{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,5,13]],"date-time":"2026-05-13T23:41:00Z","timestamp":1778715660102,"version":"3.51.4"},"reference-count":59,"publisher":"Cambridge University Press (CUP)","issue":"3","license":[{"start":{"date-parts":[[2009,4,6]],"date-time":"2009-04-06T00:00:00Z","timestamp":1238976000000},"content-version":"unspecified","delay-in-days":9075,"URL":"https:\/\/www.cambridge.org\/core\/terms"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Parasitology"],"published-print":{"date-parts":[[1984,6]]},"abstract":"<jats:title>SUMMARY<\/jats:title><jats:p>DNA contents of individual stages of <jats:italic>Isospora (Toxoplasma) gondii<\/jats:italic> and other Eucoccida were measured after Feulgen-pararosaniline (SO<jats:sub>2<\/jats:sub>) staining either by direct microfluorometry or by scanning of microphotographic negatives. Frequency distributions were analysed using a computer program based on a mathematical model describing cell division. All stages of <jats:italic>I. (T.) gondii<\/jats:italic>, except fertilized macrogametes (2c), contained a haploid amount of DNA (1c), indicating that meiosis in <jats:italic>I. (T.) gondii<\/jats:italic> occurs during sporogony. Microgametes possessed 3\u00b73% DNA in excess, presumably mitochondrial DNA. Nuclei of M2-and M3-merozoites differed in two characteristics: a small but distinct nucleolus was observed in almost 50% of the M2-merozoites but in none of the M3-merozoites; all M2 merozoites were strictly haploid, while all M3-merozoites were synthesizing DNA (17% above the haploid value). It may be concluded that all M2- and M3-merozoites are already sexually differentiated, i.e. are macro- and microgamontoblasts, respectively. DNA synthesis necessary for the development of the microgamont starts already in the microgamontoblast stage (M3-merozoite). M2-merozoites macrogametes, synthesize 11% extra DNA before fertilization, (after fertilization an extra amount of 12% of the diploid value was found), probably by amplification of genes for proteins which are needed for rapid maturation and later sporogony. Essentially parallel results have been found in <jats:italic>Eimeria tenella<\/jats:italic> and in crescent cystozoites of <jats:italic>Sarcocystis cruzi<\/jats:italic>. Absolute DNA values in representatives of the Eucoccida have been estimated as follows (10<jats:sup>\u221215<\/jats:sup> g): <jats:italic>I. (T.) gondii<\/jats:italic>, 96; <jats:italic>E. tenella<\/jats:italic> and <jats:italic>E. acervulina<\/jats:italic>, both 75; S. <jats:italic>cruzi<\/jats:italic>, 216; <jats:italic>Plasmodium berghei<\/jats:italic>, 27. The value of the estimation of total haploid amounts as a tool in taxonomy of Eucoccida is discussed.<\/jats:p>","DOI":"10.1017\/s0031182000054792","type":"journal-article","created":{"date-parts":[[2009,6,5]],"date-time":"2009-06-05T16:28:30Z","timestamp":1244219310000},"page":"531-553","source":"Crossref","is-referenced-by-count":76,"title":["Determination of nuclear DNA of five Eucoccidian parasites, <i>Isospora (Toxoplasma) gondii, Sarcocystis cruzi, Eimeria tenella, E. acervulina<\/i> and <i>Plasmodium berghei<\/i>, with special reference to gamontogenesis and meiosis in <i>I. (T.) gondii<\/i>"],"prefix":"10.1017","volume":"88","author":[{"given":"A. W. C. A.","family":"Cornelissen","sequence":"first","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"J. 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Sexual differentiation in coccidia. In Progress in Protozoology. 4th International Congress on Protozoology, Clermont-Ferrand, p. 75."},{"key":"S0031182000054792_ref027","first-page":"1529","article-title":"Cytophotometric study of RNA content in growing macrogalnetes of Eimeria schamchorica and E. gliris (Sporozoa, Coccidia) (In Russian)","volume":"14","author":"Gaibova","year":"1972","journal-title":"Tsitologiya"},{"key":"S0031182000054792_ref018","unstructured":"Cornelissen A. W. C. A. & Overdulve J. P. (1980 a). Cytofluorimetrical determination of the DNA contents of stages of Isospora (Toxoplasma) gondii . Proceedings of the 3rd European Multicolloquium of Parasitology, September 7th-13th 1980, Cambridge, p. 21."},{"key":"S0031182000054792_ref026","first-page":"171","article-title":"Ultrastructural studies on the sporulation of oocysts of Toxoplasma gondii. I. 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