ABSTRACT
The complete genome sequence of the radiation-resistant bacterium Deinococcus radiodurans R1 is composed of two chromosomes (2,648,638 and 412,348 base pairs), a megaplasmid (177,466 base pairs), and a small plasmid (45,704 base pairs), yielding a total genome of 3,284, 156 base pairs. Multiple components distributed on the chromosomes and megaplasmid that contribute to the ability of D. radiodurans to survive under conditions of starvation, oxidative stress, and high amounts of DNA damage were identified. Deinococcus radiodurans represents an organism in which all systems for DNA repair, DNA damage export, desiccation and starvation recovery, and genetic redundancy are present in one cell.
Subject(s)
Genome, Bacterial , Gram-Positive Cocci/genetics , Physical Chromosome Mapping , Sequence Analysis, DNA , Bacterial Proteins/biosynthesis , Bacterial Proteins/chemistry , Bacterial Proteins/genetics , Catalase/genetics , Chromosomes, Bacterial/genetics , DNA Damage , DNA Repair/genetics , DNA, Bacterial/genetics , Energy Metabolism , Genes, Bacterial , Gram-Positive Cocci/chemistry , Gram-Positive Cocci/classification , Gram-Positive Cocci/radiation effects , Molecular Sequence Data , Open Reading Frames , Oxidative Stress , Plasmids , Radiation Tolerance , Repetitive Sequences, Nucleic Acid , Superoxide Dismutase/genetics , Thermus/chemistry , Thermus/genetics , Ultraviolet RaysABSTRACT
Arabidopsis thaliana (Arabidopsis) is unique among plant model organisms in having a small genome (130-140 Mb), excellent physical and genetic maps, and little repetitive DNA. Here we report the sequence of chromosome 2 from the Columbia ecotype in two gap-free assemblies (contigs) of 3.6 and 16 megabases (Mb). The latter represents the longest published stretch of uninterrupted DNA sequence assembled from any organism to date. Chromosome 2 represents 15% of the genome and encodes 4,037 genes, 49% of which have no predicted function. Roughly 250 tandem gene duplications were found in addition to large-scale duplications of about 0.5 and 4.5 Mb between chromosomes 2 and 1 and between chromosomes 2 and 4, respectively. Sequencing of nearly 2 Mb within the genetically defined centromere revealed a low density of recognizable genes, and a high density and diverse range of vestigial and presumably inactive mobile elements. More unexpected is what appears to be a recent insertion of a continuous stretch of 75% of the mitochondrial genome into chromosome 2.
Subject(s)
Arabidopsis/genetics , Chromosome Mapping , DNA, Plant , Genes, Plant , Cell Nucleus/genetics , Centromere , Evolution, Molecular , Gene Duplication , Genes, Plant/physiology , Mitochondria/genetics , Molecular Sequence Data , Plant Proteins/genetics , Plant Proteins/physiology , Sequence Analysis, DNAABSTRACT
Studies on a feline model of MPS VI demonstrated a marked osteopenia in iliac crest bone samples from young adult animals with fewer, finer trabeculae. In the absence of significant differences in bone remodeling, this was considered due to defects in endochondral ossification and the formation of fewer trabeculae. Cell-level bone formation was normal despite the presence of vacuolated osteoblasts. Affected animals had vacuolated osteocytes in larger lacunae. Cats of the same age who had received a bone marrow transplant 12 months prior as young kittens, had significantly more trabecular bone with thicker trabeculae. The presence of smaller osteocyte lacunae in these animals as compared to their untreated MPS VI cats appeared to be a direct effect of bone marrow transplantation and a useful parameter to monitor its efficacy.
