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  • Pollen competitive ability  (2)
  • Adrenal function  (1)
  • Brush-border membrane vesicle  (1)
  • 1
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Biochimica et Biophysica Acta (BBA)/Biomembranes 1191 (1994), S. 27-32 
    ISSN: 0005-2736
    Keywords: Brush-border membrane vesicle ; Chemical modification ; Lepidopteran larva ; Leucine transport ; Phenylglyoxal ; Potassium ion/leucine cotransport
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology , Chemistry and Pharmacology , Medicine , Physics
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-1076
    Keywords: Hypophyso-gonadal function ; Adrenal function ; Public hair ; Genital development ; Adrenal steroids ; Puberty
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract LH-RH tests (50 μg i.v.) and hCG tests (2000 IU/day for 3 days) were carried out in 16 normal boys in stage P1 both for genitalia and pubic hair (group 1); 7 normal boys over 91/2 years in stage P 1 for genitalia and stage P 2–3 for pubic hair (group 2); 9 boys in stage P 2–3 for genitalia but stage P 1 for pubic hair (group 3); 10 boys in stage P 2–3 both for genitalia and pubic hair (group 4). In 10 prepubertal boys in group 1 (group 1a) and in all subjects in groups 2, 3 and 4 the levels of Δ4-androstenedione (Δ4), dehydroepi-androsterone (DHEA), dehydroepiandrosterone sulphate (DHEA-S) and 17-hydroxyprogesterone (17-OH-P) were evaluated under basal conditions. In groups 1 and 2 the mean basal and post-hCG testosterone values, and the basal and post-LH-RH (peak, maximum increase and area of the curve) values for LH and FSH were not significantly different. The values of Δ4, DHEA, DHEA-S for the boys in group 2 were higher (P〈0.01, P〈0.05, and P〈0.01 respectively) than for those in group 1. In the two groups of subjects in stage P 2–3 for genitalia and in different stages for pubic hair, no differences were noted for post-hCG testosterone or for gonadotropins. The basal value of testosterone was higher for the boys in group 4, as was DHEA. The values of Δ4, DHEA, DHEA-S for the boys in group 4 were higher (P〈0.05) than those of group 1a. The values of Δ4 and DHEA in the subjects in group 3 were lower (P〈0.001 and P〈0.01 respectively) than those of the boys of group 2. Our data seem to show that: (a) the appearance of pubic hair without a simultaneous increase in the volume of the testes (even if it occurs in the normal period for pubertal development), and cannot be considered an expression of the activation of the hypothalamopituitary-gonadal axis; (b) adrenarche and maturation of gonadal function are two independent processes which are usually linked in time.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Theoretical and applied genetics 91 (1995), S. 936-940 
    ISSN: 1432-2242
    Keywords: Maize ; Zea mays L ; Pollen competitive ability ; Pollen germinability Pollen-tube growth ; Pollen-pistil interaction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Various factors (pollen diameter, in vitro germination and tube length, in vivo growth rate in selfed and nonselfed styles) which could possibly contribute to the competitive ability of pollen were investigated on 30 Zea mays L. inbred lines. The only factor with which pollen diameter was positively correlated was in vitro pollen-tube growth. Traits related to the early stages of growth (in vitro germination, in vitro tube length, early in vivo pollen growth rate) were all positively correlated with each other, and these early characteristics were negatively correlated with late in vivo tube growth rate, which is largely influenced by the stylar genotype.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Theoretical and applied genetics 76 (1988), S. 601-608 
    ISSN: 1432-2242
    Keywords: Maize pollen ; Male gametophytic selection ; Pollen competitive ability ; Gametophytic fitness variability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Male gametophytic selection can play a special role in the evolution of higher plant populations. The main assumption — gametophytic-sporophytic gene expression of a large portion of a plant's genes — has been proven by a number of studies. Population analyses have revealed a large amount of variability for male gametophytic fitness. However, the data available do not prove that at least a portion of this variability is due to postmeiotic gene expression. This paper reports the analysis of a synthetic population of maize based on a gametophytic selection experiment, carried out according to a recurrent scheme. After two cycles of selection, the response was evaluated for gametophytic and sporophytic traits. A parameter representing pollen viability and time to germination, although showing a large amount of genetic variability, was not affected by gametophytic selection, indicating that this variability is largely sporophytically controlled. Pollen tube growth rate was significantly affected by gametophytic selection: 21.6% of the genetical variability was released by selection. Correlated response for sporophytic traits was observed for mean kernel weight: 15.67% of the variability was released. The results are a direct demonstration that pollen competitive ability due to pollen tube growth rate and kernel development are controlled, to a considerable extent, by genes expressed in both tissues. They also indicate that gametophytic selection in higher plants can produce a higher evolution rate than sporophytic selection; it can thus serve to regulate the amount of genetic variability in the populations by removing a large amount of the genetic load produced by recombination.
    Type of Medium: Electronic Resource
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