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Identification of nine human-specific frameshift mutations by comparative analysis of the human and the chimpanzee genome sequences.

MOTIVATION: The recent release of the draft sequence of the chimpanzee genome is an invaluable resource for finding genome-wide genetic differences that might explain phenotypic differences between humans and chimpanzees. AVAILABILITY: In this paper, we describe a simple procedure to identify potential human-specific frameshift mutations that occurred after the divergence of human and chimpanzee. The procedure involves collecting human coding exons bearing insertions or deletions compared with the chimpanzee genome and identification of homologs from other species, in support of the mutations being human-specific. Using this procedure, we identified nine genes, BASE, DNAJB3, FLJ33674, HEJ1, NTSR2, RPL13AP, SCGB1D4, WBSCR27 and ZCCHC13, that show human-specific alterations including truncations of the C-terminus. In some cases, the frameshift mutation results in gene inactivation or decay. In other cases, the altered protein seems to be functional. This study demonstrates that even the unfinished chimpanzee genome sequence can be useful in identifying modification of genes that are specific to the human lineage and, therefore, could potentially be relevant to the study of the acquisition of human-specific traits.

Amino Acid Sequence↗

Molecular genetics of schizophrenia: past, present and future.

Schizophrenia is a severe neuropsychiatric disorder with a polygenic mode of inheritance which is also governed by non-genetic factors. Candidate genes identified on the basis of biochemical and pharmacological evidence are being tested for linkage and association studies. Neurotransmitters, especially dopamine and serotonin have been widely implicated in its etiology. Genome scan of all human chromosomes with closely spaced polymorphic markers is being used for linkage studies. The completion and availability of the first draft of Human Genome Sequence has provided a treasure-trove that can be utilized to gain insight into the so far inaccessible regions of the human genome. Significant technological advances for identification of single nucleo-tide polymorphisms (SNPs) and use of microarrays have further strengthened research methodologies for genetic analysis of complex traits. In this review, we summarize the evolution of schizophrenia genetics from the past to the present, current trends and future direction of research.

Anticipation, Genetic↗

The circadian clock of the unicellular eukaryotic model organism Chlamydomonas reinhardtii.

The green unicellular alga Chlamydomonas reinhardtii, also called 'green yeast', emerged in the past years as a model organism for specific scientific questions such as chloroplast biogenesis and function, the composition of the flagella including its basal apparatus, or the mechanism of the circadian clock. Sequencing of its chloroplast and mitochondrial genomes have already been completed and a first draft of its nuclear genome has also been released recently. In C. reinhardtii several circadian rhythms are physiologically well characterized, and one of them has even been shown to operate in outer space. Circadian expression patterns of nuclear and plastid genes have been studied. The mode of regulation of these genes occurs at the transcriptional level, although there is also evidence for posttranscriptional control. A clock-controlled, phylogenetically conserved RNA-binding protein was characterized in this alga, which interacts with several mRNAs that all contain a common cis-acting motif. Its function within the circadian system is currently under investigation. This review summarizes the current state of the knowledge about the circadian system in C. reinhardtii and points out its potential for future studies.

Animals↗

DNA-based diagnosis of isolated sulfite oxidase deficiency by denaturing high-performance liquid chromatography.

Isolated sulfite oxidase deficiency is a rare autosomal recessive disease, characterized by severe neurological abnormalities, seizures, mental retardation, and dislocation of the ocular lenses, that often leads to death in infancy. There is a special demand for prenatal diagnosis, since no effective treatment is available for isolated sulfite oxidase deficiency. Until now, the cDNA sequence of the sulfite oxidase (SUOX) gene has been available, but the genomic sequence of the SUOX gene has not been published. In this study, we have performed a DNA-based diagnosis of isolated sulfite oxidase deficiency in a Chinese patient. To do so, we designed oligonucleotide primers for amplification of the predicted exons and intron-exon boundaries of the SUOX gene obtained from the completed draft version of the human genome. Using overlapping PCR products, we confirmed the flanking intronic sequences of the coding exons and that the entire 466-residue mature peptide is encoded by the last exon of the gene. We then performed mutation detection using denaturing high-performance liquid chromatography (DHPLC). The DHPLC chromatogram of exon 2b showed the presence of heteroduplex peaks only after mixing of the mutant DNA with the wild-type DNA, indicating the presence of a homozygous mutation. Direct DNA sequencing showed a homozygous base substitution at codon 160, changing the codon from CGG to CAG, which changes the amino acid from arginine to glutamine, i.e., R160Q. The DNA-based diagnosis of isolated sulfite oxidase deficiency will enable us to make an accurate determination of carrier status and to perform prenatal diagnosis of this disease. The availability of the genomic sequences of human genes from the completed draft human genome sequence will simplify the development of molecular genetic diagnoses of human diseases from peripheral blood DNA.

Child, Preschool↗

Transposable element (TE) display and rapid detection of TE insertion polymorphism in the Anopheles gambiae species complex.

Transposable element (TE) display was shown to be a highly specific and reproducible method of detecting the insertion sites of TEs in individuals of the African malaria mosquito, Anopheles gambiae, and its sibling species, A. arabiensis. Relatively high levels of insertion polymorphism were observed during the TE display of several families of miniature inverted-repeat TEs (MITEs) that have variable copy numbers. The genomic locations of selected insertion sites were identified by matching the sequences of their corresponding bands in a TE display gel to specific regions of the draft A. gambiae genome assembly. We discuss different scenarios in which TE display will provide powerful dominant and co-dominant genetic markers to study the behaviour of TEs in A. gambiae populations and to illustrate the complex population genetics of this intriguing disease vector. We suggest that TE display can also provide tools for a phylogenetic analysis of the A. gambiae complex.

Animals↗

Integrated analysis of the genome and the transcriptome by FANTOM.

The key to reliable annotation of a mammalian genome is broad characterisation of the transcriptional output, the transcriptome. FANTOM, the functional annotation of mouse cDNA, is a large-scale analysis of both the genome and the transcriptome of the mouse. In the early days of this work, the transcripts were characterised using our sophisticated methods. After the timely release of the first draft of mouse genome sequences, interesting information was obtained by its integration with these one-by-one annotations. Moreover, each transcript included its expression profile. Here, the two integrated annotation methods used by FANTOM are reviewed: one-by-one and categorised. One-by-one annotation refers to naming carried out based on well-known transcripts or its fragments using the top-down-style pipeline developed mostly by the FANTOM project. Categorised annotation, which refers to transcript grouping, not only helps naming of unknown transcripts, but will be the most utilised method for integration of the genome and the transcriptome from now on.

Abstracting and Indexing↗

Predicted ATP-binding cassette systems in the phytopathogenic mollicute Spiroplasma kunkelii.

Spiroplasma kunkelii is a cell wall-free, helical, and motile mycoplasma-like organism that causes corn stunt disease in maize. The bacterium has a compact genome with a gene set approaching the minimal complement necessary for cellular life and pathogenesis. A set of 21 ATP-binding cassette (ABC) domains was identified during the annotation of a draft S. kunkelii genome sequence. These 21 ABC domains are present in 18 predicted proteins, and are components of 16 functional systems, which account for 5% of the protein coding capacity of the S. kunkelii genome. Of the 16 systems, 11 are membrane-bound transporters, and two are cytosolic systems involved in DNA repair and the oxidative stress response; the genes for the remaining three hypothetical systems harbor nonsense and/or frameshift mutations, so their functional status is doubtful. Assembly of the 11 multicomponent transporters, and comparisons with other known systems permitted functional predictions for the S. kunkelii ABC transporter systems. These transporters convey a wide variety of substrates, and are critical for nutrient uptake, multidrug resistance, and perhaps virulence. Our findings provide a framework for functional characterization of the ABC systems in S. kunkelii.

ATP-Binding Cassette Transporters↗

Analysis of a human brain transcriptome map.

BACKGROUND: Genome wide transcriptome maps can provide tools to identify candidate genes that are over-expressed or silenced in certain disease tissue and increase our understanding of the structure and organization of the genome. Expressed Sequence Tags (ESTs) from the public dbEST and proprietary Incyte LifeSeq databases were used to derive a transcript map in conjunction with the working draft assembly of the human genome sequence. RESULTS: Examination of ESTs derived from brain tissues (excluding brain tumor tissues) suggests that these genes are distributed on chromosomes in a non-random fashion. Some regions on the genome are dense with brain-enriched genes while some regions lack brain-enriched genes, suggesting a significant correlation between distribution of genes along the chromosome and tissue type. ESTs from brain tumor tissues have also been mapped to the human genome working draft. We reveal that some regions enriched in brain genes show a significant decrease in gene expression in brain tumors, and, conversely that some regions lacking in brain genes show an increased level of gene expression in brain tumors. CONCLUSIONS: This report demonstrates a novel approach for tissue specific transcriptome mapping using EST-based quantitative assessment.

Journal Article↗

The genome sequence of silkworm, Bombyx mori.

We performed threefold shotgun sequencing of the silkworm (Bombyx mori) genome to obtain a draft sequence and establish a basic resource for comprehensive genome analysis. By using the newly developed RAMEN assembler, the sequence data derived from whole-genome shotgun (WGS) sequencing were assembled into 49,345 scaffolds that span a total length of 514 Mb including gaps and 387 Mb without gaps. Because the genome size of the silkworm is estimated to be 530 Mb, almost 97% of the genome has been organized in scaffolds, of which 75% has been sequenced. By carrying out a BLAST search for 50 characteristic Bombyx genes and 11,202 non-redundant expressed sequence tags (ESTs) in a Bombyx EST database against the WGS sequence data, we evaluated the validity of the sequence for elucidating the majority of silkworm genes. Analysis of the WGS data revealed that the silkworm genome contains many repetitive sequences with an average length of <500 bp. These repetitive sequences appear to have been derived from truncated transposons, which are interspersed at 2.5- to 3-kb intervals throughout the genome. This pattern suggests that silkworm may have an active mechanism that promotes removal of transposons from the genome. We also found evidence for insertions of mitochondrial DNA fragments at 9 sites. A search for Bombyx orthologs to Drosophila genes controlling sex determination in the WGS data revealed 11 Bombyx genes and suggested that the sex-determining systems differ profoundly between the two species.

Animals↗

Genetic information, genomic technologies, and the future of drug discovery.

The completion of the first draft of the human genome has provided an unprecedented opportunity to understand the genetic and molecular basis of disease. Parallel developments of new biological technologies, such as transcript profiling, allow scientists to examine almost any biological system in high molecular resolution. Contemporary drug discovery research is now focusing on the identification and validation of pharmaceutical targets in the molecular pathways/systems embedded in this information. Novel therapeutic interventions are being developed and evaluated as a result of this research which will be the basis of innovative pharmaceuticals of the future.

Animals↗

A genomic-systems biology map for cardiovascular function.

With the draft sequence of the human genome available, there is a need to better define gene function in the context of systems biology. We studied 239 cardiovascular and renal phenotypes in 113 male rats derived from an F2 intercross and mapped 81 of these traits onto the genome. Aggregates of traits were identified on chromosomes 1, 2, 7, and 18. Systems biology was assessed by examining patterns of correlations ("physiological profiles") that can be used for gene hunting, mechanism-based physiological studies, and, with comparative genomics, translating these data to the human genome.

Animals↗

Chicken genome sequence: a centennial gift to poultry genetics.

A draft sequence of the chicken genome will be available by early 2004. This event conveniently marks the start of the second century of poultry genetics, coming 100 years after the use of the chicken to demonstrate Mendelian inheritance in animals by William Bateson. How will the second, post-genomic century of poultry genetics differ from the first? A whole genome shotgun (WGS) approach is being used to obtain the chicken sequence, with the goal of generating approximately six-fold coverage of the genome. Bacterial artificial chromosome (BAC) and fosmid clone end sequences, along with a BAC contig map integrated with genetic linkage and radiation hybrid maps, will form the platform for assembly of the WGS data. Rapid progress in global analysis of chicken gene expression patterns is also being made. Comparative genomics will link these new discoveries to the knowledge base for all other animal species. It's hoped that the genome sequence will also provide common ground on which to unite studies of the chicken as a model species with those aimed at agriculturally-relevant applications. The current status of chicken genomics will be assessed with projections for its near and long term future.

Animals↗

Computational function assignment for potential drug targets: from single genes to cellular systems.

Biomedical science is currently undergoing an epoch-marking transition from its classical phase to the post-genome era. The outstanding success of world-wide genome sequencing efforts, evidenced by the recent publication of the draft of the human genome, together with the completion of several genomes of eukaryotic model organisms and the availability of microbial genome sequences, is opening up data sources of unprecedented scale for drug discovery. Furthermore, the elucidation of genome expression states through transcriptomic and proteomic techniques is playing a crucial role in the characterisation of disease at the molecular level. At the same time, our still very limited knowledge of the biological functions of genes and proteins at different levels of cellular organisation is preventing full exploitation of the available data. This review will discuss current computational techniques for function prediction based on the sequence-structure-function paradigm. Newly emerging approaches aimed at gaining an expanded understanding of function through integration of data from various sources and modelling of complex cellular systems will also be highlighted.

Amino Acid Sequence↗

The promise of toxicogenomics.

As human genetics and genomics have progressed, culminating in the completion of the rough draft of the human genome in February 2001, new tools and technologies have been developed to identify and quantify global gene expression changes occurring in the cell. These new technologies are allowing researchers to gain an increased understanding of the function and regulation of genes at the systems level, and are transforming virtually all areas of biological research. In the field of toxicology, a new subdiscipline termed toxicogenomics has emerged which promises to identify and characterize the molecular mechanisms that lead to toxicity. Gene expression profiling, through the use of microarray technology, is rapidly becoming a standard analysis in toxicology studies, and has the potential to play a pivotal role in all stages of drug safety evaluation. This review focuses on recent studies in toxicogenomics, and discusses the promises and future challenges in this field.

Animals↗

Extensive analysis of the 13q14 region in human prostate tumors: DNA analysis and quantitative expression of genes lying in the interval of deletion.

BACKGROUND: Loss of heterozygosity (LOH) on chromosome arm 13q14 is one of the most consistent genetic alterations in sporadic prostate cancer. This alteration may be involved in prostate oncogenesis through inactivation of one or more tumor suppressor genes (TSGs). Candidate gene expression is an approach to focus the search for TSGs in this region. METHODS: We tested 41 human sporadic prostate tumors for 13q14 LOH by using seven polymorphic markers overlapping the critical region and used a real-time quantitative RT-PCR assay to study the same tumors for expression of the 31 genes located in this genomic region (localized by the Human Genome Project Working Draft). RESULTS: Allelic loss on at least one locus was found in 18 (41%) of the 41 tumor DNAs. Only four genes (ITM2B, CHC1L, KIAA0970, and LOC51131), located in the region most frequently deleted in prostate carcinoma, showed a significant difference in expression between normal and neoplastic prostate tissues. CONCLUSIONS: Given their location in the LOH hotspot, as indicated by our genomic analysis, ITM2B, CHC1L, KIAA0970, and LOC51131 are candidate tumor suppressor genes in this region. ITM2B that showed a significant association (P < 0.005) between expression and LOH at the corresponding locus could, furthermore, be the main target of the observed LOH at 13q in prostate tumors.

Adenocarcinoma↗

Protein encoding genes in an ancient plant: analysis of codon usage, retained genes and splice sites in a moss, Physcomitrella patens.

BACKGROUND: The moss Physcomitrella patens is an emerging plant model system due to its high rate of homologous recombination, haploidy, simple body plan, physiological properties as well as phylogenetic position. Available EST data was clustered and assembled, and provided the basis for a genome-wide analysis of protein encoding genes. RESULTS: We have clustered and assembled Physcomitrella patens EST and CDS data in order to represent the transcriptome of this non-seed plant. Clustering of the publicly available data and subsequent prediction resulted in a total of 19,081 non-redundant ORF. Of these putative transcripts, approximately 30% have a homolog in both rice and Arabidopsis transcriptome. More than 130 transcripts are not present in seed plants but can be found in other kingdoms. These potential "retained genes" might have been lost during seed plant evolution. Functional annotation of these genes reveals unequal distribution among taxonomic groups and intriguing putative functions such as cytotoxicity and nucleic acid repair. Whereas introns in the moss are larger on average than in the seed plant Arabidopsis thaliana, position and amount of introns are approximately the same. Contrary to Arabidopsis, where CDS contain on average 44% G/C, in Physcomitrella the average G/C content is 50%. Interestingly, moss orthologs of Arabidopsis genes show a significant drift of codon fraction usage, towards the seed plant. While averaged codon bias is the same in Physcomitrella and Arabidopsis, the distribution pattern is different, with 15% of moss genes being unbiased. Species-specific, sensitive and selective splice site prediction for Physcomitrella has been developed using a dataset of 368 donor and acceptor sites, utilizing a support vector machine. The prediction accuracy is better than those achieved with tools trained on Arabidopsis data. CONCLUSION: Analysis of the moss transcriptome displays differences in gene structure, codon and splice site usage in comparison with the seed plant Arabidopsis. Putative retained genes exhibit possible functions that might explain the peculiar physiological properties of mosses. Both the transcriptome representation (including a BLAST and retrieval service) and splice site prediction have been made available on http://www.cosmoss.org, setting the basis for assembly and annotation of the Physcomitrella genome, of which draft shotgun sequences will become available in 2005.

Alternative Splicing↗