Do microplastic particles affect Daphnia magna at the morphological, life history and molecular level?

Microplastic particles are ubiquitous not only in marine but also in freshwater ecosystems. However, the impacts of microplastics, consisting of a large variety of synthetic polymers, on freshwater organisms remains poorly understood. We examined the effects of two polymer mixtures on the morphology, life history and on the molecular level of the waterflea Daphnia magna (three different clones). Microplastic particles of ~40 μm were supplied at a low concentration (1% of the food particles) leading to an average of ~30 particles in the digestive tract which reflects a high microplastic contamination but still resembles a natural situation. Neither increased mortality nor changes on the morphological (body length, width and tail spine length) or reproductive parameters were observed for adult Daphnia. The analyses of juvenile Daphnia revealed a variety of small and rather subtle responses of morphological traits (body length, width and tail spine length). For adult Daphnia, alterations in expression of genes related to stress responses (i.e. HSP60, HSP70 & GST) as well as of other genes involved in body function and body composition (i.e. SERCA) were observed already 48h after exposure. We anticipate that the adverse effects of microplastic might be influenced by many additional factors like size, shape, type and even age of the particles and that the rather weak effects, as detected in a laboratory, may lead to reduced fitness in a natural multi-stressor environment

New possibilities arise for studies of hybridization: SNP-based markers for the multi-species Daphnia longispina complex derived from transcriptome data

In order to trace community dynamics and reticulate evolution in hybrid species complexes, long-term comparative studies of natural populations are necessary. Such studies require the development of tools for fine-scale genetic analyses. In the present study, we developed species-diagnostic SNP-based markers for hybridizing freshwater crustaceans: the multispecies Daphnia longispina complex. Specifically, we took advantage of transcriptome data from a key species of this hybrid complex, the annotated genome of a related Daphnia species and well-defined reference genotypes from three parental species. Altogether eleven nuclear loci with several species-specific SNP sites were identified in sequence alignments of these reference genotypes from three parental species and their interspecific hybrids. A PCR-RFLP assay was developed for cost-efficient large population screening by SNP-based genotyping. Taxon assignment by RFLP patterns was nearly perfectly concordant with microsatellite genotyping across several screened populations from Europe. Finally, we were able to amplify two short regions of these loci in formaldehyde-preserved samples dating back to the year 1960. The species-specific SNP-based markers developed here provide valuable tools to study hybridization over time, including the long-term impact of various environmental factors on hybridization and biodiversity changes. SNP-based genotyping will finally allow eco-evolutionary dynamics to be revealed at different time scale

Development of molecular tools to study Daphnia - parasite dynamics

Evolutionary dynamics of hosts and their parasites are complex processes. In order to study these processes on genotype level, reliable molecular tools have to be developed. The goal of this thesis was to develop such tools for freshwater crustaceans - Daphnia longispina species complex and its parasites. On one hand, from the host side - an interspecific hybridization plays an important role. For tracing community dynamics and reticulate evolution in such a hybrid species complex, long-term comparative studies of natural populations are necessary. In order to conduct such a study, it is essential to access historical samples. These samples are usually suffering from low DNA quality due to the preservation chemical such as formaldehyde or denaturated ethanol, therefore traditional genotyping through length-based markers (such as microsatellites or allozymes) proved to be insufficient. For circumventing these issues, SNP- based markers were developed. Based on transcriptome data of one species belonging to the complex, it was possible to amplify and sequence several unlinked loci, which were then scanned for species-specific SNPs. Altogether 11 loci distinguishing all three species of the complex and their hybrids were developed and incorporated into PCR-RFLP assay. By comparing the taxon assignment from microsatellite and SNP data, there was found nearly perfect concordance. Finally, the genotyping method was successfully tested on samples dating back to the year 1960. On the other hand, parasite genetic studies are much more limited, in terms of availability of molecular markers. Only handful of parasites allows their cultivation under laboratory conditions inside the hosts. Even then, their disproportional amount of DNA compared to hosts and additional presence of other organisms present in media is forcing to rely on the traditional markers such as internal transcribed spacer (ITS). The traditional method of obtaining sequences to access the diversity (Sanger sequencing preceded by cloning – due to high intragenomic variation of this region) is becoming inefficient due to its high costs in terms of funds and time. Therefore, there was developed a molecular pipeline able to produce and process larger amount of sequence data with more accurate processing, specifically using a next-generation-sequencing platform (454). Afterwards a new bioinformatic pipeline QRS (quantification of representative sequences) was developed, inferring the representative sequences from the next generation sequencing (NGS) data sets (based on neighbor joining or statistical parsimony) and calculating their frequencies. Verification of the method was done by comparing the dataset with the previous study of population structure of Daphnia parasite Caullerya mesnili based on cloning and Sanger sequencing. Pipelines were then used for accessing genetic diversity of the two parasite microsporidian species (Berwaldia and MIC1) commonly infecting Daphnia longispina complex in Central Europe. Specifically, the patterns of geographic population structure, intraspecific genetic variation, and the recombination events were examined, which are necessary for better characterization of the biology of these parasites. The limited geographical variation that was observed in Berwaldia and the different lake origin of recombinant and parental sequences supports usage of a mobile secondary host hypothesis during the life cycle of this species. Similarly MIC1 seems to have a secondary host, however the secondary hosts of both parasites likely differ and the Berwaldia`s one is assumed to have a higher mobility than the one transmitting MIC1.Die evolutionäre Dynamik von Wirtsarten und ihren Parasiten beinhaltet komplexe Prozesse. Zur Untersuchung dieser Prozesse auf der Ebene des Genotyps ist die Entwicklung zuverlässiger molekularer Werkzeuge notwendig. Das Ziel der vorliegenden Arbeit war die Entwicklung solcher Werkzeuge für den Daphnia longispina-Artenkomplex (Süßwasser-Crustaceen) und seine Parasiten. Einerseits spielt auf Seiten des Wirts interspezifische Hybridisierung eine große Rolle. Um die Dynamik der Artengemeinschaft sowie die verästelte Evolution innerhalb eines solchen Hybridartenkomplexes nachzuvollziehen, sind vergleichende Langzeitstudien natürlicher Populationen notwendig. Zur Durchführung einer solchen Studie ist die Einbeziehung historischer Proben essentiell. Diese Proben haben üblicherweise den Nachteil einer niedrigen DNA-Qualität durch Konservierungsmittel wie Formaldehyd oder vergällter Ethanol. Daher erwiesen sich traditionelle Methoden zur Genotypisierung mittels längenbasierter Marker wie Mikrosatelliten oder Allozyme als unzureichend. Aus diesem Grund wurden SNP-basierte Marker entwickelt. Basierend auf Transkriptomdaten einer Art aus dem Daphnia longispina-Artenkomplex konnten mehrere ungekoppelte Loci amplifiziert, sequenziert und nach artspezifischen SNPs durchsucht werden. Insgesamt wurden 11 SNP-Marker entwickelt, die alle drei Arten und ihre Hybriden unterscheiden und mit Hilfe eines PCR-RFLP-Tests untersucht wurden. Beim Vergleich der Taxonzuordnung von Mikrosatelliten- und SNP-Daten wurde annähernd perfekte Übereinstimmung gefunden. Schlussendlich konnte die Genotypisierungsmethode erfolgreich angewendet werden auf Proben, die aus dem Jahr 1960 stammen. Andererseits sind Studien zur Parasitengenetik viel beschränkter in Hinblick auf die Verfügbarkeit molekularer Marker. Nur wenige Parasiten können unter Laborbedingungen in den Wirtsorganismen kultiviert werden. Außerdem lässt die unverhältnismäßig kleine DNA-Menge der Parasiten im Vergleich zum Wirt und die Anwesenheit anderer Organismen im Kulturmedium wenig Alternativen zur Verwendung traditioneller Marker wie ITS (interne transkribierte Spacer). Die traditionelle Methode, Sequenzdaten zur Beurteilung der Diversität zu erhalten (Sanger-Sequenzierung gefolgt von Klonierung wegen der hohen intragenomischen Variation dieser Region) ist mittlerweile ineffizient durch den hohen finanziellen und zeitlichen Aufwand. Daher wurde eine molekulare Pipeline entwickelt, um größere Datenmengen zu produzieren und fehlerfreier zu verarbeiten unter Verwendung einer Next Generation Sequencing-Plattform (454). Anschließend wurde eine neuartige bioinformatische Pipeline ‚QRS‘ (Quantification of Representative Sequences, Quantifizierung Repräsentativer Sequenzen) entwickelt, die mithilfe von Neighbor Joining- und Parsimony-Ansätzen repräsentative Sequenzen aus Next Generation Sequencing (NGS)- Datensätzen ermittelt und deren Frequenzen berechnet. Die Methode wurde verifiziert durch den Vergleich des Datensatzes mit einer vorangegangenen Studie zur Populationsstruktur des Daphnia-Parasiten Caullerya mesnili, die auf Klonierung und Sanger-Sequenzierung basierte. Die Pipelines wurden anschließend zur Untersuchung der genetischen Diversität zweier parasitärer Mikrosporidienarten (Berwaldia und MIC1) verwendet, die häufig den Daphnia longispina-Komplex in Zentraleuropa infizieren. Besonders die Muster geografischer Populationsstruktur, intraspezifische genetische Variation und Rekombinationsereignisse wurden untersucht, da sie eine bessere Charakterisierung der Parasitenbiologie ermöglichen. Die bei Berwaldia beobachtete begrenzte geografische Variation und die Herkunft der rekombinanten und parentalen Sequenzen aus unterschiedlichen Seen unterstützt die Hypothese eines sekundären mobilen Wirts im Lebenszyklus dieser Art. Ebenso scheint MIC1 einen sekundären Wirt zu haben. Allerdings unterscheiden sich die sekundären Wirte der beiden Parasiten wahrscheinlich, wobei derjenige von Berwaldia vermutlich eine höhere Mobilität aufweist als der Wirt, der MIC1 überträgt

Adapting to change: a systematic review of anatomy education methods during the COVID-19 pandemic

The COVID-19 pandemic has significantly altered the dynamics of medical education, particularly in thedomain of anatomy teaching. This systematic review investigates the modifications implemented in anatomyeducation during the pandemic, emphasizing the shift from traditional pedagogical methods to online andvirtual modalities. A comprehensive search across databases such as PubMed, Embase, Scopus, andWeb of Science identified 10 studies that met the inclusion criteria. These studies collectively underscorethe rapid transition to online platforms for conducting lectures, tutorials, and practical anatomy sessions.Despite challenges related to diminished hands-on experiences and concerns about student engagement,the integration of digital tools like virtual dissection software, 3D anatomical models, and Zoom-basedflipped classroom sessions has demonstrated potential in maintaining the continuity of anatomy education.Notably, student feedback has highlighted both the benefits, such as flexible learning schedules, and thedrawbacks, including internet connectivity issues and reduced practical exposure. This review highlightsthe need for further research to assess the long-term effectiveness of online teaching methodologies andtheir impact on students’ clinical skills and professional development. Additionally, the perspectives ofboth students and faculty suggest that a blended approach combining online and face-to-face instructioncould be viable path forward in post-pandemic anatomy education

Rare earth elements and uranium in Minjingu phosphate fertilizer products : plant food for thought

DATA AVAILABILITY : Data will be made available on request.Minjingu phosphate ore is Tanzania's sole domestic supply of phosphorus (P). The ore contains medium to high concentrations of naturally occurring P2O5 (20–35 %) and relevant concentrations of uranium and rare earth elements (REEs) are also suspected to be present. Currently, neither uranium nor REEs are recovered. They either end up in mine tailings or are spread across agricultural soils with fertilizer products. This work provides a first systematic review of the uranium and REE concentrations that can be expected in the different layers of Minjingu phosphate ore, the way the ore is presently processed, as well as a discussion on alternative processing pathways with uranium/REE recovery. The study analyzed ten distinct Minjingu phosphate ore layers, four mine tailings, and five intermediate and final mineral fertilizer products from the Minjingu mine and processing plant located in northern Tanzania. The results confirm that the uranium concentrations and to a lesser degree, the REE concentrations are indeed elevated if compared to concentrations in other phosphate ores. The study does not identify a significant risk resulting from this. The development of techno-economic solutions for more comprehensive utilization of Minjingu ore is, however, strongly encouraged and suggestions on such processes are provided.The Tanzania Atomic Energy Commission (TAEC), Nelson Mandela African Institution of Science and Technology (NM-AIST), the Austrian Federal Ministry of Education, Science and Research (BMBWF) through Austria's Agency for Education and Internationalization (OeAD) and BMBWF/OeAD support through a Ernst Mach Grant.https://www.sciencedirect.com/journal/resources-conservation-and-recyclinghj2024Chemical EngineeringChemistrySDG-09: Industry, innovation and infrastructur

Daphnia parasite dynamics across multiple Caullerya epidemics indicate selection against common parasite genotypes

Studies of parasite population dynamics in natural systems are crucial for our understanding of host–parasite coevolutionary processes. Some field studies have reported that host genotype frequencies in natural populations change over time according to parasite-driven negative frequency-dependent selection. However, the temporal patterns of parasite genotypes have rarely been investigated. Moreover, parasite-driven negative frequency-dependent selection is contingent on the existence of genetic specificity between hosts and parasites. In the present study, the population dynamics and host-genotype specificity of the ichthyosporean Caullerya mesnili, a common endoparasite of Daphnia water fleas, were analysed based on the observed sequence variation in the first internal transcribed spacer (ITS1) of the ribosomal DNA. The Daphnia population of lake Greifensee (Switzerland) was sampled and subjected to parasite screening and host genotyping during C. mesnili epidemics of four consecutive years. The ITS1 of wild-caught C. mesnili-infected Daphnia was sequenced using the 454 pyrosequencing platform. The relative frequencies of C. mesnili ITS1 sequences differed significantly among years: the most abundant C. mesnili ITS1 sequence decreased and rare sequences increased over the course of the study, a pattern consistent with negative frequency-dependent selection. However, only a weak signal of host-genotype specificity between C. mesnili and Daphnia genotypes was detected. Use of cutting edge genomic techniques will allow further investigation of the underlying micro-evolutionary relationships within the Daphnia–C. mesnili system

Worldwide trends in underweight and obesity from 1990 to 2022: a pooled analysis of 3663 population-representative studies with 222 million children, adolescents, and adults

Background Underweight and obesity are associated with adverse health outcomes throughout the life course. We estimated the individual and combined prevalence of underweight or thinness and obesity, and their changes, from 1990 to 2022 for adults and school-aged children and adolescents in 200 countries and territories. Methods We used data from 3663 population-based studies with 222 million participants that measured height and weight in representative samples of the general population. We used a Bayesian hierarchical model to estimate trends in the prevalence of different BMI categories, separately for adults (age ≥20 years) and school-aged children and adolescents (age 5–19 years), from 1990 to 2022 for 200 countries and territories. For adults, we report the individual and combined prevalence of underweight (BMI <18·5 kg/m2) and obesity (BMI ≥30 kg/m2). For schoolaged children and adolescents, we report thinness (BMI <2 SD below the median of the WHO growth reference) and obesity (BMI >2 SD above the median). Findings From 1990 to 2022, the combined prevalence of underweight and obesity in adults decreased in 11 countries (6%) for women and 17 (9%) for men with a posterior probability of at least 0·80 that the observed changes were true decreases. The combined prevalence increased in 162 countries (81%) for women and 140 countries (70%) for men with a posterior probability of at least 0·80. In 2022, the combined prevalence of underweight and obesity was highest in island nations in the Caribbean and Polynesia and Micronesia, and countries in the Middle East and north Africa. Obesity prevalence was higher than underweight with posterior probability of at least 0·80 in 177 countries (89%) for women and 145 (73%) for men in 2022, whereas the converse was true in 16 countries (8%) for women, and 39 (20%) for men. From 1990 to 2022, the combined prevalence of thinness and obesity decreased among girls in five countries (3%) and among boys in 15 countries (8%) with a posterior probability of at least 0·80, and increased among girls in 140 countries (70%) and boys in 137 countries (69%) with a posterior probability of at least 0·80. The countries with highest combined prevalence of thinness and obesity in school-aged children and adolescents in 2022 were in Polynesia and Micronesia and the Caribbean for both sexes, and Chile and Qatar for boys. Combined prevalence was also high in some countries in south Asia, such as India and Pakistan, where thinness remained prevalent despite having declined. In 2022, obesity in school-aged children and adolescents was more prevalent than thinness with a posterior probability of at least 0·80 among girls in 133 countries (67%) and boys in 125 countries (63%), whereas the converse was true in 35 countries (18%) and 42 countries (21%), respectively. In almost all countries for both adults and school-aged children and adolescents, the increases in double burden were driven by increases in obesity, and decreases in double burden by declining underweight or thinness. Interpretation The combined burden of underweight and obesity has increased in most countries, driven by an increase in obesity, while underweight and thinness remain prevalent in south Asia and parts of Africa. A healthy nutrition transition that enhances access to nutritious foods is needed to address the remaining burden of underweight while curbing and reversing the increase in obesit

Worldwide trends in underweight and obesity from 1990 to 2022 : a pooled analysis of 3663 population-representative studies with 222 million children, adolescents, and adults

A list of authors and their affiliations appears online. A supplementary appendix is herewith attached.Background: Underweight and obesity are associated with adverse health outcomes throughout the life course. We estimated the individual and combined prevalence of underweight or thinness and obesity, and their changes, from 1990 to 2022 for adults and school-aged children and adolescents in 200 countries and territories. Methods: We used data from 3663 population-based studies with 222 million participants that measured height and weight in representative samples of the general population. We used a Bayesian hierarchical model to estimate trends in the prevalence of different BMI categories, separately for adults (age ≥20 years) and school-aged children and adolescents (age 5–19 years), from 1990 to 2022 for 200 countries and territories. For adults, we report the individual and combined prevalence of underweight (BMI 2 SD above the median). Findings: From 1990 to 2022, the combined prevalence of underweight and obesity in adults decreased in 11 countries (6%) for women and 17 (9%) for men with a posterior probability of at least 0·80 that the observed changes were true decreases. The combined prevalence increased in 162 countries (81%) for women and 140 countries (70%) for men with a posterior probability of at least 0·80. In 2022, the combined prevalence of underweight and obesity was highest in island nations in the Caribbean and Polynesia and Micronesia, and countries in the Middle East and north Africa. Obesity prevalence was higher than underweight with posterior probability of at least 0·80 in 177 countries (89%) for women and 145 (73%) for men in 2022, whereas the converse was true in 16 countries (8%) for women, and 39 (20%) for men. From 1990 to 2022, the combined prevalence of thinness and obesity decreased among girls in five countries (3%) and among boys in 15 countries (8%) with a posterior probability of at least 0·80, and increased among girls in 140 countries (70%) and boys in 137 countries (69%) with a posterior probability of at least 0·80. The countries with highest combined prevalence of thinness and obesity in school-aged children and adolescents in 2022 were in Polynesia and Micronesia and the Caribbean for both sexes, and Chile and Qatar for boys. Combined prevalence was also high in some countries in south Asia, such as India and Pakistan, where thinness remained prevalent despite having declined. In 2022, obesity in school-aged children and adolescents was more prevalent than thinness with a posterior probability of at least 0·80 among girls in 133 countries (67%) and boys in 125 countries (63%), whereas the converse was true in 35 countries (18%) and 42 countries (21%), respectively. In almost all countries for both adults and school-aged children and adolescents, the increases in double burden were driven by increases in obesity, and decreases in double burden by declining underweight or thinness. Interpretation: The combined burden of underweight and obesity has increased in most countries, driven by an increase in obesity, while underweight and thinness remain prevalent in south Asia and parts of Africa. A healthy nutrition transition that enhances access to nutritious foods is needed to address the remaining burden of underweight while curbing and reversing the increase in obesity.peer-reviewe