Insights into the heterochromatin evolution in the genus Melipona (Apidae: Meliponini)

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Insectes Sociaux

RESEARCH ARTICLE

Insights into the heterochromatin evolution in the genus Melipona (Apidae: Meliponini) M. S. Cunha1   · L. A. O. Campos1 · D. M. Lopes1 Received: 30 March 2020 / Revised: 5 June 2020 / Accepted: 18 June 2020 © International Union for the Study of Social Insects (IUSSI) 2020

Abstract The species of the four Melipona subgenera can be subdivided into two cytogenetic groups: species belonging to Group I are characterized by having low heterochromatin content in their karyotypes ( 50%). To study the patterns of heterochromatin accumulation in this genus, we isolated moderate to highly repetitive sequences in M. (Michmelia) mondury (Mmon probe) and M. (Melikerria) fasciculata (Mfas probe) obtained based on the renaturation kinetics of C0t − 1 DNA and used these fragments as probes to hybridize in thirteen species belonging to the four Melipona subgenera. The Mmon probe marked all chromosomes in all Michmelia species and additionally the secondary constriction of M. (Eomelipona) puncticollis. The Mfas probe showed positive markings only within Melikerria. These results indicate the independence of the heterochromatin growth between Michmelia and Melikerria. Absence of markings in the regular set of chromosomes in M. (Melikerria) quinquefasciata and positive markings in the Bs, with the Mfas probe, suggests an interspecific origin of these chromosomes. We also hypothesize about the possible scenario that led to the heterochromatin growth in the genus Melipona. Keywords  C0t − 1 · Chromosomal evolution · Hymenoptera · Molecular cytogenetics · Repetitive sequences · Stingless bees

Introduction After being considered as “junk DNA” for decades, the heterochromatin has gained proper attention for its structural role in the organization of the genome, and for its functional role in various essential biological processes for the functioning of the organism (reviewed in Grewal and Jia 2007; Díaz-Castillo 2017). This portion of the genome is composed by different classes of repetitive DNA, such as satellite DNAs and mobile elements (transposons and retrotransposons) (Moran and Morrish 2005). These sequences are known for their binding sites for several structural proteins, the production of regulatory non-coding RNAs, as well as * M. S. Cunha [email protected] * D. M. Lopes [email protected] 1



Laboratório de Biologia Molecular de Insetos, Departamento de Biologia Geral, Universidade Federal de Viçosa, Campus Viçosa, Av. P.H. Rolfs s/n, CEP 36570‑900 Viçosa, Minas Gerais, Brazil

for their direct participation in the regulation of gene expression (Ugarkovic 2005; Muotri et al. 2007; Palomeque and Lorite 2008; Ferree and Prasad 2012; Lower et al. 2018). The C0t − 1 is a technique used to evidence fragments of repetitive DNA ranging from 50 to 500 bp (Alves-Silva et al. 2017). These moderate to highly repetitive sequences usually characterize the heterochromatin portion of the chromosomes and have been used to study heterochromatin composition and its evolution in some insect spe