• Journal of Microbiology
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• v.34 no.3
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• pp.220-224
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• 1996

Ultrastructural organization of encysting zoospores of Allomyces macrogynus was examined using the methods of cryofixation and freeze substitution. During enxcystment, obvious changes were observed at the surface of the plasma membrane and in the structure of gamma particles. Many multivesicular bodies associated with the plasma membrane were observed at early stages of encystment. After induction of encystment, vesicles were found within the gamma particles. These vesicles appeared to leave gamma particles after forming multivesicular bodies. This study suggests that the cell wall formation during encystment is mediated by the fusion of multivesicular bodies with the plasma membrane.

• Animal cells and systems
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• v.6 no.4
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• pp.341-347
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• 2002

The life cycle of Acanthamoeba is comprised of two distinct stages, tropho-zoite and cyst. During periods of stress, trophozoites undergo cellular differentiation into cyst. In order to understand the cellular differentiation, ore followed changes in profiles of major proteins by 2D-PAGE and ubiqui-tinated proteins by immunoblotting with anti-ubiquitin (Ub) monoclonal antibody (mAb) as a probe. We observed 51 proteins present in trophozoite were lost with the encystment. We found that 43 proteins within 24 h, and 8 proteins in 96 h of encystment. Among them, 17 proteins were staine with anti-Ub mAb. In cysts, 16 proteins including 2 anti-Ub mAb-reactive proteins were newly synthesized. Four proteins were newly detected in 24 h-cyst and disappeared in 96 h-cyst, one protein was synthesized in 24-96 h-cyst and disappeared in 168 h-cyst, and 11 proteins appeared upon en-cystment and were present in all cyst stages. We identified a cyst specific 33 kDa protein as subtilisin-like serine proteinase by N-terminal sequencing. Identification of these proteins lost and newly synthesized with encystment would improve our understanding of cysting protozoan parasites.

• Parasites, Hosts and Diseases
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• v.55 no.3
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• pp.233-238
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• 2017

Pathogenic Naegleria fowleri, Acanthamoeba castellanii, and Acanthamoeba polyphaga, are distributed worldwide. They are causative agents of primary amoebic meningoencephalitis or acanthamoebic keratitis in humans, respectively. Trophozoites encyst in unfavorable environments, such as exhausted food supply and desiccation. Until recently, the method of N. fowleri encystation used solid non-nutrient agar medium supplemented with heat-inactivated Escherichia coli; however, for the amoebic encystment of Acanthamoeba spp., a defined, slightly modified liquid media is used. In this study, in order to generate pure N. fowleri cysts, a liquid encystment medium (buffer 1) modified from Page's amoeba saline was applied for encystation of N. fowleri. N. fowleri cysts were well induced after 24 hr with the above defined liquid encystment medium (buffer 1). This was confirmed by observation of a high expression of differential mRNA of nfa1 and actin genes in trophozoites. Thus, this liquid medium can replace the earlier non-nutrient agar medium for obtaining pure N. fowleri cysts. In addition, for cyst formation of Acanthamoeba spp., buffer 2 (adjusted to pH 9.0) was the more efficient medium. To summarize, these liquid encystment media may be useful for further studies which require axenic and pure amoebic cysts.

• The Korean Journal of Malacology
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• v.23 no.2
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• pp.181-187
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• 2007

A scanning electron microscopic study on the glochidium and glochidial encystment of Anodonta arcaeformis on the host fish Carassius auratus was conducted. The shape of the glochidium was apparently subtriangular and its average size was $270\;{\mu}m\;\times\;260\;{\mu}m\;\times\;145\;{\mu}m$. The glochidial shell valves were of the same size, kept together by a ligament that is 50.4 ${\mu}m$ in length and 5.5 ${\mu}m$ in width. Each of the glochidial shell valve had a long hook studded with many spines on the superior face. A large area of at the apex of the valve surrounding the base of the hook was provided with numerous small spines which became progressively smaller toward the periphery of the area. The glochidial shell valve consisted of two layers. The mantle cells line the glochidial shell valves and some of hair cells were observed. A larval thread was 2.3 ${\mu}m$ in diameter. In the artificial infection of the glochidia to one of the natural hosts, Carassius auratus, it took about three to four hours to encyst the glochidia with epithelial cells of the fish fins. The encystment method was the cell migration from the neighboring epithelial cells.

• The Korean Journal of Malacology
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• v.7 no.1
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• pp.76-86
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• 1991

A scanning electron microscopic stuey on the glochidial encystment study on the golchidal encystment and excystment of Anodonta fukudai on Acheilognathus yamatsutae, a common natural hostfish, was conducted. The glochidium easily attached to the unscaled surfaces of the host fish such as the fins, lips, and the wall of the buccal cavity. For this study, the fins infected with the glochidia wer mainly observed in a series. The process of encystment was slowly progressed, for 21-25 hours for the early cyst and for 2-4 days for the thick walled cyst. The process of excystmint was visually detected on the 12th day since the attachmint was occurred. The first visible sign was a little tear of the cyst wall covering the hinge and marginal zones of the juvenile clam and once the little sign was appeared the progress of emerging and dettachmint of the juvenile clam from the host was finished relatively in short time. During the process of the encystmint, the cells participationg in covering the attached glochidirm were seened mainly supplied by migration from the surroundings. the shapes of the cells migrating and covering the glochidium were considerably changed and the surface structures of the cells lost their normal pattern of the surface ridges. The unstable forms of the cells were observed almost all throughout the period of the glochidial attachment. No cells of the host epithelium, which were still attached to the juvenile clam energing from the cyst, were observed. The most juvenile clams escaped from the cysts were a little bigger than the glochidia and they were still possessed of the golchidial hooks even though much degenerated. The first growth line was appeared on the shell valves of the juvenild clam when observed right after dettachment.

• Development and Reproduction
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• v.2 no.1
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• pp.81-87
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• 1998

A scanning electron microscopic study on the glochidial encystment and excystment during the development of Anodonta arcaeformis flavotincta on Carassius auratus, a common natural host fish, was carried out. The glochidia were attached to the fins, buccal cavity and gills of the host fish within 30 minutes. In this study, the fins of host fish infected with the glochidia were examined in a time series. The attachment rates of the glochidia on the pectoral fins, caudal fin and pelvic fins of the host fish were 30%, 22%, and 17%, respectively. The glochidia which attached to the fish became encysted within 27 hrs. The process of encystment progressed slowly. Ti took 24 to 27 hours in the formation of the primary cyst, and after 5 to 6 days, the larvae was covered completely with the epithelial cels of the host tissues. The process of detachment of juvenile clam was observed on the 8th day after host infection. Most of the juvenile clams have sloughed from the cyst of the host within 15 days. No significant size difference was observed in the glochidia and the juvenile which were found before attachment and after detachment from the cyst of the host fish.

• Proceedings of the Korean Society of Fisheries Technology Conference
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• 2001.05a
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• pp.595-596
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• 2001

A scanning electron microscopic study on the glochidium and glochidial encystment of Anodonta archefomis on the host fish Carassius auratus was conducted. The shape of the glochidium is apparently subtriangular and its average size is 270${\mu}{\textrm}{m}$ $\times$ 260${\mu}{\textrm}{m}$ $\times$ 145${\mu}{\textrm}{m}$. The glochidial shell valves are of the same size, kept together by a ligament of 50.4${\mu}{\textrm}{m}$ in length and 5.5${\mu}{\textrm}{m}$ in width. (omitted)

• The Korean Journal of Malacology
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• v.5 no.1
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• pp.1-9
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• 1989

A scanning electron microscopic study on the glochidium and glchidial encystment of Anodonta grandis on the guppy was conducted. The shape of the glochidium is apparently triangular and its averge size is 0.45mm X0.4mm when closed, The two glochidial shell valves are of the same size, kept together by a ligament of 120${\mu}{\textrm}{m}$ in length and 7 ${\mu}{\textrm}{m}$ in width. Each of the glochidial shell valves has a 16 ${\mu}{\textrm}{m}$ long hook sitdded with many spines on the superior face. A large area to the apex of the valve surrounding the base of the hook is provided with numerous small spines which become progressively smaller towards the periphery of the area, The external surface of the glochidial shell valve is covered with numerous small processes showing successive change in the shape and the pattern of destribution by part. Besides the processes, there are a number of niches scattered all over the exterior surface. The glochidial shell valve has two layers. One is the outer thin membrane bearing the processes and the niches and the others is the inner layer bearing numerous holes which any accessory structure and 2.65 ${\mu}{\textrm}{m}$ in diameter, emerges from a canal located at center of ventral plate of the mamtle, A total of three types of the hair cells are observed. In present artificial infection of the glochidium to the guppy, it took about three to four hours to complete an early cysts, During the period of encystment, The epithelial cells of the host fish actively migrated toward the attached glochidium and covered it.

• The Microorganisms and Industry
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• v.19 no.4
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• pp.27-31
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• 1993

Certain bacterial species possess the capability of differentiation through several morphogenetic changes which enable them to adapt to certain internal and external stimuli(Losick and Shapiro 1984). Upon induction, cells of A. vinelandii undergo a morphological process which leads to the production of one cyst per cell (Sadoff, 1975). The cysts are considerably resistant to desiccation, which confers a survival advantages upon the organism(Socolofsky and Wyss 1962). Like other prokaryotic differentiations encystment provides a relatively simple model of cellular differentiation. Like in other differentiating bacteria, vegetative growth can be separated from differentiation. Furthermore, the differentiation cycle can be synchronized by specific inducer. There have been a great deal of morphological and physiological studies on this process. However, the mechanisms used to regulate cell differentiation can be clearly defined by careful genetic analysis of the process. Unfortunately, A. vinelandii has proven to be difficult for genetic analysis (Sadoff 1975). For example, it has been shown that a variety of metabolic mutants of Azotobacter speicies are difficult to isolate after mutagenesis with chemical mutagens or UV irradiation. Nevertheless recent advances in molecular genetics in Azotobacter species, especially in the nitrogen fixation research area, appear to be able to overcome this difficulty (Robinson et al. 1986; Kennedy et al. 1986).

• 한국생물공학회:학술대회논문집
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• 2000.04a
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• pp.422-423
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• 2000

The protozoan parasite Giardia lamblia has been implicated as the causative agents of many outbreaks of waterborne intestinal illness. Accurate evaluation of Giardia lamblia removal in water treatment process requires a reliable method for measuring the concentrations of these pathogens in water. The relative recovery of Giardia cysts was assessed for seeded samples of distilled water. Cysts preparation was done by encystment in vitro. Membrane filtration was evaulated with cellulose acetate, polycarbonate, polypropylene, polyethersulfone, nylon membranes. Elution conditions were varied to improve cyst recovery.