TY  - JOUR
A1  - Gershman, Ariel
A1  - Hauck, Quinn
A1  - Dick, Morag
A1  - Jamison, Jerrica M.
A1  - Tassia, Michael
A1  - Agirrezabala, Xabier
A1  - Muhammad, Saad
A1  - Ali, Raafay
A1  - Workman, 
Rachael E.
A1  - Valle, Mikel
A1  - Wong, G. William
A1  - Welch, Kenneth C.
A1  - Timp, Winston
T1  - Genomic insights into metabolic flux in hummingbirds
Y1  - 2023/05/01 
JF  - Genome Research 
JO  - Genome Research 
SP  - 703 
EP  - 714 
DO  - 10.1101/gr.276779.122 
VL  - 33 
IS  - 5 
UR  - http://genome.cshlp.org/content/33/5/703.abstract 
N2  - Hummingbirds are very well adapted to sustain efficient and rapid metabolic shifts. They oxidize ingested nectar to directly fuel flight when foraging but have to switch to oxidizing stored lipids derived from ingested sugars during the night or long-distance migratory flights. Understanding how this organism moderates energy turnover is hampered by a lack of information regarding how relevant enzymes differ in sequence, expression, and regulation. To explore these questions, we generated a chromosome-scale genome assembly of the ruby-throated hummingbird (A. colubris) using a combination of long- and short-read sequencing, scaffolding it using existing assemblies. We then used hybrid long- and short-read RNA sequencing of liver and muscle tissue in fasted and fed metabolic states for a comprehensive transcriptome assembly and annotation. Our genomic and transcriptomic data found positive selection of key metabolic genes in nectivorous avian species and deletion of critical genes (SLC2A4, GCK) involved in glucostasis in other vertebrates. We found expression of a fructose-specific version of SLC2A5 putatively in place of insulin-sensitive SLC2A5, with predicted protein models suggesting affinity for both fructose and glucose. Alternative isoforms may even act to sequester fructose to preclude limitations from transport in metabolism. Finally, we identified differentially expressed genes from fasted and fed hummingbirds, suggesting key pathways for the rapid metabolic switch hummingbirds undergo. 
ER  -