J. Grain

An attempt at reconstructing a phylogenetic tree of the Ciliophora using parsimony methods

Summary Phylogenetic trees were constructed for the Ciliophora using a parsimony analysis that applies the Camin-Sokal method to characters of known polarity and the Wagner method (which requires no knowledge of the ancestral state) to the other characters. The data covered 56 species and 23 morphological, nuclear and ultrastructural multistate characters. Since no real-world outgroup can be assumed with certainty to root the ciliophoran tree, we used three hypothetical ancestor hypotheses; only one of them (hypothesis 3: somatic kinetosomes in pairs considered ancestral; no character transformation series assumed for the position of the buccal area or for the organization of the buccal infraciliature) produced interesting trees. Two trees, called A and D, have been retained because they were shorter than the others and were equally optimal for different codings of the hypothetical ancestor. In tree A, there is an early separation in two main branches. The first one contains two groups: the Karyorelictea-Heterotrichea (Postciliodesmatophora) and the Hypotrichea-Oligotrichea (Spirotricha) on the one hand, and the colpodids (Transversala) on the other. The second branch leads to 3 groups containing all other ciliates. In tree D, the Postciliodesmatophora and Spirotricha are first separated from all other ciliates; this is in agreement with molecular phylogenies. Despite these differences, the same five major groups appear in both trees; the main difference is in the position of the colpodid group. Class Karyorelictea appears to be polyphyletic, with (a) a Loxodia-Trachelocercia line whose genera share the same type of somatic cortex and nuclear organization, and (b) a Protoheterotrichia-Protocruziidia line which is closer to the Heterotrichia. Nyctotherus is closer to the hypotrichs than to the heterotrichs. As in the molecular trees, the heterotrichs are closer to some of the Karyorelictea, with which they share the same main type of cortical cytoskeleton (postciliary ribbons), than to the hypotrichs and oligotrichs, where the cortical microtubules are not postciliary fibers. So, there are two competing types of reinforcement of the cell cortex by microtubules, and these were selected as early as the first (in tree D) or the second branching (in tree A); this is justification enough to consider the subphylum Tubulicorticata as totally artificial. The validity of the subphylum Filocorticata is also discussed, considering the cortical cytoskeleton of some of the Vestibuliferea (Blepharocorythida and Entodiniomorphida). The Litostomatea, Vestibuliferea and Phyllopharyngea emerge as a sister-group of the Oligohymenophorea. In the phyllopharyngids, macronuclear DNA is gene-sized, as in the hypotrichs; this means that DNA fragmentation occurs independently in different lineages. Macronuclear characters concerning chromatin organization that depend on the size of the DNA molecules have become diversified into paraphyletic lines such as the phyllopharyngids, oligotrichs and hypotrichs for the character “DNA duplication in replication bands”. Nassula is separated from the Furgasonia-Pseudomicrothorax group, which is close to the scuticociliates. Nassula is close to Coleps . The peniculids branch away markedly from the tetrahymenids and are closer to the scuticociliates and peritrichs. The results are discussed with reference to some other new data, phylogenetic reconstructions and molecular trees.

On Paraptychostomum almae N. G., N. Sp., a Commensal Ciliate from the Digestive Tract of Oligochaetes of the Cameroons, in a New Subclass Hysterocinetia

ABSTRACT. Morphological and ultrastructural studies on a new ciliate, Paraptychostomum almae, from the digestive tract of an oligochaete (Alma emini) from the Cameroons are carried out. The flattened cell has a large size; its left lateral face bears an anterior thigmotactic zone that includes seven‐nine short kinetal segments. The somatic cortex is composed of flattened alveoli, a thin epiplasm and a microfibrillar ecto‐endoplasmic boundary. Kineties are made of monokinetids, each particularly characterized by a long anteriorly directed kinetodesmal fiber, and a hyperdivergent postciliary ribbon. The postero‐ventral buccal apparatus consists of a short peristome and a deep longitudinal infundibulum. The paroral organelle is a long stichodyad. The three adoral organelles are of different types: ADI and AD3 are of the membranoid type, respectively with two and one rows of ciliated kinetosomes; AD2 is of the peniculus type with six‐seven rows of ciliated kinetosomes. A microfibrillar network with nodes arises from all the buccal kinetosomes and extends under the naked wall. Mitochondria are small and numerous and dispersed throughout the whole cell. The existence of an AD2 with more than two rows of kinetosomes warrants the creation of the new genus Paraptychostomum and a new family, Ptychostomatidae. The presence of a distinct ecto‐endoplasmic boundary and of somatic kinetids exclusive without transversal dense tractus, hyperdivergent postciliary ribbons, and dispersed numerous mitochondria, added to particularities of the stomatogenesis, allow us to clearly separate hysterocinetians from the scuticociliates and to set up for them the new subclass Hysterocinetia, within the class Oligohymenophorea, with a single new order Hysterocinetida.

Contribution to the study of hysterocinetidae Ciliates of the genus Ptychostomum. Description of six new species

Summary Six new species of Ciliates belonging to the genus Ptychostomum are described. They were found in the intestine of Glossoscolecidae Oligochaetes of the genus Alma from Cameroon. Though their organizational plan is basically the one of the genus and of the family Hysterocinetidae, the variability of certain particular characteristics confirms the existence of a large diversity within the genus, that forces reexamination of the diagnosis of the genus Ptychostomum .

A morphological and ultrastructural study of Kozloffia catenula de Puytorac, 1968 (Ciliophora, Hysterocinetidae)

Summary The morphological study of Kozloffia catenula from silver impregnations brings new details on the sucker (presence of cytoskeletal fibers, absence of fragments of kineties) and the first description of the buccal infraciliature. Ultra-structural observations confirm that the latter is similar to that of Preptychostomum , with a paroral (stichodyad) and 3 adorai organelles. The second adorai organelle is segmented in two parts (AD2, AD2′). AD1, AD2 and AD2′ have 2 rows and AD3 only 1 row of ciliated kinetosomes. In the somatic cortex, the arrangement of the somatic kinetid confirms the existence of a particular hysterocinetian type of monokinetid. In the subclass Hysterocinetia, Kozloffia must be placed in the family Hysterocinetidae, clearly separated from the family Paraptychostomatidae.

Interactions entre espèces microbiennes anaérobies dans le rumen

HAL is a multi-disciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L’archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d’enseignement et de recherche français ou étrangers, des laboratoires publics ou privés. Interactions entre espèces microbiennes anaérobies dans le rumen Ph. Gouet, J. Grain, H. C. Dubourguier, G. Albagnac

Ciliés Hysterocinetidae des genres Amieta et Thurstonia: description de 4 espèces, dont 3 nouvelles, endocommensales de l'Oligochète Alma nilotica

Summary The four described species of Ciliates Hysterocinetidae are commensal of the digestive tract of Alma nilotica (Oligochaete Glossoscolecidae, from Cameroons). They have in common a sucker with two posterior lips separated by a space in which anterior extremities of a few somatic kinetics enter. The sucker is devoid of cytoskeletal fibers. Three species are new, two of which belong to the new genus Amieta ( A. prolifera, A. rotundus ); the third belongs to the genus Thurstonia ( T. almae ). The species T. kaczanowskii is redescribed. The genus Amieta differs from Thurstonia in its ovoid shape, symmetrical aspect of the sucker and transversal position of the macronucleus.

Changes in the organization of the microfilamentous cortical cytoskeletal system during oral regeneration in Climacostomum virens (ciliate)

Summary— With specific antibodies directed against non‐actin micrifilaments (NAMFs), it was possible to determine the spatial distribution of these cytoskeletal elements within the cell cortex of the ciliate Climacostomum virens by immunofluorescence. In the somatic areas, the antibodies allowed to vizualize a more or less continuous layer spanning the whole cell surface with a higher amount of filaments just beneath the ciliary rows. In the buccal region the NAMF system forms bundles running parallel to the ciliary clusters termed the membranelles. The same procedure was used on cells treated with 1 M urea, an agent which induces the release of the oral apparatus followed by a complete regeneration of this part of the cell body. Such an approach completed by an electron microscopy study allowed us to describe the dynamic of NAMFs in the region where new ciliary membranelles will organize from a few somatic kinetics. We observed that in this region, the NAMF system undergoes a desorganization‐reorganization cycle during oral apparatus regeneration. This cycle may be related to the destabilisation of the cortex which allows kinetosome proliferation and to its restabilisation which corresponds to the definitive positioning of the new kinetosomes. Consequently, regeneration of C virenss oral apparatus seems to be a good model for studying relations between cortical NAMF cytoskeleton, positioning of kinetosomes, and cortical stabilisation.

Description of the new genus Hysterocinetoides (Ciliophora, Hysterocinetidae) and revision of the systematics of the subclass Hysterocinetia

Two new species belonging to the new genus Hysterocinetoides are described after protargol staining. They were found in the intestine of worms of the genus Alma (Oligochaeta, Glossoscolecidae) from Cameroon. Their buccal apparatus and kinetosomal infraciliature are typically those of the family Hysterocinetidae. But the sucker has an inverted-U shape and is devoid of skeletal fibers and isolated segments of kineties. These characters justify the creation of the new genus. A review of the diversification of genera among the family Hysterocinetidae is followed by a revision of the systematics of the subclass Hysterocinetia.

Possible modes of microtubule nucleation and of broadening of cortical microtubular ribbons in the ciliate Climacostomum virens

Summary In ciliates, the dense material which surrounds the proximal part of the kinetosomes (Ks) is generally considered as an MTOC which nucleates the microtubules (Mts) whose arrangement gives rise to nematodesmata, transverse (T) and postciliary (Pc) fibers. These last two ribbons are composed of a few Mts near their origin, but can widen out while extending away from the Ks. This broadening is studied for T and Pc fibers in different parts of the cell of C. virens . It is shown that, in somatic dikinetids, T and Pc fibers enlarge by progressive addition of new Mts, one after the other, as they extend far from the Ks. In membranelles and peristomial kinetids, posterior Pc fibers also enlarge by this progressive broadening . In paroral dikinetids, the posterior Pc fiber does not enlarge by this process; two other ready-made ribbons (R1, R2) are added successively to the Pc ribbon to form a wide cytopharyngeal ribbon, a process called sequential broadening . Nucleation of Pc, T, R1 and R2 microtubules is then discussed. For none of these Mts is a distinct capping dense material identified that would act as a capping MTOC. So, we hypothesize that these Mts are generated by lateral nucleation, according to two possible processes that could be combined: one is a nucleation from lateral dense material, the second from a lateral interaction with a pre-existent adjacent Mt (“linker nucleation”).