Conversion of Retinoids along the Marine Food Chain Contributes to Adverse Impacts on the Spine, Liver, and Intestinal Health of the Marine Medaka (Oryzias melastigma)

Marine microalgae serve as an aquaculture bait. To enhance
algal
cell growth and breeding profits, high-intensity light conditions
are standard for cultivating bait microalgae, potentially altering
microalgal metabolite production. This research revealed that Thalassiosira pseudonana, when subjected to high-intensity
light conditions, accumulated significant quantities of retinal (RAL)
that transferred through the food chain and transformed into all-trans
retinoic acid (atRA) in marine medaka. The study further explored
the toxic effects on individual fish and specific tissues, as well
as the mechanisms behind this toxicity. The accumulation of atRA in
the liver, intestine, and spinal column resulted in structural damage
and tissue inflammation, as well as oxidative stress. It also down-regulated
the gene transcription levels of key pathways involved in immune function
and growth. Furthermore, it disrupted the homeostasis of the intestinal
microbial communities. The implications for wildlife and human health,
which are influenced by the regulation of microalgal metabolite accumulation
and their transfer via the food chain, require further investigation
and could hold broader significance.

海洋微藻是水产养殖的常用饵料。为促进藻类细胞生长并提升养殖收益，高强度光照条件是饵料微藻培育的常规手段，但该条件可能会改变微藻的代谢产物合成。本研究发现，假微型海链藻（Thalassiosira pseudonana）在高强度光照环境下会大量积累视黄醛（RAL），这类物质可通过食物链传递，并在海洋青鳉体内转化为全反式维甲酸（atRA）。本研究进一步探究了该物质对鱼类个体及特定组织的毒性效应，以及此类毒性的作用机制。全反式维甲酸在鱼类肝脏、肠道与脊柱中的积累，会引发组织结构损伤、组织炎症以及氧化应激反应；同时还会下调免疫功能与生长相关关键通路的基因转录水平。此外，该物质还会扰乱肠道微生物群落的稳态。微藻代谢产物的积累及其通过食物链的传递会对野生生物与人类健康产生影响，其背后的关联机制仍需进一步研究，或具备更广泛的研究价值。