The sequence of the human genome.

A 2.91-billion base pair (bp) consensus sequence of the euchromatic portion of the human genome was generated by the whole-genome shotgun sequencing method. The 14.8-billion bp DNA sequence was generated over 9 months from 27,271,853 high-quality sequence reads (5.11-fold coverage of the genome) from both ends of plasmid clones made from the DNA of five individuals. Two assembly strategies-a whole-genome assembly and a regional chromosome assembly-were used, each combining sequence data from Celera and the publicly funded genome effort. The public data were shredded into 550-bp segments to create a 2.9-fold coverage of those genome regions that had been sequenced, without including biases inherent in the cloning and assembly procedure used by the publicly funded group. This brought the effective coverage in the assemblies to eightfold, reducing the number and size of gaps in the final assembly over what would be obtained with 5.11-fold coverage. The two assembly strategies yielded very similar results that largely agree with independent mapping data. The assemblies effectively cover the euchromatic regions of the human chromosomes. More than 90% of the genome is in scaffold assemblies of 100,000 bp or more, and 25% of the genome is in scaffolds of 10 million bp or larger. Analysis of the genome sequence revealed 26,588 protein-encoding transcripts for which there was strong corroborating evidence and an additional approximately 12,000 computationally derived genes with mouse matches or other weak supporting evidence. Although gene-dense clusters are obvious, almost half the genes are dispersed in low G+C sequence separated by large tracts of apparently noncoding sequence. Only 1.1% of the genome is spanned by exons, whereas 24% is in introns, with 75% of the genome being intergenic DNA. Duplications of segmental blocks, ranging in size up to chromosomal lengths, are abundant throughout the genome and reveal a complex evolutionary history. Comparative genomic analysis indicates vertebrate expansions of genes associated with neuronal function, with tissue-specific developmental regulation, and with the hemostasis and immune systems. DNA sequence comparisons between the consensus sequence and publicly funded genome data provided locations of 2.1 million single-nucleotide polymorphisms (SNPs). A random pair of human haploid genomes differed at a rate of 1 bp per 1250 on average, but there was marked heterogeneity in the level of polymorphism across the genome. Less than 1% of all SNPs resulted in variation in proteins, but the task of determining which SNPs have functional consequences remains an open challenge.

The genome sequence of Drosophila melanogaster.

The fly Drosophila melanogaster is one of the most intensively studied organisms in biology and serves as a model system for the investigation of many developmental and cellular processes common to higher eukaryotes, including humans. We have determined the nucleotide sequence of nearly all of the approximately 120-megabase euchromatic portion of the Drosophila genome using a whole-genome shotgun sequencing strategy supported by extensive clone-based sequence and a high-quality bacterial artificial chromosome physical map. Efforts are under way to close the remaining gaps; however, the sequence is of sufficient accuracy and contiguity to be declared substantially complete and to support an initial analysis of genome structure and preliminary gene annotation and interpretation. The genome encodes approximately 13,600 genes, somewhat fewer than the smaller Caenorhabditis elegans genome, but with comparable functional diversity.

Identification and characterization of a monoclonal antibody that neutralizes ricin toxicity in vitro and in vivo.

We wanted to identify and characterize MAbs with specificity for the toxic lectin ricin, which could serve as detection reagents in elucidating mechanisms and tissue distribution. Neutralizing MAbs could be developed into immunotherapeutics to reverse clinical intoxications from immunotoxin or to counteract the use of ricin as a terrorist or biological warfare weapon. Two hybridomas, UNIVAX 70 and 138, producing MAbs against ricin were identified by Western blot strip analysis. The antibodies were IgG1 and were specific for the ricin A chain with no ricin B chain cross-reactivity. The MAbs neutralized ricin in vitro in an EL-4 mouse leukemia cell assay and in an in vivo mouse model. The two antibodies recognized the same epitope or overlapping epitopes, based on a competition with one another. All further characterization proceeded on the assumption that they were the same. The MAb UNIVAX 70/138 was characterized in vivo by titrating it against an 18 micrograms/kg (> six LD50) i.v. challenge and by titrating the i.v. toxin challenge against a constant dose of 100 micrograms of passive antibody per mouse. A 4:1 molar ratio of MAb to ricin led to neutralization of > or = 90% of the toxin in vitro. The MAb recognized ricin toxoid prepared by formaldehyde treatment and after conjugation of low molecular weight haptens (based on ELISA) equally as well as it recognized ricin and ricin A chain. The affinity and specificity of UNIVAX 70/138 give it excellent reagent potential, and the toxin-neutralizing capacity makes it at least a log and a half better than the next best candidate immunotherapeutic.