Satellite DNAs are tandemly repeated sequences clustered within heterochromatin.
However, in some cases such as the major TCAST1 satellite DNA from the beetle Tribolium
castaneum, they are found partially dispersed within euchromatin. Such organization together
with transcriptional activity enables TCAST1 to modulate the activity of neighbouring genes
and plays a role in heterochromatin remodelling during development and environmental stress
response. In order to explore if other T. castaneum repetitive families have features which
could provide them with a possible gene-modulatory role we analyse here transcription
activity of ten distinct TCAST families. Transcriptome sequencing (RNA-seq) was performed on
total RNA extracted from adult T. castaneum grown at 25°C as well as from adults subjected
to 24 h heat stress at 42°C, with 30 min and 1 h of recovery, respectively. For oocytes and
embryos we used publicly available dataset (SRA accession number: SRP050428). After
sequencing, adapters and low quality reads were removed and mapped using Bowtie2 to
dimers of repetitive families. Normalization method used was fragments per kb of transcript
per million mapped reads (FPKM) which we calculated manually. Results from RNA-seq were
confirmed by qPCR. Our study reveals that low copy TCAST repetitive families, partially
dispersed within euchromatin, are transcribed. Their transcriptional activity is increased after
heat stress and differs among stages of embryogenesis