bluuebunny/crossref_metadata_2025 huggingface dataset:
Analysis ofE.colipromoter recognition problem in dinucleotide feature space
Authors: Rani T. Sobha , Bhavani S. Durga , Bapi Raju S.
Published: January 2007

Motivation: Patterns in the promoter sequences within a species are known to be conserved but there exist many exceptions to this rule which makes the promoter recognition a complex problem. Although many complex feature extraction schemes coupled with several classifiers have been proposed for promoter recognition in the current literature, the problem is still open.

Results: A dinucleotide global feature extraction method is proposed for the recognition of sigma-70 promoters in Escherichia coli in this article. The positive data set consists of sigma-70 promoters with known transcription starting points which are part of regulonDB and promec databases. Four different kinds of negative data sets are considered, two of them biological sets (Gordon et al., 2003) and the other two synthetic data sets. Our results reveal that a single-layer perceptron using dinucleotide features is able to achieve an accuracy of 80% against a background of biological non-promoters and 96% for random data sets. A scheme for locating the promoter regions in a given genome sequence is proposed. A deeper analysis of the data set shows that there is a bifurcation of the data set into two distinct classes, a majority class and a minority class. Our results point out that majority class constituting the majority promoter and the majority non-promoter signal is linearly separable. Also the minority class is linearly separable. We further show that the feature extraction and classification methods proposed in the paper are generic enough to be applied to the more complex problem of eucaryotic promoter recognition. We present Drosophila promoter recognition as a case study.

Availability:  http://202.41.85.117/htmfiles/faculty/tsr/tsr.html

Contact:  tsrcs@uohyd.ernet.in
BioWeka—extending the Weka framework for bioinformatics
Authors: Gewehr Jan E. , Szugat Martin , Zimmer Ralf
Published: January 2007

Summary: Given the growing amount of biological data, data mining methods have become an integral part of bioinformatics research. Unfortunately, standard data mining tools are often not sufficiently equipped for handling raw data such as e.g. amino acid sequences. One popular and freely available framework that contains many well-known data mining algorithms is the Waikato Environment for Knowledge Analysis (Weka). In the BioWeka project, we introduce various input formats for bioinformatics data and bioinformatics methods like alignments to Weka. This allows users to easily combine them with Weka's classification, clustering, validation and visualization facilities on a single platform and therefore reduces the overhead of converting data between different data formats as well as the need to write custom evaluation procedures that can deal with many different programs. We encourage users to participate in this project by adding their own components and data formats to BioWeka.

Availability: The software, documentation and tutorial are available at http://www.bioweka.org.

Contact:  support@bioweka.org
DP-Bind: a web server for sequence-based prediction of DNA-binding residues in DNA-binding proteins
Authors: Hwang Seungwoo , Gou Zhenkun , Kuznetsov Igor B.
Published: January 2007

Summary: This article describes DP-Bind, a web server for predicting DNA-binding sites in a DNA-binding protein from its amino acid sequence. The web server implements three machine learning methods: support vector machine, kernel logistic regression and penalized logistic regression. Prediction can be performed using either the input sequence alone or an automatically generated profile of evolutionary conservation of the input sequence in the form of PSI-BLAST position-specific scoring matrix (PSSM). PSSM-based kernel logistic regression achieves the accuracy of 77.2%, sensitivity of 76.4% and specificity of 76.6%. The outputs of all three individual methods are combined into a consensus prediction to help identify positions predicted with high level of confidence.

Availability: Freely available at http://lcg.rit.albany.edu/dp-bind

Contact:  IKuznetsov@albany.edu

Supplementry information:  http://lcg.rit.albany.edu/dp-bind/dpbind_supplement.html
Identifying clusters of functionally related genes in genomes
Authors: Yi Gangman , Sze Sing-Hoi , Thon Michael R.
Published: January 2007

Motivation: An increasing body of literature shows that genomes of eukaryotes can contain clusters of functionally related genes. Most approaches to identify gene clusters utilize microarray data or metabolic pathway databases to find groups of genes on chromosomes that are linked by common attributes. A generalized method that can find gene clusters regardless of the mechanism of origin would provide researchers with an unbiased method for finding clusters and studying the evolutionary forces that give rise to them.

Results: We present an algorithm to identify gene clusters in eukaryotic genomes that utilizes functional categories defined in graph-based vocabularies such as the Gene Ontology (GO). Clusters identified in this manner need only have a common function and are not constrained by gene expression or other properties. We tested the algorithm by analyzing genomes of a representative set of species. We identified species-specific variation in percentage of clustered genes as well as in properties of gene clusters including size distribution and functional annotation. These properties may be diagnostic of the evolutionary forces that lead to the formation of gene clusters.

Availability: A software implementation of the algorithm and example output files are available at http://fcg.tamu.edu/C_Hunter/.

Contact:  mthon@tamu.edu

Supplementary information: Supplementary data are available at Bioinformatics online.
Quaternionic periodicity transform: an algebraic solution to the tandem repeat detection problem
Authors: Brodzik Andrzej K.
Published: January 2007

Motivation: One of the main tasks of DNA sequence analysis is identification of repetitive patterns. DNA symbol repetitions play a key role in a number of applications, including prediction of gene and exon locations, identification of diseases, reconstruction of human evolutionary history and DNA forensics.

Results: A new approach towards identification of tandem repeats in DNA sequences is proposed. The approach is a refinement of previously considered method, based on the complex periodicity transform. The refinement is obtained, among others, by mapping of DNA symbols to pure quaternions. This mapping results in an enhanced, symbol-balanced sensitivity of the transform to DNA patterns, and an unambiguous threshold selection criterion. Computational efficiency of the transform is further improved, and coupling of the computation with the period value is removed, thereby facilitating parallel implementation of the algorithm. Additionally, a post-processing stage is inserted into the algorithm, enabling unambiguous display of results in a convenient graphical format. Comparison of the quaternionic periodicity transform with two well-known pattern detection techniques shows that the new approach is competitive with these two techniques in detection of exact and approximate repeats.

Supplementary information: Supplementary data are available at Bioinformatics online.
The ESID Online Database network
Authors: Guzman D. , Veit D. , Knerr V. , Kindle G. , Gathmann B. , Eades-Perner A. M. , Grimbacher B.
Published: January 2007

Summary: Primary immunodeficiencies (PIDs) belong to the group of rare diseases. The European Society for Immunodeficiencies (ESID), is establishing an innovative European patient and research database network for continuous long-term documentation of patients, in order to improve the diagnosis, classification, prognosis and therapy of PIDs. The ESID Online Database is a web-based system aimed at data storage, data entry, reporting and the import of pre-existing data sources in an enterprise business-to-business integration (B2B). The online database is based on Java 2 Enterprise System (J2EE) with high-standard security features, which comply with data protection laws and the demands of a modern research platform.

Availability: The ESID Online Database is accessible via the official website (http://www.esid.org/).

Contact:  b.grimbacher@medsch.ucl.ac.uk

Supplementary information: Supplementary data are available at Bioinformatics online.
Inferring pairwise regulatory relationships from multiple time series datasets
Authors: Shi Yanxin , Mitchell Tom , Bar-Joseph Ziv
Published: January 2007

Motivation: Time series expression experiments have emerged as a popular method for studying a wide range of biological systems under a variety of conditions. One advantage of such data is the ability to infer regulatory relationships using time lag analysis. However, such analysis in a single experiment may result in many false positives due to the small number of time points and the large number of genes. Extending these methods to simultaneously analyze several time series datasets is challenging since under different experimental conditions biological systems may behave faster or slower making it hard to rely on the actual duration of the experiment.

Results: We present a new computational model and an associated algorithm to address the problem of inferring time-lagged regulatory relationships from multiple time series expression experiments with varying (unknown) time-scales. Our proposed algorithm uses a set of known interacting pairs to compute a temporal transformation between every two datasets. Using this temporal transformation we search for new interacting pairs. As we show, our method achieves a much lower false-positive rate compared to previous methods that use time series expression data for pairwise regulatory relationship discovery. Some of the new predictions made by our method can be verified using other high throughput data sources and functional annotation databases.

Availability: Matlab implementation is available from the supporting website: http://www.cs.cmu.edu/~yanxins/regulation_inference/index.html

Contact:  zivbj@cs.cmu.edu

Supplementary information: Supplementary data are available at Bioinformatics online.
Improving the accuracy of transmembrane protein topology prediction using evolutionary information
Authors: Jones David T.
Published: January 2007

Motivation: Many important biological processes such as cell signaling, transport of membrane-impermeable molecules, cell–cell communication, cell recognition and cell adhesion are mediated by membrane proteins. Unfortunately, as these proteins are not water soluble, it is extremely hard to experimentally determine their structure. Therefore, improved methods for predicting the structure of these proteins are vital in biological research. In order to improve transmembrane topology prediction, we evaluate the combined use of both integrated signal peptide prediction and evolutionary information in a single algorithm.

Results: A new method (MEMSAT3) for predicting transmembrane protein topology from sequence profiles is described and benchmarked with full cross-validation on a standard data set of 184 transmembrane proteins. The method is found to predict both the correct topology and the locations of transmembrane segments for 80% of the test set. This compares with accuracies of 62–72% for other popular methods on the same benchmark. By using a second neural network specifically to discriminate transmembrane from globular proteins, a very low overall false positive rate (0.5%) can also be achieved in detecting transmembrane proteins.

Availability: An implementation of the described method is available both as a web server (http://www.psipred.net) and as downloadable source code from http://bioinf.cs.ucl.ac.uk/memsat. Both the server and source code files are free to non-commercial users. Benchmark and training data are also available from http://bioinf.cs.ucl.ac.uk/memsat.

Contact:  dtj@cs.ucl.ac.uk
Peak selection from MALDI-TOF mass spectra using ant colony optimization
Authors: Ressom H. W. , Varghese R. S. , Drake S. K. , Hortin G. L. , Abdel-Hamid M. , Loffredo C. A. , Goldman R.
Published: January 2007

Motivation: Due to the large number of peaks in mass spectra of low-molecular-weight (LMW) enriched sera, a systematic method is needed to select a parsimonious set of peaks to facilitate biomarker identification. We present computational methods for matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) spectral data preprocessing and peak selection. In particular, we propose a novel method that combines ant colony optimization (ACO) with support vector machines (SVM) to select a small set of useful peaks.

Results: The proposed hybrid ACO-SVM algorithm selected a panel of eight peaks out of 228 candidate peaks from MALDI-TOF spectra of LMW enriched sera. An SVM classifier built with these peaks achieved 94% sensitivity and 100% specificity in distinguishing hepatocellular carcinoma from cirrhosis in a blind validation set of 69 samples. Area under the receiver operating characteristic (ROC) curve was 0.996. The classification capability of these peaks is compared with those selected by the SVM-recursive feature elimination method.

Availability: Supplementary material and MATLAB scripts to implement the methods described in this article are available at http://microarray.georgetown.edu/web/files/bioinf.htm

Contact:  hwr@georgetown.edu

Supplementary information: Supplementary data are available at Bioinformatics online.
SMotif: a server for structural motifs in proteins
Authors: Pugalenthi Ganesan , Suganthan P. N. , Sowdhamini R. , Chakrabarti Saikat
Published: January 2007

Summary: SMotif is a server that identifies important structural segments or motifs for a given protein structure(s) based on conservation of both sequential as well as important structural features such as solvent inaccessibility, secondary structural content, hydrogen bonding pattern and residue packing. This server also provides three-dimensional orientation patterns of the identified motifs in terms of inter-motif distances and torsion angles. These motifs may form the common core and therefore, can also be employed to design and rationalize protein engineering and folding experiments.

Availability: SMotif server is available via the URL http://caps.ncbs.res.in/SMotif/index.html.

Contact:  chakraba@mail.nih.gov, mini@ncbs.res.in or EPNSugan@ntu.edu.sg

Supplementary information: Supplementary data are available at Bioinformatics online.
Automatic recognition and annotation of gene expression patterns of fly embryos
Authors: Zhou Jie , Peng Hanchuan
Published: January 2007

Motivation: Gene expression patterns obtained by in situ mRNA hybridization provide important information about different genes during Drosophila embryogenesis. So far, annotations of these images are done by manually assigning a subset of anatomy ontology terms to an image. This time-consuming process depends heavily on the consistency of experts.

Results: We develop a system to automatically annotate a fruitfly's embryonic tissue in which a gene has expression. We formulate the task as an image pattern recognition problem. For a new fly embryo image, our system answers two questions: (1) Which stage range does an image belong to? (2) Which annotations should be assigned to an image? We propose to identify the wavelet embryo features by multi-resolution 2D wavelet discrete transform, followed by min-redundancy max-relevance feature selection, which yields optimal distinguishing features for an annotation. We then construct a series of parallel bi-class predictors to solve the multi-objective annotation problem since each image may correspond to multiple annotations.

Supplementary information: The complete annotation prediction results are available at: http://www.cs.niu.edu/~jzhou/papers/fruitfly and http://research.janelia.org/peng/proj/fly_embryo_annotation/. The datasets used in experiments will be available upon request to the correspondence author.

Contact:  jzhou@cs.niu.edu and pengh@janelia.hhmi.org
Compressed suffix tree—a basis for genome-scale sequence analysis
Authors: Välimäki Niko , Gerlach Wolfgang , Dixit Kashyap , Mäkinen Veli
Published: January 2007

Summary: Suffix tree is one of the most fundamental data structures in string algorithms and biological sequence analysis. Unfortunately, when it comes to implementing those algorithms and applying them to real genomic sequences, often the main memory size becomes the bottleneck. This is easily explained by the fact that while a DNA sequence of length n from alphabet Σ = {A, C, G, T } can be stored in n log |Σ|= 2n bits, its suffix tree occupies O(n log n) bits. In practice, the size difference easily reaches factor 50.

We provide an implementation of the compressed suffix tree very recently proposed by Sadakane (Theory of Computing Systems, in press). The compressed suffix tree occupies space proportional to the text size, i.e. O(n log} | Σ |) bits, and supports all typical suffix tree operations with at most log n factor slowdown. Our experiments show that, e.g. on a 10 MB DNA sequence, the compressed suffix tree takes 10% of the space of normal suffix tree. Typical operations are slowed down by factor 60.

Availability: The C++ implementation under GNU license is available at http://www.cs.helsinki.fi/group/suds/cst/. An example program implementing a typical pattern discovery task is included. Experimental results in this note correspond to version 0.95.

Contact:  vmakinen@cs.helsinki.fi
AphidBase: a database for aphid genomic resources
Authors: Gauthier Jean-Pierre , Legeai Fabrice , Zasadzinski Alain , Rispe Claude , Tagu Denis
Published: January 2007

AphidBase aims to (i) store recently acquired genomic resources on aphids and (ii) compare them to other insect resources as functional annotation tools. For that, the Drosophila melanogaster genome has been loaded in the database using the GMOD open source software for a comparison with the 17 069 pea aphid unique transcripts (contigs) and the 13 639 gene transcripts of the Anopheles gambiae. Links to FlyBase and A.gambiae Entrez databases allow a rapid characterization of the putative functions of the aphid sequences. Text mining of the D.melanogaster literature was performed to construct a network of co-cited gene or protein names, which should facilitate functional annotation of aphid homolog sequences. AphidBase represents one of the first genomic databases for a hemipteran insect.

Availability:  http://w3.rennes.inra.fr/AphidBase

Contact:  denis.tagu@rennes.inra.fr, jean-pierre.gauthier@rennes.infra.fr
Comparison of human protein–protein interaction maps
Authors: Futschik Matthias E. , Chaurasia Gautam , Herzel Hanspeter
Published: January 2007

Motivation: Large-scale mappings of protein–protein interactions have started to give us new views of the complex molecular mechanisms inside a cell. After initial projects to systematically map protein interactions in model organisms such as yeast, worm and fly, researchers have begun to focus on the mapping of the human interactome. To tackle this enormous challenge, different approaches have been proposed and pursued. While several large-scale human protein interaction maps have recently been published, their quality remains to be critically assessed.

Results: We present here a first comparative analysis of eight currently available large-scale maps with a total of over 10 000 unique proteins and 57 000 interactions included. They are based either on literature search, orthology or by yeast-two-hybrid assays. Comparison reveals only a small, but statistically significant overlap. More importantly, our analysis gives clear indications that all interaction maps imply considerable selection and detection biases. These results have to be taken into account for future assembly of the human interactome.

Availability: An integrated human interaction network called Unified Human Interactome (UniHI) is made publicly accessible at http://www.mdc-berlin.de/unihi.

Contact:  m.futschik@biologie.hu-berlin.de

Supplementary information: Supplementary data are available at Bioinformatics online.
APOPTO-CELL—a simulation tool and interactive database for analyzing cellular susceptibility to apoptosis
Authors: Huber Heinrich J. , Rehm Markus , Plchut Martin , Düssmann Heiko , Prehn Jochen H. M.
Published: January 2007

We have developed a web service that provides a comprehensive analysis of the susceptibility of cells to undergo apoptosis in response to an activation of the mitochondrial apoptotic pathway. Based on ordinary differential equations, (pre-determined) protein concentrations and release kinetics of mitochondrial pro-apoptotic factors, a network of 52 reactions and 19 reaction partners can be employed as a tool to display temporal protein profiles, to identify key regulatory proteins and to determine critical threshold concentrations required for the execution of apoptosis in HeLa cancer cells or other cell types. The web service also provides an interactive database function for the deposition of cell-type-specific quantitative data. In addition, the web service provides an output that can be compared directly to experimental results obtained from real-time single-cell experiments, making this a widely applicable systems biology tool for apoptosis and cancer researchers.

Availability:  http://systemsbiology.rcsi.ie/apopto-cell.html

Contact:  mrehm@rcsi.ie

Supplementary information: Supplementary data are available at Bioinformatics online.
LFM-Pro: a tool for detecting significant local structural sites in proteins
Authors: Sacan Ahmet , Ozturk Ozgur , Ferhatosmanoglu Hakan , Wang Yusu
Published: January 2007

Motivation: The rapidly growing protein structure repositories have opened up new opportunities for discovery and analysis of functional and evolutionary relationships among proteins. Detecting conserved structural sites that are unique to a protein family is of great value in identification of functionally important atoms and residues. Currently available methods are computationally expensive and fail to detect biologically significant local features.

Results: We propose Local Feature Mining in Proteins (LFM-Pro) as a framework for automatically discovering family-specific local sites and the features associated with these sites. Our method uses the distance field to backbone atoms to detect geometrically significant structural centers of the protein. A feature vector is generated from the geometrical and biochemical environment around these centers. These features are then scored using a statistical measure, for their ability to distinguish a family of proteins from a background set of unrelated proteins, and successful features are combined into a representative set for the protein family. The utility and success of LFM-Pro are demonstrated on trypsin-like serine proteases family of proteins and on a challenging classification dataset via comparison with DALI. The results verify that our method is successful both in identifying the distinctive sites of a given family of proteins, and in classifying proteins using the extracted features.

Availability: The software and the datasets are freely available for academic research use at http://bioinfo.ceng.metu.edu.tr/Pub/LFMPro

Contact:  ahmet@ceng.metu.edu.tr, ozturk@cse.ohiostate.edu,hakan@cse.ohiostate.edu,yusu@cse.ohiostate.edu
A computational system to select candidate genes for complex human traits
Authors: Gaulton Kyle J. , Mohlke Karen L. , Vision Todd J.
Published: January 2007

Motivation: Identification of the genetic variation underlying complex traits is challenging. The wealth of information publicly available about the biology of complex traits and the function of individual genes permits the development of informatics-assisted methods for the selection of candidate genes for these traits.

Results: We have developed a computational system named CAESAR that ranks all annotated human genes as candidates for a complex trait by using ontologies to semantically map natural language descriptions of the trait with a variety of gene-centric information sources. In a test of its effectiveness, CAESAR successfully selected 7 out of 18 (39%) complex human trait susceptibility genes within the top 2% of ranked candidates genome-wide, a subset that represents roughly 1% of genes in the human genome and provides sufficient enrichment for an association study of several hundred human genes. This approach can be applied to any well-documented mono- or multi-factorial trait in any organism for which an annotated gene set exists.

Availability: CAESAR scripts and test data can be downloaded from http://visionlab.bio.unc.edu/caesar/

Contact:  kgaulton@email.unc.edu
Modeling nonlinearity in dilution design microarray data
Authors: Zheng Xiuwen , Huang Hung-Chung , Li Wenyuan , Liu Peng , Li Quan-Zhen , Liu Ying
Published: January 2007

Motivation: Dilution design (Mixed tissue RNA) has been utilized by some researchers to evaluate and assess the performance of multiple microarray platforms. Current microarray data analysis approaches assume that the quantified signal intensities are linearly related to the expression of the corresponding genes in the sample. However, there are sources of nonlinearity in microarray expression measurements. Such nonlinearity study in the expressions of the RNA mixtures provides a new way to analyze gene expression data, and we argue that the nonlinearity can reveal novel information for microarray data analysis. Therefore, we proposed a statistical model, called proportion model, which is based on the linear regression analysis. To approximately quantify the nonlinearity in the dilution design, a new calibration, beta ratio (BR) was derived from the proportion model. Furthermore, a new adjusted fold change (adj-FC) was proposed to predict the true FC without nonlinearity, in particular for large FC.

Results: We applied our method to one microarray dilution dataset. The experimental results indicated that, to some extent, there are global biases comparing with the linear assumption for the significant genes. Further analysis of those highly expressed genes with significant nonlinearity revealed some promising results, e.g. ‘poison’ effect was discovered for some genes in RNA mixtures. The adj-FCs of those genes with ‘poison’ effect, indicate that the nonlinearity can be also caused by the inherent feature of the genes besides signal noise and technical variation. Moreover, when percentage of overlapping genes (POG) was used as a cross-platform consistency measure, adj-FC outperformed simple fold change to show that Affymetrix and Illumina platforms are consistent.

Availability: The R codes which implements all described methods, and some Supplementary material, are freely available from http://www.utdallas.edu/~ying.liu/BetaRatio.htm

Contact: ying.liu@utdallas.edu

Supplementary information: Supplementary data are available at Bioinformatics online.
Identifying bacterial genes and endosymbiont DNA with Glimmer
Authors: Delcher Arthur L. , Bratke Kirsten A. , Powers Edwin C. , Salzberg Steven L.
Published: January 2007

Motivation: The Glimmer gene-finding software has been successfully used for finding genes in bacteria, archæa and viruses representing hundreds of species. We describe several major changes to the Glimmer system, including improved methods for identifying both coding regions and start codons. We also describe a new module of Glimmer that can distinguish host and endosymbiont DNA. This module was developed in response to the discovery that eukaryotic genome sequencing projects sometimes inadvertently capture the DNA of intracellular bacteria living in the host.

Results: The new methods dramatically reduce the rate of false-positive predictions, while maintaining Glimmer's 99% sensitivity rate at detecting genes in most species, and they find substantially more correct start sites, as measured by comparisons to known and well-curated genes. We show that our interpolated Markov model (IMM) DNA discriminator correctly separated 99% of the sequences in a recent genome project that produced a mixture of sequences from the bacterium Prochloron didemni and its sea squirt host, Lissoclinum patella.

Availability: Glimmer is OSI Certified Open Source and available at http://cbcb.umd.edu/software/glimmer

Contact:  adelcher@umiacs.umd.edu
R/qtlbim: QTL with Bayesian Interval Mapping in experimental crosses
Authors: Yandell Brian S. , Mehta Tapan , Banerjee Samprit , Shriner Daniel , Venkataraman Ramprasad , Moon Jee Young , Neely W. Whipple , Wu Hao , von Smith Randy , Yi Nengjun
Published: January 2007

Summary: R/qtlbim is an extensible, interactive environment for the Bayesian Interval Mapping of QTL, built on top of R/qtl (Broman et al., 2003), providing Bayesian analysis of multiple interacting quantitative trait loci (QTL) models for continuous, binary and ordinal traits in experimental crosses. It includes several efficient Markov chain Monte Carlo (MCMC) algorithms for evaluating the posterior of genetic architectures, i.e. the number and locations of QTL, their main and epistatic effects and gene–environment interactions. R/qtlbim provides extensive informative graphical and numerical summaries, and model selection and convergence diagnostics of the MCMC output, illustrated through the vignette, example and demo capabilities of R (R Development Core Team 2006).

Availability: The package is freely available from cran.r-project.org.

Contact:  byandell@wisc.edu or nyi@ms.soph.uab.edu
A new versatile database created for geneticists and breeders to link molecular and phenotypic data in perennial crops: theAppleBreed DataBase
Authors: Antofie A. , Lateur M. , Oger R. , Patocchi A. , Durel C. E. , Van de Weg W. E.
Published: January 2007

Objective:  AppleBreed DataBase (DB) aims to store genotypic and phenotypic data from multiple pedigree verified plant populations (crosses, breeding selections and commercial cultivars) so that they are easily accessible for geneticists and breeders. It will help in elucidating the genetics of economically important traits, in identifying molecular markers associated with agronomic traits, in allele mining and in choosing the best parental cultivars for breeding. It also provides high traceability of data over generations, years and localities. AppleBreed DB could serve as a generic database design for other perennial crops with long economic lifespans, long juvenile periods and clonal propagation.

Results:  AppleBreed DB is organized as a relational database. The core element is the GENOTYPE entity, which has two sub-classes at the physical level: TREE and DNA-SAMPLE. This approach facilitates all links between plant material, phenotypic and molecular data. The entities TREE, DNA-SAMPLE, PHENOTYPE and MOLECULAR DATA allow multi-annual observations to be stored as individual samples of individual trees, even if the nature of these observations differs greatly (e.g. molecular data on parts of the apple genome, physico-chemical measurements of fruit quality traits, and evaluation of disease resistance). AppleBreed DB also includes synonyms for cultivars and pedigrees. Finally, it can be loaded and explored through the web, and comes with tools to present basic statistical overviews and with validation procedures for phenotypic and marker data to certify data quality.

AppleBreed DB was developed initially as a tool for scientists involved in apple genetics within the framework of the European project, ‘High-quality Disease Resistance in Apples for Sustainable Agriculture’ (HiDRAS), but it is also applicable to many other perennial crops.

Contact:  oger@cra.wallonie.be
Assessment of phylogenomic and orthology approaches for phylogenetic inference
Authors: Dutilh B. E. , van Noort V. , van der Heijden R. T. J. M. , Boekhout T. , Snel B. , Huynen M. A.
Published: January 2007

Motivation: Phylogenomics integrates the vast amount of phylogenetic information contained in complete genome sequences, and is rapidly becoming the standard for reliably inferring species phylogenies. There are, however, fundamental differences between the ways in which phylogenomic approaches like gene content, superalignment, superdistance and supertree integrate the phylogenetic information from separate orthologous groups. Furthermore, they all depend on the method by which the orthologous groups are initially determined. Here, we systematically compare these four phylogenomic approaches, in parallel with three approaches for large-scale orthology determination: pairwise orthology, cluster orthology and tree-based orthology.

Results: Including various phylogenetic methods, we apply a total of 54 fully automated phylogenomic procedures to the fungi, the eukaryotic clade with the largest number of sequenced genomes, for which we retrieved a golden standard phylogeny from the literature. Phylogenomic trees based on gene content show, relative to the other methods, a bias in the tree topology that parallels convergence in lifestyle among the species compared, indicating convergence in gene content.

Conclusions: Complete genomes are no guarantee for good or even consistent phylogenies. However, the large amounts of data in genomes enable us to carefully select the data most suitable for phylogenomic inference. In terms of performance, the superalignment approach, combined with restrictive orthology, is the most successful in recovering a fungal phylogeny that agrees with current taxonomic views, and allows us to obtain a high-resolution phylogeny. We provide solid support for what has grown to be a common practice in phylogenomics during its advance in recent years.

Contact:  dutilh@cmbi.ru.nl

Supplementary information: Supplementary data are available at Bioinformatics online.
Inositol Polyphosphate 5-Phosphatases 1 and 2 Are Required for Regulating Seedling Growth
Authors: Gunesekera Bhadra , Torabinejad Javad , Robinson Jamille , Gillaspy Glenda E.
Published: January 2007

Signals can be perceived and amplified at the cell membrane by receptors coupled to the production of a variety of second messengers, including myoinositol 1,4,5-trisphosphate [Ins(1,4,5)P3]. The myoinositol polyphosphate 5-phosphatases (5PTases; EC 3.1.3.56) comprise a large protein family that hydrolyzes 5-phosphates from a variety of myoinositol phosphate (InsP) and phosphoinositide phosphate (PtdInsP) substrates. Arabidopsis thaliana has 15 genes encoding 5PTases. Biochemical analyses of a subgroup of 5PTase enzymes suggest that these enzymes have both overlapping and unique substrate preferences. Ectopic expression of these genes in transgenic plants can reduce Ins(1,4,5)P3 levels and alter abscisic acid (ABA) signaling. To further explore the function of 5PTases in signaling, we have identified and characterized T-DNA insertional mutants for 5PTase1 and 5PTase2 and produced a double mutant. When grown in the dark, the seeds from these mutants germinate faster than wild-type seeds and the mutant seedlings have longer hypocotyls than wild-type seedlings. Seeds from these mutant lines also demonstrate an increase in sensitivity to ABA. These changes in early seedling growth are accompanied by mass increases in Ins(1,4,5)P3, but not by changes in endogenous ABA content. By labeling the endogenous myoinositol pool in 5ptase1 and 5ptase2 mutants, we detected increases in Ins(1,4,5)P3 and a decrease in PtdIns, PtdIns(4)P, and phosphatidylinositol (4,5) bisphosphate. Taken together, these data indicate that the At5PTase1 and At5PTase2 genes have nonredundant roles in hydrolyzing inositol second-messenger substrates and that regulation of Ins(1,4,5)P3 levels is important during germination and early seedling development.
Developmental Analysis of Maize Endosperm Proteome Suggests a Pivotal Role for Pyruvate Orthophosphate Dikinase
Authors: Méchin Valérie , Thévenot Claudine , Le Guilloux Martine , Prioul Jean-Louis , Damerval Catherine
Published: January 2007

Although the morphological steps of maize (Zea mays) endosperm development are well described, very little is known concerning the coordinated accumulation of the numerous proteins involved. Here, we present a proteomic study of maize endosperm development. The accumulation pattern of 409 proteins at seven developmental stages was examined. Hierarchical clustering analysis allowed four main developmental profiles to be recognized. Comprehensive investigation of the functions associated with clusters resulted in a consistent picture of the developmental coordination of cellular processes. Early stages, devoted to cellularization, cell division, and cell wall deposition, corresponded to maximal expression of actin, tubulins, and cell organization proteins, of respiration metabolism (glycolysis and tricarboxylic acid cycle), and of protection against reactive oxygen species. An important protein turnover, which is likely associated with the switch from growth and differentiation to storage, was also suggested from the high amount of proteases. A relative increase of abundance of the glycolytic enzymes compared to tricarboxylic acid enzymes is consistent with the recent demonstration of anoxic conditions during starch accumulation in the endosperm. The specific late-stage accumulation of the pyruvate orthophosphate dikinase may suggest a critical role of this enzyme in the starch-protein balance through inorganic pyrophosphate-dependent restriction of ADP-glucose synthesis in addition to its usually reported influence on the alanine-aromatic amino acid synthesis balance.
An IRE-Like AGC Kinase Gene, MtIRE, Has Unique Expression in the Invasion Zone of Developing Root Nodules in Medicago truncatula
Authors: Pislariu Catalina I. , Dickstein Rebecca
Published: January 2007

The AGC protein kinase family (cAMP-dependent protein kinases A, cGMP-dependent protein kinases G, and phospholipid-dependent protein kinases C) have important roles regulating growth and development in animals and fungi. They are activated via lipid second messengers by 3-phosphoinositide-dependent protein kinase coupling lipid signals to phosphorylation of the AGC kinases. These phosphorylate downstream signal transduction protein targets. AGC kinases are becoming better studied in plants, especially in Arabidopsis (Arabidopsis thaliana), where specific AGC kinases have been shown to have key roles in regulating growth signal pathways. We report here the isolation and characterization of the first AGC kinase gene identified in Medicago truncatula, MtIRE. It was cloned by homology with the Arabidopsis INCOMPLETE ROOT HAIR ELONGATION (IRE) gene. Semiquantitative reverse transcription-polymerase chain reaction analysis shows that, unlike its Arabidopsis counterpart, MtIRE is not expressed in uninoculated roots, but is expressed in root systems that have been inoculated with Sinorhizobium meliloti and are developing root nodules. MtIRE expression is also found in flowers. Expression analysis of a time course of nodule development and of nodulating root systems of many Medicago nodulation mutants shows MtIRE expression correlates with infected cell maturation during nodule development. During the course of these experiments, nine Medicago nodulation mutants, including sli and dnf1 to 7 mutants, were evaluated for the first time for their microscopic nodule phenotype using S. meliloti constitutively expressing lacZ. Spatial localization of a pMtIRE-gusA transgene in transformed roots of composite plants showed that MtIRE expression is confined to the proximal part of the invasion zone, zone II, found in indeterminate nodules. This suggests MtIRE is useful as an expression marker for this region of the invasion zone.
Interactions among PIN-FORMED and P-Glycoprotein Auxin Transporters in Arabidopsis
Authors: Blakeslee Joshua J. , Bandyopadhyay Anindita , Lee Ok Ran , Mravec Jozef , Titapiwatanakun Boosaree , Sauer Michael , Makam Srinivas N. , Cheng Yan , Bouchard Rodolphe , Adamec Jiří , Geisler Markus , Nagashima Akitomo , Sakai Tatsuya , Martinoia Enrico , Friml Jiří , Peer Wendy Ann , Murphy Angus S.
Published: January 2007

Directional transport of the phytohormone auxin is established primarily at the point of cellular efflux and is required for the establishment and maintenance of plant polarity. Studies in whole plants and heterologous systems indicate that PIN-FORMED (PIN) and P-glycoprotein (PGP) transport proteins mediate the cellular efflux of natural and synthetic auxins. However, aromatic anion transport resulting from PGP and PIN expression in nonplant systems was also found to lack the high level of substrate specificity seen in planta. Furthermore, previous reports that PGP19 stabilizes PIN1 on the plasma membrane suggested that PIN–PGP interactions might regulate polar auxin efflux. Here, we show that PGP1 and PGP19 colocalized with PIN1 in the shoot apex in Arabidopsis thaliana and with PIN1 and PIN2 in root tissues. Specific PGP–PIN interactions were seen in yeast two-hybrid and coimmunoprecipitation assays. PIN–PGP interactions appeared to enhance transport activity and, to a greater extent, substrate/inhibitor specificities when coexpressed in heterologous systems. By contrast, no interactions between PGPs and the AUXIN1 influx carrier were observed. Phenotypes of pin and pgp mutants suggest discrete functional roles in auxin transport, but pin pgp mutants exhibited phenotypes that are both additive and synergistic. These results suggest that PINs and PGPs characterize coordinated, independent auxin transport mechanisms but also function interactively in a tissue-specific manner.
In Vivo Participation of Red Chlorophyll Catabolite Reductase in Chlorophyll Breakdown
Authors: Pružinská Adriana , Anders Iwona , Aubry Sylvain , Schenk Nicole , Tapernoux-Lüthi Esther , Müller Thomas , Kräutler Bernhard , Hörtensteiner Stefan
Published: January 2007

A central reaction of chlorophyll breakdown, porphyrin ring opening of pheophorbide a to the primary fluorescent chlorophyll catabolite (pFCC), requires pheophorbide a oxygenase (PAO) and red chlorophyll catabolite reductase (RCCR), with red chlorophyll catabolite (RCC) as a presumably PAO-bound intermediate. In subsequent steps, pFCC is converted to different fluorescent chlorophyll catabolites (FCCs) and nonfluorescent chlorophyll catabolites (NCCs). Here, we show that RCCR-deficient Arabidopsis thaliana accumulates RCC and three RCC-like pigments during senescence, as well as FCCs and NCCs. We also show that the stereospecificity of Arabidopsis RCCR is defined by a small protein domain and can be reversed by a single Phe-to-Val exchange. Exploiting this feature, we prove the in vivo participation of RCCR in chlorophyll breakdown. After complementation of RCCR mutants with RCCRs exhibiting alternative specificities, patterns of chlorophyll catabolites followed the specificity of complementing RCCRs. Light-dependent leaf cell death observed in different RCCR-deficient lines strictly correlated with the accumulation of RCCs and the release of singlet oxygen, and PAO induction preceded lesion formation. These findings suggest that RCCR absence causes leaf cell death as a result of the accumulation of photodynamic RCC. We conclude that RCCR (together with PAO) is required for the detoxification of chlorophyll catabolites and discuss the biochemical role(s) for this enzyme.
NAC Transcription Factors, NST1 and NST3, Are Key Regulators of the Formation of Secondary Walls in Woody Tissues ofArabidopsis
Authors: Mitsuda Nobutaka , Iwase Akira , Yamamoto Hiroyuki , Yoshida Masato , Seki Motoaki , Shinozaki Kazuo , Ohme-Takagi Masaru
Published: January 2007

Wood is formed by the successive addition of secondary xylem, which consists of cells with a conspicuously thickened secondary wall composed mainly of lignin and cellulose. Several genes involved in lignin and cellulose biosynthesis have been characterized, but the factors that regulate the formation of secondary walls in woody tissues remain to be identified. In this study, we show that plant-specific transcription factors, designated NAC SECONDARY WALL THICKENING PROMOTING FACTOR1 (NST1) and NST3, are key regulators of the formation of secondary walls in woody tissues of Arabidopsis thaliana. In nst1-1 nst3-1 double knockout plants, the secondary wall thickenings in interfascicular fibers and secondary xylem, except for vascular vessels, were completely suppressed without affecting formation of cells destined to be woody tissues. Conversely, as shown previously for NST1, overexpression of NST3 induced ectopic secondary wall thickenings in various aboveground tissues. Furthermore, the expression of chimeric repressors derived from NST1 and NST3 suppressed secondary wall thickenings in the presumptive interfascicular fibers. Because putative orthologs of NST1 and NST3 are present in the genome of poplar, our results suggest that they are also key regulators of the formation of secondary walls in woody plants and could be used as a tool for the genetic engineering of wood and its derivatives.
TheArabidopsis irregular xylem8Mutant Is Deficient in Glucuronoxylan and Homogalacturonan, Which Are Essential for Secondary Cell Wall Integrity
Authors: Persson Staffan , Caffall Kerry Hosmer , Freshour Glenn , Hilley Matthew T. , Bauer Stefan , Poindexter Patricia , Hahn Michael G. , Mohnen Debra , Somerville Chris
Published: January 2007

The secondary cell wall in higher plants consists mainly of cellulose, lignin, and xylan and is the major component of biomass in many species. The Arabidopsis thaliana  irregular xylem8 (irx8) mutant is dwarfed and has a significant reduction in secondary cell wall thickness. IRX8 belongs to a subgroup of glycosyltransferase family 8 called the GAUT1-related gene family, whose members include GAUT1, a homogalacturonan galacturonosyltransferase, and GAUT12 (IRX8). Here, we use comparative cell wall analyses to show that the irx8 mutant contains significantly reduced levels of xylan and homogalacturonan. Immunohistochemical analyses confirmed that the level of xylan was significantly reduced in the mutant. Structural fingerprinting of the cell wall polymers further revealed that irx8 is deficient in glucuronoxylan. To explore the biological function of IRX8, we crossed irx8 with irx1 (affecting cellulose synthase 8). The homozygous irx1 irx8 exhibited severely dwarfed phenotypes, suggesting that IRX8 is essential for cell wall integrity during cellulose deficiency. Taken together, the data presented show that IRX8 affects the level of glucuronoxylan and homogalacturonan in higher plants and that IRX8 provides an important link between the xylan polymer and the secondary cell wall matrix and directly affects secondary cell wall integrity.
SLocus Genes and the Evolution of Self-Fertility inArabidopsis thaliana
Authors: Sherman-Broyles Sue , Boggs Nathan , Farkas Agnes , Liu Pei , Vrebalov Julia , Nasrallah Mikhail E. , Nasrallah June B.
Published: January 2007

Loss of self-incompatibility (SI) in Arabidopsis thaliana was accompanied by inactivation of genes required for SI, including S-LOCUS RECEPTOR KINASE (SRK) and S-LOCUS CYSTEINE-RICH PROTEIN (SCR), coadapted genes that constitute the SI specificity-determining S haplotype. Arabidopsis accessions are polymorphic for ΨSRK and ΨSCR, but it is unknown if the species harbors structurally different S haplotypes, either representing relics of ancestral functional and structurally heteromorphic S haplotypes or resulting from decay concomitant with or subsequent to the switch to self-fertility. We cloned and sequenced the S haplotype from C24, in which self-fertility is due solely to S locus inactivation, and show that this haplotype was produced by interhaplotypic recombination. The highly divergent organization and sequence of the C24 and Columbia-0 (Col-0) S haplotypes demonstrate that the A. thaliana S locus underwent extensive structural remodeling in conjunction with a relaxation of selective pressures that once preserved the integrity and linkage of coadapted SRK and SCR alleles. Additional evidence for this process was obtained by assaying 70 accessions for the presence of C24- or Col-0–specific sequences. Furthermore, analysis of SRK and SCR polymorphisms in these accessions argues against the occurrence of a selective sweep of a particular allele of SCR, as previously proposed.