Spatial resolution, spectral metrics and biomass are key aspects in estimating plant species richness from spectral diversity in species‐rich grasslands

Increasing evidence suggests that remotely sensed spectral diversity is linked to plant species richness. However, a conflicting spectral diversity–biodiversity relationship in grasslands has been found in previous studies. In particular, it remains unclear how well the spectral diversity–biodiversity relationship holds in naturally assembled species-rich grasslands. To address the linkage between spectral diversity and plant species richness in a species-rich alpine grassland ecosystem, we investigated (i) the trade-off between spectral and spatial resolution in remote sensing data; (ii) the suitability of three different spectral metrics to describe spectral diversity (coefficient of variation, convex hull volume and spectral species richness) and (iii) the importance of confounding effects of live plant biomass, dead plant biomass and plant life forms on the spectral diversity–biodiversity relationship. We addressed these questions using remote sensing data collected with consumer-grade cameras with four spectral bands and 10 cm spatial resolution on an unmanned aerial vehicle (UAV), airborne imaging spectrometer data (AVIRIS-NG) with 372 bands and 2.5 m spatial resolution, and a fused data product of both datasets. Our findings suggest that a fused dataset can cope with the requirement of both high spatial- and spectral resolution to remotely measure biodiversity. However, in contrast to several previous studies, we found a negative correlation between plant species richness and spectral metrics based on the spectral information content (i.e. spectral complexity). The spectral diversity calculated based on the spectral complexity was sensitive to live and dead plant biomass. Overall, our results suggest that remote sensing of plant species diversity requires a high spatial resolution, the use of classification-based spectral metrics, such as spectral species richness, and awareness of confounding factors (e.g. plant biomass), which may be ecosystem specific

Tributary effects on the ecological responses of a regulated river to experimental floods

Rivers regulated by dams display several ecosystem alterations due to modified flow and sediment regimes. Downstream from a dam, ecosystem degradation occurs because of reduced disturbance, mostly derived from limitations on flow variability and sediment supply. In the last decade, most flow restoration/dam impact mitigation was oriented towards the development of environmental flows. Flow variability (and consequent disturbance) can be reintroduced by releasing artificial high flows (experimental floods). Flow-sediment interactions during experimental floods represent strong ecosystem drivers, influencing nutrient dynamics, and metabolic and functional properties. In river networks, sediment and water inputs from tributaries generate points of discontinuity that can drive major changes in environmental conditions, affecting habitat structure and determining functional differences between upstream and downstream. However, despite the relevance for management, flow/sediment relations during environmental flows - and more importantly during experimental floods - remain poorly understood, mostly due to the lack of empirical evidence. In this study, we examined how a major tributary (source of water and sediments) modified the physical habitat template of a regulated river, thereby influencing ecological and geomorphological responses to experimental floods. Methods combined high-resolution drone mapping techniques with a wide range of biological samples collected in field surveys before, during, and after experimental floods in an alpine river. Data were used to quantify changes in relevant functional and structural ecosystem properties, relating ecological responses to geomorphological dynamics. Results highlight the importance of tributaries in restoring ecosystem properties lost after damming, enhancing the resilience of the system. In addition, we observed that disturbance legacy played a fundamental role in determining ecological conditions of a river prior to experimental floods, thus confirming that considering flow variability and sediment availability is crucial in adaptive dam management and environmental flows design

Circular RNAs in urine of kidney transplant patients with acute T Cell-mediated allograft rejection

BACKGROUND: Circular RNAs (circRNAs) have recently been described as novel noncoding regulators of gene expression. They are detectable in the blood of patients with acute kidney injury. We tested whether circRNAs were present in urine and could serve as new predictors of outcome in renal transplant patients with acute rejection. METHODS: A global circRNA expression analysis using RNA from urine of patients with acute T cell-mediated renal allograft rejection and control transplant patients was performed. Dysregulated circRNAs were confirmed in a cohort of 62 patients with acute rejection, 10 patients after successful antirejection therapy, 18 control transplant patients without rejection, and 13 stable transplant patients with urinary tract infection. RESULTS: A global screen revealed several circRNAs to be altered in urine of patients with acute rejection. Concentrations of 2 circRNAs including hsa_circ_0001334 and hsa_circ_0071475 were significantly increased. These were validated in the whole cohort of patients. hsa_circ_0001334 was upregulated in patients with acute rejection compared with controls. Concentrations of hsa_circ_0001334 normalized in patients with acute rejection following successful antirejection therapy. hsa_circ_0001334 was associated with higher decline in glomerular filtration rate 1 year after transplantation. CONCLUSIONS: CircRNA concentrations are significantly dysregulated in patients with acute rejection at subclinical time points. Urinary hsa_circ_0001334 is a novel biomarker of acute kidney rejection, identifying patients with acute rejection and predicting loss of kidney function

Book reviews

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/47962/1/11406_2006_Article_BF02378973.pd

Actin depolymerisation and crosslinking join forces with myosin II to contract actin coats on fused secretory vesicles

In many secretory cells actin and myosin are specifically recruited to the surface of secretory granules following their fusion with the plasma membrane. Actomyosin-dependent compression of fused granules is essential to promote active extrusion of cargo. However, little is known about molecular mechanisms regulating actin coat formation and contraction. Here, we provide a detailed kinetic analysis of the molecules regulating actin coat contraction on fused lamellar bodies in primary alveolar type II cells. We demonstrate that ROCK1 and myosin light chain kinase 1 (MLCK1, also known as MYLK) translocate to fused lamellar bodies and activate myosin II on actin coats. However, myosin II activity is not sufficient for efficient actin coat contraction. In addition, cofilin-1 and α-actinin translocate to actin coats. ROCK1-dependent regulated actin depolymerisation by cofilin-1 in cooperation with actin crosslinking by α-actinin is essential for complete coat contraction. In summary, our data suggest a complementary role for regulated actin depolymerisation and crosslinking, and myosin II activity, to contract actin coats and drive secretion

Surface pretreatments for medical application of adhesion

Medical implants and prostheses (artificial hips, tendono- and ligament plasties) usually are multi-component systems that may be machined from one of three material classes: metals, plastics and ceramics. Typically, the body-sided bonding element is bone. The purpose of this contribution is to describe developments carried out to optimize the techniques , connecting prosthesis to bone, to be joined by an adhesive bone cement at their interface. Although bonding of organic polymers to inorganic or organic surfaces and to bone has a long history, there remains a serious obstacle in realizing long-term high-bonding strengths in the in vivo body environment of ever present high humidity. Therefore, different pretreatments, individually adapted to the actual combination of materials, are needed to assure long term adhesive strength and stability against hydrolysis. This pretreatment for metal alloys may be silica layering; for PE-plastics, a specific plasma activation; and for bone, amphiphilic layering systems such that the hydrophilic properties of bone become better adapted to the hydrophobic properties of the bone cement. Amphiphilic layering systems are related to those developed in dentistry for dentine bonding. Specific pretreatment can significantly increase bond strengths, particularly after long term immersion in water under conditions similar to those in the human body. The bond strength between bone and plastic for example can be increased by a factor approaching 50 (pealing work increasing from 30 N/m to 1500 N/m). This review article summarizes the multi-disciplined subject of adhesion and adhesives, considering the technology involved in the formation and mechanical performance of adhesives joints inside the human body