Phylogeography, genetic structure, and gene flow in the endemic freshwater shrimp Palaemonetes suttkusi from Cuatro Ci��negas, Mexico

The valley of Cuatro Ciénegas in Mexico has the highest degree of local endemicity of any habitat in North America. A large number of endemic aquatic species occur both in the Cuatro Ciénegas basin and in the upper parts of the Río Salado de los Nadadores drainage, located immediately to the east of the valley. No natural surface flow occurs between these basins but artificial canals connect both areas. It is not clear whether the sharing of endemics between the Cuatro Ciénegas basin and the Río Salado is due to migration through canals. We conducted a phylogeographic study of mitochondrial haplotypes of the endemic shrimp Palaemonetes suttkusi to determine the evolutionary distinctiveness of the population found in Río Salado. We discovered that P. suttkusi likely has occurred naturally in both basins well into the distant past. Based on molecular clock analyses of the COI gene, the populations in the Río Salado and much of the Cuatro Ciénegas basin likely began diverging from each other between 1.9 and 11.2 Myr ago. The general levels of divergence are substantial but our results suggest there has also likely been recent gene flow between these basins. This is consistent with migration through human-made canals, but also consistent with the occurrence of natural gene flow during intermittent wet periods in the past million years. We also found significant differentiation of the Pozas Azules area from the rest of the Cuatro Ciénegas basin, a finding that is concordant with several phylogeographic studies on other aquatic endemics in Cuatro Ciénegas. We recommend that the upper parts of the Río Salado, the Pozas Azules area, and the rest of the Cuatro Ciénegas basin should each be considered independent evolutionarily significant units for conservation, and that migration of species through human-made canals should be monitored and controlled.     

S-genotyping of old apple cultivars from the Carpathian basin: methodological, breeding and evolutionary aspects

Apple exhibits self-incompatibility controlled by the multiallelic S-locus. Twenty-three old apple cultivars were S-genotyped using three different approaches (allele-specific polymerase chain reaction (PCR) + cleaved amplified polymorphic sequences (CAPS), consensus PCR + sequencing and consensus PCR + CAPS) to compare the robustness and reliability of these techniques and characterise genotypes from the Carpathian basin that might be useful in resistance breeding. Best results were obtained using the ASPF3 and ASPR3S consensus primer pair that detected 96% of all alleles carried by the 23 cultivars tested. Flow cytometry analysis was also needed to control the completeness of the genotypes as was seen in case of a tetraploid cultivar with only three assigned S-alleles. The genetic disparity between the old Carpathian basin and modern apple cultivars was indicated by differences in allele frequency data (S ₉, S ₂₄ and S ₂₆) as well as single nucleotide polymorphisms in S ₁, S ₂, S ₇ S ₂₄ and S ₂₆ and indels in S ₂₀ and S ₂₆ alleles. An alignment of partial genomic sequences indicated trans-specific and trans-generic evolution of S-ribonuclease alleles in the Maloideae subfamily (S ₂₆ and S ₂₈) and a possibly recent introgression event (S ₁) between Malus × domestica and Malus sylvestris. These data suggest that the genome of old cultivars from the Carpathian basin was enriched by several Malus taxa and are free from the consequences of modern breeding. These cultivars may contribute to the widening of the genetic basis of cultivated apple and prevent genetic erosion in future commercial cultivars.     

A decisive function of transforming growth factor-β/Smad signaling in tissue morphogenesis and differentiation of human HaCaT keratinocytes

The mechanism by which transforming growth factor-β (TGFβ) regulates differentiation in human epidermal keratinocytes is still poorly understood. To assess the role of Smad signaling, we engineered human HaCaT keratinocytes either expressing small interfering RNA against Smads2, 3, and 4 or overexpressing Smad7 and verified impaired Smad signaling as decreased Smad phosphorylation, aberrant nuclear translocation, and altered target gene expression. Besides abrogation of TGFβ-dependent growth inhibition in conventional cultures, epidermal morphogenesis and differentiation in organotypic cultures were disturbed, resulting in altered tissue homeostasis with suprabasal proliferation and hyperplasia upon TGFβ treatment. Neutralizing antibodies against TGFβ, similar to blocking the actions of EGF-receptor or keratinocyte growth factor, caused significant growth reduction of Smad7-overexpressing cells, thereby demonstrating that epithelial hyperplasia was attributed to TGFβ-induced "dermis"-derived growth promoting factors. Furthermore impaired Smad signaling not only blocked the epidermal differentiation process or caused epidermal-to-mesenchymal transition but induced a switch to a complex alternative differentiation program, best characterized as mucous/intestinal-type epithelial differentiation. As the same alternative phenotype evolved from both modes of Smad-pathway interference, and reduction of Smad7-overexpression caused reversion to epidermal differentiation, our data suggest that functional TGFβ/Smad signaling, besides regulating epidermal tissue homeostasis, is not only essential for terminal epidermal differentiation but crucial in programming different epithelial differentiation routes.     

Recent trends in butterfly populations from north-east Spain and Andorra in the light of habitat and climate change

Although butterfly declines have been reported across Europe, no assessment based on detailed quantitative data has ever been made for any extensive area in the Mediterranean Basin. In 1994, a Butterfly Monitoring Scheme was launched in Catalonia (NE Spain), and in 2005 a similar, albeit much smaller, scheme started in the neighbouring Pyrenean country of Andorra. Here we provide a first thorough assessment of butterfly trends in both areas for the last 15 years. Several patterns emerged, above all a worrying decline of a substantial part of the fauna. It was also evident that habitat specialists are experiencing greater declines than habitat generalists, thereby butterfly communities becoming progressively dominated by common species. However, habitat indicators based on characteristic species also revealed that trends are actually associated with habitat types, grassland and scrub specialists declining strongly but woodland specialists showing a marginal increase. These differences are certainly related to profound landscape changes, mainly a dramatic reduction of semi-natural grasslands and open Mediterranean scrub, and a major increase in woodlands. The general effect of climatic warming on butterfly populations was investigated by using the temperature community index (CTI) approach. The thermal structure of butterfly communities remained very stable over time, except in one case where, contrary to the expectations, a significant negative trend in the CTI was noted. However, this surprising result can be explained by taking into account the above-reported pattern of butterfly communities becoming dominated by common species, characterized by low thermal indices in comparison with declining Mediterranean specialists.     

A genome-wide screen identifies yeast genes required for protection against or enhanced cytotoxicity of the antimalarial drug quinine

Quinine is used in the treatment of Plasmodium falciparum severe malaria. However, both the drug's mode of action and mechanisms of resistance are still poorly understood and subject to debate. In an effort to clarify these questions, we used the yeast Saccharomyces cerevisiae as a model for pharmacological studies with quinine. Following on a previous work that examined the yeast genomic expression program in response to quinine, we now explore a genome-wide screen for altered susceptibility to quinine using the EUROSCARF collection of yeast deletion strains. We identified 279 quinine-susceptible strains, among which 112 conferred a hyper-susceptibility phenotype. The expression of these genes, mainly involved in carbohydrate metabolism, iron uptake and ion homeostasis functions, is required for quinine resistance in yeast. Sixty-two genes whose deletion leads to increased quinine resistance were also identified in this screen, including several genes encoding ribosome protein subunits. These well-known potential drug targets in Plasmodium are associated with quinine action for the first time in this study. The suggested involvement of phosphate signaling and transport in quinine tolerance was also studied, and activation of phosphate starvation-responsive genes was observed under a mild-induced quinine stress. Finally, P. falciparum homology searches were performed for a selected group of 41 genes. Thirty-two encoded proteins possess homologs in the parasite, including subunits of a parasitic vacuolar H(+)-ATPase complex, ion and phosphate importers, and several ribosome protein subunits, suggesting that the results obtained in yeast are good candidates to be transposed and explored in a P. falciparum context.