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At least 865 records · Page 48Linked to original sources
PubMed2002

A compilation of soybean ESTs: generation and analysis.

Whole-genome sequencing is fundamental to understanding the genetic composition of an organism. Given the size and complexity of the soybean genome, an alternative approach is targeted random-gene sequencing, which provides an immediate and productive method of gene discovery. In this study, more than 120000 soybean expressed sequence tags (ESTs) generated from more than 50 cDNA libraries were evaluated. These ESTs coalesced into 16928 contigs and 17336 singletons. On average, each contig was composed of 6 ESTs and spanned 788 bases. The average sequence length submitted to dbEST was 414 bases. Using only those libraries generating more than 800 ESTs each and only those contigs with 10 or more ESTs each, correlated patterns of gene expression among libraries and genes were discerned. Two-dimensional qualitative representations of contig and library similarities were generated based on expression profiles. Genes with similar expression patterns and, potentially, similar functions were identified. These studies provide a rich source of publicly available gene sequences as well as valuable insight into the structure, function, and evolution of a model crop legume genome.

Contig Mapping↗
PubMed2006

Intestinal colonisation, microbiota and future probiotics?

The human intestine is colonized by a large number of microorganisms, collectively termed microbiota, which support a variety of physiological functions. As the major part of the microbiota has not yet been cultured, molecular methods are required to determine microbial composition and the impact of specific dietary components including probiotics. Probiotics are viable microbial food supplements, which have a beneficial impact on human health. Health-promoting properties have been demonstrated for specific probiotic products. The most significant demonstrations for probiotic efficacy include prevention and treatment of antibiotic associated diarrhea, rotavirus diarrhea and allergy prevention. Lactobacillus rhamnosus GG (=ATCC 53103) and Bifidobacterium lactis Bb12 are the among the best-characterized and most studied probiotic strains with demonstrated impact on human health. New complex targets for probiotics include irritable bowel syndrome and Helicobacter pylori infection. For future probiotics the most important target is a demonstrated clinical benefit supported by knowledge on the mechanistic actions in the microbiota of the target population. Molecular and genomics-based knowledge of the composition and functions of the microbiota, as well as deviations from the balanced microbiota, will advance the selection of new and specific probiotics. Potential combinations of specific probiotics may prove to be the next step to reduce the risk on intestinal diseases and reconstruct specific microbial deviations.

Bifidobacterium↗
PubMed2026

Diet modulates cardiac metabolic stress during anthracycline treatment.

Diet is a modifiable determinant of cardiovascular risk and may influence tolerance to cancer therapies. The mechanisms by which specific dietary components affect cardiac metabolism during anthracycline treatment remain poorly defined, limiting the incorporation of dietary recommendations into treatment guidelines. Here, we integrated heart proteomics data from patients treated with or without anthracyclines with a genome-scale reconstruction of human cardiac metabolism (CardioNet). Using constraint-based flux analysis, we conducted >30,000 in silico simulations of diet scenarios generated from chemical profiles of ∼500 foods curated in the Periodic Table of Food Initiative. These simulations revealed that diets enriched in rapidly absorbable sugars and depleted of essential fatty acids impair cardiac metabolic efficiency, increasing reactive oxygen species production and the demand for purine salvage fluxes. These predicted metabolic patterns were consistent with plasma metabolomics from patients treated with anthracyclines, validating our findings. Computational modeling of 39 recipes across six cuisines revealed cardiometabolic effects of omnivorous versus vegan diets in patients. Modeling of a healthy vegan diet increased cardiometabolic efficiency compared with a healthy omnivorous diet in patients treated with anthracyclines, independent of the culinary background. Our approach demonstrates that integrating the molecular composition of food with genome-scale metabolic models enables systematic analysis of diet patterns for translational testing. Ultimately, these in silico studies provide a framework for trials and may inform dietary recommendations for improving cardiometabolic health.NEW & NOTEWORTHY We developed a systems biology framework to predict how diet influences cardiac metabolism during cancer therapy. Across >30,000 in silico diet simulations, we identified nutrient patterns that either exacerbate or mitigate anthracycline-induced metabolic stress. These findings demonstrate how computational modeling can uncover diet-metabolism interactions driving cardiotoxicity and guide dietary interventions.

Humans↗
PubMed2026

Systematic identification of germ granule proteins reveals specialized roles in RNAi and small RNA inheritance.

Biomolecular condensates, such as germ granules, organize RNAi pathways critical for fertility and genome regulation. However, the protein composition and functional contributions of these condensates remain poorly defined. Here, we applied TurboID proximity labeling to the Caenorhabditis elegans germ granule protein SIMR-1, integrating mass spectrometry with genetic screening, CRISPR-based tagging, and small RNA sequencing. This systematic approach identified several previously uncharacterized germ granule proteins that contribute to fertility, germline immortality, exogenous RNAi, and transgenerational inheritance. Small RNA sequencing of 21 mutants revealed broad and class-specific defects in siRNA and miRNA biogenesis, with distinct factors associated with defects in WAGO-class 22G-RNAs, CSR-class 22G-RNAs, or histone-directed small RNAs. Among these, we identified PINT-1, a highly disordered protein that directly interacts with and is recruited to germ granules by the PIWI Argonaute PRG-1. PINT-1 is required for piRNA-dependent and -independent secondary siRNA biogenesis and germline development. Comparative genomics revealed that PINT-1 has coevolved with PRG-1 across clade V nematodes, with a conserved structured N terminus and a rapidly diverging repeat-rich intrinsically disordered region. Together, our findings expand the germ granule proteome and reveal how distinct condensate components contribute to specialized functions within the small RNA pathways, while highlighting an evolutionarily coadapted PIWI interactor critical for siRNA biogenesis.

Animals↗
PubMed2003

FISH analysis of meiosis in Arabidopsis allopolyploids.

Although allopolyploids are common in nature and in agriculture, knowledge of their origin, evolution and genomic regulation is limited. We study synthetic allotetraploids of Arabidopsis thaliana and Arabidopsis arenosa as well as the natural allotetraploid Arabidopsis suecica. To elucidate the composition and behavior of the allotetraploid genome, we used chromosome painting with probes from contiguous regions of chromosome 4 of A. thaliana and fluorescent in-situ hybridization with centromeric (CEN) probes specific for each parental genome. We documented the presence of 16 A. arenosa and 10 A. thaliana chromosomes and demonstrate that two different A. arenosa chromosomes are homeologous to chromosome 4 of A. thaliana. Although chromosome pairing in pollen mother cells was predominantly homologous, CENs of different parental origin coalesced at early prophase I, but resolved into proper pairs by metaphase. In addition, CENs of homologous chromosomes were not paired in tapetum cells and endopolyploidy without strict polyteny was evident by the large number of independent CENs. Thus, the Arabidopsis synthetic allopolyploids were capable of homologous pairing as early as three generations after their formation. This indicates that diploid-like pairing is not the result of adaptive mutations in genes that regulate pairing nor the result of structural remodeling of the genomes: rather, it is likely that either the parents provided genes controlling pairing behavior or that features of the parental chromosomes hinder homeologous pairing.

Arabidopsis↗
PubMed1998

Natural variation in neuron number in mice is linked to a major quantitative trait locus on Chr 11.

Common genetic polymorphisms-as opposed to rare mutations-generate almost all heritable differences in the size and structure of the CNS. Surprisingly, these normal variants have not previously been mapped or cloned in any vertebrate species. In a recent paper (), we suggested that much of the variation in retinal ganglion cell number in mice, and the striking bimodality of strain averages, are caused by one or two quantitative trait loci (QTLs). To test this idea, and to map genes linked to this variable and highly heritable quantitative trait, we have counted ganglion cells in 38 recombinant inbred strains (BXD and BXH) derived from parental strains that have high and low cell numbers. A genome-wide search using simple and composite interval-mapping techniques revealed a major QTL on chromosome (Chr) 11 in a 3 cM interval between Hoxb and Krt1 (LOD = 6.8; genome-wide p = 0.001) and possible subsidiary QTLs on Chr 2 and Chr 8. The Chr 11 locus, neuron number control 1 (Nnc1), accounts for one third of the genetic variance among BXH strains and more than half of that among BXD strains, but Nnc1 has no known effects on brain weight, eye weight, or total retinal cell number. Three strong candidate genes have been mapped previously to the same region as Nnc1. These genes-Rara, Thra, and Erbb2- encode receptors for retinoic acid, thyroxine, and neuregulin, respectively. Each receptor is expressed in the retina during development, and their ligands affect the proliferation or survival of retinal cells.

Animals↗
PubMed2005

Genome wide analysis of Arabidopsis core promoters.

BACKGROUND: Core promoters are the gene regulatory regions most proximal to the transcription start site (TSS), central to the formation of pre-initiation complexes and for combinatorial gene regulation. The DNA elements required for core promoter function in plants are poorly understood. To establish the sequence motifs that characterize plant core promoters and to compare them to the corresponding sequences in animals, we took advantage of available full-length cDNAs (FL-cDNAs) and predicted upstream regulatory sequences to carry out the analysis of 12,749 Arabidopsis core promoters. RESULTS: Using a combination of expectation maximization and Gibbs sampling methods, we identified several motifs overrepresented in Arabidopsis core promoters. One of them corresponded to the TATA element, for which an in-depth analysis resulted in the generation of robust TATA Nucleotide Frequency Matrices (NFMs) capable of predicting Arabidopsis TATA elements with a high degree of confidence. We established that approximately 29% of all Arabidopsis promoters contain TATA motifs, clustered around position -32 with respect to the TSS. The presence of TATA elements was associated with genes represented more frequently in EST collections and with shorter 5' UTRs. No cis-elements were found over-represented in TATA-less, compared to TATA-containing promoters. CONCLUSION: Our studies provide a first genome-wide illustration of the composition and structure of core Arabidopsis promoters. The percentage of TATA-containing promoters is much lower than commonly recognized, yet comparable to the number of Drosophila promoters containing a TATA element. Although several other DNA elements were identified as over-represented in Arabidopsis promoters, they are present in only a small fraction of the genes and they represent elements not previously described in animals, suggesting a distinct architecture of the core promoters of plant and animal genes.

5' Untranslated Regions↗
PubMed2005

Insect mitochondrial genomics: the complete mitochondrial genome sequence of the meadow spittlebug Philaenus spumarius (Hemiptera: Auchenorrhyncha: Cercopoidae).

We present the complete mitochondrial genome sequence of the meadow spittlebug Philaenus spumarius (Auchenorrhyncha: Cercopoidae). This contribution represents the second mitochondrial genome from the Hemiptera and the second of the three hemipteran suborders sampled. The genome is a circular molecule of 16 324 bp with a total A+T content of 77.0% and 76.7% for coding regions only. The gene content, order, and structure are consistent with the Drosophila yakuba genome structure (Clary and Wolstenholme 1985) and the hypothesized ancestral arthropod genome arrangement (Crease 1999). Nucleotide composition and codon usage are near the means observed in other insect mitochondria sequenced to date but have a higher A+T richness compared with the other hemipteran example, the kissing bug Triatoma dimidiata (Dotson and Beard. 2001. Insect Mol. Biol. 10: 205-215). The major noncoding region (the A+T rich region or putative control region) between the small ribosomal subunit and the tRNAIle gene includes two extensive repeat regions. The first repeat region includes 19 tandem repeats of a 46-bp sequence, whereas the second contains a longer sequence (146 bp) tandemly repeated four times.

Animals↗
PubMed1992

Comparisons of the genomic sequences of erysimum latent virus and other tymoviruses: a search for the molecular basis of their host specificities.

The nucleotide sequence of the genome of erysimum latent tymovirus (ELV) has been determined. It closely resembles those of the other four sequenced tymoviral genomes in its gene organization and composition, but is the smallest (6034 nucleotides) and most distinct of them. Furthermore the 78 non-coding nucleotides at the 3' terminus of the ELV genome are unable to form a complete tRNA-like structure like that reported for other tymoviruses. Comparisons of the five tymovirus genomes and their encoded proteins indicate that they have probably evolved from the progenitor tymovirus by independent progressive mutational change without genetic recombination. Comparisons of the sequences of the two non-virion proteins of five tymoviruses, and virion proteins of 17 tymoviruses, revealed no specific similarities between those of ELV and turnip yellow mosaic virus that could explain why their host ranges and symptoms are so similar, yet differ, in this respect, from ononis yellow mosaic, kennedya yellow mosaic and eggplant mosaic tymoviruses.

Amino Acid Sequence↗
PubMed2001

DNA asymmetry and the replicational mutational pressure.

The mode of replication and organisation of bacterial genomes impose asymmetry on their nucleotide composition. The asymmetry is seen in coding and non-coding sequences and is reflected in the amino acid composition of proteins. The mechanisms generating asymmetry include: unequal mutation rates connected with replication and transcription, selection forces positioning genes and signal sequences nonrandomly in the genome, and protein coding constraints on coding sequences. There are different methods of visualising and measuring the asymmetry. Some of them can assess the contribution of individual mechanisms to the observed asymmetry and those have been described in greater detail. Asymmetric mutational and selection pressures differentiate the rates of evolution of genes on leading and lagging strands. The genes relocated to the opposite strand have to adapt to a different mutational pressure or are eliminated. Translocations from leading to lagging strands are more often selected against than from lagging to leading strands. Comparison of intergenic sequences that have lost the coding function to the original genes enables finding the frequencies of the twelve substitution rates in sequences free from selection. In the absence of selection, the half-time of substitution of a given type of nucleotide is linearly correlated with the fraction of that nucleotide in the sequence.

Journal Article↗
PubMed1998

Codon reassignment and amino acid composition in hemichordate mitochondria.

In the mitochondrial genome of the hemichordate Balanoglossus carnosus, the codon AAA, which is assigned to lysine in most metazoans but to asparagine in echinoderms, is absent. Furthermore, the lysine tRNA gene carries an anticodon substitution that renders its gene product unable to decode AAA codons, whereas the asparagine tRNA gene has not changed to encode a tRNA with the ability to recognize AAA codons. Thus, the hemichordate mitochondrial genome can be regarded as an intermediate in the process of reassignment of mitochondrial AAA codons, where most metazoans represent the ancestral situation and the echinoderms the derived situation. This lends support to the codon capture hypothesis. We also show that the reassignment of the AAA codon is associated with a reduction in the relative abundance of lysine residues in mitochondrial proteins.

Amino Acids↗
PubMed2005

Complete nucleotide sequence of the mitochondrial genome of Schlegel's tree frog Rhacophorus schlegelii (family Rhacophoridae): duplicated control regions and gene rearrangements.

The complete nucleotide sequence (21,359 bp) of the mitochondrial DNA of the rhacophorid frog Rhacophorus schlegelii was determined. The gene content, nucleotide composition, and codon usage of this genome corresponded to those typical of vertebrates. However, the Rh. schlegelii genome was unusually large due to the inclusion of two control regions and the accumulation of lengthy repetitive sequences in these regions. The two control regions had 97% sequence similarity over 1,510 bp, suggesting the occurrence of concerted sequence evolution. Comparison of the gene organizations among anuran species revealed that the mitochondrial gene arrangement of Rh. schlegelii diverged from that of typical vertebrates but was similar to that of Buergeria buergeri. The positions of the tRNA-Leu(CUN) and tRNA-Thr genes were exchanged between Rh. schlegelii and B. buergeri. Based on parsimonious consideration and the basal phylogenetic position of B. buergeri, these genes seemed to have been rearranged in an ancestral lineage leading to Rh. schlegelii.

Animals↗
PubMed2026

Regional genomic analysis of lineage distribution and transferable multidrug resistance among chicken-associated Salmonella Kentucky isolates in China.

Salmonella enterica serovar Kentucky is an important multidrug-resistant foodborne pathogen in the poultry meat supply chain. Although recent broader genomic studies have elucidated the population structure and epidemiological significance of major lineages in China (e.g., ST198 and ST314), the regional dynamics within local poultry supply chains remain insufficiently characterized. In this study, 31 chicken meat-derived isolates from Shanghai and 39 publicly available genomes from China were analyzed using antimicrobial susceptibility testing, whole-genome sequencing, phylogenetic analysis, conjugation experiments, and complete sequencing of representative plasmids. This enabled a systematic characterization of the molecular epidemiological features of the population and the mechanisms underlying resistance dissemination. Population genomic analysis revealed a lineage composition markedly different from the global epidemiological pattern: ST314 was the predominant sequence type among the Shanghai chicken-derived isolates (74.2%), whereas the internationally recognized high-risk clone ST198 accounted for only 25.8% of the local isolates. However, risk stratification analysis indicated that although ST198 was detected less frequently, it carried a significantly greater burden of acquired resistance genes and therefore represented a higher-risk resistant lineage. Functional and structural validation further elucidated the molecular basis of resistance dissemination within this high-risk lineage. Conjugation experiments confirmed the co-transfer of a multidrug resistance module carrying blaTEM-1 and blaCTX-M-267 to the recipient strain Escherichia coli J53. Complete plasmid analysis revealed that these two β-lactam resistance genes were co-localized on a 242-kb transferable plasmid flanked by Tn1331, Tn3, and multiple transposase-associated elements, thereby providing a structural basis for their horizontal transfer. This study provides important molecular epidemiological evidence for lineage-specific surveillance and risk-stratified control of resistant Salmonella in the poultry meat supply chain and further underscores the need for continuous monitoring of mobile genetic elements within a One Health framework.

Animals↗
PubMed2005

IRIS: a database surveying known human immune system genes.

We have compiled an online database of known human defense genes: the Immunogenetic Related Information Source (IRIS). As of October 1, 2004, there are 1562 immune genes recorded in IRIS, representing 7% of the human genome. This resource contains searchable information including chromosomal location, sequence data, and a curated functional annotation for each entry. We used IRIS as a basis for analyzing the composition and characteristics of the immune genome, such as gene clustering, polymorphism, and relationship to disease. High protein sequence similarity correlated inversely with distance between immune genes, consistent with clustering of duplicated loci. We also found that, even though some immune genes exhibit high levels of polymorphism, such as MHC class I, the range of levels of polymorphism in immune genes is similar to that of nonimmune genes. Approximately 20% of immune genes have a known disease association. IRIS is available online at .

Databases, Genetic↗
PubMed1991

Rapid determination of nucleotide content and its application to the study of genome structure.

We have developed a sensitive, reliable and accurate procedure for estimating the base composition of small samples of DNAs. This method has been applied to the analysis of genomic DNAs from several sources including large regions of human DNA cloned as yeast artificial chromosomes. To determine whether the human genome is compartmentalized into large segments of homogeneous base composition, we examined the GC content of a 1.2 megabase contig spanning the cystic fibrosis gene.

Bacteria↗
PubMed2006

Rate and polarity of gene fusion and fission in Oryza sativa and Arabidopsis thaliana.

Eukaryotic gene fusion and fission events are mechanistically more complicated than in prokaryotes, and their quantitative contributions to genome evolution are still poorly understood. We have identified all differentially composite or split genes in 2 fully sequenced plant genomes, Oryza sativa and Arabidopsis thaliana. Out of 10,172 orthologous gene pairs, 60 (0.6% of the total) revealed a verified fusion or fission event in either lineage after the divergence of O. sativa and A. thaliana. Polarizing these events by outgroup comparison revealed differences in the rate of gene fission but not of gene fusion in the rice and Arabidopsis lineages. Gene fission occurred at a higher rate than gene fusion in the O. sativa lineage and was furthermore more common in rice than in Arabidopsis. Nucleotide insertion bias has promoted gene fission in the O. sativa lineage, consistent with its generally longer nucleotide sequences than A. thaliana in selectively neutral regions, and with the abundance of transposable elements in rice. The divergence time of monocots and dicots (140-200 Myr) indicates that gene fusion/fission events occur at an average rate of 1x10(-11) to 2x10(-11) events per gene per year, approximately 100-fold slower than the average per site nuclear nucleotide substitution rate in these lineages. Gene fusion and fission are thus rare and slow processes in higher plant genomes; they should be of utility to address deeper evolutionary relationships among plants--and the relationship of plants to other eukaryotic lineages--where sequence-based phylogenies provide equivocal or conflicting results.

Arabidopsis↗
PubMed2004

Genome sequence of Haloarcula marismortui: a halophilic archaeon from the Dead Sea.

We report the complete sequence of the 4,274,642-bp genome of Haloarcula marismortui, a halophilic archaeal isolate from the Dead Sea. The genome is organized into nine circular replicons of varying G+C compositions ranging from 54% to 62%. Comparison of the genome architectures of Halobacterium sp. NRC-1 and H. marismortui suggests a common ancestor for the two organisms and a genome of significantly reduced size in the former. Both of these halophilic archaea use the same strategy of high surface negative charge of folded proteins as means to circumvent the salting-out phenomenon in a hypersaline cytoplasm. A multitiered annotation approach, including primary sequence similarities, protein family signatures, structure prediction, and a protein function association network, has assigned putative functions for at least 58% of the 4242 predicted proteins, a far larger number than is usually achieved in most newly sequenced microorganisms. Among these assigned functions were genes encoding six opsins, 19 MCP and/or HAMP domain signal transducers, and an unusually large number of environmental response regulators-nearly five times as many as those encoded in Halobacterium sp. NRC-1--suggesting H. marismortui is significantly more physiologically capable of exploiting diverse environments. In comparing the physiologies of the two halophilic archaea, in addition to the expected extensive similarity, we discovered several differences in their metabolic strategies and physiological responses such as distinct pathways for arginine breakdown in each halophile. Finally, as expected from the larger genome, H. marismortui encodes many more functions and seems to have fewer nutritional requirements for survival than does Halobacterium sp. NRC-1.

Archaeal Proteins↗