A review of the ecomorphology of pinnotherine pea crabs (Brachyura: <i>Pinnotheridae</i>), with an updated list of symbiont-host associations

Almost all pea crab species in the subfamily Pinnotherinae (Decapoda: Brachyura: Pinnotheridae) are considered obligatory endo- or ectosymbionts, living in a mutualistic or parasitic relationship with a wide variety of invertebrate hosts, including bivalves, gastropods, echinoids, holothurians, and ascidians. While the subfamily is regarded as one of the most morphologically adapted groups of symbiotic crabs, the functionality of these adaptations in relation to their lifestyles has not been reviewed before. Available information on the ecomorphological adaptations of various pinnotherine crab species and their functionality was compiled in order to clarify their ecological diversity. These include the size, shape, and ornamentations of the carapace, the frontal appendages and mouthparts, the cheliped morphology, the ambulatory legs, and the reproductive anatomy and larval characters. The phylogenetic relevance of the adaptations is also reviewed and suggestions for future studies are made. Based on an updated list of all known pinnotherine symbiont–host associations and the available phylogenetic reconstructions, it is concluded that, due to convergent evolution, unrelated species with a similar host interaction might display the same morphological adaptations.Peer Reviewe

Validating a screening agar for linezolidresistant enterococci

Background: Linezolid is an alternative treatment option for infections with multidrug-resistant Gram-positive bacteria including vancomycin-resistant enterococci. Some countries report an increasing number of isolates with resistance to linezolid. The recent publication of the Commission for Hospital Hygiene in Germany on enterococci/VRE recommends screening for linezolid-resistant enterococci (LRE). However, a suitable selective medium or a genetic test is not available. Our aim was to establish a selective screening agar for LRE detection and validate its application with a comprehensive collection of clinical LRE and linezolid-susceptible enterococci. Methods: We decided to combine the selective power of an enterococcal screening agar with a supplementation of linezolid. Several rounds of analyses with reference, control and test strains and under varying linezolid concentrations of a wider and a smaller range were investigated and assessed. The collection of linezolid-resistant enterococcal control strains included isolates with different resistance mechanisms (23S rDNA mutations, cfr(B), optrA, poxtA). Finally, we validated our LRE screening agar with 400 samples sent to our National Reference Centre in 2019. Results: Several rounds of pre-tests and confirmatory analyses favored Enterococcosel® Agar supplemented with a concentration of 2 mg/L linezolid. A 48 h incubation period was essential for accurate identification of LRE strains. Performance of the LRE screening agar revealed a sensitivity of 96.6% and a specificity of 94.4%. Conclusions: Here we describe preparation of a suitable screening agar and a procedure to identify LRE isolates with high accuracyPeer Reviewe

Determination of a Tentative Epidemiological Cut-Off Value (ECOFF) for Dalbavancin and Enterococcus faecium

Dalbavancin is a lipoglycopeptide antibiotic that shows potent activity against Gram-positive bacteria. It circumvents vanB-type glycopeptide resistance mechanisms; however, data on the in vitro activity of dalbavancin for Enterococcus faecium (E. faecium) are scarce, and thus, no breakpoints are provided. In recent years, there has been a continuing shift from vanA-type to vanB-type vancomycin-resistance in enterococci in Central Europe. Therefore, we aimed to investigate the in vitro activity of dalbavancin against different van-genotypes, with particular focus on vanB-type E. faecium. Dalbavancin susceptibility was determined for 25 van-negative, 50 vanA-positive, and 101 vanB-positive clinical E. faecium isolates (typed by cgMLST). Epidemiological Cut-Off Values (ECOFFs) were determined using ECOFFinder. For vanB-type E. faecium isolates, dalbavancin MICs were similar to those of vancomycin-susceptible isolates reaching values no higher than 0.125 mg/L. ECOFFs for van-negative and vanB-positive isolates were 0.5 mg/l and 0.25 mg/L respectively. In contrast, E. faecium possessing vanA predominantly showed dalbavancin MICs >8 mg/L, therefore preventing the determination of an ECOFF. We demonstrated the potent in vitro activity of dalbavancin against vancomycin-susceptible and vanB-type E. faecium. On the basis of the observed wildtype distribution, a dalbavancin MIC of 0.25 mg/L can be suggested as a tentative ECOFF for E. faecium.Dalbavancin is a lipoglycopeptide antibiotic that shows potent activity against Gram-positive bacteria. It circumvents vanB-type glycopeptide resistance mechanisms; however, data on the in vitro activity of dalbavancin for Enterococcus faecium (E. faecium) are scarce, and thus, no breakpoints are provided. In recent years, there has been a continuing shift from vanA-type to vanB-type vancomycin-resistance in enterococci in Central Europe. Therefore, we aimed to investigate the in vitro activity of dalbavancin against different van-genotypes, with particular focus on vanB-type E. faecium. Dalbavancin susceptibility was determined for 25 van-negative, 50 vanA-positive, and 101 vanB-positive clinical E. faecium isolates (typed by cgMLST). Epidemiological Cut-Off Values (ECOFFs) were determined using ECOFFinder. For vanB-type E. faecium isolates, dalbavancin MICs were similar to those of vancomycin-susceptible isolates reaching values no higher than 0.125 mg/L. ECOFFs for van-negative and vanB-positive isolates were 0.5 mg/l and 0.25 mg/L respectively. In contrast, E. faecium possessing vanA predominantly showed dalbavancin MICs >8 mg/L, therefore preventing the determination of an ECOFF. We demonstrated the potent in vitro activity of dalbavancin against vancomycin-susceptible and vanB-type E. faecium. On the basis of the observed wildtype distribution, a dalbavancin MIC of 0.25 mg/L can be suggested as a tentative ECOFF for E. faecium.Peer Reviewe

Use of Imatinib in the Prevention of Heterotopic Ossification

Background: Heterotopic ossification (HO) is a common complication following orthopedic and trauma surgery, which may have substantial negative effects on the postoperative outcome. Angiogenesis appears to play a critical role in heterotopic ossification. One of the involved signaling molecules is platelet-derived growth factor (PDGF) which may be inhibited by imatinib. Questions/Purposes: Our goal was to prevent HO by pharmacologically interfering with the molecular signaling pathways involved in the developmental process. We hypothesized that by administering a proven inhibitor of PDGF expression, heterotopic bone formation may be prevented. Methods: The effect of imatinib on HO formation was studied in a murine model which reliably produces islets of HO within the soft tissue following Achilles tenotomy. The control group underwent Achilles tenotomy only. The imatinib group received imatinib mesylate. After trial completion, the limbs were harvested and scanned by micro-CT. Heterotopic bone volume was then identified and quantified. Results: The mean volume of heterotopic bone formed in the control group was 0.976mm3 compared to 0.221mm3 in the imatinib group. The volume of HO in the treatment group was reduced by 85% compared to the control group. Conclusions: The administration of imatinib was associated with a significantly reduced volume of HO. This may be due to the inhibitory effect of imatinib on the PDGF signaling pathway during development of HO. Clinical Relevance: The successful reduction of HO formation following imatinib administration has led to further insight concerning the pathogenesis of HO which in the future may lead to new clinical approaches towards the prevention of H

Linezolid Resistance Genes and Mutations among Linezolid-Susceptible Enterococcus spp.—A Loose Cannon?

The National Reference Centre for Enterococci receives an increasing number of linezolid-resistant Enterococcus isolates. Linezolid (LIN) resistance is mediated by G2576T 23S rDNA gene mutations and/or acquisition of resistance genes (cfr, optrA, poxtA). There are anecdotal reports that those resistance traits may be present in phenotypically linezolid-susceptible isolates. We aimed to determine the prevalence of LIN resistance genes and mutations in enterococci with a LIN MIC of 4 mg/L in broth microdilution (EUCAST = susceptible) isolated from German hospital patients 2019-2021. LIN MICs were additionally determined by ETEST (R) and VITEK2. Selected strains were subjected to LIN selective pressure and growth was monitored with increasing antibiotic concentrations. We received 195 isolates (LIN MIC = 4 mg/L). In total, 78/195 (40%) isolates contained either a putative resistance gene, the G2576T mutation, or a combination thereof. Very major error was high for broth microdilution. The ability to predict phenotypic resistance from genotypic profile was highest for G2576T-mediated resistance. Selection experiments revealed that, in particular, E. faecium isolates with resistance gene mutations or poxtA rapidly adapt to MICs above the clinical breakpoint. In conclusion, LIN resistance genes and mutations can be observed in phenotypically linezolid-susceptible enterococci. Those isolates may rapidly develop resistance under LIN selective pressure potentially leading to treatment failure

Vancomycin-resistant vanB-type Enterococcus faecium isolates expressing varying levels of vancomycin resistance and being highly prevalent among neonatal patients in a single ICU

Background: Vancomycin-resistant isolates of E. faecalis and E. faecium are of special concern and patients at risk of acquiring a VRE colonization/infection include also intensively-cared neonates. We describe here an ongoing high prevalence of VanB type E. faecium in a neonatal ICU hardly to identify by routine diagnostics. Methods: During a 10 months’ key period 71 E. faecium isolates including 67 vanB-type isolates from 61 patients were collected non-selectively. Vancomycin resistance was determined by different MIC methods (broth microdilution, Vitek® 2) including two Etest® protocols (McFarland 0.5/2.0. on Mueller-Hinton/Brain Heart Infusion agars). Performance of three chromogenic VRE agars to identify the vanB type outbreak VRE was evaluated (BrillianceTM VRE agar, chromIDTM VRE agar, CHROMagarTM VRE). Isolates were genotyped by SmaI- and CeuI-macrorestriction analysis in PFGE, plasmid profiling, vanB Southern hybridisations as well as MLST typing. Results: Majority of vanB isolates (n = 56, 79%) belonged to a single ST192 outbreak strain type showing an identical PFGE pattern and analyzed representative isolates revealed a chromosomal localization of a vanB2-Tn5382 cluster type. Vancomycin MICs in cation-adjusted MH broth revealed a susceptible value of ≤4 mg/L for 31 (55%) of the 56 outbreak VRE isolates. Etest® vancomycin on MH and BHI agars revealed only two vanB VRE isolates with a susceptible result; in general Etest® MIC results were about 1 to 2 doubling dilutions higher than MICs assessed in broth and values after the 48 h readout were 0.5 to 1 doubling dilutions higher for vanB VRE. Of all vanB type VRE only three, three and two isolates did not grow on BrillianceTM VRE agar, chromIDTM VRE agar and CHROMagarTM VRE, respectively. Permanent cross contamination via the patients’ surrounding appeared as a possible risk factor for permanent VRE colonization/infection. Conclusions: Low level expression of vanB resistance may complicate a proper routine diagnostics of vanB VRE and mask an ongoing high VRE prevalence. A high inoculum and growth on rich solid media showed the highest sensitivity in identifying vanB type resistance

Cohesive Elements or Phase-Field Fracture: Which Method Is Better for Dynamic Fracture Analyses?

Numerical techniques to simulate crack propagation can roughly be divided into sharp and diffuse interface methods. Two prominent approaches to quantitative dynamic fracture analysis are compared here. Specifically, an adaptive cohesive element technique and a phase-field fracture approach are applied to simulate Hopkinson bar experiments on the fracture toughness of high-performance concrete. The experimental results are validated numerically in the sense of an inverse analysis. Both methods allow predictive numerical simulations of crack growth with an a priori unknown path and determine the related material parameter in a quantitative manner. Reliability, precision, and numerical costs differ however

Malate as a key carbon source of leaf dark-respired CO2 across different environmental conditions in potato plants

Dissimilation of carbon sources during plant respiration in support of metabolic processes results in the continuous release of CO(2). The carbon isotopic composition of leaf dark-respired CO(2) (i.e. δ (13) C (R)) shows daily enrichments up to 14.8‰ under different environmental conditions. However, the reasons for this (13)C enrichment in leaf dark-respired CO(2) are not fully understood, since daily changes in δ(13)C of putative leaf respiratory carbon sources (δ (13) C (RS)) are not yet clear. Thus, we exposed potato plants (Solanum tuberosum) to different temperature and soil moisture treatments. We determined δ (13) C (R) with an in-tube incubation technique and δ (13) C (RS) with compound-specific isotope analysis during a daily cycle. The highest δ (13) C (RS) values were found in the organic acid malate under different environmental conditions, showing less negative values compared to δ (13) C (R) (up to 5.2‰) and compared to δ (13) C (RS) of soluble carbohydrates, citrate and starch (up to 8.8‰). Moreover, linear relationships between δ (13) C (R) and δ (13) C (RS) among different putative carbon sources were strongest for malate during daytime (r(2)=0.69, P≤0.001) and nighttime (r(2)=0.36, P≤0.001) under all environmental conditions. A multiple linear regression analysis revealed δ (13) C (RS) of malate as the most important carbon source influencing δ (13) C (R). Thus, our results strongly indicate malate as a key carbon source of (13)C enriched dark-respired CO(2) in potato plants, probably driven by an anapleurotic flux replenishing intermediates of the Krebs cycle

Malate as a key carbon source of leaf dark-respired CO2 across different environmental conditions in potato plants

Carbon isotope analyses revealed malate as a key carbon source of leaf dark-respired CO2 in potato plants under different temperature and soil moisture conditions during a daily cycl

Optimisation of different physical methods for control of seed-borne pathogens in organic vegetable production

In the last decade, a lot of work has been done to develop new measures or to optimise existing seed treatment methods for use in organic farming. In the field of vegetable seed protection, national research projects as well as the EU-funded project “STOVE” (“Seed Treatments for Organic Vegetable Produc-tion”) are currently carried out. Among the physical methods, hot water, humid hot air and electron treatment are being investigated. All three physical treatment methods show clear reduc-ing effects on pathogens of infested vegetable seeds. Degree of effectiveness connected with a good com-patibility depends on the treatment method and on the host-pathogen-system, but also on the cultivar and even on the seed lot