Isolation of prolactin gene and its differential expression during metamorphosis involving eye migration of Japanese flounder Paralichthys olivaceus

Decoding the fish genome opens a new era in important trait research and molecular breeding in China

Aquaculture represents the fastest-growing global food production sector, as it has become an essential component of the global food supply. China has the world's largest aquaculture industry in terms of production volume. However, the sustainable development of fish culture is hindered by several concerns, including germplasm degradation and disease outbreaks. The practice of genomic breeding, which relies heavily on genome information and genotypephenotype relationships, has significant potential for increasing the efficiency of aquaculture production. In 2014, the completion of the genome sequencing and annotation of the Chinese tongue sole signified the beginning of the fish genomics era in China. Since then, domestic researchers have made dramatic progress in functional genomic studies. To date, the genomes of more than 60 species of fish in China have been assembled and annotated. Based on these reference genomes, evolutionary, comparative, and functional genomic studies have revolutionized our understanding of a wide range of biologically and economically important traits of fishes, including growth and development, sex determination, disease resistance, metamorphosis, and pigmentation. Furthermore, genomic tools and breeding techniques such as SNP arrays, genomic selection, and genome editing have greatly accelerated genetic improvement through the incorporation of functional genomic information into breeding activities. This review aims to summarize the current status, advances, and perspectives of the genome resources, genomic study of important traits, and genomic breeding techniques of fish in China. The review will provide aquaculture researchers, fish breeders, and farmers with updated information concerning fish genomic research and breeding technology. The summary will help to promote the genetic improvement of production traits and thus will support the sustainable development of fish aquaculture.

Prolactin Expression in the Baboon (Papio hamadryas) Eye

Prolactin (PRL) is a hormone expressed in lactotrophs cells of the pituitary gland in primates. Extra pituitary expression of PRL has been reported, including the eye; however, expression in the developing eye of primates is limited. The aim of the study was determining the expression of PRL and PRL receptor (PRLR) (mRNAs and proteins) in adult and fetal baboon (Papio hamadryas) ocular tissues.

METHODS

We analyzed PRL and PRLR in baboon eyes tissues by immunofluorescence. The mRNAs of PRL and PRLR were detected by RT-PCR, cDNA was cloned, and sequenced. Furthermore, we performed a phylogenetic analysis to identify the evolutionary forces that underlie the divergence of PRL and PRLR primate genes.

RESULTS

We observed the expression of PRL and PRLR (mRNAs and proteins) in all retinal cell lineages of fetal and adult baboon. PRL and PRLR fit the hypothesis of evolutionary purifying gene selection.

CONCLUSIONS

mRNA and protein of PRL and PRLR are expressed in fetal and adult baboon retinal tissue. PRL may trigger autocrine and paracrine-specific actions in retinal cell lines.

The role of autophagy on eye migration during the metamorphosis of Paralichthys olivaceus

The metamorphosis of flatfish is unique, especially its eye migration. Autophagy has been found to be involved in a variety of organisms' metamorphosis. In order to explore the relationship between autophagy and flatfish metamorphosis, we investigated the expression of autophagy marker gene lc3b during the metamorphosis using real-time quantitative polymerase chain reaction and in situ RNA hybridization. Besides, we inhibited cell division, which was reported as the force source of eye migration, and autophagy around the mobile eye by microinjecting the inhibitors to explore the effects on autophagy expression and eye migration. We found that autophagy taking place during the metamorphosis, particularly in the areas around the eyes. In addition, the eye migration could be blocked by inhibiting the autophagy in the supraorbital area of the blind side, and after we blocked the eye migration by inhibiting cell proliferation in the infraorbital area of the blind side, the autophagy around the eye was partially inhibited. These findings indicate that the autophagy around the eyes caused by eye migration. Moreover, the cell death caused by autophagy loosen the orbital tissue to create space for the eye migration.