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Hypotheses on the age and possible antiquity of the modern deep-sea fauna put forward to date almost all agree on the assumption that the deep-sea fauna is largely the result of colonisation from shallow-water environments. Here, the fossil record of the Ophiacanthidae, a modern deep-sea brittle star family with extensive fossil occurrences at shelf depths, is systematically traced against a calibrated phylogeny. Several lines of evidence suggest that the Ophiacanthidae originated and greatly diversified in the deep sea, with most extant clades having diverged by the end of the Triassic at the latest. During the Jurassic, the family temporarily invaded shelf environments, attaining relative abundances and diversities comparable to those found in coeval and modern deep-sea settings, and gradually declined in abundance subsequently, to become largely restricted to the deep-sea again. The pattern of temporary expansion to shelf environments suggested here underpins the potential of deep-sea environments to contribute significantly to shallow-water biodiversity; an aspect that has mostly been neglected so far. It is speculated that the large-scale ophiacanthid invasion of shelf environments around the Triassic- Jurassic boundary was initiated by a change from thermohaline to halothermal circulation, attenuating the thermal stratifi cation of the water column and thus providing opportunities for enhanced vertical migration of marine taxa.
The taxonomy of cyclostome bryozoans is founded on characters of the skeleton, but molecular sequence data have increasingly shown that established higher taxa are not monophyletic. Here we describe the skeletal morphology of a new species from Guadeloupe (French West Indies) with erect ramose colonies consisting of long, curved zooids that are typical of the suborder Cerioporina among living cyclostomes. However, molecular evidence from nuclear ribosomal RNA genes 18S and 28S places the new taxon in the suborder Rectangulata, where this colony-form has not been previously recorded. It nests firmly within the genus Disporella Gray, 1848, in a strongly supported clade that also includes Plagioecia patina (Lamarck, 1816) (Tubuliporina) and the sister taxa Doliocoitis cyanea Gordon & Taylor, 2001 (Rectangulata) and Favosipora rosea Gordon & Taylor, 2001 (Cerioporina). The short and robust branches of the new Guadeloupe cyclostome, here named Disporella guada Harmelin, Taylor & Waeschenbach sp. nov., are well adapted to life in shallow rocky sites exposed to severe wave action, which appear to be its exclusive habitat.
Unc-51-like kinase 4 (ULK4) is a pseudokinase that has been linked to the development of several diseases. Even though sequence motifs required for ATP binding in kinases are lacking, ULK4 still tightly binds ATP and the presence of the co-factor is required for structural stability of ULK4. Here, we present a high-resolution structure of a ULK4-ATPγS complex revealing a highly unusual ATP binding mode in which the lack of the canonical VAIK motif lysine is compensated by K39, located N-terminal to αC. Evolutionary analysis suggests that degradation of active site motifs in metazoan ULK4 has co-occurred with an ULK4-specific activation loop, which stabilizes the C helix. In addition, cellular interaction studies using BioID and biochemical validation data revealed high confidence interactors of the pseudokinase and armadillo repeat domains. Many of the identified ULK4 interaction partners were centrosomal and tubulin-associated proteins and several active kinases suggesting interesting regulatory roles for ULK4.
Die Geobotanik oder Vegetationskunde mit all ihren Teildisziplinen (u.a. Biogeographie, Pflanzensoziologie, Pflanzenökologie, Biozönologie, Floren- und Vegetationsgeschichte, Paläoökologie) ist eine der wichtigsten ganzheitlichen Zugänge zur Biologie insgesamt und die Forschungsdisziplin, welche die Aufgabe hat, zeitliche und räumliche Muster der Diversität in der Pflanzenwelt zu dokumentieren, zu analysieren, visualisieren und zu interpretieren. Die Biodiversität ist zu einem Schlüsselbegriff der ökologischen wie auch geobotanischen Forschung geworden. Die belebte Welt unseres Planeten ist von unglaublicher Vielfalt. Die Anzahl bekannter Arten an Pflanzen, Tieren und Mikroorganismen wird derzeit auf 1,4 Millionen veranschlagt, 5 bis 15 Millionen Arten werden global geschätzt. Diese Zahl lässt jedoch viele Plünderte oder Tausende von bislang noch nicht oder nur schlecht bestimmten Arten in gewissen Organismengruppen (z. B. Mikroorganismen) unberücksichtigt, welche bislang noch nicht oder nur unzureichend erfasst und beschrieben sind. Die systematische Erfassung aller Arten in international angelegten und intensiv finanzierten Arten erfassungsprogrammen ist eine notwendige Zukunftsaufgabe. Die Einbindung der Pflanzen und Mikroorganismen in die natürlichen Ökosysteme, ihr euryökes oder stenökes Standortverhalten, die Erfassung ihrer Konkurrenzkraft und ihrer Migrationsfähigkeit sind beispielsweise vordergründige Aufgaben. Neben den heute bekannten Arten hat wohl ein Mehrfaches dieser Zahl - vielleicht Millionen oder gar Milliarden - in der Vergangenheit gelebt. Sie sind heute ausgestorben, ohne je einmal lebend beschrieben worden zu sein. Nur ein kleiner Rest ist uns als Fossilien erhalten. Die Biodiversität unserer heutigen Welt muss also verstärkt kausal aus paläoökologischer Sicht beleuchtet werden. Auch die natürliche Variabilität des Klimas, die Geodiversität und die Biodiversität sind als Schätze der heutigen Ökosysteme der Erde zu betrachten. Die Rekonstruktion natürlicher klimatischer Abläufe, die genaue Erfassung der Variabilität und der Schwankungsintensität des natürlichen Klimas und der gegebenenfalls anthropogenen Klimaerwärmung sind vordergründige Aufgaben hochspezialisierter, interdisziplinärer Forschung, an denen die Geobotanik ihren zukommenden Anteil haben wird. Dies wird an einigen Beispielen verdeutlicht. Vor diesem Hintergrund sollen einige Aspekte vordergründiger Probleme des 21. Jahrhunderts aus globaler bis lokaler Perspektive diskutiert und schließlich die Rolle beleuchtet werden, welche geobotanische Forschung zu Beginn dieses neuen Jahrhunderts einnehmen könnte.
Inhibitory interneurons govern virtually all computations in neocortical circuits and are in turn controlled by neuromodulation. While a detailed understanding of the distinct marker expression, physiology, and neuromodulator responses of different interneuron types exists for rodents and recent studies have highlighted the role of specific interneurons in converting rapid neuromodulatory signals into altered sensory processing during locomotion, attention, and associative learning, it remains little understood whether similar mechanisms exist in human neocortex. Here, we use whole-cell recordings combined with agonist application, transgenic mouse lines, in situ hybridization, and unbiased clustering to directly determine these features in human layer 1 interneurons (L1-INs). Our results indicate pronounced nicotinic recruitment of all L1-INs, whereas only a small subset co-expresses the ionotropic HTR3 receptor. In addition to human specializations, we observe two comparable physiologically and genetically distinct L1-IN types in both species, together indicating conserved rapid neuromodulation of human neocortical circuits through layer 1.
The island arc of the Lesser Antilles lies at the eastern margin of the Caribbean Sea in the Western Hemisphere, and stretches from the eastern end of the islands of the Greater Antilles (at the Virgin Islands), south to a position near the continental islands of Trinidad and Tobago at the north eastern corner of South America. The islands are a part of the West Indian Islands biodiversity “hotspot” and have been available for terrestrial colonization for about the past 15 million years. This is a status report on present knowledge of the beetle faunas of these islands, which is composed of 90 families, 1210 genera, and 2612 recognized species. Many additional species are not yet identified, or are unnamed, or remain to be discovered. Reported for the first time from the Lesser Antilles are four families, 49 genera, 105 species, and 1253 new island records. The largest families are Curculionidae (588 species), Staphylinidae (389 species), Chrysomelidae (181 species), Tenebrionidae (142 species), Cerambycidae (138 species), Scarabaeidae (127 species), and Carabidae (126 species). There are differing patterns of species distributions: 154 species are probably introduced by human activities; 985 are endemic species (limited to a single island); 465 are species endemic to more than one island of the Lesser Antilles; 212 are species limited to just islands of the West Indies; and 800 are native (naturally occurring) species which also have part of their distributional range in North, Central, or South America. Most of the widely distributed beetle fauna has probably come from South America by over-water dispersal. There is no compelling evidence for a vicariance origin of any part of the beetle fauna. Earlier colonists have had more time to form endemic genera (18) and endemic species. The more widely distributed species probably represent distributions achieved in and since the Pleistocene.
Downy mildews caused by obligate biotrophic oomycetes result in severe crop losses worldwide. Among these pathogens, Pseudoperonospora cubensis and P. humuli, two closely related oomycetes, adversely affect cucurbits and hop, respectively. Discordant hypotheses concerning their taxonomic relationships have been proposed based on host–pathogen interactions and specificity evidence and gene sequences of a few individuals, but population genetics evidence supporting these scenarios is missing. Furthermore, nuclear and mitochondrial regions of both pathogens have been analyzed using microsatellites and phylogenetically informative molecular markers, but extensive comparative population genetics research has not been done. Here, we genotyped 138 current and historical herbarium specimens of those two taxa using microsatellites (SSRs). Our goals were to assess genetic diversity and spatial distribution, to infer the evolutionary history of P. cubensis and P. humuli, and to visualize genome-scale organizational relationship between both pathogens. High genetic diversity, modest gene flow, and presence of population structure, particularly in P. cubensis, were observed. When tested for cross-amplification, 20 out of 27 P. cubensis-derived gSSRs cross-amplified DNA of P. humuli individuals, but few amplified DNA of downy mildew pathogens from related genera. Collectively, our analyses provided a definite argument for the hypothesis that both pathogens are distinct species, and suggested further speciation in the P. cubensis complex.
A new family, Electrocambalidae fam. nov. of the suborder Cambalidea is described from Cretaceous Burmese amber based on two new genera, Electrocambala gen. nov. and Kachincambala gen. nov. with four new species, Electrocambala ornata gen. et sp. nov., E. cretacea gen. et sp. nov., Kachincambala muelleri gen. et sp. nov. and K. distorta gen. et sp. nov. The specimens are described combining classical light microscopy with drawings and photography, and modern micro-computed tomography (μCT). Morphological characters otherwise obscured are examined and visualized by creating volume renderings and 3D-segmentations from μCT data. Electrocambalidae fam. nov. is characterized by the following character combination: (1) a forward shift of leg pair 3, resulting in an apparently legless 3rd body ring, (2) presence of metazonital setae, and (3) extensive pilosity on the head. Although some of these characters are shared with other Juliformia they are unique in this combination. The described fossils are the oldest and first Mesozoic Spirostreptida and Cambalidea known and ca 70 million years older than previous records of the group.
Microthlaspi erraticum is widely distributed in temperate Eurasia, but restricted to Ca2+-rich habitats, predominantly on white Jurassic limestone, which is made up by calcium carbonate, with little other minerals. Thus, naturally occurring Microthlaspi erraticum individuals are confronted with a high concentration of Ca2+ ions while Mg2+ ion concentration is relatively low. As there is a competitive uptake between these two ions, adaptation to the soil condition can be expected. In this study, it was the aim to explore the genomic consequences of this adaptation by sequencing and analysing the genome of Microthlaspi erraticum. Its genome size is comparable with other diploid Brassicaceae, while more genes were predicted. Two Mg2+ transporters known to be expressed in roots were duplicated and one showed a significant degree of positive selection. It is speculated that this evolved due to the pressure to take up Mg2+ ions efficiently in the presence of an overwhelming amount of Ca2+ ions. Future studies on plants specialized on similar soils and affinity tests of the transporters are needed to provide unequivocal evidence for this hypothesis. If verified, the transporters found in this study might be useful for breeding Brassicaceae crops for higher yield on Ca2+-rich and Mg2+ -poor soils.
The ostracod genus Bennelongia De Deckker & McKenzie, 1981 is endemic to Australia and New Zealand. Extensive sampling in Western Australia (WA) revealed a high specific and largely undescribed diversity. Here, we describe seven new species belonging to the B. barangaroo lineage: B. timmsi sp. nov., B. gnamma sp. nov., B. hirsuta sp. nov., B. ivanae sp. nov., B. mcraeae sp. nov., B. scanloni sp. nov. and B. calei sp. nov., and confirm the presence of an additional species, B. dedeckkeri, in WA. For five of these eight species, we could construct molecular phylogenies and parsimonious networks based on COI sequences. We also tested for cryptic diversity and specific status of clusters with a statistical method based on the evolutionary genetic species concept, namely Birky’s 4 theta rule. The analyses support the existence of these five species and a further three cryptic species in the WA B. barangaroo lineage. The molecular evidence was particularly relevant because most species described herein have very similar morphologies and can be distinguished from each other only by the shape, size and position of the antero-ventral lapel on the right valve, and, in sexual populations, by the small differences in shape of the hemipenes and the prehensile palps in males. Four species of the WA B. barangaroo lineage occur in small temporary rock pools (gnammas) on rocky outcrops. The other four species are mainly found in soft bottomed seasonal water bodies. One of the latter species, B. scanloni sp. nov., occurs in both claypans and deeper rock pools (pit gnammas). All species, except for B. dedeckkeri, originally described from Queensland, have quite clearly delimited distributions in WA. With the seven new species described here, the genus Bennelongia now comprises 25 nominal species but several more await formal description.