The ultrastructure of the apical organ of the Müller's larva of the tiger flatworm Prostheceraeus crozieri

The tiger flatworm Prostheceraeus crozieri (Polycladida) develops via an eight-lobed, and three-eyed planktonic Müller's larva. This larva has an apical organ, ultrastructural details of which remain elusive due to a scarcity of studies. The evolution and possible homology of the polyclad larva with other spiralian larvae is still controversial. Here, we provide ultrastructural data and three-dimensional reconstructions of the apical organ of P. crozieri. The apical organ consists of an apical tuft complex and a dorso-apical tuft complex. The apical tuft complex features a central tuft of five long cilia, which emerge from four or five individual cells that are themselves encircled by two anchor cells. The necks of six multibranched gland cells are sandwiched between ciliated tuft cell bodies and anchor cells. The proximal parts of the ciliated cell bodies are in contact with the lateral brain neuropil via gap junctions. Located dorsally of the apical tuft complex, the dorso-apical tuft complex is characterized by several long cilia of sensory neurons, these emerge from an epidermal lumen and are closely associated with several gland cells that form a crescent apically around the dorsal anchor cell, and laterally touch the brain neuropil. Such ciliated sensory neurons emerging from a ciliated lumen are reminiscent of ampullary cells of mollusc and annelid larvae; a similar cell type can be found in the hoplonemertean decidula larva. We hypothesize that the ampullary-like cells and the tuft-forming sensory cells in the apical organs of these spiralian larvae could be homologous

No time to die : comparative study on preservation protocols for anaerobic fungi

Anaerobic fungi (AF, phylum Neocallimastigomycota) are best known for their ability to anaerobically degrade recalcitrant lignocellulosic biomass through mechanic and enzymatic means. While their biotechnological potential is well-recognized, applied research on AF is still hampered by the time-consuming and cost-intensive laboratory routines required to isolate, maintain, and preserve AF cultures. Reliable long-term preservation of specific AF strains would aid basic as well as applied research, but commonly used laboratory protocols for AF preservation can show erratic survival rates and usually exhibit only moderate resuscitation success for up to one or two years after preservation. To address both, the variability, and the preservation issues, we have set up a cross-laboratory, year-long study. We tested five different protocols for the preservation of AF. The experiments were performed at three different laboratories (Austria, Germany, Switzerland) with the same three morphologically distinct AF isolates (Anaeromyces mucronatus, Caeocmyces sp., and Neocallimastix cameroonii) living in stable co-culture with their naturally occurring, syntrophic methanogens. We could show that handling greatly contributes to the variability of results, especially in Anaeromyces mucronatus. Cryopreservation of (mature) biomass in liquid nitrogen had the highest overall survival rates (85–100%, depending on the strain and laboratory). Additionally, preservation on agar at 39°C had surprisingly high survival rates for up to 9 months, if pieces of agar containing mature AF thalli were resuscitated. This low-cost, low-effort method could replace consecutive batch cultivation for periods of up to 6 months, while long-term preservation is best done by cryopreservation in liquid nitrogen. Regardless of the method, however, preserving several replicates (>three) of the same strain is highly advisable

Tripmarks : Is everything everywhere?

Microbial biogeography has long been and is still influenced by the hypothesis of a microbial cosmopolitanism meaning that everything is everywhere, but, the environment selects. A number of studies were able to confirm the existence of globally occurring species. However, a general cosmopolitanism of microorganisms is arguable taking into account appearing geographical patterns and applying high resolving molecular and fingerprinting methods. High costs and questionable feasibility of global sampling cause many studies to be carried out based on models. In this study we benefit from the bicycle trip of an artist sampling soils on a route from Austria (Europe) to Laos (Asia) and relate the communities of inherent fungi, ammonia-oxidising bacteria and actinobacteria to environmental as well as medium- and large scale spatial patterns. We first generate spatial variables applying the large scale trend surface analysis and the finer-scale Principal Coordinates of Neighbour Matrices. Then we check for influences using variation partitioning and subsequently combine all variables in the descriptive Canonical Correspondence Analysis. Our results show that the variability in all investigated microbial groups is to the greatest extent owed to environmental and not spatial patterns. Clearly distinct communities in soils of far apart lying sampling sites are formed for AOB, but not for actinobacteria. Furthermore, cosmopolitan species with relative abundances as high as 80.5% (fungi) 74.0 % (actinobacteria) and 68.0% (AOB) have been detected. These findings show that Eurasian soil microbial communities are following environmental rather than spatial constraints, highlighting the unequal influence of all concerned variables on different organisms and sites and strengthening the assumption of a global distribution especially for actinobacteria.Magdalena NaglerInnsbruck, Univ., Master-Arb., 2014(VLID)12578

Extracellular DNA in natural environments: features, relevance and applications

Extracellular DNA (exDNA) is abundant in many habitats, including soil, sediments, oceans and freshwater as well as the intercellular milieu of metazoa. For a long time, its origin has been assumed to be mainly lysed cells. Nowadays, research is collecting evidence that exDNA is often secreted actively and is used to perform a number of tasks, thereby offering an attractive target or tool for biotechnological, medical, environmental and general microbiological applications. The present review gives an overview on the main research areas dealing with exDNA, depicts its inherent origins and functions and deduces the potential of existing and emerging exDNA-based applications. Furthermore, it provides an overview on existing extraction methods and indicates common pitfalls that should be avoided whilst working with exDNA.(VLID)4655734Version of recor

Most users do not follow political elites on Twitter; those who do show overwhelming preferences for ideological congruity

We offer comprehensive evidence of preferences for ideological congruity when people engage with politicians, pundits, and news organizations on social media. Using 4 years of data (2016–2019) from a random sample of 1.5 million Twitter users, we examine three behaviors studied separately to date: (i) following of in-group versus out-group elites, (ii) sharing in-group versus out-group information (retweeting), and (iii) commenting on the shared information (quote tweeting). We find that the majority of users (60%) do not follow any political elites. Those who do follow in-group elite accounts at much higher rates than out-group accounts (90 versus 10%), share information from in-group elites 13 times more frequently than from out-group elites, and often add negative comments to the shared out-group information. Conservatives are twice as likely as liberals to share in-group versus out-group content. These patterns are robust, emerge across issues and political elites, and exist regardless of users’ ideological extremity

Echo chambers revisited: The (overwhelming) sharing of in-group politicians, pundits and media on Twitter

Analyzing four years of data from a random sample of about 1.5 million Twitter users (and about 180,000 politically engaged users), we revisit the debate regarding the extent to which social media users live in political ``echo chambers'' with two new analytic approaches. First, we focus on the sharing of content from political elites, arguably the most influential and politically active actors, and estimate the extent to which ordinary users share messages from politicians, pundits, and news media of the same versus opposing ideology. Second, we examine the extent to which this sharing is annotated by users before it is shared (``quoted retweets'') and the tone of these annotations (e.g., do users share out-group content with negative commentary?). We find clear patterns indicative of echo-chambers: the politically engaged users analyzed share in-group messages from elites 14 times more frequently than out-group messages; and in the rare instances when out-group information is shared, a non-trivial amount of times it is accompanied by negative comments. These patterns emerge after accounting for how many in-group versus out-group elites a person follows, and are robust to the political interest of the user or extremity of the elite accounts, the topic of the tweet, and the type of political elite source of the original message. In line with previous research, we also find that this echo chamber is especially pronounced among conservative users, who are about twice as likely as liberals to share in-group vs out-group content. These findings have important implications for how we theorize and study online echo chambers

Estimating aquatic invertebrate diversity in the southern Alps using data from Biodiversity Days

High biodiversity is a prerequisite for the integrity, stability, and functioning of global aquatic ecosystems, but it is currently subject to anthropogenic threats. Small freshwater bodies with high habitat diversity are essential to sustain regional biodiversity, but species inventory and biodiversity are largely overlooked, especially in mountainous regions. In the Italian Alps, obligate assessments of freshwater biota (e.g., for the European water framework directive, WFD) are usually done in larger rivers or lakes only, which is why many taxa from small freshwater habitats might have been overlooked so far. Here we summarize and discuss the efforts to record aquatic invertebrates within the framework of so-called "Biodiversity Days", organized since 2001 at 13 different sites located across the North Italian province of South Tyrol. These events with voluntary participation of scientists and naturalists from universities and environmental agencies led to the detection of 334 benthic invertebrate taxa in streams and lakes (mostly species or genus level), whereby higher taxa richness was found in streams. The overall hierarchy of species numbers within invertebrate orders or families corresponded to that of other Alpine regions (groups richest in taxa were Chironomidae and Trichoptera) and these Biodiversity Days contributed to biodiversity research of that region in detecting 167 additional taxa. Besides analyzing yearly gains in the regional taxa inventory, we predict that future surveys will lead to new discoveries of aquatic taxa for that province (i.e., current modeling estimates a regional inventory of more than 600 taxa). However, specific surveys in hitherto unconsidered habitats, such as morphologically modified or urban waters, might reveal even more taxa than currently estimated. Besides characterizing the invertebrate fauna of this region and providing a first reference list for future monitoring projects in the same region, this work demonstrates that such Biodiversity Days can contribute to biodiversity research

Pesticide contamination and associated risk factors at public playgrounds near intensively managed apple and wine orchards

BACKGROUND: Pesticide levels are generally monitored within agricultural areas, but are commonly not assessed at public places. To assess possible contamination of non-target areas, 71 public playgrounds located next to intensively managed apple and wine orchards were selected in four valleys of South Tyrol (northern Italy). Further, the impact of environmental site characteristics on the number and concentration of pesticides was assessed. Grass samples from the selected playgrounds were collected and screened for 315 pesticide residues using standard gas chromatography and mass spectrometry. RESULTS: Nearly half of the playgrounds (45%) were contaminated by at least one pesticide and a quarter (24%) by more than one. Eleven of the 12 different detected pesticides are classified as endocrine-active substances including the insecticide phosmet and the fungicide fluazinam showing the highest concentrations (0.069 and 0.26 mg kg−1, respectively). Additionally, one disinfectant and one preservation agent was found. Playgrounds in Venosta valley were most often contaminated (76% of all investigated playgrounds), highest concentrations were found in the Low Adige (2.02 mg kg−1). Pesticide concentrations were positively associated with areal proportion of apple orchards in the surroundings, the amount of rainfall and wind speed. In contrast, increasing global irradiance, opposite wind direction, increasing distance to agricultural sites and high wind speeds when pesticide application was not allowed were associated with decreasing pesticide contamination. CONCLUSION: This study is among the first investigating pesticide contamination of public playgrounds together with environmental factors in areas with pesticide-intensive agriculture at the beginning of the growing season. It is likely that playgrounds will be affected by more pesticides and higher concentrations over the course of the crop season. The result, that the majority of the detected pesticides are classified as endocrine active is worrisome as children are especially vulnerable. Hence, we recommend that pesticide risk assessments should better include protection measures for non-target areas

Presentation_1_No time to die: Comparative study on preservation protocols for anaerobic fungi.pdf

Anaerobic fungi (AF, phylum Neocallimastigomycota) are best known for their ability to anaerobically degrade recalcitrant lignocellulosic biomass through mechanic and enzymatic means. While their biotechnological potential is well-recognized, applied research on AF is still hampered by the time-consuming and cost-intensive laboratory routines required to isolate, maintain, and preserve AF cultures. Reliable long-term preservation of specific AF strains would aid basic as well as applied research, but commonly used laboratory protocols for AF preservation can show erratic survival rates and usually exhibit only moderate resuscitation success for up to one or two years after preservation. To address both, the variability, and the preservation issues, we have set up a cross-laboratory, year-long study. We tested five different protocols for the preservation of AF. The experiments were performed at three different laboratories (Austria, Germany, Switzerland) with the same three morphologically distinct AF isolates (Anaeromyces mucronatus, Caeocmyces sp., and Neocallimastix cameroonii) living in stable co-culture with their naturally occurring, syntrophic methanogens. We could show that handling greatly contributes to the variability of results, especially in Anaeromyces mucronatus. Cryopreservation of (mature) biomass in liquid nitrogen had the highest overall survival rates (85–100%, depending on the strain and laboratory). Additionally, preservation on agar at 39°C had surprisingly high survival rates for up to 9 months, if pieces of agar containing mature AF thalli were resuscitated. This low-cost, low-effort method could replace consecutive batch cultivation for periods of up to 6 months, while long-term preservation is best done by cryopreservation in liquid nitrogen. Regardless of the method, however, preserving several replicates (>three) of the same strain is highly advisable.</p