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Michelle van der Bank F. H. van der Bank B. -E. van Wyk 《Plant Systematics and Evolution》1999,219(1-2):27-38
We have tested the hypothesis that reseeding is a plesiomorphic character state and that sprouting is a derived state inAspalathus linearis, and that the latter is an adaptation to ensure fire-survival in a fireprone environment. Samples of five seeder and four sprouter populations of A.linearis were examined by horizontal starch gel electrophoresis to assess the amount of genetic differentiation within and between sprouting and seeding populations, and to determine the extent of gene flow between the populations. Leaf extracts were surveyed for ten enzymes and gene products revealed genetic variation at 13 (76%) of 17 protein coding loci. Allele frequency differences were found between sprouting and seeding populations and genetic distance values show that the sprouters are grouped separate from the seeders, thus providing support for the morphological data on which the above mentioned hypothesis is based. It is evident that evolution operates at the population level inA. linearis. 相似文献
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Brief admission of the new diabetic child and of a parent to an enlightened hospital for stabilisation, preliminary education, and familiarisation with hospital and community staff is well worth while. The greater the demand for constant control of the highest quality, the greater the need for a close understanding of the psychosocial factors concerned and for clinical skill. The nature of the home and the family relationships should in theory be available from the child''s general practitioner at the time of the first referral since he has so much information about the whole family. With the virtual disappearance, however, of mutual consultation in the patient''s home in many places, the opportunity for oral communication has declined, and availability on the telephone is not always easy. The busy general practitioner (far less an unknown physician from a deputising service without access to the records) has little time to write a comprehensive letter. In practice a relatively small hospital-based mobile team of specially experienced sisters who are keen to communicate in the home, the GP''s surgery, and the school makes a major contribution to the diabetic care of a young population vulnerable to major handicap in what should be the prime of life. Their cost effectiveness may be difficult to prove but it is not at all in doubt--especially when the sisters as in this area deal in the community with a wider range of chronic illnesses and handicaps in children. 相似文献
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A P Weetman M E Holt A K Campbell R Hall A M McGregor 《BMJ (Clinical research ed.)》1984,288(6416):518-520
A study was conducted investigating the possibility that the immunosuppressive action of methimazole (the active metabolite of the antithyroid drug carbimazole) might be due to an effect on the production of oxygen radicals by monocytes. Techniques comprised measurement of luminol dependent chemoluminescence in monocytes and a spectrophotometric assay for production of hydrogen peroxide. The results showed definite inhibition of formation of oxygen radicals by resting and stimulated monocytes, which may explain the immunosuppressive action of the drug in Graves'' disease. The findings also suggest that the formation of oxygen radicals and the initiation of the immune response may be closely related. 相似文献
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Rachael V. Gallagher Lesley Hughes Michelle R. Leishman Peter D. Wilson 《Biological invasions》2010,12(12):4049-4063
Potential interactions between climate change and exotic plant invasions may affect areas of high conservation value, such
as land set aside for the protection of endangered species or ecological communities. We investigated this issue in eastern
Australia using species distribution models for five exotic vines under climate regimes for 2020 and 2050. We examined how
projected changes in the distribution of climatically suitable habitat may coincide with the remaining remnants of an endangered
ecological community—littoral rainforests—in this region. The number of known infestations of each weed in tropical, subtropical
and temperate areas was used to assess the likelihood of further expansion into areas projected to provide suitable habitat
under future conditions. Littoral rainforest reserves were consistently predicted to provide bioclimatically suitable habitat
for the five vines examined under both current and future climate scenarios. We explore the consequences and potential strategies
for managing exotic plant invasions in these protected areas in the coming decades. 相似文献
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