Characterization and evolutionary relevance of the sperm nuclear basic proteins from stickleback fish

Area of Science:

• Evolutionary Biology
• Molecular Biology
• Genomics

Background:

• Sperm nuclear basic proteins (SNBPs), specifically protamines, play a crucial role in sperm chromatin condensation.
• Sticklebacks (suborder Gasterosteoidei) offer a valuable model system for studying evolutionary processes due to their diverse habitats and speciation events.

Purpose of the Study:

• To characterize the amino acid sequences of protamines in various stickleback species.
• To evaluate the utility of protamine sequences as molecular markers for phylogenetic analysis and speciation studies.
• To investigate the evolutionary origins and diversification of protamines within the Gasterosteoidei suborder.

Main Methods:

• Amino acid sequencing of protamines from multiple stickleback species, including Aulorhynchus flavidus, Pungitius pungitius, Gasterosteus aculeatus, and G. wheatlandi.
• Phylogenetic analysis using bootstrap parsimony on protamine sequences.
• Comparative sequence analysis to infer evolutionary relationships and identify molecular changes.

Main Results:

• Protomine sequences are effective molecular markers at the generic level, yielding phylogenetic relationships consistent with morphological and behavioral analyses for Gasterosteoidei.
• Protomine evolution in Gasterosteoidei likely involved the extension of a common ancestral gene in early Acanthopterygii.
• Protomines are not ideal markers for recent freshwater isolates of G. aculeatus, except for a novel protamine component unique to benthic forms in Enos Lake, indicating recent speciation.

Conclusions:

• Protomine sequences provide robust phylogenetic insights at the generic level within Gasterosteus.
• The evolution of protamines reflects broader evolutionary patterns in Acanthopterygii.
• The discovery of a unique protamine in Enos Lake benthic sticklebacks highlights its role in recent adaptive radiation and speciation.