Hepatopancreatic metabolomics shedding light on the mechanism underlying unsynchronized growth in giant freshwater prawn, Macrobrachium rosenbergii

Comparative Transcriptome Analysis of Hepatopancreas Reveals Sexual Dimorphic Response to Methyl Farnesoate Injection in Litopenaeus vannamei

Sexually dimorphic traits such as growth and body size are often found in various crustaceans. Methyl farnesoate (MF), the main active form of sesquiterpenoid hormone in crustaceans, plays vital roles in the regulation of their molting and reproduction. However, understanding on the sex differences in their hormonal regulation is limited. Here, we carried out a comprehensive investigation on sexual dimorphic responses to MF in the hepatopancreas of the most dominant aquacultural crustacean-the white-leg shrimp (Litopenaeus vannamei). Through comparative transcriptomic analysis of the main MF target tissue (hepatopancreas) from both female and male L. vannamei, two sets of sex-specific and four sets of sex-dose-specific differentially expressed transcripts (DETs) were identified after different doses of MF injection. Functional analysis of DETs showed that the male-specific DETs were mainly related to sugar and lipid metabolism, of which multiple chitinases were significantly up-regulated. In contrast, the female-specific DETs were mainly related to miRNA processing and immune responses. Further co-expression network analysis revealed 8 sex-specific response modules and 55 key regulatory transcripts, of which several key transcripts of genes related to energy metabolism and immune responses were identified, such as arginine kinase, tropomyosin, elongation of very long chain fatty acids protein 6, thioredoxin reductase, cysteine dioxygenase, lysosomal acid lipase, estradiol 17-beta-dehydrogenase 8, and sodium/potassium-transporting ATPase subunit alpha. Altogether, our study demonstrates the sex differences in the hormonal regulatory networks of L. vannamei, providing new insights into the molecular basis of MF regulatory mechanisms and sex dimorphism in prawn aquaculture.

Transcriptomics-based analysis of Macrobrachium rosenbergii growth retardation

Macrobrachium rosenbergii is an economically important crustacean in many parts of the world, but in recent years, growth retardation has become an increasingly serious issue. While the underlying causes remain unclear, this has inevitably impacted on aquaculture and production outputs. In this study, gill, hepatopancreas, and muscle tissue samples from M. rosenbergii, with distinct growth differences, underwent transcriptome sequencing and bioinformatics analyses using high-throughput sequencing. In total, 59,796 unigenes were annotated. Differential expression analyses showed that the most differentially expressed genes (DEGs) were screened in gill tissue (1790 DEGs). In muscle and hepatopancreas tissues, 696 and 598 DEGs were screened, respectively. These DEGs were annotated to Kyoto Encyclopedia of Genes and Genomes pathways, which identified several significantly enriched pathways related to growth metabolism, such as PI3K-AKT, glycolysis/gluconeogenesis, and starch and sucrose metabolism. These results suggest that low growth metabolism levels may be one cause of M. rosenbergii growth retardation. Our data provide support for further investigations into the causes and molecular mechanisms underpinning growth retardation in M. rosenbergii.

Transcriptome analysis reveal the effect of freshwater sediments containing 2,3,7,8-tetrachlorodibenzo-p-dioxin on the Macrobrachium rosenbergii hepatopancreas, intestine, and muscle

This research evaluated the hepatopancreas, intestine, and muscle transcriptome alternation of Macrobrachium rosenbergii, and to confirm the relative glycerophospholipid, cytochrome P450 system, and fatty acid metabolism gene expression in sediments containing 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) of 60 ng/sediment (g) and 700 ng/sediment (g) for 90 days of culture. Transcriptome analysis revealed that the TCDD sediment affected the hepatopancreatic metabolism of xenobiotics in M. rosenbergii via the cytochrome P450 system, drug metabolism-other enzymes, drug metabolism-cytochrome P450, chemical carcinogenesis, and lysosome function. Intestinal analysis also showed a similar phenomenon, but this finding was not observed in the muscle tissue. qPCR analysis indicated that the expression levels of APTG4, LPGAT1, ACHE, GPX4, ECHS1, ATP5B, FABP, and ACC in the hepatopancreatic and intestinal tissues decreased, but those in the muscle tissues did not. In summary, TCDD sediment induced tissue metabolism, especially in the hepatopancreas and intestine. TCDD sediment mainly affected the digestive enzyme gene expression with concentration. These results indicated that the presence of TCDD in the sediment played a major role in the hepatopancreatic and intestinal metabolism system of M. rosenbergii.

Effect of Two Kinds of Fertilizers on Growth and Rhizosphere Soil Properties of Bayberry with Decline Disease

Decline disease causes severe damage to bayberry. However, the cause of this disease remains unclear. Interestingly, our previous studies found that the disease severity is related with the level of soil fertilizer. This study aims to explore the effect and mechanism of compound fertilizer (CF) and bio-organic fertilizer (OF) in this disease by investigating the vegetative growth, fruit characters, soil property, rhizosphere microflora and metabolites. Results indicated that compared with the disease control, CF and OF exhibited differential effect in plant healthy and soil quality, together with the increase in relative abundance of Burkholderia and Mortierella, and the reduction in that of Rhizomicrobium and Acidibacter, Trichoderma, and Cladophialophora reduced. The relative abundance of Geminibasidium were increased by CF (251.79%) but reduced by OF (13.99%). In general, the composition of bacterial and fungal communities in rhizosphere soil was affected significantly at genus level by exchangeable calcium, available phosphorus, and exchangeable magnesium, while the former two variables had a greater influence in bacterial communities than fungal communities. Analysis of GC-MS metabonomics indicated that compared to the disease control, CF and OF significantly changed the contents of 31 and 45 metabolites, respectively, while both fertilizers changed C5-branched dibasic acid, galactose, and pyrimidine metabolic pathway. Furthermore, a significant correlation was observed at the phylum, order and genus levels between microbial groups and secondary metabolites of bayberry rhizosphere soil. In summary, the results provide a new way for rejuvenation of this diseased bayberry trees.