酵母葡聚糖衍生物对凡纳滨对虾血细胞免疫反应的影响

酵母葡聚糖是水产养殖中使用最广泛的免疫增强剂之一，但其不溶解性不利于其免疫增强作用的发挥。为了增加酵母葡聚糖的溶解性，研究共制备了8种酵母葡聚糖衍生物，即4种不同取代度的羧甲基葡聚糖和磺乙基葡聚糖。将葡聚糖和其8种衍生物分别按照5、25和100 g/mL的浓度分别添加到原代培养凡纳滨对虾血细胞的培养液中。以空白血细胞作为对照。孵育6h、12h和24h后分别取样，测定血细胞的酚氧化酶和呼吸暴发活力。结果表明，在6h时，所有葡聚糖衍生物处理组的酚氧化酶活力均显著高于相同浓度下的未衍生葡聚糖处理组（P0.05）。而25 g/mL酵母葡聚糖衍生物处理组的呼吸暴发活力显著高于同浓度未经衍生葡聚糖处理组（P0.05）。在12h时，所有酵母葡聚糖衍生物处理组的酚氧化酶和呼吸暴发活力均显著高于未衍生葡聚糖处理组（P0.05）。在6h和12h时，同浓度各葡聚糖衍生物处理组的血细胞酚氧化酶和呼吸暴发活力并无显著差异（P0.05）。研究结果表明，羧甲基葡聚糖和磺乙基葡聚糖均比未衍生葡聚糖具有更强的免疫促进作用，而且这种免疫促进作用在两种衍生物之间没有显著差异；另一方面，酵母葡聚糖衍生物的免疫促进作用与其使用浓度有关，而与其取代度没有明显的关系。  

THE EFFECTS OF YEAST B-GLUCAN DERIVATIVES ON THE IMMUNE RESPONSES OF THE HAEMOCYTES OF WHITE SHRIMP LITOPENAEUS VANNAMEI

Yeast -glucan is a widely-used immunostimulant in aquaculture. However, the insolubility of -glucan reduces its efficiency as an immunostimulant. In our study, carboxymethylglucan (CMG) and sulfoethylglcuan (SEG) were generated to increase the solubility of -glucan. Both CMG-type and SEG-type of glucans had four derivatives with different degree of substitution (DS), so in total eight kinds of immunostimulants and -glucan as the control were tested in our study. Each immunostimulant was added to the primary culture of the haemocytes of white shrimp Litopenaeus vannamei at different concentrations of 5, 25 and 100 g/mL. With each concentration of every immunostimulant the primary culture was incubated for 6, 12 and 24 hours, before the haemocytes were sampled and their phenoloxidase (PO) activity and respiratory burst (RB) were assayed. After 6 hours, the PO activity of the haemoctyes incubated with all the eight -glucan derivatives was significantly higher than those incubated with -glucan control at the same concentration (P0.05). The RB of the haemocytes incubated with 25 g/mL of all the -glucan derivatives was significantly higher than those incubated with 25 g/mL of -glucan (P0.05). After 12 hours, PO activity and RB of the haemoctyes incubated with all the -glucan derivatives were significantly higher than those with -glucan (P0.05). However, the eight -glucan derivatives showed no significant difference among each other in their effects on the PO activity or RB of the haemoctyes (P0.05). Our study revealed that the immune-enhancing effects of -glucan derivatives were higher than -glucan. However, there was no significant difference in immune-enhancing effects between CMG and SEG. The concentration of -glucan derivatives could significantly influence their immune-enhancing effects, but DS did not affect the immune-enhancing effects of -glucan derivatives.