RESUMO
One of the most important laboratory animal species is the nematode Caenorhabditis elegans, which has been used in a range of research fields such as neurobiology, body development, and molecular biology. The scientific progress obtained by employing C. elegans as a model in these areas has encouraged its use in new fields. One of the new potential applications concerns the biological responses to hyperacceleration stress (g-force), but only a few studies have evaluated the response of multicellular organisms to extreme hypergravity conditions at the order of magnitude 105 x g, which is the theorized force experienced by rocks ejected from Mars (or similar planets). Therefore, we subjected the nematode C. elegans to 400,000 x g (equivalent to that force) and evaluated viability, general morphology, and behavior of C. elegans after exposure to this stress. The metabolic activity of this nematode in response to the gravitational spectrum of 50-400,000 x g was also evaluated by means of the MTT assay. Surprisingly, we found that this organism showed no decrease in viability, no changes in behavior and development, and no drastic metabolic depression after hyperacceleration. Thus, we demonstrated for the first time that this multicellular research model can withstand extremely high g-forces, which prompts the use of C. elegans as a new model for extreme hypergravity. Key Words: Caenorhabditis elegans-Hypergravity-Ultracentrifugation-Acceleration-Panspermia-Astrobiology. Astrobiology 18, 825-833.
Assuntos
Aceleração/efeitos adversos , Caenorhabditis elegans/fisiologia , Exobiologia/métodos , Hipergravidade/efeitos adversos , Estresse Fisiológico/fisiologia , Animais , Modelos AnimaisRESUMO
The aim of this study was to investigate the impacts of positive acceleration (+Gz) on the gastric mucosal tissues in cases of acute gastric mucosal injury and to explore the role of oxygen free radicals. Thirty Sprague Dawley rats were randomly divided into the absolute ethanol control group (A group), absolute ethanol +5Gz group (B group), absolute ethanol +10Gz group (C group). Following centrifugation, the gastric tissues of each group were studied for the presence of gastric mucosal injuries and morphological changes. The concentrations of malondialdehyde (MDA) and superoxide dismutase (SOD) contents were simultaneously investigated. Degree of gastric mucosal injuries were as follows: C group (visually 49.080 ± 10.254, under light microscopy 9.400 ± 2.011) > B group (visually 23.654 ± 9.678, under light microscopy 5.000 ± 1.054) > A group (visually 11.410 ± 3.742, under light microscopy 3.800 ± 1.399). The gastric mucosal MDA content (0.376 ± 0.084 vs 0.235 ± 0.044) was significantly higher in the C group than in the A group, whereas the SOD content (8.852 ± 1.001 vs 10.694 ± 0.965) was lower than that in the A group. However, the MDA and SOD contents did not change much in the B group. Our results suggest that the +Gz exposure might aggravate the acute gastric mucosal injury, and changes in MDA and SOD contents in the gastric tissues indicated that the oxygen free radicals play an important role in this regard.
Assuntos
Mucosa Gástrica/lesões , Hipergravidade/efeitos adversos , Malondialdeído/análise , Superóxido Dismutase/análise , Doença Aguda , Animais , Etanol/toxicidade , Mucosa Gástrica/efeitos dos fármacos , Estresse Oxidativo/efeitos dos fármacos , Ratos , Ratos Sprague-Dawley , Superóxido Dismutase/efeitos dos fármacosRESUMO
Stimulation by a number of conditions, including infection, cytokines, mechanical injury, and hypoxia, can upregulate inducible nitric oxide synthase (iNOS) in hepatocytes. We observed that exposure to hypergravity significantly upregulated the transcription of the hepatic iNOS gene. The aim of this study was to confirm our preliminary data, and to further investigate the distribution of the iNOS protein in the livers of mice exposed to hypergravity. ICR mice were exposed to +3 Gz for 1 h. We investigated the time course of change in the iNOS expression. Hepatic iNOS mRNA expression progressively increased in centrifuged mice from 0 to 12 h, and then decreased rapidly by 18 h. iNOS mRNA levels in the livers of centrifuged mice was significantly higher at 3, 6, and 12 h than in uncentrifuged control mice. The pattern of iNOS protein expression paralleled that of the mRNA expression. At 0 and 1 h, weak cytoplasmic iNOS immunoreactivity was found in some hepatocytes surrounding terminal hepatic venules. It was noted that at 6 h there was an increase in the number of perivenular hepatocytes with moderate to strong cytoplasmic immunoreactivity. The number of iNOS-positive hepatocytes was maximally increased at 12 h. The majority of positively stained cells showed a strong intensity of iNOS expression. The expression levels of iNOS mRNA and protein were significantly increased in the livers of mice exposed to hypergravity. These results suggest that exposure to hypergravity significantly upregulates iNOS at both transcriptional and translational levels.
Assuntos
Animais , Expressão Gênica/fisiologia , Hipergravidade , Fígado/enzimologia , Óxido Nítrico Sintase Tipo II/metabolismo , RNA Mensageiro/metabolismo , Ensaio de Imunoadsorção Enzimática , Hipergravidade/efeitos adversos , Imuno-Histoquímica , Mediadores da Inflamação/metabolismo , Interferon gama/análise , Interleucina-1beta/análise , /análise , Fígado/anatomia & histologia , Fígado/fisiologia , Camundongos Endogâmicos ICR , Óxido Nítrico Sintase Tipo II/genética , Biossíntese de Proteínas/fisiologia , Reação em Cadeia da Polimerase em Tempo Real , Transcrição Gênica/fisiologia , Fator de Necrose Tumoral alfa/análise , Regulação para Cima/fisiologiaRESUMO
Stimulation by a number of conditions, including infection, cytokines, mechanical injury, and hypoxia, can upregulate inducible nitric oxide synthase (iNOS) in hepatocytes. We observed that exposure to hypergravity significantly upregulated the transcription of the hepatic iNOS gene. The aim of this study was to confirm our preliminary data, and to further investigate the distribution of the iNOS protein in the livers of mice exposed to hypergravity. ICR mice were exposed to +3 Gz for 1 h. We investigated the time course of change in the iNOS expression. Hepatic iNOS mRNA expression progressively increased in centrifuged mice from 0 to 12 h, and then decreased rapidly by 18 h. iNOS mRNA levels in the livers of centrifuged mice was significantly higher at 3, 6, and 12 h than in uncentrifuged control mice. The pattern of iNOS protein expression paralleled that of the mRNA expression. At 0 and 1 h, weak cytoplasmic iNOS immunoreactivity was found in some hepatocytes surrounding terminal hepatic venules. It was noted that at 6 h there was an increase in the number of perivenular hepatocytes with moderate to strong cytoplasmic immunoreactivity. The number of iNOS-positive hepatocytes was maximally increased at 12 h. The majority of positively stained cells showed a strong intensity of iNOS expression. The expression levels of iNOS mRNA and protein were significantly increased in the livers of mice exposed to hypergravity. These results suggest that exposure to hypergravity significantly upregulates iNOS at both transcriptional and translational levels.
Assuntos
Expressão Gênica/fisiologia , Hipergravidade , Fígado/enzimologia , Óxido Nítrico Sintase Tipo II/metabolismo , RNA Mensageiro/metabolismo , Animais , Ensaio de Imunoadsorção Enzimática , Hipergravidade/efeitos adversos , Imuno-Histoquímica , Mediadores da Inflamação/metabolismo , Interferon gama/análise , Interleucina-1beta/análise , Interleucina-6/análise , Fígado/anatomia & histologia , Fígado/fisiologia , Camundongos Endogâmicos ICR , Óxido Nítrico Sintase Tipo II/genética , Biossíntese de Proteínas/fisiologia , Reação em Cadeia da Polimerase em Tempo Real , Transcrição Gênica/fisiologia , Fator de Necrose Tumoral alfa/análise , Regulação para Cima/fisiologiaRESUMO
The objective was to evaluate the effect of Percoll volume, and duration and force of centrifugation on sperm quality characteristics, embryo development, and sex ratio of in vitro-produced (IVP) bovine embryos. Frozen-thawed semen from four bulls were submitted to three Percoll procedures: T1-4 mL of Percoll, centrifuged for 20 min at 700 g; T2-800 microL of Percoll, centrifuged for 20 min at 700 g; and T3-800 microL of Percoll, centrifuged for 5 min at 5,000 g. Sperm total motility, morphology and integrity of the sperm acrosome, membrane and chromatin were determined before and after Percoll treatment, and semen was used for in vitro fertilization (IVF) of in vitro-matured oocytes. All Percoll methods increased the proportion of motile sperm (P<0.05). There were no significant effects of treatment for any sperm characteristic; however, for every end point, there were significant differences among bulls. Similarly, rates of cleavage and blastocyst formation were not affected by the Percoll procedure (P>0.05), but were affected by sire (P<0.05). Sex ratio was similar among treatments for Bulls 2 and 3, whereas semen from Bull 1 processed by T1 yielded a greater percentage of male embryos. However, when only treatments were considered, independent of bulls, the proportion of male:female embryos did not differ significantly from an expected 1:1 ratio. In conclusion, decreasing Percoll volume, reducing duration of centrifugation, and using a higher force of centrifugation did not significantly affect sperm quality, embryo development, or sex ratio of in vitro-produced bovine embryos.