Genetics of Dispersal

Dispersal is a process of central importance for the ecological and evolutionary dynamics of populations and communities, because of its diverse consequences for gene flow and demography. It is subject to evolutionary change, which begs the question, what is the genetic basis of this potentially complex trait? To address this question, we (i) review the empirical literature on the genetic basis of dispersal, (ii) explore how theoretical investigations of the evolution of dispersal have represented the genetics of dispersal, and (iii) discuss how the genetic basis of dispersal influences theoretical predictions of the evolution of dispersal and potential consequences. Dispersal has a detectable genetic basis in many organisms, from bacteria to plants and animals. Generally, there is evidence for significant genetic variation for dispersal or dispersal-related phenotypes or evidence for the micro-evolution of dispersal in natural populations. Dispersal is typically the outcome of several interacting traits, and this complexity is reflected in its genetic architecture: while some genes of moderate to large effect can influence certain aspects of dispersal, dispersal traits are typically polygenic. Correlations among dispersal traits as well as between dispersal traits and other traits under selection are common, and the genetic basis of dispersal can be highly environment-dependent. By contrast, models have historically considered a highly simplified genetic architecture of dispersal. It is only recently that models have started to consider multiple loci influencing dispersal, as well as non-additive effects such as dominance and epistasis, showing that the genetic basis of dispersal can influence evolutionary rates and outcomes, especially under non-equilibrium conditions. For example, the number of loci controlling dispersal can influence projected rates of dispersal evolution during range shifts and corresponding demographic impacts. Incorporating more realism in the genetic architecture of dispersal is thus necessary to enable models to move beyond the purely theoretical towards making more useful predictions of evolutionary and ecological dynamics under current and future environmental conditions. To inform these advances, empirical studies need to answer outstanding questions concerning whether specific genes underlie dispersal variation, the genetic architecture of context-dependent dispersal phenotypes and behaviours, and correlations among dispersal and other traits.Peer reviewe

Scientific Opinion on the evaluation of the substances currently on the list in the annex to Commission Directive 96/3/EC as acceptable previous cargoes for edible fats and oils – Part III of III

Shipping of edible fats and oils into Europe is permitted in bulk tanks, in which substances, included in a positive list, had been previously transported. The European Commission requested EFSA to evaluate the list of substances in the Annex to Commission Directive 96/3/EC as acceptable previous cargoes for edible fats and oils, taking into account its review of the Scientific Committee on Food criteria for acceptable previous cargoes and criteria proposed by the Codex Committee for Fats and Oils. This is the third and last scientific opinion of the EFSA Panel on Contaminants in the Food Chain (CONTAM Panel) on this topic, in which sixteen of these substances or groups of substances have been evaluated. The CONTAM Panel concluded that sodium silicate (water glass) solution, iso-octanol, iso-nonanol, iso-decanol, 1,3-propanediol, isobutyl acetate, sec-butyl acetate, tert-butyl acetate, n-butyl acetate, propylene tetramer, paraffin wax, candelilla wax, white mineral oils and glycerol would not be of health concern as previous cargoes. The CONTAM Panel concluded that carnauba wax was not acceptable as a previous cargo because of its insolubility in water and high melting point, which raise concerns regarding the efficiency of tank cleaning. There was insufficient information available on the composition of montan wax for the CONTAM Panel to conclude that it would be of no health concern when used as previous cargo and hence it does not meet the criteria for acceptability as previous cargo. The CONTAM Panel made several recommendations regarding the way in which the substances are described in the Annex to Commission Directive 96/3/EC, to correct inaccuracies and to better reflect current transport practices

Biochar Effects on Mycorrhizal Fungi in Sagebrush Roots

Non-native annual grasses such as cheatgrass (Bromus tectorum) are fueling more extensive and frequent fires in sagebrush-steppe ecosystems. These disturbances have changed soil biological properties inhibiting native sagebrush (Artemisia tridentata) reestablishment. Sagebrush depends on symbiotic soil fungi (AMF) to enhance nutrient uptake. Biochar, a plant-based charcoal used as an ameliorant for soil health, can positively impact AMF colonization in some plants. We hypothesized that adding soil from an intact sagebrush stand, which harbors AMF, in combination with biochar would increase root colonization by AMF in sagebrush seedlings grown in post-fire soil. We grew sagebrush seedlings in post-fire soil in the greenhouse for three months. We added an inoculum of sagebrush soil that had not burned, and half of the pots received a biochar treatment (dose). Upon harvest, we measured the percent of fungal colonization in roots via the line intercept method. Our preliminary findings show no significant increase in root colonization by AMF with biochar added to post-fire field soil. Similar studies conducted in other fires showed contradictory results, suggesting an interaction between biochar and soil microbial communities that vary among ecosystems. Further research into soil amendments and their influence on AMF could greatly benefit post-fire sagebrush restoration efforts

Role of Apoptosis in Modulating Effects of 2-Aminoanthracene in Pancreatic Tissue of Sprague Dawley Rat Dams

Modulation of the toxic effects of 2-aminoanthracene (2AA) on pancreatic tissue by apoptosis will be investigated. 2AA, also called anthramine, is a polycyclic aromatic hydrocarbon that is used in the manufacturing of chemicals, dyes, and inks, and it is also found in tobacco smoke and cooked foods. It is known to cause gene dysregulation, particularly of several genes of the pancreas that mediate protein and lipid metabolism (Gato and Means, 2011). To help determine the role of apoptosis in modulating the effects of 2AA, pancreatic tissue of Sprague Dawley rat dams exposed to various concentrations of 2AA for during gestation through postpartum will be analyzed for apoptotic activity using TUNEL apoptosis assay. This will be followed by total RNA extraction. The activity of Casp3, which plays a central role in the execution phase of apoptosis, will also be analyzed via assay, and relative gene expression of specific apoptotic genes will be quantified using qRT-PCR to test for significant differences in gene expression

Molecular Structure of Sphingomyelin in Fluid Phase Bilayers Determined by the Joint Analysis of Small-Angle Neutron and X-ray Scattering Data

Copyright © 2020 American Chemical Society. We have determined the fluid bilayer structure of palmitoyl sphingomyelin (PSM) and stearoyl sphingomyelin (SSM) by simultaneously analyzing small-angle neutron and X-ray scattering data. Using a newly developed scattering density profile (SDP) model for sphingomyelin lipids, we report structural parameters including the area per lipid, total bilayer thickness, and hydrocarbon thickness, in addition to lipid volumes determined by densitometry. Unconstrained all-atom simulations of PSM bilayers at 55 °C using the C36 CHARMM force field produced a lipid area of 56 Å2, a value that is 10% lower than the one determined experimentally by SDP analysis (61.9 Å2). Furthermore, scattering form factors calculated from the unconstrained simulations were in poor agreement with experimental form factors, even though segmental order parameter (SCD) profiles calculated from the simulations were in relatively good agreement with SCD profiles obtained from NMR experiments. Conversely, constrained area simulations at 61.9 Å2 resulted in good agreement between the simulation and experimental scattering form factors, but not with SCD profiles from NMR. We discuss possible reasons for the discrepancies between these two types of data that are frequently used as validation metrics for molecular dynamics force fields

Inhibition of Phospholipase Dα by N-Acylethanolamines

N-Acylethanolamines (NAEs) are endogenous lipids in plants produced from the phospholipid precursor, N-acylphosphatidylethanolamine, by phospholipase D (PLD). Here, we show that seven types of plant NAEs differing in acyl chain length and degree of unsaturation were potent inhibitors of the well-characterized, plant-specific isoform of PLD—PLDα. It is notable that PLDα, unlike other PLD isoforms, has been shown not to catalyze the formation of NAEs from N-acylphosphatidylethanolamine. In general, inhibition of PLDα activity by NAEs increased with decreasing acyl chain length and decreasing degree of unsaturation, such that N-lauroylethanolamine and N-myristoylethanolamine were most potent with IC(50)s at submicromolar concentrations for the recombinant castor bean (Ricinus communis) PLDα expressed in Escherichia coli and for partially purified cabbage (Brassica oleracea) PLDα. NAEs did not inhibit PLD from Streptomyces chromofuscus, and exhibited only moderate, mixed effects for two other recombinant plant PLD isoforms. Consistent with the inhibitory biochemical effects on PLDα in vitro, N-lauroylethanolamine, but not lauric acid, selectively inhibited abscisic acid-induced closure of stomata in epidermal peels of tobacco (Nicotiana tabacum cv Xanthi) and Commelina communis at low micromolar concentrations. Together, these results provide a new class of biochemical inhibitors to assist in the evaluation of PLDα physiological function(s), and they suggest a novel, lipid mediator role for endogenously produced NAEs in plant cells