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31.
32.
Valerie Munt 《Anthropological Forum》2011,21(2):109-129
It is more than half a century since Frederick G. G. Rose (1915–1991) published his classic text, The classification of kin, age structure and marriage amongst the Groote Eylandt Aborigines: A study in method and a theory of kinship (1960) in the former German Democratic Republic. Although the fieldwork for his thesis had been carried out in Australia on Groote Eylandt in 1938 and 1941, a conservative academic establishment and the political climate of the Cold War postponed its publication until 1960. Why were Rose's fieldwork findings suppressed by the powerful gate-keeper of Australian anthropology, Professor Adolphus Peter Elkin (1891–1979)? Moreover, why was Rose later denied a government permit to revisit Groote Eylandt and Central Australia to further his research? This paper examines the early work of the communist anthropologist, Frederick Rose, within the broad context of Western post-war anthropological developments, an expanding capitalist economy and the political tensions of the Cold War era. As a communist and public servant from 1938 to 1954, Rose was forced, after the Petrov Royal Commission cast him under a cloud of suspicion, to seek institutional support for his academic career in the German Democratic Republic. 相似文献
33.
M. Chabannes G. Hatt G. Thébaud I.D. Bedford & C. Lamb 《The Annals of applied biology》2009,155(2):293-296
Mechanisms underlying natural plant resistance to herbivorous invertebrates are still poorly understood in comparison with bacterial or fungal interactions. One reason is the difficulty in reliably and reproducibly assessing the effects under controlled conditions. This article describes a newly developed in vitro biological assay system that enables the interactions between sciarid larvae and plants, whose roots they feed on, to be studied under highly controlled conditions. The bioassay eliminates the problems created by the often variable environmental factors by providing an aseptic arena where experimental plants can be germinated and grown on agar within a Petri dish. Sciarid fly eggs are then collected, sterilised and added to the Petri dish. The system allows the eggs to hatch and the larvae to feed on the plant roots. A range of developmental parameters can then be recorded over time which can then be correlated with the experimental plant type. This assay system also allows a simultaneous comparison or 'choice chamber' between two (or more) different genotypes. The assay should greatly help to facilitate the identification of new components involved in insect resistance mediated pathway via the characterisation of mutant plants. 相似文献
34.
35.
Richard E. Litz 《Journal of nematology》1986,18(1):18-22
In vitro procedures are playing a major role in plant breeding. Embryo rescue, either through the culture of excised embryos derived from incompatible crosses or by means of ovule culture, has been a standard procedure for the introgression of genes conferring disease resistance into economically important plants. Somatic hybridization (i.e., protoplast fusion) has also been demonstrated to have some potential in obtaining hybrids that result from very wide interspecific and intergeneric crosses. Wide crosses have also been achieved by means of in vitro pollination of excised ovaries or ovules. Tissue culture-induced variability in regenerated plant (i.e., somaclonal variation) appears to be an effective way of obtaining undirected genetic change that can enhance disease resistance and yield and alter the growth habit of crops that are normally propagated vegetatively (e.g., potato) or by seed (e.g., tomato). In the near future, the isolation and sequencing of genes that confer resistance to specific plant pathogens will be possible, and transfer of this information between species will become a reality. 相似文献
36.
EMMA DESPLAND MARIA GUNDERSEN SIMON P. DAOUST BRIAN J. MADER NATHALIE DELVAS PAUL J. ALBERT ERIC BAUCE 《Physiological Entomology》2011,36(1):39-46
The pattern of feeding of Eastern spruce budworm Choristoneura fumiferana (Clem.) (Lepidoptera, Tortricidae) is compared on foliage from white spruce Picea glauca (Moench) Voss. (Pinaceae) trees previously determined to be susceptible and resistant to defoliation by budworm. No differences are observed in electrophysiological responses from taste sensilla to aqueous extracts of the two foliage types, nor is there a preference for either extract type in a choice test. Acetone extracts from the two foliage types are both preferred to a control sucrose solution, although neither elicits a preference relative to the other. These results suggest that there is no difference in phagostimulatory power of internal leaf contents of the two foliage types. Longer‐term observation of feeding behaviour in a no‐choice situation shows no difference in meal duration, confirming the lack of difference in phagostimulatory power. However, on average, intermeal intervals are twice as long on the resistant foliage, leading to an overall lower food consumption during the assay. This result suggests an anti‐digestive or toxic effect of the resistant foliage that slows behaviour and limits food intake. Previous research has shown that waxes of the resistant foliage deter initiation of feeding by the spruce budworm and that this foliage contains higher levels of tannins and monoterpenes. The data suggest that the resistant foliage contains a post‐ingestive second line of defence against the spruce budworm. 相似文献
37.
T. M. Murphy 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1982,61(4):367-372
Summary The organization of plant cells (or any other genetic elements, such as organelles) into aggregates modifies the expected distribution of mutants in clones. The reason for the modification, and its effect on the use of the Luria-Delbrück fluctuation test, are discussed. The Luria-Delbriick test was used to show that the trait for chlorate resistance in cultured rose-cell aggregates appeared spontaneously and in the absence of chlorate ion. 相似文献
38.
Population dynamics, rate of root penetration, and external root feeding behavior of Pratylenchus agilis (Pa) in monoxenic cultures of intact corn seedlings and root explants of corn, tomato, and soybean were studied. In descending order of suitability as hosts were I. O. Chief corn, Rutgers tomato, and Williams soybean. Soybean entries Kent, Pickett 71, PI 90763, and Essex were poor hosts. Numbers of eggs and vermiform Pa in the agar medium indicated total fecundity and host suitability. Agar, sand, or soil as support media did not appear to affect Pa root penetration, but the rate of corn root growth did. Whereas most vermiform Pa and eggs were in roots, substantial numbers appeared able to feed and complete their life cycle as ectoparasites on root epidermal cells and root hairs. 相似文献
39.
ERIK TALLAK NILSEN 《Botanical journal of the Linnean Society. Linnean Society of London》1992,110(3):205-233
Thermonastic leaf movements in Rhododendron L. occur in response to freezing temperatures. These movements are composed of leaf curling and leaf angle changes that are distinct leaf movements with different responses to climatic factors. Leaf angle is controlled by the hydration of the petiole, as affected by soil water content, atmospheric vapour pressure, and air temperature. In contrast, leaf curling is a specific response to leaf temperature, and bulk leaf hydration has little effect. The physiological cause of leaf curling is not well understood, but the mechanism must lie in the physiology of the cell wall and/or regional changes in tissue hydration. Available evidence suggests that intercellular freezing is not a cause of leaf curling.
Manipulation experiments demonstrate that changes in leaf orientation in Rhododendron most likely serve to protect the leaves from membrane damage due to high irradiance and cold temperatures. In particular, the pendent leaves protect the chloroplast from photoinhibition. Leaf curling may serve to slow the rate of thaw following freezing, a common phenomenon in the Appalachian mountains of the U.S. The thermonastic leaf movements have a greater importance to plants in a dim environment because the potential impact to canopy carbon gain is greater than in high light environments.
These leaf movements have several implications for horticultural management. There seems to be a trade-off between water stress tolerance and freezing stress tolerance by leaf movements. Thermonastic leaf movements may be a major mechanism of cold stress tolerance in Rhododendron species. The actual physiological cause of leaf movement has not been elucidated and many more species need to be evaluated to verify the general importance of leaf movements to Rhododendron ecology and evolution. 相似文献
Manipulation experiments demonstrate that changes in leaf orientation in Rhododendron most likely serve to protect the leaves from membrane damage due to high irradiance and cold temperatures. In particular, the pendent leaves protect the chloroplast from photoinhibition. Leaf curling may serve to slow the rate of thaw following freezing, a common phenomenon in the Appalachian mountains of the U.S. The thermonastic leaf movements have a greater importance to plants in a dim environment because the potential impact to canopy carbon gain is greater than in high light environments.
These leaf movements have several implications for horticultural management. There seems to be a trade-off between water stress tolerance and freezing stress tolerance by leaf movements. Thermonastic leaf movements may be a major mechanism of cold stress tolerance in Rhododendron species. The actual physiological cause of leaf movement has not been elucidated and many more species need to be evaluated to verify the general importance of leaf movements to Rhododendron ecology and evolution. 相似文献
40.
An intact genotoxic stress response appears to be atheroprotective and insulin sensitizing. ATM, mutated in ataxia telangiectasia, is critical for the genotoxic stress response, and its deficiency is associated with accelerated atherosclerosis and insulin resistance in humans and mice. The antimalarial drug chloroquine activates ATM signaling and improves metabolic phenotypes in mice. p53 is a major effector of ATM signaling, but it is unknown if p53 is required for the beneficial effects of chloroquine. We tested the hypothesis that the cardiometabolic effects of chloroquine are p53-dependent. ApoE-null mice with or without p53 were treated with low-dose chloroquine or saline in the setting of a Western diet. After 8 weeks, there was no p53-dependent or chloroquine-specific effect on serum lipids or body weight. Chloroquine reduced plaque burden in mice wild-type for p53, but it did not decrease lesion extent in p53-null mice. However, chloroquine improved glucose tolerance, enhanced insulin sensitivity, and increased hepatic Akt signaling regardless of the p53 genotype. These results indicate that atheroprotection induced by chloroquine is p53-dependent but the insulin-sensitizing effects of this agent are not. Discrete components of the genotoxic stress response might be targeted to treat lipid-driven disorders, such as diabetes and atherosclerosis. 相似文献