bluuebunny/crossref_metadata_2025_split huggingface dataset:
Biochemical Characterization of Secreted Proteases During Growth in Tetrahymena pyriformis WH‐14: Comparison of Extracellular with Intracellular Proteases
Authors: BANNO YOSHIKO , YANO KOH , NOZAWA YOSHINORI 
Published: May 2007

ABSTRACTTetrahymena pyriformis strain WH‐14 secreted large quantities of intracellular proteases into its culture medium during growth. Extracellular enzymes were purified to homogeneity from cell‐free medium by ammonium sulfate precipitation, CM‐Sephadex column chromatography, gel filtration, and DEAE‐cellulose column chromatography. The DEAE‐cellulose eluates were separated into four peaks (P‐I, P‐II, P‐III, and P‐IV), each of which exhibited a different specific activity toward azocasein and α‐N‐benzoyl‐DL‐arginine‐ρ‐nitroanilide (Bz‐Arg‐Nan). These four forms of the protease showed similarity in amino acid composition, molecular weight (21,000–24,000), and antigenic reactivity. They had pH optima at neutral range. P‐I showed the highest specificity to azocasein whereas P‐IV was most effective toward the synthetic substrates. The Km values for hydrolysis of Bz‐Arg‐Nan were 2.4, 1.6, 1.3, and 1.4 mM for P‐I, P‐II. P‐III, and P‐IV, respectively, and the corresponding Kcat/Km values were 5.0, 9.4, 28.5, and 114.3 S‐1.M‐1. These properties of secreted proteases were compared with those of intracellular proteases purified by the same procedure except for the initial Triton X‐100 extraction. There were similarities in specific activity toward two substrates, molecular weight, Km, pH optima, and antigenic reactivity between the proteases from two sources, providing evidence that the intracellular proteases may be secreted into the extracellular medium without modification.
The Effect of Specific Sterols on Cell Size and Fatty Acid Composition of Tetrahymena pyriformis W
Authors: CONNER ROBERT L. , LANDREY JOSEPHINE R. , CZARKOWSKI NANCY 
Published: May 2007

ABSTRACTThe size and fatty acid composition of Tetrahymena pyriformis W cells were influenced by the provision of a nutritional supplement of ergosterol, cholesterol, or tetrahymanol, but not of 20‐isocholesterol. Ergosterol and cholesterol addition led to a reduction in cellular volume, an increase in glycerophospholipid saturated fatty acid content, and an increase in palmitoleic acid and its metabolic products when compared to unsupplemented controls. Tetrahymanol supplementation resulted in an increase in cellular volume, a decrease in saturated fatty acid content, and a reduction in palmitoleic acid and derivatives. 20‐Isocholesterol was accumulated by the cells; however, this compound had no effect on any of the parameters followed in this investigation and had only a small depressant effect on tetrahymanol biosynthesis. Ergosterol and cholesterol had the same impact on the ciliates, even though the ergosterol‐supplemented cells contained approximately three times as much free sterol as did cholesterol‐grown cells. The amount of the free cholesterol and metabolic products in supplemented cultures was similar to the amount of tetrahymanol present in control cultures. This observation suggests that the cells recognize qualitative differences among the various polycyclic alcohols rather than responding to the amount of sterol present. Increased cellular levels of tetrahymanol led to a response unlike that of the true sterols, which again suggests that the high degree of specificity depends on the structure of the added polycyclic alcohol. The changes in fatty acid composition may be required to maintain proper interaction of the polar lipids and the polycyclic alcohols to give an appropriate degree of membrane fluidity.
The Effects of Purine and Pyrimidines Upon Transformation in Tetrahymena vorax, Strain V2S1
Authors: BUTZEL HENRY M. , FISCHER JANICE 
Published: May 2007

ABSTRACTColumn 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.
Ultrastructure and Cortical Morphogenesis in the Euplotine Hypotrich Certesia quadrinucleata Fabre‐Domergue, 1885 (Ciliophora, Protozoa)1
Authors: WICKLOW BARRY J. 
Published: May 2007

ABSTRACTThe cortical development during cell division and the interphase ultrastructure of the marine interstitial hypotrich Certesia quadrinucleata is described using light microscopy and both scanning and transmission electron microscopy. Membranelles are paramembranelles; postciliary microtubules from rightmost membranellar kinetosomes line the buccal cavity and separate parallel arrays of pharyngeal discs that border the cytopharynx. A large paroral membrane is present; an endoral membrane is absent. Alveolar plates lie within alveolar membranes except in regions where organelles and organellar complexes (cirri, the condylopallium, dorsal bristles, membranelles, and the paroral membrane) emerge from the cortex. Muciferous‐like bodies attach to the plasma membrane in these regions. Dorsal bristles possess transverse and postciliary microtubules as well as kinetodesmal fiber like those of other hypotrichs. Lasiosomes are present. A unique bulbous structure—the condylopallium—protrudes from the anterior right of the cell. The morphogenetic pattern is euplotine in that cortical development begins in one latitudinal zone, and the oral primordium of the opisthe develops within a subsurface pouch apart from the frontal primordia. Microtubular bundles appear beside (later attached to) developing frontal anlagen; they disappear after cirri are in final interphase locations. Although possessing unique characters, Certesia shares a close phylogenetic relationship with Euplotes.
Characterization of Two Sibling Species of the Genus Stylonychia (Ciliata, Hypotricha): S. mytilus Ehrenberg, 1838 and S. lemnae n. sp. II. Biochemical Characterization1
Authors: STEINBRÜCK GÜNTHER , SCHLEGEL MARTIN 
Published: May 2007

ABSTRACTThe two closely related hypotrichous ciliate species, Stylonychia lemnae and S. mytilus, have been compared with respect to their isoenzyme patterns, their macronuclear DNA banding patterns, and micronuclear DNA banding patterns after restriction enzyme digestion. Since macronuclear DNA contains mainly protein‐coding sequences and since the micronuclear DNA patterns represent mainly the repetitive fraction of the genome, these results, together with the isoenzyme patterns, reflect differences on three different levels of molecular evolution between morphologically very similar species. Each of the three methods allows an unequivocal identification of each of the two species. Intraspecific variation seems to be greatest among the repetitive sequences of the micronuclear genomes. By using the isoenzyme data and the formula of Nei (19) the genetic distance between the two species is calculated and compared with the results from other protozoa and different Drosophila species. Despite their morphological similarity, the two species show a considerable amount of evolutionary divergence on the three molecular levels which have been investigated.
Leishmania mexicana mexicana: Attachment and Uptake of Promastigotes to and by Macrophages In Vitro1
Authors: BRAY R. S. 
Published: May 2007

ABSTRACTPromastigotes 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.
Ultrastructural Localization of Enzymes Involved in the Feeding Process in Plasmodium chabaudi and Babesia hylomysci1
Authors: SLOMIANNY C. , CHARET P. , PRENSIER G. 
Published: May 2007

ABSTRACTIn P. chabaudi, hemoglobin digestion occurs in two ways: micropinocytosis and cytostomal phagocytosis. Both mechanisms lead to the formation of digestive vesicles which evolve to pigment vesicles containing hemozoin crystals. We used ultrastructural enzyme cytochemistry to detect and localize endoarylamidase and aminopeptidase activity. In P. chabaudi, these two enzymes are at first detected at the level of cytoplasmic ribosomes. When pinocytic vesicles appear, enzyme activity is localized at the membrane of the newly formed vesicles. Then, the labelling extends to the vesicle contents where it becomes very prominent. In the late trophozoite, enzymatic activity decreases and is no longer detected. In B. hylomysci, no endoarylamidase activity can be detected. Aminopeptidase is noted in the cytoplasm, the labelling being heavier in the growing trophozoites than in the younger stages. No vesicles or pigment can be observed. We thus conclude that aminopeptidase or endoarylamidase are synthesized in the cytoplasm of P. chabaudi and migrate to the digestive vesicles where hemoglobin digestion occurs. We do not know whether Babesia degrades hemoglobin since it does not produce residual pigment. It could feed from small peptides or amino acids coming from or through the stroma of the red blood cell.
An Ultrastructural Study of the Myxosporeans, Sphaerospoa angulata and Sphaerospora carassii, in the Common Carp, Cyprinus carpio L.1
Authors: DESSER SHERWIN S. , MOLNAR KALMAN , HORVATH IREN 
Published: May 2007

ABSTRACTSporogenesis of Sphaerospora angulata occurs in the lumen of renal tubules, and of Sphaerospora carassii sporogenesis occurs in the gill epithelium of carp (Cyprinus carpio) from Hungarian pond farms. In infected fish, the lumen of the renal tubules is filled with disporous pansporoblasts of S. angulata. Spores are formed through the participation of paired valvogenic and capsulogenic cells, and a dikaryotic sporoplasm, all of which lie in the cytoplasm of an envelope cell. The polar filament is formed through the apparent invagination of components of the elongate external tubule into the capsular primordium, coupled with the incorporation of dense material from the lumen of the primordium and external tubule. The cytological events leading to spore formation in monosporous pansporoblasts of S. carassii are similar to those of S. angulata and most other species of Myxosporea thus far. While neither parasite appears to induce severe pathogenesis, they may contribute to morbidity in concurrent infections with other microorganisms. Since spores of S. angulata and S. carassii are not formed in plasmodia and the earliest stage observed in this study was 2‐celled, earlier stages of these parasites must occur elsewhere in the carp host.
Ultrastructure of a Coccidium (Apicomplexa: Sporozoea: Coccidia) in Priapulus caudatus (Priapulida)1
Authors: McLEAN NORMAN 
Published: May 2007

ABSTRACTStages in the life cycle of a coccidium are described from the intestine of Priapulus caudatus Lamarck, 1816. Meronts, merozoites, microgamonts, microgametes, and walled and unwalled macrogametes were seen in intestinal cells. Meronts were about 8 μm long and 3–7 μm wide and produced up to seven merozoites. Free merozoites were about 9 μm long and 4 μm wide and contained about 43 subpellicular microtubules that terminated in the outer polar ring. Microgamonts were up to 23 μm long and 7 μm wide and usually were delimited by a single membrane. Microgametes were about 5 μm long, exclusive of the two flagella, about 2 μm wide, and contained a nucleus that was not uniformly dense. Macrogametes, about 6 μm in diameter, had a nucleus largely without dense chromatin. The oocyst wall formed around intracellular macrogametes to a thickness of 0.2–0.5 μm as thin, osmiophilic elements that became arranged in reticular and tubular layers. Wall‐forming bodies were not seen, but fine filaments may participate in wall formation, as these were found between the outer membrane of the pellicle and the nearest wall elements. Microgametes and walled macrogametes were delivered to the lumen of the host intestine during apocrine secretion or excretion by the intestinal cells. Fertilization may occur in the intestinal lumen. Unsporulated ovoid oocysts, 18–27 μm long and 10–14 μm wide, with a 3 μm micropyle and a wall 0.6–0.7 μm thick, were passed from the host.
Ultrastructural Study of an Endosymbiotic Alga and Its Host Ciliate Stentor niger
Authors: KAWAKAMI HISAKO 
Published: May 2007

ABSTRACTStentor niger collected in the suburbs of Hiroshima contained in its cytoplasm several hundreds of endosymbiotic algae and innumerable brownish pigment granules. The body of the ciliate was dark due to a mixture of the green endosymbiotic algae and brown pigment granules. The algae belonged to the genus Chlorella; each was enclosed in a perialgal vacuole and dispersed uniformly in the host cytoplasm from the myoneme layer inward to the center of the ciliate. The cell wall and plasma membrane of the alga enclosed a nucleus, chloroplast, mitochondrion, Golgi complex, accumulation bodies, myelinated vesicles, and many ribosomes. The chloroplast occupied more than half of the volume of the alga and contained a conspicuous pyrenoid. Algal multiplication occurred by two successive divisions of an alga, leading to four autospores within a perialgal vacuole; the walls of the vacuole invaginated to separate the autospores each into its own vacuole. Three types of pigment granules were scattered uniformly throughout the cytoplasm of the ciliate. The ultrastructure of the membranellar region, somatic cortex, and macro‐ and micronucleus of the ciliate are also described.
A Redescription of Hepatozoon mocassini (Laveran, 1902) n. comb. from Agkistrodon piscivorus leucostoma Troost, 1836
Authors: NADLER STEVEN A. , MILLER JOSEPH H. 
Published: May 2007

ABSTRACTHepatozoon mocassini (Laveran, 1902) n. comb. from Agkistrodon piscivorus leucostoma (water moccasin) is redescribed by light microscopic study of all developmental stages and reclassified since mature oocysts contained sporocysts. Formerly this species was assigned to the genus Haemogregarina on the basis of a description of the gamonts. A neotype is designated because the original specimens cannot be located. Mature oocysts, containing sporocysts, developed in the hemocoel of the experimental host Aedes aegypti. These oocysts proved infective for A. piscivorus leucostoma when administered orally.
Effects of Chloroquine on the Feeding Mechanism of the Intraerythrocytic Human Malarial Parasite Plasmodium falciparum1
Authors: YAYON AVNER , TIMBERG RINA , FRIEDMAN SHOSHANA , GINSBURG HAGAI 
Published: May 2007

ABSTRACTUltrastructural investigations of P. falciparum cultivated in vitro in human erythrocytes revealed new features of the feeding mechanism of the parasite. Mature trophozoites and schizonts take up a portion of the host cytosol by endocytosis which is restricted to cytostomes and which involves the invagination of both parasitophorous and parasite membranes. The resulting endocytic vesicles, surrounded by two concentric membranes, migrate towards the central food vacuole membrane. The external membrane of the endocytic vesicles apposes that of the food vacuole, leading to the internalization of vesicles bounded by a single membrane into the vacuolar space where they are rapidly degraded. We conclude from this sequence of events that endocytic vesicles fuse with the food vacuole. Treatment of infected cells with therapeutic concentrations of chloroquine inhibited the last step of the feeding process, i.e. vacuolar degradation. This was manifested by the accumulation within the vacuolar space of intact vesicles bounded by single membranes. The implications of these findings for the antimalarial activity of chloroquine are discussed.
Somatic and Oral Cortical Ultrastructure of the Plagiopylid Ciliates Lechriopyla mystax Lynch, 1930 and Plagiopyla minuta Powers, 19331
Authors: BERGER JACQUES , LYNN DENIS H. 
Published: May 2007

ABSTRACTThe somatic and oral cortical ultrastructure of the plagiopylid ciliates Lechriopyla mystax Lynch, 1930 and Plagiopyla minuta Powers, 1933 are described. The somatic kinetids are monokinetids with an anteriorly directed kinetodesmal fibril originating near triplets 5, 6, 7, a divergent postciliary ribbon originating at triplet 9, and an unusual transverse ribbon originating in dense material adjacent to triplets 1, 2, 3. The transverse ribbon extends beneath the right surface of the cortical ridge adjacent to the kinety from which it originated. The oral kinetids are also monokinetids from whose base rootlet fibrils extend inwards beneath the oral kineties and converge on the furcula. The striated band on these ciliates is composed of a series of short ridges orthogonal to the longitudinal axis of the band. The sides of the striated band groove are apparently supported by macrotubules. The cortical ultrastructure of the plagiopylids is discussed with reference both to the optical microscopy of the organisms and to the ultrastructure of other ciliate taxa. The plagiopylids are not clearly related to any other higher taxon and are placed incertae sedis in the Subphylum Cyrtophora Small, 1976.
The Effect of Gamma Radiation on Nosema algerae (Microspora: Nosematidae) Spore Viability, Germination, and Carbohydrates1
Authors: UNDEEN ALBERT H. , MEER ROBERT K. VANDER , SMITTLE BURRELL J. , AVERY SUSAN W. 
Published: May 2007

ABSTRACTSpores of Nosema algerae Vávra & Undeen were exposed to 5 to 3000 KR of gamma radiation, then assayed for viability in Anopheles quadrimaculatus Say, and tested for germination in vitro. There was a dosage‐dependent loss of viability between 5 and 100 KR. Immediately after exposure to radiation at dosages between 1000 and 3000 KR, the spores progressively lost ability to germinate in 0.2 M KCl, pH 9.5. Between 250 and 1000 KR spores germinated well immediately after irradiation but, over a time span of days, fewer spores were able to germinate. Gamma radiation at 1000 and 2500 also caused a decrease in intrasporal trehalose concentration. The decline in percentage germination and trehalose concentration was more rapid at the higher dosages than the lower dosages.
Cytological Studies of Trichophrya rotunda (Hentschel)1
Authors: MOGENSEN METTE M. , BUTLER R. D. 
Published: May 2007

ABSTRACTMorphological, ultrastructural, and reproductive studies of a suctorian suggest its designation as Trichophrya rotunda (Hentschel) as distinct from Heliophrya collini, Heliophrya rotunda, and Craspedophrya rotunda of previous descriptions. Trichophrya rotunda has a round or slightly irregular, dorsoventrally flattened body (37–73 μm) with peripheral tentacles arranged randomly within 4–13 fascicles, a central polymorphic macronucleus, and 7–21 peripheral contractile vacuoles with ventrally terminating discharge pores. The tentacles are contractile and highly flexible. The axoneme consists of microtubules forming seven curved lamellae and 35 outer microtubules, which are separated into seven groups. Deviations from this prevailing pattern include helically arranged lamellae at the points of apical and basal termination, outer ring microtubules joined in an apical connective sheath, and the presence of a basal connective sheath near the point of axoneme termination. In common with other suctorians the cortex is multilayered and the cytoplasm contains characteristic organelles such as crescentic bodies and elongate dense bodies, but the haptocysts have unusual radial projections. Trichophrya rotunda feeds readily on motile vorticellids, attachment of the tentacular knobs occurring at their trochal band. Reproduction is endogenous, producing a single, slightly flattened, oval‐shaped swarmer with five equatorial kineties. The swarmer cytoplasm shows no evidence of primordia of tentacle axonemes nor any stages in development of the tentacle.
Inhibition of Growth of Giardia lamblia by Difluoromethylornithine, a Specific Inhibitor of Polyamine Biosynthesis1
Authors: GILLIN FRANCES D. , REINER DAVID S. , McCANN PETER P. 
Published: May 2007

ABSTRACTDifluoromethylornithine (DFMO) is a specific and irreversible inhibitor of ornithine decarboxylase, an enzyme which catalyzes the first step in the biosynthetic pathway of the polyamines. We tested the effect of DFMO on the growth of Giardia lamblia, Entamoeba histolytica, and Trichomonas vaginalis. Growth of G. lamblia was inhibited by DFMO at concentrations of ≥ 1.25 mM. Culture doubling time increased with increasing DFMO concentration. Growth inhibition was reversed if spermidine was added within 53 h of addition of DFMO; no growth was observed if spermidine was added later, indicating eventual parasite death. The growth of E. histolytica and T. vaginalis, two unrelated mucosal‐dwelling parasites of humans, was not inhibited by 20 mM DFMO. These studies indicate that polyamine biosynthesis from ornithine is required for growth of G. lamblia.
Nutritional Requirements of Plasmodium falciparum in Culture. I. Exogenously Supplied Dialyzable Components Necessary for Continuous Growth
Authors: Divo Alan A. , Geary Timothy G. , Davis Nella L. , Jensen James B. 
Published: May 2007

ABSTRACTContinuous cultivation of Plasmodium falciparum presently requires the nutritionally complex medium, RPMI 1640. A basal medium of KCl, NaCl, Na2HPO4, Ca(NO3)2, MgSO4, glucose, reduced glutathione, HEPES buffer, hypoxanthine, phenol red (in RPMI 1640 concentrations), and 10% (v/v) exhaustively dialyzed pooled human serum was used to determine which vitamins and amino acids had to be exogenously supplied for continuous cultivation. Supplementation of basal medium with calcium pantothenate, cystine, glutamate, glutamine, isoleucine, methionine, proline, and tyrosine was necessary for continuous growth. This semi‐defined minimal medium supported continuous growth of four isolates of P. falciparum at rates slightly less than those obtained with RPMI 1640. Adding any other vitamin or amino acid did not improve growth. Incorporation of several non‐essential amino acids, particularly phenylalanine and leucine, into proteins was markedly enhanced in the minimal medium compared to RPMI 1640.