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Transcriptome and Molecular Pathway Analysis of the Hepatopancreas in the Pacific White Shrimp Litopenaeus vannamei under Chronic Low-Salinity Stress.

Chen K, Li E, Li T, Xu C, Wang X, Lin H, Qin JG, Chen L - PLoS ONE (2015)

Bottom Line: In total, 26,034 genes were obtained from the hepatopancreas tissue of L. vannamei using the Illumina HiSeq 2000 system, and 855 genes showed significant changes in expression under salinity stress.Lipids or fatty acids can reduce osmotic stress in L. vannamei by providing additional energy or changing the membrane structure to allow osmoregulation in relevant organs, such as the gills.This study is the first report on the long-term adaptive transcriptomic response of L. vannamei to low salinity, and the results will further our understanding of the mechanisms underlying osmoregulation in euryhaline crustaceans.

View Article: PubMed Central - PubMed

Affiliation: Laboratory of Aquaculture Nutrition and Environmental Health, School of Life Sciences, East China Normal University, Shanghai, China.

ABSTRACT
The Pacific white shrimp Litopenaeus vannamei is a euryhaline penaeid species that shows ontogenetic adaptations to salinity, with its larvae inhabiting oceanic environments and postlarvae and juveniles inhabiting estuaries and lagoons. Ontogenetic adaptations to salinity manifest in L. vannamei through strong hyper-osmoregulatory and hypo-osmoregulatory patterns and an ability to tolerate extremely low salinity levels. To understand this adaptive mechanism to salinity stress, RNA-seq was used to compare the transcriptomic response of L. vannamei to changes in salinity from 30 (control) to 3 practical salinity units (psu) for 8 weeks. In total, 26,034 genes were obtained from the hepatopancreas tissue of L. vannamei using the Illumina HiSeq 2000 system, and 855 genes showed significant changes in expression under salinity stress. Eighteen top Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways were significantly involved in physiological responses, particularly in lipid metabolism, including fatty-acid biosynthesis, arachidonic acid metabolism and glycosphingolipid and glycosaminoglycan metabolism. Lipids or fatty acids can reduce osmotic stress in L. vannamei by providing additional energy or changing the membrane structure to allow osmoregulation in relevant organs, such as the gills. Steroid hormone biosynthesis and the phosphonate and phosphinate metabolism pathways were also involved in the adaptation of L. vannamei to low salinity, and the differential expression patterns of 20 randomly selected genes were validated by quantitative real-time PCR (qPCR). This study is the first report on the long-term adaptive transcriptomic response of L. vannamei to low salinity, and the results will further our understanding of the mechanisms underlying osmoregulation in euryhaline crustaceans.

No MeSH data available.


Pathways of glycosaminoglycan biosynthesis: keratan sulfate (ko00533).The red line indicates that the genes were up-regulated.
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pone.0131503.g002: Pathways of glycosaminoglycan biosynthesis: keratan sulfate (ko00533).The red line indicates that the genes were up-regulated.

Mentions: Various molecular pathways were obtained by Kyoto Encyclopedia of Genes and Genomes (KEGG) annotation. A total of 9,621 unigenes were mapped onto 317 pathways, and the most enriched sequences were metabolic pathways, which was followed by the biosynthesis of secondary metabolites, spliceosome and RNA transport. The top 20 pathways with the greatest number of annotated sequences are shown in Table 4. A total of 47 significantly changed GO terms were obtained, and the most significant change was in molecular functions, which was followed by catalytic activity, histone H4 acetylation, structural constituents of cuticle and chitin binding. All of the significantly changed (P < 0.05) GO pathways are listed in Table 5. A KEGG pathway enrichment analysis was performed for the gene expression between salinity treatments to identify the number of significantly changed samples along the pathway that were relevant to the background number. The most significantly changed KEGG pathways were the glycosphingolipid biosynthesis, lysine degradation, glycosaminoglycan biosynthesis and malaria pathways. The gene recorded as B3GNT1,2 was significantly up-regulated both in the glycosphingolipid biosynthesis pathway and glycosaminoglycan biosynthesis pathway when shrimp were exposed to salinity at 3 psu (Figs 1 and 2). In addition, fatty-acid biosynthesis (Fig 3) was significantly enhanced, especially in short-carbon-chain fatty acids (C8-C18). In addition, low-salinity conditions enhanced polyunsaturated fatty-acid (PUFA) biosynthesis, especially that of highly unsaturated fatty acids such as ARA, EPA and DHA (Figs 4 and 5). All of the significantly changed (P < 0.05) KEGG pathways are listed in Table 6. These annotations provide valuable information for studying the specific biological and metabolic processes and functions and molecular mechanisms under salinity stress in L. vannamei.


Transcriptome and Molecular Pathway Analysis of the Hepatopancreas in the Pacific White Shrimp Litopenaeus vannamei under Chronic Low-Salinity Stress.

Chen K, Li E, Li T, Xu C, Wang X, Lin H, Qin JG, Chen L - PLoS ONE (2015)

Pathways of glycosaminoglycan biosynthesis: keratan sulfate (ko00533).The red line indicates that the genes were up-regulated.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4492601&req=5

pone.0131503.g002: Pathways of glycosaminoglycan biosynthesis: keratan sulfate (ko00533).The red line indicates that the genes were up-regulated.
Mentions: Various molecular pathways were obtained by Kyoto Encyclopedia of Genes and Genomes (KEGG) annotation. A total of 9,621 unigenes were mapped onto 317 pathways, and the most enriched sequences were metabolic pathways, which was followed by the biosynthesis of secondary metabolites, spliceosome and RNA transport. The top 20 pathways with the greatest number of annotated sequences are shown in Table 4. A total of 47 significantly changed GO terms were obtained, and the most significant change was in molecular functions, which was followed by catalytic activity, histone H4 acetylation, structural constituents of cuticle and chitin binding. All of the significantly changed (P < 0.05) GO pathways are listed in Table 5. A KEGG pathway enrichment analysis was performed for the gene expression between salinity treatments to identify the number of significantly changed samples along the pathway that were relevant to the background number. The most significantly changed KEGG pathways were the glycosphingolipid biosynthesis, lysine degradation, glycosaminoglycan biosynthesis and malaria pathways. The gene recorded as B3GNT1,2 was significantly up-regulated both in the glycosphingolipid biosynthesis pathway and glycosaminoglycan biosynthesis pathway when shrimp were exposed to salinity at 3 psu (Figs 1 and 2). In addition, fatty-acid biosynthesis (Fig 3) was significantly enhanced, especially in short-carbon-chain fatty acids (C8-C18). In addition, low-salinity conditions enhanced polyunsaturated fatty-acid (PUFA) biosynthesis, especially that of highly unsaturated fatty acids such as ARA, EPA and DHA (Figs 4 and 5). All of the significantly changed (P < 0.05) KEGG pathways are listed in Table 6. These annotations provide valuable information for studying the specific biological and metabolic processes and functions and molecular mechanisms under salinity stress in L. vannamei.

Bottom Line: In total, 26,034 genes were obtained from the hepatopancreas tissue of L. vannamei using the Illumina HiSeq 2000 system, and 855 genes showed significant changes in expression under salinity stress.Lipids or fatty acids can reduce osmotic stress in L. vannamei by providing additional energy or changing the membrane structure to allow osmoregulation in relevant organs, such as the gills.This study is the first report on the long-term adaptive transcriptomic response of L. vannamei to low salinity, and the results will further our understanding of the mechanisms underlying osmoregulation in euryhaline crustaceans.

View Article: PubMed Central - PubMed

Affiliation: Laboratory of Aquaculture Nutrition and Environmental Health, School of Life Sciences, East China Normal University, Shanghai, China.

ABSTRACT
The Pacific white shrimp Litopenaeus vannamei is a euryhaline penaeid species that shows ontogenetic adaptations to salinity, with its larvae inhabiting oceanic environments and postlarvae and juveniles inhabiting estuaries and lagoons. Ontogenetic adaptations to salinity manifest in L. vannamei through strong hyper-osmoregulatory and hypo-osmoregulatory patterns and an ability to tolerate extremely low salinity levels. To understand this adaptive mechanism to salinity stress, RNA-seq was used to compare the transcriptomic response of L. vannamei to changes in salinity from 30 (control) to 3 practical salinity units (psu) for 8 weeks. In total, 26,034 genes were obtained from the hepatopancreas tissue of L. vannamei using the Illumina HiSeq 2000 system, and 855 genes showed significant changes in expression under salinity stress. Eighteen top Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways were significantly involved in physiological responses, particularly in lipid metabolism, including fatty-acid biosynthesis, arachidonic acid metabolism and glycosphingolipid and glycosaminoglycan metabolism. Lipids or fatty acids can reduce osmotic stress in L. vannamei by providing additional energy or changing the membrane structure to allow osmoregulation in relevant organs, such as the gills. Steroid hormone biosynthesis and the phosphonate and phosphinate metabolism pathways were also involved in the adaptation of L. vannamei to low salinity, and the differential expression patterns of 20 randomly selected genes were validated by quantitative real-time PCR (qPCR). This study is the first report on the long-term adaptive transcriptomic response of L. vannamei to low salinity, and the results will further our understanding of the mechanisms underlying osmoregulation in euryhaline crustaceans.

No MeSH data available.