Protozoology

Abstract

PROTOZOOLOGY adopted, since it includes undoubted animals and plants, thus creating an equal amount of confusion between it and the animal or the plant. Calkins (1933) excluded chromatophore-bearing Mastigophora from his treatment of Protozoa, thus placing organisms similar in every way, except the presence or absence of chromatophores, in two different (animal and plant) groups. This intermingling of characteristics between the two groups of microorganisms shows clearly their close interrelationship and suggests strongly their common ancestry.Although the majority of Protozoa are solitary and the body is composed of a single cell, there are several forms in which the organism is made up of more than one cell. These forms, which are called colonial Protozoa (p. 173), are well represented by the members of Phytomastigina, in which the individuals are either joined by cytoplasmic threads or embedded in a common matrix. These cells are alike both in structure and in function, although in a few forms there may be a differentiation of the individuals into reproductive and vegetative cells. Unlike the cells in a metazoan which form tissues, these vegetative cells of colonial Protozoa are not so dependent upon other cells as are the cells in Metazoa; therefore, they do not form any true tissue. The reproductive cells produce zygotes through sexual fusion, which subsequently undergo repeated division and may produce a stage comparable with the blastula stage of a metazoan, but never reaching the gastrula stage. Thus, colonial Protozoa are only cell-aggregates without histological differentiation and may thus be distinguished from the Metazoa.An enormous number of species of Protozoa are known to man.From comparatively simple forms such as Amoeba, up to highly complicated organisms as represented by numerous ciliates, the Protozoa vary exceedingly in their body organization, morphological characteristics, behavior, habitat, etc., which necessitates a taxonomic arrangement for proper consideration as set forth in detail in Chapters 8 to 44. Relationship of protozoology to other fields of biological science A brief consideration of the relationship of Protozoology to other fields of biology and its possible applications may not be out of place here. Since the Protozoa are single-celled animals manifesting the characteristics common to all living things, they have been studied by numerous investigators with a view to discovering the nature and mechanism of various phenomena, the years, it has now become known that some 25 species of Protozoa occur in man. Entamoeba histolytica, Balantidium coli, and four species of Plasmodium, all of which are pathogenic to man, are widely distributed throughout the world. In certain restricted areas are found other pathogenic forms, such as Trypanosoma and Leishmania. Since all parasitic Protozoa presumably have originated in free-living forms and since our knowledge of the morphology, physiology, and reproduction of the parasitic forms has largely been obtained in conjunction with the stu...

Morphology and 18S rDNA gene sequence of Spirostomum minus and Spirostomum teres (Ciliophora: Heterotrichea) from Rio de Janeiro, Brazil

“…Spirostomum was mentioned for the first time by EHRENBERG (1838) and morphological studies have been subsequently carried out for some species (PACKARD 1948, FINLEY et al 1964, DANIEL & MATTERN 1965, TUFFRAU 1967, KUDO 1971. However, these studies were based exclusively on observations of specimens in vivo.…”

“…heavy metals like nickel, copper, mercury, and zinc; the phenol Na-PCP) (MADONI et al 1992, MADONI 2000. Nevertheless, studies on the morphology and taxonomy of Spirostomum species are quite rare (PACKARD 1948, FINLEY et al 1964, DANIEL & MATTERN 1965, TUFFRAU 1967, KUDO 1971, REPAK & ISQUITH 1974, FOISSNER et al 1992.…”

Studies on the Rumen Flagellate Neocallimastix frontalis

“…Four species of oval or bean-shaped protists bearing 3 to 15 flagella have been described and grouped in the genus Callimastix Weissenberg, in the family Callimastigidae da Fonseca of the protozoan order Polymastigina (Kudo, 1954). These organisms are: Callimastix cyclopis (Weissenberg, I 9 I 2), parasitic on fresh-water copepods ; C. frontalis (Braune, 1913), inhabiting the rumen; C. equi (Hsuing, 1930), from the horse caecum, possibly synonymous with C. frontalis (Vavra & Joyon, 1966); and C. jolepsi (Bovee, 1961), in the intestine of the fresh-water snail Helisoma duryi.…”

The Apicoplast: A Review of the Derived Plastid of Apicomplexan Parasites

“…The process of schizogony is unusual in that multiple nuclei are produced prior to organelle segregation or cytokinesis (see Figure 7). In P. falciparum the number of daughter cells (merozoites) produced by schizonts is variable, ranging anywhere from 8 to 24 (Kudo, 1971). This number must be tied to the final number of nuclei produced.…”