scholarly journals In situ analyses reveal that the two nuclei of Giardia lamblia are equivalent

1990 ◽  
Vol 95 (3) ◽  
pp. 353-360 ◽  
Author(s):  
K.S. Kabnick ◽  
D.A. Peattie
Keyword(s):  
Ribosomal Dna ◽  
Dna Sequences ◽  
Giardia Lamblia ◽  
Transcriptional Activity ◽  
Protozoan Parasite ◽  
Structure And Function ◽  
Higher Eukaryotes ◽  
And Function

The protozoan parasite Giardia lamblia has the unusual morphology of bearing two equal-sized nuclei. This organism probably represents the earliest diverging lineage of eukaryotes, suggesting that its biological tactics may be transitional. To begin to understand the role played by the two equal-sized nuclei in this organism, and perhaps the role this organism has played along the path to higher eukaryotes, we have analyzed the structure and function of these two nuclei. We show that the two nuclei are equivalent with respect to the amount of DNA harbored in each nucleus, the presence of ribosomal DNA sequences, and the transcriptional activity. We begin also to address the question of how these bilaterally symmetrical ancestors divide, by illustrating the mitotic plane of division.

scholarly journals Islands of complex DNA are widespread in Drosophila centric heterochromatin.

Genetics ◽  
1995 ◽  
Vol 141 (1) ◽  
pp. 283-303
Author(s):  
M H Le ◽  
D Duricka ◽  
G H Karpen
Keyword(s):  
Dna Sequences ◽  
Structure And Function ◽  
Southern Analysis ◽  
Cloning And Sequencing ◽  
Pulsed Field ◽  
Drosophila Heterochromatin ◽  
And Function ◽  
Heterochromatin Structure ◽  
Derivatives Of ◽  
Eukaryotic Genomes

Abstract Heterochromatin is a ubiquitous yet poorly understood component of multicellular eukaryotic genomes. Major gaps exist in our knowledge of the nature and overall organization of DNA sequences present in heterochromatin. We have investigated the molecular structure of the 1 Mb of centric heterochromatin in the Drosophila minichromosome Dp1187. A genetic screen of irradiated minichromosomes yielded rearranged derivatives of Dp1187 whose structures were determined by pulsed-field Southern analysis and PCR. Three Dp1187 deletion derivatives and an inversion had one breakpoint in the euchromatin and one in the heterochromatin, providing direct molecular access to previously inaccessible parts of the heterochromatin. End-probed pulsed-field restriction mapping revealed the presence of at least three "islands" of complex DNA, Tahiti, Moorea, and Bora Bora, constituting approximately one half of the Dp1187 heterochromatin. Pulsed-field Southern analysis demonstrated that Drosophila heterochromatin in general is composed of alternating blocks of complex DNA and simple satellite DNA. Cloning and sequencing of a small part of one island, Tahiti, demonstrated the presence of a retroposon. The implications of these findings to heterochromatin structure and function are discussed.

scholarly journals DNAContentViewer a BioJS component to visualise GC/AT Content

F1000Research ◽  
2014 ◽  
Vol 3 ◽  
pp. 54 ◽  
Author(s):  
Anil S. Thanki ◽  
Shabhonam Caim ◽  
Manuel Corpas ◽  
Robert P. Davey
Keyword(s):  
Dna Sequences ◽  
Genome Analysis ◽  
Biological Function ◽  
Structure And Function ◽  
Link Type ◽  
And Function ◽  
Potential Interactions

Summary: Compositional GC/AT content of DNA sequences is a useful feature in genome analysis. GC/AT content provides useful information about evolution, structure and function of genomes, giving clues about their biological function and organisation. We have developed DNAContentViewer, a BioJS component for visualisation of compositional GC/AT content in raw sequences. DNAContentViewer has been integrated in the BioJS project as part of the BioJS registry of components. DNAContentViewer requires a simple configuration and installation. Its design allows potential interactions with other components via predefined events. Availability: http://github.com/biojs/biojs; doi: 10.5281/zenodo.7722.

scholarly journals Structure prediction of crystals, surfaces and nanoparticles

2020 ◽  
Vol 378 (2186) ◽  
pp. 20190600
Author(s):  
Scott M. Woodley ◽  
Graeme M. Day ◽  
R. Catlow
Keyword(s):  
Machine Learning ◽  
Energy Function ◽  
Structure Prediction ◽  
Search Algorithm ◽  
Structure And Function ◽  
Current Status ◽  
Organic Systems ◽  
And Function

We review the current techniques used in the prediction of crystal structures and their surfaces and of the structures of nanoparticles. The main classes of search algorithm and energy function are summarized, and we discuss the growing role of methods based on machine learning. We illustrate the current status of the field with examples taken from metallic, inorganic and organic systems. This article is part of a discussion meeting issue ‘Dynamic in situ microscopy relating structure and function’.

scholarly journals Structure and function of a nitrifying biofilm as determined by in situ hybridization and the use of microelectrodes.

1996 ◽  
Vol 62 (12) ◽  
pp. 4641-4647 ◽  
Author(s):  
A Schramm ◽  
L H Larsen ◽  
N P Revsbech ◽  
N B Ramsing ◽  
R Amann ◽  
...  
Keyword(s):  
In Situ Hybridization ◽  
Structure And Function ◽  
And Function

Progress in ultrastructural and molecular analysis of the nuclear matrix

1992 ◽  
Vol 50 (1) ◽  
pp. 508-509
Author(s):  
Edward G. Fey
Keyword(s):  
Electron Microscopy ◽  
Nuclear Matrix ◽  
Structure And Function ◽  
Matrix Proteins ◽  
Rna Transcription ◽  
Nuclear Matrix Proteins ◽  
The Past ◽  
And Function

In the past few years, considerable advances have been made regarding the structure and function of the nuclear matrix. In the first half of this presentation, the field of nuclear matrix research will be summarized. Emphasis will be placed on those studies where molecular interactions are demonstrated in situ utilizing high resolution light and/or electron microscopy. Studies demonstrating the role of the nuclear matrix in DNA synthesis and replication, RNA transcription and processing, and the binding of matrix attachment regions to specific nuclear matrix proteins will be summarized.

scholarly journals Energetics of life on the deep seafloor

2012 ◽  
Vol 109 (38) ◽  
pp. 15366-15371 ◽  
Author(s):  
Craig R. McClain ◽  
Andrew P. Allen ◽  
Derek P. Tittensor ◽  
Michael A. Rex
Keyword(s):  
Carbon Flux ◽  
Regulatory Policy ◽  
Structure And Function ◽  
Chemical Energy ◽  
Metabolic Theory ◽  
Biological Organization ◽  
Biochemical Kinetics ◽  
Energy Limitation ◽  
And Function

With frigid temperatures and virtually no in situ productivity, the deep oceans, Earth’s largest ecosystem, are especially energy-deprived systems. Our knowledge of the effects of this energy limitation on all levels of biological organization is very incomplete. Here, we use the Metabolic Theory of Ecology to examine the relative roles of carbon flux and temperature in influencing metabolic rate, growth rate, lifespan, body size, abundance, biomass, and biodiversity for life on the deep seafloor. We show that the relative impacts of thermal and chemical energy change across organizational scales. Results suggest that individual metabolic rates, growth, and turnover proceed as quickly as temperature-influenced biochemical kinetics allow but that chemical energy limits higher-order community structure and function. Understanding deep-sea energetics is a pressing problem because of accelerating climate change and the general lack of environmental regulatory policy for the deep oceans.

Nonrandom distribution of long mono- and dinucleotide repeats in Drosophila chromosomes: correlations with dosage compensation, heterochromatin, and recombination

1989 ◽  
Vol 9 (3) ◽  
pp. 1173-1182
Author(s):  
K Lowenhaupt ◽  
A Rich ◽  
M L Pardue
Keyword(s):  
Y Chromosome ◽  
Dna Sequences ◽  
Polytene Chromosomes ◽  
Drosophila Species ◽  
Repeated Dna ◽  
Dinucleotide Repeats ◽  
Order Of Magnitude ◽  
The Individual ◽  
And Function

Long stretches of (dC-dA)n.(dT-dG)n, abbreviated CA/TG, have a distinctive distribution on Drosophila chromosomes (M.L. Pardue, K. Lowenhaupt, A. Rich, and A. Nordheim, EMBO J. 6:1781-1789, 1987). The distribution of CA/TG suggests a correlation with the overall transcriptional activity of chromosomal regions and with the ability to undergo meiotic recombination. These correlations are conserved among Drosophila species and may indicate one or more chromosomal functions. To test the generality of these findings, we analyzed the distribution of the rest of the six possible mono- and dinucleotide repeats (A/T, C/G, AT/AT, CA/TG, CT/AG, and CG/CG). All but CG/CG were present at significant levels in the genomes of the six Drosophila species studied; however, A/T levels were an order of magnitude lower than those of the other sequences. Data base analyses suggested that the same sequences are present in other eucaryotes. Like CA/TG, both CT/AG and C/G showed increased levels on dosage-compensating chromosomes; however, the individual sites clearly differed for each sequence. In contrast, A/T and AT/AT, although present in Drosophila DNA, could not be detected in situ in polytene chromosomes. We also used in situ hybridization to analyze the neo-Y chromosome of Drosophila miranda, an ancestral autosome that has become attached to the Y chromosome and is now partially heterochromatic. The neo-Y has acquired repeated DNA sequences; we found that the added sequences are as devoid of mono- and dinucleotide repeats as other heterochromatin. The distribution and function of these sequences are likely to result from both their repetitious nature and base contents.

Sign in / Sign up

Export Citation Format

Share Document