CIMAR/CIIMAR (Interdisciplinary Centre of Marine and Environmental Research), University of Porto, Porto, Portugal.
PLoS One. 2012;7(4):e35138. doi: 10.1371/journal.pone.0035138. Epub 2012 Apr 6.
Although retinoids have been reported to be present and active in vertebrates and invertebrates, the presence of mechanisms for retinoid storage in the form of retinyl esters, a key feature to maintain whole-organism retinoid homeostasis, have been considered to date a vertebrate innovation. Here we demonstrate for the first time the presence of retinol and retinyl esters in an invertebrate lophotrochozoan species, the gastropod mollusk Osilinus lineatus. Furthermore, through a pharmacological approach consisting of intramuscular injections of different retinoid precursors, we also demonstrate that the retinol esterification pathway is active in vivo in this species. Interestingly, retinol and retinyl esters were only detected in males, suggesting a gender-specific role for these compounds in the testis. Females, although lacking detectable levels of retinol or retinyl esters, also have the biochemical capacity to esterify retinol, but at a lower rate than males. The occurrence of retinyl ester storage capacity, together with the presence in males and females of active retinoids, i.e., retinoic acid isomers, indicates that O. lineatus has a well developed retinoid system. Hence, the present data strongly suggest that the capacity to maintain retinoid homeostasis has arisen earlier in Bilateria evolution than previously thought.
尽管已经报道视黄醇及其酯（一种维持整个机体视黄醇稳态的关键物质）在脊椎动物和无脊椎动物中存在并具有活性，但到目前为止，视黄醇酯的储存机制被认为是脊椎动物的创新。在这里，我们首次在一种具有担轮幼虫的软体动物腹足纲动物 Osilinus lineatus 中证明了视黄醇和视黄醇酯的存在。此外，通过肌肉内注射不同视黄醇前体的药理学方法，我们还证明了该物种体内视黄醇酯化途径是活跃的。有趣的是，只有雄性中检测到视黄醇和视黄醇酯，表明这些化合物在睾丸中有性别特异性作用。尽管雌性中没有检测到视黄醇或视黄醇酯，但它们也具有酯化视黄醇的生化能力，但其速度比雄性低。视黄醇酯储存能力的出现，以及雄性和雌性中具有活性的视黄醇，即视黄酸异构体的存在，表明 O. lineatus 具有完善的视黄醇系统。因此，目前的数据强烈表明，维持视黄醇稳态的能力在比以前认为的更早的两侧对称动物进化中出现。
