Histone epigenetic marks in heterochromatin and euchromatin of the Chagas’ disease vector, Triatoma infestans

Epigenetic studies in insects and the valproic acid perspective

“…Differential identification of acetylated H3K9, H4K8 and H4K16 and mono-, di-and trimethylated H3K9 (H3K9me/ me2/me3) between euchromatin and heterochromatin has been reported in the hemipteran species Triatoma infestans and Panstrongylus megistus, vectors of Chagas disease, and are consistent with the transcriptionally active and relatively inert status, respectively, of these chromatin compartments (Alvarenga et al, 2016(Alvarenga et al, , 2018. More details on histone acetylation, histone methylation, and histone phosphorylation in insects have been recently revised by Villagra and Frías-Lasserre (2020).…”

Spatial Distribution of Heterochromatin Bodies in the Nuclei of Triatoma infestans (Klug)

“…Considering that there is variability in proximal and distal distances between the chromocenters and the nuclear edge in the studied developmental phases and the adult stage of the Malpighian tubules of T. infestans, it is hypothesized that the chromocenters may exhibit movement within the cell nuclei. This phenomenon might occur due to the physical pressure exerted by the euchromatin mass and/or the variability in the HP1-α content or nucleolar masses that have been reported to occur associated with these heterochromatic bodies (Mello et al, 1990; Alvarenga et al, 2016). Clearly, to demonstrate that chromocenter motions occur within the nuclei, in vivo observations monitored by microcinematography may be relevant.…”

“…Although the euchromatin in the Malpighian tubules of T. infestans exhibits acetylation of lysine 9 in histone H3 (H3K9ac) and lysine 8 and 16 in histone H4 (H4K8ac and H4K16ac), as well as mono- and dimethylation of lysine 9 in histone H3 (H3K9me and H3K9me 2 ) and lysine 20 in histone H4 (H4K20me and H4K20me 2 ), these epigenetic marks have not been encountered in chromocenters (Alvarenga et al, 2016). However, the H3K9ac, H4K8ac, and H3K9me marks were shown to be concentrated around the chromocenter in single-chromocentered nuclei (Alvarenga et al, 2016).…”

“…Although the euchromatin in the Malpighian tubules of T. infestans exhibits acetylation of lysine 9 in histone H3 (H3K9ac) and lysine 8 and 16 in histone H4 (H4K8ac and H4K16ac), as well as mono- and dimethylation of lysine 9 in histone H3 (H3K9me and H3K9me 2 ) and lysine 20 in histone H4 (H4K20me and H4K20me 2 ), these epigenetic marks have not been encountered in chromocenters (Alvarenga et al, 2016). However, the H3K9ac, H4K8ac, and H3K9me marks were shown to be concentrated around the chromocenter in single-chromocentered nuclei (Alvarenga et al, 2016). This report leads to the hypothesis that in the chromocenter periphery or in the euchromatin in close contact with the chromocenter, transcriptional activity may occur, as several authors have described the enrichment in these marks in the promoters of active genes (Sterner & Berger, 2000; Talasz et al, 2005; Wu et al, 2005; Bártova et al, 2008).…”

“…Following treatment with the Schiff reagent, the preparations were rinsed in three baths of sulfurous water (5 min each), rinsed in distilled water, air-dried, cleared in xylene for 10 min, and mounted in VECTASHIELD® (Vector Laboratories, Burlingame, CA, USA). Malpighian tubules were used as the study organ because of their well-known cell biology, cytogenetics, fine structure, and physiological and epigenetic characteristics (Mello, 1971, 1989; Mello & Dolder, 1977; Wigglesworth, 1984; Mello et al, 1995, 2001; Campos et al, 2002; Alvarenga et al, 2011, 2016).…”