The Group of Mutagenesis uses Drosophila melanogaster and human lymphocytes as main assay systems.
D. melanogaster has been used since the foundation of the Group, and over this time different research projects have been accomplished:
a) A wide study on the mutagenic effects of different agents (intercalating compunds, pesticides, tritiated water, amongst others), analising several kinds of genetic damage: point mutations, chromosome mutations (chromosome loss and translocations), somatic mutations and induction of mitotic recombination. These studies put emphasis on the improvement of the standard protocol to obtain major sensitivity of the assays, which included the study of the effects induced by modifying the administration route, the dissolvents and the strains used.
b) A comparative study of the sensitivity of three assays that detect somatic mutation induction in Drosophila for evaluating mutagenic and carcinogenic agents. Two of the assays detected genetic alterations in somatic eye cells (white zeste and white ivory) and the other assay detected the effects on somatic cells in the wing (mwh/flr). To evaluate the specificity and sensitivity of these assays, compounds were analised and classified as: mutagenic and carcinogenic, mutagenic but not carcinogenic and neither mutagenic nor carcinogenic.
Currently, the main interests of the Group are:
c) The evaluation and study of the somatic and recombination mutation test using biomarkers from the wing cells (mwh/flr). This research involves the study of the role of different topoisomerase inhibitors in the genetic damage induced by standard mutagens; the study of the genotoxic potential of different pesticides, as well as other chemicals
d) Comparative study of reversion, when exposed to different mutagens, of the strains wi (white ivory) and (wi)4 (white ivory quadruplicated) in both the somatic and germinal line. The revertants are analised at the molecular level to find out the mechanisms of induction of the reversion.
e) Study on the sensitivity of several mutants from the white locus, with mobile elements inserted, to different physical mutagenic agents (thermic shock) and chemicals (alquilant agents) and the molecular characterization of the revertant phenotypes. The mutants used are the w sp1 (white spotted 1), the w 1(white honey) and the w b1(white buff). The molecular characterization is carried out using Southern-blot, Northern-blot and PCR techniques.
f) Identfication of missmatch repair deficient mutants using the AP-PCR method.
The studies using human lymphocytes constitute a more recent research in the Group. The works carried out until now are:
g) Genotoxicity testing of different pesticides, and tritiated water, as well as other compounds, by using chromosome aberrations (CA) and sister chromatid exchanges (SCE) assays.
h) Biomonitoring studies by using CA and SCE tests, on people therapeutically exposed to cytostatic agents, or occupationally to different pesticides
i) Methodological development of the micronucleus test (MN) using cytochalasin-B (CytB), analising the role of its concentration in the expression of MN. The evaluation of the MN frequency was carried out both at a basal level and after the treatments with standard mutagens.
Currently we are working on:
j) The biomonitoring of human populations occupationally exposed to petroleum derivatives or therapeutically treated with I131.
k) The molecular characterization by using thyroid cancer tissue of those mutants arising in the ras and the p53 genes.
l) Use and updating of the single cell gel electrophoresis (SCGE) assay, both in in vitro and in vivo studies.
m) The use of the in situ hibridization techniques (FISH) in the detection and evaluation of the genetic damage (chromosome breakages and aneuploidy) induced, mainly when the MN test is used.
n) The use of PAINTING techniques to evaluate the incidence of stable chromosome aberrations induced, mainly in exposed populations.