scholarly journals The Rejoining Time of Chromatid Breaks Induced by Gamma Radiation in Vicia faba Root Tips at 3 °C

1960 ◽  
Vol 7 (1) ◽  
pp. 79-85 ◽  
Author(s):  
J. R. K. Savage ◽  
G. J. Neary ◽  
H. J. Evans
Keyword(s):  
Root Growth ◽  
Vicia Faba ◽  
Low Dose ◽  
Root Meristem ◽  
Root Tips ◽  
Dose Rates ◽  
Low Dose Rate ◽  
Chromatid Aberration ◽  
Γ Rays ◽  
Chromatid Aberrations

The observation was made previously that the reduction in radiosensitivity in Vicia faba (as measured by postirradiation root growth) by prolonging the exposure time from about 10 minutes to 24 hours is much less marked at 3°C. than at 19°C. If chromosome damage is mainly responsible for the reduced root growth, this observation might be explained by a smaller drop in the "two-hit" aberration component, resulting from an increased time for which breaks are available for rejoining at 3°C. This hypothesis was tested by comparing chromatid aberration frequencies in root meristem cells produced by 105 rads of 60Co γ rays, given at dose rates of 19.4 and 0.073 rads per minute. Beans were maintained in aerated water at 2°C. prior to and during irradiation, and at this temperature the rate of development of cells was such that the two different exposure times both occupied a period during which the cell sensitivity was approximately constant. Immediately subsequent to irradiation, the roots were returned to 19°C. and examined cytologically. All chromatid aberrations were less frequent after low dose rate treatment, but only the chromatid interchange reduction was significant. The average time for which breaks are available for reunion, calculated from Lea's G function, was found to be 12 hours (95 per cent C.L. 6 to 24 hours).

Adaptive Responses to Low-Dose/Low-Dose-Rate γ Rays in Normal Human Fibroblasts: The Role of Growth Architecture and Oxidative Metabolism

2006 ◽  
Vol 166 (6) ◽  
pp. 849-857 ◽  
Author(s):  
Sonia M. de Toledo ◽  
Nesrin Asaad ◽  
Perumal Venkatachalam ◽  
Ling Li ◽  
Roger W. Howell ◽  
...  
Keyword(s):  
Dose Rate ◽  
Oxidative Metabolism ◽  
Low Dose ◽  
Human Fibroblasts ◽  
Adaptive Responses ◽  
Low Dose Rate ◽  
Normal Human ◽  
Γ Rays

Adiposity in Female B6C3F1 Mice Continuously Irradiated with Low-Dose-Rate γ Rays

2010 ◽  
Vol 173 (3) ◽  
pp. 333-341 ◽  
Author(s):  
S. Nakamura ◽  
I. B. Tanaka ◽  
S. Tanaka ◽  
K. Nakaya ◽  
N. Sakata ◽  
...  
Keyword(s):  
Dose Rate ◽  
Low Dose ◽  
Low Dose Rate ◽  
B6c3f1 Mice ◽  
Γ Rays

scholarly journals Radioprotective effects of cimetidine on rats irradiated by long-term, low-dose-rate neutrons and 60Co γ-rays

2017 ◽  
Vol 4 (1) ◽  
Author(s):  
Ding-Wen Jiang ◽  
Qing-Rong Wang ◽  
Xian-Rong Shen ◽  
Ying He ◽  
Tian-Tian Qian ◽  
...  
Keyword(s):  
Dose Rate ◽  
Low Dose ◽  
Low Dose Rate ◽  
Γ Rays

Dose-Rate Effectiveness for Unstable-Type Chromosome Aberrations Detected in Mice after Continuous Irradiation with Low-Dose-Rate γ Rays

2009 ◽  
Vol 171 (3) ◽  
pp. 290-301 ◽  
Author(s):  
Kimio Tanaka ◽  
Atsushi Kohda ◽  
Kenichi Satoh ◽  
Takuo Toyokawa ◽  
Kazuaki Ichinohe ◽  
...  
Keyword(s):  
Dose Rate ◽  
Chromosome Aberrations ◽  
Low Dose ◽  
Continuous Irradiation ◽  
Low Dose Rate ◽  
Γ Rays ◽  
Unstable Type ◽  
Type Chromosome

scholarly journals Transcription Factor-recognition Sequences Potentially Involved in Modulation of Gene Expression after Exposure to Low-dose-rate γ-rays in the Mouse Liver

2011 ◽  
Vol 52 (2) ◽  
pp. 249-256 ◽  
Author(s):  
Guillaume VARES ◽  
Yoshihiko UEHARA ◽  
Tetsuya ONO ◽  
Tetsuo NAKAJIMA ◽  
Bing WANG ◽  
...  
Keyword(s):  
Gene Expression ◽  
Transcription Factor ◽  
Dose Rate ◽  
Mouse Liver ◽  
Low Dose ◽  
Low Dose Rate ◽  
Γ Rays ◽  
Modulation Of Gene Expression

scholarly journals The microtubule-associated protein CLASP is translationally-regulated in light-dependent root apical meristem growth

2020 ◽  
Author(s):  
Laryssa Halat ◽  
Katherine Gyte ◽  
Geoffrey Wasteneys
Keyword(s):  
Root Growth ◽  
Apical Meristem ◽  
Root Meristem ◽  
Growth Promotion ◽  
Root Apical Meristem ◽  
Root Tips ◽  
Protein Levels ◽  
Hormone Transport ◽  
Dividing Cells ◽  
Root Growth Promotion

ABSTRACTThe ability for plant growth to be optimized, either in the light or dark, depends on the intricate balance between cell division and differentiation in specialized regions called meristems. When Arabidopsis thaliana seedlings are grown in the dark, hypocotyl elongation is promoted, whereas root growth is greatly reduced as a result of changes in hormone transport and a reduction in meristematic cell proliferation. Previous work showed that the microtubule-associated protein CLASP sustains root apical meristem (RAM) size by influencing microtubule (MT) organization and by modulating the brassinosteroid (BR) signalling pathway. Here, we investigated whether CLASP is involved in light-dependent root growth promotion, since dark-grown seedlings have reduced RAM activity that is observed in the clasp-1 null mutant. We showed that CLASP protein levels were greatly reduced in the root tips of dark-grown seedlings, which could be reversed by exposing plants to light. We confirmed that removing seedlings from the light led to a discernible shift in MT organization from bundled arrays, which are prominent in dividing cells, to transverse orientations typically observed in cells that have exited the meristem. BR receptors and auxin transporters, both of which are sustained by CLASP, were largely degraded in the dark. Interestingly, we found that despite the lack of protein, CLASP transcript levels were higher in dark-grown root tips. Together, these findings uncover a mechanism that sustains meristem homeostasis through CLASP, and advances our understanding of how roots modulate their growth according to the amount of light and nutrients perceived by the plant.One Sentence SummaryThe microtubule-associated protein CLASP is regulated at the translational level when root meristem growth is inhibited in dark-grown plants.

scholarly journals Perturbed transcriptional profiles after chronic low dose rate radiation in mice

PLoS ONE ◽  
2021 ◽  
Vol 16 (8) ◽  
pp. e0256667
Author(s):  
Hildegunn Dahl ◽  
Dag M. Eide ◽  
Torstein Tengs ◽  
Nur Duale ◽  
Jorke H. Kamstra ◽  
...  
Keyword(s):  
Ionizing Radiation ◽  
Dose Rate ◽  
Low Dose ◽  
High Dose Rate ◽  
High Dose ◽  
Transcriptional Responses ◽  
Transcriptional Profiles ◽  
Dose Rates ◽  
Low Dose Rate ◽  
Genome Wide

Adverse health outcomes of ionizing radiation given chronically at low dose rates are highly debated, a controversy also relevant for other stressors. Increased knowledge is needed for a more comprehensive understanding of the damaging potential of ionizing radiation from all dose rates and doses. There is a lack of relevant low dose rate data that is partly ascribed to the rarity of exposure facilities allowing chronic low dose rate exposures. Using the FIGARO facility, we assessed early (one day post-radiation) and late (recovery time of 100–200 days) hepatic genome-wide transcriptional profiles in male mice of two strains (CBA/CaOlaHsd and C57BL/6NHsd) exposed chronically to a low dose rate (2.5 mGy/h; 1200h, LDR), a mid-dose rate (10 mGy/h; 300h, MDR) and acutely to a high dose rate (100 mGy/h; 30h, HDR) of gamma irradiation, given to an equivalent total dose of 3 Gy. Dose-rate and strain-specific transcriptional responses were identified. Differently modulated transcriptional responses across all dose rate exposure groups were evident by the representation of functional biological pathways. Evidence of changed epigenetic regulation (global DNA methylation) was not detected. A period of recovery markedly reduced the number of differentially expressed genes. Using enrichment analysis to identify the functional significance of the modulated genes, perturbed signaling pathways associated with both cancer and non-cancer effects were observed, such as lipid metabolism and inflammation. These pathways were seen after chronic low dose rate and were not restricted to the acute high dose rate exposure. The transcriptional response induced by chronic low dose rate ionizing radiation suggests contribution to conditions such as cardiovascular diseases. We contribute with novel genome wide transcriptional data highlighting dose-rate-specific radiation responses and emphasize the importance of considering both dose rate, duration of exposure, and variability in susceptibility when assessing risks from ionizing radiation.

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