Sorghum is an important target for plant genomic mapping because of its adaptation to harsh environments, diverse germplasm collection, and value for comparing the genomes of grass species such as corn and rice. The construction of an integrated genetic and physical map of the sorghum genome (750 Mbp) is a primary goal of our sorghum genome project. To help accomplish this task, we have developed a new high-throughput PCR-based method for building BAC contigs and locating BAC clones on the sorghum genetic map. This task involved pooling 24,576 sorghum BAC clones (∼4× genome equivalents) in six different matrices to create 184 pools of BAC DNA. DNA fragments from each pool were amplified using amplified fragment length polymorphism (AFLP) technology, resolved on a LI-COR dual-dye DNA sequencing system, and analyzed using Bionumerics software. On average, each set of AFLP primers amplified 28 single-copy DNA markers that were useful for identifying overlapping BAC clones. Data from 32 different AFLP primer combinations identified ∼2400 BACs and ordered ∼700 BAC contigs. Analysis of a sorghum RIL mapping population using the same primer pairs located ∼200 of the BAC contigs on the sorghum genetic map. Restriction endonuclease fingerprinting of the entire collection of sorghum BAC clones was applied to test and extend the contigs constructed using this PCR-based methodology. Analysis of the fingerprint data allowed for the identification of 3366 contigs each containing an average of 5 BACs. BACs in ∼65% of the contigs aligned by AFLP analysis had sufficient overlap to be confirmed by DNA fingerprint analysis. In addition, 30% of the overlapping BACs aligned by AFLP analysis provided information for merging contigs and singletons that could not be joined using fingerprint data alone. Thus, the combination of fingerprinting and AFLP-based contig assembly and mapping provides a reliable, high-throughput method for building an integrated genetic and physical map of the sorghum genome.[The sequence data described in this paper have been submitted to the GenBank data library under accession no. AF218263.]Integrated genetic and physical genome maps are extremely valuable for map-based gene isolation, comparative genome analysis, and as sources of sequenceready clones for genome sequencing projects. Various methods have been developed for assembling physical maps of complex genomes. One of the best characterized approaches uses restriction enzymes to generate large numbers of DNA fragments from genomic subclones (Brenner and Livak 1989;Gregory et al. 1997;Marra et al. 1997). These DNA fingerprints are compared to identify related clones, and to assemble overlapping clones in contigs. The utility of fingerprinting for ordering a complex genome is limited, however, due to variation in DNA migration from gel to gel, the presence of repetitive DNAs, unusual distribution of restriction sites and skewed clone representation. Moreover, fingerprinting, unless combined with other methods, does not link genomic clones directly to gen...

This cross-national study examined preparation for and psychological functioning following Hurricane Georges in the U.S. Virgin Islands, Puerto Rico, Dominican Republic, and the United States. Four to five weeks after the storm made landfall, 697 college students (222 men, 476 women) completed a questionnaire assessing demographic characteristics, preparation, social support, resource loss, and symptoms associated with acute stress disorder. Location, resource loss (especially personal characteristic resources) and social support accounted for a significant portion of psychological distress variance. The findings support the conservation of resources stress theory (Hobfoll, 1989, 1998). Implications of the findings and future research directions are discussed.

The ω‐6 fatty acid desaturase (FAD2) gene family in soybean [Glycine max (L.) Merr.] consists of at least five members in four regions of the genome and are responsible for the conversion of oleic acid to linoleic acid. Here we report the identification of two new ω‐6 fatty acid desaturase (FAD2) gene copies from soybean expressed sequence tags (ESTs). Four bacterial artificial chromosomes (BACs) containing five FAD2 genes were sequenced to investigate structural and functional conservation between duplicate loci. Sequence comparisons show that the soybean genome is a mosaic, with some duplicate regions retaining high sequence conservation in both genic and intergenic regions, while others have only the FAD2 genes in common. Genetic mapping using SSRs from within the BAC sequences showed that two BACs with high sequence homeology mapped to linkage groups I and O; these groups share syntenic markers. Another BAC mapped to linkage group L. The fourth BAC could not be mapped. Reverse transcriptase–polymerase chain reaction (RT–PCR) analysis of the five FAD2 genes showed that the FAD2‐2B and FAD2‐2C copies were the best candidates for temperature‐dependent expression changes in developing pod tissue. Semiquantitative RT‐PCR confirmed these results, with FAD2‐2C showing upward of an eightfold increase in expression in developing pods grown in cooler conditions relative to those grown in warm conditions. The implications of these results suggest a candidate gene for controlling the levels of linoleic acid in developing pods grown in cooler climates.

PlantGDB (http://www.plantgdb.org/) is a database of molecular sequence data for all plant species with significant sequencing efforts. The database organizes EST sequences into contigs that represent tentative unique genes. Contigs are annotated and, whenever possible, linked to their respective genomic DNA. Genome sequence fragments are assembled similarly. The goal of the PlantGDB web site is to establish the basis for identifying sets of genes common to all plants or specific to particular species by integrating a number of bioinformatics tools that facilitate gene prediction and cross- species comparisons. For species with large-scale genome sequencing efforts, PlantGDB provides genome browsing capabilities that integrate all available EST and cDNA evidence for current gene models (for Arabidopsis thaliana, see the AtGDB site at http://www.plantgdb.org/AtGDB/).

Background: Soybean, Glycine max (L.) Merr., is a well documented paleopolyploid. What remains relatively under characterized is the level of sequence identity in retained homeologous regions of the genome. Recently, the Department of Energy Joint Genome Institute and United States Department of Agriculture jointly announced the sequencing of the soybean genome. One of the initial concerns is to what extent sequence identity in homeologous regions would have on whole genome shotgun sequence assembly.