The yellow mealworm Tenebrio molitor (Coleoptera) is a beetle species belonging to the family Tenebrionidae. It is a saprophagous organism that feeds in nature on organic waste, decaying wood, and leaf litter. As a consumer of diverse organic materials, T. molitor plays an important role in the decomposition of organic matter and the maintenance of ecosystems. In an economic context, this species is most commonly described as a pest that causes significant losses by attacking and damaging stored grain products.
Due to its high protein content and nutritional value, this organism is gaining increasing importance as a food supplement. The approval of various forms of yellow mealworm larvae as a novel food for human consumption has further increased interest in this species, making the expansion of knowledge about this organism both necessary and of broad societal relevance. The yellow mealworm has become an organism of interest in numerous studies across the fields of biology, biochemistry, evolution, immunology, and physiology. It has also been shown to possess particularly interesting traits, such as antifreeze proteins whose accumulation enables survival during the winter period. In addition, it has been included in several clinical trials, indicating its potential for diverse applied research related to this group of organisms. The yellow mealworm is easy to maintain under laboratory conditions, reproduces rapidly, and has a short life cycle, making it an ideal model organism for studying a wide range of biological processes.
The importance of studying this organism is also reflected in continuous efforts by the scientific community to improve the completeness of the T. molitor genome assembly. However, repetitive regions of the genome pose significant technical challenges for DNA sequencing and assembly. Although these regions are often omitted or underrepresented in assembled genomes, understanding repetitive sequences is essential for a comprehensive understanding of genome architecture and function. Repetitive sequences, sometimes referred to as the “dark matter” of the genome, are considered important builders of genome architecture and drivers of genome evolution, as processes that reorganize these sequences and alter their composition and copy number strongly influence genome evolution.
Satellite DNAs (satDNAs) are tandemly repeated sequences that are predominantly located in (peri)centromeric and subtelomeric heterochromatin, where they form long arrays composed of hundreds or thousands of monomers. However, satDNAs are also present in euchromatin, often near genes or within introns, in the form of single repeats or short arrays. SatDNAs contribute to genome evolution through the process of speciation and are important for maintaining genome stability within the nucleus. Moreover, there is increasing evidence for their active and tightly regulated transcription and for the roles of their transcripts in various biological processes, such as heterochromatin establishment and centromere function, regulation of gene expression in different biological contexts, stress responses, and environmental adaptations. Dysregulation of satDNA transcription has also been observed in carcinogenesis, and satDNA transcripts show potential as biomarkers.
A large portion of the T. molitor genome is composed of a single satDNA, which according to some estimates accounts for up to 50% of the genome. This satDNA has a monomer length of 142 bp, and its localization in the pericentromeric heterochromatin of all chromosomes has been confirmed by in situ restriction digestion of metaphase chromosomes using endonucleases with recognition sites within the satDNA monomer. Within the framework of the improved genome assembly of this species, we identified an additional 10 satDNAs; however, the localization, distribution patterns, and transcription of these sequences remain unknown.
The objectives of this project are to determine the genomic localization of 11 satDNAs in T. molitor using experimental and bioinformatic approaches; to identify and analyze related satDNAs in the genomes of other insect species; to analyze the transcription of the 11 T. molitor satDNAs using RNA-seq data from male and female individuals across all developmental stages; and to investigate the presence of T. molitor satDNAs in transcriptomic datasets of other species.
Through this approach, we aim to elucidate the transcriptional potential of satDNA sequences and relate it to the type and specific features of individual satDNAs, their genomic abundance, chromosomal localization, and the developmental stages of T. molitor. This will provide a foundation for explaining the impact and role of the “dark matter” of the genome in the functioning of this economically and ecologically important insect, as well as in other species in which these sequences occur.
Team members:
Dr.sc. Eva Šatović Vukšić
Dr.sc. Miroslav Plohl
Dr.sc. Đurđica Ugarković
Dr.sc. Antonio Sermek
mag. educ. biol. et chem. Patrik Majcen
Contact:
Eva Šatović Vukšić esatovic@irb.hr
https://www.irb.hr/Novosti/Nevidljive-poruke-prirode-Sto-nam-otkrivaju-med-dagnje-i-zuti-brasnar
https://www.linkedin.com/posts/ruder-boskovic-institute_secrets-of-the-genome-activity-7311311222396649472-GOsN?utm_source=share&utm_medium=member_desktop&rcm=ACoAAAEJhgoBo1biqBImFNmo6wHCv2rMMisrZmo
