Molecular and cytological characterization of repetitive DNA sequences from the centromeric heterochromatin of Sciara coprophila

Abstract

Sciara coprophila (Diptera, Nematocera) constitutes a classic model to analyze unusual chromosome behavior such as the somatic elimination of paternal X chromosomes, the elimination of the whole paternal, plus non-disjunction of the maternal X chromosome at male meiosis. The molecular organization of the heterochromatin in S. coprophila is mostly unknown except for the ribosomal DNA located in the X chromosome pericentromeric heterochromatin. The characterization of the centromeric regions, thus, is an essential and required step for the establishment of S. coprophila as a model system to study fundamental mechanisms of chromosome segregation. To accomplish such a study, heterochromatic sections of the X chromosome centromeric region from salivary glands polytene chromosomes were microdissected and microcloned. Here, we report the identification and characterization of two tandem repeated DNA sequences from the pericentromeric region of the X chromosome, a pericentromeric RTE element and an AT-rich centromeric satellite. These sequences will be important tools for the cloning of S. coprophila centromeric heterochromatin using libraries of large genomic clones.

High contiguity de novo genome assembly and DNA modification analyses for the fungus fly, Sciara coprophila, using single-molecule sequencing

“…4 g). In addition, the “Sccr” ( Sciara centromere consensus sequence) repeat that hybridized to the centromeres of all Sciara chromosomes [ 23 ] mapped to 48–105 contigs (Table 2 , Fig. 4 g).…”

“…The longest X-linked contig was 9.68 Mb (12 Mb). The set of haploid X-linked contigs contained those identified as X-linked using X-specific sequences above as well as contigs containing the F7 repeat sequence known to be on X, IV, and L [ 23 ] (Table 2 , Fig. 4 g, Supplemental Fig.…”

Characterization of two unrelated satellite DNA families in the Colorado potato beetleLeptinotarsa decemlineata(Coleoptera, Chrysomelidae)

“…Generally, an inverse correlation between predicted curvature and G + C content was found. The AT richness and the presence of AT runs are a fundamental feature of DNA curvature (Lorite et al , 2004; Palomeque & Lorite, 2008; Escribá et al ., 2011). Recently, Matyasek et al (2011) have reported a clear correlation between the existence of short and periodically phased T 4–6 and stDNA curvature.…”

Sex-Determining Mechanisms in Insects Based on Imprinting and Elimination of Chromosomes

“…With respect to its molecular nature, the CE is located in the middle heterochromatic block of the pericentromeric region of the X chromosome of S. coprophila [Crouse, 1960a[Crouse, , b, 1977[Crouse, , 1979. Microdissection and microcloning of this region have already been performed [Escribá et al, 2011b] so that the molecular characterization of this region is now possible.…”

“…Recent molecular data challenged this contention. Escribá et al [2011b] microdissected and microcloned the pericentromeric region of the S. coprophila X chromosome, where the rDNA is located. They identified and characterized repeated DNA sequences, a RTE element and an AT-rich satellite, and as expected, rDNA clones were also recovered.…”