RESUMO
Small eggs have lesser amounts of nutrients to be used by the embryo, and the yolk glycerol is the main substrate for glycogen production, which is the main energy source in the last days of incubation. Thus, the present study aimed to assess the effect of a glycerol injection in light weight eggs at 2 different days of incubation. To this end, 336 light eggs (55.6 to 58.6 g) from 32-wk-old broiler breeders were incubated. The eggs were divided into 3 treatment groups: 1 group inoculated with saline solution on the 17th d of embryonic development (E17) (control group), the second group injected with a 6 mg glycerol/mL solution at E17, and the third group injected with 6 mg glycerol/mL on the 18th d of incubation (E18). Incubation parameters, liver and muscle glycogen, and broilers performance at 7 d of age were evaluated. Glycerol administration in ovo did not influence hatchability, period of embryonic death or early hatching. Chicks exposed to glycerol in ovo feeding (IOF) used more yolk than birds inoculated with saline solution. Glycerol inoculation at E18 enhanced liver glycogen deposition (P = 0.001) and also improved broilers performance at 7 d, although this improvement in performance and glycogen reserves was not observed when eggs were inoculated at 17 d of incubation. Birds receiving glycerol IOF at E18 showed higher feed intake and body weight gain when compared to the control group and the group inoculated at E17. It was found that glycerol inoculation in light eggs at the 18th d of incubation contributed to raise liver glycerol levels and also to improve broilers performance at 7 d.
Assuntos
Embrião de Galinha/efeitos dos fármacos , Galinhas/fisiologia , Glicerol/metabolismo , Óvulo/efeitos dos fármacos , Animais , Embrião de Galinha/metabolismo , Galinhas/crescimento & desenvolvimento , Metabolismo Energético , Glicerol/administração & dosagem , Glicogênio/metabolismo , Injeções/veterinária , Óvulo/metabolismo , Fatores de TempoRESUMO
By the end of 2018, 42 years after the landing of the two Viking seismometers on Mars, InSight will deploy onto Mars' surface the SEIS (Seismic Experiment for Internal Structure) instrument; a six-axes seismometer equipped with both a long-period three-axes Very Broad Band (VBB) instrument and a three-axes short-period (SP) instrument. These six sensors will cover a broad range of the seismic bandwidth, from 0.01 Hz to 50 Hz, with possible extension to longer periods. Data will be transmitted in the form of three continuous VBB components at 2 sample per second (sps), an estimation of the short period energy content from the SP at 1 sps and a continuous compound VBB/SP vertical axis at 10 sps. The continuous streams will be augmented by requested event data with sample rates from 20 to 100 sps. SEIS will improve upon the existing resolution of Viking's Mars seismic monitoring by a factor of â¼ 2500 at 1 Hz and â¼ 200 000 at 0.1 Hz. An additional major improvement is that, contrary to Viking, the seismometers will be deployed via a robotic arm directly onto Mars' surface and will be protected against temperature and wind by highly efficient thermal and wind shielding. Based on existing knowledge of Mars, it is reasonable to infer a moment magnitude detection threshold of M w â¼ 3 at 40 ∘ epicentral distance and a potential to detect several tens of quakes and about five impacts per year. In this paper, we first describe the science goals of the experiment and the rationale used to define its requirements. We then provide a detailed description of the hardware, from the sensors to the deployment system and associated performance, including transfer functions of the seismic sensors and temperature sensors. We conclude by describing the experiment ground segment, including data processing services, outreach and education networks and provide a description of the format to be used for future data distribution. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (10.1007/s11214-018-0574-6) contains supplementary material, which is available to authorized users.
RESUMO
AIMS: To evaluate the influence of storage conditions on the composition of the bacterial microbiota of living oysters Crassostrea gasar. METHODS AND RESULTS: The oysters used in this study came from marine farms (Guaratuba Bay, Brazil) and were exposed to two conditions that simulated different storage situations: immersion in water (group I) and exposure to air (group II). The animals were subjected to five different temperatures (5-25°C), for 10 days. The 16S rRNA gene from oysters was amplified and sequenced to determine the taxonomic units and bacterial strains present in the samples. Group I showed higher diversity of bacteria (163 genera) rather than group II (104 genera). In all, 59 bacterial genera potentially pathogenic to humans were identified (n = 56 in group I and n = 45 in group II). CONCLUSIONS: The storage conditions having a direct influence on the oyster microbiota. Live C. gasar should be stored exposed to air at 5-25°C, because it favours a lower prevalence of bacteria potentially pathogenic to humans. SIGNIFICANCE AND IMPACT OF THE STUDY: During the oyster commercialization process, some conditions of storage, time and temperature must be followed in order to reduce the prevalence of bacteria potentially pathogenic to humans.
Assuntos
Crassostrea/microbiologia , Armazenamento de Alimentos/métodos , Microbiota , Alimentos Marinhos , Animais , Brasil , Inocuidade dos Alimentos , Humanos , Metagenômica , RNA Ribossômico 16S/genética , TemperaturaRESUMO
Airway inflammation is the most common hallmark of allergic asthma. Chemokine receptors involved in leukocyte recruitment are closely related to the pathology in asthma. CCR9 has been described as a homeostatic and inflammatory chemokine receptor, but its role and that of its ligand CCL25 during lung inflammation remain unknown. To investigate the role of CCR9 as a modulator of airway inflammation, we established an OVA-induced allergic inflammation model in CCR9-deficient mice. Here, we report the expression of CCR9 and CCL25 as early as 6 hours post-OVA challenge in eosinophils and T-lymphocytes. Moreover, in challenged CCR9-deficient mice, cell recruitment was impaired at peribronchial and perivenular levels. OVA-administration in CCR9-deficient mice leads to a less inflammatory cell recruitment, which modifies the expression of IL-10, CCL11, and CCL25 at 24 hours after OVA challenge. In contrast, the secretion of IL-4 and IL-5 was not affected in CCR9-deficient mice compared to WT mice. These results demonstrate for the first time that CCR9 and CCL25 expressions are induced in the early stages of airway inflammation and they have an important role modulating eosinophils and lymphocytes recruitment at the first stages of inflammatory process, suggesting that they might be a potential target to regulate inflammation in asthma.
Assuntos
Quimiocinas CC/metabolismo , Regulação da Expressão Gênica , Hipersensibilidade/metabolismo , Inflamação/metabolismo , Receptores CCR/metabolismo , Animais , Líquido da Lavagem Broncoalveolar , Separação Celular , Citocinas/metabolismo , Ensaio de Imunoadsorção Enzimática , Eosinófilos/citologia , Feminino , Citometria de Fluxo , Imunoglobulina E/sangue , Leucócitos/citologia , Pulmão/fisiopatologia , Linfócitos/citologia , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Linfócitos T/citologiaRESUMO
Depression is a neuropsychiatric disorder that is commonly found in patients with Parkinson's disease (PD). Many studies have suggested that physical exercise can have an antidepressant effect by increasing the levels of brain-derived neurotrophic factor (BDNF), and may also prevent neurodegenerative disease. However, different forms of training may promote different changes in the brain. The aim of this study was to investigate the effects of two types of physical training on depressive-like behavior, and on the levels of proBDNF, BDNF, and its receptor, TrkB, in a mouse model of PD. C57BL/6 mice were subjected to 60 days of exercise: either running on a treadmill or performing a strength exercise. PD was induced by striatal administration of 6-OHDA 24h after the last physical exercise session. Seven days after 6-OHDA injection, depressive-like behavior and apomorphine-induced rotational behavior were evaluated. The levels of proBDNF, BDNF, and TRKB were measured in the striatum and the hippocampus of mice by immunoblotting assay. The 6-OHDA-treated animals showed a significant increase in immobility time and rotational behavior compared with the control group. In addition, significant decreases in the levels of proBDNF, BDNF, and its receptor, TrkB were observed in the 6-OHDA group. Both types of physical exercise prevented depressive-like behavior and restored the levels of proBDNF, BDNF, and TrkB in the striatum and hippocampus of mice administered 6-OHDA. Our results demonstrate that exercise training was effective for neuroprotection in the striatum and the hippocampus in an experimental model of PD.
Assuntos
Fator Neurotrófico Derivado do Encéfalo/metabolismo , Depressão/metabolismo , Depressão/prevenção & controle , Terapia por Exercício , Doença de Parkinson/metabolismo , Animais , Depressão/etiologia , Modelos Animais de Doenças , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Atividade Motora , Oxidopamina/toxicidade , Doença de Parkinson/complicações , Receptor trkB/metabolismoRESUMO
The objective of the present study was to elaborate a survival model that integrates anatomic factors, according to the 2010 seventh edition of the tumour, node and metastasis (TNM) staging system, with clinical and molecular factors. Pathologic TNM descriptors (group A), clinical variables (group B), laboratory parameters (group C) and molecular markers (tissue microarrays; group D) were collected from 512 early-stage nonsmall cell lung cancer (NSCLC) patients with complete resection. A multivariate analysis stepped supervised learning classification algorithm was used. The prognostic performance by groups was: areas under the receiver operating characteristic curve (C-index): 0.67 (group A), 0.65 (Group B), 0.57 (group C) and 0.65 (group D). Considering all variables together selected for each of the four groups (integrated group) the C-index was 0.74 (95% CI 0.70-0.79), with statistically significant differences compared with each isolated group (from p = 0.006 to p < 0.001). Variables with the greatest prognostic discrimination were the presence of another ipsilobar nodule and tumour size > 3 cm, followed by other anatomical and clinical factors, and molecular expressions of phosphorylated mammalian target of rapamycin (phospho-mTOR), Ki67cell proliferation index and phosphorylated acetyl-coenzyme A carboxylase. This study on early-stage NSCLC shows the benefit from integrating pathological TNM, clinical and molecular factors into a composite prognostic model. The model of the integrated group classified patients with significantly higher accuracy compared to the TNM 2010 staging.
Assuntos
Carcinoma Pulmonar de Células não Pequenas/diagnóstico , Carcinoma Pulmonar de Células não Pequenas/genética , Neoplasias Pulmonares/diagnóstico , Neoplasias Pulmonares/genética , Estadiamento de Neoplasias/métodos , Idoso , Algoritmos , Área Sob a Curva , Carcinoma Pulmonar de Células não Pequenas/terapia , Estudos de Coortes , Humanos , Antígeno Ki-67/biossíntese , Neoplasias Pulmonares/terapia , Oncologia/métodos , Pessoa de Meia-Idade , Metástase Neoplásica , Probabilidade , Prognóstico , Fatores de TempoRESUMO
OBJECTIVE: To analyze the survival of patients undergoing lung resection for N2 bronchogenic carcinoma with negative findings at mediastinoscopy. MATERIAL AND METHOD: Twenty-nine patients with N2 bronchogenic carcinoma were analyzed. The patients were taken from a series of 170 patients who underwent surgery between 1993 and 1997 and whose data were recorded by the Bronchogenic Carcinoma Cooperative Group of the Spanish Society of Pneumology and Thoracic Surgery (GCCB-S). In 26 patients, nodes were found in the upper mediastinum; in three patients nodes were paraesophageal or in the area of the pulmonary ligament. In 11 cases, extracapsular nodal disease was found. Three patients who died in the postoperative period were excluded from survival analysis. RESULTS: The five-year survival rate for the series of 170 patients was 39%. For the 26 patients with N2 carcinoma, five-year survival was 14% (median 12 months). Five-year survival for the remaining patients (excluding those with N2 carcinoma) was 46%. Although the median survival of patients with intracapsular nodal disease was more than twice (25 months) that of patients with extracapsular nodal disease (12 months), the difference was not significant. CONCLUSIONS: Lung resection in patients with N2 bronchogenic carcinoma with negative mediastinoscopy has little impact on survival. Surgical exploration of the mediastinum classifies such patients with greatest certainty, although the sensitivity of staging techniques warrants improvement to assure that thoracotomy is not used unnecessarily.
Assuntos
Carcinoma Broncogênico/mortalidade , Carcinoma Broncogênico/cirurgia , Neoplasias Pulmonares/mortalidade , Neoplasias Pulmonares/cirurgia , Adulto , Idoso , Carcinoma Broncogênico/patologia , Reações Falso-Negativas , Feminino , Humanos , Neoplasias Pulmonares/patologia , Masculino , Mediastinoscopia , Pessoa de Meia-Idade , Estadiamento de Neoplasias , Taxa de SobrevidaRESUMO
BACKGROUND: This study was undertaken to evaluate the technical feasibility and the sensitivity, specificity, and accuracy of remediastinoscopy in restaging N2 bronchogenic carcinoma treated with neoadjuvant chemotherapy. METHODS: Patients presenting mediastinal lymph node involvement at mediastinoscopy received three or four cycles of neoadjuvant chemotherapy with mitomycin, iphosphamide, and cisplatin or cisplatin and gemcitabine. If there was no disease progression, these patients underwent remediastinoscopy and, if no residual extracapsular involvement or N3 disease was found, a thoracotomy was then carried out. RESULTS: Twenty-four patients underwent remediastinoscopy. In 12 (50%) remediastinoscopy was positive. The 12 remaining patients were operated on and the tumors resected: 5 pneumonectomies and 7 lobectomies. Lymphadenectomy specimens showed residual disease in mediastinal lymph nodes in 5 patients (pN2) and hilar lymph nodes in 1 patient (pN1). The other 6 patients were free of nodal disease, and 4 of them presented no involvement at lung level either. The sensitivity, specificity, and accuracy of remediastinoscopy were 0.7, 1, and 0.8, respectively. CONCLUSIONS: Remediastinoscopy is a technically feasible staging tool with high diagnostic accuracy that is useful in the selection of patients who can be served best by complete resection after neoadjuvant chemotherapy.
Assuntos
Protocolos de Quimioterapia Combinada Antineoplásica/uso terapêutico , Carcinoma Broncogênico/tratamento farmacológico , Carcinoma Pulmonar de Células não Pequenas/tratamento farmacológico , Neoplasias Pulmonares/tratamento farmacológico , Mediastinoscopia , Idoso , Carcinoma Broncogênico/cirurgia , Carcinoma Pulmonar de Células não Pequenas/cirurgia , Quimioterapia Adjuvante , Estudos de Viabilidade , Humanos , Neoplasias Pulmonares/cirurgia , Masculino , Pessoa de Meia-Idade , Estadiamento de Neoplasias/métodos , Reoperação , Sensibilidade e EspecificidadeRESUMO
We sequenced a 2.1 kb fragment of DNA carrying the structural glsA gene, which codes for the Rhizobium etli thermolabile glutaminase (A). The glsA gene complements the R. etli LM16 mutant that lacks glutaminase A activity, and is expressed in the heterologous host Sinorhizobium meliloti. The deduced amino acid sequence consists of 309 residues, with a calculated molecular mass of 33 kDa. The amino acid sequence shares 53% and 43% identity with two hypothetical glutaminases of E. coli; 42% identity with liver-type; 38% identity with kidney-type glutaminase; 41% and 40% identity hypothetical glutaminases of Bacillus subtilis; and 41% and 37% identity with two putative glutaminases of Caenorhabditis elegans. The glsA gene represents the first glutaminase gene cloned and sequenced in prokaryotes.
Assuntos
Proteínas de Bactérias , Glutaminase/genética , Rhizobium/genética , Sequência de Aminoácidos , Sequência de Bases , DNA/química , Proteínas de Choque Térmico/genética , Dados de Sequência Molecular , Rhizobium/enzimologia , Alinhamento de SequênciaRESUMO
Rhizobium etli mutants unable to grow on asparagine as the nitrogen and carbon source were isolated. Two kinds of mutants were obtained: AHZ1, with very low levels of aspartase activity, and AHZ7, with low levels of asparaginase and very low levels of aspartase compared to the wild-type strain. R. etli had two asparaginases differentiated by their thermostabilities, electrophoretic mobilities, and modes of regulation. The AHZ mutants nodulated as did the wild-type strain and had nitrogenase levels similar to that of the wild-type strain.
Assuntos
Asparaginase/metabolismo , Asparagina/metabolismo , Aspartato Amônia-Liase/metabolismo , Rhizobium/genética , Asparaginase/genética , Ácido Aspártico/metabolismo , Clonagem Molecular , Estabilidade Enzimática , Genes Bacterianos , Teste de Complementação Genética , Ácido Glutâmico/metabolismo , Glutamina/metabolismo , Isoenzimas/metabolismo , Mutação , Nitrogenase/metabolismo , Rhizobium/crescimento & desenvolvimento , Rhizobium/metabolismo , TemperaturaRESUMO
We present evidence that Rhizobium etli has two glutaminases differentiated by their thermostability and electrophoretic mobility. The thermostable glutaminase (B) is constitutive, in contrast with the thermolabile glutaminase (A), which is positively regulated by glutamine and negatively regulated by ammonium and by the carbon source. In distinction to glutaminase A, glutaminase B plays a minor role in the utilization of glutamine as a carbon source, but it may play a role in maintaining the balance of glutamine and glutamate. By complementation of the Rhizobium etli LM16 mutant that lacks glutaminase A, we have cloned the gene that codes for this enzyme.
Assuntos
Glutaminase/metabolismo , Isoenzimas/metabolismo , Rhizobium/enzimologia , Clonagem Molecular , Estabilidade Enzimática , Genes Bacterianos/genética , Teste de Complementação Genética , Glutaminase/química , Glutaminase/genética , Glutamina/metabolismo , Temperatura Alta , Isoenzimas/química , Isoenzimas/genética , Compostos de Amônio Quaternário/metabolismo , Rhizobium/genética , Rhizobium/crescimento & desenvolvimento , Succinatos/metabolismo , Ácido SuccínicoRESUMO
In order to examine the role of glutaminase in Rhizobium etli, we isolated and characterized a R. etli glutaminase mutant (LM16). This mutant was selected for its impaired ability to grow on glutamine as nitrogen and carbon source while retaining the ability to grow on other nitrogen and carbon sources. The mutant showed very low levels of glutaminase activity under various growth conditions in comparison with the wild-type strain. With glutamine as the only nitrogen and carbon source, LM16 showed poor growth, with a very high content of glutamine, low glutamate content, and reduced ammonium excretion and 14CO2 evolution from [U-14C]glutamine compared to the wild-type strain. This indicates that the main role of R. etli glutaminase is in the use of glutamine as carbon source. R. etli glutaminase also plays a role in maintaining the balance between glutamate and glutamine, as shown by the accumulation of glutamine and the low glutamate content of the mutant under different growth conditions. These results also indicate that glutaminase participates in a glutamine cycle in which it degrades glutamine which is then resynthesized by glutamine synthetase. The higher glutamine and lower glutamate content found in bacteroids of LM16 in comparison with bacteroids of the wild-type strain indicate that glutamine degradation by glutaminase plays an important role during the symbiosis between R. etli and Phaseolus vulgaris.
Assuntos
Glutaminase/metabolismo , Rhizobium/metabolismo , Fabaceae/microbiologia , Glutamato-Amônia Ligase/metabolismo , Ácido Glutâmico/metabolismo , Glutaminase/genética , Glutamina/metabolismo , Mutação , Nitrogênio/metabolismo , Fenótipo , Plantas Medicinais , Rhizobium/genética , Rhizobium/crescimento & desenvolvimento , Simbiose/genética , Simbiose/fisiologiaRESUMO
A case of a 39-year-old woman with a palpable mass in the right hemithorax is presented. The mass had been growing during the last 16 years. Radiographs and computed tomography showed two lesions in the right thoracic wall: the greater was in the anterior and lateral portion of the 7th rib, the minor lesion in the 6th rib costovertebral joint. Both lesions were surgically removed. Histological examination demonstrated the association of fibrous dysplasia and aneurysmal bone cyst in the two lesions. The coexistence of these two lesions supports the theory that aneurysmal bone cyst may represent a secondary change due to haemodynamic alterations of the vascular bed caused by fibrous dysplasia.
Assuntos
Cistos Ósseos Aneurismáticos/complicações , Displasia Fibrosa Poliostótica/complicações , Doenças Torácicas/complicações , Adulto , Cistos Ósseos Aneurismáticos/diagnóstico por imagem , Cistos Ósseos Aneurismáticos/patologia , Feminino , Displasia Fibrosa Poliostótica/diagnóstico por imagem , Displasia Fibrosa Poliostótica/patologia , Humanos , Radiografia Torácica , Doenças Torácicas/diagnóstico por imagem , Doenças Torácicas/patologia , Tomografia Computadorizada por Raios XRESUMO
Extrabronchial small cell carcinoma (ESCC) is an infrequent tumor with controversial histogenesis, clinical evolution and therapeutic strategy. The aim of this study was to know the immunohistochemical features and the clinical evolution of patients diagnosed of ESCC during a 10 year period. All the diagnoses of small cell carcinoma (bronchial and extrabronchial) carried out by the Unit of Pathology between 1980-1989 were reviewed. In all the ESCC an immunohistochemical study was performed with three neuroendocrine markers, chromogranin, neurospecific enolase and synaptophysin. The clinical evolution of the patients is described. The 6 patients with ESCC represented 4.7% of all the small cell carcinomas. The primary localization was: parotid, urinary bladder, the skin, maxillary sinus and esophagus (2 patients). In five cases positivity was observed for one or more of the neuroendocrine markers. In two cases the ESCC was associated with differentiated cell populations (squamous carcinoma). The diagnosis of ESCC logically obliges the bronchial origin and the presence of ectopic hormonal secretion syndromes to be discarded. The administration of chemotherapy regimes used in small cell lung carcinoma is advised.
Assuntos
Carcinoma de Células Pequenas/patologia , Neoplasias Esofágicas/patologia , Neoplasias do Seio Maxilar/patologia , Neoplasias Parotídeas/patologia , Neoplasias Cutâneas/patologia , Neoplasias da Bexiga Urinária/patologia , Idoso , Idoso de 80 Anos ou mais , Carcinoma de Células Pequenas/metabolismo , Neoplasias Esofágicas/metabolismo , Feminino , Humanos , Imuno-Histoquímica , Masculino , Neoplasias do Seio Maxilar/metabolismo , Pessoa de Meia-Idade , Neoplasias Parotídeas/metabolismo , Neoplasias Cutâneas/metabolismo , Neoplasias da Bexiga Urinária/metabolismoRESUMO
We established the size distribution of extrachromosomal covalently closed circular DNA molecules from embryos of various Drosophila melanogaster strains and from Kc0% tissue culture cells. In embryos, more than 80% of the circular DNA molecules are smaller than 2.5 kb and all the distributions show a peak of molecules of between 200 and 400 bp. The Kc0% cell distribution differs mainly from that of embryos in that 48% of the molecules have a size between 4 and 8 kb. Correlating with this, circular molecules homologous to copia, 412 and 297 were detected only in Kc0% cells. The three tandemly repeated families containing the 5S genes, the histone genes and the 240 bp repeat of the ribosomal DNA intergenic spacer, which had previously been identified in circular DNAs from embryos, were also found in cultured cells. A fourth tandemly repeated family corresponding to the 1.688 g/cm3 satellite DNA was detected, both in embryos and Kc0% cells. It consists of circular multimeric molecules containing multiple copies of the 359 bp repeated unit. No circular DNA molecules homologous to the actin genes, the type I ribosomal DNA insertion, or the F and I transposable elements were found in embryos or Kc0% cells. Thus it appears that the extrachromosomal circular DNA molecules from embryos and from tissue culture cells differ mainly in the presence of circular copies of the copia-like transposable elements.
Assuntos
Sequência de Bases , DNA Circular/análise , Drosophila melanogaster/genética , Herança Extracromossômica , Homologia de Sequência do Ácido Nucleico , Animais , DNA Circular/ultraestrutura , DNA Satélite/análise , DNA Satélite/ultraestrutura , Embrião não Mamífero/química , Embrião não Mamífero/ultraestrutura , Feminino , Hibridização de Ácido Nucleico , Sequências Repetitivas de Ácido NucleicoRESUMO
From extrachromosomal covalently closed circular DNA molecules purified from Drosophila melanogaster embryos, we have isolated 24 clones homologous to the histone tandemly repeated gene family. Some of the clones harbor one of the two main types of genomic repeated units of 4.8 and 5.0 kb. and probably result from homologous recombination. The remaining clones have a size ranging from 0.2 to 2.5 kb. and most of them carry a single fragment of the repeated unit. Nucleotide sequences of the junction region of six of these clones indicate they are generated by illegitimate recombination between short (8-15 bp.) imperfect direct repeats. The data suggest that most of the histone homologous circular DNA molecules are deleted histone units.
Assuntos
DNA Circular/genética , Drosophila melanogaster/genética , Histonas/genética , Recombinação Genética , Animais , Sequência de Bases , Southern Blotting , Clonagem Molecular , Drosophila melanogaster/embriologia , Herança Extracromossômica , Dados de Sequência Molecular , Família Multigênica , Sequências Repetitivas de Ácido Nucleico , Mapeamento por RestriçãoRESUMO
In Drosophila melanogaster embryos we have identified three classes of extrachromosomal circular DNA molecules homologous to the three main families of tandemly repeated genes, 5 S, rDNA and histone. 5 S genes are present in circular multimeric molecules containing up to 16 copies of the 375(+/- 7) base-pair repeated unit. Circular molecules homologous to rDNA are also multimeric molecules, which contain up to ten copies of the 240 base-pair tandemly repeated sequence of the non-transcribed spacer. The two major genomic classes of histone units (4800 and 5000 bases) are found only as monomeric circular molecules. No circular intermediate of the I transposable element was detected in embryos laid by F1 dysgenic females produced by the I-R system of hybrid dysgenesis. As far as we know, it is the first time that genes have been identified among extrachromosomal circular molecules independently of any specific amplification phenomenon.