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  • 1
    Digitale Medien
    Digitale Medien
    Springer
    Oecologia 88 (1991), S. 55-60 
    ISSN: 1432-1939
    Schlagwort(e): Annual plant ; Nutrition ; Optimization ; Reproductive allocation ; Xanthium canadense
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary The effects of nutrition on the timing of reproductive initiation of a short-day annual plant Xanthium canadense (cocklebur) were examined with the following hypotheses in mind: If the plant always follows an optimal growth schedule, low-nutrient plants will initiate reproductive growth earlier than high-nutrient plants. On the other hand, if the plant flowers in response to photoperiodic stimuli, both plants will initiate reproductive growth on the same day. The sand-culture experiment showed that high-nutrient plants flowered earlier than the low-nutrient plants, leading to rejection of the first hypothesis. The predicted optimal flowering time is 2 days later than the actual flowering time in high-nutrient plants and 10 days earlier in low-nutrient plants. These deviations from the optimal times reduced the reproductive yield by 0.1% and 2.3%, respectively. The ratio of the final reproductive yield to the vegetative mass at flower initiation was 1.10 in high-nutrient plants and 0.63 in low-nutrient plants. Since the expected ratio for the optimal growth schedule is 1.0, high-nutrient plants followed the opitmal growth schedule more closely than the low-nutrient plants. Cocklebur is a fast-growing annual which is common in relatively nutrient-rich environments. This study suggests that cocklebur adapts itself to such environments through its photoperiodic response.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 2
    ISSN: 1432-0533
    Schlagwort(e): Aging ; PAS-positive granular structures ; Learning disturbance ; Senescence accelerated mouse (SAM)
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary Abnormal granular structures, which stained positively with periodic acid-Schiff (PAS-positive granular structures; PGS), were observed in the brain of senescence accelerated mouse (SAM). They were small, round to ovoid, homogenous structures measuring up to 5 μm in diameter and usually grouped in clusters. PGS were localized in the hippocampus, piriform cortices, olfactory tubercle, nucleus of the trapezoid body, and cerebellar cortices. Quantitative analysis revealed that PGS remarkably increased in the hippocampus of SAM-P/8, a substrain of SAM, with advancing age, although a few PGS also appeared in the aged control mice, SAM-R/1 and DDD. Their histochemical nature, morphological features and distribution pattern were different from those of corpora amylacea and other similar bodies. A close anatomical relationship between PGS and glial fibrillary acidic protein-positive astrocytes was inferred from immunohistochemical studies. PGS is considered to be one of the morphological manifestations of senescence in mice brains, and are found to occur more numerously in the brains of learning or memory deficit mice, SAM-P/8.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 3
    ISSN: 1437-7799
    Schlagwort(e): Key wordsα-Smooth muscle actin ; Myosin heavy chain ; Caldesmon ; Tropomyosin ; Mesangial cell ; Interstitial cell
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract Background. Phenotypic changes in glomerular mesangial cells and interstitial cells are considered to be closely associated with the progression of glomerulosclerosis and renal fibrosis in IgA nephropathy. To further evaluate the relevance of phenotypic changes, we examined the expression of four different contractile proteins as markers of the phenotypic changes. Methods. The expression of nonmuscle myosin heavy chain isoform (SMemb), α-smooth muscle actin (α-SMA), caldesmon (CaD), and tropomyosin (TM) was evaluated by indirect immunofluorescent studies in renal biopsy specimens from 21 patients with IgA nephropathy. The relationships with the histological parameters and clinical parameters were analyzed. Results. Pronounced expression (score of 2 or more) of contractile proteins was observed in the majority of the patients (57%–90%) compared with controls. There was no significant relationship between the glomerular expression score of any contractile protein and the proliferation index or sclerotic index. Daily urinary protein excretion in the group expressing low levels of caldesmon in the glomerulus was significantly lower than that in the group expressing high levels (P 〈 0.05). There were significant correlations among the glomerular expressions of these contractile proteins, except for TM (P 〈 0.05). All contractile proteins were expressed in tubulointerstitial lesions, and only SMemb expression was detected in tubular epithelial cells. The interstitial scores of all contractile proteins increased in parallel with the degree of tubulointerstitial lesion (P 〈 0.05). Conclusions. Contractile proteins appeared to be coordinately expressed in the glomerulus and the interstitium in IgA nephropathy, which may reflect the mechanical stress involved with glomerulonephritis.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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