| Saline-alkaline water is a non-marine saline water resources distributed in the land area.Because of the characteristics of high salinity,high alkalinity,high p H and complex composition of ions,the development and utilization of saline-alkaline water is largely limited.Salinity and carbonate alkalinity are considered to be the main factors affecting the survival,growth and reproduction of aquatic animals in coastal saline-alkaline waters.Exopalaemon carinicauda has a strong environmental adaptability and a wide range of adaptability to salinity and carbonate alkalinity.It is an ideal experimental material for the study of the molecular mechanism of saline-alkaline adaptability of crustaceans.Therefore,this study takes E.carinicauda as the research object to explore the effects of long-term salinity,carbonate alkalinity and saline-alkaline complex stress on the growth performance and ovarian development of E.carinicauda,and provide basic data and ref-erence information for the saline-alkaline aquaculture of E.carinicauda.The main find-ings are as follows:1.Effect of saline-alkaline stress on growth performance and ovarian development of E.carinicaudaBased on the characteristics of coastal saline-alkaline water,a 60-day interactive stress experiment was conducted on E.carinicauda with different salinity(5,15 and 25)and carbonate alkalinity(3,5 and 8 mmol/L)gradients to explore the effects of saline-alkali stress on the growth performance and ovarian development of E.carinicauda.The results showed that salinity and carbonate alkalinity had a significant impact on the body length growth rate,body weight growth rate,and survival rate of E.carinicauda,but there was no significant interaction between salinity and carbonate alkalinity;The activity of carbonic anhydrase in gill tissue showed significant differences in salinity,carbonate al-kalinity,and salt alkali stress levels,while in muscle and hepatopancreas,the difference was only significant under carbonate alkalinity stress;The Na~+/K~+-ATPase activity in muscle,hepatopancreas,and gill tissues showed significant differences under three stress levels;The damage to gills and hepatopancreatic tissues of white shrimp under carbonate alkalinity stress is greater than that under salinity stress;Under salt alkali dual stress,the degree of damage to liver and pancreatic tissue is greater than that under single factor stress.In addition,salinity stress,carbonate alkalinity stress,and saline-alkaline complex stress can also affect the ovarian development speed of E.carinicauda.2.Analysis of transcriptome characteristics of the ovarian development of E.carini-cauda under low salinity stressIn order to explore the molecular regulation mechanism of the ovarian development of E.carinicauda under low salinity stress,this study set up 5(LS)and 25(CG)salinity culture E.carinicauda.After 60 days,the ovaries and eyestalks were taken and sequenced by transcriptomics.The results showed that 389 DEGs were identified in ovarian tissue;The 5 signal pathways enriched in arginine biosynthesis and metabolism pathway partic-ipated in the regulation of ovarian development during low salt stress;Estradiol 17 was screenedβThe expression of 10 DEGs related to ovarian development,such as dehydro-genase,ecdysteroid regulatory protein and Vg,was up-regulated,and the expression of 6DEGs,such as JHE-like carboxylesterase 1,arrestin homologue,and FMRF amide recep-tor,was significantly down-regulated.1223 DEGs were identified in the eyestalks,which were enriched in 7 pathways of insect hormone biosynthesis and folate biosynthesis,which were related to ovarian development;Ten differentially expressed genes related to ovarian development,such as PDH 1,retinol dehydrogenase 11 and Hsp70,were up-regulated,including insect juvenile hormone and estradiol 17βDehydrogenase and VMO-1 and other 8 DEGs were significantly down-regulated.The tissue section showed that low salinity stress did not cause substantial damage to the ovarian tissue of E.carini-cauda,only the number of follicular cells was relatively small.The results showed that long-term low salt stress could affect the number of ovarian follicular cells,resulting in relatively slow ovarian development of E.carinicauda,but the up-regulated expression of ovarian development-related genes would still promote ovarian development.3.Analysis of the transcriptome characteristics of the ovarian development of E.carinicauda under high carbonate alkalinity stressTo explore the molecular regulation mechanism of ovarian development of E.ca-rinicauda under high salinity stress,transcriptome sequencing technology was used.In this study,2 mmol/L(control group,CG)and 8 mmol/L(HC)were used to culture E.carinicauda with gradient salinity.After 60 days,the ovaries and eyestalks of each group were sequenced by transcriptome.The results showed that a total of 1102 DEGs were identified in the ovary;KEGG enrichment analysis showed that there were 5 signal path-ways related to ovarian development,including the interaction of neuroactive ligand-re-ceptor and metabolic pathway;15 significantly up-regulated DEGs,including VMO-1,C-type lectin and methyl farnesate epoxidase,and 3 down-regulated DEGs,including Wnt 4 and tachykinin-like peptide receptor,were screened to participate in ovarian de-velopment;A total of 468 DEGs were identified in the eyestalk.4 signal pathways related to ovarian development,such as metabolic pathway and lysosome,were obtained by KEGG enrichment analysis.7 significantly up-regulated DEGs,including VMO-1,ec-dysteroid regulatory protein and arrestin homologues,and six significantly down-regu-lated DEGs,such as PDH 1,FMRF amide receptor and CYP315,were screened to par-ticipate in ovarian development.The tissue section observation of white shrimp ovary showed that compared with the control group,the number of oocytes in E.carinicauda ovary was less and the development was slower after long-term high carbonate alkalinity stress.It is speculated that long-term high carbonate alkalinity stress can affect the devel-opment of ovary,thus affecting the development and maturation of oocytes.4.Analysis of transcriptome characteristics of the ovarian development of E.carini-cauda under saline-alkaline stressBased on the characteristics of coastal saline-alkaline water,set low salinity(5)and high carbonate alkalinity(8 mmol/L)stress concentration,take normal seawater as the control group(CG),take the ovaries and eyestalks of each group after 60 days of cultiva-tion,and conduct transcriptome sequencing respectively.The results showed that a total of 1200 DEGs were identified in the ovary;KEGG enrichment analysis showed that ly-sosomes and insect hormone biosynthesis were involved in the regulation of ovarian de-velopment during saline-alkaline stress;8 significantly up-regulated DEGs,including heat shock 70 protein,VMO-1 and estrogen-related receptor,and nine significantly down-regulated DEGs,including Vg,G protein-coupled receptor and juvenile hormone epoxide hydrolase,were found to be related to ovarian development.A total of 930 DEGs were identified in the eyestalk;KEGG enrichment analysis showed that 6 Wnt signaling path-ways and ECM-receptor interactions were related to ovarian development;Neuron 2 and C-type lectin were selected to significantly up-regulate DEGs,and vitellinogen and G-protein-coupled receptors were selected to significantly down-regulate DEGs in ovarian development.The histological observation of the ovary of E.carinicauda showed that saline-alkaline stress affected the development speed of the ovary.It is speculated that saline-alkaline stress may affect the development and maturation of oocytes by reducing the transcription level of Vg.In summary,low salinity stress,high carbonate alkalinity,and saline-alkaline com-bined stress can all affect the ovarian development of white shrimp,but their different mechanisms of influence on the ovaries of E.carinicauda are different.Specifically,un-der low salinity stress,the number of DEGs in the eyestalks is the highest,while under high carbonate alkalinity stress,the number of DEGs in the ovaries is the highest;In the ovaries,low salinity stress promotes ovarian development by upregulating the expression of Vg,while high carbonate alkalinity stress does not change the expression of Vg,while saline-alkaline combined stress inhibits ovarian development by downregulating the ex-pression of Vg;In the eyestalk,both low salinity stress and high carbonate alkalinity up-regulated the expression of PDH,while PDH did not show any difference under saline alkaline complex stress.Although the growth and ovarian development speed of the E.carinicauda were affected to some extent under salinity,carbonate alkalinity,and saline-alkaline stress conditions,it is the E.carinicauda that can regulate ovarian development by regulating genes and signaling pathways related to ovarian development. |
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