A simple method for the isolation of allelic series using male-linked translocations

Expression and function of the Drosophila melanogaster ADH in male Ceratitis capitata adults: a potential strategy for medfly genetic sexing based on gene-transfer technology

The aim of development of a Mediterranean fruit fly Ceratitis capitata genetic sexing strain derives from the large scale SIT programmes being carried out to control this pest. Toward this direction, we present here the male-specific expression of the Drosophila melanogaster alcohol dehydrogenase (ADH) in medfly transgenic adults generated by Minos-mediated germ line transformation. This expression pattern is obtained by using a promoter fragment of the male-specific gene MSSP-alpha2 of the medfly. We show that the heterologous enzyme is functional in the medfly oxidizing both ethanol and 2-propanol. Although leading to an approximately twofold increase of total ADH activity in male compared to female transgenic adults, these expression levels are not enough for performing genetic sexing when high doses of environmental alcohol are applied. This could be achieved either by further enhancement of the transgene expression or by generating an Adh- line to host the Minos insertions.

Genetic and cytological mapping of a "Y-2" translocation in the Mediterranean fruit fly Ceratitis capitata

In this paper we analyze genetically and cytologically a Y-chromosome 2 translocation with several markers, some of which are potentially useful for large scale sex separation. The breakpoint of this Y-2 translocation is located at region 6B on the trichogene polytene chromosome map. It is found that, in strains carrying this TY-2, only 40% of the fertilized eggs survived to the adult stage, 26% of them dying as embryos, 27% as larvae, and 7% as pupae. Early lethality is explained by the nonviability of adjacent-1 products of meiosis containing a deletion of section 1A-6B. The reciprocal segregation products, carrying this chromosome segment in triplicate, survive until late stages. By analyzing the phenotype of the individuals we conclude that all markers used in this study are located outside the triplicated region and that the male determining factor is not included in the piece of the Y chromosome translocated to chromosome 2. The male recombination frequencies of several genes located on chromosome 2 relative to the breakpoint of translocation T5038 have also been studied here.

Induction of alcohol dehydrogenase null mutants in the Mediterranean fruit fly Ceratitis capitata

Alcohol dehydrogenase null mutants have been induced with X rays in Ceratitis capitata, for use in a genetic sexing system. A combination of selective medium and electrophoretic screening was used to identify these mutants. The results indicate that they are probably large deletions since no homozygotes were found for any of the induced mutants.

Genetic sexing in the mediterranean fruit fly, Ceratitis capitata, using the alcohol dehydrogenase locus

Using the alcohol dehydrogenase (ADH) locus a genetic sexing system is being developed in the Mediterranean fruit fly Ceratitis capitata based on the sensitivity of ADH null mutations to environmental ethanol. A series of null mutants have been induced at this locus, however, none proved viable as homozygotes. One of these null mutants was translocated to the male determining chromosome and this line can be used for genetic sexing. When larvae from this line were reared on larval medium containing various concentrations of allyl alcohol, 97% of the emerging adults were males; in the absence of the allyl alcohol the sex ratio in the line is distorted in favour of the females. It is proposed that the higher ADH activity of the females (homozygous positive) in comparison with the males (heterozygous null) is responsible for their lower survival in larval medium containing allyl alcohol. ADH converts the allyl alcohol to the lethal ketone. The possible use of this line to sex large populations of medflies for use in sterile insect release programmes is discussed.