scholarly journals Deposit feeding of a foraminifera from an Arctic methane seep site and possible association with a methanotroph revealed by transmission electron microscopy

2021 ◽  
Author(s):  
Christiane Schmidt ◽  
Emmanuelle Geslin ◽  
Joan M. Bernhard ◽  
Charlotte LeKieffre ◽  
Mette Marianne Svenning ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Methane Emission ◽  
Barents Sea ◽  
Substantial Contribution ◽  
Type I ◽  
Feeding Experiment ◽  
Organic Detritus ◽  
Transmission Electron ◽  
Deposit Feeding

Abstract. Several foraminifera are deposit feeders that consume organic detritus (dead particulate organic material along with entrained bacteria). However, the role of such foraminifera in the benthic food-web remains understudied. As foraminifera may associate with methanotrophic bacteria, which are 13C-depleted, feeding on them has been suggested to cause negative δ13C values in the foraminiferal cytoplasm and/or calcite. To test whether the foraminiferal diet includes methanotrophs, we performed a short-term (1 d) feeding experiment with Nonionellina labradorica from an active Arctic methane-emission site (Storfjordrenna, Barents Sea) using the marine methanotroph Methyloprofundus sedimenti, and analyzed N. labradorica cytology via Transmission Electron microscopy (TEM). We hypothesized that M. sedimenti would be visible, as evidenced by their ultrastructure, in degradation vacuoles after this feeding experiment. Sediment grains (mostly clay) occurred inside one or several degradation vacuoles in all foraminifers. In 24 % of the specimens from the feeding experiment degradation vacuoles also contained bacteria, although none could be confirmed to be the offered M. sedimenti. Observations of the area adjacent to the aperture after 20 h incubation revealed three putative methanotrophs, close to clay particles. These methanotrophs were identified based on internal characteristics such as a type I stacked intracytoplasmic membranes (ICM), storage granules (SG) and gram-negative cell walls (GNCW). Furthermore, N. labradorica specimens were examined for specific adaptations to this active Arctic methane-emission site; we noted the absence of bacterial endobionts in all specimens examined but confirmed the presence of kleptoplasts, which were often partially degraded. Based on these observations, we suggest that M. sedimenti can be consumed by N. labradorica via untargeted grazing in seeps and that N. labradorica can be generally classified as a deposit feeder at this Arctic site. These results suggest that if methanothrophs are available to the foraminifera in their habitat, their non-selective uptake could make a substantial contribution to altering δ13Ctest values. This in turn may impact metazoans grazing on benthic foraminifera by altering their δ13C signature.

Modeling Congenital Dyserythropoietic Anemia Type I Through Patient-Derived Induced Pluripotent Stem Cells

Blood ◽  
2012 ◽  
Vol 120 (21) ◽  
pp. 3196-3196
Author(s):  
Orna Steinberg Shemer ◽  
Yu Yao ◽  
Gary M. Kupfer ◽  
Hannah Tamary ◽  
Mitchell J. Weiss
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Light Microscopy ◽  
Chromatin Structure ◽  
Pluripotent Stem Cells ◽  
Type I ◽  
Transmission Electron ◽  
Erythroid Precursors ◽  
Induced Pluripotent ◽  
I Cells

Abstract Abstract 3196 Congenital dyserythropoietic anemias (CDAs) are rare inherited disorders characterized by impaired red blood cell formation (dyserythropoiesis) and signature cytopathologies. CDA type I is an autosomal recessive disease with macrocytic anemia and occasional bone abnormalities. Erythroid precursors exhibit pathognomonic abnormalities including internuclear chromatin bridges and spongy (“Swiss cheese”) heterochromatin. The disease is caused by biallelic mutations in the gene CDANI (Dgany et al., 2002), which encodes codanin-1, a ubiquitously expressed protein that is believed to have fundamental roles in cell cycle control and chromatin structure (Noy-Lotan et. al, 2009). Animal models for the study of CDA I are suboptimal and clinical samples are scarce. Thus, we have developed an experimental model for the study of CDA I by generating induced pluripotent stem cells (iPSCs) from affected patients. We reprogrammed fibroblasts from CDA I patients and normal subjects using a single lentiviral vector encoding OCT4, KLF4, SOX2, and MYC. The resultant iPSCs exhibited standard criteria for pluripotency and the integrated reprogramming vector was excised using Cre-lox technology. We differentiated CDA I and control iPSCs into erythroid progenitors by inducing the formation of embryoid bodies (EBs) with stepwise additions of supportive cytokines. Beginning at about day 8, hematopoietic progenitors with erythroid potential were detected within EBs and as free-floating cells in the medium. Our differentiation protocol showed two waves of erythroid precursor production. Early EBs (days 12 to 23) produced erythroid cells that expressed mainly epsilon globin, resembling early yolk sac type “primitive” erythropoiesis. In contrast, erythroblasts produced from later EBs (days 27 to 50) expressed mainly gamma globins, resembling “definitive” erythroid cells produced by late stage yolk sac and fetal liver. Our preliminary studies, indicate that CDA I iPSCs produce normal numbers of primitive and definitive erythrocytes. No defects in survival or maturation were detected by flow cytometry assessing the expression of annexin V and the developmental stage markers CD235/CD71/forward scatter. However, definitive type (but not primitive) erythroblasts derived from CDA I iPSCs exhibit some characteristic pathological features including occasional internuclear chromatin bridging visible by light microscopy and spongy “Swiss cheese” heterochromatin revealed by transmission electron microscopy. Thus, patient-derived iPSCs can model at least some aspects of CDA I and provide the basis for future studies to define the actions of codanin-1 and the pathophysiology of this disorder. Figure: Patient iPSC-derived erythroblasts recapitulate CDA I pathology. Light microscopy and transmission electron microscopy (TEM) of normal and CDA I iPSC-derived erythroblasts generated in ∼30 day differentiation cultures. Inserts show higher magnification of the marked areas. CDA I cells exhibit occasional internuclear bridges on light microscopy (third panel). TEM showed abnormal spongy chromatin structure in most CDA I erythroid precursors (fourth panel). Figure:. Patient iPSC-derived erythroblasts recapitulate CDA I pathology. Light microscopy and transmission electron microscopy (TEM) of normal and CDA I iPSC-derived erythroblasts generated in ∼30 day differentiation cultures. Inserts show higher magnification of the marked areas. CDA I cells exhibit occasional internuclear bridges on light microscopy (third panel). TEM showed abnormal spongy chromatin structure in most CDA I erythroid precursors (fourth panel). Disclosures: No relevant conflicts of interest to declare.

Structure and synthesis of the peritrophic membrane in Trichoptera larvae

Zoosymposia ◽  
2011 ◽  
Vol 5 (1) ◽  
pp. 63-70
Author(s):  
CARLA CORALLINI
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Cardiac Valve ◽  
Food Type ◽  
Peritrophic Membrane ◽  
Type I ◽  
Type Ii ◽  
Food Ingestion ◽  
Transmission Electron ◽  
Anterior Midgut

The peritrophic membrane (PM) in Trichoptera larvae was examined by light, scanning and transmission electron microscopy. The gut of most insects produces 2 fundamental types of PM: Type I is synthesized and secreted by the entire midgut epithelium in response to the ingestion of food; type II is synthesized by specialized cells of the cardiac valve located in the anterior midgut independent from food ingestion. Corallini (2003) described, in the midgut of Limnephilidae larvae, a type I PM which is also secreted by unfed larvae. In this study, both types of PM were observed. Type I PM was evident in larvae of Rhyacophilidae, Leptoceridae, Sericostomatidae and Odontoceridae; the type II PM was observed in larvae of Philopotamidae, Polycentropodidae and Hydropsychidae.

Characterization of Cyanobacterial Picoplankton in Lake Ontario by Transmission Electron Microscopy

1987 ◽  
Vol 44 (12) ◽  
pp. 2173-2177 ◽  
Author(s):  
Gary G. Leppard ◽  
Dina Urciuoli ◽  
F. R. Pick
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Cell Envelope ◽  
Lake Ontario ◽  
Nuclear Material ◽  
Major Type ◽  
Type I ◽  
Transmission Electron ◽  
Numerous Cell ◽  
Chroococcoid Cyanobacteria

Many chroococcoid cyanobacteria from Lake Ontario, characterized by epifluorescence in concert with transmission electron microscopy, had a Type I ultrastructure, the major type in oceanic waters. Such cells had a multilayered cell envelope and their polyhedral bodies were interspersed with the central nuclear material. All thylakoids were peripheral and were arranged concentrically, with no intrusion into the nuclear region. Related chroococcoid types were also seen but these were much less abundant. The most numerous cell type in all water samples was a small, Gram-negative, rodlike bacterium. Many of these rods were sufficiently small to pass a filter of 0.45-μm pore size but none had a diameter less than 0.2 μm. Attempts to isolate and describe the cyanobacterial picoplankton presented some unusual difficulties having a potential to mislead limnological analyses. These are described and, to some extent, they are resolved here.

scholarly journals FIB and SEM-STEM Studies of Friction-stir Processed AM60 Magnesium Alloy

2012 ◽  
Vol 18 (S5) ◽  
pp. 97-98
Author(s):  
J. B. Rodríguez ◽  
P. Miniño ◽  
G. Pena ◽  
D. Gesto ◽  
P. Rey ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Magnesium Alloy ◽  
Ion Beam ◽  
Intermetallic Phase ◽  
Base Material ◽  
Type I ◽  
Friction Stir ◽  
Transmission Electron ◽  
Average Grain Size

In the present work, we present the microstructural study of a cast magnesium alloy AM60B processed by Friction Stir Processing (FSP) in order to achieve Ultra-Fine Grain (UFG) size (200–700nm) in the stirred zone. Focused ion beam (FIB) has been used for sample preparation, and transmission electron microscopy (TEM), scanning transmission electron microscopy (STEM) and selected area electron diffraction (SAED) for the structural characterization. To explain the differences induced by the FSP, two lamellas obtained by FIB from the bottom and the upper part of the cross-section of the nugget are compared to one extracted from the parent material (unaffected zone A). The obtained results show the remarkable homogenization and grain refinement produced in the structure in the processed zone, as previous reported works indicate. The microstructure of the as cast base material reveals the presence of dendrites of solid solution of Al in Mg (α-phase), with an average grain size of ~400–500 µm, and a partially divorced eutectic structure at the interdendritic spaces, where the massive and lamellar β-Mg17Al12 intermetallic phase can be observed (Figure 1). The SAED on one particle of β-phase shows a diffraction pattern that fits the crystalline structure of the cubic I -4 3 m space group (Nº 217). Also Mn containing phases were homogeneously distributed throughout the section. The performed analyses demonstrate that these particles are basically Al-Mn binary phases containing trace elements as Si or Fe, and the measured Mn/Al ratio allow to classify them into two types previously reported: Type I are particles of equiaxed or almost rounded shape and type II are needle like or flowerlike particles, with a lower Mn/Al ratio.

High-Temperature Indentation of Natural Diamond and the Quest for Lonsdaleite

1995 ◽  
Vol 383 ◽  
Author(s):  
P. Pirouz ◽  
A. Garg ◽  
X. J. Ning ◽  
J. W. Yang ◽  
S. Q. Xiao
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
High Temperature ◽  
Plastic Zone ◽  
Natural Diamond ◽  
Type I ◽  
Temperature Range ◽  
Hexagonal Diamond ◽  
Transmission Electron

ABSTRACTAttempts were made to produce bands of hexagonal diamond (Lonsdaleite) by high-temperature indentation of cubic diamond. (011) wafers of type I diamond were indented over the temperature range 1000–1300°C and the microstructure of the indentation plastic zone investigated by transmission electron microscopy (TEM). No hexagonal diamond was produced; instead, the plastic zone consisted of arrays of dislocations lying on the {001} planes. A possible mechanism for the generation of such dislocations, and reasons for the absence of hexagonal diamond, are discussed.

Characterization of Ustilago Hordei Fimbriae Using Scanning Transmission Electron Microscopy and Immunocytochemistry

1997 ◽  
Vol 3 (S2) ◽  
pp. 123-124
Author(s):  
Caroll E. Henry ◽  
T.L. Salaam ◽  
E. Steward-Clark ◽  
Joyce Craig ◽  
Lennell Reynolds
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Protein Concentration ◽  
Uranyl Acetate ◽  
Type I ◽  
Transmission Electron ◽  
Ustilago Hordei ◽  
Cacodylate Buffer ◽  
Scanning Transmission

Sporidia of Ustilago hordei produce surface fimbriae which are important in conjugation and pathogenicity. This work focuses on fimbrial origin and production using transmission electron microscopy (TEM) and immunocytochemistry.Wild type I4A sporidial cells cultured to log phase with rotary shaking in yeast extract glucose (YEG) growth for 48 h. at 21° C, were harvested by centrifugation at 8000 rpm, placed on formvar coated grids, negatively stained with 2% uranyl acetate and photographed in the JEOL 1200 STEM. Some cells were prepared for sectioning by fixation with gluteraldehyde and cacodylate buffer, post fixed in osmium tetroxide, dehydrated and embedded in epoxy and stained with uranyl acetate. The remainder of the cells were sheared in a blender to remove fimbriae. The defimbriated cells and 1 ml. of fimbrial suspension were presented to TEM. The rest of the fimbrial suspension was centrifuged at 30,000 rpm and he fimbrial pellet protein concentration was determined to be 1.345 nm. as assayed by UV adsorption.

scholarly journals Pseudocnidae of ribbon worms (Nemertea): ultrastructure, maturation, and functional morphology

PeerJ ◽  
2021 ◽  
Vol 9 ◽  
pp. e10912
Author(s):  
Timur Yu Magarlamov ◽  
James M. Turbeville ◽  
Alexei V. Chernyshev
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Core Layer ◽  
Outer Core ◽  
Type I ◽  
Type Ii ◽  
The Core ◽  
Transmission Electron ◽  
Core Rod ◽  
Eleven Species

The fine structure of mature pseudocnidae of 32 species of nemerteans, representatives of 20 genera, six families, and two classes was investigated with scanning and transmission electron microscopy. Pseudocnidae are composed of four layers (cortex, medulla, precore layer, and core) in most species investigated, but the degree of development and position of each layer can vary between different species. The secretion products comprising immature pseudocnidae segregate into separate layers: a thin envelope, which subsequently separates into the cortex and medulla and an extensive internal layer. We distinguish two pseudocnida types: type I is characterized by a two-layered core and type II by a three-layered core. Type I pseudocnidae are present in archinemertean species, Carinoma mutabilis, and in all pilidiophoran species, except Heteronemertea sp. 5DS; type II pseudocnidae occur in all studied species of Tubulanidae and the basal Heteronemertea sp. 5DS. Based on the structure of the discharged pseudocnidae observed in eleven species of palaeonemerteans and in eight species of pilidiophorans, we distinguish three different mechanisms (1–3) of core extrusion/discharge with the following characteristics and distribution: (1) the outer core layer is everted simultaneously with the tube-like layer and occurs in type I pseudocnidae of most species; (2) the extruded core is formed by both eversion of the outer core layer and medullar layer, and occurs in type I pseudocnidae of Micrura cf. bella; (3) the eversion of the outer core layer begins together with the core rod and core rod lamina and occurs in type II pseudocnidae. Morpho-functional comparison with other extrusomes (cnidae, sagittocysts, rhabdtites, and paracnids) confirm that pseudocnidae are homologous structures that are unique to nemerteans.

scholarly journals Planar defects in ZnO thin films deposited on optical fibers and flat substrates

1999 ◽  
Vol 14 (5) ◽  
pp. 1876-1885 ◽  
Author(s):  
Laurent Sagalowicz ◽  
Glen R. Fox
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Optical Fibers ◽  
Single Type ◽  
Angular Width ◽  
Type I ◽  
Transmission Electron Microscopy Analysis ◽  
Planar Defects ◽  
Peak Broadening ◽  
Transmission Electron

The microstructure and the defects of ZnO coatings deposited at room temperature by sputtering onto fibers and flat substrates were characterized using transmission electron microscopy (TEM), scanning electron microscopy, and x-ray diffraction (XRD). XRD shows that the films have a [0001] preferred orientation and a large angular width of the 0002 reflection. According to TEM observations, the film microstructure consists of columnar grains which contain large concentrations of basal planar defects and dislocations. High-resolution transmission electron microscopy analysis and the associated image simulation are in full agreement with the presence of single (type I) and double (type II) stacking faults. The relation between the observed defects and the 0002 peak broadening is discussed.

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