Fishing for mechanisms regulating senescence in sockeye salmon

Steven RobertsTom QuinnLeslie JensenCaroline Storer

photo: Foist

Salmon Senescence

• Rapid decline to death

• Alongside other complex physiological process

• Rates of senescence vary within population and across populations

• Arrival date to spawning ground correlates with rate of senescence (Hendry et al 2003)

• Bear predation plays a role in driving rates(Carlson et al 2007)

What physiological process regulate senescence?

Rationale

• Better understand how environmental change might effect senescence physiology

• Determine other traits that could be impacted by selective pressures

• Model system for studying aging in other taxa

Preliminary Investigations

Preliminary Investigations

Hansen Creek

Small tributary of Lake Aleknagik

Nearly uniform top to bottom: 4m wide & 10cm deep riffles

Annual spawning population of 3,000 – 20,000 sockeye

Stream life annually averages below 10 days (usually 7-14)

Carlson and Quinn 2007

Preliminary Investigations

Hansen Creek

Approach

• Sample fish (brain tissue)

• Select candidate genes

• Characterize gene expression patterns for select genes

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Preliminary Investigations

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HSP70

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Summary

• Baseline information on physiological changes between “arriving” and senescent salmon

• Cortisol signaling declines temporally

• Molecular chaperone protein (HSP) is upregulated at senescence

• Molecules controlling “other” primary physiological process are differentially expressed

• Receptor (NMDA) associated with aging and memory in other taxa declines in senescence

Future direction

• Compare expression in populations with different rates of senescence

• Characterize corresponding protein expression levels

• Take a non-biased approach to identify differences (NGS, Differential Display)

• Explore genetic (SNP) and epigenetic (DNA methylation pattern) differences