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Biomedical subjects

S Yarfitz

Publications and source records attributed to S Yarfitz.

9 recordsLinked to original sources
PubMed2000

A library-based bioinformatics services program.

Support for molecular biology researchers has been limited to traditional library resources and services in most academic health sciences libraries. The University of Washington Health Sciences Libraries have been providing specialized services to this user community since 1995. The library recruited a Ph.D. biologist to assess the molecular biological information needs of researchers and design strategies to enhance library resources and services. A survey of laboratory research groups identified areas of greatest need and led to the development of a three-pronged program: consultation, education, and resource development. Outcomes of this program include bioinformatics consultation services, library-based and graduate level courses, networking of sequence analysis tools, and a biological research Web site. Bioinformatics clients are drawn from diverse departments and include clinical researchers in need of tools that are not readily available outside of basic sciences laboratories. Evaluation and usage statistics indicate that researchers, regardless of departmental affiliation or position, require support to access molecular biology and genetics resources. Centralizing such services in the library is a natural synergy of interests and enhances the provision of traditional library resources. Successful implementation of a library-based bioinformatics program requires both subject-specific and library and information technology expertise.

Computational Biology↗
PubMed1994

An eye-specific G beta subunit essential for termination of the phototransduction cascade.

Heterotrimeric G proteins couple various receptors to intracellular effector molecules. Although the role of the G alpha subunit in effector activation, guanine nucleotide exchange and GTP hydrolysis has been well studied, the cellular functions of the G beta subunits are less well understood. G beta gamma dimers bind G alpha subunits and anchor them to the membrane for presentation to the receptor. In specific systems, the G beta subunits have also been implicated in direct coupling to ion channels and to effector molecules. We have isolated Drosophila melanogaster mutants defective in an eye-specific G-protein beta-subunit (G beta e), and show here that the beta-subunit is essential for G-protein-receptor coupling in vivo. Remarkably, G beta mutants are also severely defective in the deactivation of the light response, demonstrating an essential role for the G beta subunit in terminating the active state of this signalling cascade.

Animals↗
PubMed1993

Pertussis toxin expression in Drosophila alters the visual response and blocks eating behaviour.

Pertussis toxin inactivates certain G-proteins by introducing an ADP-ribose group near the carboxyl-terminus of the alpha-subunit. The major pertussis toxin substrate in Drosophila tissues is Go alpha. We introduced a pertussis toxin gene under control of the hsp70 heat-shock promoter into the Drosophila genome. When heat-shocked, transformed flies produce active pertussis toxin which ADP-ribosylates endogenous Go alpha. Pertussis toxin is expressed in photoreceptors, in the lamina of the eye and in epithelial cells lining the gut. As expected from the absence of Go alpha in photoreceptors, pertussis toxin does not affect the photoreceptor component of the Drosophila visual response. However, it abolishes light on- and off-transients in the electroretinogram. These transients normally arise from the lamina, a tissue where Go alpha transcripts have been detected. Pertussis toxin expression also blocks embryonic development and shortens the lifetime of adult Drosophila. Following heat-shock, transformed adults are active, but they fail to take up nutrients because they stop eating. High energy metabolites are significantly depleted shortly after pertussis toxin expression is induced and the flies die within 48 h.

Adenosine Diphosphate Ribose↗
PubMed1991

A G beta protein in the Drosophila compound eye is different from that in the brain.

A G protein beta subunit gene (Gbe) is expressed only in the eyes of adult D. melanogaster. This gene was identified by probing a Drosophila head cDNA expression library with monoclonal antibodies to a previously characterized Drosophila G protein beta subunit (Gbb). Immunoblot and Northern analyses demonstrate that Gbe protein and mRNA is not present in Drosophila mutants that lack eyes. Immunocytochemical and in situ hybridization analyses further demonstrate that Gbe is expressed in the eyes but not in the brain, whereas Gbb is abundantly expressed in the brain. The Gbe product is approximately 45% identical to previously identified G beta subunits and defines a new G beta class. Its localization suggests a possible role in phototransduction.

Amino Acid Sequence↗
PubMed1989

The Drosophila Go alpha-like G protein gene produces multiple transcripts and is expressed in the nervous system and in ovaries.

Drosophila melanogaster cDNA clones coding for the alpha subunit of a Go-like G protein have been isolated. The sequence of two cDNA clones shows there is alternative splicing in the 5'-coding region which, on conceptual translation, would give rise to two proteins with slightly different amino termini. A partial genomic clone indicates there are four introns in the carboxyl-terminal half of the clone. Two transcripts, 3.8 and 5.3 kilobases long, are expressed at a high level in the heads of adult flies and also in larvae, pupae, and embryos. Hybridization of the cDNA probes to sections of adult flies indicates the RNA is present predominantly in nervous tissue (in the cortex of the brain and the thoracic ganglion); it is also expressed in the ovaries. Transcripts corresponding to both cDNAs are present in the central nervous system, but only one of them is found in detectable levels in the ovaries. The gene maps to 47A on the Drosophila second chromosome.

Amino Acid Sequence↗
PubMed1988

Cloning of a Drosophila melanogaster guanine nucleotide regulatory protein beta-subunit gene and characterization of its expression during development.

A Drosophila melanogaster gene encoding a protein with greater than 80% sequence identity to the beta subunits of mammalian guanine nucleotide-binding regulatory proteins (G proteins) has been cloned. The gene, which was mapped to 13F on the X chromosome by in situ hybridization, was cloned from a Drosophila genomic library by using a bovine transducin beta-subunit cDNA probe. Genomic DNA blot hybridization analysis indicated that there is a single Drosophila G-protein beta-subunit gene. Multiple transcripts were detected throughout development; in adult flies the mRNA is expressed at higher levels in heads than in bodies. The proposed coding region is uninterrupted by introns, but there is evidence for differential mRNA splicing in the 5' nontranslated region.

Amino Acid Sequence↗
PubMed1984

Urinary glucuronidase and arylsulfatases in identical twins of bladder cancer patients.

Studies showing that bladder cancer patients have unusually high levels of urinary beta-glucuronidase and arylsulfatases A and B led to the suggestion that these urinary enzymes may participate in bladder cancer etiology. An alternative explanation of the high levels of these urinary enzymes in bladder cancer patients is that the disease itself causes the elevation. Since the levels of these enzymes are genetically determined, measuring these enzymes in healthy identical twins of bladder cancer patients can test whether high enzyme levels occurred prior to bladder cancer. Five healthy identical cotwins of bladder cancer patients, together with matched controls, were measured for urinary beta-glucuronidase, arylsulfatases A and B, and two other lysosomal enzymes as controls, alpha- and beta-galactosidases. The mean levels of all five enzymes were not very different in the cotwins and controls, suggesting that high levels of urinary enzymes observed in bladder cancer patients are a consequence of disease rather than occurring prior to disease and contributing to its etiology.

Cerebroside-Sulfatase↗