In vitro evaluation of oestrogenic/androgenic activity of the serum organochlorine pesticide mixtures previously described in a breast cancer case-control study

Some organochlorine pesticides (OCs) have been individually linked to breast cancer (BC) because they exert oestrogenic effects on mammary cells. However, humans are environmentally exposed to more or less complex mixtures of these organochlorines, and the biological effects of these mixtures must be elucidated. In this work we evaluated the in vitro effects exerted on human BC cells by the OC mixtures that were most frequently detected in two groups of women who participated in a BC case-control study developed in Spain: healthy women and women diagnosed with BC. The cytotoxicity, oestrogenicity, and androgenicity of the most prevalent OC mixtures found in healthy women (H-mixture) and in BC patients (BC-mixture) were tested at concentrations that resembled those found in the serum of the evaluated women. Our results showed that both OC mixtures presented a similar oestrogenic activity and effect on cell viability, but BC-mixture showed an additional anti-androgenic effect. These results indicate that although the proliferative effect exerted by these mixtures on human breast cells seems to depend mainly on their oestrogenic action, the BC-mixture might additionally induce cell proliferation due to its anti-androgenic activity, therefore increasing the carcinogenic potential of this mixture. The findings of this study demonstrate that subtle variations in the composition of a mixture may induce relevant changes in its biological action.

Mitochondrial DNA haplogroup phylogeny of the dog: Proposal for a cladistic nomenclature

Canis lupus familiaris mitochondrial DNA analysis has increased in recent years, not only for the purpose of deciphering dog domestication but also for forensic genetic studies or breed characterization. The resultant accumulation of data has increased the need for a normalized and phylogenetic-based nomenclature like those provided for human maternal lineages. Although a standardized classification has been proposed, haplotype names within clades have been assigned gradually without considering the evolutionary history of dog mtDNA. Moreover, this classification is based only on the D-loop region, proven to be insufficient for phylogenetic purposes due to its high number of recurrent mutations and the lack of relevant information present in the coding region. In this study, we design 1) a refined mtDNA cladistic nomenclature from a phylogenetic tree based on complete sequences, classifying dog maternal lineages into haplogroups defined by specific diagnostic mutations, and 2) a coding region SNP analysis that allows a more accurate classification into haplogroups when combined with D-loop sequencing, thus improving the phylogenetic information obtained in dog mitochondrial DNA studies.

Introducing the Algerian mitochondrial DNA and Y-chromosome profiles into the North African landscape

North Africa is considered a distinct geographic and ethnic entity within Africa. Although modern humans originated in this Continent, studies of mitochondrial DNA (mtDNA) and Y-chromosome genealogical markers provide evidence that the North African gene pool has been shaped by the back-migration of several Eurasian lineages in Paleolithic and Neolithic times. More recent influences from sub-Saharan Africa and Mediterranean Europe are also evident. The presence of East-West and North-South haplogroup frequency gradients strongly reinforces the genetic complexity of this region. However, this genetic scenario is beset with a notable gap, which is the lack of consistent information for Algeria, the largest country in the Maghreb. To fill this gap, we analyzed a sample of 240 unrelated subjects from a northwest Algeria cosmopolitan population using mtDNA sequences and Y-chromosome biallelic polymorphisms, focusing on the fine dissection of haplogroups E and R, which are the most prevalent in North Africa and Europe respectively. The Eurasian component in Algeria reached 80% for mtDNA and 90% for Y-chromosome. However, within them, the North African genetic component for mtDNA (U6 and M1; 20%) is significantly smaller than the paternal (E-M81 and E-V65; 70%). The unexpected presence of the European-derived Y-chromosome lineages R-M412, R-S116, R-U152 and R-M529 in Algeria and the rest of the Maghreb could be the counterparts of the mtDNA H1, H3 and V subgroups, pointing to direct maritime contacts between the European and North African sides of the western Mediterranean. Female influx of sub-Saharan Africans into Algeria (20%) is also significantly greater than the male (10%). In spite of these sexual asymmetries, the Algerian uniparental profiles faithfully correlate between each other and with the geography.

Genetic characterization, at the mitochondrial and nuclear DNA levels, of five Canary Island dog breeds

Many studies presenting genetic analysis of dog breeds have been conducted without the inclusion of island dog breeds, although isolation can be one of the main factors in their origin. Here we report the genetic analysis at the nuclear and mitochondrial DNA levels of five Canary Island dog breeds (Canarian Warren Hound, Canary Island Mastiff, Garafiano Shepherd, La Palma Rat-Hunter and El Hierro Wolfhound) to fill this gap and, at the same time, genetically characterize these breeds. We identified 168 alleles in autosomal microsatellites and 16 mitochondrial haplotypes. Observed and expected heterozygosities ranged from 0.556 to 0.783 and from 0.737 to 0.943 respectively. Furthermore, three haplotypes were newly described and exclusive to a particular breed (A17+ in the Canary Island Mastiff; A33+ in the Canarian Warren Hound; Bi in the La Palma Rat-Hunter). The outcome of our analyses also revealed different breed histories consistent with historical documents and hypothetical origin designations. Although mtDNA haplotypes showed poor breed discriminating power, autosomal markers allowed a clear clustering of each single population. We expect that our results, together with further analyses, will help to make the population histories of island dog breeds clearer.

Mitochondrial lineage M1 traces an early human backflow to Africa

Background

The out of Africa hypothesis has gained generalized consensus. However, many specific questions remain unsettled. To know whether the two M and N macrohaplogroups that colonized Eurasia were already present in Africa before the exit is puzzling. It has been proposed that the east African clade M1 supports a single origin of haplogroup M in Africa. To test the validity of that hypothesis, the phylogeographic analysis of 13 complete mitochondrial DNA (mtDNA) sequences and 261 partial sequences belonging to haplogroup M1 was carried out.

Results

The coalescence age of the African haplogroup M1 is younger than those for other M Asiatic clades. In contradiction to the hypothesis of an eastern Africa origin for modern human expansions out of Africa, the most ancestral M1 lineages have been found in Northwest Africa and in the Near East, instead of in East Africa. The M1 geographic distribution and the relative ages of its different subclades clearly correlate with those of haplogroup U6, for which an Eurasian ancestor has been demonstrated.

Conclusion

This study provides evidence that M1, or its ancestor, had an Asiatic origin. The earliest M1 expansion into Africa occurred in northwestern instead of eastern areas; this early spread reached the Iberian Peninsula even affecting the Basques. The majority of the M1a lineages found outside and inside Africa had a more recent eastern Africa origin. Both western and eastern M1 lineages participated in the Neolithic colonization of the Sahara. The striking parallelism between subclade ages and geographic distribution of M1 and its North African U6 counterpart strongly reinforces this scenario. Finally, a relevant fraction of M1a lineages present today in the European Continent and nearby islands possibly had a Jewish instead of the commonly proposed Arab/Berber maternal ascendance.

Mitochondrial DNA transit between West Asia and North Africa inferred from U6 phylogeography

BACKGROUND

World-wide phylogeographic distribution of human complete mitochondrial DNA sequences suggested a West Asian origin for the autochthonous North African lineage U6. We report here a more detailed analysis of this lineage, unraveling successive expansions that affected not only Africa but neighboring regions such as the Near East, the Iberian Peninsula and the Canary Islands.

RESULTS

Divergence times, geographic origin and expansions of the U6 mitochondrial DNA clade, have been deduced from the analysis of 14 complete U6 sequences, and 56 different haplotypes, characterized by hypervariable segment sequences and RFLPs.

CONCLUSIONS

The most probable origin of the proto-U6 lineage was the Near East. Around 30,000 years ago it spread to North Africa where it represents a signature of regional continuity. Subgroup U6a reflects the first African expansion from the Maghrib returning to the east in Paleolithic times. Derivative clade U6a1 signals a posterior movement from East Africa back to the Maghrib and the Near East. This migration coincides with the probable Afroasiatic linguistic expansion. U6b and U6c clades, restricted to West Africa, had more localized expansions. U6b probably reached the Iberian Peninsula during the Capsian diffusion in North Africa. Two autochthonous derivatives of these clades (U6b1 and U6c1) indicate the arrival of North African settlers to the Canarian Archipelago in prehistoric times, most probably due to the Saharan desiccation. The absence of these Canarian lineages nowadays in Africa suggests important demographic movements in the western area of this Continent.

Diversification of sympatric Sapromyza (Diptera: Lauxaniidae) from Madeira: six morphological species but only four mtDNA lineages

A series of recent studies on speciation of insects within the Canary Islands have indicated considerable within-island diversification, similar to that described in the Hawaiian islands. Little work has yet been carried out on the neighboring Madeiran archipelago, which is also volcanic. This study examines relationships among all known Lauxaniid flies of the genus Sapromyza from Madeira (including six newly described morphological species) based on mitochondrial gene trees constructed from cytochrome c oxidase (subunit I) and 16S rRNA partial sequences. Phylogenies based on maximum likelihood distances, a Bayesian method based on Markov chain Monte Carlo sampling from the posterior probability distribution, and maximum parsimony show that eight of the nine Madeiran species comprise a single monophyletic group. This clade is also split into two subclades representing black- and yellow/orange-bodied forms. The latter mtDNA clade corresponds to only two species (Sapromyza imitans and Sapromyza indigena) which are not reciprocally monophyletic. Monophyly is strongly supported within four of the six black-bodied species but not for the species pair (Sapromyza inconspicua, Sapromyza laurisilvae). We discuss the double occurrence (at least) of introgressive hybridization/incomplete lineage sorting within this group and suggest that recent speciation is the most likely explanation. The remaining species on the island, Sapromyza madeirensis, is very divergent from the aforementioned group, occupying a more basal position in the tree than the other Atlantic island and continental Sapromyza that were included in the analysis. At least two speciation events for Madeiran Sapromyza appear to correspond to quite ancient periods relative to the age of the island, while others are more recent. This suggests that a combination of island colonization and within-island sympatric and/or vicariance-mediated speciation may explain the observed diversity.

Intraspecific evolution of Canary Island Plecotine bats, based on mtDNA sequences

Island differentiation and relationships with congenerics were investigated in the endemic Canary Island bat Plecotus teneriffae, based on approximately 1 kb of mtDNA from the 16S rRNA and cytochrome b genes. P. teneriffae had closer affinities with P. austriacus than with P. auritus. Levels of differentiation between Canary Islands were quite high relative to Pipistrelle-like bats, consistent with philopatric behaviour in the Plecotus genus. Cladogenesis within P. teneriffae appears to have occurred after the emergence of the islands of El Hierro and La Palma during the Pleistocene. An intraspecific network shows that haplotypes from the younger islands of La Palma and El Hierro are connected to the Tenerife haplotype by a similarly large number of mutational steps. This suggests that they were both colonised at a similar time from the much older island of Tenerife. The other Plecotine bat species, Barbastellus barbastellus shows close affinities with B. barbastellus from mainland Spain, with levels of mtDNA divergence being comparable with intraspecific variation within other mammal species.

Phylogeography of pipistrelle-like bats within the Canary Islands, based on mtDNA sequences

Evolution of three Canary Island Vespertilionid bat species, Pipistrellus kuhlii, Pipistrellus maderensis, and Hypsugo savii was studied by comparison of approximately 1 kbp of mtDNA (from cytochrome b and 16S rRNA genes) between islands. mtDNA reveals that both P. kuhlii and P. maderensis exist in sympatry on Tenerife (and possibly other islands). Their morphological similarity explains why their co-occurrence had not been detected previously. Levels of sequence divergence are quite low within P. maderensis. Haplotypes were either identical or separated by </=2 mutational steps on two of the islands (La Gomera and El Hierro). However there is sufficient between-island divergence between haplotypes from Tenerife, La Palma, and La Gomera/El Hierro to suggest that they could represent three evolutionary significant units (ESU). H. savii has an overlapping island distribution but a contrasting phylogeographical pattern. Most significantly, sequence divergence is greatest between La Gomera and El Hierro (>/=12 mutational steps) indicating colonization of the latter from the former sometime during the last approximately 1.2 Ma, with low subsequent gene flow. Unlike P. maderensis the El Hierro population alone appears to represent an ESU. The H. savii haplotypes detected in Gran Canaria and Tenerife are identical or separated by 1 mutational step.

The Atlas mountains as a biogeographical divide in North-West Africa: evidence from mtDNA evolution in the Agamid lizard Agama impalearis

Since the early Miocene there have been several physical events within NW Africa that are likely to have had a major impact on its faunal diversity. Phylogeographical studies will shed new light on the biogeography of the region. We analysed mitochondrial DNA diversity in the agamid lizard Agama impalearis (also called A. bibronii) based on sequences from mitochondrial genes with very different evolutionary rates (16S rRNA and ND2). Well-supported topologies of rooted maximum parsimony trees (with a Laudakia outgroup) and unrooted haplotype networks indicated two major clades with similar branch lengths. These clades have non-overlapping distributions representing respective areas to the North and West and South and East of the Atlas mountain chain and each could be given full species recognition. Nested clade analyses indicate that historical and possible present-day allopatry account for the primary phylogeographic pattern. Further evidence is provided by the estimated timing of cladogenesis, based on calibration of evolutionary rates in the ND2 gene of another continental Agamid. Sequence divergence between clades corresponds to 8.5-9.4mya, coinciding with the main period of orogenic uplift of the Atlas. Additional evidence of cladogenesis by allopatric fragmentation is also detected within the North/West Atlas clade, although contiguous range expansion is the most predominant explanation of more recent phylogeographic effects in this species. Miocene vicariance mediated by the Atlas may provide a general explanation of intra- and interspecific biogeographical patterns in NW African species.

Phylogeography of Cape Verde Island skinks (Mabuya)

The Cape Verde Islands are of volcanic origin with most having appeared between the early Miocene and mid-Pleistocene. They contain six known species of Mabuya skinks. Phylogeographical relationships within and among the relatively widespread taxa M. stangeri, M. spinalis and M. delalandii were inferred, based on approximately 1 kbp of the cytochrome b gene (mitochondrial DNA). Reciprocal monophyly of M. spinalis and M. stangeri was established, which may have arisen from an early Pliocene/late Miocene cladogenetic event. Considerable between-island sequence divergence was detected among M. spinalis, which appears to have colonized the older islands (Sal and Boavista) first. Much lower sequence divergence was found in M. delalandii, indicating a more recent range expansion. Here, evidence points to colonization of the younger islands of Brava and Fogo soon after appearance. There are similarities between some of the described patterns and those seen in lizards from the Canary Islands.

Mitochondrial DNA control region diversity in the endangered blue chaffinch, Fringilla teydea

The blue chaffinch (Fringilla teydea) is found only on the two central Canary Islands of Gran Canaria and Tenerife, where it is restricted to pine forest habitat. It is reasonably abundant on the latter island but endangered on the former. Here, sequence variation was studied in a fragment spanning domains I and II of the mitochondrial DNA (mtDNA) control region. Phylogenetic analysis of all haplotypes with a F. coelebs outgroup indicated the two island populations were reciprocally monophyletic, supporting their individual conservation. Unlike in other species, most within-island haplotype diversity was due to mutations in the domain II region. Surprisingly, genetic diversity was greater in the smaller Gran Canarian population. We suggest that this is unlikely to be maintained under current population sizes although it may be mitigated by incorporating genetic information into the captive breeding programme.

Mitochondrial DNA evolution and population history of the Tenerife skink Chalcides viridanus

Recent studies of island lizards have suggested that historical vicariance as a result of volcanism may have played an important role in shaping patterns of within-island genetic diversity. The skink, Chalcides viridanus, shows variation in morphology within the volcanic island of Tenerife. Two mitochondrial DNA (mtDNA) fragments (from the 12S and 16S rRNA regions) were sequenced in individuals from 17 sites to evaluate the relationship between current phylogeography and the geological history of the island. Three main clades were detected. The two most basal clades were restricted to areas representing the ancient precursor islands of Teno and Anaga in the northwest and northeast of Tenerife, respectively. The third clade showed a widespread geographical distribution and provided evidence of a recent rapid expansion after a bottleneck. Within-island cladogenesis appears to have taken place during a recent period of volcanic activity and long after the ancient islands had been united by the eruptions that led to the formation of the Canadas edifice. Evidence of similar biogeographical histories are found in other species in the Canary archipelago, supporting the volcanism scenario as a potentially widespread cause of within-island differentiation in reptiles.

Phylogeography of skinks (Chalcides) in the Canary Islands inferred from mitochondrial DNA sequences

Mitochondrial DNA (mtDNA) evolution was investigated in skinks of the genus Chalcides found in the Canary Islands (Ch. sexlineatus, Ch. viridanus and Ch. simonyi), together with some North African congenerics (Ch. polylepis and Ch. mionecton). Several sites were included within islands to cover areas of known within-island geographical variation in morphology. Skinks from the islands of El Hierro and La Gomera appear to be sister taxa. The relationships between this clade and the Tenerife and Gran Canarian skinks were not fully resolved, although the best working hypothesis indicated monophyly with the former, with the latter forming a closely related outgroup. Ch. simonyi from Fuerteventura was more distantly related to the Western Canary Island skinks and did not show close relationships with the North African species Ch. mionecton and Ch. polylepis. Possible colonization sequences for the four most Western Canary Islands were considered. El Hierro appears to have been colonized relatively recently from La Gomera, commensurate with the recent origin of this island, while dispersal between La Gomera and Tenerife and between Gran Canaria and Tenerife or La Gomera appears to have taken place considerably earlier. Substantial within-island haplotype divergence was found in Gran Canaria and Tenerife. This may be a result of recent periods of intense volcanic activity found within these two islands. Lower levels of within-island differentiation are found in La Gomera and El Hierro and may be explained by lower levels of volcanic activity during recent geological history and a more recent colonization, respectively.

The two native estrogen receptor forms of 8S and 4S present in cytosol from human uterine tissues display opposite reactivities with the antiestrogen tamoxifen aziridine and the estrogen responsive element

We have investigated the capability of the different native ER forms, present in cytosols from human uterine tissues, of reacting with the antiestrogen [3H]Tamoxifen aziridine ([3H]TA) and with the Estrogen Responsive Element (ERE). Cytosols from uterine leiomyoma (myoma) prepared in buffer containing 40 mM molybdate and protease inhibitors, labelled with [3H]estradiol and analyzed in low-salt sucrose gradient showed 8S and 4S ER forms. The same cytosols labelled with [3H]TA only showed a 4S ER form, whereas the ERE only reacted with fractions from the 8S peak. The band of ERE reaction in the EMSA assay showed a lower relative mobility than the band labelled with [3H]TA, but both bands contained immunoreactive ER of 65 kDa. Electrophoretic mobility of the [3H]TA-labelled band in that system was not affected by cytosol treatment with cross-linkers or SDS, which suggests that it is a monomeric protein. The [3H]TA-binding 4S ER form was found in all studied myoma samples, as well as in human endometrium or myometrium, but not in rat tissues. These results suggest that the 8S and 4S ER form were already present before cytosol from human uterine tissues comes into contact with the molybdate buffer. They both contain the same ER molecule of 65 kDa, either in the free form or as an oligomer. Only the ER dimers, which have been described both in the cytosolic 8S form and in the nuclear 4-5S form, react with the ERE. [3H]TA only binds to the 4S ER monomer probably because its binding site is concealed in the 8S form under these experimental conditions. The opposite reactivity of the 8S and 4S ER forms with [3H]TA and the ERE support the hypothesis that they may constitute separate entities with a different physiological role.

Quantitative analysis of p185(HER-2/neu) protein in breast cancer and its association with other prognostic factors

The total cellular p185(HER-2/neu) protein (p185) content was measured by ELISA in 346 invasive primary breast cancers, and the results were compared with those of estrogen (ER) and progesterone (PR) receptors, pS2 and Cathepsin D (Cat D) content. At a cut-off level of 260 fmol/mg protein, 53 of the 346 tumors (15%) were p185-positive. A significant positive correlation was observed between p185 levels and those of Cat D, and a weaker, though significant, positive correlation with ER, and pS2 levels, but not with those of PR. However, when only the 293 p185-negative tumors were considered, the correlation between p185 and ER improved substantially, and statistical significance was reached for PR. p185-positive tumors exhibited lower ER and PR content and higher Cat D content than p185-negative tumors. The pS2 content, in contrast, did not undergo significant variation. Tumors considered to be p185-positive were significantly more frequently positive for Cat D at the cut-off of 45 pmol/mg protein, and were more frequently negative for ER and/or PR, but only significant at the cut-off of 15 fmol/mg or higher for both steroid receptors. Finally, p185 status was not associated with menopausal status, tumor size, axillary-lymph-node invasiveness or distant metastases. These results suggest that 260 fmol/mg protein as the cut-off for p185 allows the identification of a tumoral sub-population with a more aggresive phenotype.

Mitochondrial DNA evolution in the obscura species subgroup of Drosophila

Mitochondrial DNA (mtDNA) restriction site maps for nine species of the Drosophila obscura subgroup and for Drosophila melanogaster were established. Taking into account all restriction enzymes (12) and strains (45) analyzed, a total of 105 different sites were detected, which corresponds to a sample of 3.49% of the mtDNA genome. Based on nucleotide divergences, two phylogenetic trees were constructed assuming either constant or variable rates of evolution. Both methods led to the same relationships. Five differentiated clusters were found for the obscura subgroup species, one Nearctic, represented by Drosophila pseudoobscura, and four Palearctic, two grouping the related triads of species Drosophila subobscura, Drosophila madeirensis, Drosophila obscura, Drosophila subsilvestris, and two more represented by one species each, Drosophila bifasciata, and Drosophila tristis. The different Palearctic clusters are as distant between themselves as with the Nearctic one. For the related species D. subobscura, D. madeirensis, and D. guanche, the pair D. subobscura-D. madeirensis is the closest one. The relationships found by nucleotide divergence were confirmed by differences in mitochondrial genome size, with related species sharing similar genome lengths and differing from the distant ones. The total mtDNA size range for the obscura subgroup species was from 15.5 kb for D. pseudoobscura to 17.1 for D. tristis.