RESUMO
The Caenorhabditis elegans genome has several regular and irregular characteristics in its nucleotide composition; these are observed within and between chromosomes. To study these particularities, we carried out a multifractal analysis, which requires a large number of exponents to characterize scaling properties. We looked for a relationship between the genetic information content of the chromosomes and multifractal parameters and found less multifractality compared to the human genome. Differences in multifractality among chromosomes and in regions of chromosomes, and two group averages of chromosome regions were observed. All these differences were mainly dependent on differences in the contents of repetitive DNA. Based on these properties, we propose a nonlinear model for the structure of the C. elegans genome, with some biological implications. These results suggest that examining differences in multifractality is a viable approach for measuring local variations of genomic information contents along chromosomes. This approach could be extended to other genomes in order to characterize structural and functional regions of chromosomes.
Assuntos
Caenorhabditis elegans/genética , Genoma , Animais , Cromossomos/genética , Etiquetas de Sequências Expressas , Fractais , Genoma Humano , Humanos , Modelos Genéticos , Modelos Estatísticos , Dinâmica não Linear , Análise de Sequência de DNARESUMO
Regulation of human olfactory receptor (hOR) genes is a complex process of control and signalization with various structures and functions that are not clearly understood. To date, nearly 390 functional hOR genes and 462 pseudogenes have been discovered in the human genome. Enhancer models and trans-acting elements for the regulation of different hOR genes are among the few examples of our knowledge concerning regulation of these genes. We looked for upstream control elements that might help explain these complex control mechanisms. To analyze the human olfactory gene family, we looked for functional genes and pseudogenes common to all hOR genes obtained from public databases. Subsequently, we analyzed sequences upstream of the transcription start sites with data mining and bioinformatics tools. We found two highly conserved regions, which we called HCR I and HCR II, upstream of the transcription start sites in 77 hOR genes and 87 pseudogenes. These regions showed possible enhancer functions common to both genes and pseudogenes, an intriguing feature that may be associated with the expression of pseudogenes. Based on these HCRs, we propose a structural model of gene regulation for the olfactory gene family.
Assuntos
Região 5'-Flanqueadora , Receptores Odorantes/genética , Sequência de Aminoácidos , Sequência de Bases , Sequência Conservada , Elementos Facilitadores Genéticos , Humanos , Dados de Sequência Molecular , Filogenia , PseudogenesRESUMO
Whole body oxygen consumption and some hemolymph parameters such as pH, partial pressure of gases, level of ions and lactate were measured in the estuarine crab Chasmagnathus granulata after both acute (96 h) and chronic (2 weeks) exposure to cadmium at concentrations ranging from 0.4 to 6.3 mg/l. In all instances, the crabs developed hemolymph acidosis, but no respiratory (increased PCO2) or lactate increases were evident. Hemolymph levels of sodium and calcium were always increased by cadmium exposure. The chronic toxicity of cadmium was enhanced at 12 per mil salinity, even causing a significantly higher mortality in comparison with the higher salinity (30 per mil ) used. A general metabolic arrest took place at 12 per mil salinity in the crabs chronically exposed to cadmium, as indicated by decreases of oxygen consumption and PCO2, an increase of PO2, along with no changes in lactate levels. These imbalances were associated with severe necrosis and telangiectasia in the respiratory gills, probably leading to respiratory impairment and finally histotoxic hypoxia and death of the animals.
Assuntos
Braquiúros/efeitos dos fármacos , Cádmio/farmacologia , Hemolinfa/efeitos dos fármacos , Homeostase/efeitos dos fármacos , Cloreto de Sódio/farmacologia , Animais , Braquiúros/fisiologia , Cádmio/toxicidade , Cálcio/sangue , Hemolinfa/química , Hemolinfa/metabolismo , Lactatos/sangue , Masculino , Consumo de Oxigênio/efeitos dos fármacos , Sódio/sangueRESUMO
Whole body oxygen consumption and some hemolymph parameters such as pH, partial pressure of gases, level of ions and lactate were measured in the estuarine crab Chasmagnathus granulata after both acute (96 h) and chronic (2 weeks) exposure to cadmium at concentrations ranging from 0.4 to 6.3 mg/l. In all instances, the crabs developed hemolymph acidosis, but no respiratory (increased PCO2) or lactate increases were evident. Hemolymph levels of sodium and calcium were always increased by cadmium exposure. The chronic toxicity of cadmium was enhanced at 12 0/00 salinity, even causing a significantly higher mortality in comparison with the higher salinity (30 0/00) used. A general metabolic arrest took place at 12 0/00 salinity in the crabs chronically exposed to cadmium, as indicated by decreases of oxygen consumption and PCO2, an increase of PO2, along with no changes in lactate levels. These imbalances were associated with severe necrosis and telangiectasia in the respiratory gills, probably leading to respiratory impairment and finally histotoxic hypoxia and death of the animals
Assuntos
Animais , Masculino , Braquiúros/fisiologia , Cádmio/farmacologia , Hemolinfa/efeitos dos fármacos , Homeostase/efeitos dos fármacos , Cloreto de Sódio/farmacologia , Braquiúros/efeitos dos fármacos , Cádmio/toxicidade , Cálcio/sangue , Cálcio/metabolismo , Hemolinfa/química , Hemolinfa/metabolismo , Lactatos/sangue , Lactatos/metabolismo , Consumo de Oxigênio/efeitos dos fármacos , Sódio/sangue , Sódio/metabolismoRESUMO
A polyclonal serum sample from a lepromatous leprosy (LL) patient, which presented a specific recognition pattern for leprosin, was used to screen a Mycobacterium leprae genomic library constructed with DNA isolated from human lepromas. One clone, designated ML4-1, which expressed a specific antigenic determinant of M. leprae as part of a beta-galactosidase fusion protein, was isolated. The 1.932 bp M. leprae-derived genomic fragment was sequenced, and it had an incomplete open-reading frame shown to code for a 644 amino-acid polypeptide (72.3 kDa). Some partial nucleotide homology to the M. tuberculosis MTCY9C4 cosmid and the M. leprae B1913 cosmid were found. Southern blot assays using the 584 bp Eco RI-Bam HI fragment excised from the ML4-1 clone revealed that this sequence is present only in the M. leprae genome and not in the 24 different mycobacterial DNA tested. Two oligonucleotides based on the genomic sequence were also synthesized and used as amplifiers for a polymerase chain reaction (PCR) test, giving a positive signal exclusively in M. leprae DNA. Furthermore, 32 sequential synthetic peptides, 20 amino-acids long, spanning the entire protein corresponding to the hypothetical ML4-1 clone sequence, were synthesized and evaluated by ELISA. A peptide included in the 221-240 region was significantly recognized by either lepromatous leprosy or healthy tuberculosis contact patient sera. Thus, PCR amplification of this fragment, along with the recognition of its protein sequence by leprosy patient sera, could be a useful tool for a potential diagnostic method in the detection of M. leprae infection in the future.