Spermidine, but not spermine, is essential for pigment pattern formation in zebrafish

Polyamines are small poly-cations essential for all cellular life. The main polyamines present in metazoans are putrescine, spermidine and spermine. Their exact functions are still largely unclear; however, they are involved in a wide variety of processes affecting cell growth, proliferation, apoptosis and aging. Here we identify idefix, a mutation in the zebrafish gene encoding the enzyme spermidine synthase, leading to a severe reduction in spermidine levels as shown by capillary electrophoresis-mass spectrometry. We show that spermidine, but not spermine, is essential for early development, organogenesis and colour pattern formation. Whereas in other vertebrates spermidine deficiency leads to very early embryonic lethality, maternally provided spermidine synthase in zebrafish is sufficient to rescue the early developmental defects. This allows us to uncouple them from events occurring later during colour patterning. Factors involved in the cellular interactions essential for colour patterning, likely targets for spermidine, are the gap junction components Cx41.8, Cx39.4, and Kir7.1, an inwardly rectifying potassium channel, all known to be regulated by polyamines. Thus, zebrafish provide a vertebrate model to study the in vivo effects of polyamines

Large-scale mapping of mutations affecting zebrafish development

BACKGROUND: Large-scale mutagenesis screens in the zebrafish employing the mutagen ENU have isolated several hundred mutant loci that represent putative developmental control genes. In order to realize the potential of such screens, systematic genetic mapping of the mutations is necessary. Here we report on a large-scale effort to map the mutations generated in mutagenesis screening at the Max Planck Institute for Developmental Biology by genome scanning with microsatellite markers. RESULTS: We have selected a set of microsatellite markers and developed methods and scoring criteria suitable for efficient, high-throughput genome scanning. We have used these methods to successfully obtain a rough map position for 319 mutant loci from the Tübingen I mutagenesis screen and subsequent screening of the mutant collection. For 277 of these the corresponding gene is not yet identified. Mapping was successful for 80 % of the tested loci. By comparing 21 mutation and gene positions of cloned mutations we have validated the correctness of our linkage group assignments and estimated the standard error of our map positions to be approximately 6 cM. CONCLUSION: By obtaining rough map positions for over 300 zebrafish loci with developmental phenotypes, we have generated a dataset that will be useful not only for cloning of the affected genes, but also to suggest allelism of mutations with similar phenotypes that will be identified in future screens. Furthermore this work validates the usefulness of our methodology for rapid, systematic and inexpensive microsatellite mapping of zebrafish mutations

Limits to reproduction and seed size-number trade-offs that shape forest dominance and future recovery

International audienceThe relationships that control seed production in trees are fundamental to understanding the evolution of forest species and their capacity to recover from increasing losses to drought, fire, and harvest. A synthesis of fecundity data from 714 species worldwide allowed us to examine hypotheses that are central to quantifying reproduction, a foundation for assessing fitness in forest trees. Four major findings emerged. First, seed production is not constrained by a strict trade-off between seed size and numbers. Instead, seed numbers vary over ten orders of magnitude, with species that invest in large seeds producing more seeds than expected from the 1:1 trade-off. Second, gymnosperms have lower seed production than angiosperms, potentially due to their extra investments in protective woody cones. Third, nutrient-demanding species, indicated by high foliar phosphorus concentrations, have low seed production. Finally, sensitivity of individual species to soil fertility varies widely, limiting the response of community seed production to fertility gradients. In combination, these findings can inform models of forest response that need to incorporate reproductive potential

Limits to reproduction and seed size-number tradeoffs that shape forest dominance and future recovery

The relationships that control seed production in trees are fundamental to understanding the evolution of forest species and their capacity to recover from increasing losses to drought, fire, and harvest. A synthesis of fecundity data from 714 species worldwide allowed us to examine hypotheses that are central to quantifying reproduction, a foundation for assessing fitness in forest trees. Four major findings emerged. First, seed production is not constrained by a strict trade-off between seed size and numbers. Instead, seed numbers vary over ten orders of magnitude, with species that invest in large seeds producing more seeds than expected from the 1:1 trade-off. Second, gymnosperms have lower seed production than angiosperms, potentially due to their extra investments in protective woody cones. Third, nutrient-demanding species, indicated by high foliar phosphorus concentrations, have low seed production. Finally, sensitivity of individual species to soil fertility varies widely, limiting the response of community seed production to fertility gradients. In combination, these findings can inform models of forest response that need to incorporate reproductive potential

Akustik im Alltag von Fledermäusen. Konzeption von Experimenten zur Thematik "Ultraschall" für einen kompetenzorientierten Physikunterricht

Der momentan an allen bayerischen allgemeinbildenden Schulen (sowie Wirtschaftsschulen und beruflichen Oberschulen) gültige Lehrplan wird derzeit im Auftrag des bayerischen Kultusministeriums vom Staatsinstitut für Schulqualität und Bildungsforschung überarbeitet. Ziel der Überarbeitung ist der neue LehrplanPLUS. Dieser will den aktiven Wissenserwerb der Schülerinnen und Schüler fördern und ihnen die Fähigkeit geben, erlerntes Wissen in den Alltag zu übertragen. So sollen prozessbezogene Kompetenzen in den Bereichen „Erkenntnisgewinn“, „“Kommunikation“ und „Bewertung“ vermittelt werden. Hierdurch sollen die Bildungsstandards der Kultusministerkonferenz im neuen bayerischen LehrplanPLUS umgesetzt werden.Im Rahmen einer Bachelorarbeit wurden Experimente und kompetenzorientierte Aufgabenstellungen zur Thematik „Ultraschall“ konzipiert für einen Physikunterricht gemäß den Vorgaben des LehrplanPLUS. In diesem Artikel wird zunächst die Grundidee der Aufbereitung der Thematik vorgestellt; exemplarisch werden fünf der insgesamt 17 Experimente und Aufgabenstellungen beschrieben

Akustik im Alltag von Fledermäusen. Konzeption von Experimenten zur Thematik "Ultraschall" für einen kompetenzorientierten Physikunterricht

Der momentan an allen bayerischen allgemeinbildenden Schulen (sowie Wirtschaftsschulen und beruflichen Oberschulen) gültige Lehrplan wird derzeit im Auftrag des bayerischen Kultusministeriums vom Staatsinstitut für Schulqualität und Bildungsforschung überarbeitet. Ziel der Überarbeitung ist der neue LehrplanPLUS. Dieser will den aktiven Wissenserwerb der Schülerinnen und Schüler fördern und ihnen die Fähigkeit geben, erlerntes Wissen in den Alltag zu übertragen. So sollen prozessbezogene Kompetenzen in den Bereichen „Erkenntnisgewinn“, „“Kommunikation“ und „Bewertung“ vermittelt werden. Hierdurch sollen die Bildungsstandards der Kultusministerkonferenz im neuen bayerischen LehrplanPLUS umgesetzt werden.Im Rahmen einer Bachelorarbeit wurden Experimente und kompetenzorientierte Aufgabenstellungen zur Thematik „Ultraschall“ konzipiert für einen Physikunterricht gemäß den Vorgaben des LehrplanPLUS. In diesem Artikel wird zunächst die Grundidee der Aufbereitung der Thematik vorgestellt; exemplarisch werden fünf der insgesamt 17 Experimente und Aufgabenstellungen beschrieben

Aqp0a Regulates Suture Stability in the Zebrafish Lens.

PurposeTo investigate the roles of Aquaporin 0a (Aqp0a) and Aqp0b in zebrafish lens development and transparency.MethodsCRISPR/Cas9 gene editing was used to generate loss-of-function deletions in zebrafish aqp0a and/or aqp0b. Wild type (WT), single mutant, and double mutant lenses were analyzed from embryonic to adult stages. Lens transparency, morphology, and growth were assessed. Immunohistochemistry was used to map protein localization as well as to assess tissue organization and distribution of cell nuclei.Resultsaqp0a-/- and/or aqp0b-/- cause embryonic cataracts with variable penetrance. While lenses of single mutants of either gene recover transparency in juveniles, double mutants consistently form dense cataracts that persist in adults, indicating partially redundant functions. Double mutants also reveal redundant Aqp0 functions in lens growth. The nucleus of WT lenses moves from the anterior pole to the lens center with age. In aqp0a-/- mutants, the nucleus fails to centralize as it does in WT or aqp0b-/- lenses, and in double mutant lenses there is no consistent lens nuclear position. In addition, the anterior sutures of aqp0a-/-, but not aqp0b-/- mutants, are unstable resulting in failure of suture maintenance at older stages and anterior polar opacity. Conclusions. Zebrafish Aqp0s have partially redundant functions, but only Aqp0a promotes suture stability, which directs the lens nucleus to centralize, failure of which results in anterior polar opacity. These studies support the hypothesis that the two Aqp0s subfunctionalized during fish evolution and that Aqp0-dependent maintenance of the anterior suture is essential for lens transparency

Improved effectiveness of performance monitoring in amateur instrumental musicians

This research was supported by a Wellcome Trust Biomedical Vacation Scholarship to Anahit Mkrtchian and a Vacation Scholarship from the Institute for Behavioural and Neural Sciences to Nayantara Kansal.Here we report a cross-sectional study investigating the influence of instrumental music practice on the ability to monitor for and respond to processing conflicts and performance errors. Behavioural and electrophysiological indicators of response monitoring in amateur musicians with various skill levels were collected using simple conflict tasks. The results show that instrumental musicians are better able than non-musicians to detect conflicts and errors as indicated by systematic increases in the amplitude of the error-related negativity and the N200 with increasing levels of instrumental practice. Also, high levels of musical training were associated with more efficient and less reactive responses after experience of conflicts and errors as indicated by reduced post-error interference and post-conflict processing adjustments. Together, the present findings suggest that playing a musical instrument might improve the ability to monitor our behavior and adjust our responses effectively when needed. As these processes are amongst the first to be affected by cognitive aging, our evidence could promote musical activity as a realistic intervention to slow or even prevent age-related decline in frontal cortex mediated executive functioning.Publisher PDFPeer reviewe