A fragmented metazoan organellar genome

Background: Animal mitochondrial (mt) genomes are characteristically circular molecules of ~16–20 kb. Medusozoa (Cnidaria excluding Anthozoa) are exceptional in that their mt genomes are linear and sometimes subdivided into two to presumably four different molecules. In the genus Hydra, the mt genome comprises one or two mt chromosomes. Here, we present the whole mt genome sequence from the hydrozoan Hydra magnipapillata, comprising the first sequence of a fragmented metazoan mt genome encoded on two linear mt chromosomes (mt1 and mt2). Results: The H. magnipapillata mt chromosomes contain the typical metazoan set of 13 genes for respiratory proteins, the two rRNA genes and two tRNA genes. All genes are unidirectionally oriented on mt1 and mt2, and several genes overlap. The gene arrangement suggests that the two mt chromosomes originated from one linear molecule that separated between nd5 and rns. Strong correlations between the AT content of rRNA genes (rns and rnl) and the AT content of proteincoding genes among 24 cnidarian genomes imply that base composition is mainly determined by mt genome-wide constraints. We show that identical inverted terminal repeats (ITR) occur on both chromosomes; these ITR contain a partial copy or part of the 3' end of cox1 (54 bp). Additionally, both mt chromosomes possess identical oriented sequences (IOS) at the 5' and 3' ends (5' and 3' IOS) adjacent to the ITR. The 5' IOS contains trnM and non-coding sequences (119 bp), whereas the 3' IOS comprises a larger part (mt2) with a larger partial copy of cox1 (243 bp). Conclusion: ITR are also documented in the two other available medusozoan mt genomes (Aurelia aurita and Hydra oligactis). In H. magnipapillata, the arrangement of ITR and 5' IOS and 3' IOS suggest that these regions are crucial for mt DNA replication and/or transcription initiation. An analogous organization occurs in a highly fragmented ichthyosporean mt genome. With our data, we can reject a model of mt replication that has previously been proposed for Hydra. This raises new questions regarding replication mechanisms probably employed by all medusozoans, and also has general implications for the expected organization of fragmented linear mt chromosomes of other taxa

Making Digital Freemium Business Models a Success: Predicting Customers’ Lifetime Value via Initial Purchase Information

In digital freemium business models such as those of online games or social apps, a large share of overall revenue derives from a small portion of the user base. Companies operating in these and similar businesses are increasingly constructing forecasting models with which to identify potential heavy users as early as possible and create special retention measures to suit those users’ needs. In our study, we observe three digital freemium companies that sell virtual credits and investigate to what extent initial purchase information can be used to determine a given customer’s lifetime value. We find that customers represent higher future lifetime values if they (a) make a purchase early after registration, (b) spend a significant amount on their initial purchase, and (c) use credit cards to purchase credits. In addition, we see that users tend to spend increasing amounts on subsequent purchases

Enge Nachbarn. Doppel- und Mehrfachburgen in der Bronzezeit und im Mittelalter, mittelalterliche Doppelstädte – eine Einführung

The Bronze Age hillforts of Lossow and Lebus are our point of departure to discuss the phenomenon of multiple fortifications. This paper provides an introduction to the topic and summarizes the results of a Topoi workshop on this subject. Multiple fortifications are separated fortifications of two or more that are spatially proximate to one another and contemporaneous, making them a functional unit. This paper discusses the research objectiveas well as a possible classification of multiple fortifications. The research problems receivespecial focus, of which the proof of contemporaneity appears to be the most serious problem.Die bronzezeitlichen Burgwälle von Lossow und Lebus an der Oder bilden den Ausgangspunkt für eine Untersuchung des Phänomens der Mehrfachburgen. Dieser Beitrag stellt eine Einführung in das Thema und eine Zusammenfassung der Ergebnisse des Topoi-Workshops zu diesem Thema dar. Mehrfachburgen liegen dann vor, wenn mindestens zwei separate Burgen, die räumlich eng benachbart und gleichzeitig sind, eine funktionale Einheit bilden. In diesem Beitrag werden die Fragestellungen zum Thema Mehrfachburgen präzisiert, mögliche Klassifikationen, Gesichtspunkte und Interpretationen besprochen. Auch die Probleme bei der Erforschung der Mehrfachburgen werden thematisiert. Dabei erweist sich der Nachweis einer Gleichzeitigkeit mehrerer Befestigungsanlagen als größtes Hindernis

Molecular evolution of rDNA in early diverging Metazoa

Background: The cytoplasmic ribosomal small subunit (SSU, 18S) ribosomal RNA (rRNA) is the most frequently-used gene for molecular phylogenetic studies. However, information regarding its secondary structure is neglected in most phylogenetic analyses. Incorporation of this information is essential in order to apply specific rRNA evolutionary models to overcome the problem of co-evolution of paired sites, which violates the basic assumption of the independent evolution of sites made by most phylogenetic methods. Information about secondary structure also supports the process of aligning rRNA sequences across taxa. Both aspects have been shown to increase the accuracy of phylogenetic reconstructions within various taxa. Here, we explore SSU rRNA secondary structures from the three extant classes of Phylum Porifera (Grant, 1836), a pivotal, but largely unresolved taxon of early branching Metazoa. This is the first phylogenetic study of poriferan SSU rRNA data to date that includes detailed comparative secondary structure information for all three sponge classes. Results: We found base compositional and structural differences in SSU rRNA among Demospongiae, Hexactinellida (glass sponges) and Calcarea, (calcareous sponges). We showed that analyses of primary rRNA sequences, including secondary structure-specific evolutionary models, in combination with reconstruction of the evolution of unusual structural features, reveal a substantial amount of additional information. Of special note was the finding that the gene tree topologies of marine haplosclerid demosponges, which are inconsistent with the current morphology-based classification, are supported by our reconstructed evolution of secondary structure features. Therefore, these features can provide alternative support for sequencebased topologies and give insights into the evolution of the molecule itself. To encourage and acilitate the application of rRNA models in phylogenetics of early metazoans, we present 52 SSU rRNA secondary structures over the taxonomic range of Porifera in a database, along with some basic tools for relevant format-conversion. Conclusions: We demonstrated that sophisticated secondary structure analyses can increase the potential phylogenetic information of already available rDNA sequences currently accessible in databases and conclude that the importance of SSU rRNA secondary structure information for phylogenetic reconstruction is still generally underestimated, at least among certain early branching metazoans

A fragmented metazoan organellar genome: the two mitochondrial chromosomes of Hydra magnipapillata

<p>Abstract</p> <p>Background</p> <p>Animal mitochondrial (mt) genomes are characteristically circular molecules of ~16–20 kb. Medusozoa (Cnidaria excluding Anthozoa) are exceptional in that their mt genomes are linear and sometimes subdivided into two to presumably four different molecules. In the genus <it>Hydra</it>, the mt genome comprises one or two mt chromosomes. Here, we present the whole mt genome sequence from the hydrozoan <it>Hydra magnipapillata</it>, comprising the first sequence of a fragmented metazoan mt genome encoded on two linear mt chromosomes (mt1 and mt2).</p> <p>Results</p> <p>The <it>H. magnipapillata </it>mt chromosomes contain the typical metazoan set of 13 genes for respiratory proteins, the two rRNA genes and two tRNA genes. All genes are unidirectionally oriented on mt1 and mt2, and several genes overlap. The gene arrangement suggests that the two mt chromosomes originated from one linear molecule that separated between <it>nd5 </it>and <it>rns</it>. Strong correlations between the AT content of rRNA genes (<it>rns </it>and <it>rnl</it>) and the AT content of protein-coding genes among 24 cnidarian genomes imply that base composition is mainly determined by mt genome-wide constraints. We show that identical inverted terminal repeats (ITR) occur on both chromosomes; these ITR contain a partial copy or part of the 3' end of <it>cox1 </it>(54 bp). Additionally, both mt chromosomes possess identical oriented sequences (IOS) at the 5' and 3' ends (5' and 3' IOS) adjacent to the ITR. The 5' IOS contains <it>trnM </it>and non-coding sequences (119 bp), whereas the 3' IOS comprises a larger part (mt2) with a larger partial copy of <it>cox1 </it>(243 bp).</p> <p>Conclusion</p> <p>ITR are also documented in the two other available medusozoan mt genomes (<it>Aurelia aurita </it>and <it>Hydra oligactis</it>). In <it>H. magnipapillata</it>, the arrangement of ITR and 5' IOS and 3' IOS suggest that these regions are crucial for mt DNA replication and/or transcription initiation. An analogous organization occurs in a highly fragmented ichthyosporean mt genome. With our data, we can reject a model of mt replication that has previously been proposed for <it>Hydra</it>. This raises new questions regarding replication mechanisms probably employed by all medusozoans, and also has general implications for the expected organization of fragmented linear mt chromosomes of other taxa.</p

The influence of autophagy on the fruiting-body development of the filamentous fungus <i>Sordaria macrospora</i>

Autophagie ist ein Degradationsprozess der streng reguliert ist und in welchem eine eukaryotische Zelle zelleigene Organellen und Proteine bei Nährstoffmangel abbaut. Außerdem konnte gezeigt werden, dass dieser Prozess auch in verschiedene Entwicklungsprozesse involviert ist. Die molekulare Entschlüsselung der Autophagie wurde hauptsächlich in der Bäckerhefe S. cerevisiae vorgenommen. Allerdings ist Beteiligung der Autophagie an Entwicklungsprozessen in multizellulären filamentösen Ascomyceten weitestgehend unbekannt. Die Fruchtkörperentwicklung von Pilzen ist ein komplex gestalteter Differenzierungsprozess der von einem zwei-dimensionalem Pilzgeflecht ausgeht das sich zu einem dreidimensionalem Perithezium entwickelt. Die Fruchtkörperentwicklung erfordert spezifische Umgebungsbedingungen und wird durch viele entwicklungsassoziierten Genen reguliert. In dieser Studie diente der Modellorganismus Sordaria macrospora zur Untersuchung des Einflusses der Autophagie auf die Fruchtkörperentwicklung. Der coprophytische filamentöse Ascomycet S. macrospora pflanzt sich lediglich sexuell fort, was ihn ideal für die Fragestellung dieser Arbeit macht. Für diese Arbeit wurden eine Reihe konservierter Autophagie bezogener Gene auserwählt. Folgende Gene die homolog zu denen anderer Ascomyceten sind wurden isoliert: Smvps34, Smvps15, Smatg8, Smatg4, und Smjlb1. Durch die Deletion dieser Gene sollte geklärt werden wie Autophagie in die Fruchtkörperentwicklung involviert ist. Die Deletion des Phospolipidkinase Gens Smvps34 und des Proteinkinase Gens Smvps15 führte zur Lethalität von S. macrospora was durch eine Auskeimungsuntersuchung belegt wurde. Die Deletion des Gens Smatg8, welches eine autophagosomale Strukturkomponente kodiert und des Gens Smatg4, das eine Cystein-Protease kodiert, die SmATG8 prozessiert, beeinträchtigte ebenfalls die Fruchtkörperentwicklung und das vegetative Wachstum. Durch Fluoreszenzmikroskopie konnte gezeigt werden, daß SmATG8 in Autophagosomen lokalisiert und SmATG4 vorwiegend im Zytoplasma lokalisiert ist. Die Prozessierung von SmATG8 durch SmATG4 wurde ebenfalls durch Fluoreszenzmikroskopie und Western-blot Analyse bestätigt. Die heterologe Expression von Smatg8 und Smatg4 in S. cerevisiae und der Ape1 Reifungsuntersuchung zeigte, das die cDNA von Smatg8 und Smatg4 den Deletionsphenotyp der jeweiligen Hefedeletionsmutanten aufheben konnte. Somit konnte die Konservierung dieser beiden Gene innerhalb der Ascomyceten gezeigt werden. Die Blockade der Fruchtköperentwicklung wurde durch die Deletion des bZIP Transkriptionsfaktor Gens Smjlb1 verursacht genauso wie die Beeinträchtigung des vegetativen Wachstums. SmJLB1 ist im Kern lokalisiert und durch qRT-PCR Experimente wurde gezeigt, dass die Autophagiegene Smatg8 und Smatg4 durch Smjlb1 reguliert werden. Dies läßt vermuten, dass Smjlb1 in den Prozess der Autophagie involviert ist. Die Ergebnisse dieser Arbeit weisen darauf hin, dass Autophagie und Fruchtkörperentwicklung des filamentösen Pilzes S. macrospora streng miteinander verknüpft sind

Calcareous sponge genomes reveal complex evolution of alpha-carbonic anhydrases and two key biomineralization enzymes

Background: Calcium carbonate biominerals form often complex and beautiful skeletal elements, including coral exoskeletons and mollusc shells. Although the ability to generate these carbonate structures was apparently gained independently during animal evolution, it sometimes involves the same gene families. One of the best-studied of these gene families comprises the a-carbonic anhydrases (CAs), which catalyse the reversible transformation of CO2 to HCO3- and fulfill many physiological functions. Among Porifera -the oldest animal phylum with the ability to produce skeletal elements- only the class of calcareous sponges can build calcitic spicules, which are the extracellular products of specialized cells, the sclerocytes. Little is known about the molecular mechanisms of their synthesis, but inhibition studies suggest an essential role of CAs. In order to gain insight into the evolution and function of CAs in biomineralization of a basal metazoan species, we determined the diversity and expression of CAs in the calcareous sponges Sycon ciliatum and Leucosolenia complicata by means of genomic screening, RNA-Seq and RNA in situ hybridization expression analysis. Active biomineralization was located with calcein-staining. Results: We found that the CA repertoires of two calcareous sponge species are strikingly more complex than those of other sponges. By characterizing their expression patterns, we could link two CAs (one intracellular and one extracellular) to the process of calcite spicule formation in both studied species. The extracellular biomineralizing CAs seem to be of paralogous origin, a finding that advises caution against assuming functional conservation of biomineralizing genes based upon orthology assessment alone. Additionally, calcareous sponges possess acatalytic CAs related to human CAs X and XI, suggesting an ancient origin of these proteins. Phylogenetic analyses including CAs from genomes of all non-bilaterian phyla suggest multiple gene losses and duplications and presence of several CAs in the last common ancestor of metazoans. Conclusions: We identified two key biomineralization enzymes from the CA-family in calcareous sponges and propose their possible interaction in spicule formation. The complex evolutionary history of the CA family is driven by frequent gene diversification and losses. These evolutionary patterns likely facilitated the numerous events of independent recruitment of CAs into biomineralization within Metazoa

Corneal sensitivity is required for orientation in free-flying migratory bats

The exact anatomical location for an iron particle-based magnetic sense remains enigmatic in vertebrates. For mammals, findings from a cornea anaesthesia experiment in mole rats suggest that it carries the primary sensors for magnetoreception. Yet, this has never been tested in a free-ranging mammal. Here, we investigated whether intact corneal sensation is crucial for navigation in migrating Nathusius’ bats, Pipistrellus nathusii, translocated from their migratory corridor. We found that bats treated with corneal anaesthesia in both eyes flew in random directions after translocation and release, contrasting bats with a single eye treated, and the control group, which both oriented in the seasonally appropriate direction. Using a Y-maze test, we confirmed that light detection remained unaffected by topical anaesthesia. Therefore our results suggest the cornea as a possible site of magnetoreception in bats, although other conceivable effects of the anaesthetic are also explored. Furthermore, we demonstrate that the corneal based sense is of bilateral nature but can function in a single eye if necessary

Nathusius’ bats, Pipistrellus nathusii, bypass mating opportunities of their own species, but respond to foraging heterospecifics on migratory transit flights

In late summer, migratory bats of the temperate zone face the challenge of accomplishing two energy-demanding tasks almost at the same time: migration and mating. Both require information and involve search efforts, such as localizing prey or finding potential mates. In non-migrating bat species, playback studies showed that listening to vocalizations of other bats, both con-and heterospecifics, may help a recipient bat to find foraging patches and mating sites. However, we are still unaware of the degree to which migrating bats depend on con-or heterospecific vocalizations for identifying potential feeding or mating opportunities during nightly transit flights. Here, we investigated the vocal responses of Nathusius’ pipistrelle bats, Pipistrellus nathusii, to simulated feeding and courtship aggregations at a coastal migration corridor. We presented migrating bats either feeding buzzes or courtship calls of their own or a heterospecific migratory species, the common noctule, Nyctalus noctula. We expected that during migratory transit flights, simulated feeding opportunities would be particularly attractive to bats, as well as simulated mating opportunities which may indicate suitable roosts for a stopover. However, we found that when compared to the natural silence of both pre-and post-playback phases, bats called indifferently during the playback of conspecific feeding sounds, whereas P. nathusii echolocation call activity increased during simulated feeding of N. noctula. In contrast, the call activity of P. nathusii decreased during the playback of conspecific courtship calls, while no response could be detected when heterospecific call types were broadcasted. Our results suggest that while on migratory transits, P. nathusii circumnavigate conspecific mating aggregations, possibly to save time or to reduce the risks associated with social interactions where aggression due to territoriality might be expected. This avoidance behavior could be a result of optimization strategies by P. nathusii when performing long-distance migratory flights, and it could also explain the lack of a response to simulated conspecific feeding. However, the observed increase of activity in response to simulated feeding of N. noctula, suggests that P. nathusii individuals may be eavesdropping on other aerial hawking insectivorous species during migration, especially if these occupy a slightly different foraging niche

Implications for the protection of nocturnal migrants

The replacement of conventional lighting with energy‐saving light emitting diodes (LED) is a worldwide trend, yet its consequences for animals and ecosystems are poorly understood. Strictly nocturnal animals such as bats are particularly sensitive to artificial light at night (ALAN). Past studies have shown that bats, in general, respond to ALAN according to the emitted light color and that migratory bats, in particular, exhibit phototaxis in response to green light. As red and white light is frequently used in outdoor lighting, we asked how migratory bats respond to these wavelength spectra. At a major migration corridor, we recorded the presence of migrating bats based on ultrasonic recorders during 10‐min light‐on/light‐off intervals to red or warm‐white LED, interspersed with dark controls. When the red LED was switched on, we observed an increase in flight activity for Pipistrellus pygmaeus and a trend for a higher activity for Pipistrellus nathusii. As the higher flight activity of bats was not associated with increased feeding, we rule out the possibility that bats foraged at the red LED light. Instead, bats may have flown toward the red LED light source. When exposed to warm‐white LED, general flight activity at the light source did not increase, yet we observed an increased foraging activity directly at the light source compared to the dark control. Our findings highlight a response of migratory bats toward LED light that was dependent on light color. The most parsimonious explanation for the response to red LED is phototaxis and for the response to warm‐white LED foraging. Our findings call for caution in the application of red aviation lighting, particularly at wind turbines, as this light color might attract bats, leading eventually to an increased collision risk of migratory bats at wind turbines