Possible roles of two enzymes in releasing reproductive hormones in Penaeus monodon based on their changing brain levels during egg development

Ten transcripts exhibited up-regulated expression in black tiger shrimp after suppression of gonad-inhibiting hormone.

• Gonad-stimulating factors synthesized in the brain and thoracic ganglia induce vitellogenin synthesis during ovarian maturation in crustaceans.
• A gonad-inhibiting hormone from the eyestalk negatively regulates this process.
• Five transcripts showed down-regulated expression in shrimp treated with GIH-specific dsRNA.
• Nucleotide sequence analysis revealed that the cloned thioredoxin cDNA is highly similar to thioredoxin found in other crustaceans.
• The thioredoxin gene and other up-regulated genes were expressed in the brain during the ovarian maturation cycle, with the highest levels detected in early-vitellogenic females.
• The study suggests a potential role for transglutaminase and thioredoxin in regulating the gonad-stimulating pathway in shrimp.

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