DNA base composition, nature of intracellular DNA, morphology, and classification of bacteriophages infecting Micrococcus luteus

1979 ◽  
Vol 25 (9) ◽  
pp. 1027-1035 ◽  
Author(s):  
Scott W. Compton ◽  
John A. Mayo ◽  
Melanie Ehrlich ◽  
H. W. Ackermann ◽  
Lise Tremblay ◽  
...  
Keyword(s):  
Host Range ◽  
Base Composition ◽  
Micrococcus Luteus ◽  
Gc Content ◽  
Dna Base Composition ◽  
Bacterial Virus ◽  
Double Stranded Dna ◽  
Dna Base

Ten bacteriophages infecting Micrococcus luteus have been characterized. All phages contain double-stranded DNA, of 64.3–73.5 mol% guanine plus cytosine (GC). The DNA of phage N7 has the highest GC content reported for any bacterial virus. No unusual bases have been found. The intracellular replicating DNAs of six phages are covalently closed circular molecules. All 10 phages have isometric, probably icosahedral, heads and long, flexible, noncontractile tails and can be sorted into two morphological groups based on size and presence or absence of a collar. Host-range studies indicate six host-range groups.

New species of Humicola: an approach to genetic and biochemical classification

1976 ◽  
Vol 54 (24) ◽  
pp. 2755-2768 ◽  
Author(s):  
Marco de Bertoldi
Keyword(s):  
New Species ◽  
Base Composition ◽  
Genetic Relationships ◽  
Morphological Characters ◽  
Morphological Features ◽  
Dna Base Composition ◽  
Dna Base

Thirteen new species of Humicola are described: H. aurea, H. glauca, H. lutea, H. piriformis, H. repens, H. sardiniae, H. variabilis, H. atra, H. austera, H. globosa, H. nivea, H. rugosa, and H. veronae. The classification is based not only on morphological characters but also on genetic and biochemical ones. In Hyphomycetes similarities in morphology do not necessarily indicate genetic relationships. DNA base composition (guanine–cytosine percentage, GC%) and electrophoretic characteristics of enzymes used together with morphological features have proved to be useful and of taxonomical value in the classification of the new species of Humicola.

DNA base composition and the taxonomy of the Oomycetes

1972 ◽  
Vol 18 (7) ◽  
pp. 963-968 ◽  
Author(s):  
Beverley R. Green ◽  
Michael W. Dick
Keyword(s):  
Base Composition ◽  
Gradient Centrifugation ◽  
Cesium Chloride ◽  
Generic Level ◽  
Dna Base Composition ◽  
Composition Data ◽  
General Base ◽  
Dna Base ◽  
Cscl Gradient

The DNA base compositions of seven members of the Saprolegniaceae were determined by cesium chloride (CsCl) gradient centrifugation. In general, base composition data correlated with morphological classification, but in several cases it indicated the necessity for revisions. In particular, Achlya inflata (eccentric group) was 42% guanine–cytosine (GC), while A. racemosa, A. sparrowii, and A. colorata (racemose group) were 51–52% GC.Two isolates of Saprolegnia diclina and one of S. parasitica were 58–59% GC and all contained 10–20% of a lighter density satellite DNA.Analysis of thermal denaturation curves by a modification of De Ley's method (J. Theoret. Biol. 22: 89 (1969)) showed that as little as 7.4% GC difference represents a large difference in DNA sequence homology. Therefore, base composition data by itself can provide a rigorous aid to the classification of the oomycetous fungi at the generic level.

DNA base composition of filarial nematodes

Parasitology ◽  
1988 ◽  
Vol 97 (1) ◽  
pp. 75-79 ◽  
Author(s):  
N. Rothstein ◽  
T. J. Stoller ◽  
T. V. Rajan
Keyword(s):  
Base Composition ◽  
Thermal Denaturation ◽  
Gc Content ◽  
Direct Analysis ◽  
Molar Content ◽  
Free Living ◽  
Dna Base Composition ◽  
Base Content ◽  
Dna Base ◽  
Filarial Nematodes

SUMMARYWe have determined the molar content of guanine + cytosine (GC content) of DNA of the filarial nematode (Brugia malayi, Brugia pahangi and Dirofilaria imitis) and of the free-living soil nematodes Caenorhabditis elegans and have analysed the DNA for the presence of methylcytosine. Two independent methods, thermal denaturation and direct analysis of base content by HPLC following enzymatic hydrolysis, reveal that the GC content of filarial nematodes is 26–28%. We have been unable to find methylcytosine in the DNA of B. malayi.

scholarly journals Lifestyle and DNA base composition in polychaetes

2016 ◽  
Vol 48 (12) ◽  
pp. 883-888
Author(s):  
Andrea Tarallo ◽  
Maria Cristina Gambi ◽  
Giuseppe D'Onofrio
Keyword(s):  
Metabolic Rate ◽  
Base Composition ◽  
Gc Content ◽  
Active Lifestyle ◽  
Dna Base Composition ◽  
Polychaete Species ◽  
Dna Base ◽  
Biased Gene Conversion ◽  
Relationship Of ◽  
Genomic Gc Content

A comparative analysis of polychaete species, classified as motile and low-motile forms, highlighted that the former were characterized not only by a higher metabolic rate (MR), but also by a higher genomic GC content. The fluctuation of both variables was not affected by the phylogenetic relationship of the species. Thus, present results further support that a very active lifestyle affects MR and GC at the same time, showing an unexpected similarity between invertebrates and vertebrates. In teleosts, indeed, a similar pattern has been also observed in comparisons of migratory and nonmigratory species. A cause-effect link between MR and GC has not yet been proved, but the fact that the two variables are significantly linked in all the organisms so far analyzed is, most probably, of relevant biological and evolutionary meaning. The present results fit very well within the frame of the metabolic rate hypothesis proposed to explain the DNA base composition variability among organisms. On the contrary, the thermostability hypothesis was not supported. At present, no data about the recombination rate in polychaetes were available to test the biased gene conversion (BGC hypothesis).

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