Analysis of the distribution of ingested bacteria in nanoflagellates and estimation of grazing rates with flow cytometry
Analysis of the distribution of ingested bacteria in nanoflagellates and estimation of grazing rates with flow cytometry
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DOI：
10.3354/ame021001
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发表时间：
2000-02-21
影响因子：
1.4
通讯作者：
Taub, SR
中科院分区：
文献类型：
--
作者：
Bratvold, D;Srienc, F;Taub, SR
评估了纳鞭毛虫中摄食细菌的分布，以提示是否存在不同放牧率的食草动物亚群。将几种离散随机分布与食入荧光标记细菌（FLB）在鼻舌单胞菌和残留副葡萄球菌培养中的分布进行了比较。样本分布通常适合带额外零的泊松（泊松EZ，作为截断泊松进行测试）和负二项分布，但只偶尔适合泊松。泊松分布和负二项分布表明，该种群是由不同放牧率的鞭毛虫亚群组成的异质种群。虽然这些模型提供了可接受的数学描述，但它们在鞭毛虫亚群数量方面的具体生物学意义仍有待证实。在将被摄食猎物的分布拟合到泊松EZ的基础上，提出了一种快速估计食食率的细胞计数方法。该方法使用在短孵育期间（约15分钟）食草动物不摄入FLB的概率变化来估计泊松参数和额外零的分数，由此计算平均食草率。显微镜和细胞术测定的放牧率相似。食草动物荧光微球细胞直方图的频率分布表明，泊松EZ模型和负二项模型都是对更复杂的放牧率分布的简化。
The distribution of ingested bacteria in nanoflagellates was assessed to suggest whether or not there are subgroups of grazers with different grazing rates. Several discrete random distributions were compared to the distribution of ingested fluorescently labeled bacteria (FLB) in cultures of Rhynchomonas nasuta and Paraphysomonas vestita. Sample distributions typically fit both the Poisson with extra zeros (Poisson EZ, tested as a truncated Poisson) and negative binomial, but only occasionally fit a Poisson. Both the Poisson EZ and the negative binomial distributions suggest a heterogeneous population composed of subgroups of flagellates with different grazing rates. Although these models provide acceptable mathematical descriptions, their specific biological implications with regard to the number of flagellate subgroups remain to be proven. Based on fit of the distribution of ingested prey to a Poisson EZ, a rapid cytometric method for estimation of grazing rates on FLB is presented. The method uses changes in the probability of grazers not ingesting FLB during short incubations (ca 15 min) to estimate the Poisson parameter and the fraction of extra zeros, from which the average grazing rate is calculated. Grazing rates determined by microscopy and by this cytometry method were similar. Frequency distributions of cytometric histograms of fluorescent microspheres in grazers suggest that both the Poisson EZ and negative binomial models are simplifications of a more complex distribution of grazing rates.