不同干露条件单环刺螠的耐受性及对体表黏液特性的影响

Air exposure tolerance and characteristics of surface mucus in echiuran worm Urechis unicinctus in wet sand with and without water

为了研究单环刺螠Urechis unicinctus在不同温度(15、20、25、30℃)的湿沙无水和湿沙有水干露条件下的耐受性、体表黏液分泌量及成分含量的变化,试验采用离心管提取平均体质量为2.75 g的单环刺螠体表黏液,采用苯酚-硫酸法和总蛋白测定试剂盒分别检测黏液中多糖和蛋白质含量,同时研究其黏液对金黄色葡萄球菌Staphylococcus aureus、灿烂弧菌Vibrio splendidus、奇艺变形杆菌Bacillus mirabilis、产气肠杆菌Enterobacter aerogenes、阴沟肠杆菌Aerobacter cloacae、哈维氏弧菌Vibrio harveyi、副溶血弧菌Vibrio parahaemolyticus、鳗弧菌Vibrio anguillarum、藤黄微球菌Micrococcus luteus等常见水产动物病原菌的抗菌性,采用抑菌圈法通过比较抑菌圈直径以判断抗菌效果。结果表明:单环刺螠体表黏液分泌量随温度升高而降低,湿沙无水干露条件下的单环刺螠耐受性要强于湿沙有水;15℃条件下,10只单环刺螠湿沙无水和湿沙有水型分别在1 min(3.33 mL±0.05 mL)和10 min(2.85 mL±0.04 mL)时黏液分泌量较高;湿沙无水条件下多糖(1.04μg/mL±0.10μg/mL)及蛋白质(65.81 mg/mL±2.22 mg/mL)含量均在30 min时最高,且随干露时间的延长均呈先升高后降低的趋势;体表黏液对所测9种病原菌的抑菌圈直径小于10 mm,均无抗菌性。研究表明,2.75 g规格的单环刺螠,在15℃湿沙无水干露条件下耐受性可达48 h以上。

The polysaccharide and protein contents and secretion were detected in surface mucus of echiuran worm Urechis unicinctus with body weight of 2.75 g in a wet sand plastic box with and without water at temperature of 15, 20, 25, and 30 ℃ by phenol-sulfuric acid method and total protein assay kit, and the antibacterial activity of mucus to routine pathogens Staphylococcus aureus, Vibrio splendidus, Bacillus mirabilis, Enterobacter aerogenes, Aerobacter cloacae, V.harveyi, V.parahaemolyticus, V.anguillarum, and Micrococcus luteus in aquatic animals was tested by comparing the diameter of the bacteriostatic zone to evaluate air exposure tolerance and characteristics of surface mucus in echiuran worm in wet sand with and without water. It was found that the surface mucus secretion was decreased with the increase in temperature, and that there was stronger tolerance to air exposure in the echiuran worm in wet sand without water than that in the echiuran worm in wet sand with water, the maximal surface mucus secretion in 10 individuals in 10 min(2.85 mL±0.04 mL) in echiuran worm in wet sand with water and in 1 min(3.33 mL±0.05 mL) in echiuran worm in wet sand without water at 15 ℃. The maximal contents of polysaccharide(1.04 μg/mL±0.10 μg/mL) and protein(65.81 mg/mL±2.22 mg/mL) were observed in 30 min in echiuran worm in wet sand without water, with a tendency of first increase and then decrease. No antimicrobial activity of the mucus to the tested 9 pathogens was found. The findings indicate that the echiuran worm with body weight of 2.75 g can tolerate air exposure for more than 48 hours under the condition of wet sand without water at 15 ℃.