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Adam J Dobson

Publications and source records attributed to Adam J Dobson.

2 recordsLinked to original sources

Lifespan extension by dietary restriction in Drosophila is associated with GATA motifs and organ-specific, TOR-dependent transcriptional networks.

Animal lifespan can be extended by dietary restriction (DR), but at a cost to fitness. This phenomenon depends on essential amino acids (EAAs) and TOR signalling, but roles of specific tissues and downstream transcriptional regulators are poorly characterised. Manipulating relevant transcription factors (TFs) specifically in lifespan-limiting tissues may ameliorate ageing without costs of DR. Here we identify TFs which regulate the DR phenotype in Drosophila, analysing organs as an interacting system and reducing its transcriptional complexity by two orders of magnitude. Evolutionarily conserved GATA TFs are predicted to regulate the overlapping effects of DR and TOR on organs, and genetic analyses confirmed that these TFs interact with diet to determine lifespan. Importantly, Srp knockdown insulated fly lifespan from the pernicious effects of EAAs, but tissue-specific knockdown reduced the corrolary costs. These results provide the first indication that benefits of EAAs for early-life fitness can be decoupled from longevity by tissue-specific transcriptional reprogramming.

Systems Biology

Genomic signatures of experimental adaptation to antimicrobial peptides in Staphylococcus aureus

ObjectivesThe evolution of resistance against antimicrobial peptides has long been considered unlikely due to their mechanism of action, yet experimental selection with AMPs results in rapid evolution of resistance in several species of bacteria. Although numerous studies have utilized mutant screens to identify loci that determine AMP susceptibility, there is a dearth of data concerning the genomic changes which accompany experimental evolution of AMP resistance.\n\nMethodsUsing genome re-sequencing we analysed the mutations which arise during experimental evolution of resistance to the cationic AMPs iseganan, melittin and pexiganan, as well as to a combination of melittin and pexiganan, or to the aminoglycoside antibiotic streptomycin.\n\nResultsAnalysis of 17 independently replicated Staphylococcus aureus selection lines, including unselected controls, showed that each AMP selected for mutations at distinct loci. We identify mutations in genes involved in the synthesis and maintenance of the cell envelope. This includes genes previously identified from mutant screens for AMP resistance, and genes involved in the response to AMPs and cell-wall-active antibiotics. Furthermore, transposon insertion mutants were used to verify that a number of the identified genes are directly involved in determining AMP susceptibility.\n\nConclusionsStrains selected for AMP resistance under controlled experimental evolution displayed consistent AMP-specific mutations in genes which determine AMP susceptibility. This suggests that different routes to evolve resistance are favored within a controlled genetic background.

Microbiology