Inorganic Nitrogen Transport and Assimilation in Pea (Pisum sativum).

The genome sequences of several legume species are now available allowing the comparison of the nitrogen (N) transporter inventories with non-legume species. A survey of the genes encoding inorganic N transporters and the sensing and assimilatory families in pea, revealed similar numbers of genes encoding the primary N assimilatory enzymes to those in other types of plants. Interestingly, we find that pea and Medicago truncatula have fewer members of the NRT2 nitrate transporter family. We suggest that this difference may result from a decreased dependency on soil nitrate acquisition, as legumes have the capacity to derive N from a symbiotic relationship with diazotrophs. Comparison with M. truncatula, indicates that only one of three NRT2s in pea is likely to be functional, possibly indicating less N uptake before nodule formation and N-fixation starts. Pea seeds are large, containing generous amounts of N-rich storage proteins providing a reserve that helps seedling establishment and this may also explain why fewer high affinity nitrate transporters are required. The capacity for nitrate accumulation in the vacuole is another component of assimilation, as it can provide a storage reservoir that supplies the plant when soil N is depleted. Comparing published pea tissue nitrate concentrations with other plants, we find that there is less accumulation of nitrate, even in non-nodulated plants, and that suggests a lower capacity for vacuolar storage. The long-distance transported form of organic N in the phloem is known to be specialized in legumes, with increased amounts of organic N molecules transported, like ureides, allantoin, asparagine and amides in pea. We suggest that, in general, the lower tissue and phloem nitrate levels compared with non-legumes may also result in less requirement for high affinity nitrate transporters. The pattern of N transporter and assimilatory enzyme distribution in pea is discussed and compared with non-legumes with the aim of identifying future breeding targets.

Metabolic potential of the imperfect denitrifier Candidatus Desulfobacillus denitrificans in an anammox bioreactor.

The imperfect denitrifier, Candidatus (Ca.) Desulfobacillus denitrificans, which lacks nitric oxide (NO) reductase, frequently appears in anammox bioreactors depending on the operating conditions. We used genomic and metatranscriptomic analyses to evaluate the metabolic potential of Ca. D. denitrificans and deduce its functional relationships to anammox bacteria (i.e., Ca. Brocadia pituitae). Although Ca. D. denitrificans is hypothesized to supply NO to Ca. B. pituitae as a byproduct of imperfect denitrification, this microbe also possesses hydroxylamine oxidoreductase, which catalyzes the oxidation of hydroxylamine to NO and potentially the reverse reaction. Ca. D. denitrificans can use a range of electron donors for denitrification, including aromatic compounds, glucose, sulfur compounds, and hydrogen, but metatranscriptomic analysis suggested that the major electron donors are aromatic compounds, which inhibit anammox activity. The interrelationship between Ca. D. denitirificans and Ca. B. pituitae via the metabolism of aromatic compounds may govern the population balance of both species. Ca. D. denitrificans also has the potential to fix CO2 via an irregular Calvin cycle and couple denitrification to the oxidation of hydrogen and sulfur compounds under chemolithoautotrophic conditions. This metabolic versatility, which suggests a mixotrophic lifestyle, would facilitate the growth of Ca. D. denitrificans in the anammox bioreactor.

Prediction of permeability across intestinal cell monolayers for 219 disparate chemicals using in vitro experimental coefficients in a pH gradient system and in silico analyses by trivariate linear regressions and machine learning.

For medicines, the apparent membrane permeability coefficients (Papp) across human colorectal carcinoma cell line (Caco-2) monolayers under a pH gradient generally correlate with the fraction absorbed after oral intake. Furthermore, the in vitro Papp values of 29 industrial chemicals were found to have an inverse association with their reported no-observed effect levels for hepatotoxicity in rats. In the current study, we expanded our influx permeability predictions for the 90 previously investigated chemicals to both influx and efflux permeability predictions for 207 diverse primary compounds, along with those for 23 secondary compounds. Trivariate linear regression analysis found that the observed influx and efflux logPapp values determined by in vitro experiments significantly correlated with molecular weights and the octanol-water distribution coefficients at apical and basal pH levels (pH 6.0 and 7.4, respectively) (apical to basal, r = 0.76, n = 198; and basal to apical, r = 0.77, n = 202); the distribution coefficients were estimated in silico. Further, prediction accuracy was enhanced by applying a light gradient boosting machine learning system (LightGBM) to estimate influx and efflux logPapp values that incorporated 17 and 19 in silico chemical descriptors (r = 0.83-0.84, p < 0.001). The determination in vitro and/or prediction in silico of permeability coefficients across intestinal cell monolayers of a diverse range of industrial chemicals/food components/medicines could contribute to the safety evaluations of oral intakes of general chemicals in humans. Such new alternative methods could also reduce the need for animal testing during toxicity assessment.

Ciliary chemosensitivity is enhanced by cilium geometry and motility.

Cilia are hairlike organelles involved in both sensory functions and motility. We discuss the question of whether the location of chemical receptors on cilia provides an advantage in terms of sensitivity and whether motile sensory cilia have a further advantage. Using a simple advection-diffusion model, we compute the capture rates of diffusive molecules on a cilium. Because of its geometry, a non-motile cilium in a quiescent fluid has a capture rate equivalent to a circular absorbing region with ∼4× its surface area. When the cilium is exposed to an external shear flow, the equivalent surface area increases to ∼6×. Alternatively, if the cilium beats in a non-reciprocal way in an otherwise quiescent fluid, its capture rate increases with the beating frequency to the power of 1/3. Altogether, our results show that the protruding geometry of a cilium could be one of the reasons why so many receptors are located on cilia. They also point to the advantage of combining motility with chemical reception.

Imaging inorganic nanomaterial fate down to the organelle level.

Nanotoxicology remains an important and emerging field since only recent years have seen the improvement of biological models and exposure setups toward real-life scenarios. The appropriate analysis of nanomaterial fate in these conditions also required methodological developments in imaging to become sensitive enough and element specific. In the last 2-4 years, impressive breakthroughs have been achieved using electron microscopy, nanoscale secondary ion mass spectrometry, X-ray fluorescence microscopy, or fluorescent sensors. In this review, basics of the approaches and application examples in the study of nanomaterial fate in biological systems will be described to highlight recent successes in the field.

Microbe Profile: Aquifex aeolicus: an extreme heat-loving bacterium that feeds on gases and inorganic chemicals.

The bacterium 'Aquifex aeolicus' is the model organism for the deeply rooted phylum Aquificae. This 'water-maker' is an H2-oxidizing microaerophile that flourishes in extremely hot marine habitats, and it also thrives on the sulphur compounds commonly found in volcanic environments. 'A. aeolicus' has hyper-stable proteins and a fully sequenced genome, with some of its essential metabolic pathways deciphered (including energy conservation). Many of its proteins have also been characterized (especially structurally), including many of the enzymes involved in replication, transcription, RNA processing and cell envelope biosynthesis. Enzymes that are of promise for biotechnological applications have been widely investigated in this species. 'A. aeolicus' has also added to our understanding of the origins of life and evolution.

Stereospecific interactions between chiral inorganic nanomaterials and biological systems.

Chirality is ubiquitous in nature and plays mysterious and essential roles in maintaining key biological and physiological processes. As biological systems display high selectivity for chiral biomolecules, chiral bio-nanoscience has become a popular research field during the last decade. Homochirality, as an essential attribute of natural compounds (l-amino acids, d-sugars, etc.), inspired the emergence of synthetic chiral nanomaterials, which in turn impacted their biological functions and fates. This review is a comprehensive overview of the interactions between chiral inorganic nanostructures and biosystems. We start with the recent progress in biocompatible chiral nanomaterials and focus on stereospecific biological interactions ranging from enantioselective reactions in applications such as sensing and catalysis to chirality-dependent controllable manipulation of cell behaviours and finally to enantiopure nanoplatforms for improved disease therapy. We also discuss the current challenges and future potential of these chiral nanotechnologies in biomedicine and bioengineering, provide strategies to overcome these barriers and offer a future perspective.

Biodegradable Inorganic Nanoparticles for Cancer Theranostics: Insights into the Degradation Behavior.

Inorganic nanoparticles as a versatile nanoplatform have been broadly applied in the diagnosis and treatment of cancers due to their inherent superior physicochemical properties (including magnetic, thermal, optical, and catalytic performance) and excellent functions (e.g., imaging, targeted delivery, and controlled release of drugs) through surface functional modification or ingredient dopant. However, in practical biological applications, inorganic nanomaterials are relatively difficult to degrade and excrete, which induces a long residence time in living organisms and thus may cause adverse effects, such as inflammation and tissue cysts. Therefore, the development of biodegradable inorganic nanomaterials is of great significance for their biomedical application. This Review will focus on the recent advances of degradable inorganic nanoparticles for cancer theranostics with highlight on the degradation mechanism, aiming to offer an in-depth understanding of degradation behavior and related biomedical applications. Finally, key challenges and guidelines will be discussed to explore biodegradable inorganic nanomaterials with minimized toxicity issues, facilitating their potential clinical translation in cancer diagnosis and treatment.

Moulds on cementitious building materials-problems, prevention and future perspectives.

Materials rich in organic and inorganic compounds, such as building materials or paints, represent an excellent substrate for the development of moulds. Several conditions affect mould's growth on cementitious materials, such as nutrient and water availability, temperature, pH and moisture. Microorganisms, and especially moulds, attack these surfaces and contribute to their erosion, thereby reducing the life of the structure itself and negatively affecting human health through inhalation, ingestion and dermal contact with spores. Interventions are based on The European Communities Council Directive 89/106/EEC, that obliges the use of materials, products and building elements that are resistant to fungi and other forms of degradation, and that do not constitute a health risk for users and the environment. This mini-review summarises the current state of problems related to mould growth on cementitious building materials, emphasising new innovative approaches for limiting or contrasting their growth. In particular, the use of nanoparticles and the related nanomaterials as well as the potential use of new "biocides" from natural sources is discussed.

Different dietary trace mineral sources for broiler breeders and their progenies.

The objective of this study was to evaluate the effect of different trace mineral supplementation sources in the diet of broiler breeders on their performance and on their progenies. In total, 128 Cobb 500 broiler breeders were distributed according to a completely randomized experimental design in 2 experimental treatments. The control group was fed a diet supplemented with inorganic trace minerals (ITM), while the other group was fed a diet supplemented with reduced levels of trace minerals in the organic form. Eggs were collected when breeders were 35, 47, and 53 wk old. Their progeny (450 hatchlings) were divided according to trace mineral supplementation source from the maternal diet, creating 2 treatments with 16 replicates of 15 birds each. Organic trace mineral (OTM) supplementation improved broiler breeder performance, as shown by higher egg production and better eggshell quality of OTM-fed hens compared with those fed ITM. Egg fertility and hatchability were not influenced by the treatments. As to progeny performance, higher weight gain, and consequently, better feed conversion ratio, were obtained in the 41-day-old progenies of OTM-fed breeders, independently of hen age. Maternal diet trace mineral source did not affect broiler carcass, breast meat, or leg yields. The results of the present study show that supplementing broiler breeder diets with organic trace mineral sources enhances the performance of breeders and their progenies.

Inorganic nitrate, hypoxia, and the regulation of cardiac mitochondrial respiration-probing the role of PPARα.

Dietary inorganic nitrate prevents aspects of cardiac mitochondrial dysfunction induced by hypoxia, although the mechanism is not completely understood. In both heart and skeletal muscle, nitrate increases fatty acid oxidation capacity, and in the latter case, this involves up-regulation of peroxisome proliferator-activated receptor (PPAR)α expression. Here, we investigated whether dietary nitrate modifies mitochondrial function in the hypoxic heart in a PPARα-dependent manner. Wild-type (WT) mice and mice without PPARα (Ppara-/-) were given water containing 0.7 mM NaCl (control) or 0.7 mM NaNO3 for 35 d. After 7 d, mice were exposed to normoxia or hypoxia (10% O2) for the remainder of the study. Mitochondrial respiratory function and metabolism were assessed in saponin-permeabilized cardiac muscle fibers. Environmental hypoxia suppressed mass-specific mitochondrial respiration and additionally lowered the proportion of respiration supported by fatty acid oxidation by 18% (P < 0.001). This switch away from fatty acid oxidation was reversed by nitrate treatment in hypoxic WT but not Ppara-/- mice, indicating a PPARα-dependent effect. Hypoxia increased hexokinase activity by 33% in all mice, whereas lactate dehydrogenase activity increased by 71% in hypoxic WT but not Ppara-/- mice. Our findings indicate that PPARα plays a key role in mediating cardiac metabolic remodeling in response to both hypoxia and dietary nitrate supplementation.-Horscroft, J. A., O'Brien, K. A., Clark, A. D., Lindsay, R. T., Steel, A. S., Procter, N. E. K., Devaux, J., Frenneaux, M., Harridge, S. D. R., Murray, A. J. Inorganic nitrate, hypoxia, and the regulation of cardiac mitochondrial respiration-probing the role of PPARα.

Spent coffee grounds improve the nutritional value in elements of lettuce (Lactuca sativa L.) and are an ecological alternative to inorganic fertilizers.

The element concentration in lettuces grouped in 5 categories (baby variety, cultivated in agricultural soils with low or high percentages of spent coffee grounds-SCG, without SCG and with NPK) were measured. Lettuces cultivated in agricultural soils amended with SCG had significantly higher levels of several essential (V, Fe, Co, V, and probably Mn and Zn) and toxic elements (Al and probably As), without reaching their toxicological limits. Additionally, blocking of N uptake and therefore plant biomass, and probably Cd absorption from agricultural soil was observed. Organic farming with SCG ameliorates element concentrations in lettuces vs. NPK fertilization. The linear correlations among element uptake and the amendment of SCG could be related with their chelation by some SCG components, such as melanoidins and with the decrease in the soil pH. In conclusion, the addition of SCG produces lettuces with higher element content.

In situ analyses of inorganic nutrient distribution in sweetcorn and maize kernels using synchrotron-based X-ray fluorescence microscopy.

BACKGROUND AND AIMS: Understanding the spatial distribution of inorganic nutrients within edible parts of plant products helps biofortification efforts to identify and focus on specific uptake pathways and storage mechanisms. METHODS: Kernels of sweetcorn (Zea mays) variety 'High zeaxanthin 103146' and maize inbred line 'Thai Floury 2' were harvested at two different maturity stages, and the distributions of K, P, S, Ca, Zn, Fe and Mn were examined in situ using synchrotron-based X-ray fluorescence microscopy. KEY RESULTS: The distribution of inorganic nutrients was largely similar between maize and sweetcorn, but differed markedly depending upon the maturity stage after further embryonic development. The micronutrients Zn, Fe and Mn accumulated primarily in the scutellum of the embryo during early kernel development, while trace amounts of these were found in the aleurone layer at the mature stage. Although P accumulated in the scutellum, there was no direct relationship between the concentrations of P and those of the micronutrients, compared with the linear trend between Zn and Fe concentrations. CONCLUSIONS: This study highlights the important role of the embryo as a micronutrient reserve for sweetcorn and maize kernels, and the need to understand how biofortification efforts can further increase the inorganic nutrient concentration of the embryo for human consumption.

Limited carbon source retards inorganic arsenic release during roxarsone degradation in Shewanella oneidensis microbial fuel cells.

Directly relevant to the toxicity, mobility, and fate of arsenic, the biotransformation of inorganic and organic arsenicals has been extensively concerned, including roxarsone, a widely applied organoarsenical feed additive in poultry industry. Yet, little is known about the transformation details of roxarsone in microbial fuel cells (MFC). In this study, a two-chambered Shewanella oneidensis MR-1 microbial fuel cell was employed to investigate the transformation processes of roxarsone at various carbon source levels. Results show that limited carbon source remarkably inhibited inorganic arsenic release along roxarsone transformation, whereas numerous arsenical species were detected to be released into systems with sufficient carbon source supply, including trivalent and pentavalent inorganic arsenics, monomethylarsonous acid (MMA), and 4-hydroxy-3-aminobenzene arsonic acid (HAPA). Shewanella oneidensis MR-1 was able to cleave the C-As bond of trivalent HAPA yielding inorganic arsenics and MMA, even in the absence of the arsI gene encoding ArsI C-As lyase. We proposed a two-step nitro- and pentavalent-arsenate group reduction pathway for the roxarsone bioelectrochemical transformation. In addition, results indicated that the attached cells onto the electrode surface played a key function in the two-step reduction of roxarsone to trivalent HAPA, whereas planktonic cells were most likely responsible for the C-As bond breakage and the following dearylation. With these qualitative and quantitative estimations, it provides new insights into the mechanistic understanding of the roxarsone biotransformation process in microbial fuel cells, which is important for the biogeochemical cycling of arsenic.

Age alters uptake pattern of organic and inorganic nitrogen by rubber trees.

Several studies have explored plant nutrient acquisition during ecosystem succession, but it remains unclear how age affects nitrogen (N) acquisition by the same tree species. Clarifying the age effect will be beneficial to fertilization management through improving N-use efficiency and reducing the risk of environmental pollution due to NO3- leaching. To clarify the effect of age on N uptake, rubber (Hevea brasiliensis (Willd. ex A. Juss.) Muell. Arg.) plantations of five ages (7, 16, 24, 32 and 49 years) were selected in Xishuangbanna of southern China for brief 15N exposures of intact roots using field hydroponic experiments. 15N-labeled NH4+, NO3- or glycine were applied in this study. All targeted rubber trees uptake rates followed an order of NH4+ > glycine > NO3-. As age increased, NH4+ uptake increased first and then decreased sharply, partly consistent with the pattern of soil NH4+ concentrations. Uptake of glycine decreased first and then increased gradually, while no significant change of NO3- uptake rates existed with increasing age. Overall, rubber trees with ages from 7 to 49 years all showed a preference for NH4+ uptake. Young rubber trees (7 and 16 years) had higher NH4+ and lower glycine preferences than older trees (24, 32 and 49 years). Mycorrhizal colonization rates of rubber trees were higher in intermediately aged plantations (16, 24 and 32 years) than in plantations aged 7 and 49 years. A positive relationship was observed between arbuscular mycorrhizal colonization rates and NO3- preference. The results from this study demonstrate that rubber trees do not change their preference for NH4+ but strongly decreased their reliance on it with age. These findings indicate that the shift of N uptake patterns with age should be taken into account for rubber fertilization management to improve N-use efficiency and reduce the risk of environmental pollution during rubber production.

Molecular basis of differential nitrogen use efficiencies and nitrogen source preferences in contrasting Arabidopsis accessions.

Natural accessions of Arabidopsis thaliana differ in their growth and development, but also vary dramatically in their nitrogen use efficiencies (NUE). The molecular basis for these differences has not been addressed yet. Experiments with five contrasting accessions grown in hydroponics at different levels of inorganic nitrogen confirmed low NUE of Col-0 and higher NUE in Tsu-0. At constant external nitrogen supply, higher NUE was based on nitrogen capture, rather than utilization of nitrogen for shoot biomass. This changed when a limited nitrogen amount was supplied. Nevertheless, the total NUE sequence remained similar. Interestingly, the two most contrasting accessions, Col-0 and Tsu-0, differed in the capture of single inorganic nitrogen sources, reflected by the differential consumption of 15N label from ammonium or nitrate, when supplied together. Tsu-0 acquired more nitrate than Col-0, both in roots and shoots. This preference was directly correlated with the expression of certain nitrogen uptake and assimilation systems in the root. However, early transcriptional responses of the root to nitrate deprivation were similar in both accessions, suggesting that the sensing of the external lack of nitrate was not different in the more nitrogen use efficient accession. Thus, a robust rapid nitrate-deprivation signaling exists in both genotypes.

Characterization of inorganic phosphate transport in the triple-negative breast cancer cell line, MDA-MB-231.

BACKGROUND: Recent studies demonstrate that interstitial inorganic phosphate is significantly elevated in the breast cancer microenvironment as compared to normal tissue. In addition it has been shown that breast cancer cells express high levels of the NaPi-IIb carrier (SLC34A2), suggesting that this carrier may play a role in breast cancer progression. However, the biochemical behavior of inorganic phosphate (Pi) transporter in this cancer type remains elusive. METHODS: In this work, we characterize the kinetic parameters of Pi transport in the aggressive human breast cancer cell line, MDA-MB-231, and correlated Pi transport with cell migration and adhesion. RESULTS: We determined the influence of sodium concentration, pH, metabolic inhibitors, as well as the affinity for inorganic phosphate in Pi transport. We observed that the inorganic phosphate is dependent on sodium transport (K0,5 value = 21.98 mM for NaCl). Furthermore, the transport is modulated by different pH values and increasing concentrations of Pi, following the Michaelis-Menten kinetics (K0,5 = 0.08 mM Pi). PFA, monensin, furosemide and ouabain inhibited Pi transport, cell migration and adhesion. CONCLUSIONS: Taken together, these results showed that the uptake of Pi in MDA-MB-231 cells is modulated by sodium and by regulatory mechanisms of intracellular sodium gradient. General Significance: Pi transport might be regarded as a potential target for therapy against tumor progression.

Biological-inorganic hybrid systems as a generalized platform for chemical production.

An expanding renewable energy market to supplant petrochemicals has motivated synthesis technologies that use renewable feedstocks, such as CO2. Hybrid biological-inorganic systems provide a sustainable, efficient, versatile, and inexpensive chemical synthesis platform. These systems comprise biocompatible electrodes that transduce electrical energy either directly or indirectly into bioavailable energy, such as H2 and NAD(P)H. In combination, specific bacteria use these energetic reducing equivalents to fix CO2 into multi-carbon organic compounds. As hybrid biological-inorganic technologies have developed, the focus has shifted from phenomenological and proof-of-concept discovery towards enhanced energy efficiency, production rate, product scope, and industrial robustness. In this review, we highlight the progress and the state-of-the-art of this field and describe the advantages and challenges involved in designing bio- and chemo- compatible systems.

Membrane interactions and antimicrobial effects of inorganic nanoparticles.

Interactions between nanoparticles and biological membranes are attracting increasing attention in current nanomedicine, and play a key role both for nanotoxicology and for utilizing nanomaterials in diagnostics, drug delivery, functional biomaterials, as well as combinations of these, e.g., in theranostics. In addition, there is considerable current interest in the use of nanomaterials as antimicrobial agents, motivated by increasing resistance development against conventional antibiotics. Here, various nanomaterials offer opportunities for triggered functionalites to combat challenging infections. Although the performance in these diverse applications is governed by a complex interplay between the nanomaterial, the properties of included drugs (if any), and the biological system, nanoparticle-membrane interactions constitute a key initial step and play a key role for the subsequent biological response. In the present overview, the current understanding of inorganic nanomaterials as antimicrobial agents is outlined, with special focus on the interplay between antimicrobial effects and membrane interactions, and how membrane interactions and antimicrobial effects of such materials depend on nanoparticle properties, membrane composition, and external (e.g., light and magnetic) fields.