snRNA and heterochromatin formation are involved in DNA excision during macronuclear development in stichotrichous ciliates

Several models for specific excision of micronucleus-specific DNA sequences during macronuclear development in ciliates exist. While the template-guided recombination model suggests recombination events resulting in specific DNA excision and reordering of macronucleus-destined sequences (MDS) guided by a template, there is evidence that an RNA interference-related mechanism is involved in DNA elimination in holotrichous ciliates. We describe that in the stichotrichous ciliate Stylonychia, snRNAs homologous to micronucleus-specific sequences are synthesized during macronuclear differentiation. Western and in situ analyses demonstrate that histone H3 becomes methylated at K9 de novo during macronuclear differentiation, and chromatin immunoprecipitation revealed that micronucleus-specific sequences are associated with methylated H3. To link both observations, expression of a PIWI homolog, member of the RNA-induced silencing complex, was silenced. In these cells, the methylated micronucleus-specific histone H3 variant "X" is still present in macronuclear anlagen and no K9 methylation of histone H3 is observed. We suggest that snRNA recruits chromatin-modifying enzymes to sequences to be excised. Based on our and earlier observations, we believe that this mechanism is not sufficient for specific excision of sequences and reordering of MDS in the developing macronucleus and propose a model for internal eliminated sequence excision and MDS reordering in stichotrichous ciliates.     

A comparative analysis of nematocysts in Pelagia noctiluca and Rhizostoma pulmo from the North Adriatic Sea

Nematocysts of the scyphozoans Pelagia noctiluca and Rhizostoma pulmo were examined. In R. pulmo 4 types of nematocyst were observed: heterotrichous microbasic euryteles; holotrichous isorhizas; atrichous a-isorhizas; and atrichous -isorhizas. In P. noctiluca 5 types of nematocyst were seen: heterotrichous microbasic euryteles; heterotrichous isorhizas (previously described as atrichous isorhizas); holotrichous O-isorhizas; atrichous a-isorhizas; and an undescribed type, which in its structure and discharge mechanism resembles microbasic p-mastigophores. The results show, in both P. noctiluca and R. pulmo, a greater variety of nematocysts than described in previous studies.     

Three new genera and five new species of misophrioid copepods (Crustacea) from anchialine caves on Indo-West Pacific and North Atlantic Islands

Hydra lirosoma sp. nov. is a small, hermaphroditic species possessing broad holotrichous isorhiza nematocysts. The spherical embryo and cobbled embryotheca set it apart from similar species. Hydras with broad holotrichous isorhizas form a distinct cluster of species, but one which was not explicitly represented in the three genera ( Pelmatohydra, Hydra and Chlorohydra ) recognized by Schulze (1917, Archiv für Biontologie, 4(2 ): 29). Schulze failed to recognize this group because of the small number of species known at that time. The hydras that are known now fit naturally into four clusters of species termed, in this paper, the oligactis, vulgaris, viridissima, and braueri groups.     

Genetic heterogeneity in internal transcribed spacer genes of Balantidium coli (Litostomatea, Ciliophora)

The species Balantidium coli is the only ciliate that parasitizes humans. It has been described in other primates, and it has been proposed that the species B. suis from pigs and B. struthionis from ostriches are synonyms of B. coli. Previous genetic analysis of pig and ostrich Balantidium isolates found a genetic polymorphism in the ITS region but its taxonomic relevance was not established. We have extended the genetic analysis to Balantidium isolates of pig, gorilla, human and ostrich origin. We have PCR-amplified and sequenced the ITS region of individual Balantidium cells. The predicted ITS secondary structures of the sequences obtained were transferred by homology modelling to the sequences of other Trichostomatia ciliates (Isotricha, Troglodytella, Lacrymaria and Spathidium) and compared to determine the importance of the differences in the primary sequences. The results show that the ITS2 secondary structure of the species considered follows the general pattern of other ciliates, although with some deviations. There are at least two main types of ITS sequence variants in B. coli which could be present in the same cell and they are common to the mammal and avian hosts studied. These data do not support B. suis and B. struthionis as distinct species.     

The structure and function of the nematocysts of Chironex fleckeri Southcott, 1956

Cell and Tissue Research - Microbasic p-mastigophores, euryteles of two size groups, holotrichous isorhizas and atrichous isorhizas, comprise the cnidom of Chironex fleckeri, a cubozoan that has...     

Molecular phylogeny of litostome ciliates (Ciliophora, Litostomatea) with emphasis on free-living haptorian genera

The monophyly of the litostomes was tested using nine newly sequenced and four previously unpublished small subunit ribosomal RNA (SSrRNA) gene sequences from free-living Haptoria as well as from endosymbiotic Trichostomatia: the vestibuliferids Balantidium coli and Isotricha prostoma, the cyclotrichiid Mesodinium pulex, and the haptorids Loxophyllum rostratum, Dileptus sp., Enchelyodon sp., Enchelys polynucleata, Epispathidium papilliferum (isolates A and B), Spathidium stammeri, Arcuospathidium muscorum, Arcuospathidium cultriforme, and the unusual Teuthophrys trisulca. Phylogenetic analyses depicted the litostomes as a monophyletic group consisting of the trichostomes (subclass Trichostomatia) and the free-living haptorians (subclass Haptoria). The cyclotrichiids Mesodinium and Myrionecta (order Cyclotrichiida) branched either basally within or outside the Litostomatea. In most analyses, the haptorians did not receive support as a monophyletic group. Instead, Dileptus branched basally to all litostome taxa, and Epispathidium papilliferum grouped with the Subclass Trichostomatia. Some subgroupings, however, of haptorian genera corresponded to suggested superfamilial taxa (e.g., orders Spathidiida and Pleurostomatida). Within the monophyletic trichostomes, we can distinguish three clades: (1) an Australian clade; (2) the order Entodiniomorphida; and (3) the order Vestibuliferida. However, Balantidium, currently classified in the Vestibuliferida, did not group with the other vestibuliferids, suggesting that this order may be paraphyletic.     

Radiophryoides puytoraci sp. nov.: Astomatous Ciliate Parasite from a Fresh-Water Oligochaete

A new astomatous holotrichous ciliate, Radiophryoides puytoraci , parasitic in the gut of the Indian freshwater oligochaete is described. This is the second finding of the astomatous ciliate parasite from the microdrili from Asia. Key to all the known and valid species of Radiophryoides is given.     

Cytological studies of the nematocysts of Hydra. I. Desmonemes,isorhizas, cnidocils,and supporting structures

Entire hydras or tentacles were fixed in OsO(4) or in KMnO(4) and thereafter washed, dehydrated, and embedded in a methacrylate mixture. Ultrathin sections were cut on an experimental model, thermal expansion type ultramicrotome or on a Porter-Blume microtome. The sections were examined in an RCA electron microscope. Type EMU-2 D. "Squash preparations" for light microscopy, were made from the hydra mouth region and the attached tentacles. These were observed with an AO Baker interference microscope. In the mature organism, three of the four types of nematocysts normally found in hydra could be positively identified with the electron microscope. The desmonemes, the smallest type, have a dense matrix and a thin capsule. The two different types of mature isorhizas could not be distinguished with certainty. They are intermediate in size between the desmonemes and stenoteles and have a capsule with a dense matrix. The cnidocil, or triggering hair, which is composed of a dense core and a fibrillar sheath has nine supporting elements arranged in a semi-circle near its base. Twenty "supporting structures" are arranged around the nematocyst capsule and interconnections between the supporting elements and these latter structures have been observed. Development of the nematocysts involves an increase in density of the matrix. Spines can be seen in the interior of tubular structures within the capsules of the holotrichous isorhizas.     

淡水鱼类寄生肠袋虫一新种

19851986年,作者于长江上游的四川省忠县、涪陵两地收到的中华倒刺鲃(Barbodes sinensis Bleeker)肠道中发现一种肠袋虫,感染率为50％。经仔细观察比较,确定为一新种,命名为涪陵肠道虫(Balantidium fulinensis sp.nov.),现将其形态描述于后。       

Changes in RNA Synthesis during the Culture Growth Cycle of Tetrahymena

During logarithmic growth of the holotrichous ciliate Tetrahymena pyriformis , as well as in most cell systems, characteristic growth parameters are constant and highly reproducible. If the cells are allowed, however, to perform the complete culture growth cycle, their entry into the stationary phase is accompanied by events too complex to be attributed to "cessation of proliferation". At that stage we observed a sharp increase in uptake and incorporation of tritiated uridine. This seems to be caused by the increase in specific radioactivity of the external precursor supply following consumption of the non-radioactive counterpart. Density gradient centrifugation of pulse-labelled RNA revealed the cessation of ribosomal RNA synthesis at stationary phase to be due to a transition of pulse-labelled RNA from ribosomal to heterogenous low molecular weight RNA profiles. The decrease in ribosomal and the appearance of heterogenous RNA are discussed in terms of degradation and density-dependent selective inhibition of ribosomal RNA.
Evidence of a density-dependent inhibition of culture growth would indicate principles of growth control functioning in a similar way in unicellular organisms as observed in epithelial cells.     

Philaster hiatti 1 n. sp., a Holotrichous Ciliate from Hawaii2

SYNOPSIS. Philaster hiatti n. sp., a marine holotrichous ciliate is described from Hawaii. Anatomic studies were made on specimens treated with the Chatton-Lwoff silver impregnation technic. Particular attention was given to the buccal infraciliature. Anatomic data, especially of the buccal infraciliature, differ from those of Philaster digitiformis, the only species in the genus; a new species, Philaster hiatti, is therefore proposed for this ciliate.     

Intestinal parasites of Agouti paca (Rodentia: Dasyproctidae) in Costa Rica

In a sample of 23 breeding places of pacas (Agouti paca) in Costa Rica, the following parasites were found: Eimeria agoutii, Balantidium coli, Capillaria sp., Trichuris sp., Taenia sp., Strongyloides sp., and members of the superfamilies Strongyloidea and Ascaroidea.     

Morphology of the nematocysts of the medusae of two scyphozoans, Catostylus mosaicus and Phyllorhiza punctata (Rhizostomeae): implications for capture of prey

Abstract. We examined the cnidomes (total complement of nematocysts) of medusae of the zooxanthellate and azooxanthellate jellyfishes Phyllorhiza punctata and Catostylus mosaicus (Rhizostomeae, Scyphozoa), and compared the assemblage of zooplankton captured on the oral arms of each species to determine whether differences in the types or amount of zooplankton captured were consistent with possible differences in the cnidomes. Cnidomes were described using light and scanning electron microscopy. Each species had a distinct cnidome and, in general, specimens of P. punctata appeared to have far fewer nematocysts than those of C. mosaicus. Four types of nematocysts were identified in medusae of C. mosaicus; 2 types of holotrichous isorhizae, rhopaloids, and birhopaloids. In C. mosaicus, the oral arms and bell margins possessed all of these types, but the cnidomes of the 2 regions differed in relative abundances and sizes of isorhizae and rhopaloids. Five types of nematocysts were identified in medusae of P. punctata, although not all types were found in all specimens. Round holotrichous isorhizae were found only in the bell, while oval holotrichous isorhizae, rhopaloids of 2 distinct size ranges, and birhopaloids were found in the bell and oral arms. Cnidomes of the bell and oral arms in specimens of P. punctata also differed in the relative abundance and sizes of oval isorhizae and rhopaloids. Although there were clear differences in the overall cnidomes and absolute abundances of nematocysts in each species, the oral arms (feeding appendages) of specimens of both C. mosaicus and P. punctata had similar types and relative abundances of nematocysts. Zooplankton sampled from the oral arms of each species showed that both species preyed predominantly on copepod nauplii and larvae of gastropods and bivalves. Medusae of C. mosaicus captured ～10 × more gastropod larvae and 5 × more bivalve larvae than those of P. punctata. Specimens of P. punctata captured approximately twice as many copepod nauplii as those of C. mosaicus. Differences in the relative abundance of types of zooplankton captured by each species could not be adequately explained by differences in the cnidomes of the oral arms.     

Cytological Studies of the Nematocysts of Hydra : I. Desmonemes, Isorhizas, Cnidocils, and Supporting Structures

Entire hydras or tentacles were fixed in OsO₄ or in KMnO₄ and thereafter washed, dehydrated, and embedded in a methacrylate mixture. Ultrathin sections were cut on an experimental model, thermal expansion type ultramicrotome or on a Porter-Blume microtome. The sections were examined in an RCA electron microscope. Type EMU-2 D. "Squash preparations" for light microscopy, were made from the hydra mouth region and the attached tentacles. These were observed with an AO Baker interference microscope. In the mature organism, three of the four types of nematocysts normally found in hydra could be positively identified with the electron microscope. The desmonemes, the smallest type, have a dense matrix and a thin capsule. The two different types of mature isorhizas could not be distinguished with certainty. They are intermediate in size between the desmonemes and stenoteles and have a capsule with a dense matrix. The cnidocil, or triggering hair, which is composed of a dense core and a fibrillar sheath has nine supporting elements arranged in a semi-circle near its base. Twenty "supporting structures" are arranged around the nematocyst capsule and interconnections between the supporting elements and these latter structures have been observed. Development of the nematocysts involves an increase in density of the matrix. Spines can be seen in the interior of tubular structures within the capsules of the holotrichous isorhizas.     

Stephanoscyphus eumedusoides n. spec. (Scyphozoa,Coronatae), ein Höhlenpolyp mit einem neuen Entwicklungsmodus

The new solitary scyphopolypStephanoscyphus eumedusoides was detected in submarine caves of the rocky shore near Marseille (Mediterranean Sea), where it lives attached to colonies of corals at a depth of 2–3 m to 40–50 m. The new mode of development has been described briefly in an earlier paper in which the polyp was given the preliminary nameTesseroscyphus eumedusoides (Werner 1971a) but by a more detailed investigation it proved to belong to the genusStephanoscyphus. The essential characteristics of the peridermal tube and the soft body are outlined. Most of them are not sufficient to identify significantly the new species. Identification was possible by the observations on the new mode of development by sessile medusoids which is unique in the order Coronatae and the class Scyphozoa. The medusoids originate in the normal way by the process of strobilation. But other than in the known scyphozoan development by which free-swimming young medusae are produced, the medusoids remain connected with each other and the basal residue of the polyp's body within the peridermal tube. Development, morphology and anatomy of the medusoids are described. As they exhibit essential medusan characteristics they belong to the type of eumedusoid. On the other hand, there are remarkable signs of reduction due to progressive steps of evolution. The hermaphroditic medusoids become mature and reproduce within the polyp's tube. The fertilized eggs develop within the gastric cavity of the medusoids into free-swimming planulae which are released by the chain of degenerating and dying medusoids being pushed out of the tube by the regenerating polyp. After a planktonic period of several weeks, the planula attaches to a substratum in the normal way and undergoes development into the young polyp. This is described briefly. The cnidom of the polyp, the medusoid, and the planula consists of holotrichous haplonemes and heterotrichous microbasic euryteles. The vertical and horizontal distribution, and some details of the ecology are outlined according to the present state of knowledge. Because the new species has been collected and found only in submarine caves it is considered to be a true cave-living animal. Its diagnosis is given.     

Formation of blooms by the symbiotic ciliate Mesodinium rubrum: the significance of nitrogen uptake

Mesodinium rubrum, a holotrichous ciliate that harbors endosymbioticchloroplasts, was responsible for patches of red water in thecoastal upweUing ecosystem at 15°S, Peru during March—May1977. Stations within red patches showed elevated concentrationsof paniculate nitrogen, chlorophyll a and dissolved organicnitrogen (DON), and lower concentrations of nitrate comparedwith areas where there were no ciliate blooms. These naturallyoccurring populations of M.rubrum took up nitrate, ammoniumand DON. Light was required for nitrate uptake and to a lesserextent for ammonium uptake. Dark uptake of ammonium occurredin all experiments. There was no effect of light on DON uptake.Possession of endosymbiotic chloroplasts enables this protozoanto use upwelled nitrate efficiently for development of largeblooms and concentrate into patches in the face of relativelystrong advective regimes.     

Data on intestinal parasites of lower monkeys in the Adler apery

Under captive conditions, a parasite fauna connected with the changes in ecological conditions, feeding, and mode of life is usually formed in monkeys. Species composition of the intestinal parasites has been investigated in six species of the monkeys (Macaca mulatta, M. fascicularis, M. nemestrina, Ceropithecus aethiops, Papio hamadryas, and P. anubis), which were born in the Adler apery and live there for a long time. A comparison with similar investigations carried out in the Sukhumi apery, where the climatic and keeping conditions are practically identical with those in the Adler apery, was conducted. Parasite fauna of monkeys in the Adler apery was found to include three species of Nematoda (Ascaris sp., Trichocephalus sp., and Strongyloides sp.) and two species of Protozoa (Balantidium coli and Lamblia intestinalis). In our material, Trichocephalus sp. is the dominant parasite species among helminthes, and Balantidium coli is the most frequent species of Protozoa. The commonness in the transmission of these parasites and similarity in their life cycles contribute to the forming of polyinvasions in monkeys.     

Sequence-specific fragmentation of macronuclear DNA in a holotrichous ciliate

Macronuclear DNA from the protozoan G. chattoni, a holotrichous ciliate, was analyzed. Most, if not all, of the macronuclear DNA is subchromosomal, ranging in size from above 100 kb down to 2.1 kb, with molecules in the lower molecular weight range being resolvable by gel electrophoresis into reproducible, specific, discrete size classes. A prominent class of linear 9.3 kb molecules consists of single free rRNA genes. Upon denaturation and partial renaturation, a high percentage of total macronuclear DNA was found as single-stranded circles. Sequence analysis showed that a minimum of 38 tandem repeats of the sequence CCCCAA is present in inverted orientation at each end of most or all Glaucoma macronuclear DNA molecules, including the rDNA. This sequence must therefore be recognized during site-specific fragmentation of chromosomes in macronuclear development.     

A coprological study of parasitism in orangutans (Pongo pygmaeus) in Indonesia

Fecal specimens from 89 orangutans (36 captive, 34 rehabilitant, and 19 wild) at different locations in Indonesia were examined. Strongyloides spp, Balantidium coli, and strongylid nematodes were the most common infestations detected. A syngamid nematode, Mammomonogamus sp, is reported for the first time in orangutans.