Application of taurine in promoting litopenaeus vannamei larvae to adapt to low-salinity water body

Abstract

The invention discloses an application of taurine in promoting litopenaeus vannamei larvae to adapt to a low-salinity water body, taurine is used as a survival and growth promoter for feeding the larvae, and the influence on the adaptive capacity under the low-salinity condition, including survival rate, body length, tissue structure, cell proliferation and osmotic pressure regulation capacity, is explored. Research finds that taurine promotes the adaptive capacity of litopenaeus vannamei larvae in a low-salinity water body, which shows that the taurine significantly improves the survival rate and body length of the larvae; after the taurine is added, muscle fibers of the young shrimps are tighter, and tissue boundaries are clearer; transcriptomics results show that taurine negatively regulates a Wnt pathway to promote proliferation of epithelial cells of the young shrimps, and receptor signals coping with external stimulation and response gene expression are reduced; the taurine also relieves the NKA enzyme activity and protein expression level induced by the low-salinity water body. Therefore, the taurine can be used as a survival and growth promoter for improving the adaptive capacity of the litopenaeus vannamei larvae in a low-salinity water body.

Description

Technical Field

[0001] The present invention belongs to the technical field of shrimp survival and growth promoters, and specifically relates to the application of taurine in promoting the adaptation of Litopenaeus vannamei postlarvae to low-salinity water bodies. Background Art

[0002] Litopenaeus vannamei, commonly known as the whiteleg shrimp, belongs to the class Malacostraca, order Decapoda, family Penaeidae, and genus Litopenaeus. It is native to the coastal waters of the Pacific Ocean in the Americas, with a relatively large distribution in the coastal waters from southern Peru to Sonora, Mexico, and is most concentrated in Ecuador. Litopenaeus vannamei is rich in nutrition, and its muscle contains a variety of essential amino acids, making it an important source of high-quality animal protein for humans. Litopenaeus vannamei has the following advantages in aquaculture production: wide temperature tolerance, capable of surviving at 16°C - 38°C; wide salinity tolerance, able to grow in fresh water to seawater with a salinity of 40‰; short growth cycle, able to reach the market size in 3 months to 100 days depending on the culture temperature; low nutritional requirements, with a protein content of about 20% in the feed being sufficient to meet its growth needs; and it also has characteristics such as strong adaptability and disease resistance. Since it was introduced into China in the late 1980s, significant achievements have been made in the cultivation of Litopenaeus vannamei. However, with the increasing shortage of China's marine resources and the pollution of coastal seawater, the success rate of shrimp seawater aquaculture is getting lower and lower; the desalination culture technology of Litopenaeus vannamei has been successful and rapidly promoted, but there are unfavorable factors such as low unit area yield and changed muscle quality in the desalination culture of Litopenaeus vannamei; these are all closely related to the osmotic stress caused by low-salinity conditions. To improve the growth performance of Litopenaeus vannamei in freshwater aquaculture, it is necessary to improve its osmotic regulation ability under low-salinity conditions through means such as nutritional regulation.

[0003] Taurine is an important functional amino acid that participates in the regulation of a large number of biological functions, such as heart rhythm regulation, nerve impulse, cell proliferation, and bile acid synthesis. These functions are mostly related to the transport of Ca 2＋ , Na + and K + ion transport and protein phosphorylation, etc. In many aquatic animals, taurine has been proven to be a conditionally essential amino acid. Results in various cultured fish such as Scophthalmus maximus have shown that adding taurine can significantly improve the growth performance of fish. In addition, studies in teleost fish have shown that taurine also plays an important role in osmotic regulation. Summary of the Invention

[0004] The present invention aims to provide the application of taurine in promoting the adaptation of Litopenaeus vannamei postlarvae to low-salinity water bodies. Through research, the present invention has found that taurine has functions such as improving the survival and growth of postlarvae, promoting cell proliferation of postlarvae, and enhancing the osmotic pressure regulation ability of postlarvae. Therefore, it can be used as a promoter to improve the survival, growth, cell proliferation, and osmotic pressure regulation ability of Litopenaeus vannamei, which has important application value.

[0005] To achieve the above object, the technical solution adopted by the present invention is as follows: The present invention provides the application of taurine in promoting the adaptation of Litopenaeus vannamei postlarvae to low-salinity water bodies.

[0006] Further, the indexes of the adaptation ability include: survival rate, body length, tissue structure, cell proliferation, and osmotic pressure regulation ability.

[0007] Further, the taurine promotes the survival and growth of Litopenaeus vannamei postlarvae in low-salinity water bodies.

[0008] Further, after adding taurine, the survival and growth of Litopenaeus vannamei postlarvae in low-salinity water bodies are promoted. The survival rate of Litopenaeus vannamei postlarvae cultured in normal seawater is 92.67%, while the survival rate in low-salinity water bodies decreases significantly, only being 61.11%. After adding taurine, the survival rate of postlarvae in low-salinity water bodies can significantly increase to 76.67%. Similarly, the body length of postlarvae significantly increases after adding taurine.

[0009] Further, the taurine improves the tissue structure of Litopenaeus vannamei postlarvae in low-salinity water bodies.

[0010] Further, after culturing Litopenaeus vannamei postlarvae in low-salinity water bodies, the spaces between muscle fibers become larger, and the boundaries between tissues become blurred. After adding taurine, the tissue structure of postlarvae is improved, the muscle fibers are tighter, and the boundaries are clearer.

[0011] Further, the taurine promotes cell proliferation of Litopenaeus vannamei postlarvae in low-salinity water bodies.

[0012] Further, the expression of genes related to cell proliferation and differentiation pathways in Litopenaeus vannamei postlarvae in low-salinity water bodies is down-regulated. After adding taurine, the proliferation of epithelial cells of postlarvae is promoted by negatively regulating the Wnt signaling pathway, indicating that taurine enhances the epithelial cell proliferation of Litopenaeus vannamei postlarvae.

[0013] Further, the taurine enhances the osmotic pressure regulation ability of Litopenaeus vannamei postlarvae in low-salinity water bodies.

[0014] Furthermore, the low-salinity water body significantly upregulates signal pathways such as ligands, activators, and regulators of receptors in postlarval shrimp. After adding taurine, the receptor signals and response gene expressions of postlarval shrimp in response to external stimuli are significantly reduced. In addition, after adding taurine, the NKA enzyme activity and in-situ expression level of NKA protein induced by the low-salinity water body are significantly alleviated, indicating that taurine significantly enhances the osmotic regulation ability of postlarval shrimp in the low-salinity water body.

[0015] The present invention also provides a promoter for the adaptability of Litopenaeus vannamei postlarval shrimp in a low-salinity water body, and the promoter includes taurine.

[0016] Compared with the prior art, the beneficial effects of the present invention are as follows: By feeding Litopenaeus vannamei postlarval shrimp with taurine as a survival and growth promoter, the present invention explores the effect of taurine on the adaptability of Litopenaeus vannamei postlarval shrimp in a low-salinity water body, including survival rate, body length, tissue structure, cell proliferation, osmotic regulation ability, etc. It is found that taurine can improve the survival rate and growth of Litopenaeus vannamei postlarval shrimp in a low-salinity water body, and promote the integrity of muscle fibers and tissue structure. At the same time, taurine promotes epithelial cell proliferation by negatively regulating the Wnt pathway, and significantly downregulates the receptor signals and response gene expression levels in response to external stimuli. In addition, taurine, as an osmotic regulator, alleviates the NKA enzyme activity and in-situ expression level of protein induced by the low-salinity water body. Therefore, taurine can be used as a survival and growth promoter to promote the adaptation of Litopenaeus vannamei postlarval shrimp to the low-salinity water body, enhance the production performance of Litopenaeus vannamei postlarval shrimp in low-salinity water body culture, and is of great significance for promoting the desalination culture of Litopenaeus vannamei. Description of the Drawings

[0017] Figure 1 Survival rate results of postlarval shrimp in different treatment groups in Example 1 of the present invention; Figure 2 Body length statistics results of postlarval shrimp in different treatment groups in Example 1 of the present invention; Figure 3 Section staining results of postlarval shrimp in different treatment groups in Example 1 of the present invention; Figure 4 Volcano plot of differential genes of samples of postlarval shrimp in different treatment groups in Example 1 of the present invention; Figure 5 GO enrichment analysis results of differentially expressed genes of postlarval shrimp in different treatment groups in Example 1 of the present invention; Figure 6 Detection results of NKA enzyme activity levels of postlarval shrimp in different treatment groups in Example 1 of the present invention; Figure 7 Immunofluorescence map results of NKA of postlarval shrimp in different treatment groups in Example 1 of the present invention. Detailed implementation manners

[0018] The technical solutions of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts belong to the scope of protection of the present invention.

[0019] Example 1 Research on the promotion of Litopenaeus vannamei postlarvae to adapt to low-salinity water by taurine 1. Test materials Select the same batch of Litopenaeus vannamei postlarvae that are bred, of the same specification and healthy, and raise them in an indoor experimental tank. They are divided into three groups: a control group (Control, C), a low-salinity water group (Low-salinity, L), and a low-salinity water + taurine group (Taurine, T). Feed the microcapsule bait 6 times a day. Among them, the low-salinity water + taurine group additionally supplements 0.3% by mass of taurine in the microcapsule feed. After the experiment, count the survival rate and body length of the postlarvae in each group, and fix some postlarvae in paraformaldehyde and store them in a -80 °C refrigerator for subsequent analysis.

[0020] 2. Taurine improves the survival and growth of Litopenaeus vannamei postlarvae in low-salinity water To study the regulatory effect of taurine treatment on the survival and growth of Litopenaeus vannamei postlarvae, count the survival rate and body length of Litopenaeus vannamei postlarvae after the breeding cycle.

[0021] The results are as Figure 1 , Figure 2 shown. Figure 1 In the control group of the results, the survival rate of Litopenaeus vannamei postlarvae was 92.67%, while in the low-salinity water, the survival rate of the postlarvae decreased significantly, only 61.11%. After adding taurine, the survival rate of the postlarvae in the low-salinity water increased significantly, reaching 76.67%. Figure 2 In the control group of the results and the low-salinity water, the body lengths of Litopenaeus vannamei postlarvae were 0.69 cm and 0.70 cm, respectively, and there was no significant difference between the two. After adding taurine, the body length of the postlarvae could reach 0.75 cm, which was significantly greater than the other two groups. The above results indicate that adding taurine improves the survival and growth of Litopenaeus vannamei postlarvae in low-salinity water.

[0022] 3. Taurine improves the tissue structure of Litopenaeus vannamei postlarvae in low-salinity water Perform paraffin sectioning on the Litopenaeus vannamei postlarvae in the control group, the low-salinity group, and the low-salinity + taurine group, and then observe the sections of the whole shrimp by H&E staining. The specific experimental steps are as follows: (1) Preparation of paraffin sections of juvenile penaeid shrimp 1) Tissue fixation: Anaesthetize penaeid shrimp with MS-222, take the whole shrimp in the saline group, fresh water group and taurine + fresh water group, and place them in 4% paraformaldehyde for more than 24 h to ensure that the tissue is fully immersed in the fixative.

[0023] 2) Gradient dehydration: Transfer the fixed tissue successively to 60% absolute ethanol for 4 h, 70% absolute ethanol overnight (8 - 10 h), 80% absolute ethanol for 2 h, 90% absolute ethanol for 2 h, 95% absolute ethanol I for 1.5 h, 95% absolute ethanol II for 1 h, 100% absolute ethanol I for 0.5 h, and 100% absolute ethanol II for 0.5 h.

[0024] 3) Clearing: Benzene-ethanol solution for 10 min, xylene I for 7 min, xylene II for 7 min.

[0025] 4) Wax infiltration: Infiltrate with paraffin at 60 °C for 3 times, change the cylinder each time, and each time for 1 h.

[0026] 5) Embedding: Place the tissue completed with wax infiltration in the central position of the metal embedding frame and wait for the wax block to solidify.

[0027] 6) Sectioning: Trim the wax block section and fix it on the microtome for sectioning (thickness 5 µm), transfer it to a spreading machine with a water temperature of 41 °C, pick up the section immediately after the section surface is flat, and place it in a constant temperature oven at 65 °C for 2 h for standby.

[0028] (2) Hematoxylin-eosin (H&E) staining procedure 1) Dewaxing: Take out the sections from the oven, and then transfer them to xylene I for 20 min, xylene II for 15 min, and xylene III for 15 min to complete the dewaxing treatment.

[0029] 2) Replace xylene: Absolute ethanol I for 5 min, absolute ethanol II for 5 min, 75% absolute ethanol for 5 min, and wash with water for 3 min.

[0030] 3) Hematoxylin staining: For 3 min (the time can be adjusted according to the effect of the hematoxylin staining solution), wash twice with water, and then soak in water for 3 min.

[0031] 4) After washing, immerse the glass slides in the differentiation solution (99 mL 70% alcohol + 1 mL concentrated HCl) for 3 - 5 s, wash in water for 5 s, dry the water and then examine under the microscope. If it is found that the staining is too deep, continue to wash in water for a period of time to fully remove HCL. If the differentiation is incomplete, it can be re-immersed in the differentiation solution.

[0032] 5) After rinsing, immerse in the blueing solution (99 mL of 70% alcohol + 1 mL of concentrated ammonia water) for 3 - 5 s. After taking out, rinse under distilled water, and then transfer to distilled water for immersion washing for 3 min.

[0033] 6) Place the glass slide in 85% ethanol for 5 min, 95% ethanol for 5 min, and immerse in the eosin solution (1 g of water-soluble eosin dissolved in 100 mL of 85% alcohol) for 2 - 3 min. If the staining is difficult, 1 - 2 drops of glacial acetic acid can be added to every 100 mL of the staining solution, which can make the tissue easier to stain and not easy to decolorize.

[0034] 7) Dehydrate with gradient alcohol: absolute ethanol I for 5 min, absolute ethanol II for 5 min, absolute ethanol III for 5 min, n-butanol for 5 min, xylene I for 5 min, xylene II for 5 min.

[0035] 8) Mount the slide with neutral balsam and image: Use the AXIOVISION software to obtain images in a microscope (Olympus).

[0036] (3)Result analysis The H&E staining results of the paraffin sections of juvenile shrimp are as Figure 3 shown. Compared with the control group, the space between muscle fibers of Litopenaeus vannamei juvenile shrimp becomes larger after being cultured in low-salinity water, and the boundary between tissues becomes blurred. After adding taurine, the tissue structure of juvenile shrimp is improved, the muscle fibers are more compact, and the boundary between tissues is also clearer. The above results indicate that adding taurine improves the tissue structure of Litopenaeus vannamei juvenile shrimp in low-salinity water and also achieves the function of improving the growth and survival of juvenile shrimp.

[0037] 4. Taurine promotes cell proliferation of Litopenaeus vannamei juvenile shrimp in low-salinity water To study the regulatory effect of taurine treatment on the cell proliferation of Litopenaeus vannamei juvenile shrimp in low-salinity water, the enrichment of genes related to cell proliferation was detected by extracting RNA and then performing transcriptomic sequencing analysis. The specific experimental steps are as follows: (1)Extraction of total RNA 1) Take out the tissue sample from the -80 °C refrigerator, put it into a 2 mL RNAiso Plus centrifuge tube containing 1 mL of TRIzol reagent, add glass beads sterilized with DEPC-treated water, homogenize in a homogenizer for 1 min and observe whether the tissue in the TRIzol has been completely broken, and then immediately let it stand at 4 °C for 10 min.

[0038] 2) Add 0.2 mL of chloroform, shake the centrifuge tube vigorously for 10 s, let it stand at 4 °C for 5 min, and then centrifuge at 12000 r / min at 4 °C for 15 min.

[0039] 3) Carefully aspirate the supernatant into a new 1.5 mL RNAiso Plus centrifuge tube, add an equal volume of isopropanol, gently invert the tube up and down several times. After the isopropanol fully reacts with the supernatant, let it stand at 4°C for 10 min and then centrifuge at 12,000 r / min at 4°C for 10 min.

[0040] 4) Discard the supernatant, add 1 mL of 75% ethanol prepared with DEPC water to resuspend the precipitate, and centrifuge at 7,500 r / min at 4°C for 5 min.

[0041] 5) Discard the supernatant, repeat step 4), and then let it stand and dry on ice in the fume hood for about 10 min until the 75% ethanol in the centrifuge tube has completely evaporated. Add an appropriate amount of DEPC water to dissolve the precipitate. If necessary, gently pipette the precipitate to completely dissolve it.

[0042] 6) Detection of RNA purity and concentration: Using DEPC water as a blank control, take 1 μL of RNA in a ultra-micro spectrophotometer to measure the concentration of the RNA sample and the ratio of OD260 / OD280. When the absorbance ratio is between 1.9 - 2.1, it indicates that the extracted total RNA has high purity and no protein or genomic contamination.

[0043] 7) Detection of RNA integrity: Take 2 μL of RNA, mix it with 1 μL of loading buffer, perform 1% agarose gel electrophoresis at a voltage of 140 V for 18 min, and then observe the results in a gel imaging system. If the 28S and 18S bands are clear and the brightness ratio is approximately 2:1, and the 5S band is faintly visible, it indicates that the extracted total RNA has good integrity. Subsequently, the RNA is used to construct a library and transcriptome sequencing is performed using Illumina Novaseq 6000.

[0044] (2)Transcriptome analysis 1) Quality assessment of sequencing data: Use the fastp software (https: / / github.com / OpenGene / fastp) to filter the raw data to obtain high-quality sequencing data and perform statistics and quality assessment again. Align the quality-controlled raw data with the reference genome, and at the same time perform quality assessment on the alignment results of this transcriptome sequencing, mainly including sequencing saturation, gene coverage, distribution of Reads in different regions of the reference genome, and distribution analysis of Reads on different chromosomes (using the software: HiSat2, http: / / ccb.jhu.edu / software / hisat2 / index.shtml).

[0045] 2) Analyze the differential gene expression among different samples: Use the RSEM software (http: / / deweylab.github.io / RSEM / ) to quantitatively analyze the expression levels of genes and transcripts respectively for subsequent analysis of the differential gene expression among different samples. Use the DESeq2 software (http: / / bioconductor.org / packages / stats / bioc / DESeq2) to analyze the gene expression differences among samples and identify the differentially expressed genes (DEGs). The screening criteria for significantly differentially expressed genes are: FDR < 0.05 and |log2FC| ≥ 1.

[0046] 3) GO enrichment analysis: Utilize the GO (gene ontology) database (http: / / geneontology.org / ) to classify genes according to the biological processes, cellular components, and molecular functions they participate in, and perform GO annotation on the differentially expressed genes.

[0047] (3)Results and analysis The sequencing analysis results of transcriptomics are as Figure 4 and Figure 5 shown. Among them, Figure 4 is the volcano plot of differential genes, Figure 5 is the GO enrichment result plot of differential genes. Figure 4 The results show that compared with the control group, the numbers of up-regulated and down-regulated genes in the larvae of the low-salinity water group are 497 and 437 respectively, while the numbers of up-regulated and down-regulated genes in the larvae after adding taurine are 396 and 133 respectively, indicating that adding taurine significantly reduces the number of differentially expressed genes under low-salinity water conditions. Figure 5 The GO enrichment analysis results of

[0048] show that low-salinity water leads to the down-regulation of genes related to pathways such as cell proliferation and differentiation in the larvae of Litopenaeus vannamei, while adding taurine promotes the proliferation of epithelial cells in the larvae of Litopenaeus vannamei by negatively regulating the Wnt signaling pathway, indicating that taurine promotes the proliferation of epithelial cells in the larvae of Litopenaeus vannamei in low-salinity water. To study the effect of taurine treatment on the osmotic regulation ability of the larvae of Litopenaeus vannamei in low-salinity water, further enrichment analysis of the differentially expressed genes obtained from the above transcriptomics, kit detection of NKA enzyme activity, and immunofluorescence detection of the in-situ expression of NKA protein were carried out. The specific experimental steps are as follows: (1) Perform GO enrichment analysis on the differentially expressed genes obtained in the transcriptome as described above to detect the main enriched signal pathways.

[0049] (2) Kit method for detecting NKA enzyme activity The samples of larval Penaeus vannamei from different treatment groups (frozen in -80℃ refrigerator) were accurately weighed, and 9 volumes of physiological saline were added and mechanically homogenized in an ice bath, followed by centrifugation at 2500 r / min for 10 min. The supernatant was taken and 10% of the homogenate supernatant was used to determine the Na + / K + -ATPase activity. The protein content in the sample was first determined using a Coomassie brilliant blue staining test kit (W067, Nanjing Jiancheng Bioengineering Institute), and then ultra-trace Na + / K + -ATPase test kit (A070-2, Nanjing Jiancheng Bioengineering Institute) to detect Na + / K + -ATPase activity, with one unit (U) being the amount of ATP decomposed into ADP per mg of shrimp tissue per hour to produce 1 μmoL of inorganic phosphorus.

[0050] (3) Immunofluorescence detection of in situ expression of NKA protein; 1) Dewaxing and removing xylene from the paraffin sections obtained above; 2) Repair the above sections with 1% EDTA-2Na repair solution in a microwave oven, and after cooling to room temperature, wash the slides twice with PBS, 5 min each time; 3) Use a histochemical pen to draw a circle around the tissue, block with protein blocking solution for 30 minutes, and rinse with PBS to remove the blocking solution; 4) Add diluted mouse NKA antibody to tissue sections, place at 4°C overnight, and wash 4 times with PBS to remove unbound antibody; 5) Add diluted goat anti-mouse secondary antibody to tissue sections, leave at room temperature for 45 minutes, and wash 4 times with PBS to remove unbound antibody; 6) Use DAPI to stain the cell nucleus at room temperature for 8 min, wash twice with PBS, absorb the water around the tissue with absorbent paper, add anti-fluorescence attenuation mounting medium and seal with a coverslip; 7) Use an Olympus BX53 fluorescence microscope to collect fluorescence signals, and use the corresponding imaging system to analyze and process the images.

[0051] (4) Results and analysis The results are as follows Figure 5 ,Figure 6 and Figure 7 as shown Figure 5 The GO enrichment analysis in [study] showed that low salinity water led to a significant up - regulation of signal pathways such as ligands, activators, and regulators of receptors in postlarvae, while the addition of taurine significantly reduced the receptor signals and the expression of response genes of postlarvae in response to external stimuli, thus saving the energy consumed in coping with stimuli for growth. Figure 6 The results of NKA enzyme activity detection in [study] showed that low salinity water led to a significant increase in NKA enzyme activity in postlarvae, while the addition of taurine alleviated the NKA enzyme activity level induced by low salinity. Figure 7 The in - situ expression results of NKA protein in [study] showed that low salinity water led to a significant increase in the in - situ expression of NKA protein in postlarvae, and taurine also alleviated the in - situ expression of NKA protein induced by low salinity water. Therefore, taurine enhanced the osmotic regulation ability of Litopenaeus vannamei postlarvae in low salinity water.

Claims

1. Application of taurine in promoting the adaptation of Litopenaeus vannamei postlarvae to low-salinity water bodies.

2. The application according to claim 1, wherein The indicators of the adaptation ability of Litopenaeus vannamei in low-salinity water bodies include: survival rate, body length, tissue section structure, cell proliferation, and osmotic regulation ability, etc.

3. The application according to claim 2, wherein The taurine promotes the survival and growth of Litopenaeus vannamei postlarvae in low-salinity water bodies.

4. The application according to claim 3, characterized in that, After adding taurine, the survival rate and body length of Litopenaeus vannamei postlarvae in low-salinity water bodies are increased. The survival rate of Litopenaeus vannamei postlarvae cultured in high-salinity water bodies is 92.67%, while after desalination treatment, the survival rate significantly decreases, only being 61.11%. However, after adding taurine, the survival rate of postlarvae in low-salinity water bodies is significantly increased, reaching 76.67%. Similarly, after adding taurine, the body length of postlarvae in low-salinity water bodies is significantly increased.

5. The application according to claim 2, wherein The taurine improves the tissue structure of Litopenaeus vannamei postlarvae in low-salinity water bodies.

6. The application according to claim 5, characterized in that, After the Litopenaeus vannamei postlarvae are cultured in low-salinity water bodies, the spaces between muscle fibers become larger, and the boundaries between tissues become blurred. However, after adding taurine, the tissue structure of the postlarvae is improved, the muscle fibers are more compact, and the boundaries are clearer.

7. The application according to claim 2, characterized in that, The taurine promotes the cell proliferation of Litopenaeus vannamei postlarvae in low-salinity water bodies.

8. The application according to claim 7, characterized in that, The results of transcriptome sequencing show that low-salinity water bodies lead to the down-regulation of the expression of genes related to cell proliferation, differentiation and other pathways in postlarvae. However, after adding taurine, the proliferation of epithelial cells of postlarvae is promoted by negatively regulating the Wnt signaling pathway, indicating that taurine promotes the epithelial cell proliferation of Litopenaeus vannamei postlarvae.

9. The application according to claim 2, characterized in that, The taurine enhances the osmotic regulation ability of Litopenaeus vannamei postlarvae in low-salinity water bodies.

10. The application according to claim 9, characterized in that, The results of transcriptome sequencing show that low-salinity water bodies lead to a significant up-regulation of signal pathways such as ligands, activators and regulators of receptors in postlarvae. However, after adding taurine, the receptor signals and the expression of response genes of postlarvae in response to external stimuli are significantly reduced. In addition, after adding taurine, the NKA enzyme activity and the in-situ expression level of NKA protein induced by low-salinity water bodies in postlarvae are significantly alleviated, indicating that taurine enhances the osmotic regulation ability of Litopenaeus vannamei postlarvae in low-salinity water bodies.

11. A survival and growth promoter for Litopenaeus vannamei postlarvae in low-salinity water bodies, characterized in that, The survival and growth promoter includes taurine.

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