Study On Muscle Growth And PI3K/AKt Pathway Of Golden Carp Cultured In Rice Field

Jinbei common carp（Cyprinus carpio var.Jinbei）has lived in rice fields over a long period of time through natural and artificial selection.On the basis of collecting,sorting out and excavating the distribution areas of Jinbei common carp in the rice field,this study further adopted histology,biochemistry and molecular biology methods,using juvenile and adult Jinbei common carp as experimental materials and pond cultured Jinbei common carp as control group.The objective was to study the characteristics of caudal stalk muscle fiber,metabolic enzyme activity and PI3K/AKt pathway related gene expression,and to find out the correlation characteristics of the muscle of caudal stalk of Jinbei common carp in rice field under shallow water ecological conditions.The specific results are as follows:1.Distribution and morphological characteristics of Jinbei common carpJinbei common carp is mainly distributed in rice fields in the border areas of Guizhou province,Hunan province and Guangxi province.In Guizhou province,it is mainly distributed in rice fields of Jinping County,Liping County,Congjiang County,Rongjiang County,Sansui County,Cengong County,Shibing County,Majiang County,Huangping County,Kaili County,Danzhai County,Leishan County,Duyun Town,Yuqing County,Tongren City.Congjiang County,Huangping County,Tongren City had the largest distribution quantity,while Tongren City had the least.The body color of Jinbei common carp showed yellow,black and red strains,indicating that the morphology of Jinbei common carp was different in the rice field environment in different regions.The pond-cultured Jinbei common carp was used as the control group to explore the morphological characteristics of paddy Jinbei common carp adapted to the caudal stalk of paddy field.Determination of weight,body length and caudal stalk height/length parameters of paddy Jinbei common carp,pond Jinbei common carp.The results showed that there was no significant difference in body weight and body length between the two groups（p>0.05）,and caudal stalk height/length was significantly higher than that of pond Jinbei common carp（p<0.05）.The results show that the caudal stalk of paddy Jinbei common carp has a large side area and a short and stout shape,which is speculated to be related to the living habits of Jinbei common carp in the field.2.Muscle fibers and metabolic enzyme activity characteristics of the Jinbei common carp in rice fieldsUsing pond cultured Jinbei common carp as the control group,the characteristics of muscle fibers and metabolic enzyme activities of juvenile and adult Jinbei common carp in different growth stages of rice were explored.The results showed that the cross-section area of caudal stalk muscle fibers in the rice paddy group was significantly larger than that in the pond group（p<0.05）;The lactate dehydrogenase LDH、Ca²⁺ATPase of juvenile Jinbei common carp in paddy group was significantly higher than that in pond group at flowering stage and maturity stage（p<0.05）.Studies have shown that the caudal stalk muscle of the rice field Jinbei common carp has larger muscle fiber diameter and cross-sectional area,and the caudal stalk muscle has higher LDH and Ca²⁺-ATPase activities,which are characteristics of its adaptation to shallow water life in paddy fields.3.Characteristics of muscle fiber related genes Igf-1,Igf-1r,Irs1,Pi3k and Akt1 of the caudal stalk of Jinbei common carp in rice fieldsTaking the pond cultured carp as the control group,the expression characteristics of key genes Igf-1,Igf-1r,Irs1,Pi3k and Akt1 in the PI3K/Akt pathway of juvenile and adult carp in different rice field growth period were explored.The results showed that there were no significant differences in the expression levels of Igf-1,Igf-1r,Irs1,Pi3k and Akt1 of juvenile Jinbei common carp in the paddy field compared with the pond group at rice maturity stage（p>0.05）;The expression level of Igf1,Igf1r,Irs1 in adult Jinbei common carp in paddy field was significantly higher than that in pond group（p<0.05）,the expression levels of Pi3k and Akt1 in rice mature stage were significantly higher than those in pond group（p<0.05）.Studies have shown that in the PI3K/AKT signaling pathway,Igf-1,Igf-1r,Irs1,Pi3k and Akt1 genes are up-regulated during the muscle movement of the caudal stalk of Jinbei common carp,and their up-regulation is positively correlated with the increase of the cross-section area of muscle fibers.Juvenile Jinbei common carp is small,weak in feeding ability in the rice field,less resistance in the process of shuttling in the rice field,and the expression level of key genes in the PI3K/AKT pathway is low.However,in the process of wagging the tail stalk,the movement resistance of adult Jinbei common carp is high due to the influence of shallow water level and rice plants.And the PI3K/AKT pathway is activated.It causes up-regulation of Igf-1,Igf-1R,Irs1,Pi3k and Akt1 genes,accelerates muscle fiber protein synthesis,and promotes muscle hypertrophy,which is an adaptive characteristic of Jinbei common carp living in paddy fields for a long time.4.Characteristics of Ampk,Sirt1 and Pgc-1αin caudal stalk muscle fibers of Jinbei common carpTaking the Jinbei common carp cultured in ponds as the control group,the expression characteristics of key genes in the AMPK pathway of the caudal stalk muscle fibers of the Jinbei common carp in paddy fields were explored.The results showed that the expression levels of Ampk and Sirt1 of juvenile fish in paddy field group were significantly lower than those in pond group at flowering stage and maturity stage（p<0.05）,and Pgc-1αin paddy field group was significantly lower than that in pond group at maturity stage（p<0.05）.The expression levels of Ampk,Sirt1 and Pgc-1αin paddy field group were significantly higher than those in pond group at rice maturation stage（p<0.05）.The results showed that in AMPK pathway,the swing of caudal stalk in the rice field induced the high expression of Ampk gene,and Ampk directly mediated the high expression of downstream gene Pgc-1α.Pgc-1αcan enhance mitochondrial biosynthesis,enhance muscle oxidative metabolism,inhibit muscle catabolism,and thus increase the cross-sectional area of muscle fibers.Meanwhile,Ampk can also indirectly regulate the downstream Pgc-1αby activating Sirt1,resulting in an increase in the cross-sectional area of muscle fibers.