Changes in brain gene expression during migration in the white-crowned sparrow.

Area of Science:

• Animal behavior
• Neurobiology
• Genomics

Background:

• White-crowned sparrows (Zonotrichia leucophrys gambelii) exhibit reduced sleep during migration.
• Despite sleep reduction, these birds display no neurobehavioral deficits.
• Understanding the molecular basis of this adaptation is crucial.

Purpose of the Study:

• To investigate gene expression changes in the sparrow telencephalon during migration.
• To compare gene expression during migration (M) with sleep restriction (SR) and normal wakefulness (W).
• To identify molecular mechanisms underlying adaptation to reduced sleep during migration.

Main Methods:

• Microarray analysis of gene expression in the telencephalon.
• Comparison of gene expression profiles across three conditions: migratory season (M), sleep restriction (SR), and normal wakefulness (W).
• Analysis of approximately 17,100 detected transcripts.

Main Results:

• A small percentage of transcripts (0.17%) showed altered expression during migration (M) compared to SR and W.
• A similar small percentage (0.11%) changed expression during sleep restriction (SR) compared to M and W.
• Upregulated transcripts during migration include GLUT1, PARL, and heat shock proteins (HSP70, HSP90, GRP78, BiP).

Conclusions:

• Migration in white-crowned sparrows is associated with molecular indicators of brain cellular stress.
• Enhanced energetic demands in the brain are suggested during the migratory period.
• These findings point to adaptive physiological adjustments in the brain to cope with migration-induced sleep loss.