At least 7 proteorhodopsin sequences of Oxyrrhis marina were recently proven in bands obtained by sucrose density gradient centrifugation, and MS analyses revealed that the bands consisted almost of pure, native proteorhodopsins (Rhiel et al. 2020). The proteorhodopsin fractions, i.e., bands B2, B3, and B4 were subjected to transmission electron microscopy. Negative staining revealed that band B2 consisted most likely of monomeric/oligomeric proteorhodopsins with particle dimensions of about 6 nm. Negative staining, freeze-fracture, and cryo-transmission electron microscopy revealed that bands B3 and B4 consisted of vesicular, sheet-like, and cup-shaped structures which all seemed to be composed of protein. Frequently, ring-like protein aggregates were registered at higher magnifications. They measured about 4 nm in diameter with a tiny hole of 1.5 nm in the middle. The bands B2, B3, and B4 were pooled and used to raise an antiserum. Immunoelectron microscopy resulted in intense labeling of the isolated structures. Immunofluorescence light microscopy of formaldehyde-fixed Oxyrrhis cells resulted in intense labeling of the cell periphery. Some cell internal structures became labeled, too. Immunoelectron microscopy of freeze-fractured cells revealed that most likely the membranes of the amphiesmal vesicles were labeled at the cell periphery, while the cell internal label seemed to originate from the food vacuoles.

中文翻译：

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甲藻 Oxyrrhis marina 的原视紫红质：超微结构和免疫荧光光学显微镜和免疫电子显微镜定位

最近在通过蔗糖密度梯度离心获得的条带中证明了 Oxyrrhis marina 的至少 7 个蛋白视紫红质序列，并且 MS 分析显示这些条带几乎由纯天然蛋白视紫红质组成（Rhiel 等人，2020 年）。视紫红质蛋白组分，即条带 B2、B3 和 B4 进行透射电子显微镜检查。阴性染色显示条带 B2 最有可能由颗粒尺寸约为 6 nm 的单体/寡聚视紫红质组成。阴性染色、冷冻断裂和冷冻透射电子显微镜显示，B3 和 B4 条带由囊状、片状和杯状结构组成，这些结构似乎都由蛋白质组成。通常，环状蛋白质聚集体在更高的放大倍数下被记录。他们测量出直径约为 4 nm，有一个 1 的小孔。中间 5 纳米。条带 B2、B3 和 B4 被合并并用于产生抗血清。免疫电子显微镜导致分离结构的强烈标记。甲醛固定的 Oxyrrhis 细胞的免疫荧光光学显微镜导致细胞外围的强烈标记。一些细胞内部结构也被标记了。冷冻破裂细胞的免疫电子显微镜显示，两性囊泡的膜很可能在细胞外围被标记，而细胞内部标记似乎来自食物液泡。甲醛固定的 Oxyrrhis 细胞的免疫荧光光学显微镜导致细胞外围的强烈标记。一些细胞内部结构也被标记了。冷冻破裂细胞的免疫电子显微镜显示，两性囊泡的膜很可能在细胞外围被标记，而细胞内部标记似乎来自食物液泡。甲醛固定的 Oxyrrhis 细胞的免疫荧光光学显微镜导致细胞外围的强烈标记。一些细胞内部结构也被标记了。冷冻破裂细胞的免疫电子显微镜显示，两性囊泡的膜很可能在细胞外围被标记，而细胞内部标记似乎来自食物液泡。