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Conversion by retinoic acid of anterior cells into ZPA cells in the chick wing bud
Conversion by retinoic acid of anterior cells into ZPA cells in the chick wing bud N. Wanek, D. M. Gardiner, K. Muneoka and S. V. Bryant Nature 350, 81-86
Retinoic acid induces polarizing activity but is unlikely to be a morphogen in the chick limb bud S. Noji et al. Nature 350, 83-86 The zone of polarizing activity (ZPA) at the posterior margin of the chick limb bud specifies the anterior-posterior pattern of mesenchymal tissues - a ZPA graft at the anterior margin causes mirror-image duplication of the digit pattern. A similar effect is obtained by implanting a retinoic acid-soaked bead (RA-bead) at the anterior margin. A gradient of retinoic acid, produced by the ZPA,
has thus been implicated in the establishment of anterior-posterior pattern in the chick limb bud. An alternative view of retinoic acid action is suggested by these papers. Wanek et al. demonstrated polarizing activity of anterior limb bud tissue that had been adjacent to an RA-bead for at least 16 h; carry-over of retinoic acid was excluded. Furthermore, Noji et c I. reported a functional
distinction between the ZPA graft and RA bead: the RA-bead, but not the ZPA graft, increased retinoic acid receptor type-13 gene expression. These data indicate that the effects of implanting an RA-bead at the anterior margin of the chick limb bud may result from local induction of a new polarizing region, which itself then specifies anterior-posterior pattern.
The isolated ER-Golgi intermediate compartment exhibits properties that are different from ER and cls-Golgl
A novel multigene family may encode odorant receptors: a molecular basis for odor recognition
cDNA derived from olfactory epithelium RNA, a novel multigene family has been identified. Estimates indicate that the family contains at least 100 members. The genes are believed to encode olfactory receptors because their expression is confined to the olfactory epithelium and the proteins have seven potential membrane-spanning domains, as predicted. Subfamilies show major sequence divergence in the third, fourth and fifth transmembrane segments, suggesting that these form the diverse ligand-binding sites. The cloning of these receptors should lead to further progress in understanding how the diversity and specificity of odour perception is accomplished at both molecular and neural levels.
A. Schweizer, K. Matter, C. M. Ketcham and H-P. Hauri J. Cell Biol. 113, 45-54 Morphological studies have suggested the existence of an intermediate compartment in the secretory pathway between the ER and the Golgi complex. This compartment, which consists of vesicular and tubular structures, is defined by the membrane protein p53. This paper describes the purification of the intermediate compartment, and shows that it is distinct from ER and cis Golgi elements in its polypeptide composition and content of marker enzymes. It should now be possible to test this fraction for the presence of various post-translational modifying enzymes whose locations are still unknown. In addition, a better understanding of the composition of the intermediate compartment may shed light on salvage mechanisms for ER proteins, and on the disruption of membrane traffic by the drug brefeldin A.
L. Buck and R. Axel. Cell 65, 175-187
Olfactory signal transduction is thought to involve G proteins, suggesting the existence of olfactory receptors with the seven transmembrane domains typical of G proteincoupled receptors. By a polymerase chain reaction (PCR) approach, using primers to conserved regions of this receptor superfamily and
TRENDSIN CELLBIOLOGYVOL. 1 JULY1991
SUBSCRIPTION ENQUIRIES Trends in Cell Biology subscriptions are handled from the Barking, UK office. Subscription queries and new subscriptions should be addressed to Trends Subscriptions Department, Eisevier Science Publishers Ltd, Crown House, Linton Road, Barking, Essex IG11 8JU, UK. Tel. +44 (81) 594 7272 Fax +44 (81) 594 5942 13
Retinoic acid induces polarizing activity but is unlikely to be a morphogen in the chick limb bud S. Noji et al. Nature 350, 83-86 The zone of polarizing activity (ZPA) at the posterior margin of the chick limb bud specifies the anterior-posterior pattern of mesenchymal tissues - a ZPA graft at the anterior margin causes mirror-image duplication of the digit pattern. A similar effect is obtained by implanting a retinoic acid-soaked bead (RA-bead) at the anterior margin. A gradient of retinoic acid, produced by the ZPA,
has thus been implicated in the establishment of anterior-posterior pattern in the chick limb bud. An alternative view of retinoic acid action is suggested by these papers. Wanek et al. demonstrated polarizing activity of anterior limb bud tissue that had been adjacent to an RA-bead for at least 16 h; carry-over of retinoic acid was excluded. Furthermore, Noji et c I. reported a functional
distinction between the ZPA graft and RA bead: the RA-bead, but not the ZPA graft, increased retinoic acid receptor type-13 gene expression. These data indicate that the effects of implanting an RA-bead at the anterior margin of the chick limb bud may result from local induction of a new polarizing region, which itself then specifies anterior-posterior pattern.
The isolated ER-Golgi intermediate compartment exhibits properties that are different from ER and cls-Golgl
A novel multigene family may encode odorant receptors: a molecular basis for odor recognition
cDNA derived from olfactory epithelium RNA, a novel multigene family has been identified. Estimates indicate that the family contains at least 100 members. The genes are believed to encode olfactory receptors because their expression is confined to the olfactory epithelium and the proteins have seven potential membrane-spanning domains, as predicted. Subfamilies show major sequence divergence in the third, fourth and fifth transmembrane segments, suggesting that these form the diverse ligand-binding sites. The cloning of these receptors should lead to further progress in understanding how the diversity and specificity of odour perception is accomplished at both molecular and neural levels.
A. Schweizer, K. Matter, C. M. Ketcham and H-P. Hauri J. Cell Biol. 113, 45-54 Morphological studies have suggested the existence of an intermediate compartment in the secretory pathway between the ER and the Golgi complex. This compartment, which consists of vesicular and tubular structures, is defined by the membrane protein p53. This paper describes the purification of the intermediate compartment, and shows that it is distinct from ER and cis Golgi elements in its polypeptide composition and content of marker enzymes. It should now be possible to test this fraction for the presence of various post-translational modifying enzymes whose locations are still unknown. In addition, a better understanding of the composition of the intermediate compartment may shed light on salvage mechanisms for ER proteins, and on the disruption of membrane traffic by the drug brefeldin A.
L. Buck and R. Axel. Cell 65, 175-187
Olfactory signal transduction is thought to involve G proteins, suggesting the existence of olfactory receptors with the seven transmembrane domains typical of G proteincoupled receptors. By a polymerase chain reaction (PCR) approach, using primers to conserved regions of this receptor superfamily and
TRENDSIN CELLBIOLOGYVOL. 1 JULY1991
SUBSCRIPTION ENQUIRIES Trends in Cell Biology subscriptions are handled from the Barking, UK office. Subscription queries and new subscriptions should be addressed to Trends Subscriptions Department, Eisevier Science Publishers Ltd, Crown House, Linton Road, Barking, Essex IG11 8JU, UK. Tel. +44 (81) 594 7272 Fax +44 (81) 594 5942 13