The First FISH-Confirmed Non-Canonical Telomeric Motif in Heteroptera: Cimex lectularius Linnaeus, 1758 and C. hemipterus (Fabricius, 1803) (Hemiptera, Cimicidae) Have a 10 bp Motif (TTAGGGATGG) n

Abstract

Fluorescence in situ hybridization (FISH) with two different probes, the canonical insect telomeric sequence (TTAGG)_n and the sequence (TTAGGGATGG)_n, was performed on meiotic chromosomes of two members of the true bug family Cimicidae (Cimicomorpha), the common bed bug Cimex lectularius Linnaeus, 1758 and the tropical bed bug C. hemipterus (Fabricius, 1803), whose telomeric motifs were not known. In both species, there were no hybridization signals with the first probe, but strong signals at chromosomal ends were observed with the second probe, indicating the presence of a telomeric motif (TTAGGGATGG)_n. This study represents the first FISH confirmation of the presence of a non-canonical telomeric motif not only for the infraorder Cimicomorpha but also for the suborder Heteroptera (Hemiptera) as a whole. The present finding is of key significance for unraveling the evolutionary shifts in the telomeric sequences in this suborder.

Keywords: Heteroptera; bed bugs; chromosomes; fluorescence in situ hybridization; telomeres.

Figure 1

Male metaphase I plates after FISH with (TTAGGGATGG)_n probe: (a–c)—C. lectularius, n = 13 + X₁X₂Y (2n = 26 + X₁X₂Y); (d–f)—C. hemipterus, n = 14 + X₁X₂Y (2n = 28 + X₁X₂Y).

Figure 2

Telomeric repeats found by FISH or predicted from whole-genome data in various families of Cimicomorpha, Pentatomomorpha, and (as an outgroup) Nepomorpha, mapped on the true bug phylogeny (after Weirauch et al. [43]).