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Chromosome aberrations in metaphase II oocytes of Chinese hamsters (Cricetulus griseus)
218
4"IH ANNUAL MEETING, ltEII)IgI. BER(,
26 HANSI~.IANN, I.*, \V. RI-ICHERT AND G. ROHRBORN,
* h ' . s t i t u t ffir H u m a n g e n e t i k ,
Universit/it G6ttingen, Nikolausbergerweg 5 a and Institut fiir Anthropologie und Humangenetik, Universit~it Heidelberg, Neuenheimerfeld 328 (W. (;ermanvl.
X-Ray-induced chromosome aberrations in oocytes of mice** II. Sensitive stages in the oogenesis Numerical and s t r u c t m a l chromosome abnormalities were induced by chemical nmtagens in mouse oocytes at different stages of oogenesis (HaNs.~.XNN, Mutation Res., 22 (IC)74) t75 ). Therefore, we investigated the question whether X-rays are able t~, induce chromosome anomalies in different stages of female meiosis. This was carried out with a correlated dose-effect s t u d y during the pre-ovulatory phase (RElCHFRT el al.). N M R I females, i o - I 2 weeks old, were treated with i. 5. i.u. pregnant mare's serum (PMS) and with 2.0 i.u. huinan chorionic gonadotrophin tH('G) for ~timulated ovulation. After ovulation at the stage of metaphase II the chromosomes were analyzed for numerical and structural anomalies. The irradiation was carried out at different stages of female meiosis, as follows. The prenatal comse was irradiated with 22.2 R on the IItl~, x3th and z7th days of gestation. The postnatal course, i.e. different stages of dictyotene, was influenced with 66.6 R by irradiation of feinales I, 3 and 6 weeks old. 3-week-old fenmles received a dose of 22.2 R as well. The ovulation and the n u m b e r of ovulated ,ocyteb per female were influenced by the X-ra\ s only in two dictvotene stages; namely with females I and 3 weeks old by 66.() R. No female ovulated tt~at had been treated previously at the age of I week, and onl\' I7°,, of those irradiated at the age ot 3 weeks. Here, too, the n u m b e r of ovulated oocvtes per female decreased to 4.4 compared with 8.~1 in the controls. A significant increase ot structural chromosolne anomalies was only observed after the irradiation of oocvte.~ from 0-week-old feinales. No increase was observed with 3-week-old felnale~, after either 66.(~ or 22.2 R. The sensitivity for X-ray-induced structural anolnalies decreased from the w e - o v u l a t o r y phase to the dicty(~tene in ~) weeks, and to 3-week-old females where no increase ove~ the ccmtr~l frequency was observed. A slight, but not significant increas;e of srructural chroinosome anomalies was observed during tl,e pre-natal course by 22.e R. No hyperploidies were observed either in controls or after irradiation of the pre-natal course and of the dictyotene stages tested. Diploid oocyte~, however, were observed after the irradiation of embryos, on the I z t h and *3th days -f gestation. ** This work was sponsored by the Deutsches Forschungsgemeinschatt. Abbreviations: HCG, h u m a n chroionic gonadotrophin; PMS, pregnant mare'~ serum.
27 HANSMANN, I.*, G. R6HRBORN AND J. NEHER, *Institut ffir Humangenetik, Univer~qtS~t Gg,ttingen, Nikolausbergerweg 5 a and Institut Itir Anthropologie und H u m a n genetik, Universit~t Heidelberg, Neuenheimerfeld 328 (\Y. Germany).
EUROPEAN ENVIRONMENTAL MUTAGEN SOCIETY
219
Chromosome aberrations in metaphase II oocytes of Chinese hamsters
( Cricetulus griseus)** The pre-ovulatory stages of mice are sensitive for the induction of numerical and structural chromosome anomalies bv chemical mutagens (R6HRBORN AND HANSMANN, H,~m2ngenetik, 13 (197I) 184; Hansmann, Mutation Res., 22 (1974) 175). Here we checked whether these findings are restricted to mice. Hormonally stimulated Chinese hamsters received triaziquone (o, o.25 or I.O mg/kg body weight) at 3 intervals before ovulation. ]'he agent was applied once in relation to HCG injection: 8 h before, at the same time as and 3 h after HCG. The chromosomes from ovulated oocytes were analyzed at the stage of metaphase I I for aneuploidies and structural anomalies. After triaziquone treatment the frequency of structural as well as of numerical anomalies was increased significantly. No hyperploidy and only I I hypoploidies were observed in 22o control oocytes. Hyperploid and diploid oocytes were only observed after treatment. The lowest frequency of structural anomalies was induced at the last stage, 3 h after HCG. This stage corresponds to the transitional phase from dictvotene to diakinesis/metaphase I. The Chinese hamsters were less sensitive than (IOI × C3H) Vz mice (ROHRBORN and Hansmann, Humangenetik, 13 (1971) 184) to the induction of structural and especially of numerical chromosome anomalies in oocytes at these pre-ovulatory stages. ** This w o r k was sponsored b y the Deutsche Forschungsgemeinschaft. Abbreviation: HCG, h u m a n chorionic gonadotrophin.
28 SEARLE, A. G., AND C. V. BEECHEY',Medical Research Council, Radiobiology Unit, Harwell, Berks (England).
Changes in sensitivity of the maturing mouse oocyte to the induction of cytogenetic damage Hybrid female mice were given doses of 0-400 rad acute X-irradiation and were paired on the same day or two weeks later, Much higher levels of dominant lethality (overall and post-implantation) were found in conceptions in the third week after treatment than in the first week. Egg fertilizability also dropped significantiy ill the third week after 400 rad compared with the first. In further experiments, the amount of visible cytological damage (e.g. multivalent configurations and fragments) in metaphase I oocytes was examined at the same two periods. About twice as much damage was found in the third week after 400 rad than in the first, though levels at IOO rad were similar. The situation at metaphase II is now being studied.
4"IH ANNUAL MEETING, ltEII)IgI. BER(,
26 HANSI~.IANN, I.*, \V. RI-ICHERT AND G. ROHRBORN,
* h ' . s t i t u t ffir H u m a n g e n e t i k ,
Universit/it G6ttingen, Nikolausbergerweg 5 a and Institut fiir Anthropologie und Humangenetik, Universit~it Heidelberg, Neuenheimerfeld 328 (W. (;ermanvl.
X-Ray-induced chromosome aberrations in oocytes of mice** II. Sensitive stages in the oogenesis Numerical and s t r u c t m a l chromosome abnormalities were induced by chemical nmtagens in mouse oocytes at different stages of oogenesis (HaNs.~.XNN, Mutation Res., 22 (IC)74) t75 ). Therefore, we investigated the question whether X-rays are able t~, induce chromosome anomalies in different stages of female meiosis. This was carried out with a correlated dose-effect s t u d y during the pre-ovulatory phase (RElCHFRT el al.). N M R I females, i o - I 2 weeks old, were treated with i. 5. i.u. pregnant mare's serum (PMS) and with 2.0 i.u. huinan chorionic gonadotrophin tH('G) for ~timulated ovulation. After ovulation at the stage of metaphase II the chromosomes were analyzed for numerical and structural anomalies. The irradiation was carried out at different stages of female meiosis, as follows. The prenatal comse was irradiated with 22.2 R on the IItl~, x3th and z7th days of gestation. The postnatal course, i.e. different stages of dictyotene, was influenced with 66.6 R by irradiation of feinales I, 3 and 6 weeks old. 3-week-old fenmles received a dose of 22.2 R as well. The ovulation and the n u m b e r of ovulated ,ocyteb per female were influenced by the X-ra\ s only in two dictvotene stages; namely with females I and 3 weeks old by 66.() R. No female ovulated tt~at had been treated previously at the age of I week, and onl\' I7°,, of those irradiated at the age ot 3 weeks. Here, too, the n u m b e r of ovulated oocvtes per female decreased to 4.4 compared with 8.~1 in the controls. A significant increase ot structural chromosolne anomalies was only observed after the irradiation of oocvte.~ from 0-week-old feinales. No increase was observed with 3-week-old felnale~, after either 66.(~ or 22.2 R. The sensitivity for X-ray-induced structural anolnalies decreased from the w e - o v u l a t o r y phase to the dicty(~tene in ~) weeks, and to 3-week-old females where no increase ove~ the ccmtr~l frequency was observed. A slight, but not significant increas;e of srructural chroinosome anomalies was observed during tl,e pre-natal course by 22.e R. No hyperploidies were observed either in controls or after irradiation of the pre-natal course and of the dictyotene stages tested. Diploid oocyte~, however, were observed after the irradiation of embryos, on the I z t h and *3th days -f gestation. ** This work was sponsored by the Deutsches Forschungsgemeinschatt. Abbreviations: HCG, h u m a n chroionic gonadotrophin; PMS, pregnant mare'~ serum.
27 HANSMANN, I.*, G. R6HRBORN AND J. NEHER, *Institut ffir Humangenetik, Univer~qtS~t Gg,ttingen, Nikolausbergerweg 5 a and Institut Itir Anthropologie und H u m a n genetik, Universit~t Heidelberg, Neuenheimerfeld 328 (\Y. Germany).
EUROPEAN ENVIRONMENTAL MUTAGEN SOCIETY
219
Chromosome aberrations in metaphase II oocytes of Chinese hamsters
( Cricetulus griseus)** The pre-ovulatory stages of mice are sensitive for the induction of numerical and structural chromosome anomalies bv chemical mutagens (R6HRBORN AND HANSMANN, H,~m2ngenetik, 13 (197I) 184; Hansmann, Mutation Res., 22 (1974) 175). Here we checked whether these findings are restricted to mice. Hormonally stimulated Chinese hamsters received triaziquone (o, o.25 or I.O mg/kg body weight) at 3 intervals before ovulation. ]'he agent was applied once in relation to HCG injection: 8 h before, at the same time as and 3 h after HCG. The chromosomes from ovulated oocytes were analyzed at the stage of metaphase I I for aneuploidies and structural anomalies. After triaziquone treatment the frequency of structural as well as of numerical anomalies was increased significantly. No hyperploidy and only I I hypoploidies were observed in 22o control oocytes. Hyperploid and diploid oocytes were only observed after treatment. The lowest frequency of structural anomalies was induced at the last stage, 3 h after HCG. This stage corresponds to the transitional phase from dictvotene to diakinesis/metaphase I. The Chinese hamsters were less sensitive than (IOI × C3H) Vz mice (ROHRBORN and Hansmann, Humangenetik, 13 (1971) 184) to the induction of structural and especially of numerical chromosome anomalies in oocytes at these pre-ovulatory stages. ** This w o r k was sponsored b y the Deutsche Forschungsgemeinschaft. Abbreviation: HCG, h u m a n chorionic gonadotrophin.
28 SEARLE, A. G., AND C. V. BEECHEY',Medical Research Council, Radiobiology Unit, Harwell, Berks (England).
Changes in sensitivity of the maturing mouse oocyte to the induction of cytogenetic damage Hybrid female mice were given doses of 0-400 rad acute X-irradiation and were paired on the same day or two weeks later, Much higher levels of dominant lethality (overall and post-implantation) were found in conceptions in the third week after treatment than in the first week. Egg fertilizability also dropped significantiy ill the third week after 400 rad compared with the first. In further experiments, the amount of visible cytological damage (e.g. multivalent configurations and fragments) in metaphase I oocytes was examined at the same two periods. About twice as much damage was found in the third week after 400 rad than in the first, though levels at IOO rad were similar. The situation at metaphase II is now being studied.