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

Abstract

Ladybird beetles (Coccinellidae) are one of the largest groups of beetles. Among them, some species are of economic interest since they can act as a biological control for some agricultural pests whereas other species are phytophagous and can damage crops. Chnootriba argus (Coccinellidae, Epilachnini) has large heterochromatic pericentromeric blocks on all chromosomes, including both sexual chromosomes. Classical digestion of total genomic DNA using restriction endonucleases failed to find the satellite DNA located on these heterochromatic regions. Cloning of C0t-1 DNA resulted in the isolation of a repetitive DNA with a repeat unit of six base pairs, TTAAAA. The amount of TTAAAA repeat in the C. argus genome was about 20%. Fluorescence in situ hybridization (FISH) analysis and digestion of chromosomes with the endonuclease Tru9I revealed that this repetitive DNA could be considered as the putative pericentromeric satellite DNA (satDNA) in this species. The presence of this satellite DNA was tested in other species of the tribe Epilachnini and it is also present in Epilachna paenulata. In both species, the TTAAAA repeat seems to be the main satellite DNA and it is located on the pericentromeric region on all chromosomes. The size of this satDNA, which has only six base pairs is unusual in Coleoptera satellite DNAs, where satDNAs usually have repeat units of a much larger size. Southern hybridization and FISH proved that this satDNA is conserved in some Epilachnini species but not in others. This result is in concordance with the controversial phylogenetic relationships among the genera of the tribe Epilachnini, where the limits between genera are unclear.

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

“…In the same species, but with the generation of a C0t-1 library, a satDNA family with an unusual short repeat unit with only 6 bp (TTAAAA) was isolated. This satDNA is also present in other Coccinellid species such as Epilachna paenulata but is not present in other species such as Henosepilachna vigintioctomaculata, Henosepilachna septima or Diekeana admirabilis [44].…”

“…In spite of their ecological and economic importance, the data about repetitive DNA in Coccinelids are scarce. The analysis of satDNA has only been carried out in one Coccinellid species, Chnootriba argus, using classical methods such as restriction enzyme digestion or C0t-1 library construction [43,44]. The use of restriction enzymes allowed the isolation of a subtelomeric satDNA family located on the subtelomeric regions in all the chromosomes with the exception of the long arm of the X chromosome [43].…”

Satellitome of the Red Palm Weevil, Rhynchophorus ferrugineus (Coleoptera: Curculionidae), the Most Diverse Among Insects

“…In Coleoptera, the use of classic methods such as restriction endonucleases digestions [revised in Palomeque and Lorite (2008)] or C0t-1 libraries generation (Mora et al, 2019) has allowed the identification of most of the satDNAs. Among beetles, the use of next-generation sequencing (NGS) data to study the satDNA has been so far limited to two species, the model species Tribolium castaneum (Tenebrionidae) and the ladybird Hippodamia variegata (Coccinellidae) (Pavlek et al, 2015;Mora et al, 2020).…”

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

“…Dot-blot hybridization was used to estimate the amount of the Hyscu-H satDNA in the H. scutellatus genome [ 59 , 60 ]. Inserts of the recombinant Hyscu-H-20 and Hyscu-H-21 plasmids were labeled with DIG as indicated above and used as a probe in the dot-blot hybridization.…”