Chapter 21 Electron Microscopy of Lamin and the Nuclear Lamina in Caenorhabditis elegans

Cohen, Merav; Santarella, Rachel; Wiesel, Naama; Mattaj, Iain W.; Gruenbaum, Yosef

doi:10.1016/s0091-679x(08)00421-4

Cited by 11 publications

(8 citation statements)

References 26 publications

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“…Cells were then high-pressure frozen in a Leica EMPACT2 (Leica, Vienna) or HPM010 (Abra Fluids, Switzerland) high-pressure freezing machine. For morphological and immuno-labeling studies, cells were freeze-substituted and embedded as described in [48]. Thin sections (60 nm) were labeled with an anti-gp4978 antibody (1∶100) as described in [49].…”

Section: Methodsmentioning

confidence: 99%

The Compartmentalized Bacteria of the Planctomycetes-Verrucomicrobia-Chlamydiae Superphylum Have Membrane Coat-Like Proteins

et al. 2010

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Section: Methodsmentioning

confidence: 99%

The Compartmentalized Bacteria of the Planctomycetes-Verrucomicrobia-Chlamydiae Superphylum Have Membrane Coat-Like Proteins

et al. 2010

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“…Cell pellets were suspended in 2 l 20% (wt/vol) bovine serum albumin (BSA) in phosphatebuffered saline (PBS; for Epon embedding) or in 2 l dextran (high molecular weight) in PBS (for Lowicryl HM20 embedding). After high-pressure freezing in an HPM 010 instrument (Abra Fluid AG, Widnau, Switzerland), freeze substitution was performed with a Leica EM AFS2 system (Leica Microsystems, Vienna, Austria) and cells were embedded into either Epon or Lowicryl HM20 (51). The Epon samples were stained with 1% (wt/vol) OsO 4 in acetone and 2% (wt/vol) uranyl acetate in water.…”

Section: Methodsmentioning

confidence: 99%

Biopearling of Interconnected Outer Membrane Vesicle Chains by a Marine Flavobacterium

Fischer

Schorb²,

Reintjes

et al. 2019

Appl Environ Microbiol

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Large surface-to-volume ratios provide optimal nutrient uptake conditions for small microorganisms in oligotrophic habitats. The surface area can be increased with appendages. Here, we describe chains of interconnecting vesicles protruding from cells of strain Hel3_A1_48, affiliating with Formosa spp. within the Flavobacteriia and originating from coastal free-living bacterioplankton. The chains were up to 10 μm long and had vesicles emanating from the outer membrane with a single membrane and a size of 80 to 100 nm by 50 to 80 nm. Cells extruded membrane tubes in the exponential phase, whereas vesicle chains dominated on cells in the stationary growth phase. This formation is known as pearling, a physical morphogenic process in which membrane tubes protrude from liposomes and transform into chains of interconnected vesicles. Proteomes of whole-cell membranes and of detached vesicles were dominated by outer membrane proteins, including the type IX secretion system and surface-attached peptidases, glycoside hydrolases, and endonucleases. Fluorescein-labeled laminarin stained the cells and the vesicle chains. Thus, the appendages provide binding domains and degradative enzymes on their surfaces and probably storage volume in the vesicle lumen. Both may contribute to the high abundance of these Formosa-affiliated bacteria during laminarin utilization shortly after spring algal blooms. IMPORTANCE Microorganisms produce membrane vesicles. One synthesis pathway seems to be pearling that describes the physical formation of vesicle chains from phospholipid vesicles via extended tubes. Bacteria with vesicle chains had been observed as well as bacteria with tubes, but pearling was so far not observed. Here, we report the observation of, initially, tubes and then vesicle chains during the growth of a flavobacterium, suggesting biopearling of vesicle chains. The flavobacterium is abundant during spring bacterioplankton blooms developing after algal blooms and has a special set of enzymes for laminarin, the major storage polysaccharide of microalgae. We demonstrated with fluorescently labeled laminarin that the vesicle chains bind laminarin or contain laminarin-derived compounds. Proteomic analyses revealed surface-attached degradative enzymes on the outer membrane vesicles. We conclude that the large surface area and the lumen of vesicle chains may contribute to the ecological success of this marine bacterium.

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“…At the appropriate cell cycle stage, the capillary tubes were placed in 100 μm membrane carriers filled with 20% BSA in M9 buffer and frozen with the EMPACT2 high pressure freezing machine (Leica Microsystems, Vienna). Embryos were then freeze substituted in 0.1% uranyl acetate in acetone and embedded in Lowicryl, HM20 according to (Cohen et al, 2008). Serial sections were cut at 60 nm and placed on formvar coated grids.…”

Section: Methodsmentioning

confidence: 99%

Sm protein down-regulation leads to defects in nuclear pore complex disassembly and distribution in C. elegans embryos

Joseph-Strauss

Gorjánácz

Santarella-Mellwig

et al. 2012

Developmental Biology

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Summary Nuclear pore complexes (NPCs) are large macromolecular structures embedded in the nuclear envelope (NE), where they facilitate exchange of molecules between the cytoplasm and the nucleoplasm. In most cell types, NPCs are evenly distributed around the NE. However, the mechanisms dictating NPC distribution are largely unknown. Here, we used the model organism C. elegans to identify genes that affect NPC distribution during early embryonic divisions. We found that down-regulation of the Sm proteins, which are core components of the spliceosome, but not down-regulation of other splicing factors, led to clustering of NPCs. Down-regulation of Sm proteins also led to incomplete disassembly of NPCs during mitosis, but had no effect on lamina disassembly, suggesting that the defect in NPC disassembly was not due to a general defect in nuclear envelope breakdown. We further found that these mitotic NPC remnants persisted on an ER membrane that juxtaposes the mitotic spindle. At the end of mitosis, the remnant NPCs moved toward the chromatin and the reforming NE, where they ultimately clustered by forming membrane stacks perforated by NPCs. Our results suggest a novel, splicing-independent, role for Sm proteins in NPC disassembly, and point to a possible link between NPC disassembly in mitosis and NPC distribution in the subsequent interphase.

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Chapter 21 Electron Microscopy of Lamin and the Nuclear Lamina in Caenorhabditis elegans

Cited by 11 publications

References 26 publications

The Compartmentalized Bacteria of the Planctomycetes-Verrucomicrobia-Chlamydiae Superphylum Have Membrane Coat-Like Proteins

The Compartmentalized Bacteria of the Planctomycetes-Verrucomicrobia-Chlamydiae Superphylum Have Membrane Coat-Like Proteins

Biopearling of Interconnected Outer Membrane Vesicle Chains by a Marine Flavobacterium

Sm protein down-regulation leads to defects in nuclear pore complex disassembly and distribution in C. elegans embryos

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