RESUMO
Mariner-like elements (MLE) are members from class II of transposable elements also known as DNA transposons. These elements have a wide distribution among different groups of organisms, including insects, which can be explained by horizontal and vertical gene-transfer. MLE families have been described in tephritid flies and other genera. During screening for Wolbachia bacteria in fruit flies of the genus Anastrepha, we discovered two sequences related to mariner-like elements. Based on these sequences, we designed primers that allowed us to isolate and characterize two new mariner-like elements (Anmar1 and Anmar2) in Anastrepha flies. These elements, which belong to the mellifera and rosa subfamilies have a low nucleotide diversity, and are probably inactive and acquired by vertical transfer. This is the first report of mariner-like transposons in flies found in South America.
Assuntos
Proteínas de Ligação a DNA/genética , Tephritidae/classificação , Tephritidae/genética , Transposases/genética , Animais , FilogeniaRESUMO
This paper reports a comparative analysis of heterochromatin organization in the sex chromosomes of the fruit fly Anastrepha. Mitotic chromosomes of eight Anastrepha species from different taxonomic groups were stained with DAPI and chromomycin A3 fluorochromes followed by C-banding. A specific sex-chromosome banding pattern was obtained for each of the analyzed species. Fluorescence in situ hybridization (FISH) was performed to investigate the chromosomal location of rDNA loci. In all cases the rDNA sequences were found to localize exclusively to the sex chromosomes. The results further extend the chromosomal knowledge of Anastrepha and allow a precise species identification.
Assuntos
Mapeamento Cromossômico , DNA Ribossômico/genética , Cromossomos Sexuais , Tephritidae/genética , Animais , Corantes , DNA Ribossômico/análise , Feminino , Hibridização In Situ , Cariotipagem , Larva , Masculino , Tephritidae/citologia , Tephritidae/crescimento & desenvolvimentoRESUMO
O presente trabalho descreve 19 faixas heterozigotas (ou assimétricas) que ocorrem nos cromossomos politênicos de Sciara ocellaris, sendo 11 no cromossomo A, três no cromossomo B, quatro no cromossomo C e uma no cromossomo X. A assimetria das faixas pode ser agrupada em três classes: (1) uma faixa grossa; (2) uma faixa fina oposta à duas faixas grossas e (3) uma faixa grossa em um cromossomo sem que haja correspondente no cromossomo homólogo. O polimorfismo para as faixas é muito extenso. Na presente amostra, as 368 larvas, provenientes de uma populaçäo mantida em caixa no laboratório, eram heterozigotas, em média, para 4,95 ñ 0,10 das 15 faixas analisadas. Estudo da assimetria das faixas de larvas em estágios que antecedem e que säo posteriores à amplificaçäo do DNA na glândula salivar, mostrou que a assimetria näo é devida à amplificaçäo diferencial de DNA em cromômeros homólogos. A origem dessas aberraçöes ainda é uma incognita. Deficiências parciais ou duplicaçöes devem, portanto, ser as causas de sua formaçäo
Assuntos
Animais , Bandeamento Cromossômico , Cromossomos/citologia , DNA , Heterozigoto , Insetos , Polimorfismo Genético , Glândulas SalivaresRESUMO
The pattern anomaly double abdomen was induced in embryos of Bradysia tritici (syn. Sciara ocellaris) by irradiation of the anterior egg pole with far UV (254 or 285 nm) using low UV fluences. The maximum yield of 18% of double abdomens was obtained when 2.5 h embryos were irradiated (late intravitelline cleavage stage); earlier irradiation failed to yield double abdomens, as did irradiations after the early syncytial blastoderm stage. Exposing irradiated embryos to photoreverting light (366 nm) reduced the yield of malformations. Most double abdomens were symmetrical and the number of segments ranged from 3 to 8 in each set, with the mean value at 6.4 segments.