Evaluation of the genotoxic or mutagenic effects of thermal stress on cultured human lymphocytes
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Turkish Journal of Biology Turk J Biol
(2015) 39: 98-103
http://journals.tubitak.gov.tr/biology/
© TÜBİTAK
Research Article doi:10.3906/biy-1404-55
Evaluation of the genotoxic or mutagenic effects of thermal stress on
cultured human lymphocytes
1, 1 2 3 1
Hasan Basri İLA *, Mehmet TOPAKTAŞ , Mehmet ARSLAN , Mehmet BÜYÜKLEYLA , Erman Salih İSTİFLİ
1
Department of Biology, Faculty of Science and Letters, Çukurova University, Adana, Turkey
2
Department of Nursing, School of Health Sciences, Ardahan University, Ardahan, Turkey
3
Natural and Applied Science Institute, Department of Biology, Çukurova University, Adana, Turkey
Received: 15.04.2014 Accepted: 14.07.2014 Published Online: 02.01.2015 Printed: 30.01.2015
Abstract: This study was performed to determine the cytogenetic effects of short-term thermal stress in human cultured lymphocytes.
Experimental heat shock (39 °C) was performed alone or with the addition of mitomycin C (MMC) to determine the synergistic or
antagonistic effects of heat shock on genotoxicity induced by MMC. In this study, during culture periods of 72 h, human peripheral
blood lymphocytes were exposed to heat shock for specified durations (30, 60, 120, and 240 min) 24 or 48 h before harvest. According to
our results, the selected temperatures did not show genotoxic or mutagenic effects. In summary, the heat shock tested did not show any
cytogenetic effect on the cultured blood cells and did not cause significant alterations in genotoxicity induced by MMC.
Key words: Heat shock, mitomycin C, in vitro, sister chromatid exchange, chromosome aberration, micronucleus
1. Introduction lethality was observed to increase. In other words, it was
All organisms in the ecosystem are in engaged in the stated that there was an increased sensitivity to heat at pH
effort of maintaining the optimal balance in their internal 7.4 and the temperature sensitivity of the cells was low at
environment as long as they survive. Acid–base balance pH 6.9 (Li et al., 1990). While temperature applications in
and body temperature regulation are 2 of these balances. Japanese fish exposed to heat shock at various levels (34
This concept, defined for the first time by C. Bernard in °C, 36 °C, and 38 °C) produced DNA single-strand break
1865 (Cross and Albury, 1987), was named homeostasis and micronuclei, 38 °C heat inhibited cell proliferation.
by W.B. Cannon (1926). In particular, balance in the body In addition, chromosome abnormalities were detected
temperature of an organism is important for life activities. in metaphase at temperatures of 34 °C and 36 °C (Anitha
The normal internal body temperature of a human is in the et al., 2000). Similarly, in Saccharomyces cerevisiae cells
range of 36.3 to 37.3 °C (Mackowiak et al., 1992), but it is exposed to lethal heat stress (50 °C), oxidative stress was
possible for these ranges to have small deviations because observed and anaerobic cells were observed to be more
of physiological reasons. resistant to this stress than aerobic cells. It has been
Temperature changes in an organism may be caused by reported that aerobic heat stress causes degradation in
exogenous factors, but they may also depend on endogenous the mitochondrial membrane (Davidson and Schiestl,
sources like pathological and hormonal phenomena. 2001). In addition, it was stated that for triploid induction
Whatever the reason is, development of thermal stress in shrimp, which have economic importance, heat shock
(heat shock) as a result of sudden temperature changes is (29–32 °C) was very effective (Li et al., 2003). In another
unavoidable. As a result of thermal stress, transcriptional study performed on the same organism in fertilized shrimp
discrepancies and extraordinary RNA processing merge, (Fenneropenaeus chinensis), some abnormal chromosome
synthesis of mRNAs is stimulated, and various molecular behaviors (3 pronuclei and triploid embryo development)
responses like heat shock protein accumulation occur were observed in eggs exposed to 10 min of heat shock
(Wu, 1995). In one of the limited studies investigating the (30 ± 0.5 °C) (Zhang et al., 2003). The small number of
cytotoxic and genotoxic effects of thermal stress in Chinese publications on this subject and the inadequate number of
hamster ovary (CHO) cells treated with 7 mM procaine studies investigating the effects of heat shock on known
HCl under alkaline conditions, temperature-dependent mutagens acted as the inspiration for our study.
* Correspondence: milenium@cu.edu.tr
98İLA et al. / Turk J Biol
Therefore, in this study, in order to determine the rpm and then the supernatant was removed. The precipitate
genotoxic or mutagenic effect of heat shock alone or heat was homogenized, a warmed (37 °C) hypotonic solution
shock + mitomycin C (MMC) treatment on cultured (0.4% KCl) was added, and the cells were treated at 37 °C
human peripheral blood cells, in vitro sister chromatid for 5 min. At the end of the period, the suspension was
exchange (SCE), chromosomal aberration (CA), and precipitated by centrifuging the tubes for 15 min at 1200
micronuclei (MN) tests were performed. rpm and the supernatant was removed. After the addition
of a cold fixative (1:3 glacial acetic acid and methanol),
2. Materials and methods the cells were held at room temperature for 15 min and
In this study, human peripheral blood was used in vitro centrifugation was performed again for 10 min at 1200 rpm.
as the test material. Whole blood was taken from healthy This process was repeated 3 times in total. The cell pellet
volunteer blood donors (1 female and 1 male) who did in the tube was homogenized and dropped onto a cold
not smoke or use drugs, and the ages (25–30 years) of the slide from a height of 50 cm. After the slides dried under
donors were close to each other. Blood samples were taken room temperature, they were stained with a 5% Giemsa
from the donors in sterile conditions and were added to stain prepared in a Sorensen buffer and covered with
a chromosome medium (GIBCO cat. no. 12552-013) in a Entellan. In order to determine chromosome aberrations,
volume of 2.5 mL. For incubation of the cultures and heat 100 well-spread metaphase chromosomes from each tube
shock treatment, an adjustable incubator (Incucell) was were evaluated. Chromatid and chromosome gaps were
used. In order to determine the alteration caused by heat not evaluated as chromosome abnormalities (Mace et al.,
shock on the genotoxic effects of mutagens, MMC (Sigma, 1978). Mitotic index (MI) was calculated by counting 3000
CAS number 50-07-7; 0.25 µg/mL), a known mutagen, cells in total from the slides of each donor.
was used (Erboğa and İla, 2013). To investigate SCE, the fluorescence plus Giemsa
2.1. In vitro sister chromatid exchange and chromosome method, developed by Speit and Haupter (1985) and
aberration assay Speit (1984), was modified and used. From each tube, 25
Determination of the genotoxic effects of mutagens and well-spread metaphase chromosomes were evaluated for
carcinogens that may have genotoxic effects on humans is SCE average. Proliferation index (PI) was determined
possible primarily through the use of SCE and CA tests. according to the following formula by evaluating 100 total
When this type of study is planned and executed, there is a cells undergoing first, second, and third mitosis from each
requirement to follow international guidelines. Therefore, application.
this study was performed according to the International
Programme on Chemical Safety instructions published by
1 × (M1) + 2 × (M2) + 3 × (M3)
Albertini et al. (2000). PI = ,
In this study, to determine SCE and CA, the preparation 100
and cell cultures were conducted according to the methods
modified by Evans (1984) and Perry and Thomson (1984).
In order to determine the genotoxic and mutagenic effects where M1 is the number of cells undergoing the first
of heat shock producing stress, peripheral blood samples mitosis, M2 is the number of cells undergoing the second
taken from the volunteer donors were transplanted as mitosis, and M3 is the number of cells undergoing the
6 drops (0.2 mL) into chromosome media that were third mitosis.
heparinized at a 1/10 ratio in sterile cabins (Labormed). To The significances between percentages of the mean
determine SCE, the cells were incubated for 72 h at 37 ± 0.5 for SCE, CA, PI, and MI in the treated cultures and their
°C by adding fresh 10 µg/mL 5′-bromo-2′-deoxyuridine controls were evaluated using the t-test. At P < 0.05, the
solution (Sigma, CAS number: 59-14-3) into culture tubes results were interpreted as statistically significant.
at the beginning of the incubation. 2.2. In vitro micronucleus assay
For the heat shock treatment (24 or 48 h after blood The potential of heat shock to exert a genotoxic effect
transplantation), tubes were exposed to 39 °C for 30, 60, was also investigated using a micronucleus test in human
120, and 240 min in a water bath (BM 302). In a parallel peripheral lymphocytes. For the in vitro micronucleus
series, in addition to the heat shock, an effective dose of test, the method developed by Rothfuss et al. (2000) was
MMC (0.25 µg/mL) was added. In order to block mitosis modified and used. In this test, blood taken from the
in the metaphase stage, colchicine (Sigma, CAS number: same donors was added to the chromosome medium
64-86-8) was added (0.06 µg/mL) 2 h before harvesting and incubated for 68 h at 37 °C. Cytochalasin B (Sigma,
(i.e. at the 70th hour of the culture). CAS Number: 14930-96) was added at the 44th hour of
At the end of 72 h, the length of culture time employed, incubation to a final concentration of 6 µg/mL in order to
cells were precipitated by centrifugation for 5 min at 2000 block cytokinesis.
99İLA et al. / Turk J Biol
After the culture period elapsed, the tubes were Micronucleated binuclear cell percentages and NDI
centrifuged (2000 rpm for 5 min) and the precipitated values were determined in the controls and treated cultures
cells were incubated for 5 min in a warm (37 °C) hypotonic and the significance of the values between the treated and
solution. The cell culture was then centrifuged (1200 rpm control cultures was evaluated using the t-test. At P < 0.05,
for 10 min) and the precipitated cells were treated with a the results were considered statistically significant.
cold first fixative (1:5:6 glacial acetic acid, methanol, and
0.9% NaCl) for 20 min. With the second and third cold 3. Results
fixatives, treatment was repeated with the same principle
3.1. Effects of heat shock upon sister chromatid exchange
(1:5 glacial acetic acid and methanol). Finally, slides were
In this study, the findings of the group treated with heat
prepared by dropping cells onto the cold slides at close
shock alone were compared to the findings of the control
range. These slides were stained with a 5% Giemsa stain
prepared in a Sorensen buffer and covered with Entellan group. Furthermore, findings of the heat shock + MMC
to be made permanent. treated group were compared with the findings of the
In order to determine MN binuclear cells in the slides MMC control.
prepared from the blood cultures of each group, 1000 No significant differences were determined between
binuclear cells were examined. A total of 1000 cells were SCE frequencies in the control group and in the cultures
scored to determine the frequency of the cells with 1, 2, exposed to heat shock alone for various time durations (30,
3, or 4 nuclei and to calculate the nuclear division index 60, 120, and 240 min) after 24 or 48 h (P > 0.05). Although
(NDI) for the nucleus proliferation: NDI = (MI + 2MII there were increases in SCE frequencies in the cultures
+ 3MIII + 4MIV) / total, where MI, MII, MIII, and MIV where MMC was applied in addition to heat shock, no
represent the number of cells with 1–4 nuclei, respectively significant difference was observed when compared to the
(Eastmond and Tucker, 1989). MMC controls (Table 1).
Table 1. Frequency of chromosomal alterations (SCE, CA, and MN)* in human cultured blood cells treated with heat shock (HS) alone
or heat shock + MMC 24 or 48 h after blood transplantation.
Treatment
SCE ± SE mean % CA ± SE mean % MN ± SE mean %
Heat shock (39 °C) HS duration (min) Period (h)
Control (37 °C) – – 5.36 ± 0.52 3.50 ± 1.50 0.30 ± 0.10
MMC (37 °C) – 24 40.42 ± 4.30 63.50 ± 7.50 0.50 ± 0.20
HS 30 24 6.18 ± 0.18 6.74 ± 0.27 (1) 0.05 ± 0.05
HS 60 24 6.14 ± 0.34 7.00 ± 4.00 0.65 ± 0.15
HS 120 24 6.06 ± 0.58 7.00 ± 1.00 0.35 ± 0.25
HS 240 24 6.34 ± 0.30 7.00 ± 0.01 0.30 ± 0.20
HS + MMC 30 24 40.82 ± 3.58 23.50 ± 1.50 b1 1.15 ± 0.35
HS + MMC 60 24 46.90 ± 7.30 50.00 ± 12.00 0.80 ± 0.80
HS + MMC 120 24 46.68 ± 5.96 55.00 ± 13.00 1.00 ± 0.10
HS + MMC 240 24 45.94 ± 1.54 59.50 ± 0.50 0.95 ± 0.35
MMC (37 °C) – 48 100.90 ± 6.62 206.90 ± 14.60 (2) 2.85 ± 0.55
HS 30 48 6.04 ± 0.28 13.00 ± 10.00 0.35 ± 0.25
HS 60 48 4.84 ± 0.68 8.50 ± 1.50 0.20 ± 0.10
HS 120 48 5.46 ± 0.30 14.00 ± 20.00 0.15 ± 0.05
HS 240 48 5.98 ± 0.46 10.50 ± 4.50 0.40 ± 0.30
HS + MMC 30 48 92.72 ± 8.55 179.70 ± 6.60 (3) 8.45 ± 5.45
HS + MMC 60 48 97.56 ± 4.76 137.00 ± 53.50 5.65 ± 0.55
HS + MMC 120 48 100.53 ± 6.25 162.50 ± 48.50 6.25 ± 0.85
HS + MMC 240 48 99.07 ± 1.07 188.60 ± 23.60 (4) 9.05 ± 0.45 b1
*A total of 50 metaphase chromosomes were examined for the detection of SCE, a total of 200 metaphase chromosomes were examined
for CA, and a total of 2000 binuclear cells were examined for MN. Due to toxicity, a total of (1)193, (2)120, (3)195, and (4)198 cells were
scored for CA examination. b1 =significant differences compared to MMC control at P < 0.05.
100İLA et al. / Turk J Biol
3.2. Heat shock effects on chromosome aberration and in the other treatments were found not to be statistically
micronucleus significant (Table 1).
When CA and MN percentages obtained from the cultures 3.3. Effects of thermal stress on cell proliferation
exposed to heat shock alone 24 or 48 h after initiating parameters
incubation were compared with the control, no significant There were slight but not significant differences in PI and
differences were found (Table 1). No significant difference MI in the groups treated with heat shock + MMC or heat
was observed between the positive control and the group shock alone (Table 2).
where heat shock + MMC were applied, with 2 exceptions. The values calculated in the 3 applications in terms of NDI
CA frequencies obtained over 30 min in the heat shock + showed significant alterations compared to the controls.
MMC applied cultures 24 h after treatment were found to From these, in the treatment where 120 min of heat shock
be significantly lower when compared to the MMC control. was applied alone after 24 h of initiation of the culture,
Furthermore, in the group in which 240 min of heat shock the NDI value was found to be higher compared to the
+ MMC was applied 48 h after initiating of the culture, control; however, in the cultures that were exposed to 30
MN percentage was found to be significantly higher (P < and 240 min of heat shock + MMC 48 h after initiation
0.05) when compared to the positive control. Relatively of the culture, NDI was found to be significantly reduced
high CA as well as abnormal cells and MN values observed compared to its own control (Table 2).
Table 2. Evaluation of cell proliferation parameters (PI, MI, and NDI) in human cultured blood cells treated with heat shock (HS) alone
or heat shock + MMC 24 or 48 h after blood transplantation.
Treatment
PI ± SE (x) mean MI ± SE (y) mean NDI ± SE (z) mean
Heat shock (39 °C) HS duration (min) Period (h)
Control (37 °C) – – 2.430 ± 0.060 6.165 ± 0.435 1.290 ± 0.180
MMC (37 °C) – 24 1.635 ± 0.245 2.830 ± 0.100 1.450 ± 0.050
HS 30 24 2.375 ± 0.015 6.580 ± 1.050 1.475 ± 0.125
HS 60 24 2.320 ± 0.080 7.045 ± 0.485 1.305 ± 0.235
HS 120 24 2.285 ± 0.055 6.715 ± 0.215 1.535 ± 0.005 a1
HS 240 24 2.260 ± 0.090 6.860 ± 1.100 1.515 ± 0.105
HS + MMC 30 24 1.790 ± 0.090 3.815 ± 0.415 1.260 ± 0.020
HS + MMC 60 24 1.885 ± 0.155 3.180 ± 0.320 1.310 ± 0.080
HS + MMC 120 24 1.775 ± 0.065 3.095 ± 0.435 1.412 ± 0.024
HS + MMC 240 24 1.710 ± 0.130 2.715 ± 0.485 1.532 ± 0.153
MMC (37 °C) – 48 1.340 ± 0.150 2.080 ± 0.081 1.216 ± 0.655
HS 30 48 2.285 ± 0.165 5.900 ± 1.400 1.350 ± 0.079
HS 60 48 2.480 ± 0.040 6.350 ± 0.950 1.587 ± 0.127
HS 120 48 2.370 ± 0.070 5.780 ± 1.320 1.663 ± 0.137
HS 240 48 2.365 ± 0.175 6.380 ± 0.850 1.383 ± 0.097
HS + MMC 30 48 1.225 ± 0.065 2.630 ± 0.730 1.137 ± 0.003 a1b1
HS + MMC 60 48 1.300 ± 0.010 2.450 ± 0.750 1.087 ± 0.075
HS + MMC 120 48 1.310 ± 0.050 2.815 ± 0.485 1.203 ± 0.106
HS + MMC 240 48 1.280 ± 0.080 2.615 ± 0.285 1.096 ± 0.004 a1b1
A total of (x) 200, (y) 6000, and (z) 2000 cells were counted for PI, MI, and NDI, respectively. a1 = significant differences compared to control
and b1 = significant differences compared to MMC control at P < 0.05.
101İLA et al. / Turk J Biol
4. Discussion to 40 °C heat shock in the first hour of seed germination
The body heats of organisms are prone to instantaneous was reduced, and a preheating process was determined
rises owing to internal and external reasons. It is inevitable not to change nitrosomethylurea sensitivity (Mashkina
that these sudden and transient rises, occurring within the and Gus’kov, 2002). Various stresses such as heat shock
thermal tolerance limits of the organism, will trigger some induced germ cell apoptosis of Caenorhabditis elegans
molecular and cellular response mechanisms. but did not involve genotoxicity (Salinas et al., 2006).
The temperature tested in this study (39 °C) was lower However, it was reported that 30 min of preheat shock can
than the denaturation temperature of biological molecules. inhibit γH2AX foci formation induced by an alkylating
However, in some studies, it was stated that endonucleases agent, N-methyl-N′-nitro-N-nitrosoguanidine. These
(S1 nuclease) that were activated in the presence of data suggest that although heat shock might influence the
denatured DNA (a single-stranded molecule) that arose γH2AX foci formation process, it does not stimulate DNA
by increased temperature caused DNA breakages (Hunter damage in the different cells lines (including HeLa, CHL,
et al., 1976), and also that the DNA of a metaphase cell HepG2, and 293 other cells, as well as human spermatozoa)
is denatured at approximately 8–10 °C lower temperatures (Dong et al., 2007). Likewise, heat can induce γH2AX foci
than are interphase cell DNAs (Darzynkiewicz et formation in many mammalian cell lines (Takahashi et al.,
al., 1977). Expression increases in the genes of heat
2008).
shock proteins come at the beginning of the molecular
The type of alterations in the parameters related to
mechanism alterations as a response to the temperature
chromosome morphology in cells exposed to heat shock
increases (Kelley and Schlesinger, 1978). It was reported
(39 °C) for certain time periods and the alterations in the
that heat shock applied to Drosophila melanogaster caused
response of cells to heat stress + a genotoxic compound
expression of a small number of RNA transcripts; some of
(MMC) constitute the backbone of this study. The
them coded proteins (Bonner and Kerby, 1982). In CHO
cells, molecular changes such as aggregation or protein temperature level tested in this study, 39 °C, is a level
denaturation as a result of exposure to temperature and that can induce stress for humans. However, according
also radiation for various times at 43 °C caused cell cycle to our study, it would be plausible to say that the tested
delay, chromosome aberrations, and cell death events. temperature generally does not have any clastogenic effect.
In addition, the S phase was found to be more sensitive The insignificant effects shown by heat shock on various
to heat shock than the G1 phase (Dewey et al., 1990). indexes (PI, MI, and NDI) lead us to the impression that
Temperature-dependent increases in the expression levels thermal stress does not affect the cell proliferation course.
of some genes like estrogen in some salamander larvae and In summary, it was concluded that the heat shock (39 °C)
the early stages of reptile embryos were determined to play did not have any genotoxic or mutagenic effect on cultured
an important role in sex differentiation (Dournon et al., human peripheral lymphocytes, and it also failed to alter
1990). It was stated that, in CHO cells, the effect of lethality the sensitivity of lymphocytes to MMC. The clear effect of
and chromosomal damage after cisplatin treatment at 37 heat shock in this study was not apparent.
°C or 41.5 °C were similar and the S phase was detected
to be more sensitive in terms of damage affinities than the Acknowledgment
G1 phase (Krishnaswamy and Dewey, 1993). Proliferation This work was funded by the Çukurova University
activity in the root meristem cells of sunflower exposed Research Fund: FEF2011BAP4.
References
Albertini RJ, Anderson D, Douglas GR, Hagmar L, Hemminki Cannon WB (1926). Physiological regulation of normal states: some
K, Merlo F, Natarajan AT, Norppa H, Shuker DE, Tice R et tentative postulates concerning biological homeostasis. In:
al. (2000). IPCS guidelines for the monitoring of genotoxic Pettit A, editor. À Charles Richet: Ses Amis, Ses Collègues, Ses
effects of carcinogens in humans. International Programme on Élèves. Paris, France: Éditions Médicales, pp. 91–93.
Chemical Safety. Mutat Res 463: 111–172. Cross SJ, Albury WR (1987). Walter B. Cannon, L.J. Henderson, and
Anitha B, Chandra N, Gopinath PM, Durairaj G (2000). Genotoxicity the organic analogy. Osiris 3: 165–192.
evaluation of heat shock in gold fish (Carassius auratus). Mutat Darzynkiewicz Z, Traganos F, Sharpless T, Melamed MR (1977).
Res 469: 1–8. Different sensitivity of DNA in situ in interphase and metaphase
Bonner JJ, Kerby RL (1982). RNA polymerase II transcribes all of chromatin to heat denaturation. J Cell Biol 73: 128–138.
the heat shock induced genes of Drosophila melanogaster.
Chromosoma 85: 93–108.
102İLA et al. / Turk J Biol
Davidson JF, Schiestl RH (2001). Cytotoxic and genotoxic Mace ML Jr, Daskal Y, Wray W (1978). Scanning-electron microscopy
consequences of heat stress are dependent on the presence of of chromosome aberrations. Mutat Res 52: 199–206.
oxygen in Saccharomyces cerevisiae. J Bacteriol 183: 4580–4587. Mackowiak PA, Wasserman SS, Levine MM (1992). A critical
Dewey WC, Li XL, Wong RS (1990). Cell killing, chromosomal appraisal of 98.6°F, the upper limit of the normal body
aberrations, and division delay as thermal sensitivity is temperature, and other legacies of Carl Reinhold August
modified during the cell cycle. Radiat Res 122: 268–274. Wunderlich. JAMA 268: 1578–1580.
Dong Z, Hu H, Chen W, Li Z, Liu G, Yang J (2007). Heat shock does Mashkina EV, Gus’kov EP (2002). Cytogenetic effect of temperature
not induce γH2AX foci formation but protects cells from on the sunflower varieties. Tsitologiia 44: 1220–1226.
N-methyl-N′-nitro-N-nitrosoguanidine-induced genotoxicity. Perry P, Thomson EJ (1984). The methodology of sister chromatid
Mutat Res 629: 40–48. exchanges. In: Kilbey BJ, Legator M, Nicholson W, Ramel C,
Dournon C, Houillon C, Pieau C (1990). Temperature sex-reversal in editors. Handbook of Mutagenicity Test Procedures. 2nd ed.
amphibians and reptiles. Int J Dev Biol 34: 81–92. Amsterdam, the Netherlands: Elsevier Science Publishers, pp.
495–529.
Eastmond DA, Tucker JD (1989). Identification of aneuploidy-
inducing agents using cytokinesis blocked human lymphocytes Rothfuss A, Schutz P, Bochum S, Volm T, Eberhardt E, Kreienberg
and an antikinetochore antibody. Environ Mol Mutagen 13: R, Vogel W, Speit G (2000). Induced micronucleus frequencies
34–43. in peripheral lymphocytes as a screening test for carriers of
a BRCA1 mutation in breast cancer families. Cancer Res 60:
Erboğa H, İla HB (2013). Cytogenetic effects of endogenous sex
390–394.
hormones depending on smoking habits. Turk J Biol 37: 709–
715. Salinas LS, Maldonado E, Navarro RE (2006). Stress-induced germ
cell apoptosis by a p53 independent pathway in Caenorhabditis
Evans HJ (1984). Human peripheral blood lymphocytes for the
elegans. Cell Death Differ 13: 2129–2139.
analysis of chromosome aberrations in mutagen tests. In: Kilbey
BJ, Legator M, Nicholson W, Ramel C, editors. Handbook Speit G (1984). Considerations on the mechanism of differential
of Mutagenicity Test Procedures. 2nd ed. Amsterdam, the Giemsa staining of BrdU-substituted chromosomes. Hum
Netherlands: Elsevier Science Publishers, pp. 405–427. Genet 67: 264–269.
Hunter JD, Bodner AJ, Hatch FT, Balhorn RL, Mazrimas JA, McQueen Speit G, Haupter S (1985). On the mechanism of differential Giemsa
AP, Gledhill BL (1976). Single-strand nuclease action on heat- staining of bromodeoxyuridine-substituted chromosomes. II.
denatured spermiogenic chromatin. J Histochem Cytochem Differences between the demonstration of sister chromatid
24: 901–907. differentiation and replication patterns. Hum Genet 70: 126–
129.
Kelley PM, Schlesinger MJ (1978). The effect of amino acid analogues
and heat shock on gene expression in chicken embryo Takahashi A, Mori E, Somakos GI, Ohnishi K, Ohnishi T (2008).
fibroblasts. Cell 15: 1277–1286. Heat induces γH2AX foci formation in mammalian cells.
Mutat Res 656: 88–92.
Krishnaswamy G, Dewey WC (1993). Cell killing and chromosomal
aberrations induced in Chinese hamster ovary cells by treating Wu C (1995). Heat shock transcription factors: structure and
with cisplatin at 41.5°C during the G1 or late S phase. Cancer regulation. Annu Rev Cell Dev Biol 11: 441–469.
Res 53: 1239–1243. Zhang X, Lu F, Xiang J (2003). Chromosome behavior of heat
Li FH, Xiang JH, Zhou LH, Wu CG, Zhang XJ (2003). Optimization shock induced triploid in Fenneropenaeus chinensis. Chinese J
of triploid induction by heat shock in Chinese shrimp Oceanol Limn 21: 222–228.
Fenneropenaeus chinensis. Aquaculture 219: 221–231.
Li XL, Wang ZH, Chu GL, Dewey WC (1990). Effects of pH on heat
sensitization of mammalian cells with procaine hydrochloride.
Int J Radiat Oncol Biol Phys 18: 933–935.
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