Expression and antimicrobial activity of liver-expressed antimicrobial peptides in the ovaries of the viviparous teleost Xenotoca eiseni

The mechanism via which the mothers of viviparous animals regulate the internal environment of pregnancy-associated organs for maintaining offspring growth is poorly understood. Environmental niches in organs contain fluid components for supporting embryonic growth; however, they may serve as nutrients for microbes. Therefore, microbial control is essential in viviparous animals to reduce the risk of infection in the ovarian lumen. Its importance may be higher than that in the case of oviparous animals. In this study, we investigated the antimicrobial factors in a viviparous teleost, Xenotoca eiseni. Four transcripts of the liver-expressed antimicrobial peptide (LEAP) were identified via RNA-Seq analysis. Some of the genes were expressed in the ovaries or intraovarian embryos of the fish. In particular, high expression of leap1a was detected in the ovaries of both pregnant and non-pregnant fish. Moreover, the ovary extracts from X. eiseni and transformed leap genes exhibited antimicrobial activity against Escherichia coli. Our results suggest that viviparous teleosts utilize antimicrobial peptides to reduce the risk of infection in the ovarian lumen.