumar M Sedegah R L Beaudoin S L Hoffman 《Science (New York, N.Y.)》1991,252(5006):715-718
The circumsporozoite (CS) protein has been the target for development of malaria sporozoite vaccines for a decade. However, immunization with subunit vaccines based on the CS protein has never given the complete protection found after immunization with irradiated sporozoites. BALB/c mice immunized with irradiated Plasmodium yoelii sporozoites produced antibodies and cytotoxic T cells against a 140-kilodalton protein, sporozoite surface protein 2 (SSP2). Mice immunized with P815 cells that had been transfected with either SSP2 or CS genes were partially protected, and those immunized with a mixture of SSP2 and CS transfectants were completely protected against malaria. These studies emphasize the importance of vaccine delivery systems in achieving protection and define a multi-antigen sporozoite vaccine. 相似文献
155.
Activation of ras oncogenes preceding the onset of neoplasia 总被引:24,自引:0,他引:24
The identification of ras oncogenes in human and animal cancers including precancerous lesions indicates that these genes participate in the early stages of neoplastic development. Yet, these observations do not define the timing of ras oncogene activation in the multistep process of carcinogenesis. To ascertain the timing of ras oncogene activation, an animal model system was devised that involves the induction of mammary carcinomas in rats exposed at birth to the carcinogen nitrosomethylurea. High-resolution restriction fragment length polymorphism analysis of polymerase chain reaction-amplified ras sequences revealed the presence of both H-ras and K-ras oncogenes in normal mammary glands 2 weeks after carcinogen treatment and at least 2 months before the onset of neoplasia. These ras oncogenes can remain latent within the mammary gland until exposure to estrogens, demonstrating that activation of ras oncogenes can precede the onset of neoplasia and suggesting that normal physiological proliferative processes such as estrogen-induced mammary gland development may lead to neoplasia if the targeted cells harbor latent ras oncogenes. 相似文献
156.
Falkner-Skan方程描述磁场中连续平直面上不可压缩粘性流的边界层流,本文研究此方程初值问题之解的渐近性质。 相似文献
157.
158.
Gap junction membrane channels mediate electrical and metabolic coupling between adjacent cells. The structure of a recombinant cardiac gap junction channel was determined by electron crystallography at resolutions of 7.5 angstroms in the membrane plane and 21 angstroms in the vertical direction. The dodecameric channel was formed by the end-to-end docking of two hexamers, each of which displayed 24 rods of density in the membrane interior, which is consistent with an alpha-helical conformation for the four transmembrane domains of each connexin subunit. The transmembrane alpha-helical rods contrasted with the double-layered appearance of the extracellular domains. Although not indicative for a particular type of secondary structure, the protein density that formed the extracellular vestibule provided a tight seal to exclude the exchange of substances with the extracellular milieu. 相似文献
159.
Zhou D Cantu C Sagiv Y Schrantz N Kulkarni AB Qi X Mahuran DJ Morales CR Grabowski GA Benlagha K Savage P Bendelac A Teyton L 《Science (New York, N.Y.)》2004,303(5657):523-527
It is now established that CD1 molecules present lipid antigens to T cells, although it is not clear how the exchange of lipids between membrane compartments and the CD1 binding groove is assisted. We report that mice deficient in prosaposin, the precursor to a family of endosomal lipid transfer proteins (LTP), exhibit specific defects in CD1d-mediated antigen presentation and lack Valpha14 NKT cells. In vitro, saposins extracted monomeric lipids from membranes and from CD1, thereby promoting the loading as well as the editing of lipids on CD1. Transient complexes between CD1, lipid, and LTP suggested a "tug-of-war" model in which lipid exchange between CD1 and LTP is on the basis of their respective affinities for lipids. LTPs constitute a previously unknown link between lipid metabolism and immunity and are likely to exert a profound influence on the repertoire of self, tumor, and microbial lipid antigens. 相似文献
160.
The trace water content of salt in six Louisiana salt domes has been determined and has been found to be the lowest of any terrestrial rock type. The average water content of normal domal salt is on the order of 0.003 percent by weight, but anomalous zones within salt stocks can have more than ten times this amount. From the average value, the minimum amount of water in liters, W, available to collect around a radioactive waste repository is given as W = 0.28 r(3), where r is the radius in meters of the sphere in which water may be thermally activated to migrate completely to the repository. 相似文献