Biomedical subjects

Zanoni Dias

Publications and source records attributed to Zanoni Dias.

3 recordsLinked to original sources

PubMed2006

New strategy to detect single nucleotide polymorphisms.

A great effort has been made to identify and map a large set of single nucleotide polymorphisms. The goal is to determine human DNA variants that contribute most significantly to population variation in each trait. Different algorithms and software packages, such as PolyBayes and PolyPhred, have been developed to address this problem. We present strategies to detect single nucleotide polymorphisms, using chromatogram analysis and consensi of multiple aligned sequences. The algorithms were tested using HIV datasets, and the results were compared with those produced by PolyBayes and PolyPhred using the same dataset. Our algorithms produced significantly better results than these two software packages.

Algorithms↗

PubMed2006

Analysis of slipped sequences in EST projects.

Slippage is an important sequencing problem that can occur in EST projects. However, very few studies have addressed this. We propose three new methods to detect slippage artifacts: arithmetic mean method, geometric mean method, and echo coverage method. Each method is simple and has two different strategies for processing sequences: suffix and subsequence. Using the 291,689 EST sequences produced in the SUCEST project, we performed comparative tests between our proposed methods and the SUCEST method. The subsequence strategy is better than the suffix strategy, because it is not anchored at the end of the sequence, so it is more flexible to find slippage at the beginning of the EST. In a comparison with the SUCEST method, the advantage of our methods is that they do not discard the majority of the sequences marked as slippage, but instead only remove the slipped artifact from the sequence. Based on our tests the echo coverage method with subsequence strategy shows the best compromise between slippage detection and ease of calibration.

DNA Replication↗

PubMed2002

A lower bound on the reversal and transposition diameter.

One possible model to study genome evolution is to represent genomes as permutations of genes and compute distances based on the minimum number of certain operations (rearrangements) needed to transform one permutation into another. Under this model, the shorter the distance, the closer the genomes are. Two operations that have been extensively studied are the reversal and the transposition. A reversal is an operation that reverses the order of the genes on a certain portion of the permutation. A transposition is an operation that "cuts" a certain portion of the permutation and "pastes" it elsewhere in the same permutation. In this note, we show that the reversal and transposition distance of the signed permutation pi(n) = (-1 -2.-(n - 1)-n) with respect to the identity is left floor n/2 right floor + 2 for all n>or=3. We conjecture that this value is the diameter of the permutation group under these operations.

Computational Biology↗