Human impact, soil erosion, and vegetation response lags to climate change: challenges for the mid-Scandinavian pollen-based transfer-function temperature reconstructions

Precise and accurate reconstructions of past environmental parameters from high-quality palaeoenvironmental studies are critical for realistic testing of climate models. To ascertain the reliability of the reconstructions of the past, cross-validation from a variety of proxies and methods is essential. Mid-Scandinavia, showing a variety of palaeoecological studies, is a suitable region for comparing and validating environmental reconstructions. Here, pollen-based transfer-function reconstructions show inconsistent late-glacial temperature patterns. They also show that the Holocene Thermal Maximum (HTM) occurs at ca. 7.5–4.5 cal. ka b.p. However, thermal indicators (pollen, megafossils, plant macrofossils) place the HTM at no later than ca. 10–7.5 cal. ka b.p. It is argued that after the onset of the early Holocene warming equilibrium between vegetation and climate was established over a prolonged period; i.e. ca. 1,500 and 4,000 years in the mountains and lowlands, respectively. In the mountains, soil drought, wind and winter stress were important factors causing the lag, whereas inter-specific competition and soil development delayed the succession within the species-diverse lowland forests. These lags when vegetation was not filling its thermal potential result in a distortion of the temperature signal as derived by transfer functions which assume that vegetation is essentially in equilibrium with climate. Due to widespread human impact and erosion today, many modern training set samples are unsuitable as reference material for past environmental conditions. Various recommendations are suggested towards making improvements in the pollen-transfer function approach to climate reconstructions. To overcome the difficulties resulting from vegetation lags in the early Holocene, proxies that have a faster response time to climate, such as chironomids and aquatic plants including algae, may replace terrestrial pollen.     

Male phenotypic quality influences offspring sex ratio in a polygynous ungulate

Evolutionary models of sex ratio adjustment applied to mammals have ignored that females may gain indirect genetic benefits from their mates. The differential allocation hypothesis (DAH) predicts that females bias the sex ratio of their offspring towards (more costly) males when breeding with an attractive male. We manipulated the number of available males during rut in a polygynous ungulate species, the reindeer (Rangifer tarandus), and found that a doubling of average male mass (and thus male attractiveness) in the breeding herd increased the proportion of male offspring from approximately 40 to 60%. Paternity analysis revealed indeed that males of high phenotypic quality sired more males, consistent with the DAH. This insight has consequences for proper management of large mammal populations. Our study suggests that harvesting, by generating a high proportion of young, small and unattractive mates, affects the secondary sex ratio due to differential allocation effects in females. Sustainable management needs to consider not only the direct demographic changes due to harvest mortality and selection, but also the components related to behavioural ecology and opportunities for female choice.     

An attempt to define 1qh+, 9qh+, and 16qh+

Summary The lengths of the secondary constrictions of chromosomes 1, 9, and 16 vary with the degree of contraction of the chromosomes but these constrictions contract to a lesser degree than the euchromatic portions of the chromosomes. The regression coefficient for the regression of the length of the secondary constriction on the length of the euchromatic part of the chromosomes is shown to be larger for large constrictions. It is furthermore shown that there is a linear correlation between the regression coefficient and the size of the secondary constriction in question. This linear correlation makes it possible to correct the lengths of the secondary constrictions to the lengths expected when contraction is average. The correction method is used in a sample of 30 couples, and on the basis of this sample, the normal limits for the lengths of the secondary constrictions in chromosomes 1, 9, and 16 are defined.     

Tailored Electron Transfer Pathways in Aucore/Ptshell–Graphene Nanocatalysts for Fuel Cells

Au_core/Pt_shell–graphene catalysts (G‐Cys‐Au@Pt) are prepared through chemical and surface chemical reactions. Au–Pt core–shell nanoparticles (Au@Pt NPs) covalently immobilized on graphene (G) are efficient electrocatalysts in low‐temperature polymer electrolyte membrane fuel cells. The 9.5 ± 2 nm Au@Pt NPs with atomically thin Pt shells are attached on graphene via l ‐cysteine (Cys), which serves as linkers controlling NP loading and dispersion, enhancing the Au@Pt NP stability, and facilitating interfacial electron transfer. The increased activity of G‐Cys‐Au@Pt, compared to non‐chemically immobilized G‐Au@Pt and commercial platinum NPs catalyst (C‐Pt), is a result of (1) the tailored electron transfer pathways of covalent bonds integrating Au@Pt NPs into the graphene framework, and (2) synergetic electronic effects of atomically thin Pt shells on Au cores. Enhanced electrocatalytic oxidation of formic acid, methanol, and ethanol is observed as higher specific currents and increased stability of G‐Cys‐Au@Pt compared to G‐Au@Pt and C–Pt. Oxygen reduction on G‐Cys‐Au@Pt occurs at 25 mV lower potential and 43 A g_Pt^?1 higher current (at 0.9 V vs reversible hydrogen electrode) than for C–Pt. Functional tests in direct fomic acid, methanol and ethanol fuel cells exhibit 95%, 53%, and 107% increased power densities for G‐Cys‐Au@Pt over C–Pt, respectively.     

Circulating surfactant protein -D is low and correlates negatively with systemic inflammation in early, untreated rheumatoid arthritis

Introduction

Surfactant protein D (SP-D) is a collectin with immuno-regulatory functions, which may depend on oligomerization. Anti-microbial and anti-inflammatory properties have been attributed to multimeric SP-D variants, while trimeric subunits per se have been suggested to enhance inflammation. Previously, we reported low circulating SP-D in early rheumatoid arthritis (RA), and the present investigation aims to extend these data by serial SP-D serum measurements, studies on synovial fluid, SP-D size distribution and genotyping in patients with early RA.

Methods

One-hundred-and-sixty disease-modifying antirheumatic drug (DMARD) naïve RA patients with disease duration less than six months were studied prospectively for four years (CIMESTRA (Ciclosporine, Methotrexate, Steroid in RA) trial) including disease activity measures (C-reactive protein, joint counts and Health Assessment Questionnaire (HAQ) score), autoantibodies, x-ray findings and SP-D. SP-D was quantified by enzyme-linked immunosorbent assay (ELISA) and molecular size distribution was assessed by gel filtration chromatography. Further, SP-D Met11Thr single nucleotide polymorphism (SNP) analysis was performed.

Results

Serum SP-D was significantly lower in RA patients at baseline compared with healthy controls (P < 0.001). SP-D increased slightly during follow-up (P < 0.001), but was still subnormal at four years after adjustment for confounders (P < 0.001). SP-D in synovial fluid was up to 2.5-fold lower than in serum. While multimeric variants were detected in serum, SP-D in synovial fluid comprised trimeric subunits only. There were no significant associations between genotype distribution and SP-D. Baseline SP-D was inversely associated to CRP and HAQ score. A similar relationship was observed regarding temporal changes in SP-D and CRP (zero to four years). SP-D was not associated to x-ray findings.

Conclusions

This study confirms that circulating SP-D is persistently subnormal in early and untreated RA despite a favourable therapeutic response obtained during four years of follow-up. SP-D correlated negatively to disease activity measures, but was not correlated with x-ray progression or SP-D genotype. These observations suggest that SP-D is implicated in RA pathogenesis at the protein level. The exclusive presence of trimeric SP-D in affected joints may contribute to the maintenance of joint inflammation.

Trial registration

(j.nr NCT00209859).     

Effect of hypercapnia on cerebral blood flow and blood volume in pigs studied by positron emission tomography

Pigs are increasingly used as in vivo models in neuroscience, including studies using positron emission tomography. During anesthesia, cerebral blood flow (CBF) and cerebral blood volume (CBV) are mainly regulated by the partial pressure of CO2 (pCO2) in arterial blood. We sought to determine the effects of increased arterial pCO2 (hypercapnia) on CBF and CBV in anesthetized domestic pigs. We anesthetized 4 pigs and manipulated the tidal volume of the ventilator to different pCO2 levels. Baseline pCO2 was on average 6.5 kPa (n = 9 periods) and hypercapnia pCO2 ranged from 11 to 20 kPa, mean 18.5 kPa (n = 9 periods). Series of dynamic PET scans with H(2)15O (CBF measurements) and C15O (CBV measurements) were performed. CBF increased on average 54%, from mean 0.48 ml blood/min/ml brain tissue during normoxia to 0.74 ml blood/min/ml brain tissue during hypercapnia. CBV increased 41% from mean 0.061 ml blood/ml brain tissue (n = 6) during normoxia to 0.086 ml blood/ml brain tissue (n = 6) during hypercapnia. Our observations indicate that pCO2 levels have a major influence on porcine CBF and CBV and should be controlled in studies where a constant level is crucial.     

DNA methylation at promoter regions of interleukin 1B, interleukin 6, and interleukin 8 in non-small cell lung cancer

Epidemiologic and experimental evidences support the concept that inflammation promotes the development and progression of cancers. Interleukins (ILs) regulate the expression of several molecules and signaling pathways involved in inflammation. High expression of some ILs in the tumor microenvironment has been associated with a more virulent tumor phenotype. To examine the role of IL-1β, IL-6, and IL-8 in non-small cell lung cancer, we measured mRNA levels and promoter DNA methylation in a panel of cultured human lung cells (n = 23) and in matched pair lung tumor versus adjacent non-tumorous tissues (n = 24). We found that lung cancer cells or tissues had significantly different DNA methylation and mRNA levels than normal human bronchial epithelial cells or adjacent non-tumorous tissues, respectively. High DNA methylation of ILs promoters in lung cancer cells or tissues was associated with low mRNA levels. We found an inverse correlation between DNA methylation of IL1B, IL6, and IL8 gene promoters and their corresponding mRNA levels, such inverse correlation was more significant for IL1B (i.e., all cancer cell lines used in this study had a hypermethylated IL1B promoter which was associated with silencing of the gene). Our results underline for the first time the role of epigenetic modifications in the regulation of the expression of key cytokines involved in the inflammatory response during lung cancer development.     

Basic Surgical Techniques in the G?ttingen Minipig: Intubation,Bladder Catheterization,Femoral Vessel Catheterization,and Transcardial Perfusion

The emergence of the Göttingen minipig in research of topics such as neuroscience, toxicology, diabetes, obesity, and experimental surgery reflects the close resemblance of these animals to human anatomy and physiology ^1-6.The size of the Göttingen minipig permits the use of surgical equipment and advanced imaging modalities similar to those used in humans ^6-8. The aim of this instructional video is to increase the awareness on the value of minipigs in biomedical research, by demonstrating how to perform tracheal intubation, transurethral bladder catheterization, femoral artery and vein catheterization, as well as transcardial perfusion. Endotracheal Intubation should be performed whenever a minipig undergoes general anesthesia, because it maintains a patent airway, permits assisted ventilation and protects the airways from aspirates. Transurethral bladder catheterization can provide useful information about about hydration state as well as renal and cardiovascular function during long surgical procedures. Furthermore, urinary catheterization can prevent contamination of delicate medico-technical equipment and painful bladder extension which may harm the animal and unnecessarily influence the experiment due to increased vagal tone and altered physiological parameters. Arterial and venous catheterization is useful for obtaining repeated blood samples and monitoring various physiological parameters. Catheterization of femoral vessels is preferable to catheterization of the neck vessels for ease of access, when performing experiments involving frame-based stereotaxic neurosurgery and brain imaging. When performing vessel catheterization in survival studies, strict aseptic technique must be employed to avoid infections⁶. Transcardial perfusion is the most effective fixation method, and yields preeminent results when preparing minipig organs for histology and histochemistry^2,9. For more information about anesthesia, surgery and experimental techniques in swine in general we refer to Swindle 2007. Supplementary information about premedication and induction of anesthesia, assisted ventilation, analgesia, pre- and postoperative care of Göttingen minipigs are available via the internet at http://www.minipigs.com¹⁰. For extensive information about porcine anatomy we refer to Nickel et al. Vol. 1-5¹¹.