Minuta form

Minuta form Following oral ingestion of the cyst, 4 trophozoites (= minuta form) are generated from each cyst in the intestine. This form, which inhabits the intestinal lumen, has an as)mimetric structure, 12-20 pm in diameter, and displays 1 or 2 nuclei in its cytoplasm, occasionally with ingested bacteria in the vacuoles. It is capable of amoeboid movement. The minuta form is probably a primarily non-pathogenic amoeba, i.e. it is sometimes the cause of mild dysenteric symptoms. 

Asymptomatic intestinal amoebiasis may be witnessed both with and without excretion of cysts or the minuta form of the pathogen. It is, however, possible that the tissue is invaded without the appearance of symptoms, so that patients with extraintestinal amoebiasis do not complain of diarrhoea, either at the time of consultation or in the anamnesis. This is obviously of chnical and therapeutic relevance. 

The minuta and magna forms excreted in the faeces in intestinal amoebiasis are usually not infectious, as they perish rapidly in the stools once they have been excreted. Today, differentiation can be made between the two forms using molecular biology techniques. Only the cysts are responsible for transmission, but they are not present in the stool in the acute phase infection from the cysts is transmitted by the faecal-oral route and hence only in the symptom-free, chronic stage of the disease. An exact incubation period has not been defined. The latent period may last for several years. 

Fukuda, H., T. Fujii, E. Sukita, M. Tazaki, S. Nagahama, and T. Ogawa (1994). Reconstitution of the isobutene-forming reaction catalyzed by cytochrome P450 and P450 reductase from Rhodotorula minuta Decarboxylation with the formation of isobutene. Biochem. Biophys. Res. Commun. 201, 516-522. 

A cell-free isobutene-forming system from disrupted R. minuta cells was also created (Fujii et al. 1988). Isobutene was produced from a-ketoisocaproate, isovaleryl-CoA and isovalerate where isovalerate gave the best isobutene formation rate of these three with 9.1 nL/L/h. Adding NADPH to the reaction mixture proportionally increased the rate of isobutene production, until a concentration of around 0.1 mM, as did increasing the concentratiOTi of isovalerate until 30 mM. EDTA had no inhibitory effect (Fujii et al. 1988). The formation of isobutene was inhibited by some redox reagents and completely eliminated by the presence of carbon monoxide (Fujii et al. 1989b). 

Fujii T, Ogawa T, Fukuda H (1988) Preparation of a cell-free, isobutene-forming system from Rhodotorula minuta. Appl Environ Microbiol 54(2) 583-4 Fujii T et al (1989a) The role of L-phenylalanine in the production of isobutene by Rhodotorula minuta. J Ferment Bioeng 67(2) 115-118... 

Fujii T et al (1989b) A membrane-bound isobutene-forming enzyme from Rhodotorula minuta. FEMS Microbiol Lett 58(2-3) 199-202... 

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