Studies On The Morphology And The Cortical Pigment Granules Of A Hypotrichous Ciliate, Trichototaxis Songi

Most of the protozoas are colourless, excpt that there are some of the spieces have symbiont of bacterias, algae, and other microorganisms, and some of the spieces have cortical pigment granules, which result to certain kind of colour. In the coloured protozoas, some of them have been studied such as flagellates, amoebae, and paramecia. while the comparatively superior spieces of the hypotrichous ciliate have not got a detail research. We only know some description of the morphology about the cortical pigment granules. But the reason why the cortical pigment granule which is involved in the color of the cell can remain unchanged after many generations, the exact positions where the cortical granule exist, and the connection between the cortical granules' heredity and the cell' living are still unknown yet. So it is quite important to know more about the cortical pigment granules during the cell morphogenesis.It was lucky to collect a reddish hypotrichous ciliate Trichototaxis songi from Shanghai. The red colour of Trichototaxis songi have not been changed after two years culture. The cellular morphology and cortical pigment granules were investigated by using differential interference contrast microscopy, scanning electron microscopy, transmission electron microscopy and Feulgen staining. The results are as follows:1,cell morphologyTrichototaxis songi has two typical mid ventral rows, one right marginal row, 1-4 left marginal rows, 3-5 dorsal bristles and about 100 macronucleus. Different from other urostylidae, macronucleus of Trichototaxis songi do not not fuse to be a big macronucleus during the morphogenesis. Instead, each macronuclear nodule divides individually, this is identical to pseudokeronopsis. Maybe the cilatures can not give a right copy of the parental one that result in the difference in cell morphology. Both of these proved Trichototaxis songi to be a transitional species in hypotrichous ciliate. To know more about this is of great significance to the diversity of cell structure and the heredity of the coloured ciliates.Two types of cortical granules were observed by using differential interference contrast microscopy. One is red pigment granule while the other is colorless. The red pigment granules distribute mainly near the ciliatures in ventral and dorsal cortex to form "(?)"and rose garland. But in other area of the cortex, the red pigment granules and the colourless granules distribute disorderly. by using scanning electron microscopy, it was found that the distributing characteristics in the surface of the cortex are the same with the result by using differential interference contrast microscopy, but the quantity of the pigment granules decerased relatively. The result by transmission electron microscopy shows that there are a lot of high electron density granules which are the same big as the pigment granules beneath the cortex and in the cytoplasm. So we could conclude from these the pigment granules exist mainly near the ciliatures beneath the cortex and its surface.Moreover, during the prosses of morphogenesis. the old pigment granules regularly along the ciliatures disappeared gradually, while the new pigment granules rearranged near new cilatures. During this period , the pigment granules seem to divide and the distribution of the pigment granules in proter and opisthe return to the same as before. Furthermore, by transmission electron microscopy, we also found the high electron density granules surrounded by membranes changed from ellipse to columniform, and then give birth to several eye-spot structure in the columniform, after that release several oval granules with eye-spot structure. At last the eye-spot structur disappear and return to several high electron density granules. From the periodically change of these pigment granules , we could confer that the reason why the cells can remain red in color after many generations is that the red pigment granules could divide and increase in number to pass down to the new generation.According to the results above, it could be concluded that these pigment granules are basic components of the cortical structure and are closely related to the function of ciliatures. So, it can be inferred that the pigment granules might function as a bacterial symbiont of the ciliates both inside and outside of the cortex. The related content have not been researched in and out abroad. So it is necessary to separate the pigment granules and combine molecular biology method, to give a further research about the fuction of the pigment granules and its relationship with the ciliate.