Evolution of genetic systems in filamentous ascomycetes

A great variety of genetic systems exist in filamentous ascomycetes. The transmission of genetic material does not only occur by (sexual or asexual) reproduction, but it can also follow vegetative fusion of different strains. In this thesis the evolution of this variability is studied, using theoretical population genetic models.First the evolution of different reproductive systems is studied. It is found that homothallism (allowing selfing) most probably evolved from heterothallism. (with two mating types), and that a polymorphism of homo- and heterothallism can be evolutionary stable. A variable fitness of ascospore production is predicted as an explanation for hermaphroditism in heterothallic species and the formation of both asexual and sexual spores by homothallic species.Secondly the evolution of vegetative incompatibility (VI) is studied. VI prevents vegetative fusion of different strains, and is very common between different natural isolates. In many species a large number of Vegetative Compatibility Groups (VCGs) is found, that only show vegetative fusion within and not between groups. After a comparison of different selective regimes, it is concluded that a harmful cytoplasmic element offers the most plausible selective explanation for the evolution of VI. However, the effects of genetic drift appear to be important in generating large numbers of VCGs and can override the effects of selection.Next, attention is focused on spore killing. This is a form of segregation distortion (or meiotic drive), causing the death of half the number of spores in an ascus. In a model it is found that the evolution of spore killing can only be explained if 'Spore killers' have some additional advantage during the process of killing.Finally, a model is presented for the evolution of sexual incompatibility (SI) in Podospora anserina. As the existence of SI cannot be explained on its own, a hypothesis is studied, that explains SI as an anti meiotic drive device. Although the model shows that this hypothesis could be true, experimental evidence is needed to confirm this

Evaluation of risk based microbiological criteria for Campylobacter in broiler carcasses in Belgium using TRiMiCri

Campylobacteriosis is the most frequently reported foodborne zoonosis worldwide. Consumer´s exposure to Campylobacter might be reduced by establishing a microbiological criterion (MC) for Campylobacter on broiler meat. In the present study two possible approaches were evaluated, using the freely available software tool for risk based microbiological criteria TRiMiCri (http://tools.food.dtu.dk/trimicri). The first approach was the traditional one that implies a microbiological limit (ML-MC) and the second one which is based on the relative risk estimate (RRL-MC). The analyses were based on Campylobacter quantitative data collected from 28 Campylobacter positive bathes processed in 6 Belgian broiler slaughterhouses. To evaluate the performance of ML-MC, n=6, different c (0,1,2) and m (100,1 000,10 000) were used. Results showed that more than 90% of Campylobacter positive batches were not complying with strict ML criteria based on the m=100 for all applied combination of c. The RRL approach requires a baseline risk which was estimated based on the Campylobacter baseline data collected in Belgium in 2008. Approximately 60% of evaluated Campylobacter positive batches account for higher risk than the baseline risk. For both approaches, application of less stringent criteria results in lower percentage of NC and higher minimum relative residual risks (MRRR; it refers to the change in risk when all batches are sampled and all NC batches undergo treatment that effectively eliminates Campylobacter so they are replaced by zero risk batches). It was also observed that the number of samples (n) had little effect on risk estimates. Additionally, the results from ML-MC and RRL-MC follow the same curve when plotting percentage of NC against MRRR. However, for RRL-MC the percentage of NC batches and MRRR was lower and higher, respectively. To conclude, obtained results indicate that TRiMiCri is a useful and user friendly tool to make a risk based decision on the choice of the MC

Smart Distance Lab’s art fair, experimental data on social distancing during the COVID-19 pandemic

In the absence of a vaccine, social distancing behaviour is pivotal to mitigate COVID-19 virus spread. In this large-scale behavioural experiment, we gathered data during Smart Distance Lab: The Art Fair (n = 839) between August 28 and 30, 2020 in Amsterdam, the Netherlands. We varied walking directions (bidirectional, unidirectional, and no directions) and supplementary interventions (face mask and buzzer to alert visitors of 1.5 metres distance). We captured visitors’ movements using cameras, registered their contacts (defined as within 1.5 metres) using wearable sensors, and assessed their attitudes toward COVID-19 as well as their experience during the event using questionnaires. We also registered environmental measures (e.g., humidity). In this paper, we describe this unprecedented, multi-modal experimental data set on social distancing, including psychological, behavioural, and environmental measures. The data set is available on figshare and in a MySQL database. It can be used to gain insight into (attitudes toward) behavioural interventions promoting social distancing, to calibrate pedestrian models, and to inform new studies on behavioural interventions

Early and late optical coherence tomography findings following everolimus-eluting bioresorbable vascular scaffold implantation in myocardial infarction: A preliminary report

Introduction: Although bioresorbable vascular scaffolds (BVS) have been used with promising results in patients with stable and unstable angina, little is known about the acute vascular response following BVS implantation in myocardial infarction. We present angiographic and OCT findings from the first patients undergoing bioresorbable vascular scaffold (BVS) implantation for non-ST-elevation myocardial infarction (NSTEMI) or ST-elevation myocardial infarction (STEMI) in our institution. Methods: The first 5 patients with NSTEMI and the first 5 patients with STEMI who underwent BVS implantation in our institution, followed by optical coherence tomography (OCT) imaging of the treated culprit vessel, were included in this series. All patients underwent angiographic analysis pre- and post- BVS implantation, as well as OCT analysis, including qualitative and quantitative assessment. Results: Implantation was successful in all cases, as assessed by angiography and OCT. There were no cases with coronary spasm, distal embolization or no-reflow. No adverse clinical events were recorded in any patient at the 6-month follow up. Specific illustrative cases demonstrating the challenges of BVS implantation in myocardial infarction are presented. Conclusions: BVS implantation can potentially be used in the setting of thrombotic lesions encountered in myocardial infarction; however, the role of this treatment approach warrants systematic evaluation in prospective studies

Everolimus-eluting bioresorbable vascular scaffolds for treatment of patients presenting with ST-segment elevation myocardial infarction: BVS STEMI first study

AimsWe evaluated the feasibility and the acute performance of the everolimus-eluting bioresorbable vascular scaffolds (BVS) for the treatment of patients presenting with ST-segment elevation myocardial infarction (STEMI).Methods and resultsThe present investigation is a prospective, single-arm, single-centre study, reporting data after the BVS implantation in STEMI patients. Quantitative coronary angiography and optical coherence tomography (OCT) data were evaluated. Clinical outcomes are reported at the 30-day follow-up. The intent-to-treat population comprises a total of 49 patients. The procedural success was 97.9%. Pre-procedure TIMI-flow was 0 in 50.0% of the patients; after the BVS implantation, a TIMI-flow III was achieved in 91.7% of patients and the post-procedure percentage diameter stenosis was 14.7 ± 8.2%. No patients had angiographically visible residual thrombus at the end of the procedure. Optical coherence tomography analysis performed in 31 patients showed that the post-procedure mean lumen area was 8.02 ± 1.92 mm2, minimum lumen area 5.95 ± 1.61 mm2, mean incomplete scaffold apposition area 0.118 ± 0.162 mm2, mean intraluminal defect area 0.013 ± 0.017 mm2, and mean percentage malapposed struts per patient 2.80 ± 3.90%. Scaffolds with >5% malapposed struts were 7. At the 30-day follow-up, target-lesion failure rate was 0%. Non-target-vessel revascularization and target-vessel myocardial infarction (MI) were reported. A non-target-vessel non-Q-wave MI occurred. No cases of cardiac death or scaffold thrombosis were observed.ConclusionIn the present series, the BVS implantation in patients presenting with acute MI appeared feasible, with high rate of final TIMI-flow III and good scaffold apposition. Larger studies are currently needed to confirm these preliminary data