Water borne parasites are ubiquitous protozoan pathogens that affect humans, domestic animals and wildlife throughout the world. From a water perspective, several protozoan parasites are important but till now mostly Giardia and Cryptosporidium have been highlighted as significant waterborne parasitic pathogens. For many years WHO took under consideration the intestinal protozoa and Giardiasis and Cryptosporidiosis are already included into the “Neglected Diseases Initiative”. At least 325 water associated outbreaks of parasitic protozoan diseases have been reported worldwide. Giardia lamblia and Cryptosporidium parvum account for the majority of the outbreaks, since Entamoeba histolytica, Cyclospora cayetanensis, Toxoplasma gondii, Isospora belli, Blastocystis hominis, Balantidium coli, Microsporidia, Acanthamoeba and Naegleria fowleri were responsible for only a small part of the reported outbreaks. This review is intended to provide an overview of the current state of knowledge regarding these medically important parasites, to present results on their prevalence in water supplies and to stimulate research questions on different aspects of their developmental biology and water transmission.
The soil-dwelling social amoeba Dictyostelium discoideum is known to be unusually resistant to oxidative stress. However, little is known about how D. discoideum cells protect themselves from the stress. We found a gene coding for manganese superoxide dismutase (MnSOD) in the database of D. discoideum. The gene, designated sodE, encodes a polypeptide 37% identical to Escherichia coli MnSOD. A plasmid expressing the truncated form of SodE, pSOD5, was constructed to determine whether SodE suppressed E. coli JI132 (sodA sodB). Experimental results showed that JI132 transformed by pSOD5 was more tolerant of menadione than was JI132 carrying a control vector and that the mutation rate of JI132 carrying pSOD5 was lower than that of JI132 harboring the control vector.
It is known that various species of organisms inhabit the brackish-water Lake Nakaumi. Lake Nakaumi has been subjected to the influence of reclamation and desalination projects. Consequently, its ecosystem has been modified to a great extent, but investigations on protozoan biota have not been conducted so far. In this research, the species diversity and occurrence of ciliate protozoans were examined at 12 fixed points over the course of a year. As a result, spatial distribution of ciliates, species compositions, and their seasonal changes became clear in the whole region of the lake. The species of frequent occurrence were divided to 5 assemblages. Among the environmental factors examined (water temperature, salinity, and pH), salinity showed the strongest influence on the species composition of ciliates. In the Honjo area that is artificially isolated from the main stream of seawater by a system of dikes, some species of ciliates, which normally appears in the inner bay or at high salinity, were seen.
We have recently shown that the anterior flagellum and its mastigonemes play an important role in gliding movement in the colorless euglenoid flagellate, Peranema trichophorum. To facilitate further biochemical analysis of the molecular mechanism of flagellar surface motility, we have developed an improved monoxenic sterile culture method and a method for flagellar isolation. With initial cell densities of Peranema and co-existing food flagellates, Chlorogonium elongatum, at 800 and 30,000 cells/ml, respectively, Peranema reached its maximum cell density of about 10,000 cells/ml in one week. A cold-shock treatment allowed efficient isolation of flagella from the cell body, and light and electron microscope observations confirmed that the isolated flagella retained their intact structure with abundant mastigonemes. SDS-PAGE analysis showed that the preparation contained a predominant protein band of 100 kDa, which was not stained by silver and may therefore be highly glycosylated.
MMP (Matrix metalloproteinase) is a zinc-binding metalloproteinase functions in degrading and remodeling extracellular matrix (ECM). They identified in plants, in Arabidopsis, soybean, cucumber, or green algae Volvox. But the exact functions of MMP in plants are still not known. There are at least three matrix metalloprotease (MMP) genes in Chlamydomonas reinhardtii: 1) MMP1 gene encodes gametolysin (EC 220.127.116.11), which is responsible for removal of cell walls of gametes of both mating types during mating as a necessary prelude to cell fusion; 2) MMP2 gene is tandemly oriented with MMP1 gene and codes for a protein that is 54% identical to gametolysin; 3) MMP3 is found by a search of the EST library and codes for a protein with 65% identity to gametolysin. All three proteases have characteristic motifs of MMP. Specific antibodies were raised against the oligopeptides derived from cDNA sequences of MMP2 and MMP3, respectively. MMP2 was synthesized during 4–20 hrs after zygote cells
Planktonic ciliates are generally known to be strictly heterotrophic, but many marine Strombidiidea including Laboea strobila, and some Tontonia and Strombidium contain functional chloroplasts and perform photosynthesis. These mixotrophic planktonic ciliates isolate chloroplasts from their diet algae. Such behavior of the isolation and sequestration of a cell organ of different creature is interesting not only from ecological but also from evolutional point of view. The purpose of this study is to get enough number of virgin vegetative cells of a planktonic ciliate without chloroplasts to follow the processes of the isolation/sequestration of chloroplasts after supplying diet algae. One of the most dominant planktonic ciliates, Strombidium conicum, in Onagawa Bay, Japan sequesters the functional chloroplasts from ingested phytoplankton. Kim and Taniguchi (1995, 1997) isolated the cysts of this species from sediment samples collected in the bayand successfully identified outenal conditions induce excystment in laboratory. Then, it is theoretically possible to obtain enough number of the newly excysted virgin cells in laboratory if the encystement can also be artificially induced. We put some stresses on a clonal Strombidium conicum population but encystment could not be induced. However, during continual cultures of mixed clones numerous encystements occurred along with a few conjugations after 15–17 times of binary fissions. This suggests that aging and conjugation are necessary for the encystment in this species.
Yuu Microlife Museum is the first museum in the world to display dynamic behavior of microorganisms and their interrelationship to the natural environment and human life. Since its opening on July 16th, 2005, the museum has attracted many visitors interested in microscopic organisms that cannot be seen with bare eyes. The museum is dedicated to promoting the understanding and appreciation of life and surrounding environment, through real-time demonstration of microscopic behaviors of various species of protozoa. Details of displays at the Yuu Microlife Museum and related social activities of the museum staff are summarized in this Mini Review.
Oligotrich ciliates are recognized to be a conspicuous component of microzooplanktonic assemblages in marine habitats. It has become obvious that perform multiple functions in the marine ecosystems such as a primary consumer of pico-and nano-sized producers, a significant nutrient regenerator and important food sources of metazoan zooplankton. To evaluate their functional role in the ecosystems, accurate estimates of growth and reproduction of organisms is indispensable. Cell cycle method including frequency of dividing cells (FDC) method is possibly one of the best too to estimate the growth rate of the ciliates in situ. This method have been successfully applied for several types of planktonic organisms, however, not attempted for oligotrichs because information of diel division pattern of the natural populations had not been available yet. Therefore, an attempt to obtain such basic data was made in this study. As a result, diel division patterns were successfully defined for several natural populations of oligotrichs in the oceanic waters and finally growth rate of the natural populations were determined.