scholarly journals Intramolecular heterogeneity of mitochondrial DNA of Drosophila melanogaster.

1977 ◽  
Vol 73 (2) ◽  
pp. 279-286 ◽  
Author(s):  
E S Goldring ◽  
W J Peacock
Keyword(s):  
Mitochondrial Dna ◽  
Drosophila Melanogaster ◽  
Base Composition ◽  
Gc Content ◽  
Contour Length ◽  
Regional Heterogeneity ◽  
Partial Denaturation

DNA from purified mitochondria of Drosophila melanogaster can be isolated as supercoiled molecules which when nicked have a contour length of 5.9 micron. Partial denaturation mapping shows regional heterogeneity of base composition with one early denaturing region, with a calculated GC content close to zero, extending over 20% of the genome. DNA isolated from unfertilized eggs shows nuclear and mitochondrial DNA in equal proportions; we found no evidence of other cytoplasmic species.

scholarly journals Contrasting patterns of sequence divergence and base composition between Drosophila introns and intergenic regions

2006 ◽  
Vol 2 (4) ◽  
pp. 604-607 ◽  
Author(s):  
Lino Ometto ◽  
David De Lorenzo ◽  
Wolfgang Stephan
Keyword(s):  
Drosophila Melanogaster ◽  
Recombination Rate ◽  
Base Composition ◽  
Gc Content ◽  
Sequence Divergence ◽  
Evolutionary Patterns ◽  
Nucleotide Variability ◽  
Selective Constraints ◽  
Intergenic Regions

Two non-coding DNA classes, introns and intergenic regions, of Drosophila melanogaster exhibit contrasting evolutionary patterns. GC content is significantly higher in intergenic regions and affects their degree of nucleotide variability. Divergence is positively correlated with recombination rate in intergenic regions, but not in introns. We argue that these differences are due to different selective constraints rather than mutational or recombinational mechanisms.

scholarly journals The tamas Gene, Identified as a Mutation That Disrupts Larval Behavior in Drosophila melanogaster, Codes for the Mitochondrial DNA Polymerase Catalytic Subunit (DNApol-γ125)

Genetics ◽  
1999 ◽  
Vol 153 (4) ◽  
pp. 1809-1824 ◽  
Author(s):  
Balaji Iyengar ◽  
John Roote ◽  
Ana Regina Campos
Keyword(s):  
Mitochondrial Dna ◽  
Drosophila Melanogaster ◽  
Mutant Strain ◽  
Dna Polymerase ◽  
Complementation Group ◽  
Behavioral Changes ◽  
Catalytic Subunit ◽  
Primary Deficit ◽  
Mitochondrial Dna Polymerase ◽  
Food Substrate

AbstractFrom a screen of pupal lethal lines of Drosophila melanogaster we identified a mutant strain that displayed a reproducible reduction in the larval response to light. Moreover, this mutant strain showed defects in the development of the adult visual system and failure to undergo behavioral changes characteristic of the wandering stage. The foraging third instar larvae remained in the food substrate for a prolonged period and died at or just before pupariation. Using a new assay for individual larval photobehavior we determined that the lack of response to light in these mutants was due to a primary deficit in locomotion. The mutation responsible for these phenotypes was mapped to the lethal complementation group l(2)34Dc, which we renamed tamas (translated from Sanskrit as “dark inertia”). Sequencing of mutant alleles demonstrated that tamas codes for the mitochondrial DNA polymerase catalytic subunit (DNApol-γ125).

scholarly journals Evolution of Nucleotide Composition in the SARS-CoV-2 Lineage: Implications for Vaccine Design

2020 ◽  
Author(s):  
Sankar Subramanian
Keyword(s):  
Base Composition ◽  
Scientific Community ◽  
Significant Positive Correlation ◽  
Gc Content ◽  
Nucleotide Composition ◽  
Reverse Direction ◽  
Novel Coronavirus ◽  
Near Future ◽  
Systematic Reduction ◽  
Gc Contents

The worldwide outbreak of a novel coronavirus, SARS-CoV-2 has caused a pandemic of respiratory disease. Due to this emergency, researchers around the globe have been investigating the evolution of the genome of SARS-CoV-2 in order to design vaccines. Here I examined the evolution of GC content of SARS-CoV-2 by comparing the genomes of the members of the group Betacoronavirus. The results of this investigation revealed a highly significant positive correlation between the GC contents of betacoronaviruses and their divergence from SARS-CoV-2. The betacoronaviruses that are distantly related to SARS-CoV-2 have much higher GC contents than the latter. Conversely, the closely related ones have low GC contents, which are only slightly higher than that of SARS-CoV-2. This suggests a systematic reduction in the GC content in the SARS-CoV-2 lineage over time. The declining trend in this lineage predicts a much-reduced GC content in the coronaviruses that will descend/evolve from SARS-CoV-2 in the future. Due to the three consecutive outbreaks (MERS-CoV, SARS-CoV and SARS-CoV-2) caused by the members of the SARS-CoV-2, the scientific community is emphasizing the need for universal vaccines that are effective across many strains including those, that will inevitably emerge in the near future. The reduction in GC contents implies an increase in the rate of GC→AT mutations than that the mutational changes in the reverse direction. Therefore, understanding the evolution of base composition and mutational patterns of SARS-CoV-2 could be useful in designing broad-spectrum vaccines that could identify and neutralize the present and future strains of this virus.

Filarial DNA and its interaction with polyamines and antifilarial drugs

1997 ◽  
Vol 71 (4) ◽  
pp. 325-332 ◽  
Author(s):  
U. Pandya ◽  
J.K. Saxena ◽  
O.P. Shukla
Keyword(s):  
Escherichia Coli ◽  
Secondary Structure ◽  
Melting Temperature ◽  
Base Composition ◽  
Micrococcus Luteus ◽  
Gc Content ◽  
Setaria Cervi ◽  
Calf Thymus ◽  
Absorption Studies ◽  
Z Dna

AbstractThe interaction of DNA from filarial parasite Setaria cervi with polyamines was monitored by melting temperature (Tm) profile, condensation and B to Z DNA transition and compared with DNA of Escherichia coli, Micrococcus luteus and calf thymus having different GC content. Polyamines, viz. spermine and spermidine, stabilized the secondary structure of all DNAs as indicated by increase in Tm value. UV absorption studies indicated B to Z DNA transition in the presence of polyamines. The amount of polyamines required for B to Z transition was dependent upon base composition of DNA and charge of the polyamine. Filarial DNA (AT rich) required six times higher concentration of spermine as compared to GC rich DNA for B to Z DNA transition. Spermidine was not effective in causing transition of S. cervi DNA even at Spd:DNA-P ratio of 20. The antifilarial compound suramin significantly decreased melting temperature of filarial DNA as compared to GC rich DNAs of other parasites. Suramin adversely affected condensation and B to Z DNA transition of various DNAs but prior addition of polyamines protected the DNAs from the destabilizing effect of suramin.

DNA Synthesis in Isolated Yeast Mitochondria

1974 ◽  
Vol 52 (11) ◽  
pp. 941-949 ◽  
Author(s):  
L. Zeman ◽  
C. V. Lusena
Keyword(s):  
Molecular Weight ◽  
Mitochondrial Dna ◽  
Base Composition ◽  
Nuclear Dna ◽  
Sedimentation Velocity ◽  
Yeast Saccharomyces Cerevisiae ◽  
Denatured State ◽  
Saccharomyces Cerevisiae Mitochondria

Isolated yeast (Saccharomyces cerevisiae) mitochondria incorporate radioactive precursors into mitochondrial DNA. This in vitro labelled DNA was characterized by isopycnic and sedimentation velocity centrifugation both in the native and denatured state. The profiles of isopycnic CsCl gradients obtained by centrifugation in a fixed-angle rotor are skewed toward high density. The skew is neither due to the presence of in vitro labelled nuclear DNA nor due to random breaks in mitochondrial DNA which would reveal, then, its heterogeneity in base composition. The in vitro labelled DNA is reproducibly recovered as a class of molecules sedimenting at about 5–8 S, indicating a molecular weight of 1 × 105 – 4 × 105 daltons, while the smallest in vivo labelled fragments sediment at about 13–14 S, corresponding to 1.6 × 106 – 2.0 × 106 daltons. After denaturation, the in vitro labelled DNA molecules sediment at about 2–5 S, corresponding to a single-strand molecular weight of 1 × 104 – 7 × 104 daltons, which is about one hundred times less than the observed size of the denatured in vivo labelled molecules.

scholarly journals Characterization of the genome of the mealybug Planococcus lilacinus, a model organism for studying whole-chromosome imprinting and inactivation

2002 ◽  
Vol 79 (2) ◽  
pp. 111-118 ◽  
Author(s):  
K. NAGA MOHAN ◽  
PARAMITA RAY ◽  
H. SHARAT CHANDRA
Keyword(s):  
Drosophila Melanogaster ◽  
Repetitive Sequences ◽  
Gc Content ◽  
Model Organism ◽  
Fruit Fly ◽  
Single Copy ◽  
Coding Sequences ◽  
Repeat Sequences ◽  
Chromosome Imprinting

The co-occurrence of three chromosome-wide phenomena – imprinting, facultative heterochromatization and diffuse centromere – in the mealybug Planococcus lilacinus makes investigation of the genomics of this species an attractive prospect. In order to estimate the complexity of the genome of this species, 300 random stretches of its DNA, constituting ∼0·1% of the genome, were sequenced. Coding sequences appear to constitute ∼53·5%, repeat sequences ∼44·5% and non-coding single-copy sequences ∼2% of the genome. The proportion of repetitive sequences in the mealybug is higher than that in the fruit fly Drosophila melanogaster (∼30%). The mealybug genome (∼220 Mb) is about 1·3 times the size of the fly genome (∼165 Mb) and its GC content (∼35%) less than that of the fly genome (∼40%). The relative abundance of various dinucleotides, as analysed by the method of Gentles and Karlin, shows that the dinucleotide signatures of the two species are moderately similar and that in the mealybug there is neither over-representation nor under-representation of any dinucleotide.

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.

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