title: Gene discovery in the embryonic chick retina.
abstract: OBJECTIVE
  The chick embryo is a powerful model system for the study of retinal development. However, analysis of gene expression in the chick retina has lagged behind biological studies. The purpose of this study was to identity and characterize genes expressed in the chick embryo retina as candidate molecules involved in the development and function of photoreceptors and other retinal cell types.
  
  
  METHODS
  RNA from embryonic day (ED) 18 White Leghorn chick embryo retinae was used to generate an oligo dT-primed cDNA library. Bacterial colonies representing five thousand individual clones were arrayed onto nylon membranes using a microarray robot. Replicate membranes were hybridized with cDNA probes synthesized from ED 18 retina, brain and liver. Clones that appeared preferentially expressed in retina were identified by homology searches, and their spatial and temporal expression patterns were analyzed by in situ hybridization.
  
  
  RESULTS
  Two hundred and seventy-two clones were identified. Approximately forty percent of the clones represented potential novel genes, including ESTs, hypothetical proteins and clones with no assigned identities. Furthermore, many genes were identified that are the putative chick orthologues of genes cloned from other species. We determined the expression pattern of several clones for which sequence homologies suggested possible roles in transcriptional regulation, apoptosis or intercellular signaling. Their corresponding mRNAs were expressed in the embryonic retina in topographically specific, developmentally regulated patterns.
  
  
  CONCLUSIONS
  We identified and characterized genes in the chick embryo retina using a combination of microarray analysis and in situ hybridization. Analysis of the expression patterns suggests involvement of several of these genes in key events during embryogenesis.
authors.affiliation: Guerrieri Center for Genetic Engineering and Molecular Ophthalmology, Wilmer Eye Institute, Johns Hopkins University School of Medicine, Baltimore, MD 21287-9257, USA.
authors.forename: Abigail S
authors.initials: AS
authors.lastname: Hackam
authors.forename: Rebecca L
authors.initials: RL
authors.lastname: Bradford
authors.forename: Rita N
authors.initials: RN
authors.lastname: Bakhru
authors.forename: Raza M
authors.initials: RM
authors.lastname: Shah
authors.forename: Ronald
authors.initials: R
authors.lastname: Farkas
authors.forename: Donald J
authors.initials: DJ
authors.lastname: Zack
authors.forename: Ruben
authors.initials: R
authors.lastname: Adler
mesh_terms: D000818:Animals; D002642:Chick Embryo; D018076:DNA, Complementary / Q000032:analysis; D016208:Databases, Factual; D005136:Eye Proteins / Q000235:genetics* / Q000378:metabolism; D020869:Gene Expression Profiling / Q000379:methods; D018507:Gene Expression Regulation, Developmental / Q000235:genetics*; D015723:Gene Library; D009693:Nucleic Acid Hybridization / Q000379:methods; D020411:Oligonucleotide Array Sequence Analysis; D012333:RNA, Messenger / Q000378:metabolism; D012160:Retina / Q000196:embryology / Q000378:metabolism*; D017422:Sequence Analysis, DNA; D020539:Sequence Analysis, Protein
chemical_list: D018076:DNA, Complementary; D005136:Eye Proteins; D012333:RNA, Messenger