Chromosome-scale Genome Assembly of the Rough Periwinkle Littorina saxatilis

The intertidal gastropod Littorina saxatilis is a model system to study speciation and local adaptation. The repeated occurrence of distinct ecotypes showing different levels of genetic divergence makes L. saxatilis particularly suited to study different stages of the speciation continuum in the same lineage. A major finding is the presence of several large chromosomal inversions associated with the divergence of ecotypes and, specifically, the species offers a system to study the role of inversions in this divergence. The genome of L. saxatilis is 1.35 Gb and composed of 17 chromosomes. The first reference genome of the species was assembled using Illumina data, was highly fragmented (N50 of 44 kb), and was quite incomplete, with a BUSCO completeness of 80.1% on the Metazoan dataset. A linkage map of one full-sibling family enabled the placement of 587 Mbp of the genome into 17 linkage groups corresponding to the haploid number of chromosomes, but the fragmented nature of this reference genome limited the understanding of the interplay between divergent selection and gene flow during ecotype formation. Here, we present a newly generated reference genome that is highly contiguous, with a N50 of 67 Mb and 90.4% of the total assembly length placed in 17 super-scaffolds. It is also highly complete with a BUSCO completeness of 94.1% of the Metazoa dataset. This new reference will allow for investigations into the genomic regions implicated in ecotype formation as well as better characterization of the inversions and their role in speciation.

Diverse pathways to speciation revealed by marine snails

Speciation is a key evolutionary process that is not yet fully understood. Combining population genomic and ecological data from multiple diverging pairs of marine snails (Littorina) supports the search for speciation mechanisms. Placing pairs on a one-dimensional speciation continuum, from undifferentiated populations to species, obscured the complexity of speciation. Adding multiple axes helped to describe either speciation routes or reproductive isolation in the snails. Divergent ecological selection repeatedly generated barriers between ecotypes, but appeared less important in completing speciation while genetic incompatibilities played a key role. Chromosomal inversions contributed to genomic barriers, but with variable impact. A multidimensional (hypercube) approach supported framing of questions and identification of knowledge gaps and can be useful to understand speciation in many other systems.

Structural Variants and Speciation: Multiple Processes at Play

Research on the genomic architecture of speciation has increasingly revealed the importance of structural variants (SVs) that affect the presence, abundance, position, and/or direction of a nucleotide sequence. SVs include large chromosomal rearrangements such as fusion/fissions and inversions and translocations, as well as smaller variants such as duplications, insertions, and deletions (CNVs). Although we have ample evidence that SVs play a key role in speciation, the underlying mechanisms differ depending on the type and length of the SV, as well as the ecological, demographic, and historical context. We review predictions and empirical evidence for classic processes such as underdominance due to meiotic aberrations and the coupling effect of recombination suppression before exploring how recent sequencing methodologies illuminate the prevalence and diversity of SVs. We discuss specific properties of SVs and their impact throughout the genome, highlighting that multiple processes are at play, and possibly interacting, in the relationship between SVs and speciation.

Population Genomics Reveals the Underlying Structure of the Small Pelagic European Sardine and Suggests Low Connectivity within Macaronesia

The European sardine (Sardina pilchardus, Walbaum 1792) is indisputably a commercially important species. Previous studies using uneven sampling or a limited number of makers have presented sometimes conflicting evidence of the genetic structure of S. pilchardus populations. Here, we show that whole genome data from 108 individuals from 16 sampling areas across 5000 km of the species' distribution range (from the Eastern Mediterranean to the archipelago of Azores) support at least three genetic clusters. One includes individuals from Azores and Madeira, with evidence of substructure separating these two archipelagos in the Atlantic. Another cluster broadly corresponds to the center of the distribution, including the sampling sites around Iberia, separated by the Almeria-Oran front from the third cluster that includes all of the Mediterranean samples, except those from the Alboran Sea. Individuals from the Canary Islands appear to belong to the Mediterranean cluster. This suggests at least two important geographical barriers to gene flow, even though these do not seem complete, with many individuals from around Iberia and the Mediterranean showing some patterns compatible with admixture with other genetic clusters. Genomic regions corresponding to the top outliers of genetic differentiation are located in areas of low recombination indicative that genetic architecture also has a role in shaping population structure. These regions include genes related to otolith formation, a calcium carbonate structure in the inner ear previously used to distinguish S. pilchardus populations. Our results provide a baseline for further characterization of physical and genetic barriers that divide European sardine populations, and information for transnational stock management of this highly exploited species towards sustainable fisheries.

How chromosomal inversions reorient the evolutionary process

Inversions are structural mutations that reverse the sequence of a chromosome segment and reduce the effective rate of recombination in the heterozygous state. They play a major role in adaptation, as well as in other evolutionary processes such as speciation. Although inversions have been studied since the 1920s, they remain difficult to investigate because the reduced recombination conferred by them strengthens the effects of drift and hitchhiking, which in turn can obscure signatures of selection. Nonetheless, numerous inversions have been found to be under selection. Given recent advances in population genetic theory and empirical study, here we review how different mechanisms of selection affect the evolution of inversions. A key difference between inversions and other mutations, such as single nucleotide variants, is that the fitness of an inversion may be affected by a larger number of frequently interacting processes. This considerably complicates the analysis of the causes underlying the evolution of inversions. We discuss the extent to which these mechanisms can be disentangled, and by which approach.

The Impact of Chromosomal Rearrangements in Speciation: From Micro- to Macroevolution

Chromosomal rearrangements (CRs) have been known since almost the beginning of genetics. While an important role for CRs in speciation has been suggested, evidence primarily stems from theoretical and empirical studies focusing on the microevolutionary level (i.e., on taxon pairs where speciation is often incomplete). Although the role of CRs in eukaryotic speciation at a macroevolutionary level has been supported by associations between species diversity and rates of evolution of CRs across phylogenies, these findings are limited to a restricted range of CRs and taxa. Now that more broadly applicable and precise CR detection approaches have become available, we address the challenges in filling some of the conceptual and empirical gaps between micro- and macroevolutionary studies on the role of CRs in speciation. We synthesize what is known about the macroevolutionary impact of CRs and suggest new research avenues to overcome the pitfalls of previous studies to gain a more comprehensive understanding of the evolutionary significance of CRs in speciation across the tree of life.

Chromosomal inversion polymorphisms are widespread across the species ranges of rough periwinkles (Littorina saxatilis and L. arcana)

Inversions are thought to play a key role in adaptation and speciation, suppressing recombination between diverging populations. Genes influencing adaptive traits cluster in inversions, and changes in inversion frequencies are associated with environmental differences. However, in many organisms, it is unclear if inversions are geographically and taxonomically widespread. The intertidal snail, Littorina saxatilis, is one such example. Strong associations between putative polymorphic inversions and phenotypic differences have been demonstrated between two ecotypes of L. saxatilis in Sweden and inferred elsewhere, but no direct evidence for inversion polymorphism currently exists across the species range. Using whole genome data from 107 snails, most inversion polymorphisms were found to be widespread across the species range. The frequencies of some inversion arrangements were significantly different among ecotypes, suggesting a parallel adaptive role. Many inversions were also polymorphic in the sister species, L. arcana, hinting at an ancient origin.

Integrating Pool-seq uncertainties into demographic inference

Next-generation sequencing of pooled samples (Pool-seq) is a popular method to assess genome-wide diversity patterns in natural and experimental populations. However, Pool-seq is associated with specific sources of noise, such as unequal individual contributions. Consequently, using Pool-seq for the reconstruction of evolutionary history has remained underexplored. Here we describe a novel Approximate Bayesian Computation (ABC) method to infer demographic history, explicitly modelling Pool-seq sources of error. By jointly modelling Pool-seq data, demographic history and the effects of selection due to barrier loci, we obtain estimates of demographic history parameters accounting for technical errors associated with Pool-seq. Our ABC approach is computationally efficient as it relies on simulating subsets of loci (rather than the whole-genome) and on using relative summary statistics and relative model parameters. Our simulation study results indicate Pool-seq data allows distinction between general scenarios of ecotype formation (single versus parallel origin) and to infer relevant demographic parameters (e.g. effective sizes and split times). We exemplify the application of our method to Pool-seq data from the rocky-shore gastropod Littorina saxatilis, sampled on a narrow geographical scale at two Swedish locations where two ecotypes (Wave and Crab) are found. Our model choice and parameter estimates show that ecotypes formed before colonization of the two locations (i.e. single origin) and are maintained despite gene flow. These results indicate that demographic modelling and inference can be successful based on pool-sequencing using ABC, contributing to the development of suitable null models that allow for a better understanding of the genetic basis of divergent adaptation.

An allozyme polymorphism is associated with a large chromosomal inversion in the marine snail Littorina fabalis

Understanding the genetic targets of natural selection is one of the most challenging goals of population genetics. Some of the earliest candidate genes were identified from associations between allozyme allele frequencies and environmental variation. One such example is the clinal polymorphism in the arginine kinase (Ak) gene in the marine snail Littorina fabalis. While other enzyme loci do not show differences in allozyme frequencies among populations, the Ak alleles are near differential fixation across repeated wave exposure gradients in Europe. Here, we use this case to illustrate how a new sequencing toolbox can be employed to characterize the genomic architecture associated with historical candidate genes. We found that the Ak alleles differ by nine nonsynonymous substitutions, which perfectly explain the different migration patterns of the allozymes during electrophoresis. Moreover, by exploring the genomic context of the Ak gene, we found that the three main Ak alleles are located on different arrangements of a putative chromosomal inversion that reaches near fixation at the opposing ends of two transects covering a wave exposure gradient. This shows Ak is part of a large (3/4 of the chromosome) genomic block of differentiation, in which Ak is unlikely to be the only target of divergent selection. Nevertheless, the nonsynonymous substitutions among Ak alleles and the complete association of one allele with one inversion arrangement suggest that the Ak gene is a strong candidate to contribute to the adaptive significance of the inversion.

Representativeness of EXPLORER-HCM trial and prevalence of eligibility criteria for Mavacamten in a nationwide cohort

Introduction

The EXPLORER-HCM trial evaluated the safety and efficacy of Mavacamten, a cardiac myosin inhibitor, in symptomatic obstructive hypertrophic cardiomyopathy (HCM). Mavacamten improved symptoms, exercise capacity and left ventricular outflow tract (LVOT) obstruction. However, the proportion of patients eligible for this therapy in real practice remains unclear.

Purpose

To determine the prevalence of eligibility criteria for Mavacamten and to describe the profile of patients complying with EXPLORER-HCM criteria in a nationwide cohort.

Methods

Cross-sectional study including all HCM patients enrolled in a European country-based nationwide registry. Presence of EXPLORER-HCM inclusion [≥18 years, obstructive HCM (LVOT gradient ≥50 mmHg), left ventricular ejection fraction (LVEF) ≥55%, New York Heart Association (NYHA) class II–III] and exclusion criteria [syncope or sustained ventricular tachycardia with exercise] were analyzed.

Results

Of 1042 patients included in this analysis (57.8% male, mean age at diagnosis 52 years, 39.6% obstructive HCM), 45 met the EXPLORER-HCM inclusion criteria and, after applying exclusion criteria, 30 patients were eligible for therapy with Mavacamten.

Eligible patients were all Caucasian, mostly female (63.3%), with a mean age at diagnosis of 58±14 years. All patients presented with heart failure symptoms, and were mostly in NYHA class II (83.3%); 4 patients (13.3%) presented with atrial fibrillation. In the baseline echocardiogram, mean LVEF was 68±9%; mean interventricular septum thickness was 20±4 mm; most patients presented with systolic anterior motion of the mitral valve (96.7%) and mitral regurgitation (96.7%). In cardiac magnetic resonance imaging evaluation, maximal wall thickness was 22±4 mm and 76.9% had late gadolinium enhancement. A pathogenic or likely pathogenic HCM gene variant was identified in 5 patients (MYH7 and MYBPC3 gene mutations).

In this group, 86.2% of patients were treated with beta-blockers and 34.5% with calcium channel antagonists. Only 1 patient was on Disopyramide. Septal reduction techniques were used in 43.3% of patients: alcohol septal ablation and septal myectomy were performed in 7 (23.3%) and 6 (20.0%) patients, respectively. Cardioverter-defibrillators were implanted in 2 patients for primary prevention of sudden cardiac death, and 6 patients received a pacemaker for bradycardia indications.

Conclusion

Specific therapies remain an unmet need in HCM. In this large nationwide cohort, only 2.9% of patients were eligible for therapy with Mavacamten according to EXPLORER-HCM criteria. Among patients complying with the study criteria, invasive septal reduction therapies were offered to a high proportion of patients. Further real-world data are warranted to estimate the proportion of HCM patients that will benefit from Mavacamten.

Funding Acknowledgement

Type of funding sources: None.

Predictors of left ventricular dysfunction in hypertrophic cardiomyopathy: results from a nationwide registry

Introduction

Progression of hypertrophic cardiomyopathy (HCM) with incident left ventricular (LV) dysfunction (HCM-LVSD) is associated with poor prognosis and advanced heart failure (HF). Prevalence ranges from 5–10% in previous studies. Identification of predictors of adverse remodeling may improve risk stratification and prognostication in HCM.

Purpose

To identify predictors of HCM-LVSD in a nationwide cohort of HCM patients (pts).

Methods

Retrospective study including all HCM pts enrolled in a European country-based nationwide registry. HCM-LVSD group included pts with LV ejection fraction (LVEF) ≤50% at baseline and pts who developed LV dysfunction/dilated phenotype during follow-up. Multivariate logistic regression was performed to identify predictors of HCM-LVSD.

Results

1042 HCM patients (57.8% male, mean age at diagnosis 52 years) were included, of whom 81 (8%) belonged to the HCM-LVSD group. HCM-LVSD pts were mostly male (60.5%) and tended to be older at the time of diagnosis than those without LVSD (55 vs 52 years, p=0.054). HCM-LVSD pts were more often symptomatic at the index visit (84.1% vs 65.2%, p<0.001), with more functional impairment (New York Heart Association class III–IV: 18.5% vs 9.2%, p=0.021). Atrial fibrillation (21.3% vs 8.6%, p<0.001) and intraventricular conduction disturbances (28.6% vs 14.4%, p=0.002) were more prevalent in HCM-LVSD pts. HCM-LVSD pts had higher baseline left atrium (LA) volumes (52 vs 39 ml, p=0.001), lower LVEF (50 vs 67%, p<0.001) and higher rates of mitral regurgitation (79.0% vs 65.1%, p=0.011). Prevalence of obstructive HCM was lower in the HCM-LSVD group (25.3% vs 40.9%, p=0.007). Presence of late gadolinium enhancement (92.6% vs 74.6%, p=0.035) was more common in pts with LVSD. Baseline N-terminal pro–B-type natriuretic peptide was higher in HCM-LVSD (3839 vs 1281 pg/ml, p=0.027). There were no differences in the number and type of genetic variants between groups. In HCM-LVSD pts, implantation of cardioverter-defibrillators for secondary prevention was more frequent (28.6% vs 6.4%, p=0.002), as was the use of pacemaker (16.7% vs 7.0%, p=0.002). During a mean follow-up of 5.3±6.1 years, hospitalization for HF (50.0% vs 11.3%) and all-cause mortality (12.3% vs 2.9%, p<0.001) were more frequent in HCM-LVSD group.

After multivariate analysis, higher LA volume (odds ratio [OR] 1.03, 95% confidence interval [CI] 1.01–1.05, p=0.003) and nonobstructive HCM (OR 2.74, 95% CI 1.03–7.27, p=0.043) were independent predictors of HCM-LVSD.

Conclusions

In this large nationwide cohort of HCM pts, prevalence of LVSD was 8%, in line with existing literature. In this cohort, larger LA volumes and nonobstructive HCM predicted progression to HCM-LVSD.

Funding Acknowledgement

Type of funding sources: None.

Differing associations between sex determination and sex‐linked inversions in two ecotypes of Littorina saxatilis

Sexual antagonism is a common hypothesis for driving the evolution of sex chromosomes, whereby recombination suppression is favored between sexually antagonistic loci and the sex‐determining locus to maintain beneficial combinations of alleles. This results in the formation of a sex‐determining region. Chromosomal inversions may contribute to recombination suppression but their precise role in sex chromosome evolution remains unclear. Because local adaptation is frequently facilitated through the suppression of recombination between adaptive loci by chromosomal inversions, there is potential for inversions that cover sex‐determining regions to be involved in local adaptation as well, particularly if habitat variation creates environment‐dependent sexual antagonism. With these processes in mind, we investigated sex determination in a well‐studied example of local adaptation within a species: the intertidal snail, Littorina saxatilis. Using SNP data from a Swedish hybrid zone, we find novel evidence for a female‐heterogametic sex determination system that is restricted to one ecotype. Our results suggest that four putative chromosomal inversions, two previously described and two newly discovered, span the putative sex chromosome pair. We determine their differing associations with sex, which suggest distinct strata of differing ages. The same inversions are found in the second ecotype but do not show any sex association. The striking disparity in inversion‐sex associations between ecotypes that are connected by gene flow across a habitat transition that is just a few meters wide indicates a difference in selective regime that has produced a distinct barrier to the spread of the newly discovered sex‐determining region between ecotypes. Such sex chromosome‐environment interactions have not previously been uncovered in L. saxatilis and are known in few other organisms. A combination of both sex‐specific selection and divergent natural selection is required to explain these highly unusual patterns.

Inversions and parallel evolution

Local adaptation leads to differences between populations within a species. In many systems, similar environmental contrasts occur repeatedly, sometimes driving parallel phenotypic evolution. Understanding the genomic basis of local adaptation and parallel evolution is a major goal of evolutionary genomics. It is now known that by preventing the break-up of favourable combinations of alleles across multiple loci, genetic architectures that reduce recombination, like chromosomal inversions, can make an important contribution to local adaptation. However, little is known about whether inversions also contribute disproportionately to parallel evolution. Our aim here is to highlight this knowledge gap, to showcase existing studies, and to illustrate the differences between genomic architectures with and without inversions using simple models. We predict that by generating stronger effective selection, inversions can sometimes speed up the parallel adaptive process or enable parallel adaptation where it would be impossible otherwise, but this is highly dependent on the spatial setting. We highlight that further empirical work is needed, in particular to cover a broader taxonomic range and to understand the relative importance of inversions compared to genomic regions without inversions.

This article is part of the theme issue ‘Genomic architecture of supergenes: causes and evolutionary consequences’.

Longest sediment flows yet measured show how major rivers connect efficiently to deep sea

Here we show how major rivers can efficiently connect to the deep-sea, by analysing the longest runout sediment flows (of any type) yet measured in action on Earth. These seafloor turbidity currents originated from the Congo River-mouth, with one flow travelling >1,130 km whilst accelerating from 5.2 to 8.0 m/s. In one year, these turbidity currents eroded 1,338-2,675 [>535-1,070] Mt of sediment from one submarine canyon, equivalent to 19–37 [>7–15] % of annual suspended sediment flux from present-day rivers. It was known earthquakes trigger canyon-flushing flows. We show river-floods also generate canyon-flushing flows, primed by rapid sediment-accumulation at the river-mouth, and sometimes triggered by spring tides weeks to months post-flood. It is demonstrated that strongly erosional turbidity currents self-accelerate, thereby travelling much further, validating a long-proposed theory. These observations explain highly-efficient organic carbon transfer, and have important implications for hazards to seabed cables, or deep-sea impacts of terrestrial climate change.

This paper analyses the longest sediment flows measured in action on Earth. These seabed flows were caused by floods and spring tides, and flushed prodigious sediment and carbon volumes into the deep sea, as they accelerated for a thousand kilometres.

Ten years of demographic modelling of divergence and speciation in the sea

Understanding population divergence that eventually leads to speciation is essential for evolutionary biology. High species diversity in the sea was regarded as a paradox when strict allopatry was considered necessary for most speciation events because geographical barriers seemed largely absent in the sea, and many marine species have high dispersal capacities. Combining genome-wide data with demographic modelling to infer the demographic history of divergence has introduced new ways to address this classical issue. These models assume an ancestral population that splits into two subpopulations diverging according to different scenarios that allow tests for periods of gene flow. Models can also test for heterogeneities in population sizes and migration rates along the genome to account, respectively, for background selection and selection against introgressed ancestry. To investigate how barriers to gene flow arise in the sea, we compiled studies modelling the demographic history of divergence in marine organisms and extracted preferred demographic scenarios together with estimates of demographic parameters. These studies show that geographical barriers to gene flow do exist in the sea but that divergence can also occur without strict isolation. Heterogeneity of gene flow was detected in most population pairs suggesting the predominance of semipermeable barriers during divergence. We found a weak positive relationship between the fraction of the genome experiencing reduced gene flow and levels of genome-wide differentiation. Furthermore, we found that the upper bound of the 'grey zone of speciation' for our dataset extended beyond that found before, implying that gene flow between diverging taxa is possible at higher levels of divergence than previously thought. Finally, we list recommendations for further strengthening the use of demographic modelling in speciation research. These include a more balanced representation of taxa, more consistent and comprehensive modelling, clear reporting of results and simulation studies to rule out nonbiological explanations for general results.

Role of epicardial adipose tissue volume as predictor of atrial fibrillation recurrence

Funding Acknowledgements

Type of funding sources: None.

Background

Several studies have demonstrated the relation between general obesity and atrial fibrillation (AF). Epicardial adipose tissue (EAT), due to its local paracrine effect and the intimate relation with the atrium, could influence AF recurrence rates, but very few studies have explored this association.

Purpose

In this study we aimed to evaluate if EAT could be a predictor of AF recurrence after an AF ablation procedure.

Methods

We included all consecutive patients submitted to AF ablation (2017-2019) who performed a computed tomography scan prior to the procedure. EAT volume was semi-automatically reconstructed by manually tracing the pericardium. Adipose tissue was defined in the range between -150 and -50 Hounsfield units. Recurrence was defined as any documented (ECG/Holter) episode of AF, atrial flutter or atrial tachycardia after 3 months of the procedure. Logistic regression with a restricted cubic polynomial transformation was used to model the non-linear relationship between recurrence and EAT volumes. Inspection of the partial effect curves suggested that a cutoff for EAT volume ≥80mL could stratify patients at risk of recurrence and a Time-to-event analysis was carried.

Results

A total of 354 patients (66% male, median age 57 years [IQR 48–65] and 21% persistent AF) were included. During a median follow-up of 34 months [IQR 24-43], 117 patients (33%) had AF recurrence. These patients had a significantly greater EAT volume (76 mL [IQR 55-111] vs 72 mL [IQR 48-95], p=0.03) when compared to those without recurrence. Also, patients with higher EAT volume (≥ 80mL) had a higher risk of recurrence compared to patients with lower volume (Figure 1, log-rank test p=0.007). After adjusting for clinical risk factors (age, gender, hypertension, diabetes mellitus, obesity, thyroid disease, AF type and left atrial enlargement), higher EAT volume did not remain an independent predictor of AF recurrence (Figure 2, HR 1.25 [95% CI, 0.83-1.86] p=0.3).

Conclusion

In this cohort of patients with AF submitted to catheter ablation, EAT volume ≥80mL was associated with increased risk of AF recurrence. However, it was not an independent predictor of AF recurrence after adjustment to clinical risk factors.

Higher coronary calcium score is associated with increased risk of atrial fibrillation recurrence

Funding Acknowledgements

Type of funding sources: None.

Introduction

Patients with atrial fibrillation (AF) referred for catheter ablation routinely undergo cardiac computed tomography (CCT) for procedure planning. An opportunistic evaluation of coronary artery calcium score (CACS) can be an important tool to improve clinical care. It is already known that CACS is associated with a high risk of AF development, particularly if values are above 100, but few data are available regarding the impact of CACS in AF recurrence after ablation.

Purpose

To assess the impact of CACS on atrial fibrillation recurrence following catheter ablation.

Methods

Retrospective, single-centre cohort study of consecutive patients with AF undergoing CCT for ablation procedure planning, from 2017 to 2019. Baseline clinical and demographical data were collected. Patients with known history of coronary artery disease (CAD) and moderate to severe valvular heart disease were excluded. CACS was assessed using the Agatston method. Recurrence was defined as any documented episode of AF, atrial flutter or atrial tachycardia after 3 months from procedure. Patients were stratified in CACS<100 and CACS≥100. Explorative analysis incorporated Kaplan-Meier survival curves and Cox regression.

Results

A total of 354 patients were included, with a mean age of 56 ± 12 years, 66% male and 21% with persistent AF. More than half of the patients had a CACS>0 (n=185, 52%) and 63 patients (18%) had a CACS≥100. Patients with CACS≥100 were older (63 ± 7 vs 54 ± 12 years, p<0.001), had higher prevalence of hypertension (68% vs 43%, p<0.001) and diabetes mellitus (21% vs 10%, p=0.012) and higher left atrial volume (39 ± 9 vs 35 ± 9 ml/m2, p=0.018). After a median observation time of 34 months (IQR 24-43), 117 patients (33%) had AF recurrence.

CACS≥100 was associated with increased risk of AF recurrence (unadjusted Cox regression: hazard ratio [HR] 1.85; 95% confidence interval [CI], 1.23-2.79, p=0.003) (Fig. 1). After covariate adjustment (age, gender, hypertension, diabetes mellitus, obesity, thyroid disease, AF type and left atria enlargement) CACS≥100 remained an independent predictor of the risk of AF recurrence (HR, 1.68; 95% CI, 1.05-2.70, p=0.03) as well as persistent AF (HR, 1.91; 95% CI, 1.23-3.00, p=0.004) (Fig. 2).

Conclusion

In patients with AF undergoing catheter ablation, without previous history of CAD, a CACS≥100 was independently associated with a 68% increase in the risk of AF recurrence.

Association of epicardial adipose tissue and coronary artery calcium score in patients with atrial fibrillation

Funding Acknowledgements

Type of funding sources: None.

Introduction

Both coronary artery calcium (CAC) and epicardial adipose tissue (EAT) had been implicated in coronary artery disease (CAD) and risk of future adverse cardiovascular events. There are scarce data regarding the assessment and association of EAT volume and CAC score (CACS) in atrial fibrillation (AF) patients.

Purpose

To assess the association between EAT volume and the presence and severity of CAC in patients with AF.

Methods

Retrospective and single-centre study including consecutive patients with AF undergoing contrast-enhanced cardiac computed tomography for catheter ablation planning, from 2017 to 2019. Patients with known history of CAD and moderate to severe valvular heart disease were excluded. Baseline clinical and demographical data were collected, as well as their cardiovascular risk, based on the SCORE (Systematic Coronary Risk Evaluation) system and cardiovascular risk categories. We assessed CACS (Agatston method) and EAT volume and analysed their association. EAT was defined as the adipose tissue accumulated between the visceral pericardium and the myocardium and was semi-automatically reconstructed by manually tracing the pericardium. Patients were split into three groups according to CACS: 0, 1-99 and ≥100. A logistic regression (LR) analysis was performed to explore the relationship between EAT volume and the presence of CAC (CACS>0), adjusted for age, gender, obesity, diabetes mellitus and hypertension.

Results

A total of 354 patients were included, with a mean age of 56 ± 12 years, 66% male and 21% with persistent AF. A CHA2DS2-VASc score ≥2 was present in 130 (37%) patients and most patients had low to moderate cardiovascular risk (n=213, 82%). More than half of the patients had a CACS>0 (n=185, 52%), of which 63 patients (18%) had a CACS≥100. The mean EAT volume was 79 ± 39 ml. There was a significant association between EAT volume and the presence of CAC: CACS=0 69 ± 34 ml vs CACS 1-99 84 ± 38 ml vs CACS ≥100 95 ± 45 ml (p<0.001) (Fig. 1). After covariate adjustment (LR model R2 = 0.373, p <0.0001), the presence of CAC was not associated with EAT volume (OR 1.00, 95%CI 1.00 - 1.01, p=0.2) or obesity, and only with higher age, male gender, hypertension and diabetes mellitus (Fig. 2).

Conclusion

In our cohort of patients with AF undergoing catheter ablation we observed an association between EAT and CACS. Nevertheless, EAT volume was not an independent predictor of CACS and only the classical cardiovascular risk factors remained significant.

Coronary calcification by computed tomography in patients with paroxysmal and persistent atrial fibrillation undergoing catheter ablation

Introduction

Cardiac computed tomography (CCT) is routinely performed for pulmonary vein isolation (PVI) planning in patients with paroxysmal or persistent atrial fibrillation (AF). This imaging method can also identify coronary artery calcium (CAC).

Purpose

To evaluate the prevalence of CAC in patients with paroxysmal and persistent AF undergoing catheter ablation.

Methods

Cross-sectional study including patients with AF/atrial flutter (AFL) undergoing CCT for ablation procedure planning from 2017 to 2019. Baseline clinical and demographic data were collected and CAC score was assessed using the Agatston method. Patients with paroxysmal and persistent AF/AFL (defined according to 2020 European Society of Cardiology guidelines for the diagnosis and management of AF) were compared.

Results

A total of 474 patients were included (441 with AF and 33 with AFL), with a mean age of 57±12 years, of which 295 (62%) were males. CHA2DS2-VASc score was ≥1 (male) or ≥2 (female) in 278 (64%) patients and most patients had a low to moderate cardiovascular risk (259, 80%). CAC was identified in 254 (54%) patients. AF/AFL was paroxysmal in 348 (75%) patients and persistent in 116 (25%). Baseline characteristics and cardiovascular risk factors were similar between groups except for diabetes mellitus (33 [10%] vs 22 [20%], p=0.012) and valvular heart disease (13 [4%] vs 18 [16%], p<0.001) that were more prevalent in patients with persistent AF/AFL. Patients with persistent AF/AFL had higher left atrial volume and left ventricle mass (36±8 vs 43±12 ml/m2, p<0.001 and 90±22 vs 96±22 g/m2, p=0.041). CAC was more frequently present in patients with persistent AF/AFL (175 [50%] vs 72 [62%], p=0.028), especially CAC score >100 (58 [17%] vs 35 [30%], p=0.002). After multivariate analysis, CAC score>100 remained an independent predictor of persistent AF/AFL (OR 2.12, 95% CI 1.18–3.82, p=0.013) along with higher left atrial volume (OR 1.06, 95% CI 1.03–1.08, p<0.001).

Conclusion

In this study, coronary artery calcium was present in more than half of AF/FLA patients undergoing catheter ablation. Patients with persistent AF/AFL showed higher calcium scores and this could derive from chronic, more advanced disease. Especially in those patients, opportunistic CV risk screening and CAC-guided clinical management might be clinically useful.

Funding Acknowledgement

Type of funding sources: None.

Coronary artery calcium in patients with atrial fibrillation undergoing catheter ablation – an opportunity to personalize cardiovascular and thromboembolic risk management

Introduction

There is a well-established association between atrial fibrillation (AF) and coronary artery disease (CAD). Coronary artery calcium score (CACS) is a helpful tool to refine cardiovascular risk stratification and guide strategies of cardiovascular (CV) primary prevention.

Purpose

To evaluate the prevalence and clinical implications of CACS in terms of CV and thromboembolic risk stratification and preventive therapies, in patients with AF and atrial flutter (AFL) undergoing catheter ablation.

Methods

Cross-sectional study including patients with AF/AFL undergoing multidetector computed tomography (MDCT) for ablation procedure planning from 2017 to 2019. Baseline clinical and demographical data were collected. CV and thromboembolic risks were evaluated based on the SCORE (Systematic Coronary Risk Evaluation) system and CHA2DS2-VASc score. CACS was assessed in patients without history of coronary artery disease using the Agatston method.

Results

A total of 474 patients were included (441 with AF and 33 with AFL, mean age of 58±10 years, 62% male). Excluding those over 70 years of age (n=50, 11%), most patients had low (n=69, 22%) or moderate (n=188, 60%) CV risk and 277 (64%) patients had a CHA2DS2-VASc score ≥1 (male) or ≥2 (female). Overall, 265 patients (65%) were under chronic anticoagulation and 157 (39%) were under statin therapy. CAC was present in 254 (54%) patients and showed a multivessel distribution in 62% of the cases. The left main stem was affected in 81 (17%) patients and the left anterior descending artery in 211 (45%). Incorporating CACS>100 as a variable in CHA2DS2-VASc score (vascular disease parameter in patients without history of vascular disease) would have resulted in a significant score reclassification (n=87, 20%) and identification of new potential candidates for anticoagulation (n=12, 3%). Additional, anticoagulation would be indicated as a class IA recommendation in more 26 (6%) patients. Twenty three percent of patients with zero calcium were taking statins, and only 7% of patients with a CACS >300 were on high-intensity statin therapy. According to the recommendations and based on their CACS and current therapy, 103 (25%) patients would be candidates for statin therapy and 69 (17%) patients would be candidates for changes in the current statin therapy intensity (Table 1).

Conclusion

In our study, more than half of the patients undergoing MDCT before AF/AFL catheter ablation had coronary calcium above zero. Our findings suggest that an opportunistic evaluation of CACS can be clinically valuable in thromboembolic risk stratification and management of preventive pharmacological strategies such as anticoagulation and statins.

Funding Acknowledgement

Type of funding sources: None.

Speciation in marine environments: Diving under the surface

Marine environments are inhabited by a broad representation of the tree of life, yet our understanding of speciation in marine ecosystems is extremely limited compared with terrestrial and freshwater environments. Developing a more comprehensive picture of speciation in marine environments requires that we 'dive under the surface' by studying a wider range of taxa and ecosystems is necessary for a more comprehensive picture of speciation. Although studying marine evolutionary processes is often challenging, recent technological advances in different fields, from maritime engineering to genomics, are making it increasingly possible to study speciation of marine life forms across diverse ecosystems and taxa. Motivated by recent research in the field, including the 14 contributions in this issue, we highlight and discuss six axes of research that we think will deepen our understanding of speciation in the marine realm: (a) study a broader range of marine environments and organisms; (b) identify the reproductive barriers driving speciation between marine taxa; (c) understand the role of different genomic architectures underlying reproductive isolation; (d) infer the evolutionary history of divergence using model-based approaches; (e) study patterns of hybridization and introgression between marine taxa; and (f) implement highly interdisciplinary, collaborative research programmes. In outlining these goals, we hope to inspire researchers to continue filling this critical knowledge gap surrounding the origins of marine biodiversity.

Using replicate hybrid zones to understand the genomic basis of adaptive divergence

Combining hybrid zone analysis with genomic data is a promising approach to understanding the genomic basis of adaptive divergence. It allows for the identification of genomic regions underlying barriers to gene flow. It also provides insights into spatial patterns of allele frequency change, informing about the interplay between environmental factors, dispersal and selection. However, when only a single hybrid zone is analysed, it is difficult to separate patterns generated by selection from those resulting from chance. Therefore, it is beneficial to look for repeatable patterns across replicate hybrid zones in the same system. We applied this approach to the marine snail Littorina saxatilis, which contains two ecotypes, adapted to wave-exposed rocks vs. high-predation boulder fields. The existence of numerous hybrid zones between ecotypes offered the opportunity to test for the repeatability of genomic architectures and spatial patterns of divergence. We sampled and phenotyped snails from seven replicate hybrid zones on the Swedish west coast and genotyped them for thousands of single nucleotide polymorphisms. Shell shape and size showed parallel clines across all zones. Many genomic regions showing steep clines and/or high differentiation were shared among hybrid zones, consistent with a common evolutionary history and extensive gene flow between zones, and supporting the importance of these regions for divergence. In particular, we found that several large putative inversions contribute to divergence in all locations. Additionally, we found evidence for consistent displacement of clines from the boulder-rock transition. Our results demonstrate patterns of spatial variation that would not be accessible without continuous spatial sampling, a large genomic data set and replicate hybrid zones.

Accelerated Evolution of Tissue-Specific Genes Mediates Divergence Amidst Gene Flow in European Green Lizards

The European green lizards of the Lacerta viridis complex consist of two closely related species, L. viridis and Lacerta bilineata that split less than 7 million years ago in the presence of gene flow. Recently, a third lineage, referred to as the “Adriatic” was described within the L. viridis complex distributed from Slovenia to Greece. However, whether gene flow between the Adriatic lineage and L. viridis or L. bilineata has occurred and the evolutionary processes involved in their diversification are currently unknown. We hypothesized that divergence occurred in the presence of gene flow between multiple lineages and involved tissue-specific gene evolution. In this study, we sequenced the whole genome of an individual of the Adriatic lineage and tested for the presence of gene flow amongst L. viridis, L. bilineata, and Adriatic. Additionally, we sequenced transcriptomes from multiple tissues to understand tissue-specific effects. The species tree supports that the Adriatic lineage is a sister taxon to L. bilineata. We detected gene flow between the Adriatic lineage and L. viridis suggesting that the evolutionary history of the L. viridis complex is likely shaped by gene flow. Interestingly, we observed topological differences between the autosomal and Z-chromosome phylogenies with a few fast evolving genes on the Z-chromosome. Genes highly expressed in the ovaries and strongly co-expressed in the brain experienced accelerated evolution presumably contributing to establishing reproductive isolation in the L. viridis complex.

Genetic variation for adaptive traits is associated with polymorphic inversions in Littorina saxatilis

Chromosomal inversions have long been recognized for their role in local adaptation. By suppressing recombination in heterozygous individuals, they can maintain coadapted gene complexes and protect them from homogenizing effects of gene flow. However, to fully understand their importance for local adaptation we need to know their influence on phenotypes under divergent selection. For this, the marine snail Littorina saxatilis provides an ideal study system. Divergent ecotypes adapted to wave action and crab predation occur in close proximity on intertidal shores with gene flow between them. Here, we used F2 individuals obtained from crosses between the ecotypes to test for associations between genomic regions and traits distinguishing the Crab‐/Wave‐adapted ecotypes including size, shape, shell thickness, and behavior. We show that most of these traits are influenced by two previously detected inversion regions that are divergent between ecotypes. We thus gain a better understanding of one important underlying mechanism responsible for the rapid and repeated formation of ecotypes: divergent selection acting on inversions. We also found that some inversions contributed to more than one trait suggesting that they may contain several loci involved in adaptation, consistent with the hypothesis that suppression of recombination within inversions facilitates differentiation in the presence of gene flow.

Inversions and genomic differentiation after secondary contact: When drift contributes to maintenance, not loss, of differentiation

Due to their effects on reducing recombination, chromosomal inversions may play an important role in speciation by establishing and/or maintaining linked blocks of genes causing reproductive isolation (RI) between populations. This view fits empirical data indicating that inversions typically harbor loci involved in RI. However, previous computer simulations of infinite populations with two to four loci involved in RI implied that, even with gene flux as low as 10^-8 per gamete, per generation between alternative arrangements, inversions may not have large, qualitative advantages over collinear regions in maintaining population differentiation after secondary contact. Here, we report that finite population sizes can help counteract the homogenizing consequences of gene flux, especially when several fitness-related loci reside within the inversion. In these cases, the persistence time of differentiation after secondary contact can be similar to when gene flux is absent and notably longer than the persistence time without inversions. Thus, despite gene flux, population differentiation may be maintained for up to 100,000 generations, during which time new incompatibilities and/or local adaptations might accumulate and facilitate progress toward speciation. How often these conditions are met in nature remains to be determined.

Psychiatric manifestations of anti-NMDAR encephalitis

Introduction

Anti-N-methyl-D-aspartate receptor (NMDAR) encephalitis is an autoimmune disorder characterized by neuropsychiatric symptoms before progressing to seizures, complex movement disorder, autonomic dysfunction and hypoventilation.

Objectives

Presenting a review of the psychiatric manifestations of anti-NMDAR encephalitis.

Methods

Search on Pubmed® and Medscape® databases with the following keywords: “psychiatric”, “anti-NMDA receptor encephalitis” and “anti-NMDAR encephalitis”. We focused on data from systematic reviews and meta-analyzes. The articles were selected by the authors according to their relevance.

Results

Studies show that 77% to 95% of patients with anti-NMDAR encephalitis initially present psychiatric manifestations. Age and sex distribution are young women, and the frequency of cases is lower after 40 years of age. The most common psychiatric symptoms are agitation (59%) and psychotic symptoms (54%). The psychotic symptoms more common are visual (64%), auditory (59%) hallucinations and persecutory delusions (73%). Catatonia is described in 42% of patients. Antipsychotic treatment induces an adverse drug reaction (33%), the neuroleptic malignant syndrome represents 22% of the cases. Delays in distinguishing this disease from a psychiatric disorder can have serious complications, with a mortality of up to 25% in patients receiving limited or delayed immunotherapy.

Conclusions

It’s important to consider anti-NMDAR encephalitis in the differential diagnosis of patients with an acute onset psychosis or unusual psychiatric symptoms. Antipsychotic treatment should be use with caution when suspected or confirmed anti-NMDAR encephalitis. Without appropriate treatment, patients may suffer a protracted course with significant long-term disability or death. A clinical index of suspicion is required to identify patients who would benefit from cerebrospinal fluid testing and immunotherapies.

Disclosure

No significant relationships.

Impulse control disorders and dopamine agonists

Introduction

Impulse control disorders (ICDs) are an adverse effect of dopamine agonists (DAAs) that affects the quality of life and can lead to legal, criminal and familiar problems.

Objectives

Presenting a review of the mechanisms, prevalence and factors associated with the development of an ICD due to DAA use.

Methods

Search on Pubmed database with combination of the following keywords were used: “Impulse control disorders”, “dopamine agonist” or “therapy”. We focused on data from studies published between 2015 and 2020. The articles were selected by the author according to their relevance.

Results

DAAs are mainly indicated in the treatment of Parkinson’s Disease (PD), and are also used on symptoms of restless legs syndrome (RLS) and prolactinoma or lactation inhibition. Dopamine replacement therapy act on dopamine receptors in the nigrostriatal and the reward pathways, which plays a role in addictive behavior. The prevalence of ICDs ranged from 2.6 to 34.8% in PD patients and a lower prevalence in RLS patients. Some of the ICDs reported were pathological gambling, hypersexuality, compulsive shopping, obsessive hobbying, punding, and compulsive medication use. The factors associated with the development include the type of DAAs, dosage, male gender, younger age, history of psychiatric symptoms, earlier onset of disease, longer disease duration, and motor complications in PD.

Conclusions

Further studies are needed to clarify the pathophysiology of the ICD in DAA therapy and determinate premorbid risk factors. The percentage of patients with ICDs is underrated, so it’s important to improve the patient’s evaluation, using validated and consensual assessment tools.

Phenocopy syndrome of frontotemporal dementia

Introduction

Frontotemporal dementia (FTD) is a group of neurodegenerative disorders characterized by behavioral or language changes with progressive executive dysfunction. It´s subdivided into two variants, the behavioral and language variants. The phenocopy syndrome of frontotemporal dementia (phFTD) mimics the behavioral variant, but doesn´t show frontotemporal atrophy in neuroimaging and doesn´t progress to frank dementia over the years.

Objectives

Presenting a review of phenocopy syndrome of frontotemporal dementia.

Methods

Search on Pubmed® and Medscape® databases with the following keywords: “frontotemporal dementia and phenocopy” or “FTD phenocopy”. We focused on data from systematic reviews and meta-analyzes published in the last five years. The articles were selected by the authors according to their relevance.

Results

Mutations in GRN and MAPT gens and genetic expansion of C9orf72 have been identified. The discovery of the C9orf72 expansion in psychiatric disorders (psychosis, bipolar disorder or depressive disorder), for some authors, represents that phFTD is a psychiatric pathology. In fact, there’s a higher frequency of psychiatric and psychological symptoms in phFTD compared to the variants of FTD. Usually are male patients who don´t have significant cognitive deficits, with preservation of executive functions and episodic memory. Until now, there are no definitive biomarkers of the disease. The prognosis is more benigne, unlike FTD, which has an average survival of 3 years since diagnosis.

Conclusions

phFTD is a clinical and scientific challenge. The neurobiological bases remain unknown, requiring further studies in this field. The identification of markers that can differentiate patients with typical FTD and phFTD can facilitate prognosis orientation and pharmacological an non-pharmacological treatment.

Is coronary computed tomography angiography a good choice for elders and high probability cases?

Introduction

Coronary computed tomography angiography (cCTA) is widely considered the optimal non-invasive test to rule out coronary artery disease (CAD) and the gatekeeper for invasive coronary angiography (ICA). However, its diagnostic utility in elderly patients (pts) and in cases of high pre-test probability (PTP) is still questioned.

Aim

To determine whether older age and high PTP are correlated with non-diagnostic cCTA scans in pts with suspected chronic coronary syndrome (CCS).

Methods

Single-centre retrospective study of 302 pts with suspected CAD assigned to two groups: (A) 207 pts aged ≥70 years (y); (B) 95 aged <70y. Younger pts were randomly selected from our database. We excluded pts with known history of CAD and suspected acute coronary syndrome. A 192x2 dual-source CT equipment was used. Baseline demographic and clinical characteristics were collected as well as scan features and findings. We defined high PTP according to clinical Morise score. Our endpoint was the obtention of diagnostic scan (all segments evaluable). Multivariate analysis was performed to assess the determinants of non-diagnostic scans. We used SPSS Statistics 22 for statistical analysis.

Results

Overall, mean age was 68±9y and 53% were male. Elderly pts presented more co-morbidities (hypertension: 78.3 vs 54.7%, p<0.01; hyperlipidaemia: 69.1 vs 52.6%, p<0.01; pulmonary disease: 13.0 vs 4.2%, p=0.02) and high PTP more frequently (16.9 vs 6.3%, p<0.01). Total coronary calcium score (CaS) was higher in elderly pts (382.7±658.7 vs 243.5±490.8, p=0.04); per-vessel, both left anterior descending (156.7±254.2 vs 92.2±187.8, p=0.01) and left circumflex (LCX) arteries (65.5±131.3 vs 26.8±67.6, p<0.01) showed higher CaS in the elderly. Multiple calcified plaques (≥5) were also more common in this group (60.4 vs 45.3%, p=0.01). However, the proportion of pts with CaS considered prohibitive for angiography (13.5 vs 7.4%; p=0.12) and calcium blooming artefacts impairing interpretation (14.5 vs 12.5%; p=0.65) did not differ. A diagnostic study was more frequently obtained in younger pts but without reaching statistical significance (69.1 vs 76.8%; p=0.17). Obstructive CAD was equally identified (30.3 vs 30.4%; p=0.92) with a respective per-patient accuracy of 68.4% (13/19) and 57.1% (8/14) comparing with ICA when performed. Multivariate analysis showed that LCX CaS ≥75th percentile and multiple calcified plaques (≥5) were associated with non-diagnostic cCTA scan (Figure 1). High PTP (p=0.83) and age ≥70y (p=0.61) were not associated with the endpoint.

Conclusion

In this comparison study of elderly and young pts undergoing cCTA for suspected CCS, age ≥70y and high PTP were not associated with non-diagnostic tests while multiple calcified lesions and severe LCX calcification predicted inconclusive studies. Our results cast hope on the applicability of cCTA to elderly pts and cases with high PTP, although larger studies are required.

Funding Acknowledgement

Type of funding source: None

Genetic and morphological divergence between Littorina fabalis ecotypes in Northern Europe

Low dispersal marine intertidal species facing strong divergent selective pressures associated with steep environmental gradients have a great potential to inform us about local adaptation and reproductive isolation. Among these, gastropods of the genus Littorina offer a unique system to study parallel phenotypic divergence resulting from adaptation to different habitats related with wave exposure. In this study, we focused on two Littorina fabalis ecotypes from Northern European shores and compared patterns of habitat-related phenotypic and genetic divergence across three different geographic levels (local, regional and global). Geometric morphometric analyses revealed that individuals from habitats moderately exposed to waves usually present a larger shell size with a wider aperture than those from sheltered habitats. The phenotypic clustering of L. fabalis by habitat across most locations (mainly in terms of shell size) support an important role of ecology in morphological divergence. A genome scan based on amplified fragment length polymorphisms (AFLPs) revealed a heterogeneous pattern of differentiation across the genome between populations from the two different habitats, suggesting ecotype divergence in the presence of gene flow. The contrasting patterns of genetic structure between nonoutlier and outlier loci, and the decreased sharing of outlier loci with geographic distance among locations are compatible with parallel evolution of phenotypic divergence, with an important contribution of gene flow and/or ancestral variation. In the future, model-based inference studies based on sequence data across the entire genome will help unravelling these evolutionary hypotheses, improving our knowledge about adaptation and its influence on diversification within the marine realm.

Predictors of Fabry disease in patients with hypertrophic cardiomyopathy: How to guide the diagnostic strategy?

BACKGROUND

Fabry disease (FD) is a treatable cause of hypertrophic cardiomyopathy (HCM). We aimed to determine the independent predictors of FD and to define a clinically useful strategy to discriminate FD among HCM.

METHODS

Multicenter study including 780 patients with the ESC definition of HCM. FD screening was performed by enzymatic assay in males and genetic testing in females. Multivariate regression analysis identified independent predictors of FD in HCM. A discriminant function analysis defined a score based on the weighted combination of these predictors.

RESULTS

FD was found in 37 of 780 patients with HCM (4.7%): 31 with p.F113L mutation due to a founder effect; and 6 with other variants (p.C94S; p.M96V; p.G183V; p.E203X; p.M290I; p.R356Q/p.G360R). FD prevalence in HCM adjusted for the founder effect was 0.9%. Symmetric HCM (OR 3.464, CI95% 1.151-10.430), basal inferolateral late gadolinium enhancement (LGE) (OR 10.677, CI95% 3.633-31.380), bifascicular block (OR 10.909, CI95% 2.377-50.059) and ST-segment depression (OR 4.401, CI95% 1.431-13.533) were independent predictors of FD in HCM. The score ID FABRY-HCM [-0.729 + (2.781xBifascicular block) + (0.590xST depression) + (0.831xSymmetric HCM) + (2.130xbasal inferolateral LGE)] had a negative predictive value of 95.8% for FD, with a cut-off of 1.0, meaning that, in the absence of both bifascicular block and basal inferolateral LGE, FD is a less probable cause of HCM, being more appropriate to perform HCM gene panel than targeted FD screening.

CONCLUSION

FD prevalence in HCM was 0.9%. Bifascicular block and basal inferolateral LGE were the most powerful predictors of FD in HCM. In their absence, HCM gene panel is the most appropriate step in etiological study of HCM.

AB0406 HUMAN PAPILLOMA VIRUS (HPV) VACCINATION SAFETY IN SYSTEMIC LUPUS ERYTHEMATOSUS COHORT - PORTUGUESE UNIVERSITY HOSPITAL SINGLE-CENTER COHORT STUDY

Background:

Cervical cancer is a potentially preventable consequence of Human Papillomavirus (HPV). HPV vaccination is recommended in most countries for all young women, preferentially before sexual activity begins. In Portugal, HPV vaccination is available in either bivalent (genotypes 6, 18) or tetravalent (6, 11, 16 e 18) vaccines. Both have aluminum as an adjuvant, a substance arguably capable of inducing inflammatory adjuvant syndromes. Systemic Lupus Erythematosus (SLE) mostly afflicts women of childbearing age, the very target population for HPV vaccination. There are conflicting reports in the literature regarding both the efficacy and safety of this vaccine in SLE patients. This question is particularly pressing as HPV infection prevalence seems to be increased in SLE patients.

Objectives:

To analyze the safety of HPV vaccination in a SLE patient cohort followed at a university hospital.

Methods:

Retrospective single-center (35 year long, 436 SLE patient cohort) review of all female SLE patients’ local and online national records on HPV vaccination and cervical cancer screening. Data on activity (using SLEDAI-2K scoring) and concomitant drug use were reviewed for the two years before and after vaccination date.

Results:

Of the 463 SLE patients, 420 were women (91%), of which 322 had clinical information about yes/no HPV vaccination. Twenty-seven of the patients (8%) had one of HPV vaccines, but only 13 (4%) had full information on activity before and after vaccination. Mean current age was 33,8 years and a minimum of 8,4 years of follow-up after HPV vaccination. Twenty-there (85%) were vaccinated with the tetravalent vaccine. Pre-vaccination mean SLEDAI score of was 5.9: due to arthritis (n= 5; 38,5%), low complement (n=4; 31%), dsDNA (n=4; 31%); with a medium dose of 10mg prednisolone/day and 265mg/day of hydroxychloroquine. Post-vaccination mean SLEDAI was 5.8: due to arthritis (n=6; 46%), rash (n= 5; 38,5%) and low complement (n=6; 46%); with a medium dose of 8mg prednisolone/day and 288mg/day of hydroxychloroquine. There was not a difference in organ involvement before and after vaccination, but rash was slightly more prevalent after vaccination.

Conclusion:

In our population, HPV vaccination didn’t significantly change disease activity and organ involvement or mean dose need of prednisolone or hydroxychloroquine. Although it is a small size SLE sample, it suggests that is safe to administer HPV vaccination to SLE patients.

References:

[1]eularSegal Yahel, Zabludowicz Center for Autoimmune Diseases, Tel Aviv (2017), “HPV and systemic lupus erythematosus: a mosai of potential crossreaction”, SLE Research and Clinical Update, 23 January 2017

[2]Geier David Institute of Chronic Illnesses, USA, (2016), “Quadrivalent human pappilomavirus vaccine and autoimmune adverse events: a case-control assessment of the vaccine adverse event reporting system (VAERS) database, Environment and Autoimmunity, 13 July 2016

Disclosure of Interests: :

None declared

AB1026 INFLAMMATORY MANIFESTATIONS IN PATIENTS WITH HUMAN LEUKOCYTE ANTIGEN-B*51 POSITIVE AND WITHOUT BEHÇET’S DISEASE

Background:

Human leukocyte antigen (HLA) B*51 allele is the most important genetic factor in susceptibility to Behçet’s disease (BD), an immune-mediated systemic disorder of unknown etiology, characterized by recurrent episodes of inflammatory manifestations. In fact there is a considerable clinical overlap of BD with autoinflammatory syndromes. As it’s known, the majority of HLA-B*51 positive individuals do not develop BD. But do these individuals also present inflammatory manifestations?

Objectives:

Characterize the group of individuals in our hospital with positive HLA-B*51, without BD diagnosis and review whether inflammatory manifestations are present in these individuals.

Methods:

A retrospective study of HLA-B*51 positive patients between 2000 and 2019. Genomic DNA was obtained from peripheral blood and HLA genotyping was performed using a PCR with Sequence Specific Primers (PCR–SSP) methodology. From the group of 289 B*51 positive patients, BD diagnosis were excluded. Demographic and clinical data were collected by review of clinical files in December 2019.

Results:

176 patients, mean age of 48.5 ± 16.5 years (5 to 84 years). Most were female (68%). The HLA study was motivated by multiple diagnostic suspicions: spondyloarthritis (SpA, 25.0%), BD (22.7%) and systemic sclerosis (SSc, 10.8%). The mean time elapsed since the immunogenetic study was 8.3 years, with 12 deaths recorded. 69 (39.2%) subjects had no diagnosis for immune-mediated disease (IMD). Of the other 107 patients, the majority had 1 IMD (64.5%), and the rest were diagnosed with 2 to 4 IMD. The most frequent IMD were SpA (20.8%), psoriasis (10.4%), psoriatic arthritis (9.7%), SSc (9.7%) and rheumatoid arthritis (7.1%). Autoantibodies were detected in 94 individuals (53.4%): antinuclear antibodies (64 patients), rheumatoid factor (26 patients) and CCP antibodies (11 patients). In 55 individuals no inflammatory manifestation was identified but the 68.8% of them presented between 1 to 7 manifestations:

System involvedClinical manifestationFrequencyEars, nose and throatChronic rhinitis32 (13.2%)∑ = 76 (31.4%)Recurrent tonsillitis20 (8.3%)Other24 (9.9%)Cutaneous, mucous and serousRecurrent oral aphtous ulcers34 (14.0%)∑ = 57 (23.6%)Serositis10 (4.1%)Other13 (5.4%)NeurologicalChronic headache34 (14.0%)∑ = 36 (14.9%)Asseptic meningitis2 (0.8%)OcularOcular inflammation31 (12.8%)∑ = 31 (12.8%)UrinaryRecurrent cystitis15 (6.2%)∑ = 15 (6.2%)VascularVenous thromboembolism7 (2.9%)∑ = 14 (5.8%)Aneurysm6 (2.5%)Spontaneous coronary dissection1 (0.4%)RheumaticArthromyalgia6 (2.5%)∑ = 9 (3.7%)Gout3 (1.2%)ConstitutionalRecurrent fever syndrome1 (0.4%)∑ = 1 (0.4%)DigestiveRecurrent abdominal pain1 (0.4%)∑ = 1 (0.4%)LymphaticAxillary and inguinal adenopathies1 (0.4%)∑ = 1 (0.4%)PulmonaryChronic pulmonary infiltrate1 (0.4%)∑ = 1 (0.4%)

Conclusion:

Inflammatory manifestations are common in HLA-B*51 positive individuals, even in those without BD diagnosis. Further research is needed, considering other HLA alleles associated with increased risk of BD and including control groups.

References:

[1]Burillo-Sanz S, Montes-Cano M, García-Lozano J,et al. Behçet´s disease and genetic interactions between HLA-B*51 and variants in genes of autoinflammatory syndromes.Sci Rep2019;9:2777.

[2]McGonagle D, McDermott MF. A Proposed Classification on the Immunological Diseases.PLoS Med2006;3(8):e297.

[3]Tong B, Liu X, Xiao J, Su G. Immunopathogenesis of Behcet´s Disease.Front. Immunol2019;10:665.

Disclosure of Interests:

None declared

AB0407 HUMAN PAPILLOMA VIRUS (HPV) INFECTION AND CERVICAL CANCER PREVALENCE IN A PORTUGUESE UNIVERSITY HOSPITAL SINGLE-CENTER SYSTEMIC LUPUS ERYTHEMATOSUS COHORT

Background:

About 12% of women worldwide are infected with Human Papillomavirus (HPV), the most frequent cause of cervical cancer (CC) - very prevalent (~ 7,5%) and preventable. National screening efforts are in use in several countries, including Portugal. Patients with Systemic Lupus Erythematosus (SLE) are at increased risk of HPV infection and CC when compared to the healthy population.

Objectives:

To evaluate the prevalence of HPV infection and rate of incidence of cervical neoplastic lesions in a SLE patient cohort followed at a university hospital.

Methods:

Retrospective single-center (35 year long, 463 SLE patient cohort) review of all female SLE patients’ local and online national health care records on HPV vaccination and CC screening.

Results:

Of the 463 SLE patients, 420 were women (91%), of which 322 had records on of HPV infection or CC developed. Mean patients’ current age was 48 years and all had screening for cervical pathology in the last 3 years. Thirty-three patients (11%) had HPV infection diagnosed at a mean age of 44 years. Twenty-seven (8%) of SLE patients were vaccinated for HPV: 8 (22%) of the infected patients had the vaccine, half after the HPV infection. Despite HPV infection, 49 patients (15%) had developed some cervical lesion, of which 41 (84% of cervical lesion) were suggestive of malignancy, and ultimately CC was diagnosed in 20 women (41%; 6% of total women), with a mean age at diagnosis of 45 years. All CC patients had history of HPV infection, but only 3 women (15%; 0,9% of total women) had been vaccinated against HPV, 2 after the diagnoses of CC and 1 before.

Conclusion:

In our population the prevalence of HPV was higher than reported for the general population using the World Health Organization database, conforming the higher risk of HPV infection in SLE patients. The prevalence of cervical cancer, however, was similar to the healthy population.

References:

[1]https://www.who.int/immunization/diseases/hpv/en/

[2]Forman David (2012); “Global Burden of Human Papillomavirus and Related Diseases”, Vaccine, Elsevier Volume 30, Supplement 5, 20 November 2012

[3]Grein Ingrid (2016), Department of Pediatric Immunology and Rheumatology, Netherland (2016), HPV infection and vaccination in Systemic Lupus Erythematosus patients: what we really should know, Pediatric Rheumatology, 2016

Disclosure of Interests: :

None declared

Transcriptomic resources for evolutionary studies in flat periwinkles and related species

The flat periwinkles, Littorina fabalis and L. obtusata, comprise two sister gastropod species that have an enormous potential to elucidate the mechanisms involved in ecological speciation in the marine realm. However, the molecular resources currently available for these species are still scarce. In order to circumvent this limitation, we used RNA-seq data to characterize the transcriptome of four individuals from each species sampled in different locations across the Iberian Peninsula. Four de novo transcriptome assemblies were generated, as well as a pseudo-reference using the L. saxatilis reference transcriptome as backbone. After transcripts' annotation, variant calling resulted in the identification of 19,072 to 45,340 putatively species-diagnostic SNPs. The discriminatory power of a subset of these SNPs was validated by implementing an independent genotyping assay to characterize reference populations, resulting in an accurate classification of individuals into each species and in the identification of hybrids between the two. These data comprise valuable genomic resources for a wide range of evolutionary and conservation studies in flat periwinkles and related taxa.

Evolutionary history of two cryptic species of northern African jerboas

BACKGROUND

Climatic variation and geologic change both play significant roles in shaping species distributions, thus affecting their evolutionary history. In Sahara-Sahel, climatic oscillations shifted the desert extent during the Pliocene-Pleistocene interval, triggering the diversification of several species. Here, we investigated how these biogeographical and ecological events have shaped patterns of genetic diversity and divergence in African Jerboas, desert specialist rodents. We focused on two sister and cryptic species, Jaculus jaculus and J. hirtipes, where we (1) evaluated their genetic differentiation, (2) reconstructed their evolutionary and demographic history; (3) tested the level of gene flow between them, and (4) assessed their ecological niche divergence.

RESULTS

The analyses based on 231 individuals sampled throughout North Africa, 8 sequence fragments (one mitochondrial and seven single copy nuclear DNA, including two candidate genes for fur coloration: MC1R and Agouti), 6 microsatellite markers and ecological modelling revealed: (1) two distinct genetic lineages with overlapping distributions, in agreement with their classification as different species, J. jaculus and J. hirtipes, with (2) low levels of gene flow and strong species divergence, (3) high haplotypic diversity without evident geographic structure within species, and (4) a low level of large-scale ecological divergence between the two taxa, suggesting species micro-habitat specialization.

CONCLUSIONS

Overall, our results suggest a speciation event that occurred during the Pliocene-Pleistocene transition. The contemporary distribution of genetic variation suggests ongoing population expansions. Despite the largely overlapping distributions at a macrogeographic scale, our genetic results suggest that the two species remain reproductively isolated, as only negligible levels of gene flow were observed. The overlapping ecological preferences at a macro-geographic scale and the ecological divergence at the micro-habitat scale suggest that local adaptation may have played a crucial role in the speciation process of these species.

Phylogeographic history of flat periwinkles, Littorina fabalis and L. obtusata

Background

The flat periwinkles, Littorina fabalis and L. obtusata, are two sister species widely distributed throughout the Northern Atlantic shores with high potential to inform us about the process of ecological speciation in the intertidal. However, whether gene flow has occurred during their divergence is still a matter of debate. A comprehensive assessment of the genetic diversity of these species is also lacking and their main glacial refugia and dispersal barriers remain largely unknown. In order to fill these gaps, we sequenced two mitochondrial genes and two nuclear fragments to perform a phylogeographic analysis of flat periwinkles across their distribution range.

Results

We identified two main clades largely composed by species-specific haplotypes corresponding to L. obtusata and L. fabalis, with moderate to strong support, respectively. Importantly, a model of divergence with gene flow between the two species (from L. obtusata to L. fabalis) was better supported, both in Iberia and in northern-central Europe. Three mitochondrial clades were detected within L. fabalis and two within L. obtusata, with strong divergence between Iberia and the remaining populations. The largest component of the genetic variance within each species was explained by differences between geographic regions associated with these clades. Our data suggests that overall intraspecific genetic diversity is similar between the two flat periwinkle species and that populations from Iberia tend to be less diverse than populations from northern-central Europe.

Conclusions

The phylogeographic analysis of this sister-species pair supports divergence with gene flow. This system thus provides us with the opportunity to study the contribution of gene flow and natural selection during diversification. The distribution of the different clades suggests the existence of glacial refugia in Iberia and northern-central Europe for both species, with a main phylogeographic break between these regions. Although the genetic diversity results are not fully conclusive, the lower diversity observed in Iberia could reflect marginal conditions at the southern limit of their distribution range during the current interglacial period.

Hybridization patterns between two marine snails, Littorina fabalis and L. obtusata

Characterizing the patterns of hybridization between closely related species is crucial to understand the role of gene flow in speciation. In particular, systems comprising multiple contacts between sister species offer an outstanding opportunity to investigate how reproductive isolation varies with environmental conditions, demography and geographic contexts of divergence. The flat periwinkles, Littorina obtusata and L. fabalis (Gastropoda), are two intertidal sister species with marked ecological differences compatible with late stages of speciation. Although hybridization between the two was previously suggested, its extent across the Atlantic shores of Europe remained largely unknown. Here, we combined genetic (microsatellites and mtDNA) and morphological data (shell and male genital morphology) from multiple populations of flat periwinkles in north-western Iberia to assess the extent of current and past hybridization between L. obtusata and L. fabalis under two contrasting geographic settings of divergence (sympatry and allopatry). Hybridization signatures based on both mtDNA and microsatellites were stronger in sympatric sites, although evidence for recent extensive admixture was found in a single location. Misidentification of individuals into species based on shell morphology was higher in sympatric than in allopatric sites. However, despite hybridization, species distinctiveness based on this phenotypic trait together with male genital morphology remained relatively high. The observed variation in the extent of hybridization among locations provides a rare opportunity for future studies on the consequences of different levels of gene flow for reinforcement, thus informing about the mechanisms underlying the completion of speciation.

Founder effect of Fabry disease due to p.F113L mutation: Clinical profile of a late-onset phenotype

BACKGROUND

Knowledge on clinical profiles of late-onset phenotypes of Fabry disease (FD) is essential to better define their natural history. Our study aims to demonstrate a founder effect of FD due to the GLA gene mutation c.337T>C (p.F113L) in the Portuguese region of Guimarães; and to characterize the clinical profile of this late-onset phenotype in a large cohort of genetically related adult patients, living in the same region.

METHODS AND RESULTS

FD screening was performed in 150 adult patients with hypertrophic cardiomyopathy (HCM) and found 25 Fabry patients (16.6%). The p.F113L mutation was found in 21 of them, leading to a genealogy study and haplotype analysis of the p.F113L patients. Genealogy research revealed a 12-generation family tree with a common ancestor to p.F113L patients, suggesting a founder effect that was supported by haplotype findings. Pedigree analysis was performed and 120 consecutive p.F113L patients underwent a predefined diagnostic evaluation of FD multiorgan involvement. This late-onset phenotype was characterized by common and/or potentially severe cardiac manifestations (left ventricular hypertrophy 40.8%, atrial fibrillation 5%, non-sustained ventricular tachycardia 12.5%, atrioventricular block 18.3%, bifascicular block 13.4%). Extracardiac manifestations included albuminuria>30 mg/24 h 36.1%, chronic kidney disease≥G3 7.6%, brain white matter lesions 54.4%, stroke 3.3%, sensorineural deafness 44.5%, cornea verticillata 13.9%. Plasma lyso-GB3 was undetectable in females, regardless of clinical manifestations.

CONCLUSION

A founder effect of FD due to p.F113L mutation was documented by genealogy and genetics in a Portuguese region. In this late-onset phenotype, although cardiac manifestations carry the highest prognostic impact, extracardiac involvement is common.

Is embryo abortion a post-zygotic barrier to gene flow between Littorina ecotypes?

Genetic incompatibilities contribute to reproductive isolation between many diverging populations, but it is still unclear to what extent they play a role if divergence happens with gene flow. In contact zones between the "Crab" and "Wave" ecotypes of the snail Littorina saxatilis, divergent selection forms strong barriers to gene flow, while the role of post‐zygotic barriers due to selection against hybrids remains unclear. High embryo abortion rates in this species could indicate the presence of such barriers. Post‐zygotic barriers might include genetic incompatibilities (e.g. Dobzhansky–Muller incompatibilities) but also maladaptation, both expected to be most pronounced in contact zones. In addition, embryo abortion might reflect physiological stress on females and embryos independent of any genetic stress. We examined all embryos of >500 females sampled outside and inside contact zones of three populations in Sweden. Females' clutch size ranged from 0 to 1,011 embryos (mean 130 ± 123), and abortion rates varied between 0% and 100% (mean 12%). We described female genotypes by using a hybrid index based on hundreds of SNPs differentiated between ecotypes with which we characterized female genotypes. We also calculated female SNP heterozygosity and inversion karyotype. Clutch size did not vary with female hybrid index, and abortion rates were only weakly related to hybrid index in two sites but not at all in a third site. No additional variation in abortion rate was explained by female SNP heterozygosity, but increased female inversion heterozygosity added slightly to increased abortion. Our results show only weak and probably biologically insignificant post‐zygotic barriers contributing to ecotype divergence, and the high and variable abortion rates were marginally, if at all, explained by hybrid index of females.

Genomic architecture of parallel ecological divergence: Beyond a single environmental contrast

The study of parallel ecological divergence provides important clues to the operation of natural selection. Parallel divergence often occurs in heterogeneous environments with different kinds of environmental gradients in different locations, but the genomic basis underlying this process is unknown. We investigated the genomics of rapid parallel adaptation in the marine snail Littorina saxatilis in response to two independent environmental axes (crab-predation versus wave-action and low-shore versus high-shore). Using pooled whole-genome resequencing, we show that sharing of genomic regions of high differentiation between environments is generally low but increases at smaller spatial scales. We identify different shared genomic regions of divergence for each environmental axis and show that most of these regions overlap with candidate chromosomal inversions. Several inversion regions are divergent and polymorphic across many localities. We argue that chromosomal inversions could store shared variation that fuels rapid parallel adaptation to heterogeneous environments, possibly as balanced polymorphism shared by adaptive gene flow.

Cancer gene therapy mediated by RALA/plasmid DNA vectors: Nitrogen to phosphate groups ratio (N/P) as a tool for tunable transfection efficiency and apoptosis

Cancer gene therapy based on p53 tumor suppressor gene supplementation emerges as one of the most challenging and promising strategies. The development of a suitable gene delivery system is imperative to ensure the feasibility and viability of cancer gene therapy in a clinical setting. The conception of delivery systems based on cell- penetrating peptides may deeply contribute for the evolution of therapy efficacy. In this context, the present work explores the p53 encoding plasmid DNA (pDNA) condensation ability of RALA peptide to produce a suitable intracellular delivery platform. These carriers, formed at several nitrogen to phosphate groups (N/P) ratio, were characterized in terms of morphology, size, surface charges, loading and complexation capacity and the fine structure has been analyzed by Fourier-transformed infrared (FTIR) spectroscopy. Confocal microscopy studies confirmed intracellular localization of nanoparticles, resulting in enhanced sustained pDNA uptake. Moreover, in vitro transfection of HeLa cells mediated by RALA/pDNA vectors allows for gene release and p53 protein expression. From these progresses, apoptosis in cancer cells has been investigated. It was found that N/P ratio strongly tailors gene transfection efficiency and, thus, it can be fine-tuned for desired degree of both protein expression and apoptosis. The great asset of the proposed system relies precisely on the use of N/P ratio as a tailoring parameter that can not only modulate vector´s properties but also the extent of pDNA delivery, protein expression and, consequently, the efficacy of p53 mediated cancer therapy.

P1772Diagnostic accuracy of a novel electrocardiographic criterion for the diagnosis of left ventricular hypertrophy in hypertrophic cardiomyopathy

Introduction

The 12-lead electrocardiogram (ECG) is a fundamental initial diagnostic modality for the early evaluation of a patient suspected of having hypertrophic cardiomyopathy (HCM). ECG criteria for the diagnosis of left ventricular hypertrophy (LVH) typically have low sensitivity and high specificity. Recently, a novel ECG criterion (Peguero-Lo Presti, PLP) with higher sensitivity (62%) and similar specificity (90%) was developed in a cohort of hypertensive patients, but its accuracy in patients with HCM has not been tested. We hypothesized that Peguero-Lo Presti criterion would improve upon the sensitivity of other criteria, while maintaining high specificity, for the diagnosis of LVH in patients for with HCM.

Methods

We retrospectively analyzed 215 consecutive patients who underwent cardiac magnetic resonance (CMR) between 2010 and 2018 for suspected HCM. All patients aged 18 years or older, who had CMR-confirmed HCM and an ECG without confounders (complete left or right bundle brunch block or paced ventricular rhythm) were included for analysis (n=88). Left ventricular mass (LVM) index and maximum wall thickness were derived from CMR analysis. The PLP criteria was defined as the sum of the deepest S wave (SD) in any lead and the S wave amplitude of lead V4 (SV4). Cornell voltage (CL) and Sokolow-Lyon (SL) were used for comparison. We randomly selected 88 gender-matched patients who performed an ECG and CMR for other clinical reasons and who had no structural heart disease or LVH for use as controls. The DeLong and McNemar's test were used to compare ROC area under the curve (AUC) and sensitivity and specificity, respectively, between the three criteria.

Results

88 patients with HCM (63% male, mean age 56.7±15 years) were analyzed. The mean maximum wall thickness was 19.9±4.4mm and mean indexed LVM was 89.7±27g/m2. 34 patients (38.6%) had increased indexed LVM and 77 (87.5%) had at least one segment with late gadolinium enhancement (LGE). Discrimination by AUC was highest for PLP (0.85 [95% CI 0.8–0.9]), compared to CL (0.79, p=0.03) and SL (0.73, p=0.02). Using literature cut-offs, the sensitivity of PLP (60% [95% CI 50–70%]) was significantly higher compared to CL (40% [95% CI 30–50%, p<0,001) and SL (41%, [95% CI 31–51%], p=0.01), whilst maintaining high specificity (PLP 96%; CL 98%; SL 94%). After adjusting for LVM, the amount of LGE had a positive correlation with PLP amplitude (Spearman's rho=0.6, coef=2.4, p=0.01), but not Cornell or Sokolow. The sensitivity of PLP was significantly higher than CL and Sokolow in patients with LGE (61% vs 44% vs 43%, p<0.05).

Conclusion

The Peguero-Lo Presti criteria demonstrated higher sensitivity and similar specificity when compared to the Cornell and Sokolow-Lyon criteria for the diagnosis of LVH in a cohort of patients with hypertrophic cardiomyopathy. Therefore, they could become the standard ECG diagnostic criteria in patients suspected of having LVH and HCM.

Improving operational management of wastewater systems. A case study

Wastewater treatment facilities collecting wastewater from longstanding sewer networks of five municipalities in the Ave River basin (located in NW Portugal) are especially vulnerable to water inflows since they have considerable extensions of sewers installed in stream and riverbeds. TRATAVE, the company responsible for operating the system, designed and implemented a monitoring network to measure discharges along the entire drainage network and treatment facilities in order to reduce those water inflows. Several flow measurement devices were installed at strategic locations within the sewer network and integrated with a SCADA system responsible for its operation. A decision support system (DSS) is being implemented using the Delft-FEWS platform, integrating monitoring data and models. Based on monitored data and model results, an estimation of infiltration volumes during wet periods is presented. Moreover, the capabilities of the DSS are illustrated in: (i) location of manholes losses along sewer networks during wet periods; (ii) identification and location of unknown connections to the sewer network using wastewater balances; and (iii) design of a PID controller for a pumping station using on-line tank water level measurement. Acquired knowledge resulting from the DSS greatly improved the utility performance both in terms of economic revenue and environmental protection.

Signatures of Selection on Standing Genetic Variation Underlie Athletic and Navigational Performance in Racing Pigeons

Racing pigeons have been selectively bred to find their way home quickly over what are often extremely long distances. This breed is of substantial commercial value and is also an excellent avian model to gain empirical insights into the evolution of traits associated with flying performance and spatial orientation. Here, we investigate the molecular basis of the superior athletic and navigational capabilities of racing pigeons using whole-genome and RNA sequencing data. We inferred multiple signatures of positive selection distributed across the genome of racing pigeons. The strongest signature overlapped the CASK gene, a gene implicated in the formation of neuromuscular junctions. However, no diagnostic alleles were found between racing pigeons and other breeds, and only a small proportion of highly differentiated variants were exclusively detected in racing pigeons. We can thus conclude that very few individual genetic changes, if any, are either strictly necessary or sufficient for superior athletics and navigation. Gene expression analysis between racing and nonracing breeds revealed modest differences in muscle (213) and brain (29). These transcripts, however, showed only slightly elevated levels of genetic differentiation between the two groups, suggesting that most differential expression is not causative but likely a consequence of alterations in regulatory networks. Our results show that the unique suite of traits that enable fast flight, long endurance, and accurate navigation in racing pigeons, do not result from few loci acting as master switches but likely from a polygenic architecture that leveraged standing genetic variation available at the onset of the breed formation.

Multiple chromosomal rearrangements in a hybrid zone between Littorina saxatilis ecotypes

Both classical and recent studies suggest that chromosomal inversion polymorphisms are important in adaptation and speciation. However, biases in discovery and reporting of inversions make it difficult to assess their prevalence and biological importance. Here, we use an approach based on linkage disequilibrium among markers genotyped for samples collected across a transect between contrasting habitats to detect chromosomal rearrangements de novo. We report 17 polymorphic rearrangements in a single locality for the coastal marine snail, Littorina saxatilis. Patterns of diversity in the field and of recombination in controlled crosses provide strong evidence that at least the majority of these rearrangements are inversions. Most show clinal changes in frequency between habitats, suggestive of divergent selection, but only one appears to be fixed for different arrangements in the two habitats. Consistent with widespread evidence for balancing selection on inversion polymorphisms, we argue that a combination of heterosis and divergent selection can explain the observed patterns and should be considered in other systems spanning environmental gradients.

Divergent evolution in the genomes of closely related lacertids, Lacerta viridis and L. bilineata, and implications for speciation

BACKGROUND

Lacerta viridis and Lacerta bilineata are sister species of European green lizards (eastern and western clades, respectively) that, until recently, were grouped together as the L. viridis complex. Genetic incompatibilities were observed between lacertid populations through crossing experiments, which led to the delineation of two separate species within the L. viridis complex. The population history of these sister species and processes driving divergence are unknown. We constructed the first high-quality de novo genome assemblies for both L. viridis and L. bilineata through Illumina and PacBio sequencing, with annotation support provided from transcriptome sequencing of several tissues. To estimate gene flow between the two species and identify factors involved in reproductive isolation, we studied their evolutionary history, identified genomic rearrangements, detected signatures of selection on non-coding RNA, and on protein-coding genes.

FINDINGS

Here we show that gene flow was primarily unidirectional from L. bilineata to L. viridis after their split at least 1.15 million years ago. We detected positive selection of the non-coding repertoire; mutations in transcription factors; accumulation of divergence through inversions; selection on genes involved in neural development, reproduction, and behavior, as well as in ultraviolet-response, possibly driven by sexual selection, whose contribution to reproductive isolation between these lacertid species needs to be further evaluated.

CONCLUSION

The combination of short and long sequence reads resulted in one of the most complete lizard genome assemblies. The characterization of a diverse array of genomic features provided valuable insights into the demographic history of divergence among European green lizards, as well as key species differences, some of which are candidates that could have played a role in speciation. In addition, our study generated valuable genomic resources that can be used to address conservation-related issues in lacertids.

Karyotype Characterization of Nine Periwinkle Species (Gastropoda, Littorinidae)

Periwinkles of the family Littorinidae (Children, 1834) are common members of seashore littoral communities worldwide. Although the family is composed of more than 200 species belonging to 18 genera, chromosome numbers have been described in only eleven of them. A molecular cytogenetic analysis of nine periwinkle species, the rough periwinkles Littorina arcana, L. saxatilis, and L. compressa, the flat periwinkles L. obtusata and L. fabalis, the common periwinkle L. littorea, the mangrove periwinkle Littoraria angulifera, the beaded periwinkle Cenchritis muricatus, and the small periwinkle Melarhaphe neritoides was performed. All species showed diploid chromosome numbers of 2n = 34, and karyotypes were mostly composed of metacentric and submetacentric chromosome pairs. None of the periwinkle species showed chromosomal differences between male and female specimens. The chromosomal mapping of major and minor rDNA and H3 histone gene clusters by fluorescent in situ hybridization demonstrated that the patterns of distribution of these DNA sequences were conserved among closely related species and differed among less related ones. All signals occupied separated loci on different chromosome pairs without any evidence of co-localization in any of the species.