Investigation of 17 candidate genes for personality traits confirms effects of the HTR2A gene on novelty seeking

Genes involved in serotonergic and dopaminergic neurotransmission have been hypothesized to affect different aspects of personality, but findings from genetic association studies did not provide conclusive results so far. In previous studies, however, only one or a few polymorphisms within single genes were investigated neglecting the possibility that the genetic associations might be more complex comprising several genes or gene regions. To overcome this limitation, we performed an extended genetic association study analyzing 17 serotonergic ( SLC6A4, HTR1A, HTR1B, HTR2A, HTR2C, HTR3A, HTR6, MAOA, TPH1, TPH2 ) and dopaminergic genes ( SLC6A3, DRD2, DRD3, DRD4, COMT, MAOA, TH, DBH ), which have been previously reported to be implicated with personality traits.
One hundred and ninety-five single nucleotide polymorphisms (SNPs) within these genes were genotyped with the Illumina BeadChip technology (HumanHap300, Human-1) in a sample of 366 mentally healthy Caucasians. Additionally, we tried to replicate our results in an independent sample of further 335 Caucasians. Personality traits in both samples were assessed with the German version of Cloninger's Tridimensional Personality Questionnaire.
From 30 SNPs showing associations at a nominal level of significance, two intronic SNPs, rs2770296 and rs927544, both located in the HTR2A gene, withstood correction for multiple testing. These SNPs were associated with the personality trait novelty seeking . The effect of rs927544 could be replicated for the novelty seeking subscale extravagance , and the same SNP was also associated with extravagance inthe combined samples.
Our results show that HTR2A polymorphisms modulate facets of novelty seeking behaviour in healthy adults suggesting that serotonergic neurotransmission is involved in this phenotype.     

In a comfort zone and beyond—Ecological plasticity of key marine mediators

Copepods of the genus Calanus are the key components of zooplankton. Understanding their response to a changing climate is crucial to predict the functioning of future warmer high‐latitude ecosystems. Although specific Calanus species are morphologically very similar, they have different life strategies and roles in ecosystems. In this study, C. finmarchicus and C. glacialis were thoroughly studied with regard to their plasticity in morphology and ecology both in their preferred original water mass (Atlantic vs. Arctic side of the Polar Front) and in suboptimal conditions (due to, e.g., temperature, turbidity, and competition in Hornsund fjord). Our observations show that “at the same place and time,” both species can reach different sizes, take on different pigmentation, be in different states of population development, utilize different reproductive versus lipid accumulation strategies, and thrive on different foods. Size was proven to be a very mutable morphological trait, especially with regard to reduced length of C. glacialis. Both species exhibited pronounced red pigmentation when inhabiting their preferred water mass. In other domains, C. finmarchicus individuals tended to be paler than C. glacialis individuals. Gonad maturation and population development indicated mixed reproductive strategies, although a surprisingly similar population age structure of the two co‐occurring species in the fjord was observed. Lipid accumulation was high and not species‐specific, and its variability was due to diet differences of the populations. According to the stable isotope composition, both species had a more herbivorous diatom‐based diet in their original water masses. While the diet of C. glacialis was rather consistent among the domains studied, C. finmarchicus exhibited much higher variability in its feeding history (based on lipid composition). Our results show that the plasticity of both Calanus species is indeed impressive and may be regulated differently, depending on whether they live in their “comfort zone” or beyond it.     

Plant species diversity in Mediterranean old-growth forests: A case study from central Italy

Abstract

To investigate the differences in understorey composition and diversity between old-growth and managed forests, we analyzed an old-growth and a managed beech stand in the same area displaying similar abiotic features. We considered variations in understorey species composition and richness. The sampled understorey species were characterized in terms of functional traits, Ellenberg's indicator values and taxonomic distinctness; next, we calculated four different pairwise plot-to-plot dissimilarity matrices based on species composition, functional traits, Ellenberg's indices and taxonomic distances. We applied a permutational multivariate extension of ANOVA to test whether the forest stands significantly differ in the considered features. Indicator values of all plant species in managed and old-growth stands were evaluated.

The old-growth forest had a higher species richness; permutational analysis of variance showed significant differences between the two stands in plant species composition, functional traits, Ellenberg indices and taxonomic distances. Indicator species analysis highlighted 14 indicator species for the unmanaged stand, while only 3 indicators were found for the managed one.

The results suggest that forest management determines ecological differences that strongly affect plant species composition.

The knowledge of natural stands dynamics could allow development of new approaches and practices in forest management focusing on biodiversity conservation.     

Adaptive inter-population differences in blue tit life-history traits on Corsica

Few studies of natural populations have investigated how phenotypic variation across populations relates to key factors in the environment and landscape structure. In the blue tits of southern France, inter-population differences in reproductive life-history traits (e.g. laying date and clutch size) are small, whatever the timing of maximum caterpillar availability, a key factor for offspring survival in tits. These small differences are attributed to gene flow between local populations occupying different habitat types. In contrast, in blue tits on the island of Corsica, we noted large differences in reproductive life-history traits between two populations, where each population is synchronized with the peak-date of caterpillar abundance. These occur over a short geographical distance (25km). Considering our study within a framework of long-term population studies in tits, our results support the hypothesis that different blue tit populations on Corsica show adaptive differences in life-history traits, and suggest that landscape structure at a small spatial scale can have profound effects on adaptive between-population differentiation in life-history traits that are closely linked with fitness.     

Testing the rare-alleles model of quantitative variation by artificial selection

The rare-alleles model of quantitative variation posits that a common allele (the ‘wild-type’) and one or more rare alleles segregate at each locus affecting a quantitative trait; a scenario predicted by several distinct evolutionary hypotheses. Single locus arguments suggest that artificial selection should substantially increase the genetic variance (Vg) if the rare-alleles model is accurate. This paper tests the ‘ΔVg prediction’ using a large artificial selection experiment on flower size of Mimulus guttatus. Vg for flower size does evolve, increasing with selection for larger flower while decreasing in the other direction. These data are consistent with a model in which flower size variation is caused by rare, partially dominant alleles. However, this explanation becomes increasingly tenuous when considered with other data (correlated responses to selection and the effects of inbreeding). A combination of modern (marker-based mapping) and classical (biometric) techniques will likely to be required to determine the distribution of allele frequencies at loci influencing quantitative traits.     

Magnetic field dependence of radical-pair decay kinetics and molecular triplet quantum yield in quinone-depleted reaction centers

Radical-pair decay kinetics and molecular triplet quantum yields at various magnetic fields are reported for quinone-depleted reaction centers from the photosynthetic bacterium Rhodopseudomonas sphaeroides R26. The radical-pair decay is observed by picosecond absorption spectroscopy to be a single exponential to within the experimental uncertainty at all fields. The decay time increases from 13 ns at zero field to 17 ns at 1 kG, and decreases to 9 ns at 50 kG. The orientation averaged quantum yield of formation of the molecular triplet of the primary electron donor, ³P, drops to 47% of its zero-field value at 1 kG and rises to 126% at 50 kG. Combined analysis of these data gives a singlet radical-pair decay rate constant of 5 · 10⁷s^?1, a lower limit for the triplet radical-pair decay rate constant of 1 · 10⁸s^?1 and a lower limit for the quantum yield of radical-pair decay by the triplet channel of 38% at zero field. The upper limit of the quantum yield of ³P formation at zero field is measured to be 32%. In order to explain this apparent discrepancy, decay of the radical pair by the triplet channel must lead to some rapid ground state formation as well as some ³P formation. It is proposed that the triplet radical pair decays to a triplet charge-transfer state which is strongly coupled to the ground state by spin-orbit interactions. Several possibilities for this charge-transfer state are discussed.     

Linking Physiology To Ecological Function: Environmental Conditions Affect Performance And Size Of The Intertidal Kelp Hedophyllum Sessile (Laminariales,Phaeophyceae)

For autogenic ecosystem engineers, body size is an aspect of individual performance that has direct connections to community structure; yet the complex morphology of these species can make it difficult to draw clear connections between the environment and performance. We combined laboratory experiments and field surveys to test the hypothesis that individual body size was determined by disparate localized physiological responses to environmental conditions across the complex thallus of the intertidal kelp Hedophyllum sessile, a canopy‐forming physical ecosystem engineer. We documented substantial (> 40%) declines in whole‐thallus photosynthetic potential (as Maximum Quantum Yield, MQY) as a consequence of emersion, which were related to greater than 10‐fold increases in intra‐thallus MQY variability (as Coefficient of Variation). In laboratory experiments, desiccation and high light levels during emersion led to lasting impairment of photosynthetic potential and an immediate > 25% reduction in area due to tissue contraction, which was followed by complete loss of structural integrity after three days of submersion. Tissue exposed to desiccation and high light during emersion had higher nitrogen concentrations and lower phlorotannin concentrations than tissue in control treatments (on average 1.36 and 0.1x controls, respectively), suggesting that conditions during emersion have the potential to affect food quality for consumers. Our data indicate that the complex thallus morphology of H. sessile may be critical to this kelp’s ability to persist in the intertidal zone despite the physiological challenges of emersion and encourage a more nuanced view of the concept of “sub‐lethal stress” on the scale of the whole individual.     

Tree functional traits as predictors of microburst-associated treefalls in tropical wet forests

On 19 May 2018, a microburst caused 600 isolated forest gaps in a Costa Rican tropical forest. We surveyed fallen and standing trees within gaps to determine whether certain variables are associated with treefalls. Our results highlight considerations for future research to understand the impacts of microbursts in tropical forests.     

Lipid droplet proteins and metabolic diseases

Lipid droplets (LDs) are ubiquitous cellular organelles for lipid storage which are composed of a neutral lipid core bounded by a protein decorated phospholipid monolayer. Although lipid storage is their most obvious function, LDs are far from inert as they participate in maintaining lipid homeostasis through lipid synthesis, metabolism, and transportation. Furthermore, they are involved in cell signaling and other molecular events closely associated with human disease such as dyslipidemia, obesity, lipodystrophy, diabetes, fatty liver, atherosclerosis, and others. The last decade has seen a great increase in the attention paid to LD biology. Regardless, many fundamental features of LD biology remain obscure. In this review, we will discuss key aspects of LD biology including their biogenesis, growth and regression. We will also summarize the current knowledge about the role LDs play in human disease, especially from the perspective of the dynamics of the associated proteins. This article is part of a Special issue entitled Cardiac adaptations to obesity, diabetes and insulin resistance, edited by Professors Jan F.C. Glatz, Jason R.B. Dyck and Christine Des Rosiers.