RESUMO
A novel genetic male sterile germplasm was developed by successively crossing of (C. annuum x C. chinense) x C. pubescens and by chemical mutagenesis in pepper. The sterile anthers showed morphological abnormalities, but pistils developed normally with fine pollination capability. We investigated fertility segregation through sib-crossing of the same strains and test crossing by male sterile plants with 6 advanced inbred lines. The results showed that male fertility in the pepper was dominant in the F1 generation and segregated at a rate of 3:1 in the F2 generation, suggesting that monogenic male sterility was recessive and conformed to Mendelian inheritance. Cyto-anatomy analysis revealed that microspore abortion of sterile anthers occurred during telophase in the microspore mother cell stage when tapetal cells showed excessive vacuolation, resulting in occupation of the loculi. The microspore mother cells self-destructed and autolyzed with the tapetum so that meiosis in pollen mother cells could not proceed past the tetrad stage.
Assuntos
Capsicum/genética , Infertilidade das Plantas/genética , Pólen/citologia , Capsicum/citologia , Hibridização Genética , Mutagênese , Pólen/genética , TelófaseRESUMO
To date, many anticancer drugs have been developed by directly or indirectly targeting microtubules, which are involved in cell division. Although this approach has yielded many anticancer drugs, these drugs produce undesirable side effects. An alternative strategy is needed, and targeting mitotic exit may be one alternative approach. Localization of phosphorylated barrier-to-autointegration factor (BAF) to the chromosomal core region is essential for nuclear envelope compartment relocalization. In this study, we isolated brazilin from Caesalpinia sappan Leguminosae and demonstrated that it inhibited BAF phosphorylation in vitro and in vivo. Moreover, we demonstrated direct binding between brazilin and BAF. The inhibition of BAF phosphorylation induced abnormal nuclear envelope reassembly and cell death, indicating that perturbation of nuclear envelope reassembly could be a novel approach to anticancer therapy. We propose that brazilin isolated from C. sappan may be a new anticancer drug candidate that induces cell death by inhibiting vaccinia-related kinase 1-mediated BAF phosphorylation.
Assuntos
Antineoplásicos/isolamento & purificação , Antineoplásicos/farmacologia , Benzopiranos/isolamento & purificação , Benzopiranos/farmacologia , Caesalpinia/química , Proteínas de Ligação a DNA/metabolismo , Membrana Nuclear/efeitos dos fármacos , Proteínas Nucleares/metabolismo , Animais , Antineoplásicos/metabolismo , Benzopiranos/metabolismo , Morte Celular/efeitos dos fármacos , Avaliação Pré-Clínica de Medicamentos , Células HeLa , Humanos , Peptídeos e Proteínas de Sinalização Intracelular/metabolismo , Masculino , Camundongos , Membrana Nuclear/metabolismo , Fosforilação/efeitos dos fármacos , Proteínas Serina-Treonina Quinases/metabolismo , Telófase/efeitos dos fármacosRESUMO
Previous studies in the wetland macrophyte Bidens laevis L have demonstrated that the insecticide endosulfan induces a high frequency of somatic chromosome aberrations in anaphase-telophase (CAAT) but no DNA changes as determined by the single cell gel electrophoresis (Comet) assay. Thus, cytogenetic biomarkers appear to be more sensitive to the toxic effects of the insecticide than the DNA molecule in the studied species. For this reason, the goals of this study were to use cytogenetic biomarkers--CAAT and abnormal metaphase--and defense biomarkers such as the activity of the antioxidant enzymes--guaiacol peroxidases (POD), glutathione reductase, and microsomal and cytosolic (m- and c-) glutathione-S-transferase (GST)--to evaluate in B. laevis effects caused by a commercial formulation of endosulfan. The frequency of CAAT was increased at 5, 10, 50, and 100 µg/L endosulfan with respect to the negative controls by 3.1, 2.5, 2.5, and 3.2-fold, respectively while the frequency of abnormal metaphases was also increased at the same concentrations by 3.5, 2.8, 3.2, and 11.3-fold, respectively. In addition to these aneugenic effects, other abnormalities such as C-mitosis and chromosome clumping were observed at 10 µg/L endosulfan. On the other hand, POD induction at 0.02, 0.5, 5, and 10 µg/L and m-GST inhibition at 0.5, 10, and 50 µg/L in plants exposed during 24 h to endosulfan were observed but all of these responses were highly variable. In conclusion, only cytogenetic biomarkers like CAAT in B. laevis can serve potentially as early warning systems to detect environmentally relevant concentrations of endosulfan in aquatic ecosystems.
Assuntos
Bidens/efeitos dos fármacos , Endossulfano/toxicidade , Inseticidas/toxicidade , Anáfase , Bidens/enzimologia , Bidens/genética , Biomarcadores/metabolismo , Aberrações Cromossômicas , Ensaio Cometa , Marcadores Genéticos , Glutationa Redutase/metabolismo , Glutationa Transferase/metabolismo , TelófaseRESUMO
Rab24 is an atypical member of the Rab GTPase family whose distribution in interphase cells has been characterized; however, its function remains largely unknown. In this study, we have analyzed the distribution of Rab24 throughout cell division. We have observed that Rab24 was located at the mitotic spindle in metaphase, at the midbody during telophase and in the furrow during cytokinesis. We have also observed partial co-localization of Rab24 and tubulin and demonstrated its association to microtubules. Interestingly, more than 90% of transiently transfected HeLa cells with Rab24 presented abnormal nuclear connections (i.e., chromatin bridges). Furthermore, in CHO cells stably transfected with GFP-Rab24wt, we observed a large percentage of binucleated and multinucleated cells. In addition, these cells presented an extremely large size and multiple failures in mitosis, as aberrant spindle formation (metaphase), delayed chromosomes (telophase) and multiple cytokinesis. A marked increase in binucleated, multinucleated and multilobulated nucleus formation was observed in HeLa cells depleted of Rab24. We also present evidence that a fraction of Rab24 associates with microtubules. In addition, Rab24 knock down resulted in misalignment of chromosomes and abnormal spindle formation in metaphase leading to the appearance of delayed chromosomes during late telophase and failures in cytokinesis. Our findings suggest that an adequate level of Rab24 is necessary for normal cell division. In summary, Rab24 modulates several mitotic events, including chromosome segregation and cytokinesis, perhaps through the interaction with microtubules.
Assuntos
Divisão Celular , Cromossomos/ultraestrutura , Microtúbulos/metabolismo , Proteínas rab de Ligação ao GTP/fisiologia , Animais , Células CHO , Núcleo Celular/metabolismo , Cricetinae , Cricetulus , Citocinese , Proteínas de Fluorescência Verde/metabolismo , Células HeLa , Humanos , Microscopia de Fluorescência , Mitose , RNA Interferente Pequeno/metabolismo , Fuso Acromático , Telófase , Transfecção , Proteínas rab de Ligação ao GTP/metabolismoRESUMO
In order to determine the reasons for pollen sterility in lily hybrids, four diploid sterile Oriental x Trumpet (OT) lily cultivars ('Nymph', 'Gluhwein', 'Yelloween', and 'Shocking') were used to investigate the meiotic chromosome behaviors in pollen mother cells (PMCs), using genomic in situ hybridization and conventional cytological methods. At metaphase I, chromosome associations were quite variable, not only among different genotypes but also in different PMCs of the same genotype. In addition to bivalents, a certain amount of univalent, trivalents, and quadrivalents were observed in all of the investigated genotypes. In addition, ring octavalents and ring hexavalents were observed in 'Nymph'. Even dodecavalents were observed in 'Nymph'. These abnormal chromosome associations at metaphase I implied the occurrence of chromosome interchanges (translocation) in these intersectional hybrids. At anaphase-telophase, a large number of laggard chromosomes and different kinds of chromosome bridge configurations were observed. At the tetrad stage, micronuclei and polyads were also found in many PMCs. All of these abnormal chromosome behaviors in PMCs were responsible for the pollen sterility in lily hybrids.
Assuntos
Quimera/genética , Segregação de Cromossomos/genética , Infertilidade/genética , Lilium/genética , Fuso Acromático/genética , Anáfase/genética , Cruzamento , Aberrações Cromossômicas , Cromossomos de Plantas , Análise Citogenética , Especiação Genética , Hibridização Genética , Hibridização In Situ , Lilium/classificação , Meiose , Metáfase/genética , Pólen/genética , Cromossomos em Anel , Telófase/genéticaRESUMO
PURPOSE: To evaluate the nuclear maturation stage and the presence of meiotic spindles of in vivo matured oocytes from infertile women undergoing stimulated cycles for intracytoplasmic sperm injection (ICSI) and compare intracytoplasmic sperm injection outcomes between oocytes in telophase I (TI) and metaphase II (MII), and the ones with and without visible meiotic spindle. METHODS: A prospective and controlled study with 106 infertile patients who underwent ovarian stimulation for intracytoplasmic sperm injection purposes. Patients aged 38 years or less, with basal follicle stimulating hormone (FSH) less than 10 mIU/mL and body mass index (BMI) less than 30 kg/m². Were included patients presenting any systemic diseases, any active infection, smokers or patients who had been using hormonal medications and hormonal and nonhormonal anti-inflammatory drugs for the past two months prior to the assisted reproduction procedure were excluded. The oocytes with the first polar body extruded (in vivo matured oocytes) were imaged by polarization microscopy immediately before intracytoplasmic sperm injection and characterized according to nuclear maturation stage (telophase I and metaphase II) and to the presence of a meiotic spindle. We analyzed the fertilization rates, cleavage, number of good quality embryos on the second day (D2) from oocytes on telophase I versus those in metaphase II, and metaphase II visible spindle versus non-visible ones. Data were analyzed comparatively by Fisher's exact test. The level of significance was set at 5% in all analyses (p<0.05). RESULTS: The meiotic spindles of 516 oocytes were imaged using polarization microscopy. From the 516 oocytes analyzed, seventeen were in telophase I (3.3%) and 499 (96.7%) in metaphase II. The oocytes injected in telophase I had significantly lower fertilization rates than those injected in metaphase II (53 and 78%, respectively) and produced no good quality embryos on day 2. When the oocytes with and without a visible meiotic spindle were compared, there was no significant difference in the intracytoplasmic sperm injection results. CONCLUSIONS: Oocytes injected in telophase I showed lower fertilization rates when compared to those in metaphase II. It is possible that the analysis of oocyte nuclear maturation by polarization microscopy can be used as a predictor of fertilization after intracytoplasmic sperm injection.
Assuntos
Oócitos/citologia , Técnicas de Reprodução Assistida , Adulto , Feminino , Humanos , Técnicas de Maturação in Vitro de Oócitos , Injeções , Estudos Prospectivos , Injeções de Esperma Intracitoplásmicas , TelófaseRESUMO
OBJETIVO: Avaliar o estágio de maturação nuclear de oócitos com o primeiro corpúsculo polar (CP) visível de pacientes inférteis submetidas à estimulação ovariana para injeção intracitoplasmática de espermatozoide (ICSI) e comparar os resultados da injeção intracitoplasmática de espermatozoide entre os oócitos em telófase I (TI) e metáfase II (MII), e entre aqueles em metáfase II com e sem fuso celular visível. MÉTODOS: Estudo prospectivo que incluiu 106 pacientes inférteis submetidas à injeção intracitoplasmática de espermatozoide. Foram incluídas pacientes com idade menor ou igual a 38 anos, hormônio folículo estimulante (FSH) basal menor que 10 mIU/mL e índice de massa corpórea (IMC) menor que 30 kg/m². Foram excluídas pacientes com doenças sistêmicas, com qualquer infecção ativa, tabagistas ou que fizeram uso de medicações hormonais e anti-inflamatórias hormonais e não hormonais nos últimos dois meses, previamente à programação para o procedimento de reprodução assistida. Os oócitos com extrusão do primeiro corpúsculo polar foram avaliados pela microscopia de polarização, imediatamente antes da realização da injeção intracitoplasmática de espermatozoide, e caracterizados quanto ao estágio de maturação nuclear (telófase I ou metáfase II). Os oócitos em metáfase II foram avaliados de acordo com a presença ou não do fuso meiótico. Foram analisadas as taxas de fertilização, clivagem e o número de embriões de boa qualidade no segundo dia (D2) de desenvolvimento. Os dados foram analisados comparativamente através do teste exato de Fisher. Em todas as análises foi considerado o nível de significância de 5% (p<0,05). RESULTADOS: O fuso meiótico de 516 oócitos foi visualizado através da microscopia de polarização. Dezessete dos 516 oócitos avaliados estavam em telófase I (3,3%) e 499 (96,7%) em metáfase II. Os oócitos injetados em telófase I apresentaram taxas de fertilização significativamente menores do que os injetados em metáfase II (53 e 78%, respectivamente) e não produziram nenhum embrião de boa qualidade no segundo dia. Comparando-se os oócitos com e sem fuso celular visível, não foi observada diferença significativa nos resultados de injeção intracitoplasmática de espermatozoide. CONCLUSÕES: Oócitos injetados em telófase I apresentaram menores taxas de fertilização quando comparados aos em metáfase II. É possível que a análise do estágio de maturação nuclear oocitária, por meio da microscopia de polarização, possa ser utilizada como fator de predição das taxas de fertilização pós-injeção intracitoplasmática de espermatozoide.
PURPOSE: To evaluate the nuclear maturation stage and the presence of meiotic spindles of in vivo matured oocytes from infertile women undergoing stimulated cycles for intracytoplasmic sperm injection (ICSI) and compare intracytoplasmic sperm injection outcomes between oocytes in telophase I (TI) and metaphase II (MII), and the ones with and without visible meiotic spindle. METHODS: A prospective and controlled study with 106 infertile patients who underwent ovarian stimulation for intracytoplasmic sperm injection purposes. Patients aged 38 years or less, with basal follicle stimulating hormone (FSH) less than 10 mIU/mL and body mass index (BMI) less than 30 kg/m². Were included patients presenting any systemic diseases, any active infection, smokers or patients who had been using hormonal medications and hormonal and nonhormonal anti-inflammatory drugs for the past two months prior to the assisted reproduction procedure were excluded. The oocytes with the first polar body extruded (in vivo matured oocytes) were imaged by polarization microscopy immediately before intracytoplasmic sperm injection and characterized according to nuclear maturation stage (telophase I and metaphase II) and to the presence of a meiotic spindle. We analyzed the fertilization rates, cleavage, number of good quality embryos on the second day (D2) from oocytes on telophase I versus those in metaphase II, and metaphase II visible spindle versus non-visible ones. Data were analyzed comparatively by Fisher's exact test. The level of significance was set at 5% in all analyses (p<0.05). RESULTS: The meiotic spindles of 516 oocytes were imaged using polarization microscopy. From the 516 oocytes analyzed, seventeen were in telophase I (3.3%) and 499 (96.7%) in metaphase II. The oocytes injected in telophase I had significantly lower fertilization rates than those injected in metaphase II (53 and 78%, respectively) and produced no good quality embryos on day 2. When the oocytes with and without a visible meiotic spindle were compared, there was no significant difference in the intracytoplasmic sperm injection results. CONCLUSIONS: Oocytes injected in telophase I showed lower fertilization rates when compared to those in metaphase II. It is possible that the analysis of oocyte nuclear maturation by polarization microscopy can be used as a predictor of fertilization after intracytoplasmic sperm injection.
Assuntos
Adulto , Feminino , Humanos , Oócitos/citologia , Técnicas de Reprodução Assistida , Técnicas de Maturação in Vitro de Oócitos , Injeções , Estudos Prospectivos , Injeções de Esperma Intracitoplásmicas , TelófaseRESUMO
Several mutations are known to alter the normal progression of meiosis and can be correlated with defects in microtubule distribution. The dv mutation affects the spindle organization and chromosomes do not converge into focused poles. Two Brachiaria hybrids presented the phenotypic expressions of dv mutation but exhibited many more details in the second division. Bivalents were distantly positioned and spread over a large metaphase plate and failed to converge into focused poles. Depending on the distance of chromosomes at the poles, telophase I nuclei were elongated or the chromosomes were grouped into various micronuclei of different sizes in each cell. The first cytokinesis occurred. However, when there were micronuclei, a second cytokinesis immediately took place dividing the prophase II meiocytes into three or four cells. In each meiocyte, meiosis progressed to the second division. Slightly elongated nuclei or micronuclei were recorded in telophase II. After a third cytokinesis, hexads or octads were formed. Pollen grains of different sizes were generated. One of these hybrids presented a higher frequency of abnormal cells than when previously analyzed. The fate of these hybrids as genitors or as candidates for cultivars in the Brachiaria breeding program is discussed.
Assuntos
Brachiaria/genética , Quimera/genética , Regulação da Expressão Gênica de Plantas/genética , Meiose/genética , Mutação/genética , Fuso Acromático/genética , Brachiaria/crescimento & desenvolvimento , Brachiaria/metabolismo , Ciclo Celular/genética , Segregação de Cromossomos/genética , Citocinese/genética , Micronúcleo Germinativo/genética , Fenótipo , Pólen/citologia , Pólen/genética , Reprodução/genética , Telófase/genéticaRESUMO
A spontaneous male-sterile, female-fertile mutation affecting bivalent arrangement at the metaphase plate and cytokinesis was detected in line BR98-197 of the soybean breeding program developed by Embrapa - National Soybean Research Centre. Untill diakinesis, meiosis was normal with chromosome pairing as bivalents. From this phase, in several meiocytes, bivalents were not able to organize a single metaphase plate and remained scattered in the cytoplasm in a few or several groups. In these meiocytes, chromosomes segregated in both divisions giving rise to several micronuclei. However, the main cause of male sterility was the absence of cytokinesis after telophase II. Instead of the typical tetrads of microspores, four nucleate coenocytic microspores were formed. In the mutant, pollen mitoses did not occur, and after engorgement by starch, pollen underwent a progressive process of degeneration.
Assuntos
Cromossomos/ultraestrutura , Glycine max/genética , Mutação , Alelos , Ciclo Celular , Núcleo Celular/genética , Citocinese , Citoplasma/metabolismo , Heterozigoto , Meiose , Metáfase , Micronúcleos com Defeito Cromossômico , Mitose , Fenômenos Fisiológicos Vegetais , Pólen/metabolismo , TelófaseRESUMO
The hydrogenosome is an unusual organelle found in several trichomonad species and other protists living in oxygen poor or anoxic environments. The hydrogenosome behavior in the protist Tritrichomonas foetus, parasite of the urogenital tract of cattle, is reported here. The hydrogenosomes were followed by light and transmission electron microscopy during the whole cell cycle. Videomicroscopy, immunofluorescence microscopy, and immunocytochemistry were also used. It is shown that the hydrogenosomes divide at any phase of the cell cycle and that the organellar division is not synchronized. During the interphase the hydrogenosomes are distributed mainly along the axostyle and costa, and at the beginning of mitosis migrate to around the nucleus. Three forms of hydrogenosome division were seen: (1). segmentation, where elongated hydrogenosomes are further separated by external membranous profiles; (2). partition, where rounded hydrogenosomes, in a bulky form, are further separated by a membranous internal septum and, (3). a new dividing form: heart-shaped hydrogenosomes, which gradually present a membrane invagination leading to the organelle division. The hydrogenosomes divide at any phase of the cell cycle. A necklace of intramembranous particles delimiting the outer hydrogenosomal membrane in the region of organelle division was observed by freeze-etching. Similarities between hydrogenosomes and mitochondria behavior during the cell cycle are discussed.
Assuntos
Ciclo Celular/fisiologia , Organelas/fisiologia , Tritrichomonas foetus/citologia , Animais , Imunofluorescência , Técnica de Congelamento e Réplica/métodos , Técnica de Fratura por Congelamento/métodos , Interfase/fisiologia , Malatos/análise , Malatos/imunologia , Metáfase/fisiologia , Microscopia Eletrônica , Microscopia de Fluorescência/métodos , Microscopia de Vídeo/métodos , Microtúbulos/fisiologia , Microtúbulos/ultraestrutura , Mitose/fisiologia , Organelas/ultraestrutura , Prófase/fisiologia , Telófase/fisiologia , Tritrichomonas foetus/fisiologia , Tritrichomonas foetus/ultraestrutura , Tubulina (Proteína)/análise , Tubulina (Proteína)/imunologiaRESUMO
A spontaneous desynaptic mutation, affecting only microsporogenesis and causing pollen sterility, has been detected in BR97-12986H, a line of the official Brazilian soybean breeding program. In this male-sterile, female-fertile mutant, up to metaphase II, the meiotic behavior was similar to that described for the st series of synaptic mutants previously reported in soybean. Besides many univalents, few or total absence of bivalents were recorded in diakinesis. Bivalents presented one or two terminal chiasmata, while univalents retained the sister chromatid cohesion. Bivalents and most univalents congregated at the equatorial metaphase plate, although univalents frequently migrated to the poles prematurely. Laggards resulting from delay in chiasmata terminalization were also recorded. Distinctly different in their behavior from st series soybean mutants, telophase I-originated micronuclei of different sizes organized their own spindle in the second division. This behavior contributed towards an increase in genome fractionation. Several microspores and microcytes of different sizes were recorded at the end of meiosis. Pollen sterility was estimated at 91.2%. Segregation ratio for sterility in this line and its progenies reached 3:1. Allelism tests with st series of synaptic mutants are in progress. The importance of male-sterile, female-fertile mutations for soybean breeding programs is discussed.
Assuntos
Genes de Plantas , Glycine max/genética , Mutação , Meiose/genética , Metáfase/genética , Fenômenos Fisiológicos Vegetais , Telófase/genéticaRESUMO
Many aneugenic compounds are known to affect one or more components of the mitotic apparatus leading to an erroneous migration of chromosomes. Malsegregation occurs when a chromosome (or a chromatid) fails to migrate and remains at the metaphase plate. Nondisjunction implies the lack of dissociation between sister chromatids and the migration of both together to the same pole. The aim of the present study was to provide evidence that the aneugenic effect of some metal salts is the consequence of malsegregation at anaphase and that it is not caused by nondisjunction mechanisms. The frequencies of lagging chromosomes at anaphase-telophase of mitosis, hypoploid metaphases, and kinetochore-positive micronuclei induced by cadmium chloride, potassium dichromate, and cacodilic acid (dimethylarsinic acid) in MRC-5 human cells were compared. The data indicate that all the tested compounds are able to induce aneuploidy in MRC-5 human cells. Positive, statistically significant correlations were found when kinetochore-positive micronuclei, hypoploidy, and lagging chromosome frequencies were compared. The results suggest that malsegregation is the main mechanism involved in the induction of aneuploidy by metal salts in MRC-5 cells.
Assuntos
Aneuploidia , Ácido Cacodílico/efeitos adversos , Cloreto de Cádmio/efeitos adversos , Metais/efeitos adversos , Dicromato de Potássio/efeitos adversos , Sais/efeitos adversos , Anáfase/efeitos dos fármacos , Ciclo Celular/efeitos dos fármacos , Linhagem Celular , Cromossomos/ultraestrutura , Corantes/efeitos adversos , Relação Dose-Resposta a Droga , Fibroblastos/citologia , Herbicidas/efeitos adversos , Humanos , Masculino , Testes para Micronúcleos , Não Disjunção Genética , Troca de Cromátide Irmã , Telófase/efeitos dos fármacos , Fatores de TempoRESUMO
As evidências de que a aneuploidia durante a mitose pode ser um fator na etiologia de malignidades somáticas estäo cada vez mais fortes. A análise de alteraçöes em anáfase-telófase da mitose é um teste útil para a avaliaçäo da capacidade aneuploidogênica e clastogênica de substâncias químicas. Vários metais têm sido identificados como carcinogênicos para o homem e para animais. Contudo, os mecanismos de açäo permanecem obscuros. No presente estudo, a capacidade aneugênica e clastogênica do sulfato de cádmio, do dicromato de potássio e do cloreto de níquel foi analisada usando o teste anáfase-telófase. Células do ovário do hamster chinês cultivadas por dois ciclos foram tratadas com o composto desejado por 8 horas antes da colheita das células. Foram quantificadas as freqüências de células com pontes de cromatina, lagging cromossomos e lagging fragmentos cromossômicos. O índice mitótico foi determinado pela contagem do número de células em mitose por 1000 células em cada lamínula e foi expresso como uma porcentagem do número de placas mitóticas. A análise estatística foi feita usando o método "G". Análises de correlaçäo e de regressäo foram realizadas para avaliar as variaçöes do índice mitótico. O crômio e o cádmio foram clastogênicos e aneugênicos e aumentaram as freqüências dos três tipos de aberraçöes avaliadas; o níquel teve apenas atividade aneugênica porque ele aumentou a freqüência de lagging cromossomos. Estes resultados indicam que o teste anáfase-telófase é sensível o suficiente para detectar as relaçöes dependentes da dose que podem distinguir as atividades clastogênicas e/ou aneugênicas e que os resultados obtidos usando o teste anáfase-telófase foram semelhantes aos obtidos pela contagem cromossômica.
Assuntos
Humanos , Animais , Masculino , Feminino , Anáfase , Cádmio/toxicidade , Cricetinae , Níquel/toxicidade , Potássio/toxicidade , Telófase , Aneuploidia , Técnicas de Cultura de Células , Hibridização in Situ Fluorescente , Testes de MutagenicidadeRESUMO
Aneugenic effects of the Vinca alkaloid vinorelbine (VRB) were evaluated in vitro, measuring sister chromatid exchanges (SCE), cell proliferation kinetics and anaphase telophase aberrations in Chinese hamster ovary (CHO) cells. The highest dose of VRB (0.50 microg/ml) arrested cells at the first metaphase. An increase in abnormal anaphases was seen at 0.05-0.50 microg/ml of VRB, containing chiefly lagging chromosomes and multipolar spindles. No increase in SCE was found. These results indicate that VRB does not directly damage DNA, but acts on spindle microtubules, altering chromosome movement and causing aneuploidy.
Assuntos
Anáfase/efeitos dos fármacos , Antineoplásicos Fitogênicos/farmacologia , Mitose/efeitos dos fármacos , Vimblastina/análogos & derivados , Animais , Células CHO , Ciclo Celular/efeitos dos fármacos , Divisão Celular/efeitos dos fármacos , Cricetinae , Cinética , Troca de Cromátide Irmã/efeitos dos fármacos , Telófase/efeitos dos fármacos , Vimblastina/farmacologia , VinorelbinaRESUMO
10(-6) M and 10(-5) M 5-azacytidine, demethylated around 9% and 17% of the 5-methylcytosine residues found in Allium cepa L. native DNA, respectively. Both treatments stimulated RNA synthesis in the cells of root meristems. On the other hand, the 10(-5) M treatment gave rise to multiple chromosomal anomalies in mitosis before any fall in the mitotic index was detectable, but no chromosomal breaks were ever seen. Serious lesions involved in chromatids and segregation in anaphase were preferentially found after hypomethylation of DNA sequences replicated in the second half of the previous S period: (i) sister telomeres remained unresolved at the cell equator while kinetochores had reached the poles, (ii) whole unsegregated chromosomes were pulled to one of the poles by obviously disfunctional kinetochores, resulting in an unbalanced distribution of chromatids, (iii) unsegregated chromosomes in other cells remained at the spindle equator as if kinetochores were nonfunctional, while cytoplasmic division took place before their migration to the poles. Frequently, a growing cytokinetic plate randomly cut the unsegregated chromosomes, giving rise to aneuploid nuclei. These anaphase failures are a firm basis to explain why the 10(-5) M treatment selectively depressed the rate of cell proliferation in these cells in the long run. On the other hand, if hypomethylation occurred at the first half of the previous S period, enlarged chromosomal segments were evident in most metaphases, while chromosome laggards and bridges were recorded in anaphase at rather similar frequencies after the different 5-azacytidine treatments. These data were consistently obtained both in the native mononucleate cells of meristems and in one subpopulation of synchronous cells labelled as binucleate by 5 mM caffeine.
Assuntos
Anáfase/genética , Cromossomos/fisiologia , DNA de Plantas/metabolismo , Allium , Azacitidina/farmacologia , Divisão Celular/efeitos dos fármacos , Cromátides/metabolismo , Cinética , Metilação , Mitose/efeitos dos fármacos , Telófase/efeitos dos fármacosAssuntos
Aldeídos/toxicidade , Aneuploidia , Cádmio/toxicidade , Cloretos/toxicidade , Cromossomos/efeitos dos fármacos , Anáfase/efeitos dos fármacos , Anáfase/genética , Animais , Células CHO , Cloreto de Cádmio , Cricetinae , Cricetulus , DNA/efeitos dos fármacos , DNA/metabolismo , Mitose/efeitos dos fármacos , Mutação Puntual/efeitos dos fármacos , Análise de Regressão , Telófase/efeitos dos fármacos , Telófase/genéticaRESUMO
The genotoxic activity of MTZ was evaluated in vitro with the anaphase-telophase test in a CHO cell line, chromosomal aberration and micronucleus test in lymphocyte cultures, and in vivo using the micronucleus test in mouse bone marrow cells. The In vivo test was performed using clinical trial doses (23, 70 and 160 mg/kg). A significant increase in micronucleated cells (p < 0.02) was observed in the three assayed doses with a linear dose response (r = 0.91). In vitro studies showed a significant increase in the percentage of abnormal anaphases (p < 0.05), in chromosome aberrations (p < 0.01) and in the frequency of micronuclei (p < 0.02) at all the concentrations assayed (0.1, 1 and 10 micrograms/ml). These findings demonstrate the clastogenic effect of this drug which should be taken into account considering its wide human consumption.
Assuntos
Aberrações Cromossômicas , Linfócitos/efeitos dos fármacos , Metronidazol/toxicidade , Mutagênicos/toxicidade , Anáfase , Animais , Células da Medula Óssea , Células CHO , Células Cultivadas , Cricetinae , Citocalasina B/farmacologia , Relação Dose-Resposta a Droga , Eritrócitos/efeitos dos fármacos , Feminino , Humanos , Linfócitos/citologia , Linfócitos/patologia , Masculino , Camundongos , Testes para Micronúcleos , Testes de Mutagenicidade , Fatores Sexuais , TelófaseRESUMO
The movement of microtubules (MTs) during nuclear division of Entamoeba histolytica was ultrastructurally studied. Regarding this MT movement, five stages of mitosis could be defined: prophase, metaphase, anaphase A, anaphase B, and telophase. In early stages of mitosis, chromatinic material appeared condensed, and MTs were detected in the center of the nucleus. Later, MTs seemed to grow from an electron-dense body located in the center of the nucleus. This body might be the microtubule organizing center, which organized the MTs, first in a lateral way, and later to form the mitotic spindle, which was made of a bundle of MTs joined by their ends. This junction of MTs to themselves could also be observed in cross-sections. The last stage of mitosis was the nuclear separation. Two different morphological types of intranuclear vesicles were also observed, which seemed to have different types of membrane. Both intranuclear vesicles were present during nuclear division, generally in clusters, and located close to the nuclear periphery.
Assuntos
Entamoeba histolytica/citologia , Microtúbulos/fisiologia , Mitose , Anáfase , Animais , Núcleo Celular/ultraestrutura , Entamoeba histolytica/ultraestrutura , Metáfase , Microscopia Eletrônica , Microtúbulos/ultraestrutura , Movimento , Prófase , Fuso Acromático/ultraestrutura , TelófaseRESUMO
El Mebendazole (MBZ), o 5-benzoyl- 1H-benzimidazole-2- il ácido metil éster carbámico fue estudiado con tres ensayos de corto plazo. Se probó su capacidad para inducir micronúcleos "in vivo" en eritrocitos policromáticos de médula ósea de ratones CFW. Se analizaron 3 dosis, 25, 50 y 100 mg/kg de peso corporal inyectados intraperitonealmente. Las 3 dieron incremento significativo (p < 0.01). Las pruebas "in vitro" se realizaron en células CHO. Se analizó la capacidad para inducir aberraciones cromosómicas y figuras anormales por prueba de anafase-telofase. Se detectó una frecuencia aumentada en la formación de dicéntricos, gaps, C-mitosis, puentes y cromosomas rezagados. La acción genotóxica observada puede asociarse con la estructura química de un æester carbámico derivado que sugeriría un papel de mutágeno directo
Assuntos
Camundongos , Animais , Aberrações Cromossômicas/genética , Células Cultivadas/citologia , Mebendazol/farmacologia , Medula Óssea/citologia , Testes de Mutagenicidade , Análise de Variância , Anáfase/genética , Sítios de Ligação/genética , Contagem de Células , Química , Citogenética , Injeções Intraperitoneais , Mebendazol/metabolismo , Telófase/genéticaRESUMO
El Mebendazole (MBZ), o 5-benzoyl- 1H-benzimidazole-2- il ácido metil éster carbámico fue estudiado con tres ensayos de corto plazo. Se probó su capacidad para inducir micronúcleos "in vivo" en eritrocitos policromáticos de médula ósea de ratones CFW. Se analizaron 3 dosis, 25, 50 y 100 mg/kg de peso corporal inyectados intraperitonealmente. Las 3 dieron incremento significativo (p < 0.01). Las pruebas "in vitro" se realizaron en células CHO. Se analizó la capacidad para inducir aberraciones cromosómicas y figuras anormales por prueba de anafase-telofase. Se detectó una frecuencia aumentada en la formación de dicéntricos, gaps, C-mitosis, puentes y cromosomas rezagados. La acción genotóxica observada puede asociarse con la estructura química de un µester carbámico derivado que sugeriría un papel de mutágeno directo (AU)