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1Author    Karlheinz TempelRequires cookie*
 Title    Radioadapted Chicken Embryo Cells: Challenge Specificity and Alterations in Higher-Order D N A Structure  
 Abstract    Radioadapted chicken embryo cells (X-irradiation in ovo with 10 cGy at the 14th day of developm ent with priming periods of 24 h) were treated in vitro by challenge doses of 14 different D N A -and/or chromatin-interactive agents, including X-rays. A decrease in the cel­ lular damage, as measured by scheduled D N A synthesis, was only observed with X-irradia­ tion. Sedimentation of nucleoids as well as viscosity of alkaline lysates from ethidium bro­ mide (0 .3 5 -4 0 0 (ig/ml)-, novobiocin (1 2 5 -1 8 0 0 ^g/ml)-, and hyperthermia (30 min at 43° and 45°)-treated cells suggest a higher tendency of radioadapted cells to undergo positive D N A supercoiling. When D N A from adapted and non-adapted chicken embryo cells was used as substrate, neither its digestion by D N ase I nor the inhibition of DNase I activity by various DNA-interactive agents was changed in primed cells. From the previous investigations as well as from the present results it is concluded that an increase of tightening of protein-DNA interactions within the nuclear matrix is a molecular determinant of the elevated radiation resistance in radioadapted chicken embryo cells. 
  Reference    Z. Naturforsch. 51c, 211 (1996); received N ovem ber 29 1995/January 5 1996 
  Published    1996 
  Keywords    Chicken Embryo, Radioadaptation, Challenge Specificity, Nucleoids 
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 TEI-XML for    default:Reihe_C/51/ZNC-1996-51c-0211.pdf 
 Identifier    ZNC-1996-51c-0211 
 Volume    51 
2Author    Karlheinz Tempel, Hannelore Kortenbeutel, Christina Von ZallingerRequires cookie*
 Title    Bleomycin -Induced DNA Damage and DNA Repair in Chicken Embryo Cells as Compared to X-Irradiation  
 Abstract    Following in vitro-and in ovo-exposure of chicken embryo cells, the level of bleomycin (BM) -induced damage was evaluated by using DNA synthesis, nucleoid sedimentation (SED), and viscometry of alkaline cell lysates (VISC). This damage was compared to X-irradiation, using 5.9-378 nM BM in vitro, 1.5-116 (.ig BM/egg in ovo, and 2-32 Gy, respec­ tively, in vitro as well as in ovo. With respect to BM. the most notable result is the increase in D N A synthesis and VISC at the lowest concentrations of the drug. A decrease in both parameters was observed at high BM concentrations and following exposure to X-rays, con­ comitantly with an increase in SED. Regarding the radiomimetic drug BM and X-rays, dif­ ferent modes of DNA damage and D N A repair are suggested by previous investigations and the present results. Therefore, further evidence is presented, that the chicken embryo can act as a simple, rapid and inexpensive test system to characterize the biological effects of many nucleo-and/or cytotoxic agents. 
  Reference    Z. Naturforsch. 54c, 1068—1074 (1999); received July 14/September 3 1999 
  Published    1999 
  Keywords    Bleomycin, Chicken Embryo, DNA-Damage, DNA-Repair, Nucleoids, X-Irradiation 
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 TEI-XML for    default:Reihe_C/54/ZNC-1999-54c-1068.pdf 
 Identifier    ZNC-1999-54c-1068 
 Volume    54 
3Author    Karlheinz Tempel, Rüdiger HeinzelmannRequires cookie*
 Title    Sedimentation von Nukleoiden aus Thymus-und Milzzellen der Ratte nach Ganzkörper-Röntgenbestrahlung Sedimentation of Nucleoids from Thymic and Splenic Cells of the Rat Following Total-Body X-Irradiation  
 Abstract    The sedimentation of nucleoids from thymic and splenic cells of rats was tested following total-body X-irradiation (TBI) with doses ranging from 24 to 1520 cGy. The principal results may be summarized as follows: 1) The nucleoid sedimentation of the cells was reduced immediately after TBI with doses of > 760 cGy. In the following postirradiation period, an enhancement of sedimentation rate has been observed which could be neutralized by addition of proteinase K to the nucleoid preparation. 2) When nucleoids were prepared 6 h after TBI with doses > 190 cGy, beside the main nucleoid band a smaller nucleoid fraction appeared in the ethidium bromide containing saccharose gradient. This fraction was of less sedimentability than the main nucleoid peak and could not be distinguished from pure, high molecular DNA. — From the present results it is suggested that the reduction of the nucleoid sedimentation immediately following high doses of TBI is the result of primary (non-repaired) DNA lesions whereas the changes detectable some hours later are due to the secondary enzymatic changes connected with the interphase death of the cells. With respect to the detection of in vivo effects of X-irradiation, the nucleoid sedimentation has to be regarded much less sensitive than some biochemical and/or cytomorphological methods. 
  Reference    Z. Naturforsch. 43c, 126—132 (1988); received August 14/October 2 1987 
  Published    1988 
  Keywords    X-Irradiation, Rat Thymic Cells, Rat Splenic Cells, Nucleoids, DNA-Protein-Cross-links 
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 TEI-XML for    default:Reihe_C/43/ZNC-1988-43c-0126.pdf 
 Identifier    ZNC-1988-43c-0126 
 Volume    43 
4Author    Karlheinz Tempel, Christina Von ZallingerRequires cookie*
 Title    Caffeine -D N A Interactions: Biochemical Investigations Comprising DNA-Repair Enzymes and Nucleic Acid Synthesis  
  Reference    Z. Naturforsch. 52c, 466—474 (1997); received March 4/May 25 1997 
  Published    1997 
  Keywords    Caffeine, Deoxyribunuclease I, 0 6-Alkylguanine-DNA Alkyltransferase, Poly(ADP-Ribose)Polymerase, Nucleic Acid Synthesis, Nucleoids 
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 TEI-XML for    default:Reihe_C/52/ZNC-1997-52c-0466.pdf 
 Identifier    ZNC-1997-52c-0466 
 Volume    52