The role of high-pressure flow-through experiments for evaluating the mechanical behaviour of gas hydrate-bearing soils

The role of high-pressure flow-through experiments for evaluating the mechanical behaviour of gas hydrate-bearing soil

The algicidal bacterium Kordia algicida shapes a natural plankton community

Plankton communities consist of complex microbial consortia that change over time. These fluctuations can be only partially explained by limiting resources. Biotic factors such as herbivores and pathogens also contribute to the control of algal blooms. Here we address the effects of algicidal bacteria on a natural plankton community in an indoor enclosure experiment. The algicidal bacteria, introduced into plankton taken directly from the North Sea during a diatom bloom, caused the rapid decline of the bloom-forming Chaetoceros socialis within only 1 day. The haptophyte Phaeocystis, in contrast, is resistant to the lytic bacteria and could benefit from the removal of the competitor, as indicated by an onset of a bloom in the treated enclosures. This cascading effect caused by the bacterial pathogen accelerated the succession of Phaeocystis, which bloomed with a delay of only several weeks in the in situ waters at Helgoland Roads in the North Sea. The algicidal bacteria can thus modulate the community within the limits of the abiotic and biotic conditions of the local environment. Implications of our findings for plankton ecosystem functioning are discussed. IMPORTANCE Plankton communities change on a seasonal basis in temperate systems, with distinct succession patterns; this is mainly due to algal species that have their optimal timing relative to environmental conditions. We know that bacterial populations are also instrumental in the decay and termination of phytoplankton blooms. Here, we describe algicidal bacteria as modulators of this important species succession. Upon treatment of a natural plankton consortium with an algicidal bacterium, we observed a strong shift in the phytoplankton community structure, compared to controls, resulting in formation of a succeeding Phaeocystis bloom. Blooms of this alga have a substantial impact on global biogeochemical and ecological cycles, as they are responsible for a substantial proportion of primary production during spring in the North Sea. We propose that one of the key factors influencing such community shifts may be algicidal bacteria

Driving Soils to Change: Tyre Particles Modulate Microbial-Mediated Soil Functions & Nutrient Status in Vegetable Crops

Driving Soils to Change: Tyre Particles Modulate Microbial-Mediated Soil Functions & Nutrient Status in Vegetable Crop

GaMin’11 – an International Inter-laboratory Comparison for Geochemical CO2 - Saline Fluid - Mineral Interaction Experiments

Due to the strong interest in geochemical CO2-fluid-rock interaction in the context of geological storage of CO2 a growing number of research groups have used a variety of different experimental ways to identify important geochemical dissolution or precipitation reactions and – if possible – quantify the rates and extent of mineral or rock alteration. In this inter-laboratory comparison the gas-fluid-mineral reactions of three samples of rock-forming minerals have been investigated by 11 experimental labs. The reported results point to robust identification of the major processes in the experiments by most groups. The dissolution rates derived from the changes in composition of the aqueous phase are consistent overall, but the variation could be reduced by using similar corrections for changing parameters in the reaction cells over time. The comparison of experimental setups and procedures as well as of data corrections identified potential improvements for future gas-fluid-rock studies

Sustainable peeling of Kapok Tree (Ceiba pentandra) bark by the chimpanzees (Pan troglodytes verus) of Comoé National Park, Ivory Coast

Primates often consume either bark or cambium (inner bark) as a fallback food to complete their diet during periods of food scarcity. Wild chimpanzees exhibit great behavioral diversity across Africa, as studies of new populations frequently reveal. Since 2014, we have been using a combination of camera traps and indirect signs to study the ecology and behavior of wild chimpanzees (Pan troglodytes verus) in Comoé National Park, Ivory Coast, to document and understand the behavioral adaptations that help them to survive in a savanna–forest mosaic landscape. We found that Comoé chimpanzees peel the bark of the buttresses of kapok tree (Ceiba pentandra) trees to eat the cambium underneath. Individuals of all sex/age classes across at least six neighboring communities peeled the bark, but only during the late rainy season and beginning of the dry season, when cambium may represent an important fallback food. Baboons (Papio anubis) also target the same trees but mainly eat the bark itself. Most of the bark-peeling wounds on Ceiba trees healed completely within 2 years, seemingly without any permanent damage. We recorded chimpanzees visiting trees in early stages of wound recovery but leaving them unpeeled. Only 6% of peeled trees (N = 53) were reexploited after a year, suggesting that chimpanzees waited for the rest of the trees to regrow the bark fully before peeling them again, thus using them sustainably. Many human groups of hunter-gatherers and herders exploited cambium sustainably in the past. The observation that similar sustainable bark-peeling behavior evolved in both chimpanzees and humans suggests that it has an important adaptive value in harsh environments when other food sources become seasonally scarce, by avoiding the depletion of the resource and keeping it available for periods of scarcity

Adipocytokines and CD34+ Progenitor Cells in Alzheimer's Disease

BACKGROUND: Alzheimer's disease (AD) and atherosclerosis share common vascular risk factors such as arterial hypertension and hypercholesterolemia. Adipocytokines and CD34(+) progenitor cells are associated with the progression and prognosis of atherosclerotic diseases. Their role in AD is not adequately elucidated. METHODS AND FINDINGS: In the present study, we measured in 41 patients with early AD and 37 age- and weight-matched healthy controls blood concentrations of adiponectin and leptin by enzyme linked immunoabsorbent assay and of CD34(+) progenitor cells using flow cytometry. We found significantly lower plasma levels of leptin in AD patients compared with the controls, whereas plasma levels of adiponectin did not show any significant differences (AD vs. control (mean ± SD): leptin:8.9 ± 5.6 ng/mL vs.16.3 ± 15.5 ng/mL;P = 0.038; adiponectin:18.5 ± 18.1 µg/mL vs.16.7 ± 8.9 µg/mL;P = 0.641). In contrast, circulating CD34(+) cells were significantly upregulated in AD patients (mean absolute cell count ± SD:253 ± 51 vs. 203 ± 37; P = 0.02) and showed an inverse correlation with plasma levels of leptin (r =  -0.248; P = 0.037). In logistic regression analysis, decreased leptin concentration (P = 0.021) and increased number of CD34(+) cells (P = 0.036) were both significantly associated with the presence of AD. According to multifactorial analysis of covariance, leptin serum levels were a significant independent predictor for the number of CD34(+) cells (P = 0.002). CONCLUSIONS: Our findings suggest that low plasma levels of leptin and increased numbers of CD34(+) progenitor cells are both associated with AD. In addition, the results of our study provide first evidence that increased leptin plasma levels are associated with a reduced number of CD34(+) progenitor cells in AD patients. These findings point towards a combined involvement of leptin and CD34(+) progenitor cells in the pathogenesis of AD. Thus, plasma levels of leptin and circulating CD34(+) progenitor cells could represent an important molecular link between atherosclerotic diseases and AD. Further studies should clarify the pathophysiological role of both adipocytokines and progenitor cells in AD and possible diagnostic and therapeutic applications

Large herbivores may alter vegetation structure of semi-arid savannas through soil nutrient mediation

In savannas, the tree–grass balance is governed by water, nutrients, fire and herbivory, and their interactions. We studied the hypothesis that herbivores indirectly affect vegetation structure by changing the availability of soil nutrients, which, in turn, alters the competition between trees and grasses. Nine abandoned livestock holding-pen areas (kraals), enriched by dung and urine, were contrasted with nearby control sites in a semi-arid savanna. About 40 years after abandonment, kraal sites still showed high soil concentrations of inorganic N, extractable P, K, Ca and Mg compared to controls. Kraals also had a high plant production potential and offered high quality forage. The intense grazing and high herbivore dung and urine deposition rates in kraals fit the accelerated nutrient cycling model described for fertile systems elsewhere. Data of a concurrent experiment also showed that bush-cleared patches resulted in an increase in impala dung deposition, probably because impala preferred open sites to avoid predation. Kraal sites had very low tree densities compared to control sites, thus the high impala dung deposition rates here may be in part driven by the open structure of kraal sites, which may explain the persistence of nutrients in kraals. Experiments indicated that tree seedlings were increasingly constrained when competing with grasses under fertile conditions, which might explain the low tree recruitment observed in kraals. In conclusion, large herbivores may indirectly keep existing nutrient hotspots such as abandoned kraals structurally open by maintaining a high local soil fertility, which, in turn, constrains woody recruitment in a negative feedback loop. The maintenance of nutrient hotspots such as abandoned kraals by herbivores contributes to the structural heterogeneity of nutrient-poor savanna vegetation

Preferential Entry of Botulinum Neurotoxin A Hc Domain through Intestinal Crypt Cells and Targeting to Cholinergic Neurons of the Mouse Intestine

Botulism, characterized by flaccid paralysis, commonly results from botulinum neurotoxin (BoNT) absorption across the epithelial barrier from the digestive tract and then dissemination through the blood circulation to target autonomic and motor nerve terminals. The trafficking pathway of BoNT/A passage through the intestinal barrier is not yet fully understood. We report that intralumenal administration of purified BoNT/A into mouse ileum segment impaired spontaneous muscle contractions and abolished the smooth muscle contractions evoked by electric field stimulation. Entry of BoNT/A into the mouse upper small intestine was monitored with fluorescent HcA (half C-terminal domain of heavy chain) which interacts with cell surface receptor(s). We show that HcA preferentially recognizes a subset of neuroendocrine intestinal crypt cells, which probably represent the entry site of the toxin through the intestinal barrier, then targets specific neurons in the submucosa and later (90–120 min) in the musculosa. HcA mainly binds to certain cholinergic neurons of both submucosal and myenteric plexuses, but also recognizes, although to a lower extent, other neuronal cells including glutamatergic and serotoninergic neurons in the submucosa. Intestinal cholinergic neuron targeting by HcA could account for the inhibition of intestinal peristaltism and secretion observed in botulism, but the consequences of the targeting to non-cholinergic neurons remains to be determined