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Niels Jahn

Publications and source records attributed to Niels Jahn.

4 recordsLinked to original sources
PubMed2006

tuple_plot: fast pairwise nucleotide sequence comparison with noise suppression.

SUMMARY: The program tuple_plot identifies and visualizes local similarities between two genomic sequences, typically 100 kb or longer, by applying the well-known dotplot principle. A dictionary of sequence words built from the input sequences serves to construct a task-specific expectancy model that is used to attribute significance values to pairwise word hits. The dictionary-based approach allows fast computation, the computation time scaling to O(N log N), depending on the size of the input sequences. The proposed scoring scheme appreciably increases the signal-to-noise ratio and may help to improve other word-based sequence comparison approaches. AVAILABILITY: tuple_plot is available at http://genome.fli-leibniz.de/software.html and may be used under GNU public license.

Algorithms↗
PubMed2005

Single-nucleotide polymorphisms in NAGNAG acceptors are highly predictive for variations of alternative splicing.

Aberrant or modified splicing patterns of genes are causative for many human diseases. Therefore, the identification of genetic variations that cause changes in the splicing pattern of a gene is important. Elsewhere, we described the widespread occurrence of alternative splicing at NAGNAG acceptors. Here, we report a genomewide screen for single-nucleotide polymorphisms (SNPs) that affect such tandem acceptors. From 121 SNPs identified, we extracted 64 SNPs that most likely affect alternative NAGNAG splicing. We demonstrate that the NAGNAG motif is necessary and sufficient for this type of alternative splicing. The evolutionarily young NAGNAG alleles, as determined by the comparison with the chimpanzee genome, exhibit the same biases toward intron phase 1 and single-amino acid insertion/deletions that were already observed for all human NAGNAG acceptors. Since 28% of the NAGNAG SNPs occur in known disease genes, they represent preferable candidates for a more-detailed functional analysis, especially since the splice relevance for some of the coding SNPs is overlooked. Against the background of a general lack of methods for identifying splice-relevant SNPs, the presented approach is highly effective in the prediction of polymorphisms that are causal for variations in alternative splicing.

Alleles↗
PubMed2004

Widespread occurrence of alternative splicing at NAGNAG acceptors contributes to proteome plasticity.

Splice acceptors with the genomic NAGNAG motif may cause NAG insertion-deletions in transcripts, occur in 30% of human genes and are functional in at least 5% of human genes. We found five significant biases indicating that their distribution is nonrandom and that they are evolutionarily conserved and tissue-specific. Because of their subtle effects on mRNA and protein structures, these splice acceptors are often overlooked or underestimated, but they may have a great impact on biology and disease.

Alternative Splicing↗