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Study of time response of fission neutrons induced apoptosis in murine thymocytes and its molecular mechanism

Yuan, Bin; Sun, Jianmin LU ; Hou, Chunmei; Liu, Hongtao; Xue, Wenchang; Li, Liang and Wang, Baoqin (2000) In Bulletin of Academy of Military Medical Sciences 24. p.184-184
Abstract
Objective:To study the time response of fission neutrons induced apoptosis in murine thymocytes with 60 Co γ-rays as the reference radiation and to investigate preliminarily its molecular mechanism. Methods: Apoptosis induction was detected by means of DNA gel electrophoresis, morphologic assay, flow cytometric (FCM) analysis and diphenylamine(DPA) method respectively. p53 and bcl-2 gene expressions were studied by dot hybridization with digoxigenin labeled probes. Results: When mice was exposed to 2.5 Gy of fission neutrons, DNA ladders of thymocytes were detected at different time points during 2-24 hours post-irradiation. Thymocytes with typical morphological characteristics of apoptosis were also observed. Time response curves were... (More)
Objective:To study the time response of fission neutrons induced apoptosis in murine thymocytes with 60 Co γ-rays as the reference radiation and to investigate preliminarily its molecular mechanism. Methods: Apoptosis induction was detected by means of DNA gel electrophoresis, morphologic assay, flow cytometric (FCM) analysis and diphenylamine(DPA) method respectively. p53 and bcl-2 gene expressions were studied by dot hybridization with digoxigenin labeled probes. Results: When mice was exposed to 2.5 Gy of fission neutrons, DNA ladders of thymocytes were detected at different time points during 2-24 hours post-irradiation. Thymocytes with typical morphological characteristics of apoptosis were also observed. Time response curves were obtained with methods of morphologic assay, FCM analysis and DPA method. The percentage of thymocytes undergoing apoptosis steeply increased during the first 6 hours post-irradiation,reached the peak levels at 8-10 hours,began to decrease 12 hours later and significantly decreased by 24 hours as compared with the level at 4-12 hours (P<0.05)but was still slightly higher than the normal level. Similar curves were obtained by using three different methods. Time response curve after exposure to 5.0 Gy of γ- irradiation was characterized by an initial slow increase in the number of apoptotic thymocytes during the first 6 hours post-irradiation. In addition, DNA ladders were not detected at 24 hours post-irradiation. After exposure to 2.5 Gy of fission neutrons irradiation, p53 gene expression at 2, 4, 12 and 24 hours post-irradiation were obviously higher than in control (P<0.05 or P<0.01),while bcl-2 gene expression at different time points during 2-24 hours post-irradiation decreased obviously (P<0.01)in comparison with non-irradiated control. Conclusions: Apoptosis of murine thymocytes can be induced in mice exposed to 2.5 Gy of fission neutrons. The rules of time response after fission neutrons irradiation for 2.5 Gy is similar to γ-ray irradiation for 5.0 Gy. However,apoptosis induced by fission neutrons irradiation increases were rapidly and lasts longer than that induced by γ-irradiation. These results indicate that damage to murine immune tissues induced by fission neutrons is more severe and difficult for discovery than that induced by γ-rays. The results of examination of gene expression by dot hybridization show that p53 and bcl-2 genes are involved in the regulation of fission neutrons induced apoptosis in thymocytes. (Less)
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published
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keywords
fission neutron, apoptosis, thymocyte, time response, dot hybridization, gene expression
in
Bulletin of Academy of Military Medical Sciences
volume
24
pages
184 - 184
publisher
Academy of Military Medical Sciences
ISSN
1000-5501
language
Chinese
LU publication?
no
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03653c44-1d0d-42cd-b090-2e9acf0dbae2 (old id 1118419)
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http://www.wanfangdata.com.cn/qikan/periodical.articles/jsyxkxyyk/jsyx2000/0003/000307.htm
date added to LUP
2008-06-30 14:40:24
date last changed
2016-06-29 08:55:36
@article{03653c44-1d0d-42cd-b090-2e9acf0dbae2,
  abstract     = {Objective:To study the time response of fission neutrons induced apoptosis in murine thymocytes with 60 Co γ-rays as the reference radiation and to investigate preliminarily its molecular mechanism. Methods: Apoptosis induction was detected by means of DNA gel electrophoresis, morphologic assay, flow cytometric (FCM) analysis and diphenylamine(DPA) method respectively. p53 and bcl-2 gene expressions were studied by dot hybridization with digoxigenin labeled probes. Results: When mice was exposed to 2.5 Gy of fission neutrons, DNA ladders of thymocytes were detected at different time points during 2-24 hours post-irradiation. Thymocytes with typical morphological characteristics of apoptosis were also observed. Time response curves were obtained with methods of morphologic assay, FCM analysis and DPA method. The percentage of thymocytes undergoing apoptosis steeply increased during the first 6 hours post-irradiation,reached the peak levels at 8-10 hours,began to decrease 12 hours later and significantly decreased by 24 hours as compared with the level at 4-12 hours (P<0.05)but was still slightly higher than the normal level. Similar curves were obtained by using three different methods. Time response curve after exposure to 5.0 Gy of γ- irradiation was characterized by an initial slow increase in the number of apoptotic thymocytes during the first 6 hours post-irradiation. In addition, DNA ladders were not detected at 24 hours post-irradiation. After exposure to 2.5 Gy of fission neutrons irradiation, p53 gene expression at 2, 4, 12 and 24 hours post-irradiation were obviously higher than in control (P&lt;0.05 or P&lt;0.01),while bcl-2 gene expression at different time points during 2-24 hours post-irradiation decreased obviously (P&lt;0.01)in comparison with non-irradiated control. Conclusions: Apoptosis of murine thymocytes can be induced in mice exposed to 2.5 Gy of fission neutrons. The rules of time response after fission neutrons irradiation for 2.5 Gy is similar to γ-ray irradiation for 5.0 Gy. However,apoptosis induced by fission neutrons irradiation increases were rapidly and lasts longer than that induced by γ-irradiation. These results indicate that damage to murine immune tissues induced by fission neutrons is more severe and difficult for discovery than that induced by γ-rays. The results of examination of gene expression by dot hybridization show that p53 and bcl-2 genes are involved in the regulation of fission neutrons induced apoptosis in thymocytes.},
  author       = {Yuan, Bin and Sun, Jianmin and Hou, Chunmei and Liu, Hongtao and Xue, Wenchang and Li, Liang and Wang, Baoqin},
  issn         = {1000-5501},
  keyword      = {fission neutron,apoptosis,thymocyte,time response,dot hybridization,gene expression},
  language     = {chi},
  pages        = {184--184},
  publisher    = {Academy of Military Medical Sciences},
  series       = {Bulletin of Academy of Military Medical Sciences},
  title        = {Study of time response of fission neutrons induced apoptosis in murine thymocytes and its molecular mechanism},
  volume       = {24},
  year         = {2000},
}