Preliminary Studies On Genetic Diversity And Melanin Biosynthesis In Gobiopterus Lacustris

Gobiopterus lacustris is a small benthic fish with warm water and brackish water.It is mainly distributed in the mangrove forest area of Leizhou peninsula and the dominant species in this area and also a new record species in China.On the basis of previous molecular marker recognition,the morphological indices of female and male samples of G.lacustris were systematically observed and their morphological characteristics were identified.The mangrove forest,as a marine ecological buffer zone,absorbs a large amount of land source and marine pollution and poses a threat to marine organisms in this area.Therefore,the population genetic diversity and genetic differentiation of G.lacustris are studied,reveal its life background and adaptability to changes in the external environment.According to the special morphological characteristics of G.lacustris skin translucency,the mechanism of melanin synthesis and regulation in skin was analyzed,and exposure to treatment was carried out with nonylphenol,the effects of environmental endocrine disruptors on the synthesis and regulation of the skin melanin of G.lacustris were investigated.At the same time,we hoped to screen the biomarkers of environmental endocrine disruptors.The main results are as follows:1.Taking pictures using the OLYMPUS SZX7 stereoscopic microscope,and then measuring with cell Sens standard software.The color of this species being semi-translucent,colorless or light yellow was similar to Gobiopterus macrolepis.There were differences from this species in a number of ways.From the starting point of the second dorsal and anal fins of the scale protrudes forward was in “<” shape(vs.from the first dorsal to the genital papilla was neat,forward was in “\” shape);male having 9 pairs of canines in the upper jaw and 8 pairs of smaller canine-like teeth in the hind part of the lower jaw(vs.male having 11 pairs of canines in the upper jaw and 9 pairs of smaller canine-like teeth in the hind part of the lower jaw);longitudinal scale series 19~21(vs.17~19);transverse scale series 5(vs.5~6);pectoral fin rays 12~13(vs.14);the main caudal fin13(vs.14);there were spots on the fins(vs.without spots).The morphological parameters of G.lacustris distributed in Leizhou Peninsula indicate that it is a new record in China.2.The genetic diversity and genetic structure of G.lacustris were analyzed by microsatellite markers.This study showed that 11 microsatellite loci were polymorphic with different degrees of polymorphism,the number of alleles was 2~15,the average number of alleles was 6.455.Therefore,it was considered to be used in the analysis of population genetic diversity in this study.The 11 microsatellite loci were used to analyze the genetic diversity of four populations distributing in DH,JLS,FC and GQ.The average number of effective alleles of the four G.lacustris populations was in ranging of 1.919~2.485.The observed heterozygosity and expected heterozygosity distributed 0.343~0.465 and 0.381~0.483,respectively.The average polymorphic information content(PIC)ranged from0.348~0.465.Chi-square tests showed that most loci in the 4 G.lacustris groups did not deviated from Hardy-Weinberg equilibrium.The genetic differentiation of the 4 populations reached above average level(0.107~0.216).Molecular variance analysis(AMOVA)revealed that genetic variation was mainly derived from the population.3.Through the transcriptional data of G.lacustris transparent and black skin,it is found that the mc1 r gene in the melanin synthesis pathway is not expressed,thus causing melanin synthesis to be blocked and lack of melanin in the skin for Gobiopterus.However,there are some black spots on the head and abdomen of G.lacustris,especially when the sex is mature,the markings on the abdomen are more obvious.This may be a small amount of melanin produced by the Wnt signaling pathway and MAPK signaling pathway in the melanin synthesis pathway,or by the synthesis of a small amount of melanin from the DAG-IP3 path,and then regulated by factors such as hormones,nutrients or external environment.4.After exposure to nonylphenol in G.lacustris,the relative expression of camk,er? and er? gene was detected by Quantitative Real-time PCR.The results showed that the expression of camk,er? and er? gene were significantly up-regulated,which was promoted the synthesis of melanin,but was harmful to the reproductive and endocrine system in the body.Compared to er? and er?,camk is more sensitive to nonylphenol.Therefore,camk gene is more suitable as a biomarker for endocrine disrupting substances in G.lacustris.In addition,we hope to make use of the characteristics of camk gene and melanin synthesis,and directly characterize the pollution status of endocrine disruptors through characterization.