Spontaneous induction of bacteriophage during growth of Azospirillum brasilense in complex media

1984 ◽  
Vol 30 (6) ◽  
pp. 805-808 ◽  
Author(s):  
James J. Germida
Keyword(s):  
Electron Microscopy ◽  
Host Range ◽  
Azospirillum Brasilense ◽  
Divalent Cations ◽  
Complex Media ◽  
Icosahedral Head

Spontaneous induction of bacteriophage occurred during growth of Azospirillum brasilense ATCC 29145 in complex media incubated at 27 or 30 °C under agitated and nonagitated conditions. Phage replication on strain 29145 was stimulated by divalent cations and inhibited by NaCl or temperatures greater than 37 °C. The phage morphology as revealed by electron microscopy showed an icosahedral head of 60 nm and a tail of 208 nm. The host range was limited to A. brasilense strains 29145 and 29710. Other Azospirillum strains tested did not produce phage under any of the conditions tested.

Fighting foam with phages?

2002 ◽  
Vol 46 (1-2) ◽  
pp. 511-518 ◽  
Author(s):  
J.A. Thomas ◽  
J.A. Soddell ◽  
D.I. Kurtböke
Keyword(s):  
Activated Sludge ◽  
Host Range ◽  
Contractile Tail ◽  
Icosahedral Head

Seventeen (17) phages infective for the mycolata were isolated from six samples of activated sludge using 21 prospective hosts from the genera Dietzia, Gordonia, Nocardia, Rhodococcus, Tsukamurella and Mycobacterium. Their morphology indicated that they were all members of the viral family Siphoviridae, but they varied in the size of the icosahedral head and length of non-contractile tail, suggesting they were different. This was confirmed by host-range studies with 47 strains of mycolata, which showed that each phage had a unique host-range, and this was polyvalent in the majority (15/17) of cases, with 12 phages infective for hosts representing two or three of the genera Gordonia, Nocardia and Rhodococcus. The potential for use of these phages in the control of foaming and other applications is discussed.

Isolation and genetic analysis of Azospirillum brasilense Nif− mutants

1983 ◽  
Vol 29 (8) ◽  
pp. 968-972 ◽  
Author(s):  
P. Jara ◽  
B. Quiviger ◽  
P. Laurent ◽  
C. Elmerich
Keyword(s):  
Genetic Analysis ◽  
Host Range ◽  
Azospirillum Brasilense ◽  
Nitrogenase Activity ◽  
Plasmid Vector ◽  
Ecori Fragment ◽  
Broad Host Range ◽  
Broad Host Range Plasmid ◽  
Ethylmethane Sulfonate ◽  
Derivatives Of

After ethylmethane sulfonate mutagenesis of Azospirillum brasilense strain 7000, mutants devoid of nitrogenase activity were isolated. Partial diploids were constructed by introducing plasmids pAB35 and pAB36 into the Nif− mutants. The two plasmids were derivatives of the broad host-range plasmid vector pRK290. Plasmid pAB35 contained a 6.7 kilobase pairs (kb) EcoRI fragment which carried the nifHDK gene cluster cloned from strain 7000. Plasmid pAB36 contained the same fragment from which a 2.6-kb PstI fragment that likely covers nifK, and a part of nifD was deleted. The restoration of a Nif+ phenotype by pAB35, but not by pAB36, was observed in the case of mutant 7571, which might be impaired in a structural gene for the nitrogenase complex.

scholarly journals The β-tail domain (βTD) regulates physiologic ligand binding to integrin CD11b/CD18

Blood ◽  
2006 ◽  
Vol 109 (8) ◽  
pp. 3513-3520 ◽  
Author(s):  
Vineet Gupta ◽  
Annette Gylling ◽  
José Luis Alonso ◽  
Takashi Sugimori ◽  
Petre Ianakiev ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Ligand Binding ◽  
Conformational Changes ◽  
Divalent Cations ◽  
Contact Region ◽  
Allosteric Modulator ◽  
Tail Domain ◽  
Wild Type ◽  
High Affinity

Abstract Crystallographic and electron microscopy studies revealed genuflexed (bent) integrins in both unliganded (inactive) and physiologic ligandbound (active) states, suggesting that local conformational changes are sufficient for activation. Herein we have explored the role of local changes in the contact region between the membrane-proximal β-tail domain (βTD) and the ligand-binding βA domain of the bent conformation in regulating interaction of integrin CD11b/CD18 (αMβ2) with its physiologic ligand iC3b. We replaced the βTD CD loop residues D658GMD of the CD18 (β2) subunit with the equivalent D672SSG of the β3 subunit, with AGAA or with NGTD, expressed the respective heterodimeric receptors either transiently in epithelial HEK293T cells or stably in leukocytes (K562), and measured their ability to bind iC3b and to conformation-sensitive mAbs. In the presence of the physiologic divalent cations Ca2+ plus Mg2+ (at 1 mM each), the modified integrins showed increased (in HEK293) or constitutive (in K562) binding to iC3b compared with wild-type receptors. K562 expressing the βTD-modified integrins bound in Ca2+Mg2+ to the βA-directed high-affinity reporter mAb 24 but not to mAb KIM127, a reporter of the genu-straightened state. These data identify a role for the membrane proximal βTD as an allosteric modulator of integrin activation.

Adhesion of Golgi cisternae by proteinaceous interactions: intercisternal bridges as putative adhesive structures

1992 ◽  
Vol 103 (3) ◽  
pp. 773-784 ◽  
Author(s):  
E.B. Cluett ◽  
W.J. Brown
Keyword(s):  
Electron Microscopy ◽  
Tannic Acid ◽  
Golgi Complex ◽  
Proteolytic Enzymes ◽  
Divalent Cations ◽  
Secretory Vesicles ◽  
Bridge Structure ◽  
Electron Microscopic ◽  
Bridge Structures ◽  
Dose Dependent

We have investigated the nature of the component(s) responsible for holding the cisternal membranes of the Golgi complex into a stacked unit. Isolated Golgi complexes were treated with a variety of agents to induce the separation of intact Golgi stacks into single cisternal elements, i.e. “unstacking”, and the effects were analyzed and quantitated by electron microscopy. In control experiments, isolated, intact Golgi stacks were stable at 4 degrees C and 20 degrees C for > or = 1 h; however, some unstacking occurred at 32 degrees C. Treatment of intact Golgi stacks with a variety of proteolytic enzymes resulted in a time- and dose-dependent unstacking of the cisternae, although stacks were resistant to various other proteases. Following liberation from the stack, single cisternae remained flattened with dilated rims. The integrity of intact Golgi stacks was unaffected by treatment with various concentrations and combinations of monovalent and divalent cations, or chelators of divalent cations. Electron microscopic observations of tannic acid- or negatively stained Golgi complexes, revealed the presence of highly structured, intercisternal “bridges”. When seen within intact Golgi complexes, these bridges were only consistently found between closely apposed cisternae and were not observed on dilated rims or secretory vesicles. These bridges, on both intact stacks and physically disrupted cisternae, were rectangular, being approximately 8.5 nm in width, approximately 11 nm in height. Treatment with proteases under conditions that resulted in the with proteases under conditions that resulted in the unstacking of intact complexes also removed these bridge structures. These data show that proteinaceous components are responsible for holding Golgi cisternae together into a cohesive, stacked unit, and identify a candidate bridge structure that could serve this purpose.

scholarly journals CRITIQUE ON THE K-PYROANTIMONATE METHOD FOR SEMIQUANTITATIVE ESTIMATION OF CATIONS IN CONJUNCTION WITH ELECTRON MICROSCOPY

1972 ◽  
Vol 20 (1) ◽  
pp. 65-78 ◽  
Author(s):  
RICHARD L. KLEIN ◽  
SHYUE-SHONG YEN ◽  
ÅSA THURESON-KLEIN
Keyword(s):  
Electron Microscopy ◽  
Divalent Cations ◽  
Test Tube ◽  
Tetraacetic Acid ◽  
Test Conditions ◽  
Solubility Products ◽  
Controlled Preparation ◽  
Preparation Techniques ◽  
Potassium Pyroantimonate

The histochemical method employing potassium pyroantimonate in conjunction with electron microscopy has been investigated using carefully controlled preparation techniques and very sensitive atomic absorption analysis of cations. A critique on the reliability and limitations of the method based on test tube and in vitro experiments is given. The method is sensitive to Ca++, Mg++ and Na+ at the 10–6, 10–5 and <10–2 M levels, respectively. Under defined conditions a linear ~l:l ratio of cation present to cation precipitated occurs above these levels. Approximate solubility products have been estimated. Under the test conditions, K+ does not precipitate as a pyroantimonate salt, and neither K+ nor OsO4 influences cation precipitaton at physiologic concentrations. Unbuffered, Tris-HCl-buffered and weakly buffered NaHCO3 media at pH 7.2-7.8 give statistically similar results with Na+ precipitation. The pyroantimonate ion can compete with chelators, ethylenedinitrilotetraacetic acid and ethylene glycol bis-N, N'-tetraacetic acid, for divalent cations when employed simultaneously. These chelators effectively remove Ca++ but not Mg++ from embryonic myocardium, and their effects on Na+ and K+ balance are not marked if employed for relatively short periods. Electron micrographic examples of cation precipitates are given in support of certain findings. A brief discussion of the significance of pyroantimonate grain size, the discrepancy between the ratio of intra- and extracellular precipitates and guidelines for the use of the method are included.

scholarly journals Molecular, Ultrastructural, and Biological Characterization of Pennsylvania Isolates of Plum pox virus

2011 ◽  
Vol 101 (5) ◽  
pp. 627-636 ◽  
Author(s):  
William L. Schneider ◽  
Vernon D. Damsteegt ◽  
Fred E. Gildow ◽  
Andrew L. Stone ◽  
Diana J. Sherman ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Host Range ◽  
The United States ◽  
Plum Pox Virus ◽  
Biological Characterization ◽  
Multiple Introductions ◽  
Aphis Spiraecola ◽  
Electron Microscopy Analysis ◽  
Microscopy Analysis

Plum pox virus (PPV) was identified in Pennsylvania in 1999. The outbreak was limited to a four-county region in southern Pennsylvania. Initial serological and molecular characterization indicated that the isolates in Pennsylvania belong to the D strain of PPV. The Pennsylvania isolates were characterized by sequence analysis, electron microscopy, host range, and vector transmission to determine how these isolates related to their previously studied European counterparts. Genetically, Pennsylvania (PPV-Penn) isolates were more closely related to each other than to any other PPV-D strains, and isolates from the United States, Canada, and Chile were more closely related to each other than to European isolates. The PPV-Penn isolates exist as two clades, suggesting the possibility of multiple introductions. Electron microscopy analysis of PPV-Penn isolates, including cytopathological studies, indicated that the virions were similar to other Potyvirus spp. PPV-Penn isolates had a herbaceous host range similar to that of European D isolates. There were distinct differences in the transmission efficiencies of the two PPV-Penn isolates using Myzus persicae and Aphis spiraecola as vectors; however, both PPV-Penn isolates were transmitted by M. persicae more efficiently than a European D isolate but less efficiently than a European M isolate.

Further properties of P-2 R-factors of Pseudomonas aeruginosa and their relationship to other plasmid groups

1975 ◽  
Vol 21 (5) ◽  
pp. 592-605 ◽  
Author(s):  
M. S. Shahrabadi ◽  
L. E. Bryan ◽  
H. M. Van Den Elzen
Keyword(s):  
Electron Microscopy ◽  
Pseudomonas Aeruginosa ◽  
Host Range ◽  
Dna Hybridization ◽  
Classification Scheme ◽  
Incompatibility Group ◽  
R Factor ◽  
Significant Homology ◽  
Pseudomonas Species ◽  
R Factors

R-factors of the P-2 (prototype R-factor R931) incompatibility group pf plasmids detected in Pseudomonas are compatible with group P, C, W, and N R-factors which are plasmids that can be transferred to Pseudomonas aeruginosa recipients. Members of the P-2 group (R130, R931) have significant homology by DNA–DNA hybridization. R-factors of the P-group (RP1, RP9) and F-group (R1) exhibited homology with P-2 R-factors but to a lesser extent than R130 with R931. Members of the 1, C, and W groups showed no significant homology with P-2 R-factors. Minicircular DNA of strain 931(R931) was not homologous with R931 DNA. The host range of R931 and R130 is limited mainly to certain Pseudomonas species including P. aeruginosa, P. fluorescens, P. putida, and P. stutzeri. These R-factors could not be transferred at detectable frequencies to any member of the Enterobacteriaceae examined. R-factor-specified pili were strongly suggested by the detection of pili by electron microscopy in R+ but not R− non-piliated mutants of P. aeruginosa strain PA01. The combined properties of R-factors 931 and similar R-factors reported before and in this study strongly support our previous contention that this group of R-factors form a significant new group of plasmids. A classification scheme previously proposed for plasmids occurring in Pseudomonas has been modified and four groups have been specified.

scholarly journals The Terminally Redundant, Nonpermuted Genome of Listeria Bacteriophage A511: a Model for the SPO1-Like Myoviruses of Gram-Positive Bacteria

2008 ◽  
Vol 190 (17) ◽  
pp. 5753-5765 ◽  
Author(s):  
Jochen Klumpp ◽  
Julia Dorscht ◽  
Rudi Lurz ◽  
Regula Bielmann ◽  
Matthias Wieland ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Host Range ◽  
Genome Structure ◽  
High Resolution Electron Microscopy ◽  
Open Reading Frames ◽  
Trna Genes ◽  
Broad Host Range ◽  
Gram Positive ◽  
Terminal Repeats ◽  
Sequence Relatedness

ABSTRACT Only little information on a particular class of myoviruses, the SPO1-like bacteriophages infecting low-G+C-content, gram-positive host bacteria (Firmicutes), is available. We present the genome analysis and molecular characterization of the large, virulent, broad-host-range Listeria phage A511. A511 contains a unit (informational) genome of 134,494 bp, encompassing 190 putative open reading frames (ORFs) and 16 tRNA genes, organized in a modular fashion common among the Caudovirales. Electron microscopy, enzymatic fragmentation analyses, and sequencing revealed that the A511 DNA molecule contains linear terminal repeats of a total of 3,125 bp, encompassing nine small putative ORFs. This particular genome structure explains why A511 is unable to perform general transduction. A511 features significant sequence homologies to Listeria phage P100 and other morphologically related phages infecting Firmicutes such as Staphylococcus phage K and Lactobacillus phage LP65. Equivalent but more-extensive terminal repeats also exist in phages P100 (∼6 kb) and K (∼20 kb). High-resolution electron microscopy revealed, for the first time, the presence of long tail fibers organized in a sixfold symmetry in these viruses. Mass spectrometry-based peptide fingerprinting permitted assignment of individual proteins to A511 structural components. On the basis of the data available for A511 and relatives, we propose that SPO1-like myoviruses are characterized by (i) their infection of gram-positive, low-G+C-content bacteria; (ii) a wide host range within the host bacterial genus and a strictly virulent lifestyle; (iii) similar morphology, sequence relatedness, and collinearity of the phage genome organization; and (iv) large double-stranded DNA genomes featuring nonpermuted terminal repeats of various sizes.

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