Carbon pool densities and a first estimate of the total carbon pool in the Mongolian forest‐steppe

The boreal forest biome represents one of the most important terrestrial carbon stores, which gave reason to intensive research on carbon stock densities. However, such an analysis does not yet exist for the southernmost Eurosiberian boreal forests in Inner Asia. Most of these forests are located in the Mongolian forest‐steppe, which is largely dominated by Larix sibirica. We quantified the carbon stock density and total carbon pool of Mongolia's boreal forests and adjacent grasslands and draw conclusions on possible future change. Mean aboveground carbon stock density in the interior of L. sibirica forests was 66 Mg C ha^?1, which is in the upper range of values reported from boreal forests and probably due to the comparably long growing season. The density of soil organic carbon (SOC, 108 Mg C ha^?1) and total belowground carbon density (149 Mg C ha^?1) are at the lower end of the range known from boreal forests, which might be the result of higher soil temperatures and a thinner permafrost layer than in the central and northern boreal forest belt. Land use effects are especially relevant at forest edges, where mean carbon stock density was 188 Mg C ha^?1, compared with 215 Mg C ha^?1 in the forest interior. Carbon stock density in grasslands was 144 Mg C ha^?1. Analysis of satellite imagery of the highly fragmented forest area in the forest‐steppe zone showed that Mongolia's total boreal forest area is currently 73 818 km², and 22% of this area refers to forest edges (defined as the first 30 m from the edge). The total forest carbon pool of Mongolia was estimated at ~ 1.5?1.7 Pg C, a value which is likely to decrease in future with increasing deforestation and fire frequency, and global warming.     

Horn length is not correlated with calling efforts in the horn‐headed cricket Loxoblemmus doenitzi (Orthoptera: Gryllidae)

Field cricket species are ideal model organisms for the study of sexual selection because cricket calling songs, used to attract mating partners, are pronouncedly sexually dimorphic. However, few studies have focused on other sexually dimorphic traits of field crickets. The horn‐headed cricket, Loxoblemmus doenitzi, exhibits exaggerated sexual dimorphism in head shape: males have flat heads with triangular horns, while females lack horns. This study examines the relationship between horn length, male calling efforts and diet quality. Horn length was not found to be significantly correlated with calling efforts. When diet was manipulated for late‐stage nymphs, calling efforts in the group with poor‐quality diet treatment was significantly lower than that of crickets in the group with high‐quality diet treatment. However, horn length was not affected by diet quality. The implication of these results in the context of the evolution of multiple signals and sexual dimorphism is discussed.     

The Orphan G Protein-coupled Receptor GPR17 Negatively Regulates Oligodendrocyte Differentiation via Gαi/o and Its Downstream Effector Molecules

Recent studies have recognized G protein-coupled receptors as important regulators of oligodendrocyte development. GPR17, in particular, is an orphan G protein-coupled receptor that has been identified as oligodendroglial maturation inhibitor because its stimulation arrests primary mouse oligodendrocytes at a less differentiated stage. However, the intracellular signaling effectors transducing its activation remain poorly understood. Here, we use Oli-neu cells, an immortalized cell line derived from primary murine oligodendrocytes, and primary rat oligodendrocyte cultures as model systems to identify molecular targets that link cell surface GPR17 to oligodendrocyte maturation blockade. We demonstrate that stimulation of GPR17 by the small molecule agonist MDL29,951 (2-carboxy-4,6-dichloro-1H-indole-3-propionic acid) decreases myelin basic protein expression levels mainly by triggering the Gα_i/o signaling pathway, which in turn leads to reduced activity of the downstream cascade adenylyl cyclase-cAMP-PKA-cAMP response element-binding protein (CREB). In addition, we show that GPR17 activation also diminishes myelin basic protein abundance by lessening stimulation of the exchange protein directly activated by cAMP (EPAC), thus uncovering a previously unrecognized role for EPAC to regulate oligodendrocyte differentiation. Together, our data establish PKA and EPAC as key downstream effectors of GPR17 that inhibit oligodendrocyte maturation. We envisage that treatments augmenting PKA and/or EPAC activity represent a beneficial approach for therapeutic enhancement of remyelination in those demyelinating diseases where GPR17 is highly expressed, such as multiple sclerosis.     

Polyceraty (multi‐horns) in Damara sheep maps to ovine chromosome 2

Polyceraty (presence of multiple horns) is rare in modern day ungulates. Although not found in wild sheep, polyceraty does occur in a small number of domestic sheep breeds covering a wide geographical region. Damara are fat‐tailed hair sheep, from the south‐western region of Africa, which display polyceraty, with horn number ranging from zero to four. We conducted a genome‐wide association study for horn number with 43 Damara genotyped with 606 006 SNP markers. The analysis revealed a region with multiple significant SNPs on ovine chromosome 2, in a location different from the mutation for polled in sheep on chromosome 10. The causal mutation for polyceraty was not identified; however, the region associated with polyceraty spans nine HOXD genes, which are critical in embryonic development of appendages. Mutations in HOXD genes are implicated in polydactly phenotypes in mice and humans. There was no evidence for epistatic interactions contributing to polyceraty. This is the first report on the genetic mechanisms underlying polyceraty in the under‐studied Damara.     

Conflicts over host manipulation between different parasites and pathogens: Investigating the ecological and medical consequences

When parasites have different interests in regard to how their host should behave this can result in a conflict over host manipulation, i.e. parasite induced changes in host behaviour that enhance parasite fitness. Such a conflict can result in the alteration, or even complete suppression, of one parasite's host manipulation. Many parasites, and probably also symbionts and commensals, have the ability to manipulate the behaviour of their host. Non‐manipulating parasites should also have an interest in host behaviour. Given the frequency of multiple parasite infections in nature, potential conflicts of interest over host behaviour and manipulation may be common. This review summarizes the evidence on how parasites can alter other parasite's host manipulation. Host manipulation can have important ecological and medical consequences. I speculate on how a conflict over host manipulation could alter these consequences and potentially offer a new avenue of research to ameliorate harmful consequences of host manipulation.     

Summary goodness‐of‐fit statistics for binary generalized linear models with noncanonical link functions

Generalized linear models (GLM) with a canonical logit link function are the primary modeling technique used to relate a binary outcome to predictor variables. However, noncanonical links can offer more flexibility, producing convenient analytical quantities (e.g., probit GLMs in toxicology) and desired measures of effect (e.g., relative risk from log GLMs). Many summary goodness‐of‐fit (GOF) statistics exist for logistic GLM. Their properties make the development of GOF statistics relatively straightforward, but it can be more difficult under noncanonical links. Although GOF tests for logistic GLM with continuous covariates (GLMCC) have been applied to GLMCCs with log links, we know of no GOF tests in the literature specifically developed for GLMCCs that can be applied regardless of link function chosen. We generalize the Tsiatis GOF statistic originally developed for logistic GLMCCs, (), so that it can be applied under any link function. Further, we show that the algebraically related Hosmer–Lemeshow () and Pigeon–Heyse (J²) statistics can be applied directly. In a simulation study, , , and J² were used to evaluate the fit of probit, log–log, complementary log–log, and log models, all calculated with a common grouping method. The statistic consistently maintained Type I error rates, while those of and J² were often lower than expected if terms with little influence were included. Generally, the statistics had similar power to detect an incorrect model. An exception occurred when a log GLMCC was incorrectly fit to data generated from a logistic GLMCC. In this case, had more power than or J².     

Readily Accessible Multiplane Microscopy: 3D Tracking the HIV‐1 Genome in Living Cells

Human immunodeficiency virus (HIV)‐1 infection and the associated disease AIDS are a major cause of human death worldwide with no vaccine or cure available. The trafficking of HIV‐1 RNAs from sites of synthesis in the nucleus, through the cytoplasm, to sites of assembly at the plasma membrane are critical steps in HIV‐1 viral replication, but are not well characterized. Here we present a broadly accessible microscopy method that captures multiple focal planes simultaneously, which allows us to image the trafficking of HIV‐1 genomic RNAs with high precision. This method utilizes a customization of a commercial multichannel emission splitter that enables high‐resolution 3D imaging with single‐macromolecule sensitivity. We show with high temporal and spatial resolution that HIV‐1 genomic RNAs are most mobile in the cytosol, and undergo confined mobility at sites along the nuclear envelope and in the nucleus and nucleolus. These provide important insights regarding the mechanism by which the HIV‐1 RNA genome is transported to the sites of assembly of nascent virions.