Biomedical subjects

P Morozov

Publications and source records attributed to P Morozov.

6 recordsLinked to original sources

PubMed2001

A chemosensory gene family encoding candidate gustatory and olfactory receptors in Drosophila.

A novel family of candidate gustatory receptors (GRs) was recently identified in searches of the Drosophila genome. We have performed in situ hybridization and transgene experiments that reveal expression of these genes in both gustatory and olfactory neurons in adult flies and larvae. This gene family is likely to encode both odorant and taste receptors. We have visualized the projections of chemosensory neurons in the larval brain and observe that neurons expressing different GRs project to discrete loci in the antennal lobe and subesophageal ganglion. These data provide insight into the diversity of chemosensory recognition and an initial view of the representation of gustatory information in the fly brain.

Animal Structures↗

PubMed2001

Markov chain Monte Carlo computation of confidence intervals for substitution-rate variation in proteins.

We suggest a method implemented in a computer program, immodestly dubbed TSUNAMI, that allows us to compare two homologous protein subfamilies with respect to the distribution of substitution rates along sequences. This study furthers our earlier work on a wavelet model of rate variation (1). The current approach allows sensitive detection of subtle discordances in the selection patterns between two protein subfamilies. In addition to performing fast computation of the maximum posterior probability estimates of the relative substitution rates, the method can select the most appropriate number of wavelet parameters for a particular dataset. TSUNAMI is based on a Markov chain Monte Carlo technique, and appears to be more applicable to larger datasets than is the full likelihood-based approach.

Amino Acid Substitution↗

PubMed2000

Using BLAST for identifying gene and protein names in journal articles.

We describe a system which automatically identifies gene and protein names in journal articles, an important and non-trivial first step in knowledge extraction of protein and gene actions. Our system uses a database of gene and protein names and is based on BLAST [Altschul et al., Nucleic Acids Res. 25 (1997) 3389-3402], a popular tool for DNA and protein sequence comparison. We describe a method that consists of mapping sequences of text characters into sequences of nucleotides that can be processed by BLAST. We demonstrate that this approach is feasible: the system matches gene and protein names with a recall of 78.8% and a precision of 71.7%, which includes names that are not part of the system database. An analysis of the results suggests techniques that can be used to improve performance further.

Algorithms↗

PubMed2000

A new method for characterizing replacement rate variation in molecular sequences. Application of the Fourier and wavelet models to Drosophila and mammalian proteins.

We propose models for describing replacement rate variation in genes and proteins, in which the profile of relative replacement rates along the length of a given sequence is defined as a function of the site number. We consider here two types of functions, one derived from the cosine Fourier series, and the other from discrete wavelet transforms. The number of parameters used for characterizing the substitution rates along the sequences can be flexibly changed and in their most parameter-rich versions, both Fourier and wavelet models become equivalent to the unrestricted-rates model, in which each site of a sequence alignment evolves at a unique rate. When applied to a few real data sets, the new models appeared to fit data better than the discrete gamma model when compared with the Akaike information criterion and the likelihood-ratio test, although the parametric bootstrap version of the Cox test performed for one of the data sets indicated that the difference in likelihoods between the two models is not significant. The new models are applicable to testing biological hypotheses such as the statistical identity of rate variation profiles among homologous protein families. These models are also useful for determining regions in genes and proteins that evolve significantly faster or slower than the sequence average. We illustrate the application of the new method by analyzing human immunoglobulin and Drosophilid alcohol dehydrogenase sequences.

Alcohol Dehydrogenase↗

PubMed1996

GEOMETRY: a software package for nucleotide sequence analysis using statistical geometry in sequence space.

GEOMETRY is a software package for the analysis of nucleotide sequences using the method of statistical geometry in sequence space. The package consists of programs performing estimation of the average geometry of sequence quartets, analysis of positional variability and computer simulation of parallel and tree-like sequence divergence with user-defined parameters. It provides an independent tool for evaluation of the reliability of conventional phylogenetic trees and calibration of the time of sequence divergence. GEOMETRY may be of interest for all scientists engaged in the study of molecular phylogeny. The package is available by anonymous FTP from ftp.bionet.nsk.su, directory /incoming/molevol/geom.exe, and will be available from EMBL file server (URL: http://@www.ebi.ac.uk)

Algorithms↗

PubMed1991

[The French-language works of Wladimir Serbski].

The only thing for which Serbski is known nowadays is that, following his death in 1917, the Institute of Medico-Legal Psychiatry in Moscow was named after him. It was here, half a century later, that was made the diagnosis of sluggish schizophrenia from the observation of numerous dissidents. Yet the biography of this pupil and successor of Korsakov is that of a liberal, who championned the cause of human rights under the ancient regime, and in particular those of the mentally ill. His theoretical writings, published in the medico-psychological Annales in 1903-1904, are a contribution to the critique made by the French speaking school of the extended conception of dementia praecox developed by Kraepelin in 1899, and taken up by Bleuler in 1911, with his description of the group of schizophrenias. Serbski does not then deserve the opprobrium which the proper condemnation of the use of psychiatry for political issues has inflicted up on his name.

Delusions↗