A cDNA clone coding for a mite allergen of mol wt approximately 14,000 has been isolated and its DNA sequence determined. The native component from mite extracts encoded by this DNA was identified by immunoprobing blots of mite body extract with human IgE eluted from the electroblotted cloned fusion polypeptides derived from the expressed cDNA clone. The clone encodes a polypeptide with a deduced mol wt of 17,460. The deduced amino acid sequence was not homologous to any known protein sequences and it contains no cysteine or tryptophan. On blots, 21 of 38 sera from mite-allergic subjects recognized the cloned material, and this recognition strongly correlated with IgE-binding to the native component on protein blots of mite extract.

The full-length 8\02 cDNA from Arabidopsis fbaliana was isolated using an expressed sequence tag that was homologous to the Escherichia coli biotin synthase gene (BioB). Comparisons of the deduced amino acid sequence from B 1 0 2 with bacterial and yeast biotin synthase homologs revealed a high degree of sequence similarity. The amino terminus of the predicted B102 protein contains a stretch of hydrophobic residues similar in composition to transit peptide sequences. B 1 0 2 is a single-copy nuclear gene in Arabidopsis that is expressed at high levels in the tissues of immature plants. Expression of B 1 0 2 was higher in the light relative to dark and was induced 5-fold during biotin-limited conditions. These results demonstrate that expression of at least one gene in this pathway is regulated in response to developmental, environmental, and biochemical stimuli.

A hybrid transcription factor comprising a fusion of the DNA-binding domain of Saccharomyces cerevisiae GAL4 and the transcription activation domain of maize C1 was expressed in stably transformed Arabidopsis. Additional transgenic lines were created containing test genes controlled by a synthetic promoter consisting of concatemeric copies of the cis-acting site recognized by GAL4 (UASG) fused to a minimal promoter. The GAL4/C1 effector line was crossed to two lines containing a synthetic promoter/GUS fusion. Both histochemical staining and GUS activity assays indicate strong activation of GUS expression was achieved only after crossing. The GAL4/C1 effector line was also crossed to 15 lines containing a synthetic promoter/antisense adenylosuccinate synthetase gene. Severely retarded growth, and in some cases lethality, was observed in 40% of the F1 lines. This system of activation by crossing is generally useful for activating expression of test transgenes.