Cross-striated Band Research Articles

Morphology and SSU rDNA sequences of four cyrtophorian ciliates from China,with description of a new species (Protista, Ciliophora, Phyllopharyngea).

Four cyrtophorian ciliates, Chlamydodon pararoseus sp. n., Chlamydodon bourlandi Qu et al., 2018, Dysteria crassipes Claparède Lachmann, 1859, and Dysteria monostyla (Ehrenberg, 1838) Kahl, 1931, isolated from coastal waters off China, were investigated using morphological and SSU rDNA sequencing techniques. C. pararoseus sp. n. can be recognized by having a kidney-shaped body, a complete cross-striated band, 44-51 somatic kineties, and 11-14 nematodesmal rods. The other three species were re-described based on new populations. Additionally, the SSU rRNA genes of C. pararoseus sp. n. and D. monostyla were sequenced for the first time. Phylogenetic analyses inferred from SSU rRNA gene sequences reveal that C. pararoseus sp. n. has a close relationship with C. bourlandi and C. mnemosyne Gong et al., 2005 within the genus Chlamydodon; and D. monostyla and D. crassipes cluster with its congeners, which confirms their generic assignments.

Diversity of the cyrtophorid genus Chlamydodon (Protista, Ciliophora): its systematics and geographic distribution, with taxonomic descriptions of three species

The ciliate genus Chlamydodon is characterized by a unique cross-striated band (CSB) along the cell perimeter. To date, more than 15 nominal species have been assigned to this genus, all of which are exclusively from marine or brackish water. In the present work, we have revised the genus according to the available data and suggest an illustrated key to aid species diagnosis. In addition, the systematic relationships of chlamydodontid congeners were analysed based on SSU rRNA gene sequences, indicating that all congeners belong to a well-defined clade. Furthermore, we investigated three species from coastal areas of China, including two new species, Chlamydodon wilberti sp. nov. and C. bourlandi sp. nov., using morphological and phylogenetic criteria. Chlamydodon wilberti sp. nov. is characterized by a cell size of 65–105 × 35–60 µm, a complete CSB, and 38–49 somatic kineties. Chlamydodon bourlandi sp. nov. has a cell size of 150–250 × 65–150 µm, a complete CSB, a reddish to violet cell colour, 83–97 somatic kineties, and 40–68 contractile vacuoles. As a further contribution, a well-studied species, C. triquetrus (Müller, 1786) Kahl, 1931, is also re-described.www.zoobank.org/urn:lsid:zoobank.org:pub:B83A5466-9D2B-4502-9A23-F16A61D48172.

A Contribution to the Morphology and Phylogeny of Chlamydodon, with Three New Species from China (Ciliophora, Cyrtophoria)

Three new cyrtophorian ciliates isolated from coastal areas of China were described based on morphological and genetic data. The Chlamydodon mnemosyne-like species Chlamydodon similis sp. n. differs from its congeners mainly by its number of somatic kineties. Chlamydodon oligochaetus sp. n. is distinguished from its congeners mainly by having fewer somatic kineties, and/or an elongated body shape. Chlamydodon crassidens sp. n. is characterized mainly by an inverted triangular body shape, a posteriorly interrupted cross-striated band (5-6μm wide), and a large cytostome. Moreover, we provided small-subunit (SSU) rDNA sequences of C.similis sp. n. and C.oligochaetus sp. n. Maximum likelihood (ML) and Bayesian inference (BI) consistently placed C.similis sp. n. as a sister to C.paramnemosyne, but showed different branching position of C.oligochaetus sp. n., which may be due to a low taxon sampling in the Chlamydodontidae and/or an insufficient resolution of the marker gene at species level.

Morphological and Molecular Description of Three New Species of the Cyrtophorid Genus Chlamydodon (Ciliophora, Cyrtophoria)

This study investigates the morphology and molecular characteristics of three new cyrtophorid ciliates isolated from China seas: Chlamydodon salinus n. sp., Chlamydodon caudatus n. sp., and Chlamydodon paramnemosyne n. sp. Of these, C. salinus n. sp. differs from its congeners through a combination of body size, a cross-striated band that is not continuous, the presence of 30-34 somatic kineties, 11-15 nematodesmal rods, and 13 contractile vacuoles. Chlamydodon caudatus n. sp., meanwhile, is characterized by having a conspicuous tail, a continuous cross-striated band, 34-40 somatic kineties, about 15 contractile vacuoles, and 20-24 nematodesmal rods. Compared with other Chlamydodon species, the third new one, C. paramnemosyne n. sp., could be identified by its continuous cross-striated band, 16-18 somatic kineties, 5 contractile vacuoles, and 9-12 nematodesmal rods. Based on the sequence of the small subunit (SSU) rRNA gene, the phylogeny of these three new species was analyzed, indicating that they all clustered with other congeners to form a monophyletic assemblage. Based on previous studies and the present work, a brief revision of the genus Chlamydodon is supplied, and a key to aid the identification of Chlamydodon species is given.

Ultrastructure and phylogeny of colpodellids (Colpodellida, Alveolata)

The structure of cells of the predatory flagellates Colpodella pseudoedax and C. unguis was studied. The cell was found to contain two heterodynamic flagellae, three-membrane pellicle, micropores, subpellicular microtubulae, 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 flagellae. 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.

The morphology of predatory flagellate Colpodella pseudoedax Mylnikov et Mylnikov, 2007 (Colpodellida, Alveolata)

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.

Establishment of a New Amphileptid Genus, Apoamphileptus nov. gen. (Ciliophora, Litostomatea, Pleurostomatida), with Description of a New Marine Species, Apoamphileptus robertsi nov. spec, from Qingdao, China

A new pleurostomatid genus Apoamphileptus is described, which is diagnosed as: Belonging to the Amphileptidae with spica on right side; on each side of the cell, a single perioral kinety, which encircles the cytostome and does not extend to the posterior end of the cell; somatic kineties of both sides near ventral margin shortened and forming a postoral suture; two to several extra fragments with densely arranged dikinetids located in anterior portion of left side. As the type species, the morphology and infraciliature of Apoamphileptus robertsi nov. spec., isolated from a shrimp-farming pond near Qingdao (Tsingtao), China, have been investigated using living observations and the protargol silver impregnation method. The diagnosis for this new species is: Apoamphileptus 90-180 x 30-60 microm in vivo, body elongate pyriform-shaped and slightly flattened; with one cross-striated band along the cytostome; 2-6 (generally 4) large macronuclear nodules, one micronucleus; 33-43 right somatic kineties; left side 6-8 kineties; two extra anterior fragments on left side; about 13 contractile vacuoles dispersed throughout whole body; extrusomes absent or not recognizable; marine habitat. Some morphologically related morphotypes are discussed and tabulated. Regarding the pattern of infraciliature and other morphological features, the well-described fresh-water species, Amphileptus claparedii Stein, 1867 is believed to be a member of this new genus, hence a new combination is suggested: Apoamphileptus claparedii (Stein, 1867) nov. comb.

Re-establishment of the cyrtophorid genus Coeloperix Deroux, nov. gen., with a description of Coeloperix sleighi nov. spec. (Protozoa, Ciliophora, Cyrtophorida)

The cyrtophorid genus Coeloperix, which has remained invalid for over 20 years, is re-established. This taxon is characterized by Lynchellids without podites on the ventral side; somatic kineties making no noticeable naked gap between left and right areas; pre- and post-oral kineties completely separated; two terminal fragments; perioral kineties consisting of one continuous anterior and two detached posterior rows; with cross-striated band around perimeter between ventral and dorsal surfaces. Based on this definition, two nominal species formerly placed in the invalid genus have been included again in Coeloperix: Coeloperix dirempta (Deroux, 1970) nov. comb. [synonym: Lynchella dirempta; Deroux, 1970], C. aspidisciformis (Kahl, 1933) nov. comb. [syn. Lynchella aspidisciformis; Kahl, 1933]. Another two morphotypes C. eforiana (Tucolesco, 1962) nov. comb. [syn. Lynchella eforiana; Tucolesco, 1962] and C. lynchelliformis (Borror, 1972) nov. comb. [syn. Chlamydodon lynchelliformis; Borro, 1972] have been transferred into the new genus. The morphology of living cells and infraciliature of a new species, C. sleighi nov. spec., isolated from the coastal area of China, have been investigated. It is diagnosed by: size about 40×30 μm in vivo; consistently 4 preoral and 15–16 postoral kineties; 12–16 nematodesmata; cross-striated band with two separations in the equatorial area; 3–4 (usually 3) finger-like tentacles on the ventral side; macronucleus ellipsoidal; two contractile vacuoles diagonally located; marine habitat.

Dynamics of actin and alpha-actinin in nascent myofibrils and stress fibers.

Actin labeled with fluorescein isothiocyanate (FITC) and alpha-actinin labeled with rhodamine (rh) were co-injected into chick embryonic cardiac myocytes and fibroblasts. In cardiomyocytes, FITC-actin was distributed in nonstriated lines, linearly arranged punctate structures with short intervals, and cross-striated bands with regular sarcomeric intervals. rh-alpha-Actinin was seen to be distributed in the same pattern in the former two portions, and in the center of each striation in the latter portion. Photobleaching of structures incorporated with these fluorescent analogs revealed that the fluorescent recovery rate of actin decreased in the order of nonstriated > punctated > striated portions, while that of alpha-actinin was low and stable at all portions. During the transition phase from punctate to regular sarcomere structures of these proteins, short spaced alpha-actinin dots adjoined each other and aligned with Z bands of neighboring myofibrils. It appears that both the difference in exchangeability between actin and alpha-actinin molecules and the movement of alpha-actinin dots during this phase of myofibrillogenesis are related to sarcomere lengthening and I-Z-I brush formation; adjoining dots of low-exchangeable alpha-actinin may provide favorable situations for exchangeable actin molecules in filaments to elongate and/or rearrange. In fibroblasts, both FITC-actin and rh-alpha-actinin formed nonstriated lines. In these cells, exchangeabilities of both proteins were high and similar in rate. This seems to indicate that stress fibers are constantly exchanging their components for motile and other vital functions of these cells. The high exchangeabilities of both proteins in stress fibers showthat these fibers are clearly different from nonstriated, stress-fiber like structures of nascent myofibrils.

Ribosome distribution in normal and infarcted rat hearts

Distribution of ribosomes throughout the myocardium of normal and infarcted rat hearts was studied by immunofluorescence and laser confocal scanning microscopy. In addition, sections were labelled with peroxidase or immunogold particles for electron microscopic examination. Ligation of the proximal free left coronary artery produced severe myocardial ischaemia, and after 6 days of ligation most of the left ventricular wall was necrotic and partially replaced by granulation tissue. Immunofluorescence microscopy revealed the presence of ribosomes throughout the non-necrotic myocardium. Some cardiac muscle cells located in subendocardial areas and in the border areas surrounding the infarct were particularly intensely stained. Cells constituting the granulation tissue frequently exhibited strong ribosomal immunostaining. Within longitudinally sectioned cardiac muscle cells, ribosomes were organized in strands oriented along the long axis of the cell as well as in a cross-striated pattern. By double labelling of muscle cells with antibodies against ribosomes and Z-line-associated proteins (desmin or alpha-actinin), it was shown that the cross-striated bands of anti-ribosomal staining coincided with the I-bands along the myofibrils. Immunoelectron microscopy confirmed a wide distribution of ribosomes throughout the intermyofibrillar and subsarcolemmal sarcoplasm, and some labelling was also observed within the I-band. The present results indicate that ribosomes are distributed in a characteristic pattern throughout the sarcoplasm of cardiac muscle cells in association with the myofibrils. Furthermore, it is suggested that within viable cardiac muscle cells located adjacent to the infarct, protein synthesis is increased; this might be an important factor in regional development of compensatory hypertrophy of the surviving cardiac muscle cells.

Response of the Cortical Cytoskeleton of Paramecium caudatum to Merotomy

Summary Changes occurring within 2 min of merotomy in the cortical cytoskeleton of fragments cut from Paramecium caudatum were studied in thin sections. None of the microtubular components of the cortical cytoskeleton showed alterations suggestive of functional reorganization of microtubules and attributable to the mechanical damage made to the cell. Marked changes, however, were found in the amount and distribution of the infraciliary lattice. The bands of microfilaments were thicker and the meshes between them were reduced. This thickened layer penetrated deep into the wound under a newly-formed plasma membrane. The granulofibrillar meshwork, which fills the polygonal ridges in an intact cortex, was completely disorganized in fragments. Its remnants were always found in association with the plasma membrane or alveolar membranes. Cross-striated bands of microfilaments were retained only at the margin of the wound where they were attached to alveolar debris. Kinetodesmal fibrils maintained their integrity but their regular pattern of longitudinal bands was disturbed. The epiplasm (membrane skeleton) in the remnants of alveolar membranes was preserved and found also in some regions of the newly-formed plasma membrane. Little information is available on the chemical composition of these microfilamentous components and their function could only be the object of speculations. For instance the character of changes in the infraciliary lattice might suggest that its thickening was due to polymerization of new microfilaments which, together with wound contraction, were involved in the process of healing.