Persistent organic pollutants in Finnish reindeer (Rangifer tarandus tarandus L.) and moose (Alces alces)

Summary

Polychlorinated dibenzo-p-dioxins (PCDDs), dibenzofurans (PCDFs), polychlorinated biphenyls (PCBs), and polybrominated diphenyl ethers (PBDEs) in Finnish semi-domesticated reindeer (Rangifer tarandus tarandus L.)

To explore the concentrations and dynamics of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs), polychlorinated biphenyls (PCBs) and polybrominated diphenyl ethers (PBDEs) in Finnish semi-domesticated reindeer (Rangifer tarandus tarandus L.) the reindeer milk and tissue samples were collected from the sub-arctic northern Finland. Reindeer milk's PCB sum (1.20 ng g(-1) wet weight) and PCDD/F sum (0.70 pg g(-1) ww) in autumn were higher than in summer (PCBs 0.50 ng g(-1) ww and PCDD/Fs 0.20 pg g(-1) ww). The mean fat content in autumn milk (26%) was significantly higher than in summer (10%). Concentrations in reindeer milk were generally far below 50% of that in adult reindeer body burden. However, the bioaccumulation factors were multiple in milk/reindeer calf ratio and that aroused the question of other important exposure routes than lactation. The muscle and liver of reindeer calves had higher PCDD/F and PCB concentrations than adult animals that possibly indicate the significance of transfer of these compounds from dam to calf through lactation and placenta. However, PBDE concentrations were higher in adult reindeer, especially in liver. In addition, reindeer liver seems to have a special feature to collect highly toxic PCDD/Fs, although the PCB sum concentrations (range from 0.33 to 1.69 ng g(-1) wet weight) were clearly higher than the sums of PCDD/Fs (range from 3.78 to 39.2 pg g(-1) ww). Stillborn reindeer calves represented individuals who had got their PCDD/F, PCB and PBDE load only via the placenta. Concentrations in muscle and brown adipose tissue samples did not indicate dependency on fat content. Obviously effective placental transfer of PCBs and PBDEs from reindeer dam to foetus was seen in this study.

Polychlorinated dibenzo-p-dioxins, dibenzofurans, and polychlorinated biphenyls in semi-domesticated reindeer (Rangifer tarandus tarandus) and wild moose (Alces alces) meat in Finland

Semi-domesticated reindeer and wild moose meat samples were analyzed for polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs), and polychlorinated biphenyls (PCBs). Both calves and adults were studied. Individual reindeer and moose meat samples and pooled reindeer calf meat samples were collected from the northern, the middle, and the southern reindeer herding regions in Finland. Samples represented the edible parts of carcasses. In individual samples of reindeer the fat based WHO-PCDD/F-PCB-TEQ concentration was on average 3.2pgg(-1) in calves and 2.3pgg(-1) in adults. In moose calves the fat based WHO-PCDD/F-PCB-TEQ concentration (1.9pgg(-1)) was lower than in reindeer calves. WHO-PCDD/F-PCB-TEQ concentration in the adult moose samples was equal as in the adult reindeer samples. The mean fat based WHO-PCDD/F-PCB-TEQ concentration was highest in reindeer calf samples from the middle region. These samples contained also the highest content of fat. Individual samples of reindeer contained on average more WHO-PCB-TEQ than WHO-PCDD/F-TEQ, while the opposite was true for moose samples, and also samples of adult reindeer from the southern area. The contributions of PCDD/Fs and PCBs to the total TEQ were similar in the reindeer calves' pooled samples which were collected from more western regions than individual samples.

Detection of germ cell mutagenicity of trophosphamide by the spermatid micronucleus test in the rat

The effects of the antineoplastic drug trophosphamide (TP) on male rat germ cells were examined with the spermatid micronucleus test (SMNT). We used the microdissection technique in order to isolate stage I of the seminiferous epithelial cycle, where the cells that have just passed the meiotic divisions can be found. Micronuclei (MN) were scored at different time-points after TP treatment at dose levels of 25 and 50 mg/kg. An induction of MN was detected in cells exposed at preleptotene (18 and 19 days) and late pachytene (3 days), as well as at the diplotene-diakinesis stage (1 day). The dose-response for MN induction was linear at all time intervals studied, except for 18 days time point. The highest frequency of MN (5.20 +/- 0.57/1000 spermatids) could be found with the lower TP dose at 18 days, corresponding to exposed preleptotene spermatocytes and reflecting S-dependent clastogenicity. While a significant increase in MN could only be detected in exposed preleptotene spermatocytes with the lower TP dose, the higher dose level also induced MN significantly in late pachytene and the diplotene-diakinesis stage. DNA flow cytometry at 18 days showed cytotoxicity of TP to exposed primary spermatocytes at pachytene, but no cytotoxicity to the preleptotene spermatocytes that exhibited a significant MN induction. The results show that the SMNT using the stage-I-specific examination of the rat seminiferous epithelium can detect the germ cell mutagenicity of TP and gives further evidence of the usefulness of this technique in the testing of chemicals for genotoxic effects in male germ cells.

The spermatid micronucleus test with the dissection technique detects the germ cell mutagenicity of acrylamide in rat meiotic cells

As a part of the development and validation of the spermatid micronucleus test (SMNT) in the project 'Detection of Germ Cell Mutagens' sponsored by the CEC we studied the mutagenicity of acrylamide (AA) and mitomycin C (MMC). Of two alternative techniques, we used the 'dissection technique' based on microdissection of seminiferous tubules offering a narrow window for evaluation of cell stage sensitivity, and including DNA-specific staining and scoring. AA given as a single injection of 50 or 100 mg/kg did not significantly increase MN frequencies. When a subchronic treatment (4 x 50 mg/kg) was given, a significant increase over background was observed 18 and 19 days after the last injection, indicating genotoxic activity in preleptotene spermatocytes and late spermatogonial stages. MMC given as single injections of 0.5 or 1.0 mg/kg increased MN frequencies significantly 17, 18, 19 and 20 days after treatment as a result of clastogenicity in S phase cells. DNA flow cytometry did not show cytotoxicity of AA to preleptotene spermatocytes, but a small decrease in the numbers of stem cells. If spindle disturbances are caused by AA, as suggested, they were not detectable by induction of spermatid MN in vivo 1 or 3 days after treatment or by treatment with AA of cultured segments of seminiferous tubules undergoing meiotic divisions in vitro. In conclusion, the SMNT with the dissection technique is able to show the germ cell clastogenicity of AA and MMC. AA was observed to have a much weaker MN inducing potency than MMC.

Etoposide (VP-16) is a potent inducer of micronuclei in male rat meiosis: spermatid micronucleus test and DNA flow cytometry after etoposide treatment

The genotoxic and cytotoxic effects of etoposide (VP-16), a topoisomerase II inhibitor, on male rat spermatogenic cells were studied by analysing induction of micronuclei during meiosis. Micronuclei (MN) were scored in early spermatids after different time intervals corresponding to exposure of different stages of meiotic prophase. Etoposide had a strong effect on diplotene-diakinesis I cells harvested 1 day after exposure, and a significant effect also on late pachytene cells harvested 3 days after exposure. The effect at 18 days corresponding to exposure of preleptotene stage of meiosis (S-phase) was weaker but also statistically significant. Adriamycin was used as a positive control in this study. The results indicate a different mechanism of action of etoposide compared with adriamycin and other chemicals studied previously with the spermatid micronucleus test. DNA flow cytometry was carried out to assess cytotoxic damage at the same time intervals (1, 3, and 18 days after treatment) at stages I and VII of the seminiferous epithelial cycle allowing a study of cytotoxicity to different spermatogenic cell stages. Damage of differentiating spermatogonia was observed by a decrease in the cell numbers of the 2C peak 1 and 3 days after treatment and by a reduction of the number of 4C cells (primary spermatocytes) 18 d after etoposide treatment. Adriamycin also killed differentiating spermatogonia. Since the cell population which showed a high induction of MN by etoposide was not reduced in number, the genotoxic effect is remarkable. We conclude that etoposide is a potent inducer of genotoxicity and patients treated with this agent during cancer chemotherapy are at a risk of genetic damage.