Search results for "Base Sequence"

Specific roles of 5′ RNA secondary structures in stabilizing transcripts in chloroplasts

2005

RNA secondary structures, e.g. stem-loops that are often found at the 5' and 3' ends of mRNAs, are in many cases known to be crucial for transcript stability but their role in prolonging the lifetime of transcripts remains elusive. In this study we show for an essential RNA-stabilizing stem-loop at the 5' end of rbcL gene transcripts in Chlamydomonas that it neither prevents ribonucleases from binding to the RNA nor impedes their movement along the RNA strand. The stem-loop has a formative function in that it mediates folding of a short sequence around its base into a specific RNA conformation, consisting of a helical and single-stranded region, i.e. the real structure required for longevit…

New alleles and mutational events at 14 STR loci from different German populations.

2007

The molecular origin of DNA mutations and the mutation rates were analyzed at 14 short tandem repeat (STR) loci with samples from trio cases derived from 10 different German population samples. STR loci comprised of D2S1360, D3S1744, D4S2366, D5S2500, D6S474, D7S1517, D8S1132, D10S2325, D12S391, D18S51, D19S246, D20S480, D21S226, and D22S689. In a total of 488 meioses, 16 isolated genetic inconsistencies in 8 different STRs were observed, whereas no mutations were found at the other loci. The data of five mutations suggested the presence of silent or null alleles due to sequence variation in primer binding site. This could be confirmed for four suspected cases by the use of alternative prim…

Rapid evolution of translational control mechanisms in RNA genomes

1997

We have introduced 13 base substitutions into the coat protein gene of RNA bacteriophage MS2. The mutations, which are clustered ahead of the overlapping lysis cistron, do not change the amino acid sequence of the coat protein, but they disrupt a local hairpin, which is needed to control translation of the lysis gene. The mutations decreased the phage titer by four orders of magnitude but, upon passaging, the virus accumulated suppressor mutations that raised the fitness to almost wild-type level. Analysis of the pseudorevertants showed that the disruption of the local hairpin, controlling expression of the lysis gene, had apparently been so complete that its restoration by chance mutations…

Subrepeats result from regional DNA sequence conservation in tandem repeats in Chironomus telomeres

1990

Repeat units, widespread in eukaryotic genomes, are often partially or entirely built up of subrepeats. Homogenization between whole repeat units arranged in tandem usually can best be understood as a result of unequal crossing over. Such a mechanism is less plausible for maintaining similarities between subrepeats within a repeat unit when present in a regular array. In Chironomus telomeres, large blocks of tandemly repeated approximately 350 base-pair units contain two or three pairs of subrepeats with high mutual identities, embedded in linker DNA, non-repetitive within the repeat unit. Measurements of evolutionary base changes in two closely related species, Chironomus tentans and Chiro…

Forensics of birds of prey by DNA fingerprinting with 32P-labeled oligonucleotide probes.

1991

Paternity tests on confiscated families of eight species of birds of prey were carried out successfully by DNA fingerprinting with 32P-labeled oligonucleotide probes. Variations in the number of hybridized fragments, depending on the species of birds, are observed using the same probe, as well as differences of polymorphism by hybridizing the DNA samples with several oligonucleotide probes.

Genetic and phenotypic heterogeneity in two novel cases of Waardenburg syndrome type IV.

2009

Murine Cytomegalovirus Major Immediate-Early Enhancer Region Operating as a Genetic Switch in Bidirectional Gene Pair Transcription

2007

ABSTRACT Enhancers are defined as DNA elements that increase transcription when placed in any orientation relative to a promoter. The major immediate-early (MIE) enhancer region of murine cytomegalovirus is flanked by transcription units ie1/3 and ie2 , which are transcribed in opposite directions. We have addressed the fundamental mechanistic question of whether the enhancer synchronizes transcription of the bidirectional gene pair (synchronizer model) or whether it operates as a genetic switch, enhancing transcription of either gene in a stochastic alternation (switch model). Clonal analysis of cytokine-triggered, transcription factor-mediated MIE gene expression from latent viral genomes…

Retroposon insertions provide insights into deep lagomorph evolution.

2010

The homogenous mammalian order Lagomorpha comprises about 80 species in two families, Ochotonidae (pikas) and Leporidae (rabbits and hares). However, the phylogenetic relationships among leporids are controversial. Molecular data, particularly from mitochondrial sequences, give highly homoplasious signals. To resolve the controversy between mitochondrial and nuclear data, we analyzed genomic orthologous retroposon insertion sites, a virtually homoplasy-free marker system. From a differential screen of rabbit genomic data for intronic retroposon insertions of CSINE elements, we polymerase chain reaction-amplified and sequenced 11 retroposons in eight representative lagomorphs. We found three…

Nucleotide sequence of the unassigned reading frame urf a in the mitochondrial genome of three Schizosaccharomyces pombe strains.

1990

Sequence Variability and Sequence Evolution: An Explanation of Molecular Polymorphisms and Why Many Molecular Structures Can Be Preserved Although Th…

2010

The existence of many processes that regulate RNA expression poses a challenge to the idea that the cell is the culmination of a highly efficient interplay of individual proteins, each with specific, highly specialized functions. It will be demonstrated here the extent to which the cell may undergo evolutionary processes that also occur in the macrocosmos, specifically with reference to the rules of mutation and preservation. These molecular evolutionary processes could facilitate a better understanding of the development of molecular structures and the functioning of the cell and could give an explanation of the molecular polymorphisms and also explain why many molecular structures can be …