Taxonomic re-evaluation of the Ceratobasidium-Rhizoctonia complex and Rhizoctonia butinii, a new species attacking spruce

A taxonomic re-evaluation of the Ceratobasidium-Rhizoctonia group suggests that Ceratobasidium contains only the type species C. calosporum, which deviates in micromorphological and ultrastructural characters from all other species so far included in that genus. Rhizoctonia species are compared with the type species of Ceratobasidium, Cejpomyces, Oncobasidium, Tofispora, Waitea, and Ypsilonidium. The micromorphology, ultrastructure, cellular interaction with the host, and molecular phylogeny of a Rhizoctonia species parasitic on needles and young shoots of Picea abies have been studied. The parasite has been known for a long time, but misinterpreted, and not named so far. Rhizoctonia butinii is described and compared with related species of the genus.     

Smc5/6-Mms21 Prevents and Eliminates Inappropriate Recombination Intermediates in Meiosis

Repairing broken chromosomes via joint molecule (JM) intermediates is hazardous and therefore strictly controlled in most organisms. Also in budding yeast meiosis, where production of enough crossovers via JMs is imperative, only a subset of DNA breaks are repaired via JMs, closely regulated by the ZMM pathway. The other breaks are repaired to non-crossovers, avoiding JM formation, through pathways that require the BLM/Sgs1 helicase. “Rogue” JMs that escape the ZMM pathway and BLM/Sgs1 are eliminated before metaphase by resolvases like Mus81-Mms4 to prevent chromosome nondisjunction. Here, we report the requirement of Smc5/6-Mms21 for antagonizing rogue JMs via two mechanisms; destabilizing early intermediates and resolving JMs. Elimination of the Mms21 SUMO E3-ligase domain leads to transient JM accumulation, depending on Mus81-Mms4 for resolution. Absence of Smc6 leads to persistent rogue JMs accumulation, preventing chromatin separation. We propose that the Smc5/6-Mms21 complex antagonizes toxic JMs by coordinating helicases and resolvases at D-Loops and HJs, respectively.     

A proof of principle experiment for microbeam radiation therapy at the Munich compact light source

Microbeam radiation therapy (MRT), a preclinical form of spatially fractionated radiotherapy, uses an array of microbeams of hard synchrotron X-ray radiation. Recently, compact synchrotron X-ray sources got more attention as they provide essential prerequisites for the translation of MRT into clinics while overcoming the limited access to synchrotron facilities. At the Munich compact light source (MuCLS), one of these novel compact X-ray facilities, a proof of principle experiment was conducted applying MRT to a xenograft tumor mouse model. First, subcutaneous tumors derived from the established squamous carcinoma cell line FaDu were irradiated at a conventional X-ray tube using broadbeam geometry to determine a suitable dose range for the tumor growth delay. For irradiations at the MuCLS, FaDu tumors were irradiated with broadbeam and microbeam irradiation at integral doses of either 3 Gy or 5 Gy and tumor growth delay was measured. Microbeams had a width of 50 µm and a center-to-center distance of 350 µm with peak doses of either 21 Gy or 35 Gy. A dose rate of up to 5 Gy/min was delivered to the tumor. Both doses and modalities delayed the tumor growth compared to a sham-irradiated tumor. The irradiated area and microbeam pattern were verified by staining of the DNA double-strand break marker γH2AX. This study demonstrates for the first time that MRT can be successfully performed in vivo at compact inverse Compton sources.     

A model of erythropoiesis in adults with sufficient iron availability

In this paper we present a model for erythropoiesis under the basic assumption that sufficient iron availability is guaranteed. An extension of the model including a sub-model for the iron dynamics in the body is topic of present research efforts. The model gives excellent results for a number of important situations: recovery of the red blood cell mass after blood donation, adaptation of the number of red blood cells to changes in the altitude of residence and, most important, the reaction of the body to different administration regimens of erythropoiesis stimulating agents, as for instance in the case of pre-surgical administration of Epoetin-α. The simulation results concerning the last item show that choosing an appropriate administration regimen can reduce the total amount of the administered drug considerably. The core of the model consists of structured population equations for the different cell populations which are considered. A key feature of the model is the incorporation of neocytolysis.     

Neuroprotection of medical IOP-lowering therapy

Intraocular pressure (IOP)-lowering therapy has been shown to arrest or retard the progression of optic neuropathy typical for glaucoma and can, thus, be described as neuroprotective. At present, six classes of medical therapy are employed, namely parasympathomimetics, alpha/beta-sympathomimetics, β-blockers, carbonic anhydrase inhibitors, α₂-adrenergic receptor agonists and prostaglandin analogues. For several of these substances, some experimental evidence exists of a possible neuroprotective mechanism, beyond their IOP-lowering activity. β-Blockers are involved in the up-regulation of brain-derived neurotrophic factor (BDNF) and can decrease glutamate-mediated NMDA receptor activation. Not only systemic but also topical carbonic anhydrase inhibitors are able to increase retinal blood flow. α₂-Adrenergic receptor agonists can up-regulate the formation of BDNF and anti-apoptotic factors. Prostaglandin analogues increase blood flow to the eye, possibly including the retina. To date, evidence for a neuroprotective effect independent of IOP regulation in human glaucoma is scarce and has only been shown to be likely for the α₂-adrenergic receptor agonist, brimonidine.     

Status and perspectives of neuroprotective therapies in glaucoma: The European Glaucoma Society White Paper

Glaucoma, a chronic progressive neuropathy and the most frequent cause of irreversible blindness worldwide, is commonly treated by medication or surgery aimed at lowering intraocular pressure. In view of the limited therapeutic options, the European Glaucoma Society (EGS) sponsored two Think Tank Meetings with the goal of assessing the current status and the overall perspectives for neuroprotective treatment strategies in glaucoma. The results of the meetings are summarized in this EGS White Paper.     

Untersuchungen zum Bekämpfungsrichtwert bei der Haferblattlaus,Rhopalosiphum padi (L.), an Sommergerste

In unseren Untersuchungen prüften wir den Einfluß einer Saatgutbehandlung des Maises mit Imidacloprid (Gaucho) sowohl auf die Übertragung des persistenten barley yellow dwarf virus (BYDV) als auch auf die nichtpersistenten Potyviren maize dwarf mosaic virus (MDMV) und sugarcane mosaic virus (SCMV). Dazu wurden Freiland‐ und Gewächshausversuche sowie Experimente in einer Klimakammer angestellt. Für die Virusübertragungen nutzten wir die Blattlausarten Rhopalosiphum padi L. und weniger häufig Sitobion avenae F. Im Vergleich zu S. avenae wanderte R. padi schneller von den behandelten Pflanzen ab. In Gewächshausversuchen zeigte sich, daß das SCMV nach einer Saatgutbehandlung in deutlich geringerem Umfang übertragen wurde, wenn die Inokulation bis 3 Wochen nach dem Auslegen erfolgte. Inokulationen von älteren Pflanzen ließen keine insektizide Wirkung erkennen. Ebenso ergaben Freilandversuche keinen eindeutigen Zusammenhang zwischen Saatgutbehandlung und Virusbefall. Im Falle des BYDV konnte bei einer Inokulation bis 9 Tage nach dem Auslegen durch einen Imidacloprid‐Einsatz eine signifikante Reduzierung der Übertragung erreicht werden. Spätere Inokulationen verliefen in der Regel negativ. Die Ergebnisse des Feldversuches 1992 bestätigten die im Gewächshaus gewonnenen Resultate. Im Freiland war die natürliche Besiedlung des Maises durch Blattläuse in den Parzellen mit behandeltem Saatgut deutlich vermindert. Hinzu kam eine zeitliche Verzögerung des Massenwechselgeschehens um ca. 2 Wochen.

Für eine abschließende Beurteilung von Imidacloprid sind weiterführende Untersuchungen sowohl zum Saugverhalten der Blattläuse als auch zu seiner Wirkung auf die Virusübertragung unter Einbeziehung verschiedener Sorten erforderlich.     

Noise-Induced Inner Hair Cell Ribbon Loss Disturbs Central Arc Mobilization: A Novel Molecular Paradigm for Understanding Tinnitus

Increasing evidence shows that hearing loss is a risk factor for tinnitus and hyperacusis. Although both often coincide, a causal relationship between tinnitus and hyperacusis has not been shown. Currently, tinnitus and hyperacusis are assumed to be caused by elevated responsiveness in subcortical circuits. We examined both the impact of different degrees of cochlear damage and the influence of stress priming on tinnitus induction. We used (1) a behavioral animal model for tinnitus designed to minimize stress, (2) ribbon synapses in inner hair cells (IHCs) as a measure for deafferentation, (3) the integrity of auditory brainstem responses (ABR) to detect differences in stimulus-evoked neuronal activity, (4) the expression of the activity-regulated cytoskeletal protein, Arc, to identify long-lasting changes in network activity within the basolateral amygdala (BLA), hippocampal CA1, and auditory cortex (AC), and (5) stress priming to investigate the influence of corticosteroid on trauma-induced brain responses. We observed that IHC ribbon loss (deafferentation) leads to tinnitus when ABR functions remain reduced and Arc is not mobilized in the hippocampal CA1 and AC. If, however, ABR waves are functionally restored and Arc is mobilized, tinnitus does not occur. Both central response patterns were found to be independent of a profound threshold loss and could be shifted by the corticosterone level at the time of trauma. We, therefore, discuss the findings in the context of a history of stress that can trigger either an adaptive or nonadaptive brain response following injury.     

A predictive framework to assess spatio‐temporal variability of infestations by the European spruce bark beetle

Natural disturbances are key factors for the development of forest ecosystems. In forests of central Europe and Scandinavia, the European spruce bark beetle Ips typographus is the most devastating biotic disturbance agent in Norway spruce Picea abies, but our understanding of the factors determining its spatio‐temporal dynamics is still quite limited. To quantify the drivers of bark beetle dynamics, we analyzed a survey dataset with annual resolution that covers 17 yr and 469 forest districts (10 860 km² of forest area) all over Switzerland. We used Poisson log‐normal models in a Bayesian framework to analyze the spatio‐temporal dynamics of bark beetle infestation spots at the forest district level. Bark beetle infestations increased with increasing heat sum (> 8.3°C), volume of standing Norway spruce stock, and the number of infestation spots of the previous year. Precipitation tended to slightly affect the risk of bark beetle infestations. Two major storm events further increased the spatio‐temporal variability of bark beetle infestations. Spruce abundance, storm damage and temperature are known to be important factors influencing the population dynamics of the European spruce bark beetle. Our study is the first to quantify the combined effects of spruce abundance and heat sum, whereby the heat sum turned out to be the most important and consistent predictor. Because our study area encompasses large ecological and climatological gradients, our model is likely to be applicable to Norway spruce forests in other regions of central Europe and Scandinavia.