Evolution and origin of the chemical composition of radiolarian test during geologic time scale

用光学显微镜、扫描电子显微镜和透射电子显微镜观察了多胱氨酸放射虫的繁殖群。虫体细胞长约8微米，呈梨形，圆锥形末端有两根鞭毛。细胞质中有脂滴和典型的空泡包裹的SrSO4晶体。生殖类群的形态特征和分子系统发育显示出放射虫的祖先特征；棘类和多囊类有共同的祖先。利用天然材料和培养材料描述了从多胱氨酸放射虫中分离到的共生甲藻。在培养过程中获得的运动细胞具有非装甲性质，其特征表明为裸子藻。我们的结果表明，放射虫中至少存在两种甲藻共生体，它们可能自19世纪以来就被报道为“Zooxanthella nutrilla”。

Reproductive swarmers of the polycystine radiolarians were examined using light, scanning and transmission electron microscopy. The swarmer cells were about 8um in length with a pear-like shape and a conical end with two flagella. Lipid droplets and characteristically a vacuole-bound SrSO4 crystal were present in the cytoplasm. The morphological features and molecular phylogeny of the reproductive swarmers show evidence of ancestral traits of radiolarians; acantharians and polycystines have a common ancestry. Symbiotic dinoflagellate isolated from polycystine radiolarians was described using both natural and cultured materials. Motile cells were obtained in culture showed unarmored nature and the characteristics suggested it as Gymnodinium. Our results suggest that at least two dinoflagellate symbiont species existed in the radiolarians and they have been possibly reported as "Zooxanthella nutricula" since the 19th century.