Unveiling the Role of Dynamic Alternative Splicing Modulation After Infestation with Sea Lice (Caligus rogercresseyi) in Atlantic Salmon.

Sea lice are pathogenic marine ectoparasite copepods that represent a severe risk to the worldwide salmon industry. Several transcriptomic investigations have characterized the regulation of gene expression response of Atlantic salmon to sea lice infestation. These studies have focused on the levels of transcript, overlooking the potentially relevant role of alternative splicing (AS), which corresponds to an essential control mechanism of gene expression through RNA processing. In the present study, we performed a genome-wide bioinformatics characterization of differential AS event dynamics in control and infested C. rogercresseyi Atlantic salmon and in resistant and susceptible phenotypes. We identified a significant rise of alternative splicing events and AS genes after infestation and 176 differential alternative splicing events (DASE) from 133 genes. In addition, a higher number of DASE and AS genes were observed among resistant and susceptible phenotypes. Functional annotation of AS genes shows several terms and pathways associated with behavior, RNA splicing, immune response, and RNA binding. Furthermore, three protein-coding genes were identified undergoing differential transcript usage events, among resistant and susceptible phenotypes. Our findings support AS performing a relevant regulatory role in the response of salmonids to sea lice infestation.

Modulation of the Proteostasis Machinery to Overcome Stress Caused by Diminished Levels of t6A-Modified tRNAs in Drosophila.

Transfer RNAs (tRNAs) harbor a subset of post-transcriptional modifications required for structural stability or decoding function. N6-threonylcarbamoyladenosine (t6A) is a universally conserved modification found at position 37 in tRNA that pair A-starting codons (ANN) and is required for proper translation initiation and to prevent frame shift during elongation. In its absence, the synthesis of aberrant proteins is likely, evidenced by the formation of protein aggregates. In this work, our aim was to study the relationship between t6A-modified tRNAs and protein synthesis homeostasis machinery using Drosophila melanogaster. We used the Gal4/UAS system to knockdown genes required for t6A synthesis in a tissue and time specific manner and in vivo reporters of unfolded protein response (UPR) activation. Our results suggest that t6A-modified tRNAs, synthetized by the threonyl-carbamoyl transferase complex (TCTC), are required for organismal growth and imaginal cell survival, and is most likely to support proper protein synthesis.