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.

William Bateson, Richard Goldschmidt, and Non-Genic Modes of Speciation

2003 ◽  
Vol 11 (04) ◽  
pp. 341-350 ◽  
Author(s):  
D. R. Forsdyke
Keyword(s):  
New Species ◽  
Base Composition ◽  
Hybrid Sterility ◽  
Parental Factors ◽  
Dna Base Composition ◽  
William Bateson ◽  
Dna Base ◽  
Negative Effect ◽  
Positive Effect ◽  
Richard Goldschmidt

Sometimes a cross between two individuals that appear to belong to the same species produces a sterile offspring (i.e., their hybrid is sterile). Thus, the two individuals appear reproductively isolated from each other. If each could find a compatible mate, then new species might emerge. At issue is whether the form of hybrid sterility that precedes sympatric differentiation into species is, in the general case, of genic or non-genic origin. Several recent papers lend the authority of William Bateson to the genic hypothesis, referring to the "Bateson–Dobzhansky–Muller hypothesis". All these papers cite a 1996 paper that, in turn, cites a 1909 paper of Bateson. However, from 1902 until 1926 the latter espoused a non-genic hypothesis that today would be classified as "chromosomal". Analysis of Bateson's 1909 text reveals no recantation. Bateson's non-genic view was similar to that advanced by Richard Goldschmidt in the 1940s. However, Bateson proposed a contribution from parents of abstract factors that, together in their hybrids, complement to bring about a negative effect (hybrid sterility). In contrast, Goldschmidt proposed that normally parents contribute complementary factors making parental chromosomes compatible at meiosis in their hybrids, which hence are fertile (i.e., the parental factors work together to produce a positive effect). When the factors are not sufficiently complementary the parental chromosomes are incompatible in their hybrids, which hence are sterile. The non-genic Batesonian–Goldschmidtian abstractions are now being fleshed-out chemically in terms of DNA base-composition differences.

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.

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.

scholarly journals Spiroplasma insolitum sp. nov., a New Species of Group I Spiroplasma with an Unusual DNA Base Composition

1993 ◽  
Vol 43 (2) ◽  
pp. 272-277 ◽  
Author(s):  
K. J. Hackett ◽  
R. F. Whitcomb ◽  
J. G. Tully ◽  
D. L. Rose ◽  
P. Carle ◽  
...  
Keyword(s):  
New Species ◽  
Base Composition ◽  
Dna Base Composition ◽  
Group I ◽  
Dna Base ◽  
A New Species
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