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  • Molecular marker  (3)
  • Bone mineral density  (1)
  • Electrochemical detector  (1)
  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Theoretical and applied genetics 93 (1996), S. 494-502 
    ISSN: 1432-2242
    Keywords: Key words Mapping ; Segregation distortion ; Molecular marker ; Recombination value ; Maximum likelihood method
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In the mapping of DNA markers the distortion of segregation of marker genotypes is often observed, which may be caused by a lethal factor acting in filial generations derived from distant crosses. A method is presented for estimating the recombination values between a lethal factor locus and neighboring molecular markers, and the relative viability or fertilization ability of gametes or zygotes affected by the lethal factor in an F2 population using the maximum likelihood method and the expectation conditional maximization (ECM) algorithm. Three selection models of gamete or zygote were considered, and the most likely one was determined by goodness of fit of the observed frequency of the phenotypes to the expected ones under the models. The method was applied to segregation data of molecular markers of an F2 population consisting of 144 individuals derived from a cross between an Indica and a Japonica rice variety. The presence of a lethal factor locus (L) located on chromosome III that caused partial gametic selection in both the male and female sides was suggested. The locus L was tightly linked to RFLP marker number 23 of the RFLP linkage map of Saito et al. (1991a), and the fertilization chance of a male or female gamete possessing the lethal factor was, on average, 41.5% of that of the normal gamete.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Theoretical and applied genetics 97 (1998), S. 293-298 
    ISSN: 1432-2242
    Keywords: Key words Distorted segregation ; Molecular marker ; Recombination value ; Maximum-likelihood method ; EM algorithm
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  Distorted segregation has been repeatedly observed in various plant species in molecular-marker linkage mapping where distant crosses were made. It may be caused by a partial lethal-factor acting in the filial generations. A method is presented for estimating the recombination values between a partial lethal-factor locus and a linked molecular marker and the relative viability or fertilization ability of zygotes or gametes, respectively affected by the partial lethal factor in backcross (BC) and doubled-haploid (DH) populations using the maximum-likelihood method associated with the expectation maximization (EM) algorithm. The method was applied to segregation data of molecular markers for a population of 150 DH lines developed from the ‘Steptoe’בMorex’ cross in barley. The presence of a partial lethal-factor locus, located on chromosome 4, causing partial selection was suggested. This locus was tightly linked to the ABG500B marker, and the chance of fertilization of female gametes possessing the partial lethal factor was, on average, 59.8% that of a normal one. Two additional partial lethal factors were found on chromosome 5.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Theoretical and applied genetics 93 (1996), S. 494-502 
    ISSN: 1432-2242
    Keywords: Mapping ; Segregation distortion ; Molecular marker ; Recombination value ; Maximum likelihood method
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In the mapping of DNA markers the distortion of segregation of marker genotypes is often observed, which may be caused by a lethal factor acting in filial generations derived from distant crosses. A method is presented for estimating the recombination values between a lethal factor locus and neighboring molecular markers, and the relative viability or fertilization ability of gametes or zygotes affected by the lethal factor in an F2 population using the maximum likelihood method and the expectation conditional maximization (ECM) algorithm. Three selection models of gamete or zygote were considered, and the most likely one was determined by goodness of fit of the observed frequency of the phenotypes to the expected ones under the models. The method was applied to segregation data of molecular markers of an F2 population consisting of 144 individuals derived from a cross between an Indica and a Japonica rice variety. The presence of a lethal factor locus (L) located on chromosome III that caused partial gametic selection in both the male and female sides was suggested. The locus L was tightly linked to RFLP marker number 23 of the RFLP linkage map of Saito et al. (1991a), and the fertilization chance of a male or female gamete possessing the lethal factor was, on average, 41.5% of that of the normal gamete.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
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  • 4
    ISSN: 1612-1112
    Keywords: High performance liquid chromatography ; Electrochemical detector ; Naltrexone ; Rat brain regions and serum analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A method is described for the determination of naltrex-one in discrete rat brain regions and serum. Separation and quantitation are performed by reversed-phase high-performance liquid chromatography with electrochemical detection. The drug gave a linear response over the range of 12.5–100ng for either 1.0ml for cerebellar homogenate or 25μl for serum (1.25–10ng on column). Recoveries of naltrexone, added to the homogenate or serum, were 94±7 and 86±6%, respectively, when compared with naltrexone dissolved in water. The mean between-run relative standard deviations were 5.8 and 6.8% for cerebellar homogenate and serum, respectively, over the concentration range studied. The within-run relative standard deviations for cerebellar homogenate (12.5ng/ml) or serum (12.5ng/25μl) were 7.7%. The application of the method to an in vivo animal experiment is demonstrated.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    European journal of epidemiology 13 (1997), S. 553-558 
    ISSN: 1573-7284
    Keywords: Bone mineral density ; Oestrogens ; Sex hormones ; Smoking
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract It is known that among women over the age of 65, bone mineral density is lower, and the risk of hip fracture higher, in smokers than non-smokers. We report a study in 1334 health pre- and postmenopausal women aged 35–64 years, to determine whether this effect can be attributed to lower oestrogen levels in smokers. Among 676 premenopausal women forearm bone density was no lower in smokers (95% confidence interval 1% lower, 4% higher). Among 543 postmenopausal women who had not used hormone replacement therapy (HRT) for more than a year there was no statistically significant difference, but the lower confidence interval was consistent with a lower bone density in older smokers (by 8% at age 55–59, 16% at age 60–64). Measurements in 194 postmenopausal women not taking HRT showed that oestrone and oestradiol were similar in smokers and non-smokers, as were cortisol and FSH, LH and prolactin. Meta-analysis of the present study and previous studies confirmed significantly higher levels in smokers of the androgens DHEAS (by 37%) and androstenedione (by 34%). Oestrogens were no lower in smokers, and the lower confidence limit excluded more than a trivial effect of smoking in lowering oestrogen. These results indicate that the recognised lower bone density in elderly smokers cannot be explained by an effect of smoking on oestrogen, since in premenopausal women bone density is no lower in smokers and in postmenopausal women oestrogens are no lower in smokers. The data suggest a balance between higher androgen levels but lower rates of conversion of androgens to oestgrogens in smokers. The effect of smoking on bone may be due to impaired response of bone and other target organs to oestrogen, or to actions independent of oestrogen.
    Type of Medium: Electronic Resource
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