Identification and Expression Analysis of LncRNAs Reveal the Immune Mechanism of Visceral White-Nodules Disease Resistance in Large Yellow Croaker.

Long non-coding RNAs (lncRNAs) have several known functions in fish growth processes and signal transduction, but their possible roles in response to bacterial diseases remain largely unresolved. In this study, we report a comprehensive cold-water bacterial disease-responsive lncRNA expression profile for understanding the transcriptional regulatory mechanisms of visceral white-nodules disease resistance in large yellow croaker. A total of 2534 high-confidence lncRNAs were identified by a rigorous filtering pipeline as a basic sequence set for comparative transcriptional analysis. In addition, a total of 10,200 lncRNA-mRNA pairs with high correlation coefficients were identified by expressions level correlation analysis, including non-redundant 381 DE lncRNAs and 2590 differential expressed genes. MSTRG_11084_1 and MSTRG_20402_1 were linked to a large number of target genes and may be involved in important functions in immune regulation. We further revealed the conserved and idiosyncratic features of the disease response process between the technical control strain (TCS) and the resistant strain (RS). Immune-related pathways were enriched in GO terms and KEGG pathways, among which cytokine-cytokine receptor interaction, MAPK signaling pathway, and NF-kappa B signaling pathway may play a key role in VWND resistance in large yellow croaker. Protein-protein interaction network (PPI) analysis revealed that immune-related target genes such as il-10, met, acta2, myc, cav1, and ntrk1, as well as growth and metabolism-related target genes such as pik3r2, igf1, sc5d, hmgcr, and lss were considered the main hub genes. This study represents the first characterization of lncRNAs involved in VWND resistance in large yellow croaker and provides new clues for elucidating the disease response mechanism of large yellow croaker.

Tissue-Specific Analysis of Alternative Splicing Events and Differential Isoform Expression in Large Yellow Croaker (Larimichthys crocea) After Cryptocaryon irritans Infection.

The large yellow croaker (Larimichthys crocea) is one of the most important mariculture fish in China. Recently, cryptocaryonosis caused by Cryptocryon irritans infection has brought huge economic losses and threatens the healthy and sustainable development of the L. crocea industry. However, the molecular mechanism and regulation process for L. crocea resistance to C. irritans infection has not been fully researched. Alternative splicing (AS) is an important post-transcriptional regulatory mechanism that allows cells to produce transcriptional and proteomic diversity. The results of AS are tissue dependent, and the expression of tissue-specific transcription subtype genes is determined by AS and transcriptional regulation. However, studies on the tissue specificity of AS events in L. crocea following infection with C. irritans have not been performed. In this study, the L. crocea were artificially infected with C. irritans; their skin and gill were collected at 0 h, 24 h, 48 h, 72 h, and 96 h post infection. After sequencing and differential expression analysis, a set of 452, 692, 934, 711, 534, and 297 differential alternative splicing (DAS) events were identified in 0 h, 12 h, 24 h, 48 h, 72 h, and 96 h post infection respectively. Furthermore, 4160 differentially expressed isoforms (DEIs) and 4209 DEI genes were identified from all time point groups. GO enrichment and pathway analysis indicated that many genes of DAS and DEIs were rich in immune-related GO terms and KEGG pathways, such as the Toll and Imd signaling pathway, NOD-like receptor signaling pathway, TNF signaling pathway, and TNF signaling pathway. Among hub DEI genes, alternative splicing-related genes (cwc25, prpf8, and sf3a3), skin function-related gene (fa2h), and oxygen deprivation-related gene (hyo1) were found in DEI genes. This study provided insight into the temporal change of DAS and DEIs between skin and gill of L. crocea against C. irritans infection and revealed that these differences might play immune-related roles in the infection process.

Chromosome-Level Assembly of the Southern Rock Bream (Oplegnathus fasciatus) Genome Using PacBio and Hi-C Technologies.

The Rock Bream (Oplegnathus fasciatus) is an economically important rocky reef fish of the Northwest Pacific Ocean. In recent years, it has been cultivated as an important edible fish in coastal areas of China. Despite its economic importance, genome-wide adaptions of domesticated O. fasciatus are largely unknown. Here we report a chromosome-level reference genome of female O. fasciatus (from the southern population in the subtropical region) using the PacBio single molecule sequencing technique (SMRT) and High-through chromosome conformation capture (Hi-C) technologies. The genome was assembled into 120 contigs with a total length of 732.95 Mb and a contig N50 length of 27.33 Mb. After chromosome-level scaffolding, 24 chromosomes with a total length of 723.22 Mb were constructed. Moreover, a total of 27,015 protein-coding genes and 5,880 ncRNAs were annotated in the reference genome. This reference genome of O. fasciatus will provide an important resource not only for basic ecological and population genetic studies but also for dissect artificial selection mechanisms in marine aquaculture.

Ultrasensitive electrochemiluminescence immunosensor for 5-hydroxymethylcytosine detection based on Fe3O4@SiO2 nanoparticles and PAMAM dendrimers.

An ultrasensitive sandwiched electrochemiluminescence (ECL) immunosensor was developed for 5-hydroxymethylcytosine (5hmC) detection in genomic DNA by using Fe3O4@SiO2 core-shell magnetic nanomaterial as a immobilization matrix for anti-5hmC antibody, PAMAM conjugated avidin and Ru(bpy)2(phen-5-NH2)(PF6)2 as signal amplification unit. Importantly, Fe3O4@SiO2 nanoparticles were verified to not only possess enormous surface for loading antibody by amido link, but also exhibit excellent bioactivity. With the dual signal amplification strategy, the ECL immunosensor showed wide detection range from 0.1 to 30nM with low detection limit of 0.047nM (S/N = 3). Based on the specific immunoreaction, the developed method also illustrated excellent detection selectivity. The fabricated immunosensor was also applied to detect the 5hmC in genomic DNA of cancer tissue, which indicated that the immunosensor possess potential applications in clinical detection.