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  • 1990-1994  (4)
  • 1975-1979
  • Life and Medical Sciences  (2)
  • parasitic angiosperm  (2)
  • 1
    Electronic Resource
    Electronic Resource
    Resistance of cowpea and cereals to the parasitic angiospermStriga (1992)
    Springer
    Euphytica 63 (1992), S. 85-93 
    Details
    ISSN: 1573-5060
    Keywords: breeding for resistance ; cowpea ; parasitic angiosperm ; resistance mechanisms ; sorghum ; Striga ; Vigna unguiculata ; Sorghum bicolor
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Striga species are parasitic angiosperms that attack many crops grown by subsistence farmers in sub-Saharan Africa and India. Control of the parasite is difficult and genetically resistant crops are the most feasible and appropriate solution. In cowpea, complete resistance toStriga gesnerioides has been identified. Breeding for resistance in sorghum has identified varieties with good resistance toS. asiatica in Africa and India. One variety was also resistant toS. hermonthica in W. Africa. No such resistance toStriga has been found in maize or millets. Resistant varieties have usually been sought by screening germplasm in fields naturally infested withStriga. However, laboratory techniques have also been developed, including anin vitro growth system used to screen cowpeas for resistance toS. gesnerioides. Two new sources of resistance in cowpea have been identified using the system. The technique has also been used to investigate the mechanisms of resistance in this crop. Two mechanisms have been characterised, both were expressed after penetration of cowpea roots by the parasite. The resistance of some sorghum varieties toStriga is controlled by recessive genes. In cowpea, resistance toStriga is controlled by single dominant genes. The genes for resistance are currently being transferred to cowpea varieties which are high yielding or adapted to local agronomic conditions. OneStriga resistant cowpea variety, Suvita-2, is already being grown widely by farmers in Mali. Reports of ‘breakdown’ of resistance in cowpea toStriga have not yet been confirmed, but a wider genetic base to the resistance is essential to ensure durability ofStriga resistance.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00023914
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Virulence characteristics of a new race of the parasitic angiosperm, Striga gesnerioides, from southern Benin on cowpea (Vigna unguiculata) (1993)
    Springer
    Euphytica 72 (1993), S. 183-188 
    Details
    ISSN: 1573-5060
    Keywords: Striga gesnerioides ; Vigna unguiculata ; cowpea ; parasitic angiosperm ; breeding for resistance ; parasite variation ; races
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract An in vitro growth system was used to determine the virulence of two samples of Striga gesnerioides from Zakpota in southern Benin. Cowpea variety B301, previously considered resistant to all races of S. gesnerioides, was susceptible to both samples of the parasite. Two other cowpea varieties, 58–57 and IT81D-994, were totally resistant. Resistance in 58–57 was associated with a hypersensitive necrosis of infected roots, whilst IT81D-994 supported production of small S. gesnerioides tubercles with stems which failed to develop. Striga gesnerioides from southern Benin is the fourth race of the parasite to be identified, and the first with virulence on variety B301. The implications for breeding cowpeas with resistance to S. gesnerioides are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00034156
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Effects of cold shock and phospholipase A2 on intact boar spermatozoa and sperm head plasma membranes (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Molecular Reproduction and Development 26 (1990), S. 143-149 
    Details
    ISSN: 1040-452X
    Keywords: Fertility ; Ca2+ uptake ; Head plasma membrane ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Head plasma membranes (HPM) isolated from cryopreserved boar spermatozoa show an excessive fluidization (Buhr et al., Gamete Res 23:441-449, 1989), which might be involved in the loss of fertility. The current study assessed the ability of cold shock (5°C) and phospholipase A2 (PA2) to duplicate these effects on membrane structure and to affect 45Ca2+ uptake and gross morphological characteristics of whole, fresh boar sperm. The HPM from cold-shocked sperm showed a significantly greater rate of fluidization over time than did HPM from control sperm. Addition of PA2 (bee or snake venom, 0.1 or 10.0 ng/ml) to HPM from control sperm caused fluidization similar to cold shocking, but to a lesser degree (P 〈 0.05). Cold-shocked intact sperm exhibited severe acrosomal disruption, loss of motility, and increased 45Ca2+ uptake relative to control sperm. Addition of PA2 (bee or snake venom, 0.1, 1.0., 10.0, and 1,000 ng/ml) to control sperm had not effect on gross morphology or motility while maintaining or increasing sperm extrusion of 45Ca2+. Therefore, although PA2 can, to some extent, duplicate the effects of cold shock on HPM molecular organization, its lipid hydrolytic action is insufficient to cause all the gross disruptions of severe thermal shock. Both PA2 and cold shock disrupted HPM structure, but only cold shock increased 45Ca2+ uptake, suggesting that cold shock may be increasing 45Ca2+ uptake in areas other than the head. Cold shock disrupts sperm on three levels; membrane molecular organization, intracellular Ca2+ regulation, and gross morphology/motility.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrd.1080260208
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    Paper (German National Licenses)
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  • 4
    Electronic Resource
    Electronic Resource
    Effects of ethanol dehydration and critical point drying on fish tissue culture cell membrane elemental composition by scanning electron microscopy/X-ray microanalysis (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Microscopy Research and Technique 28 (1994), S. 259-260 
    Details
    ISSN: 1059-910X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Natural Sciences in General
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jemt.1070280310
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    Paper (German National Licenses)
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