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Statistical modeling of biomedical corpora: mining the Caenorhabditis Genetic Center Bibliography for genes related to life span.

BACKGROUND: The statistical modeling of biomedical corpora could yield integrated, coarse-to-fine views of biological phenomena that complement discoveries made from analysis of molecular sequence and profiling data. Here, the potential of such modeling is demonstrated by examining the 5,225 free-text items in the Caenorhabditis Genetic Center (CGC) Bibliography using techniques from statistical information retrieval. Items in the CGC biomedical text corpus were modeled using the Latent Dirichlet Allocation (LDA) model. LDA is a hierarchical Bayesian model which represents a document as a random mixture over latent topics; each topic is characterized by a distribution over words. RESULTS: An LDA model estimated from CGC items had better predictive performance than two standard models (unigram and mixture of unigrams) trained using the same data. To illustrate the practical utility of LDA models of biomedical corpora, a trained CGC LDA model was used for a retrospective study of nematode genes known to be associated with life span modification. Corpus-, document-, and word-level LDA parameters were combined with terms from the Gene Ontology to enhance the explanatory value of the CGC LDA model, and to suggest additional candidates for age-related genes. A novel, pairwise document similarity measure based on the posterior distribution on the topic simplex was formulated and used to search the CGC database for "homologs" of a "query" document discussing the life span-modifying clk-2 gene. Inspection of these document homologs enabled and facilitated the production of hypotheses about the function and role of clk-2. CONCLUSION: Like other graphical models for genetic, genomic and other types of biological data, LDA provides a method for extracting unanticipated insights and generating predictions amenable to subsequent experimental validation.

Animals↗

Phylogenetic analyses identify 10 classes of the protein disulfide isomerase family in plants, including single-domain protein disulfide isomerase-related proteins.

Protein disulfide isomerases (PDIs) are molecular chaperones that contain thioredoxin (TRX) domains and aid in the formation of proper disulfide bonds during protein folding. To identify plant PDI-like (PDIL) proteins, a genome-wide search of Arabidopsis (Arabidopsis thaliana) was carried out to produce a comprehensive list of 104 genes encoding proteins with TRX domains. Phylogenetic analysis was conducted for these sequences using Bayesian and maximum-likelihood methods. The resulting phylogenetic tree showed that evolutionary relationships of TRX domains alone were correlated with conserved enzymatic activities. From this tree, we identified a set of 22 PDIL proteins that constitute a well-supported clade containing orthologs of known PDIs. Using the Arabidopsis PDIL sequences in iterative BLAST searches of public and proprietary sequence databases, we further identified orthologous sets of 19 PDIL sequences in rice (Oryza sativa) and 22 PDIL sequences in maize (Zea mays), and resolved the PDIL phylogeny into 10 groups. Five groups (I-V) had two TRX domains and showed structural similarities to the PDIL proteins in other higher eukaryotes. The remaining five groups had a single TRX domain. Two of these (quiescin-sulfhydryl oxidase-like and adenosine 5'-phosphosulfate reductase-like) had putative nonisomerase enzymatic activities encoded by an additional domain. Two others (VI and VIII) resembled small single-domain PDIs from Giardia lamblia, a basal eukaryote, and from yeast. Mining of maize expressed sequence tag and RNA-profiling databases indicated that members of all of the single-domain PDIL groups were expressed throughout the plant. The group VI maize PDIL ZmPDIL5-1 accumulated during endoplasmic reticulum stress but was not found within the intracellular membrane fractions and may represent a new member of the molecular chaperone complement in the cell.

Base Sequence↗

The potential of proteomics and peptidomics for allergy and asthma research.

Progress in the field of proteomics, the branch of biology that studies the full set of proteins derived from a given genome, is moving fast. Two-dimensional gel electrophoresis (2DG) separation of complex protein mixtures and the subsequent analysis of isolated protein spots by mass spectrometry allow fast and accurate identification of proteins. The comparison of spots from different samples separated on customized 2D gels allows the detection of punctual differences in their mobility and facilitates tracing back differences in protein expression, presence of isoforms, splice variants and posttranslational modifications by mass spectrometry. In spite of significant analytical challenges owing to the high complexity of the proteome and the challenge deriving from the necessity to process huge amounts of raw data generated by mass spectrometric profiling, proteomics has evolved to an indispensable tool in life sciences. A restricted window of the proteome that consists of peptides and small proteins not easily manageable by conventional gel electrophoresis prompted the development of separation methods based on liquid chromatography. This new research field termed peptidomics already contributed, together with proteomics to enlarge our knowledge about biological processes and supported by sophisticated bioinformatics tools, to the discovery of new diagnostic and therapeutic targets. The technological capabilities of biophysical separation, mass spectrometry and bioinformatics form the basis of discovery programs that aim at mining the proteome starting from microgram amounts of protein extracts derived from body fluids and tissues. Proteomics and peptidomics have a great potential to speed up allergy and asthma research, where disease- and tissue-specific samples are easy to obtain.

Asthma↗

Expressed sequence tags (ESTs) and simple sequence repeat (SSR) markers from octoploid strawberry (Fragaria x ananassa).

BACKGROUND: Cultivated strawberry (Fragaria x ananassa) represents one of the most valued fruit crops in the United States. Despite its economic importance, the octoploid genome presents a formidable barrier to efficient study of genome structure and molecular mechanisms that underlie agriculturally-relevant traits. Many potentially fruitful research avenues, especially large-scale gene expression surveys and development of molecular genetic markers have been limited by a lack of sequence information in public databases. As a first step to remedy this discrepancy a cDNA library has been developed from salicylate-treated, whole-plant tissues and over 1800 expressed sequence tags (EST's) have been sequenced and analyzed. RESULTS: A putative unigene set of 1304 sequences--133 contigs and 1171 singlets--has been developed, and the transcripts have been functionally annotated. Homology searches indicate that 89.5% of sequences share significant similarity to known/putative proteins or Rosaceae ESTs. The ESTs have been functionally characterized and genes relevant to specific physiological processes of economic importance have been identified. A set of tools useful for SSR development and mapping is presented. CONCLUSION: Sequences derived from this effort may be used to speed gene discovery efforts in Fragaria and the Rosaceae in general and also open avenues of comparative mapping. This report represents a first step in expanding molecular-genetic analyses in strawberry and demonstrates how computational tools can be used to optimally mine a large body of useful information from a relatively small data set.

Chromosome Mapping↗

The era of microbiology: a golden phoenix.

The discoveries over the last decade have demonstrated that microbiology is a central scientific discipline with practical applications in agriculture, medicine, bioremediation, biotechnology, engineering, and other fields. It is clear that the roles of microbes in nature are so diverse that the process of mining this genetic variation for new applications will continue long into the future. Moreover, the rapid rate of microbial evolution ensures that there will be no permanent solution to agricultural, medical, or environmental problems caused by microbes. These problems will demand a continual stream of creative new approaches that evolve along with the microbes. Thus, the excitement of this field will continue long into the future. However, these opportunities and imperatives demand a deep understanding of basic microbial physiology, genetics, and ecology. Major challenges that lay ahead are to impart the broad training needed to entice and enable the next generation of microbiologists, and to educate the public and government representatives about the continued and critical importance of this field for health and the economy.

Biological Evolution↗

Transcriptional co-regulation of secondary metabolism enzymes in Arabidopsis: functional and evolutionary implications.

The combined knowledge of the Arabidopsis genome and transcriptome now allows to get an integrated view of the dynamics and evolution of metabolic pathways in plants. We used publicly available sets of microarray data obtained in a wide range of different stress and developmental conditions to investigate the co-expression of genes encoding enzymes of secondary metabolism pathways, in particular indoles, phenylpropanoids, and flavonoids. We performed hierarchical clustering of gene expression profiles and found that major enzymes of each pathway display a clear and robust co-expression throughout all the conditions studied. Moreover, detailed analysis evidenced that some genes display co-regulation in particular physiological conditions only, certainly reflecting their modular recruitment into stress- or developmentally regulated biosynthetic pathways. The combination of these microarray data with sequence analysis allows to draw very precise hypotheses on the function of otherwise uncharacterized genes. To illustrate this approach, we focused our analysis on secondary metabolism glycosyltransferases (UGTs), a multigenic family involved in the conjugation of small molecules to sugars like glucose. We propose that UGT74B1 and UGT74C1 may be involved in aromatic and aliphatic glucosinolates synthesis, respectively. We also suggest that UGT75C1 may function as an anthocyanin-5-O-glucosyltransferase in planta. Therefore, this data-mining approach appears very powerful for the functional prediction of unknown genes, and could be transposed to virtually any other gene family. Finally, we suggest that analysis of expression pattern divergence of duplicated genes also provides some insight into the mechanisms of metabolic pathway evolution.

Arabidopsis↗

Identification, tissue expression, and chromosomal position of a novel gene encoding human ubiquitin-conjugating enzyme E2-230k.

Through large-scale human genome mapping and sequencing of a region at chromosome 17q25.1 that is of particular interest because genes associated with breast, ovarian, and esophageal cancer are likely to be located there, we isolated the cDNA of a novel member of the family of ubiquitin-conjugating enzymes. The predicated peptide showed 97% identity in amino-acid sequence to murine ubiquitin-conjugating enzyme E2-230k (Mus UBE2-230k). The human cDNA consisted of 4878 nucleotides with an open reading frame encoding 1138 amino acids; the approximately 5 kb transcript was expressed predominantly in skeletal muscle and heart. The predicted UBE2-230k peptide contained a motif typical of the UBC domain that has been implicated in the ubiquitin-dependent proteolytic system and related pathways.

Amino Acid Sequence↗

Mining for SNPs: putting the common variants--common disease hypothesis to the test.

Classical molecular genetic strategies have succeeded in identifying mutations responsible for numerous rare diseases with Mendelian patterns of inheritance, but have been largely unsuccessful in unravelling the (genetic basis of complex medical conditions like cardiovascular disease' diabetes and mental illness. These common disorders are shaped by multiple genes that exert weak allelic effects in the setting of confounding environmental variables. Association study designs provide statistical povwer to reveal the modest contributions of weak alleles, and evidence is mounting that common genetic polymorphisms play a role in complex diseases. Cataloguing genetic variation in human populations is a prerequisite for further validation of the 'common variants-common disease' hypothesis, and polymorphism discovery has begun in earnest in the academic and private sector. We will review several strategies for high-throughput polymorphism discovery and discuss the implications of early results from polymorphism screens for future genetic studies.

Gene Frequency↗

A structural-informatics approach for mining beta-sheets: locating sheets in intermediate-resolution density maps.

Here, we report a new computational method, called sheetminer, for mining beta-sheets in the density maps at intermediate resolutions of 6 to 10A. The method employs a multi-step ad hoc morphological analysis of density maps to identify the unique characteristics of beta-sheets. It was tested on density maps from 12 protein crystal structures that were artificially blurred to intermediate resolutions. There are a total of 35 independent beta-sheets with a wide distribution of morphology. The method successfully located 34 of them and missed only one. The method was also applied to an experimental 9A electron cryomicroscopic structure and an 8A X-ray density map. In both cases, the sheet-searching results were found to agree very well with known high-resolution crystal structures. Collectively, these results demonstrate clearly the robustness of sheetminer in locating the regions belonging to beta-sheets in the intermediate-resolution density maps. Furthermore, sheetminer is completely complementary to all other existing computational methods, including helixhunter and threading algorithms. Their combined usage has the potential to significantly enhance the computational modeling capacity for a much more complete interpretation of structural data at intermediate resolutions, from which extraction of functional information would be more effective. This is particularly important in the field of structural genomics, in which the fast screening approach may not always yield crystals that diffract to atomic resolution. An exciting future application of sheetminer is as a valuable tool for revealing the structures of amyloid fibrils that are rich in beta-motifs.

Algorithms↗

The purinome, a complex mix of drug and toxicity targets.

Much attention has focused on the development of protein kinases as drug targets to treat a variety of human diseases including diabetes, cancer, hypertension and arthritis. To date, Gleevec is one example of a drug targeting protein that has successfully treated human cancer. Several other protein kinase inhibitors are in clinical development. However, protein kinases are in fact part of a larger collection of some 2000 distinct proteins expressed by the genome that like the protein kinases also bind purines (the purinome), either to be utilized as substrates or as co-factors in the form of NAD, NADP and co-enzyme A. The solution structures of many representative gene family members within the purinome show these proteins bind purines in a similar orientations to that observed in all protein kinases. Several non-protein kinase purine utilizing proteins are established drug targets such as HMG CoA reductase, dihydrofolate reductase, phosphodiesterase and HSP90. Searches of OMIM identifies many purine utilizing enzymes that are associated with inborn errors in metabolism. Inhibition of any one of which by a drug could lead to an undesirable side effect. The purinome is therefore somewhat of a drug discovery mixed blessing. It is a rich source of therapeutic targets, but also contains a large collection of diverse proteins whose inhibition could result in an adverse outcome. Drug discovery within the purinome should therefore encompass strategies that enable broad assessment of selectivity across the entire purinome at the earliest stages of the discovery process. In this article we review the purinome within the context of drug discovery and discuss approaches for avoiding off target binding during the discovery/lead optimization process with particular emphasis on use of proteome mining technology.

Animals↗

Cytogenetic effects in children and mothers exposed to air pollution assessed by the frequency of micronuclei and fluorescence in situ hybridization (FISH): a family pilot study in the Czech Republic.

A family pilot study was conducted in the Czech Republic to test the hypothesis that exposure to air pollution with particulate matter (PM) in children results in detectable effects indicated by a number of biomarkers of exposure and early effects. The frequency of micronuclei (MN) in peripheral blood lymphocytes (PBLs) was analysed to assess the cytogenetic effects in children and mothers living in two different areas. From each area two groups of children from a total of 24 families (mean age: 6.0+/-0.6 and 9.0+/-1.2 years) in a total of 47 children and 19 mothers (mean age: 33.6+/-3.9 years) participated. Chromosome aberrations determined with fluorescence in situ hybridization (FISH) painting for chromosomes #1 and #4 were analysed in 39 children and 20 parents. Teplice, a mining district, in Northern Bohemia was selected for the analyses of the effects in a population exposed to high levels of air pollution, especially during winter, and compared with a population from the rural area of Prachatice in Southern Bohemia. Significant higher frequencies of MN were found in the younger children living in the Teplice area as compared with those living in the Prachatice area (7.0+/-2.3 per thousand versus 4.9+/-2.0 per thousand, p=0.04). Higher levels of MN were also measured in the older children and the mothers from the Teplice area (9.2+/-3.7 per thousand versus 6.6+/-4.4 per thousand) and (12.6+/-3.4 per thousand versus 10.1+/-4.0 per thousand). The increased MN frequency may be associated with elevated carcinogenic polycyclic aromatic hydrocarbons (c-PAHs) concentration of the PM(2.5) measured in the ambient Teplice air, but other factors like genotoxic compounds from the diet or protective effect of micronutrients, which was not addressed in this pilot study, may also differ between the two areas. MN frequencies were found to increase with age in children. Lower MN frequency was found in boys as compared to girls. The result of the FISH analyses showed a low number of individuals with detectable levels of aberrations and no significant increases in genomic frequency of stable chromosome exchanges (F(G)/100) were found in children or parents from the Teplice area in comparison with those from the Prachatice area. The family pilot study indicates that MN is a valuable and sensitive biomarker for early biological effect in children and adults living in two different areas characterised with significant exposure differences in c-PAHs concentrations during winter.

Adult↗

Clinical and pharmacogenomic data mining: 2. A simple method for the combination of information from associations and multivariances to facilitate analysis, decision, and design in clinical research and practice.

The physician and researcher must ultimately be able to combine qualitative and quantitative features from a variety of combinations of observations on data of many component items (i.e., many dimensions), and hence reach simple conclusions about interpretation, rational courses of action, and design. In the first paper of this series, it was noted that such needs are challenging the classical means of using statistics. Hence, the paper proposed the use of a Generalized Theory of Expected Information or "Zeta Theory". The conjoint event [a,b,c,..] is seen as a rule of association for a,b,c,.. associated with a rule strength I(a;b;c;...) = xi(s,o[a,b,c,..]) - xi (s,e[a,b,c,...]), where xi is the incomplete Zeta Function. Here, o[a,b,c,...] is the observed, and e[a,b,c,..] the expected, frequency of occurrence of conjoint event [a,b,c,...]. The present paper explores how output from this approach might be assembled in a form better suited for decision support. Related to this is the difficulty that the treatment of covariance and multivariance was previously rendered as a "fuzzy association" so that the output would fall into a similar form as the true associations, but this was a somewhat ad hoc approach in which only the final I( ) had any meaning. Users at clinical research sites had subsequently requested an alternative approach in which "effective frequencies" o[ ] and e[ ] calculated from the above variances and used to evaluate I( ) give some intuitive feeling analogous to the association treatment, and this is explored here. Though the present paper is theoretical, real examples are used to illustrate application. One clinical-genomic example illustrates experimental design by identifying data which is, or is not, statistically germane to the study. We also report on some impressions based on applying these techniques in studies of real, extensive patient record data which are now emerging, as well as on molecular design data originally studied in part to test the ability to deduce the effects of simple natural patient sequence variations ("SNPs") on patient protein activity. On the basis of these study experiences, methods of rationalizing and condensing the rules implied by associations and variances between data, as well as discussion of the difficulty of what is meant by "condensed", are presented in the Appendix.

Biomedical Research↗

Degradation of rice bran hemicellulose by Paenibacillus sp. strain HC1: gene cloning, characterization and function of beta-D-glucosidase as an enzyme involved in degradation.

A bacterium (strain HC1) capable of assimilating rice bran hemicellulose was isolated from a soil and identified as belonging to the genus Paenibacillus through taxonomical and 16S rDNA sequence analysis. Strain HC1 cells grown on rice bran hemicellulose as a sole carbon source inducibly produced extracellular xylanase and intracellular glycosidases such as beta-D-glucosidase and beta-D-arabinosidase. One of them, beta-D-glucosidase, was further analyzed. A genomic DNA library of the bacterium was constructed in Escherichia coli and gene coding for beta-D-glucosidase was cloned by screening for beta-D-glucoside-degrading phenotype in E. coli cells. Nucleotide sequence determination indicated that the gene for the enzyme contained an open reading frame consisting of 1,347 bp coding for a polypeptide with a molecular mass of 51.4 kDa. The polypeptide exhibits significant homology with other bacterial beta-D-glucosidases and belongs to glycoside hydrolase family 1. Beta-D-Glucosidase purified from E. coli cells was a monomeric enzyme with a molecular mass of 50 kDa most active at around pH 7.0 and 37 degrees C. Strain HC1 glycosidases responsible for degradation of rice bran hemicellulose are expected to be useful for structurally determining and molecularly modifying rice bran hemicellulose and its derivatives.

Amino Acid Sequence↗

Study of thermal aggregation of oat globulin by laser light scattering.

The heat-induced aggregation of oat globulin was studied using size-exclusion chromatography (SEC) combined with on-line multiangle laser light scattering (MALLS) and quasi-elastic light scattering (QELS). The unheated oat globulin exists as a mixture of hexamer (>95%), trimer, and dimer forms of hexamer. The molecular weight of the hexamer was estimated by MALLS to be 330 000, close to that deduced from the genomic cloned data of the acidic and basic polypeptides of oat globulin. From QELS measurements, it can be predicted that the hexamer exists as two annular trimeric rings, with a diameter of 11.8 nm, placed on top of each other, forming an oblate cylinder with a height of about 8.5 nm. Upon heating at 100 degrees C, the oat globulin hexamers and trimers were dissociated into monomers. The heat-denatured monomers, probably assuming an extended structure, were associated to form small aggregates, which were further aggregated to high molecular weight complexes. Upon further heating (60 min), the soluble aggregates were associated to form insoluble aggregates. Aggregation of oat globulin occurred at a much faster rate at 110 degrees C. The results indicate that the SEC-MALLS-QELS system is suitable for studying thermal aggregation of food proteins.

Avena↗

GSTM1 and CYP1A1 polymorphisms, tobacco, air pollution, and lung cancer: a study in rural Thailand.

OBJECTIVES: The Lampang Province is situated in the northern region of Thailand. Incidence rates of lung cancer are high for Asian standards, particularly in women. This study was conducted to quantify the risk of lung cancer associated with exposures prevalent in the area and to investigate possible interactions with genetic susceptibility. The presence of several large open-cast coal mines from 1955 close to electricity-generating plants was a particular focus of concern. METHODS: Two-hundred and eleven cases of primary lung cancers diagnosed in 1993 to 1995 and residents in the province were recruited at the Lampang Provincial Hospital (main referral center for treatment of the disease). Two sets of controls, frequency-matched to the cases by sex and age, were recruited (a) from the resident population (202 interviewed) and (b) from patients admitted to the hospital for diseases predominantly unrelated to tobacco smoking (211 interviewed). Sociodemographic information, complete residential history, and characteristics of the household (place of cooking, cooking fuel, and heating fuels), occupational history, and history of tobacco smoking were obtained by interview. Cases and controls ( approximately 50% of the population-based series) provided a blood sample. A point source air pollution exposure index was calculated for each village/township reported in residential histories based on the linear distance from the Mae Moh Center (the area of the electricity-generating plants), the year-specific gaseous (SO(2) and NO(2)) or total suspended particulate emissions from the Mae Moh Power Plant, and the percentage of wind from the center. Odds ratios (OR) for the disease associated with categorical variables were estimated within unconditional logistic regression. Extraction of genomic DNA and genotyping of variants in CYP1A1 and GSTM1 were conducted to assess the extent of modification of risk by these genes that are involved in the metabolism of polycyclic aromatic hydrocarbons, a common component of the exposures. RESULTS: Overall, there was no evidence of relevant differences in the socioeconomic level of the three groups. The two control sets were similar with respect to lifelong tobacco habit and were subsequently pooled in analyses. Never-smokers were 7% of men and 33% of women. Smoking of local traditional products unfiltered and high in tar content is a common habit in the rural female population. ORs associated with smoking increased with duration of the habit and average daily amount, being 4.9 [95% confidence interval (95% CI), 2.5-9.7] for smokers of > or =7 cigarettes/d and 3.3 (95% CI, 1.7-6.2) for duration of 41 years or longer compared with nonsmokers. Smoking of local products was associated with an independent OR of 3.1 (95% CI, 1.7-5.6) adjusted for lifelong cumulative amount of tobacco smoked. Although most smokers had the habit for at least 16 years, the daily consumption was low compared with Western standards. Other potential sources of exposure to lung carcinogens (emission from the power-generating plants and domestic burning of coal and wood for cooking and heating) were not associated with increased risk of lung cancer. None of the three polymorphisms examined increased the risk of lung cancer or modified the risk associated with tobacco smoking. CONCLUSION: In this rural population, 96% of male and 64% of female lung cancer incidence were explained by tobacco smoking. None of the potential sources of air pollution deriving from the combustion of coal and wood, or polymorphisms in the CYP1A1 gene or deletion of the GSTM1 had an effect on the risk of lung cancer, either together or separately.

Age Factors↗

Identification of Prognostic Gene Signatures for Survival of Patients With Phaeochromocytoma, Paraganglioma, and Other Tumor Types.

BACKGROUND/AIM: Tumor treatments remain unsatisfactory, as many patients continue to die despite therapy. There is an urgent need for novel drug targets, particularly for rare tumors. In this study, we sought to identify genes with prognostic significance for survival in patients with phaeochromocytoma or paraganglioma. We also examined whether these genes are relevant in other tumor entities. PATIENTS AND METHODS: We mined the TCGA-based KM Plotter and studied 186 risk genes for phaeochromocytoma and paraganglioma. RESULTS: Using Kaplan-Meier statistics, we performed 3,163 calculations based on 7,489 tumor biopsies and identified a 2-gene signature for phaeochromocytoma/paraganglioma (AQP4, FAM84H). Since the 186 risk genes are not exclusively related to the development of phaeochromocytoma/paraganglioma alone, we also investigated their prognostic relevance in 17 other tumor types. A clustered 12-gene signature has been found common in four other tumor entities (liver hepatocellular carcinoma, renal clear cell carcinoma, renal papillary cell carcinoma, lung adenocarcinoma). This signature consisted of BUB1, BUB1B, CDK1, CENPA, CKAP2L, IQGAP3, MKI67, NDC80, PBK, RRM2, TOP2A, and TTK. CONCLUSION: Our analysis provides a basis for the development of a novel prognostic test to predict the survival time of patients.

Kaplan-Meier analysis↗

A text-mining analysis of the human phenome.

A number of large-scale efforts are underway to define the relationships between genes and proteins in various species. But, few attempts have been made to systematically classify all such relationships at the phenotype level. Also, it is unknown whether such a phenotype map would carry biologically meaningful information. We have used text mining to classify over 5000 human phenotypes contained in the Online Mendelian Inheritance in Man database. We find that similarity between phenotypes reflects biological modules of interacting functionally related genes. These similarities are positively correlated with a number of measures of gene function, including relatedness at the level of protein sequence, protein motifs, functional annotation, and direct protein-protein interaction. Phenotype grouping reflects the modular nature of human disease genetics. Thus, phenotype mapping may be used to predict candidate genes for diseases as well as functional relations between genes and proteins. Such predictions will further improve if a unified system of phenotype descriptors is developed. The phenotype similarity data are accessible through a web interface at http://www.cmbi.ru.nl/MimMiner/.

Chromosome Mapping↗

Establishment of an in vitro culture and regeneration protocol for the native Chilean grass Polypogon australis Brong.

Polypogon australis Brong. is a native Chilean grass frequently found colonizing metal-rich mine tailings, yet it lacks an established in vitro regeneration system to support controlled physiological and biotechnological studies. Here, we report a reproducible protocol for seed germination, callus induction, and plant regeneration using coleoptile-mesocotyl explants. Surface-sterilized seeds were germinated on Murashige and Skoog (MS) medium supplemented with sucrose, achieving a cumulative germination percentage of 47.67 ± 3.15% after 15 days. The coleoptile-mesocotyl explant proved highly responsive to culture on callus induction medium (CIM) supplemented with dicamba, resulting in a callus induction frequency of 30.55 ± 11.96% after 3-5 weeks. Induced calli were predominantly embryogenic, with embryogenic calli representing 65.42 ± 8.61% of the total callus population. Embryogenic calli regenerated complete plantlets with a regeneration efficiency of 45.0 ± 23.3%. Organogenic structures, including primary shoots and roots, developed directly from embryogenic calli maintained on callus induction medium (CIM) supplemented with dicamba, without transfer to a specialized regeneration medium containing organogenesis-promoting growth regulators. After the initiation of organogenesis, cultures were exposed to a 16 h light/8 h dark photoperiod while remaining on CIM, and regenerated plantlets were subsequently transferred to MS+10 S medium for further growth and elongation. This study establishes the first complete in vitro regeneration system for P. australis, providing a practical framework for future physiological studies, large-scale propagation, genetic transformation, and genome engineering applications in this ecologically relevant native Chilean grass.

Regeneration↗