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1999 (1)
1996 (1)
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