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  • 1
    ISSN: 1365-3040
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie
    Notizen: The cis-unsaturated molecular species of phosphatidylglycerol (PG) in chloroplasts have been implicated in the chilling sensitivity of plants. Homozygous lines of transgenic tobacco (Nicotiana tabacum) that overexpressed the cDNA for glycerol-3-phosphate acyltransferase, a key enzyme in the determination of the extent of cis-unsaturation of PG, were established from a chilling-sensitive squash (Cucurbita moschata). In transgenic plants, the proportion of saturated plus trans-monounsaturated molecular species of PG increased from 24 to 65%. However, this change did not affect the architecture of the chloroplasts. Chilling stress decreased the growth and biomass production of young seedlings of transgenic plants more severely than those of wild-type plants, and this observation suggests that the changes in the proportion of cis-unsaturated PG affected not only leaves but also developing plants. Chilling stress also damaged inflorescences. In particular, the abscission of flower buds and inflorescence meristems from transgenic plants occurred more frequently than that from wild-type plants. Thus, it is likely that decreases in the proportion of cis-unsaturated PG enhanced the sensitivity to chilling of reproductive organs.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 2
    Digitale Medien
    Digitale Medien
    Oxford, UK : Blackwell Science Ltd
    Plant, cell & environment 25 (2002), S. 0 
    ISSN: 1365-3040
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie
    Notizen: The acclimation of a plant to a constantly changing environment involves the accumulation of certain organic compounds of low molecular mass, known collectively as compatible solutes, in the cytoplasm. The evidence from numerous investigations of the physiology, genetics, biophysics and biochemistry of plants strongly suggests that glycine betaine (GB), an amphoteric quaternary amine, plays an important role as a compatible solute in plants under various types of environmental stress, such as high levels of salts and low temperature. Plant species vary in their capacity to synthesize GB and some plants, such as spinach and barley, accumulate relatively high levels of GB in their chloroplasts while others, such as Arabidopsis and tobacco, do not synthesize this compound. Genetic engineering has allowed the introduction into GB-deficient species of biosynthetic pathways to GB from both micro-organisms and higher plants; this approach has facilitated investigations of the importance of GB in stress protection. In this review, we summarize recent progress in the genetic manipulation of the synthesis of GB, with special emphasis on the relationship between the protective effects of GB in vivo and those documented in vitro.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 3
    Digitale Medien
    Digitale Medien
    Oxford, UK : Blackwell Science Ltd
    Plant, cell & environment 23 (2000), S. 0 
    ISSN: 1365-3040
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie
    Notizen: To examine the effect of abscisic acid (ABA) on the photo-induced inactivation of the photosystem II (PSII) complex, a suspension culture of Chlamydomonas reinhardtii was treated with ABA for 24 h in darkness and then, after removal of ABA, the cells were exposed to strong light at a photon flux density of 2000 μmol m−2 s−1 at various temperatures. The activity of PSII, as estimated in terms of chlorophyll fluorescence and the evolution of oxygen, decreased significantly during the exposure of cells to the strong light, and the extent of the photo-induced decrease in PSII activity was much greater at lower temperatures. Irrespective of temperature, the decrease in PSII activity in ABA-treated cells was significantly smaller than that in control cells. Moreover, the recovery of PSII activity from the photo-inactivated state in ABA-treated cells was significantly faster than that in control cells. The recovery of PSII activity in both ABA-treated and control cells was almost entirely prevented by the presence of chloramphenicol. These results indicate that ABA protects the PSII complex in C. reinhardtii against photo-induced inactivation by accelerating the recovery of this complex.
    Materialart: Digitale Medien
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  • 4
    Digitale Medien
    Digitale Medien
    Oxford, UK : Blackwell Science Ltd
    Histopathology 42 (2003), S. 0 
    ISSN: 1365-2559
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Medizin
    Notizen: Aims:  The pathogenic mechanism and predictive indicators of biological behaviour of inflammatory myofibroblastic tumour are poorly understood. We investigated molecular abnormalities of p53 and MDM2 in order to assess whether these play an important role in pathogenesis, and whether they also contribute to clinicopathological aggressive phenotype in inflammatory myofibroblastic tumour.Methods and results:  We compared the immunohistochemical expression of calponin, h-caldesmon, ALK, and p53 gene mutation and MDM2 gene amplification with clinicopathological findings in 15 cases of inflammatory myofibroblastic tumour. Histologically, cellular atypia was observed in five (33.3%) out of 15 cases. Local recurrences were observed in two (14.3%) of 14 informative cases, but no distant metastasis was observed. The expression of calponin (9/14; 64%) but not h-caldesmon (0/14; 0%) was seen, which suggested myofibroblastic differentiation. ALK expression was seen in eight (53.3%) out of 15 cases, particularly in patients under 40 years old. Nuclear expression of p53 protein was recognized in only one (6.7%) of 15 cases, and polymerase chain reaction single-strand conformation polymorphism followed by direct sequencing revealed p53 gene missense mutations in two (13.3%) of 15 cases. Nuclear expression of MDM2 was seen in four (26.7%) of 15 cases, and the MDM2 gene amplification was observed in two of the four cases.Conclusion:  Inflammatory myofibroblastic tumour shows a wide spectrum of cellular atypia and biological behaviour with p53 and MDM2 expression. However, the alterations in the p53 pathway seem not to play a major role in the pathogenesis of inflammatory myofibroblastic tumour.
    Materialart: Digitale Medien
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  • 5
    ISSN: 1365-2559
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Medizin
    Notizen: Secondary malignant giant-cell tumour of bone: molecular abnormalities of p53 and H-ras gene correlated with malignant transformation Aims: We report two cases of secondary malignant giant-cell tumour occurring without irradiation therapy. To elucidate the mechanism of malignant transformation in this tumour, we searched for the molecular abnormalities of p53, MDM2 and the H-ras genes. Methods and results: These cases were retrieved after a review of 103 cases of primary giant-cell tumour of bone, registered in our institute. One case occurred in the distal femur of a 42-year-old female after surgical curettage, while the other arose in the acetabulum of a 25-year-old male after en bloc resection. Microscopically, the malignant tumour in the distal femur was composed of a proliferation of ovoid or fusiform cells arranged in fascicles with high mitotic activities. The malignant transformed tumour in the acetabulum was made up of pleomorphic tumour cells with atypical mitoses. In the tumour of the distal femur, both p53 and H-ras mutations were detected. Abnormal nuclear accumulation of p53 protein and c-myc expression were also revealed by immunohistochemistry. In both cases, the recurrent malignant tumour over-expressed MMP-9 and revealed a higher MIB-1-labelling index compared with the primary conventional giant-cell tumour. Conclusions: Our results suggest that multiple oncogene or tumour suppressor gene mutations may play an important role during malignant transformation in conventional giant-cell tumours.
    Materialart: Digitale Medien
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  • 6
    ISSN: 1365-2559
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Medizin
    Notizen: Matrix metalloproteinase-2 expression correlates with morphological and immunohistochemical epithelial characteristics in synovial sarcoma Aims: Synovial sarcoma is a unique mesenchymal tumour characterized by the presence of epithelial differentiation, although the mechanism involved in the epithelial morphology is still unclear. The aim of this study was to evaluate the function of matrix metalloproteinase-2 (MMP-2) in synovial sarcoma, in order to assess whether MMP-2 expression plays an important role in epithelial differentiation, or whether it contributes to a poor clinical outcome. Methods and results: Immunohistochemical stainings for MMP-2, cytokeratins (CKs) 7, 8, 18 and 19, and E-cadherin were performed for 58 (44 monophasic and 14 biphasic) cases of synovial sarcoma, and we compared the expression of these proteins with the histological and clinical findings. MMP-2 and E-cadherin expression was observed in 43 cases (74.1%) and in 18 cases (31.0%), respectively. Expression of these proteins was preferentially observed in the glandular components of biphasic tumours or the epithelioid areas of monophasic tumours. Statistically significant correlations were recognized between MMP-2 expression and E-cadherin expression of biphasic subtype. Moreover, there were statistically significant correlations between monophasic tumours with epithelioid areas and MMP-2 expression or E-cadherin expression. MMP-2 expression was correlated with epithelial differentiation as assessed by CK immunoreactivity. The expression of MMP-2 did not affect the overall survival rate in synovial sarcoma. Conclusions: MMP-2 expression seemed to have an important role to play in the epithelial differentiation of tumour cells in synovial sarcoma, through remodelling of the extracellular matrix and by changing the cytoskeletal interaction between the extracellular matrix and tumour cells.
    Materialart: Digitale Medien
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  • 7
    facet.materialart.
    Unbekannt
    Amsterdam : Periodicals Archive Online (PAO)
    Population research and policy review. 11:3 (1992:Sept.) 217 
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 8
    ISSN: 1365-2133
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Medizin
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 9
    Digitale Medien
    Digitale Medien
    Amsterdam : Elsevier
    Biochemical and Biophysical Research Communications 200 (1994), S. 679-686 
    ISSN: 0006-291X
    Quelle: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Thema: Biologie , Chemie und Pharmazie , Physik
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 10
    Digitale Medien
    Digitale Medien
    Amsterdam : Elsevier
    Biochemical and Biophysical Research Communications 184 (1992), S. 1448-1455 
    ISSN: 0006-291X
    Quelle: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Thema: Biologie , Chemie und Pharmazie , Physik
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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