scholarly journals Electron Microscopic Evidence for a Multimeric System of Plasmids in Fast-Growing Rhizobium Spp.

1979 ◽  
Vol 32 (6) ◽  
pp. 651 ◽  
Author(s):  
EA Schwinghamer ◽  
ES Dennis
Keyword(s):  
Size Range ◽  
Buoyant Density ◽  
Contour Length ◽  
Chromosomal Dna ◽  
Electron Microscopic ◽  
Fast Growing ◽  
Open Circular ◽  
Rhizobium Spp ◽  
Fast Growing Rhizobia ◽  
Wide Size Range

Covalently closed circular (CCC)-DNA could be isolated, by dye-buoyant density centrifugation, from l3 out of 15 strains from three species of fast-growing rhizobia. The plasmid band was also present in ineffective mutants and non-infective mutants derived from symbiotically effective, plasmid-carrying parent strains. The buoyant density in caesium chloride was 1� 719 g/cm3 for chromosomal DNA and 1� 715-1� 716 g/cm3 for plasmid DNA in the four strains examined. Electron microscopy of the CCC-DNA from five strains revealed a wide size range of large circular molecules, with the contour length ranging from l3. 5 to c. 170 jim (mol. wt range 28 x 106-352 x 106 ). Analysis of the size distribution of open circular molecules from the five strains indicated that a multimeric series of plasmid molecules may occur in these bacteria, with an estimated mean monomer length of l3�5 jlin.

Studies of Circular DNA Using a New Electron Microscopic Technique

1973 ◽  
Vol 31 ◽  
pp. 596-597
Author(s):  
C. N. Gordon
Keyword(s):  
Electron Microscopy ◽  
Aqueous Salt Solution ◽  
Contour Length ◽  
Cleavage Surface ◽  
Mica Substrate ◽  
Electron Microscopic ◽  
Replica Technique ◽  
Circular Dna ◽  
Transmission Electron ◽  
Electron Microscopic Technique

Gordon and Kleinschmidt have described a new preparative technique for visualizing DNA by electron microscopy. This procedure, which is a modification of Hall's “mica substrate technique”, consists of the following steps: (a) K+ ions on the cleavage surface of native mica are exchanged for Al3+ ions by ion exchange. (b) The mica, with Al3+ in the exchange sites on the surface, is placed in a dilute aqueous salt solution of DNA for several minutes; during this period DNA becomes adsorbed on the surface. (c) The mica with adsorbed DNA is removed from the DNA solution, rinsed, dried and visualized for transmission electron microscopy by Hall's platinum pre-shadow replica technique.In previous studies of circular DNA by this technique, most of the molecules seen were either broken to linears or extensively tangled; in general, it was not possible to obtain suitably large samples of open extended molecules for contour length measurements.

Existence of DNA in yeast microbodies

1978 ◽  
Vol 36 (2) ◽  
pp. 232-233
Author(s):  
Masako Osumi ◽  
Misuzu Nagano ◽  
Hiroko Kazama
Keyword(s):  
Catalase Activity ◽  
Buoyant Density ◽  
Model System ◽  
Contour Length ◽  
Native State ◽  
Normal Alkane ◽  
Remarkable Increase ◽  
Dna Molecule ◽  
Mitochondrial Dnas

We have found that microbodies appeared profusely together with a remarkable increase in catalase activity in normal alkane-grown cells of hydrocarbon-utilizing Candida yeasts, and that the microbodies multiplied by division in these cells. These features of Candida yeasts seem to provide a useful model system for studies on the biogenesis of the microbody. Subsequently, we have succeeded in isolation of Candida microbodies in an apparently native state, as judged biochemically and morphologically. The presence of DNA in the purified microbody fraction thus obtained was proved by the diphenylamine method. DNA molecule of about 15 urn in contour length was released from an isolated microbody. The physicochemical analyses of the microbody DNA revealed that its buoyant density differed from nuclear and mitochondrial DNAs. All these results lead us to the possibility that there is a novel type of DNA in microbodies.

scholarly journals Phenotypic diversity and amylolytic activity of fast growing rhizobia from pigeonpea [Cajanus cajan (L.) Millsp.]

2012 ◽  
Vol 43 (4) ◽  
pp. 1604-1612 ◽  
Author(s):  
Paulo Ivan Fernandes Júnior ◽  
Andréa Aparecida de Lima ◽  
Samuel Ribeiro Passos ◽  
Carlos Alberto Tuão Gava ◽  
Paulo Jansen de Oliveira ◽  
...  
Keyword(s):  
Cajanus Cajan ◽  
Phenotypic Diversity ◽  
Amylolytic Activity ◽  
Fast Growing ◽  
Fast Growing Rhizobia

The Mechanism of active capture of animal food by the Sergestid Shrimp Acetes Sibogae Australis

1998 ◽  
Vol 78 (2) ◽  
pp. 497-508 ◽  
Author(s):  
Lachlan Mcleay ◽  
C.G. Alexander
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Prey Capture ◽  
Size Range ◽  
The Third ◽  
Feeding Modes ◽  
In Captivity ◽  
Combined Actions ◽  
Wide Size Range ◽  
Scanning Electron

Combining the use of scanning electron microscopy and microcinematography with functional and behavioural observations has clarified many aspects underlying the feeding processes of the small planktonic sergestid shrimp Acetes sibogae australis. In captivity Acetes sibogae australis is an opportunistic feeder that uses four principal feeding modes to capture a wide size range of prey: Artemia nauplii (<0.33 mm), copepods (<1mm) and moribund Acetes (up to 25 mm). Prey capture is effected by combined actions of the first three pairs of pereiopods and the third maxillipeds before transfer to the more dorsal second maxillipeds. The second maxillipeds are the principal appendages used in securing, manipulating, sorting and rejecting prey before insertion into the vicinity of the inner mouthparts.

Genetic diversity of fast-growing rhizobia that nodulate soybean (Glycine max L. Merr)

2003 ◽  
Vol 180 (1) ◽  
pp. 45-52 ◽  
Author(s):  
Gustavo Salda�a ◽  
Virginia Martinez-Alc�ntara ◽  
Jos� M. Vinardell ◽  
Ram�n Bellog�n ◽  
Jos� E. Ru�z-Sainz ◽  
...  
Keyword(s):  
Genetic Diversity ◽  
Glycine Max ◽  
Fast Growing ◽  
Glycine Max L ◽  
Fast Growing Rhizobia

The effect of oleic acid on the synthesis of Fe3−xO4 nanoparticles over a wide size range

2015 ◽  
Vol 17 (41) ◽  
pp. 27373-27379 ◽  
Author(s):  
Carlos Moya ◽  
Xavier Batlle ◽  
Amílcar Labarta
Keyword(s):  
Thermal Decomposition ◽  
Oleic Acid ◽  
Structural Properties ◽  
Acid Concentration ◽  
Size Range ◽  
Benzyl Ether ◽  
Oleic Acid Concentration ◽  
Wide Size Range

This work reports on the effect of the oleic acid concentration on the magnetic and structural properties of Fe3−xO4 nanoparticles synthesized by thermal decomposition of Fe(acac)3 in benzyl-ether.

Production, Characterization, and Deposition of Carbon Clusters

1990 ◽  
Vol 206 ◽  
Author(s):  
Y. K. Bae ◽  
D. C. Lorents ◽  
R. Malhotra ◽  
C. H. Becker ◽  
D. Tse ◽  
...  
Keyword(s):  
High Temperatures ◽  
Thermal Desorption ◽  
Size Range ◽  
Ion Source ◽  
Carbon Clusters ◽  
Heating Process ◽  
Cluster Ion Source ◽  
Semiconductor Clusters ◽  
Cluster Ion ◽  
Wide Size Range

ABSTRACTWe have developed a new cluster ion source that can generate intense beams of metal and semiconductor clusters of a very wide-size range. With the source, we have observed intense beams of carbon clusters with mean cluster sizes of up to 4000 atoms/clusters. However, we have found that for generating small fullerenes, such as C60 and C70, the recently discovered technique by Kraetschmer et al. is much more efficient. By improving the technique, we have generated gram quantities of C60 and C70 and systematically investigated their thermal desorption properties. During the heating process, we have discovered that at high temperatures the bulk fullerenes, fullerite, transformed to another form of carbon, which still evaporates at temperatures above 700 C, but does not dissolve in benzene.

scholarly journals Saccharomyces cerevisiae cdc2 mutants fail to replicate approximately one-third of their nuclear genome.

1983 ◽  
Vol 3 (6) ◽  
pp. 1000-1012 ◽  
Author(s):  
M N Conrad ◽  
C S Newlon
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Dna Replication ◽  
Nuclear Genome ◽  
Electron Microscopic Examination ◽  
Temperature Sensitive ◽  
Chromosomal Dna ◽  
Electron Microscopic ◽  
Dna Strands ◽  
Total Dna ◽  
Random Fraction

Chromosomal DNA replication was examined in temperature-sensitive mutants of Saccharomyces cerevisiae defective in a gene required for the completion of S phase at the nonpermissive temperature, 37 degrees C. Based on incorporation of radioactive precursors and density transfer experiments, strains carrying three different alleles of cdc2 failed to replicate approximately one-third of their nuclear genome at 37 degrees C. Whole-cell autoradiography experiments demonstrated that 93 to 96% of the cells synthesized DNA at 37 degrees C. Therefore, all cells failed to replicate part of their genome. DNA isolated from terminally arrested cells was of normal size as measured on neutral and alkaline sucrose gradients, suggesting that partially replicated DNA molecules do not accumulate and that DNA strands are ligated properly in cdc2 mutants. In addition, electron microscopic examination of the equivalent of more than one genome's DNA from arrested cells failed to reveal any partially replicated molecules. The sequences which failed to replicate at 37 degrees C were not highly specific; eight different cloned sequences replicated to the same extent as total DNA. The 2-microns plasmid DNA and rDNA replicated significantly less well than total DNA, but approximately one-half of these sequences replicated at 37 degrees C. These observations suggest that cdc2 mutants are defective in an aspect of initiation of DNA replication common to all chromosomes such that a random fraction of the chromosomes fail to initiate replication at 37 degrees C, but that once initiated, replication proceeds normally.

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