The repellent effects on nymphal stages of Ixodes ricinus L. of some plant materials have been studied in the laboratory. The plant material consisted of an ethanolic extract from Achillea millefolium L., and volatile oils of birch and/or pine tar, citronella, cloves, eucalyptus, geranium, lavender,
A plasmid, pWEH1, was constructed containing a fusion of the DNA encoding the signal sequence of the Escherichia coli outer-membrane protein A to the 5'-end of a glyceraldehyde-3-phosphate dehydrogenase cDNA from Ricinus communis. When expressed in E. coli, the fusion protein was secreted by the