Discharges of past flood events based on historical river profiles

International audienceThis paper presents a case study to estimate peak discharges of extreme flood events of Neckar River in south-western Germany during the 19th century. It was carried out within the BMBF research project RIMAX (Risk Management of Extreme Flood Events). The discharge estimations were made for the flood events of 1824 and 1882 based on historical cross profiles. The 1-D model Hydrologic Engineering Centers River Analysis System (HEC-RAS) was applied with different roughness coefficients. The results are compared (i) with contemporary historical calculations and (ii) in the case of a flood event in 1824 with the discharge simulation by the water balance model LARSIM (Large Area Runoff Simulation Model). These calculations are matched by the HEC-RAS simulation based on the standard roughness coefficients

Insights into the 1968–1997 Dasht-e-Bayaz and Zirkuh earthquake sequences, eastern Iran, from calibrated relocations, InSAR and high-resolution satellite imagery

The sequence of seismicity in the Dasht-e-Bayaz and Zirkuh region of northeastern Iran, which includes 11 destructive earthquakes within a period of only 30 years, forms one of the most outstanding examples of clustered large and intermediate-magnitude seismic activity in the world.We perform a multiple-event relocation analysis, with procedures to remove systematic location bias, of 169 earthquakes, most of which occurred in the period 1968–2008, to better image the distribution of seismicity within this highly active part of Iran. The geographic locations of the clustered earthquakes were calibrated by the inclusion of phase arrivals from seismic stations at short epicentral distances, and also by matching the relative locations of the three largest events in the study to their mapped surface ruptures. The two independent calibration methods provide similar results that increase our confidence in the accuracy of the distribution of relocated epicentres. These calibrated epicentres, combined with the mapping of faults from high-resolution satellite imagery, and from an InSAR-derived constraint on fault location in one case, allow us to associate individual events with specific faults, and even with specific segments of faults, to better understand the nature of the active tectonics in this region during the past four decades. Several previous assumptions about the seismicity in this region are confirmed: (1) that the 1968 August 30 Mw 7.1 Dasht-e-Bayaz earthquake nucleated at a prominent segment boundary and left-step in the fault trace, (2) that the 1968 September 11 Mw 5.6 aftershock occurred on the Dasht-e-Bayaz fault at the eastern end of the 1968 rupture and (3) that the 1976 November 7 Mw 6.0 Qayen earthquake probably occurred on the E–W left-lateral Avash Fault. We show, in addition, that several significant events, including the 1968 September 1 and 4 (Mw 6.3 and 5.5) Ferdows earthquakes, the 1979 January 16 (Mw 6.5) and 1997 June 25 (Mw 5.9) Boznabad events and the 1979 December 7 (Mw 5.9) Kalat-e-Shur earthquake are likely to have ruptured previously unknown faults. Our improved description of the faulting involved in the 1968–1997 earthquake sequence highlights the importance of rupturing of conjugate left- and right-lateral faults in closely spaced events, or potentially even within a single earthquake, as was likely the case at the eastern end of the 1979 November 27 (Mw 7.1) Khuli-Buniabad main shock. The high level of clustered seismic activity probably results from the simultaneous activity on left- and right-lateral faults, an inherently unstable arrangement that must evolve rapidly. The combination of high-resolution satellite imagery and calibrated earthquake locations is a useful tool for investigating active tectonics, even in the absence of detailed field observations

Potential conservation of circadian clock proteins in the phylum Nematoda as revealed by bioinformatic searches

Although several circadian rhythms have been described in C. elegans, its molecular clock remains elusive. In this work we employed a novel bioinformatic approach, applying probabilistic methodologies, to search for circadian clock proteins of several of the best studied circadian model organisms of different taxa (Mus musculus, Drosophila melanogaster, Neurospora crassa, Arabidopsis thaliana and Synechoccocus elongatus) in the proteomes of C. elegans and other members of the phylum Nematoda. With this approach we found that the Nematoda contain proteins most related to the core and accessory proteins of the insect and mammalian clocks, which provide new insights into the nematode clock and the evolution of the circadian system.Fil: Romanowski, Andrés. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Bioquímicas de Buenos Aires. Fundación Instituto Leloir. Instituto de Investigaciones Bioquímicas de Buenos Aires; Argentina. Universidad Nacional de Quilmes. Departamento de Ciencia y Tecnología. Laboratorio de Cronobiología; ArgentinaFil: Garavaglia, Matías Javier. Universidad Nacional de Quilmes. Departamento de Ciencia y Tecnología. Laboratorio de Ing.genética y Biolog.molecular y Celular. Area Virus de Insectos; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Goya, María Eugenia. Universidad Nacional de Quilmes. Departamento de Ciencia y Tecnología. Laboratorio de Cronobiología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Ghiringhelli, Pablo Daniel. Universidad Nacional de Quilmes. Departamento de Ciencia y Tecnología. Laboratorio de Ing.genética y Biolog.molecular y Celular. Area Virus de Insectos; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Golombek, Diego Andres. Universidad Nacional de Quilmes. Departamento de Ciencia y Tecnología. Laboratorio de Cronobiología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

Evolution of Susceptibility to Ingested Double-Stranded RNAs in Caenorhabditis Nematodes

International audienceBACKGROUND: The nematode Caenorhabditis elegans is able to take up external double-stranded RNAs (dsRNAs) and mount an RNA interference response, leading to the inactivation of specific gene expression. The uptake of ingested dsRNAs into intestinal cells has been shown to require the SID-2 transmembrane protein in C. elegans. By contrast, C. briggsae was shown to be naturally insensitive to ingested dsRNAs, yet could be rendered sensitive by transgenesis with the C. elegans sid-2 gene. Here we aimed to elucidate the evolution of the susceptibility to external RNAi in the Caenorhabditis genus. PRINCIPAL FINDINGS: We study the sensitivity of many new species of Caenorhabditis to ingested dsRNAs matching a conserved actin gene sequence from the nematode Oscheius tipulae. We find ample variation in the Caenorhabditis genus in the ability to mount an RNAi response. We map this sensitivity onto a phylogenetic tree, and show that sensitivity or insensitivity have evolved convergently several times. We uncover several evolutionary losses in sensitivity, which may have occurred through distinct mechanisms. We could render C. remanei and C. briggsae sensitive to ingested dsRNAs by transgenesis of the Cel-sid-2 gene. We thus provide tools for RNA interference studies in these species. We also show that transgenesis by injection is possible in many Caenorhabditis species. CONCLUSIONS: The ability of animals to take up dsRNAs or to respond to them by gene inactivation is under rapid evolution in the Caenorhabditis genus. This study provides a framework and tools to use RNA interference and transgenesis in various Caenorhabditis species for further comparative and evolutionary studies

Mating dynamics in a nematode with three sexes and its evolutionary implications

Nematodes have diverse reproductive strategies, which make them ideal subjects for comparative studies to address how mating systems evolve. Here we present the sex ratios and mating dynamics of the free-living nematode Rhabditis sp. SB347, in which males, females and hermaphrodites co-exist. The three sexes are produced by both selfing and outcrossing, and females tend to appear early in a mother’s progeny. Males prefer mating with females over hermaphrodites, which our results suggest is related to the female-specific production of the sex pheromones ascr#1 and ascr#9. We discuss the parallels between this system and that of parasitic nematodes that exhibit alternation between uniparental and biparental reproduction

Phylogenetic systematisation and catalogue of paraphyletic “Rhabditidae” (Secernentea, Nematoda)

This contribution presents an alphabetical list of 38 genus taxa accepted for “Rhabditidae” along with their synonyms and a list of the valid species that have been described to date with synonyms and specific type locality and habitat. Also names of misidentified species are given as synonyms if they can be assigned to a definite species. There are 492 species names, of which 368 are accepted as valid and 124 as synonyms, four of these being nomina oblita, whereas 37 species formerly described as “Rhabditidae” are transferred to taxa in other groups. Many nomenclatural changes are proposed. New combinations are established for 64 species names, 11 species names are suggested as new synonyms, and several previous synonymies are rescinded, particularly where it has been found an underlying complex of cryptic species (e.g. in Cruznema and Litoditis). Future analyses with new isolates will show if these species are valid or not. In Rhabditis macrospiculata, Pelodera operosa and Rhabditis teroides holotype and paratype of different sex belong to different species. Four species of Agamonema and Agamonematodum could not be properly allocated generically. The three new genus taxa Buetschlinema gen. n., Litoditis gen. n. and Reiterina gen. n. are constituted, and two new species names are proposed, namely Teratorhabditis geraerti nom. nov. for Teratorhabditis dentifera apud Zeidan and Geraert (1990), nec Völk (1950) and Crustorhabditis transita nom. nov. for Rhabditis scanica apud Sudhaus (1974c), nec Allgén (1949). Of the here suppressed genus names, Phasmarhabditis Andrássy, 1976 should be mentioned as a junior synonym of Pellioditis Dougherty, 1953. As new subjective synonyms, Evaginorhabditis Sultan, Kaul & Chhabra, 1985 is regarded as synonymous of Panagrolaimus Fuchs, 1930; Lumbricicola Friedlaender, 1895 of Porrocaecum Raillet& Henry, 1912; and Macramphis Altherr, 1950 of Cooperia Ransom, 1907. A list of 35 nomina nuda is given. Type localities of most valid species are in European countries (42%). Currently, about four new species are described per year. As many more species await discovery, some suggestions for future taxonomic works are provided based on the experience of forty years. “Rhabditidae” are treated here as a paraphyletic group within the Rhabditina because Diplogastridae, Strongylida, Agfa/ Angiostomatidae, Rhabdiasidae and two other parasitic taxa arose from within this group and have sister taxa thatbelong to “Rhabditidae”. There are good reasons to accept this paraphyletic taxon because it has well-defined ecology and morphology and allows making generalisations. Here, characteristics of the bauplan of “Rhabditidae” are specified. The species are mostly inhabitants of ephemeral terrestrial habitats rich in bacteria, but some are parasites of insects, gastropods, rodents and perhaps other mammals. With focus on common ancestry and not on distinguishing characters, a new systematisation for the genus taxa in “Rhabditidae” is suggested that is based primarily on the “New York” phylogenetic tree (Kiontke et al., 2007). Of the 72 existing genus and subgenus names of “Rhabditidae”, 38 genus names are accepted on phylogenetic arguments and nine new synonyms are suggested. Most of these genus taxa are monophyletic; however, no morphological apomorphy could be demonstrated for four of them, namely Haematozoon, Pelodera, Rhabditis and Rhabditoides. “Protorhabditis” is paraphyletic. Eight genus taxa are presently monotypic, and other eight still have an uncertain position in the system (incertae sedis). Within the monophyletic Rhabditina, four species-rich clades above the genus level are proposed: Eurhabditis, Pleiorhabditis (including Rhabdiasidae), Anarhabditis and Synrhabditis (including Agfa/ Angiostomatidae), the latter two names being new. Arguments are given why contrary to traditional systematics, no special rank (category) is assigned to these and other high-rank taxa. The genus is the only exception because a genus name is part of the species name