Restoring natural seepage conditions on former agricultural grasslands does not lead to reduction of organic matter decomposition and soil nutrient dynamics

In the central part of the Netherlands, wetland restoration projects involve the rewetting of former agricultural land, where low water levels were artificially maintained (polders). Many of these projects do not result in the expected reduction of nitrogen and phosphorus availability and subsequent re-establishment of a diverse wetland vegetation. The aim of the present study was to investigate which mechanisms are responsible for this lack of success. Thereto, we studied the effect of rewetting of former agricultural grasslands on acidified peat soil (pH = 3.5) on organic matter decomposition, nitrogen cycling and phosphorus availability in the soil for three seasons. To provide an explanation for the observed effects, we simultaneously studied a set of potentially controlling abiotic soil conditions that were expected to change after rewetting. It was found that rewetting of these grasslands with natural, unpolluted seepage water did not affect nitrogen cycling, but raised decomposition rates and almost doubled phosphorus availability. The main cause of these effects is a raise of soil pH to about 7 due to the hydrochemical composition of the soil pore water after rewetting, which reflects groundwater with high amounts of buffering ions. This effect overruled any reduction in process rates by the lowered soil redox potential. The counterintuitive finding of eutrophication after rewetting with natural and unpolluted water is considered to represent a new form of internal eutrophication, triggered by the restoration of natural site conditions of former agricultural land on acid peat soil.     

PHOTOSYNTHETIC PIGMENT AND GENETIC DIFFERENCES BETWEEN TWO SOUTHERN OCEAN MORPHOTYPES OF EMILIANIA HUXLEYI (HAPTOPHYTA)1

The widespread coccolithophorid Emiliania huxleyi (Lohmann) W. W. Hay et H. Mohler plays a pivotal role in the carbon pump and is known to exhibit significant morphological, genetic, and physiological diversity. In this study, we compared photosynthetic pigments and morphology of triplicate strains of Southern Ocean types A and B/C. The two morphotypes differed in width of coccolith distal shield elements (0.11–0.24 μm, type A; 0.06–0.12 μm, type B/C) and morphology of distal shield central area (grill of curved rods in type A; thin plain plate in type B/C) and showed differences in carotenoid composition. The mean 19′‐hexanoyloxyfucoxanthin (Hex):chl a ratio in type B/C was >1, whereas the type A ratio was <1. The Hex:fucoxanthin (fuc) ratio for type B/C was 11 times greater than that for type A, and the proportion of fuc in type A was 6 times higher than that in type B/C. The fuc derivative 4‐keto‐19′‐hexanoyloxyfucoxanthin (4‐keto‐hex) was present in type A but undetected in B/C. DNA sequencing of tufA distinguished morphotypes A, B/C (indistinguishable from B), and R, while little variation was observed within morphotypes. Thirty single nucleotide polymorphisms were identified in the 710 bp tufA sequence, of which 10 alleles were unique to B/C and B morphotypes, seven alleles were unique to type A, and six alleles were unique to type R. We propose that the morphologically, physiologically, and genetically distinct Southern Ocean type B/C sensu Young et al. (2003) be classified as E. huxleyi var. aurorae var. nov. S. S. Cook et Hallegr.     

Ferrous Iron Stimulates Phenol Oxidase Activity and Organic Matter Decomposition in Waterlogged Wetlands

Soil organic matter decomposition is limited at waterlogged conditions by the low activity of extracellular enzymes like phenol oxidases. In this paper, we show that ferrous iron (Fe²⁺), which is abundant in waterlogged soils, significantly stimulates phenol oxidase activity both in pure enzyme assays and in waterlogged soil slurries from nutrient-poor dune slacks. However, the effects in soil slurries were less strong than in enzyme assays. Both the addition of Fe²⁺ and the initial presence of Fe²⁺ stimulated phenol oxidase activity at the microaerophilic conditions tested. This stimulation is attributed to the catalysis of additional OH radical production, promoting the oxidation of phenolics. Subsequently, the presence of Fe²⁺ strongly increased total decomposition rates of soil organic matter, measured as CO₂ production and Cotton strip Tensile Strength Loss. There is circumstantial evidence that this stimulation by Fe²⁺ could be important for decomposition in wetlands at field conditions, but its relevance compared to the effects of other compounds still needs to be elucidated. These results emphasise the crucial role of water quality in determining extracellular enzyme activity and decomposition in waterlogged wetlands.     

Effects of jaw adductor hypertrophy on buccal expansions during feeding of air breathing catfishes (Teleostei,Clariidae)

Some species of Clariidae (air breathing catfishes) have extremely well developed (hypertrophied) jaw closing muscles that increase the maximal biting force of these species. As these enlarged jaw muscles tightly cover the suspensoria, which are firmly connected to the neurocranium, we expect diminished lateral expansions during suction for species with hypertrophied jaw muscles. In turn, this could imply a reduced suction performance for these species. Compared to Clarias gariepinus, which has relatively small jaw closers, Clariallabes longicauda shows a clear hypertrophy of the jaw adductors. A kinematic analysis of prey capture in these two species is presented here. As predicted, Clariallabes longicauda shows less lateral expansion (average abduction of the hyoids of 19.0°) than Clarias gariepinus (abduction of 31.1°). However, our data indicate that the decrease in lateral expansion capacity in the species with excessive adductor development is compensated for by a larger and faster ventral expansion of the buccal cavity by depression of the hyoid.     

<Emphasis Type="Italic">Usnea antarctica</Emphasis>, an important Antarctic lichen,is vulnerable to aspects of regional environmental change

Studies of cryptogam responses to climate change in the polar regions are scarce because these slow-growing organisms require long-term monitoring studies. Here, we analyse the response of a lichen and moss community to 10 years of passive environmental manipulation using open-top chambers (OTCs) in the maritime Antarctic region. Cover of the dominant lichen Usnea antarctica declined by 71 % in the OTCs. However, less dominant lichen species showed no significant responses except for an increase in Ochrolechia frigida, which typically covered dying lichen and moss vegetation. There were no detectable responses in the moss or associated micro-arthropod communities to the influence of the OTCs. Based on calculated respiration rates, we hypothesise that the decline of U. antarctica was most likely caused by increased net winter respiration rates (11 %), driven by the higher temperatures and lower light levels experienced inside the OTCs as a result of greater snow accumulation. During summer, U. antarctica appears unable to compensate for this increased carbon loss, leading to a negative carbon balance on an annual basis, and the lichen therefore appears to be vulnerable to such climate change simulations. These findings indicate that U. antarctica dominated fell-fields may change dramatically if current environmental change trends continue in the maritime Antarctic, especially if associated with increases in winter snow depth or duration.     

The facile detection of 1505G-->A in Gaucher patients with different phenotypes

In Gaucher disease patients, over 100 disease-causing mutations have been identified. For identification of the 1504C-->T (R463C) mutation it is common to use PCR-restriction fragmentation analysis using the restriction enzyme MspI. In the present study we investigated the reliability of this approach because accurate determination of genotypes is important in genotype-phenotype correlations. A simple modification, i.e. using the restriction enzyme HphI instead of MspI, revealed that type I and II Gaucher disease patients who had previously been identified as carrying the 1504C-->T mutation in fact carried the 1505G-->A (IVS10(-1)G-->A) mutation. Sequencing of the appropriate fragment confirmed this. The PCR method easily differentiates between these two mutations in Gaucher disease patients, thus circumventing the need for sequencing procedures. The phenotypes of the patients found to be carrying the 1505G-->A mutation are also described.     

Evaluation of progesterone receptor expression in eosinophils using real-time quantitative PCR

Progesterone has been shown in many instances to have immune-suppressant activities. Most of these activities have been investigated in the light of general immune suppression or with a focus on lymphocytes. However, many clinical and in vitro studies have shown that progesterone also has a suppressive effect on eosinophilia. This effect so far has not been thoroughly investigated. The purpose of this study was to evaluate whether the effect is mediated via the classical progesterone receptor (PR). We developed a new real-time quantitative PCR (RQ-PCR) for the analysis and quantification of expression of the classical PR. The test was first validated both on breast cancer cell lines and on breast cancer biopsies. Subsequently, when using eosinophils isolated from peripheral blood of healthy volunteers, we could not find evidence for the expression of PR. These data suggest that the effects of progesterone on eosinophils are not mediated by the classical PR.     

Experimentally generated footprints in sand: Analysis and consequences for the interpretation of fossil and forensic footprints

Fossilized footprints contain information about the dynamics of gait, but their interpretation is difficult, as they are the combined result of foot anatomy, gait dynamics, and substrate properties. We explore how footprints are generated in modern humans. Sixteen healthy subjects walked on a solid surface and in a layer of fine‐grained sand. In each condition, 3D kinematics of the leg and foot were analyzed for three trials at preferred speed, using an infrared camera system. Additionally, calibrated plantar pressures were recorded. After each trial in sand, the depth of the imprint was measured under specific sites. When walking in sand, subjects showed greater toe clearance during swing and a 7° higher knee yield during stance. Maximal pressure was the most influential factor for footprint depth under the heel. For other foot zones, a combination of factors correlates with imprint depth, with pressure impulse (the pressure‐time integral) gaining importance distally, at the metatarsal heads and the hallux. We conclude that footprint topology cannot be related to a single variable, but that different zones of the footprint reflect different aspects of the kinesiology of walking. Therefore, an integrated approach, combining anatomical, kinesiological, and substrate‐mechanical insights, is necessary for a correct interpretation. Am J Phys Anthropol, 2010. © 2009 Wiley‐Liss, Inc.