RESUMEN
Ciliated protists represent one of the most primitive and diverse lineages of eukaryotes, with nuclear dimorphism, a distinctive sexual process (conjugation), and extensive genome rearrangements. Among divergent ciliate lineages, the peritrich order Sessilida includes members with a colonial lifestyle, which may hint to an independent evolutionary attempt for multicellularity, although they are still single-celled organisms. To date, the evolution and phylogeny of this group are still far from clear, in part due to the paucity of molecular and/or morphological data for many taxa. In this study, we extend taxon sampling of a loricate group of sessilids by obtaining 69 new rDNA (SSU rDNA, ITS1-5.8S rDNA-ITS2, and LSU rDNA) sequences from 20 well-characterized representative species and analyze the phylogenetic relationships within Sessilida. The main findings are: (i) the genera Rhabdostyla and Campanella each represents a unique taxon at family level, supporting the establishment of two new families, i.e., Rhabdostylidae n. fam. and Campanellidae n. fam., respectively, the former being sister to a morphologically heterogeneous clade comprising Astylozoidae and several incertae sedis species and the latter occupying the basal position within the Sessilida clade; (ii) the structure of infundibular polykinety 3 is likely to be a phylogenetically informative character for resolving evolutionary relationships among sessilids; (iii) differences between sparsely and the densely arranged silverline systems could be a suprageneric taxonomic character; (iv) the monophyly of Vaginicolidae is confirmed, which is consistent with its specialized morphology, i.e., the possession of a typical peritrich lorica which might be an apomorphy for this group; (v) within Vaginicolidae, the monotypic Cothurniopsis sensu Stokes, 1893 is a synonym of Cothurnia Ehrenberg, 1831, and a new combination is created, i.e., Cothurnia valvata nov. comb.; (vi) Vaginicola sensu lato comprises at least two distinctly divergent clades, one affiliated with Thuricola and the other with a systematically puzzling clade represented by Vaginicola tincta.
Asunto(s)
Cilióforos , Oligohimenóforos , Humanos , Filogenia , Cilióforos/genética , Oligohimenóforos/genética , ADN Ribosómico/genética , Cognición , Análisis de Secuencia de ADNRESUMEN
The Peritrichia is a speciose and morphologically distinctive assemblage of ciliated protists that was first observed by Antonie van Leeuwenhoek over 340 years ago. In the last two decades, the phylogenetic relationships of this group have been increasingly debated as morphological and molecular analyses have generated contrasting conclusions, mainly owing to limited sampling. In the present study, we performed expanded phylogenetic analyses of 152 sessilid peritrichs collected from 14 different provinces of China and 141 SSU rDNA peritrich sequences from GenBank. The results of the analyses revealed new divergent relationships between and within major clades that challenge the morphological classification of this group including, (1) the recovery of four major phylogenetically divergent clades in the monophyletic order Sessilida, (2) aboral structures such as the stalk and spasmoneme were evolutionary labile, (3) the stalk or/and spasmoneme was lost in each divergent clade indicating that parallel evolution occurred in sessilid peritrichs and (4) the life cycle and habit drive the diversity of aboral structures as well as diversification and evolution in peritrichs.
Asunto(s)
Cilióforos , Oligohimenóforos , Filogenia , ADN Protozoario/genética , ADN Ribosómico/genéticaRESUMEN
Four epibiotic sessilid peritrichs, i.e., Zoothamnium wilberti n. sp., Baikalonis microdiscus n. sp., Epistylis anastatica (Linnaeus, 1767) Ehrenberg, 1830, and Rhabdostyla commensalisMöbius, 1888, were isolated from one syllid polychaete and three crustacean hosts in Qingdao, China. For each species, specimens were observed both in vivo and following silver staining. Their SSU rDNA was also sequenced for phylogenetic analyses. Zoothamnium wilberti n. sp. is characterized by the appearance of its colony, which is up to 350 µm high, and usually has fewer than 16 zooids, and the dichotomously branched stalk with transverse wrinkles, the conspicuously conical peristomial disc, and infundibular polykinety 3 comprising three isometric ciliary rows. Baikalonis microdiscus n. sp. can be recognized by its barrel-shaped zooid, small peristomial disc, smooth and short stalk, and its unusual infundibular polykinety 3 comprising a long inner row and a short outer row. Two poorly known species, i.e., Epistylis anastatica and Rhabdostyla commensalis, are redescribed and redefined. Phylogenetic analyses reveal that: (i) R. commensalis is closely related to the family Astylozoidae rather than to the morphologically similar Epistylididae; (ii) B. microdiscus n. sp. is sister to the family Scyphidiidae; (iii) E. anastatica groups with vorticellids and ophrydiids, which further supports the polyphyly of the genus Epistylis; and (iv) Z. wilberti n. sp. is nested within the Zoothamniidae, as expected.
Asunto(s)
Crustáceos/parasitología , Oligohimenóforos/clasificación , Poliquetos/parasitología , Animales , China , ADN Protozoario/genética , Oligohimenóforos/citología , Oligohimenóforos/genética , Filogenia , Especificidad de la EspecieRESUMEN
Myxophagan water beetles from Madagascar are comprehensively revised. Holotypes of the two previously known species are re-described and illustrated. Six new species of Incoltorrida Steffan and one new species of Hydroscapha LeConte are described and illustrated. The larvae of Incoltorrida quintacostata are illustrated and discussed. The presence of peritrich ciliates of the genus Platycola Kent on specimens of Incoltorrida madagassica Steffan is discussed and illustrated. Habitus, habitats, and male genitalia are illustrated, and distributions are mapped. The following new species are described (type localities parenthetic): Incoltorrida benesculpta n. sp. (Fianarantsoa, 3.2km S Ambohimanjaka); I. galoko n. sp. (Antsiranana, Diana, Ambilobe, Antsaba, Galoko mountains ); I. magna n. sp. (Antsiranana, Diana, Ambilobe, Antsaba, Galoko mountains); I. marojejy n. sp. (Antsiranana, Sava, Marojejy National Park); I. quintacostata n. sp. (Fianarantsoa, 3.5km N Ivato); I. zahamena n. sp. (Toamasina, Alaotra-Mangoro, Zahamena National Park); Hydroscapha andringitra n. sp. (Fianarantsoa, Ambilavao, Sendrisoa, approx. 10km N of Andringitra National Park).
Asunto(s)
Escarabajos , Distribución Animal , Animales , Ecosistema , Larva , Madagascar , Masculino , AguaRESUMEN
Many protists form cell colonies. Among them several are filter-feeders depending on suspended food particles such as bacteria. It has been suggested that the formation of colonies enhances feeding efficiency and implied that - in the case of colonial choanoflagellates - it was an adaptive trait that led to the evolution of metazoans. Here it is shown experimentally - for a colonial peritrich ciliate and for a choanoflagellate - that colony-formation does not enhance the efficiency of filter-feeding relative to solitary cells and that the adaptive significance of cell colony-formation must have some other explanation.
Asunto(s)
Coanoflagelados/fisiología , Cilióforos/fisiología , Coanoflagelados/citología , Cilióforos/citología , Conducta Alimentaria/fisiologíaRESUMEN
Recently, genetic approaches have revealed a surprising bacterial world as well as a growing knowledge of the enormous distribution of animal-bacterial interactions. In the present study, the diversity of the microorganisms associated to the hydroid Aglaophenia octodonta was studied with epifluorescence, optical, and scanning electron microscopy. Small subunit ribosomal RNA gene sequencing with "universal" and taxon-specific primers allowed the assignment of the microalgae to Symbiodinium and the peritrich ciliates to Pseudovorticella, while the luminous vibrios were identified as Vibrio jasicida of the Harvey clade. To understand the possible relationships among Vibrio jasicida, Symbiodinium, A. octodonta, and Pseudovorticella, specific treatments were conducted in microcosm experiments, with the antibiotic ampicillin and other substances that interfere with bacterial and hydroid metabolism. Treatment of A. octodonta with ampicillin resulted in a decrease of bacterial luminescence followed by Pseudovorticella detachment and Symbiodinium expulsion and suggesting that these microorganisms form a "consortium" with beneficial metabolic interdependence. This hypothesis was reinforced by the evidence that low concentrations of hydrogen peroxide, which stimulate the bacterial oxidative metabolism and luminescence by releasing oxygen, were able to counteract the detrimental effect of ampicillin on the stability of the studied A. octodonta association. A model is proposed in which microalgae that release oxygen during photosynthesis are useful to luminous bacteria for their metabolism and for establishing/maintaining symbiosis leading to a close alliance and mutual benefit of the system A. octodonta-Vibrio jasicida-Pseudovorticella sp.-Symbiodinium sp.
Asunto(s)
Interacciones Microbiota-Huesped/fisiología , Hidrozoos/microbiología , Microbiota/fisiología , Ampicilina/farmacología , Animales , Antibacterianos/farmacología , Bacterias/clasificación , Bacterias/efectos de los fármacos , Bacterias/metabolismo , Biodiversidad , Dinoflagelados/efectos de los fármacos , Dinoflagelados/genética , Dinoflagelados/aislamiento & purificación , Dinoflagelados/fisiología , Peróxido de Hidrógeno , Hidrozoos/clasificación , Hidrozoos/citología , Hidrozoos/efectos de los fármacos , Italia , Microalgas/clasificación , Microalgas/efectos de los fármacos , Microalgas/genética , Microalgas/aislamiento & purificación , Microbiota/efectos de los fármacos , Microbiota/genética , Oligohimenóforos/clasificación , Oligohimenóforos/genética , Oligohimenóforos/aislamiento & purificación , Oligohimenóforos/fisiología , Oxígeno , Filogenia , ARN Ribosómico 18S/genética , Agua de Mar , Simbiosis , Vibrio/efectos de los fármacos , Vibrio/genética , Vibrio/aislamiento & purificación , Vibrio/fisiologíaRESUMEN
This paper gave detailed description of the fine structure of Apiosoma piscicola Blanchard 1885. These parasites were collected from the fry of Tachysurus fulvidraco during parasite surveys of fish at Jiangxia Fish Hatchery in Wuhan, Hubei province in May 2011. Its pellicle, peristomial apparatus, nuclei, trochal band and scopula were described, respectively. The relationship between these peritrich ciliates and their hosts was well discussed herein. The scopula of A. piscicola did not adhere directly to the surface of the host epithelial cells, but by means of a secreted adhesive pad of material according to the present study. Besides, no ultrastructural damage to host epithelial cells could be detected in our work. We concluded that these sessilids should be ectocommensals rather than ectoparasites, but not always harmless. In addition, their great variability of body shape and non-strict host specificity were also discussed.
RESUMEN
The phylogenetic relationships of the ciliate subclass Peritrichia, composed of the orders Mobilida and Sessilida, have recently come under debate as morphological and molecular analyses have struck contrasting conclusions as to the monophyly of the group. We provide additional molecular data to assess the monophyly of the Peritrichia by sequencing the small subunit ribosomal RNA genes of two symbiotic peritrichs, Urceolaria korschelti and Scyphidia ubiquita, found inhabiting the mantle cavity of limpets. Although phylogenetic analyses indicated a nonmonophyletic Peritrichia, approximately unbiased tests revealed that the monophyletic hypothesis could not be rejected. With regard to the Mobilida, our analysis showed divergence within the family Trichodinidae related to host taxa-a molluscan clade and a fish clade. For the Sessilida, the family Scyphidiidae was sister to the Astylozoidae. In our sampling of U. korschelti and S. ubiquita, both species showed significant genetic divergence among geographically isolated, yet morphologically indistinguishable populations. We hypothesize that cryptic speciation has produced these morphologically identical species and argue that more extensive genomic analyses are required to fully assess the monophyly, biogeography, and ultimately biodiversity of the peritrichs.
Asunto(s)
Cilióforos/clasificación , Cilióforos/genética , Gastrópodos/parasitología , Animales , Biodiversidad , Cilióforos/citología , ADN Protozoario/genética , Genes de ARNr , Datos de Secuencia Molecular , Oligohimenóforos/clasificación , Filogenia , ARN Ribosómico 18S/genética , Subunidades Ribosómicas Pequeñas/genética , Análisis de Secuencia de ADNRESUMEN
A limnetic peritrichous ciliate, Epistylis plicatilis Ehrenberg, 1831, was collected from a freshwater ditch beside Moshan Hill, Wuhan, China. Its morphology, infraciliature, and morphogenesis were investigated based on specimens examined in vivo, following staining with protargol and by scanning electron microscopy. The characteristics of the Wuhan population of E. plicatilis are as follows: 1) colonial, each colony typically comprising 30-50 individuals, with a dichotomously branched, noncontractile stalk; 2) fully expanded zooids measure 90-155 × 30-50 µm in vivo; 3) a series of 6 or 7 conspicuous folds appear in the posterior region of the zooid when it contracts; 4) single horseshoe-shaped macronucleus oriented transversely; 5) single contractile vacuole located in peristomial region on dorsal wall of infundibulum; 6) myoneme system comprises 20-24 longitudinal fibers, peristomial disk fibers as a wreath-like net and peristomial ring fibers; 7) narrowly spaced transverse striations on the surface of the body; 8) infundibular polykineties 1 and 2 are three-rowed, infundibular polykinety 3 is two-rowed; and 9) stomatogenesis is of the buccokinetal type; in the new oral apparatus, infundibular polykineties 2 and 3, the haplokinety, and the germinal kinety all originate from the germinal kinety of the parental oral apparatus whereas the polykinety and infundibular polykinety 1 originate from the parental haplokinety. An improved diagnosis of E. plicatilis is supplied.
Asunto(s)
Oligohimenóforos/crecimiento & desarrollo , Animales , Núcleo Celular/fisiología , Núcleo Celular/ultraestructura , División del Núcleo Celular , China , Cilios/ultraestructura , Microscopía Electrónica de Rastreo , Morfogénesis , Oligohimenóforos/ultraestructuraRESUMEN
Vorticella includes more than 100 currently recognized species and represents one of the most taxonomically challenging genera of ciliates. Molecular phylogenetic analysis of Vorticella has been performed so far with only sequences coding for small subunit ribosomal RNA (SSU rRNA); only a few of its species have been investigated using other genetic markers owing to a lack of similar sequences for comparison. Consequently, phylogenetic relationships within the genus remain unclear, and molecular discrimination between morphospecies is often difficult because most regions of the SSU rRNA gene are too highly conserved to be helpful. In this paper, we move molecular systematics for this group of ciliates to the infrageneric level by sequencing additional molecular markers-fast-evolving internal transcribed spacer (ITS) regions-in a broad sample of 66 individual samples of 28 morphospecies of Vorticella collected from Asia, North America and Europe. Our phylogenies all featured two strongly supported, highly divergent, paraphyletic clades (I, II) comprising the morphologically defined genus Vorticella. Three major lineages made up clade I, with a relatively well-resolved branching order in each one. The marked divergence of clade II from clade I confirms that the former should be recognized as a separate taxonomic unit as indicated by SSU rRNA phylogenies. We made the first attempt to elucidate relationships between species in clade II using both morphological and multi-gene approaches, and our data supported a close relationship between some morphospecies of Vorticella and Opisthonecta, indicating that relationships between species in the clade are far more complex than would be expected from their morphology. Different patterns of helix III of ITS2 secondary structure were clearly specific to clades and subclades of Vorticella and, therefore, may prove useful for resolving phylogenetic relationships in other groups of ciliates.
Asunto(s)
Evolución Molecular , Oligohimenóforos/citología , Oligohimenóforos/genética , Filogenia , Composición de Base , Secuencia de Bases , Teorema de Bayes , Análisis por Conglomerados , ADN Espaciador Ribosómico/genética , Modelos Genéticos , Datos de Secuencia Molecular , Alineación de Secuencia , Análisis de Secuencia de ADN , Especificidad de la EspecieRESUMEN
A computerized system was devised to trace the attachment, growth and disappearance of peritrich ciliates in an urban river. By tracing the development of each Carchesium polypinum colony in the river, it was possible to estimate the actual growth rate of this species without considering the effect of immigration. The survival and colonization rates of the colonies and individuals of solitary species could also be estimated. C. polypinum showed high growth rates (r=1.370 day-1, doubling time 12.14 h). The number of daily colonizers also increased at a high rate, and the combination of growth and colonization caused very high population increase rates at the area level. Because of its low survivorship, the rate of Vorticella microstoma increase was much lower than previously reported. The survival of solitary species and small colonies was lower than with large colonies, and fewer new colonizers survived with the development of the attached microbial community.