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  • 1
    Electronic Resource
    Electronic Resource
    [s.l.] : Nature Publishing Group
    Nature 173 (1954), S. 504-505 
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Apart from the work of Luscher3, which in any event, was not intended as a true in vitro cell culture, no attempts at tissue culture have been carried out on insects of the order Hemiptera-Heteroptera, of which Rhodnius prolixus, a useful and convenient laboratory insect, is a representative. It ...
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  • 2
    ISSN: 1570-7458
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Résumé Les Hétéroptères suceurs de sève possèdent sur le mesenteron postérieur de nombreux coecums remplis de bactéries symbiotiques. Chez beaucoup d'espèces, par exemple Mygdonia tuberculosa (Coreidae) le mesenteron est interrompu dans sa région moyenne et la partie postérieure renferme un contenu digestif qui représente les bactéries coecales digérées. La partie antérieure contient peu de matière solide provenant de la sève de la plante-hôte. Chez Piezosternum calidum, suceur de sève sur des cucurbitacées; l'intestin moyen n'est pas interrompu et est complètement rempli par un matériel presque solide. Ce contenu digestif est uniforme d'aspect sur coupes histologiques et sa composition riche en acides aminés, le rapproche davantage des bactéries coecales que de la sève de la plante-hôte. Le mesenteron présente d'ailleurs une région très acide où les bactéries pourraient être digérées. Ces bactéries se cultivent sur un milieu à base d'acide urique, de nitrate ou d'ammoniaque, en ce qui concerne la source d'azote. L'utilisation massive des bactéries symbiotiques par l'insecte lui est peut-être nécessaire car la source d'azote dans la plante n'est pas directement assimilable. La continuité de la lumière intestinale est peut-être liée à l'absence dans la sève de la plante d'une substance qui serait nuisible aux bactéries.
    Notes: Abstract Evidence is presented in support of the hypothesis that in Piezosternum calidum the mid-gut contents consist of symbiotic bacteria from the gastric caeca, and are not derived from the plant sap ingested. A similar process has been observed in other large sap-sucking Heteroptera, of which Mygdonia tuberculosa (Coreidae) has been studied as an example, the site of bacterial digestion is usually posterior to an interruption in the continuity of the mid-gut, but in P. calidum the gut is continuous and the contents fill it completely. It is suggested that the mid-gut contents of some other sap-sucking Heteroptera with continuous guts may also prove to be derived from their bacterial symbionts.
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  • 3
    ISSN: 1573-5060
    Keywords: barley ; genotype by environment interaction ; Hordeum vulgare ; farmer participation ; PPB ; participatory plant breeding
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Decentralized selection, defined as selection in the target environment, has been used to emphasize favorable interactions when significant genotype by environment interactions exist. However, crop breeding based on decentralized selection can still miss its objectives if it does not utilize the farmers' knowledge of the crops and the environment, and it may fail to fit crops to the specific needs and uses of farmers' communities unless it becomes participatory.One cycle of decentralized participatory selection was conducted in eleven locations in Syria. 208 barley entries (fixed lines and segregating populations) were planted unreplicated in two research stations and in the fields of nine Syrian (host) farmers, where they were managed (except planting) by the farmers themselves. Visual selection was conducted by a breeder at all locations and by the host farmers on their own fields and on both stations. In five farm locations, there was also a one-time group selection by neighboring farmers.Host farmers were able to handle the large number of entries making observations during the cropping season using different scoring methods. They did not use the performance of entries on station for their final selection and used a higher selection pressure than the breeder. In their own fields, they selected about one tenth the number of entries selected by the breeder, while on station the farmers selected, on average, about half the number of lines selected by the breeder. For some broad attributes, such as modern germplasm versus landraces, selection was mostly driven by environmental effects. Selection for other attributes was partly environmentally driven and partly based on individual farmers preferences.Selection preferences were similar for fixed or segregating populations. There was wider diversity among farmers' selections in their own fields than among farmers' selections on research stations and among breeder's selections, irrespective of where the selection was conducted. Larger kernels, higher grain yield and biomass, and taller plants (particularly in environmentally stressed locations) were the characteristics most frequently used as selection criteria by both breeder and farmers.Entries selected by the farmers yielded as much, and in one case significantly more, than those selected by the breeder.Decentralized-participatory selection was significantly more efficient in identifying the highest yielding entries in farmers' fields than any other type of selection. There was also evidence suggesting that the breeder was more efficient in selecting higheryielding entries in the research station in a high rainfall area, while the farmers were more efficient in selecting under stress conditions. The results suggest that farmers can handle selection choices among a large number of lines, and because farmers' selections are at least as high yielding as breeder's selections, it is possible to transfer the responsibility of selection to farmers in their fields.
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  • 4
  • 5
    Publication Date: 1994-02-01
    Description: SUMMARYIn the first two of four experiments, sheep were fed, ad libitum, sorghum stover supplemented with graded levels of foliage of the shrub leucaena (Leucaena leucocephald) or mulga (Acacia aneura), which provided between 0 and 0·34 or between 0 and 0·43 of the dietary dry matter (DM) respectively. A second treatment (with or without urea) was superimposed in a factorial design. The effect of treatments on liveweight (LW) was explainable by their effects on voluntary intake of apparently digestible organic matter (DOMI). D0M1 was increased by mulga, largely due to an increase in the total voluntary intake of organic matter (OM). Leucaena increased DOMI by increasing the ration OM digestibility and, at low levels of inclusion, intake of the basal diet. Roughage intake was greatest when leucaena provided 0·15–0·20 of the dietary DM. Leucaena increased rumen ammonia, and whenever roughage intake was increased by urea, leucaena also increased it.In the third experiment, when diets were made isonitrogenous with urea, roughage intake was slightly greater when leucaena, rather than its ash or a mineral mixture, was supplemented. Total OM intake and DOMI were greatest when leucaena was fed.In the final experiment, sheep were fed one of ten treatments: three basal diets (two of sorghum stover and the third of native pasture hay) each supplemented with legumes (leucaena to the hay and one stover diet and cowpea straw to the second stover diet), ash of the respective legume and formaldehyde-treated casein. The tenth treatment was sorghum stover plus urea. For sorghum stover diets with leucaena-based or cowpea straw-based supplements, DOMI responded linearly to the nonurea nitrogen concentration of the diet. On the other hand, for native hay with leucaena-based supplements, the response of DOMI to non-urea N was negligible. It was noted that the native hay (predominantly Flinders grass, Iseilema vaginiflorum), contained lower concentrations of polyphenols than sorghum stover.It was concluded that browse foliage can increase the voluntary DOMI of sheep consuming low quality roughages by providing nitrogen and sometimes minerals and OM of greater digestibility. The slowly-degradable proteins in leucaena, cowpea straw or formaldehyde-treated casein are more effective with polyphenol-rich sorghum stover than with native hay of otherwise similar composition.
    Print ISSN: 0021-8596
    Electronic ISSN: 1469-5146
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
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  • 6
    Publication Date: 1997-11-01
    Description: Annual variation in the feeding value of barley straw (Hordeum vulgare L. subsp. vulgare) is economically significant in the Mediterranean region. The relationship between the feeding value for sheep of several winter-planted barley cultivars and monthly meteorological data was analysed at Tel Hadya, northwest Syria (mean annual precipitation 330 mm) in 11 years. Indicators of feeding value included contents of neutral detergent fibre, acid detergent fibre and nitrogen (11 years), voluntary straw intake by sheep (10 years), voluntary digestible organic matter intake (9 years), in sacco dry matter loss and lignin content (8 years), in vitro digestibility (7 years) and in vitro gas production (6 years). Monthly meteorological data included total precipitation, mean minimum and mean maximum air temperatures.Conditions likely to decrease grain yield tended to increase the feeding value of straw. Low mean minimum temperature in February, low precipitation in January, February, March and April, and high mean maximum temperature in March, April and May increased one or more indicators of straw feeding value (by both bivariate and multiple regression, P
    Print ISSN: 0021-8596
    Electronic ISSN: 1469-5146
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
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  • 7
    Publication Date: 1954-03-01
    Print ISSN: 0028-0836
    Electronic ISSN: 1476-4687
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Published by Springer Nature
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