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

Abstract

The Colorado potato beetle (Leptinotarsa decemlineata, family Chrysomelidae),a phytophagous insect, which feeds preferably on potatoes, constitutes a serious pest of this crop and causes extensive damage to tomatoes and egg plants. It has a remarkable ability to develop resistance quickly against insecticides and shows a diversified and flexible life history. Consequently, the control of this pest has become difficult, requiring the development of new alternative biotechnology-based strategies. Such strategies require a thorough knowledge of the beetle’s genome,including the repetitive DNA. Satellite DNA (stDNA), composed of long arrays of tandemly arranged repeat units, constitutes the major component of heterochromatin and is located mainly in centromeric and telomeric chromosomal regions. We have studied two different unrelated satellite-DNA families of which the consensus sequences were 295 and 109bp in length, named LEDE-I and LEDE-II, respectively.Both were AT-rich (70.8% and 71.6%, respectively). Predictive models of sequence-dependent DNA bending and the study of electrophoretic mobility on non-denaturing polyacrylamide gels have shown that the DNA was curved in both satellite-DNA families. Among other features, the chromosome localization of both stDNAs has been studied. In situ hybridization performed on meiotic and mitoticnuclei showed chromosomes, including the X chromosome, with zero, one, or two stDNAs. In recent years, it has been proposed that the repetitive DNA may play a key role in biological diversification processes. This is the first molecular and cytogenetic study conducted on L. decemlineata repetitive DNA and specifically on stDNA, which is one of the important constituents of eukaryotic genomes.

Satellitome Analysis in the Ladybird Beetle Hippodamia variegata (Coleoptera, Coccinellidae)

“…Sometimes, the satDNA is chromosome-, species-or genome-specific in many species and may cause a large variation between close species [13,14]. Normally, the satDNA is A+T rich, which is why the satDNA has been related to the curvature and the condensation of the chromatin [15].…”

Cytogenetic Analysis, Heterochromatin Characterization and Location of the rDNA Genes of Hycleus scutellatus (Coleoptera, Meloidae); A Species with an Unexpected High Number of rDNA Clusters

“…Six high potential curvature peaks were observed ( Figure 3 ); four of them had curvature propensities over 12 (around positions 130, 180, 320 and 355) and two had curvature propensities of approximately 9–9.5 (around positions 70 and 200). These magnitudes of curvature have been experimentally associated with a retarded DNA electrophoretic mobility in other insect satDNAs [ 81 , 86 ].…”

Isolation of a Pericentromeric Satellite DNA Family in Chnootriba argus (Henosepilachna argus) with an Unusual Short Repeat Unit (TTAAAA) for Beetles

“…In Coleoptera, the repeat units of the isolated satDNAs using conventional techniques are usually between these values [38], although, in some cases, the length is significantly higher, such as the 1.2 kb Pst I family of Misolampus goudoti [39] or the 1061-bp TBREV family of Tribolium brevicornis [40]. Among coleopteran species, the pericentromeric satDNA with the shorter repeat unit was the 109 bp LEDE-II family isolated in Leptinotarsa decemlineata [41]. Therefore, the TTAAAA satDNA isolated in C. argus was the pericentromeric satDNA with the shortest tandem repeat described to date in Coleoptera.…”