A. Vicario

Mutation of E2F2 in Mice Causes Enhanced T Lymphocyte Proliferation, Leading to the Development of Autoimmunity

E2Fs are important regulators of proliferation, differentiation, and apoptosis. Here we characterize the phenotype of mice deficient in E2F2. We show that E2F2 is required for immunologic self-tolerance. E2F2(-/-) mice develop late-onset autoimmune features, characterized by widespread inflammatory infiltrates, glomerular immunocomplex deposition, and anti-nuclear antibodies. E2F2-deficient T lymphocytes exhibit enhanced TCR-stimulated proliferation and a lower activation threshold, leading to the accumulation of a population of autoreactive effector/memory T lymphocytes, which appear to be responsible for causing autoimmunity in E2F2-deficient mice. Finally, we provide support for a model to explain E2F2s unexpected role as a suppressor of T lymphocyte proliferation. Rather than functioning as a transcriptional activator, E2F2 appears to function as a transcriptional repressor of genes required for normal S phase entry, particularly E2F1.

Single-strand conformational polymorphism and sequence polymorphism of Mhc-DRB in Latxa and Karrantzar sheep: implications for Caprinae phylogeny.

Abstract. Single-strand conformational polymorphism analysis and DNA sequencing were used to characterize Mhc-DRB second exon variability in the Latxa and Karrantzar breeds of sheep. The presence of more than two sequences in some animals indicates that alleles of two different loci have been amplified. Six new alleles were identified by sequencing. The allele frequency distribution of the DRB1 gene is striking, with two alleles accounting for half of the gene pool in both breeds under study. The most frequent allele in both breeds was the same (named DRB1*0702), with some specific amino acids: Tyr in position 31 and Thr in 51. A species variability analysis was also performed including the entire set of sheep DRB exon 2 sequences. Based on the patchwork patterns of different alleles, interallelic recombination appears to be playing a significant role in the generation of allelic diversity at this locus in sheep. The phylogenetic tree of all known Caprinae DRB sequences shows that certain alleles from one species are more closely related to those from other species than they are to each other. Allele DRB1*0702 merits special attention due to its high similarity to the Mufflon allele. As this is the most frequent in both breeds analyzed, one can hypothesize that in sheep, both Mufflon and Argali have had different influences depending on the sheep breed under study and that the relationship between domestic sheep and Mufflon is greater than previously thought. The data generated in this study can serve as a basis for developing a typing assay for the sheep DRB genes in the Latxa and Karrantzar populations.

Quantitative analysis of two-dimensional gel electrophoresis protein patterns: a method for studying genetic relationships among Globodera pallida populations

A method based in two-dimensional protein gel electrophoresis has been developed in order to improve the analysis of genetic relationships among populations of Globodera. It has been used to estimate genetic divergence among nine Globodera pallida nematode populations. Sixty-one anonymous polypeptide spots were resolved using silver-stained high-resolution 2D gels and they were quantified in each population to establish genetic variation among G. pallida populations. The results of this analysis were compared with those obtained after a study of allelic frequency variation, which was carried out using seven previously described loci. Genetic distances among populations were calculated by means of both studies, the quantitative analysis and the allelic frequency variation, and phylogenetic trees were constructed for each type of analysis. A correlation analysis between the two distance matrices was carried out and a bootstrap analysis was performed to determine the strength of the clusters obtained with each method. The results obtained support the idea that quantitative protein analysis can be successfully applied to phylogenetic analysis of G. pallida populations.

Distribution of Cepaea nemoralis according to climatic regions in Spain

121 Populations of Cepaea nemoralis were sampled in Spain. In an area which extends from the coast of the Bay of Biscay to 182 km inland, following the meridian 3° west of Greenwich, and which has a width of approximately 40 km. In this study, we analysed the relationships between the populations and some selective agents, such as predation by Turdus ericetorum and climatic factors. These latter are represented by indirect parameters, such as altitude and distance from the sea, and direct parameters such as rainfall or temperatures. Visual selection is unimportant in the sampled populations. It was observed that our area of study is subdivided into 3 zones: Zone 1. Transitional and Zone 2, which have very different phenotype frequencies. What is more, these Zones correspond to very different climatic regions. Zone 1 is located in the climatic region known as “Green Iberia”. The most frequent phenotypes of Cepaea nemoralis are the pale ones. Zone 2 is located in “Brown Iberia”, and the most frequent phenotypes are the dark ones. Therefore we believe that in the populations sampled, one or more climatic factors are operating, and presumably causing the subdivision of these populations into Zones 1 and 2.

Acid Phosphatase, Adenosine Deaminase and Esterase D Polymorphisms in the Spanish Basque Population

The 3 red-cell polymorphic systems acid phosphatase (ACP), adenosine deaminase (ADA) and esterase D (ESD) have been studied in a random sample of 1,112 individuals from the Basque country: The allelic frequencies obtained were ACP*A = 0.275, ACP*B = 0.718 and ACP*C = 0.007; ADA*2 = 0.021, and, ESD*2 = 0.066. The allelic frequencies have been compared with those of other Basque and other European populations. In comparison with Basques, significant differences were detected only for ACP, whereas as regards other Europeans significant differences were obtained with practically all the populations compared for the 3 genetic systems studied. The low values of the less frequent alleles, especially that for the ACP*C allele which is the lowest reported in Europe, are noteworthy.

Some red cell enzymes and haptoglobin gene frequencies in two Basque regions and León

A study was conducted to determine the distribution of phenotypes and gene frequencies of haptoglobin, phosphoglucomutase 1, esterase D, 6-phosphogluconate dehydrogenase and three monomorphic systems SOD, sMDH and NADH DIA I. Results obtained from two Basque regions and León were compared with those from other Spanish populations. Gene frequencies observed in the León sample were similar to those obtained from the other Spanish samples. The Basque samples differed from the other Spanish populations in the gene frequencies of esterase D.

North/South differentiation in the distribution of Cepaea nemoralis in Spain

Sixteen enzymatic loci of Cepaea nemoralis were studied in an area of 180 km long by 40 km wide in northern Spain. Two new polymorphic loci DIA and GLO, and two monomorphics, ARYL and β-GAL are described.The analysis of principal components groups the populations in two geographical areas, in the north and south of the sampling area. There is also an intermediate area between them. Heterozygosity in the northern area is significantly higher than in the southern one. Heterozygosity seems to diminish in unfavourable conditions (greater dryness or greater altitude), which is in accordance with the niche width variation hypothesis. There seems to exist an association between alleles of GLO and PGM and altitude.The geographical areas created by the biochemical polymorphism coincide with those of the visible polymorphism, which in turn correspond to climatic zones. The northern area, according to visible and biochemical polymorphism is located in the so-called “Green Iberia”, and the southern area in “Brown Iberia”. The intermediate area corresponds to the area of climatic transition between them. These areas could correspond to “geographical races” of Cepaea nemoralis.Climatic selection may be acting upon some loci such as PGM and GLO while in others random drift could be the cause of heterogeneity.

Allozyme variation in populations of Cepaea nemoralis from Northern Spain

Allozyme frequencies at eleven gene loci have been tested electrophoretically in 46 populations of the land snail Cepaea nemoralis from the North of Spain. There is some geographic differentiation for molecular polymorphism which coincides to some small extent with the two main climatic regions in the Iberian peninsula, “green” and “brown” Iberia. However, there are no significant correlations between gene frequencies and climatic parameters. At least, part of this geographic change may have emerged through genetic drift, with a counterbalanced action of drift and climatic selection associated with a restricted gene flow, to promote a different genetic structure of C. nemoralis populations in each climatic region.

Polymorphism in Cepaea Hortensis in marginal populations in Spain

Cepaea hortensis (Mull) is found in Spain only in the western part of the Iberian mountain range. This is the southernmost limit of its range. The most frequent colour is yellow, brown being very rare. The most frequent band patterns are 12345, fused banded and unbanded. There are associations between maximum and minimum temperatures and pink and effectively unbanded yellow phenotypes. The populations may be grouped into two zones, one located in the north and the other in the south of the sampled area. Visual predation was not observed. The marginal populations studied by us were compared with others from Northern Europe, and it was observed that pink snails are more frequent at the southern limit, and unbanded ones at the northern limit. This was interpreted as a climatic selection.

Some genetic markers in Castillian populations

Haptoglobin, phosphoglucomutase 1 and 6-phosphogluconate dehydrogenase gene frequencies have been found for some Castillian provinces. The NADH diaphorase I, superoxide dismutase, lactate dehydrogenase, soluble oxaloacetate transaminase, soluble malate dehydrogenase, carbonic anhydrase I and carbonic anhydrase II are non-polymorphic red cell enzymes in Caucasoids and we have verified this in Castillian samples.