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1.
Protalveolate phylogeny and systematics and the origins of Sporozoa and dinoflagellates (phylum Myzozoa nom. nov.) 总被引:4,自引:2,他引:2
The protozoan infrakingdom Alveolata comprises the phyla Ciliophora and Miozoa. The name Myzozoa—sucking life—is introduced here to replace Miozoa (protalveolates, dinoflagellates, Sporozoa, apicomonads) as both subphyla (Dinozoa, Apicomplexa) are commonly or ancestrally myzocytotic feeders. We studied ultrastructurally two contrasting myzocytotic flagellates: Colpodella tetrahymenae sp. n. (predatory on Tetrahymena), with an inner membrane complex like Sporozoa, and Voromonas (=Colpodella) pontica gen. et comb. nov., with discrete cortical alveoli like Dinozoa; we also sequenced 18S rDNA of both of these flagellates and of two highly divergent isolates of Oxyrrhis. Phylogenetic analysis shows early divergence between Colpodella, Voromonas and Alphamonas edax and supports the independent origin of dinoflagellates, Perkinsea and Apicomplexa (Sporozoa, Apicomonadea) from myzocytotic protalveolate flagellates. Oxyrrhis is probably a highly modified dinoflagellate, not a protalveolate with primitive chromatin and ciliary organization. The rapid basal radiation of Myzozoa is poorly resolved; the predatory colpodellids sensu stricto are probably sisters of Sporozoa. We discuss early cellular diversification of Myzozoa (=Miozoa) and revise its classification, establishing a new class Myzomonadea for Voromonas, Alphamonas and Chilovora (=Bodo) perforans gen. et comb. nov., three new peridinean subclasses (Oxyrrhia, Gonaulacoidia, Suessioidia), and five new orders: Acrocoelida for Acrocoelus; Voromonadida for Voromonas and Alphamonas; Chilovorida for Chilovora; Rastromonadida for Rastromonas and Parvilucifera; and Algovorida for Algovora, a new genus for Colpodella turpis and Colpodella pugnax sensu Simpson and Patterson. We suggest that the flattened inner membrane complex of Apicomplexa evolved in association with trichocyst loss by fusion of already flattened myzomonad cortical alveoli as an adaptation for actomyosin-based host penetration and gliding motility. 相似文献
2.
The structure of the predatory freshwater flagellate Colpodella pseudoedax was studied. The cell was found to contain two heterodynamic flagella, three-membrane pellicle, micropores, subpellicular
microtubules, microtubular open-side conoid, roptries, micronemes, extrusive organelles (trichocysts), and mitochondria with
vesicular and tubular cristae. Upon discharge, trichocysts form cross-striated bands. A thin-walled cylinder lies in the transitional
zone of the flagella. Cells reproduce by means of longitudinal binary fission. This species differs from similar C. edax by their smaller cell size and lack of reproduction cyst. Similarities between C. pseudoedax and other colpodelids, as well as between colpodellids and perkinseids and sporozoans, are discussed. 相似文献
3.
A. P. Mylnikov 《Biology Bulletin》2009,36(6):582-590
The structure of cells of the predatory flagellates Colpodella pseudoedax and C. unguis was studied. The cell was found to contain two heterodynamic flagella, three-membrane pellicle, micropores, subpellicular
microtubules, microtubular open conoid, roptries, micronemes, extrusive organelles (trichocysts), and mitochondria with tubular
cristae. Upon discharging, trichocysts form cross-striated bands. The thin-walled cylinder lies in the transitional zone of
the flagella. Cells reproduce by means of longitudinal binary fission. The similarities between given species and other colpodelids
and such between perkinsea, sporozoans, and dinoflagellates are discussed. 相似文献
4.
The ultrastructure of the marine predatory flagellate Metromonas simplex Larsen et Patterson was studied. The cell is surrounded by a low-contrast fibrous layer composed of thin hairs covered by
a thin bilayer membrane and an outer layer of thin short fibers. The plasmalemma lies under these layers. The predator captures
whole cells of the prey, usually bodonids or chrysomonads. The cytostome as a cell pocket is undetectable. The long flagellum
bears very thin mastigonemes (hairs) with lengths of 0.8–1.0 μm; the short flagellum is naked and reduced in length. The transitional
zone lacks spirals or other additional elements. The transversal plate is elevated on the cell surface. The flagellar root
system is very simple and has one microtubular band which originates near the kinetosomes. The latter are parallel to each
other and interconnected by fibrous bridges. The vesicular nucleus, Golgi apparatus, and endoplasmic reticulum are of typical
structures. The oval mitochondria of 0.6–2.5 μm contain lamellar cristae. The cylindrical extrusomes (trichocysts) found in
the cytoplasm have lengths of 1.0–1.4 μm and diameters of 0.12–0.08 μm. The trichocysts have a wheel-shaped structure with
13 spokes visible in cross-sections. The contractile vacuole is absent. The similarity that M. simplex shares with Metopion fluens Larsen et Patterson, cryothecomonads, and other predatory flagellates is discussed. 相似文献
5.
6.
The apical complex is one of the defining features of apicomplexan parasites, including the malaria parasite Plasmodium, where it mediates host penetration and invasion. The apical complex is also known in a few related lineages, including several non-parasitic heterotrophs, where it mediates feeding behaviour. The origin of the apical complex is unclear, and one reason for this is that in apicomplexans it exists in only part of the life cycle, and never simultaneously with other major cytoskeletal structures like flagella and basal bodies. Here, we used conventional TEM and serial TEM tomography to reconstruct the three dimensional structure of the apical complex in Psammosa pacifica, a predatory relative of apicomplexans and dinoflagellates that retains the archetype apical complex and the flagellar apparatus simultaneously. The P. pacifica apical complex is associated with the gullet and consists of the pseudoconoid, micronemes, and electron dense vesicles. The pseudoconoid is a convex sheet consisting of eight short microtubules, plus a band made up of microtubules that originate from the flagellar apparatus. The flagellar apparatus consists of three microtubular roots. One of the microtubular roots attached to the posterior basal body is connected to bypassing microtubular strands, which are themselves connected to the extension of the pseudoconoid. These complex connections where the apical complex is an extension of the flagellar apparatus, reflect the ancestral state of both, dating back to the common ancestor of apicaomplexans and dinoflagellates. 相似文献
7.
8.
Pavla Hanousková Petr Táborský Ivan Čepička 《The Journal of eukaryotic microbiology》2019,66(1):120-139
We report the discovery of a new genus of heterolobosean flagellates, Dactylomonas gen. nov., with two species, D. venusta sp. nov. and D. crassa sp. nov. Phylogenetic analysis of the SSU rRNA gene showed that Dactylomonas is closely related to the amoeba Selenaion, the deepest‐branching lineage of Tetramitia. Dactylomonads possess two flagella, and ultrastructural studies revealed an unexpected organization of the flagellar apparatus, which resembled Pharyngomonada (the second lineage of Heterolobosea) instead of Tetramitia: basal bodies were orthogonal to each other and a putative root R1 was present in the mastigont. On the other hand, Dactylomonas displayed several features uncommon in Heterolobosea: a microtubular corset, a distinctive rostrum supported by the main part of the right microtubular root, a finger‐like projection on the proximal part of the recurrent flagellum, and absence of a ventral groove. In addition, Dactylomonas is anaerobic and seems to have lost mitochondrial cristae. Dactylomonas and Selenaion are accommodated in the family Selenaionidae fam. nov. and order Selenionida ord. nov. The taxonomy of Tetramitia is partially revised, and the family Neovahlkampfiidae fam. nov. is established. 相似文献
9.
Prey manipulation through headfirst ingestion is a common foraging tactic in predatory taxa. Sawsharks possess a toothed rostrum that is thought to assist in prey capture, but the process from prey contact to ingestion is unknown. This study provides evidence of headfirst ingestion and possible prey orientation in situ through the use of cone beam CT scans in the common sawshark (Pristiophorus cirratus). CT scans provide an efficient method for assessing ingestion and proposing plausible behavioural tactics for food manipulation in a species difficult to observe in the wild or maintain in captivity. 相似文献
10.
Schoeneck L.Jane; Williamson Craig E.; Stoeckel Mark E. 《Journal of plankton research》1990,12(1):29-40
The diel periodicity and selectivity in the feeding behaviorof the predatory cyclopoid copepod Mesocyclops edax was investigatedat 3 h intervals over two 24 h sampling periods in nature. Gutcontent analyses revealed an increase in gut fullness at 11.30and 20.30 in July, and at 20.30 in August. The increase in gutfullness at these times could not be explained by an increasein prey density, changes in predator-prey overlap or differencesin prey vulnerability. We suggest that M.edax exhibits a truediel periodicity in the intensity of its predatory activities,although the alternative hypothesis of a diel periodicity ingut passage time cannot be ruled out. Vanderploeg and Scavia'sE* selectivity index indicated a preference for rotifer andcladoceran prey over copepods. 相似文献
11.
Summary The predatory copepod Mesocyclops edax preys effectively on the rotifers Asplanchna girodi and Polyarthra vulgaris but not on the rotifer Keratella cochlearis. It readily captures individuals of this latter species but usually releases them unharmed, being unable to remove the soft parts within their loricae. The predatory A. girodi regularly eats K. cochlearis but cannot catch P. vulgaris. When P. vulgaris is contacted by the corona of A. girodi, it immediately escapes by elevating its paddles and jumping away a distance up to about ten times its own body length. In experimental communities of these predator and prey species the survival of Polyarthra and Keratella is significantly affected by the species of predator present and by predator-prey interaction between the two predators when both are present.Supported by National Science Foundation research grant DEB 76-09768 and Public Health Service career development award KO4-GM 70557 to J.J.G. 相似文献
12.
A flagellated predator of the chlorophyte algaDunaliella spp. was examined by light and electron microscopy. Although this predator had previously been identified as a species of the kinetoplastid genusBodo, the present study revealed the flagellate to be indistinguishable fromColpodella pugnax, the type-species for its genus. The flagellate lacks a kinetoplast, a microtubule supported cytopharynx and paraxial rods in the flagella — characters universally found in kinetoplastid flagellates. The cell has mitochondria with vesicular cristae. Multiple membranes surround the cell and are underlain by longitudinal microtubules not originating from the flagellar region. Most notably, the flagellate has micropores and an apical complex including a conoid, sacculate rhoptries and, apparently, a polar ring. This study hs confirmed thatColpodella is the genus with free-living species most closely related to the apicomplexan parasites (i.e. the “Euapicomplexa” andPerkinsus). No unambiguous synapomorphy supports an “apicomplexan parasites” clade: Inclusion ofColpodella is necessary to secure the Apicomplexa as a monophyletic (=holophyletic) taxon. A new family, the Colpodellidae, is erected for this genus. Colpodella turpis, a previously undescribed species that also consumesDunaliella spp., was isolated from the same samples asC. pugnax. A diagnosis for this species is presented together with a brief review of the genus, in which we recognise seven species. The generic namesAlphamonas Aléxéieff,Nephromonas Droop andDingensia Patterson & Zölffel are rendered into synonomy withColpodella. 相似文献
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14.
E. T. HITCHEN 《The Journal of eukaryotic microbiology》1974,21(2):221-231
Cell structure, cell adhesion, and stalk formation have been examined by electron microscopy in the colonial flagellate, Cephalothamnium cyclopum. Each cell is obconical or spindle-shaped, pointed posteriorly and truncated anteriorly. The cell membrane is underlain by epiplasm 0.1 μm thick in the posterior region, but bands of microtubules support the anterior region which is differentiated into a flagellar pocket, oral apparatus and contractile vacuole. Each of 2 flagella, joined a short way above their bases by an interflagellar connective, has a paraxial rod and mastigonemes. One flagellum is free and is important in food gathering while the other is recurrent and lies in a shallow groove on the ventral cell surface but projects posteriorly into the stalk. The basal bodies of these flagella are bipartite structures connected by a pair of striated rootlets with accessory microtubular fibers. The oral apparatus consists of a funnel-shaped buccal cavity and cytostome. It is supported by helical and longitudinal microtubules and also has nearby striated and microtubular fibers. Possible roles of associated oral vesicles in relation to ingestion are discussed. A reticulate mitochondrion houses a massive kinetoplast which has a fibrillar substructure resembling that of dinoflagellate chromosomes. Adjacent flagellates adhere by laminate extensions of their posterior regions and attach by their recurrent flagella to a communally secreted stalk composed of finely fibrillar material. This study indicates that Cephalothamnium belongs in the order Kinetoplastida, and has many features in common with members of the family Bodonidae. 相似文献
15.
Summary A new amylolytic yeastCandida edax CBM20 was isolated from soil. The strain was able to grow at 37°C and pH 4.5 on a soluble starch (mineral salts) medium with a maximum specific growth rate of 0.59 h–1 and a cell yield of 0.58 g per gram utilized starch. The strain synthesized high activities of intra- and extra-cellular -amylase and glycoamylase.Candida edax CBM20 is considered to be a good candidate for single-cell protein production from starch.
Resumen Se ha aislado una nueva levadura amilolítica,Candida edax CBM 20 a partir del suelo. La cepa puede crecer a 37°C y a pH 4.5 en un medio mineral con almidón soluble, obteniendose una tasa de crecimiento máxima de 0.59 h–1 y un rendimiento celular de 0.58 g por gramo de almidón utilizado. La cepa sintetiza elevades actividades de -amilasa y de glucoamilasa tanto intra como extracelulares. Se considera aCandida edax como un buen candidato para la producción de proteínas celulares a partir de almidón.
Résumé Une nouvelle levure amylolytique,Candida edax CBM20, a été isolée à partir du sol. La souche peut pousser à 37°C et pH 4,5 sur un milieu minéral contenant de l'amidon soluble avec un taux de croissance maximum de 0.59 h–1 et un rendement cellulaire de 0,58 g par g d'amidon utilisé. La souche synthétise de fortes activités -amylase et glucoamylase, toutes les deux intra-et extra-cellulaires.Candida edax CBM20 est considérée comme un bon candidat pour la production de protéines d'organismes unicellulaires à partir d'amidon.相似文献
16.
Caulophilus zherikhini, sp. nov. (Curculionidae: Cossoninae) is described from the Late Eocene Rovno amber. The new species is distinguished from
all known species of the genus by its longer rostrum. It is especially similar to C. falini Davis et Engel, 2007 from Dominican amber, from which it probably differs also in the more strongly curved rostrum, less
flattened body, longer and narrower profemur, and shorter elytral setae. 相似文献
17.
The predatory feeding of Mesocyclops edax and Cyclops vicinus was studied using the 14C-labelled Ceriodaphnia and some other kinds of the crustacean zooplankters. When given a choice, both species exhibited clear selection of smaller specimens of prey. The feeding rates depend on the kind of prey. The daily ration for the prey readily accepted by Mesocyclops was roughly equal to the predator's biomass, while it was only one half or one third of the body biomass in Cyclops vicinus. Only about one third of the killed biomass was actually ingested and 21–32% was assimilated when the copepods preyed upon the cladocerans or the copepodid larvae. When fed with naupliar larvae the cyclopoid copepods assimilated over 70% of the killed biomass. Almost one half of the freshly assimilated carbon passes through the short term cycle and is quickly respired and excreted. 相似文献
18.
Peranema trichophorum (Ehrenberg) Stein, a colorless phagotrophic euglenoid flagellate, has a typically euglenoid microtubular root complement. Striated root components, relatively uncommon in euglenoids, are connected to the basal bodies and to a microtubular root. The flagellar system of Peranema consists of three unequal microtubular roots which extend anteriorly beneath the reservoir membrane, and narrow-band striated roots (periodicity = 29–33 nm) which connect one of the four basal bodies to the movable rodorgan of the feeding apparatus. An inter basal body striated fiber forms a three-way connection between one particular microtubular root, a flagellar basal body, and the striated roots. A striated fibril (periodicity = 18–25 nm), which may be an extension of the striated root system, extends beneath the reservoir membrane. Associated with the striated fibril and the striated roots are cisternae of smooth endoplasmic reticulum. 相似文献
19.
Summary Changes in the intracellular distribution of microtubules and microfilaments during amoeba-to-flagellate and flagellate-to-amoeba transformations inPhysarum polycephalum were examined by fluorescence microscopy using anti-tubulin antibody and NBD-phallacidin, respectively. Amoebae contained an extensive microtubular cytoskeleton, which was converted to a flagellar cone structure during transformation to flagellates in liquid medium. When flagellates reverted back to amoebae, this conical structure disintegrated prior to flagella resorption. Amoebae showed some microfilament-enriched domains along the periphery, from which numerous filamentous extrusions, probably pseudopods and filopods, emanated. Flagellates contained a ridge, a sheet-like structure, along their dorsal axis, especially in the earlier stages of flagellation. Another microfilament-enriched thick filamentous structure ran along the dorsal axis, starting from the anterior tip of the cell. This structure apparently coincided spatially with one of the bundles of microtubules. During the reversion to amoebae, other localized microfilaments were transiently observed at the posterior end. A model of cytoskeletal changes in the transformations between these two cell types was proposed. 相似文献
20.
Leucoplast of the cryptomonad Chilomonas paramecium: Evidence for presence of a true plastid in a colorless flagellate 总被引:1,自引:0,他引:1
S. Sepsenwol 《Experimental cell research》1973,76(2):395-409
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