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  • 1
    ISSN: 1432-2145
    Keywords: Key words Sex chromosomes ; Sex-differentiating chromocentres ; Heterochromatin ; In situ hybridization ; Phoenix dactylifera
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  In the date palm, a dioecious mode (separate male and female individuals) and the late initial reproductive age (5–10 years) are major practical constraints for genetic improvement. Early selection on young seedlings could enhance breeding programmes and generate experimental male and female genetic stocks, but no cytogenetic protocol exists for sex determination in an immature date palm. Here we describe a cytological method based on chromomycin staining which demonstrates the occurrence of sexual chromosomes carrying distinctive nucleolar heterochromatin and thus offers, for the first time, the possibility of identifying male and female individuals by simple analysis of root meristems. This observation has been extended by in situ rDNA hybridization, confocal microscopy and dual-label flow cytometry of nuclei.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-2145
    Keywords: Sex chromosomes ; Sex-differentiating chromocentres ; Heterochromatin ; In situ hybridization ; Phoenix dactylifera
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In the date palm, a dioecious mode (separate male and female individuals) and the late initial reproductive age (5–10 years) are major practical constraints for genetic improvement. Early selection on young seedlings could enhance breeding programmes and generate experimental male and female genetic stocks, but no cytogenetic protocol exists for sex determination in an immature date palm. Here we describe a cytological method based on chromomycin staining which demonstrates the occurrence of sexual chromosomes carrying distinctive nucleolar heterochromatin and thus offers, for the first time, the possibility of identifying male and female individuals by simple analysis of root meristems. This observation has been extended by in situ rDNA hybridization, confocal microscopy and dual-label flow cytometry of nuclei.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1432-2242
    Keywords: Keywords Domestication ; Genetic diversity ; Geographical structure ; Gene flow
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  AFLP markers were used to assess genetic diversity and patterns of geographic variation among 39 accessions of foxtail millet (Setaria italica) and 22 accessions of green foxtail millet (S. viridis), its putative wild progenitor. A high level of polymorphism was revealed. Dendrograms based on Nei and Li distances from a neighbour joining procedure were constructed using 160 polymorphic bands. Bootstrap values revealed that no specific geographic structure can be extracted from these data. The high level of diversity among Chinese accessions was consistent with the hypothesis of a centre of domestication in China. The results also showed that accessions from Eastern Europe and Africa form two distinct clusters. The narrow genetic basis of these two gene pools may be the result of local-adaptation.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Theoretical and applied genetics 100 (2000), S. 147-159 
    ISSN: 1432-2242
    Keywords: Key words Domestication ; Pennisetum glaucum ; Quantitative trait loci (QTL) ; RFLP mapping ; Wild relatives
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  Quantitative trait loci (QTLs) controlling the morphological differences between pearl millet (Pennisetum glaucum ssp. glaucum) and its wild ancestor (Pennisetum glaucum ssp. monodii, form mollissimum) were investigated in a cultivated/wild F2 population by means of RFLP markers. The most critical adaptive changes resulting from the domestication process involved the spikelet structure: non-shedding seeds with reduced bracts and bristles and long involucral pedicel. Major differences also concerned characters describing the plant architecture, phenology and spike sizes. Many morphological differences could be attributed to the effect of a small number of loci with relatively large effects. These loci are mainly concentrated on four linkage groups (2, 5, 6 and 7). The loss of shedding ability, due to the absence of a functional abscission layer, is controlled by a single locus on linkage group 6 (al6). Genetic control of the other spikelet traits involved factors with large effects which are located in the region of linkage group 6 close to al6 and to an esterase gene, Esterase-E. Moreover, QTLs with large effects on plant and spike morphology traits such as plant height, number of spikes and weight of the spike were also mapped on linkage groups 6 and 7. This strong linkage of factors in the domestication syndrome may be involved in the maintenance of the phenotypic identity of wild and cultivated populations in sympatry. This result also brings new arguments in the understanding of the domestication process of this allogamous crop.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1435-4373
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Two enzyme immunoassays (EIAs), Chlamydiazyme (CZ; Abbott Laboratories) and Pathfinder (PF; Kallestadt), were compared with a cell culture technique in the detection of cervicalChlamydia trachomatis infection in 670 women in urban settings in Senegal (377 pregnant women and 293 prostitutes). Positive CZ and positive PF specimens were tested a second time using a monoclonal antibody blocking technique. True positive specimens were defined as those positive on culture or positive on EIA with confirmation of the result after blocking. Using this definition, the prevalence of genital chlamydial infection was 14.6 % and 14.3 % in pregnant women and prostitutes respectively. An important difference between the two populations was that the pregnant women were younger than the prostitutes, which might explain the fact that the prevalence of infection among the pregnant women was as high as that among the prostitutes, although the age-adjusted prevalence was higher among prostitutes than among pregnant women. The chlamydial detection rates of cell culture, CZ and PF were 62 % (26/42), 69 % (29/42) and 86 % (36/42) respectively in prostitutes and 76 % (42/55), 40 % (22/55) and 53 % (29/55) respectively in pregnant women. Agreement between the tests was 89 %, 85 % and 88 % for culture/CZ, culture/PF and CZ/PF respectively. However, when data were adjusted for chance agreement, kappa coefficients were 0.40 for culture/CZ, 0.34 for culture/PF and 0.48 for CZ/PF. These results indicate that the accuracy of the EIAs and cell culture may vary greatly in different populations: both EIAs showed a distinctly higher detection rate than culture in prostitutes and a significantly lower detection rate in pregnant women. Confirmation of positive EIA results with a blocking assay greatly enhanced the specificity of the antigen detection tests and should be obtained when using the EIAs in a clinical setting.
    Type of Medium: Electronic Resource
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