Seahorse Brood Pouch Transcriptome Reveals Common Genes Associated with Vertebrate Pregnancy.
Viviparity (live birth) has evolved more than 150 times in vertebrates, and represents an excellent model system for studying the evolution of complex traits. There are at least 23 independent origins of viviparity in fishes, with syngnathid fishes (seahorses and pipefish) unique in exhibiting male pregnancy. Male seahorses and pipefish have evolved specialized brooding pouches that provide protection, gas exchange, osmoregulation, and limited nutrient provisioning to developing embryos. Pouch structures differ widely across the Syngnathidae, offering an ideal opportunity to study the evolution of reproductive complexity. However, the physiological and genetic changes facilitating male pregnancy are largely unknown. We used transcriptome profiling to examine pouch gene expression at successive gestational stages in a syngnathid with the most complex brood pouch morphology, the seahorse Hippocampus abdominalis. Using a unique time-calibrated RNA-seq data set including brood pouch at key stages of embryonic development, we identified transcriptional changes associated with brood pouch remodeling, nutrient and waste transport, gas exchange, osmoregulation, and immunological protection of developing embryos at conception, development and parturition. Key seahorse transcripts share homology with genes of reproductive function in pregnant mammals, reptiles, and other live-bearing fish, suggesting a common toolkit of genes regulating pregnancy in divergent evolutionary lineages.
Institute of Evolutionary Biology and Environmental Studies, University of Zurich, Zurich, Switzerland School of Biological Sciences, The University of Sydney, Sydney, NSW, Australia camilla.whittington@sydney.edu.au twilson@brooklyn.cuny.edu.
Camilla M
CM
Whittington
Institute of Evolutionary Biology and Environmental Studies, University of Zurich, Zurich, Switzerland.
Oliver W
OW
Griffith
Functional Genomics Centre, University of Zurich, Zurich, Switzerland.
Weihong
W
Qi
Institute of Evolutionary Biology and Environmental Studies, University of Zurich, Zurich, Switzerland.
Michael B
MB
Thompson
School of Biological Sciences, The University of Sydney, Sydney, NSW, Australia Department of Biology, Brooklyn College The Graduate Center, City University of New York camilla.whittington@sydney.edu.au twilson@brooklyn.cuny.edu.
Anthony B
AB
Wilson
D000818:Animals; D005075:Biological Evolution; D005260:Female; D005306:Fertilization; D020869:Gene Expression Profiling; D008297:Male; D012098:Reproduction / Q000235:genetics*; D017423:Sequence Analysis, RNA; D012726:Sexual Behavior, Animal; D023701:Smegmamorpha / Q000235:genetics*; D052286:Viviparity, Nonmammalian / Q000235:genetics*
Hippocampus abdominalis; RNA-seq; Syngnathidae; brood pouch; evolution; gestation; live birth; male pregnancy; reproduction