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[The destruction of microscopic organisms by their irradiation with a special form of UHF electromagnetic signals].

Electromagnetic signals of special form produced by an ultra-high frequency generator were used to destroy various microorganisms: baker's yeast; blue-green alga Nostoc muscorum; mold fungus; and two flagellates, plant flagellate Euglena gracilis and an animal flagellate parasitizing on humans. The control samples before irradiation and experimental samples damaged and destroyed by irradiation were examined on a microscope with a computer system of image analysis. The results are presented as computer graph images.

Animals↗

PubMed1998

Crithidia fasciculata induces encystation of Entamoeba invadens in a galactose-dependent manner.

The ability of the flagellate Crithidia fasciculata to induce encystation of the reptile pathogen, Entamoeba invadens, was studied in vitro. A specific ratio of flagellate to amoeba was required; both live and heat-killed C. fasciculata induced amoebic encystation. The interaction between the Crithidia and Entamoeba cells was found to be galactose-mediated because the addition of galactose to the culture medium, or the pretreatment of the flagellate with galactosidase, eliminated its ability to induce encystation. Galactose was also found to prevent the amoeba amoeba aggregation that normally occurs in axenic cultures of encystation-induced E. invadens. Both galactose and glcNAc completely inhibited cyst formation of these induced cultures, although the latter sugar did not prevent cell aggregation. These results indicate that a galactose-mediated interaction between E. invadens cells is an early step in the in vitro encystation pathway.

Animals↗

PubMed1996

Changes in flagellar movement of rat spermatozoa along the length of the epididymis: manual and computer-aided image analysis.

The different patterns of motility of rat spermatozoa during epididymal transit were studied in vitro using high-speed videomicroscopy. The sperm images were analysed after manual tracing as well as with a computer imaging system. The present work is the first which reports both the swimming path of the sperm head and the characteristics of flagellation in this species. The hook-shaped head of the rat spermatozoa allowed us to demonstrate the two-dimensional (2D) swimming movement compared to the three-dimensional (3D) sperm motion which was mainly related to rotation of the head. Immotile spermatozoa entered the initial segment of the testis and showed rigid flagella. The potential for sperm motility occurred abruptly in the proximal caput region, and different patterns of flagellation were observed: vibrating, motile in place, motile with a static curvature of the midpiece resulting in a spinning motion or a circular path, and forward progressive movement with regular rotation of the head. The pattern of sperm movement became homogeneous in the distal cauda where the whole sperm population swam in a straight line. A static curvature appeared in the midpiece portion when the spermatozoa reached the proximal caput region. The formation of the static curvature was observed on both sides of the rat flagellum which were easily indicated by the head-shaped projection of the head and the axonemal side of the principal wave. As soon as they moved, the spermatozoa successively initiated principal (P) and reverse (R) waves, but the waves were visible only distal to the static curvature. The midpiece stiffness progressively decreased during the epididymal maturation; simultaneously the static curvature showed a larger radius and then disappeared. Consequently, the initiation of waves which was first seen in the distal part of the flagellum of immature cells occurred progressively near the junction with the head of maturing spermatozoa. These changes in sperm motion previously shown in rams and now in rats might be a general phenomenon in mammals. The high resolution of this computer imaging system applied tosperm motion showing a well-characterized "side of the flagellum" should allow sensitive detection of biochemical effects on flagellar beating.

Animals↗

PubMed1994

Neural network analysis of flow cytometric data for 40 marine phytoplankton species.

Flow cytometry data (time of flight, horizontal and vertical forward light scatter, 90 degrees light scatter, and "red" and "orange" integral fluorescence) were collected for laboratory cultures of 40 species of marine phytoplankton, from the following taxonomic classes, the Dinophyceae, Bacillariophyceae, Prymnesiophyceae, Cryptophyceae, and other flagellates. Single-hidden-layer "back-propagation" neural networks were trained to discriminate between species by recognising patterns in their flow cytometric signatures, and network performance was assessed using an independent test data set. Two approaches were adopted employing: (1) a hierarchy of small networks, the first identifying to which major taxonomic group a cell belonged, and then a network for that taxonomic group identified to species, and (2) a single large network. Discriminating some of the major taxonomic groups was successful but others less so. With networks for specific groups, cryptophyte species were all identified reliably (probability of correct classification always being > 0.75); in the other groups half of the species were identified reliably. With the large network, dinoflagellates, cryptomonads, and flagellates were identified almost as well as by networks specific for these groups. The application of neural computing techniques to identification of such a large number of species represents a significant advance from earlier studies, although further development is required.

Flow Cytometry↗

PubMed1977

Rapid decline thymidine kinase activity during differentiation of Naegleria.

A logarithmically growing population of Naegleria gruberi differentiate into flagellates synchronously in about 85 to 90 minutes after the stimulation. Using this system, two separate enzymes that phosphorylate thymidine were assayed. Thymidine kinase activity decreases rapidly after the stimulation, while nucleoside phosphotransferase activity remains approximately constant. The possibility that this observed decrease in thymidine kinase activity is due to an expanded thymidine pool or to an increased phosphatase activity has been ruled out. Mixing experiments indicated that there is neither an activator of thymidine kinase in growing cells nor an inhibitor in differentiating cells. Thus, the observed decrease is likely to be due to an inactivation of the enzyme. Addition of actinomycin D or cycloheximide does not prevent the decrease in thymidine kinase activity suggesting that neither transcription nor translation is involved in the putative inactivation of thymidine kinase enzyme. There is very good correlation between the degree (or rate) of decrease in thymidine kinase activity and the percent of cells differentiating into flagellates. Thus, it appears certain that the residual thymidine kinase activity is primarily due to some portion of cells which did not respond to the stimulation and did not differentiate. Since there is an early termination of nuclear DNA synthesis in differentiating Naegeria, the decrease in thymidine activity (but no change in nucleoside phosphotransferase) suggests a correlation between thymidine kinase and DNA synthesis in Naegleria.

Animals↗

PubMed1990

Ultrastructure of sperm, spermiogenesis, and sperm-egg interactions in selected invertebrates and lower vertebrates which use external fertilization.

This review discusses the ultrastructure of sperm with reference to their development, the surface morphology of the egg, and the processes of sperm binding and penetration during fertilization. These topics are treated for selected invertebrates and lower vertebrates which live in aquatic environments and fertilize their eggs externally. Specifically, sperm eggs from cnidarians, echinoderms, decapod crustaceans, ascidians, lampreys, bony fishes, and amphibians are discussed. Sperm from the majority of these groups exhibit the classical head-midregion-tail configuration characteristic of primitive sperm. Specific variations within this general morphology have been described. The notable exceptions to the primitive-sperm paradigm are the sperm of decapod crustaceans and amphibians. Eggs from all of the animals considered are covered by complex vitelline envelopes except those of cnidarians. In general, the ultrastructural analysis of these egg envelopes shows that they are composed of fibrous subunits. Sperm bind to the vitelline envelope and then penetrate through it to fertilize the egg in all groups reviewed except fishes. In sperm ultrastructure which occur during penetration of the egg envelopes in both flagellated and non-flagellated sperm. These changes, which involve membrane fusion and reorganization as well as movement of membranous organelles, aid the sperm in reaching the actual site of gamete fusion.

Animals↗

PubMed1975

Feulgen microspectrophotometric analysis of deoxyribonucleoprotein organization in larval and adult freshwater sponge nuclei.

Microspectrophotometric measurements of nuclei of adult choanocytes and archeocytes and larval archeocytes and flagellated ectodermal epithelia from stages III and IV were undertaken on tissues from the freshwater sponge, Eunapius fragilis (Leidy). The condensed nuclei of differentiated choanocytes and state IV flagellated epithelial cells presented integrated extinction values about 64% of those obtained for either adult or larval archeocytes. This suggests that such measurements represent sensitive indicators of deoxyribonucleoprotein-complex organization; thus, nuclear differentiation. Further, no large population of G2 (4C) nuclei was found among these populations as has been reported in two classes of coelenterates.

Animals↗

PubMed1996

Histone H1 and core histones in Leishmania and Crithidia: comparison with Trypanosoma.

The Trypanosomatidae family is characterized by flagellated protozoa presenting a kinetoplast. Several genera of this family contain species that are pathogenic to man and domestic animals. Their chromatin is not condensed into chromosomes during cell division. As a contribution to the understanding of basic aspects of their genome organization, we present a systematic characterization of the histones from three genera of the Trypanosomatidae family. Crithidia fasciculata and Leishmania mexicana show core nucleosomal histones with electrophoretic mobilities both similar to and different from those of Trypanosoma cruzi and higher eukaryotes. Another protein is extracted from the chromatin of these organisms by procedures designed to purify histone H1. This protein presents elution profiles by HPLC and amino acid composition of histone H1. Considering these data and the high mobility of this protein in Triton-acetic acid-urea-polyacrylamide gel electrophoresis, as well as its position relative to the nucleosomal core histones in sodium dodecyl sulfate-polyacrylamide gel electrophoresis, we postulate that Crithidia and Leishmania possess a histone H1 shorter than that of higher eukaryotes as we have previously shown to be the case for T. cruzi. The possible presence of a shorter histone H1 in these trypanosomatids may explain the absence of chromatin condensation during cell division in these flagellates.

Amino Acids↗

PubMed1996

Trypanosomatidae: a spliced-leader-derived probe specific for the genus Phytomonas.

We probed DNA from all trypanosomatid genera by slot blot hybridization with an oligonucleotide (SL3') complementary to a sequence of the Phytomonas spliced-leader or mini-exon RNA. The 19-nucleotide probe target site was previously shown to be highly conserved among a limited number of Phytomonas isolates, but diverges in other kinetoplastid genera. Our examination of 84 isolates of various genera of trypanosomatids showed hybridization of this probe exclusively with isolates from plants or insects which could, by morphological, biochemical, and molecular criteria, be considered to belong to the genus Phytomonas. In contrast, no hybridization was observed with flagellates of the genera Blastocrithidia, Crithidia, Endotrypanum, Herpetomonas, Leptomonas, Leishmania, and Trypanosoma. The method detected DNA quantities as low as 50 ng using either radioactive or nonradioactive probes, and was effective with as few as 10(4) intact flagellates. Together, these results suggest that this probe will serve as a convenient marker for taxonomic and epidemiological studies requiring reliable identification of Phytomonas spp. in plants or in putative insect vectors.

Animals↗

PubMed2001

Veneza zonata (Hemiptera: Coreidae)/trypanosomatid relationship: action of hemolymph in vitro and experimental infection.

The defense response of Veneza zonata (Hemiptera: Coreidae) against three different trypanosomatid infections was assessed: (1) strain 714TD, a Leptomonas which has V. zonata as vector of a plant trypanosomatid, (2) strain 563TD, a Leptomonas isolated from the digestive tract of Euchistus heros (Hemiptera: Pentatomidae), and (3) Leishmania (L.) amazonensis, a human parasite that cannot infect V. zonata. Experiments with V. zonata hemolymph showed agglutination only of L. (L.) amazonensis culture forms and hemocytic recognition was more intense with this strain. L. (L.) amazonensis also activated the prophenoloxidase system, whereas strains 714TD and 563TD did not activate this system but rather seemed to inhibit phenoloxidase activity. No flagellates were seen in the digestive tract, hemolymph, or salivary glands in insects infected with L. (L.) amazonensis. The digestive tract, the hemolymph, and the salivary glands of insects fed on tomatoes inoculated with 714TD are sequentially invaded by the flagellate, which is inoculated in plants together with saliva. Insects fed on tomatoes inoculated with 563TD exhibited culture forms in the digestive tract (6 days after) and hemocoel (three additional days); however, they died 12 to 14 days after exposure. The salivary glands in insects inoculated in the hemocoel with 714TD strain are rapidly invaded, whereas those with 563TD culture forms died approximately 24 h after infection. Bacterial proliferation in the hemocoel and hemocyte surface blebbing were seen in insects infected only with 563TD strain as the probable pathogenic mechanism of insect death.

Animals↗

PubMed1996

A 5 S rRNA gene is present in the mitochondrial genome of the protist Reclinomonas americana but is absent from red algal mitochondrial DNA.

Except in the case of land plants, mitochondrial ribosomes apparently lack a 5 S rRNA species, even though this small RNA is a component of all prokaryotic, chloroplast and eukaryotic cytosol ribosomes. In plants, the mitochondrial 5 S rRNA is encoded by mtDNA and differs in sequence from the 5 S rRNA specified by plant nuclear and chloroplast genomes. A distinctive 5 S rRNA component has not been found in the mitochondrial ribosomes of non-plant eukaryotes and, with the notable exception of the chlorophycean alga, Prototheca wickerhamii, a 5 S rRNA gene has not been identified in those non-plant mtDNAs characterized to date. Here, we report the presence of a 5 S rRNA gene in the mtDNA of the heterotrophic flagellate Reclinomonas americana. This unicellular eukaryote is a member of the jakobid flagellates, an early-diverging group of protists that share ultrastructural characteristics with the retortamonads, primitive protists that lack mitochondria. We report sequence data from the mtDNAs of the red algae Porphyra purpurea and Gracilariopsis lemaneiformis, which we use to evaluate a recent claim that a 5 S rRNA gene exists in the mtDNA of a third rhodophyte alga, Chondrus crispus. Our results lead us to the opposite conclusion: that a 5 S rRNA gene is not encoded by red algal mtDNA. In view of the accumulating evidence favoring a monophyletic origin of the mitochondrial genome, it is likely that a 5 S rRNA gene was present in an ancestral proto-mitochondrial genome, and that contemporary mtDNA-encoded 5 S rRNA genes have all descended from this ancestral gene. Considering the highly restricted phylogenetic distribution of identified mtDNA-encoded 5 S rRNA genes, it follows that the mitochondrial 5 S rRNA gene must have been lost multiple times during evolutionary diversification of the eukaryotic lineage.

Animals↗

PubMed2000

Two novel flagellar components and H-NS are involved in the motor function of Escherichia coli.

A mutation in H-NS results in non-flagellation of Escherichia coli due to a reduced expression of the flhDC master operon. We found that the hns-negative strain restored its flagellation in the presence of flhDC, although the resulting strain was still non-motile. Since the intracelluar levels of motor components MotA, MotB, and FliG in the Deltahns strain were unaltered, the non-motility indicates that H-NS affects flagellar function as well as biogenesis. We obtained an insertion in ycgR, a putative gene encoding a protein of 244 amino acid residues, which suppresses the motility defect of hns-deficient cells. The abnormally low swimming speed of hns mutant cells was fully restored by an insertion in ycgR, as assessed with computer-assisted motion analysis. A similar suppressor phenotype was observed with a multicopy expression of yhjH, a putative gene encoding a polypeptide of 256 amino acid residues. Since the flagella of most hns-deficient cells were not rotating, except a few with reduced speed, the suppression appears to increase the number of rotating flagella as observed with tethered bacteria. The ycgR and yhjH genes contain the consensus sequence found among the class III promoters of the flagellar regulon, and their expression monitored with a lacZ fusion requires FlhDC. These findings suggest that ycgR and yhjH, together with H-NS, are involved in the motor function and constitute new members of the flagellar regulon.

Bacterial Proteins↗

PubMed1996

Phylogeny of the Chlamydomonadales (Chlorophyceae): a comparison of ribosomal RNA gene sequences from the nucleus and the chloroplast.

Phylogenetic analyses of nuclear-encoded small-subunit rRNA sequences and chloroplast-encoded large-subunit rRNA sequences from flagellate green algae representing the order Chlamydomonadales were found to show considerable congruence. In general, the chloroplast data set exhibited more robust support for comparable lineages than the nuclear data set. The phylogenetic inferences derived from the independent data sets support some, but also challenge many, traditional taxonomic and phylogenetic concepts regarding the green flagellates. Results from phylogenetic analyses of both molecular data sets support six distinct lineages that include taxa from the biflagellate genus, Chlamydomonas, and a basal lineage that comprises taxa from the quadriflagellate genus, Carteria. Both data sets support the conclusion that Chlamydomonas is not monophyletic. Although the chloroplast data are ambiguous regarding the question of Carteria monophyly, the nuclear data fail to support Carteria monophyly. The chlorococcalean genus Chlorococcum was found to have affinities with the Chlamydomonadales, indicating that the traditional concepts of both Chlorococcales and Chlamydomonadales may need revision. The genus Dunaliella is allied within the Chlamydomonadales, supporting the contention that it has lost a typical glycoprotein cell wall.

Animals↗

PubMed1987

Longevity in the protozoa.

In ciliates there are examples of cells which have different proliferation potential in the macronucleus. Those species with limited macronuclear proliferation potential require sex to activate the reserve nucleus. In terms of the capital investment theory, some ciliates invested in their spare nucleus without loss of their original potential, while others accumulated debts and needed the reserve account to maintain life. Other cells neglected maintenance of their reserve account and failed unless their venture capital account was not a self-sustaining venture. Sex provided access to the reserve account and had to occur before deterioration of the reserve account. The question is not when cellular immortality was lost, but rather when immortality was partitioned from a mortal segment. The separation provided the option both for senescence and evolution in multicellular organisms. In colonial flagellates, separation of cells with infinite and finite cell lifespan potential occurred in some species, while in others the separation did not involve loss of immortality. In colonial flagellates, sex did not become an obligate stage. The immortal cells are haploid and could not accumulate damage and live (in contrast with the diploids in the ciliated protozoans). The present theory predicts that differences between species or cells with infinite versus finite lifespan potential may reveal differences in the critical determinants of longevity. Senescence could arise as an accident, as well as a design of nuclear differentiation. Cells therefore may have a much greater reserve for totipotency than would be predicted if they were assumed to lose immortality simply by the act of differentiation.

Aging↗

PubMed1975

The mechanism of swarming of Vibrio alginolyticus.

Factors leading to swarming of Vibrio alginolyticus cells on solid media were studied. Polar flagellated rods from liquid medium develop into small colonies on solid medium. Byproducts, accumulating in the colony area, induce at certain critical concentrations, the formation of peritrichous flagella and development of long heavily flagellated filaments which swarm away form the high by-product concentrations. Several types of nonswarming mutants were isolated, among them, mutants which lack the capacity to form swarming-inducing pyproducts, but can be induced to swarm by byproducts of other mutants incapable of swarming. Different compounds could replace the natural metabolic byproducts; at very low concentration these compounds induce peritrichous flagella and swarming in some of the nonswarming mutants mentioned above. The natural metabolic byproducts accumulating in yeast-extract-peptone medium are suggested to be volatile acids belonging to the valine and isoleucine pathway. Wild-type V. alginolyticus cells cannot swarm on certain substrates but its mutants, able to swarm on many substrates in minimal media, are easily selected.

Arginine↗

PubMed1995

Isolation, in vitro culture, ultrastructure study, and characterization by lectin-agglutination tests of Phytomonas isolated from tomatoes (Lycopersicon esculentum) and cherimoyas (Anona cherimolia) in southeastern Spain.

Plants of Lycopersicon esculentum (grown in greenhouses) and Anona cherimolia cultivated in southeastern Spain were examined for the presence of trypanosomatid flagellates. Kinetoplastid protozoa were found in the fruits but not in the phloem or other plant tissues. Parasites were detected from the onset of fruiting. Isolates were detected from the onset of fruiting. Isolates were adapted to in vitro culturing in monophase media. The form and the structural organization was studied by scanning and transmission electron microscopy. The parasites showed an ultrastructural pattern similar to that of other species of the genus Phytomonas. In tomatoes experimentally inoculated with flagellates cultivated in vitro, we observed that the parasites did not lose their infectious capacity. Three strains of trypanosomatids of the genus Phytomonas, isolated from different species of Euphorbia (E. characias and E. hyssopifolia) and from Cocos nucifera, were compared with our isolates by lectin-agglutination tests. Our isolates were different from the two strains isolated from Euphorbia, but with this technique we could not differentiate our isolates from those of the coconut, nor could we differentiate between the isolates, their ultrastructural similarity together with their similar behavior in the lectin-agglutination test suggesting that these isolates have a common origin.

Agglutination Tests↗

PubMed1994

The phylogenetic position of Dimastigella trypaniformis within the parasitic kinetoplastids.

The nuclear 16S-like rRNA coding regions of two strains of the kinetoplastid flagellate Dimastigella trypaniformis Sandon (strain Ulm and strain Glasgow) were sequenced and phylogenetically analyzed. Strain Ulm was isolated from the hindgut contents of the Australian termite Mastotermes darwiniensis Frogatt, whereas strain Glasgow originates from a soil sample in Scotland. After preparation of genomic DNA the 16S-like rRNA coding regions were amplified using polymerase chain reaction (PCR) technology. The amplification products were cloned in a plasmid vector and sequenced according to standard methods. The sequence of the 16S-like rRNA coding region of strain Ulm differs less than 2% from the sequence of strain Glasgow, indicating that the two strains are most probably members of one species. Phylogenetic analysis of the sequence data positioned D. trypaniformis Sandon as a deep branching lineage near the root of the kinetoplastid group of flagellates.

Animals↗

PubMed1988

The use of fluorochromes in the cytochemical characterization of some phytoflagellates.

Sixteen fluorochromes were tested for the cytochemical characterization of two dinoflagellates (Amphidinuim carterae, Prorocentrum micans) and one chlorophycean flagellate (Dunaliella tertiolecta). Depending on the fluorochrome used, various cellular components (including the plasma membrane, thecal plates, pusule, trichocysts, nucleus, lipid bodies and vacuoles) were revealed. The different colours obtained from single or double fluorochrome staining enabled the differentiation and identification of most cellular components. Protoplasmic staining with Fluorescein diacetate suggested the occurrence of esterases in the three phytoflagellates. Rhodamine B, Neutral Red, FluoroBora P and Nile Blue revealed extensive occurrence of lipoid bodies in A. carterae, but Nile Blue showed considerable difference from the other stains in the inclusion size and intracellular location of these bodies. Chlortetracycline binding, and its inhibition by the Ca2+ionophore A23187, indicated that the plasma membrane, pusule system and trichocysts contain sites of Ca2+ binding. Calcofluor White ST proved superior to Congo Red and Lucifer Yellow in elucidating structural details of the thecal plates of P. micans. While Acridine Orange revealed the presence of surface-coat acidic polysaccharides, the fluoresceinated lectins established their glycoconjugate nature in all the three flagellates. Possible mechanisms of fluorochrome uptake are discussed.

Animals↗