Growth and the composition and transport of carbohydrate in compatible and incompatible peach/plum grafts     

Moing A  Salesses G  Saglio PH 《Tree physiology》1987,3(4):345-354

The growth of scions and rootstocks of compatible (Prunus persica L. Batsch cv. Springtime/Prunus cerasifera L. Ehrh. cv. myrobolan P2032) and incompatible (Prunus persica L. Batsch cv. Springtime/Prunus cerasifera L. Ehrh. cv. myrobolan P18) peach/plum grafts were compared. The composition of soluble carbohydrates in phloem and cortical tissues of both peach/plum grafts and ungrafted plums and the translocation of these compounds across the union of grafted plants were examined. Sorbitol and sucrose were the dominant sugars in the phloem and cortical tissues of plum. A cyanogenic glycoside, prunasin, was present in peach tissues in amounts equivalent to those of sorbitol or sucrose, whereas only small amounts of prunasin were detected in plum tissues. The concentration of prunasin was significantly higher in the phloem of the P18 rootstock of the incompatible graft. Sorbitol was the only sugar significantly depleted in rootstock tissues of the incompatible graft when the first foliar symptoms of graft incompatibility became evident. Translocation studies with 1-(14)C-deoxyglucose showed that the relative distribution of radioactivity across the graft union was similar in both compatible and incompatible grafts. However, the total amount of radioactivity translocated across the incompatible graft was less than one-third of that translocated across the compatible graft. The results are consistent with the hypothesis of a progressive poisoning of the root system in the incompatible graft by a compound synthesized in peach foliage. The role of prunasin as a possible candidate is discussed.  相似文献   

Nonchromosomal genes: extrachromosomal elements in lower eukaryotes     

Blackburn EH 《Science (New York, N.Y.)》1987,237(4812):307

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A low-threshold test ban is feasible     

Feiveson HA  Paine CE  VON Hippel F 《Science (New York, N.Y.)》1987,238(4826):455-459

At present, nuclear explosions are limited by treaty to underground testing with yields of no more than 150 kilotons, and recently there have been renewed calls for further test restrictions. As part of these discussions, the U.S. Congress is considering bills that would legislate new limits to testing,whereas the Reagan Administration opposes such constraints. The editors of Science have asked two groups of participants in the debate to present their arguments for or against new limits to testing. Feiveson, Paine, and von Hippel argue for a treaty of indefinite duration between the United States and the Soviet Union, which includes the following provisions: (i) a ban on all testing outside a desiqnated site having known seismic properties; (ii)verification by means of on-site inspection and in-country seismic monitoring; (iii) unlimited testing below 1 kiloton at the special site; and (iv) an average of one test per year with a yield of up to 15 kilotons for ensuring reliability of the nuclear stockpile. MiUer, Brown, and Nordyke argue that a lowering of the present 150-kiloton threshold would be undesirable, and that new test bans would divert attention from a comprehensive approach to negotiated reductions in the nuclear and conventional arsenals of the United States and the Soviet Union.  相似文献   

The testing movement and its founders: psychological testing and american society, 1890-1930     

Kuklick H 《Science (New York, N.Y.)》1987,237(4820):1358-1359

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The process of science: science in action     

Etzkowitz H 《Science (New York, N.Y.)》1987,238(4827):695-696

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Response of egg weight to the inclusion of various fats in layer diets     

R. H. Scragg  N. B. Logan  N. Geddes 《British poultry science》1987,28(1):15-21

1. Brown egg layers were fed diets differing in oil content, oil source and linoleic acid concentration and the effect on performance from 22 to 69 weeks of age was studied.

2. The birds responded with an increasing mean egg weight up to a linoleic acid intake of 2.75 g/bird d.

3. Increasing the intake of readily absorbable oil without increasing linoleic acid concentration did not increase mean egg weight.  相似文献   

Proliferative glomerulonephritis leading to nephrotic syndrome in a cow     

Doré M  Morin M  Gagnon H 《The Canadian veterinary journal. La revue veterinaire canadienne》1987,28(1-2):40-41

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Infestation in the dog by the paralysis tick Ixodes holocyclus 3. Respiratory effects     

J. E. ILKIW  D. M. TURNER 《Australian veterinary journal》1987,64(5):142-144

To assess respiratory function in dogs with tick paralysis, respiratory measurements were recorded on 14 dogs experimentally infested with Ixodes holocyclus. There was a progressive fall in respiratory rate with no change in tidal volume, which resulted in a significant fall in minute respiratory volume in the latter stages of the disease. The fall in respiratory rate was possibly central in origin and was accompanied by an increased alveolar-arterial oxygen tension difference, probably caused by pulmonary congestion and oedema. The "grunting" respiration seen in tick paralysis was due to closure of the vocal cords during expiration and could represent an attempt to re-expand collapsed parts of the lung.  相似文献   

Federal and trade deficits     

Abelson PH 《Science (New York, N.Y.)》1987,238(4831):1211

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Materials research     

Abelson PH 《Science (New York, N.Y.)》1987,235(4784):9

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