title: Metabolic rate and rates of protein turnover in food-deprived cuttlefish, Sepia officinalis (Linnaeus 1758).
abstract: To determine the metabolic response to food deprivation, cuttlefish (Sepia officinalis) juveniles were either fed, fasted (3 to 5 days food deprivation), or starved (12 days food deprivation). Fasting resulted in a decrease in triglyceride levels in the digestive gland, and after 12 days, these lipid reserves were essentially depleted. Oxygen consumption was decreased to 53% and NH4 excretion to 36% of the fed group following 3-5 days of food deprivation. Oxygen consumption remained low in the starved group, but NH4 excretion returned to the level recorded for fed animals during starvation. The fractional rate of protein synthesis of fasting animals decreased to 25% in both mantle and gill compared with fed animals and remained low in the mantle with the onset of starvation. In gill, however, protein synthesis rate increased to a level that was 45% of the fed group during starvation. In mantle, starvation led to an increase in cathepsin A-, B-, H-, and L-like enzyme activity and a 2.3-fold increase in polyubiquitin mRNA that suggested an increase in ubiquitin-proteasome activity. In gill, there was a transient increase in the polyubiquitin transcript levels in the transition from fed through fasted to the starved state and cathepsin A-, B-, H-, and L-like activity was lower in starved compared with fed animals. The response in gill appears more complex, as they better maintain rates of protein synthesis and show no evidence of enhanced protein breakdown through recognized catabolic processes.
authors.affiliation: Department of Biology, Université de Moncton, Moncton, New Brunswick, Canada; simon.lamarre@umoncton.ca.
authors.forename: Simon G
authors.initials: SG
authors.lastname: Lamarre
authors.affiliation: Department of Chemistry and Biochemistry, Mount Allison University, Sackville, New Brunswick, Canada;
authors.forename: Tyson J
authors.initials: TJ
authors.lastname: MacCormack
authors.affiliation: Centro de Ciências do Mar do Algarve, Campus de Gambelas, Universidade do Algarve, Faro, Portugal;
authors.forename: Antonio V
authors.initials: AV
authors.lastname: Sykes
authors.affiliation: Aquatic Research Cluster, Core Research Equipment and Instrument Training Network, Ocean Sciences Centre, Memorial University of Newfoundland, St. John's, Newfoundland, Canada; and.
authors.forename: Jennifer R
authors.initials: JR
authors.lastname: Hall
authors.affiliation: Department of Ocean Sciences, Memorial University of Newfoundland, St. John's, Newfoundland, Canada.
authors.forename: Ben
authors.initials: B
authors.lastname: Speers-Roesch
authors.affiliation: Department of Chemistry and Biochemistry, Mount Allison University, Sackville, New Brunswick, Canada;
authors.forename: Neal I
authors.initials: NI
authors.lastname: Callaghan
authors.affiliation: Department of Ocean Sciences, Memorial University of Newfoundland, St. John's, Newfoundland, Canada.
authors.forename: William R
authors.initials: WR
authors.lastname: Driedzic
mesh_terms: D000818:Animals; D049832:Decapodiformes / Q000378:metabolism*; D004734:Energy Metabolism; D005508:Food Deprivation; D005880:Gills / Q000378:metabolism*; D008657:Metabolic Clearance Rate; D009928:Organ Specificity; D010101:Oxygen Consumption; D014176:Protein Biosynthesis; D013217:Starvation / Q000378:metabolism*
keywords: NH4 production; ammonia quotient; cathepsin; digestive gland; polyubiquitin; proteasome; triglyceride