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The enzyme ACC oxidase catalyses the last step of ethylene biosynthesis in plants, converting 1-aminocyclopropane-1-carboxylic acid (ACC) to ethylene. We have previously described the isolation and characterization of a cDNA clone (pMEL1) encoding an ACC oxidase homolog from melon (Cucumis melo L.). Here we report the isolation and characterization of three genomic clones, corresponding to three putative members of the ACC oxidase gene family in melon. All are transcriptionally active. The sequences of these genes have been determined. One genomic clone (CM-ACO1), corresponding to the cDNA previously isolated, presents a coding region interrupted by three introns. Its transcription initiation site has been defined with RNA from ripe fruit and ethylene-treated leaves. The other two genes (CM-ACO2, CM-ACO3) have only two introns, at positions identical to their counterparts in CM-ACO1. The degree of DNA homology in the coding regions of CM-ACO2 and CM-ACO3 relative to CM-ACO1 is 59% and 75%, respectively. CM-ACO2 and CM-ACO3 are 59% homologous in their coding regions. These three genes have close homology to PH-ACO3, a member of the ACC oxidase multigene family of petunia. The predicted amino acid sequences of CM-ACO1 and CM-ACO3 are 77% to 81% identical to those encoded by the tomato and petunia genes, while the deduced amino acid sequence of CM-ACO2 shows only 42% to 45% homology. RT-PCR analysis using gene-specific primers shows that the three genes are differentially expressed during development, ethylene treatment and wounding. CM-ACO1 is induced in ripe fruit and in response to wounding and to ethylene treatment in leaves. CM-ACO2 is detectable at low level in etiolated hypocotyls. CM-ACO3 is expressed in flowers and is not induced by any of the stimuli tested.

The isopenicillin N synthetase (IPNS) gene has been isolated from wild-type Penicillium chrysogenum and used as a probe to detect the equivalent gene on Southern blots of genomic DNA from a mutant producing high levels of penicillin. The IPNS gene in this strain is contained within a region of DNA of wild-type restriction pattern that extends for at least 39 kb and is present at between 8 and 16 copies. The steady state level of IPNS mRNA in the mutant producing high levels of penicillin is between 32- and 64-fold of that of the wild type, suggesting that the rate of transcription of some or all of the copies has been increased. In addition we have also shown that both the IPNS mRNA and enzyme is present throughout the growth phase in both strains under the culture conditions used. IPNS enzyme activity is greatly increased in the strain with the high penicillin titre.

The identification of novel genes or groups of genes expressed in prostate cancer may allow earlier diagnosis or more accurate staging of the disease. We describe the assembly and use of a 1877-member microarray representing cDNA clones from a range of prostate cancer stages and grades, precursor lesions and normal tissue. Using labelled cDNA from tumour samples obtained from TURP or radical prostatectomy, analysis of expression patterns identified many up-regulated transcripts. Cell lines were found to over-express fewer genes than diseased tissue samples. 17 known genes were found to over-express more than 4-fold in 4 or more cancers out of 15 cancers. Only 2 genes were over-expressed in 6 out of 15 cancers or more, whilst no genes were consistently found to be over-expressed in all cancer samples. Novel prostate cancer associations for several well characterized genes or full length cDNAs were identified, including PLRP1, JM27, human UbcM2, dynein light intermediate chain 2 and human homologue of rat sec61 . Novel associations with high-grade PIN include: breast carcinoma fatty acid synthase and cDNA DKFZp434B0335 . We shortlist and discuss the most significant over-expressed genes in prostate cancer and PIN, and highlight expression differences between malignant and benign samples. © 2001 Cancer Research Campaign http://www.bjcancer.com