Evidence for ecological speciation via a host shift in the holly leaf miner,Phytomyza glabricola (Diptera: Agromyzidae)

Evolutionary radiations have been well documented in plants and insects, and natural selection may often underly these radiations. If radiations are adaptive, the diversity of species could be due to ecological speciation in these lineages. Agromyzid flies exhibit patterns of repeated host‐associated radiations. We investigated whether host‐associated population divergence and evidence of divergent selection exist in the leaf miner Phytomyza glabricola on its sympatric host plants, the holly species, Ilex coriacea and I. glabra. Using AFLPs and nuclear sequence data, we found substantial genetic divergence between host‐associated populations of these flies throughout their geographic range. Genome scans using the AFLP data identified 13 loci under divergent selection, consistent with processes of ecological speciation. EF‐1α data suggest that I. glabra is the original host of P. glabricola and that I. coriacea is the novel host, but the AFLP data are ambiguous with regard to directionality of the host shift.     

Essential oils from Azorean Laurus azorica

The essential oils isolated from leaves of ten and from unripe berries of eight populations of Laurus azorica (Seub.) Franco, collected on five islands of the Azorean archipelago, were analysed by GC and GC-MS. All oil samples were dominated by their monoterpene fraction (60-94%), alpha-pinene (15-37%) and 1,8-cineole (12-31%) being the main components of the leaf oils, while trans-beta-ocimene (27-45%) and alpha-pinene (12-22%) were the main components of the oils from the berries. The sesquiterpene fractions of the oils ranged from 3 to 17% and the main components were beta-caryophyllene (traces-8%) and beta-elemene (traces-3%) both in the leaf and berry oils. Some phenylpropanoid components were also present, in total amounting to 17%, trans-cinnamyl acetate (215% of the leaf oils) being the main component of this fraction. Cluster analysis of the enantiomeric composition of alpha- and beta-pinene in the oils from the leaves clearly showed two groups, one constituted by the two populations growing on the island S. Jorge, and the other constituted by the remaining populations.     

Subcellular localization and N-glycosylation of human ABCC6, expressed in MDCKII cells

Mutations in the gene coding for a human ABC transporter protein, ABCC6 (MRP6), are responsible for the development of pseudoxanthoma elasticum. Here, we demonstrate that human ABCC6, when expressed by retroviral transduction in polarized mammalian (MDCKII) cells, is exclusively localized to the basolateral membrane. The human ABCC6 in MDCKII cells was found to be glycosylated, in contrast to the underglycosylated form of the protein, as expressed in Sf9 cells. In order to localize the major glycosylation site(s) in ABCC6, we applied limited proteolysis on the fully glycosylated and underglycosylated forms, followed by immunodetection with region-specific antibodies for ABCC6. Our results indicate that Asn15, which is located in the extracellular N-terminal region of human ABCC6, is the only N-glycosylation site in this protein. The polarized mammalian expression system characterized here provides a useful tool for further examination of routing, glycosylation, and function of the normal and pathological variants of human ABCC6.     

CPMK2, an SLT2-homologous mitogen-activated protein (MAP) kinase,is essential for pathogenesis of Claviceps purpurea on rye: evidence for a second conserved pathogenesis-related MAP kinase cascade in phytopathogenic fungi

Cpmk2, encoding a mitogen-activated protein (MAP) kinase from the ascomycete Claviceps purpurea, is an orthologue of SLT2 from Saccharomyces cerevisiae, the first isolated from a biotrophic, non-appressorium-forming pathogen. Deletion mutants obtained by a gene replacement approach show impaired vegetative properties (no conidiation) and a significantly reduced virulence, although they retain a limited ability to colonize the host tissue. Increased sensitivity to protoplasting enzymes indicates that the cell wall structure of the mutants may be altered. As the phenotypes of these mutants are similar to those observed in strains of the rice pathogen, Magnaporthe grisea, that have been deprived of their MAP kinase gene mps1, the ability of cpmk2 to complement the defects of delta mps1 was investigated. Interestingly, the C. purpurea gene, under the control of its own promoter, was able to complement the M. grisea mutant phenotype: transformants were able to sporulate and form infection hyphae on onion epidermis and were fully pathogenic on barley leaves. This indicates that, despite the differences in infection strategies, which include host and organ specificity, mode of penetration and colonization of host tissue, CPMK2/MPS1 defines a second MAP kinase cascade (after the Fus3p/PMK1 cascade) essential for fungal pathogenicity.     

El Niño effects on the dynamics of terrestrial ecosystems

New studies are showing that the El Ni?o Southern Oscillation (ENSO) has major implications for the functioning of different ecosystems, ranging from deserts to tropical rain forests. ENSO-induced pulses of enhanced plant productivity can cascade upward through the food web invoking unforeseen feedbacks, and can cause open dryland ecosystems to shift to permanent woodlands. These insights suggest that the predicted change in extreme climatic events resulting from global warming could profoundly alter biodiversity and ecosystem functioning in many regions of the world. Our increasing ability to predict El Ni?o effects can be used to enhance management strategies for the restoration of degraded ecosystems.     

A new locus for generalized epilepsy with febrile seizures plus maps to chromosome 2

Generalized epilepsy with febrile seizures plus (GEFS+) is a recently recognized but relatively common form of inherited childhood-onset epilepsy with heterogeneous epilepsy phenotypes. We genotyped 41 family members, including 21 affected individuals, to localize the gene causing epilepsy in a large family segregating an autosomal dominant form of GEFS+. A genomewide search examining 197 markers identified linkage of GEFS+ to chromosome 2, on the basis of an initial positive LOD score for marker D2S294 (Z=4.4, recombination fraction [straight theta] = 0). A total of 24 markers were tested on chromosome 2q, to define the smallest candidate region for GEFS+. The highest two-point LOD score (Zmax=5.29; straight theta=0) was obtained with marker D2S324. Critical recombination events mapped the GEFS+ gene to a 29-cM region flanked by markers D2S156 and D2S311, with the idiopathic generalized epilepsy locus thereby assigned to chromosome 2q23-q31. The existence of the heterogeneous epilepsy phenotypes in this kindred suggests that seizure predisposition determined by the GEFS+ gene on chromosome 2q could be modified by other genes and/or by environmental factors, to produce the different seizure types observed.     

Intergenerational context discontinuity affects the onset of puberty

The assumption that the onset of puberty is a context-sensitive marker of a reproductive strategy is tested by comparing parental and filial childhood context and somatic development in West and East Germany. Sixty-eight mother-daughter dyads and 35 father-son dyads were taken from two samples of families from Osnabrück in West Germany and Halle in East Germany. According to the observed context discontinuity between the generations in the male dyads, linear regression models show that no indicator of male sexual maturation was influenced significantly by the somatic development of the father. Instead of an inherited timing of maturation, antecedent distal factors like socioeconomic childhood context variables and critical life events lead to an acceleration of male sexual maturation. Finally we test the effect of two different conditions of childhood context continuity on daughter’s age at menarche with maternal age at menarche controlled. Linear regression models show that mother’s age at menarche predicts daughter’s age at menarche only under the condition of contextual continuity between generations, which was the case in the West German sample only. In East Germany, where mother’s age at menarche had no significant effect, the amount of variance explained by childhood context variables was almost the same. These results indicate the context sensitivity of somatic development which seems to follow an evolutionary rationale.     

A Changing Number of Alternative States in the Boreal Biome: Reproducibility Risks of Replacing Remote Sensing Products

Publicly available remote sensing products have boosted science in many ways. The openness of these data sources suggests high reproducibility. However, as we show here, results may be specific to versions of the data products that can become unavailable as new versions are posted. We focus on remotely-sensed tree cover. Recent studies have used this public resource to detect multi-modality in tree cover in the tropical and boreal biomes. Such patterns suggest alternative stable states separated by critical tipping points. This has important implications for the potential response of these ecosystems to global climate change. For the boreal region, four distinct ecosystem states (i.e., treeless, sparse and dense woodland, and boreal forest) were previously identified by using the Collection 3 data of MODIS Vegetation Continuous Fields (VCF). Since then, the MODIS VCF product has been updated to Collection 5; and a Landsat VCF product of global tree cover at a fine spatial resolution of 30 meters has been developed. Here we compare these different remote-sensing products of tree cover to show that identification of alternative stable states in the boreal biome partly depends on the data source used. The updated MODIS data and the newer Landsat data consistently demonstrate three distinct modes around similar tree-cover values. Our analysis suggests that the boreal region has three modes: one sparsely vegetated state (treeless), one distinct ‘savanna-like’ state and one forest state, which could be alternative stable states. Our analysis illustrates that qualitative outcomes of studies may change fundamentally as new versions of remote sensing products are used. Scientific reproducibility thus requires that old versions remain publicly available.     

Next-Generation Sequencing of a 40 Mb Linkage Interval Reveals TSPAN12 Mutations in Patients with Familial Exudative Vitreoretinopathy

Familial exudative vitreoretinopathy (FEVR) is a genetically heterogeneous retinal disorder characterized by abnormal vascularisation of the peripheral retina, often accompanied by retinal detachment. To date, mutations in three genes (FZD4, LRP5, and NDP) have been shown to be causative for FEVR. In two large Dutch pedigrees segregating autosomal-dominant FEVR, genome-wide SNP analysis identified an FEVR locus of ∼40 Mb on chromosome 7. Microsatellite marker analysis suggested similar at risk haplotypes in patients of both families. To identify the causative gene, we applied next-generation sequencing in the proband of one of the families, by analyzing all exons and intron-exon boundaries of 338 genes, in addition to microRNAs, noncoding RNAs, and other highly conserved genomic regions in the 40 Mb linkage interval. After detailed bioinformatic analysis of the sequence data, prioritization of all detected sequence variants led to three candidates to be considered as the causative genetic defect in this family. One of these variants was an alanine-to-proline substitution in the transmembrane 4 superfamily member 12 protein, encoded by TSPAN12. This protein has very recently been implicated in regulating the development of retinal vasculature, together with the proteins encoded by FZD4, LRP5, and NDP. Sequence analysis of TSPAN12 revealed two mutations segregating in five of 11 FEVR families, indicating that mutations in TSPAN12 are a relatively frequent cause of FEVR. Furthermore, we demonstrate the power of targeted next-generation sequencing technology to identify disease genes in linkage intervals.