Micro-heterogeneity and aggregation in β2-microglobulin solutions: effects of temperature, pH, and conformational variant addition

We show that beta(2)-microglobulin solutions in physiological conditions contain a tiny fraction of aggregates, which can hardly be filtered out and tend to re-form spontaneously. At physiological pH the fractional amount and size distribution of the latter aggregates do not depend on temperature. Conversely, in the pH range typical of the peri-articular tissue acidosis that often occurs in hemodialysis, temperature increase leads to fast and irreversible growth of the aggregates. Quite similar, but strongly enhanced aggregation effects can be induced even in physiological conditions by adding a very small amount of DeltaN6, a naturally occurring truncated isoform of beta(2)-m known to promote fibrillogenesis.     

DenNit – Experimental analysis and modelling of soil N2O efflux in response on changes of soil water content, soil temperature, soil pH, nutrient availability and the time after rain event

To quantify the effects of soil temperature (T_soil), and relative soil water content (RSWC) on soil N₂O emission we measured N₂O soil efflux with a closed dynamic chamber in situ in the field and from soil cores in a controlled climate chamber experiment. Additionally we analysed the effect of soil acidity, ammonium, and nitrate concentration in the field. The analysis was performed on three meadows, two bare soils and in one forest. We identified soil water content, soil temperature, soil nitrogen content, and pH as the main parameters influencing soil N₂O emission. The response of N₂O emission to soil temperature and relative soil water content was analysed for the field and climate chamber measurements. A non-linear regression model (DenNit) was developed for the field data to describe soil N₂O efflux as a function of soil temperature, soil moisture, pH value, and ammonium and nitrate concentration. The model could explain 81% of the variability in soil N₂O emission of all individual field measurements, except for data with short-term soil water changes, namely during and up to 2 h after rain stopped. We validated the model with an independent dataset. For this additional meadow site 73% of the flux variation could be explained with the model.     

Cascading effects of soil organic and inorganic fertilizers on tri-trophic interactions: Plant–aphid–parasitoid wasp as a study system

Understanding the mechanisms underlying tri-trophic interactions between insect herbivores, their host plants and natural enemies is an important aim in ecology. In the present study, the effect of urea fertilizer and vermicompost on a tri-trophic level cascade, comprising safflower, Carthamus tinctorius, safflower aphid, Uroleucon carthami and its primary parasitoid wasp, Praon yomenae, was investigated. Vermicompost increased the number of leaves, leaf area, fresh weight, dry weight, the total number of aphids and reduced the number of winged aphids and aphid load (Aphid load = number of aphids / plant fresh weight). Only two variables, plant phenol content and relative water content, were not significantly affected by vermicompost. Urea fertilizer had no impact on all variables except a significant effect on plant height. In another experiment, the effect of urea fertilizer and vermicompost on the wasp parasitoid was studied. The number of parasitoid mummies, mummification time, developmental time, the number of emerged adults, sex ratio, percentage of parasitism and hind tibia length was measured. Vermicompost had no significant effect on any of the measured parameters, but urea fertilizer increased the hind tibia length of the parasitoid. Vermicompost increased plant growth parameters and had an indirect and inhibiting effect on the safflower aphid itself. There was evidence of a bottom-up cascade to the third trophic level by adding fertilizers in this system: Urea fertilizer enhanced plant height but seemingly had no impact on the attacking herbivore. It is interesting that the effect of urea can be transferred to the third trophic level, that is parasitoid. This suggests that vermicompost could be used simultaneously with urea fertilizer, because urea fertilizer had a positive impact on the parasitoid and vermicompost had a positive impact on plant growth as well as the ability to reduce aphid load.     

Plant–soil feedback effects on the performance and functional traits of Dodonaea viscosa in a dry-hot valley,China

Plant–soil feedback has been widely studied and may be particularly important in resource-poor areas. However, the roles of direct and indirect biotic effect in affecting plant growth and functional traits in this process still remained unclear. The aim of this study was to explore the roles of soil biota in affecting plant performance and traits by conducting a two-phase feedback experiment in a dry-hot valley, with a conditioning phase during which there were Dodonaea viscosa or no D. viscosa growing in the soil and a feedback phase in which the effect of the conditioned soil biota on D. viscosa performance was measured. Soil N was reduced by the presence of D. viscosa during the conditioning phase. However, D. viscosa showed a positive plant–soil feedback. In the feedback phase, the D. viscosa-conditioned soil increased the stem diameter, total biomass, and leaf dry mass content of D. viscosa, while the specific leaf area was significantly lower in D. viscosa-conditioned soil than that in bare soil. In contrast, soil sterilization had a negative effect on the growth of D. viscosa, with a significant reduction in biomass, especially in D. viscosa-conditioned soil, and soil sterilization significantly increased the root:shoot biomass ratio and litter mass. Furthermore, we showed that although the biota-driven changes in enzyme activities correlated with leaf N and especially P amount, the enzyme activity was not the main reason to promote D. viscosa growth in conditioned soil. These results suggest that the positive biotic feedback effect was superior to the negative nutrient-depleted effect on D. viscosa growth, and the direct biotic feedback effect would drive the positive effect of soil biota to a greater extent than the indirect effect. The positive biotic plant–soil feedback in dry-hot valley plays an important role in ecosystem restoration and helps in understanding plant adaptation to the local environment in this area.

     

Soil–atmosphere exchange of N2O, CO2 and CH4 along a slope of an evergreen broad-leaved forest in southern China

At most sites the magnitude of soil-atmosphere exchange of nitrous dioxide (N₂O), carbon dioxide (CO₂) and methane (CH₄) was estimated based on a few chambers located in a limited area. Topography has been demonstrated to influence the production and consumption of these gases in temperate ecosystems, but this aspect has often been ignored in tropical areas. In this study, we investigated spatial variability of the net fluxes of these gases along a 100 m long slope of a evergreen broadleaved forest in southern China over a whole year. We expected that the lower part of slope would release more N₂O and CO₂, but take up less atmospheric CH₄ than the upper part due to different availability of water and nutrients. Our results showed that the soil moisture (Water Filled Pore Space, WFPS) decreased along the slope from bottom to top as we expected, but among the three gases only N₂O emissions followed this pattern. Annual means of WFPS ranged from 27.7% to 52.7% within the slope, and annual emissions of N₂O ranged from 2.0 to 4.4 kg N ha^?1 year^?1, respectively. These two variables were highly and positively correlated across the slope. Neither potential rates of net N mineralization and nitrification, nor N₂O emissions in the laboratory incubated soils varied with slope positions. Soil CO₂ release and CH₄ uptake appeared to be independent on slope position in this study. Our results suggested that soil water content and associated N₂O emissions are likely to be influenced by topography even in a short slope, which may need to be taken into account in field measurements and modelling.     

Soil water uptake by trees using water stable isotopes (δ2H and δ18O)−a method test regarding soil moisture,texture and carbonate

Aims

Stable isotopes of oxygen and hydrogen are often used to determine plant water uptake depths. We investigated whether and to what extend soil moisture, clay content, and soil calcium carbonate influences the water isotopic composition.

Methods

In the laboratory, dried soil samples varying in clay content were rewetted with different amounts of water of known isotopic composition. Further, we removed soil carbonate from a subset of samples prior to rewetting. Water was extracted from samples via cryogenic vacuum extraction and analysed by mass spectrometry.

Results

The isotopic composition of extracted soil water was similarly depleted in both ¹⁸O and ²H with decreasing soil moisture and increasing clay and carbonate content. Soil carbonate changed the δ¹⁸O composition while δ²H was not affected.

Conclusions

Our results indicate that soil carbonate can cause artifacts for ¹⁸O isotopic composition of soil water. At low soil moisture and high carbonate content this could lead to conflicting results for δ¹⁸O and δ²H in plant water uptake studies.     

Distribution of the hallucinogens N,N-dimethyltryptamine and 5-methoxy-N,N-dimethyltryptamine in rat brain following intraperitoneal injection: application of a new solid-phase extraction LC–APcI–MS–MS–isotope dilution method

A method for the solid-phase extraction (SPE) and liquid chromatographic–atmospheric pressure chemical ionization–mass spectrometric–mass spectrometric–isotope dilution (LC–APcI–MS–MS–ID) analysis of the indole hallucinogens N,N-dimethyltryptamine (DMT) and 5-methoxy DMT (or O-methyl bufotenin, OMB) from rat brain tissue is reported. Rats were administered DMT or OMB by the intraperitoneal route at a dose of 5 mg/kg and sacrificed 15 min post treatment. Brains were dissected into discrete areas and analyzed by the methods described as a demonstration of the procedure’s applicability. The synthesis and use of two new deuterated internal standards for these purposes are also reported.     

Effects of desertification on the C:N:P stoichiometry of soil,microbes, and extracellular enzymes in a desert grassland北大核心CSCD

Aims In order to discuss the underlying mechanism of desertification effect on the ecological stoichiometry of soil, microbes and extracellular enzymes, we studied the changes of soil, soil microbial and extracellular enzyme C:N:P stoichiometry during the desertification process in the desert grassland in Yanchi County, China. Methods The “space-for-time” method was used. Important findings The results demonstrated that: (1) Soil C, N, P contents and soil C:P, N:P significantly decreased, but soil C:N gradually increased with increasing desertification. (2) Soil microbial biomass C (MBC):soil microbial biomass P (MBP), soil microbial biomass N (MBN):MBP and soil β-1,4-glucosidase (BG):β-1,4-N-acetylglucosaminidase (NAG) gradually decreased, soil BG:alkaline phosphatase (AP) and NAG:AP basically showed an increasing trend with increasing desertification. (3) Desertification increased the soil microbial carbon use efficiency (CUE C : N and CUE C : P ) gradually, while soil microbial nitrogen use efficiency (NUE N : C ) and soil microbial phosphorus use efficiency (PUE P : C ) basically decreased. (4) Soil, soil microbial and soil extracellular enzyme C:N stoichiometry (C:N, MBC:MBN, BG:NAG) were significantly negatively correlated with the soil, soil microbial and extracellular enzyme N:P stoichiometry (N:P, MBN:MBP, NAG:AP), the soil and extracellular enzymes C:N (C:N, BG:NAG) were significantly positively correlated with the soil and extracellular enzymes C:P (C:P, BG:AP). Soil N:P was significantly positively correlated with the soil MBN:MBP, but was significantly negatively correlated with the soil NAG:AP. The analysis demonstrated that soil microbial biomass and extracellular enzyme activity changed with soil nutrient during the desertification process in the desert grassland. The co-variation relationship between soil nutrient and C:N:P stoichiometry of microbial-extracellular enzyme provides a theoretical basis for understanding the underlying mechanism of C, N, P cycling in the soil-microbial system in desert grasslands. © 2018 Editorial Office of Chinese Journal of Plant Ecology. All Rights Reserved.     

Oestrogenic effects of ICI 182,780, a putative anti-oestrogen,on the secretion of oxytocin and prostaglandin F2α during oestrous cycle in the intact ewe

The effect of ICI 182,780, oestrogen antagonist, on the concentrations of oxytocin and uterine PGF_2α was investigated in intact Border Leicester Merino cross ewes during the late oestrous cycle. Twelve cyclic ewes (n=6 per group) were randomly assigned to receive, at 6 h intervals, intra-muscular injection of either peanut oil or ICI 182,780 (1.5 mg kg⁻¹ day⁻¹) in oil for 2 days, starting at 1900 h on day 13 until 1300 h on day 15 post-oestrus. Hourly blood samples were collected via a jugular catheter from 0800 h on day 14 for 37 h and then daily over days 16, 17 and 18 post-oestrus. Peripheral plasma concentrations of oxytocin, the metabolite of prostaglandin F_2α, 15-keto-13,14-dihydro-prostaglandin F_2α, (PGFM) and progesterone were measured by radioimmunoassay. All ewes treated with ICI 182,780 exhibited functional luteal regression as indicated by a marked reduction in plasma progesterone concentrations to less than 1000 pg/ml over the period of 18–36 h during sampling period on days 14 and 15 of the oestrous cycle. In five of six vehicle-treated ewes, progesterone concentrations declined between day 16 and day 18 post-oestrus. In the remaining control ewe, progesterone concentrations reach less than 1000 pg/ml within 36 h of the commencement of the sampling period. During the frequent sampling period, the number of oxytocin pulses in the ICI 182,780 treated ewes was significantly higher compared to control ewes (2.7±0.3 vs. 0.8±0.3). The mean amplitude of oxytocin pulses observed was also greater (70.4±19.5 pg/ml) in ewes treated with ICI 182,780, but was not significantly different from control ewes (33.5±12.9 pg/ml). Oxytocin pulses may however have occurred following the initial two ICI 182,780 injections but before commencing blood sampling. The oxytocin pulses were detected at a mean of 3.2±0.2 h following each injection with ICI 182,780 during blood sampling. In the ICI 182,780-treated ewes, the pulsatile pattern of plasma PGFM in jugular blood samples over the 37 h sampling period on days 14 and 15 post-oestrus had a higher amplitude (512.9±158.9 vs. 121.7±78.7 pg/ml) and pulse area (618.1±183.3 vs. 151.5±102.9 (pg/ml)τ) compared to the vehicle-treated ewes (P<0.05) respectively. The average number of PGFM pulses observed per ewe was 3.0±0.7 in the ICI 182,780-treated group and was significantly (P<0.02) higher than the number of pulses (0.5±0.3) observed in ewes treated with vehicle alone. The PGFM pulses were detected at 4.2±0.6 h following each injection with ICI 182,780 during blood sampling. The percentage of PGFM pulses that occurred coincidently with a significant elevation of oxytocin concentrations was 44.4% in ICI 182,780-treated compared to 66.6% in control ewes. We conclude that administration of oestrogen antagonist ICI 182,780 accelerated development of the luteolytic mechanism by enhancing pulsatile secretion of oxytocin and PGFM which suggests that ICI 182,780 acts as an agonist for oxytocin and prostaglandin F_2α release in intact ewes when administered at 1.5 mg/kg/day over Day 13 to 15 post-oestrus.     

Seasonal variation of vegetation productivity over an alpine meadow in the Qinghai–Tibet Plateau in China: modeling the interactions of vegetation productivity, phenology, and the soil freeze–thaw process

Phenology controls the seasonal activities of vegetation on land surfaces and thus plays a fundamental role in regulating photosynthesis and other ecosystem processes. Therefore, accurately simulating phenology and soil processes is critical to ecosystem and climate modeling. In this study, we present an integrated ecosystem model of plant productivity, plant phenology, and the soil freeze–thaw process to (1) improve the quality of simulations of soil thermal regimes and (2) estimate the seasonal variability of plant phenology and its effects on plant productivity in high-altitude seasonal frozen regions. We tested different model configurations and parameterizations, including a refined soil stratification scheme that included unfrozen water in frozen soil, a remotely sensed diagnostic phenology scheme, and a modified prognostic phenology scheme, to describe the seasonal variation in vegetation. After refined soil layering resolution and the inclusion of unfrozen water in frozen soil, the results show that the model adequately reproduced the soil thermal regimes and their interactions observed at the site. The inclusion of unfrozen water in frozen soil was found to have a significant effect on soil moisture simulation during the spring but only a small effect on soil temperature simulation at this site. Moreover, the performance of improved phenology schemes was good. The phenology model accurately predicted the start and end of phenology, and its precise prediction of phenology variation allows an improved simulation of vegetation production.     

Life cycle assessment of California processing tomato: an evaluation of the effects of evolving practices and technologies over a 10-year (2005–2015) timeframe

Purpose

California is the largest US producer of processing tomatoes, generating 96% of all domestic production and nearly 30% of global supply. Processing tomatoes are mostly processed into diced and paste products. Consumers and actors along their supply chains are increasingly interested in understanding their environmental burdens and identifying opportunities for improvements. This study applies life cycle assessment (LCA) to California diced and paste products over a 10-year timeframe to characterize current impacts and historical trends.

Methods

The LCA considers a scope from cradle-to-processing facility gate and accords with relevant Product Category Rules as published by the International EPD® System. Extensive primary data were collected for tomato cultivation for the years 2005 and 2015, and from processing facilities for 2005, 2010, and 2015 to understand the effects of evolving practices and technologies. We estimate crop and regional specific nitrous oxide and nitrate leaching emissions using a biogeochemical model, and the USES-LCA model is used to determine potential impacts from pesticide application. A suite of impact assessment categories is included based on the CML method (only global warming potential and freshwater consumption values are in the abstract).

Results and discussion

The 2015 results of the study indicate that diced tomatoes are responsible for 0.16 kg CO₂e and 71 L of freshwater per kg, and paste is responsible for 0.83 kg CO₂e and 328 L of freshwater per kg. The main opportunities for improvement include natural gas use in the greenhouse phase, energy for irrigation pumping and fertilizer type in the cultivation phase, and natural gas and electricity use in the facility processing phase. These hotspots are consistent with studies of processing tomato in other parts of the world. Evaluating trends over time showed that technological improvements in the industry had reduced life cycle impacts; for example, global warming potential decreased by 12% for paste and 26% for diced products between 2005 and 2015.

Conclusions

Trends over time show increasing efficiency at the cultivation and processing facility stages that have led to reductions in all impact categories evaluated. However, additional opportunities exist beyond efficiency improvements. Fertilizer and pesticide choice are potential opportunities for further reducing impacts. Also, the introduction of renewables in each phase of the supply chain (solar-powered irrigation pumps and onsite solar energy generation for facilities) could reduce the overall supply chain GWP₁₀₀ impacts by 9–10%.

     

Comparison of N losses (NO − 3, N 2O, NO) from surface applied, injected or amended (DCD) pig slurry of an irrigated soil in a Mediterranean climate

Nitrous oxide (N ₂O), nitric oxide (NO), denitrification losses and NO^–₃ leaching from an irrigated sward were quantified under Mediterranean conditions. The effect of injected pig slurry (IPS) with and without the nitrification inhibitor dicyandiamide (DCD) was evaluated and also compared with that of a surface pig slurry application (SPS) and a control treatment (Control) without fertiliser. After application, fluxes of NO and N ₂O peaked from SPS (3.06 mg NO-N m ^–2 d ^–1 and 108 mg N ₂O-N m ^–2 d ^–1) and IPS (3.50 mg NO-N m ^–2 d ^–1 and 105 mg N ₂O-N m ^–2 d ^–1). However, when irrigation was applied, N ₂O and NO emissions declined. The total N ₂O and denitrification losses were slightly large from IPS than from SPS, although the differences were not significant (P < 0.05). Emission of NO was not affected by the method of pig slurry application. DCD inhibited nitrification during the first 20–30 days and reduced N ₂O and NO emissions from pig slurry by at least 46% and 37%, respectively. Considering the 215 days following pig slurry application, the emission factor of N ₂O based on N fertiliser was 1.60% (SPS), 2.95% (IPS), and 0.50% (IPS + DCD). The emission factor for NO was 0.14% (SPS), 0.12% (IPS), and 0.02% (IPS + DCD). Environmental conditions of the crop favoured the denitrification process as the most important source of N ₂O during the experimental period. The differences in the denitrification rate between treatments could be explained by the pattern of water soluble carbon (WSC), that was the highest value in injected pig slurry (with and without DCD). Due to low drainage (5% of water applied), leaching losses of NO₃^– were lower than those of denitrification from the upper soil layer (0–10 cm) in all treatments and especially with IPS + DCD, where the nitrification inhibitor was very efficient in reducing leaching losses.     

The social and economic origins of genetic determinism: a case history of the American Eugenics Movement, 1900–1940 and its lessons for today

Eugenics, the attempt to improve the genetic quality of the human species by ‘better breeding’, developed as a worldwide movement between 1900 and 1940. It was particularly prominent in the United States, Britain and Germany, and in those countries was based on the then-new science of Mendelian genetics. Eugenicists developed research programs to determine the degree to which traits such as Huntington's chorea, blindness, deafness, mental retardation (feeblemindedness), intelligence, alcoholism, szhiophrenia, manic depression, rebelliousness, nomadism, prostitution and feeble-inhibition were genetically determined. Eugenicists were also active in the political arena, lobbying in the United States for immigration restriction and compulsory sterilization laws for those deemed genetically unfit; in Britain they lobbied for incarceration of genetically unfit and in Germany for sterilization and eventually euthanasia. In all these countries one of the major arguments was that of efficiency: that it was inefficient to allow genetic defects to be multiplied and then have to try and deal with the consequences of state care for the offspring. National Socialists called genetically defective individuals ‘useless eaters’ and argued for sterilization or euthanasia on economic grounds. Similar arguments appeared in the United States and Britain as well. At the present time (1997) much research and publicity is being given to claims about a genetic basis for all the same behaviors (alcoholism, manic depression, etc), again in an economic context – care for people with such diseases is costing too much. There is an important lesson to learn from the past: genetic arguments are put forward to mask the true – social and economic – causes of human behavioral defects. This revised version was published online in August 2006 with corrections to the Cover Date.     

pH optimum of the photosystem II H₂O oxidation reaction: effects of PsbO, the manganese-stabilizing protein, Cl- retention, and deprotonation of a component required for O₂ evolution activity

Hydroxide ion inhibits Photosystem II (PSII) activity by extracting Cl(-) from its binding site in the O(2)-evolving complex (OEC) under continuous illumination [Critchley, C., et al. (1982) Biochim. Biophys. Acta 682, 436]. The experiments reported here examine whether two subunits of PsbO, the manganese-stabilizing protein, bound to eukaryotic PSII play a role in protecting the OEC against OH(-) inhibition. The data show that the PSII binding properties of PsbO affect the pH optimum for O(2) evolution activity as well as the Cl(-) affinity of the OEC that decreases with an increasing pH. These results suggest that PsbO functions as a barrier against inhibition of the OEC by OH(-). Through facilitation of efficient retention of Cl(-) in PSII [Popelkova, H., et al. (2008) Biochemistry 47, 12593], PsbO influences the ability of Cl(-) to resist OH(-)-induced release from its site in the OEC. Preventing inhibition by OH(-) allows for normal (short) lifetimes of the S(2) and S(3) states in darkness [Roose, J. L., et al. (2011) Biochemistry 50, 5988] and for maximal steady-state activity by PSII. The data presented here indicate that activation of H(2)O oxidation occurs with a pK(a) of ～6.5, which could be a function of deprotonation of one or more amino acid residues that reside near the OEC active site on the D1 and CP43 intrinsic subunits of the PSII reaction center.     

Effect of tillage and straw return on carbon footprints,soil organic carbon fractions and soil microbial community in different textured soils under rice–wheat rotation: a review

Reviews in Environmental Science and Bio/Technology - Measuring the influence of long-term agricultural tillage practices on soil organic carbon (SOC) is of great importance to farmers and...     

Nitrogen fertilization alters the distribution and fates of photosynthesized carbon in rice–soil systems: a 13C-CO2 pulse labeling study

Plant and Soil - Traits of the plant root system architecture (RSA) play a key role in crop performance. Therefore, architectural root traits are becoming increasingly important in plant...