Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada.
Bamfield Marine Sciences Centre, Bamfield, British Columbia, Canada.
PLoS One. 2019 Apr 5;14(4):e0215027. doi: 10.1371/journal.pone.0215027. eCollection 2019.
Hagfishes are living representatives of the earliest-diverging vertebrates and are thus useful for the study of early vertebrate physiology. It has been previously postulated that digestive enzymes account for the majority of digestion because hagfish are agastric with notable zymogen granules in specialized cells of the hindgut. While the presence of some digestive enzymes (amylase, lipase and leucinaminopeptidase) have been confirmed with histochemistry, quantification of enzymatic activity is limited. This study sought to biochemically quantify the tissue activity of six digestive enzymes (α-amylase, maltase, lipase, trypsin, aminopeptidase and alkaline phosphatase) along the length of the Pacific hagfish (Eptatretus stoutii) alimentary canal. In addition, the effect of feeding on the rate of enzyme activity was examined. Overall, maltase and trypsin activities were unchanging with respect to location or feeding status, while the activities of α-amylase and alkaline phosphatase decreased substantially following feeding, but were consistent along the length. Lipase and aminopeptidase activities were elevated in the anterior region of the alimentary canal in comparison to the more posterior regions, but were not altered with feeding. This study indicates hagfish have an assortment of digestive enzymes that likely are the result of a varied diet. The differential expression of these enzymes along the tract and in regards to feeding may be indications of early compartmentalization of digestive function.
盲鳗是最早分化的脊椎动物的活代表，因此对于研究早期脊椎动物生理学很有用。先前有人假设消化酶占消化的大部分，因为盲鳗没有胃，在后肠的特殊细胞中有明显的酶原颗粒。虽然已经通过组织化学证实了一些消化酶（淀粉酶、脂肪酶和亮氨酰肽酶）的存在，但酶活性的定量仍然有限。本研究旨在从生物化学角度定量测定太平洋盲鳗（Eptatretus stoutii）消化道沿程的六种消化酶（α-淀粉酶、麦芽糖酶、脂肪酶、胰蛋白酶、氨肽酶和碱性磷酸酶）的组织活性。此外，还研究了摄食对酶活性速率的影响。总的来说，麦芽糖酶和胰蛋白酶的活性与位置或摄食状态无关，而α-淀粉酶和碱性磷酸酶的活性在摄食后显著下降，但在整个消化道中保持一致。与后肠相比，脂肪酶和氨肽酶在前肠区域的活性更高，但摄食不会改变其活性。本研究表明盲鳗拥有多种消化酶，可能是由于其饮食多样化所致。这些酶在消化道中的差异表达以及摄食状态的差异可能表明消化功能的早期分隔。
