Developmental refinement of hair cell synapses tightens the coupling of Ca2+ influx to exocytosis

Cochlear inner hair cells (IHCs) develop from pre‐sensory pacemaker to sound transducer. Here, we report that this involves changes in structure and function of the ribbon synapses between IHCs and spiral ganglion neurons (SGNs) around hearing onset in mice. As synapses matured they changed from holding several small presynaptic active zones (AZs) and apposed postsynaptic densities (PSDs) to one large AZ/PSD complex per SGN bouton. After the onset of hearing (i) IHCs had fewer and larger ribbons; (ii) Ca_V1.3 channels formed stripe‐like clusters rather than the smaller and round clusters at immature AZs; (iii) extrasynaptic Ca_V1.3‐channels were selectively reduced, (iv) the intrinsic Ca²⁺ dependence of fast exocytosis probed by Ca²⁺ uncaging remained unchanged but (v) the apparent Ca²⁺ dependence of exocytosis linearized, when assessed by progressive dihydropyridine block of Ca²⁺ influx. Biophysical modeling of exocytosis at mature and immature AZ topographies suggests that Ca²⁺ influx through an individual channel dominates the [Ca²⁺] driving exocytosis at each mature release site. We conclude that IHC synapses undergo major developmental refinements, resulting in tighter spatial coupling between Ca²⁺ influx and exocytosis.     

Can monitoring data contribute to the biodiversity-ecosystem function debate? Evaluating data from a highly dynamic ecosystem

One of the most controversially discussed topics in current biodiversity-ecosystem function research is the transfer of results from experimental and theoretical studies to natural ecosystems. At the same time, monitoring data on biodiversity are requested as key indicators for the state of an ecosystem in most environmental evaluation frameworks. We analyse two monitoring data sets comprising information on abundance and biomass of macrozoobenthos communities in the German Wadden Sea in order to evaluate how much information monitoring data on biodiversity provide concerning ecosystem functioning and what implications this information (or the lack thereof) has for future monitoring programmes. Our results show a positive correlation between number of species of macrozoobenthos and its standing stock. Despite differences in overall biomass and individual size in different functional groups, this correlation remained consistent for different feeding guilds and therefore is likely to be independent of certain species traits. Moreover, functional turnover analyses indicate that increasing species richness is needed to maintain biomass levels over increasing periods of time. Whereas our data thus corroborate predictions from theory, we could not determine any causal relationships, because monitoring data commonly include only vague proxies for very few functional parameters, in our case standing biomass as a proxy for production. As to the use of diversity as an indicator for ecosystem functioning, we advise that management decisions are to be based on verified causal relationships and therefore strongly suggest the general incorporation of unambiguous proxies for functional parameters in the measuring campaigns of monitoring programmes.     

Uncoupling of the dynamics of host–pathogen interaction uncovers new mechanisms of viral interferon antagonism at the single-cell level

Antiviral defence in mammals is mediated through type-I interferons (IFNs). Viruses antagonise this process through expression of IFN antagonist proteins (IAPs). Understanding and modelling of viral escape mechanisms and the dynamics of IAP action has the potential to facilitate the development of specific and safe drugs. Here, we describe the dynamics of interference by selected viral IAPs, NS1 from Influenza A virus and NS3/4A from Hepatitis C virus. We used Tet-inducible IAP gene expression to uncouple this process from virus-driven dynamics. Stochastic activation of the IFN-β gene required the use of single-cell live imaging to define the efficacy of the inhibitors during the virus-induced signalling processes. We found significant correlation between the onset of IAP expression and halted IFN-β expression in cells where IFN-β induction had already occurred. These data indicate that IAPs not only prevent antiviral signalling prior to IFN-β induction, but can also stop the antiviral response even after it has been activated. We found reduced NF-κB activation to be the underlying mechanism by which activated IFN expression can be blocked. This work demonstrates a new mechanism by which viruses can antagonise the IFN response.     

Long-Term Performance of Modern Coronary Sinus Leads in Cardiac Resynchronization Therapy

Background

Cardiac resynchronization therapy (CRT) has become an important pillar of contemporary heart failure therapy. The efficacy of CRT, however, critically relies on proper LV lead placement and performance, which is why data regarding the long-term performance of CS leads are of considerable interest. Available studies are limited by a restricted variety of lead vendors, earlier lead models and / or very short follow-up periods. In the current study, we therefore investigated the long-term performance of modern LV leads in a large "real world" cohort of patients undergoing CRT implantation.

Methods and Results

All 193 patients who had successfullyundergone CRT implantation at the University Hospital Zurich between September 2003 and January 2010 were included in the study. An overall stable course of stimulation energy was observed over time; neither ischemic etiology, lead configuration, or severely reduced EF had an influence on the evolution of energy thresholds over time. Interestingly, patients with a high energy threshold at baseline experienced a significant reduction during follow-up. In contrast, a significant drop in impedance was seen following implantation, followed by a steady course for the rest of the observation period. Only 15 patients (9.7%) showed an impedance > 1000 Ohm at any time during their follow-up. Seven lead dislocations were observed during follow up.

Conclusion

The current comprehensive analysis of long-term performance of modern coronary sinus leads demonstrates excellent stability, performance and safety. These data may have important implications for physicians involved in biventricular pacemaker implantations and in the follow-up care of these patients.     

Multiple Protein Biomarker Assessment for Recombinant Bovine Somatotropin (rbST) Abuse in Cattle

Biomarker profiling, as a rapid screening approach for detection of hormone abuse, requires well selected candidate biomarkers and a thorough in vivo biomarker evaluation as previously done for detection of growth hormone doping in athletes. The bovine equivalent of growth hormone, called recombinant bovine somatotropin (rbST) is (il)legally administered to enhance milk production in dairy cows. In this study, first a generic sample pre-treatment and 4-plex flow cytometric immunoassay (FCIA) were developed for simultaneous measurement of four candidate biomarkers selected from literature: insulin-like growth factor 1 (IGF-1), its binding protein 2 (IGFBP2), osteocalcin and endogenously produced antibodies against rbST. Next, bovine serum samples from two extensive controlled rbST animal treatment studies were used for in vivo validation and biomarker evaluation. Finally, advanced statistic tools were tested for the assessment of biomarker combination quality aiming to correctly identify rbST-treated animals. The statistical prediction tool k-nearest neighbours using a combination of the biomarkers osteocalcin and endogenously produced antibodies against rbST proved to be very reliable and correctly predicted 95% of the treated samples starting from the second rbST injection until the end of the treatment period and even thereafter. With the same biomarker combination, only 12% of untreated animals appeared false-positive. This reliability meets the requirements of Commission Decision 2002/657/EC for screening methods in veterinary control. From the results of this multidisciplinary study, it is concluded that the osteocalcin – anti-rbST-antibodies combination represent fit-for-purpose biomarkers for screening of rbST abuse in dairy cattle and can be reliably measured in both the developed 4-plex FCIA as well as in a cost-effective 2-plex microsphere-based binding assay. This screening method can be incorporated in routine veterinary monitoring programmes: in the European Union for detection of rbST abuse and in the control of rbST-free dairy farms in the United States of America and other countries.     

Opposing effects of heat stress on male versus female reproductive success in Bicyclus anynana butterflies

In ectothermic organisms, reproductive success and survival are vitally affected by temperature. Here, we analyzed the effects of a short-time exposure to heat stress (1 h at 40 °C versus controls) on reproductive success and longevity in Bicyclus anynana butterflies. After having applied heat stress or a control treatment, individuals were mated in all four possible sexes by treatment combinations. Heat exposure of females caused a subsequent reduction in longevity, fecundity, egg size and concomitantly reproductive investment. Heat exposure of males also reduced longevity, but had in general little effect on the reproduction of female mates. However, females having mated with heat-stressed males showed surprisingly an increased rather than decreased early fecundity, which may indicate an increased investment in current reproduction in stressful environments. Heat stress had no significant effect on egg hatching success, time to copulation and copulation duration. Our results suggest that a short period of heat stress may substantially reduce longevity and reproductive output, with striking differences among sexes. We found no evidence for males being more strongly affected by heat stress than females.     

A new type of brachyuran seminal receptacle in the masked crab Ethusa mascarone (Brachyura,Ethusidae)

The reproductive system of the female Ethusa mascarone was studied with a combination of histological and MRI‐techniques. The study reveals a completely new type of eubrachyuran seminal receptacle. This receptacle consists of two largely separate chambers that engage with each other in a manner similar to shaking hands. One chamber facing the medial axis is lined by cuticle while the second chamber consists of a thick holocrine epithelium. Both chambers are connected by two openings of a unique structure. First, the glandular chamber opens ventro‐laterally to the cuticle chamber via a laterally flattened connective duct that is lined by a highly folded cuticle. A second opening connects both chambers dorsally with the oviduct orifice. A distinct character is the cuticular hook‐like projection that is situated in between the connection of oviduct opening, the glandular chamber and the cuticle chamber of the seminal receptacle. The complete seminal receptacle exhibits a combination of plesiomorphic and apomorphic characters. The arrangement of the receptacles featured in two separate chambers, including the ventro‐lateral connection of the glandular chamber to the cuticle chamber, presumably reflects an early evolutionary stage of an eubrachyuran receptacle. In contrast, the dorso‐lateral opening between both chambers, including the hook‐like projection, appears to be an apomorphic character of at least E. mascarone. J. Morphol. 277:1497–1508, 2016. © 2016 Wiley Periodicals, Inc.