Studies on cellular characteristics and phylogeny of chromistan algae.

这项研究旨在了解极地水域中栖息着的触生植物的混合营养活性。对来自南极和格陵兰的样本进行了检测。结果表明，只有金色假单胞菌、刺金藻和巴拉尼格变种具有混合营养功能，而棕囊藻、拟单胞藻和金色假单胞菌等单细胞不能吸收食物颗粒。由于触生植物的密度很低，极地水样不适合混合营养的检测。因此，使用了大多数从日本沿海水域收集和分离的培养菌株。混合营养摄取率随着食物颗粒(乳胶珠)密度的增加而增加。当浓度超过10~(-7)粒/毫升时，吸光度下降，这是因为在如此高的密度下，在触角线虫表面形成的食物颗粒聚集物大于5微米，这是毛细管藻所能吸收的最大食物颗粒尺寸。在颗粒密度小于10^7(使用0.88um微珠时)的条件下，毛细管藻的清除率为0.07nl/cell/min。这大约是Dinobrion的三倍，Dinobrion是淡水藻类中最常见的成员，能够吸收食物颗粒。此外，还对金针菇不同的食物捕获方法进行了调查。在短毛金龟子、星形金龟子和球茎金龟子中发现了一种新的食物捕获方式，即形成管状结构，捕获食物颗粒并将其吸走。这与已知的其他物种的捕获方法不同，在其他物种中，hirta和C.spinifera的捕获过程涉及到触角线虫。

This study was intended to understand mixotrophic activity of were surveyed for haptophytes inhabiting in polar waters. Samples from Antarctic and Greenland were examined. It was found that only three taxa, Chrysochromulina hirta, C.spinifera and Balaniger sp.were mixotrophic, and other haptophytes such as Phaeocystis, Pappomonas and Chrysochromulina parkeae were not able to uptake food particles. Because density of haptophytes was very low, polar water samples were not suitable for examination of mixotrophy. So, culture strains mostly collected and isolated from Japanese coastal waters were used. Mixotrophic uptake rate increased as density of food particles (latex beads) increased. However, it decreased at the concentration of over 10^7 particles/ml. This was interepreted as that in such high density, the aggregate of food particles formed on the haptonema surface became bigger than 5 mum which was the maximum size of food particle C.hirta could uptake. Clearance rate of C.hirta was 0.07nl/cell/min under the condition that particle density is less than 10^7 (when 0.88 mum beads were used). This is about three times higher than that of Dinobryon, the most common member of freshwater algae that is able to uptake food particles. Variations of methods in food capturing were also surveyed for Chrysochromulina species. New type of food capture was found in C.aff brevifilum, C.asteroplastida sp.nov.and C.strobilus, that is, they form tubular structure and capturing food particle and suck it. This is different from capturing method previously known in other species, C.hirta and C.spinifera, in which the haptonema is involved in the capturing process.