Genes in pieces and spliceosomal introns are a landmark of eukaryotes, with intron invasion usually assumed to have happened early
on in evolution. Here, we analyze the intron landscape of Micromonas, a unicellular green alga in the Mamiellophyceae lineage,
demonstratingthe coexistence of several classesof introns andtheoccurrence of recentmassive intron invasion. This study focuseson
twostrains,CCMP1545andRCC299,andtheir related individuals fromoceansamplings, showingthat they notonly harbordifferent
classes of introns depending on their location in the genome, as for other Mamiellophyceae, but also uniquely carry several classes of
repeat introns. These introns, dubbed introner elements (IEs), are found at novel positions in genes and have conserved sequences,
contrary to canonical introns. This IE invasion has a huge impact on the genome, doubling the number of introns in the CCMP1545
strain. We hypothesize that each IE class originated from a single ancestral IE that has been colonizing the genome after strain
divergence by inserting copies of itself into genes by intron transposition, likely involving reverse splicing. Along with similar cases
recently observed in other organisms, our observations in Micromonas strains shed anewlight on the evolution of introns, suggesting
that intron gain is more widespread than previously thought.
Phasha, Mmatshepho Malekgale; Wingfield, Brenda D.; Coetzee, Martin Petrus Albertus; Santana, Quentin C.; Fourie, Gerda; Steenkamp, Emma Theodora(Genetics Society of America, 2017-11)
Removal of introns from transcribed RNA represents a crucial step during the production of
mRNA in eukaryotes. Available whole-genome sequences and expressed sequence tags (ESTs) have
increased our knowledge of this ...
Phasha, Mmatshepho Malekgale(University of Pretoria, 2012-12-14)
The genus Fusarium constitutes fungi with diverse biological behaviours. This study focused on four plant pathogenic species. These were F. verticillioides which infects maize, F. oxysporum which infects tomato, F. ...
Familial Adult Myoclonic Epilepsy (FAME) is characterised by cortical myoclonic tremor
usually from the second decade of life and overt myoclonic or generalised tonic-clonic seizures.
Four independent loci have been ...