Search results for "Systematics"
showing 10 items of 6702 documents
Biotic recovery after the end-Triassic extinction event: Evidence from marine bivalves of the Neuquén Basin, Argentina
2017
We analyze the Late Triassic extinction and Early Jurassic recovery of bivalve faunas within marine environments in the Atuel River area of the Neuquén Basin, Argentina. Data were collected from a hundred samples with invertebrates in a well-exposed uppermost Triassic to lower Jurassic section in the Neuquén Basin (southern Mendoza Province, Argentina) and allow a high-resolution reconstruction of the local diversity dynamics. The nearly continuous presence of marine stenohaline major taxa such as cnidarians, rhynchonelliform brachiopods, echinoderms and cephalopods indicates normal salinity throughout. All bivalve species were identified, and each occurrence was recorded in meters above th…
Subtercola boreus gen. nov., sp. nov. and Subtercola frigoramans sp. nov., two new psychrophilic actinobacteria isolated from boreal groundwater.
2000
Psychrophilic actinobacterial isolates from permanently cold groundwater in Finland were characterized using a polyphasic approach. Growth on agar plates was observed at temperatures down to -2 degrees C, with an optimum at 15-17 degrees C, but no growth was observed at 30 degrees C. The peptidoglycan type was B2y and the characteristic diamino acid was diaminobutyric acid. The cell wall sugars of strain K265T were rhamnose, ribose, xylose and mannose and those of strain K300T were glucose, rhamnose and xylose. The polar lipids included phosphatidylglycerol, diphosphatidylglycerol, one unknown phospholipid and two glycolipids. The main whole-cell fatty acids were 12-methyltetradecanoic acid…
<p><strong>Typification of two Gandoger’s names in <em>Rhamnus </em>(Rhamnaceae)</strong></p>
2020
Gandoger’s names for Rhamnus bourgaeana and R. hispanorum (Rhamnaceae) are typified. A neotype is selected for R. bourgaeana, and a specimen preserved at M is designated as the lectotype of R. hispanorum.
Leaf domatia in the section Alaternus (Miller) DC. of the genus Rhamnus (Rhamnaceae)
1993
Anatomical and morphological study of leaves from three species of Rhamnus (R. alaternus, R. myrtifolius and R. ludovici-salvatoris) which comprise the section Alaternus (Miller) DC. from the Iberian Peninsula and Balearic Islands, have revealed the presence of domatia, which are macroscopic infundibuliform structures. Although not all the leaves of one single plant showed domatia, all the individuals of each species examined presented these structures.
Modelling the interactions of soil microbes and nematodes
2009
Abstract Six different soil food webs, assembled from a bacterium, a bacterial-feeding nematode, a fungus and a fungal-feeding nematode, were established in replicated laboratory microcosms. Glucose was supplied as the sole carbon source for the microbes. Biomasses of the organisms and the concentration of dissolved organic carbon (DOC) were measured ten times during 20 weeks. A discrete dynamic model based on the material flow between system components was fitted to the experimental data. Bacterial-based food chains were largely inactive in the absence of fungi, but mutual facilitation was observed in the systems with both fungus and bacterium. The population dynamics of a fungal-feeding …
Evidence for a symbiosis between bacteria of the genus Rhodobacter and the marine sponge Halichondria panicea : harbor also for putatively toxic bac…
1998
Halichondria panicea (Pallas) is a marine sponge, abundantly occurring in the Adriatic sea, North sea and Baltic sea. It was the aim of the present study to investigate if this sponge species harbors bacteria. Cross sections through H. panicea were taken and inspected by electron microscopy. The micrographs showed that this sponge species is colonized by bacteria in its mesohyl compartment. To identify the bacteria, polymerase chain reaction (PCR) analysis of the 16S rRNA gene segment, typical for bacteria, was performed. DNA was isolated from sponge material that had been collected near Rovinj (Adriatic Sea), Helgoland (North Sea), and Kiel (Baltic Sea) and was amplified with bacterial pri…
The GTP- and Phospholipid-Binding Protein TTD14 Regulates Trafficking of the TRPL Ion Channel in Drosophila Photoreceptor Cells
2015
Recycling of signaling proteins is a common phenomenon in diverse signaling pathways. In photoreceptors of Drosophila, light absorption by rhodopsin triggers a phospholipase Cβ-mediated opening of the ion channels transient receptor potential (TRP) and TRP-like (TRPL) and generates the visual response. The signaling proteins are located in a plasma membrane compartment called rhabdomere. The major rhodopsin (Rh1) and TRP are predominantly localized in the rhabdomere in light and darkness. In contrast, TRPL translocates between the rhabdomeral plasma membrane in the dark and a storage compartment in the cell body in the light, from where it can be recycled to the plasma membrane upon subsequ…
Climatic oscillations triggered post-Messinian speciation of Western Palearctic brown frogs (Amphibia, Anura, Ranidae)
2003
Abstract Oscillating glacial cycles over the past 2.4 million years are proposed to have had a major impact on the diversity of contemporary species communities. We used mitochondrial and nuclear DNA sequence data to infer phylogenetic relationships within Western Palearctic brown frogs and to test the influence of Pliocene and Pleistocene climatic changes on their evolution. We sequenced 1976 bp of the mitochondrial genes 16S rRNA and cytochrome b and of the nuclear rhodopsin gene for all current species and subspecies. Based on an established allozyme clock for Western Palearctic water frogs and substitution rate constancy among water frogs and brown frogs, we calibrated a molecular clock…
Support for the monophyletic origin of Gnathifera from phylogenomics
2009
The monophyletic origin of Spiralia within the metazoan tree of life is supported by many large-scale phylogenomic data. While there is now substantial molecular evidence for Lophotrochozoa being a monophyletic taxon within Spiralia, the phylogenetic affiliations of many other spiralian phyla remain unclear. Here we focus on the question of a monophyletic taxon Gnathifera, which was originally characterized by jaw morphology as comprising the taxa Rotifera, Acanthocephala and Gnathostomulida. Based on a large-scale molecular sequence dataset of 11,146 amino acid residues, we reconstructed phylogenetic trees of spiralian phyla using maximum-likelihood and Bayesian approaches. We obtain the f…
Evolutionary implications of intron-exon distribution and the properties and sequences of the RPL10A gene in eukaryotes.
2013
The RPL10A gene encodes the RPL10 protein, required for joining 40S and 60S subunits into a functional 80S ribosome. This highly conserved gene, ubiquitous across all eukaryotic super-groups, is characterized by a variable number of spliceosomal introns, present in most organisms. These properties facilitate the recognition of orthologs among distant taxa and thus comparative studies of sequences as well as the distribution and properties of introns in taxonomically distant groups of eukaryotes. The present study examined the multiple ways in which RPL10A conservation vs. sequence changes in the gene over the course of evolution, including in exons, introns, and the encoded proteins, can be…