Preservation of 5'-end integrity of a potyvirus genomic RNA is not dependent on template specificity.

Full-length in vitro transcripts of plum pox potyvirus (PPV) genomic RNA with mutations altering the number of 5'-terminal adenosine residues were able to infect Nicotiana clevelandii plants, whereas a mutant with a substitution of adenosine in position 2 by guanosine failed to infect. The genomic 5' end was template-independently repaired during in vivo RNA synthesis producing wild-type viral progeny. Putative models of replication initiation are discussed.

A single nucleotide change in the MNR1 (VCX1/HUM1) gene determines resistance to manganese in Saccharomyces cerevisiae.

Several spontaneous Mn2+-resistant mutants were isolated from Saccharomyces cerevisiae strain W303-1b. All displayed an identical semidominant resistance phenotype. The gene responsible for this phenotype from one of these mutants, as well as that from the wild-type, was cloned and sequenced, which allowed the identification of a single nucleotide change in the former. Further sequencing work with the remaining mutants, as well as with others on the MNAR1 gene (Bianchi et al., 1981), indicated that all displayed the same mutation (mnr1 allele). In addition, MNR1 was shown to correspond to VCX1 and HUM1, which determine a vacuolar membrane protein. The nucleotide sequence has been deposited at EMBL, with Accession No. AJ001272.

Genotoxicity testing of six insecticides in two crosses of the Drosophila wing spot test.

Among the great variety of genotoxicity assays available, the wing spot test in Drosophila melanogaster has some characteristics that make it very suited for the screening of genotoxic activity, i.e., it is an easy and inexpensive assay using a eukaryotic organism in vivo. One of the most interesting characteristics of the assay is its capacity to detect genotoxic activity of promutagens without the necessity of an exogenous metabolic activation system. In this paper we present results obtained with a recently developed high bioactivation cross of the wing spot test (NORR cross). The positive results obtained with the five well-known procarcinogens 7, 12-dimethylbenz[a]anthracene, N-nitrosopyrrolidine, p-dimethylaminoazobenzene, diethylnitrosamine and urethane clearly show that the NORR strains are similar to the other high bioactivation strains previously described, but they lack their methodological disadvantages. We have tested six insecticides, which are characterised by having contradictory results in other genotoxicity tests, using both the standard and the high bioactivation (NORR) cross. The six insecticides analysed are the pyrethroid allethrin, the methylenedioxyphenolic compound piperonyl butoxide, the chlorinated hydrocarbons dieldrin and endrin, and the organophosphates dimethoate and malathion. We obtained negative results for all six compounds. Our results show the suitability of the wing spot test for the evaluation of compounds at the first level of genotoxicity testing.

Genetic polymorphisms of the Basques from Gipuzkoa: genetic heterogeneity of the Basque population.

A random sample of 586 Basque individuals from the province of Gipuzkoa was studied for 16 genetic systems: A1A2B0, Rh, MNSs, P, Lewis, Duffy, Kell, GC, TF, AAT, ACP, AK, ADA, ESD, HP and PGM1. The results of this study indicate that the Basque population of Gipuzkoa presents certain differential values with respect to other Basque series, such as maximum values for RH*cde, AK*2 and PGM1*2+ and minimum for PGM1*1-, while the remaining alleles are located within the range of values found in the Basque population to date. It is suggested that there is intraprovincial heterogeneity, as described for Bizkaia by Aguirre et al. in 1991, and the existence of heterogeneity within the Basque population on an inter-provincial level, backing up previous studies in this respect (by Aguirre et al. in 1989 and Manzano et al. 1993).

Alpha-2-HS-glycoprotein gene frequencies in Basques.

The genetic polymorphism of human alpha 2-HS-glycoprotein (AHSG) was analyzed in a sample of 736 native individuals from the three provinces of the Basque Autonomous Community (Guipúzcoa, Vizcaya and Alava). The Basque population shows the highest frequency of the allele AHSG*3 described to date in European populations. The same is not true for the frequency of allele AHSG*2, which fits well into the genocline described in Europe, in accordance with the adaptive hypothesis.

New contribution to the genetics of the Basques: heterogeneity in the esterase D subtype distribution.

A random sample of 1,491 individuals from three Basque provinces was studied for the red-cell esterase D (ESD) polymorphism by means of isoelectric focusing. The following allele frequencies were observed: Vizcaya, ESD*1 = 0.933, ESD*2 = 0.058, ESD*5 = 0.009; Guipuzcoa, ESD*1 = 0.938, ESD*2 = 0.053, ESD*5 = 0.009; and Alava, ESD*1 = 0.894, ESD*2 = 0.088, ESD*5 = 0.018. The Basques from Vizcaya and Guipuzcoa display the lowest values for allele ESD*5 of any European population studied to date. The value obtained for this allele in the Basque population of Alava is significantly higher than those found in the other two Basque samples. This, together with the fact that Basques from Alava display the lowest ESD*1 frequency of any Basque series, suggests that there are genetic differences between Basque provinces.