Biomedical subjects

William M Gelbart

Publications and source records attributed to William M Gelbart.

22 records · Page 2Linked to original sources

PubMed2002

Comparative genome and proteome analysis of Anopheles gambiae and Drosophila melanogaster.

Comparison of the genomes and proteomes of the two diptera Anopheles gambiae and Drosophila melanogaster, which diverged about 250 million years ago, reveals considerable similarities. However, numerous differences are also observed; some of these must reflect the selection and subsequent adaptation associated with different ecologies and life strategies. Almost half of the genes in both genomes are interpreted as orthologs and show an average sequence identity of about 56%, which is slightly lower than that observed between the orthologs of the pufferfish and human (diverged about 450 million years ago). This indicates that these two insects diverged considerably faster than vertebrates. Aligned sequences reveal that orthologous genes have retained only half of their intron/exon structure, indicating that intron gains or losses have occurred at a rate of about one per gene per 125 million years. Chromosomal arms exhibit significant remnants of homology between the two species, although only 34% of the genes colocalize in small "microsyntenic" clusters, and major interarm transfers as well as intra-arm shuffling of gene order are detected.

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PubMed2002

A deletion-generator compound element allows deletion saturation analysis for genomewide phenotypic annotation.

With the available eukaryotic genome sequences, there are predictions of thousands of previously uncharacterized genes without known function or available mutational variant. Thus, there is an urgent need for efficient genetic tools for genomewide phenotypic analysis. Here we describe such a tool: a deletion-generator technology that exploits properties of a double transposable element to produce molecularly defined deletions at high density and with high efficiency. This double element, called P[wHy], is composed of a "deleter" element hobo, bracketed by two genetic markers and inserted into a "carrier" P element. We have used this P[wHy] element in Drosophila melanogaster to generate sets of nested deletions of sufficient coverage to discriminate among every transcription unit within 60 kb of the starting insertion site. Because these two types of mobile elements, carrier and deleter, can be found in other species, our strategy should be applicable to phenotypic analysis in a variety of model organisms.

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PubMed2002

Universal Fast Walking for direct and versatile determination of flanking sequence.

We report a highly compact system for accelerating direct genome walking. Unlike previous walking techniques, our strategy does not rely on restriction enzymes or ligases, and is therefore unaffected by the availability of useful restriction sites in the flanking region. A complete circumvention of molecular cloning steps qualifies this method for sequencing genome segments that are regarded unclonable, and thus unsequenceable by the traditional methods. A premium was placed on economy of design: the system comprises just four direct reagent additions, in microliter-scale volumes, over the course of a 6-h procedure. The walk range in this method is directly related to the capabilities of the associated polymerase blend, indicating that it can achieve in excess of 35 kilobases per reaction. It also produces a DNA fingerprint that is distinctive to the flanking sequence. Despite the complexity of banding patterns in these fingerprints, we observed that the reaction products were directly sequenceable. In view of its speed, reliability and generality, we term the described method Universal Fast Walking.

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PubMed2002

Using the P[wHy] hybrid transposable element to disrupt genes in region 54D-55B in Drosophila melanogaster.

Understanding the function of each gene in the genome of a model organism such as Drosophila melanogaster is an important goal. The development of improved methods for uncovering the mutant phenotypes of specific genes can accelerate achievement of this goal. The P[wHy] hybrid transposable element can be used to generate nested sets of precisely mapped deletions in a given region of the Drosophila genome. Here we use the P[wHy] method to generate overlapping, molecularly defined deletions from a set of three P[wHy] insertions in the 54E-F region of chromosome 2. Deletions that span a total of 0.5 Mb were identified and molecularly mapped precisely. Using overlapping deletions, the mutant phenotypes of nine previously uncharacterized genes in a 101-kb region were determined, including identification of new loci required for viability and female fertility. In addition, the deletions were used to molecularly map previously isolated lethal mutations. Thus, the P[wHy] method provides an efficient method for systematically determining the phenotypes of genes in a given region of the fly genome.

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