Male-specific protein (MSP): A new gene linked to sexual behavior and aggressiveness of tilapia males

Ziv Machnes, Ramy Avtalion, Andrey Shirak, David Trombka, Ron Wides, Marc Fellous, Jeremy Don

Research output: Contribution to journalArticlepeer-review

15 Scopus citations


MSP is a male-specific protein initially identified in the serum of sexually active Sarotherodon galilaeus males, and is shown herein to be present in the serum of sexually mature males, but not females, of three other tilapia species. Cloning of the MSP cDNA and analysis of its predicted amino-acid sequence revealed that it is an outlier lipocalin that contains a signal peptide in its N-terminal region. The abundance of highly homologous sequences found in fish and the monophyletic relationship to tetrapod Alpha-1-acid glycoprotein (AGP) places it as a clade XII lipocalin. MSP was shown to undergo major N-glycosylation, characteristic of many lipocalins. The expression pattern of MSP, as determined at both the RNA and protein levels, points to the liver, head kidney and testis as production tissues, and resembles a pattern typical of some hormones. We found that MSP is secreted in urine and seminal fluids, and is present in the skin mucus of socially dominant males. Moreover, we discovered a positive correlation between MSP levels in the serum and the dominance and aggressive behavior displayed by socially dominant males. Based on these data, we suggest that MSP is a novel male-specific lipocalin that may function in intra and inter-sex communication.

Original languageEnglish
Pages (from-to)442-449
Number of pages8
JournalHormones and Behavior
Issue number3
StatePublished - Aug 2008

Bibliographical note

Funding Information:
The authors would like to thank Mr. Eli Shemesh for his solid advice and assistance in cloning MSP. This research was funded in part by the Bar-Ilan University president stipend to Ziv Machnes. This study was performed by Ziv Machnes as part of his Ph.D. requirements in the Mina and Everard Goodman Faculty of Life Sciences at Bar-Ilan University, Israel.


  • Intra and inter-sex communication
  • Lipocalins
  • MSP
  • Sexual dominance and aggressiveness
  • Tilapia


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