A first report on coexistence and hybridization of <Emphasis Type="Italic">Mytilus trossulus</Emphasis> and <Emphasis Type="Italic">M. edulis</Emphasis> mussels in Greenland

Semi-sessile Mytilus mussels are used as indicators of climate changes, but their geographic distribution is not sufficiently known in the Arctic. The aim of this study was to investigate the taxonomic status and genetic differentiation of Mytilus populations in a Northwest Greenlandic fjord at Maarmorilik, impacted by contaminations from a former mine. In this study, mussels were collected at three sites differing in exposure to environmental factors. A total of 54 polymorphic SNPs found in the Mytilus EST and DNA sequences analyzed were successfully applied to 256 individuals. The results provided the first evidence for the existence of M. trossulus in Greenland. The mussel from M. trossulus and M. edulis taxa are shown to coexist and hybridize in the fjord. The three studied sites were found to differ significantly in the distribution of taxa with a higher prevalence of M. trossulus in the inner fjord. The identified M. edulis × M. trossulus hybrids mostly had a hybrid index score of about 0.5, indicating a similar number of alleles characteristic for M. trossulus and M. edulis. There was a low number of backcrosses between ‘pure’ taxa and hybrids. This newly discovered hybrid zone between the two taxa is unique in comparison with the Canadian populations. As Mytilus mussels in Greenland hitherto have been regarded as the one taxon M. edulis, the results have importance for biogeography and future monitoring and environmental studies.     

Identifying and correcting spatial bias in opportunistic citizen science data for wild ungulates in Norway

Many publications make use of opportunistic data, such as citizen science observation data, to infer large‐scale properties of species’ distributions. However, the few publications that use opportunistic citizen science data to study animal ecology at a habitat level do so without accounting for spatial biases in opportunistic records or using methods that are difficult to generalize. In this study, we explore the biases that exist in opportunistic observations and suggest an approach to correct for them. We first examined the extent of the biases in opportunistic citizen science observations of three wild ungulate species in Norway by comparing them to data from GPS telemetry. We then quantified the extent of the biases by specifying a model of the biases. From the bias model, we sampled available locations within the species’ home range. Along with opportunistic observations, we used the corrected availability locations to estimate a resource selection function (RSF). We tested this method with simulations and empirical datasets for the three species. We compared the results of our correction method to RSFs obtained using opportunistic observations without correction and to RSFs using GPS‐telemetry data. Finally, we compared habitat suitability maps obtained using each of these models. Opportunistic observations are more affected by human access and visibility than locations derived from GPS telemetry. This has consequences for drawing inferences about species’ ecology. Models naïvely using opportunistic observations in habitat‐use studies can result in spurious inferences. However, sampling availability locations based on the spatial biases in opportunistic data improves the estimation of the species’ RSFs and predicted habitat suitability maps in some cases. This study highlights the challenges and opportunities of using opportunistic observations in habitat‐use studies. While our method is not foolproof it is a first step toward unlocking the potential of opportunistic citizen science data for habitat‐use studies.     

Soil organic matter molecular composition and state of decomposition in three locations of the European Arctic

Increased mineralization of the organic matter (OM) stored in permafrost is expected to constitute the largest additional global warming potential from terrestrial ecosystems exposed to a warmer climate. Chemical composition of permafrost OM is thought to be a key factor controlling the sensitivity of decomposition to warming. Our objective was to characterise OM from permafrost soils of the European Arctic: two mineral soils—Adventdalen, Svalbard, Norway and Vorkuta, northwest Russia—and a “palsa” (ice-cored peat mound patterning in heterogeneous permafrost landscapes) soil in Neiden, northern Norway, in terms of molecular composition and state of decomposition. At all sites, the OM stored in the permafrost was at an advanced stage of decomposition, although somewhat less so in the palsa peat. By comparing permafrost and active layers, we found no consistent effect of depth or permafrost on soil organic matter (SOM) chemistry across sites. The permafrost-affected palsa peat displayed better preservation of plant material in the deeper layer, as indicated by increasing contribution of lignin carbon to total carbon with depth, associated to decreasing acid (Ac) to aldehyde (Al) ratio of the syringyl (S) and vanillyl (V) units, and increasing S/V and contribution of plant-derived sugars. By contrast, in Adventdalen, the Ac/Al ratio of lignin and the Alkyl C to O-alkyl C ratio in the NMR spectra increased with depth, which suggests less oxidized SOM in the active layer compared to the permafrost layer. In Vorkuta, SOM characteristics in the permafrost profile did not change substantially with depth, probably due to mixing of soil layers by cryoturbation. The composition and state of decomposition of SOM appeared to be site-specific, in particular bound to the prevailing organic or mineral nature of soil when attempting to predict the SOM proneness to degradation. The occurrence of processes such as palsa formation in organic soils and cryoturbation should be considered when up-scaling and predicting the responses of OM to climate change in arctic soils.     

Mechanical properties of C-5 epimerized alginates

There is an increased need for alginate materials with both enhanced and controllable mechanical properties in the fields of food, pharmaceutical and specialty applications. In the present work, well-characterized algal polymers and mannuronan were enzymatically modified using C-5 epimerases converting mannuronic acid residues to guluronic acid in the polymer chain. Composition and sequential structure of controls and epimerized alginates were analyzed by (1)H NMR spectroscopy. Mechanical properties of Ca-alginate gels were further examined giving Young's modulus, syneresis, rupture strength, and elasticity of the gels. Both mechanical strength and elasticity of hydrogels could be improved and manipulated by epimerization. In particular, alternating sequences were found to play an important role for the final mechanical properties of alginate gels, and interestingly, a pure polyalternating sample resulted in gels with extremely high syneresis and rupture strength. In conclusion, enzymatic modification was shown to be a valuable tool in modifying the mechanical properties of alginates in a highly specific manner.     

Rapid and sustained improvements in health-related quality of life,fatigue, and other patient-reported outcomes in rheumatoid arthritis patients treated with certolizumab pegol plus methotrexate over 1 year: results from the RAPID 1 randomized controlled trial

Introduction

The objective of this study was to assess the impact of certolizumab pegol (CZP) treatment on health-related quality of life (HRQoL), fatigue and other patient-reported outcomes (PROs) in patients with rheumatoid arthritis (RA).

Methods

Patients with active RA (N = 982) were randomized 2:2:1 to subcutaneous CZP (400 mg at weeks 0, 2 and 4; followed by CZP 200 mg or 400 mg) plus methotrexate (MTX) every other week, or placebo (PBO) plus MTX. PRO assessments included HRQoL, fatigue, physical function, arthritis pain and disease activity. Adjusted mean changes from baseline in all PROs were obtained using analysis of covariance (ANCOVA) applying last observation carried forward (LOCF) imputation. The proportion of patients achieving clinically meaningful improvements in each PRO was obtained using logistic regression and by applying non-responder imputation to missing values after rescue medication or withdrawal. The correlations between PRO responses and clinical responses were also assessed by tetrachoric correlation using non-responder imputation.

Results

Patients treated with CZP plus MTX reported significant (P < 0.001), clinically meaningful improvements in HRQoL at the first assessment (week 12); reductions in fatigue, disease activity and pain and improvements in physical function were reported at week 1. In particular, CZP-treated patients reported improvements in mental health. Mean changes from baseline in the SF-36 Mental Component Summary (MCS) at week 52 for CZP 200 mg and 400 mg plus MTX, and PBO plus MTX were 6.4, 6.4 and 2.1, respectively (P < 0.001). In addition, mental health and vitality scores in CZP-treated patients approached age- and gender-adjusted US population norms. Improvements in all PROs were sustained. Similar benefits were reported with both CZP doses. Changes in SF-36 MCS scores had the lowest correlation with disease activity scores (DAS28) and American College of Rheumatology 20% improvement (ACR20) response rates, while improvements in pain showed the highest correlation.

Conclusions

Treatment with CZP plus MTX resulted in rapid and sustained improvements in all PROs, indicating that the benefits of CZP extend beyond clinical efficacy endpoints into areas that are more relevant and meaningful for patients on a daily basis.

Trial Registration

ClinicalTrials.gov {"type":"clinical-trial","attrs":{"text":"NCT00152386","term_id":"NCT00152386"}}NCT00152386.     

Transcriptional response to mitochondrial NADH kinase deficiency in Saccharomyces cerevisiae

Yeast cells lacking the mitochondrial NADH kinase encoded by POS5 display increased sensitivity to hydrogen peroxide, a slow-growth phenotype, reduced mitochondrial function and increased levels of mitochondrial protein oxidation and mtDNA mutations. Here we examined gene expression in pos5Δ cells, comparing these data to those from cells containing deletions of superoxide dismutase-encoding genes SOD1 or SOD2. Surprisingly, stress–response genes were down-regulated in pos5Δ, sod1Δ and sod2Δ cells, implying that cells infer stress levels from mitochondrial activity rather than sensing reactive oxygen species directly. Additionally, pos5Δ, but not sod1 or sod2, cells displayed an anaerobic expression profile, indicating a defect in oxygen sensing that is specific to pos5, and is not a general stress–response. Finally, the pos5Δ expression profile is quite similar to the hap1Δ expression profile previously reported, which may indicate a shared mechanism.     

Estimation of non-linear growth models by linearization: a simulation study using a Gompertz function

A method based on Taylor series expansion for estimation of location parameters and variance components of non-linear mixed effects models was considered. An attractive property of the method is the opportunity for an easily implemented algorithm. Estimation of non-linear mixed effects models can be done by common methods for linear mixed effects models, and thus existing programs can be used after small modifications. The applicability of this algorithm in animal breeding was studied with simulation using a Gompertz function growth model in pigs. Two growth data sets were analyzed: a full set containing observations from the entire growing period, and a truncated time trajectory set containing animals slaughtered prematurely, which is common in pig breeding. The results from the 50 simulation replicates with full data set indicate that the linearization approach was capable of estimating the original parameters satisfactorily. However, estimation of the parameters related to adult weight becomes unstable in the case of a truncated data set.