RESUMO
Activated human neutrophils produce a fibrillar DNA network [neutrophil extracellular traps (NETs)] for entrapping and killing bacteria, fungi, protozoa and viruses. Our results suggest that the neutrophil extracellular traps show a resistant amyloidogenic backbone utilized for addressing reputed proteins and DNA against the non-self. The formation of amyloid fibrils in neutrophils is regulated by the imbalance of reactive oxygen species (ROS) in the cytoplasm. The intensity and source of the ROS signal is determinant for promoting stress-associated responses such as amyloidogenesis and closely related events: autophagy, exosome release, activation of the adrenocorticotrophin hormone/α-melanocyte-stimulating hormone (ACTH/α-MSH) loop and synthesis of specific cytokines. These interconnected responses in human activated neutrophils, that have been evaluated from a morphofunctional and quantitative viewpoint, represent primitive, but potent, innate defence mechanisms. In invertebrates, circulating phagocytic immune cells, when activated, show responses similar to those described previously for activated human neutrophils. Invertebrate cells within endoplasmic reticulum cisternae produce a fibrillar material which is then assembled into an amyloidogenic scaffold utilized to convey melanin close to the invader. These findings, in consideration to the critical role played by NET in the development of several pathologies, could explain the structural resistance of these scaffolds and could provide the basis for developing new diagnostic and therapeutic approaches in immunomediated diseases in which the innate branch of the immune system has a pivotal role.
Assuntos
Amiloide/metabolismo , Armadilhas Extracelulares/imunologia , Armadilhas Extracelulares/fisiologia , Ativação de Neutrófilo , Neutrófilos/imunologia , Hormônio Adrenocorticotrópico/fisiologia , Animais , Autofagia , Exossomos/fisiologia , Humanos , Imunidade Inata , Neutrófilos/ultraestrutura , Espécies Reativas de Oxigênio , alfa-MSH/metabolismoRESUMO
(C57BL/Cne x C3H/Cne)F1 mice were splenectomized at 3, 9, or 19 months of age (males) or at 4 months of age (females) and observed until spontaneous death. Their mean lifespans were only slightly increased by splenectomy, but the final incidence of and age-specific death rate from reticulum cell sarcoma (RCS) were significantly decreased; the latter effect was associated with prolonged latency times of neoplastic expression. Splenectomized females had a more pronounced decrease in incidence of and rate of death from RCS than did males. Lethally irradiated male mice were inoculated with isogeneic spleen cells from young (3 mo of age) or old (12-18 mo of age) untreated male donors, and the animals surviving acute radiation effects were also observed until spontaneous death. In spite of the fact that the mean life-spans of the spleen-repopulated animals were slightly shortened, age-specific death rate analysis showed that the rate of RCS incidence approached that of untreated controls of comparable ages. The combined results of splenectomy and spleen cell transplantation strongly indicated that some cells in the spleens of these mice have a high probability of being transformed into potentially neoplastic progenitor cells with long latency between cell transformation and overt tumor growth.
Assuntos
Linfoma não Hodgkin/etiologia , Baço/fisiologia , Fatores Etários , Animais , Transformação Celular Neoplásica , Feminino , Masculino , Camundongos , Camundongos Endogâmicos , Quimera por Radiação , Sarcoma Experimental/etiologia , Baço/transplante , Esplenectomia , Transplante IsogênicoRESUMO
The average final incidence of reticulum cell sarcoma (RCS) in untreated control (C57BL/Cnefemale X C3H/Cnemale)F1 male mice was 57% and was not significantly changed by single acute whole-body doses of X-rays up to 400 rads. Higher doses sharply decreased this incidence to very low levels. In a syngeneic chimera system, however, irradiation (400 rads) of bone marrow prior to transplantation significantly increased the frequency and rate of RCS relative to transplantation of unirradiated marrow. An endogenous repopulating system was tested; marrow was irradiated in situ by a limb-shielding technique. The results indicated a biphasic dose-incidence curve with a peak at 500 rads. The rising part of the curve was in agreement with and extended the conclusion from the exogenous system, whereas the descending portion at higher doses paralleled the trend observed in the whole-body X-irradiated animals. Finally, the irradiation of two hind legs resulted in a higher frequency of RCS than did irradiation of only one leg at the same dose levels.
Assuntos
Medula Óssea/efeitos da radiação , Linfoma não Hodgkin/etiologia , Neoplasias Induzidas por Radiação/etiologia , Animais , Transplante de Medula Óssea , Quimera , Relação Dose-Resposta à Radiação , Masculino , Camundongos , Camundongos Endogâmicos , Sarcoma Experimental/etiologia , Transplante IsogênicoRESUMO
Biozzi mice selected for high (Hi) or low (Lo) responsiveness to phytohemagglutinin (PHA) have been followed for their entire life-span to examine their pathology at death. Spontaneous lymphomas were found to exhibit higher incidence and faster development in Lo/PHA than in Hi/PHA females, whereas a similar difference between the two lines did not attain the level of statistical significance in male mice. The incidence of solid tumors was higher in Lo/PHA than in Hi/PHA males but the same in females of the two lines, yet the probability of dying from solid tumors was slightly increased in Lo/PHA mice of both sexes. All these results indicate that T-cell-mediated immunity influences mainly the spontaneous incidence of lymphomas and, to a lesser degree, the appearance of other solid tumors.
Assuntos
Linfoma/veterinária , Camundongos/imunologia , Fito-Hemaglutininas/farmacologia , Doenças dos Roedores/imunologia , Linfócitos T/imunologia , Animais , Broncopneumonia/epidemiologia , Broncopneumonia/veterinária , Feminino , Longevidade , Linfoma/epidemiologia , Linfoma/genética , Linfoma/imunologia , Masculino , Camundongos/genética , Neoplasias/epidemiologia , Neoplasias/veterinária , Doenças dos Roedores/epidemiologia , Doenças dos Roedores/genética , Fatores SexuaisRESUMO
Transplantation of harderian gland cells from CBA/-Cne mice into the fat pad of isogenic recipients was used for a quantitative in vivo study of cell survival and risk of transformation after x-ray irradiation (1-7 Gy). A survival curve for gland cells was generated in vivo with a D0 of 1.83 Gy and an extrapolation number of 7.23. Subsequently, the dose-response curve for lesions observed in nodules after cell transplantation was compared with that for lesions observed in glands irradiated in situ. A high incidence of epithelial hyperplasias with severe dysplasia was observed in transplantation nodules after x-irradiation. Gland tumors were significantly induced in whole-body irradiated animals; the tumors reached a maximum incidence after doses of 3 Gy. The risk of transformation per surviving cell was estimated both for dysplastic lesions and for tumors. These results approximated a dose-squared relationship in both cases, suggesting a common induction mechanism at the cellular level. Myeloid leukemia was observed at all doses in whole-body irradiated mice, and the maximum tumor incidence was reached at doses around 3 Gy.
Assuntos
Neoplasias Oculares/etiologia , Glândula de Harder/efeitos da radiação , Aparelho Lacrimal/efeitos da radiação , Leucemia Mieloide/etiologia , Leucemia Induzida por Radiação/patologia , Neoplasias Induzidas por Radiação/patologia , Animais , Sobrevivência Celular/efeitos da radiação , Relação Dose-Resposta à Radiação , Neoplasias Oculares/patologia , Glândula de Harder/patologia , Glândula de Harder/transplante , Hiperplasia , Leucemia Mieloide/patologia , Masculino , Camundongos , Camundongos Endogâmicos CBA , Irradiação Corporal TotalRESUMO
Transplantation of hepatocytes from CBA/Cne mice into the fat pads of isogeneic recipients has been used for the quantitative in vivo study of cell survival and risk of transformation after x-ray irradiation (1-7 Gy). A survival curve for liver cells was generated in vivo with a D0 of 3.08 Gy and an extrapolation number not significantly different from 1. Data on liver tumor incidence in whole-body irradiated CBA/Cne and C57BL/Cne X C3H/HeCne (BC3F1) mice are also reported. A statistical analysis of trend in both cases proved a significant induction of tumors by x-rays mainly for doses above 2 Gy. The risk of transformation per surviving cell was estimated for both mouse strains. For CBA mice the data points suggested the presence of a linear component in the dose-effect curve at low doses, whereas for BC3F1 mice a quadratic expression appeared to provide a better description of the points from 1 to 6 Gy. The data of this study suggested that liver tumors can be induced by radiation in mouse strains with either a high or low spontaneous hepatoma incidence.
Assuntos
Neoplasias Hepáticas Experimentais/etiologia , Fígado/efeitos da radiação , Neoplasias Induzidas por Radiação , Animais , Transformação Celular Neoplásica , Neoplasias Hepáticas Experimentais/genética , Transplante de Fígado , Masculino , Camundongos , Camundongos Endogâmicos C3H , Camundongos Endogâmicos C57BL , Camundongos Endogâmicos CBA , Irradiação Corporal TotalRESUMO
Biozzi mice selected for high (H) or low (L) antibody responsiveness to natural antigens have been followed for their entire life-span to examine their pathology at death. As previously found in selection I, shorter life-span and higher lymphoma incidence were observed in L responder mice than in H responder mice selected for antibody responsiveness to sheep red blood cells (selection II). In mice selected for antibody responsiveness to Salmonella flagellar antigens (selection III), similar life-span and similar lymphoma incidence were found in H and L responder mice. Natural killer (NK) cell activity, as assessed in spleen cells from young mice, was lower in L than in H responder mice of selection I but higher in L than in H responder mice of both selections II and III. All these results indicate that longevity and lymphoma incidence at death are independent of NK cell activity in mice selected for H or L antibody responsiveness to natural antigens. Furthermore, genetic selection for antibody responsiveness does not always appear to influence life-span and lymphoma incidence.
Assuntos
Formação de Anticorpos , Células Matadoras Naturais/imunologia , Longevidade , Neoplasias Experimentais/epidemiologia , Animais , Antígenos de Bactérias/imunologia , Eritrócitos/imunologia , Feminino , Linfoma/epidemiologia , Masculino , Camundongos , Fatores Sexuais , Ovinos , Baço/imunologiaRESUMO
Long-term syngeneic radiation chimeras displayed a very low incidence of reticulum cell sarcoma as compared with control mice. Immune reactivity of these animals was studied in vivo by anti-dinitrophenyl antibody titer and affinity and in vitro by mitotic responsiveness to phytohemagglutinin, concanavalin A and lipopolysaccharide. Anti-body titer and affinity as well as the response to T lectins were found to be increased in chimeras. These results were attributed to increased function of mature T2 cells, which could explain the reduced incidence of reticulum cell sarcoma in chimeras.
Assuntos
Formação de Anticorpos , Linfoma não Hodgkin/imunologia , Quimera por Radiação , Animais , Anticorpos/análise , Concanavalina A/farmacologia , Lectinas/farmacologia , Lipopolissacarídeos/farmacologia , Ativação Linfocitária , Linfoma não Hodgkin/patologia , Masculino , Camundongos , Camundongos Endogâmicos C3H , Camundongos Endogâmicos C57BL , Baço/citologia , Fatores de TempoRESUMO
Extension of previous investigations at this laboratory regarding life shortening and tumor induction in the mouse has provided more complete dose-response information in the low dose region of X rays and neutrons. A complete observation of survival and late pathology has been carried out on over 2000 BC3F1 female mice irradiated with single doses of 1.5 MeV neutrons (0.5, 1, 2, 4, 8, 16 cGy) and, for comparison, of X rays (4, 8, 16, 32, 64, 128, 256 cGy). Data analysis has shown that a significant life shortening is observable only for individual neutron doses not lower than 8 cGy. Nevertheless, assuming a linear nonthreshold form for the overall dose-effect relationships of both radiation qualities, an RBE value of 12.3 is obtained for the 1.5 MeV neutrons. The induction of solid tumors by neutrons becomes statistically significant at individual doses from 8 cGy and by X rays for doses larger than 1 Gy. Linear dependence on neutron dose appears adequate to interpret the data at low doses. A separate analysis of ovarian tumor induction substantiates the hypothesis of a threshold dose for the X rays, while this is not strictly needed to interpret the neutron data. A trend analysis conducted on the neoplasm incidence confirms the above findings. Death rates have been analyzed, and a general agreement between the shift to earlier times of these curves and tumor induction was found.
Assuntos
Nêutrons Rápidos , Longevidade/efeitos da radiação , Neoplasias Induzidas por Radiação/mortalidade , Nêutrons , Animais , Feminino , Camundongos , Doses de Radiação , Eficiência Biológica Relativa , Raios XRESUMO
The main object of this study is to investigate the role of age on the susceptibility to radiation carcinogenesis and life shortening for different qualities of radiation. Over the last few years, a line of research at the Laboratory of Pathology, C.R.E. Casaccia, has been set up to study the effects of exposure to neutron irradiation, including observations on late effects (both neoplastic and nonneoplastic) as a function of radiation dose and of age at irradiation. Graded single doses of X rays or attenuated fission neutrons have been given to male BC3F1 mice 3 and 19 months old and to animals in utero at 17 days postcoitum. The analysis of data from over 3000 mice indicates that irradiation at 3 months of age causes life shortening which is associated with the incidence and rate of radiation-induced neoplasms. Prenatal irradiation or irradiation at 19 months of age does not show a clearly measurable life shortening for both X-ray and neutron exposures. However, significantly higher incidence and rate of solid tumors and reticulum cell sarcomas were observed. In general the data confirm the higher biological effectiveness of neutrons compared with X rays. The estimates of neutron relative biological effectiveness for different end points were found to be in the range of 3 to 18 and their variation was closely dose dependent.
Assuntos
Envelhecimento , Expectativa de Vida , Neoplasias Induzidas por Radiação , Nêutrons , Animais , Relação Dose-Resposta à Radiação , Feminino , Linfoma Difuso de Grandes Células B/etiologia , Masculino , Camundongos , Gravidez , Efeitos Tardios da Exposição Pré-Natal , Eficiência Biológica RelativaRESUMO
A study was conducted on the genotoxicity of butadiene diepoxide (DEB) in mouse oocytes. Superovulated female mice were injected intraperitoneally with DEB and mated with untreated males. Oocyte exposure occurred approximately 1.5 days before ovulation. DEB doses ranged between 26 and 52 mg/kg. Chromosome aberrations were scored in C-banded metaphases of one-cell embryos. The percentage of mated females, the average number of zygotes harvested per female, the frequencies of unfertilized oocytes and developmentally delayed zygotes did not reveal any overt sign of chemical toxicity which hindered the propensity of animals to mate or affected the ovulation, fertilization, or cell cycle progression of treated oocytes. A dose-dependent induction of chromosome aberrations was observed which was best fitted by a linear-quadratic equation. Half of all the aberrations transmitted by DEB-treated oocytes were chromatid-type breaks or exchanges. Among chromosome-type aberrations, double fragments for exceeded chromosome exchanges. This spectrum of structural aberrations differed markedly from what was previously observed in one-cell embryos conceived by DEB-treated sperm, where 97% were chromosome-type aberrations and 40% were dicentrics or translocations. This difference suggests that chromosome damage in one-cell embryos can be fixed by different mutagenic pathways influenced by the targeted gamete and its specific chromatin configuration. After exposure to the same dose, oocytes transmitted to one-cell embryos between 4 and 8 times fewer aberrations than DEB-treated sperm. While the rate of aberration induction suggests that female germ cells may be less at risk than mature sperm, especially at low-dose levels, the higher threshold for reproductive toxicity observed in female than in male mice may justify inclusion of data on female germ cell mutagenicity in the genetic risk assessment of butadiene exposure.
Assuntos
Aberrações Cromossômicas , Compostos de Epóxi/toxicidade , Fertilização/efeitos dos fármacos , Mutagênicos/toxicidade , Oócitos/efeitos dos fármacos , Animais , Cruzamento , Feminino , Fertilização/genética , Cariotipagem , Masculino , CamundongosRESUMO
Lung fibroblasts from BD-exposed mice have been analysed for the occurrence of micronuclei. Primary cultures set up 24h after the end of exposure were treated with cytochalasin B and micronuclei scored in binucleate cells. A three-fold statistically significant increase of micronucleated cells was detected after exposure to 500ppm, the lowest tested concentration. A linear dose effect relationship was observed between 500 and 1300ppm. Immunofluorescent staining of kinetochore proteins was applied to distinguish between acentric micronuclei produced by chromosome breaks and micronuclei containing a centromeric region, most likely induced by chromosome loss. A statistically significant increase of both types of MN in 1300ppm-exposed females and a significant increase in centromeric MN in 500ppm-exposed males were detected. These data demonstrate that an intermediate of BD metabolism with a potential for clastogenic and aneugenic effects is active in lung cells after inhalation exposure. These effects can play a role in the initiation and promotion of BD-induced lung tumours.
Assuntos
Butadienos/toxicidade , Pulmão/efeitos dos fármacos , Mutagênicos/toxicidade , Animais , Células Cultivadas , Relação Dose-Resposta a Droga , Imunofluorescência , Pulmão/citologia , Pulmão/ultraestrutura , Camundongos , Testes para MicronúcleosRESUMO
The effect of selection processes operating on chemically induced aneuploid and polyploid cells was studied in mouse bone marrow cells at their third generation after a single i.p. treatment with vinblastine (VBL). Bromodeoxyuridine (BrdUrd)-labeled metaphases were analyzed for chromosome number and the frequencies of aneuploid and polyploid cells recorded at 2 different times, both within the third cell cycle after VBL treatment. Cell-cycle progression was analyzed for both control and treated mice at the 2 fixation times. Our data suggest that polyploid cells and possibly also cells with numerous additional chromosomes could have a cell cycle longer than that of diploid cells and cells hyperploid for 1-2 additional chromosomes. Both hyperploid and polyploid cells seem to have a reduced probability of undergoing further mitoses, as shown by the reduction of their frequencies at the third cell cycle, when compared to the frequencies observed in the second cell cycle after the same VBL treatment.
Assuntos
Aneuploidia , Seleção Genética , Vimblastina/toxicidade , Animais , Medula Óssea/efeitos dos fármacos , Ciclo Celular/efeitos dos fármacos , Injeções Intraperitoneais , CamundongosRESUMO
Within the context of a coordinated program to study aneuploidy induction sponsored by the European Community, nine chemicals were tested in mouse bone marrow and spermatocytes after intraperitoneal injection. In somatic cells, cell progression delay, hyperploidy, polyploidy induction and induction of micronucleated polychromatic erythrocyte (MnPCE) were studied. In germ cells hyperploidy induction was evaluated. The chemicals selected were: colchicine (COL), econazole (EZ), hydroquinone (HQ), thiabendazole (TB), diazepam (DZ), chloral hydrate (CH), cadmium chloride (CD), pyrimethamine (PY) and thimerosal (TM). Using literature data on c-mitotic effects in bone marrow as a reference, the same doses were tested in somatic and germ cells in order to compare the effects induced. Bone marrow cells were sampled 18 or 24 h after treatment. Germ cells were sampled 6, 8 or 18 h after treatment. Effects of COL and HQ in bone marrow have been reported elsewhere. Somatic effects were induced by CH (hyperploidy and cell cycle lengthening), TB (MnPCEs and cell cycle lengthening) and by PY (MnPCEs). EZ, DZ, CD and TM did not induce any kind of somatic effects. An increase in the incidence of hyperploid spermatocytes was induced by COL, at three dose levels, and by one dose of HQ and TB. All the other chemicals did not induce germinal aneuploidy at any dose or time tested. The hyperploidy control frequency ranged between 0.4 and 1.0% in somatic cells and from 0.3 to 0.9% in germ cells. In both somatic and germ cells, the maximum yield of induced hyperploidy did not exceed 3.5%. The time period of target cell sensitivity is probably restricted and this, associated with the heterogeneity and the asynchrony of cellular maturation processes, may account for our data. Under these circumstances, the negative data should be interpreted with some caution, particularly in germ cells, where additional indicators of chemical-cell interaction and cell cycle effects were not provided by standardized approaches. The possibility of increasing the size of analyzed cell samples could be considered in the light of automatic scoring procedures.
Assuntos
Aneuploidia , Medula Óssea/efeitos dos fármacos , Mutagênicos/toxicidade , Espermatócitos/efeitos dos fármacos , Animais , Medula Óssea/patologia , Cádmio/toxicidade , Cloreto de Cádmio , Hidrato de Cloral/toxicidade , Cloretos/toxicidade , Colchicina/toxicidade , Diazepam/toxicidade , Econazol/toxicidade , Hidroquinonas/toxicidade , Masculino , Camundongos , Camundongos Endogâmicos , Testes para Micronúcleos/métodos , Testes de Mutagenicidade , Ploidias , Pirimetamina/toxicidade , Espermatócitos/citologia , Testículo/efeitos dos fármacos , Testículo/patologia , Tiabendazol/toxicidade , Timerosal/toxicidadeRESUMO
Vinblastine (VBL) was tested in the mouse for induction of chromosome malsegregation in bone marrow cells. The occurrence of aneuploidy and polyploidy was correlated with cell-cycle kinetics measured by DNA labelling with bromodeoxyuridine (BrdUrd). Sister-chromatid exchanges (SCE) were also detected. A dose-dependent lengthening of the cell cycle was induced in the dose range of 0.9-4.5 mg/kg body weight, up to a complete inhibition of cell-cycle progression (100% of metaphases were arrested before completion of the first mitotic division following a recovery time of 18 h, compared with 8% in the controls). Both aneuploidy and polyploidy were induced. Aneuploid metaphases were grouped into 2 classes, those with no more than 2 extra chromosomes and those with 3-10 extra chromosomes. The frequencies of cells with severe aneuploidy and polyploidy increased considerably when second-generation cells were sampled at a recovery time of 24 h. This observation suggested that gross chromosome imbalances occur preferentially after a period of mitotic arrest, probably as a consequence of multipolar spindles or failure of proper spindle assembly. Non-disjunction of single chromosomes arises independently of the mitotic block. A slight increase in SCE frequency was observed only at a recovery time of 18 h. This study may provide information on the kinetics and mechanisms of origin of VBL-induced numerical aberrations in vivo.
Assuntos
Aneuploidia , Medula Óssea/ultraestrutura , Ciclo Celular , Vimblastina/farmacologia , Análise de Variância , Animais , Medula Óssea/efeitos dos fármacos , Ciclo Celular/efeitos dos fármacos , Divisão Celular/efeitos dos fármacos , Cromossomos/efeitos dos fármacos , Cromossomos/fisiologia , Cinética , Masculino , Camundongos , Análise de RegressãoRESUMO
Griseofulvin (GF) was tested in female mouse germ cells for the induction of aneuploidy and meiotic arrest. Superovulated mice were orally treated with 200, 666, 1332 or 2000 mg/kg in olive oil at the time of human chorionic gonadotrophin (HCG) injection and were sacrificed 18 h later. A dose-dependent increase in the frequency of metaphase I (M I) arrested oocytes was observed (maximum of 70%). Aneuploidy was not significantly induced. Also, the kinetics of meiotic progression up to the metaphase II (M II) stage was studied in untreated mice in order to correlate the time of treatment with the time of the first meiotic division. The results demonstrate that the majority of cells was treated with GF approximately 8 h before the M I stage. A second series of experiments were performed to test GF effects at a different treatment time. Doses of 200, 666 or 2000 mg/kg were administered 2 h post HCG. As in the first series of experiments, the animals were sacrificed 18 h post HCG. The results, compared with those obtained in the first experimental series, showed an inverse trend for meiotic arrest and aneuploidy induction. The frequency of M I arrested oocytes dropped from a maximum of 70% to a maximum of 20%, while, at the latest treatment time, a dose-dependent increase in the frequency of hyperploid oocytes was observed up to 56% aberrant cells at 2000 mg/kg. Altogether the results suggest that the arrest of meiotic division and the induction of aneuploidy by GF are caused by interaction with different targets or different developmental stages of the same target. In conclusion, GF has been shown to induce aneuploidy during the first meiotic division in a dose-related manner, together with other effects such as polyploidy, developmental delay and meiotic arrest. Also, these findings demonstrate that the sensitivity of the oocyte target(s) may be restricted to a specific time period and that a correct experimental protocol is critical for assessing the aneugenic activity of a chemical.
Assuntos
Aneuploidia , Griseofulvina/toxicidade , Meiose/efeitos dos fármacos , Oócitos/efeitos dos fármacos , Animais , Gonadotropina Coriônica/farmacologia , Relação Dose-Resposta a Droga , Feminino , Metáfase , Camundongos , Camundongos Endogâmicos C3H , Camundongos Endogâmicos C57BLRESUMO
The effects of griseofulvin (GF) upon the first meiotic division of female mouse germ cells were evaluated by cytogenetic analysis of first-cleavage (1-Cl) zygotes. The present study is an extension of an investigation that began with the cytogenetic analysis of metaphase II (M II) oocytes. Different doses (200, 666, 1332, 2000 mg/kg) were tested by oral administration of GF to superovulated animals either at the time of human chorionic gonadotrophin (HCG) injection or 2 h post HCG. When GF was given at the time of HCG, significant dose-dependent increases of different types of cytogenetically abnormal cells were found. These included zygotes containing ostensibly female-derived M I or M II arrested chromosomes and polyploid zygotes. The total yields of these aberrations were 2.9, 4.3, 26.2, 60.6, and 64.1% for control, 200, 666, 1332, and 2000 mg/kg, respectively. The origin of these zygotes was attributed to the fertilization of oocytes that had been previously arrested at M I. No significant induction of hyperploidy was detected. Developmentally abnormal zygotes were still observed when GF was administered 2 h post HCG, although their frequencies were significantly lower than in the first series of experiments. The yields of developmentally abnormal zygotes were 49, 10.2, and 23.6% at 200, 666, and 2000 mg/kg. Additionally, a dose-dependent increase in the frequency of hyperploid zygotes was detected up to a maximum of 36.5% at 2000 mg/kg. These results confirm the cytogenetic observations from M II oocytes after GF treatment under the same experimental conditions; namely, a dramatic change in the oocyte target susceptibility to GF occurred within a short time period. Also, the present study demonstrated that most of GF-induced aneuploid oocytes were fertilized and reached first-cleavage metaphase.
Assuntos
Aneuploidia , Griseofulvina/toxicidade , Meiose/efeitos dos fármacos , Zigoto/efeitos dos fármacos , Animais , Relação Dose-Resposta a Droga , Feminino , Camundongos , Camundongos Endogâmicos C3H , Camundongos Endogâmicos C57BL , Zigoto/ultraestruturaRESUMO
Nitrilotriacetic acid (NTA) was tested for the induction of aneuploidy in mouse bone marrow cells. Doses of 138 or 275 mg/kg of body weight were intraperitoneally injected 24 h after implantation of a bromodeoxyuridine tablet. Cell-replication kinetics was assessed by comparing the relative percentages of first, second and third metaphases in control and treated samples. The hyperploidy incidence was estimated in second metaphases only, together with the SCE/cell level. Mice injected with 1.8 mg/kg vinblastine (VBL) were used as positive controls. A slight delay of cell cycle was induced by NTA, as shown by regression analysis applied to average generation time values. No increase over the control level was observed for hyperploidy or SCE induction in NTA-treated mice. VBL induced both cell-cycle alteration and a highly significant (P less than 0.001) increase of the hyperploid cell frequency. On the basis of these and previous (Costa et al., 1988) observations it seems that the non-disjunctional activity of NTA in the mouse is confined to meiotic processes.
Assuntos
Acetatos/toxicidade , Aneuploidia/efeitos dos fármacos , Ácido Nitrilotriacético/toxicidade , Animais , Células da Medula Óssea , Ciclo Celular/efeitos dos fármacos , Camundongos , Testes para Micronúcleos , Troca de Cromátide Irmã/efeitos dos fármacos , Vimblastina/toxicidadeRESUMO
Within a project coordinated by the Commission of the European Communities for the detection of germ cell mutagens, the cytogenetic analysis of first-cleavage metaphases was carried out to detect chromosomal damage induced by acrylamide (AA) in meiotic and postmeiotic stages of mouse spermatogenesis. Male mice were intraperitoneally injected with single acute doses of 75 or 125 mg/kg or treated with five daily injections of 50 mg/kg and mated either 7 or 28 days after the end of treatment. Chromosomal aberrations were scored in C-banded metaphases prepared from one-cell zygotes by a mass harvest technique. AA treatment of late spermatids-spermatozoa resulted in significant increases of structural aberrations at all doses tested. The data could be fitted to a curvilinear regression and a doubling dose of 23 mg/kg was calculated. The large majority of observed aberrations were of the chromosome type, including dicentrics, rings and translocations, in agreement with a mechanism of chromosomal damage mediated through the alkylation of DNA-associated protamines. Even though the frequency of aberrations 28 days after treatment was not significantly higher than the control value, the presence of multiple rearrangements in two cells suggested that AA might also have a minor effect on spermatocytes. The results of the cytogenetic analysis of first cleavage metaphases agreed well both qualitatively and quantitatively with the outcome of dominant lethal and heritable translocation assays. AA-induced cytotoxicity was monitored by flow cytometric DNA content analysis of testicular cells. By this method, a dose-dependent depletion of mature spermatids after treatment of spermatogonia and a toxic effect upon primary spermatocytes were detected.
Assuntos
Acrilamidas/toxicidade , Aberrações Cromossômicas , Mutagênicos/toxicidade , Testículo/efeitos dos fármacos , Zigoto/efeitos dos fármacos , Acrilamida , Animais , Relação Dose-Resposta a Droga , Feminino , Citometria de Fluxo , Masculino , Metáfase , Camundongos , Camundongos Endogâmicos , Troca de Cromátide Irmã , Espermatogênese , Superovulação , Testículo/patologia , Zigoto/citologiaRESUMO
Reproductive effects of 1,3 butadiene inhalation have been evaluated in male mice by reduction of post-meiotic germ cells, alteration of sperm chromatin structure and transmission of chromosome aberrations to one-cell embryos. Animals were exposed for 5 consecutive days for 6 h per day to butadiene concentrations of 130, 500 or 1300 ppm. The testicular fraction of post-meiotic germ cells was measured by flow cytometric analysis on the basis of their DNA content. Round spermatids were discriminated from mature, elongated spermatids by their different degree of chromatin condensation. Butadiene-induced cytotoxic effects on differentiating spermatogonia were shown by a concentration-dependent decrease of round spermatids occurring 21 days after chemical exposure, confirmed by a similar decrease of elongated spermatids measured in testes sampled 7 days later. Statistically significant effects were seen already at 130 ppm. An incomplete repopulation of the elongated spermatid compartment observed 35 days after exposure to 1300 ppm suggested that, at the highest concentration tested, butadiene toxicity extended to stem cells. Alterations of sperm chromatin were revealed by its increased sensitivity to acidic denaturation in situ. The percentage of abnormal sperm was significantly increased after butadiene exposure of differentiating spermatogonia and spermatocytes. This suggested the induction of persistent effects interfering with chromatin remodelling during spermiogenesis. Chromosome-type structural aberrations were significantly elevated in first-cleavage embryos conceived by males mated during the first and second week after the end of exposure. The lowest effective tested concentration was 500 ppm, the same reported for dominant lethal induction under identical exposure conditions. As in the dominant lethal assay, the effect of this dose was confined to exposed sperm, while both sperm and late spermatids were affected by the inhalation of 1300 ppm. A quantitative comparison between the effects induced by intraperitoneal injections of diepoxybutane or butadiene inhalations suggested that other reactive intermediates, in addition to diepoxybutane, might contribute to mediate butadiene-induced reproductive toxicity.