雌性阿根廷滑柔鱼性腺发育阶段的脂肪酸组成及其变化

Fatty acid composition and its changes during sexual maturation in female Illex argentinus

摘要:

阿根廷滑柔鱼是典型的头足类，资源生物量与其生长发育过程中营养物质积累及生殖投入密切相关。为了获知雌性阿根廷滑柔鱼性腺发育各阶段的脂肪酸组成及其变化特点，研究采用氯仿甲醇法和气相色谱法检测分析胴体、消化腺和卵巢的脂肪酸种类及其含量。结果表明，雌性阿根廷滑柔鱼胴体、消化腺和卵巢3个组织的脂肪酸均以多不饱和脂肪酸（PUFA）为主，饱和脂肪酸（SFA）次之，单不饱和脂肪酸（MUFA）的总含量最低。胴体组织的脂肪酸种类最全面，共检测出28种脂肪酸，消化腺和卵巢分别检测出21种和17种脂肪酸。检测发现3个组织中SFA均以C16∶0脂肪酸最为丰富，MUFA以C18∶1n9c和C20∶1脂肪酸为主，PUFA的DHA （C22∶6n3）最丰富，EPA （C20∶5n3）次之。胴体的SFA和MUFA在成熟期达到最大值，在产卵期显著降低；消化腺的PUFA保持相对稳定水平，但是其含量显著低于胴体和卵巢；卵巢持续积累脂肪酸，在产卵期时MUFA和PUFA显著降低。研究表明，雌性阿根廷滑柔鱼胴体、消化腺和性腺3个组织的脂肪酸种类具有组织特殊性，而主要脂肪酸具有一致性。性腺发育过程中，胴体的SFA和MUFA可能转化为能量供给卵巢发育，消化腺的PUFA则向胴体和卵巢转移，卵巢则持续积累脂肪酸供给卵子发生。

Abstract:

Argentinean short-fin squid, Illex argentinus, is an important Cephalopod species, characterized by fast growth, short lifespan and semelparous reproduction. It has been assumed that the stock biomass is closely related to the nutrients acquisition, accumulation and subsequent allocation to reproduction during the sexual maturation. In order to understand the fatty acid composition and its changes during sexual maturation in female Illex argentinus, the fatty acid profiles and their relative content in multiple tissues, namely mantle tissue, digestive gland and ovary, were investigated by the methods of chloroform-methanol and gas chromatography. The results indicated that the polyunsaturated fatty acids (PUFA) were the most abundant fatty acid class for the tissues investigated, followed by saturated fatty acids (SFA) and monounsaturated fatty acids (MUFA). A total of 28 fatty acid profiles were detected in mantle tissue, while digestive gland and ovary were had 21 fatty acid profiless and 17 fatty acid profiles, respectively. It was found that most of SFA content was presented as C16:0, MUFA content as C18:1n9c and C20:1, and PUFA content as docosahexaenoic acid (DHA; 22:6n3) and eicosapentaenoic acid (EPA; 20:5n3). During the sexual maturation, both SFA content and MUFA content in mantle tissue attained the highest level at mature stage, and then decreased significantly at spawning stage, probably indicating these fatty acids were mobilized to fuel reproduction. PUFA content in digestive gland was significantly lower than that in mantle tissue or ovary, even though it maintained a relatively stable status throughout sexual maturation. The ovary continuously accumulated fatty acid content, but showed a significant decrease in MUFA content and PUFA content during the spawning period, possibly suggesting that these fatty acids were increasingly allocated to oogenesis. These evidence indicated that the fatty acid profiles in Illex argentinus showed tissue-specific characteristics, while the major fatty acid profiles were consistent in mantle tissue, digestive gland and ovary. In the mantle tissue, both SFA and MUFA were possibly mobilized to fuel reproductive growth during sexual maturation. In the digestive gland, the PUFA content might be continuously transferred to mantle and ovary with maturation. Regarding fatty acids in the ovary, the content might be continuously accumulated and subsequently used to support oogenesis during the sexual maturation.