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J E Richardson

Publications and source records attributed to J E Richardson.

At least 19 recordsLinked to original sources
PubMed2005

Deep Impact: excavating comet Tempel 1.

Deep Impact collided with comet Tempel 1, excavating a crater controlled by gravity. The comet's outer layer is composed of 1- to 100-micrometer fine particles with negligible strength (<65 pascals). Local gravitational field and average nucleus density (600 kilograms per cubic meter) are estimated from ejecta fallback. Initial ejecta were hot (>1000 kelvins). A large increase in organic material occurred during and after the event, with smaller changes in carbon dioxide relative to water. On approach, the spacecraft observed frequent natural outbursts, a mean radius of 3.0 +/- 0.1 kilometers, smooth and rough terrain, scarps, and impact craters. A thermal map indicates a surface in equilibrium with sunlight.

Jupiter↗
PubMed2005

Do farmers reduce genetic diversity when they domesticate tropical trees? A case study from Amazonia.

Agroforestry ecosystems may be an important resource for conservation and sustainable use of tropical trees, but little is known of the genetic diversity they contain. Inga edulis, a widespread indigenous fruit tree in South America, is used as a model to assess the maintenance of genetic diversity in five planted vs. five natural stands in the Peruvian Amazon. Analysis of five SSR (simple sequence repeat) loci indicated lower allelic variation in planted stands [mean corrected allelic richness 31.3 (planted) and 39.3 (natural), P = 0.009]. Concerns regarding genetic erosion in planted Amazonian tree stands appear valid, although allelic variation on-farm is still relatively high.

DNA Primers↗
PubMed2004

Historical biogeography of two cosmopolitan families of flowering plants: Annonaceae and Rhamnaceae.

Annonaceae are a pantropically distributed family found predominantly in rainforests, so they are megathermal taxa, whereas Rhamnaceae are a cosmopolitan family that tend to be found in xeric regions and may be classified as mesothermal. Phylogenetic analyses of these families are presented based on rbcL and trnL-F plastid DNA sequences. Likelihood ratio tests revealed rate heterogeneity in both phylogenetic trees and they were therefore made ultrametric using non-parametric rate smoothing and penalized likelihood. Divergence times were then estimated using fossil calibration points. The historical biogeography of these families that are species rich in different biomes is discussed and compared with other published reconstructions. Rhamnaceae and most lineages within Annonaceae are too young to have had their distribution patterns influenced by break-up of previously connected Gondwanan landmasses. Contrasts in the degree of geographical structure between these two families may be explained by differences in age and dispersal capability. In both groups, long-distance dispersal appears to have played a more significant role in establishing modern patterns than had previously been assumed. Both families also contain examples of recent diversification of species-rich lineages. An understanding of the processes responsible for shaping the distribution patterns of these families has contributed to our understanding of the historical assembly of the biomes that they occupy.

Annonaceae↗
PubMed2001

Rapid diversification of a species-rich genus of neotropical rain forest trees.

Species richness in the tropics has been attributed to the gradual accumulation of species over a long geological period in stable equatorial climates or, conversely, to speciation in response to late Tertiary geological events and unstable Pleistocene climates. DNA sequence data are consistent with recent diversification in Inga, a species-rich neotropical tree genus. We estimate that speciation was concentrated in the past 10 million years, with many species arising as recently as 2 million years ago. This coincides with the more recent major uplifts of the Andes, the bridging of the Isthmus of Panama, and Quaternary glacial cycles. Inga may be representative of other species-rich neotropical genera with rapid growth and reproduction, which contribute substantially to species numbers in the world's most diverse flora.

Biological Evolution↗
PubMed2001

Rapid and recent origin of species richness in the Cape flora of South Africa.

The Cape flora of South Africa grows in a continental area with many diverse and endemic species. We need to understand the evolutionary origins and ages of such 'hotspots' to conserve them effectively. In volcanic islands the timing of diversification can be precisely measured with potassium-argon dating. In contrast, the history of these continental species is based upon an incomplete fossil record and relatively imprecise isotopic palaeotemperature signatures. Here we use molecular phylogenetics and precise dating of two island species within the same clade as the continental taxa to show recent speciation in a species-rich genus characteristic of the Cape flora. The results indicate that diversification began approximately 7-8 Myr ago, coincident with extensive aridification caused by changes in ocean currents. The recent origin of endemic species diversity in the Cape flora shows that large continental bursts of speciation can occur rapidly over timescales comparable to those previously associated with oceanic island radiations.

Ecosystem↗
PubMed2001

The Mouse Genome Database (MGD): integration nexus for the laboratory mouse.

The Mouse Genome Database (MGD) is the community database resource for the laboratory mouse, a key model organism for interpreting the human genome and for understanding human biology and disease (http://www.informatics.jax.org). MGD provides standard nomenclature and consensus map positions for mouse genes and genetic markers; it provides a curated set of mammalian homology records, user-defined chromosomal maps, experimental data sets and the definitive mouse 'gene to sequence' reference set for the research community. The integration and standardization of these data sets facilitates the transition between mouse DNA sequence, gene and phenotype annotations. A recent focus on allele and phenotype representations enhances the ability of MGD to organize and present data for exploring the relationship between genotype and phenotype. This link between the genome and the biology of the mouse is especially important as phenotype information grows from large mutagenesis projects and genotype information grows from large-scale sequencing projects.

Alleles↗
PubMed2001

The Mouse Gene Expression Database (GXD).

The Gene Expression Database (GXD) is a community resource of gene expression information for the laboratory mouse. By combining the different types of expression data, GXD aims to provide increasingly complete information about the expression profiles of genes in different mouse strains and mutants, thus enabling valuable insights into the molecular networks that underlie normal development and disease. GXD is integrated with the Mouse Genome Database (MGD). Extensive interconnections with sequence databases and with databases from other species, and the development and use of shared controlled vocabularies extend GXD's utility for the analysis of gene expression information. GXD is accessible through the Mouse Genome Informatics web site at http://www.informatics.jax.org/ or directly at http://www.informatics.jax.org/menus/expression_menu. shtml.

Animals↗
PubMed2001

Physiological responses of firefighters wearing level 3 chemical protective suits while working in controlled hot environments.

Firefighters in Queensland are exposed to hot, humid weather conditions that contribute to the overall workload encountered during emergency operations. Responding to certain hazardous material incidents requires firefighters to wear fully encapsulated chemical protective suits for a maximum period of 20 minutes. The nature of these suits, combined with workload and environmental conditions, poses a potential heat stress problem for firefighters. This study evaluates the heat-induced physiological responses of firefighters while wearing fully encapsulated chemical protective suits in a series of controlled thermal environments. Heart rate, body (aural) temperature, blood pressure, fluid loss, and a rating of perceived exertion were measured to evaluate the effect of increasing ambient air temperature during the performance of standard tasks. The results of the study indicated that the significant increase in heart rate, body temperature, and blood pressure was directly related to the increase in air temperature. The research indicates that the recommended suit wearing time of 20 minutes provided adequate physiological protection under the research conditions.

Adult↗
PubMed2000

The Mouse Genome Database (MGD): expanding genetic and genomic resources for the laboratory mouse. The Mouse Genome Database Group.

The Mouse Genome Database (MGD) is a comprehensive public database of mouse genomic, genetic and phenotypic information (http://www. informatics.jax.org). This community database provides information about genes, serves as a mapping resource of the mouse genome, details mammalian orthologs, integrates experimental data, represents standardized mouse nomenclature for genes and alleles, incorporates links to other genomic resources such as sequence data, and includes a variety of additional information about the laboratory mouse. MGD scientists and annotators work cooperatively with the research community to provide an integrated, consensus view of the mouse genome while also providing experimental data including data conflicting with the consensus representation. Recent improvements focus on the representation of phenotypic information and the enhancement of gene and allele descriptions.

Animals↗
PubMed2000

GXD: a Gene Expression Database for the laboratory mouse: current status and recent enhancements. The Gene Expresison Database group.

The Gene Expression Database (GXD) is a community resource of gene expression information for the laboratory mouse. The database is designed as an open-ended system that can integrate different types of expression data. New expression data are made available on a daily basis. Thus, GXD provides increasingly complete information about what transcripts and proteins are produced by what genes; where, when and in what amounts these gene products are expressed; and how their expression varies in different mouse strains and mutants. GXD is integrated with the Mouse Genome Database (MGD). Continuously refined interconnections with sequence databases and with databases from other species place the gene expression information in the larger biological and analytical context. GXD is accessible through the Mouse Genome Informatics Web site at http://www.informatics.jax.org/ or directly at http://www.informatics.jax.org/menus/expression_menu.shtm l

Alternative Splicing↗
PubMed2000

A phylogenetic analysis of Rhamnaceae using rbcL and trnL-F plastid DNA sequences.

Previous tribal classifications of Rhamnaceae have been based on fruit characters, resulting in the delimitation of large and otherwise heterogeneous groups. We evaluated the most recent classification with DNA sequences of two regions of the plastid genome, rbcL and trnL-F, from 42 genera of Rhamnaceae and representatives of the related families Elaeagnaceae, Barbeyaceae, Dirachmaceae, Urticaceae, Ulmaceae, Moraceae, and Rosaceae. The trnL-F trees have higher consistency and retention indices than the rbcL trees, and patterns of change in rbcL and trnL-F are compared. The closest relatives of Rhamnaceae are Dirachmaceae and Barbeyaceae, followed by the urticalean families. The plastid trees support the monophyly of the family and provide the basis for a new tribal classification. Three strongly supported clades are identified, but morphological characters could not be found to underpin a formal taxonomic description of these three clades as subfamilies. We therefore only recognize groups that are also defined by morphological characters. The biogeography of Rhamnaceae is discussed with reference to the molecular trees.

Journal Article↗
PubMed1999

GXD: a gene expression database for the laboratory mouse. The Gene Expression Database Group.

The Gene Expression Database (GXD) is a community resource that stores and integrates expression information for the laboratory mouse, with a particular emphasis on mouse development, and makes these data freely available in formats appropriate for comprehensive analysis. GXD is implemented as a relational database and integrated with the Mouse Genome Database (MGD) to enable global analysis of genotype, expression and phenotype information. Interconnections with sequence databases and with databases from other species further extend GXD's utility for the analysis of gene expression data. GXD is available through the Mouse Genome Informatics Web Site at http://www.informatics.jax.org/

Animals↗
PubMed1999

The Mouse Genome Database (MGD): genetic and genomic information about the laboratory mouse. The Mouse Genome Database Group.

The Mouse Genome Database (MGD) focuses on the integration of mapping, homology, polymorphism and molecular data about the laboratory mouse. Detailed descriptions of genes including their chromosomal location, gene function, disease associations, mutant phenotypes, molecular polymorphisms and links to representative sequences including ESTs are integrated within MGD. The association of information from experiment to gene to genome requires careful coordination and implementation of standardized vocabularies, unique nomenclature constructions, and detailed information derived from multiple sources. This information is linked to other public databases that focus on additional information such as expression patterns, sequences, bibliographic details and large mapping panel data. Scientists participate in the curation of MGD data by generating the Chromosome Committee Reports, consulting on gene family nomenclature revisions, and providing descriptions of mouse strain characteristics and of new mutant phenotypes. MGD is accessible at http://www.informatics.jax.org

Animals↗
PubMed1998

The Mouse Genome Database (MGD): a community resource. Status and enhancements. The Mouse Genome Informatics Group.

The Mouse Genome Database (MGD) is a comprehensive community database that integrates genetic, genomic and phenotypic information about the laboratory mouse. MGD provides detailed information about genes and genetic markers, elemental data from mapping experiments, descriptions of molecular segments including ESTs, probes, and cDNA clones, homology information between mouse and many other mammalian genomes, and phenotypic descriptions of gene mutations, gene function and mouse strains. All data are supported by citations. Interactive graphical displays of cytogenetic, genetic and physical maps are available. User support is provided through dedicated staff, bulletin boards, and user documentation. MGD can be accessed at http://www.informatics.jax.org

Animals↗