| As the oviparous, Poultry embryonic development is susceptible to external environmental factors, including nutrition, incubation temperature, hormones and exercise, in particular the incubation temperature has great impact on poultry embryonic development and metabolism. In this study the duck embryo was selected as the research, by changing the incubation temperature in duck middle and late embryonic period we detected changes of tissue and organ development, blood lipid metabolism of duck embryo and hatched ducklings. Meanwhile, we further investigated the molecular mechanism of the effects of incubation temperature on embryonic tissue development by Transcriptome sequencing, in which duck leg muscle was selected as the research object.The main results and conclusions are listed as follows:(1)Incubation temperature treatment had a certain influence on incubation effect, However, compared with control group no significant difference was found(P>0.05). Leg muscle development was inhibited by elevated incubation temperature, there were significant differences on day E25and the day of hatching between the two groups (P<0.05). Ducklings weight increased by incubation temperature in treatment group. The weight of breast and leg muscle in treatment group were heavier than control group on W2, W4and W6, and there was significant difference between the two groups’leg muscle weight on W6(P<0.05).(2) The impact of incubation temperature on duck embryos and ducklings heart development was not obvious, the overall performance was inhibition, only a significant difference on the E25was found between the two groups (P<0.05). We found temperature could inhibit liver development in the embryonic period, but facilitate its developmen in the postnatal period, and significant differences were found in the research stages (P<0.05).(3) The duck blood glucose levels were reduced by raising the incubation temperature, and significant difference between the two groups was found at4weeks of age (P<0.05). Higher Incubation temperature had an impact on blood lipid metabolism indicators. The plasma TG, TC and LDL levels of treatment group were higher than the control group. The difference between two groups’LDL levels was significant in embryonic period (P<0.05), and TC was significant in postnatal period (P<0.05).(4)Incubation temperature also had some impacts on the duck immune organs development in embryonic stage. The results showed that thymus, spleen and bursa organ index of the treatment group ducks decreased in embryonic period, in which the bursa index differences between the two groups was significant on E25(P<0.05), the spleen index differences of two groups on the day of hatching was significant (P<0.05).Higher incubation temperature also had an impact on the content of IFN-γ and immunoglobulin/total protein ratio, and significant differences of the both indexes between the two groups were found at W2(P<0.05).(5) The impact of incubation temperature on the duck embryonic development, also indirectly affect the duck embryo tissue development and blood lipid metabolism during the postnatal period. The results showed that:in the treated group, blood glucose levels revealed a significant negative correlation between the E20and W4(P<0.01), as well as the day of hatching and W4(P<0.01). TG levels in the blood of control group between the day of hatching and W2showed a significant negative correlation (P<0.05), TC levels showed a negative correlation between E20and W2in treatment group, with a positive correlation between E20and W2in the control group.(6)The results of analysis of the impact of incubation temperature on duck embryo muscle development showed that the breast and leg muscle of treatment group were larger than that in the control group on the day of E20and W2, which indicated that effect of incubation temperature on the E20duck leg muscle development was obvious. Therefore, the Illumina/Hiseq-2000RNA-seq deep sequencing analysis was used to analysis transcriptome data of duck E20leg muscle, and the analysis showed as follows:clean reads of two groups occupied over98%of the total number of reads. Distribution of Reads in the reference genome database was uniform and random. Growth rate of gene number was gentle, the number of genes detected tended to be saturated. All these results suggested the quality of this sequencing could meet the need of further analysis. In total, we detected335differently expressed genes, in which182genes were up-regulated and153genes were down-regulated. GO significant enrichment analysis showed these differently expressed genes mainly involved in cell composition, molecular function and biological process, which related with changes in cell morphology, cell-mediated immunity, energy metabolism and signal transduction. Signal pathway enrichment results showed that incubation temperature affected the duck embryonic muscle development by affecting the process of protein synthesis. Ribosomal metabolic processes and MAPK signal pathway were important molecular pathways for the effects of incubation temperature on duck embryo skeletal muscle development... |
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