bluuebunny/crossref_metadata_2025_split huggingface dataset:
Taxonomic Criteria for Limax Amoebae, with Descriptions of 3 New Species of Hartmannella and 3 of Vahlkampfia*
Authors: PAGE FREDERICK C. 
Published: May 2007

SYNOPSIS. Seven species of limax amoebae were isolated into clonal, monoxenic cultures with Aerobacter aerogenes from material collected from freshwater habitats. Studies were made of their trophic structure, nuclear division, cyst structure, some aspects of cytochemistry, and other characteristics. Six new species are described: Vahlkampfia inornata, V. avara, V. jugosa, Hartmannella limacoides, H. vermiformis, and H. exundans. The well‐known species Naegleria gruberi (Schardinger, 1899) is re‐described on the basis of 8 strains; its flagellated phase was found to be biflagellate, with rare exceptions.A correlation exists between the manner of locomotion and the pattern of nuclear division in the limax amoebae in the family Vahlkampfiidae and those in the genus Hartmannella.Trophic amoebae of all species had a PAS‐positive surface layer, altho results with H. vermiformis and H. exundans were less definite than with other species. All species except H. limacoides formed cysts in culture. The cyst walls of all cyst‐forming species were strongly PAS‐positive, but results of the zinc chloroiodide test for cellulose were negative with the method used.The genus Hartmannella Alexeieff, 1912, is re‐defined to include those species which assume a simple, monopodial limax‐like form during locomotion and have nuclear division similar to that of metazoan cells and to distinguish it from the genus Acanthamoeba Volkonsky, 1931.
The Process of Chamber Formation in the Foraminifer Rosalina floridana (Cushman)
Authors: ANGELL ROBERT W. 
Published: May 2007

SYNOPSIS. The foraminifer Rosalina floridana builds a chambered, calcareous test which is periodically enlarged by the addition of new chambers. R. floridana begins to form a chamber by constructing an algal growth cyst which covers the dorsal side of the animal and is cemented to the substrate. The pseudopods that build the cyst coalesce to form a cytoplasmic template or anlage on which the chamber walls will be secreted. Electron micrographs reveal the anlage cytoplasm to be a “froth” of nearly empty vesicles which contain mitochondria, fibrillar material, and electron dense granules. The organic lining of the new chamber is secreted on the anlage by pseudopods extending thru it. After the organic lining is completed, cytoplasm from within the test flows into the forming chamber and forces the anlage cytoplasm out thru the new aperture. This “frothy” anlage cytoplasm forms a sheath over the dorsal surface of the test; while it is in place, a layer of calcite is deposited on the walls of the new chamber and over the rest of the test. When calcification is completed, the sheath breaks up and is incorporated into newly formed pseudopods as the foraminifer gradually moves out of the growth cyst and begins normal feeding.The production of vesiculated cytoplasm in normal pseudopods and in the anlage is viewed as a method of greatly increasing cytoplasmic volume with a resultant very small loss in cytoplasmic mass. In the anlage during the production of the organic lining the vesiculated cytoplasm apparently acts only as a support for the membranes being secreted by the pseudopods and presumably does not take part in the secretory process. This same cytoplasm forms the sheath that is present during calcification. The view is advanced that, altho the sheath could be active during calcification with the mitochondria within the vesicles actively transporting calcium to sites of crystal growth, its more probable function is to form a partition between the parts to be calcified and the environment. The foraminifer could then secrete CaCO3 from pooled reserves in the cytoplasm into the area between the sheath and the chamber membranes. The basal membrane is considered the nucleating agent during calcification and is responsible for the ordering of the crystals so their C axes are perpendicular to the surface of the chamber.
An Intra‐Axonal Protozoon in the Spinal Cord of the Toad Bufo arenarum (Hensel)
Authors: STENSAAS LARRY J. , STENSAAS SUZANNE S. , SOTELO J. ROBERTO 
Published: May 2007

SYNOPSIS. A protozoon was found in myelinated axons of the spinal cord and brain of the toad, Bufo arenarum. Examination with the light microscope using Giemsa, Feulgen, PAS and methylene blue technics revealed a primary cell as large as 30 μ in diameter and containing up to 80 nuclei. Electron micrographs showed that the protozoon ranged from 2 μ to 30 μ in diameter and that larger specimens contained numerous secondary cells (2 μ) in addition to multiple nuclei. A few specimens were found in which the secondary cells had long processes with microtubules. Multiple nuclei together with secondary cells suggest that it may be a schizont form of a sporozoon.The protozoon was found most frequently in axons of the perimedullary plexus just beneath the pia. These axons are without degenerative changes, are up to 3 times the diameter of the largest normal myelinated fibers. The myelin appears normal altho there are fewer laminae than in myelin of other large nerve fibers. The protozoon apparently causes axonal swelling but does not block the fibers completely.Light microscopic attempts to locate similar forms or other stages in the life cycle by examining blood, skin lesions, spleen, liver, small intestine, dorsal and ventral roots, or sensory ganglia were unsuccessful.Examination of spinal cords which had been mechanically severed excluded the possibility of confusing the protozoa with multinucleated macrophages. Altho observations do not prove their mode of entrance to the nervous system, the preponderance of protozoa in the peripherally located perimedullary plexus suggests that the path may be by way of the cerebrospinal fluid or along the endoneurium.
Re‐Definition of the Genus Acanthamoeba with Descriptions of Three Species
Authors: PAGE FREDERICK C. 
Published: May 2007

SYNOPSIS. Ten strains of Acanthamoeba from freshwater habitats were isolated in clonal cultures. Studies were made of trophic structure, nuclear division, cyst structure, some aspects of cytochemistry, and other characteristics. One strain was identified as A. castellanii (Douglas, 1930), one as A. astronyxis (Ray and Hayes, 1954), and 8 as A. polyphaga (Puschkarew, 1913). Strains of Acanthamoeba isolated by other workers were also examined comparatively.The pattern of nuclear division in all strains resembled that in metazoan cells, with the exception that centrioles were never found. Trophic amoebae had a PAS‐positive surface outline. Cyst walls were strongly PAS‐positive and also gave a positive test for cellulose with zinc chloroiodide.The genus Acanthamoeba Volkonsky, 1931 is re‐defined, being distinguished from Hartmannella Alexeieff, 1912, emend. Volkonsky, chiefly by the formation of tapering, hyaline pseudopods (acanthopodia) and by a cyst made up of an ectocyst and a polyhedral or stellate endocyst, with excystment by removal of opercula. Other characteristics found in all strains include a distinctive food cup, the presence of many small refractile globules in the cytoplasm of trophic amoebae, and a cyst wall containing cellulose. The degree of spindle convergence, employed by Volkonsky as a generic criterion, was unusable.Differential diagnoses based principally on cyst structure are offered for A. castellanii, A. astronyxis, and A. polyphaga. The strain previously called Mayorella palestinensis Reich, 1933 is a distinct species of Acanthamoeba.
The Fine Structure of Trophozoites and Gametocytes in Plasmodium coatneyi*
Authors: RUDZINSKA MARIA A. , TRAGER W. 
Published: May 2007

SYNOPSIS. An electron microscope study of Plasmodium coatneyi in the rhesus monkey supplied information on the fine structure of trophozoites, gametocytes and of the host cell. The trophozoites resemble other mammalian malaria parasites. They do not have typical protozoan mitochondria, but instead a concentric double‐membraned organelle, which, it is assumed, performs mitochondrial functions. They feed on the host cell by pinocytosis, engulfing droplets of erythrocytes thru invaginations of the plasma membranes at any region of the cell or thru the cytostome. Digestion of hemoglobin takes place in small vesicles pinched off from the food vacuole proper.Gametocytes can be clearly distinguished into macro‐ and microgametocytes. Macrogametocytes are covered by 2 plasma membranes, the inner one appearing thicker in some places. The cytoplasm is filled with Palade's particles and has numerous vesicles of endoplasmic reticulum and toxonemes. In microgametocytes most of the inner membrane is thickened, the cytoplasm has few Palade's particles and vesicles of the endoplasmic reticulum and does not have toxonemes.Erythrocytes with trophozoites are irregularly scallop‐shaped and have elevated points with knob‐like protrusions covered by a double membrane. If these protrusions are sticky they might be in part responsible for clumping and arresting the schizonts and segmenters in the capillaries. The host cell contains numerous Maurer's clefts which in some instances are continuous with the membranes of the parasite suggesting that they might originate from them.
The Fine Structure of the Mature Gametes of Haemoproteus columbae Kruse*
Authors: BRADBURY PHYLLIS CLARKE , TRAGER WILLIAM 
Published: May 2007

SYNOPSIS. The filiform microgamete of Haemoproteus columbae consists of an elongate double‐walled nucleus paralleled by 2 axonemes embedded in a homogeneous matrix. At one end of the gamete, the axonemes are sharply flexed back on themselves, but no conventional kinetosome has been recognized. No mitochondria have been seen. Single‐walled vesicles occur in the matrix, and the entire gamete is surrounded by a single membrane.The large round macrogamete has a conspicuous central nucleus with its outer membrane drawn out into anastomosing evaginations which extend to the periphery of the cell. A moderately electron dense material fills the space between the 2 nuclear membranes and the lumina of the evaginations. Nucleolar material may occur in scattered masses within the nucleus. One or 2 axonemes appear to arise endogenously next to the nuclear membrane.The cytoplasm is filled with ribosomes and perhaps glycogen granules. Typical protozoan mitochondria and vesicles containing pigment retained from the erythrocytic stage are found in the peripheral cytoplasm. Accumulations of dense‐walled vesicles occur in the cytoplasm in conjunction with evaginations of the nuclear membrane. Amid these vesicles triple‐ringed discs resembling the cytostomes of merozoites are frequently seen.Several distinct layers of dense material surround the micro‐gamete.
Studies on Meiotic Division in Coccidial and Malarial Parasites
Authors: CANNING ELIZABETH U. , ANWAR M. 
Published: May 2007

SYNOPSIS. Oocysts of Eimeria tenella and E. maxima, incubated in colcemid after removal from the host gut, were better preserved after fixation with acetic alcohol than oocysts fixed directly. Colcemid may delay hardening of the oocyst but does not interfere with meiosis. During meiosis the nucleolus disappears and 10 rod‐like chromosomes are formed by condensation of filamentous, beaded chromosomes, which appear in prophase. Two granules which appear on the nuclear membrane at the end of prophase are interpreted as centrioles. The 10 chromosomes align themselves in 2 rows of 5 parallel with, rather than transverse to, the elongate meiotic spindle. After stretching across the spindle as beaded filaments during migration to the poles, the chromosomes condense as a cluster of 5 rods at each pole. Reduction is thus effected in a single phase without duplication of chromosomes or centromeres.During meiosis in P. gallinaceum oocysts paired, Y‐shaped and paired dot‐like chromosomes appear among the pigment granules. No duplication is evident.
Fine Structure of Schizonts and Merozoites of Eimeria nieschulzi*
Authors: COLLEY FREDERICK C. 
Published: May 2007

SYNOPSIS. Schizonts of E. nieschulzi lie in a vacuole within the host cell. After nuclear division the cell membrane invaginates forming merozoites. Differentiation of the pellicle and other organelles occurs while merozoites are still attached to the schizont cytoplasm. Merozoites have a pellicle thickened at the anterior end to form a polar ring. Radiating posteriorly from the ring, directly beneath the pellicle, are about 25 microtubules. Within the polar ring is a dense conoid. Extending posteriorly from within the conoid is a paired organelle. The paired organelle varies in size and shape in each generation of merozoites. Numerous toxonemes occupy the anterior half of the merozoites. Two paranuclear bodies are present in 1st generation merozoites. One or 2 granular bodies were seen in the anterior end of 2nd generation merozoites. In 3rd generation merozoites 6 or more granular bodies were seen anterior to the nucleus.Each merozoite has a single nucleus containing diffuse chromatin material. Elongate mitochondria and glycogen granules are present. The vacuole surrounding mature merozoites contains residual cytoplasm of the schizont and some granular material. Microvilli project into the vacuole from the host cell membrane.
Encystment and Excystment of the Heterotrichous Ciliate Blepharisma stoltei Isquith*
Authors: REPAK ARTHUR J. 
Published: May 2007

SYNOPSIS. The structure and cytochemistry of encystment and excystment of Blepharisma stoltei Isquith are described.The encystment process may be subdivided into 4 stages: (i) in the precystic stage the buccal apparatus overlaps about the posterior, (ii) in early encystment, the buccal apparatus is resorbed and an ectocyst is secreted, (iii) an interwall space, endocyst, and plug are secreted during late encystment, and (iv) the resting cyst stage typically has disc‐like structures on the ectocyst, and a vacuole in the macronucleus.In excystment, 6 distinct stages may be defined: (i) partial kineties are formed in early excystment, (ii) permanent kineties give rise to anlagen of the buccal apparatus during stomatogenesis, (iii) the organism elongates and reforms the vegetative shape in late excystment, (iv) some cysts then divide, (v) the redeveloped organism is liberated thru the plug pore, and (vi) the postcystic stage resembles the vegetative form except for its size and lack of pigmentation.Cortical structures, extracellular membranes, and the macronuclear membrane are composed of protein‐lipids. Unbound protein and RNA are found in the cytoplasm thruout the cystic cycle. DNA is present only in the nuclei. Polysaccharides, 1st found in the cytoplasm, are shifted to the plug in encystment. The plug material disappears during excystment, while PAS positive granules appear in the cytoplasm.
Two New Species of Hartmannella Amebae Infecting Freshwater Mollusks
Authors: RICHARDS CHARLES S. 
Published: May 2007

SYNOPSIS. Two new species of small amebae, Hartmannella biparia n. sp. and Hartmannella quadriparia n. sp., were 1st observed in the freshwater mollusks Bulinus globosus and Biomphalaria pallida, respectively. The amebae multiplied in cytoplasmic vacuoles in host cells, particularly in foci in the mantle collar, foot, and intestinal wall. Both amebae had functional contractile vacuoles while within host cells. H. biparia emerged from intracytoplasmic vacuoles in pairs, H. quadriparia in fours, suggesting characteristic reproductive stages.H. biparia had limax‐type motility by smooth lobopodia, was 22 μ long; with vesicular nucleus 3 μ and central endosome 1.5 μ, multiplied by binary fission and formed spherical, smooth‐walled cysts 11 μ in diameter. H. quadriparia had limax‐type motility by lobopodia with fine, acute projections; was 10 μ long, with vesicular nucleus 2 μ and central endosome 0.75 μ, multiplied and formed spherical, smooth‐walled cysts 5 μ in diameter. Neither species multiplied in cysts outside the host.H. biparia was found infecting 12 species and experimentally transferred to 4 more species of freshwater snails; H. quadriparia was found in one species and experimentally transferred to 6 other species.
Observations on the Fine Structure of the “Cyst Stage” of Besnoitia jellisoni
Authors: SHEFFIELD HARLEY G. 
Published: May 2007

SYNOPSIS. Light and electron microscope studies of the “cyst” of Besnoitia jellisoni indicate that it consists of an extracellular wall, a large, sometimes multinucleate, host cell, and an intracellular vacuole containing the parasites. The “cyst” wall has fine fibrils and small dense granules embedded in an election‐lucid matrix. The wall may be formed from a secretion of the enclosed host cell. The plasma membrane of the host cell is very irregular, being modified into microvillar or pseudopodial extensions. Small vesicles and invaginations of the plasma membrane indicate mioropinocytosis. The one to several large lobular nuclei lie in a thick area of cytoplasm which is filled with rough endoplasmic reticulum and many mitochondria with lamellar cristae. The parasite‐containing vacuole is limited by a vacuolar membrane which has many blebs suggesting a transfer of materials into the vacuole.The “cyst” organisms are crescentic or piriform and are enclosed by a pellicle consisting of outer and inner membranes. Twenty‐two subpellicular fibrils extend longitudinally adjacent to the inner membrane from the anterior polar ring to a posterior ring. A micropyle is situated laterally in the pelliole near the level of the nucleus. A conold and several associated paired organelles are present at the anterior end. Microuemes, more abundant in older organisms, are also present in the anterior portion of the parasite. A Golgi apparatus lies adjacent and anterior to the nucleus. One or more mitochondria with saccular cristae, ovoid glycogen bodies, free ribosomes and occasional vacuoles are also present. Organisms within the “cyst” multiply by endodyogeny.
Ribonucleoprotein‐Containing Vesicles in Cysts of Naegleria gruberi*
Authors: SCHUSTER FREDERICK L. , SVIHLA GEORGE 
Published: May 2007

SYNOPSIS. Ultraviolet microscopy and electron microscope autoradiography were used to study ribonucleoprotein in cysts of Naegleria gruberi. The absorption maximum for cysts is at 265 nm with little detectable absorption occurring at 295 nm. Pre‐cystic trophozoites absorb less strongly than the cysts at 265 mm. Acridine orange staining indicated concentrations of ribose nucleic acid or ribonucleoprotein in the cytoplasm of young cysts. The dye stained discrete vesicles in the cytoplasm.Tritiated uridine and tritiated proline were used to follow changes in RN‐protein at encystment. Label was incorporated into vesicles filled with ribosome‐like particles. These are presumably the sites of acridine orange staining. Relatively little label was associated with the cyst cytoplasmic matrix; most of the silver grains lay over the nucleus and cytoplasmic organelles. The vesicles are believed to represent autophagosomal‐type vacuoles with the contents derived from breakdown of organelles such as mitochondria. The path of label into the vesicles is via lysis of labeled cytoplasmic organelles.The RN‐protein vesicles of Naegleria gruberi cysts are compared to the chromatoid bodies of Entamoeba invadens. It is concluded that, tho differences in detail are present, the role of the structures in the cysts is probably the same. They are a ready source of amino acids and ribosomes in a dedifferentiated or pool state to be used for synthetic reactions that accompany resumption of trophic existence.
Microtubular Structures in Macronuclei of Synchronously Dividing Tetrahymena pyriformis
Authors: FALK HEINZ , WUNDERLICH FRANK , FRANKE WERNER W. 
Published: May 2007

SYNOPSIS. When heat‐synchronized cultures of Tetrahymena pyriformis, amicronucleate strain GL, were examined by electron microscopy, intramacronuclear microtubules were observed in dividing cells. These tubules have a diameter of 180–230 A and occur either singly or packed together in bundles. They are predominantly associated with outpocketings and invaginations of the nucleus. Sections as well as negatively stained preparations of isolated macronuclear envelopes indicate that the microtubules are inserted at the inner nuclear membrane.The findings suggest that microtubules of the spindle type participate in the process of macronuclear division.
The Fine Structure of Trypanosoma congolense in Its Bloodstream Phase
Authors: VICKERMAN KEITH 
Published: May 2007

SYNOPSIS. The fine structure of 2 isolates of Trypanosoma congolense maintained in laboratory rodents has been studied from thin sections of osmium‐ and aldehyde‐fixed flagellates. The pellicular complex, nucleus, and flagellar apparatus are all similar to those of other African trypanosomes. Aberrant intracellular differentiation of the flagellum is occasionally found.As in bloodstream forms of other salivarian trypanosomes the single mitochondrion forms an irregular canal running from one end of the body to the other, with a shallow bowl‐shaped expansion forming a capsule for the fibrous kinetoplast (mitochondrial DNA). A connexion between the mitochondrial envelope of the kinetoplast and the basal body of the flagellum is not evident, and sometimes the flagellum base is not even apposed to the kinetoplast but lies behind it. Tubular cristae are present in the mitochondrial canal and, by light microscopy, this structure gives a positive reaction for NAD diaphorase suggesting at least some activity in electron transport, even tho at this stage in its life cycle respiration is doubtfully sensitive to cyanide and cytochrome pigments are in all probability absent.The region of the cytoplasm between the nucleus and the flagellar pocket has all the trappings associated with secretory cells in higher animals, or with the secretion of surface structures in phytoflagellates. just behind the nucleus a limb of granular reticulum subtends a Colgi stack of flattened saccules with attendant vesicles. Close to the distal pole of the Golgi complex is a network of smooth‐membraned cisternae, termed here the agranular or secretory reticulum, which undergoes localized swelling with the accumulation of a secretory product to form large spherical sacs or vacuoles. These network‐linked vacuoles probably correspond to the post nuclear vacuole complex visible by light microscopy. From its apparent secretory function this complex is regarded here as being possibly an extension or derivative of the Golgi complex, the smooth‐membraned tubules lying alongside the 2 structures possibly representing a link between them.By analogy with phytoflagellates and the secretory cells of higher animals, it is suggested that the secretion is transported for discharge into the flagellar pocket by way of multivesicular bodies and smooth‐walled tubules or vesicles. Spiny pits in the wall of the flagellar pocket, and similar‐sized vesicles in the nearby cytoplasm, could be stages in either exocytosis of secretion or endocytosis (pinocytosis). It is tentatively suggested that the secretion may be the material from which the surface coat is formed.Neither a cytostome nor a contractile vacuole has been observed in T. congolense.
Gamma Irradiation of Stentor polymorphus
Authors: PREECE ALAN W. 
Published: May 2007

SYNOPSIS. Stentor polymorphus was irradiated with 60Co gamma rays at 525 rads/minute to examine the effect on survival, cell division, oral membranellar frequency and oxygen uptake. Both survival and cell division were studied on single cells. The LD50 is 285 kilorads but cell division is inhibited below this dose; 110 kilorads doubles the 1st post‐irradiation division interval, and a delay of 240 hours occurs at the maximum tolerated dose of 310 kilorads. Conjugating cells are more sensitive, with an LD50 of approximately 40 kilorads.The frequency of cilia in the membranellar band, measured stroboscopically, is reduced by 30% after 14.5 kilorads, and stopped by higher doses. Recovery has a similar time scale to recovery of fission. A Clarke electrode was used to measure changes in oxygen uptake after irradiation. Depressions of up to 50% were found. Recovery followed a similar pattern to that of ciliary activity and cell division.