Isobaric Tags for Relative and Absolute Quantitation-Based Proteomics Analysis Provides a New Perspective Into Unsynchronized Growth in Kuruma Shrimp (Marsupenaeus japonicus)

Unsynchronized growth is a common phenomenon in farmed crustaceans. The underlying molecular mechanism of unsynchronized growth of crustaceans is unclear. In this study, a comparative proteomic analysis focusing on growth differences was performed using kuruma shrimp Marsupenaeus japonicus, an economic crustacean species, as the model. The study analyzed kuruma shrimp at fast growth stage and steady growth stage from both fast growth group and slow growth group by an Isobaric tags for relative and absolute quantitation (iTRAQ)-based quantitative proteomic analysis method. A total of 1,720 proteins, including 12,291 peptides, were identified. Fifty-two and 70 differentially expressed proteins (DEPs) were identified in the fast growth stage and steady growth stage, respectively. Interestingly, 10 DEPs, including 14-3-3-epsilon-like, GPI, GPD1, MHC-1a, and MHC-1b, were presented in both growth stages. In addition, all these 10 DEPs shared the same expression tendency at these two growth stages. The results indicated that these 10 DEPs are potential growth biomarkers of M. japonicus. Proteins associated with faster growth of M. japonicus may promote cell growth and inhibit cell apoptosis through the Hippo signaling pathway. The fast growth group of M. japonicus may also achieve growth superiority by activating multiple related metabolic pathways, including glycolysis, glycerophospholipid metabolism and Citrate cycle. The present study provides a new perspective to explore the molecular mechanism of unsynchronized growth in crustacean species.

Genome and transcriptome assemblies of the kuruma shrimp, Marsupenaeus japonicus

The kuruma shrimp Marsupenaeus japonicus (order Decapoda, family Penaeidae) is an economically important crustacean that occurs in shallow, warm seas across the Indo-Pacific. Here, using a combination of Illumina and Oxford Nanopore Technologies platforms, we produced a draft genome assembly of M. japonicus (1.70 Gbp; 18,210 scaffolds; scaffold N50=234.9 kbp; 34.38% GC, 93.4% BUSCO completeness) and a complete mitochondrial genome sequence (15,969 bp). As with other penaeid shrimp genomes, the M. japonicus genome is extremely rich in simple repeats, which occupies 27.4% of the assembly. A total of 26,381 protein-coding gene models (94.7% BUSCO completeness) were predicted, of which 18,005 genes (68.2%) were assigned functional description by at least one method. We also produced an Illumina-based transcriptome shotgun assembly (40,991 entries; 93.0% BUSCO completeness) and a PacBio Iso-Seq transcriptome assembly (25,415 entries; 67.5% BUSCO completeness). We envision that the M. japonicus genome and transcriptome assemblies will serve as useful resources for the basic research, fisheries management, and breeding programs of M. japonicus.

Anti-lipopolysaccharide factor D from kuruma shrimp exhibits antiviral activity

Anti-lipopolysaccharide factors (ALFs) exhibit a potent antimicrobial activity against a broad range of bacteria, filamentous fungi, and viruses. In previous reports, seven groups of ALFs (groups A–G) were identified in penaeid shrimp. Among them, group D showed negative net charges and weak antimicrobial activity. Whether this group has antiviral function is not clear. In this study, the ALF sequences of penaeid shrimp were analyzed, and eight groups of ALF family (groups A–H) were identified. The four ALFs including MjALF-C2, MjALF-D1, MjALF-D2, and MjALF-E2 from kuruma shrimp Marsupenaeus japonicus were expressed recombinantly in Escherichia coli, and the antiviral activity was screened via injection of purified recombinant ALFs into shrimp following white spot syndrome virus (WSSV) infection. Results showed that the expression of Vp28 (WSSV envelope protein) decreased significantly in the MjALF-D2-injected shrimp only. Therefore, MjALF-D2 was chosen for further study. Expression pattern analysis showed that MjAlf-D2 was upregulated in shrimp challenged by WSSV. The WSSV replication was detected in RNA, genomic DNA, and protein levels using VP28 and Ie1 (immediate-early gene of WSSV) as indicators in MjALF-D2-injected shrimp following WSSV infection. Results showed that WSSV replication was significantly inhibited compared with that in the rTRX- or PBS-injected control groups. After knockdown of MjAlf-D2 in shrimp by RNA interference, the WSSV replication increased significantly in the shrimp. All these results suggested that MjALF-D2 has an antiviral function in shrimp immunity, and the recombinant ALF-D2 has a potential application for viral disease control in shrimp aquaculture.