Tetrad Arrangement Research Articles

Ulcerative Gastritis in Sarcina Ventriculi: A Case Report

Background: Sarcina Ventriculi is a Gram-positive organism, which has not been found in gastric samples from patients with gastroparesis. We report the observation of a patient with ulcerative gastritis in Sarcina Ventriculi collected in the pathological anatomy department at the Mohammed VI University Hospital in Marrakech. Case Presentation: This is a 64-year-old woman, with a history of accidental ingestion of Hydrochloric acid, who presented with chronic epigastralgia. An upper endoscopy revealed diffuse gastric erythema. The biopsies revealed a reported inflammation with the formation of an ulcerated ulcer and the presence of Sarcina organisms. Conclusions: Sarcina Ventriculi is an increasingly common Gram-positive coccus recognized in gastric biopsies, especially in patients with delayed gastric abnormalities. It occurs most often in adult females and can be easily identified by its morphological features such as basophilic staining, cuboid shape, tetrad arrangement, red blood cell-sized bundles, flattened cell walls, and nature. refractile under an optical microscope. Although the pathogenesis of the organism is debated, it has been implicated in cases of gastric perforation, emphysematous gastritis and peritonitis, as well as in the development of gastric adenocarcinoma.

ATP-triggered, selective superoxide radical generating oxidase-mimetic cerium oxide nanozyme exhibiting efficient antibacterial activity at physiological pH

Bacterial infections are considered as one of the major health threats to the global population. The advent of bacterial species with antibiotic resistance has attracted significant efforts to develop novel materials and strategies to effectively avoid the resistance with enhanced antibacterial potential. In this work, we have developed oxidase-mimetic cerium oxide nanoparticles (CeO2 NPs), which exhibit nanozyme activity at physiological pH in the presence of adenosine triphosphate (ATP). The oxidase-mimetic activity was confirmed to involve superoxide radicals using p-benzoquinone and dihydroethidium. Using indole propionic acid, ethanol, and terephthalic acid, it was confirmed that the oxidase-mimetic activity of CeO2 NPs with ATP does not involve the formation of hydroxyl radicals. CeO2 NPs with ATP produced a strong antibacterial activity against Staphylococcus aureus and Escherichia coli within 3 – 6 hrs. The bacterial cell morphology analysis suggested that superoxide radicals generated during the oxidase-mimetic activity of CeO2 NPs with ATP cause distortion of paired and tetrad arrangement (Staphylococcus aureus), loss of cytoplasmic content, damage, and pore formation in the cell wall (Escherichia coli) that led to the death of bacteria. Further, the live/dead assay also concludes the time-dependent death of bacterial cells with the highest death in the cell population exposed to CeO2 NPs and ATP. Thus, the antibacterial activity at physiological pH by superoxide radical generating oxidase-mimetic CeO2 NPs could be further extended to other pathogenic bacterial species.

Three-Dimensional Ultrastructure of the Normal Rod Photoreceptor Synapse and Degenerative Changes Induced by Retinal Detachment.

The rod photoreceptor synapse is the first synapse of dim-light vision and one of the most complex in the mammalian CNS. The components of its unique structure, a presynaptic ribbon and a single synaptic invagination enclosing several postsynaptic processes, have been identified, but disagreements about their organization remain. Here, we have used EM tomography to generate high-resolution images of 3-D volumes of the rod synapse from the female domestic cat. We have resolved the synaptic ribbon as a single structure, with a single arciform density, indicating the presence of one long site of transmitter release. The organization of the postsynaptic processes, which has been difficult to resolve with past methods, appears as a tetrad arrangement of two horizontal cell and two rod bipolar cell processes. Retinal detachment severely disrupts this organization. After 7 d, EM tomography reveals withdrawal of rod bipolar dendrites from most spherules; fragmentation of synaptic ribbons, which lose their tight association with the presynaptic membrane; and loss of the highly branched telodendria of the horizontal cell axon terminals. After detachment, the hilus, the opening through which postsynaptic processes enter the invagination, enlarges, exposing the normally sequestered environment within the invagination to the extracellular space of the outer plexiform layer. Our use of EM tomography provides the most accurate description to date of the complex rod synapse and details changes it undergoes during outer segment degeneration. These changes would be expected to disrupt the flow of information in the rod pathway.SIGNIFICANCE STATEMENT Ribbon-type synapses transmit the first electrical signals of vision and hearing. Despite their crucial role in sensory physiology, the three-dimensional ultrastructure of these synapses, especially the complex organization of the rod photoreceptor synapse, is not well understood. We used EM tomography to obtain 3-D imaging at nanoscale resolution to help resolve the organization of rod synapses in normal and detached retinas. This approach has enabled us to show that in the normal retina a single ribbon and arciform density oppose a tetrad of postsynaptic processes. In addition, it enabled us to provide a 3-D perspective of the ultrastructural changes that occur in response to retinal detachment.

Palynological diversity of highly medicinal rare, endangered, and threatened plants from Western Himalaya, India

The present study investigated the palynological diversity of highly medicinal Rare, Endangered, and Threatened (RET) plant species dwelling in higher altitudes of Western Himalaya, India. The pollen morphology of 32 plant species covering 29 genera, 23 families, and 18 orders of Angiosperms was analyzed by Light Microscopy (LM) and Scanning Electron Microscopy (SEM). The families of the studied plant species have been arranged and discussed following the evolutionary sequence as per the updated version of Angiosperm Phylogeny Group ІV. The studied pollen characters were found to be helpful in the delimitation of taxa at the species level. In the studied monocots, the species belonging to order Zingiberales, Asparagales, and Liliales followed the general trend of having primitive inaperturate to advance monosulcate pollen except for Alismatales which had inaperturate pollen and placed after the orders mentioned above in the APG ІV classification system. The pollen aperture of the eudicot group in the present study followed the evolutionary pattern from tricolpate to tricolporate and triporate, which corroborated previous reports. All the investigated species of both monocot and eudicot groups had monad pollen units suggesting their primitiveness on the evolutionary scale except for the Rhododendron companulatum (Ericales), having evolutionarily advanced tetrad arrangement. The current study found primitive exine ornamentation in Ranunculales to advance in Asterales, Lamiales, Gentianales, and Boraginales and confirms the results of the previous studies. The data on the pollen morphological features of the studied species generated in the present study will help understand these important high-altitude plant species' reproductive biology and conservation aspects.

Development and expansion of the pollen wall in Barleria obtusa Nees (Acanthaceae)

Anthers containing pollen grains of Barleria obtusa at various stages of development were examined to investigate pollen wall ontogeny. Whole anthers containing pollen grains were viewed with a light microscope, firstly to identify stages of pollen grain development and secondly to assess the state of the tapetum. Developing pollen grains were sectioned with a Focused Ion Beam-Scanning Electron Microscope (FIB-SEM) in order to determine the suitability of this method for an investigation of exine ontogeny. The pollen wall structure and in particular the development of the external elaborate, reticulate sculpturing were examined. The exine was deposited on the immature pollen grains during the tetrad phase of development with the sculpturing, although somewhat condensed, already apparent at this early stage. The subsequent stages of development show the sculpturing advancing towards its final expanded structure as the grain increases in size. The tapetum was unusual in that it not only lined the anther locule but also surrounded each tetrad group without invaginating the tetrad arrangement, thus defining it as a secretory type.

Sarcina ventriculi : Review of the Literature.

Sarcina ventriculi is an increasingly common gram-positive coccus, recognized in gastric biopsies, particularly of patients with delayed gastric emptying. It occurs most commonly in adult women and can be identified easily by its characteristic morphologic features, such as basophilic staining, cuboid shape, tetrad arrangement, red blood cell-sized packets, flattened cell walls, and refractile nature on light microscopy. Although the pathogenesis of the organism is debated, it has been implicated in cases of gastric perforation, emphysematous gastritis, and peritonitis as well as occurring in the background of gastric adenocarcinomas. This review of the literature discusses the clinical features, endoscopy findings, histopathology, ancillary studies, microbiology, pathogenesis, differential diagnosis, treatment, and prognosis of this bacterium based on 19 published cases.

The Cytoplasmic Domain of the RyR1 Foot is Sufficient for DHPR (Cav1.1) Organization into Tetrads

A RyR1 construct that lacks the channel forming C-terminal residues but includes the entire cytoplasmic foot region (YFP-RyR11:4300) forms a stable tetrameric structure (H. Bichraoui et al., abstract this meeting), colocalizes with DHPRs at SR/plasmalemma junctions and retrogradely enhances peak DHPR currents when expressed in dyspedic (RyR1 null) myotubes (A. Polster et al., abstract this meeting). We tested the interaction of the expressed RyR11:4300 with DHPRs in dyspedic myotubes by examining the DHPR disposition using freeze-fracture. Normally DHPRs are targeted to junctional sites in the absence of RyR, but their organization into tetrads and the arrangement of tetrads in ordered arrays is strictly dependent on their link to arrays of tetrameric RyRs. Thus the disposition of DHPRs in freeze-fracture images provides direct information both on DHPR/RyR interaction and on the arrangement of RyRs. In dyspedic cells DHPR clusters at peripheral couplings in a loose, completely random arrangement. Cells expressing full-length RyR1 show more tightly clustered DHPRs and the presence of complete (4 elements) and incomplete (2-3 elements) tetrads that are aligned in an orthogonal array. Cells expressing the truncated RyR11:4300 show small well identifiable DHPR foci with closely spaced particles. Some but not all foci show clear grouping of DHPRs into complete tetrads and/or tetrads composed of only three elements, but the tetrads are not aligned into a orthogonal array. We conclude that similar to intact RyR1, RyR11:4300 forms homo-tetramers which can link to DHPRs and organize them into tetrads, but that the cytoplasmic RyR1 foot differs from full-length RyR1 in that it does not form orthogonal arrays. The related positioning of RyR11:4300 and DHPRs is necessary for the retrograde interaction between the two.

Carboxyl-Terminal Domain of DHPR β1A is Essential for DHPR Tetrad Formation

Lack of expression of DHPR-β1a subunit in skeletal muscle cells severely compromises the DHPRs-RyR1 stereospecific association that results in the assembly of ordered DHPR tetrads arrays. This, in turn results in the disruption of the EC-coupling DHPR-RyR signal. Previously, using expression of β1a subunits with progressive truncations of the carboxyl-terminal (C-term) domain in β1-null myotubes we found that aa residues 488-512 of β1a were critical to the restoration of the EC-coupling signal. Here we explore the effect of C-term truncations on DHPR tetrad formation and whether the ability of different truncated β1a to restore EC-coupling correlate with their ability to restore DHPR tetrad array. cDNA constructs carrying wt-β1a and C-term truncated clones were transiently expressed in mouse β1-null myotubes and tested for their ability to restore depolarization-induce Ca2+ release. Cells were then fixed and freeze-fractured to assess DHPR tetrad arrangement. Our data show that expression of wt-β1a fully restores EC-coupling, as well as normal DHPR tetrads arrays. Construct β14, lacking 14 aa of the C-terminal tail of β1a, still supports normal EC-coupling and also shows normal arrangement of tetrads. On the other hand, β14 clone containing several Leu/Ala mutations (β14L/A) that prevent EC-coupling failed to restore tetrad arrays. Immunofluorescence staining confirmed that all clones were expressed and targeted to the plasmalemma. These results suggest that 1) C-term tail of β1a plays an essential role in permitting and/or maintaining the precise positioning of four DHPRs relative to the four RyR subunits; 2) DHPR positioning in tetrads is essential to EC-coupling and 3) the molecular structure (aa sequence) of the C-term tail is relevant for the role of β1a in the DHPR-RyR structural and functional relationship.Supported by NIH Grants: 5K01AR054818-02 (to CFP) and AR055104 to KG. Beam (CFA subcontract).

Skeletal muscle excitation–contraction coupling is independent of a conserved heptad repeat motif in the C-terminus of the DHPRβ1a subunit

In skeletal muscle excitation–contraction (EC) coupling the sarcolemmal L-type Ca2+ channel or 1,4-dihydropyridine receptor (DHPR) transduces the membrane depolarization signal to the sarcoplasmic Ca2+ release channel RyR1 via protein–protein interaction. While it is evident that the pore-forming and voltage-sensing DHPRα1S subunit is essential for this process, the intracellular DHPRβ1a subunit was also shown to be indispensable. We previously found that the β1a subunit is essential to target the DHPR into groups of four (tetrads) opposite the RyR1 homotetramers, a prerequisite for skeletal muscle EC coupling. Earlier, a unique hydrophobic heptad repeat motif (L⋯V⋯V) in the C-terminus of β1a was postulated by others to be essential for skeletal muscle EC coupling, as substitution of these residues with alanines resulted in 80% reduction of RyR1 Ca2+ release. Therefore, we wanted to address the question if the proposed β1a heptad repeat motif could be an active element of the DHPR–RyR1 signal transduction mechanism or already contributes at the ultrastructural level i.e. DHPR tetrad arrangement. Surprisingly, our experiments revealed full tetrad formation and an almost complete restoration of EC coupling in β1-null zebrafish relaxed larvae and isolated myotubes upon expression of a β1a-specific heptad repeat mutant (LVV to AAA) and thus contradict the earlier results.

Teratisms in living and fossil megaspores of the Lycopsida: tetrad arrangement and exine ontogeny

Abnormal megaspore tetrad configurations fromSelaginella laevigataand ofLagenicula crassiaculeata(Lower Carboniferous) have been studied by SEM. These abnormalities reflect the variation expected in the presumed evolution of the seed-plants from free-sporing heterosporous ancestors. In addition, they indicate a possible role for the aborted members of a tetrad in the successful development and maturation of the functional spore(s). Aborted members of tetrads also reveal the later stages of the developmental sequence occurring in spore wall construction and highlight the interplay of sporopollenin production, its colloidal flocculation and polymerization, and distortion caused by protoplast expansion. Possible causes of abortion in both living and extinct lycopsid megaspores are discussed.

Teratisms in living and fossil megaspores of the Lycopsida: tetrad arrangement and exine ontogeny

Abnormal megaspore tetrad configurations fromSelaginella laevigataand ofLagenicula crassiaculeata(Lower Carboniferous) have been studied by SEM. These abnormalities reflect the variation expected in the presumed evolution of the seed-plants from free-sporing heterosporous ancestors. In addition, they indicate a possible role for the aborted members of a tetrad in the successful development and maturation of the functional spore(s). Aborted members of tetrads also reveal the later stages of the developmental sequence occurring in spore wall construction and highlight the interplay of sporopollenin production, its colloidal flocculation and polymerization, and distortion caused by protoplast expansion. Possible causes of abortion in both living and extinct lycopsid megaspores are discussed.

Coordinated incorporation of skeletal muscle dihydropyridine receptors and ryanodine receptors in peripheral couplings of BC3H1 cells.

Rapid release of calcium from the sarcoplasmic reticulum (SR) of skeletal muscle fibers during excitation-contraction (e-c) coupling is initiated by the interaction of surface membrane calcium channels (dihydropyridine receptors; DHPRs) with the calcium release channels of the SR (ryanodine receptors; RyRs, or feet). We studied the early differentiation of calcium release units, which mediate this interaction, in BC3H1 cells. Immunofluorescence labelings of differentiating myocytes with antibodies against alpha1 and alpha2 subunits of DHPRs, RyRs, and triadin show that the skeletal isoforms of all four proteins are abundantly expressed upon differentiation, they appear concomitantly, and they are colocalized. The transverse tubular system is poorly organized, and thus clusters of e-c coupling proteins are predominantly located at the cell periphery. Freeze fracture analysis of the surface membrane reveals tetrads of large intramembrane particles, arranged in orderly arrays. These appear concomitantly with arrays of feet (RyRs) and with the appearance of DHPR/RyS clusters, confirming that the four components of the tetrads correspond to skeletal muscle DHPRs. The arrangement of tetrads and feet in developing junctions indicates that incorporation of DHPRs in junctional domains of the surface membrane proceeds gradually and is highly coordinated with the formation of RyR arrays. Within the arrays, tetrads are positioned at a spacing of twice the distance between the feet. The incorporation of individual DHPRs into tetrads occurs exclusively at positions corresponding to alternate feet, suggesting that the assembly of RyR arrays not only guides the assembly of tetrads but also determines their characteristic spacing in the junction.

A new species of Neisseria from the dental plaque of the domestic cow, Neisseria dentiae sp. nov.

A new species of the genus Neisseria is proposed, Neisseria dentiae sp. nov. The organism is found in dental plaque of domestic cows. It resembles N. animalis, N. canis and N. iguanae phenotypically but is distinguished from the first two by being positive for acidification of gluconate, D-glucose and usually D-fructose, and from the third by lack of predominant tetrad arrangement, lack of distinct alpha-haemolysis and by growing on nutrient agar and usually acidifying D-fructose. It is suggested that it may have significance for dental microbiology because members of the genus rapidly utilize oxygen and this may contribute to the anaerobic microenvironment found in dental plaque.

Tetrad pollen in the subfamily Caesalpinioideae (Leguminosae) and its significance

Pollen in permanent tetrads occurs in only eight species from three genera placed in widely separated tribes in the Caesalpiniodease. Tetrads are recorded in all four species of Diptychandra (including one yet to be described) in the tribe Caesalpinieae. They occur in only two species of about 300 in Bauhinia ( B. phoenicea and B. pottsii and its varieties) in the tribe Cercideae. Of 13 species of Afzelia in the tribe Detarieae tetrad pollen has been found only in A. pachyloba and A. bella and its varieties. There are few common features in the tetrad pollen found in the subfamily. Diptychandra has acalymate tetrads with distinctive interconnecting channels between individual grains. Bauhinia phoenicea has calymate pollen while B. pottsii has acalymate pollen with cross wall cohesion and exine bridges. There is a wide range of variation in the shape of the pollen, colpal length and ornamentation among the four varieties of B. pottsii. The tetrads are acalymate in Afzelia, held together by a shared tectum. The pollen has a thin endexine, very thin lamellated foot layer, short columellae and very thick, coarsely reticulate tectum, very distinct from the perforate tectum found in the other genera. The limited occurrence of tetrad pollen within the subfamily and the significance of its great variation in Bauhinia, and to a lesser extent in the other genera, is discussed. The range of structure and plasticity of arrangement of tetrads and their wide taxonomic distribution, suggest that these pollen structures arose more than once in the Caesalpinioideae and this might be expected in the subfamily which is regarded as ancestral in the Leguminosae.

A new species of Neisseria from iguanid lizards, Neisseria iguanae sp. nov.

A new species of the genus Neisseria is proposed, Neisseria iguanae sp. nov. The organism is associated with septic lesions in the common iguana (Iguana iguana) and the rhinoceros iguana (Cyclura cornuta) but is also a commensal. It resembles N. animalis and N. canis phenotypically but is distinguished from these by exhibiting pronounced tetrad arrangement and alpha haemolysis and by fermenting gluconate.

Pollen morphology of <i>Curroria</i>, <i>Mondia</i>, <i>Socotranthus</i> and <i>Stomatostemma</i> (Periplocaceae)

The pollen morphology of I Planch., O Skeels, Socotranthus Kuntze and Stomatostemma N.E. Br. was studied.All the genera are characterized by pollen grains arranged in tetrads. The arrangement of the grains may be rhomboidal, tetrahedral or decussate. The 4 - 6 pores present are restricted to the junction area of adjacent grains. The exine is smooth.Exine structure consists of an outer, homogeneous stratum (tectum) subtended by a granular stratum. The intine is well developed. The pollen grains of tetrads are connected by wall bridges (cross-wall cohesion). Except for small differences which may occur between species and genera in pollen size and arrangement of tetrads, the pollen is uniform in morphology.

On the experimental silicification of microorganisms. III. Implications of the preservation of the green prokaryotic alga prochloron and other coccoids for interpretation of the microbial fossil record

Abstract Evidence for Precambrian fossil eukaryotic microorganisms has been based on: (1) the presence of internal ‘spots’ which have been variously interpreted to be remains of nuclei or pyrenoids of photosynthetic plastids or other organelles; (2) tetrahedral tetrad arrangement of cells; (3) trilete scars interpreted to be indicative of meiotic division: (4) large cell diameters; and (5) putative mitotic cell divisions. These features have been reported in fossils preserved in Precambrian cherts. We have studied modern microbial mats, thought to be analogues of Precambrian fossil communities, and found they may be silicified by laboratory procedures. In microbial mats from Baja California we have found many ‘spot cells’ that we could identify as remains of cyanophytes. We have silicified the newly discovered large prokaryotic coccoid green alga Prochloron and have found that it, like many cyanophytes previously silicified, preserves its structure and maintains its initial dimensions. In laboratory-silicified prokaryotic organisms we have found that all of the above criteria, supposedly characteristic of eukaryotes, can be observed. We conclude that there is no compelling morphological evidence for fossil eukaryotic microbes from Precambrian cherts.

Pteridophytic features in some Lower Carboniferous seed megaspores

Some Lower Carboniferous seed megaspores have triradiate suturesunequivocal evidence of their being arranged in a tetrahedral configuration. This type of tetrad arrangement is unknown in the ovules of

The Structure and Development of the Sporophylls and Sporangia of Isoetes (Concluded)

Previous articleNext article FreeThe Structure and Development of the Sporophylls and Sporangia of Isoetes (Concluded)R. Wilson SmithR. Wilson Smith Search for more articles by this author PDFPDF PLUS Add to favoritesDownload CitationTrack CitationsPermissionsReprints Share onFacebookTwitterLinkedInRedditEmail SectionsMoreDetailsFiguresReferencesCited by Volume 29, Number 5May, 1900 Article DOIhttps://doi.org/10.1086/327991 Views: 664Total views on this site Citations: 5Citations are reported from Crossref Journal History This article was published in the Botanical Gazette (1876-1991), which is continued by International Journal of Plant Sciences (1992-present). PDF download Crossref reports the following articles citing this article:Barbara A. Ambrose The Morphology and Development of Lycophytes, (Apr 2018): 91–114.https://doi.org/10.1002/9781119312994.apr0488Barbara A. Ambrose The Morphology and Development of Lycophytes, (Nov 2012): 91–114.https://doi.org/10.1002/9781118305881.ch3Shane William Shaw, R. James Hickey Comparative Morphology of the Glossopodia of Three North American Isoetes Ligules, American Fern Journal 95, no.33 (Jul 2005): 94–114.https://doi.org/10.1640/0002-8444(2005)095[0094:CMOTGO]2.0.CO;2ALAN R. HEMSLEY Teratisms in living and fossil megaspores of the Lycopsida: tetrad arrangement and exine ontogeny, Botanical Journal of the Linnean Society 125, no.11 (Jun 2008): 1–24.https://doi.org/10.1111/j.1095-8339.1997.tb02243.xRobert Babcock SAMUEL GOMPERS AND THE FRENCH-CANADIAN WORKER, 1900–1914, American Review of Canadian Studies 3, no.22 (Nov 2009): 47–66.https://doi.org/10.1080/02722017309481289