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  • 1990-1994  (6)
  • 1975-1979
  • sexual orientation  (4)
  • parasitic angiosperm  (2)
  • 1
    Electronic Resource
    Electronic Resource
    Familiality of female and male homosexuality (1993)
    Springer
    Behavior genetics 23 (1993), S. 313-322 
    Details
    ISSN: 1573-3297
    Keywords: Homosexuality ; sexual orientation ; familiality ; environment ; genetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Psychology
    Notes: Abstract We examined data from a large cohort of homosexual and heterosexual females and males concerning their siblings' sexual orientations. As in previous studies, both male and female homosexuality were familial. Homosexual females had an excess of homosexual brothers compared to heteroxual subjects, thus providing evidence that similar familial factors influence both male and female homosexuality. Furthermore, despite the large sample size, homosexual females and males did not differ significantly from each other in their proportions of either homosexual sisters or homosexual brothers. Thus, results were most consistent with the possibility that similar familial factors influence male and female sexual orientation. However, because results conflicted with those of some other studies, and because siblings' sexual orientations were obtained in a manner likely to yield more errors than in these other, smaller studies, further work is needed using large samples and more careful methods before the degree of cofamiliality of male and female homosexuality can be resolved definitively. We also examined whether some parental influences comprised shared environmental effects on sexual orientation. Scales attempting to measure such influences failed to distinguish subjects with homosexual siblings from subjects with only heterosexual siblings and, thus, did not appear to measure shared environmental determinants of sexual orientation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01067431
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  • 2
    Electronic Resource
    Electronic Resource
    Sexual orientation, sexual identity, and sex-dimorphic behaviors in male twins (1991)
    Springer
    Behavior genetics 21 (1991), S. 75-96 
    Details
    ISSN: 1573-3297
    Keywords: sexual orientation ; twins ; heritability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Psychology
    Notes: Abstract Sexual orientation, sexual identity, and sex-dimorphic behaviors were assessed concurrently and retrospectively, for childhood, in 95 pairs of male monozygotic (MZ) twins and 63 pairs of dizygotic (DZ) twins. There was a significantly higher rate of adult homosexuality among the MZ than among DZ twins. We employed a model-fitting approach using LISREL to test for genetic and environmental influences on variation for each trait singly and on the covariation among all six traits (three for childhood and three for adulthood). Univariate analyses confirmed the presence of familial factors for five of the six variables but were generally unable to distinguish shared environmental from genetic influences. Hierarchial tests of multivariate models supported the existence of an additive genetic factor contributing to the covariance among the variables. More restrictive multivariate models yielded a significant genetic influence on sexual orientation. Because of the different rates of orientation by zygosity and because of the restrictive nature of some of the multivariate models, our results are best considered tentative but do suggest that further biometrically oriented studies of sexual orientation and its correlates would be worthwhile.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01067668
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    Paper (German National Licenses)
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  • 3
    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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  • 4
    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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  • 5
    Electronic Resource
    Electronic Resource
    A test of the maternal stress theory of human male homosexuality (1991)
    Springer
    Archives of sexual behavior 20 (1991), S. 277-293 
    Details
    ISSN: 1573-2800
    Keywords: maternal stress ; sexual orientation ; etiology ; homosexuality ; familiality
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Psychology
    Notes: Abstract Both the neurohormonal theory of sexual orientation and previous research on humans and animals suggest that male homosexuality may arise from prenatal stress during the brain's sexual differentiation. Stress-proneness and retrospective reports of stress during pregnancy were obtained from mothers of male and female heterosexuals, bisexuals, and homosexuals. Each mother also rated pregnancy stress for a heterosexual sibling of the subject. For males, neither between-family nor within-family analyses revealed a maternal stress effect for either sexual orientation or childhood gender nonconformity. However, mothers of effeminate children reported more stress-proneness than other mothers. Male homosexuality nevertheless was strongly familial, suggesting a reconsideration of genetic and familial environmental mechanisms.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01541847
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  • 6
    Electronic Resource
    Electronic Resource
    Maternally rated childhood gender nonconformity in homosexuals and heterosexuals (1993)
    Springer
    Archives of sexual behavior 22 (1993), S. 461-469 
    Details
    ISSN: 1573-2800
    Keywords: homosexuality ; gender nonconformity ; sexual orientation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Psychology
    Notes: Abstract Homosexual and heterosexual subjects provided self-ratings of childhood gender nonconformity. Additionally, their mother rated them on several adjectives describing childhood behavior, which included words related to gender nonconformity. Male homosexuals were remembered by their mothers as less masculine and more nonathletic. This finding did not appear to be due to a bias in mothers' memories. Though female homosexuals were recalled as more masculine than female heterosexuals, this appeared to reflect retrospective bias, as mothers who knew of their daughters' homosexuality were more likely to rate them as masculine. Both self-rated and maternally rated childhood gender nonconformity made independent contributions in predicting sexual orientation. Within the homosexual samples, maternal and self-ratings of subjects' childhood gender nonconformity failed to correlate significantly.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01542559
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    Paper (German National Licenses)
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