TWISTED DWARF1 mediates the action of auxin transport inhibitors on actin cytoskeleton dynamics

Plant growth and architecture is regulated by the polar distribution of the hormone auxin. Polarity and flexibility of this process is provided by constant cycling of auxin transporter vesicles along actin filaments, coordinated by a positive auxin-actin feedback loop. Both polar auxin transport and vesicle cycling are inhibited by synthetic auxin transport inhibitors, such as 1-N-naphthylphthalamic acid (NPA), counteracting the effect of auxin; however, underlying targets and mechanisms are unclear. Using NMR, we map the NPA binding surface on the Arabidopsis thaliana ABCB chaperone TWISTED DWARF1 (TWD1). We identify ACTIN7 as a relevant, although likely indirect, TWD1 interactor, and show TWD1-dependent regulation of actin filament organization and dynamics and that TWD1 is required for NPA-mediated actin cytoskeleton remodeling. The TWD1-ACTIN7 axis controls plasma membrane presence of efflux transporters, and as a consequence act7 and twd1 share developmental and physiological phenotypes indicative of defects in auxin transport. These can be phenocopied by NPA treatment or by chemical actin (de)stabilization. We provide evidence that TWD1 determines downstream locations of auxin efflux transporters by adjusting actin filament debundling and dynamizing processes and mediating NPA action on the latter. This function appears to be evolutionary conserved since TWD1 expression in budding yeast alters actin polarization and cell polarity and provides NPA sensitivity

Early disruption of photoreceptor cell architecture and loss of vision in a humanized pig model of usher syndromes

Usher syndrome (USH) is the most common form of monogenic deaf-blindness. Loss of vision is untreatable and there are no suitable animal models for testing therapeutic strategies of the ocular constituent of USH, so far. By introducing a human mutation into the harmonin-encoding USH1C gene in pigs, we generated the first translational animal model for USH type 1 with characteristic hearing defect, vestibular dysfunction, and visual impairment. Changes in photoreceptor architecture, quantitative motion analysis, and electroretinography were characteristics of the reduced retinal virtue in USH1C pigs. Fibroblasts from USH1C pigs or USH1C patients showed significantly elongated primary cilia, confirming USH as a true and general ciliopathy. Primary cells also proved their capacity for assessing the therapeutic potential of CRISPR/Cas-mediated gene repair or gene therapy in vitro. AAV-based delivery of harmonin into the eye of USH1C pigs indicated therapeutic efficacy in vivo

Facies Distribution, Sequence Stratigraphy, Chemostratigraphy, and Diagenesis of the Middle-Late Triassic Al Aziziyah Formation, Jifarah Basin, NW Libya

This study presents the depositional facies, sequence stratigraphy, chemostratigraphy and diagenetic evolution of the Middle-Late Triassic Al Aziziyah Formation, Jifarah Basin northwest Libya. Eight measured sections were sampled and analyzed. High-resolution stable carbon isotope data were integrated with an outcrop-based sequence stratigraphic framework, to build the stratigraphic correlation, and to provide better age control of the Al Aziziyah Formation using thin section petrography, cathodoluminescence (CL) microscopy, stable isotope, and trace element analyses. The Al Aziziyah Formation was deposited on a gently sloping carbonate ramp and consists of gray limestone, dolomite, and dolomitic limestone interbedded with rare shale. The Al Aziziyah Formation is predominantly a 2nd-order sequence (5-20 m.y. duration), with shallow marine sandstone and peritidal carbonate facies restricted to southernmost sections. Seven 3rd-order sequences were identified (S1-S7) within the type section. North of the Ghryan Dome section are three mainly subtidal sequences (S8-S10) that do not correlate to the south. Shallowing upward trends define 4th-5th order parasequences, but correlating these parasequences between sections is difficult due to unconformities. The carbon isotope correlation between the Ghryan Dome and Kaf Bates sections indicates five units of δ13C depletion and enrichment (sequences 3-7). The enrichment of δ13C values in certain intervals most likely reflects local withdrawal of 12C from the ocean due to increased productivity, as indicated by the deposition of organic-rich sediment, and/or whole rock sediment composed of calcite admixed with aragonite. The depletion of δ13C is clearly associated with exposure surfaces and with shallow carbonate facies. Heavier δ18O values are related to evaporetic enrichment of 18O, whereas depletion of δ18O is related to diagenesis due to freshwater input. Al Aziziyah Formation diagenetic events indicate: 1) initial meteoric and shallow burial; 2) three types of dolomite D1, D2 and D3 were most likely formed by microbial, seepage reflux and burial processes, respectively; and 3) diagenetic cements cannot be related to the arid, mega-monsoonal climate of the Triassic and most likely formed subsequently in a humid, meteoric setting

Case studies of Late Cretaceous calcareous nannofossils

Die mittlere Kreidezeit (Aptium-Coniacium) gilt als eine der wärmsten Perioden der Erdgeschichte. Das Treibhausklima dieser erdgeschichtlichen Phase verursachte mehrmals globale ozeanische Anoxia, die als Ozeanische Anoxische Ereignisse (OAEs) bekannt sind. Das Ziel dieser Arbeit ist es mit Hilfe kalkiger Nannofossilien (kN) einen Einblick in die Paläozeanographie des Proto-Nordatlantik der späten Kreidezeit (Cenomanium-Maastrichtium) zu erlangen. Besonders deutliche Veränderungen der kN-Vergesellschaftung traten während des OAE2 im späten Cenomanium auf. Ab dem Turonium gab es im offenen Nordatlantik kN-Vergesellschaftungen, die sich von denen der europäischen Schelfmeere unterscheiden. Ein Abkühlungsereignis im späten Campanium wirkte sich hingegen kaum auf die Zusammensetzung der kN mittlerer Latituden aus. Für ein paläozeanographisches Gesamtbild wurden die Daten der vorliegenden Arbeit mit Ergebnissen früherer Studien (kN, Foraminiferen, Dinoflagellaten, Geochemie) diskutiert.In particular the mid-Cretaceous (Aptian - Coniacian) is known as one of the warmest periods in the Phanerozoic. This greenhouse climate caused repeating periods of world wide oceanic anoxia called $\underline {O}$ceanic $\underline {A}$noxic $\underline {E}$vents (OAEs). The objective of this thesis is to reconstruct the palaeoceanographic conditions in the Late Cretaceous (Cenomanian-Maastrichtian) proto-North Atlantic with the help of calcareous nannofossils (CN). Major changes of CN assemblages occurred during the Late Cenomanian OAE2. From the Turonian onwards, open oceanic CN assemblages became increasingly different relative to those from European shelf areas. The climatic cooling of the Late Campanian had only a minor influence on mid latitudinal CN assemblages. In order to improve the palaeoceanographic knowledge all data of this thesis were discussed with results of previous CN-studies and compared with data from planktic/benthic foraminifera, dinoflagellates and geochemical studies

(Appendix A) Campanian-Maastrichtian calcareous nannofossils in DSDP Hole 44-390A

The latest Cretaceous (Campanian–Maastrichtian) is characterized by several global cooling and intermittent warming events. These climatic changes influenced the palaeoceanography substantially, including changes of the deep water sources and surface water currents. One of the most prominent episodes of climatic cooling occurred during the Campanian–Maastrichtian transition. This study focuses on the palaeoclimate and palaeoceanography of the Campanian–Maastrichtian transition by analysing the calcareous nannofossils of DSDP Hole 390A (139.92–126.15 mbsf; Blake Nose). For the examination of calcareous nannofossils sixty samples were processed using the settling technique. Biostratigraphical index taxa (Broinsonia parca constricta, Uniplanarius trifidus, and Tranolithus orionatus) suggest a late Campanian age for the major part of the studied section. The calcareous nannofossils are well preserved, highly abundant (6.80 billion specimens/gram sediment) and diverse (80 species/sample). The assemblages are dominated by Prediscosphaera spp. (20.5%), Watznaueria spp. (20.3%) and Retecapsa spp. (9.8%). Cool water taxa (Ahmuellerella octoradiata, Gartnerago segmentatum, and Kamptnerius magnificus), however, appear less frequently and do not exceed more than 1%. Due to their rarity these cool water taxa do not support the existence of an intense cooling phase during the Campanian–Maastrichtian transition at DSDP Hole 390A. Around 133 mbsf several nannofossil taxa, however, show a distinctive turnover. Mesotrophic species like Discorhabdus ignotus, Zeugrhabdotus bicrescenticus and Zygodiscus exmouthiensis are abundant below 133 mbsf, whereas oligotrophic taxa like Watznaueria spp., Eiffellithus spp. and Staurolithites flavus become common above this level. These changes imply a decrease in the input of nutrients, perhaps caused by a reorganization of ocean currents (Palaeo Gulf Stream) and reduced upwelling

NMR assignments of the FKBP-type PPIase domain of FKBP42 from Arabidopsis thaliana

The Atfkbp42 gene is associated with reduced and disoriented growth of Arabidopsis thaliana. Resonance assignments are reported for the FKBP-type PPIase domain of AtFKBP42. Signal intensities reveal an additional structure element that is atypical for such FKBP domains

Calcareous nannofossils from the Paleocene-Eocene Thermal Maximum of the equatorial Atlantic

Independent geological and micropaleontological lines of evidence suggest a ~200 kyr, period of intense warming covering the Paleocene/Eocene boundary interval (PETM). It has been suggested that this warming was initiated by a massive release of methane from the continental slopes. Among other groups of organisms, calcareous nannofossils are characterized by a remarkable increase of warm water taxa during this interval. Here we report the tropical response of calcareous nannofossils to the Paleocene/Eocene interval in ODP Site 1260B (283.15-276.35 mbsf). The PETM is about 1.38 m thick (279.88-278.5 mbsf) as defined by the onset and termination of the delta13C excursion and is marked by a ~12 cm thick laminated clay layer at the start of the excursion. A 30 cm thick interval (279.75-279.45 mbsf) directly above the clay layer, is characterized by common Discoaster spp. and Coccolithus subpertusus (syn. Ericsonia subpertusus) and the first occurrences of Discoaster araneus, Rhomboaster cuspis and Tribrachiatus bramlettei. All five taxa are interpreted as proxies for warm surface waters. The increase of Discoaster spp. during the PETM is solely caused by the onset of the new species D. araneus, which is here seen as a malformed Discoaster related to specific PETM conditions. These possibly include an acidification of the surface waters and/or higher salinity. The Rhomboaster/Tribrachiatus group, which first occurs in the PETM, is also thought to be a proxy for increased salinity. The abundance of the genus Toweius, indicative for mesotrophic conditions, declines simultaneously. Discoaster abundance decreases in the later stages of the PETM, being substituted by Chiasmolithus and Campylosphaera indicating a change to more eutrophic conditions. The genus Fasciculithus, very common in the tropical Paleocene, suffered a dramatic decline in the clay layer (basal PETM), without recovering later in the Eocene. This decline and the subsequent extinction of Fasciculithus, a solid robust nannolith, are here thought to be related to a calcification crises, perhaps caused by a high CO2 concentration and an acidification of the oceans. The observed changes in the composition of the calcareous nannofossils were relatively short lived, following the course of the PETM, which was characterized by warm surface waters with possibly low pH conditions

(Appendix) Late Cretaceous calcareous nannofossils of DSDP Holes 80-549 and 80-551

he early late Cretaceous (Cenomanian–early Turonian) is thought to have been one of the warmest periods of the Phanerozoic. This period was characterised by tropical sea surface temperatures of up to 36 °C and a pole-to-equator-gradient of less than 10 °C. The subsequent Turonian–Maastrichtian was characterised by a continuous climatic cooling, peaking in the Maastrichtian. This climatic cooling and the resulting palaeoceanographic changes had an impact on planktic primary producer communities including calcareous nannofossils. In order to gain a better understanding of these Cenomanian–Maastrichtian palaeoceanographic changes, calcareous nannofossils have been studied from the proto North Atlantic (Goban Spur, DSDP Sites 549, 551). In order to see potential differences between open oceanic and shelf dwelling nannofossils, the data from Goban Spur have been compared to findings from the European shelf (northern Germany). A total of 77 samples from Goban Spur were studied for calcareous nannofossils revealing abundant (mean 6.2 billion specimens/g sediment) and highly diverse (mean 63 species/sample) nannofossil assemblages. The dominant taxa are Watznaueria spp. (mean 30.7%), Prediscosphaera spp. (mean 18.3%), Zeugrhabdotus spp. (mean 8.3%), Retecapsa spp. (mean 7.2%) and Biscutum spp. (mean 6.6%). The Cenomanian assemblages of both Goban Spur (open ocean) and Wunstorf (shelf) are characterised by elevated abundances of high fertility taxa like Biscutum spp., Zeugrhabdotus spp. and Tranolithus orionatus. Early Turonian to Maastrichtian calcareous nannofossil assemblages of Goban Spur are, however, quite different to those described from European sections. Oceanic taxa like Watznaueria spp., Retecapsa spp. and Cribrosphearella ehrenbergii dominate in Goban Spur whereas the fertility indicators Biscutum spp. and T. orionatus are more abundant in the European shelf assemblages. This shift from a homogeneous distribution of calcareous nannofossils in the Cenomanian towards a heterogeneous one in the Turonian–Maastrichtian implies a change of the ocean circulation. The “eddy ocean” system of the Cenomanian was replaced by an oceanic circulation similar to the modern one in the Turonian–Maastrichtian, caused by the cooling. The increased pole-to-equator-gradients resulted in an oceanic circulation similar to the modern one