Jie Qi | PubMed Health

PubMed2026

Antibacterial mechanisms and pathogen-dependent protective effects of the golden pompano LEAP2-derived peptide TroLEAP2-21.

Antimicrobial peptides (AMPs) are essential components of the innate immune system, with liver-expressed antimicrobial peptide 2 (LEAP2) playing a pivotal role in fish immunity. This study investigated the antimicrobial activity and mechanisms of TroLEAP2-21, a 21-amino-acid short peptide from golden pompano (Trachinotus ovatus), against Gram-positive (Lactococcus garvieae, Staphylococcus epidermidis) and Gram-negative (Vibrio alginolyticus, Vibrio harveyi) bacteria. The predicted three-dimensional structure and helical wheel projection of TroLEAP2-21 suggested typical AMP-like physicochemical features. troleap2 expression in the liver and intestine of T. ovatus was significantly upregulated post L. garvieae or V. harveyi infection, suggesting its potential involvement in antibacterial defense. In vitro, TroLEAP2-21 exhibited antibacterial activity against the tested bacterial strains, with membrane disruption, increased membrane permeability, cytoplasmic leakage, and membrane depolarization observed after peptide treatment. Gel retardation assays further indicated species-dependent association of TroLEAP2-21 with bacterial genomic DNA. In vivo, under the tested intraperitoneal injection conditions, TroLEAP2-21 was associated with improved survival and reduced tissue damage in V. harveyi-infected T. ovatus, whereas no significant survival benefit was observed against L. garvieae. Transcriptomic analysis at 48 h post-infection showed transcriptional changes in immune-related DEGs (rsad2, mx1/mx2, il-8) and enrichment of TLR and Jak-STAT signaling pathways at the transcriptional level in peptide-treated fish. FISH showed the tissue localization of tnf-α and nf-κb transcripts and revealed treatment-associated changes in fluorescence signals, and qRT-PCR of eight immune genes supported transcriptomic results in tissues at 48 h post-infection. Collectively, these findings characterize TroLEAP2-21 as a short LEAP2-derived peptide with antibacterial and immunomodulatory activities. Its comparative advantages over other LEAP2-related peptides and its practical application potential remain to be further investigated.

AMPs↗

PubMed2026

Exploratory identification and cellular functional characterization of ppiabl as a candidate gene associated with growth traits in Paralichthys olivaceus.

The Japanese flounder (Paralichthys olivaceus) is an important mariculture species. However, the genetic mechanisms underlying its growth traits remain poorly understood. To explore the genetic basis of growth variation, whole-genome resequencing was performed in a cultured cohort of 60 individuals, followed by exploratory genome-wide association analysis and candidate-gene prioritization. The results revealed heritability estimates of 0.40 for body weight and 0.24 for body length, with substantial overlap in associated loci between the two traits. Exploratory association and variant-annotation analyses prioritized ppiabl, which carries a nonconservative missense variant, as a candidate gene for further investigation. Tissue expression analysis showed that ppiabl was highly expressed in muscle tissue. This gene encodes a protein belonging to the conserved peptidyl-prolyl cis-trans isomerase family. In Japanese flounder primary muscle cells, ppiabl knockdown was associated with altered expression of growth-related genes and an increased G1-phase fraction, whereas overexpression produced changes in the opposite direction. In line with this, fast-growing individuals were found to have significantly larger muscle fiber areas than slow-growing ones. These findings suggest that ppiabl may be involved in muscle-related cellular processes associated with growth variation in Japanese flounder, although its contribution to whole-animal growth requires further validation. Overall, this exploratory study prioritizes ppiabl as a candidate gene potentially associated with growth-related cellular processes in Japanese flounder, although validation in larger independent populations and in vivo models is required.

Animals↗