Comparative phylogeography of two sympatric beeches in subtropical China: Species‐specific geographic mosaic of lineages

In subtropical China, large‐scale phylogeographic comparisons among multiple sympatric plants with similar ecological preferences are scarce, making generalizations about common response to historical events necessarily tentative. A phylogeographic comparison of two sympatric Chinese beeches (Fagus lucida and F. longipetiolata, 21 and 28 populations, respectively) was conducted to test whether they have responded to historical events in a concerted fashion and to determine whether their phylogeographic structure is exclusively due to Quaternary events or it is also associated with pre‐Quaternary events. Twenty‐three haplotypes were recovered for F. lucida and F. longipetiolata (14 each one and five shared). Both species exhibited a species‐specific mosaic distribution of haplotypes, with many of them being range‐restricted and even private to populations. The two beeches had comparable total haplotype diversity but F. lucida had much higher within‐population diversity than F. longipetiolata. Molecular dating showed that the time to most recent common ancestor of all haplotypes was 6.36 Ma, with most haplotypes differentiating during the Quaternary. [Correction added on 14 October 2013, after first online publication: the time unit has been corrected to ‘6.36’.] Our results support a late Miocene origin and southwards colonization of Chinese beeches when the aridity in Central Asia intensified and the monsoon climate began to dominate the East Asia. During the Quaternary, long‐term isolation in subtropical mountains of China coupled with limited gene flow would have lead to the current species‐specific mosaic distribution of lineages.     

Punish and Voice: Punishment Enhances Cooperation when Combined with Norm-Signalling

Material punishment has been suggested to play a key role in sustaining human cooperation. Experimental findings, however, show that inflicting mere material costs does not always increase cooperation and may even have detrimental effects. Indeed, ethnographic evidence suggests that the most typical punishing strategies in human ecologies (e.g., gossip, derision, blame and criticism) naturally combine normative information with material punishment. Using laboratory experiments with humans, we show that the interaction of norm communication and material punishment leads to higher and more stable cooperation at a lower cost for the group than when used separately. In this work, we argue and provide experimental evidence that successful human cooperation is the outcome of the interaction between instrumental decision-making and the norm psychology humans are provided with. Norm psychology is a cognitive machinery to detect and reason upon norms that is characterized by a salience mechanism devoted to track how much a norm is prominent within a group. We test our hypothesis both in the laboratory and with an agent-based model. The agent-based model incorporates fundamental aspects of norm psychology absent from previous work. The combination of these methods allows us to provide an explanation for the proximate mechanisms behind the observed cooperative behaviour. The consistency between the two sources of data supports our hypothesis that cooperation is a product of norm psychology solicited by norm-signalling and coercive devices.     

Increased Endoparasite Infection in Late-Arriving Individuals of a Trans-Saharan Passerine Migrant Bird

Earlier migration in males than in females is the commonest pattern in migrating passerines and is positively related to size dimorphism and dichromatism. The early arrival of males is a costly trait that may confer reproductive advantages in terms of better territories and/or mates. Given the physiological cost of migration, early migrants are those in best condition and accordingly the prevalence, load, and/or diversity of parasites is expected to increase in both sexes for late migrants. To test this hypothesis, we sampled 187 trans-Saharan migrant garden warblers Sylvia borin and 64 resident serins Serinus serinus (as a control for potential circannual patterns in parasite load) during spring migration in Spain. We assessed the prevalence of blood parasites (Haemoproteus, Plasmodium, and Leucocytozoon) and the prevalence and load of intestinal parasites (mainly coccidians and spirurids). The relationship between parasite (prevalence, load, and richness) and the timing of passage through a stopover area was tested using generalized linear models. Protandry occurs in the monomorphic garden warbler and males migrated on average 5.5 days before females. Intestinal parasite richness increased with the date of migration. The timing of migration was unrelated to the presence or load of the other parasite groups analyzed. Our results support the idea that the timing of migration is a condition-dependent trait and suggests that multiple intestinal parasite infestations could delay migration in birds. Even in monomorphic species parasites may play a role in sexual selection by delaying the arrival of the most infected individuals at breeding grounds, thereby further increasing the benefits of mating with early-arriving individuals.     

Cocaine Inhibits Dopamine D2 Receptor Signaling via Sigma-1-D2 Receptor Heteromers

Under normal conditions the brain maintains a delicate balance between inputs of reward seeking controlled by neurons containing the D₁-like family of dopamine receptors and inputs of aversion coming from neurons containing the D₂-like family of dopamine receptors. Cocaine is able to subvert these balanced inputs by altering the cell signaling of these two pathways such that D₁ reward seeking pathway dominates. Here, we provide an explanation at the cellular and biochemical level how cocaine may achieve this. Exploring the effect of cocaine on dopamine D₂ receptors function, we present evidence of σ₁ receptor molecular and functional interaction with dopamine D₂ receptors. Using biophysical, biochemical, and cell biology approaches, we discovered that D₂ receptors (the long isoform of the D₂ receptor) can complex with σ₁ receptors, a result that is specific to D₂ receptors, as D₃ and D₄ receptors did not form heteromers. We demonstrate that the σ₁-D₂ receptor heteromers consist of higher order oligomers, are found in mouse striatum and that cocaine, by binding to σ₁ -D₂ receptor heteromers, inhibits downstream signaling in both cultured cells and in mouse striatum. In contrast, in striatum from σ₁ knockout animals these complexes are not found and this inhibition is not seen. Taken together, these data illuminate the mechanism by which the initial exposure to cocaine can inhibit signaling via D₂ receptor containing neurons, destabilizing the delicate signaling balance influencing drug seeking that emanates from the D₁ and D₂ receptor containing neurons in the brain.     

Polymorphisms in DNA-Repair Genes in a Cohort of Prostate Cancer Patients from Different Areas in Spain: Heterogeneity between Populations as a Confounding Factor in Association Studies

Background

Differences in the distribution of genotypes between individuals of the same ethnicity are an important confounder factor commonly undervalued in typical association studies conducted in radiogenomics.

Objective

To evaluate the genotypic distribution of SNPs in a wide set of Spanish prostate cancer patients for determine the homogeneity of the population and to disclose potential bias.

Design, Setting, and Participants

A total of 601 prostate cancer patients from Andalusia, Basque Country, Canary and Catalonia were genotyped for 10 SNPs located in 6 different genes associated to DNA repair: XRCC1 (rs25487, rs25489, rs1799782), ERCC2 (rs13181), ERCC1 (rs11615), LIG4 (rs1805388, rs1805386), ATM (rs17503908, rs1800057) and P53 (rs1042522). The SNP genotyping was made in a Biotrove OpenArray® NT Cycler.

Outcome Measurements and Statistical Analysis

Comparisons of genotypic and allelic frequencies among populations, as well as haplotype analyses were determined using the web-based environment SNPator. Principal component analysis was made using the SnpMatrix and XSnpMatrix classes and methods implemented as an R package. Non-supervised hierarchical cluster of SNP was made using MultiExperiment Viewer.

Results and Limitations

We observed that genotype distribution of 4 out 10 SNPs was statistically different among the studied populations, showing the greatest differences between Andalusia and Catalonia. These observations were confirmed in cluster analysis, principal component analysis and in the differential distribution of haplotypes among the populations. Because tumor characteristics have not been taken into account, it is possible that some polymorphisms may influence tumor characteristics in the same way that it may pose a risk factor for other disease characteristics.

Conclusion

Differences in distribution of genotypes within different populations of the same ethnicity could be an important confounding factor responsible for the lack of validation of SNPs associated with radiation-induced toxicity, especially when extensive meta-analysis with subjects from different countries are carried out.     

Grapevine xylem response to fungi involved in trunk diseases

Grapevine trunk diseases (GTD), caused by a wide range of different fungi, are responsible for decline and productivity losses in vines at all growth stages. Grapevine responses to fungal attack include morphological and physiochemical defence mechanisms in the vascular system to reduce fungal infections. However, the extent to which these responses could control further spread by GTD‐fungi in the xylem vessels is poorly known. This study shows the formation of tyloses inside xylem vessels of diseased grapevines, as well as extracellular ligninolytic activities [lignin peroxidase, manganese peroxidase (MnP) and/or laccase] exhibited by some GTD‐fungi isolated here from symptomatic grapevines. In particular, Botryosphaeriaceae spp. and Phaeoacremonium minimum showed all three lignin‐degrading enzymatic activities. We also examined whether selected vine phenolic compounds, often located in the vascular system in response to fungal infection, could affect the lignin‐degrading activity from those GTD‐fungi as well as fungal colonisation. We found that phenolic compounds appeared to inhibit MnP activity, in addition to reducing fungal growth by causing anomalies in the hyphae morphology. Our results support that affected grapevines can initiate the tylosis formation in order to constrain fungi in the xylem vessels, while highlight the complementary action of the phenolic compounds to inhibit the fungi growth and colonisation. Phenolic compounds are therefore likely to have important role in alternative strategies for preventing trunk diseases.     

Phosphorus accumulates faster than nitrogen globally in freshwater ecosystems under anthropogenic impacts

Combined effects of cumulative nutrient inputs and biogeochemical processes that occur in freshwater under anthropogenic eutrophication could lead to myriad shifts in nitrogen (N):phosphorus (P) stoichiometry in global freshwater ecosystems, but this is not yet well‐assessed. Here we evaluated the characteristics of N and P stoichiometries in bodies of freshwater and their herbaceous macrophytes across human‐impact levels, regions and periods. Freshwater and its macrophytes had higher N and P concentrations and lower N : P ratios in heavily than lightly human‐impacted environments, further evidenced by spatiotemporal comparisons across eutrophication gradients. N and P concentrations in freshwater ecosystems were positively correlated and N : P was negatively correlated with population density in China. These results indicate a faster accumulation of P than N in human‐impacted freshwater ecosystems, which could have large effects on the trophic webs and biogeochemical cycles of estuaries and coastal areas by freshwater loadings, and reinforce the importance of rehabilitating these ecosystems.