In a sample of 79 genes with multiple introns, 33 showed significant heterogeneity in G+C content among introns of the same gene and significant positive correspondence between the intron and the third codon position G+C content within genes. These results are consistent with selection adding against preferred codons at the start of genes.

Flanking gypsy\su(Hw)BRs can create a chromosomal domain permissible for activity of the chorion gene DNA replication origin, DNA replication is dramatically protected from position effects. Inclusion of only a single gypsy\su(Hw)BR does not detectably protect chorion gene DNA replication origin from position effects.

A 150bp region from -189bp to -39bp encompasses many positive and negative, at least partially degenerate, cis-regulatory elements, which are involved in specifying the highly precise expression of Cp15 during development.

The equilibrium dissociation constant of the usp protein to its response element on Cp15 promoter is determined and compared to the binding activities of other nuclear hormone receptors to their cognate elements.

P element constructs carrying Ecol\lacZ and CAT reporter genes demonstrate that if the 5' untranslated and coding regions of Cp15 are deleted then normal ovarian expression is maintained but tissue specificity is relaxed.

Binding of usp gene product to the Cp15 follicular-specific promoter of Cp15 studied.

Binding of Cf2 proteins to Cp15 promoter studied: Cf2-I and Cf2-II binding is to AT rich regions.

Alternatively spliced versions of chorion transcription factor Cf2 product bind differentially to the Cp15 promoter.

Primarily regulated at the transcriptional level.

Two dimensional gels have been used to map the replication sites within the third chromosome chorion domain during amplification.

5' flanking sequence conservation of Cp15 is very strong between species and extends further upstream than that for Cp18, Cp16 or Cp19.

The Cp15, Cp16, Cp18 and Cp19 genes of the chorion cluster have been characterized in D.melanogaster, D.subobscura, D.virilis and D.grimshawi. The temporally specific follicular expression of Cp15, Cp16, Cp18 and Cp19 and gene organization has been conserved.

Deletion analysis of the chorion gene cluster using P element mediated transformation has identified a 1.5kb region in the vicinity of Cp15 and Cp19 that is important for high chorion gene amplification levels.

mus101^K451, Mcm6^K1214 and fs(1)A1059^K1 mutants interfere with the amplification of the major chorion genes Cp15, Cp16, Cp18, Cp19, Cp36 and Cp38.

A 73bp segment of the proximal 5' flanking DNA contains sequences essential for the tissue-specific expression and the precise "late" temporal regulation of Cp15. At least three adjacent elements are recognizable within the regulatory sequences, two exerting positive regulation and one negative.

Neither Cp15 nor Cp18 transcription is required for amplification.

Tissue and stage specific expression of Cp15 and Cp38 are retained when the genes are removed from the remaining genes of the cluster, and in the absence of amplification.

The complete nucleotide sequence of ACE3, Cp15 and Cp18 has been determined to identify sequences involved in the regulation of chorion gene amplification and expression.

Sequence analysis of Cp15, Cp18 and Cp19 has led to the identification of a specific DNA element that may control tissue specificity of amplification. Sequences have also been found that may recognize DNA-binding proteins and so function in regulating the amplification or expression of the chorion genes.

A specific 3.8kb genomic fragment from the chorion gene cluster at 66D retains the ability to amplify during oogenesis when removed to other locations in the genome.

Probably the locus for which Yannoni and Petri (1980) detected electrophoretic variants by isoelectric focusing.

Encodes S15-1, a chorion protein estimated at 15kD by Waring and Mahowald (1979) and 9.7kD by Petri et al. (1976). Temporal and spatial distribution of expression described by Parks and Spradling (1987).