The calcitic test growth rate of <i>Spirillina vivipara</i> (Foraminifera)

Foraminifera encompass vastly differing morphologies, ecological preferences, and elemental/isotopic test compositions. The calcification mechanism is completely unknown for some wall-type taxa and might be different from that of well-studied groups. This study aims to understand the test growth and determine the calcification rate of Spirillina vivipara Ehrenberg, 1843 (order Spirillinida) and to compare them to other foraminiferal species. Spirillinids have a closely coiled spiral chamber like a tube, yet their calcitic microstructure is unique amongst foraminifera. Calcification observations in S. vivipara facilitate the estimation of carbonate precipitation rates during active test growth, which are revealed to be independent of the individual's size. Spirillina vivipara grows its test in response to food availability, suggesting that calcification directly corresponds to cell growth. Time-lapse observations of S. vivipara indicate continuous growth, suggesting active growth phases interspersed with resting periods, hinting at potential biological rhythms in the growth and calcification process. We also implemented a 24 h observation period using calcein staining, showing calcite precipitation rates of 8.08 µm h−1, which corresponds to approximately 364 nmol cm−2 min−1 (i.e., 36.4 mg cm−2 min−1). These rates are higher than those of other foraminiferal species and those in most inorganic precipitation experiments. Such high rates in spirillinid foraminifera may explain their distinctive morphology, elemental composition, unusual reproduction, and ecological distribution.</p

Weaving of biomineralization framework in rotaliid foraminifera: implications for paleoceanographic proxies

Elemental and/or isotopic signatures of calcareous tests of foraminifera are commonly used to reconstruct paleoenvironmental conditions. A major problem, often referred to as the vital effect, is that such geochemical signatures stored in inorganic calcium carbonates differ greatly under the same environmental conditions, as well as between taxa, species, individuals, etc. This effect was previously explained by relative contributions between passive vs. active ion transport patterns, but their details are still under investigation. In this study, the functional role of pseudopodial structures during chamber formation is elucidated by detailed observation of Ammonia beccarii (Linnaeus, 1758) using a time-lapse optical imaging system and high-resolution electron microscopy. We document triple organic layers sandwiching carbonate precipitation sites for the first time. The three major organic layers (outer organic layer, primary organic sheet, and inner organic layer) are formed by an initial framework of pseudopodia overlaid with further layer-like pseudopodia. The primary organic sheet seems to facilitate early calcium carbonate nucleation, then entrapped by double precipitation sites. We further show that calcification starts when outer or inner organic layers still exhibit tiny gaps (holes within the framework) that may serve as pathways for passive ion exchange (e.g. Mg2+) between seawater and the confined precipitation space. Nevertheless, the majority of wall thickening occurs when the precipitation site is completely isolated from seawater, which implies active ion exchange. This may explain the differences in Mg&thinsp;∕&thinsp;Ca ratios in early and later stages of calcification observed in previous studies. Our study provides insight into resolving a key missing piece in understanding foraminiferal calcification through culture experiments and in-depth observations of living animals. Our findings contribute to interpreting and understanding biogeochemical proxies by showing that the vital effect, specifically elemental and isotopic ratios along chamber walls, is directly linked to spatio-temporal organization of the biomineralization sandwich controlled by the three major organic layers.</p

Benthic carbon mineralization in hadal trenches:assessment by in situ O₂ microprofile measurements

Hadal trenches are considered to act as depo-centers for organic material at the trench axis and host unique and elevated biomasses of living organisms as compared to adjacent abyssal plains. To explore the diagenetic activity in hadal trench environments we quantified in situ benthic O2 consumption rates and sediment characteristics from the trench axis of two contrasting trench systems in the Pacific Ocean; the Izu-Bonin Trench underlying mesotrophic waters and the Tonga Trench underlying oligotrophic waters. In situ oxygen consumption at the Izu-Bonin Trench axis site (9200 m; 746±103 µmol m−2 d−1; n=27) was 3-times higher than at the Tonga Trench axis site (10800 m; 225±50 µmol m−2 d−1; n=7) presumably reflecting the higher surface water productivity in the Northern Pacific. Comparing benthic O2 consumption rates measured in the central hadal Tonga Trench to that of nearby (60 km distance) abyssal settings (6250 m; 92±44 µmol m−2 d−1; n=16) revealed a 2.5 higher activity at the trench bottom. Onboard investigations on recovered sediment furthermore revealed that the prokaryotic abundance and concentrations of phytopigments followed this overall trend (i.e minimum values at the abyssal site followed by higher values from the Tonga and Izu-Bonin Trenches axis, respectively). Excess 210Pb profiles suggested that mass-wasting events contributed to the deposition of material enhancing the concentration of organic matter in the central trench as compared to the abyssal settings. Our results complement recent findings from the Challenger deep in the Mariana Trench area, which also revealed elevated diagenetic activity in the central trench underpinning the importance of hadal ecosystems for the deep sea carbon cycling

Current management strategies for the pain of elderly patients with burning mouth syndrome : a critical review

Burning Mouth Syndrome (BMS), a chronic intraoral burning sensation or dysesthesia without clinically evident causes, is one of the most common medically unexplained oral symptoms/syndromes. Even though the clinical features of BMS have been astonishingly common and consistent throughout the world for hundreds of years, BMS remains an enigma and has evolved to more intractable condition. In fact, there is a large and growing number of elderly BMS patients for whom the disease is accompanied by systemic diseases, in addition to aging physical change, which makes the diagnosis and treatment of BMS more difficult. Because the biggest barrier preventing us from finding the core pathophysiology and best therapy for BMS seems to be its heterogeneity, this syndrome remains challenging for clinicians. In this review, we discuss currently hopeful management strategies, including central neuromodulators (Tricyclic Antidepressants - TCAs, Serotonin, and Norepinephrine Reuptake Inhibitors - SNRIs, Selective Serotonin Reuptake Inhibitors - SSRIs, Clonazepam) and solutions for applying non-pharmacology approaches. Moreover, we also emphasize the important role of patient education and anxiety management to improve the patients’ quality of life. A combination of optimized medication with a short-term supportive psychotherapeutic approach might be a useful solution

Characteristics of a High-Purity Germanium Detector

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Physiological levels of nitrate support anoxic growth by denitrification of Pseudomonas aeruginosa at growth rates reported in cystic fibrosis lungs and sputum

© 2014 Line, Alhede, Kolpen, Kuhl, Ciofu, Bjarnsholt, Moser, Toyofuku, Nomura, H0i'by and Jensen. Chronic Pseudomonas aeruginosa lung infection is the most severe complication in patients with cystic fibrosis (CF). The infection is characterised by the formation of biofilm surrounded by numerous polymorphonuclear leukocytes (PMNs) and strong O2 depletion in the endobronchial mucus. We have reported that O2 is mainly consumed by the activated PMNs, while O2 consumption by aerobic respiration is diminutive and nitrous oxide (N2O) is produced in infected CF sputum. This suggests that the reported growth rates ofP. aeruginosa in lungs and sputum may result from anaerobic respiration using denitrification. The growth rate of P. aeruginosa achieved by denitrification at physiological levels (~400 μM) of nitrate (NO3-) is however, not known. Therefore, we have measured growth rates of anoxic cultures of PAO1 and clinical isolates (n = 12) in LB media supplemented with NO3- and found a significant increase of growth when supplementing PAO1 and clinical isolates with > 150 μM NO3- and 100 μM NO3-, respectively. An essential contribution to growth by denitrification was demonstrated by the inability to establish a significantly increased growth rate by a denitrification deficient ΔnirS-N mutant at <1 mM of NO3-. Activation of denitrification could be achieved by supplementation with as little as 62.5 μM of NO3- according to the significant production of N2O by the nitrous oxide reductase deficient ΔnosZ mutant. Studies of the promoter activity, gene transcripts and enzyme activity of the four N-oxide reductases in PAO1 (Nar, Nir, Nor, Nos) further verified the engagement of denitrification, showing a transient increase in activation and expression and rapid consumption of NO3- followed by a transient increase of NO2-. Growth rates obtained by denitrification in this study were comparable to our reported growth rates in the majority of P. aeruginosa cells in CF lungs and sputum. Thus, we have demonstrated that denitrification is required for P. aeruginosa growth in infected endobronchial CF mucus

Drainage, Rebound and Oscillation of a Meniscus in a Tube

In this paper, the drainage and subsequent rebound of a liquid column in a cylindrical tube is examined experimentally and theoretically. When liquid is drawn up into a capillary and then released under gravity, inertia allows the meniscus to overshoot the equilibrium capillary rise height. The meniscus then rebounds up the tube, again overshooting the equilibrium height and undergoes oscillation. By varying both the immersion depth and radius of the tube, one can observe rich dynamical behavior, with the most dramatic being the formation of a fast liquid jet, barely visible to the naked eye but easily captured with high-speed video. In addition to the flow separation caused by the sudden expansion at the end of the tube, this jet serves as a mechanism of energy dissipation. Some qualitative differences between the works of Quere et al. [“Rebounds in a capillary tube,” Langmuir 15, 3679–3682 (1999)] and Lorenceau et al. [“Gravitational oscillations of a liquid column in a pipe,” Phys. Fluids 14(6), 1985–1992 (2002)] and the present experiment are observed and discussed. A critical condition for oscillatory behavior is derived theoretically and matches well with the experimental observation. Once in the oscillatory regime, both the maximum depth below and the maximum rebound height above the equilibrium level are investigated by performing a systematic sweep through the relevant parameter space, incorporating the initial meniscus height, immersion depth, tube radius, and fluid properties. Lastly, the characteristic period of oscillation, tp, is assessed and found to be largely independent of fluid viscosity, and could be reasonably well-collapsed by a single curve whereby tp~√(hi), where hi is the tube immersion depth