Concern about genetic alterations in fish populations arising from anthropogenic activities has led to the adaptation and/or development of new tests and techniques that shed light on these alterations. The high number and the reduced size of chromosomes and the long cell cycle associated with most fish species preclude the use of most accepted genotoxicity assays. The purpose of this work was to study the capability of the randomly amplified polymorphic DNA technique to show genotoxic effects induced by chemicals in fish cells. To do that we studied the effect of 0.5 microg/ml mitomycin C (MMC) on an established rainbow trout cell line (RTG-2). To increase the sensitivity of detecting altered copies of DNA and to avoid the presence of false positives and a lack of reproducibility, the amounts of DNA template and primer present in amplification reactions were studied and optimized after comparison between the control and exposed fingerprints for 4, 6 and 8 h. Results show that 5 ng of DNA template and 4 pM chosen primer were optimum to show differences between control and exposed cells and to obtain reproducible results. The results obtained, after optimum conditions were established, show that this system could be useful for the assessment of DNA alterations in in vitro genotoxicity studies.

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The acute toxicity of chlorpyrifos, methylchlorpyrifos, parathion and methylparathion to three age classes of Artemia salina was determined. In general, A. salina 24-h old was less sensitive to these organophosphorous insecticides (OPI) than A. salina 48-h old and A. salina 48-h old was significantly more tolerant than A. salina 72-h old, in contrast, chlorpyrifos was equally toxic to A. salina 48- and 72-h old. There were some differences among the three age classes of A. salina in the relative order of toxicity of OPI tested. The rank order of toxicity to A. salina 48-h old was methylparathion < parathion < methyl-chlorpyrifos < chlorpyrifos, while to A. salina 24- and 72-h old it was methylparathion = parathion < methyl-chlorpyrifos < chlorpyrifos. The protective effect of the cholinergic antagonists atropine, hexamethonium, pirenzepine and 11-(2-((diethyl-amino)methyl)-1-piperidinylacetyl)-5, 11-dihydro-6H-pyrido(2,3-b)-(1,4)-benzodiazepine-6-one (AF-DX 116) and a cholinesterase-reactivating oxime 2-pyridine aldoxime methochloride (2-PAM) on the mortality due to four selected OPI in Artemia salina 24-h old was investigated. The lethal action of OPI tested was completely prevented by pretreatment of Artemia salina 24-h old with 2-PAM (10(-5) M) and atropine (10(-4 )M). However no concentration of hexamethonium, pirenzepine or AF-DX 116 protected 100% of the animals poisoned by LC84 of the OPI selected, maximum protection obtained was 71 to 88%. In contrast, the maximum inhibition of mortality obtained with AF-DX 116 pretreatment was about 55% because this compound was used at concentrations which were non toxic to control Artemia salina. Atropine, hexamethonium, pirenzepine, AF-DX 116 and 2-PAM afforded 50 % protection (IC50) of Artemia salina against mortality by LC84 of the OPI selected at concentrations in the range of 6.62x10(-7)-1.6x10(-6) M, 2. 38x10(-4)-2.05x10(-3)M, 8.91x10(-7)-1.24x10(-6) M, 9.66x10(-8)-1. 34x10(-7 )M, and 1.95x10(-8)-2.73x10(-8 )M, respectively. Pretreatment of atropine plus 2-PAM to determine whether this combination afforded greater inhibition of the lethality induced by four OPI tested than pretreatment with either atropine or 2-PAM alone was investigated. Atropine (10(-5) M) in combination with 2-PAM (10(-7 )M) inhibited completely the acute toxicity of all OPI tested, while the pretreatment with atropine (10(-6) M) plus 2-PAM at the same concentration gave a inhibition of mortality (about 62%) significantly greater than each antagonist alone (about 14 and 46%, respectively).

In apricot, there are two traits related to flower biology that can be a limitation for the breeder: self‐incompatibility and male sterility. Fully mature trees are needed to determine both phenotypes. Molecular biology techniques may provide a potential tool for increasing selection efficiency by means of marker‐assisted selection. In this study, randomly amplified polymorphic DNA markers combined with bulked segregant analysis have been used to search for markers linked to these traits. A screening of 228 primers resulted in a marker linked to male‐fertility (M4‐650). No markers linked to S alleles were obtained. A second approach consisted of the screening of primers in a subset of seedlings and resulted in three markers linked to male‐fertility and two markers linked to the Sc allele. These markers may allow an earlier determination of the phenotype in progenies segregating for these traits.

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