Hybridization as a threat in climate relict <Emphasis Type="Italic">Nuphar pumila</Emphasis> (Nymphaeaceae)

Field studies and conceptual work on hybridization-mediated extinction risk in climate relicts are extremely rare. Nuphar pumila (Nymphaeaceae) is one of the most emblematic climate relicts in Europe with few isolated populations in the Alpine arc. The extent of introgression with related lowland and generalist species Nuphar lutea has never been studied using molecular methods. All biogeographical regions where N. pumila naturally occurs in the neighbourhood of the Alpine arc were sampled and studied using nuclear microsatellite markers. Furthermore, we used forward-in-time simulations and Approximate Bayesian Computation to check whether an introgression scenario fits with the observed admixture patterns and estimated the demographic parameters associated with this process. Our study confirms ongoing hybridization between N. pumila and N. lutea and validates it by the use of population models. More than 40 % of investigated N. pumila individuals were admixed and hybrids were found in over 60 % of studied populations. The introgression is bidirectional and is most likely a result of very recent gene flow. Our work provides strong evidence for rapid extinction risk and demographic swamping between specialized climatic relicts and closely related generalists. The remaining pure populations of N. pumila are rare in the Alpine arc and deserve high conservation priority.     

Analysis of the Precision,Robustness, and Speed of Elastic Resonator Interference Stress Microscopy

Localization-microscopy-based methods are widely used to map the forces that cells apply to their substrates and to study important questions of cellular biomechanics. By contrast, elastic resonator interference stress microscopy (ERISM) uses an interference-based approach, which requires low light intensity and facilitates imaging of cellular forces with extreme precision (down to pN forces) and robustness (e.g., for continuous force monitoring over weeks). Here, the measurement trade-offs and numerical considerations required to optimize the performance of ERISM are described. The crucial parts of the fitting algorithm and the computational tools used to evaluate the data are explained in detail, and the precision and accuracy achievable with ERISM are analyzed. Additional features that can improve the robustness of ERISM further are discussed. The implementation of the analysis algorithm is verified with simulated test data and with experimental data. In addition, an approach to increase the acquisition speed of ERISM by a factor of four compared to the original implementation is described. In combination, these strategies allow us to measure the forces generated by a neural growth cone with high temporal resolution and continuously over several hours.     

Towards effective monitoring of tropical phenology: maximizing returns and reducing uncertainty in long‐term studies

Phenology is a key component of ecosystem function and is increasingly included in assessments of ecological change. We consider how existing, and emerging, tropical phenology monitoring programs can be made most effective by investigating major sources of noise in data collection at a long‐term study site. Researchers at Lopé NP, Gabon, have recorded monthly crown observations of leaf, flower and fruit phenology for 88 plant species since 1984. For a subset of these data, we first identified dominant regular phenological cycles, using Fourier analysis, and then tested the impact of observation uncertainty on cycle detectability, using expert knowledge and generalized linear mixed modeling (827 individual plants of 61 species). We show that experienced field observers can provide important information on major sources of noise in data collection and that observation length, phenophase visibility and duration are all positive predictors of cycle detectability. We find that when a phenological event lasts >4 wk, an additional 10 yr of data increases cycle detectability by 114 percent and that cycle detectability is 92 percent higher for the most visible events compared to the least. We also find that cycle detectability is four times as high for flowers compared to ripe fruits after 10 yr. To maximize returns in the short‐term, resources for long‐term monitoring of phenology should be targeted toward highly visible phenophases and events that last longer than the observation interval. In addition, programs that monitor flowering phenology are likely to accurately detect regular cycles more quickly than those monitoring fruits, thus providing a baseline for future assessments of change.     

Soft Interactions with Model Crowders and Non-canonical Interactions with Cellular Proteins Stabilize RNA Folding

Living cells contain diverse biopolymers, creating a heterogeneous crowding environment, the impact of which on RNA folding is poorly understood. Here, we have used single-molecule fluorescence resonance energy transfer to monitor tertiary structure formation of the hairpin ribozyme as a model to probe the effects of polyethylene glycol and yeast cell extract as crowding agents. As expected, polyethylene glycol stabilizes the docked, catalytically active state of the ribozyme, in part through excluded volume effects; unexpectedly, we found evidence that it additionally displays soft, non-specific interactions with the ribozyme. Yeast extract has a profound effect on folding at protein concentrations 1000-fold lower than found intracellularly, suggesting the dominance of specific interactions over volume exclusion. Gel shift assays and affinity pull-down followed by mass spectrometry identified numerous non-canonical RNA-binding proteins that stabilize ribozyme folding; the apparent chaperoning activity of these ubiquitous proteins significantly compensates for the low-counterion environment of the cell.     

Evaluating interactions between space‐use sharing and defence under increasing density conditions for the group‐territorial Red‐cockaded Woodpecker Leuconotopicus borealis

Information about how bird species respond to increasing density conditions through either space‐use sharing or increased territoriality, and how those changes affect fitness, is essential for effective conservation planning. We used a case study of endangered Red‐cockaded Woodpeckers Leuconotopicus borealis (RCW) to address these questions. We documented over 36 000 locations from 44 RCW groups in three density conditions on two sites in South Carolina, USA, between April 2013 and March 2015. The frequency of neighbouring group interactions differed among density conditions and was highest for high‐density groups. RCW home‐ranges and core‐areas were larger under low‐density conditions ( = 88.4 ha,  = 21.0 ha) than under medium ( = 68.29 ha,  = 16.6 ha) and high‐density ( = 76.3 ha,  = 18.6 ha) conditions. Neighbouring RCWs maintained overlapping home‐ranges with nearly exclusive core‐areas across density conditions, but overlap tended to increase as neighbouring group density increased. Under high‐density conditions, home‐range overlap correlated inversely with clutch size (β ± se = ?0.19 ± 0.09), nestling production (β ± se = ?0.37 ± 0.09) and fledgling production (β ± se = ?0.34 ± 0.08). Our results indicate that RCWs dedicate more effort to territorial defence under high‐density conditions, potentially at the expense of greater foraging efficiency and time allocated to reproduction, as evidenced by reduced fitness. Large home‐range overlap indicated limited territoriality farther away from cavity trees, but the existence of exclusive core‐areas suggests that RCW groups defend habitat closer to cavity trees. Thiessen partitions used to allocate critical foraging habitat offered comprehensive habitat protection for RCW but appear flawed for spatially explicit habitat assessments because they do not accurately delineate space used by individual RCW groups.     

Plasma alpha 1B-glycoprotein allele frequencies in Finns and Swedish Lapps: evidence for a new alpha 1B allele

A new allele (A1B*5) of human plasma alpha 1B-glycoprotein (alpha 1B) was reported. alpha 1B phenotyping was done by two-dimensional agarose gel (pH 5.4)-horizontal polyacrylamide gel (pH 9.0) electrophoresis followed by protein staining. The alpha 1B phenotypes 1-1, 1-2, 1-5 and 2-2 were observed in Finns and phenotypes 1-1, 1-2, 1-5 and 2-5 in Swedish Lapps. The respective frequencies of A1B*1, A1B*2 and A1B*5 were 0.9575, 0.0350, 0.0075 in Finns and 0.8922, 0.0653, 0.0425 in Swedish Lapps. The Swedish Lapps showed a higher degree of alpha 1B polymorphism (polymorphism information content = 0.19) than other Caucasian populations that have been studied.     

Neurogenic pulmonary edema in a pulmonary normotensive model

In the present study our aim was to determine whether or not neurogenic pulmonary edema would develop from a brief pulse of intracranial pressure (ICP) in the absence of any obvious pulmonary hypertension. There were three groups of cats: sham-operated controls, ICP only, and ICP plus variable occlusion of the pulmonary artery. Partial occlusion of the pulmonary artery was carried out by placing a ligature around the pulmonary trunk and mechanically constricting the artery to maintain pulmonary arterial pressure (PAP) and left atrial pressure (LAP) at pre-ICP levels. In sham-operated animals the extravascular lung water/blood free dry weight ratio (EVLW/BFDW) was 3.26 +/- 0.07 and broncho-alveolar lavage (BAL) protein, 6.49 +/- 0.62 mg/g lung. ICP-only caused a rise in PAP, left atrial pressure, and EVLW/BFDW to 3.67 +/- 0.08 (P less than 0.05). ICP with partial occlusion of the pulmonary artery prevented any rise in PAP or LAP while EVLW/BFDW rose to 3.67 +/- 0.10 (P less than 0.05) and BAL protein was 8.37 +/- 1.27 mg/g lung. Our results show that EVLW/BFDW can increase with neurogenic pulmonary edema in cats in the absence of an obvious increase in pulmonary arterial or left atrial pressure.