P-element-induced male recombination can be produced in Drosophila melanogaster by combining end-deficient elements in trans.

Male recombination, not normally present in Drosophila melanogaster, can be produced at high rates when target P elements at homologous sites are combined in the presence of transposase protein. We have produced a set of elements by in situ deletion of a particular insertion and have found elements that have deletions stretching into either end. Elements were tested in pairs to see whether they complement each other in their ability to induce recombination. The combination of elements that are deficient for the same end produces very little recombination, but the combination of a right-end and a left-end element can generate recombination values higher than given by two complete P[CaSpeR] elements at homologous sites. This strongly suggests that "hybrid" P elements, containing ends from two different elements, can be recognized by transposase protein. We have also examined genotypes containing a normal and an end-deficient element and found that they yield reasonably high levels of recombination. We interpret the resultant gametes from such genotypes as showing that the majority of events in this genotype derive from the association of complementary ends from the same element, whereas the complementary ends from elements in trans associate in only a minority of cases.

Constitutive heterochromatin (C-banding) studies in patients with testicular malignancies.

The heterochromatic index [qh/(p + q) X 100] is a quantitative measure of variations in the heterochromatic regions of C-banded cells which minimizes differential contraction of heterochromatic and euchromatic areas. Heterochromatic indices of the homologues of chromosomes #1, #9, #16, and Y were studied in the genotypes of 48 patients with germinal tumors and in 30 controls. The heterochromatic indices of chromosome #9 in patients showed statistically significant heteromorphism compared with controls. In addition, the heteromorphism was found to increase from the lower malignancy seminoma to the highly malignant teratoma. A similar but statistically nonsignificant pattern was seen in chromosome #16. No statistical difference in the mean of the heterochromatic indices was found in chromosomes #1 and Y. The difference in the mean heterochromatic index in chromosome #9 appeared to be due to an increase in the mean heterochromatic index in chromosome #9 appeared to be due to an increase in the amount of constitutive heterochromatin and not to a decrease.

Studies in a patient with acute leukaemia after lysergide treatment.

The second case of acute leukaemia developing after administration of lysergide is reported. The unusual bone-marrow chromosome pattern and the presence of large cells containing multiple micronucleoli suggest that this association may be causal.

Clinical findings in patients with numerical abnormalities of the X chromosome: a three-year survey of consecutive admissions to a general hospital.

A buccal smear study of 21,634 consecutive patients admitted to a general hospital was carried out over a period of three years. Twenty-eight patients were found to have an X-chromosome abnormality giving an over-all frequency of 1.3 per 1000. There were 19 males with Klinefelter's syndrome and nine females with triple-X syndrome. The sex chromosome abnormality had been diagnosed in only one patient before this study began, but examination after admission to hospital showed that the presence of small testes was an invariable finding in the postpubertal males with Klinefelter's syndrome. No other feature was found which could be considered diagnostic of an X-chromosome abnormality. The frequency of Klinefelter's and triple-X syndromes in this hospital population did not differ from the recorded frequency of these syndromes at birth.

Microsatellite analysis of the Queensland fruit fly Bactrocera tryoni (Diptera: Tephritidae) indicates spatial structuring: implications for population control.

The population structure of a tephritid pest species, the Queensland fruit fly Bactrocera tryoni (Froggatt), has been analysed over a five year period (1994-1998), using six microsatellites. Adult fly samples were collected to cover most regions of eastern and central Australia where the flies are regularly found. Tests for heterogeneity indicated that flies within geographically defined regions were homogeneous. The samples were allocated into five regions, including one very large region, Queensland, which encompasses that portion of the fly's range where breeding can occur year-round. With one exception, the collections from different regions were homogeneous between years, showing a fairly static distribution of the species. However, differences between regions were highly significant. The one case of a change in frequency between years indicated a gradual replacement of flies in a marginal region by flies from the main part of the range. The finding of stability in the distribution of a highly mobile insect is of interest, potentially also for other species which have expanded beyond their native range. It is argued that a contributing reason for this stability may be adaptation to different climatic regimes, and that strategies for control based on this hypothesis afford a reasonable chance of success.