Do asymptomatic STEC-long-term carriers need to be isolated or decolonized? New evidence from a community case study and concepts in favor of an individualized strategy

Asymptomatic long-term carriers of Shigatoxin producing Escherichia coli (STEC) are regarded as potential source of STEC-transmission. The prevention of outbreaks via onward spread of STEC is a public health priority. Accordingly, health authorities are imposing far-reaching restrictions on asymptomatic STEC carriers in many countries. Various STEC strains may cause severe hemorrhagic colitis complicated by life-threatening hemolytic uremic syndrome (HUS), while many endemic strains have never been associated with HUS. Even though antibiotics are generally discouraged in acute diarrheal STEC infection, decolonization with short-course azithromycin appears effective and safe in long-term shedders of various pathogenic strains. However, most endemic STEC-strains have a low pathogenicity and would most likely neither warrant antibiotic decolonization therapy nor justify social exclusion policies. A risk-adapted individualized strategy might strongly attenuate the socio-economic burden and has recently been proposed by national health authorities in some European countries. This, however, mandates clarification of strain-specific pathogenicity, of the risk of human-to-human infection as well as scientific evidence of social restrictions. Moreover, placebo-controlled prospective interventions on efficacy and safety of, e.g., azithromycin for decolonization in asymptomatic long-term STEC-carriers are reasonable. In the present community case study, we report new observations in long-term shedding of various STEC strains and review the current evidence in favor of risk-adjusted concepts

Mitochondrial introgression, color pattern variation, and severe demographic bottlenecks in three species of Malagasy poison frogs, genus Mantella

Madagascar is a biodiversity hotspot particularly rich in amphibian diversity and only a few charismatic Malagasy amphibians have been investigated for their population-level differentiation. The Mantella madagascariensis group is composed of two rainforest and three swamp forest species of poison frogs. We first confirm the monophyly of this clade using DNA sequences of three nuclear and four mitochondrial genes, and subsequently investigate the population genetic differentiation and demography of the swamp forest species using one mitochondrial, two nuclear and a set of nine microsatellite markers. Our results confirm the occurrence of two main mitochondrial lineages, one dominated by Mantella aurantiaca (a grouping supported also by our microsatellite-based tree) and the other by Mantella crocea + Mantella milotympanum. These two main lineages probably reflect an older divergence in swamp Mantella. Widespread mitochondrial introgression suggests a fairly common occurrence of inter-lineage gene flow. However, nuclear admixture seems to play only a limited role in this group, and the analyses of the RAG-1 marker points to a predominant incomplete lineage sorting scenario between all five species of the group, which probably diverged relatively recently. Our demographic analyses show a common, severe and recent demographic contraction, inferred to be in temporal coincidence with the massive deforestation events that took place in the past 1000 years. Current data do not allow to conclusively delimit independent evolutionary units in these frogs, and we therefore refrain to suggest any taxonomic changes

New insights on phylogeography and distribution of painted frogs (Discoglossus) in northern Africa and the Iberian Peninsula

Painted frogs (Discoglossus) contain five to six species of Western Palearctic anurans that are mainly distributed in allopatry. We here provide the first comprehensive assessment of the phylogeography of the Moroccan species D. scovazzi and geographically characterize its contact zone with D. pictus in Eastern Morocco. Discoglossus scovazzi shows, in general, a weak phylogeographic structure across Morocco on the basis of mitochondrial DNA sequences of the cytochrome b gene, with only populations centered in the Atlas Mountains characterized by the presence of slightly divergent haplotypes. In eastern Morocco, all populations east of the Moulouya River were clearly assignable to D. pictus. This species was also found along the Mediterranean coast west of the Moulouya, in the cities of Nador and Melilla, suggesting that not the river itself but the wide arid valley extending along much of the river (except close to the estuary) acts as a possible distributional barrier to these frogs. No sympatry of D. scovazzi with D. pictus was observed, and all specimens were concordantly assigned to either species by DNA sequences of cytochrome b and of the nuclear marker RAG1. Species distribution models of the two taxa show largely overlapping areas of suitable habitat, and the two species’ niches are significantly more similar than would be expected given the underlying environmental differences between the regions in which they occur. Comparative data are also presented from the southern Iberian contact zone of D. galganoi galganoi and D. g. jeanneae. These taxa showed less clear-cut distributional borders, extensively shared RAG1 haplotypes, and had instances of sympatric occurrence on the basis of cytochrome b haplotypes, in agreement with the hypothesis of a yet incomplete speciation. In this wide contact zone area we found mitochondrial sequences containing double peaks in electropherograms, suggesting nuclear pseudogenes or (less likely) heteroplasmy, possibly related to the ongoing admixture among the lineagesPeer reviewe

The necessity of genetic screening for proper management of captive crocodile populations based on the examples of Crocodylus suchus and C. mindorensis

Based on sequences of mitochondrial and nuclear genes, we report on a screening of 11 presumed Nile crocodiles from various European zoos, of which five (from four facilities) turned out to be western Nile crocodiles, Crocodylus suchus, the recently resurrected name applied to the western genetic lineage of Crocodylus niloticus sensu loto. We also provide evidence for a pure species-level genetic background of six additional Crocodylus mindorensis from a European zoo facility, a species that is known to hybridise with Crocodylus porosus. Our results are based on a limited number of genetic markers and thus might miss backcrossed hybrid specimens, but they provide an important basis for the establishment of conservation breeding programmes, already in place for C. mindorensis and contemplated for C. suchus. We found evidence for possible genetic admixture between C. suchus and C. niloticus in a specimen found in Lebanon, possibly representing a released captive-bred hybrid. We reiterate the need for such basic genetic screening especially in morphologically cryptic and poorly studied species in the context of ex-situ conservation breeding, to avoid erroneous species identification and overlooking of unknown evolutionary lineages

From species divergence to population structure: A multimarker approach on the most basal lineage of Salamandridae, the spectacled salamanders (genus Salamandrina) from Italy

Hauswaldt JS, Angelini C, Gehara M, Benavides E, Polok A, Steinfartz S. From species divergence to population structure: A multimarker approach on the most basal lineage of Salamandridae, the spectacled salamanders (genus Salamandrina) from Italy. Molecular Phylogenetics and Evolution. 2014;70:1-12.The Apennine Peninsula is one of Europe's main glacial refugial areas and harbors a large number of lineages and species. Here, a pattern of higher genetic diversity in the south compared to that of the north is characteristic of most vertebrates; however, most studies that have produced these results have relied only on inferences based on mitochondrial DNA. The spectacled salamanders (genus Salamandrina) are endemic to the Apennine Peninsula and have diverged into two sibling species: S. terdigitata (in the south) and S. perspicillata (in the north), presumably in the late Miocene or early Pliocene. By sequencing one mitochondrial (cytb) and two nuclear genes (RAG1 and POMC) and genotyping 10 microsatellite loci, we traced the evolution of these sibling species from their divergence to their contemporary population structure at a fine scale. Using a multilocus coalescent-based approach, we estimated the temporal divergence of both species at approximately 2.25 mya (million years ago), which, hence, is much younger than previous estimates. The classical pattern of high genetic diversity in the south and lower diversity in the north was confirmed only for some markers, and the demographic histories of the two species differed substantially. Whereas S. perspicillata (north) expanded from a single major refugium in the center of the Apennine Peninsula, populations of S. terdigitata (south) persisted through cooler periods in multiple refugia. Further, the fine-scale population genetic structure of 16 S. perspicillata populations revealed significant genetic differentiation, even across short geographic distances. The results of our study stress that for a better understanding of phylogeographic patterns and past demographic processes, both mitochondria] and multiple nuclear loci should be analyzed to avoid gene-specific, and possibly biased results. (C) 2013 Elsevier Inc. All rights reserved

First microsatellite loci for spectacled salamanders (Salamandrina perspicillata and S. terdigitata) endemic to the Apennine peninsula

Hauswaldt JS, Polok A, Angelini C, Steinfartz S. First microsatellite loci for spectacled salamanders (Salamandrina perspicillata and S. terdigitata) endemic to the Apennine peninsula. Conservation Genetics Resources. 2012;4(2):399-402.We describe ten microsatellite loci isolated for the oldest lineage of extant salamandrids, the spectacled salamanders (Salamandrina), a genus of terrestrial salamanders endemic to the Apennine peninsula (Italy). Primers were tested in 24 individuals per species, the northern species (Salamandrina perspicillata) and the southern species (Salamandrina terdigitata). All loci were polymorphic in S. perspicillata with number of alleles ranging from three to eleven and observed heterozygosity ranging from 0.25 to 0.83. In S. terdigitata eight loci were polymorphic, the number of alleles ranged from two to nine, and observed heterozygosity from 0.04 to 0.92

Design and analysis of control systems: case studies

This book provides methods to unify different approaches to tackle stability theory problems. In particular, it presents a methodology to blend approaches obtained from measure theory with methods obtained from Lyapunov’s stability theory. The author summarizes recent works on how different analysis/design methods can be unified and employed for systems that do not belong to either of domains of validity