Immobilization and stretching of 5′-pyrene-terminated DNA on carbon film deposited on electron microscope grid

2015 ◽  
Vol 78 (11) ◽  
pp. 994-1000 ◽  
Author(s):  
Alexandre Loukanov ◽  
Chavdar Filipov ◽  
Marta Lecheva ◽  
Saim Emin
Keyword(s):  
Electron Microscope ◽  
Carbon Film ◽  
Electron Microscope Grid ◽  
Microscope Grid

Characterization of colloidal materials by cryo-TEM

1993 ◽  
Vol 51 ◽  
pp. 728-729
Author(s):  
J. R. Minter
Keyword(s):  
Electron Microscope ◽  
Silver Halide ◽  
Carbon Film ◽  
Liquid Films ◽  
Material Parameters ◽  
Trap Door ◽  
Electron Microscope Grid ◽  
Microscope Grid ◽  
Colloidal Materials

Many researchers develop products and processes that depend upon colloidal materials. Rheological and other important material parameters are influenced by the morphology of the colloid. The photography industry uses many such colloids including silver halide sols, photographic coupler sols and emulsions surfactants, and gelatin solutions and gels. High-resolution direct electron images of these systems in their native states permit photographic scientists to understand how changes in formulation produce changes in microstructure and, ultimately, to understand the photographic performance of the system.We prepare thin biconcave liquid films spanning the holes in a perforated carbon film supported by an electron microscope grid (see Fig 1). To prevent changes in composition of the colloid caused by evaporation, the films are prepared in an environmental chamber and are propelled through a trap door into a container of liquid ethane. The specimen is cooled at a rate sufficient to prevent crystallization of water. When maintained below -150 °C, these specimens are stable and compatible with the high vacuuary of the electron microscope.

Growth and morphology of NaCl-type crystals prepared by various methods

1990 ◽  
Vol 48 (4) ◽  
pp. 848-849
Author(s):  
Yoshio Saito ◽  
Chihiro Kaito ◽  
Shigeo Maeda
Keyword(s):  
Aqueous Solution ◽  
Free Energy ◽  
Electron Microscope ◽  
Growth Mechanism ◽  
Ultrafine Particles ◽  
Carbon Film ◽  
Growth Mechanisms ◽  
Circulating Water ◽  
Electron Microscope Grid ◽  
Microscope Grid

NaCl type crystals generally grow a cube. NaCl-type crystals with rhombic prism shape have been found among the cube crystals. No convincing interpretation for the rhombic prism crystals has been given. The growth mechanisms of some crystals have been clarified by means of potetial energy calculations in previous papers. In the present paper, free energy of NaCl type crystals having various shapes have been calculated in order to make clear the origin of the appearing of the rhombic prism crystals. The growth mechanism is discussed on the basis of the free energy.NaCl crystals were grown from aqueous solution in a glass made growth cell thermostated with circulating water(±l⋅C). The NaCl crystals were grown at temperature of 50°C which is equivalent to the supersaturation of 2%. The grown crystals were mounted on a net and were dried with a filter paper as quickly as possible. The specimens were examined by a microscope. PbS crystals are prepared by the two-heater method which have been developed to produce ultrafine particles of low melting materials. The detail of the preparation has been shown in a previous paper. The grown crystals collected on a carbon film supported by an electron microscope grid were observed with a Hitachi H-9000 electron microscope.

82COMPARISON OF THE SURVIVAL OF IN VITRO-DERIVED PORCINE OOCYTES AND EMBRYOS VITRIFIED BY OPEN PULLED STRAW, ELECTRON MICROSCOPE GRID, AND NYLON LOOP SYSTEM

2004 ◽  
Vol 16 (2) ◽  
pp. 162 ◽  
Author(s):  
M.-H. Ahn ◽  
H.-B Seok ◽  
I.-D. Kim ◽  
D.-S Son
Keyword(s):  
Electron Microscope ◽  
Liquid Nitrogen ◽  
Bovine Serum ◽  
Blastocyst Stage ◽  
Loop System ◽  
Sample Container ◽  
Continue Development ◽  
Electron Microscope Grid ◽  
Microscope Grid

Various sample containers have been developed for ultra-rapid vitrification of oocytes and embryos to minimize chilling and other injuries. In this study, the survival rates of in vitro-derived porcine oocytes were compared after cryopreservation using open pulled straw (OPS), electron microscope grid (EMG), and nylon loop system (NLS). In addition, the post-thaw survival of porcine morulae and blastocysts was assessed after vitrification by the OPS method. In vitro maturation and fertilization were performed according to the procedures of Funahashi et al., 1994 Theriogenology 41, 1425–1433). Fertilized oocytes were cultured in glucose-free NCSU 23 supplemented with 5mM sodium pyruvate, 0.5mM sodium lactate and 4mgmL−1 bovine serum albumin for 2 days at 39°C; 10% fetal bovine serum was added to the culture medium thereafter. Oocytes and embryos were treated with 7.5μgmL−1 cytochalasin B for 30min, centrifuged at 13,000g for 13min and then exposed sequentially to an ethylene glycol (EG) vitrification solution (0M for 1min, 2M for 5min and 8M plus 7% polyvinylpyrrolidone for 1min). Oocytes (n=100per treatment group) were placed in or on sample containers and plunged into liquid nitrogen. Porcine morulae and blastocysts (n=137) were similarly treated, aspirated into OPSs, and plunged into liquid nitrogen. Oocytes and embryos were thawed rapidly by transferring the sample container into 1M EG for 2min, and then the embryos were serially diluted by transfer into 0.5M for 2min, and medium for 5min. Post-thaw survival of vitrified oocytes was assessed by development after IVF and culture to morulae or blastocysts. Post-thaw survival of vitrified morulae and blastocysts was assessed by their ability to continue development to, respectively, blastocysts and expanded blastocysts. After oocytes were thawed, fertilized and cultured in vitro, the rates of development to the morula- or blastocyst-stage were 8%, 0% and 6% for, respectively, the OPS, EMG and NLS groups. The rate of development of non-cryopreserved control oocytes was 38% (38/100). Although significantly fewer oocytes developed after vitrification compared to the control (P<0.05), OPS and NLS containers were superior to EMG containers (P<0.05). Morula- or blastocyst-stage embryos vitrified using OPS yielded a significantly higher rate of survival than did oocytes (48%, 66/137; P<0.05). This study indicates that very few in vitro-matured porcine oocytes survive vitrification using OPS, EMG and NLS methods. Considerably higher rates of survival were obtained by in vitro-produced porcine morulae and blastocysts following vitrification by the OPS method. Additional research is needed to identify and develop methods to overcome the factors limiting the cryopreservation of porcine oocytes for practical uses. Supported by KOSEF (R05-2002-000-00388-0) grant.

scholarly journals The fibrillar substructure of keratin filaments unraveled.

1983 ◽  
Vol 97 (4) ◽  
pp. 1131-1143 ◽  
Author(s):  
U Aebi ◽  
W E Fowler ◽  
P Rew ◽  
T T Sun
Keyword(s):  
Electron Microscope ◽  
Limited Proteolysis ◽  
Published Data ◽  
Model Based ◽  
Phosphate Ions ◽  
Electron Microscope Grid ◽  
Keratin Filaments ◽  
Microscope Grid

We show that intermediate-sized filaments reconstituted from human epidermal keratins appear unraveled in the presence of phosphate ions. In such unraveling filaments, up to four "4.5-nm protofibrils" can be distinguished, which are helically twisted around each other in a right-handed sense. Lowering the pH of phosphate-containing preparations causes the unraveling filaments to further dissociate into "2-nm protofilaments." In addition, we find that reconstitution of keratin extracts in the presence of small amounts of trypsin yields paracrystalline arrays of 4.5-nm protofibrils with a prominent 5.4-nm axial repeat. Limited proteolysis of intact filaments immobilized on an electron microscope grid also unveils the presence of 4.5-nm protofibrils within the filament with the same 5.4-nm axial repeat. These results, together with other published data, are consistent with a 10-nm filament model based on three distinct levels of helical organization: (a) the 2-nm protofilament, consisting of multi-chain extended alpha-helical segments coiled around each other; (b) the 4.5-nm protofibril, being a multi-stranded helix of protofilaments; and (c) the 10-nm filament, being a four-stranded helix of protofibrils.

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