Highly structured populations of copepods at risk to deep-sea mining: Integration of genomic data with demogenetic and biophysical modelling

Copepoda is the most abundant taxon in deep-sea hydrothermal vents, where hard substrate is available. Despite the increasing interest in seafloor massive sulphides exploitation, there have been no population genomic studies conducted on vent meiofauna, which are known to contribute over 50% to metazoan biodiversity at vents. To bridge this knowledge gap, restriction-site-associated DNA sequencing, specifically 2b-RADseq, was used to retrieve thousands of genome-wide single-nucleotide polymorphisms (SNPs) from abundant populations of the vent-obligate copepod Stygiopontius lauensis from the Lau Basin. SNPs were used to investigate population structure, demographic histories and genotype-environment associations at a basin scale. Genetic analyses also helped to evaluate the suitability of tailored larval dispersal models and the parameterization of life-history traits that better fit the population patterns observed in the genomic dataset for the target organism. Highly structured populations were observed on both spatial and temporal scales, with divergence of populations between the north, mid, and south of the basin estimated to have occurred after the creation of the major transform fault dividing the Australian and the Niuafo'ou tectonic plate (350 kya), with relatively recent secondary contact events (<20 kya). Larval dispersal models were able to predict the high levels of structure and the highly asymmetric northward low-level gene flow observed in the genomic data. These results differ from most studies conducted on megafauna in the region, elucidating the need to incorporate smaller size when considering site prospecting for deep-sea exploitation of seafloor massive sulphides, and the creation of area-based management tools to protect areas at risk of local extinction, should mining occur.

Cell-cycle-linked growth reprogramming encodes developmental time into leaf morphogenesis

How is time encoded into organ growth and morphogenesis? We address this question by investigating heteroblasty, where leaf development and form are modified with progressing plant age. By combining morphometric analyses, fate-mapping through live-imaging, computational analyses, and genetics, we identify age-dependent changes in cell-cycle-associated growth and histogenesis that underpin leaf heteroblasty. We show that in juvenile leaves, cell proliferation competence is rapidly released in a "proliferation burst" coupled with fast growth, whereas in adult leaves, proliferative growth is sustained for longer and at a slower rate. These effects are mediated by the SPL9 transcription factor in response to inputs from both shoot age and individual leaf maturation along the proximodistal axis. SPL9 acts by activating CyclinD3 family genes, which are sufficient to bypass the requirement for SPL9 in the control of leaf shape and in heteroblastic reprogramming of cellular growth. In conclusion, we have identified a mechanism that bridges across cell, tissue, and whole-organism scales by linking cell-cycle-associated growth control to age-dependent changes in organ geometry.

Genealogical Analyses of 3 Cultivated and 1 Wild Specimen of Vitis vinifera from Greece

Grapevine (Vitis vinifera) has been an important crop with considerable cultural and economic significance for over 2,500 years, and Greece has been an important entry point into Europe for lineages that were domesticated in Western Asia and the Caucasus. However, whole-genome-based investigation of the demographic history of Greek cultivars relative to other European lineages has only started recently. To understand how Greek cultivars relate to Eurasian domesticated and wild populations, we sequenced 3 iconic domesticated strains ('Xinomavro,' 'Agiorgitiko,' 'Mavrotragano') along with 1 wild accession (the vinetree of Pausanias-a historically important wild specimen) and analyzed their genomic diversity together with a large sample of publicly available domesticated and wild strains. We also reconstructed genealogies by leveraging the powerful tsinfer methodology which has not previously been used in this system. We show that cultivated strains from Greece differ genetically from other strains in Europe. Interestingly, all the 3 cultivated Greek strains clustered with cultivated and wild accessions from Transcaucasia, South Asia, and the Levant and are amongst the very few cultivated European strains belonging to this cluster. Furthermore, our results indicate that 'Xinomavro' shares close genealogical proximity with European elite cultivars such as 'Chardonnay,' 'Riesling,' and 'Gamay' but not 'Pinot.' Therefore, the proximity of 'Xinomavro' to Gouais/Heunisch Weiss is confirmed and the utility of ancestral recombination graph reconstruction approaches to study genealogical relationships in crops is highlighted.

Transition to Self-compatibility Associated With Dominant S-allele in a Diploid Siberian Progenitor of Allotetraploid Arabidopsis kamchatica Revealed by Arabidopsis lyrata Genomes

A transition to selfing can be beneficial when mating partners are scarce, for example, due to ploidy changes or at species range edges. Here, we explain how self-compatibility evolved in diploid Siberian Arabidopsis lyrata, and how it contributed to the establishment of allotetraploid Arabidopsis kamchatica. First, we provide chromosome-level genome assemblies for two self-fertilizing diploid A. lyrata accessions, one from North America and one from Siberia, including a fully assembled S-locus for the latter. We then propose a sequence of events leading to the loss of self-incompatibility in Siberian A. lyrata, date this independent transition to ∼90 Kya, and infer evolutionary relationships between Siberian and North American A. lyrata, showing an independent transition to selfing in Siberia. Finally, we provide evidence that this selfing Siberian A. lyrata lineage contributed to the formation of the allotetraploid A. kamchatica and propose that the selfing of the latter is mediated by the loss-of-function mutation in a dominant S-allele inherited from A. lyrata.

Pan-European study of genotypes and phenotypes in the Arabidopsis relative Cardamine hirsuta reveals how adaptation, demography, and development shape diversity patterns

We study natural DNA polymorphisms and associated phenotypes in the Arabidopsis relative Cardamine hirsuta. We observed strong genetic differentiation among several ancestry groups and broader distribution of Iberian relict strains in European C. hirsuta compared to Arabidopsis. We found synchronization between vegetative and reproductive development and a pervasive role for heterochronic pathways in shaping C. hirsuta natural variation. A single, fast-cycling ChFRIGIDA allele evolved adaptively allowing range expansion from glacial refugia, unlike Arabidopsis where multiple FRIGIDA haplotypes were involved. The Azores islands, where Arabidopsis is scarce, are a hotspot for C. hirsuta diversity. We identified a quantitative trait locus (QTL) in the heterochronic SPL9 transcription factor as a determinant of an Azorean morphotype. This QTL shows evidence for positive selection, and its distribution mirrors a climate gradient that broadly shaped the Azorean flora. Overall, we establish a framework to explore how the interplay of adaptation, demography, and development shaped diversity patterns of 2 related plant species.

Diffuse skin findings secondary to lymph node tularemia in a patient with chronic rheumatoid arthritis on methotrexate

Tularemia has many atypical presentations which can represent a diagnostic challenge. The history is essential in the investigation of this disease. Bite-induced primary skin lesions should be distinguished from the infrequent immune-mediated secondary skin lesions. Herein, we present an atypical pseudovesicular rash secondary to Francisella tularensis.

Joint inference of evolutionary transitions to self-fertilization and demographic history using whole-genome sequences

The evolution from outcrossing to selfing is a transition that occurred recurrently throughout the eukaryote tree of life, in plants, animals, fungi and algae. Despite some short-term advantages, selfing is supposed to be an evolutionary dead-end reproductive strategy on the long-term and its tippy distribution on phylogenies suggests that most selfing species are of recent origin. However, dating such transitions is challenging while it is central for this hypothesis. We build on previous theories to explicit the differential effect of past changes in selfing rate or in population size on the probability of recombination events along the genome. This allows us to develop two methods making use of full genome polymorphism data to 1) test if a transition from outcrossing to selfing occurred, and 2) infer its age. The sequentially Markov coalescent based (teSMC) and the Approximate Bayesian Computation (tsABC) methods use a common framework based on a transition matrix summarizing the distribution of times to the most recent common ancestor along the genome, allowing to estimate changes in the ratio of population recombination and mutation rates in time. We first demonstrate that our methods can disentangle between past change in selfing rate from past changes in demographic history. Second, we assess the accuracy of our methods and show that transitions to selfing as old as approximatively 2.5N_e generations can be identified from polymorphism data. Third, our estimates are robust to the presence of linked negative selection on coding sequences. Finally, as a proof of principle, we apply both methods to three populations from Arabidopsis thaliana, recovering a transition to selfing which occurred approximately 600,000 years ago. Our methods pave the way to study recent transitions to predominant self-fertilization in selfing organisms and to better account for variation in mating systems in demographic inferences.

An update on the applications and characteristics of magnetic iron oxide nanoparticles for drug delivery

INTRODUCTION

In the field of drug delivery, controlling the release of therapeutic substances at localized targets has become a primary focus of medical research, especially in the field of cancer treatment. Magnetic nanoparticles are one of the most promising drug carriers thanks to their biocompatibility and (super)paramagnetic properties. These properties allow for the combination between imaging modalities and specific release of drugs at target sites using either local stimulus (i.e. pH, conjugation of biomarkers, …) or external stimulus (i.e. external magnetic field).

AREAS COVERED

This review provides an update on recent advances with the development of targeted drug delivery systems based on magnetic nanoparticles (MNPs). This overview focuses on active targeting strategies and systems combining both imaging and therapeutic modalities (i.e. theranostics). If most of the examples concern the particular case of cancer therapy, the possibility of using MNPs for other medical applications is also discussed.

EXPERT OPINION

The development of clinically relevant drug delivery systems based on magnetic nanoparticles is driven by advantages stemming from their remarkable properties (i.e. easy preparation, facile chemical functionalization, biocompatibility, low toxicity and superior magnetic responsiveness). This literature review shows that drug carriers based on magnetic nanoparticles can be efficiently used for the controlled release of drug at targeted locations mediated by various stimuli. Advances in the field should lead to the implementation of such systems into clinical trials, especially systems enabling drug tracking in the body.

Gene expression evolution in pattern-triggered immunity within Arabidopsis thaliana and across Brassicaceae species

Plants recognize surrounding microbes by sensing microbe-associated molecular patterns (MAMPs) to activate pattern-triggered immunity (PTI). Despite their significance for microbial control, the evolution of PTI responses remains largely uncharacterized. Here, by employing comparative transcriptomics of six Arabidopsis thaliana accessions and three additional Brassicaceae species to investigate PTI responses, we identified a set of genes that commonly respond to the MAMP flg22 and genes that exhibit species-specific expression signatures. Variation in flg22-triggered transcriptome responses across Brassicaceae species was incongruent with their phylogeny, while expression changes were strongly conserved within A. thaliana. We found the enrichment of WRKY transcription factor binding sites in the 5'-regulatory regions of conserved and species-specific responsive genes, linking the emergence of WRKY-binding sites with the evolution of gene expression patterns during PTI. Our findings advance our understanding of the evolution of the transcriptome during biotic stress.

Impact of Genetic Variation in Gene Regulatory Sequences: A Population Genomics Perspective

The unprecedented rise of high-throughput sequencing and assay technologies has provided a detailed insight into the non-coding sequences and their potential role as gene expression regulators. These regulatory non-coding sequences are also referred to as cis-regulatory elements (CREs). Genetic variants occurring within CREs have been shown to be associated with altered gene expression and phenotypic changes. Such variants are known to occur spontaneously and ultimately get fixed, due to selection and genetic drift, in natural populations and, in some cases, pave the way for speciation. Hence, the study of genetic variation at CREs has improved our overall understanding of the processes of local adaptation and evolution. Recent advances in high-throughput sequencing and better annotations of CREs have enabled the evaluation of the impact of such variation on gene expression, phenotypic alteration and fitness. Here, we review recent research on the evolution of CREs and concentrate on studies that have investigated genetic variation occurring in these regulatory sequences within the context of population genetics.

Effects of disease-modifying therapy on peripheral leukocytes in patients with multiple sclerosis

Modern disease-modifying therapies (DMTs) in multiple sclerosis (MS) have variable modes of action and selectively suppress or modulate the immune system. In this review, we summarize the predicted and intended as well as unwanted adverse effects on leukocytes in peripheral blood as a result of treatment with DMTs for MS. We link changes in laboratory tests to the possible therapeutic risks that include secondary autoimmunity, infections, and impaired response to vaccinations. Profound knowledge of the intended effects on leukocyte counts, in particular lymphocytes, explained by the mode of action, and adverse effects which may require additional laboratory and clinical vigilance or even drug discontinuation, is needed when prescribing DMTs to treat patients with MS.

Les opioïdes : de la douleur à l’addiction ?

La crise des opioïdes actuelle aux États-Unis et sa médiatisation soulèvent la question de l’utilisation adéquate de ces antalgiques dans notre pratique quotidienne. En quatre vignettes cliniques, nous évoquons le travail conjoint des équipes d’addictologie et d’algologie pour prendre en charge au mieux les patients sous opioïdes en oncologie. Nous présentons les meilleurs moyens de diagnostiquer, prévenir et prendre en charge les écueils de ces traitements : la dépendance aux opioïdes de prescription et le mésusage des opioïdes de prescription, voire l’addiction aux opioïdes. Une des clés de cette prise en charge est la multidisciplinarité, centrale dans la réunion de concertation pluridisciplinaire.

Regorafenib after failure of gemcitabine and platinum-based chemotherapy for locally advanced/metastatic biliary tumors: REACHIN, a randomized, double-blind, phase II trial

BACKGROUND

There is a high unmet clinical need for treatments of advanced/metastatic biliary tract cancers after progression on first-line chemotherapy. Regorafenib has demonstrated efficacy in some gastrointestinal tumors that progress on standard therapies.

PATIENTS AND METHODS

REACHIN was a multicenter, double-blind, placebo-controlled, randomized phase II study designed to evaluate the safety and efficacy of regorafenib in patients with nonresectable/metastatic biliary tract cancer that progressed after gemcitabine/platinum chemotherapy. Patients were randomly assigned 1 : 1 to best supportive care plus either regorafenib 160 mg once daily 3 weeks on/1 week off or placebo until progression or unacceptable toxicity. No crossover was allowed. The primary objective was progression-free survival (PFS). Secondary objectives were response rate, overall survival, and translational analysis.

RESULTS

Sixty-six patients with intrahepatic (n = 42), perihilar (n = 6), or extrahepatic (n = 9) cholangiocarcinoma, or gallbladder carcinoma (n = 9) were randomized, 33 to each treatment group (33 per group). At a median follow-up of 24 months, all patients had progressed and six patients were alive. Median treatment duration was 11.0 weeks [95% confidence interval (CI): 6.0-15.9] in the regorafenib group and 6.3 weeks (95% CI: 3.9-7.0) in the placebo group (P = 0.002). Fourteen of 33 patients (42%) in the regorafenib group had a dose reduction. Stable disease rates were 74% (95% CI: 59-90) in the regorafenib group and 34% with placebo (95% CI: 18-51; P = 0.002). Median PFS in the regorafenib group was 3.0 months (95% CI: 2.3-4.9) and 1.5 months (95% CI: 1.2-2.0) in the placebo group (hazard ratio 0.49; 95% CI: 0.29-0.81; P = 0.004) and median overall survival was 5.3 months (95% CI: 2.7-10.5) and 5.1 months (95% CI: 3.0-6.4), respectively (P = 0.28). There were no unexpected/new safety signals.

CONCLUSION

Regorafenib significantly improved PFS and tumor control in patients with previously treated metastatic/unresectable biliary tract cancer in the second- or third-line setting.

CLINICAL TRIAL REGISTRATION

The trial is registered in the European Clinical Trials Register database (EudraCT 2012-005626-30) and at ClinicalTrials.gov (NCT02162914).

Autoregulation of RCO by Low-Affinity Binding Modulates Cytokinin Action and Shapes Leaf Diversity

Mechanisms through which the evolution of gene regulation causes morphological diversity are largely unclear. The tremendous shape variation among plant leaves offers attractive opportunities to address this question. In cruciferous plants, the REDUCED COMPLEXITY (RCO) homeodomain protein evolved via gene duplication and acquired a novel expression domain that contributed to leaf shape diversity. However, the molecular pathways through which RCO regulates leaf growth are unknown. A key question is to identify genome-wide transcriptional targets of RCO and the DNA sequences to which RCO binds. We investigate this question using Cardamine hirsuta, which has complex leaves, and its relative Arabidopsis thaliana, which evolved simple leaves through loss of RCO. We demonstrate that RCO directly regulates genes controlling homeostasis of the hormone cytokinin to repress growth at the leaf base. Elevating cytokinin signaling in the RCO expression domain is sufficient to both transform A. thaliana simple leaves into complex ones and partially bypass the requirement for RCO in C. hirsuta complex leaf development. We also identify RCO as its own target gene. RCO directly represses its own transcription via an array of low-affinity binding sites, which evolved after RCO duplicated from its progenitor sequence. This autorepression is required to limit RCO expression. Thus, evolution of low-affinity binding sites created a negative autoregulatory loop that facilitated leaf shape evolution by defining RCO expression and fine-tuning cytokinin activity. In summary, we identify a transcriptional mechanism through which conflicts between novelty and pleiotropy are resolved during evolution and lead to morphological differences between species.

The Demographic History of African Drosophila melanogaster

As one of the most commonly utilized organisms in the study of local adaptation, an accurate characterization of the demographic history of Drosophila melanogaster remains as an important research question. This owes both to the inherent interest in characterizing the population history of this model organism, as well as to the well-established importance of an accurate null demographic model for increasing power and decreasing false positive rates in genomic scans for positive selection. Although considerable attention has been afforded to this issue in non-African populations, less is known about the demographic history of African populations, including from the ancestral range of the species. While qualitative predictions and hypotheses have previously been forwarded, we here present a quantitative model fitting of the population history characterizing both the ancestral Zambian population range as well as the subsequently colonized west African populations, which themselves served as the source of multiple non-African colonization events. We here report the split time of the West African population at 72 kya, a date corresponding to human migration into this region as well as a period of climatic changes in the African continent. Furthermore, we have estimated population sizes at this split time. These parameter estimates thus represent an important null model for future investigations in to African and non-African D. melanogaster populations alike.

P1539Aortic pulse wave velocity measured by an oscillometric device independently predicts all-cause mortality in a cohort of 4146 subjects

Objectives

Assessment of carotid-femoral pulse wave velocity by applanation tonometry independently predicts all-cause and cardiovascular mortality. However, there has been a need for a simpler, user-independent measurement with a validated device, that is applicable even in the primary care setting.

Methods and subjects

4146 subjects (49% men) aged 35–75 years were measured in multiple centers in Hungary. Subjects visited the outpatient department of these centers on their own initiative. The measurement of aortic pulse wave velocity (PWVao) with Arteriograph was performed in addition to taking past medical history, physical examination and laboratory tests. The mean follow-up time of the study was 5.5 years. The number of events (all cause mortality) were provided by the Hungarian National Health Insurance Fund. Cox regression analyses were used to identify predictive factors for this endpoint.

Results

The mean age of the study population was 53 years, brachial systolic and diastolic blood pressure were 137±20 and 82±11 mmHg, and heart rate was 70±10 1/min. The mean value of SCORE was 3 in this large cohort. 410 subjects had a registered cerebro-or cardiovascular event before the measurement, the number of smokers was 656 (16%), 1974 subjects were treated with at least one anti-hypertensive drug (48%), while the number of subjects on lipid-lowering, antidiabetic or antiplatelet medication were 807 (19%), 352 (8%) and 398 (17%), respectively. There were 116 fatal events during a mean follow-up of 5.5 years. According to the Cox regression, PWVao is a significant and independent predictor of all cause-mortality and in univariate analysis, a 1.0 m/s increase in PWVao was associated with HR 1.7 [1.47–1.98; p<0.001], for this endpoint.

Conclusion

Aortic pulse wave velocity measured by an invasively validated, simple, oscillometric device predicted all-cause mortality in a large cohort of relatively young subjects of the general population that may improve risk stratification even in the everyday clinical practice or primary care setting.

P1553Differential association between vascular and chronological age with cardiovascular outcomes

Background/Introduction

Increased pulse wave velocity (PWV), is a reliable marker of early vascular aging (EVA). However, the identification of individuals whose arteries are abnormally healthy in comparison to their age and cardiovascular (CV) risk profile might be of interest, to discover novel pathways of cardioprotection and provide preventive strategies for successful vascular aging.

Purpose

1) to provide a novel calculation for vascular age and examine his determinants; 2) to test the hypothesis that individuals with the largest difference between chronological and vascular age (C-V age) show a lower rate of CV events than their counterparts, and may thus be defined as the supernormal vascular aging group (SUPERNOVA).

Methods

Vascular age was defined as predicted age based on classical CV risk factors and PWV. The best fitting model for vascular age was investigated in the multicenter, European, cross-sectional Reference Values for Arterial stiffness Collaboration Database (n=11406). Continuous variables were modelled as smoothing splines. Thereafter, the risk of fatal and non-fatal CV events associated with C-V age was examined in the longitudinal cohort of the Malmo Diet and Cancer Study (n=2663) using Cox proprotional hazard regression models. C-V age was examined as a continuous variable (natural splines) and as a 3 levels categorical variables based on the best grouping of the deciles of C-V age and corresponding to the EVA (<3.0 years), normal vascular aging (3.0 to 8.8 years) and SUPERNOVA (>8.8 years) respectively.

Results

In the Reference Values Cohort (age range 17–85 years, 52.4% men, 38.1% hypertensives, 3.9% diabetics, average PWV 7.8 m/s), the most significant predictor of vascular age (full model r2 0.598) was PWV. In the Malmo Diet and Cancer Study Cohort (age 61–89 years, 63.6% men, 64.0% hypertensives, 12.9% diabetics, PWV 11.5 m/s), during follow-up (6.6 years on average), 286 individuals developed a first cardiovascular event. In the Cox survival analysis, C-V age was significantly and inversely associated with CV events. Compare to normal vascular aging, participants with SUPERNOVA had lower risk for CV events [HR 0.51 (0.34–0.76)] whereas those with EVA had a higher risk [HR 2.71 (1.80–4.09)]. Instead, there was no significant association with all-cause mortality.

Conclusions

The use of PWV and CV risk factors may be useful to define early and supernormal vascular aging in particular, and to assess its clinical relevance towards the risk of cardiovascular disease and death.

Dendron based antifouling, MRI and magnetic hyperthermia properties of different shaped iron oxide nanoparticles

Owing to the great potential of iron oxide nanoparticles (NPs) for nanomedicine, large efforts have been made to better control their magnetic properties, especially their magnetic anisotropy to provide NPs able to combine imaging by MRI and therapy by magnetic hyperthermia. In that context, the design of anisotropic NPs appears as a very promising and efficient strategy. Furthermore, their bioactive coating also remains a challenge as it should provide colloidal stability, biocompatibility, furtivity along with good water diffusion for MRI. By taking advantage of our controlled synthesis method of iron oxide NPs with different shapes (cubic, spherical, octopod and nanoplate), we demonstrate here that the dendron coating, shown previously to be very suitable for 10 nm sized iron oxide, also provided very good colloidal, MRI and antifouling properties to the anisotropic shaped NPs. These antifouling properties, demonstrated through several experiments and characterizations, are very promising to achieve specific targeting of disease tissues without affecting healthy organs. On the other hand, the magnetic hyperthermia properties were shown to depend on the saturation magnetization and the ability of NPs to self-align, confirming the need of a balance between crystalline and dipolar magnetic anisotropies.

Update on liver transplantation for cholangiocarcinoma : a review of the recent literature

Cholangiocarcinoma (CC) represent 3% of all gastrointestinal tumours and can be classified anatomically in 3 types: intrahepatic (ICC), perihilar (PCC) and distal (DCC) cholangiocarcinomas. Resection is the treatment of choice but is only achieved in a few cases (<20%) because of invasion of the biliary tract and/or vascular structures. The outcome of advanced CC is poor with an overall survival (OS) of maximum 15 months with chemotherapy. In the 1990s, CC was regarded as a contraindication for liver transplantation (LT). LT has recently been proposed as potentially curative option for ICC and PCC. Careful patient selection has changed OS. This article provides an update on current status of LT for patients with unresectable CC.

Demographic History of the Human Commensal Drosophila melanogaster

The cohabitation of Drosophila melanogaster with humans is nearly ubiquitous. Though it has been well established that this fly species originated in sub-Saharan Africa, and only recently has spread globally, many details of its swift expansion remain unclear. Elucidating the demographic history of D. melanogaster provides a unique opportunity to investigate how human movement might have impacted patterns of genetic diversity in a commensal species, as well as providing neutral null models for studies aimed at identifying genomic signatures of local adaptation. Here, we use whole-genome data from five populations (Africa, North America, Europe, Central Asia, and the South Pacific) to carry out demographic inferences, with particular attention to the inclusion of migration and admixture. We demonstrate the importance of these parameters for model fitting and show that how previous estimates of divergence times are likely to be significantly underestimated as a result of not including them. Finally, we discuss how human movement along early shipping routes might have shaped the present-day population structure of D. melanogaster.

The Evolutionary History of Nebraska Deer Mice: Local Adaptation in the Face of Strong Gene Flow

The interplay of gene flow, genetic drift, and local selective pressure is a dynamic process that has been well studied from a theoretical perspective over the last century. Wright and Haldane laid the foundation for expectations under an island-continent model, demonstrating that an island-specific beneficial allele may be maintained locally if the selection coefficient is larger than the rate of migration of the ancestral allele from the continent. Subsequent extensions of this model have provided considerably more insight. Yet, connecting theoretical results with empirical data has proven challenging, owing to a lack of information on the relationship between genotype, phenotype, and fitness. Here, we examine the demographic and selective history of deer mice in and around the Nebraska Sand Hills, a system in which variation at the Agouti locus affects cryptic coloration that in turn affects the survival of mice in their local habitat. We first genotyped 250 individuals from 11 sites along a transect spanning the Sand Hills at 660,000 single nucleotide polymorphisms across the genome. Using these genomic data, we found that deer mice first colonized the Sand Hills following the last glacial period. Subsequent high rates of gene flow have served to homogenize the majority of the genome between populations on and off the Sand Hills, with the exception of the Agouti pigmentation locus. Furthermore, mutations at this locus are strongly associated with the pigment traits that are strongly correlated with local soil coloration and thus responsible for cryptic coloration.

Prevalence, management and ethnobotanical investigation of hypertension in two Guinean urban districts

ETHNOPHARMACOLOGICAL RELEVANCE

Hypertension is an important public health challenge in low- and middle-income countries, and in many African countries including Guinea medicinal plants are still widely used for its treatment.

MATERIALS AND METHODS

The objective of this study was to determine the prevalence of hypertension in two Guinean urban districts (Pounthioun and Dowsare), to describe its management and to collect information on traditional herbal remedies. A total of 316 participants entered the study, 28.2% (89/316) men and 71.8% (227/316) women. Of these, 181 were from Dowsare (50 men and 131 women) and 135 from Pounthioun (39 men and 96 women). The mean age of subjects was 40.8 ± 14.0 years (range18 - 88years), while the majority of subjects (63.3% or 200/316) were 45-74 years old.

RESULTS

The overall prevalence of hypertension was 44.9% (142/316): 46.4% (84/181) from Dowsare and 43.0% (58/135) from Pounthioun. Ethnobotanical investigations among hypertensive patients led to the collection of 15 plant species, among which Hymenocardia acida leaves and Uapaca togoensis stem bark were the most cited. Phytochemical investigation of these two plant species led to the isolation and identification of isovitexin and isoorientin from H. acida, and betulinic acid and lupeol from U. togoensis.

CONCLUSION

The presence of these constituents in Hymenocardia acida leaves and Uapaca togoensis stem bark may at least in part support their traditional use against hypertension in Guinea.

Linking a mutation to survival in wild mice

Adaptive evolution in new or changing environments can be difficult to predict because the functional connections between genotype, phenotype, and fitness are complex. Here, we make these explicit connections by combining field and laboratory experiments in wild mice. We first directly estimate natural selection on pigmentation traits and an underlying pigment locus, Agouti, by using experimental enclosures of mice on different soil colors. Next, we show how a mutation in Agouti associated with survival causes lighter coat color through changes in its protein binding properties. Together, our findings demonstrate how a sequence variant alters phenotype and then reveal the ensuing ecological consequences that drive changes in population allele frequency, thereby illuminating the process of evolution by natural selection.

VSION as high field MRI T1 contrast agent: evidence of their potential as positive contrast agent for magnetic resonance angiography

Because of their outstanding magnetic properties, iron oxide nanoparticles have already been the subject of numerous studies in the biomedical field, in particular as a negative contrast agent for T₂-weighted nuclear magnetic resonance imaging, or as therapeutic agents in hyperthermia experiments. Recent studies have shown that below a given particle size (i.e. 5 nm), iron oxide may be used to provide a significant positive (brightening) effect on T₁-weighted MRI. In such an application, not only the size of the crystal, but also the control of the coating process is essential to ensure optimal properties, especially at a very high field (> 3 T). In this work, we focused on the development of very small iron oxide nanoparticles as a potential platform for high field T₁ magnetic resonance angiography (MRA) applications. The feasibility has been evaluated in vivo at 9.4 T, demonstrating the usefulness of the developed system for MRA applications.

Evaluation of the Active Targeting of Melanin Granules after Intravenous Injection of Dendronized Nanoparticles

The biodistribution of dendronized iron oxides, NPs10@D1_DOTAGA and melanin-targeting NPs10@D1_ICF_DOTAGA, was studied in vivo using magnetic resonance imaging (MRI) and planar scintigraphy through [¹⁷⁷Lu]Lu-radiolabeling. MRI experiments showed high contrast power of both dendronized nanoparticles (DPs) and hepatobiliary and urinary excretions. Little tumor uptake could be highlighted after intravenous injection probably as a consequence of the negatively charged DOTAGA-derivatized shell, which reduces the diffusion across the cells' membrane. Planar scintigraphy images demonstrated a moderate specific tumor uptake of melanoma-targeted [¹⁷⁷Lu]Lu-NPs10@D1_ICF_DOTAGA at 2 h post-intravenous injection (pi), and the highest tumor uptake of the control probe [¹⁷⁷Lu]Lu-NPs10@D1_DOTAGA at 30 min pi, probably due to the enhanced permeability and retention effect. In addition, ex vivo confocal microscopy studies showed a high specific targeting of human melanoma samples impregnated with NPs10@D1_ICF_Alexa647_ DOTAGA.

Reinvestigation of the mechanism of polymerization of β-butyrolactone from 1,5,7-triazabicyclo[4.4.0]dec-5-ene

The questionable mechanism initially proposed to explain how 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD) allows us to ring-open β-lactones, such as β-butyrolactone (BL), is reinvestigated here.

Characterization of Gd loaded chitosan-TPP nanohydrogels by a multi-technique approach combining dynamic light scattering (DLS), asymetrical flow-field-flow-fractionation (AF4) and atomic force microscopy (AFM) and design of positive contrast agents for molecular resonance imaging (MRI)

Chitosan CS-tripolyphosphate TPP/hyaluronic acid HA nanohydrogels loaded with gadolinium chelates (GdDOTA ⊂ CS-TPP/HA NGs) synthesized by ionic gelation were designed for lymph node (LN) MRI. In order to be efficiently drained to LNs, nanogels (NGs) needed to exhibit a diameter ϕ < 100 nm. For that, formulation parameters were tuned, using (i) CS of two different molecular weights (51 and 37 kDa) and (ii) variable CS/TPP ratio (2 < CS/TPP < 8). Characterization of NG size distribution by dynamic light scattering (DLS) and asymetrical flow-field-flow-fractionation (AF4) showed discrepancies since DLS diameters were consistently above 200 nm while AF4 showed individual nano-objects with ϕ < 100 nm. Such a difference could be correlated to the presence of aggregates inherent to ionic gelation. This point was clarified by atomic force microscopy (AFM) in liquid mode which highlighted the main presence of individual nano-objects in nanosuspensions. Thus, combination of DLS, AF4 and AFM provided a more precise characterization of GdDOTA ⊂ CS-TPP/HA nanohydrogels which, in turn, allowed to select formulations leading to NGs of suitable mean sizes showing good MRI efficiency and negligible toxicity.

How a grafting anchor tailors the cellular uptake and in vivo fate of dendronized iron oxide nanoparticles

Superparamagnetic iron oxide nanoparticles synthesized by thermal decomposition have been grafted with two dendrons bearing respectively a monophosphonic anchor (D2) or a biphosphonic tweezer (D2-2P) at their focal point.

Minor changes in the macrocyclic ligands but major consequences on the efficiency of gold nanoparticles designed for radiosensitization

Many studies have been devoted to adapting the design of gold nanoparticles to efficiently exploit their promising capability to enhance the effects of radiotherapy. In particular, the addition of magnetic resonance imaging modality constitutes an attractive strategy for enhancing the selectivity of radiotherapy since it allows the determination of the most suited delay between the injection of nanoparticles and irradiation. This requires the functionalization of the gold core by an organic shell composed of thiolated gadolinium chelates. The risk of nephrogenic systemic fibrosis induced by the release of gadolinium ions should encourage the use of macrocyclic chelators which form highly stable and inert complexes with gadolinium ions. In this context, three types of gold nanoparticles (Au@DTDOTA, Au@TADOTA and Au@TADOTAGA) combining MRI, nuclear imaging and radiosensitization have been developed with different macrocyclic ligands anchored onto the gold cores. Despite similarities in size and organic shell composition, the distribution of gadolinium chelate-coated gold nanoparticles (Au@TADOTA-Gd and Au@TADOTAGA-Gd) in the tumor zone is clearly different. As a result, the intravenous injection of Au@TADOTAGA-Gd prior to the irradiation of 9L gliosarcoma bearing rats leads to the highest increase in lifespan whereas the radiophysical effects of Au@TADOTAGA-Gd and Au@TADOTA-Gd are very similar.

Genetic diversity of two Daphnia-infecting microsporidian parasites, based on sequence variation in the internal transcribed spacer region

Background

Microsporidia are spore-forming obligate intracellular parasites that include both emerging pathogens and economically important disease agents. However, little is known about the genetic diversity of microsporidia. Here, we investigated patterns of geographic population structure, intraspecific genetic variation, and recombination in two microsporidian taxa that commonly infect cladocerans of the Daphnia longispina complex in central Europe. Taken together, this information helps elucidate the reproductive mode and life-cycles of these parasite species.

Methods

Microsporidia-infected Daphnia were sampled from seven drinking water reservoirs in the Czech Republic. Two microsporidia species (Berwaldia schaefernai and microsporidium lineage MIC1) were sequenced at the internal transcribed spacer (ITS) region, using the 454 pyrosequencing platform. Geographical structure analyses were performed applying Fisher’s exact tests, analyses of molecular variance, and permutational MANOVA. To evaluate the genetic diversity of the ITS region, the number of polymorphic sites and Tajima’s and Watterson’s estimators of theta were calculated. Tajima’s D was also used to determine if the ITS in these taxa evolved neutrally. Finally, neighbour similarity score and pairwise homology index tests were performed to detect recombination events.

Results

While there was little variation among Berwaldia parasite strains infecting different host populations, the among-population genetic variation of MIC1 was significant. Likewise, ITS genetic diversity was lower in Berwaldia than in MIC1. Recombination signals were detected only in Berwaldia.

Conclusion

Genetic tests showed that parasite populations could have expanded recently after a bottleneck or that the ITS could be under negative selection in both microsporidia species. Recombination analyses might indicate cryptic sex in Berwaldia and pure asexuality in MIC1. The differences observed between the two microsporidian species present an exciting opportunity to study the genetic basis of microsporidia-Daphnia coevolution in natural populations, and to better understand reproduction in these parasites.

Electronic supplementary material

The online version of this article (doi:10.1186/s13071-016-1584-4) contains supplementary material, which is available to authorized users.