Single-Cell Peptide Profiling to Distinguish Stickleback Ecotypes with Divergent Breeding Behavior

Area of Science:

• Behavioral Ecology
• Neuroendocrinology
• Fish Biology

Background:

• Parenting behaviors vary widely across species, with notable differences observed between ecotypes of the three-spined stickleback fish (Gasterosteus aculeatus).
• The pituitary gland, a key regulator of the hypothalamic-pituitary-adrenal (HPA) and hypothalamic-pituitary-gonadal (HPG) axes, is a potential neurochemical source influencing these behaviors.

Purpose of the Study:

• To investigate the peptide differences in the pituitary gland between attentive (common ecotype) and deserting (white ecotype) male three-spined stickleback fish.
• To identify specific pituitary peptides that correlate with distinct paternal care strategies.

Main Methods:

• Utilized matrix-assisted laser desorption ionization mass spectrometry (MALDI-MS) for high-throughput single-cell peptide analysis.
• Performed peptide mass fingerprinting using an in silico peptide library for prohormone identification.
• Conducted differential analysis of peptide levels between the two ecotypes.

Main Results:

• Significant differences in POMC-derived peptides, MCH-derived peptides, and oxytocin were identified between the common and white ecotypes.
• The common ecotype, exhibiting higher paternal care, showed significantly higher oxytocin levels.
• These neurochemical distinctions were not discernible through Leiden clustering of cellular phenotypes.

Conclusions:

• Pituitary peptide profiles, particularly oxytocin, are significantly different between three-spined stickleback ecotypes with contrasting parenting behaviors.
• These findings suggest a neurochemical basis for the observed variation in paternal care.
• Further research is warranted to fully elucidate the role of these peptides in regulating stickleback parenting.