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PubMed2005

Parasite genomes.

The availability of genome sequences and the associated transcriptome and proteome mapping projects has revolutionised research in the field of parasitology. As more parasite species are sequenced, comparative and phylogenetic comparisons are improving the quality of gene prediction and annotation. Genome sequences of parasites are also providing important data sets for understanding parasite biology and identifying new vaccine candidates and drug targets. We review some of the preliminary conclusions from examination of parasite genome sequences and discuss some of the bioinformatics approaches taken in this analysis.

Animals↗
PubMed2006

Modeling methanogenesis with a genome-scale metabolic reconstruction of Methanosarcina barkeri.

We present a genome-scale metabolic model for the archaeal methanogen Methanosarcina barkeri. We characterize the metabolic network and compare it to reconstructions from the prokaryotic, eukaryotic and archaeal domains. Using the model in conjunction with constraint-based methods, we simulate the metabolic fluxes and resulting phenotypes induced by different environmental and genetic conditions. This represents the first large-scale simulation of either a methanogen or an archaeal species. Model predictions are validated by comparison to experimental growth measurements and phenotypes of M. barkeri on different substrates. The predicted growth phenotypes for wild type and mutants of the methanogenic pathway have a high level of agreement with experimental findings. We further examine the efficiency of the energy-conserving reactions in the methanogenic pathway, specifically the Ech hydrogenase reaction, and determine a stoichiometry for the nitrogenase reaction. This work demonstrates that a reconstructed metabolic network can serve as an analysis platform to predict cellular phenotypes, characterize methanogenic growth, improve the genome annotation and further uncover the metabolic characteristics of methanogenesis.

Genome, Bacterial↗
PubMed2002

Parallel identification of new genes in Saccharomyces cerevisiae.

Short open reading frames (ORFs) occur frequently in primary genome sequence. Distinguishing bona fide small genes from the tens of thousands of short ORFs is one of the most challenging aspects of genome annotation. Direct experimental evidence is often required. Here we use a combination of expression profiling and mass spectrometry to verify the independent transcription of 138 and the translation of 50 previously nonannotated genes in the Saccharomyces cerevisiae genome. Through combined evidence, we propose the addition of 62 new genes to the genome and provide experimental support for the inclusion of 10 previously identified genes.

Amino Acid Sequence↗
PubMed2004

Functional genomics approaches in arthritis.

The post-genomic era of functional genomics and target validation will allow us to narrow the bridge between clinically correlative data and causative data for complex diseases, such as arthritis, for which the etiological agent remains elusive. The availability of human and other annotated genome sequences, and parallel developments of new technologies that allow analysis of minute amounts of human and animal cells (peripheral blood cells and infiltrating cells) and tissues (synovium and cartilage) under different pathophysiological conditions, has facilitated high-throughput gene mining approaches that can generate vast amounts of clinically correlative data. Characterizing some of the correlative/causative genes will require reverting to the hypothesis-driven, low throughput method of complementary experimental biology using genomic approaches as a tool. This will include in silico gene expression arrays, genome-wide scans, comparative genomics using various animal models (such as rodents and zebrafish), bioinformatics and a team of well trained translational scientists and physicians. For the first time, the "genomic tools" will allow us to analyze small amounts of surgical samples (such as needle biopsies) and clinical samples in the context of the whole genome. Preliminary genomic analysis in osteoarthritis has already resurrected the debate on the semantic issues in the definition of inflammation. Further analyses will not only facilitate the development of unbiased hypotheses at the molecular level, but also assist us in the identification and characterization of novel targets and disease markers for pharmacological intervention, gene therapy, and diagnosis.

Animals↗
PubMed1999

Prediction of potential GPI-modification sites in proprotein sequences.

Glycosylphosphatidylinositol (GPI) lipid anchoring is a common posttranslational modification known mainly from extracellular eukaryotic proteins. Attachment of the GPI moiety to the carboxyl terminus (omega-site) of the polypeptide follows after proteolytic cleavage of a C-terminal propeptide. For the first time, a new prediction technique locating potential GPI-modification sites in precursor sequences has been applied for large-scale protein sequence database searches. The composite prediction function (with separate parametrisation for metazoan and protozoan proteins) consists of terms evaluating both amino acid type preferences at sequence positions near a supposed omega-site as well as the concordance with general physical properties encoded in multi-residue correlation within the motif sequence. The latter terms are especially successful in rejecting non-appropriate sequences from consideration. The algorithm has been validated with a self-consistency and two jack-knife tests for the learning set of fully annotated sequences from the SWISS-PROT database as well as with a newly created database "big-Pi" (more than 300 GPI-motif mutations extracted from original literature sources). The accuracy of predicting the effect of mutations in the GPI sequence motif was above 83 %. Lists of potential precursor proteins which are non-annotated in SWISS-PROT and SPTrEMBL are presented on the WWW-page http://www.embl-heidelberg.de/beisenha/gpi/gpi_p rediction. html The algorithm has been implemented in the prototype software "big-Pi predictor" which may find application as a genome annotation and target selection tool.

Algorithms↗
PubMed2002

Online genomics facilities in the new millennium.

The review begins by providing a brief typology of biological databases on the Internet, illustrated by examples of the most influential resources of each kind. We then take an insider look at one typical on-line genomic resource -- the yeast genome database hosted at the Munich Information Center for Protein Sequences (MIPS) -- and explain how and why it has evolved from a basic sequence repository to a multidomain knowledge base. The role of community efforts in curating and annotating genome data is discussed. The crucial role of data integration and interoperability in developing next-generation genomic facilities is underscored.

Animals↗
PubMed2005

Functional genomics, new tools in malaria research.

The mosquito-transmitted unicellular parasite Plasmodium falciparum, the agent of malaria disease, still causes more than one million deaths every year in the tropical and subtropical areas of the world. New intervention strategies are needed to contrast the insurgence of resistance to effective drugs and insecticides. The complete annotated genomes of the human parasite P. falciparum and the rodent model P. yoelii is now available thus providing a prediction of their possible gene products. This makes feasible the application of functional genomics to malaria research with the final goal of providing a complete survey of Plasmodium life cycle. Genome-wide approaches to the study of transcriptome or proteome were successfully applied to malaria parasite with the promise for new drug and vaccine candidates in the next future.

Animals↗
PubMed2026

High-Quality Genome Assembly, Metabolome, Pangenome, and Metabolic Models of Megasphaera hexanoica KCCM 43214T.

Megasphaera hexanoica KCCM 43214T, isolated from cow rumen, is capable of producing medium-chain carboxylic acids such as hexanoate and octanoate. In this study, we present a high-quality genome assembly, along with intracellular metabolomic profiling and pangenomic analysis. Illumina sequencing generated 2.3 Gbp from 15,293,634 reads with a GC content of 49.5%, while PacBio HiFi sequencing produced 331.5 Mbp across 45,266 reads, with an average read length of 7,323 bp and a HiFi read N50 of 8,214 bp. Hybrid assembly of short and long reads resulted in a single 2.88 Mbp contig, containing 2,835 protein-coding genes. Genome-scale metabolic models were constructed to evaluate its metabolic capabilities under specific growth conditions. Intracellular metabolomic analysis of cells grown in medium containing fructose and lactate revealed key metabolic activities associated with chain elongation. Pangenomic analysis across nine annotated genomes identified 6,721 orthologous genes using OrthoMCL, emphasizing the genetic and functional diversity within the Megasphaera genus. This dataset offers valuable insights into the metabolism and biotechnological potential of M. hexanoica KCCM 43214T.

Metabolome↗
PubMed2025

Oogenesis and germinal bed morphology of the brown anole (A. sagrei).

BACKGROUND: The brown anole is a model species of the genus Anolis, a squamate (encompassing lizards and snakes) group widely studied in evolutionary, behavioral, and developmental biology. Full genome annotation, the establishment of gene editing techniques, and comprehensive description of reproductive tract morphology and embryogenesis in this species, has laid the foundation for functional studies. However, analysis of brown anole oogenesis is still required and vital to optimize genome modification, mutant line establishment, and analyses of the evolution of reproductive developmental mechanisms. RESULTS: Here, we characterize ovary morphology and gametogenesis in the female brown anole, A. sagrei using brightfield imaging, microCT, histology staining, electron microscopy, and confocal imaging. We define 10 stages of oocyte maturation which commences inside the oogonial nest within the germinal bed and concludes with the mature follicle ready to ovulate based on follicle size, yolk-acquisition, and follicular, cellular, and basement membrane architecture. CONCLUSIONS: We describe the complete oogenesis of the brown anole in 10 stages and report that oogenesis is highly conserved within iguanids, a suborder of lizards. With our staging framework, we lay the foundation for functional studies of oogenesis and optimized gene-editing.

Journal Article↗
PubMed2006

Bioinformatic analysis of an unusual gene-enzyme relationship in the arginine biosynthetic pathway among marine gamma proteobacteria: implications concerning the formation of N-acetylated intermediates in prokaryotes.

BACKGROUND: The N-acetylation of L-glutamate is regarded as a universal metabolic strategy to commit glutamate towards arginine biosynthesis. Until recently, this reaction was thought to be catalyzed by either of two enzymes: (i) the classical N-acetylglutamate synthase (NAGS, gene argA) first characterized in Escherichia coli and Pseudomonas aeruginosa several decades ago and also present in vertebrates, or (ii) the bifunctional version of ornithine acetyltransferase (OAT, gene argJ) present in Bacteria, Archaea and many Eukaryotes. This paper focuses on a new and surprising aspect of glutamate acetylation. We recently showed that in Moritella abyssi and M. profunda, two marine gamma proteobacteria, the gene for the last enzyme in arginine biosynthesis (argH) is fused to a short sequence that corresponds to the C-terminal, N-acetyltransferase-encoding domain of NAGS and is able to complement an argA mutant of E. coli. Very recently, other authors identified in Mycobacterium tuberculosis an independent gene corresponding to this short C-terminal domain and coding for a new type of NAGS. We have investigated the two prokaryotic Domains for patterns of gene-enzyme relationships in the first committed step of arginine biosynthesis. RESULTS: The argH-A fusion, designated argH(A), and discovered in Moritella was found to be present in (and confined to) marine gamma proteobacteria of the Alteromonas- and Vibrio-like group. Most of them have a classical NAGS with the exception of Idiomarina loihiensis and Pseudoalteromonas haloplanktis which nevertheless can grow in the absence of arginine and therefore appear to rely on the arg(A) sequence for arginine biosynthesis. Screening prokaryotic genomes for virtual argH-X 'fusions' where X stands for a homologue of arg(A), we retrieved a large number of Bacteria and several Archaea, all of them devoid of a classical NAGS. In the case of Thermus thermophilus and Deinococcus radiodurans, the arg(A)-like sequence clusters with argH in an operon-like fashion. In this group of sequences, we find the short novel NAGS of the type identified in M. tuberculosis. Among these organisms, at least Thermus, Mycobacterium and Streptomyces species appear to rely on this short NAGS version for arginine biosynthesis. CONCLUSION: The gene-enzyme relationship for the first committed step of arginine biosynthesis should now be considered in a new perspective. In addition to bifunctional OAT, nature appears to implement at least three alternatives for the acetylation of glutamate. It is possible to propose evolutionary relationships between them starting from the same ancestral N-acetyltransferase domain. In M. tuberculosis and many other bacteria, this domain evolved as an independent enzyme, whereas it fused either with a carbamate kinase fold to give the classical NAGS (as in E. coli) or with argH as in marine gamma proteobacteria. Moreover, there is an urgent need to clarify the current nomenclature since the same gene name argA has been used to designate structurally different entities. Clarifying the confusion would help to prevent erroneous genomic annotation.

Acetylation↗
PubMed2026

Whole-genome sequencing reveals hidden antimicrobial resistance genes in phenotypically susceptible probiotic candidate lactic acid bacteria.

Phenotypic assays commonly used to evaluate probiotic safety may fail to detect clinically relevant antimicrobial resistance (AMR), potentially allowing genetically concerning strains to appear acceptable based on MIC testing alone. To explore this issue, we applied whole-genome sequencing (WGS) to three lactic acid bacteria (LAB) isolates previously identified as probiotic candidates based on acid and bile tolerance, antagonism against enteric pathogens, and biofilm formation in vitro: Lactiplantibacillus plantarum L25F and L22F (from pigs) and Ligilactobacillus salivarius AF2319 (from a chicken). Genome annotation identified extensive repertoires of probiotic-associated genes (46-47 per strain) linked to stress tolerance, adhesion, immunomodulation, and quorum sensing, supporting functional potential. The two L. plantarum strains exhibited broader predicted metabolic capacities than L. salivarius AF2319. However, genomic analysis revealed acquired AMR genes with complex genotype-phenotype relationships not fully apparent from phenotypic testing. The L. plantarum strains harbored lnu(A) (99.79% identity) on extrachromosomal DNA, conferring the L-phenotype (lincomycin resistance, clindamycin susceptibility); clindamycin MICs (1 mg/L) were concordant with this genotype, though lincomycin MICs were not determined. L. salivarius AF2319 carried tet(M), tet(L), and erm(C) (99.48%, 99.49%, and 99.45% identity by ResFinder, respectively) on extrachromosomal DNA; notably, the erythromycin MIC (1 mg/L) was precisely at the EFSA breakpoint (≤ 1 mg/L), representing borderline genotype-phenotype discordance potentially due to silent gene expression. Under current EFSA QPS criteria, these acquired ARGs would preclude all three strains from approval as probiotic feed additives despite favorable functional profiles, underscoring the indispensable role of WGS-based AMR gene detection in modern probiotic safety evaluation.

Probiotics↗
PubMed2004

MaGIC: a program to generate targeted marker sets for genome-wide association studies.

High-throughput genotyping technologies such as DNA pooling and DNA microarrays mean that whole-genome screens are now practical for complex disease gene discovery using association studies. Because it is currently impractical to use all available markers, a subset is typically selected on the basis of required saturation density. Restricting markers to those within annotated genomic features of interest (e.g., genes or exons) or within feature-rich regions, reduces workload and cost while retaining much information. We have designed a program (MaGIC) that exploits genome assembly data to create lists of markers correlated with other genomic features. Marker lists are generated at a user-defined spacing and can target features with a user-defined density. Maps are in base pairs or linkage disequilibrium units (LDUs) as derived from the International HapMap data, which is useful for association studies and fine-mapping. Markers may be selected on the basis of heterozygosity and source database, and single nucleotide polymorphism (SNP) markers may additionally be selected on the basis of validation status. The import function means the method can be used for any genomic features such as housekeeping genes, long interspersed elements (LINES), or Alu repeats in humans, and is also functional for other species with equivalent data. The program and source code is freely available at http://cogent.iop.kcl.ac.uk/MaGIC.cogx.

Algorithms↗
PubMed2025

Chromosome-level genome assembly and annotation of Spinibarbus caldwelli.

Spinibarbus caldwelli is an economically important freshwater species within the Cyprinidae family, abundant in the middle and lower reaches of the Yangtze River and its adjacent basins. As a promising species suitable for aquaculture in southern China, the lack of genomic resources has hampered the genetic breeding and conservation. Here, we release a chromosome-level genome assembly for S. caldwelli using PacBio HiFi long-reads, Illumina short-reads, and Hi-C sequencing data. The final genome assembly is 1.77 Gb in size, with a contig N50 of 24.27 Mb. Using Hi-C scaffolding, 99.14% of the contigs were successfully anchored to 50 chromosomes, resulting in a scaffold N50 of 35.29 Mb. The final genome assembly shows a BUSCO completeness of 98.27%. The assembled genome contains 49.41% repetitive sequences and 51,505 predicted genes, 90.83% of which have been functionally annotated. This genome provides a genetic basis for S. caldwelli, facilitating the exploration of Cyprinid phylogeny, genetic improvement, and conservation efforts.

Animals↗
PubMed2004

Has the yo-yo stopped? An assessment of human protein-coding gene number.

Since the identification of approximately 25,000 proteins from the draft human genome assembly in 2001, estimates of the total have oscillated between 30,000 and 70,000. The recently announced genome closure has not generated a consensus gene count despite this being a key parameter for many areas of biology including drug target discovery and characterization of the human proteome. Contrary to earlier predictions of constitutive under-detection for eukaryotic genes, the latest model organism updates have produced minor increases in the worm but fly and yeast gene numbers have decreased. The postdraft, precompletion interval has produced large increases in human transcript coverage, continuous improvements in genome assembly and refinements in automated genomic annotation. Notably these enhancements have resulted in an Ensembl human protein-coding gene number of 22,184, a decrease of 1862 since the first release. Longitudinal database surveys indicate that redundancy-reduced human mRNA and protein collections are flattening out at approximately 28,000, although Ensembl maps approximately 20,000 known sequences. Observations suggest high-throughput cloning projects are predominantly extending known genes or sampling new splice forms and novel protein discovery has slowed to a trickle. The hypothesis that substantial numbers of short proteins remain experimentally and computationally undetected in mammalian genomes is neither supported by sequence data nor by the extensive homology between mouse and human proteins. Aggregating the independent annotations for complete transcripts from seven completed human chromosomes extrapolates to approximately 25,000 genes. The inclusion of partial putative genes would increase this to above 30,000 but recent data suggest these represent predominantly nonprotein-coding transcripts. Mass spectrometry-based proteomics has already verified more than 10% of human genes but has not identified significant numbers of unpredicted proteins. The available data are thus converging to a basal protein-coding gene number well below 30,000, which could even be as low as 25,000.

Chromosomes, Human↗
PubMed2006

Xanthusbase: adapting wikipedia principles to a model organism database.

xanthusBase (http://www.xanthusbase.org) is the official model organism database (MOD) for the social bacterium Myxococcus xanthus. In many respects, M.xanthus represents the pioneer model organism (MO) for studying the genetic, biochemical, and mechanistic basis of prokaryotic multicellularity, a topic that has garnered considerable attention due to the significance of biofilms in both basic and applied microbiology research. To facilitate its utility, the design of xanthusBase incorporates open-source software, leveraging the cumulative experience made available through the Generic Model Organism Database (GMOD) project, MediaWiki (http://www.mediawiki.org), and dictyBase (http://www.dictybase.org), to create a MOD that is both highly useful and easily navigable. In addition, we have incorporated a unique Wikipedia-style curation model which exploits the internet's inherent interactivity, thus enabling M.xanthus and other myxobacterial researchers to contribute directly toward the ongoing genome annotation.

Databases, Nucleic Acid↗
PubMed2003

From genome to enzyme: analysis of key glycolytic and oxidative pentose-phosphate pathway enzymes in the cyanobacterium Synechocystis sp. PCC 6803.

Activities of glucokinase, glucose-6-phosphate dehydrogenase, 6-phosphogluconate dehydrogenase, phosphoglucose isomerase, phosphofructokinase (PFK), enolase, pyruvate kinase (PK) and phosphoenolpyruvate (PEP) carboxylase were determined in extracts of photoautotrophic, mixotrophic, and heterotrophic cultures of Synechocystis sp. PCC 6803. Annotated genomes of Synechocystis sp. PCC 6803 and Anabaena sp. PCC 7120 were analyzed for the respective predicted physical properties of each enzyme investigated here. Enzymatic activity was largely unaffected by nutritional mode, with the exception of glucokinase and PK whose activities were significantly elevated in heterotrophic cultures of Synechocystis sp. PCC 6803. PFK activity was insensitive to bacterial PFK-A (allosteric) effectors such as PEP, implying that Synechocystis PFK should be classified as a PFK-B (non-allosteric). Immunoblot and kinetic studies indicated that irrespective of nutritional mode, the Synechocystis PK corresponds to a PK-A (AMP activated) rather than PK-F (fructose-1,6-bisphosphate activated).

Anabaena↗
PubMed2004

Mapping of microbial pathways through constrained mapping of orthologous genes.

We present a novel computer algorithm for mapping biological pathways from one prokaryotic genome to another. The algorithm maps genes in a known pathway to their homologous genes (if any) in a target genome that is most consistent with (a) predicted orthologous gene relationship, (b) predicted operon structures, and (c) predicted co-regulation relationship of operons. Mathematically, we have formulated this problem as a constrained minimum spanning tree problem (called a Steiner network problem), and demonstrated that this formulation has the desired property through applications. We have solved this mapping problem using a combinatorial optimization algorithm, with guaranteed global optimality. We have implemented this algorithm as a computer program, called PMAP. Our test results on pathway mapping are highly encouraging -- we have mapped a number of pathways of H. influenzae, B. subtilis, H. pylori, and M. tuberculosis to E. coli using P-MAP, whose homologous pathways in E coli. are known and hence the mapping accuracy could be checked. We have then mapped known E. coli pathways in the EcoCyc database to the newly sequenced organism Synechococcus sp WH8102, and predicted 158 Synechococcus pathways. Detailed analyses on the predicted pathways indicate that P-MAP's mapping results are consistent with our general knowledge about (local) pathways. We believe that P-MAP will be a useful tool for microbial genome annotation projects and inference of individual microbial pathways.

Algorithms↗
PubMed2003

Evaluation of annotation strategies using an entire genome sequence.

MOTIVATION: Genome-wide functional annotation either by manual or automatic means has raised considerable concerns regarding the accuracy of assignments and the reproducibility of methodologies. In addition, a performance evaluation of automated systems that attempt to tackle sequence analyses rapidly and reproducibly is generally missing. In order to quantify the accuracy and reproducibility of function assignments on a genome-wide scale, we have re-annotated the entire genome sequence of Chlamydia trachomatis (serovar D), in a collaborative manner. RESULTS: We have encoded all annotations in a structured format to allow further comparison and data exchange and have used a scale that records the different levels of potential annotation errors according to their propensity to propagate in the database due to transitive function assignments. We conclude that genome annotation may entail a considerable amount of errors, ranging from simple typographical errors to complex sequence analysis problems. The most surprising result of this comparative study is that automatic systems might perform as well as the teams of experts annotating genome sequences.

Amino Acid Sequence↗