360 research outputs found
The genome of Romanomermis culicivorax:revealing fundamental changes in the core developmental genetic toolkit in Nematoda
Background: The genetics of development in the nematode Caenorhabditis elegans has been described in exquisite detail. The phylum Nematoda has two classes: Chromadorea (which includes C. elegans) and the Enoplea. While the development of many chromadorean species resembles closely that of C. elegans, enoplean nematodes show markedly different patterns of early cell division and cell fate assignment. Embryogenesis of the enoplean Romanomermis culicivorax has been studied in detail, but the genetic circuitry underpinning development in this species has not been explored. Results: We generated a draft genome for R. culicivorax and compared its gene content with that of C. elegans, a second enoplean, the vertebrate parasite Trichinella spiralis, and a representative arthropod, Tribolium castaneum. This comparison revealed that R. culicivorax has retained components of the conserved ecdysozoan developmental gene toolkit lost in C. elegans. T. spiralis has independently lost even more of this toolkit than has C. elegans. However, the C. elegans toolkit is not simply depauperate, as many novel genes essential for embryogenesis in C. elegans are not found in, or have only extremely divergent homologues in R. culicivorax and T. spiralis. Our data imply fundamental differences in the genetic programmes not only for early cell specification but also others such as vulva formation and sex determination. Conclusions: Despite the apparent morphological conservatism, major differences in the molecular logic of development have evolved within the phylum Nematoda. R. culicivorax serves as a tractable system to contrast C. elegans and understand how divergent genomic and thus regulatory backgrounds nevertheless generate a conserved phenotype. The R. culicivorax draft genome will promote use of this species as a research model
Methods for the automatic recording of bird calls and songs in field ornithology
Der gegenwärtige Kenntnisstand über automatisierte Methoden
zur akustischen Erfassung von Rufen und Gesängen von
Vögeln wird dargelegt. Die Grundlage für eine automatisierte
Erfassung bilden Langzeitaufzeichnungen. Es wird der
Frage nachgegangen, inwiefern Tonaufzeichnungen für eine
qualitative und auch quantitative Analyse von Vogelbeständen
geeignet sind. Spezielles Augenmerk wird autonomen Aufzeichnungsmethoden
und der Auswertung von Langzeitaufzeichnungen
unter Nutzung von Algorithmen der akustischen
Mustererkennung gewidmet. Sinnvolle Einsatzszenarien für
automatisierte Methoden im Rahmen avifaunistischer Feldforschung
sind die Erfassung des nächtlichen Vogelzuges, die
Erfassung nachtaktiver Brutvogelarten und die Datenerhebung
in Kernzonen von Schutzgebieten.This review presents our current knowledge on automated methods for acoustic recording of calls and songs of birds. Acoustic
long-term recordings can serve as a basis for an automated bird census. We stress the question of whether sound recordings
are suitable for qualitative and quantitative analysis of bird populations. Special attention is devoted to autonomous recording
methods and the evaluation of long-term recordings by use of acoustic pattern recognition algorithms. Realistic scenarios for
the use of automated methods in field ornithology we see in the investigation of nocturnal bird migration, the census of
nocturnal bird species, and data collection in core areas of nature reserves
Mutations in NNT encoding nicotinamide nucleotide transhydrogenase cause familial glucocorticoid deficiency
This work has been supported by the Medical Research Council UK (New Investigator Research Grant G0801265 to L.A.M., Clinical Research Training Fellowship Grant G0901980 to C.R.H. and Project Grant G0700767 to P.J.K.)
Digitales Video
Elektronische Dokumente werden immer häufiger durch zeitbasierte Medienobjekte wie z.B. Videoclips angereichert. Selbst im WWW sind mittlerweile Videos komfortabel durch Streamingtechnologie verfügbar. Rechnergestützte Videoschnittlösungen und Telekonferenzsysteme sind zudem weitere Einsatzfelder für digitale Videosequenzen. Aufgrund beschränkter Ressourcen ist Kompression aber weiterhin ein entscheidender Einsatzfaktor
The Song of the Sirens
In Homer’s account of the adventurous journey of Odysseus, the song of the sirens was so appealing and tempting that it lured sailors to their deaths. Warned by the goddess Kirke, Odysseus overcame the trap by plugging his crew’s ears with wax. An archaeo-acoustical research expedition undertaken by members of Humboldt University Berlin made sound propagation experiments at the supposedly historical scene at the Galli Islands where it’s said that the sirens originally sung. At the site we broadcasted both synthetic signals and natural voices via loudspeakers in the direction Odysseus most probably should have approached the Siren’s island. Subjective listening as well as objective acoustic analysis of the recorded signals revealed evidence for a combination of site-specific acoustic effects, which may explain the nature and origin of the song of the sirens in Homer. The local arrangement of the three islands deforms the acoustic signals by amplification and by changes in timbre. Two female singers from the Berlin State Opera were asked to sing differently pitched musical intervals to be tested in the Li Galli environment. The experiment evinced that the first overtones (octave, fifth, and fourths) would be merged by the echo of the rocks; yet when singing pure thirds and less consonant intervals, which yield higher orders in the overtone series, the voices appear recognisable as being two. As a result, and particularly because Homer stresses the number of exactly two sirens several times, the evidence of our research supports the musicological theory for a rather early existence of enharmonic tunings and most prominently a two-part polyphonic singing of Greek songs. Given that the rocky formation of the Galli Islands most likely didn’t change during the geological tick of just 2,700 years, we conclude that there has been a real acoustic basis for the myth reported by Homer and that a “song of the Sirens”, most probably based on natural voices, was transformed by the particular acoustic conditions of the landscape in such a way that signals were amplified and sent out in one concrete direction. Based on these results, we continue to discuss further leading acoustic theories that offer new insights into the mythology and which were essential to motivate our expedition in the first place. After all, the question remains open what kind of beings the first emitters of the song might have been
Etablierung und Optimierung einer PCR-basierten Methode zur Detektion von genetischen Veränderungen im PDPK1-Gen bei Kindern mit intrauterinem und postnatalem Kleinwuchs
Untersuchungen zeigen, dass Kinder mit einem Geburtsgewicht und/oder einer Geburtslänge unterhalb der 3. Perzentile der populationsspezifischen Norm (SGA) u. a. ein erhöhtes Risiko für kardiovaskuläre und metabolische Krankheitsbilder haben. Mausembryonen mit einer Funktionseinschränkung der PDPK1 sind überlebensfähig, haben aber ein um 40-50 Prozent vermindertes Längenwachstum als Wurfgeschwister.
Im Rahmen dieser Arbeit wurden bei 111 SGA-Kindern mit nachgewiesenem proportioniertem Kleinwuchs ohne Aufholwachstum, dem Phänotyp einer IGF1 Resistenz und einem im Vorfeld ausgeschlossenem IGF1 Rezeptordefekt die Nukleotidabfolge der kodierenden Bereiche der PDPK1 untersucht. Dabei konnte für die Exons 1, 3 und 4, sowie 7 bis 14 eine PCR-Reaktion etabliert werden, wobei das PCR Produkt mittels dHPLC und/oder Sequenzierung untersucht wurde. Methodische Probleme ergaben sich aus der Existenz eines Pseudogen, sodass für die Exons 2-10 eine Vor-PCR etabliert werden musste. Aufgrund der Länge des homologen Bereichs und der damit verbundenen relativ weiten Entfernung zu spezifischen Primerbindungsstellen konnten nicht alle Exons mit ausreichender Spezifität amplifiziert werden. Es wurden insgesamt 6 verschiedene intronische Varianten bei 11 Patienten nachgewiesen, welche bisher in der Literatur noch nicht beschrieben worden sind. Ob oder in wie weit diese Sequenzvarianten eine Rolle bei der Entwicklung des SGA-Phänotyps der Kinder gespielt haben, ist aufgrund der Lokalisation außerhalb der Exons bzw. wegen ihres seltenen Auftretens auch in der Gesundpopulation unklar. Möglich wären z. B. Wechselwirkungen mit Promoterregionen und eine daraufhin eingeschränkte Funktion der Aktivität der PDPK1. Weiterführende methodische Optimierungen oder alternative Analysetechniken sowie die Untersuchung größerer Patientenkollektive mit geeigneten Kontrollgruppen werden helfen, die Relevanz der PDPK1 bei der Ausprägung eines isolierten Minderwuchses bei Patienten mit IGF1-Resistenz zu etablieren
Automatic acoustic detection of birds through deep learning : the first bird audio detection challenge
Assessing the presence and abundance of birds is important for monitoring specific species as well as overall ecosystem health. Many birds are most readily detected by their sounds, and thus passive acoustic monitoring is highly appropriate. Yet acoustic monitoring is often held back by practical limitations such as the need for manual configuration, reliance on example sound libraries, low accuracy, low robustness, and limited ability to generalise to novel acoustic conditions.
Here we report outcomes from a collaborative data challenge. We present new acoustic monitoring datasets, summarise the machine learning techniques proposed by challenge teams, conduct detailed performance evaluation, and discuss how such approaches to detection can be integrated into remote monitoring projects.
Multiple methods were able to attain performance of around 88% AUC (area under the ROC curve), much higher performance than previous general‐purpose methods.
With modern machine learning including deep learning, general‐purpose acoustic bird detection can achieve very high retrieval rates in remote monitoring data ̶ with no manual recalibration, and no pre‐training of the detector for the target species or the acoustic conditions in the target environment.</ol
Structurally rich dry grasslands – Potential stepping stones for bats in open farmland
Agricultural intensification has caused decrease and fragmentation of European semi-natural dry grasslands. While a high biodiversity value of dry grasslands is acknowledged for plants and insects, locally and on landscape level, their relevance for mobile species, such as bats, is unknown. Here we investigate the use of dry grassland fragments by bats in an agriculturally intensified region in Germany and evaluate local and landscape factors influencing bat activity and assemblages. Specifically, we predicted that a combination of local dry grassland structural richness and landscape features as well as their interactions affect bat activity and foraging above dry grasslands. We also expected that these features influence compositions of local bat assemblages. We repeatedly sampled at 12 dry grassland plots with acoustic monitoring and assessed activity and foraging of bat species/sonotypes, which we grouped into guilds known for foraging in open land, at vegetation edges and in narrow spaces. We determined structural richness of the dry grassland plots in field and derived landscape features from digital landscape data. A relatively high proportion of bat species/sonotypes used dry grasslands regularly. The edge space foragers responded positively to higher local structural richness. Their dry grassland use increased when surrounding forests and woody features were less available, but they foraged more on dry grasslands closer to water bodies. Narrow space bat activity on dry grasslands decreased with less landscape connectivity. Open and narrow space foragers responded to local structural richness only in landscape context. For all bat guilds we found increased use of structurally richer dry grasslands when there was more open farmland in the surroundings. This was also the case for edge space foragers, when landscapes were more homogeneous. Lastly, with increasing structural richness, bat assemblages were more dominated by edge space foragers. We show the importance of European dry grassland fragments for the highly mobile group of bats under certain local structural and landscape compositional conditions. Our results underline the value of heterogeneous dry grassland fragments as potential stepping stones in intensively used farmland areas and contribute to evidence based decision making in dry grassland management and bat conservation
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