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1.
Gymnodinium acidotum Nygaard, a blue-green dinoflagellate previously shown to contain cryptophycean chloroplasts and other organelles, was observed from water and soil samples and in culture. The dinoflagellate excysts from soil samples as a mononucleated colorless cell that is positively phototactic. Colorless cells in unialgal culture remain colorless and can only be maintained less than one week whereas pigmented cells cultured unialgally grow for 10 days but then decline rapidly. Colorless cells cultured with Chroomonas spp. regain chloroplasts and have been maintained in mixed cultures for nine months. Fifty-seven percent of the dinoflagellates from mixed cultures are bi-nucleated, and three cells have been observed possibly ingesting cryptophytes. We suggest that cryptophycean chloroplasts are retained and possibly utilized by G. acidotum for at least ten days and then digested.  相似文献   

2.
The genusPrototheca is composed of colorless algae. Plastids, a characteristic feature of colorless algae, are absent fromP. filamenta cells. The growth pattern seen with light and scanning electron microscopes, and the ultrastructure observed with the transmission electron microscope suggest thatP. filamenta is a fungus. Consequently we recommend the removal ofP. filamenta from the genusPrototheca and subsequent investigation of this organism to determine its correct taxonomic placement among the fungi.  相似文献   

3.
Chilomonas paramecium is a colorless cryptomonad flagellate which contains a leucoplast. The structural features of the leucoplast parallel those shown in the cryptomonad chloroplast, exemplified by Cryptomonas ovata. An electron microscopic study of this colorless organelle shows it to be divided into two compartments: the outer compartment contains starch granules and 220 Å ribosomes similar to cytoplasmic RNP particles. The inner compartment often contains carotenoid-like masses, 160 Å ribosomes significantly smaller than those in the outer compartment, and DNA-like filaments. Cesium-chloride density gradients of the whole-cell DNAs show three DNase-sensitive satellites in addition to the major fraction. One of them is presumed to be associated with the leucoplast. Evidence for the existence of true plastids in bleached and colorless flagellates is reviewed.  相似文献   

4.
The preparation of the co-oligopeptides of the series H-Gly-Trp-(Gly)n-Trp-Gly-OH (n = 0, 1, and 2) and of a number of other unprotected co-oligopeptides of glycine and tryptophan is reported. The syntheses have been carried out by conventional methods, using, in general, N-hydroxysuccinimide esters for the coupling steps. All the oligopeptides were obtained after purfication as colorless and crystalline products, and gave only one spot on thin-layer chromatography. Specfic problems connected with the synthesis and purficiation of optically pure tryptophan-containing peptides are discussed.  相似文献   

5.
Deinococcus radiodurans R1, a red-pigmented strain of the extremely radioresistant genus Deinococcus, contains a major carotenoid namely deinoxanthin. The high resistance of this organism against the lethal actions of DNA-damaging agents including ionizing radiation and ultraviolet light (UV) has been widely reported. However, the possible antioxidant role of carotenoids in this strain has not been completely elucidated. In this study, we constructed two colorless mutants by knockout of crtB and crtI genes, respectively. Comparative analysis of the two colorless mutants and the wild type showed that the two colorless mutants were more sensitive to ionizing radiation, UV, and hydrogen peroxide, but not to mitomycin-C (MMC). With electron spin resonance (ESR) and spin trapping techniques, we observed that hydroxyl radical signals occurred in the suspensions of UV irradiated Deinococcus radiodurans cells and the intensity of signals was influenced by carotenoids levels. We further showed that the carotenoid extract from the wild type could obviously scavenge superoxide anions generated by the irradiated riboflavin/EDTA system. These results suggest that carotenoids in D. radiodurans R1 function as free radical scavengers to protect this organism against the deleterious effects of oxidative DNA-damaging agents.  相似文献   

6.
Khawkinea quartana, a naturally occurring colorless homologue of Euglena, was examined with the electron microscope. The organism is biflagellate though only one of the 2 flagella emerges from the anterior reservoir. The pellicular strips covering the body of the organism are supported by microtubules which are continuous in part with microtubules bordering the reservoir. Additional rows of microtubules are found associated with the kinetosomes. An eyespot is located in the wall of the reservoir and, adjacent to it, the contractile vacuole. The nucleus, mitochondria, and Golgi complexes are similar to those described in other euglenoid flagellates. The food reserve is paramylon. The study supports the phylogenetic origin of Khawkinea from pigmented Euglena through the loss of chloroplasts.  相似文献   

7.
Aecidium dispori forms spermogonium and aecium onDisporum sessile andD. smilacinum, which are distributed in East Asia. TheAecidium species is found to be an aecial anamorph of aPuccinia fungus, with its uredinial-telial stage being formed onCarex conica, C. dolichostachya subsp.multifolia, C. pisiformis subsp.alterniflora andC. rugata. Urediniospores of this fungus are large, colorless, thick-walled with 4–5 equatorial germ pores. The morphological characteristics of urediniospores and the spermogonial-aecial host do not fit to any set of circumscribing characters of previously described species. We consider the fungus to be a new species and propose a new name,Puccinia albispora, for the fungus.  相似文献   

8.
A gene encoding phytoene desaturase (crtI) in the carotenoid biosynthetic pathway of Sphingomonas elodea ATCC 31461, an industrial gellan gum-producing strain, was cloned and identified. This gene is predicted to encode a 492-amino acid protein with significant homology to the phytoene desaturase of other carotenogenic organisms. Knockout of crtI gene blocked yellow carotenoid pigment synthesis and resulted in the accumulation of colorless phytoene, confirming that it encodes phytoene desaturase. Further research indicates that the yield of gellan gum production by crtI gene knockout mutants is almost the same as that by the wild-type strain. In addition, a recovery method based on the colorless fermentation broth of the crtI gene knockout mutant was investigated. Compared to the volume of alcohol for the parent strain, much less alcohol (30%) is required in this recovery process; thus, the costs of downstream purification of gellan gum can be substantially reduced.  相似文献   

9.
ABSTRACT. A new genus of rigid, colorless, phagotrophic euglenoid is described from a standing pond on a salt marsh. The cell body measures 21–25 μm long, is about 18 μm wide, has a slight dorso-ventral flattening, and is marked by distinct pellicular ridges. The organism, described as Serpenomonas costata, has two unequal, antapically inserted, heterodynamic flagella. The shorter flagellum is anteriorly directed during swimming and the longer one trails posteriorly. Cells move along the substrate with a creeping motion. The ingestion apparatus is composed of separate ribs extending the length of the cell and is incorporated into the ventral pellicular ridge. The apparatus is independent of the canal and reservoir and is not protrusible. The taxonomic affinities of Serpenomonas with other euglenoids are discussed.  相似文献   

10.
Summary The pigments of the endosymbiotic algae in Cyanophora paradoxa (colorless cryptomonad) and Glaucocystis nostochinearum (colorless Chlorophyceae) and two Rhodophyceae, Porphyridium aerugineum and Asterocytis ramosa have been examined. Both endosymbionts contain chlorophyll a, -carotene, zeaxanthin, C-phycocyanin and small amounts of allophycocyanin. Porphyridium has been shown to contain chlorophyll a, -carotene and zeaxanthin, as does Asterocytis ramosa. The biliproteins of Porphyridium have not been examined, but evidence is presented to suggest that Asterocytis ramosa may contain R-phycocyanin and possibly C-phycocyanin. The taxonomic implications of these results have been discussed, especially with regard to cyanome symbionts and their evolution from and classification with the Cyanophyceae.  相似文献   

11.
A hypomycete fungus with colorless clavate conidia was isolated from soybean roots. Seven rhizosphere bacteria andAzotobacter from an alternate source induced ascocarps in culture plates. Some bacteria retarded mycelial growth rate and some promoted conidiation. The anamorph and teliomorph resembleDactylella rhopalota Drechsler andOrbilia sp. respectively.  相似文献   

12.
Feces from a specimen of Tamandua tetradactyla (Linn.) from Portel, Para State, north Brazil, contained two different coccidial oocysts; one identified as Eimeria tamanduae Lainson 1968, and the other as a new species, described here as Eimeria corticulata n. sp. Oocysts of E. corticulata are ellipsoidal, 37.4 × 30.4 (31.2–43.7 × 23.7–35.0) μm, shape index (length/width) 1.2 (1.0–1.5). Oocyst wall 2.5–3.7 μm thick and composed of two layers; an outer thick, brown-yellow one with radial striations, and a thin inner smooth one: no visible micropyle. Oocyst residuum a large globule of about 10.7 × 10.3 μm, usually accompanied by a number of smaller attached globules. Sporocysts ellipsoidal, 21.0 × 11.0 (20.0–22.5 × 10.0–12.5) μm, with a conspicuous Stieda body: shape index 1.9 (1.6–2.2). Sporocyst residuum a small number of scattered granules: sporozoites 18.7 × 5.0 μm, with a large posterior refractile body. Eimeria zygodontomyis n. sp. is described in feces from Zygodontomys lasiurus (Lund) from the Serra dos Carajas, Para. Oocysts ellipsoidal to cylindrical, 16.5 × 12.0 (13.7–18.7 × 11.2–12.3) μm, shape index 1.4 (1.2–1.5). Wall colorless, smooth, single-layered and about 0.6 μm thick: no micropyle. No oocyst residuum, but a polar granule of about 1.8 × 1.0 μm is sometimes present. Sporocysts ellipsoidal, 8.4 × 5.5(7.5–8.7 × 5.0–6.2) μm, shape index 1.5 (1.4–1.7), with a thin colorless wall and a delicate Stieda body. Sporozoites enclose a compact residuum of about 2.5 × 3.7 μm.  相似文献   

13.
In Spirodela oligorhiza and Wolffia punctata ultraviolet energy induces the conversion of colorless flavans present in scattered idioblasts to red-brown phlobaphene-like compounds. The rare appearance of pigment cells in laboratory grown material is discussed.  相似文献   

14.
Summary An electron microscope study of the colorless mutant I 125 of Chlorella vulgaris shows that the algae contain plastids with a lamellar system.  相似文献   

15.
Colpomenia borea sp. nov. is described from Hokkaido, Japan and Magadan, Far East Russia based on morphological observations and molecular analyses using mitochondrial cox3 and chloroplast rbcL genes. This new species is distinguished from other Colpomenia by its small globular to ovoidal thallus up to 5 cm in diameter, and thin thallus membrane composed of a cortex of one to two-cell layers and a colorless medulla of up to three layers. This species is epiphytic on the brown alga Stephanocystis in areas protected against waves. The life history in culture of C. borea was investigated and the observed life history pattern was similar to those reported in C. peregrina and C. sinuosa. Our phylogenetic analyses supported that C. borea is a distinct species, yet it is more related to C. peregrina than C. sinuosa.  相似文献   

16.
A new species of a chlorarachniophyte alga, Bigelowiella longifila sp. nov., is described. It is classified as a member of Bigelowiella as flagellate cells constitute the main stage of the life cycle. However, this alga is different from the only described species of the genus, B. natans Moestrup, in having a unique amoeboid stage in the life cycle. We observed an interesting behavior of amoeboid daughter cells after cell division: One of the two daughter cells inherits the long filopodium of the parental cell, and it subsequently transports its cell contents through the filopodium to develop at its opposite end. The other daughter cell forms a new filopodium. This unequal behavior of daughter cells may have evolved before the chlorarachniophytes and some colorless cercozoans diverged.  相似文献   

17.
It is revealed experimentally that predatory alveolate flagellates Colpodella angusta Simpson et Patterson, C. edax Simpson et Patterson, and Voromonas pontica (Mylnikov, 2000) Cavalier-Smith, 2004 eat its prey by sucking out the insides through the front of its own body (rostrum). Feeding spectra of these predators include bodonids, percolomonads and colorless chrysomonads, while colorless euglenoids, cryptomonads, ciliates and naked amoebas are unsuitable food for them. Predators’ rostrum contains a microtubular structure (pseudoconoid) complemented by microtubular bands, micronemas or rhoptries. It is shown that the pseudoconoid begins near the kinetosomes of flagella and passes along the flagellate pocket into the rostrum. The pseudoconoid forms an unlocked cone in Colpodella angusta and Voromonas pontica, while, in Colpodella edax, it coils significantly without forming a cone. The similarity between the pseudoconoid and associated structures of predatory flagellates with analogous structures in other colpodellids, percinzoids, dinoflagellates and sporozoans is discussed.  相似文献   

18.
Summary A colorless mutant of the extremely halophilic bacterium, Halobacterium salinarium, has been isolated. In comparative experiments with the carotenoid-containing wild type, it was shown that neither type was killed upon exposure to bright sunlight under aerobic conditions. Exposure to tungsten light of an incident intensity comparable to that of bright sunlight inhibited strongly the growth of the colorless mutant; the growth of the carotenoid-containing wild type was unaffected.In their natural habitats, the extremely halophilic bacteria are usually exposed to bright sunlight. It seems likely that such light will affect the growth of these bacteria as does tungsten light. It is therefore inferred that in their natural habitats, carotenoid-containing forms will develop more freely than colorless forms, because the pigments protect the cells against an inhibitory effect of light upon growth. Carotenoid-containing forms have therefore come to dominate the population of extremely halophilic bacteria in nature.  相似文献   

19.
Summary The pal-rec-low-o is a special repressed state of the pallida-recurrens allele, which normally mutates from the recessive to the dominant condition, giving pigmented Pal spots on corolla lobes. The pal-rec-low-o in the homozygous condition is stably colorless (except for rare mutant spots), but when crossed with the recessive tester strain, pal-tub pal-tub (also stably colorless), the mutation frequency of the particular repressed state of pal-rec (i.e., pal-rec-low-o) increases spectacularly, giving several shifts of varying sizes. The evidence suggests that the activity of the repressed state of the: pal-rec-low-o allele is dependent on the presence of an independently located Pr element, contributed by the pal-tub tester strain. In the absence of such a regulatory element, the repressed allele exhibits stable expression due to the effect of a repressor Rp element residing at or near the locus. It has also been shown that the pal-tub regulatory element, Pr, while coming through a phase of heterozygosity, could be changed either by picking up an element from the stabilized colorless original strain which, being dominant, suppresses the gene action completely; or a change may take place in pal-tub's own regulatory machinery, which otherwise has characteristics of gene regulation. However, the pal-tub regulatory element, when inactive, can be made trans-active by introducing a fresh regulator into the genome, which may segregate at meiosis.  相似文献   

20.
Alkylphenols were effectively treated with horseradish peroxidase at pH 7.0 and 30 °C in the presence of H2O2 and poly(ethylene glycol) irrespective of the relative position or isomeric form of the alkyl chains. Water-insoluble oligomer precipitates were readily filtered out after enzymatic treatment, and transparent and colorless solutions were obtained for all p- and m-alkylphenols used.  相似文献   

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