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为了探究中国林蛙(Rana chensinensis)哈蟆油最佳采收期,为养殖和采收提供依据,以吉林省靖宇县3龄雌性中国林蛙为研究对象,建立了哈蟆油PUFAs含量测定的体外分析方法,采用气相色谱法测定中国林蛙6个生长阶段(出蛰期、产卵期、捕食期、入蛰期、散居冬眠期和群居冬眠期)哈蟆油中的总PUFAs、OA、ALA、AA、EPA和DHA的含量并进行聚类分析; 利用RT-PCR法测定与PUFAs合成相关的FAD基因(Δ6-FAD、Δ5-FAD、Δ9-FAD和n-3系列)的表达量; 利用SPSS 19.0和R 4.0.1分析PUFAs含量与FAD基因表达量的相关性。结果表明:在不同生长阶段中,散居冬眠期的中国林蛙哈蟆油中PUFAs含量及FAD基因表达量最高; OA和EPA的含量与总PUFAs含量具有显著相关性,Δ6-FAD和Δ5-FAD基因的表达量与总PUFAs含量具有显著相关性,这4个指标在哈蟆油采集时期的鉴别及质量评价上具有重要参考价值。

建立气相色谱方法测定同年9个不同生长期中国林蛙皮肤中花生四烯酸(AA)、二十碳五烯酸(EPA)和二十二碳六烯酸(DHA)含量,比较分析其含量差异。采用SPSS 19.0软件对各时期多不饱和脂肪酸(PUFA)含量进行聚类分析,探讨其变化规律,结果表明:9个时期中国林蛙皮肤中PUFA含量可聚为4大类,第一类为时期2018-09-21,第二类为时期2018-09-05,第三类为时期2018-01-08日和2018-04-26,第四类为时期2018-03-08、2018-03-19、2018-04-09、2018-10-18和2018-11-27,即中国林蛙全年不同生长时期皮肤中PUFA含量存在差异,在其深居冬眠期和上岸后捕食生长期时皮肤中PUFA含量总体较高。本文从中国林蛙全年各生长发育时期考察其皮肤组织营养物质含量差异,为进一步利用林蛙皮资源提供有力依据,对改善中国林蛙的养殖条件以及林蛙皮品质最佳期的确定具有重要的指导意义。

为初步了解林蛙油重金属的污染现状,采集东北林蛙、黑龙江林蛙和中国林蛙的林蛙油,以湿法消化法消化,利用荧光比色法测定锡含量、原子吸收法分别检测镉、铬、铜和铅的含量,并采用单因子污染指数及每周可耐受摄入量分别评价5种重金属在3种林蛙油中的污染程度并对其食用安全进行评价。结果表明,该批次样品中东北林蛙蛙油重金属含量分别为锡10～20、镉50～90、铬670～720、铜100～250和铅60～90 μg/kg; 黑龙江林蛙蛙油重金属含量分别为锡12～22、镉80～110、铬700～820、铜150～250和铅80～100 μg/kg; 中国林蛙蛙油重金属含量分别为锡2～10、镉30～60、铬590～700、铜800～130和铅30～60 μg/kg,5种金属分别在3种林蛙油内的含量差异显著。单因子污染指数结果显示3种林蛙油中锡、铅的含量均未超过轻度污染指数; 铬、镉的含量,除中国林蛙蛙油中铬为轻度污染,其余皆为中度污染,根据样本数据可知仅黑龙江林蛙油镉超标40%,其余皆在食品污染物限量国家标准范围之内。根据每周可耐受摄入量评定,其结果显示3种林蛙油的食用风险依次是铬>镉>铜>铅>锡。因此本批次所检测的林蛙油可食性良好,但仍有必要监测林蛙油中镉、铬的含量。

In the current study, 5-nydroxytryptamine （5-HT） and gastrin （GAS） cells in the digestive canals of Rana chensinensis tadpoles at different developmental stages were investigated by immunohistochemistry. Results showed that the 5-HT cells were only detected in the duodenum before metamorphosis began, and were extensively distributed in the stomach, duodenum, small intestine, and rectum thereafter, with the highest counts found in the duodenum and rectum when metamorphosis was completed. The GAS cells were only distributed in the stomach and duodenum, and only rarely detected in the duodenum before metamorphosis began, but increased in the stomach during metamorphosis and showed zonal distribution in the gastric mucosa when metamorphosis was completed. Metamorphosis is a critical period for amphibians, during which structural and functional physiological adaptations are required to transition from aquatic to terrestrial environments. During metamorphosis, the differentiations of 5-HT cells in the gastrointestinal canals of tadpoles could facilitate mucus secretion regulation, improve digestive canal lubrication, and help water- shortage food digestion in terrestrial environments. Conversely, GAS cell differentiations during metamorphosis might contribute to the digestive and absorptive function transition from herbivore to omnivore.