Evolutionary inheritance of elemental stoichiometry in phytoplankton

The elemental composition of phytoplankton is a fusion of the evolutionary history of the host and plastid, resulting in differences in genetic constraints and selection pressures associated with environmental conditions. The evolutionary inheritance hypothesis predicts similarities in elemental composition within related taxonomic lineages of phytoplankton. To test this hypothesis, we measured the elemental composition (C, N, P, S, K, Mg, Ca, Sr, Fe, Mn, Zn, Cu, Co, Cd and Mo) of 14 phytoplankton species and combined these with published data from 15 more species from both marine and freshwater environments grown under nutrient-replete conditions. The largest differences in the elemental profiles of the species distinguish between the prokaryotic Cyanophyta and primary endosymbiotic events that resulted in the green and red plastid lineages. Smaller differences in trace element stoichiometry within the red and green plastid lineages are consistent with changes in trace elemental stoichiometry owing to the processes associated with secondary endosymbioses and inheritance by descent with modification.     

Fate of elemental sulfur in an intertidal sediment

Abstract: Sediment from a tidal flat at Wedderwarden, near the mouth of the Weser estuary, northern Germany, was amended with elemental sulfur, and concentrations of metabolic end products were monitored. The production of both sulfate and sulfide was consistent with disproportionation as the most important fate of the added elemental sulfur. A population of bacteria conducting active elemental sulfur disproportionation was also enriched from the sediment. In the enrichments, containing both elemental sulfur and Fe oxides as a sulfide 'scrub', sulfide and sulfate were produced in a ratio of     , somewhat lower than the predicted ratio of     . The mismatch between predicted and observed production ratios is explained by the channelling of electrons into autotrophic or mixotrophic CO₂ fixation rather than sulfide formation. The production of organic carbon, in the correct amount to explain the observed sulfide to sulfate production ratio, was verified by organic carbon analysis. Finally, rates of sulfate reduction were identical in the elemental sulfur amended sediment, and in control sediment with no added sulfur. Hence, the heterotrophic bacterial community was completely unaffected by an active metabolism conducting elemental sulfur disproportionation.     

Early postoperative feeding with elemental diet.

The value of early postoperative feeding with an elemental diet was assessed in 30 patients after major gastrointestinal operations. The patients were allocated at random to conventional treatment (control group) or feeding with the elemental diet (ED group). The clinical and metabolic course of the 15 patients in the ED group was significantly better than that of the controls. Patients in the ED group lost less weight and had a shorter stay in hospital. Negative nitrogen balance was more pronounced in the control group throughout the seven postoperative days. Energy intake was higher in the ED group. Provided elemental feeding is used with caution, it may be given from the first postoperative day. Patients do better metabolically and require shorter stays in hospital.     

Anaerobic oxidation of thiosulfate and elemental sulfur in Thiobacillus denitrificans

Thiobacillus denitrificans strain RT could be grown anaerobically in batch culture on thiosulfate but not on other reduced sulfur compounds like sulfide, elemental sulfur, thiocyanate, polythionates or sulfite. During growth on thiosulfate the assimilated cell sulfur was derived totally from the outer or sulfane sulfur. Thiosulfate oxidation started with a rhodanese type cleavage between sulfane and sulfone sulfur leading to elemental sulfur and sulfite. As long as thiosulfate was present elemental sulfur was transiently accumulated within the cells in a form that could be shown to be more reactive than elemental sulfur present in a hydrophilic sulfur sol, however, less reactive than sulfane sulfur of polythionates or organic and inorganic polysulfides. When thiosulfate had been completely consumed, intracellular elemental sulfur was rapidly oxidized to sulfate with a specific rate of 45 natom S°/min·mg protein. Extracellularly offered elemental sulfur was not oxidized under anaerobic conditions.     

Acidocalcisomes of trypanosomatids have species-specific elemental composition

The elemental composition and stoichiometric profile of elements present in acidocalcisomes of different genera of the Trypanosomatidae family (insect, plant, and mammalian parasites) submitted to parallel cultivation conditions were studied. X-ray microanalysis using transmission electron microscopy in conjunction with a morphometric approach was used to investigate the elemental content, number, distribution, and volumetric density of acidocalcisomes of different species. Microanalytical data showed that the different parasites possess the same elemental composition (oxygen, sodium, magnesium, phosphorus, calcium, iron, and zinc) in their acidocalcisomes. However, the relative concentrations of the elements varied among species, but not within acidocalcisomes of individual species. Iron was detected in acidocalcisomes of all species analyzed, characterizing this element as a constituent of these organelles. Taken together, the results strongly indicate a species-specific composition of acidocalcisomes in trypanosomatid parasites.     

Predation risk, stoichiometric plasticity and ecosystem elemental cycling

It is widely held that herbivore growth and production is limited by dietary nitrogen (N) that in turn constrains ecosystem elemental cycling. Yet, emerging evidence suggests that this conception of limitation may be incomplete, because chronic predation risk heightens herbivore metabolic rate and shifts demand from N-rich proteins to soluble carbohydrate-carbon (C). Because soluble C can be limiting, predation risk may cause ecosystem elemental cycling rates and stoichiometric balance to depend on herbivore physiological plasticity. We report on a stoichiometrically explicit ecosystem model that investigates this problem. The model tracks N, and soluble and recalcitrant C through ecosystem compartments. We evaluate how soluble plant C influences C and N stocks and flows in the presence and absence of predation risk. Without risk, herbivores are limited by N and respire excess C so that plant-soluble C has small effects only on elemental stocks and flows. With predation risk, herbivores are limited by soluble C and release excess N, so plant-soluble C critically influences ecosystem elemental stocks flows. Our results emphasize that expressing ecosystem stoichiometric balance using customary C : N ratios that do not distinguish between soluble and recalcitrant C may not adequately describe limitations on elemental cycling.     

Taxonomic and regional patterns in benthic macroinvertebrate elemental composition in streams

1. Ecological stoichiometry has been used to better understand dynamics in consumer growth and the role of consumer‐recycled nutrients because it focuses on more than one element. Most research has focused on pelagic rather than benthic consumers. Variation in elemental composition among benthic consumer taxa would suggest that taxa differ in their susceptibility to nutrient limitation or in their role in recycling nutrients. 2. We collected benthic macroinvertebrates from streams in two regions (Indiana–Michigan and Wisconsin, U.S.A.) to examine taxonomic and regional variation in benthic macroinvertebrate body carbon (C), nitrogen (N), and phosphorus (P) concentrations and ratios. 3. Elemental composition varied little within taxa common to both regions. In contrast, elemental composition differed greatly among taxa and appeared to be related to phylogeny. The elemental composition of macroinvertebrates clustered into three distinct groups: insects, mollusks, and crustaceans. To a lesser extent, insects and mollusks also differed in elemental composition among genera. 4. Functional feeding groups (FFGs) differed in elemental composition, with predators having a higher N content than other groups. Substantial elemental imbalances between C and N were found between most primary consumers and their likely food sources, and the magnitude of the imbalance depended in part on the FFG. 5. Our results support an assumption of most ecological stoichiometry models that, within a species, the elemental composition of aquatic invertebrates is relatively constant. Variation in elemental composition among taxa at various higher taxonomic levels suggests that susceptibility of stream invertebrates to nutrient limitation and their role in nutrient cycling will strongly depend on phylogeny.     

硫氧化细菌源单质硫的生成、转运和回收

单质硫(硫粒)是硫化物生物氧化的中间产物.按化学计量式精准调控O/S比(溶解氧与硫化物的摩尔比),单质硫可成为硫氧化细菌(Sulfur-oxidizing bacteria,SOB)的主要代谢产物.根据单质硫的分布,单质硫可分为胞内硫粒和胞外硫粒.单质硫由胞内向胞外的跨膜转运过程是泌硫型SOB的重要生理特征.从生物脱硫...     

Constraint-based simulation of multiple interactive elemental cycles in biogeochemical systems

Simulating multiple linked elemental cycles is a frontier in the field of biogeochemistry. The Generalized Algorithm for Nutrient, Growth, Stoichiometric and Thermodynamic Analysis (GANGSTA) is a software framework that automates the instantiation of formalized, user-defined conceptual models of linked elemental cycles as simulation model code. The GANGSTA employs first principles of stoichiometry and thermodynamics to generate models that simulate any suite of elemental cycles, compounds, metabolic processes, and microorganisms. Results demonstrated, e.g., that simulating the oxygen (O) cycle, rather than oxic versus anoxic conditions, fundamentally altered carbon (C) and nitrogen (N) cycling - despite holding the compounds and processes involved in the C and N cycles constant. Additionally, incorporating the sulfur (S) cycle substantively changed C and N cycling, largely via shifts in the O cycle. Thus, emergent dynamics from GANGSTA-derived models can aid in the development of hypotheses to describe the specific mechanisms of interdependence among linked elemental cycles.     

Otolith elemental fingerprints of juvenile Pacific swordfish Xiphias gladius

The trace element composition of young‐of‐the‐year (YOY) juvenile swordfish Xiphias gladius sagittal otoliths were analysed as a preliminary test of the value of otolith elemental fingerprints for determining swordfish nursery ground origins in the central Pacific Ocean. A suite of five elements (Mg, Zn, Sr, Ba and Pb) was assayed with isotope dilution ICP‐MS; all elemental concentrations were roughly comparable to otoliths of other marine fishes. Multivariate analyses of elemental fingerprints based on Ba and Sr revealed differences between sample sites, and the magnitude of the differences increased with latitudinal separation. With more comprehensive sampling of nursery grounds, it should be possible to identify origin of nursery ground for adult swordfish by analysing the YOY juvenile portion of the sagittal otolith.     

嗜酸硫氧化细菌消解元素硫的研究进展

浸矿酸性环境下,金属硫化矿在Fe3+作用下,经过硫代硫酸盐途径或多聚硫化氢途径而分解的过程中导致大量元素硫的累积,进而可能在金属硫化矿表面形成疏水元素硫层,阻碍金属离子的进一步浸出。酸性环境下,惰性元素硫的消解必须借助嗜酸硫氧化细菌来实现。该消解过程包括嗜酸硫氧化细菌对元素硫的吸附、转运以及氧化转化等过程。本文对近年来嗜酸硫氧化细菌消解元素硫过程的相关研究进行了全面评述,认为有关嗜酸硫氧化细菌消解元素硫的分子机制的清晰阐述还有待人们通过对消解过程的各个环节的分子机制进行大量研究来实现。     

Glutathione reductase/glutathione is responsible for cytotoxic elemental sulfur tolerance via polysulfide shuttle in fungi

Fungi that can reduce elemental sulfur to sulfide are widely distributed, but the mechanism and physiological significance of the reaction have been poorly characterized. Here, we purified elemental sulfur-reductase (SR) and cloned its gene from the elemental sulfur-reducing fungus Fusarium oxysporum. We found that NADPH-glutathione reductase (GR) reduces elemental sulfur via glutathione as an intermediate. A loss-of-function mutant of the SR/GR gene generated less sulfide from elemental sulfur than the wild-type strain. Its growth was hypersensitive to elemental sulfur, and it accumulated higher levels of oxidized glutathione, indicating that the GR/glutathione system confers tolerance to cytotoxic elemental sulfur by reducing it to less harmful sulfide. The SR/GR reduced polysulfide as efficiently as elemental sulfur, which implies that soluble polysulfide shuttles reducing equivalents to exocellular insoluble elemental sulfur and generates sulfide. The ubiquitous distribution of the GR/glutathione system together with our findings that GR-deficient mutants derived from Saccharomyces cerevisiae and Aspergillus nidulans reduced less sulfur and that their growth was hypersensitive to elemental sulfur indicated a wide distribution of the system among fungi. These results indicate a novel biological function of the GR/glutathione system in elemental sulfur reduction, which is distinguishable from bacterial and archaeal mechanisms of glutathione- independent sulfur reduction.     

Variation in the elemental content of Eichhornia crassipes

Summary The elemental composition of E. crassipes falls within the range of elemental values reported for other aquatic and terrestrial plants. Concentrations of macronutrients in water hyacinth biomass were not correlated with environmental levels of these nutrients. E. crassipes produces large, dense stands and dominates biogeochemical cycles in many aquatic ecosystems.This research is supported by Contract AT (38-1)-310 between the University of Georgia and the U. S. Atomic Energy Commission.     

Comparison of proprietary elemental and whole-protein diets in unconscious patients with head injury.

Forty men who had sustained head injury were randomly assigned to one of five groups to receive 0.2 g nitrogen/kg body weight/day as either an elemental or a whole-protein diet. Three proprietary elemental and two whole-protein diets were compared. The mean daily nitrogen intake was below 0.2 g/kg in all groups, and was significantly lower in the groups receiving elemental compared with whole-protein diets. Energy intake was significantly different only between one group receiving an elemental and one receiving a whole-protein diet. Mean daily urinary nitrogen excretion was significantly lower in the groups receiving elemental diets, and mean daily nitrogen balance was negative in all groups except one receiving a whole-protein diet. Reduced nitrogen intakes occurred particularly with the elemental diets, which often provoked reflex vomiting or gastric stasis. The need to introduce diets at reduced strength made a negative balance almost inevitable, but nutritional balance seemed to be more readily achieved with the whole-protein diets. More work is needed to assess the relative merits of these proprietary diets compared with tube feeds prepared in hospitals.     

Modelling of sulfur oxidation from elemental sulfur

An elemental S oxidation model has been developed which combines a maximum S release rate with modifiers for temperature and soil moisture conditions. This model has been combined with a pasture growth and CNSP nutrient cycling model to match S oxidation rate to pasture S demand. In two Southern Australian enviroments, 100m elemental S was superior to 200m particles whilst in Northern Australia the 200m particles were superior. These models can be used to match S release to plant demand.     

Microbial oxidation of elemental sulphur in brown soil

Plant and Soil - Brown soil formed from loamy clay was examined for its ability to produce sulphate from added elemental suphur. At higher rates of sulphur applications the pH of a slightly acid...     

Effect of experimental hyperthyroidism on the elemental content of rat hepatocytes

X-ray microanalysis has been used to determine elemental content in the cytoplasm of hepatocytes of hyperthyroid rats in comparison with euthyroid controls. No significant differences were found for any examined element (sodium, phosphorus, sulfur, chlorine, potassium, magnesium and calcium). In contrast to earlier reports from another laboratory, these data indicate that thyroid hormones do not substantially affect elemental content in rat hepatocytes.     

Production of elemental sulfur by green and purple sulfur bacteria

The utilization of sulfide by phototrophic sulfur bacteria temporarily results in the accumulation of elemental sulfur. In the green sulfur bacteria (Chlorobiaceae), the sulfur is deposited outside the cells, whereas in the purple sulfur bacteria (Chromatiaceae) sulfur is found intracellularly. Consequently, in the latter case, sulfur is unattainable for other individuals. Attempts were made to analyze the impact of the formation of extracellular elemental sulfur compared to the deposition of intracellular sulfur.According to the theory of the continuous cultivation of microorganisms, the steady-state concentration of the limiting substrate is unaffected by the reservoir concentration (S _R).It was observed in sulfide-limited continuous cultures ofChlorobium limicola f.thiosulfatophilum that higherS _R values not only resulted in higher steady-state population densities, but also in increased steady-state concentrations of elemental sulfur. Similar phenomena were observed in sulfide-limited cultures ofChromatium vinosum.It was concluded that the elemental sulfur produced byChlorobium, althouth being deposited extracellularly, is not easily available for other individuals, and apparently remains (in part) attached to the cells. The ecological significance of the data is discussed.Non-standard abbreviations RP reducing power - BChl bacteriochlorophyll - N_cell cell material - specific growth rate - {ie52-1} maximal specific growth rate - D dilution rate - K _s saturation constant - s concentration of limiting substrate - S _R same ass but in reservoir bottle - Y yield factor - iS^o intracellular elemental sulfur - eS^o extracellular elemental sulfur - PHB poly-beta-hydroxybutyric acid     

Biphasic behavior of changes in elemental composition during staurosporine-induced apoptosis

Although the identification of events that occur during apoptosis is a fundamental goal of apoptotic cell death research, little is know about the precise sequence of changes in total elemental composition during apoptosis. We evaluated total elemental composition (Na, Mg, P, Cl, S, and K) in relation to molecular and morphological features in human U937 cells induced to undergo apoptosis with staurosporine, an intrinsic pathway activator. To evaluate total elemental content we used electron probe X-ray microanalysis to measure simultaneously all elements from single, individual cells. We observed two phases in the changes in elemental composition (mainly Na, Cl and K). The early phase was characterized by a decrease in intracellular K (P < 0.001) and Cl (P < 0.001) content concomitant with cell shrinkage, and preceded the increase in proteolytic activity associated with the activation of caspase-3. The later phase started with caspase-3 activation, and was characterized by a decrease in the K/Na ratio (P < 0.001) as a consequence of a significant decrease in K and increase in Na content. The inversion of intracellular K and Na content was related with the inhibition of Na⁺/K⁺ ATPase. This later phase was also characterized by a significant increase (P < 0.001) in intracellular Cl with respect to the early phase. In addition, we found a decrease in S content and an increase in the P/S ratio. These distinctive changes coincided with chromatin condensation and DNA fragmentation. Together, these findings support the concept that changes in total elemental composition take place in two phases related with molecular and morphological features during staurosporine-induced apoptosis.