In the absence of O2, the step-up photophobic response of Blepharisma japonicum is suppressed. To evaluate the possibility that reactivated oxygen species (ROS) produced by blepharismin photosensitization are involved in the primary transduction for the step-up photophobic response of B. japonicum, the effects of OH radical scavengers and the singlet oxygen quencher on the photophobic response were examined. The reagents used in the present assays hardly suppressed the step-up photophobic response, even though OH radical scavengers were rescued from the photodynamic killing of the cells. Alternatively, in the presence of an electron acceptor, the latency of the step-up photophobic response was prolonged. In addition,
oxyblepharismin fluorescence was quenched slightly in the presence of free amino acids. These results
support a hypothesis proposed by Lenci’s research group, that electron transfer from the first excited singlet
state of blepharismin (or oxyblepharismin) to associated proteins may be involved in the primary
phototransduction for the step-up photophobic response.
The oligomannose-coated liposome (OML) vaccine is known to induce cellular immunity specific for the encapsulated antigen in immunized mice. In the present study, we preliminarily evaluated the effect of the OML vaccine encapsulating the soluble protozoan lysate of Toxoplasma gondii, Trypanosoma brucei gambiense, or Babesia rodhaini on the corresponding protozoan infections in mice. After the challenge of T. gondii, the OML vaccine group avoided the high mortality resulting from acute infection that was dominantly observed in other control groups. During the infectious course, the development of the T. gondii-specific antibody, which is an indicator of humoral immunity, was constantly controlled at a lower level in the surviving mice of the OML vaccine group than in other lethally affected mice. On the other hand, other OML vaccines targeting for T. b. gambiense and B. rodhaini did not show any effect on these lethal infections in mice. The present preliminary study suggests that OML is a novel vaccine tool, at least for the control of acute toxoplasmosis.
Meliae cortex (Melia azedarach Linne. var. japonica Makino, M. toosendan Siebold & Zucc) is one of the herbs used in oriental medicine for the treatment of various types of vaginitis. The present study was performed to examine the effects of Meliae cortex extracts on the growth and fine structure of Trichomonas vaginalis (T. vaginalis).
Meliae cortex dose-dependently reduced the viability of T. vaginalis. In the electron microscopy study, we also observed the ultrastructural changes of T. vaginalis following the treatment with Meliae cortex. One to two hours after the addition of the extract of Meliae cortex, the movement of flagella and axostyle decreased, but the cell death did not occur. The fine structure of the cytoplasm was changed 30 min to 2 hour after the treatment of the extract of Meliae cortex. The number of polyribosome decreased, whereas the number of single ribosomes in the cytoplasm increased.
These results indicate that Meliae cortex has the antiprotozoal effects on T. vaginalis cells through the inhibition of cell multiplication as well as the impairment of protein synthesis.
With the hypothesis that African trypanosomes could have in vivo specific genes for adaptation to host’s
environment, the present study was conducted by using suppressive subtractive hybridization (SSH)
technique to seek the highly expressed genes especially in host. A total of 328 clones from the in vivo SSH
library and that of 160 clones from the in vitro SSH library were analyzed in order to determine their
expression levels, but none of the above-mentioned genes showed differential expression. This indicates that
no trypanosome genes could be differentially expressed either the in vivo or in vitro propagated
trypanosomes. Alternatively, there might be limitation for detecting specifically expressed genes in African
trypanosomes using this method, because of their polycistronic gene expression.