Trying to cultivation of Dinophysis caudata (Dinophyceae) and the appearance of small cells
2003
Nishitani, G. (Kyoto Univ. (Japan)) | Miyamura, K. | Imai, I.
Abstract: Dinophysis species have been reported to be involved in DSP incidents but the biology of these mixotrophic dinoflagellates is poorly understood due to unsuccessful attempts at cultivation. In this report, we attempted the cultivation of D. caudata obtained from Ogamae Bay (Oita prefecture, Japan) with certain kinds of organisms as food. The organisms were three phytoplankton species (Thalassiosira sp., Chroomonas sp. and an eukaryotic picophytoplankton), and these cells were crushed by ultrasonic treatment and frozen (-30 deg C). As a result, the addition of food was apparently effective for D. caudata growth. D. caudata continued to grow by binary fission until 22 days after the inoculation and increases in cell numbers were especially seen after the food was added. The largest number of D. caudate cells obtained from a single cell was 28, and we could keep them alive for at least 2 months. In the succeeding scale-up cultivation, all D. caudata cells were transferred from a 1-ml culture in the well of a microplate to a 10-ml culture medium in an Erlenmeyer flask. In one case, D. caudata cells were filled with dense plasmatic contents in spite of 46 days of incubation, and the size and shape were the same as for normal natural cells. In the other case of flask cultivation, small cells of D. caudata (D. diegensis-like cells and D. diegensis-like small cells) appeared, and one of them had two trailing flagella. The appearance of these small cells fn the culture of D. caudata clearly indicates that they are each form of D. caudata and cannot be considered separate species.
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