Department of Life Science, National Taiwan University, Taipei, Taiwan.
Institute of Cellular and Organismic Biology, Academia Sinica, Nankang, Taipei, Taiwan.
PLoS One. 2020 Jul 30;15(7):e0236601. doi: 10.1371/journal.pone.0236601. eCollection 2020.
Omega-3 polyunsaturated fatty acids (n-3 PUFAs), such as eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), exhibit antibacterial and anti-inflammatory activities. Furthermore, diets rich in n-3 PUFAs are known to improve disease resistance and limit pathogen infection in commercial aquaculture fishes. In this study, we examined the effects of transgenic overexpression of n-3 PUFA biosynthesis genes on the physiological response to bacterial infection in tilapia. We first established tilapia strains with single or dual expression of salmon delta-5 desaturase and/or delta-6 desaturase and then challenged the fish with Vibrio vulnificus infection. Interestingly, our data suggest that n-3 PUFA-mediated alterations in gut microbiota may be important in determining disease outcome via effects on immune response of the host. Both liver- and muscle-specific single and dual expression of delta-5 desaturase and delta-6 desaturase resulted in higher n-3 PUFA content in transgenic fish fed with a LO basal diet. The enrichment of n-3 PUFAs in dual-transgenic fish is likely responsible for their improved survival rate and comparatively reduced expression of inflammation- and immune-associated genes after V. vulnificus infection. Gut microbiome analysis further revealed that dual-transgenic tilapia had high gut microbiota diversity, with low levels of inflammation-associated microbiota (i.e., Prevotellaceae). Thus, our findings indicate that dual expression of transgenic delta-5 and delta-6 desaturase in tilapia enhances disease resistance, an effect that is associated with increased levels of n-3 PUFAs and altered gut microbiota composition.
ω-3 多不饱和脂肪酸（n-3PUFAs），如二十碳五烯酸（EPA）和二十二碳六烯酸（DHA），具有抗菌和抗炎活性。此外，富含 n-3PUFAs 的饮食被认为可以提高商业水产养殖鱼类的疾病抵抗力并限制病原体感染。在这项研究中，我们研究了 n-3PUFA 生物合成基因的转基因过表达对罗非鱼细菌感染生理反应的影响。我们首先建立了单或双表达三文鱼 δ-5 去饱和酶和/或 δ-6 去饱和酶的罗非鱼品系，然后用创伤弧菌感染这些鱼。有趣的是，我们的数据表明，n-3PUFA 介导的肠道微生物群的改变可能通过对宿主免疫反应的影响在决定疾病结果方面很重要。肝和肌肉特异性的单和双表达 δ-5 去饱和酶和 δ-6 去饱和酶导致用 LO 基础饲料喂养的转基因鱼中 n-3PUFA 含量更高。双转基因鱼中 n-3PUFAs 的富集可能是其生存率提高和创伤弧菌感染后炎症和免疫相关基因表达降低的原因。肠道微生物组分析进一步表明，双转基因罗非鱼具有较高的肠道微生物组多样性，炎症相关微生物组（即普雷沃氏菌科）水平较低。因此，我们的研究结果表明，在罗非鱼中双表达转基因 δ-5 和 δ-6 去饱和酶可增强疾病抵抗力，这种作用与 n-3PUFAs 水平升高和肠道微生物组组成改变有关。
