ALBERT

Notes: One third of a collection of cloned Stylonychia pustulata micronuclear DNA PstI fragments were found to be of a similar size, consistent with their being members of a repetitious sequence family with a repeat size of about 160 base pairs. Cross-hybridization experiments confirmed that these small cloned fragments are related by sequence homology. Hybridization of the cloned repetitious sequences to PstI digested micronuclear DNA revealed a “ladder” of bands (step size = 160 base pairs), indicating that the repeats are found in tandem arrays. This is the first demonstration of highly repetitious, tandemly repeated sequences in a ciliated protozoan.

Notes: The erythrocytic developmental cycle of Plasmodium falciparum can be conveniently divided into the ring, trophozoite, and schizont stages based on morphology and metabolism. Using highly synchronous cultures of P. falciparum, considerable variation was demonstrated among these stages in sensitivity to chloroquine. The effects of timed, sequential exposure to several clinically relevant concentrations of chloroquine were monitored by three techniques: morphological analysis, changes in the rate of glucose consumption, and changes in the incorporation of 3H-hypoxanthine into parasite nucleic acids. All three techniques gave essentially identical results. The trophozoite and schizont stages were considerably more sensitive to the drug than ring-stage parasites. Chloroquine sensitivity decreased as nuclear division neared completion. The increase in chloroquine sensitivity was coincident with a marked rise in the rate of glucose consumption and nucleic acid synthesis. The rate of nucleic acid synthesis decreased as schizogony progressed while glucose consumption continued at high rates during this process. The degree of chloroquine sensitivity was not highly correlated with either metabolic activity.

Notes: Bloodstream trypomastigote and culture procyclic (insect midgut) forms of a cloned T. rhodesiense variant (WRATat 1) were tested for agglutination with the lectins concanavalin A (Con A), phytohemagglutinin P (PP), soybean agglutinin (SBA), fucose binding protein (FBP), wheat germ agglutinin (WGA), and castor bean lectin (RCA). Fluorescence-microscopic localization of lectin binding to both formalin-fixed trypomastigotes and red cells was determined with fluorescein isothiocyanate (FITC)-conjugated Con A, SBA, FBP, WGA, RCA, PNA (peanut agglutinin), DBA (Dolichos bifloris), and UEA (Ulex europaeus) lectins. Electron microscopic localization of lectin binding sites on bloodstream trypomastigotes was accomplished by the Con A-horseradish peroxidase-diaminobenzidine (HRP-DAB) technique, and by a Con A-biotin/avidin-ferritin method. Trypomastigotes, isolated by centrifugation or filtration through DEAE-cellulose or thawed after cryopreservation, were agglutinated by the lectins Con A and PP with agglutination strength scored as Con A 〈 PP. No agglutination was observed in control preparations or with the lectins WGA, FBA or SBA. Red cells were agglutinated by all the lectins tested. Formalin-fixed bloodstream trypomastigotes bound FITC-Con A and FITC-RCA but not FITC-WGA, -SBA, -PNA, -UEA or -DBA lectins. All FITC-labeled lectins bound to red cells. Con A receptors, visualized by Con A-HRP-DAB and Con A-biotin/avidin-ferritin techniques, were distributed uniformly on T. rhodesiense bloodstream forms. No lectin receptors were visualized on control preparations. Culture procyclics lacked a cell surface coat and were agglutinated by Con A and WGA but not RCA, SBA, PP and FBP. Procyclics were not agglutinated by lectins in the presence of competing sugar at 0.25 M. The expression of lectin binding cell surface saccharides of T. rhodesiense WRATat 1 is related to the parasite stage. Sugars resembling α-D-mannose are on the surface of bloodstream trypomastigotes and culture procyclics; n-acetyl-D-galactosamine and D-galactose residues are on bloodstream forms; and n-acetyl-D-glucosamine-like sugars are on procyclic stages.

Notes: The cationic permeant fluorescent dye rhodamine 123 (R123) was used to stain Plasmodium yoelii-infected mouse erythrocytes. Fluorescence microscopic observations demonstrated that the parasite, but not the matrix of the infected erythrocyte, accumulated the dye. Differences in fluorescence intensity could not be found at the various developmental stages of the parasite; however, quantitation of the cell-associated dye revealed an increase in R123 uptake with parasite development. The retention of the parasite-associated dye, as measured by fluorescence microscopy and spectrophotometry after extraction of R123 with butanol, was markedly reduced by treatment of the infected erythrocytes with a proton ionophore, carbonyl cyanide m-chlorophenylhydrazone (CCCP), and an inhibitor of proton ATPase, dicyclohexylcarbodiimide (DCCD). These results indicate that the accumulation and retention of R123 in P. yoelii reflect the parasite membrane potential and suggest that the parasite plasma membrane has a membrane potential-generating proton pump.

Notes: Distinctive organic-walled resting cysts of at least three different types with a highly conservative morphology appear to characterize specific orders or groups of genera within the Class Polyhymenophorea (Protozoa, Ciliophora), contrasting markedly with the great diversity of form seen in trophic stages. Polyhymenophorean ciliates have been considered in the past to form a cohesive class within the Phylum Ciliophora and, possibly, to represent the pinnacle of ciliate evolution. Evidence from cysts challenges the cohesive nature of the class, suggesting that the hypotrichs should be subdivided and that they have a different phylogenetic origin from the heterotrichs, tintinnids, and oligotrichs.

Notes: Yellow-brown, algal symbionts varying in diameter from approximately 5 μ m to 20 μ m, associated with solitary Radiolaria with spongiose skeletons (i.e. Spongodrymus sp.), exhibit fine structural features resembling the Prymnesiida (botanical class, Prymnesiophyceae). A large central vacuole is surrounded by a thin layer of cytoplasm containing plastids with lamellae composed of three thylakoids and granular pyrenoids with internal tubules immersed between the thylakoids. The pyrenoids lack internal thylakoid membranes. The nucleus is surrounded by a dilated cisterna of the nuclear envelope that also encloses the plastids and gives rise to saccules of the endoplasmic reticulum. The algal symbionts appear coccoid; hence no flagella nor surface scales were observed. The symbiont fine structure is compared to similar yellow-brown symbionts associated with Acantharia. Thus far, three kinds of algal symbionts have been observed to be associated with solitary Radiolaria: dinoflagellate, prasinomonad, and this apparent prymnesiomonad.

Notes: Ultrastructural observations of the cortically-located mitochondria of Tetrahymena thermophila revealed associations not only between the mitochondria and certain of the cortical microtubule bands, but also between the mitochondria and the epiplasm of the cortex. Most of the distal mitochondrial surface is close and parallel to the epiplasm; favorable views show bridge-like structures spanning the 20–10 nm gap between the mitochondrion and the epiplasm.Previous studies have shown that the placement of mitochondria in the cortex appears to be determined by certain of the cortical microtubule bands. This study, however, shows that mitochondrion-microtubule interactions account for only a small proportion of the total mitochondrial area associated with the cortex; the rest is accounted for by the epiplasm. A possible analogue of the spectrin layer of erythrocyte membranes, the epiplasm may be important in helping to arrange the intricately organized components of the ciliate cortex. Its involvement in apparently helping to “moor” mitochondria to their cortical sites is the first suggestion of any role in cell patterning played by the epiplasm.

Notes: Ce Tetradimorpha, rencontre en eau douce se présente soit sous forme sphérique pourvue de quatre flagelles et d'axopodes rayonnants, soit sous forme allongée avec a l'avant quatre flagelles associes a quatre axopodes et a l'arriére six a huit axopodes divergents. L'etude ultrastructurale révèle un cytosquelette axopodial de type centroplastidie comprenant un centroplaste lenticulaire homogéne, centre organisateur des quatre axopodes anterieurs et des six a huit axopodes posterieurs, auquel s'ajoutent les quatre cinetosomes des flagelles anterieurs. En outre, un deuxiéme éleément cytosquelettique incluant un microtubule associe chacun des quatre cinetosomes a l'axopode antérieur correspondant. Des cordons microfibrillaires réunissent axopodes et cinetosomes au niveau du centroplaste, puis a quelque distance du centroplaste les axopodes posterieurs. Les axonémes des axopodes comprenant de 5 a 30 microtubules sont constitues de triades, lorsqu'on peut détecter une organisation. Le noyau, a nucléole central est coince dans le cone axopodial posterieur, lui-méme entouré des dictyosomes. Par l'organisation du cytosquelette, par la structure des kinétocystes, par la structure des flagelles dépourvus de mastigonémes tubulaires, Tetradimorpha différe nettement de Ciliophrys marina. Comme le prévoyait Davidson (1975), il represönte bien un des chainons dans la série évolutive des Héliozoaires centrohélidiens. Mais il ne présente guère d'affinites avec les Chrysomonadines considerees comme la souche des Héliozoaires. L'intéret de ce Protiste dans l'étude de la differentiation et de l'evolution du cytosquelette est également présente.〈section xml:id="abs1-2"〉〈title type="main"〉ABSTRACTThis freshwater species of Tetradimorpha has a spherical body with four flagella and radiating axopods; it transforms into a pear-shaped cell that anteriorly has four flagella intercalated between four axopods and posteriorly has six to eight divergent axopods. Ultrastructural study reveals an axopodial cytoskeleton of the centrohelidan type comprising an homogeneous lenticular centroplast which acts as MTOC for axopodial microtubules. A second skeletal element is a microtubular linkage between the kinetosomes and the axonemes of anterior axopods. A microtubule embedded in dense material diverges from near the base of each kinetosomes and parallels the distal portion of the axoneme of each anterior axopod. A microfibrillar envelope around the centroplast links the axopodial bases to the kinetosomes situated just above. Close to the centroplast, microfibrillar strands link the axopodial axonemes to the kinetosomes. Axopodial axonemes are composed of 5 to 30 microtubules irregularly arranged except for some that form equilateral triangles. The nucleus containing a central nucleolus is constrained within a cone formed by the axonemes of the posterior axopods and surrounded by dictyosomes. By the cytoskeletal organization, the structure of kinetocysts, and flagella wthout tubular mastigonemes, Tetradimorpha differs obviously from Ciliophrys marina. As Davidson (1975) predicted, Tetradimorpha is an intermediate link in the centrohelidan lineage: however, it lacks the characteristics of chrysomonads, the supposed ancestors of Heliozoa. The contribution of this genus to the study of the differentiation and the evolution of the cytoskeleton is also presented and discussed.

Notes: Two-dimensional gel electrophoresis was used to identify the patterns of protein synthesis during initiation, and the patterns of membrane protein expression following initiation, in all of the mating types of the Tetrahymena thermophila B family. In addition, one-dimensional analysis was used to survey 125I-Concanavalin A-binding proteins. Although a large number of proteins was identified by each technique, no variation among the mating types was observed.

Notes: Cells of Tetrahymena pyriformis, T. thermophila, and Euglena gracilis were saturated with nitrogen gas at pressures up to 300 atm and rapidly decompressed. Damage was assessed by measuring post-decompression cell fragmentation or viability. Occurrence of intracellular bubbles was determined by cinephotomicrography performed during the decompression or by direct observations afterwards. The extreme gas supersaturations induced led to intracellular bubble formation and rupture in cells of Tetrahymena that contained food vacuoles, but only with supersaturations of 175 atm or higher; 225 atm left few cells intact. Bubbles were never observed in cells of Euglena or in Tetrahymena cells freed of food vacuoles, even when they were decompressed from substantially higher nitrogen supersaturations. Cells of Euglena were most resistant and were unaffected by supersaturations up to 250 atm.

Notes: The rapid, synchronous differentiation of N. gruberi from amoebae to flagellates is a useful paradigm to study aspects of cell differentiation, including regulation of the synthesis of proteins that are related to the changes in cell shape and motility, which occur during differentiation. The differentiation requires synthesis of new RNA and protein molecules to accomplish defined morphogenetic events. Specific new proteins, including the tubulins that form the flagellar microtubules, are synthesized at various times during differentiation, and particular mRNA species appear and disappear. The time course of the synthesis of the α and β subunits of flagellar tubulin is paralleled by the programmed appearance and disappearance of flagellar tubulin mRNAs. The evidence supports the hypothesis that the synthesis of flagellar tubulin is regulated by the transcription, and subsequent disappearance, of flagellar tubulin mRNA. Translatable mRNAs for two calmodulin-like calcium-binding proteins appear and disappear contemporaneously with those for flagellar tubulin. During differentiation the synthesis of actin, the major protein of amoebae, is selectively shut down, and translatable actin mRNA rapidly disappears. This description of the orderly appearance, utilization, and disappearance of the mRNAs for actin, calcium-binding proteins, and flagellar tubulin during differentiation provides means and motivation to investigate the mechanisms that regulate these events.

Notes: Earlier experimental work involving macronuclear implants in Stentor coeruleus has shown that the cytoplasmic cortex of the nuclear site 1) attracts the macronucleus and 2) holds it in place during interphase. Now experiments indicate macronuclei transferred with overlying cortex elongate in the direction of the transferred cortical pigment stripes, whether or not the transferred stripes realign in the direction of the host stentor's stripes. Therefore the third function of the cortex is to determine the direction of elongation and thus assure that both daughter cells at division receive part of the macronucleus.

Notes: During an electron microscopic study of Glugea stephani, three morphologically distinct tubular appendages that are continuous with the sporoblast plasmalemma were observed. The tubules were designated as: type I, 45–50 nm in diameter and 600–900 nm in length; type II, 25–35 nm in diameter, averaging 1300 nm in length; type III, 50–70 nm in diameter and with an indeterminate length, which often exceeds 3000 nm. Type III tubules contain regularly spaced, electron-dense particles that are approximately 30 nm in diameter. Since many genera of microsporida have some type of appendage, which may eventually be utilized for taxonomic purposes, we propose the formation of a system of serially numbered detailed descriptions of these structures to promote uniformity and clarity in future publications.

Notes: Cells of Paramecium tetraurelia, stock hrd, cultured in a micro-capillary containing 1 μl fresh culture medium, expressed mating activity through the whole cell cycle. Mating-reactive G2 phase cells can conjugate with cells of other phases. The G2 phase cells, which have double (4C) the normal micronuclear DNA content, undergo pre-meiotic DNA synthesis when conjugated with G1 phase cells. The micronucleus of the progeny from the cross between a G1 and a G2 cell becomes triploid.

Notes: Buffered solutions of KCl and NaCl were tested for their stimulatory effect on the germination of variously-aged spores of Vavraia culicis. Germination was optimal in 0.2 M KCl, pH 6.5 for one isolate, and, for another isolate, peaks of germination occurred at pH 7.0 and 9.5. Spores incubated for several hours in suboptimal solutions became unable to germinate under optimal conditions. After being returned to water, they regained their ability to germinate. Calcium chloride, magnesium chloride, and ammonium chloride inhibited germination. After ingestion by mosquito larvae, spores germinated near the posterior end of the midgut.

Notes: . Leishmania tropica promastigotes transport α-aminoisobutyric acid (AIB), the nonmetabolizable analog of neutral amino acids, against a substantial concentration gradient. AIB is not incorporated into cellular material but accumulates within the cells in an unaltered form. Intracellular AIB exchanges with external AIB. Various energy inhibitors (amytal, HOQNO, KCN, DNP, CCCP, and arsenate) and sulfhydryl reagents (NEM, pCMB, and iodoacetate) severely inhibit uptake. The uptake system is saturable with reference to AIB-and the Lineweaver-Burk plots show biphasic kinetics suggesting the involvement of two transport systems. AIB shares a common transport system with alanine, cysteine, glycine, methionine, serine, and proline. Uptake is regulated by feedback inhibition and transinhibition.

Notes: . Oxytricha strains used in biochemical studies have traditionally been grown in unaerated, unagitated culture tubes or Fernbach flasks. These cultures are limited in volume to about one liter and have a very nonuniform distribution of cells, with the majority of the cells at the very top or bottom of the medium. We have found conditions in which Oxytricha can be grown in 50-liter fermentation vats. The cultures grow to a uniform density of about 6000 cells/ml.

Notes: . The fine structure of the tomite of Foettingeria actiniarum (Claparède) was examined and compared with that of other apostome tomites. This stage in the life cycle has a unique configuration of kineties that form a spiral through the cytoplasm in the interior of the body. The structure and behavior of this internal spiral were evaluated as a mechanism for the storage of kinetosomes, an adaptation to the ciliate's two-host life cycle. The spiral is composed of nine ribbons of laterally compressed kinetosomes that are in contact with a thin electron-dense fibril. Paralleling the kineties of the spiral are conspicuous, swollen lamellae of the rough endoplasmic reticulum; these lamellae contain moderately electron-dense material. The spiral is associated with the large contractile vacuole and winds about the macronucleus. The tomite of Foettingeria possesses a single, robust, caudal cilium located in a pit, along with the nozzle-like pore of the contractile vacuole. The walls of the pit contain several trichocysts arranged radially about the caudal cilium and aimed into the pit.

Notes: . Fine structural studies of a specialized vesicle system associated with the endoplasmic reticulum (ER) of exo-erythrocytic Plasmodium berghei suggest that this system may be the equivalent of a Golgi apparatus. Patches of ER, randomly distributed in the cytoplasm of developing parasites, are formed of smooth and ribosome-studded cisternae intermingled with each other. The vesicle systems are located between as well as at the edges of ER aggregates and appear to be in different stages of budding from the cisternae. Prolonged osmication reveals distinct staining of the nuclear envelope and ER of the parasites as well as part of the Golgi apparatus of the hepatocytes. However, the small vesicles associated with the parasite's ER are unstained, as are the coated vesicles in the Golgi region of the liver cell. These sites in the parasite cytoplasm seem comparable to the concave surface of the Golgi apparatus in liver cells. The pinched-off vesicles fuse with others to form the prominent peripheral vacuolization characteristic of the nearly mature exo-erythrocytic form. The formation of these peripheral vacuoles and their subsequent fusion with the parasite membrane may be an exocytosis mechanism supplying the rapidly expanding parasite with new plasma membrane material.

Notes: . Ultrastructural cytochemical techniques were used to analyze the nucleus and the kinetoplast of epimastigotes of Trypanosoma cruzi. With the use of ethanolic phosphotungstic acid, which detects basic proteins, reaction product was seen in the chromatin and at the periphery of the kinetoplast. Thallium alcoholate, which interacts with DNA, stained strongly the whole kinetoplast and the chromatin. With the use of a silver impregnation method that detects acidic nucleolar proteins, silver granules were seen preferentially located in the central region of the nucleolus. With the EDTA method, which reveals the presence of ribonucleoproteins, staining was observed in the nuclear pores. Also 6–8 nm fibrils, 25 nm and 40 nm granules, which correspond to the perichromatin fibers, interchromatin granules and the perichromatin granules, respectively, were identified in the nucleus. The EDTA method also revealed the presence of 40 nm granules in the kinetoplast. These granules were seen mainly at the two extremities of the kinetoplast. Freeze-fracture images indicate that the nuclear membrane contains ca. 9 pores/μm2 of nuclear surface area. The mean diameter of the pores was 80 nm. All these results suggest that epimastigotes of T. cruzi have a very active nucleus and a high rate of nucleocytoplasmic interchange.

Notes: . Micronuclear mitosis in living Spirostomum teres has been studied by sensitive polarization microscopy, and the dynamic aspects of micronuclear division are described. The small, spherical, interphase micronuclei lie in form-fitting depressions in the macronuclear surface. Nuclear division begins with the rounding and slight swelling of the macronucleus and, coincidentally, the micronuclei move out of the depressions and away from the macronucleus, increase in size, and become weakly birefringent. As mitosis proceeds, the micronuclei increase in uniaxial birefringence and elongate to form irregular ovoids that convert to angular structures displaying principal axes of positive birefringence so divergent as to appear oriented at a right angle to one another. Micronuclei maintain this appearance for as long as 60 min and then abruptly change to rectangular-shaped structures, increase in uniaxial birefringence, and begin anaphase elongation. The somewhat dumbbell-shaped micronuclei lengthen at the constant rate of 2.0 μm/min to reach lengths 〉70 μm. It appears that little half-spindle shortening occurs during spindle elongation. Accompanying the changes in micronuclear spindle length are changes in birefringence. Just before elongation begins, presumably metaphase, the micronucleus is uniformly and intensely birefringent. At the magnifications employed, a chromosome plate is not clearly visible as a region of reduced birefringence. As elongation begins, the putative half-spindles are more birefringent than is the interzone, a condition that is maintained until the spindles have achieved ∼30% elongation, at which time a region of increased birefringence develops at the center of the interzone. This pattern persists for a very short time, then gives way to a uniform birefringence of the entire separation spindle that is maintained until elongation is completed. The rate of micronuclear spindle elongation, changes in micronuclear dimensions, and corresponding changes in birefringence are discussed with respect to possible mechanisms of mitosis.

Notes: . Studies performed with the basidiomycete Laccaria trullisata collected from the sandy beach at the Hempstead Lake State Park, Long Island, New York, during the growing seasons of 1979 and 1980, have demonstrated a carposphere (equivalent to rhizosphere) effect. This region exerts a positive influence on the population density of amoebae when numbers are compared with those obtained in the bare sand 5 cm away. Moreover, amoebae have been shown to exist in, and have been recovered from, internal tissue of the cap (72%) and stalk (91%) of these mushrooms. A partial characterization of three strains of amoebae isolated from the internal tissue of L. trullisata and established in clonal culture is presented.

Notes: L'étude, par le protargol, des phénomènes infraciliaires et de leur corrélation avec les phénomènes nucléaires au cours de l'autogamie dans le genre Euplotes montre, par comparaison avec la conjugaison, que les diverses étapes de la morphogenèse sont liées à la progression de l'état nucléaire. Par ailleurs, l'étude comparative des différents types de morphogenèse (bipartition, phénomena sexuel, réorganisation induite par le jeǔne) permet de supposer qu'il existe deux territoires morphogènes soumis à des systèmes de régulation bien distincts. La comparaison des séquences de morphogenèse chez divers hypotriches conduit à dresser un plan général d'évolution de la régulation de l'activité corticale en relation avec l'étendue des remaniements associés à la stomatogenèse.〈section xml:id="abs1-2"〉〈title type="main"〉ABSTRACTThe changes in the arrangement of the infraciliature associated with autogamy in Euplotes are described and compared with similar events associated with conjugation. The successive steps of morphogenesis are strongly correlated with nuclear processes. The comparative study of different types of morphogenesis (binary fission, sexual phenomena, starvation-induced reorganization) leads to the hypothesis that two morphogenetic fields (a ventral one and a dorsal one) depend on separate regulatory systems. From the viewpoint of evolution, the morphogenetic sequences of some hypotrichs have been compared. A general scheme of the evolution of cortical regulation is proposed, taking into account the extension of the area concerned with stomatogenic activity.

Notes: Mouse omentum was studied after intraperitoneal challenge with tachyzoites of Toxoplasma gondii. Parasites inhabit omental histiocytes, fibroblasts, mesothelial cells, and free peritoneal macrophages. Recently infected cells showed enhanced metabolic and functional activity. Villous projections of the parasitophorous vacuole wall appeared, usually opposite the anterior pole of the parasite. In mesothelial cells, projections formed terminal swellings not observed in other infected cells. Activation of host cells was followed by reduction of the density of the cytoplasmic matrix, autophagosome formation, and intracellular edema, indicating the damage. The wall of the parasitophorous vacuole loses the supporting host cell endoplasmic reticulum that was attached to the vacuole just after entrance of the parasite into the cell. Then lysis of the parasitophorous vacuole and complete cell destruction occurs. The growth of parasites in undamaged cells does not coincide with the inflammatory response. Inflammation of the peritoneum develops only after the start of mass destruction of infected cells. Thus tachyzoites of Toxoplasma exert significant pathogenic effects by their ability to activate the host cell, causing lysis of the parasitophorous vacuole and subsequent destruction of the entire cell.

Notes: Discophrya collini is a free-living suctorian with retractile tentacles covered by a thick fibrous cortex. The tentacles contain a microtubular central canal surrounded at the base by a fibrous collar. Electrical stimulation induces a reproducible tentacle retraction. With extracellular electrodes, the tentacles nearest the anode respond initially, contracting by up to 75% of their original length. There is an inverse relationship between voltage level and duration of stimulus in producing a threshold response, and at a set voltage, between duration and degree of retraction. With intracellular electrodes, the membrane potential has been measured as -30 mV, and tentacle retraction occurs in response to as little as 1.25 nA when the intracellular electrode is made the cathode of the circuit. SEM studies show that retracted tentacles have a wrinkled cortex, while TEM shows that the microtubular canal bends as it enters the cytoplasm. No consistent changes occur in the microtubule configuration of the canal on retraction, suggesting that the microtubules are not directly involved in the contractile mechanism.

Notes: A rapid in vitro prescreen for Fe-binding chelators has been developed with growth of Crithidia fasciculata and the sparing of its heme requirement in a defined medium as a test system. The prescreen functions as an index of chelator-mediated Fe transport and as an index of growth inhibition, presumably by the interference with Fe and/or heme metabolism at intracellular chelatable sites. Of 161 chelators examined, 84 were active heme-sparers; 32 of these inhibited growth at low chelator concentrations. Twenty-eight other chelators inhibited growth and another 49 were inactive. Such chelating activity directed at Fe and heme targets in hemoflagellates may provide leads for chemotherapy.

Notes: Study of microorganism growth kinetics requires measurement of maximal specific growth rate. Standard methods of measurement-batch, semicontinuous and continuous steady state-have sources of imprecision that can be substantially reduced by a modification of the continuous steady-state method. Data are presented, using the ciliate Tetrahymena pyriformis, that indicate that the theoretical foundation of the new method is firm and that precision can be increased.

Notes: Viable merozoites of Plasmodium knowlesi were isolated and the proteins that were labeled on intact merozoites by lactoperoxidase-catalyzed radioiodination were identified. Sodium dodecyl sulfate polyacrylamide gel electrophoresis and autoradiography of Triton soluble extracts of labeled merozoites demonstrated eight major bands ranging in apparent molecular weight from 150,000 D to 22,000 D. Exposure of intact merozoites to trypsin (10 μg/ml) for 10 min resulted in the loss of the two highest molecular weight proteins (150,000 D and 105,000 D) and the appearance of two new bands at 70,000 D and 62,000 D. Trypsin treatment under these conditions also removed the receptor(s) for merozoite attachment to erythrocytes. Therefore, these high molecular weight proteins are candidates for the merozoite component that attaches to erythrocytes. There was no evidence that the labeled membrane components were serum or erythrocyte membrane components, two potential contaminants in the preparation. Anti-rhesus erythrocyte antibody did not precipitate labeled merozoite proteins. Furthermore, the immunoprecipitation of labeled merozoite proteins by rhesus anti-merozoite serum was not inhibited by erythrocyte ghosts.

Notes: Species of trypanosomatids without endosymbionts (Leptomonas seymouri, L. collosoma, L. samueli, Crithidia fasciculata, C. luciliae, C. acanthocephali, Herpetomonas megaseliae, H. mariadeanei, H. samuelpessoai, H. muscarum muscarum, Trypanosoma cruzi) and species of trypanosomatids with endosymbionts (Crithidia deanei, C. oncopelti, Blastocrithidia culicis) were comparatively studied by means of electron microscopy. Artificially aposymbiotic strains derived from species with symbiont were also included in the survey. Species with symbiont were found to differ in some ultrastructural aspects from the group of species without symbiont. Paraxial rods of flagella or intraflagellar structure were found exclusively in species without symbiont. Peripheral branching of mitochondria, accompanied by absence of subpellicular microtubules in sites where the mitochondrial branches are appressed to the cell membrane, were found exclusively in species with symbiont. Networks of kinetoplast DNA fibrils were found to be larger and looser in species with symbiont. Symbiont-free strains of species with symbiont retained the same morphological characteristics of their parental species.

Notes: During a freeze-fracture electron microscopical study of the plasma membrane of Tetrahymena, several different types of organized particle assemblies were observed. Three of these were found only on the protoplasmic face and were localized in the anterior-ventral region of the cell. These consisted of plate-like arrays composed of 4–25 triplet rows of small 3–4 nm particles; long, paired linear arrays localized at the tops of cortical ridges and composed of 7–8 nm particles; and elongated tetragonal arrays located in the grooves between ridges and composed of approximately 10 nm particles. The distribution of these arrays is consistent with roles in cellular morphogenesis, chemoreception, or cell-cell pairing during conjugation. In addition, a unique particle track associated with the cytoproct (anal pore) was observed in the external face of the plasma membrane. Furthermore, the protoplasmic face of the plasma membrane is characterized by a high density of particles organized into localized microarrays, consisting of small paracrystals or strings, which exhibit a loose higher-order patterning most evident toward the anterior end of the cell. Particle distributions on the protoplasmic face do not appear to be significantly altered by conditions that cause clumping of alveolar membrane particles. Taken together, these observations are consistent with the idea that the proteins of the plasma membrane are highly ordered and relatively immobile and that the structure of the plasma membrane is regionally differentiated.

Notes: . A new species of Dactylosoma (Dactylosomatidae, Piroplasmia), for which the name Dactylosoma hannesi n. sp. is proposed, was discovered in blood erythrocytes of Mugil cephalus, Liza richardsoni, and L. dumerili (Mugilidae) from Swartkops estuary, located east of Port Elizabeth, South Africa. The life cycle of this species differs in some respects from that described for all other known species of Dactylosoma and Babesiosoma. Mature schizonts contain eight nuclei but undergo division only to two to four daughter cells. During cytoplasmic cleavage, schizonts assume triad, rosette, or cruciform shapes. Merozoites are finally produced through a series of binary fissions of these daughter cells which may also be involved in additional nuclear divisions.

Notes: Electron microscopy was used to examine the flagellar apparatus of Herpetomonas ampelophilae from the gut and malpighian tubules of Drosophila melanogaster. The flagellates attach to the microvilli either by weaving their flagella between the microvilli or by engulfing several microvilli with an external flagellar membrane. The first type predominated in the gut while the second type was limited to the malpighian tubules. Desmosomes were not involved in either type of attachment. A subpellicular collar with emerging microtubules was found to be adjacent to the desmosome of the flagellar pocket of herpetomonads in the gut.

Notes: Prorocentrum micans Ehrenberg, a free-living marine dinoflagellate, was used to test the intracellular toxic action of cadmium. The cells were cultivated in Erdschreiber medium, with Cd concentrations of 10–100 ppb. Thin sections of treated cells, examined ultramicroscopically, exhibited vacuolations, increased numbers of lysosomes, and severe mitochondrial damage. The first two alterations are a general response to toxicity; the third is Cd specific. Although some chloroplasts were affected by Cd, they were not very sensitive to its action. The nuclear apparatus was not morphologically affected.

Notes: Toxoplasma-like avian parasites inhabiting mononuclear phagocytes have been called Haemogregarina, Toxoplasma. avian Toxoplasma, Atoxoplasma, and Lankesterella by various authors. My attempts to transmit the parasites by bloodsucking mites or by transfer of blood and tissues of infected sparrows and canaries were unsuccessful. However, it was noted that the infection was exacerbated under conditions that favored transmission of coccidiosis: crowding and lack of cleanliness. Oral inoculation of sporulated oocysts of Isospora resulted in death from overwhelming macrophage infection with Toxoplasma-like organisms. Experiments using sparrows and canaries showed that the Isospora species involved was not cross infectious. Further investigations using canaries demonstrated that after oral oocyst inoculation, infection of macrophages spread from the submucosa of the duodenum to the liver. spleen, and lungs. After several generations in the internal organs, asexual multiplication, occured in the intestinal epithelium of the small intestinc. Fecal oocysts first appeared at the end of 9–10 days. Oocysts continued to be passed in the feces for months after infection. This chronicity may be explained by the relatively long life of the macrophages that serve as host cells for the asexual stages as compared to the intestinal epithelium which is the cell type parasitized by conventional coccidia.

Notes: Stages of mitosis of the micronuclei of Stentor coeruleus were described as seen by transmission electron microscopy. Cells in division and those regenerating new oral membranelles were studied. Microtubules were found in early prophase in the karyoplasm and interspersed between the condensing chromatin. A monaxial intranuclear spindle is formed by early metaphase, with kinetochore microtubule attachment sites on the chromosomes. The spindle elongates, separating the daughter nuclei at anaphase. A new nuclear envelope, consisting of two unit membranes, begins to form at late anaphase. Small segments of membrane found in the space between the newly forming and the old micronuclear envelopes appear to fuse to form the new nuclear envelope. No ultrastructural differences were found in the mitotic nuclei of cells in division or regeneration.

Notes: Sorogena stoianovitchae is an unusual ciliated protozoan with a life cycle characterized by the aggregation of individual trophic cells to form a multicellular sorogen that rises from the liquid culture medium surface by the secretion of a stalk. The noncellular stalk is a tapered, longitudinally furrowed structure composed of a fibrillar matrix that is initially hydrated, but with time dehydrates, the stalk becoming thin and brittle. This dehydration is of importance from the earliest stages of stalk formation since it results in the formation of the outer sheath-like region of the stalk that appears to provide much of the support of the stalk. Cytochemical tests of the stalk for polysaccharides (including acidic mucopolysaccharides) and proteins are positive. Proteolytic enzymes degrade the stalk. Lectins specific for glucose and N-acetyl-D-glucosamine bind to the stalk. Gas chromatography analysis detected the presence of fucose, glucose, glucosamine, and arabinose, as well as a variety of amino acids, predominantly glycine. The cytochemical and biochemical tests, the ultrastructural data, and the behavior of the stalk material suggest that the staik is composed of a matrix of complex protein-polysaccharide molecules.

Notes: Nosema disstriae, a parasite of the forest tent caterpillar, Malacosoma disstria, was cultured with cell lines UMN-MDH-1 (Malacosoma disstria), IPLB-1075 (Heliothis zea), and BTC-32 (Triatoma infestans). Infected cultured cells were used to infect the healthy cell lines. Electron micrographs of thin sections of 6-day-old cultures revealed infected cells that exocytosed vesicles containing vegetative and immature sporulating forms of the parasite. Some of these forms were believed to be responsible for intercellular transmission of the parasite. The spread of infection was augmented by culturing the cells at high densities; if the density was too low, there was little or no cross infection. Cross infection was inhibited, but not blocked completely, by high osmolality of the culture medium. The yield of spores from a confluent cell monolayer at the end of growth was generally 1–4 × 107 per ml of culture medium.

Notes: The fine structure of the trophozoite of Acanthamoeba palestinensis with a special emphasis on the Golgi complex, microbodies, and mitochondria has been examined. Golgi complexes are distributed throughout the cytoplasm but are most abundant in the perinuclear region. Usually two Goigi complexes are found in the same plane on opposite sides of the nucleus. One of them appears to be in an intimate association with the nuclear membrane. The region of contact contains compact cisternae, vesicles of various sizes, as well as granular and amorphous electron-dense material. Structural changes in the nuclear envelope are also observed in this area. A structure consisting of a Golgi complex and electron-dense microtubule organizing center, comparable to the centrosphere of other Acanthamoeba species, has been observed. Microbodies, surrounded by a single unit membrane and containing a granular matrix and tubular inclusions, are scattered throughout the cytoplasm. These organelles, circular (∼1 μm in diameter) or ovoidal (∼1 μm in length and ∼0.5 μm in width) in section, have often an irregular outline. These microbodies are probably the morphological equivalent of peroxisomes and glyoxysomes. Most mitochondria show a typical structure including tubular cristae and intracristal inclusions. Occasionally mitochondria with two apposed double membranes running through the midline are found. Such atypical cristae have never been reported in small amoebae before.

Notes: Heavy infections with enigmatic mobile organisms have recently been found in the blood of carp (Cyprinus carpio) in Central Europe. The organisms measure up to 15 μm, are variable in shape, and exhibit an unceasing twitching or dancing movement. Their developmental cycle starts with a primary cell enclosing a secondary cell. The former grows while the latter produces inside itself by a series of binary fissions and internal cleavages up to eight secondary cells, each of which encloses an inner (tertiary) cell of its own. In addition, up to four tiny cells with compact nuclei (“residual bodies”) also result from divisions of the secondary cells. Primary cells containing the products of the division of secondary cells finally disintegrate, releasing the secondary cells, which in their turn become new primary cells and repeat the cycle all over again. The structure and behavior of these organisms were so incompatible with existing ideas on myxosporean development that their myxosporean affinity was at first unrecognized. The final proof of their identity–appearance of myxosporean spores in sterile, experimentally infected hosts–is still to be presented. The interpretation of the myxosporean features of their life cycle (i.e., [1] the pericyte nature of the primary cell, [2] proliferation by disintegration of the pseudoplasmodial primary cell, [3] no rigidly fixed pattern in vegetative development), their ultrastructure (i.e., [1] characteristic bundles of microtubules and numerous free ribosomes in secondary cells, [2] lack of centrioles, [3] membranes enclosing the secondary cells within the primary cells), and facts on their epizootiology (i.e., [1] no success at transmission via leeches, [2] the occurrence of these organisms along with Sphaerospora renicola Dykova and Lom) suggest that they are stages of S. renicola from the kidney of carp. Similar mobile organisms were found in the blood of fry of two other fishes (Gobio gobi and Tinca tinca) which are also hosts for a Sphaerospora that infects the kidney. This suggests that these organisms represent an early phase in the developmental cycle in the genus Sphaerospora. The existence of cells enveloped one within the other (secondary and tertiary cells) in the developmental cycle, a characteristic myxosporean feature itself, is an intriguing parallel to similarly enclosed cells in sporogenesis of Paramyxea (Ascetospora).

Notes: The morphology and morphogenesis of the kinetofragminophoran soil ciliates, Fuscheria terricola n. sp. and Spathidium muscorum Dragesco & Dragesco-Kerneis, 1979, are described. Stained specimens (protargol) are characterized biometrically. The new species differs from the other species of the genus in its body size, body shape, number of kineties, length of extrusomes, and habitat. Both species have telokinetal stomatogenesis, which commences with a proliferation of kinetosomes at those kineties which bear the brosse. Fuscheria terricola does not have a complex perioral ciliature; indeed, it might be that this species has only monokinetids. Thus only a proliferation of kinetosomes and the separation of the kineties takes place in the prospective division furrow. In contrast, S. muscorum differentiates short dikinetid kinetofragments in the region of the division furrow, which are arranged to form the perioral kinety of the opisthe in the intermediate and late stages of the stomatogenesis. The right part of the perioral kinety develops first. This and other studies show that telokinetal stomatogenesis proceeds very differently depending on the differentiation of the oral ciliature; however, detailed studies on the morphogenesis of kinetofragminophoran ciliates are still too few in number for subtypes to be defined.

Notes: The apicomplexan family Barrouxiidae Léger, 1911 is reviewed and revised on the basis of present information. It includes the genera Barrouxia Schneider, 1885 with ten named species, Defretinella Henneré, 1966 with one named species, and Goussia Labbé, 1896 with 25 named species. The family is characterized by having bivalved sporocysts with a longitudinal suture line. Available information, admittedly spotty, is given for each species on oocyst, sporocyst and sporozoite structure, and on locus of sporulation. The following seven new combinations are made: Goussia flaviviridis (Setna & Bana, 1935) n. comb. in the gecko Hemidactylus flaviviridis; G. hyalina (Léger, 1898) n. comb. in an unidentified aquatic beetle; G. lacazei (Labbé, 1895) n. comb. in the centipedes Lithobius forficatus and L. martini; G. metchnikovi (Laveran, 1897) n. comb. in the gobies Gobio gobio and G. albipinnatus; G. schaudinniana (Pinto, 1928) n. comb. in the centipede Lithobius forficatus; G. stankovitchi (Pinto, 1928) n. comb. in the small bleak Alburnus alburnus, the bream Abramis brama, and the red roach Scardinius erythrophthalmus; Goussia sp. (Dogel' Akhmerov, 1959) nov. comb. in the freshwater fish Gnathopogon chankaensis.

Notes: Comparison of the electrophoretic migration patterns of proteins of active 40S and 60S ribosomal subunits isolated from nine amicronucleate strains of Tetrahymena of known phenoset revealed strain dependent differences which correlated with the phenoset classification of these strains as determined by Borden, Whitt & Nanney, who compared isoenzyme patterns.

Notes: Chromatin from a uninucleate dinoflagellate, Crypthecodinium cohnii, a binucleate dinoflagellate, Peridinium balticum, and a chromophyte, Olisthodiscus luteus, was examined by nuclease digestion and the results were compared to those from vertebrates. Gel analysis of the products of staphylococcal (micrococcal) nuclease digestion revealed a DNA repeat unit of 220(±5) base pairs for O. luteus and 215(±5) for P. balticum. Limit digestion gave a core particle of 140 base pairs, revealing that these longer repeat sizes are due to longer linker regions. No repeating subunit structure was found upon electrophoresis of digests of C. cohnii nuclei. Examination of the DNA fragments produced by DNAse I digestion of nuclei isolated from P. balticum and O. luteus showed the same ladder of ten base multiples as seen in chromatin from other eukaryotes. Examination of the kinetics of digestion by DNAse II of Peridinium chromatin revealed less susceptibility when compared to DNAse I digestions while 70% of Olisthodiscus chromatin and 35% of C. cohnii chromatin was sensitive to DNAse II. These data, taken together with previous results from Euglena, indicate that while algal chromatin is similar to that of higher eukaryotes in regard to DNAse I and II action, it differs in that the linker DNA is longer. In addition, the Hl-like histone from O. luteus and P. balticum is located in the linker DNA as in higher eukaryotes.

Notes: Changes in mean cell size, DNA and cell density were monitored at 6-h intervals for 72 h in populations of six species (eight clones) of marine dinoflagellates to determine the temporal relationships between the cell cycle events of DNA replication and cytokinesis. Batch cultures were maintained at 15 or 20°C on a 12-h light: 12-h dark photoperiod. Cell densities and size frequency distributions were determined conductimetrically and the amount of DNA within populations was measured fluorometrically. A variety of intra- and interspecific relationships were observed, ranging from parallel phasing of cell cycle processes to variations which involved the temporal uncoupling of DNA synthesis from the phased pattern of cell division which is characteristic of dinoflagellate cell cycles. Daily growth rates of individual populations varied from 0.05 (Gymnodinium nelsoni) to 2.08 (Amphidinium carteri) cell divisions day-1 and DNA doubling rates ranged from 0 to 1.14 day-1. Mean doubling rates for DNA were usually 30–40% lower than those for cells. The degree of difference in these rates and the amount of variability evident in cell cycle sequences may be major factors in determining the rate and extent of development of dinoflagellate populations in nature.

Notes: In Aedes cantator, Amblyospora sp. is transovarially transmitted and has two developmental sequences. The life cycle is initiated in the adult female with the release of sporoplasms from binucleated spores not bounded by membranes, lying free within host oenocytes. Sporoplasms infect the developing oocytes and are transmitted to the filial generation when the eggs are laid. In some of the female progeny that hatch from infected eggs, diplokaryotic cells infect host oenocytes and divide by binary fission during merogony. Sporulation and spore formation do not occur until a blood meal is taken by the host and they coincide with the development and maturation of the oocytes to complete the cycle. In other female and all male progeny, pathogen development occurs within fat body tissue of the host where diplokaryotic cells divide by multiple fission during merogony to spread the infection. Sporulation in this developmental sequence is characterized by the secretion of an accessory membrane and the meiotic division of diplokaryotic sporonts, which result in the formation of octonucleated plasmodia that undergo cytokinesis to form eight haploid spores which are not perorally infectious to other mosquito larvae. There is no increase in the prevalence of either type of infection in field populations during juvenile development, indicating that there is no direct horizontal transmission of the pathogen within any one generation. Data obtained from laboratory rearings of infected progeny, however, show that infections cannot persist relying solely upon maternal-mediated transmission and that some other mode of transmission must be operative for continued maintenance of this microsporidium in A. cantator.

Notes: Cells of Amoeba proteus and Chaos carolinensis that were in the process of phagocytosing large prey organisms were studied to find a structural basis for the generation of mechanical forces exerted by newly forming food cups. It was found that the food-cup walls facing prey organisms have a more prominent network of thin filaments inside the plasmalemma and that the glycocalyx covering the area is more condensed than usual.

Notes: Monoclonal IgG antibodies against sporozoites of Eimeria tenella were obtained from the ascites fluid of BALB/c mice. Oocysts, sporocysts, and sporozoites were exposed to medium 199, normal ascites fluid, or monoclonal antibodies 1A, 9D, 3D3II, or 2G8f. Specimens were then incubated with ferritin-conjugated goat anti-mouse IgG antibody. Ferritin was uniformly distributed over the surface of sporozoites exposed to 1A, 9D, or 3D3II; ferritin was localized in patches on sporozoites exposed to 2G8f. A uniform layer of ferritin was present on the inner layer of oocyst walls and on the Stieda body and outer surface of sporocysts exposed to 1A, 9D or 3D3II. In specimens treated with 2G8f, ferritin was present on the inner layer of the oocyst wall and the Stieda body, but not on the sporocyst wall. No ferritin was found on specimens exposed to medium 199 or normal ascites fluid. Monoclonal antibodies 1A, 9D, and 3D3II, but not 2G8f, caused complement-mediated lysis of sporozoites. These findings indicate that oocysts, sporocysts, and sporozoites of E. tenella contain common antigens specific for each monoclonal antibody tested.

Notes: Several divalent cation-dependent ATP phosphohydrolases associated with cilia, ciliary axonemes, ciliary membranes, pellicles, trichocysts, nuclei, mitochondria, microsomes, and soluble peripheral cell surface fractions of Paramecium tetraurelia were resolved in this study. Fifteen different activity bands were detected in whole cell sonicates or subcellular fractions by Triton polyacrylamide gel electrophoresis and ATPase activity staining. The ciliary surface membrane contained two major ATPase activities that were distinct from the enzymes associated with all other cell fractions.

Notes: During feeding a peritrophic membrane (PM) is formed in the gut of the tick Ixodes dammini, dividing the lumen of the gut into an ecto- and endoperitrophic space. Babesia and all food particles ingested with the blood meal by the tick are retained in the endoperitrophic space, the lumen proper. Only Babesia equipped with a highly specialized organelle, the arrowhead, are able to pass the PM and enter the ectoperitrophic compartment. During the crossing of the PM the arrowhead loses its density, suggesting that enzymes released from it dissolve the polymers in the PM, making passage of the parasite through this barrier possible. In the ectoperitrophic space the arrowhead of Babesia touches the epithelial cell. At the point of contact the membrane of the host cell starts to invaginate, and simultaneously the arrowhead's fine structure loses its highly organized pattern. The growing host membrane encircles the parasite and the arrowhead diminishes progressively in size. When the piroplasm is inside the host cell, the arrowhead can no longer be found. During invasion the host membrane often touches the parasite's plasma membrane at the site of a coiled structure, and the host membrane becomes ruptured and the nearby host cytoplasm appears to be lysed. Babesia inside the host cell is covered solely by its own plasma membrane; the invaginated host membrane is missing. It is postulated that the latter disintegrates during invasion by the parasite through the action of enzymes from the coiled structure. The parasite is surrounded by a halo of homogeneous material deriving most probably from the lysed host cytoplasm.

Notes: A technique for the separation of schizonts of Plasmodium falciparum is described. The different stages of the asexual cell cycle of the parasite were positioned according to their density in a continuous gradient of Percoll. Young trophozoites coincided with erythrocytes in a broad band corresponding to densities from 1.075 to 1.100 g/ml, whereas schizonts were concentrated at a density approximating 1.062 g/ml. The viability of the parasites was unimpaired by this procedure. Young trophozoites and schizonts continued their normal life cycle when cultured after the separation procedure. The percentage of recovery was high, reaching 80% of the initial quantity. Possible applications of the technique are discussed.

Notes: Chemically defined minimal media for the cultivation of high temperature tolerant and pathogenic Naegleria spp. have been developed. A defined minimal medium, identical for N. fowleri and N. lovaniensis, consists of eleven amino acids (arginine, glycine, histidine, isoleucine, leucine, methionine, phenylalanine, proline, threonine, tryptophan, and valine), six vitamins (biotin, folic acid, hemin, pyridoxal, riboflavin, and thiamine), guanosine, glucose, salts, and metals. Three of the four strains of Naegleria fowleri tested (ATCCr̀30100, ATCCr̀30863, and ATCCr̀30896) and two strains of N. lovaniensis (ATCCr̀30467 and ATCCr̀30569) could be cultured beyond ten subcultures on this medium. For N. fowleri ATCCr̀30894 diaminopimelic acid, or lysine, or glutamic acid was also required. Mean generation time was reduced and population density increased for all strains with the introduction of glutamic acid. Glucose could be eliminated from the minimal medium only if glutamic acid was present. Without glucose, mean generation time increased and population density decreased. Diaminopimelic acid could substitute for lysine for ATCCr̀30894, indicating that Naegleria species may synthesize their lysine via the DAP pathway. Naegleria fowleri ATCCr̀30100 could be adapted to grow without serine or glycine in the minimal medium with glutamic acid added, but with mean generation time increased and population density decreased. The strain could be grown in the minimal medium in the absence of metals. For growth of N. australiensis ATCCr̀30958, modification of the medium by increasing metals ten-fold, substituting guanine for guanosine and adding lysine, glutamic acid, and six vitamins (p-aminobenzoic acid, choline chloride, inositol, vitamin B12, nicotinamide, and Ca pantothenate) was required.

Notes: From several surveys of environmental sites, the virulent human pathogen, Naegleria fowleri, was isolated from a pond in Georgia, a sewage treatment plant in Missouri, and from the Potomac and Anacostia rivers near and in Washington, D.C. Widely scattered, sparse populations seemed only a potential threat to human health at the time of sampling. The data support an estimate that the sites sampled contain 10,000 typical, low temperature, bactivorous amoebae for each heat tolerant amoeba able to grow at 45° C. Heat tolerant competitors were much more common than N. fowleri. Naegleria lovaniensis, which is heat tolerant but nonpathogenic, was isolated from and downstream from an open air thermal pollution temperature gradient. Hot piles of composting sewage sludge yielded no amoeboflagellates, many heat tolerant (45–49° C) amoebae, and one thermophilic (52° C) Acanthamoeba. Features of the methods used include two-stage incubation to increase isolation of sparse organisms and distinction of N. fowleri from almost all other amoebae on agar plates. The flagellate-empty habitat hypothesis postulates a general model in which human intervention and/ or natural events remove usual competitors and the ability to transform to a motile flagellate confers an advantage in recolonizing.

Notes: The ultrastructure of the bloodstream form of Cryptobia salmositica in rainbow trout was examined during the acute phase of experimental infection. The arrangement of the major groupings of cytoplasmic microtubules originating near the basal bodies is similar to that in other bodonids. The cytostome is reinforced both by pellicular microtubules and an electron-dense plaque. Certain microtubules associated with the flagellar pocket serve as nucleating sites for pellicular microtubules. A flagellar rootlet, consisting of two parallel fibers which are bound together intermittently by electron-dense plaques, curves posteriorly from the basal body of the recurrent flagellum towards the kinetoplast. The basal body associated plaque on the kinetoplast membranes is duplicated at the same time as the basal bodies. Cytoplasmic microtubules are found in association with the plaque and the outer kinetoplastic membrane. A pulsatile vacuole, described for the first time in a hemoparasitic cryptobiid, lies adjacent to the post-flagellar pit. Smaller, interconnected vesicles of the spongiome are continuous with the pulsatile vacuole. Since a pulsatile vacuole occurs not only in free-living and ectoparasitic cryptobiids but in the hemoparasitic (=trypanoplasm) forms as well, this is no longer a character by which the genus Trypanoplasma may be separated from the genus Cryptobia. Possession of this osmoregulatory complex may allow the organism to survive outside of a host and fulfill a monoxenous life cycle, in addition to the usual heteroxenous cycle involving a leech as vector.

Notes: The life-cycle of the amoeboflagellate Tetramitus rostratus includes amoeboid, cyst, and flagellate stages. The ultrastructure of these three stages is illustrated, with particular emphasis on flagellate morphology. Amoeba morphology is typical of that of limax amoebas. Cysts, forming from trophic amoebas, are enclosed by a wall made up of two layers: ectocyst (ca. 70 nm), and endocyst (200 nm). The wall apparently forms from precursor material present in vesicles in the pre-cyst stage cytoplasm. Flagellate morphology is characterized by a well-defined top-shaped profile, maintained by microtubules under the plasma membrane. The flagellar apparatus or mastigont consists of four flagella, their basal bodies, sheaves of microtubules associated with two of the basal bodies, and several rhizoplasts (periodicity 20 nm). A deep, microtubule-supported, ventral invagination appears to function as a gullet. A small number of mitotic stages observed in amoeboid and flagellate individuals suggests similarity in the division process in both stages: intranuclear mitotic apparatus, nucleolus persisting through mitosis, no centrioles or basal bodies functioning as centrioles, difficulty in resolving chromosomes. The text compares ultrastructures of several amoeboflagellate organisms and evaluates the phylogenetic significance of those features common to different species. On the basis of this study, Tetramitus most closely resembles Naegleria spp.

Notes: The hypothesis is advanced that all freshwater Euplotes species with a 9 type 1 fronto-ventral cirrus pattern (E. patella type) depend upon bacteria-like endosymbionts. Aposymbiotic cells of these species are unable to divide. The hypothesis is based on the investigation of 40 different freshwater Euplotes stocks collected in Germany, France, the USA, and Japan. No symbionts were found in E. crenosus and E. palustris, freshwater species with 10 fronto-ventral cirri, nor in E. muscicola, a representative of the freshwater Euplotes group with a 9 type 2 fronto-ventral cirrus pattern (E. affinis type). Characteristic for the essential endosymbionts are multiple nucleoids, a feature described earlier for omikron, an indispensable symbiont of E. aediculatus. Although the symbionts differ from omikron and among each other in size, shape, and their average number per host, they are believed to be related to omikron. In two stocks a different type of bacterium was found in which no defined nucleoids can be detected. Transfer of this symbiont into aposymbiotic cells, originally carrying omikron, revealed that it can restore the ability to multiply. Similarly, omikron was also able to restore the ability to divide in cells freed of this symbiont. It is assumed that this different type of symbiont is a secondary invader of Euplotes which displaced the original omikron-like endosymbiont. Some of the stocks were found to carry, in addition to omikron-like symbionts, other symbiotic bacteria; E. daidaleos carries in addition an alga. The findings suggest that the freshwater Euplotes species with a 9 type 1 cirrus pattern are closely related to each other and evolved from an ancestor (probably of cirrotype 10) which already was dependent upon endosymbionts of the omikron type. It supports the view that the two subgroups of freshwater Euplotes forms with a cirrotype of 9 have evolved independently from each other from species with 10 fronto-ventral cirri by losing a cirrus at different positions.

Notes: Promastigotes of Leishmania mexicana mexicana attach to mouse macrophages in vitro in the absence of serum by a wheat germ agglutinin-like ligand on the surface of the promastigote that binds to the N-acetyl glucosamine moiety of a receptor on the surface of the macrophage. The binding is temperature dependent, and the macrophage receptor is trypsin, cytochalasin B, and glutaraldehyde sensitive. The promastigote ligand is proteolytic enzyme and glutaraldehyde insensitive. Uptake follows attachment and is assisted or inhibited as for attachment. Treatment of promastigotes with proteolytic enzymes uncovers a receptor for a serum component that binds strongly to a mouse macrophage receptor in vitro. The strain of mice donating the macrophages had little effect upon attachment and uptake except that A strain mouse macrophages attached fewer promastigotes in 10 min than those of outbred mice, but took up as many promastigotes over 90 min as those of outbred mice. Low responder Biozzi mouse macrophages took up more promastigotes than high responder Biozzi mouse macrophages. Normal unheated human, rabbit, and guinea pig sera lysed promastigotes and so inhibited their attachment to macrophages in vitro. Unheated immune serum showed an enhanced inhibition of attachment. Heated normal serum allowed attachment and uptake, while promastigotes treated with heated immune serum showed enhanced attachment to and uptake by macrophages. Treatment of macrophages in vitro with immune serum enhanced their ability to attach promastigotes and to engulf them. Repeated 90-min exposures of a population of promastigotes to uptake by mouse macrophages in vitro did not deplete the population of any sub-population more likely to be taken by macrophages. The first sub-population to be taken up survived better in macrophages over 24 h than subsequently engulfed sub-populations.

Notes: BALB/c mice were hyperimmunized with non-infectious extracts of either Leishmania braziliensis promastigotes or Trypanosoma cruzi epimastigotes. When spleen cells from these mice were fused with P3X63Ag8 plasmacytoma cells, the resultant hybridomas synthesized monoclonal antibodies which displayed specific reactivity by indirect immunofluorescence with distinct subcellular components of the parasites. These studies revealed that antigens associated with the flagellum and with a nongranular component of the cytoplasm would account for much of the serologic cross-reactivity observed between the two species. Conversely, antigens associated with surface and/or cytoplasmic granules and with an intracellular organelle believed to be the kinetoplast appeared to be species-specific.

Notes: The invasion of liver parenchymal cells by sporozoites of Plasmodium berghei Vincke & Lips, 1948, was studied in vivo using transmission electron microscopy. Livers of Brown Norway rats were examined 30 and 60 min after intraportal injection of 15 million sporozoites each. Sporozoites found after incorporation into vacuoles in hepatocytes were often located near a bile canaliculus at the lateral cell surface, surrounded by hepatocyte lysosomal structures; however, degradation of sporozoites caused by lysosomal digestion inside hepatocytes was never observed. Due to the crescent shape of sporozoites, serial sections were necessary to demonstrate the actual process of invasion of the hepatocyte. The hepatocyte's plasmalemma appeared to invaginate due to the sporozoite's action, thereby creating a parasitophorous vacuole. It was suggested that the sporozoite actively penetrated the hepatocyte; however, no visible depletion of rhoptries and micronemes was observed.

Notes: The human pathogenic amoeboflagellate Naegleria fowleri and the nonpathogenic species N. gruberi can be cultivated axenically but usually in different media. Naegleria fowleri 6088 has been adapted to grow in Balamuth H-4 medium, usually used to propagate N. gruberi nB81. and nB81 has been adapted to grow in supplemented Nelson's medium, usually used to propagate N. fowleri. N. gruberi nB81. grown in either medium, enflagellated 135 to 150 min after subculture to non-nutrient amoeba saline, whereas 6088 required 225 min. Naegleria gruberi nB81 grown in either medium was agglutinated by 100 ug concanavalin A/ml, whereas N. fowleri 6088 was not. Naegleria fowleri and N. gruberi grown in Nelson's medium became rounded to a greater extent upon chilling at 5° C and remained rounded longer than Naegleria grown in Balamuth medium. The specificity of the surface antigens was an inherent characteristic of each species and not dependent upon the propagating medium. but Naegleria grown in Nelson's medium was agglutinated more reproducibly and more effectively by antiserum. N. gruberi was somewhat more resistant to acriflavine, actinomycin D, cycloheximide, or tetracycline than N. fowleri, regardless of the culture medium. Naegleria fowleri 6088 grown in Nelson's medium, however, was more resistant to actinomycin D, daunomycin. mithramycin. sulfamethoxazole, or tyrocidine than 6088 grown in Balamuth medium. There are limitations on the validity of comparisons of N. fowleri and N. gruberi based upon cultures grown in different media.

Notes: Fine structural studies of the hydrogenosomes of Tritrichomonas foetus using an improved fixative reveal that they are enclosed by two closely apposed 6 nm membranes, which separate at some regions forming a large intramembranous vacuole where Ca++-binding sites are located. Fixation of the cells in a glutaraldehyde solution containing 5 mM CaCl2 and postfixation in an osmium tetroxide-potassium ferrocyanide solution led to the appearance of a reaction product associated with certain regions of the membrane of the hydrogenosomes and in the cisternae of the endoplasmic reticulum, in the recurrent flagellum, and in the plasma membrane. Treatment of ultrathin sections with EGTA removed the reaction product. These results, in association with others previously described, indicate the existence of several similarities between the hydrogenosomes and the mitochondria.

Notes: . One hundred eighty-eight stocks of Paramecium primaurelia. P. biaurelia, P. tetraurelia. and P. octaurelia were grown axenically and screened for variation in four different esterases and acid phosphatase using starch gel electrophoresis. Major observations: frequency of intraspecies variation for these enzymes is much lower in these four species than in other organisms; hypervariability for two esterases occurs in P. biaurelia both in isolates from worldwide locales and in a restricted locale; clustering of variations occurs in a high proportion of variant stocks in all four species; frequency of intraspecies variation is highest in Central and South America for all four species; and geographical differentiation is lacking between stocks in the same species both for common as well as variant phenotypes despite the cosmopolitan distribution of these species. These results are not correlated with adaptations that favor inbreeding over outbreeding. nor is the possession of bacterial endosymbionts strongly correlated with enzyme variation. When the riequency of intraspecies variation was examined for the aurelia complex of species as a whole for 13 enzymes, mitochondrial DNA, and ribosomal DNA, differences between enzymes in frequency of variation could be seen, ranging from less than 2% for seven enzymes to 12.4% for glucosephosphate isomerase, a value similar to that observed for malic dehydrogenase, mitochondrial DNA, and ribosomal DNA in P. tetraurelia. The percentage of polymorphic enzyme loci in the complex as a whole was found to be much lower than that observed for other organisms. For the species more intensely studied in this paper the level of genetic polymorphism was also much lower, although P. biaurelia showed greater variability for two of the enzymes.

Notes: . Strains of Tetrahymena thermophila were examined in an attempt to establish what role certain ions (Na+, K+, Li+, Ba++, Ca++, Mg++, Mn++, Al+++, Fe+++) play in influencing cell survival time in a culture medium. In short-term experiments (20–30 min), cell survival time in a 1% peptone medium is directly related to the valence of the ion employed. Long-term observations (lasting up to five days) in a 1% peptone medium containing lower ion concentrations revealed that the effects on cell-cycle time are not correlated with the valence state of the ion. Comparisons were made among the ionic resistances of strains of T. thermophila, of T. pyriformis sensu stricto, and of two subspecies of T. pigmentosa. Strains within a species are highly correlated in their patterns of ionic response, while marked differences between species occur. The most distinctive group of strains examined came from one of the subspecies (syngen 6) of T. pigmentosa.

Notes: . A two-stage chemostat modified to accommodate the growth of adhesive organisms was used to determine the yield constant, Y, of a representative soil amoeba, Acanthamoeba polyphaga, utilizing as its prey Pseudomonas paucimobilis. The first stage consisted of a glucose-limited bacterial culture in steady state. The second stage consisted of a simplified predator-prey system, nongrowing bacteria serving as the limiting substrate for amoebae. A refined methodology to more accurately determine Y was developed, and Y for Acanthamoeba polyphaga in batch and continuous culture was determined to be 19.1%.

Notes: . The swiftness of thermotaxis of Paramecium caudatum has been investigated for various populations of organisms by measuring the transient spatial distribution of the gathering process of organisms that are transferred to a temperature-gradient cell from the culture medium. The dispersion obtained from the spatial distribution for each population is found to decrease linearly with time and finally reach a steady state value. The gathering rate determined by the slope of the dispersion strongly depends on population; it increases with population.

Notes: . Blastocystis hominis, an anaerobic intestinal protozoan parasite of man, has a generation time (GT) in axenic culture of 8.5–19.4 h, depending on the strain tested. Average GT of the eight strains was 11.7 h. Zero growth time cell counts of 5.0 × 105/ml to 2.0 × 106/ml rose in 3–5 days to 1 × 107 or 1 × 108 cells/ml. The GT was determined for the 24-h period during which the most rapid growth occurred; about 2% of the B. hominis cells were in division during this time. Division under the culture conditions provided was by binary fission, the usual mode for B. hominis in vitro as well as in vivo. Division times were determined also by direct observation of individual dividing cells in slide cultures. These were usually ca. 40–60 min but sometimes as low as 20 min.

Notes: In contrast to the situation in 13 other species of the Tetrahymena pyriformis complex, in which the condensed degenerating old macronucleus lies in the posterior end of the cell during the late stages of conjugation, in Tetrahymena tropicalis that nucleus is found in the anterior portion. This developmental characteristic may be useful for taxonomic purposes as well as being of value in investigations on nucleocytoplasmic interaction.

Notes: Eimeria nuttalli oocysts were found in 58% (21/36) and E. procyonis oocysts in 25% (9/36) of raccoons Procyon lotor in Illinois, and sporocysts of Sarcocystis sp. in 17% (2/12) of other raccoons in Illinois. The oocysts of E. nuttalli were ellipsoidal to ovoid. 15–21 × 12–17 μm, with a one-layered, smooth, colorless wall. The oocysts of E. procyonis were 22–28 × 18–22 μm, with a rough, striated, brownish, two-layered wall. The sporulated sporocysts of Sarcocystis sp. were 11–13 × 8–10 μm. Attempts to infect baby pigs by feeding them sporocysts of Sarcocystis sp. from the raccoon failed.

Notes: Comments are made concerning the work reported at this Conference by Dr. Edith Box. The importance of stress on the animals used in experimental work is emphasized. Difficulties in identification of isosporan species in birds are mentioned.

Notes: A trypanosomatid flagellate, Leptomonas sp., develops and multiplies in the macronucleus (only) of natural and laboratory-reared populations of the ciliate Euplotes. Up to 90% of the natural populations of Euplotes in our test pond had such nuclear infections. Laboratory infections were transmitted to this ciliate by feeding it liberated parasites. Paramecium resisted infections. All laboratory-induced infections were lethal to Euplotes, while control clones of the uninfected ciliates remained viable. This leptomonad, unlike Leptomonas karyophilus (found in Paramecium), shows no leishmanial forms in its several ciliate hosts and shows a varied pattern of locomotion.

Notes: Some generalizations of a decade ago are reexamined in light of modern advances in coccidiology. Perhaps surprisingly, not many modifications need or can yet be made. Future successes of significance will be in areas of immunology and chemical genetics.

Notes: Stocks of the Tetrahymena pyriformis complex have been collected in North America and their mating reactivity has been studied. In addition to stocks mating with Tetrahymena americanis, T. borealis, T. pigmentosa, T. hyperangularis, and T. australis, stocks belonging to old syngen 5 and three new mating groups, numbers 13, 14, and 15, were discovered. Syngen 5 and groups 13 and 14 are distinct “biological” species, based on their reproductive isolation from other groups and on the ability of withingroup crosses to produce immature progeny. These species have been named T. hegewischi n. sp., T. sonneborni n. sp., and T. nipissingi n. sp., respectively. The cross between the two group 15 stocks did not produce immature progeny, and there is not sufficient evidence to conclude that this pair of stocks represents a separate species. Temperature tolerance measurements have been made on stocks representing all known micronucleate members of “pyriformis” complex. Within each species, the range of temperature tolerances is narrow; the average within-species standard deviation is 0.63°C. The species averages range from 32.7 to 40.7°C. Using syngen numbers, the order from lowest to highest temperature tolerance is 9, 8, 10, 7, 6, 4, 13, 14, 12, 11, 5, 3, 2, 1. The large differences among species make temperature tolerance a useful aid in identification, but the origins of the differences among species are unknown.

Notes: Members of the family Sarcocystidae, as defined by Frenkel, have had a complicated history, principally due to the existence of both coccidial and cystic stages. This formerly clandestine relationship resulted in dual or partial designations of nomenclature for individual species. The problem was further compounded by the obligatory heteroxeny of several of the genera, making it impossible to transmit the parasites from one individual to another of a single host. As a result, oocysts similar in appearance, though from hosts separated taxonomically up to the familial level, were sometimes considered to be identical. Discoveries within the last decade have generated much interest and some understanding. Current studies of these and other coccidia should emphasize complete cyclical transmissions with cognizance of potential heteroxeny with the production of tissue cysts in intermediate hosts.

Notes: Book reviews in this article: Ecology and Parasitology. Alexander, M., ed. 1980. Advances in Microbial Ecology Smith, H. G. 1978. The Distribution and Ecology of Terrestrial Protozoa of Sub-Antarctic and Maritime Antarctic Islands Taylor, Angela E. R. & Muller, R., eds. 1980. Vaccines Against Parasites Kreier, Julius P., ed. 1980. Malaria New Textbook of Protozoology Farmer, John N. 1980. The Protozoa: Introduction to Protozoology Phytoflagellates and Serial Endosymbiosis Theory Cox, Elenor R., ed. Phytoflagellates Tappan, Helen. 1980. The Paleobiology of Plant Protists. Margulis, Lynn. 1981. Symbiosis in Cell Evolution: Life and Its Environment on the Early Earth. Intercellular Communication and Nuclear-Cytoplasmic Interactions O'Day, Danton H. & Horgen, Paul A., eds. 1981. Sexual Interactions in Eukaryotic Microbes Whitson, Gary L., ed. 1980. Nuclear-Cytoplasmic Interactions in the Cell Cycle. Invertebrate Texts Alexander, R. McNeill. 1979. The Invertebrates Barnes, Robert D. 1980. Invertebrate Zoology Engemann, Joseph G. & (the late) Hegner, Robert W. 1981 Invertebrate Zoology ATCC Catalogue of Strains Hatt, Harold D., ed. 1980. The American Type Culture Collection: Catalogue of Strains I.

Notes: Polyamines are multiply amine-substituted straight-chain aliphatics; their content in different tissues may vary widely, and their functions are many. Their main routes of biosynthesis originate from ornithine and methionine. Polyamine content and biosynthesis in tryposomatid flagellates are reviewed concluding with emphasis on their possible role as critical drug targets in these parasitic protozoa so pathogenic for man in large areas of the world.

Notes: During spring and autumn, the total number of amoebae and the number of Acanthamoeba species able to grow at 37°C were determined in six thermally polluted factory discharges and the surrounding surface waters. The isolated Acanthamoeba strains were studied for growth in axenic medium, cytopathic effect in Vero cell cultures, and virulence in mice. Although more amoebae were isolated in autumn, the number of Acanthamoeba species was lower than in spring, when the percent of pathogenic strains among the isolates was highest. Higher concentrations of amoebae were found in warm discharges, and more virulent strains occurred in thermal discharges than in surface waters.

Notes: Eight species of loricate choanoflagellates (Acanthoecidae), Acanthoecopsis spiculifera Norris, Bicosta antennigera Moestrup, Bicosta spinifera Throndsen, Calliacantha multispina Manton & Oates, Calliacantha simplex Manton & Oates, Crinolina aperta Leadbeater, Diaphanoeca multiannulata n. sp., and Parvicorbicula socialis (Meunier) Deflandre, have been observed, by light and electron microscopy, in samples obtained from the Weddell Sea during the austral summer of 1977. Diaphanoeca multiannulata is described for the first time from these samples: the other organisms are discussed. The distribution of most species within the Weddell Sea was widespread. Habitats in which choanoflagellates were found included the water column, the edge of (or ponds on) ice floes, and the interior of ice floes. The distributional, environmental, habitat, and/or morphological range of all previously described species is expanded. Methods of variation of transverse costal diameters between genera may be potentially useful to the understanding of taxonomy and phylogeny of this family.

Notes: The occurrence of amoebae in the rhizosphere of a beach grass (Panicum sp.) collected at the Hempstead Lake State Park, Long Island, New York, was investigated throughout the growing season of 198 1. Amoebae achieved increased population density in the root system when compared with that in the surrounding bare sand; moreover, numbers of amoebae were higher only during the period of active plant growth and up to flowering. Following flowering, the numbers of amoebae in the root system fell to the level found in bare sand. The species diversity of amoebae in this system was compared with that in the carposphere of the mushroom Laccaria trullisata which appears at the same site but at a different time of year.

Notes: Studies of the life cycle of Myxosoma cerebralis showed that development of infectivity did not occur endogenously but that the spore “aging” process required participation of an aquatic tubificid oligochaete. Data suggestive of such involvement were derived from trials in which spores were “aged” in an array of inert, sterilized, pasteurized, or natural aquatic substrates and from examination of aquatic soils from trout hatcheries in which whirling disease was epizootic. The role of the aquatic oligochaete was confirmed two ways. First, signs of whirling disease developed, and M. cerebralis spores were produced in young rainbow trout (Salmo gairdneri) that had been fed oligochaetes harvested from pond soil taken from two hatcheries where whirling disease was epizootic. Second, when containers of pasteurized soil were populated with four genera of oligochaetes–Aeolosoma, Dero, Stylaria, or Tubifex– from a biological supply house, or with tubificid worms from trout hatcheries free of whirling disease, and then seeded with M. cerebralis spores and “aged” for 4 months, whirling disease occurred only in trout held with Tubifex and with hatchery tubificids.

Notes: During the cellular differentiation induced by starvation of Acanthamoeba castellanii, the expression of a number of genes is regulated. Evidence is reviewed that at least one of these, the precursor ribosomal RNA transcription unit, is regulated at the level of transcription. The structure of the rRNA transcription unit and of the RNA polymerases responsible for transcription in Acanthamoeba are reviewed. Utilizing an in vitro transcription system constructed from these components, preliminary evidence has been obtained that pre-rRNA gene expression is regulated by a modification of RNA polymerase I that affects the enzyme's ability to participate efficiently in the initiation of transcription. These results are reviewed in relation to other known mechanisms of transcriptional regulation in eukaryotes.

Notes: All Stylonychia mytilus-like ciliates which were collected and sent to us during the last 20 years belonged either to S. mytilus or to a new species, S. lemnae, which is described here. The only morphological differences are the shape and the size. Stylonychia mytilus that have been starved for one day average 300 μm in length, and S. lemnae starved for a day are 230 μm long. The occurrence of mating types is described.

Notes: The ultrastructural organization of Nuclearia moebiusi is described. The organism has filose pseudopodia without supportive microtubules; it has mitochondria with flattened cristae, lacks extrusomes, microtubule-organizing centers, and cytoplasmic microtubules. During cell division, microtubules appear only within the nucleus, and reorganization of the nuclear envelope occurs late in the nuclear division cycle. Ultrastructural studies reveal that Nuclearia spp. have a pattern of cellular organization distinct from that of other amoebae. Comparison of ultrastructural features suggests that this organism is only distantly related to other rhizopod amoebae (including other filose amoebae) and to the heliozoa.

Notes: Metacyclic forms of Trypanosoma cruzi isolated from the hindgut of infected insect vectors (Rhodnius prolixus) were found to be immunologically cross-reactive with cultured epimastigote, amastigote, and metacyclic stages of the parasite as well as with bloodstream trypomastigote forms by direct agglutination and indirect immunofluorescence techniques. Sera specific for each of these forms of the parasite systematically yielded maximal antibody titers when measured against the homologous antigen, indicating that antigenic determinants are shared by all of the developmental forms used in this work. Supporting this conclusion were the significant reductions in anti-insect-derived metacyclic antibody titer caused by absorption with any of the other life stages of T. cruzi. These results are relevant to the potential use of laboratory-grown forms of T. cruzi in vaccination against a natural infection with this parasite.

Notes: Core-protected DNA can drive only 60% of the Tetrahymena thermophila macronuclear genome into duplexes in hybridization experiments. This core-protected DNA therefore contains only a subset of the genome complexity. We interpret this to mean that a large fraction, if not all, of the genome is phased with respect to nucleosome placement. Among the sequences present in total DNA and absent from core-protected DNA are most of the sequences containing N6-methyladenine (MeAde) residues, consistent with our previous demonstration that most of these residues lie in linker DNA. We show that these results are not due to artifacts resulting from the small size of the DNA driver, nor are they due to any sequence preferences exhibited by staphylococcal (staph) nuclease. This is the first evidence that nucleosome phasing may be a bulk genome characteristic.

Notes: Book review in this Article Cox, F. E. G., ed. 1982. Modern Parasitology. A Textbook of Parasitology

Notes: Column chromatography with Biogel P2 (molecular exclusion of 1800 daltons) indicates that the transforming principle causing microstomes to become macrostomes is a small molecule. Absorbance tests show that only those fractions with high absorbance at 260 nm have biological activity, indicating that the active principle is a component of nucleic acids. Tests of purines and pyrimidines show that purines are active, with hypoxanthine having the highest activity. The combination of hypoxanthine with uridine shows a synergistic reaction. As these two compounds are the natural catabolic excretory products from nucleic acids in Tetrahymena, the fact that they induce transformation in concentrated, starving cells may be a survival mechanism allowing cannibalism to be induced when nutrients are depleted, thereby allowing the survival of the transformed cells until such time as adequate nutritional conditions are restored.

Notes: RESUME.Après résorption des structures buccales du protomonte, la stomatogenèse ne commence que sur les produits de l'avant-dernière division du tomonte. Elle se poursuit et se complète sur les tomites individualisés de la dernière division. Au niveau des extrémités antérieures des cinéties somatiques intercalaires et des extrémités rompues de cinéties bipolaires, une lère vague de proliferation des cinétosomes produit de courtes lignes, obliques, de cinétosomes isolés. Elles se transforment en lignes d'une double rangèe de cinétosomes, à la suite d'une 2ème vague de multiplication de cinétosomes. Un alignement de ces segments, procédant de gauche à droite et d'avant en arrière, constitue successivement les 3 membranelles longitudinales en doublets (M1 puis M2 et M3) ainsi que la membrane parorale, également en doublet. Une 3ème vague de proliferation cinétosomienne juxtapose une rangée de cinétosomes à droite des doublets (sauf à l'extrémité postérieure de M1 et au niveau de la parorale) transformant les promembranelles en triplets. Cette proliferation cinétosomienne se prolonge par addition d'une 4ème rangée de cinétosomes au trajet médian et postérieur de M2 et peut-ětre à M3 et par juxtapositions successives de nouvelles rangées supplémentaires à l'extrémité postérieure de M2 (flamme). Les cinétosomes des rangées droites de promembranelles portent de larges rideaux de nombreuses fibres postciliaires. Les cinétosomes des autres rangées de M2, au moins, ont également des fibres postciliaires. Entre les cils de promembranelles il n'y a pas de couche alvéolaire, ni d'épiplasme. Une résorption des cinétosomes commence à se manifester par disparition des cinétosomes de la rangée gauche de la parorale dont subsistent les cinétosomes droits porteurs de fibres postciliaires. A vec le raccourcissement de l'aire buccale la résorption s'étend aux cinétosomes postérieurs des 2 rangées droites de M1, et des extrémités antérieures des 2 (ou 3?) rangées droites dc M3. Une invagination de la dépression buccale entraǐne vers la gauche les organelles buccaux et enfonce les cinéties vestibulaires en remontant en avant et à gauche leurs extrémités postérieures tronquées. Il y a régression postéro-antérieure totale des cinétosomes de la parorale. M1 reste constituée au départ de 3 rangées ciliaires; M2 est également formée de 3 rangées ciliaires doublées postérieurement de nombreuses rangées constituant la flamme; M3 n'est finalement constituée que d'une seule rangée ciliaire. Une ultime proliferation cinétosomienne aux extrémités antérieures de cinéties vestibulaires serait peut-ětre à l'origine d'un champ allongé de nouveaux cinétosomes vestibulaires.〈section xml:id="abs1-1"〉〈title type="main"〉ABSTRACTAfter resorption of the buccal structures of the protomont, stomatogenesis begins only in the products of the penultimate division of the tomont. It continues to completion in the individualized tomites of the last division. At the anterior ends of the intercalary somatic kineties and the broken ends of bipolar kineties, a first wave of kinetosome proliferation produces short streak lines of isolated kinetosomes. These develop into lines formed of double rows of kinetosomes following a second wave of kinetosome multiplication. An alignment of these segments, proceeding from left to right and from front to rear, constitutes successively the three longitudinal membranelles in doublets (M1 then M2 and M3), and the paroral membrane, also a doublet. A third wave of kinetosome proliferation juxtaposes a row of kinetosomes to the right of the doublets (except at the posterior end of M1 and at the level of the paroral membrane) to give triplets. This proliferation is extended by addition of a fourth row of kinetosomes on the median and posterior path of M2 and perhaps M3, and by successive juxtaposition of further rows at the posterior end of M2 (flare). The kinetosomes of the right hand rows of promembranelles bear wide ribbons of numerous postciliary fibers. There is no alveolar layer nor epiplasm between the cilia of the promembranelles. Resorption of kinetosomes begins by disappearance of the kinetosomes of the left hand row of the paroral membrane; the right hand kinetosomes carrying postciliary fibers remain. With shortening of the buccal zone, resorption extends to the kinetosomes of the two posterior rows of M1 and the anterior ends of the two (or three?) left hand rows of M3. An invagination of the buccal cavity draws the buccal organelles to the left and pushes in the vestibular kineties while raising forward and to the left their truncated posterior ends. Total postero-anterior regression of the kinetosomes of the paroral membrane occurs. Membranelle 1 remains composed of three rows of cilia; M2 is also composed of three rows of cilia edged posteriorly by numerous rows constituting the flare; M3 is composed of a single row of cilia. A final kinetosome proliferation at the anterior ends of the vestibular kineties might be responsible for the extended field of new vestibular kinetosomes.

Notes: . A new procedure is described that utilizes Percoll gradients for purifying micronuclei (MIC) and macronuclei (MAC) from Tetrahymena thermophila. Separation of MIC from MAC during certrifugation in Percoll gradients occurs as a result of their difference in size rather than density. Three kinds of tests were used to evaluate the purity of the nuclei: visualization of the nuclei by light microscopy; examination of the nuclei by electron microscopy; and Southern blots of MIC and MAC DNA probed with the 5s rRNA genes or a fragment from the MAC extrachromosomal rDNA molecule. When examined under the light microscope, the isolated MIC and MAC have much lower nuclear cross contamination levels than previous methods have reported. MIC's contaminated with less than 1 MAC in 1000 MIC and MAC's contaminated with less than 1 MIC in 500 MAC can be routinely prepared. Quantitative analyses of electron micrographs gave higher estimates of cross contamination in our purified nuclei, which may, in part, be explained by the difficulty in identifying small MIC or MAC fragments. Southern blots of MIC and MAC DNA probed with 5s rDNA confirmed the level of MAC contamination in the MIC estimated by light microscopy during purification of the nuclei. The level of nucleolar contamination in the MIC was estimated at 10% by Southern blots of MIC and MAC DNA, derived from a heterokaryon with distinctive MIC and MAC Bam HI sites, using an rDNA probe.