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The genetic structure of Aphanius fasciatus populations has been analysed using two mitochondrial DNA (mtDNA) markers (16S rRNA and D-loop) obtained from specimens collected in nine sites from the Venice lagoon, Comacchio saltworks and Corsica. Available GenBank sequences were also included, in order to extend the results on a Mediterranean scale. Genetic polymorphism within the Venice lagoon was very low, with most of the specimens analysed (66% for 16S rRNA and 83% for D-loop) sharing the same haplotype for either of the two markers. The genetic homogeneity found within the Venice lagoon may be the consequence of the northward migration of southern Adriatic populations after the Last Glacial Maximum: mismatch analysis showed indeed clear signs of a rapid demographic and spatial expansion. To explain this genetic homogeneity other hypotheses were also suggested, such as adaptation to the high variability of brackish water habitats, and artificial introductions. On a Mediterranean scale, phylogenetic analyses showed the presence of five distinct geographical lineages: Aegean Sea, Greek coast of the Ionian Sea, Adriatic Sea, Tyrrhenian Sea and Southern Sicily. Analysis of molecular variance revealed a genetic partitioning mainly due to differences between groups presumably due to late Miocene geological events, while less polymorphism was present within groups and populations.

Background: A number of studies which have investigated isolation patterns in human populations rely on the analysis of intra- and inter-population genetic statistics of mtDNA polymorphisms. However, this approach makes it difficult to differentiate between the effects of long-term genetic isolation and the random fluctuations of statistics due to reduced sample size. Aim: To overcome the confounding effect of sample size when detecting signatures of genetic isolation. Subjects and methods: A re-sampling based procedure was employed to evaluate reduction in intra-population diversity, departure from surrounding genetic background and demographic stationarity in 34 Italian populations subject to isolation factors. Results: Signatures of genetic isolation were detected for all three statistics in seven populations: Pusteria valley, Sappada, Sauris, Timau settled in the eastern Italian Alps and Cappadocia, Filettino and Vallepietra settled in the Appenines. However, this study was unable to find signals for any of the statistics analysed in 19 populations. Finally, eight populations showing signals of isolation were found for one or two statistics. Conclusion: The analysis revealed that the use of population genetic statistics combined with re-sampling procedure can help detect signatures of genetic isolation in human populations, even using a single, although highly informative, locus like mtDNA.

The purpose of this study was to determine the phylogeographic structure of the brackish-hypersaline cyprinodont fish Aphanius fasciatus (Valenciennes, 1821), using sequencing and RFLP analysis of a 1,330 bp mitochondrial DNA segment containing part of the 16S rRNA gene as well as the genes for tRNA-Leu, NADH subunit 1 and tRNA-Ile. Individuals were collected from 13 different sites in Greece and Turkey, while seven published A. fasciatus sequences were also included to cover the area of distribution of the species. Pairwise sequence divergence values ranged from 0 to 4.51%. Congruent phylogenies were recovered with maximum likelihood, maximum parsimony and neighbour-joining methods. All analyses revealed two main groups. The first group consists of populations from almost all localities that drain into the Aegean Sea. The second group comprises the remaining population samples, which in some cases seem to consist of population-specific subgroups. Our results show that vicariant events have predominantly affected the evolution of A. fasciatus, with the Messinian salinity crisis having shaped the present genetic structure of its populations. Additionally, the life-history traits of the species, which determine a low potential for dispersal, coupled with the typical fragmentation of brackish-hypersaline water habitats have led to a high degree of isolation of A. fasciatus populations, even at restricted spatial scales. Analysis of the partitioning of the total amount of polymorphism with analyses of molecular variance (AMOVA) gave a value of F ST = 84.6%. Potential conservation policies concerning A. fasciatus should also consider the low-genetic variability in the majority of its populations and the presence of fixed haplotypes in some of them.

Anguis fragilis (Squamata: Anguidae). Sono stati studiati vari individui di tre popolazioni italiane di Anguis fragilis mediante metodi di colorazione standard dei cromosomi. Tutti gli individui studiati mostrano un cariotipo di 2n=44 elementi (20 macro- e 24 microcromosomi). Tre coppie di macrocromosomi (1, 4 e 5) sono metacentrici, la decima coppia è formata da cromosomi subtelocentrici, mentre tutti i rimanenti macrocromosomi sono telocentrici. I risultati ottenuti indicano che le popolazioni italiane di orbettino sono cariologicamente uniformi, ma differiscono dalle popolazioni centro-europee, che hanno cariotipi in cui gli elementi della decima coppia sono telocentrici.

Summary Fanconi anemia (FA) is an autosomal recessive disease characterized by progressive pancytopenia, congenital malformations, and predisposition to acute myeloid leukemia. At least five complementation groups (FA-A–FA-E) have been identified. The relative prevalence of FA-A has been estimated at an average of ∼65% but may widely vary according to ethnic background. In Italy, 11 of 12 patients analyzed by cell-fusion studies were assigned to group FA-A, suggesting an unusually high relative prevalence of this FA subtype in patients of Italian ancestry. We have screened the 43 exons of the FAA gene and their flanking intronic sequences in 38 Italian FA patients, using RNA-SSCP. Ten different mutations were detected: three nonsense and one missense substitutions, four putative splice mutations, an insertion, and a duplication. Most of the mutations are expected to cause a premature termination of the FAA protein at various sites throughout the molecule. Four protein variants were also found, three of which were polymorphisms. The missense mutation D1359Y, not found in chromosomes from healthy unrelated individuals, was responsible for a local alteration of hydrophobicity in the FAA protein, and it was likely to be pathogenic. Thus, the mutations so far encountered in the FAA gene are essentially all different. Since screening based on the analysis of single exons by genomic DNA amplification apparently detects only a minority of the mutations, methods designed to detect alterations in the genomic structure of the gene or in the FAA polypeptide may be helpful in the identification of FAA mutations.

The gene frequencies of alpha-1-antitrypsin (α1AT) in samples from several Italian localities are reported. An analysis of the data reveals a remarkable heterogeneity of frequencies. However no linear trend is observed when frequencies are correlated with latitude. A possible hypothesis for this observation is proposed.