The genetic architecture of susceptibility to parasites

<p>Abstract</p> <p>Background</p> <p>The antagonistic co-evolution of hosts and their parasites is considered to be a potential driving force in maintaining host genetic variation including sexual reproduction and recombination. The examination of this hypothesis calls for information about the genetic basis of host-parasite interactions – such as how many genes are involved, how big an effect these genes have and whether there is epistasis between loci. We here examine the genetic architecture of quantitative resistance in animal and plant hosts by concatenating published studies that have identified quantitative trait loci (QTL) for host resistance in animals and plants.</p> <p>Results</p> <p>Collectively, these studies show that host resistance is affected by few loci. We particularly show that additional epistatic interactions, especially between loci on different chromosomes, explain a majority of the effects. Furthermore, we find that when experiments are repeated using different host or parasite genotypes under otherwise identical conditions, the underlying genetic architecture of host resistance can vary dramatically – that is, involves different QTLs and epistatic interactions. QTLs and epistatic loci vary much less when host and parasite types remain the same but experiments are repeated in different environments.</p> <p>Conclusion</p> <p>This pattern of variability of the genetic architecture is predicted by strong interactions between genotypes and corroborates the prevalence of varying host-parasite combinations over varying environmental conditions. Moreover, epistasis is a major determinant of phenotypic variance for host resistance. Because epistasis seems to occur predominantly between, rather than within, chromosomes, segregation and chromosome number rather than recombination via cross-over should be the major elements affecting adaptive change in host resistance.</p

Between Rock and Breeze

My thesis project consists of a series of works on paper and songs about the collusion of the body and nature. I use a lens that both distorts and makes clearer the ineffable ways our bodies shake their boundaries, moving without us and within us

Präventionsbündel zur Vermeidung Gefäßkatheter-assoziierter Blutstrominfektionen in der neonatologischen Intensivmedizin Systematische Literaturanalyse international publizierter Interventionsstudien

Hintergrund: Seit dem Beginn des Einsatzes von Präventionsbündeln zur Vermeidung Gefäßkatheter-assoziierter Blutstrominfektionen steigt die Zahl der dazu durchgeführten Studien weltweit. Intensivmedizinisch behandelte Früh- und Neugeborene sind Hochrisikopatienten für nosokomiale Infektionen wie die Gefäßkatheter-assoziierte Blutstrominfektion (CABSI), weshalb die Infektionsprävention hier einen sehr hohen Stellenwert einnimmt. Zielsetzung: Ziel der hier vorgelegten Untersuchung war es, die bis 2016 verfügbaren Studien zum Einsatz von Präventionsbündeln zur Prävention von CABSI auf neonatologischen Intensivstationen systematisch auszuwerten. Methodik: In der vorliegenden Arbeit wurden insgesamt 27 zwischen 2002 und 2016 publizierte Studien zum Einfluss von Präventionsbündeln zur Prävention von CABSI bei neonatologischen Intensivpatienten eingeschlossen. Dabei handelt es sich vorwiegend um Kohortenstudien oder Studien mit einer Analyse unterbrochener Zeitserien vor und nach Intervention (Einführung der Präventionsbündel). Die wichtigsten Informationen aus den ausgewählten Studien wurden in einer einheitlich strukturierten Ergebnistabelle zusammengeführt. In acht Studien wurde die Inzidenzdichte (Ereignisse pro 1000 Patiententage) oder Inzidenzrate (Ereignisse pro 1000 Anwendungstage) von CABSI dezidiert ausgewiesen. Die Daten dieser Untergruppe aller eingeschlossenen Studien wurden in einer Metanalyse zusammengeführt. Ergebnisse: Das gepoolte relative Risiko im Vergleich der Gruppen vor und nach Einführung des Präventionsbündels lag bei 0,58 (95% Konfidenzintervall = 0,50 - 0,67) mit einer moderaten Heterogenität (I2 = 48,8%; CI 95% 0 – 74,5%). Die Studien sind heterogen in Bezug auf die Definition der Endpunkte, sowie in Bezug auf Details der implementierten Maßnahmen. Es gab Hinweise auf einen Publikationsbias zugunsten des Einsatzes von Präventionsbündeln. Insgesamt ergab die kumulative Auswertung einen statistisch und klinisch signifikanten Nutzen von Präventionsbündeln zur Prävention von CABSI bei neonatologischen Intensivpatienten. Ausblick: Leiter von neonatologischen Intensivstationen sollten anhand der 2018 aktualisierten Empfehlungen der Kommission für Krankenhaushygiene und Infektionsprävention (KRINKO) die präventiven Strategien vor Ort überprüfen. Gemeinsam mit allen beteiligten Berufsgruppen sollten Präventionsbündel definiert und nachhaltig in der klinischen Praxis implementiert werden.Background: Since the start of the assignment of preventive bundles to avoid catheter-associated bloodstream infections (CABSI) the number of conducted studies concerning this clinical topic increases worldwide. Preterm infants and neonates in neonatal intensive care face an increased risk for nosocomial infections like CABSI. In this regard, it is of outstanding importance to exercise infection prevention. Aim: The aim of this systematic analysis was to evaluate the available studies up to 2016 on the use of preventive bundles for the prevention of CABSI in neonatal intensive care units. Methods: After an extensive literature search, 27 studies published from 2002 to 2016 were included in this systematic review. Most studies are cohort studies or use an interrupted time series analysis before and after the intervention. The most important information was entered into a structured summary of findings table. 8 studies stated CABSI incidence densities (events/1000 inpatient days) and incidence rates (events/1000 utilization days) before and after intervention. The results of these studies subgroup of all eligible studies were used for a meta-analysis. Results: The implementation of preventive bundles significantly reduced the pooled relative risk of CABSI (fixed effects, Mantel-Haenszel, Rothman-Boice) at 0.58 (95% CI = 0.50–0.67) with moderate heterogeneity (I2 48.8%; 95% CI 0–74.5%). The analyzed studies showed heterogeneity in terms of endpoint definitions, details of the preventive bundle, and a publication bias favoring the use of preventive bundles was detected. Eventually, the cumulative analysis demonstrated a statistically and clinically significant benefit of preventive bundles to avoid CABSI in neonatal intensive care. Perspective: The medical leaders of neonatal intensive care units in Germany should reexamine local CABSI prevention strategies according to the recently actualized recommendations of the Commission for Hospital Hygiene and Infection Prevention (KRINKO). Preventive bundles should be defined together with all involved professional groups and sustainably implemented in daily clinical routine

A second generation genetic map of the bumblebee Bombus terrestris (Linnaeus, 1758) reveals slow genome and chromosome evolution in the Apidae.

RIGHTS : This article is licensed under the BioMed Central licence at http://www.biomedcentral.com/about/license which is similar to the 'Creative Commons Attribution Licence'. In brief you may : copy, distribute, and display the work; make derivative works; or make commercial use of the work - under the following conditions: the original author must be given credit; for any reuse or distribution, it must be made clear to others what the license terms of this work are.BACKGROUND: The bumblebee Bombus terrestris is an ecologically and economically important pollinator and has become an important biological model system. To study fundamental evolutionary questions at the genomic level, a high resolution genetic linkage map is an essential tool for analyses ranging from quantitative trait loci (QTL) mapping to genome assembly and comparative genomics. We here present a saturated linkage map and match it with the Apis mellifera genome using homologous markers. This genome-wide comparison allows insights into structural conservations and rearrangements and thus the evolution on a chromosomal level. RESULTS: The high density linkage map covers ~ 93% of the B. terrestris genome on 18 linkage groups (LGs) and has a length of 2'047 cM with an average marker distance of 4.02 cM. Based on a genome size of ~ 430 Mb, the recombination rate estimate is 4.76 cM/Mb. Sequence homologies of 242 homologous markers allowed to match 15 B. terrestris with A. mellifera LGs, five of them as composites. Comparing marker orders between both genomes we detect over 14% of the genome to be organized in synteny and 21% in rearranged blocks on the same homologous LG. CONCLUSIONS: This study demonstrates that, despite the very high recombination rates of both A. mellifera and B. terrestris and a long divergence time of about 100 million years, the genomes' genetic architecture is highly conserved. This reflects a slow genome evolution in these bees. We show that data on genome organization and conserved molecular markers can be used as a powerful tool for comparative genomics and evolutionary studies, opening up new avenues of research in the Apidae

Different forms of African cassava mosaic virus capsid protein within plants and virions

One geminiviral gene encodes the capsid protein (CP), which can appear as several bands after electrophoresis depending on virus and plant. African cassava mosaic virus-Nigeria CP in Nicotiana benthamiana, however, yielded one band (~ 30 kDa) in total protein extracts and purified virions, although its expression in yeast yielded two bands (~ 30, 32 kDa). Mass spectrometry of the complete protein and its tryptic fragments from virions is consistent with a cleaved start M1, acetylated S2, and partial phosphorylation at T12, S25 and S62. Mutants for additional potentially modified sites (N223A; C235A) were fully infectious and formed geminiparticles. Separation in triton acetic acid urea gels confirmed charge changes of the CP between plants and yeast indicating differential phosphorylation. If the CP gene alone was expressed in plants, multiple bands were observed like in yeast. A high turnover rate indicates that post-translational modifications promote CP decay probably via the ubiquitin-triggered proteasomal pathway

A Multi-Technique Study of C2H4 Adsorption on Fe3O4(001)

The adsorption/desorption of ethene (C2H4), also commonly known as ethylene, on Fe3O4(001) was studied under ultrahigh vacuum conditions using temperature programmed desorption (TPD), scanning tunneling microscopy, x-ray photoelectron spectroscopy, and density functional theory (DFT) based computations. To interpret the TPD data, we have employed a new analysis method based on equilibrium thermodynamics. C2H4 adsorbs intact at all coverages and interacts most strongly with surface defects such as antiphase domain boundaries and Fe adatoms. On the regular surface, C2H4 binds atop surface Fe sites up to a coverage of 2 molecules per (rt2xrt2)R45{\deg} unit cell, with every second Fe occupied. A desorption energy of 0.36 eV is determined by analysis of the TPD spectra at this coverage, which is approximately 0.1-0.2 eV lower than the value calculated by DFT + U with van der Waals corrections. Additional molecules are accommodated in between the Fe rows. These are stabilized by attractive interactions with the molecules adsorbed at Fe sites. The total capacity of the surface for C2H4 adsorption is found to be close to 4 molecules per (rt2xrt2)R45{\deg} unit cell