The structure and function of tRNA genes of higher eukaryotes

1981 ◽  
Vol 37 (1) ◽  
pp. 1-9 ◽  
Author(s):  
Eric Kubli
Keyword(s):  
Structure And Function ◽  
Trna Genes ◽  
Higher Eukaryotes ◽  
And Function

Spatial epigenetics: linking nuclear structure and function in higher eukaryotes

2010 ◽  
Vol 48 ◽  
pp. 25-43 ◽  
Author(s):  
Dean A. Jackson
Keyword(s):  
Nuclear Structure ◽  
Genetic Information ◽  
Nuclear Architecture ◽  
Cell Types ◽  
Structure And Function ◽  
Chromatin Dynamics ◽  
Functional Product ◽  
Higher Eukaryotes ◽  
And Function ◽  
Different Cell Types

Eukaryotic cells are defined by the genetic information that is stored in their DNA. To function, this genetic information must be decoded. In doing this, the information encoded in DNA is copied first into RNA, during RNA transcription. Primary RNA transcripts are generated within transcription factories, where they are also processed into mature mRNAs, which then pass to the cytoplasm. In the cytoplasm these mRNAs can finally be translated into protein in order to express the genetic information as a functional product. With only rare exceptions, the cells of an individual multicellular eukaryote contain identical genetic information. However, as different genes must be expressed in different cell types to define the structure and function of individual tissues, it is clear that mechanisms must have evolved to regulate gene expression. In higher eukaryotes, mechanisms that regulate the interaction of DNA with the sites where nuclear functions are performed provide one such layer of regulation. In this chapter, I evaluate how a detailed understanding of nuclear structure and chromatin dynamics are beginning to reveal how spatial mechanisms link chromatin structure and function. As these mechanisms operate to modulate the genetic information in DNA, the regulation of chromatin function by nuclear architecture defines the concept of ‘spatial epigenetics’.

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.

Chloroplast tRNAs and tRNA genes: structure and function

1991 ◽  
pp. 45-57 ◽  
Author(s):  
L. Maréchal-Drouard ◽  
P. Guillemaut ◽  
H. Pfitzingzer ◽  
J. H. Weil
Keyword(s):  
Structure And Function ◽  
Trna Genes ◽  
And Function

scholarly journals An evidence based hypothesis on the existence of two pathways of mitochondrial crista formation

eLife ◽  
2016 ◽  
Vol 5 ◽  
Author(s):  
Max E Harner ◽  
Ann-Katrin Unger ◽  
Willie JC Geerts ◽  
Muriel Mari ◽  
Toshiaki Izawa ◽  
...  
Keyword(s):  
Protein Complexes ◽  
Structure And Function ◽  
Evidence Based ◽  
Molecular Pathways ◽  
Metabolic Function ◽  
F1fo Atp Synthase ◽  
Higher Eukaryotes ◽  
And Function ◽  
Open Question ◽  
Boundary Membrane

Metabolic function and architecture of mitochondria are intimately linked. More than 60 years ago, cristae were discovered as characteristic elements of mitochondria that harbor the protein complexes of oxidative phosphorylation, but how cristae are formed, remained an open question. Here we present experimental results obtained with yeast that support a novel hypothesis on the existence of two molecular pathways that lead to the generation of lamellar and tubular cristae. Formation of lamellar cristae depends on the mitochondrial fusion machinery through a pathway that is required also for homeostasis of mitochondria and mitochondrial DNA. Tubular cristae are formed via invaginations of the inner boundary membrane by a pathway independent of the fusion machinery. Dimerization of the F1FO-ATP synthase and the presence of the MICOS complex are necessary for both pathways. The proposed hypothesis is suggested to apply also to higher eukaryotes, since the key components are conserved in structure and function throughout evolution.

scholarly journals The Where, When, and How of Organelle Acidification by the Yeast Vacuolar H+-ATPase

2006 ◽  
Vol 70 (1) ◽  
pp. 177-191 ◽  
Author(s):  
Patricia M. Kane
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Current Knowledge ◽  
Structure And Function ◽  
Regulatory Mechanisms ◽  
Eukaryotic Cells ◽  
Higher Eukaryotes ◽  
Specific Regulation ◽  
And Function ◽  
Acidic Organelles ◽  
The Relationship

SUMMARY All eukaryotic cells contain multiple acidic organelles, and V-ATPases are central players in organelle acidification. Not only is the structure of V-ATPases highly conserved among eukaryotes, but there are also many regulatory mechanisms that are similar between fungi and higher eukaryotes. These mechanisms allow cells both to regulate the pHs of different compartments and to respond to changing extracellular conditions. The Saccharomyces cerevisiae V-ATPase has emerged as an important model for V-ATPase structure and function in all eukaryotic cells. This review discusses current knowledge of the structure, function, and regulation of the V-ATPase in S. cerevisiae and also examines the relationship between biosynthesis and transport of V-ATPase and compartment-specific regulation of acidification.

Structure and function of neural networks in the retina

1988 ◽  
Vol 46 ◽  
pp. 26-27
Author(s):  
Peter Sterling
Keyword(s):  
Ganglion Cells ◽  
Three Dimensional ◽  
Structure And Function ◽  
Synaptic Connections ◽  
Visual Axis ◽  
One Dimensional ◽  
Cat Retina ◽  
Ultrathin Sections ◽  
And Function ◽  
Insight Into

The synaptic connections in cat retina that link photoreceptors to ganglion cells have been analyzed quantitatively. Our approach has been to prepare serial, ultrathin sections and photograph en montage at low magnification (˜2000X) in the electron microscope. Six series, 100-300 sections long, have been prepared over the last decade. They derive from different cats but always from the same region of retina, about one degree from the center of the visual axis. The material has been analyzed by reconstructing adjacent neurons in each array and then identifying systematically the synaptic connections between arrays. Most reconstructions were done manually by tracing the outlines of processes in successive sections onto acetate sheets aligned on a cartoonist's jig. The tracings were then digitized, stacked by computer, and printed with the hidden lines removed. The results have provided rather than the usual one-dimensional account of pathways, a three-dimensional account of circuits. From this has emerged insight into the functional architecture.

Osseointegration interface of calcified bone and endosseous implants

1992 ◽  
Vol 50 (2) ◽  
pp. 1096-1097
Author(s):  
K.E. Krizan ◽  
J.E. Laffoon ◽  
M.J. Buckley
Keyword(s):  
Structure And Function ◽  
Titanium Implants ◽  
En Bloc ◽  
Endosseous Implants ◽  
Ultrastructural Studies ◽  
The Past ◽  
Cacodylate Buffer ◽  
One Year ◽  
And Function

With increase use of tissue-integrated prostheses in recent years it is a goal to understand what is happening at the interface between haversion bone and bulk metal. This study uses electron microscopy (EM) techniques to establish parameters for osseointegration (structure and function between bone and nonload-carrying implants) in an animal model. In the past the interface has been evaluated extensively with light microscopy methods. Today researchers are using the EM for ultrastructural studies of the bone tissue and implant responses to an in vivo environment. Under general anesthesia nine adult mongrel dogs received three Brånemark (Nobelpharma) 3.75 × 7 mm titanium implants surgical placed in their left zygomatic arch. After a one year healing period the animals were injected with a routine bone marker (oxytetracycline), euthanized and perfused via aortic cannulation with 3% glutaraldehyde in 0.1M cacodylate buffer pH 7.2. Implants were retrieved en bloc, harvest radiographs made (Fig. 1), and routinely embedded in plastic. Tissue and implants were cut into 300 micron thick wafers, longitudinally to the implant with an Isomet saw and diamond wafering blade [Beuhler] until the center of the implant was reached.

Use of human autoantibodies and immunoelectron microscopy to study structure and function of the nucleolus and nuclear bodies

1992 ◽  
Vol 50 (1) ◽  
pp. 506-507
Author(s):  
Robert L. Ochs
Keyword(s):  
Electron Microscopy ◽  
Structure And Function ◽  
Nuclear Bodies ◽  
Nuclear Interior ◽  
Coiled Bodies ◽  
Interchromatin Granules ◽  
And Function ◽  
Conventional Electron Microscopy ◽  
Perichromatin Granules ◽  
Perichromatin Fibrils

By conventional electron microscopy, the formed elements of the nuclear interior include the nucleolus, chromatin, interchromatin granules, perichromatin granules, perichromatin fibrils, and various types of nuclear bodies (Figs. 1a-c). Of these structures, all have been reasonably well characterized structurally and functionally except for nuclear bodies. The most common types of nuclear bodies are simple nuclear bodies and coiled bodies (Figs. 1a,c). Since nuclear bodies are small in size (0.2-1.0 μm in diameter) and infrequent in number, they are often overlooked or simply not observed in any random thin section. The rat liver hepatocyte in Fig. 1b is a case in point. Historically, nuclear bodies are more prominent in hyperactive cells, they often occur in proximity to nucleoli (Fig. 1c), and sometimes they are observed to “bud off” from the nucleolar surface.

Depletion and Reconstitution of Active E. Coli Ribosomes

1975 ◽  
Vol 33 ◽  
pp. 640-641
Author(s):  
M. Boublik ◽  
W. Hellmann ◽  
F. Jenkins
Keyword(s):  
Protein Biosynthesis ◽  
Large Subunit ◽  
High Resolution Electron Microscopy ◽  
Small Subunit ◽  
Structure And Function ◽  
Biologically Active ◽  
Biological Macromolecules ◽  
E Coli ◽  
Resolution Electron ◽  
And Function

Correlations between structure and function of biological macromolecules have been studied intensively for many years, mostly by indirect methods. High resolution electron microscopy is a unique tool which can provide such information directly by comparing the conformation of biopolymers in their biologically active and inactive state. We have correlated the structure and function of ribosomes, ribonucleoprotein particles which are the site of protein biosynthesis. 70S E. coli ribosomes, used in this experiment, are composed of two subunits - large (50S) and small (30S). The large subunit consists of 34 proteins and two different ribonucleic acid molecules. The small subunit contains 21 proteins and one RNA molecule. All proteins (with the exception of L7 and L12) are present in one copy per ribosome.This study deals with the changes in the fine structure of E. coli ribosomes depleted of proteins L7 and L12. These proteins are unique in many aspects.

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