Kisspeptin system in pejerrey fish (Odontesthes bonariensis). Characterization and gene expression pattern during early developmental stages

Abstract

In vertebrates, kisspeptins and their receptors are known to be related to puberty onset and gonadal maturation, however, there are few studies concerning their role in early development. Here, we characterize the kisspeptin system in the pejerrey, Odontesthes bonariensis, a fish with strong temperature-dependent sex determination. We reconstructed the phylogenetic history of the two ligands (kiss1 and kiss 2) and two receptors (kissr2 and kissr3) in pejerrey in the context of recent classifications of bony fishes, determined their tissue distribution and documented the early expression pattern of these ligands and receptors. Phylogenetic analysis of these gene families clearly resolved the percomorph clade and grouped pejerrey with Beloniformes. Paralogous sets of genes putatively arising from the teleost-specific genome duplication event (3R) were not detected. Kisspeptins and their receptors showed a wide tissue distribution in adult pejerrey, including tissues not related to reproduction. In larvae reared at 24°C, the four kisspeptin elements were expressed in the head from week 1 to week 8 of life, with no differences in transcript levels. Larvae kept at a female-producing temperature (17°C) did not show statistically significant differences in the transcript levels of all analyzed genes during the sex determination/differentiation period; however, in those larvae raised at male producing temperature (29°C), kiss2 levels were increased at week 4 after hatching. These results showed that all members of the kisspeptin system are expressed at this early period, and the increase of kiss2 transcripts at week 4 could be interpreted as it would be related to the differentiation of the brain-pituitary axis in male development.

Eel Kisspeptins: Identification, Functional Activity, and Inhibition on both Pituitary LH and GnRH Receptor Expression

“…In some species, both kisspeptins are detected in the gonads [medaka and zebrafish ( 42 , 53 ); sea bass ( 60 ); rohu ( 45 ); and Catla catla ( 46 , 47 )]. In contrast, in the chub mackerel, Kiss1 is expressed in the gonads of both sexes, while Kiss2 expression is not detected ( 44 ), whereas in the pejerrey, expression of both genes is very low in the gonads ( 48 ). We previously showed a strong expression of KissR-1 in both the ovary and testis of the European eel ( 19 ), which supports a potential endocrine action of Kiss1 and/or Kiss2 on European eel gonads.…”

“…In other teleosts presenting two Kiss genes, both Kiss1 and Kiss2 mRNAs are also expressed in the central nervous system [RT-PCR and qPCR, zebrafish ( 40 – 42 ); RT-PCR, goldfish ( 43 ); RT-PCR, sea bass ( Dicentrarchus labrax ), medaka ( Oryzias latipes ) ( 42 ); RT-PCR and qPCR, chub mackerel ( 44 ); qPCR, rohu, Labeo rohita ( 45 ); qPCR, Catla catla ( 46 , 47 ); qPCR, pejerrey, Odontesthes bonariensis ( 48 )], suggesting that kisspeptins exert important functions in the teleost brain. Anatomical studies, using ISH and laser-capture microdissection coupled with qPCR, have demonstrated that each transcript is located in different brain nuclei: Kiss1 mRNA is observed in the ventral habenula , while Kiss2 mRNA is found in the preoptic region and in the hypothalamus [for review see Ref.…”

“…In other teleost species possessing two kisspeptin genes, different observations have been reported. Only Kiss2 expression is detected in zebrafish ( 52 ) and pejerrey ( 48 ) pituitaries, while only Kiss1 is expressed in the chub mackerel pituitary ( 44 ). In the medaka, none of the two kisspeptin genes is expressed in the pituitary ( 53 ), while in the sea bass, both genes are expressed ( 54 ), as in the eel.…”

“…We previously showed the expression of KissR-1 in the eye, suggesting the potential involvement of the kisspeptin system in the local regulation of visual functions. Kiss1 and Kiss2 expression also occurs in the eye of other teleost species [zebrafish and medaka ( 42 ); rohu ( 45 ); and pejerrey ( 48 )]. Kisspeptin receptor mRNAs are also observed in the eye of zebrafish [ KissR-3 only ( 61 )] and pejerrey [ KissR-2 and KissR-3 ( 48 )].…”

Estudio de la perturbación del desarrollo sexual de Cnesterodon decemmaculatus (Pisces, Poeciliidae) por compuestos con actividad estrogénica

“…Sin embargo, a diferencia de lo documentado para mamíferos, los peces tienen dos genes Kiss (kiss1 y kiss2) debido a duplicaciones del genoma (Mechaly et al, 2013;Ohga et al, 2018). Sin embargo, a pesar de que los niveles de kisspeptina1 y 2 varían durante el ciclo sexual (Tovar Bohórquez et al, 2017), la relación entre kisspeptina y reproducción en peces no parece ser tan directa como en tetrápodos (Tang et al, 2015;Nakajo et al, 2018).…”