Explaining variability in the production of seed and allergenic pollen by invasive <Emphasis Type="Italic">Ambrosia artemisiifolia</Emphasis> across Europe

To better manage invasive populations, it is vital to understand the environmental drivers underlying spatial variation in demographic performance of invasive individuals and populations. The invasive common ragweed, Ambrosia artemisiifolia, has severe adverse effects on agriculture and human health, due to its vast production of seeds and allergenic pollen. Here, we identify the scale and nature of environmental factors driving individual performance of A. artemisiifolia, and assess their relative importance. We studied 39 populations across the European continent, covering different climatic and habitat conditions. We found that plant size is the most important determinant in variation of per-capita seed and pollen production. Using plant volume as a measure of individual performance, we found that the local environment (i.e. the site) is far more influential for plant volume (explaining 25% of all spatial variation) than geographic position (regional level; 8%) or the neighbouring vegetation (at the plot level; 4%). An overall model including environmental factors at all scales performed better (27%), including the weather (bigger plants in warm and wet conditions), soil type (smaller plants on soils with more sand), and highlighting the negative effects of altitude, neighbouring vegetation and bare soil. Pollen and seed densities varied more than 200-fold between sites, with highest estimates in Croatia, Romania and Hungary. Pollen densities were highest on arable fields, while highest seed densities were found along infrastructure, both significantly higher than on ruderal sites. We discuss implications of these findings for the spatial scale of management interventions against A. artemisiifolia.     

Molecular and morphological divergence in a stygobiont gastropod lineage (Truncatelloidea,Moitessieriidae, Paladilhiopsis) within an isolated karstic area in the Mecsek Mountains (Hungary)

Truncatelloid gastropods are one of the most species‐rich subterranean invertebrate groups. Their current taxonomy is based on morphological characters. However, this is not a comprehensive approach and does not take into account the degree of phylogenetic divergence between stygobiont populations inhabiting hydrologically isolated but geographically close caves. We studied two Paladilhiopsis populations of a small and isolated karstic area (Mecsek Mountains, Hungary) with two hydrologically separated cave systems, investigating morphological (shell morphometrics) and genetic (COI, 16S) divergence together. The populations differed both morphologically and genetically: we found strong divergence in the relative width of the shell (best described by the variable “shell angle”) and a 6.4% divergence in COI. This provides strong support for the presence of two distinct taxa; however, it is still doubtful whether they differ at the species or the subspecies level. In one of the caves, we found representatives of both haplotypes (and phenotypes), which can be explained by secondary contact after an allopatric divergence.     

Starvation- and xenobiotic-related transcriptomic responses of the sulfanilic acid-degrading bacterium,Novosphingobium resinovorum SA1

Applied Microbiology and Biotechnology - Novosphingobium resinovorum SA1 was the first single isolate capable of degrading sulfanilic acid, a widely used representative of sulfonated aromatic...     

The role of water in the extracellular half channel of bacteriorhodopsin.

The changes in the photocycle of the wild type and several mutant bacteriorhodopsin (D96N, E204Q, and D212N) were studied on dried samples, at relative humidities of 100% and 50%. Samples were prepared from suspensions at pH approximately 5 and at pH approximately 9. Intermediate M with unprotonated Schiff base was observed at the lower humidity, even in the case where the photocycle in suspension did not contain this intermediate (mutant D212N, high pH). The photocycle of the dried sample stopped at intermediate M1 in the extracellular conformation; conformation change, switching the accessibility of the Schiff base to the cytoplasmic side, and proton transport did not occur. The photocycle decayed slowly by dissipating the absorbed energy of the photon, and the protein returned to its initial bacteriorhodopsin state, through several M1-like substates. These substates presumably reflect different paths of the proton back to the Schiff base, as a consequence of the bacteriorhodopsin adopting different conformations by stiffening on dehydration. All intermediates requiring conformational change were hindered in the dried form. The concentration of intermediate L, which appears after isomerization of the retinal from all-trans to 13-cis, during local relaxation of the protein, was unusually low in dried samples. The lack of intermediates N and O demonstrated that the M state did not undergo a change from the extracellular to the cytoplasmic conformation (M1 to M2 transition), as already indicated by Fourier transform infrared spectroscopy, quasielastic incoherent neutron scattering, and electric signal measurements described in the literature.     

Cell surface dynamics of CFTR: the ins and outs

Ganeshan et al. (Biochem Biophys. Acta 1173 (2007) 192-200) recent study documents the effect of N-WASP inhibition and actin cytoskeleton disruption on the constitutive internalization and recycling of the cystic fibrosis transmembrane conductance regulator (CFTR) channel. The results implicate the cytoskeleton network as a potential modulator of immobilized CFTR pool size at the plasma membrane and the recycling efficiency of endocytosed channel back to the cell surface.     

Deciphering the genomic architecture of the stickleback brain with a novel multilocus gene‐mapping approach

Quantitative traits important to organismal function and fitness, such as brain size, are presumably controlled by many small‐effect loci. Deciphering the genetic architecture of such traits with traditional quantitative trait locus (QTL) mapping methods is challenging. Here, we investigated the genetic architecture of brain size (and the size of five different brain parts) in nine‐spined sticklebacks (Pungitius pungitius) with the aid of novel multilocus QTL‐mapping approaches based on a de‐biased LASSO method. Apart from having more statistical power to detect QTL and reduced rate of false positives than conventional QTL‐mapping approaches, the developed methods can handle large marker panels and provide estimates of genomic heritability. Single‐locus analyses of an F₂ interpopulation cross with 239 individuals and 15 198, fully informative single nucleotide polymorphisms (SNPs) uncovered 79 QTL associated with variation in stickleback brain size traits. Many of these loci were in strong linkage disequilibrium (LD) with each other, and consequently, a multilocus mapping of individual SNPs, accounting for LD structure in the data, recovered only four significant QTL. However, a multilocus mapping of SNPs grouped by linkage group (LG) identified 14 LGs (1–6 depending on the trait) that influence variation in brain traits. For instance, 17.6% of the variation in relative brain size was explainable by cumulative effects of SNPs distributed over six LGs, whereas 42% of the variation was accounted for by all 21 LGs. Hence, the results suggest that variation in stickleback brain traits is influenced by many small‐effect loci. Apart from suggesting moderately heritable (h² ≈ 0.15–0.42) multifactorial genetic architecture of brain traits, the results highlight the challenges in identifying the loci contributing to variation in quantitative traits. Nevertheless, the results demonstrate that the novel QTL‐mapping approach developed here has distinctive advantages over the traditional QTL‐mapping methods in analyses of dense marker panels.