Pest pressure,hurricanes, and genotype interact to strongly impact stem form in young loblolly pine (Pinus taeda L.) along the coastal plain of North Carolina

Key message

Stem defects in loblolly pine due to insect pests and wind damage can decrease economic value and affect ecosystem function, however silvicultural management can decrease the impact of these stresses.

Abstract

Loblolly pine (Pinus taeda L.) is one of the most important tree crops in the southern United States, comprising 45 % of commercial forestry land. Stem defects can reduce timber product quality and influence competitive interactions. We examined the effects of controlling Nantucket pine tip moth (Rhyacionia frustrata Scudder in Comstock, 1880) and site management (fertilizer or herbicide use) on stem defects, of two full-sib families (C1 and C2) and two clonal varieties (V1 and V2) of loblolly pine at upper and lower coastal plain sites in North Carolina (UCP and LCP, respectively). At UCP, V1 and V2 had fewer stem defects with insecticide treatment indicating that pest pressure affected stem form. C2 had twice as many defects as other genotypes at LCP, while C1 had the most defects at UCP, showing that carefully matching site and genotype could improve plantation performance without increasing costs. Additionally, we examined the effects of Hurricane Irene on stem leaning at LCP. V1, the tallest genotype, was most strongly affected, indicating genotype differences in tolerance to this form of abiotic stress. Interestingly, insecticide treatment decreased the negative effects of the hurricane on C1 stem lean, indicating that tip moth pressure may make C1 more susceptible. Our results illustrate that the interaction of biotic and abiotic stressors, such as pest infestation and climate, can strongly impact stem form, potentially affecting ecophysiological function and economic value. Cost-effective silvicultural options, such as pest control and management of genetic resources can potentially decrease exposure to such environmental risk.     

Genome-Wide Analysis of Cold Adaptation in Indigenous Siberian Populations

Following the dispersal out of Africa, where hominins evolved in warm environments for millions of years, our species has colonised different climate zones of the world, including high latitudes and cold environments. The extent to which human habitation in (sub-)Arctic regions has been enabled by cultural buffering, short-term acclimatization and genetic adaptations is not clearly understood. Present day indigenous populations of Siberia show a number of phenotypic features, such as increased basal metabolic rate, low serum lipid levels and increased blood pressure that have been attributed to adaptation to the extreme cold climate. In this study we introduce a dataset of 200 individuals from ten indigenous Siberian populations that were genotyped for 730,525 SNPs across the genome to identify genes and non-coding regions that have undergone unusually rapid allele frequency and long-range haplotype homozygosity change in the recent past. At least three distinct population clusters could be identified among the Siberians, each of which showed a number of unique signals of selection. A region on chromosome 11 (chr11:66–69 Mb) contained the largest amount of clustering of significant signals and also the strongest signals in all the different selection tests performed. We present a list of candidate cold adaption genes that showed significant signals of positive selection with our strongest signals associated with genes involved in energy regulation and metabolism (CPT1A, LRP5, THADA) and vascular smooth muscle contraction (PRKG1). By employing a new method that paints phased chromosome chunks by their ancestry we distinguish local Siberian-specific long-range haplotype signals from those introduced by admixture.     

The connecting cilium inner scaffold provides a structural foundation that protects against retinal degeneration

Inherited retinal degeneration due to loss of photoreceptor cells is a leading cause of human blindness. These cells possess a photosensitive outer segment linked to the cell body through the connecting cilium (CC). While structural defects of the CC have been associated with retinal degeneration, its nanoscale molecular composition, assembly, and function are barely known. Here, using expansion microscopy and electron microscopy, we reveal the molecular architecture of the CC and demonstrate that microtubules are linked together by a CC inner scaffold containing POC5, CENTRIN, and FAM161A. Dissecting CC inner scaffold assembly during photoreceptor development in mouse revealed that it acts as a structural zipper, progressively bridging microtubule doublets and straightening the CC. Furthermore, we show that Fam161a disruption in mouse leads to specific CC inner scaffold loss and triggers microtubule doublet spreading, prior to outer segment collapse and photoreceptor degeneration, suggesting a molecular mechanism for a subtype of retinitis pigmentosa.

Inherited retinal degeneration due to loss of photoreceptor cells is a leading cause of human blindness. Ultrastructure expansion microscopy on mouse retina reveals the presence of a novel structure inside the photoreceptor connecting cilium, the inner scaffold, that protects the outer segment against degeneration.     

Simulation of direct shear tests on rooted and non-rooted soil using finite element analysis

The finite element (FE) method has been used in recent years to simulate overturning processes in trees and to better comprehend plant anchorage mechanics. We aimed at understanding the fundamental mechanisms of root-soil reinforcement by simulating direct shear of rooted and non-rooted soil. Two- (2D) and three-dimensional (3D) FE simulations of direct shear box tests were carried out using readily available software for routine strength assessment of the root-soil composite. Both rooted and non-rooted blocks of soil were modelled using a simplified model of root distribution and root material properties representative of real roots. Linear elastic behaviour was assumed for roots and the soil was modelled as an ideally plastic medium. FE analysis showed that direct shear tests were dependent on the material properties specified for both the soil and roots. 2D and 3D simulations of direct shear of non-rooted soil produced similar results and any differences between 2D and 3D simulations could be explained with regard to the spatial complexity of roots used in the root distribution model. The application of FE methods was verified through direct shear tests on soil with analogue roots and the results compared to in situ tests on rooted soil in field conditions.     

Analysis of the Proenkephalin Second Messenger-Inducible Enhancer in Rat Striatal Cultures

Abstract: We have previously shown that in cell extracts from rat striatum, cyclic AMP response element (CRE) binding protein (CREB), rather than AP-1 proteins, preferentially interacts with the CRE-2 element of the proenkephalin second messenger-inducible enhancer, even under conditions in which AP-1 proteins are highly induced. Here we use primary striatal cultures to permit a more detailed analysis of CRE-2 function and protein binding in relevant neural cell types. By transfection we find that in primary striatal cultures, as in transformed cell lines, the CRE-1 and CRE-2 elements are required for significant induction by cyclic AMP. We report that cyclic AMP induction of the proenkephalin gene in striatal cultures is protein synthesis independent, excluding a role for newly synthesized proteins like c-Fos. We also show that cyclic AMP induces CREB phosphorylation and that phosphorylated CREB interacts strongly with CRE-2 and weakly with CRE-1. The predominant protein bound to CRE-1 is not CREB, however, and remains to be identified. Despite some prior predictions, we do not find a role for c-Fos in cyclic AMP regulation of proenkephalin gene expression in neurons.     

Civility vs. Incivility in Online Social Interactions: An Evolutionary Approach

Evidence is growing that forms of incivility–e.g. aggressive and disrespectful behaviors, harassment, hate speech and outrageous claims–are spreading in the population of social networking sites’ (SNS) users. Online social networks such as Facebook allow users to regularly interact with known and unknown others, who can behave either politely or rudely. This leads individuals not only to learn and adopt successful strategies for using the site, but also to condition their own behavior on that of others. Using a mean field approach, we define anevolutionary game framework to analyse the dynamics of civil and uncivil ways of interaction in online social networks and their consequences for collective welfare. Agents can choose to interact with others–politely or rudely–in SNS, or to opt out from online social networks to protect themselves from incivility. We find that, when the initial share of the population of polite users reaches a critical level, civility becomes generalized if its payoff increases more than that of incivility with the spreading of politeness in online interactions. Otherwise, the spreading of self-protective behaviors to cope with online incivility can lead the economyto non-socially optimal stationary states. JEL Codes: C61, C73, D85, O33, Z13. PsycINFO Codes: 2240, 2750.