Effects of biochar on copper immobilization and soil microbial communities in a metal-contaminated soil

Purpose

Copper (Cu) contamination has been increasing in land ecosystems. Biochars (BCs) and arbuscular mycorrhizal fungi (AMF) are known to bind metals, and metallophyte can remove metals from soils. Will BC in combination with AMF contain the Cu uptake by a metallophyte growing in a metal-contaminated soil? The objective of this study was to investigate the effects of BCs on the Cu immobilization and over soil microbial communities in a metal-contaminated soil in the presence of AMF and metallophyte.

Materials and methods

Two BCs were produced from chicken manure (CMB) and oat hull (OHB). A Cu-contaminated sandy soil (338 mg kg^?1) was incubated with CMB and OHB (0, 1, and 5 % w/w) for 2 weeks. Metallophyte Oenothera picensis was grown in pots (500 mL) containing the incubated soils in a controlled greenhouse for 6 months. A number of analyses were conducted after the harvest. These include plant biomass weight, microbial basal respiration, and dehydrogenase activity (DHA), AMF root colonization, spore number, and glomalin production; changes in fungal and bacterial communities, Cu fractions in soil phases, and Cu uptake in plant tissues.

Results and discussion

The BCs increased the soil pH, decreased easily exchangeable fraction of Cu, and increased organic matter and residual fraction of Cu. The BCs provided favorable habitat for microorganisms, thereby increasing basal respiration. The CMB increased DHA by ～62 and ～574 %, respectively, for the low and high doses. Similarly, the OHB increased soil microbial activity by ～68 and ～72 %, respectively, for the low and high doses. AMF root colonization, spore number, and total glomalin-related soil protein (GRSP) production increased by ～3, ～2, and ～3 times, respectively, in soils treated with 1 % OHB. Despite being a metalophyte, O. picensis could not uptake Cu efficiently. Root and shoot Cu concentrations decreased or changed insignificantly in most BC treatments.

Conclusions

The results show that the BCs decreased bioavailable Cu, decreased Cu uptake by O. picensis, improved habitat for microorganisms, and enhanced plant growth in Cu-contaminated soil. This suggests that biochars may be utilized to remediate Cu-contaminated soils.

     

Production and characterization of fibroin hydrogel using waste silk fibers

The use of natural resources, especially processing wastes, as low cost and environmentally friendly alternative aiming high value-added applications is a subject of broad interest. Since the Brazilian silk production annually generates a large amount of waste during the silk fibers processing, this work explores the preparation and characterization of silk fibroin hydrogels using spinning waste silk fibers from textile processing and the processed ones. Hydrogels were obtained directly by dialyzing silk fibroin solutions against frequent changes of water until the gelation point and then lyophilized and characterized in terms of their morphology, crystallinity, thermal resistance and secondary structure. X-ray diffraction analysis revealed the presence of β-sheet conformation related to sol-gel transition. FT-IR spectra indicated the coexistence of random coil (silk I) and β-sheet (silk II) structures, with predominance of β-sheet conformation for hydrogels from processed silk fibers. From thermogravimetric analysis the presence of β-sheet secondary conformation was demonstrated by a degradation peak around 292 °C for both hydrogels. Freeze-dried hydrogels presented sheet or leaf like morphology and no significant change was observed among the hydrogels from waste silk fibers and processed ones. These characteristics suggest that silk fibroin hydrogels prepared from spinning waste silk fibers and obtained directly by dialysis can be potential candidates for biomaterials application, such as drug delivery systems and for wound dressings.     

Echinochrome A Treatment Alleviates Atopic Dermatitis-like Skin Lesions in NC/Nga Mice via IL-4 and IL-13 Suppression

Atopic dermatitis (AD) is a chronic inflammatory skin disease in which skin barrier dysfunction leads to dryness, pruritus, and erythematous lesions. AD is triggered by immune imbalance and oxidative stress. Echinochrome A (Ech A), a natural pigment isolated from sea urchins, exerts antioxidant and beneficial effects in various inflammatory disease models. In the present study, we tested whether Ech A treatment alleviated AD-like skin lesions. We examined the anti-inflammatory effect of Ech A on 2,4-dinitrochlorobenzene (DNCB)-induced AD-like lesions in an NC/Nga mouse model. AD-like skin symptoms were induced by treatment with 1% DNCB for 1 week and 0.4% DNCB for 5 weeks in NC/Nga mice. The results showed that Ech A alleviated AD clinical symptoms, such as edema, erythema, and dryness. Treatment with Ech A induced the recovery of epidermis skin lesions as observed histologically. Tewameter^® and Corneometer^® measurements indicated that Ech A treatment reduced transepidermal water loss and improved stratum corneum hydration, respectively. Ech A treatment also inhibited inflammatory-response-induced mast cell infiltration in AD-like skin lesions and suppressed the expression of proinflammatory cytokines, such as interferon-γ, interleukin-4, and interleukin-13. Collectively, these results suggest that Ech A may be beneficial for treating AD owing to its anti-inflammatory effects.     

Near-infrared reflectance spectroscopy (NIRS) for protein, tryptophan, and lysine evaluation in quality protein maize (QPM) breeding programs

Quality protein maize (QPM) has approximately twice the tryptophan (Trp) and lysine (Lys) concentrations in protein compared to normal maize. Because several genetic systems control the protein quality of QPM, it is essential to regularly monitor Trp and/or Lys in breeding programs. Our objective was to examine the potential of near-infrared reflectance spectroscopy (NIRS) to enhance the efficiency of QPM research efforts by partially replacing more expensive and time-consuming wet chemistry analysis. More than 276 maize samples were used to develop NIRS models for protein content (PC), Trp, and Lys. The standard error of prediction (SEP) for the calibration and the coefficient of determination for validation (R(2)(v)) were 0.26 and 0.96 for PC, 0.005 and 0.85 for Trp, and 0.02 and 0.75 for Lys. When the NIRS models were used to evaluate 266 S2 lines from five QPM breeding populations, the coefficients of determination between NIRS and the chemical data were 0.94, 0.76, and 0.80 for PC, Trp, and Lys, respectively. Therefore, the NIRS models can be used to support the QPM breeding efforts.     

Plant species influence microbial diversity and carbon allocation in the rhizosphere

Plant species effects on microbial communities are attributed to changes in microbial community composition and biomass, and may depend on plant species specific differences in the quality of resources (carbon) inputs. We examined the idea that plant-soil feedbacks can be explained by a chance effect, which is the probability of a highly productive or keystone plant species is present in the community and will influence the functions more than the number of species per se. A ¹³C pulse labelling technique was applied to three plant species and a species mixture in a greenhouse experiment to examine the carbon flow from plants to soil microbial communities. The ¹³C label was given as CO₂ to shoots of a legume (Lotus corniculatus), a forb (Plantago lanceolata), a grass (Holcus lanatus) and a mixture of the three species. Microbial phospholipid fatty acids (PLFA) was analysed in order to determine the biomass and composition of the soil microbial community. The incorporation of the stable isotope into soil microorganisms was determined through GC-IRMS analyses of the microbial PLFAs. Plant species identity did not influence the microbial biomass when determined as total carbon of microbial phospholipid fatty acids. However, the labelled carbon showed that the grass monoculture (H. lanatus) and the plant mixture allocated more ¹³C into bacteria and actinomycete biomass than the other plant species. H. lanatus monocultures had also the highest amounts of ¹³C allocated to AM-fungi and saprophytic fungi. The carbon allocation from plants to soil microorganisms in a plant species mixture can thus be explained by the presence of a highly productive species that influence soil functions.     

Carbohydrate tolerance in the fruit‐eating fish Piaractus mesopotamicus (Holmberg, 1887)

Some fish species have a limited ability to metabolize dietary carbohydrates. An important tool for understanding carbohydrate metabolism is the application of the glucose tolerance test, which can be performed orally or intraperitoneally. To evaluate carbohydrate tolerance in the fruit‐eating fish pacu, two experiments were performed, one with oral administration by gavage of three carbohydrate types (glucose, fructose and starch, 2.0 g/kg body weight (BW)) and the other with intraperitoneal injection (IP) of glucose (500 mg/kg BW). Oral glucose resulted in an increase in plasma glucose 2 hr later with the peak at 4 hr (8.30 mmol/L), and return to baseline between 6 and 12 hr; starch administration promoted a peak after 4 hr (7.70 mmol/L), returning to the baseline at 6 hr. The administration of fructose promoted a moderate peak after 2 hr (5.71 mmol/L), and return to baseline for the time points that followed. Elevated serum cholesterol levels were observed 2 and 24 hr after administration of glucose and starch. Hepatic glycogen levels increased within 24 hr, regardless of the type of carbohydrate administered. IP glucose load resulted in a peak of plasma glucose 3 hr post injection (6.91 mmol/L), returning to baseline 6 hr later. There was a reduction in the concentration of triglycerides at 24 hr. The results demonstrate that pacu metabolize both oral (glucose or starch) and intraperitoneal (glucose) carbohydrate loads after 6 hr, suggesting good ability to deal with dietary carbohydrates.     

Haematological effects of 2‐phenoxyethanol and etomidate in carp (Cyprinus carpio L.)

ObjectiveTo evaluate the effects of handling alone versus handling under anaesthesia with 2-phenoxyethanol or etomidate on haematological parameters in carp.Study designProspective, randomized, laboratory experiment.AnimalsSeventy-two juvenile carp (Cyprinus carpio) weighing 35.9 ± 10.4 g were divided into six groups of 12 fish.MethodsEither 2-phenoxyethanol or 2% etomidate were administered to induce deep anaesthesia (0.3 mL L⁻¹ and 0.6 mL L⁻¹, respectively) or deep sedation (0.15 mL L⁻¹ and 0.3 mL L⁻¹, respectively). Fish were handled with and without sedation. Blood was sampled at 1 hour and 1 week post-treatment. Phagocyte oxidative activity [nitrotetrazolium blue reduction test (NBT)] and differential erythrocyte [red blood cell (RBC)] and leukocyte (white blood cell) counts were evaluated.ResultsAt 1 hour after the induction of anaesthesia, haematocrit (Ht) and haemoglobin (Hb) were increased in fish anaesthetized with 2-phenoxyethanol, and mean corpuscular haemoglobin (MCH) was increased in fish anaesthetized with etomidate. At 1 week, an increase in RBC, erythroblastosis, erythrocyte damage, lymphopenia, neutrophilia, monocytosis and thrombocytosis occurred in both groups. Red blood parameters did not change 1 hour after handling alone, but after 1 week Ht, Hb and mean cell volume decreased, whereas MCH concentration (MCHC) and abnormal erythrocytes increased. Lymphopenia, neutrophilia, monocytosis, thrombocytosis and a decrease in NBT occurred. Fish handled under sedation showed an increase in Hb and MCHC followed by a decrease at 1 week in Ht, Hb and MCH, erythroblastosis and increased abnormal erythrocytes. Lymphopenia and neutrophilia were less pronounced than in fish handled without sedation, but a decrease in NBT was noted at 1 week post-treatment.Conclusions and clinical relevanceDeep anaesthesia with 2-phenoxyethanol or etomidate induced significant haematological alterations in juvenile carp. Deep sedation reduced the immediate immunosuppressive effects of handling but did not eliminate longterm effects. These anaesthetics should be avoided during experimental procedures involving haematological measurements. In contexts that require the short-term handling of carp, these drugs should be used with caution in view of their possible side effects.     

Interplay of intra- and intermolecular H-bonding in a progressively solvated macrocyclic peptide

Studying solvation of a large molecule on an atomic level is challenging because of the transient character and inhomogeneity of hydrogen bonding in liquid water. We studied water clusters of a protonated macrocyclic decapeptide, gramicidin S, which were prepared in the gas phase and then cooled to cryogenic temperatures. The experiment spectroscopically tracked fine structural changes of the clusters upon increasing the number of attached water molecules from 1 to 50 and distinguished vibrational fingerprints of different conformers. The data indicate that only the first two water molecules induce a substantial change of the gramicidin S structure by breaking two intramolecular noncovalent bonds. The peptide structure remains largely intact upon further solvation, reflecting the interplay between the strong intramolecular and weaker intermolecular hydrogen bonds.