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A 2.2-kb full length cDNA containing an ORF encoding a putative acetylcholinesterase (AChE) precursor of 673 amino acid residues was obtained by a combined degenerate PCR and RACE strategy from an organophosphate-susceptible Bactrocera oleae strain. A comparison of cDNA sequences of individual insects from susceptible and resistant strains, coupled with an enzyme inhibition assay with omethoate, indicated a novel glycine-serine substitution (G488S), at an amino acid residue which is highly conserved across species (G396 of Torpedocalifornica AChE), as a likely cause of AChE insensitivity. This mutation was also associated with a 35-40% reduction in AChE catalytic efficiency. The I199V substitution, which confers low levels of resistance in Drosophila, was also present in B. oleae (I214V) and in combination with G488S produced up to a 16-fold decrease in insecticide sensitivity. This is the first agricultural pest where resistance has been associated with an alteration in AChE, which arises from point mutations located within the active site gorge of the enzyme.

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SUMMARYIn colonies of the olive fruit fly Dacus oleae maintained on an artificial substrate, an allele of the ADH locus whose frequency in natural populations is about 1 per cent increases in frequency to about 40 per cent within 6 generations of artificial rearing; the allele most common in natural populations suffers a compensatory decrease from 65 per cent to 30 per cent; a third allele is only slightly affected. This rapid genetic change coincides with an initial negative population growth rate followed by gradually increasing rates, an indication that the selection associated with this change has a toll on the colony's growth. Estimation of relative fitnesses shows that under artificial rearing, heterozygotes are on avera twenty times as fit as homozygotes. These are probably the largest selection differentials reported for allozymes, and are comparable only to differentials for tolerance to heavy metals in plants. The hypothesis of linkages of the ADH alleles with other genetic elements (e.g., chromosomal inversions), which are the targets of selection, cannot be excluded. The study demonstrates the types of selection pressures that may operate on newly established colonies of "domesticated" insects and the genetic changes that may result from them.

The rate of allelism of lethals on the O chromosome of Drosophila subobscura in two natural populations and the interpopulation allelism rate are 0.0062, 0.0025 and 0.0058 respectively. They do not differ statistically. It is concluded that the natural populations studied have practically an infinite size. This conclusion is corroborated by ecological data on density and dispersion, and partly by data based on the temporal method. The allelism rate of genes producing male and female sterility was also studied. From the study of the allelism rate for lethal and sterility genes the number of such genes on the O chromosome ofD. subobscura was inferred.

Species and genome relationships among 11 diploid (A and C genomes), five tetraploid (AB and AC genomes) and two hexaploid (ACD genome) Avena taxa were investigated using amplified fragment length polymorphisms (AFLPs) and random amplified polymorphic DNA (RAPD) markers. The two primer pairs used for the AFLP reactions produced a total of 354 polymorphic bands, while 187 reproducible bands were generated using ten RAPD primers. Genetic similarities amongst the entries were estimated using the Jaccard and Dice algorithms, and cluster analyses were performed using UPGMA and neighbor joining methods. Principle coordinate analysis was also applied. The highest cophenetic correlation coefficient was obtained for the Jaccard algorithm and UPGMA clustering method ( r=0.99 for AFLP and r=0.94 for RAPD). No major clustering differences were present between phenograms produced with AFLPs and RAPDs. Furthermore, data produced with AFLPs and RAPDs were highly correlated ( r=0.92), indicating the reliability of our results. All A genome diploid taxa are clustered together according to their karyotype. The AB genome tetraploids were found to form a subcluster within the A(s )genome diploids (AFLPs), indicating their near-autoploid origin. The AC genome tetraploids are clustered to the ACD genome hexaploids. Finally, the C genome diploids form an outer branch, indicating the major genomic divergence between the A and C genomes in Avena.

SUMMARYThree closely related Drosophila species of the "obscura" group have been examined: Dropophila madeirensis, D. guanche and D. subobscura. Some crosses are possible between them and F1 progeny were used in order to clarify chromo. somal homologies. D. madeirensis has the following constitution in relation to D. subobscura: Am+i; J.; En-; 03; U12 while D. guanche has: A,,,+g; J; E; O3+g; U12 (where m and g indicate inversions specific to those species). Some data are also presented on the inheritance of eight different quantitative characters used by some taxonomists to differentiate other palearctic obscura group species.

Three hundred twenty-eight patients were examined and classified according to age (65–69, 70–74, 75–79, and ≥80 years) and degree of male pattern baldness Hamilton/Norwood Class I-VII. In addition, the inferior to superior height of potential temporal, parietal, and occipital donor sites containing at least eight hairs per 4-mm round circle was measured. A schematic drawing of the borders of this “safe” donor area containing permanently hair-bearing scalp with adequate hair density for transplanting is presented.