Technology

An oligonucleotide fingerprint normalized and expressed sequence tag characterized zebrafish cDNA library. Clark M. D. et al. Genome Res. 11, 1594–1602 (2001) [PubMed]

Relatively few genomic resources are available to zebrafish researchers, despite the popularity of this organism among developmental biologists and geneticists. However, a new expressed-sequence-tag (EST) resource has been generated by a large collaborative effort, in which more than 25,000 unique cDNA clones were compiled following the normalization and subtraction of 75,000 clones from two cDNA libraries. Clone uniqueness was ensured by oligonucleotide fingerprinting, which identifies and preclusters similar clones before EST sequencing. Importantly for the zebrafish community, the complete set of clones is publicly available through The Resource Center of the German Human Genome Project (RZPD).

Mouse genetics

Mutations in Mlph , encoding a member of the Rab effector family, cause the melanosome transport defects observed in leaden mice. Matesic, L. E. et al. Proc. Natl Acad. Sci. USA 98, 10238–10243 (2001) [PubMed]

Mammalian pigmentation requires specialized organelles called melanosomes, which synthesize melanin and are transported from melanocytes to, eventually, the hair shaft. Mouse coat-colour mutants have helped to identify components of this complex process, as indeed has the cloning of the gene mutated in leaden mice. Mlph encodes melanophilin, a novel Rab-effector-like protein involved in melanosome transport.

Developmental biology

Sightless has homology to transmembrane acyltransferases and is required to generate active Hedgehog protein. Lee, J. D. & Treisman, J. E. Curr. Biol. 11, 1147–1152 (2001) [PubMed]

Skinny hedgehog, an acyltransferase required for palmitoylation and activity of the Hedgehog signal. Chamoun, Z. et al. Science 2 August 2001 (10.1126/science.1064437) [PubMed]

The conserved family of Hedgehog (Hh) proteins is responsible for important developmental signalling events in many species. Using different genetic screens, these papers identify a new Drosophila gene — called sightless (sit) in the first study and skinny hedgehog (ski) in the second — in the Hedgehog signalling pathway. They show that sit/ski is required in embryonic segmentation, and in eye and wing imaginal tissues, for effective signalling by Hh, but does not affect Hh transcription or accumulation. ski/sit encodes a conserved 500-amino-acid transmembrane enzyme with homology to a family of membrane-bound acyltransferases. Genetic and biochemical experiments indicate that Sit/Ski catalyses an amino-terminal lipid modification of Hh that is essential for its patterning activity.