Pictured is an optical section of planarian testes, showing mRNAs expressed at different stages of spermatogenesis, including early spermatogonia (magenta) and spermatocytes (yellow-to-red). DNA staining (cyan) highlights changes in testis cell nuclei throughout spermatogenesis. Melanie Issigonis et al. found that the enzyme AADC in reproductive niche cells helps the enzyme NRPS produce the dipeptide β-alanyl-tryptamine (BATT). Inhibition of the gene for either enzyme in planarians led to the loss of female reproductive organs and accumulation of spermatogonial stem cells in testes. The defects were reversed by administering synthetic BATT. According to the authors, monoamine-derived compounds, such as BATT, can trigger development in reproductive niche cells. Credit: Melanie Issigonis, Katherine Browder, and Phillip Newmark, Morgridge Institute for Research
Researchers have discovered a new role for biogenic monoamines, such as 
Melanie Issigonis, Research Investigator, Morgridge Institute for Research. Credit: Morgridge Institute for Research
This surprising discovery began in a separate study published in 2022 by former graduate student Umair Khan and Morgridge Investigator Phil Newmark, also an investigator with the Howard Hughes Medical Institute. They set out to characterize the transcriptomes of the ovaries and testes in planarians (which are hermaphrodites) and generated a long list of genes with enriched expression in ovaries. One of the top hits came back as aromatic L-amino DOI: 10.1073/pnas.2321349121
This research was supported by the Eunice Kennedy Shriver National Institute of Child Health & Human Development of the
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