bluuebunny/crossref_metadata_2025 huggingface dataset:
Infection of Alga‐Free Paramecium bursaria with Strains of Chlorella, Scenedesmus, and a Yeast
Authors: BOMFORD R.
Published: May 2007

SYNOPSIS. Twenty‐one different stocks of Paramecittm bursaria, belonging t o 4 separate varieties (syngens), whose endosymbiotic chorellae had been removed, were tested for reinfection by several strains of Chorella, some previously isolated from P. bursaria, and others free‐living. In addition, infection of P. bursaria by a single strain of the green alga Scenedesmus sp., and an unidentified strain of yeast was attempted. Most combinations involving Chlorella yielded infected paramecia, and all those with Scenedesmus or the yeast did so. The failures with Chlorella were attributed to low infectibility of the stocks of Paramecium concerned, rather than to inability of the Chlorella to survive inside the paramecia. Little evidence was found that the strains of P. bursaria differed genetically in ability to maintain the symbiotic organisms.
The Effects of Heat and Cold on Cellular Development in Synchronized Tetrahymena pyriformis WH‐6*
Authors: GAVIN RAY H.
Published: May 2007

SYNOPSIS. Experiments were performed to ascertain the effect of heat and cold on oral and micronuclear development in synchronized Tetrahymena pyriformis WH‐6. The developing oral primordium becomes insensitive to cold sometime during stage 2. Cold shocks cause the reversion of many stage 2 primordia to stage 1. Cells so affected are set back in division. The delayed division is always asynchronous. When heat shocks are applied prior to late stage 4, the developing primordium will regress. High temperature shocks applied at later stages permit continued development. However, when the cell begins to cleave at the high temperature, division is frequently arrested and the new oral areas regress. Subsequent cell separation is greatly delayed and asynchronous.

Heat and cold affect the micronucleus in the same way. Both agents prolong the arrest of mitosis brought about by the synchronizing treatment. A temperature shock is ineffective if applied after there is a space completely separating the chromosome groups, so that mitosis is completed in the presence of the agent. Bimicronucleate chains result in those cases in which division is arrested by heat shocks.

It is suggested that the different phases of sensitivity to heat and cold may reflect different types of syntheses necessary for development of the oral primordium. Division arrest and subsequent oral replacement might possibly be related to high temperature induced changes in the physical state of the ciliate cortex.
The Fine Structure of Two Archigregarines, Selenidium fallax and Ditrypanocystis cirratuli
Authors: MACGREGOR H. C. , THOMASSON P. A.
Published: May 2007

SYNOPSIS. In S. fallax and D. cirratuli the pellicle is thrown into longitudinal folds. The pellicle consists of 2 membranes, one 3‐layered, the other 5‐layered. Sub‐pellicular fibrils, each about 23 mμ in diameter run along the pellicular folds. Pellicle and sub‐pellicular fibrils together form the mechanism by which Selenidiids move. The undulating membranes of D. cirratuli are enlarged pellicular folds, the tips of which are packed with fibrils. The light ovoid patches seen in thin sections are sections through regions which contain a form of glycogen in the living animals. Typical mitochondria are absent. Objects described as lipochondria have a regular distribution at the bases of the grooves in the pellicle and are probably formed from the inner components of the pellicle.
Fission and Morphogenesis in a Marine Ciliate Under Osmotic Stress*
Authors: TARTAR VANCE
Published: May 2007

SYNOPSIS. Condylostoma magnum can be greatly yet reversibly swollen or shrunken by altering the salinity of the medium. These ciliates survive well in 10% to 400% sea water. Swollen animals can initiate and complete cell division, with important implications for the nature of the division furrow and the origin of the division primordium. Reproduction is also possible in 400% sea water though the animals are then tiny and vitreous. Normal oral regeneration at the extreme salinities mentioned also shows that morphogenesis is remarkably unaffected by extraordinary changes in the colloidal state of the cytoplasm.
Ultrastructure of Trypanosoma lewisi: Flagellum, Microtubules, and the Kinetoplast
Authors: ANDERSON W. A. , ELLIS R. A.
Published: May 2007

SYNOPSIS. With the technique of preselecting pure suspensions of trypanosomes for subsequent electron microscopy and with epoxy resin embedding after glutaraldehyde fixation, we have re‐examined the ultrastructure of Trypanosoma lewisi with particular reference to the flagellum and pellicle. The peripheral flagellar tubules exhibit clockwise asymmetry; however, sub‐tubule B of the peripheral tubules is divided into a doublet by a diagonally running anti‐clockwise arm that originates from the median diaphragm. Projections which seem to be continuous with the counter‐clockwise arms extend into a “basket shaped” intra‐flagellar structure. This structure, originating distal to the flagellar pocket and running anteriorly within the flagellar membrane, may play a role in maintaining the rigidity of the flagellum.

The central flagellar tubules have a double helical substructure and dense cross‐striae (diameter 50 Å), and are regularly arranged at distances of approximately 250 Å. The central tubules arise from separate kinetosomal plates that lie at two different elevations. One central flagellar tubule originates from a flattened kinetosomal plate which makes contact with the peripheral tubules. The other central tubule passes through the flattened plate to fuse with an underlying “disc‐like” plate.

The primary kinetosome exhibits the uniform triplet pattern of tubules at its most proximal region. A pair of tubules closely associated with one of the triplets represents two of the four subpellicular tubules which penetrate the cytoplasm in the region of the flagellar pocket. Sub‐pellicular tubules of dimensions similar to the flagellar tubules form a uniform cytoskeleton in all regions of the cell except in the area of the flagellar pocket.

A desmosome‐like structure maintains continual cell membrane contact with the flagellum and the pellicle. This structure is designated the attachment zone. The fine structure of the kinetoplast is demonstrated. The dense intra‐mitochondrial elements (presumably containing DNA) are actually tubules, embedded in a moderately dense matrix. Morphological observations indicate that this organelle is probably primarily concerned with the ontogenesis of mitochondria, and several mitochondria extend from it into the cytoplasm of the cell.
Effect of pH of the Medium on the Availability of Chelated Iron for Chlamydomonas mundana
Authors: MACIASR F. M.
Published: May 2007

SYNOPSIS. Nutritional and cultural factors influenced growth of Chlamydomonas mundana at different H‐ion concentrations. Growth at acid pH (5.5–6.0) primarily depended on the acetate and chelated iron concentration and on the method of preparation of the medium. The organism had increased Na, Ca, and Mn requirements at an acid pH. Sensitivity to increased levels of phosphate was greater at low than at high pH. The requirement for chelated as compared with non‐chelated Fe was qualitatively easier to demonstrate at low pH. The procedure followed in preparing the growth media was more important with higher levels of chelator and Fe and with media of low pH. All 6 synthetic chelators studied were more effective, as measured by growth, if combined with iron before addition to the media. At high pH (7.0–7.5), the organism was much more adept at utilizing over‐chelated Fe. This latter finding, and the greater sensitivity at low pH to trace‐metal imbalance in ill‐prepared media, indicate that the organism absorbs Fe much more efficiently at neutral or slightly alkaline pH.
A New Species of Heliochona, H. psychra n. sp. (Ciliata: Chonotrichida), from Nuwuk Lake, Alaska*
Authors: MATSUDO HITOSHI , MOHR JOHN LUTHER
Published: May 2007

SYNOPSIS. Heliochona psychra n. sp. (Ciliata: Chonotrichi‐da), an ectocommensal on the pleopodal bristles of Gammarus setosa Dementieva from Nuwuk Lake, a marine halocline lake at Point Barrow, Alaska is described. H. psychra differs from the older species H. scheutenii Stein and H. sessilis Plate in its size, outline of the cytosome, and appearance of the funnel rays.
Paranophrys marina n. g., n. sp., a New Ciliate Associated with a Hydroid from the Northeast Pacific (Ciliata: Hymenostomatida)*
Authors: THOMPSON JESSE C. , BERGER JACQUES
Published: May 2007

SYNOPSIS. The ciliate, Paranophrys marina n. g., n. sp., is described from a marine hydroid, Plumularia sp., collected in the San Juan Archipelago, Washington. Morphological studies were made on specimens treated with the Chatton‐Lwoff silver impregnation technique. Particular attention is given to the infraciliature of the buccal apparatus and its importance in generic and familial assignment within the order HYMENOSTOMATIDA.
Cytological Observations on Two Planktonic Foraminifera, Globigerina bulloides d'Orbigny, 1826, and Globigerinoides ruber (d'Orbigny, 1839) Cushman, 1927*†‡
Authors: LEE JOHN J. , FREUDENTHAL HUGO D. , KOSSOY VICTOR , BÉ ALLAN
Published: May 2007

SYNOPSIS. Globigerina bulloides and Globigerinoides ruber, two pelagic foraminifera from the North Atlantic, were fixed in modified Zenker or Bouin solutions directly after collection and studied cytochemically. They have two unusual organelles: a vesicular system and an organelle provisionally named a “cryptosome.” The vesicular system occurs chiefly in the newest formed chambers and consists of a pair of intertwined tubules with helical fine structure which terminate in a bouquet of approximately 20 vesicles or loops. The function of this system is unknown. The detailed morphology of the vesicular system is different in each species. The cryptosome is a structure which varies greatly in its morphology. It is better developed in G. bulloides than it is in G. ruber. At times a cryptosome may occupy up to 2/3 of the protoplasm of a chamber. In Himes‐Moriber‐stained preparations crypto‐somes stain with naphthol yellow S and contain within them an azure A‐Schiff staining spongy reticulum. Both of the pelagic foraminifera studied are heterokaryotic. Agamonts of G. ruber may have a graded series of nuclear sizes but those of G. bulloides typically have a single somatic nucleus. The zooxanthellae of G. ruber are similar to Symbiodinium microadriaticum and may collectively occupy almost 4/5 the volume of a chamber.
A Dinoflagellate with Characters of Gymnodinium and Gyrodinium*
Authors: KIMBALL J. F. , WOOD E. J. FERGUSON
Published: May 2007

SYNOPSIS. An organism was isolated which in the first instance appeared to be Gymnodinium mirabile and in subsequent cultures took on characteristics similar to those of Gyrodinium fissum. It is not known at present whether the pleomorphism exhibited by this strain is frequent among the naked flagellates, but this finding raises the question of whether naked dinoflagellates can be identified by examination of collected samples, whether living or preserved, or whether culture studies are necessary for all such identifications.
Neustonic Marine Craspedomonadales (Choanofiagellates) from Washington and California
Authors: NORRIS RICHARD E.
Published: May 2007

SYNOPSIS. Neustonic choanoflagellates can be found in marine tide pools in the San Juan Islands, Washington, and on the Monterey Peninsula, California. Several marine photo‐synthetic Chrysophyceae (in the Pedinellaceae), which also occur in these regions, have a basic structure so similar to choanoflagellates that this family is placed in the Craspedomonadales. In pointing out this relationship, the derivation of the Craspedomonadales from pigmented Chrysophyceae is strongly indicated.

In addition to the naked choanoflagellates, which are placed in the Codonosigaceae, these organisms produce loricae of two different types: 1) loricae possibly of cellulose and without visible structure in the light microscope (Salpingoecaceae), 2) loricae composed of silica strands, sometimes forming a mesh with large open spaces (Acanthoecaceae). Members of the latter family seem to be confined to a marine environment and are a prominent part of this investigation. Examination of several species with the electron microscope has revealed interesting details of lorica morphology that are not visible with the light microscope.

Several new combinations of taxa are proposed in addition to new taxa, including 4 new species of Salpingoeca, 3 new species of Diploeca and 4 new species of Pleurasiga. Three new genera are described, Ellisiella gen. nov., Acanthoecopsis gen. nov., and Sportelloeca gen. nov.
Observations on the Sexual Generation of Gromia oviformis Dujardin
Authors: ARNOLD ZACH M.
Published: May 2007

SYNOPSIS. The firm union of the shells of adult Gromia oviformis in plastogamous pairs is followed by gametogenesis and fertilization with the production of distinctive fusiform zygotes that undergo further transformation into amoebulae initially having hyaline radiate pseudopodia. The amoebulae emerge from the parental shells and probably initiate the asexual phase of the life cycle.
Prolonged Culture of the Voracious Flagellate Peranema in Antioxidant‐Containing Media*
Authors: ALLEN JAMES R. , LEE JOHN J. , HUTNER S. H. , STORM JACK
Published: May 2007

SYNOPSIS. Peranema trichophorum remained vigorous at least a year in milk‐lecithin media and 3 months in a nearly defined autoclavable biphasic agar medium fortified with the fat‐soluble antioxidant butylated hydroxytoluene. The only undefined substance in the present “defined” medium is crude soybean lecithin; 0.001% lecithin suffices in the presence of a mixture of long‐chain saturated and unsaturated fatty acids. Linoleic acid may be indispensable. Histidine is an absolute requirement as well as a favored substrate. Cholesterol, not ergosterol, satisfied the sterol requirement. Voracity is retained in these media as shown by engorgement on plastic latex particles.
Observations on Some Chrysomonads from Scotland
Authors: BRADLEY D.E.
Published: May 2007

SYNOPSIS. The taxonomy of the genera Mallomonas, Mallomonopsis and Synura is based on their silica scales. Examination of water samples from Southern Scotland in the electron microscope revealed that they were plentiful in the area and permitted detailed observations on new species. Comparative studies are made on the flagella of three known species of Synura; the “flimmergeissel” of these biflagellates appear to be more or less similar, but the whip‐lash flagella show specific differences suggesting a possible secondary taxonomic criterion. The distribution of the three genera is discussed with particular reference to species found in Iceland, Scotland and Japan. A stage in the conjugation of a species of Mallomonas is described.
A Method for Harvesting Mass Cultures of Tetrahymena pyriformis
Authors: CONNER R. L. , CLINE S. G. , KOROLY M. J. , HAMILTON B.
Published: May 2007

SYNOPSIS. A centrifugation procedure for removing Tetrahymena from mass cultures is described. This method offers the following advantages: (a) inexpensive apparatus, (b) the short period of time required for harvesting large numbers of cells, (c) lack of cellular damage, (d) the ability to obtain proven dilution with regard to the culture fluid, (e) nearly quantitative recovery of the cells, and (f) the ease of assembling and disassembling the apparatus for cleaning.
Glauconema trihymene n. g., n. sp., a Hymenostome Ciliate from the Virginia Coast*
Authors: THOMPSON JESSE C.
Published: May 2007

SYNOPSIS. Glauconema trihymene n. g., n. sp., a marine hymenostome ciliate, is described from the Virginia coast. Morphologic studies were made on specimens treated with the Chatton‐Lwoff silver impregnation technic and on animals observed with the phase microscope. Particular attention is given to the buccal ciliature and its importance to generic assignment in the order Hymenostomatida.
Paraholosticha polychaeta n. sp. (Ciliata, Hypotrichida) from a New Hampshire Tidal Marsh
Authors: BORROR ARTHUR C.
Published: May 2007

SYNOPSIS. This member of the Holostichidae differs from its five congenors in the possession of transverse cirri, the way in which its frontal cirri are arranged, and its estuarine habitat. Like other valid members of the genus Paraholosticha, this species has some of the frontal cirri arranged in a corona parallel with the anterior part of the zone of membranelles. This unique character, despite the possession of transverse cirri, places this ciliate in the genus Paraholosticha. Diagnostic characters of all valid members of this genus are presented, and the need for careful descriptions and taxonomic revisions within the suborder Stichotrichina is discussed.
Uptake of 45‐Calcium by Spirostomum ambiguum*
Authors: JONES ALICK R.
Published: May 2007

SYNOPSIS. Spirostomum ambiguum equilibrated with 45Ca in the external medium after about 14 days under normal conditions. As the external Ca concentration was increased, uptake was increased but only until the internal concentration was ∼ 60 mM. Changing the Ca/K ratio or increasing the K or Mg concentrations had no effect on uptake of the isotope; this was taken as an indication that most of the uptake reflected Ca binding as apatite. Increasing and decreasing the temperature increased and decreased Ca uptake, but Ca bound at higher temperatures remained in the animal at lower temperatures. Feeding caused a marked increase in uptake of isotope, probably due to the availability of a large number of binding sites on the products of digestion perhaps accompanied by increased permeability of the cell membrane. It is argued that most of the 45Ca taken up is incorporated into Ca phosphate deposits, although it is likely that there will be a certain amount of free or weakly bound Ca.
The Fine Structure of Colpoda maupasi with Special Emphasis on Food Vacuoles*
Authors: RUDZINSKA MARIA A. , JACKSON GEORGE J. , TUFFRAU MICHEL
Published: May 2007

SYNOPSIS. An electron microscope study of Colpoda maupasi Enriques, isolated from the intestine of the blue‐tongued skink Tiliqua nigrolutea, showed that the fine structure of this ciliate is similar in all respects to that of free‐living ciliates. The correspondence applies particularly to the structure, distribution and number of mitochondria. This organelle has a rich intramitochondrial structure in the form of microvilli; it is found close to the periphery, near the nuclear apparatus and in other parts of the cytoplasm. It was concluded that the association between Colpoda maupasi and Tiliqua nigrolutea was probably accidental and limited to the cyst stage. Thus electron microscopy confirmed a conclusion arrived at by light microscopy.

The presence of numerous food vacuoles made it possible to study stages of digestion within this organelle. Four major types of food vacuole were distinguished. Type 1 food vacuoles are characterized by their large size, the presence of intact bacteria and abundance of water. In type 2 the food vacuole is deprived of water, the bacteria are pressed together and the nuclei have lost their structure. Type 3 food vacuoles contain only bacterial ghosts, cytoplasmic and nuclear material having been digested. Food vacuoles of this type are found only occasionally, suggesting their short duration. It is of interest that during this transient stage the bulk of digestion takes place. In type 4 nothing reminiscent of bacteria is found; there are only myelin figures and vesicles of different sizes. Evaginations and invagnations of the vacuolar membrane and vesicles of different size and structure inside and outside the food vacuoles of types 1, 3 and 4 suggest that extensive communication exists between the cytoplasm and the food vacuole. It seems likely that enzymes are delivered to the food vacuole and digested materials are released from the food vacuole to the cytoplasm.
Sterols of Soil Amoebas and Ochromonas danica: Phylogenetic Approach
Authors: HALEVY S. , AVIVI LYDIA , KATAN HAYA
Published: May 2007

SYNOPSIS. Sterols of Ochromonas danica, Mayorella palestinensis, Acanthamoeba sp. and Hartmannella rhysodes were examined by thin‐layer and gas‐liquid chromatography. The sterol patterns of O. danica and the amoebas were strikingly similar. Two of the sterols present in both groups, were identified as ergosterol and stigmasterol. This similarity is construed as evidence that “soil” amoebas evolved from phytoflagellates having sterol patterns similar to that of O. danica. An explanation is suggested for the role of ergosterol in phytoflagellates, as originally an ultra‐violet‐protective agent, then a membrane component.
Multiple Alleles and Other Factors Affecting Plasmodium Formation in the True Slime Mold Physarum polycephalum Schw*
Authors: DEE JENNIFER
Published: May 2007

SYNOPSIS. The life cycle of the true slime mold Physarum polycephalum includes 2 vegetative stages: the multinucleate coenocytic plasmodium and the uninucleate amoeba. A clone of amoebae established from a single spore does not normally yield plasmodia. Plasmodia are formed when amoebae from particular clones are mixed; thus plasmodium formation is said to be controlled by a ‘mating‐type’ system.

Previous work by the author with a sample of P. polycephalum derived from a single source revealed that 2 mating types were present and were determined by a pair of alleles at 1 locus. The present paper reveals the presence of 2 more mating types in a sample of P. polycephalum derived from a different source and provides evidence that these are determined by 2 alleles at the same locus as the other 2.

Evidence for the presence of other inherited factors affecting plasmodium formation, the mode of action of these factors and possible explanations for the occurrence of plasmodia in single‐spore cultures are also discussed.
Nuclear Activity During Regeneration in Blepharisma intermedium Bhandary*
Authors: PARKER JOHN W. , GIESE ARTHUR C.
Published: May 2007

SYNOPSIS. Transection and regeneration of Blepharisma intermedium initiate complex macronuclear activity and micronuclear division. Reversible condensation of the macronucleus is achieved by contraction which involves primary and secondary coiling. Primary coiling, evident in vegetative cells, is enhanced by pronounced constriction of the macronuclear extremities during regeneration. Secondary coiling is restricted to the period of contraction and is initiated at the ends of the mauonucleus. Condensation terminates the coiling processes and gives rise to an amorphous structure. Re‐elongation of the macronucleus is not followed immediately by coiling. Micronuclear division begins early in regeneration, but the peak of visible activity is not reached until the 3rd through 5th hours.
Mating Types, Breeding System, Conjuàtion and Nuclear Phenomena in the Marine Ciliate Euplotes cristatus Kahl from the Gulf of Naples
Authors: WICHTERMAN RALPH
Published: May 2007

SYNOPSIS. The marine ciliate Euplotes cristatus Kahl (Ciliophora, Hypotrichida), collected off Capri, Gulf of Naples, is described in detail. From populations, 6 different mating types, representing 1 variety or syngen, have been isolated. The breeding relations revealed a multiple mating type system characteristic of other members of the Hypotrichida that have been investigated. Presumably a 7th mating type was found which does not mate with any of the others. Although this may belong to another syngen, it could represent a mating type which has not yet reached sexual maturity or 1 which may be in a period of decline. Animals of different mating type do not mate immediately after being mixed but usually 3 or more hours later. An agglutination reaction involving many specimens is absent. Instead, 2 ciliates engage in a “pairing play” before joining firmly in conjugation. Well‐fed or actively feeding and dividing ciliates do not mate; mating occurs only after the food becomes gradually depleted or when the food supply is sharply cut off. All mating types appear to be extremely stable. Neither selfing pairs (intraclonal conjugation) nor autogamy have been observed within any clonal culture during the several years under investigation. Cell‐free filtrates from 1 mating type do not elicit mating or induce conjugation with specimens of a different mating type. The general pattern of nuclear events in conjugation and exconjugant reorganization is as follows: 1 preliminary division, 3 pregamic (prezygotic) divisions, fertilization, and generally 1 or occasionally 2 postzygotic divisions. The fate of micronuclear products may be determined by their size and location. Those which are larger and close to the cell membranes of the joined conjugants persist and/or divide. Those which are smaller are carried by cyclosis toward the center of each ciliate and degenerate. The degenerating macronucleus of each conjugant becomes segmented in a more or less uniform manner resulting in 4 subspherical masses. Two become localized in the anterior end of a conjugant and 2 in the posterior end. Those in the posterior end are always the first to degenerate completely and disappear. In nuclear reorganization of the exconjugant, fusion of the macronuclear anlage with parts of the old macronucleus does not occur.
Characterization and Localization of Acid Phosphatase Activity of Trypanosoma gambiense*
Authors: SEED JOHN RICHARD , BYRAM JAMES , GAM ALBERT A.
Published: May 2007

SYNOPSIS. Properties and cellular location of acid phosphatase in Trypanosoma gambiense were studied. Activity was found in both the sediment (32,000 ×g) and the supernatant of homogenates. Cenrifugation in 0.3 M sucrose showed activity principally in the lowspeed fraction (4,000 ×g). One min of sonication released most of this activity. Several phosphomonoesters were hydrolyzed at acid H's. Enzymatic activity was relatively specific for pyrophosphate and p‐nitrophenylphosphate at pH 3.6. At pH 5.2, purine and pyimidine nucleotide 5′‐triphosphates as well as adenosine di‐ and ono‐5′‐phosphates were hydrolyzed nonspecifically. Activity with yrophosphate at pH 3.6 had a temperature optimum of 60‐70 C while that for adenosine 5′‐triphosphate (pH 5.2) was 50 C. These ctivities of the sediment required no metal co‐factors and were inibited by Fe++, inhibition at the lower pH being greater.

Glucose 6‐phosphate was hydrolyzed by the supernatant with maximum activity between pH 6.0 and 7.2 and a temperature optimum of 50 C. This pH range showed a broad plateau with 2 or 3 minor peaks. The hydrolysis of p‐nitrophenylphosphate showed a similar pH curve. In glucose 6‐phosphate hydrolysis, Mg++ was a required co‐factor but could be replaced by Ni++ or Co++. Ammonium sulfate fractionation precipitated most of the supernatant activity between 50 and 75% saturation.

A modified Gomori technic produced spherical deposits of PbS thruout the cytoplasm of the intact cell. With the electron microscope, Pb phosphate deposition was observed in membrane‐bound vesicles (i.e., lysosomes) approximately 100‐150 mμ in diameter. These organelles were common in the region of the reservoir at the base of the flagellum. Acid phosphatase activity specific for glucose 6‐phosphate as substrate was localized within this basal pocket.
Ultrastructural Observations on the Development of the Microsporidian Protozoon Plistophora hyphessobryconis Schaperclaus*
Authors: LOM JIRI , CORLISS JOHN O.
Published: May 2007

SYNOPSIS. A sequence of developmental stages of Plistophora hyphessobryconis Schaperclaus, a microsporidian protozoan parasite of the muscular tissue of several species of freshwater fishes, was studied with the electron microscope. The youngest stages observed, ca. 4 × 2 μ, have a single nucleus and their plasm contains only ergastoplasmic lamellae and ribosomes. They are surrounded by a halo of lysed host tissue. They increase in volume to become large sporonts with a great number of nuclei and a thick, 2‐layered membrane. Thru schizogony, a corresponding number of sporoblasts is produced within this pansporoblast membrane. Sporoblasts start to develop a thick spore membrane, and a number of smooth‐membraned vesicles appear in the plasm. These vesicles fuse to make the outer membrane of the filament. Later, its inner structures originate—the axial electron‐dense substance, filling the hollow lumen of the filament, and a middle, electron‐transparent layer. The structure of the filament is discussed in relation to its function and with regard to the findings of other authors.

The polaroplast is a laminated structure, originating possibly by transformation of endoplasmic reticulum; the polar cap forms its apical part. The cap is also lamellar; its substance reaches into the lumen of the filament for a certain distance. No micropyle was discovered in the shell; the filament is fastened to the polar cap. These observations on microsporidian development and on the structure of their spores are compared with similar data on myxosporidian species. Such a comparison speaks clearly in favor of the complete taxonomic separation of the Microsporidea from the Myxosporidea, the latter being quite different also from other sporozoa sensu lato.
Nuclear Structure and Mitosis in the Dinoflagellate Gonyaulax monilata*
Authors: CHUNOSOFF LAURA , HIRSHFIELD HENRY I.
Published: May 2007

SYNOPSIS. Nuclear structure and mitosis in Gonyaulax monilata were studied. Between the arms of the U‐shaped interphase nucleus is a band of material which, it is suggested, is homologous with the “central body” of G. tamarensis. Histochemical studies of whole cells, extruded nuclei and Epon‐embedded sections indicate that the band is composed at least in part of protein, phospholipid and possibly RNA. The chromosomes of interphase nuclei are attached to the ends of the band. The band is also attached to a proteinaceous, extra‐chromosomal matrix which pervades the nucleus. Studies on material treated with trypsin indicate that the matrix may be a factor in maintaining chromosomal integrity and orientation and nuclear form. During mitosis the band acts as a point of attachment for the chromosomes, and appears to control anaphase and telophase movements. It is suggested that the band is a component of the mitotic apparatus in G. monilata.
Myxosoma pendula n. sp. (Protozoa, Myxosporida) from the Creek Chub Semotilus atromaculatus*
Authors: GUILFORD HARRY G.
Published: May 2007

SYNOPSIS. A new species, Myxosoma pendula, was found surrounded by tissue fluid with granulocytes in pedunculated cysts formed from the mucous membrane of the gill arches of Semotilus atromaculatus collected in the Kewaunee River in Wisconsin. This species has a spherical vegetative stage with 2‐layered ectoplasm composed of an outer homogeneous layer and an inner layer with canaliculi, and avoid spores that differentiate in the central area of the endoplasm.
The Time of DNA Synthesis During the Interdivision Growth Cycle of Tetrahymena pyriformis Fed on Living Bacteria
Authors: CALKINS JOHN , GUNN GEORGE
Published: May 2007

SYNOPSIS. It has been possible to obtain selective labeling of the macronucleus of Tetrahymena pyriformis fed on living Escherichia coli. The bacteria themselves, a thymidine requiring mutant, were labeled by exposure to tritiated thymidine in a lettuce infusion medium supplemented with trypticase broth. Various patterns of labeling were seen in synchronized Tetrahymena when the radioactive bacteria were given at particular times during the growth cycle. These patterns have been interpreted as indicating the duration of the G1, S, and G2 periods; they also suggest that a soluble pool of thymine exists in this animal from one S period to the next.
Toxicity of Antioxidants to Tetrahymena pyriformis*
Authors: EPSTEIN SAMUEL S . , SAPOROSCHETZ INNA B. , HUTNER S . H.
Published: May 2007

SYNOPSIS. The cytotoxicity of 97 antioxidants of various structural types was determined for Tetrahymena pyriformis grown in a peptone medium. Cytotoxicity fo Tetrahymena, generally, was positively associated with acute oral tomicoiciity to rats but not with antioxidant pdency as measured by the Tetrahymena photodynamic assay for antioxidants. Some commonly used hindered‐phenol, lipidsoluble anttioxidants, e.g., 2,6‐di‐tert.‐butyl‐P‐cresol (BHT), had low toxicity (to Tetrahymena but poor antioxidant activity by the photodynamic test. Nmdihydroguahetic acid, with low toxicity to the rat and high Coxicity (to Tetrahymena, had very high activity in the photodynamic test.
Large‐Scale Autotrophic Culture of Euglena gracilis*
Authors: LYMAN HARVARD , SIEGELMAN H. W.
Published: May 2007

SYNOPSIS. Large quantities of autotrophic Euglena gracilis can be obtained in a short time using simple and inexpensive equipment. Cultures grown in flasks on a rotary shaker are transferred to a polyethylene drum containing 180 liters of medium. The drum, which is illuminated with both internal and external fluorescent lamps, contains a coil of vinyl tubing carrying tap water for temperature control and 2 vinyl tubes for air and CO2. Sterilization of the drum or the medium was unnecessary, but can be accomplished by gassing the drum with ethylene oxide or overnight exposure to germicidal lamps and by dispensing the medium into the drum through a large Millipore apparatus. Yields of 289–330 g of fresh weight material have been obtained after one week's growth. Shorter growth periods yielded 134–160 g of fresh weight material. Ten g of purified chloroplasts have been obtained from 160 g of cells grown in this manner.
A Proposed Life Cycle of Minchinia nelsoni (Haplosporida, Haplosporidiidae) in the American Oyster Crassostrea virginica
Authors: FARLEY C. AUSTIN
Published: May 2007

SYNOPSIS. A developmental sequence is proposed for the haplosporidan Minchinia nelsoni Haskin, Stauber and Mackin, 1966, based on study of oyster infections over the past 5 years in Chesapeake Bay. Uninucleate stages develop by nuclear division into multinucleate plasmodia which proliferate in the tissues by plasmotomy. Relatively small plasmodia containing what are considered to be gametic nuclei originate by unequal plasmotomy of large plasmodia. These have been interpreted to aggregate and fuse to form large plasmodia which contain prozygotes. Pairing and fusion of nuclei occur within each plasmodium to produce zygote nuclei (synkaryons) which undergo division, possibly meiotic, to form sporonts. Sporoblasts differentiate into spores with the development of spore walls and opercula. Cystoid plasmodia develop during times of unfavorable conditions. An anomalous but common sequence involving sexuality and mitosis is described, and the occurrence of various life cycle stages within the host thruout the year is discussed.
Critical Phases of Oral Primordium Development in Tetrahymena pyriformis GL‐C: An Analysis Employing Low Temperature Treatment
Authors: FRANKEL JOSEPH
Published: May 2007

SYNOPSIS. The effects of temperatures of 12–18 C on cell division and oral primordium development were investigated in cultures of synchronized Tetrahymena pyriformis GL‐C. If exposures to 12 or 15 C were initiated prior to a “transition point,” long delays of cell division were generated. After this transition point, cell division could no longer be substantially delayed by exposure to low temperature. The time of the transition point was somewhat earlier with 15 C than with 12 C treatments. At temperatures higher than 15 C long delays of cell division were not generated regardless of time of treatment.

The effects of low temperature on oral morphogenesis were strongly dependent on the stage which was affected. (i) The further development of cells initially in the “anarchic field” stage (stage 1) was immediately blocked at both 12 and 15 C. (ii) Cells initially in the stages of incipient membranelle differentiation (stages 2 and 3) continued to develop at both 12 and 15 C, and formed oral primordia in which all 3 membranelles were clearly differentiated (stage 4). The subsequent progress of these stage 4 primordia depended on the temperature: at 12 C virtually all were resorbed (and cell division was blocked); at 15 C only about 1/3 were resorbed, while the remaining 2/3 completed their development (with the concomitant completion of cell division). (iii) Cells initially in intermediate stages of membranelle differentiation (early stage 4) developed to some extent at 12 C, and then underwent resorpton of oral primordia and blockage of cell division; at 15 C such cells completed their development and division normally. (iv) Cells in which the membranelles and undulating membrane were complete or nearly so (stage 5 and very late stage 4) at the time of the beginning of the cold treatment subsequently finished their development and went thru cell division, even at temperatures as low as 5 C.

These results indicate that in addition to a “stabilization point” which occurs shortly before the completion of membranelle development, there is an earlier change in the primordium at the time of the onset of membranelle development, which renders development much less sensitive to direct interference by low temperature.
Conjugation in Stentor coeruleus
Authors: BURCHILL BROWER R.
Published: May 2007

SYNOPSIS. Sexual reproduction of up to 50% of the cells from 9 cultures of Stentor coeruleus was observed repeatedly for several months. Photomicrographs were taken of mating pairs, and a number of new observations were made, including the ability of well fed cells (containing food vacuoles) to conjugate, the ability of a high percentage of cells (approaching 50%) in a culture to mate at one time, a more detailed description of the region of cell attachment as viewed from the frontal fields of the partner cells, and the ability of one partner to twist off and leave its oral area attached to the other member of the pair.
Freeze‐Preservation of Leucocytozoon simondi Sporozoites in Liquid Nitrogen
Authors: KOCAN RICHARD M. , KELKER NORMAN E. , CLARK DAVID T.
Published: May 2007

SYNOPSIS. Sporozoites of L. simondi were maintained in a viable state for 7 months in liquid nitrogen. Comparison of parasite development initiated with fresh and frozen sporozoites showed a delay in development of each stage studied. Comparisons of prepatency, first elongate gametocytes, peak density of round and elongate forms, anemia and disappearance of megaloschizonts were made. In each phase there was a delay of 2–3 days in ducks infected with frozen sporozoites.
Parauronema virginianum n. g., n. sp., a Marine Hymenostome Ciliate
Authors: THOMPSON JESSE C.
Published: May 2007

SYNOPSIS. Parauronema virginianum n. g., n. sp., a marine hymenostome ciliate is described from the Virginia coast. Structural studies were made on specimens treated with the Chatton‐Lwoff silver impregnation technic and on animals observed with the phase microscope. Particular attention was given to the buccal ciliature and its importance to generic assignment in the order Hymenostomatida.
Infection of Macrophages in Culture by Leptomonads of Leishmania donovani
Authors: MILLER HAROLD C. , TWOHY DONALD W.
Published: May 2007

SYNOPSIS. Peritoneal macrophages from hamsters were monolayered on coverslips in Leighton tubes. Twenty‐four hours later these were transferred to a perfusion chamber. Leptomonads were added with fresh medium and the infection process observed with the aid of phase contrast. In the perfusion chamber free‐swimming leptomonads attached to the macrophage by the tip of their flagella. Shortly after this initial attachment the macrophage extended a narrow pseudopodium around the flagellum which eventually reached and enveloped the body of the parasite. Upon complete envelopment the pseudopod containing the leptomonad was retracted into the central body of the macrophage. When first seen in the granular endoplasm of the macrophage, most of the leptomonads appeared to be surrounded by vacuoles. In most cases these vacuoles disappeared in a few minutes making it difficult to distinguish the parasite from the host cell cytoplasm.

Leptomonads also were added directly to Leighton tube cultures, and the coverslips with the adherent macrophages and parasites were removed, fixed and stained periodically during the infection process. In these preparations most of the parasites were in clumps in the vicinity of macrophages. Details of the ingestion of the clumps could not be seen, but occasionally a single organism was seen with its flagellum and part of its body enclosed by an extended pseudopod. Most of the intracellular leptomonads were in large vacuoles. Forms intermediate between elongate leptomonads and LD bodies were surrounded by smaller vacuole‐like spaces. The halo‐like vacuoles most frequently seen around LD bodies may have been fixation artifacts. Under favorable conditions the leptomonads transformed to LD bodies in 1–4 hours, but it was 48 hours before a population increase could be found.
Generic Criteria for Flabellula, Rugipes and Hyalodiscus, With Descriptions of Species*
Authors: PAGE FREDERICK C.
Published: May 2007

SYNOPSIS. Six strains of amoebae isolated from freshwater habitats and having broad, flattened locomotive forms were studied in clonal cultures, with attention to trophic structure, nuclear division, cyst structure in those strains which formed cysts, some aspects of cytochemistry, and other characteristics.

Three strains were found to belong to the genus Flabellula, one being identified as F. platypodia (Gläser, 1912) and the other 2 as F. mira Schaeffer, 1926. The new species Rugipes placidus is described. One strain, identified as belonging to the species originally called Amoeba actinophora Auerbach, 1855, is re‐described as Hyalodiscus actinophorus, and a similar strain is described as H. actinophorus var. minor n. var.

All 3 strains of Flabellula had the unusual type of mitotic figure reported by Gläser for F. platypodia but not previously studied with the Feulgen technic. The genus Rugipes has the mitotic pattern more common to small amoebae and is distinguished from Flabellula partly on that basis. Both strains of Hyalodiscus have division figures of this common type.

Of the strains included in this investigation, only R. placidus and H. actinophorus formed cysts in culture. The cysts of neither species were viable after one year at room temperature and humidity.

The status of Rugipes as distinct from Flabellula is discussed. The genus Hyalodiscus is interpreted in a manner compatible with the original definition of Hertwig and Lesser and is included within the order Amoebida. The strains of this genus isolated have a doubly contoured, strongly PAS‐positive covering over the endoplasmic hump.

Some criteria for the taxonomy of amoebae are evaluated in the light of work reported in this and 2 previous papers.
Electron Microscopic Observations on the Symbiosis of Paramecium bursaria and its Intracellular Algae*
Authors: KARAKASHIAN STEPHEN J. , KARAKASHIAN MARLENE W. , RUDZINSKA MARIA A.
Published: May 2007

SYNOPSIS. Observations were made on the fine structure of Paramecium bursaria and its intracellular Chlorella symbionts. Emphasis was placed on the structure of the algae and structural aspects of the relationship between the organisms.

The algae are surrounded by a prominent cell wall and contain a cup‐shaped chloroplast which lies just beneath the plasma membrane. Within the cavity formed by the chloroplast are a large nucleus, a mitochondrion, one or more dictyosomes, and numerous ribosomes. The chloroplast itself is made up of a series of lamellar stacks each containing 2–6 or more thylakoids with a granular stroma and starch grains intercalated between the stacks. The thylakoid stacks of mature algae are frequently more compact than those of recently divided algae. A large pyrenoid is located within the base of the chloroplast. It is made up of a granular or fibrillar matrix surrounded by a shell of starch. The matrix is bisected by a stack of 2 thylakoids. Prior to the division of the chloroplast the pyrenoid regresses; pyrenoids subsequently form in the daughter chloroplasts thru condensation of the matrix material and the reappearance of a starch shell. This shell appears to be formed by the hollowing‐out of starch grains already present in the chloroplast stroma. Accordingly, in this case, starch moves from the stroma to the pyrenoid.

The algae are located thruout the peripheral cytoplasm of the Paramecium. Each alga is located in an individual vacuole except immediately following division of the algae when the daughter cells are temporarily located in the vacuole which harbored the parental cell. Shortly thereafter the vacuole membrane invaginates, thereby isolating the daughter algae into individual vacuoles. Degenerating symbiotic algae are seen; because these are frequently found in vacuoles with bacteria, they are presumed to be undergoing digestion. Due to the conditions of culture these algae could have been either of intracellular or extracellular origin.
Redescriptions of Uronema filificum and U. elegans*
Authors: THOMPSON JESSE C. , KANESHIRO E. S.
Published: May 2007

SYNOPSIS. Two species of hymenostome ciliates, Uronema filificum, and U. elegans, are described from the Atlantic coast. Studies were made on specimens treated with the Chatton‐Lwoff silver impregnation technic, and particular attention was given to the buccal infraciliature.
Some Observations on the Biology of Tintinnopsis sp.*
Authors: GOLD KENNETH
Published: May 2007

SYNOPSIS. Technics are described for isolating and maintaining Tintinnopsis sp. in vitro. The principal factors which have made cultivation possible appear to be low temperature, a mixture of live algal foods, and control of the bacteria in the medium. A constant supply of material in good physiologic condition is now available for nutritional and developmental studies.
Guanine Metabolism in Carbon‐Limited Euglena gracilis
Authors: SCHUIT K. E. , BUETOW D. E.
Published: May 2007

SYNOPSIS. Guanine‐8‐3H is not a specific label for nucleic acids in Euglena gracilis (strain SM‐L1, streptomycin‐bleached), but is incorporated into all biochemical fractions. Autoradiographic results show that guanine is metabolized in, both the nucleus and the cytoplasm of these Eugelna, but nuclear metabolism of guanine occurs only at a very low level in carbon‐limited cells. Further, carbon‐limited Euglena incorporate less total guanine than do control Euglena in a comparable time period. However, the majority of label incorporated into the nucleic acid fraction of the carbon‐limited cells is incorporated into RNA.
L'Organisation Ultrastructurale Corticale de la Gregarine Lecudina pellucida; ses Rapports avec l'Alimentation et la Locomotion
Authors: VIVIER E.
Published: May 2007

SYNOPSIS. The structure of the cortical region (epicyte and ectoplasm) of the gregarine Lecudina pellucida, an intestinal parasite of the polychete worm Perinereis cultrifera was studied by electron microscopy.

The epicitary folds have 3 unit type membranes. Between the 1st and 2nd is a layer probably composed of fine longitudinal fibrils which has an arch‐like or gutter‐like structure at the crest of the folds. Inside these folds is cytoplasm without any noticeable differentiation or inclusion except for a granular (or finely fibrillar) layer under the limiting inner membrane and close to it.

The ectoplasmic zone of the entocyte is separated from the epicitary region by a lengthwise discontinuous cylindrical opaque layer, inwardly tangential to the folds. The ectoplasm lacks paraglycogen granules but has various organelles: apparently pinocytic vesicles against the wall between the folds, vesicles with myelinic membranes, opaque granules, a few mitochondria with blistered internal vesicles, and a few circular tubular fibers.

The superficial zone of the gregarine is supposed to contribute to nutrition, thru the extensive surface furnished by its folds and thru the pinocytic vesicles; but this alimentary intake is incomplete compared with that of the previously studied anterior region.

Insufficient mucus is discharged to account for locomotion. There are some circular ectoplasmic fibers, but locomotory myonemes are completely absent. However, there are deformations of the folds and corresponding waves that could account for locomotion by creeping or swimming. These movements of the folds might be due to the action of the contractile proteins and correspond with some of the layers seen in the wall.