Enriched Conditions Research Articles

Contributions of microbial necromass and plant lignin to soil organic carbon stock in a paddy field under simulated conditions of long-term elevated CO2 and warming

Global climate change has various fundamental impacts on plant productivity and soil microbial communities, altering the formation and sequestration of soil organic carbon (SOC). However, the effect of climate change on different SOC components such as plant-derived C and microbial-derived C, remains poorly understood. A 3-year field experiment was conducted from 2018 to 2020 to examine the impacts of elevating atmospheric CO2 levels (550 ppm) and warming (+2 °C) on microbial necromass, plant lignin and phospholipid fatty acid (PLFA) in a Chinese rice paddy. Results showed that elevated CO2 and warming conditions increased the SOC stock by 16.5% and 8.6%, respectively. Elevated CO2 increased the accumulation of microbial necromass (mainly fungal) C by 24.6% and total lignin phenols by 15.8%, while also increasing the biomass of fungal PLFAs by 33.4%. In comparison, warming increased the accumulation of microbial necromass C (mainly bacterial necromass) by 11.1% and bacterial biomass by 27.1%, while it decreased total lignin phenols and their contribution to SOC by 8.3% and 15.7%, respectively. The reduction in lignin phenols and their contribution to SOC under warming conditions was mainly attributed to the lower level of plant productivity and increased activities of the enzymes β-1,4-glucosidase, β-cellobiohydrolase and xylanase. This resulted in increased plant residue conversion to microbial necromass in warmed soils. Random forest and correlation analysis indicated that soil pH, fungal biomass, root biomass and C-acquiring enzyme activities were the major factors affecting microbial necromass, while lignin phenols were mainly regulated by the ratio of fungal/bacterial necromass and fungal biomass. Overall, the combined effects of CO2 enrichment and warming conditions increased the storage and sequestration of SOC by enhancing the accumulation of microbial necromass, which was affected by soil properties, plant root C inputs and microbial communities within soil.

Coupled Effect of Nutritional Food Molecules and Lactobacillus reuteri Surface Protein Interaction on the Bacterial Gastrointestinal Tolerance.

Lactobacillus reuteri, which is present in fermented foods, can produce LPxTG motif proteins (LMPs) to help the strain resist gastrointestinal fluid environmental stress and enhance the adherence and colonizing properties. Intestinal nutrient small molecules can interact with LMPs and cooperate with Lactobacillus to exert probiotic effects in the host intestine. However, the mechanism of their correlation with gastrointestinal tolerance needs to be further studied. In this study, different kinds of nutritional food molecules, such as intestinal phenols, sugars, and acids, were screened and the interaction between the LPxTG proteins and small molecules was explored via the molecular docking approach. The docking results showed that phenols and oligosaccharides were more likely to bind to the LPxTG protein (B3XKV5), with the benzene ring, phenolic hydroxyl group, and glycosidic bond in the small molecule more easily binding to the active site of B3XKV5. Furthermore, the gastrointestinal tolerance was enhanced under the rutin, myricetin, quercetin phenols, and stachyose-treated L. reuteri strain groups, especially the phenol group, which revealed the relationship between the molecular interaction of the strain with the small molecules and strain tolerance mechanism. All the findings illustrated the gastrointestinal tolerance escape effect of the Lactobacillus strain under enriched intestinal nutrient small molecular conditions, and they also provide insight regarding the small molecules for the Lactobacillus strain under abnormal growth environments.

The Impact of Puzzle Feeders, Ice-Pops and Artificial Seaweed on Captive Harbour Seals (Phoca vitulina) Behaviour

Environmental enrichment is used in zoos and aquaria to improve animal welfare through the stimulation of naturalistic behaviours and reduction of stereotypic behaviours. This study investigated the impact of new enrichment items on the behaviour of a group of captive adult harbour seals. Data were collected in summer-autumn 2023 using continuous scan sampling and all behaviours one-zero recording method for 1-minute intervals (4 hours/day, 8 days). Under standard enrichment conditions, more than 90% of the seals’ behavioural budget was represented by naturalistic behaviours, with low levels of pattern group swimming, which occurred mainly before the two daily shows. Group swimming decreased and random swimming increased before the seal shows on days with new enrichment, but these differences were not statistically significant. The presence of new enrichment items led to a significant increase in exploration and a significant decrease in group swimming only during the morning periods when the new items were actually present in the enclosure (p<0.05, Kruskal Wallis test). During these periods the seals interacted most frequently with the submersed fish-filled puzzle feeders and least frequently with the floating artificial seaweed. This study concluded that new environmental enrichment may be beneficial even for seals displaying low levels of stereotypic behaviours as it provides more behavioural choices and helps promote active naturalistic exploratory behaviours which may alleviate captivity induced stress and improve welfare.

Optimization of Germination Conditions for Enriched γ-Aminobutyric Acid and Phenolic Compounds of Foxtail Millet Sprouts by Response Surface Methodology.

The optimum germination conditions for foxtail millet sprouts enriched with γ-aminobutyric acid (GABA) and antioxidant polyphenols were investigated. From single-factor experimental results, both the GABA level and total phenolic content (TPC) were more significantly affected by soaking temperature and time, and concentration of sucrose culture solution. Response surface methodology (RSE) was used to optimize the germination conditions of foxtail millet sprouts, where the interaction between soaking temperature and sucrose concentration exhibited a significant (p < 0.05) effect on TPC, and the interaction between soaking time and sucrose concentration displayed a significant (p < 0.05) effect on GABA content. The optimal germination conditions for TPC and GABA enrichment of foxtail millet sprouts were soaking at 31 °C for 4.5 h and germinating at 35 °C with 4.5 g/L sucrose solution for 5 days. Under the optimized conditions, the TPC and GABA content of foxtail millet sprouts were 926.53 milligrams of ferulic acid equivalents per 100 g dry weight (mg FAE/100 g DW) and 259.13 mg/kg, separately, with less difference from the predicted values of 929.44 mg FAE/100 g DW and 263.60 mg/kg, respectively. Collectively, all the individual phenolic compounds increased significantly (p < 0.05) by optimization, except for cis-p-coumaric acid and cis-ferulic acid in bound. The results provide a practical technology for suitable germination conditions to improve the health components of foxtail millet sprouts and increase their added value.

Enrichment conditions and resource potential of coal-rock gas in Ordos Basin, NW China

To reveal the enrichment conditions and resource potential of coal-rock gas in the Ordos Basin, this paper presents a systematic research on the sedimentary environment, distribution, physical properties, reservoir characteristics, gas-bearing characteristics and gas accumulation play of deep coals. The results show that thick coals are widely distributed in the Carboniferous–Permian of the Ordos Basin. The main coal seams Carboniferous 5# and Permian 8# in the Carboniferous–Permian have strong hydrocarbon generation capacity and high thermal evolution degree, which provide abundant materials for the formation of coal-rock gas. Deep coal reservoirs have good physical properties, especially porosity and permeability. Coal seams Carboniferous 5# and Permian 8# exhibit the average porosity of 4.1% and 6.4%, and the average permeability of 8.7×10−3 μm2 and 15.7×10−3 μm2, respectively. Cleats and fissures are developed in the coals, and together with the micropores, constitute the main storage space. With the increase of evolution degree, the micropore volume tends to increase. The development degree of cleats and fissures has a great impact on permeability. The coal reservoirs and their industrial compositions exhibit significantly heterogeneous distribution in the vertical direction. The bright coal seam, which is in the middle and upper section, less affected by ash filling compared with the lower section, and contains well-developed pores and fissures, is a high-quality reservoir interval. The deep coals present good gas-bearing characteristics in Ordos Basin, with the gas content of 7.5–20.0 m3/t, and the proportion of free gas (greater than 10%, mostly 11.0%–55.1%) in coal-rock gas significantly higher than that in shallow coals. The enrichment degree of free gas in deep coals is controlled by the number of macropores and microfractures. The coal rock pressure testing shows that the coal-limestone and coal-mudstone combinations for gas accumulation have good sealing capacity, and the mudstone/limestone (roof)-coal-mudstone (floor) combination generally indicates high coal-rock gas values. The coal-rock gas resources in the Ordos Basin were preliminarily estimated by the volume method to be 22.38×1012 m3, and the main coal-rock gas prospects in the Ordos Basin were defined. In the central-east of the Ordos Basin, Wushenqi, Hengshan–Suide, Yan'an, Zichang, and Yichuan are coal-rock gas prospects for the coal seam #8 of the Benxi Formation, and Linxian West, Mizhi, Yichuan–Huangling, Yulin, and Wushenqi–Hengshan are coal-rock gas prospects for the coal seam #5 of the Shanxi Formation, which are expected to become new areas for increased gas reserves and production.

Organic matter enrichment model of fine-grained rocks in volcanic rift lacustrine basin: A case study of lower submember of second member of Lower Cretaceous Shahezi Formation in Lishu rift depression of Songliao Basin, NE China

Based on sedimentary characteristics of the fine-grained rocks of the lower submember of second member of the Lower Cretaceous Shahezi Formation (K1sh2L) in the Lishu rift depression, combined with methods of organic petrology, analysis of major and trace elements as well as biological marker compound, the enrichment conditions and enrichment model of organic matter in the fine-grained sedimentary rocks in volcanic rift lacustrine basin are investigated. The change of sedimentary paleoenvironment controls the vertical distribution of different lithofacies types in the K1sh2L and divides it into the upper and lower parts. The lower part contains massive siliceous mudstone with bioclast-bearing siliceous mudstone, whereas the upper part is mostly composed of laminated siliceous shale and laminated fine-grained mixed shale. The kerogen types of organic matter in the lower and upper parts are types II2–III and types I–II1, respectively. The organic carbon content in the upper part is higher than that in the lower part generally. The enrichment of organic matter in volcanic rift lacustrine basin is subjected to three favorable conditions. First, continuous enhancement of rifting is the direct factor increasing the paleo-water depth, and the rise of base level leads to the expansion of deep-water mudstone/shale deposition range. Second, relatively strong underwater volcanic eruption and rifting are simultaneous, and such event can provide a lot of nutrients for the lake basin, which is conducive to the bloom of algae, resulting in higher productivity of types I–II1 kerogen. Third, the relatively dry paleoclimate leads to a decrease in input of fresh water and terrestrial materials, including Type III kerogen from terrestrial higher plants, resulting in a water body with higher salinity and anoxic stratification, which is more favorable for preservation of organic matter. The organic matter enrichment model of fine-grained sedimentary rocks of volcanic rift lacustrine basin is established, which is of reference significance to the understanding of the organic matter enrichment mechanism of fine-grained sedimentary rocks of Shahezi Formation in Songliao Basin and even in the northeast China.

Rare elements and non-ferrous metals in the paleogene brown-coal deposits of the Zeya-Bureya sedimentary basin (Amur Region, Far East): accumulation models, enrichment conditions and criteria for assessment of resource potential (a review)

A model has been developed for deposition of rare earth elements with yttrium, trace elements, and non-ferrous metals in platform and activated structures of the Upper Amur region. Genetic types of lanthanide enrichment are considered; lanthanides are shown to concentrate non-uniformly in coal seams and in coal combustion products. Light rare earth elements predominate in coals. The capacity of peat and coal for metal extraction from aqueous solutions was proven. Criteria for a preliminary assessment of coal as a raw material for lanthanides were considered and prospects for their identification were analyzed.

Environmental enrichment and sex, but not n-acetylcysteine, alter extended-access amphetamine self-administration and cue-seeking

There are no approved therapeutics for psychostimulant use and recurrence of psychostimulant use. However, in preclinical rodent models environmental enrichment can decrease psychostimulant self-administration of low unit doses and cue-induced amphetamine seeking. We have previously demonstrated that glutamate-dependent therapeutics are able to alter amphetamine seeking to amphetamine-associated cues only in enriched rats. In the current experiment, we will determine if enrichment can attenuate responding and cue-induced amphetamine seeking during extended access to a high dose of intravenous amphetamine. We will also determine if N-acetylcysteine (NAC), a glutamate dependent therapeutic, can attenuate amphetamine seeking in differentially reared rats. Female and male Sprague-Dawley rats were reared in enriched, isolated, or standard conditions from postnatal day 21–51. Rats were trained to self-administer intravenous amphetamine (0.1 mg/kg/infusion) during twelve 6-hour sessions. During the abstinence period, NAC (100 mg/kg) or saline was administered daily. Following a cue-induced amphetamine-seeking test, astrocyte densities within regions of the medial prefrontal cortex (mPFC) and nucleus accumbens (ACb) were quantified using immunohistochemistry. Environmental enrichment decreased responding for amphetamine and during the cue-induced amphetamine-seeking test. NAC did not attenuate cue-induced amphetamine seeking or alter astrocyte density. Across all groups, female rats self-administered less amphetamine but responded more during cue-induced amphetamine seeking than male rats. While amphetamine increased astrocyte densities within the ACb and mPFC, it did not alter mPFC astrocyte densities in female rats. The results suggest that enrichment can attenuate responding during extended access to a high dose of amphetamine and the associated cues. Sex alters amphetamine-induced changes to astrocyte densities in a regionally specific matter.

Exploring microalgae and endophyte as biostimulants: Antioxidant and anti-inflammatory properties of Cannabis sativa L. sprouts under standard and enrichment conditions

Sprouts from germinated seeds of edible herbaceous plants are richer in bioactive compounds and micronutrients than mature plants. In recent years, the consumption of sprouted seeds in diets and the interest in exploring vegetable sprout's potential beneficial effects on human health has increased. In this work, the five-day-old sprouts of Cannabis sativa L. cultivar “Futura 75” were investigated and characterized. Hemp sprouts were obtained by germination tests under standard and enrichment conditions using the microalgal strain Chlorella sp. C2 and the bacterium Sphingomonas sp. Can_S11. The biochemical properties of hemp sprouts were analyzed for total polyphenol and flavonoid content and antioxidant activities (DPPH, ABTS, FRAP, ORAC, and Fe2+-chelating activity) by in vitro assays. A significant increase in phenolic compounds and greater antioxidant and anti-radical activities were observed for hemp sprouts obtained under enrichment conditions (dry microalgal biomass C2 and the bacterium Can_S11). Additionally, these sprouts and C. sativa seeds demonstrated enhanced protective effects on inflamed A549 cells, effectively mitigating the TNF-α induced changes and reducing the expression of IL-8 and COX-2. Overall, PGP (Plant Growth Promoting) microorganisms and microalgae represent a good strategy to promote the development of hemp sprouts and increase their phytochemical content, and antioxidant and anti-inflammatory activity.

Puzzle feeder as a cognitive enrichment strategy determines long-term welfare improvements in a teleost fish

Providing access to cognitive tasks, such as puzzle feeders, holds promise as enrichment strategy to enhance the welfare of captive animals. Despite the substantial number of teleost fish in captivity, the effects of cognitive enrichments in this group remain relatively unexplored. To address this gap in knowledge, we investigated the response of zebrafish to a puzzle feeder. In the first experiment of this study, zebrafish were presented with the option of a puzzle feeder or freely available food. While the subjects exhibited a preference for the latter option, they demonstrated some interest in the puzzle feeder, continuing to use it even though there was easily accessible food nearby. In a subsequent experiment, zebrafish groups were maintained in either a cognitive enrichment condition, where food was consistently provided through puzzle feeders, or a control condition with no cognitive enrichments. Welfare effects of the treatments were then assessed using standard behavioural indicators in the open-field test (i.e., time spent in the centre of the apparatus; number of entrances in the central sector; swim velocity; erratic swimming). Results unveiled an improvement in three welfare indicators due to cognitive enrichment, becoming apparent approximately 20 days after the treatment. Our study underscores the significance of puzzle feeders as cognitive enrichments in captive fish welfare, although consideration of other welfare indicators and different types of puzzles that elicit a more pronounced attraction is required.

Cesium accumulation and plant growth promotion characteristics of Paecilomyces lilacinus A10 isolated from Brassica juncea L. rhizosphere soil

The combined microbial-plant remediation has increasingly been used to remediate heavy metal-contaminated soil. Some microorganisms could enhance phytoremediation efficiency by solubilizing heavy metal and improve plant growth by producing phytohormones in the heavy metal contaminated soils. In the present study, a strong cesium (Cs)-tolerant fungal strain Paecilomyces lilacinus was identified from soil microorganisms contaminated with Cs, and the enrichment conditions for Cs were optimized. Furthermore, the effects of the A10 fermentation solution on the growth of Indian mustard (Brassica juncea L.) seedlings were investigated. The results indicated that the optimal combination of factors consisted of a culture temperature of 28 °C, pH7.0, initial concentration of Cs at 5.91 g·L−1. The maximum enrichment of Cs in the A10 was up to 75.36 mg·g−1 DW. In addition, the enrichment of Cs in Indian mustard was significantly enhanced by the application of the A10 fermentation solution, and the growth of Indian mustard was promoted under Cs stress. The present study has expanded the repertoire of microbial resources available for facilitating the Cs contaminated soil, thereby enhancing its applicability in the phytoremediation strategies.

Optimization of high-temperature thermal pretreatment conditions for maximum enrichment of lithium and cobalt from spent lithium-ion polymer batteries

Due to their increasingly high demand, lithium-ion batteries (LIBs) will encounter a scarcity of essential resources if recycling is not prioritized. The current pretreatment methods for spent LIBs used in industrial production are inefficient, costly, and hazardous. The study aimed to maximize the yield of lithium and cobalt from the black mass of spent Lithium-ion batteries through an optimized high-temperature thermal pretreatment process, which combined mechanical (direct crushing) and thermal treatments to facilitate the subsequent recovery of these valuable metals. Sieve analysis showed that direct crushing for 2 min resulted in 40.81 % of the anode material in the 4750 + 2500 μm size range, while 5 min of crushing led to a more even distribution, with 28.57 % in the smallest size range (−75 μm). Heat treatment followed by 2 min of crushing concentrated 52.38 % of the anode material in the 4750 + 2500 μm range. For the cathode material, 2 min of direct crushing distributed 24.49 % in the −2500 + 1250 μm range, while 5 min of crushing accumulated 38.80 % in the −75 μm range. Heat treatment and 2 min of crushing resulted in 56.05 % of the cathode material in the −75 μm range, indicating improved liberation. The combination of heat treatment and mechanical treatment effectively liberates and reduces the size of the active materials, resulting in a higher cumulative mass fraction of finer particles (≤630 μm). Heat treatment at 600 °C for 15 min, followed by 2 min of crushing, dissociated current collectors (Al) from the cathode material, minimized the harmful gas emissions and produced fine particles (630 μm) with minimal Al content (0.8 wt%). The optimal heat treatment condition of 600 °C for 35 min achieved complete decomposition of PVDF and enriched 73.49 wt% cobalt and 5.41 wt% lithium in the black mass, superior to previous studies.

CupAR negatively controls the key protein CupA in the carbon acquisition complex NDH–1MS in Synechocystis sp. PCC 6803

The low CO2-inducible NDH complex (NDH-1MS) plays a crucial role in the cyanobacterial CO2-concentrating mechanism. However, the components in this complex and the regulation mechanism are still not completely understood. Using a mutant only with NDH-1MS as active Ci sequestration system, we identified a functional gene sll1736 named as cupAR (CupA Regulator). The cupAR deletion mutant, ΔcupAR, grew faster than the WT under high CO2 (HC) condition, more evidently at low pH. The activities of O2 evolution, CO2 uptake，NDH-1, and the building up of a transthylakoid proton were stimulated in this mutant under HC conditions. The cupAR gene is cotranscribed with the NDH-1S operon (ndhF3-ndhD3-cupA) and encoded protein, which specifically suppresses the transcription level of this operon under HC conditions. Mutation of cupAR significantly upregulated the accumulation of CupA, the key protein of NDH-1MS, under HC condition. CupAR interacted with NdhD3 and NdhF3, the membrane components of NDH-1MS, while accumulation of CupAR was reduced in the ΔndhD3 mutant. Furthermore, CupAR was colocated with CupA in both NDH-1MS complex and NDH-1S subcomplex. On the other hand, deletion of ndhR, a negative regulator of the NDH-1S operon, increased the accumulation of CupAR, whereas deletion of cupAR significantly lowered NdhR. Based on these results, we concluded that CupAR is a novel subunit of NDH-1MS, negatively regulating the activities of CupA and CO2 uptake dependent on NDH-1MS by positive regulation of NdhR under enriched CO2 conditions.

Magnetically attracting hydrogel reshapes iron metabolism for tissue repair.

Ferroptosis, caused by disorders of iron metabolism, plays a critical role in various diseases, making the regulation of iron metabolism essential for tissue repair. In our analysis of degenerated intervertebral disc tissue, we observe a positive correlation between the concentration of extracellular iron ions (ex-iron) and the severity of ferroptosis in intervertebral disc degeneration (IVDD). Hence, inspired by magnets attracting metals, we combine polyether F127 diacrylate (FDA) with tannin (TA) to construct a magnetically attracting hydrogel (FDA-TA). This hydrogel demonstrates the capability to adsorb ex-iron and remodel the iron metabolism of cells. Furthermore, it exhibits good toughness and self-healing properties. Notably, it can activate the PI3K-AKT pathway to inhibit nuclear receptor coactivator 4-mediated ferritinophagy under ex-iron enrichment conditions. The curative effect and related mechanism are further confirmed in vivo. Consequently, on the basis of the pathological mechanism, a targeted hydrogel is designed to reshape iron metabolism, offering insights for tissue repair.

New insights on the degradation of polystyrene and polypropylene by larvae of the superworm Zophobas atratus and gut bacterial consortium enrichments obtained under different culture conditions

This study aims to deepen knowledge of the biodegradation of plastics, focusing on polypropylene (PP) fabric from surgical masks and polystyrene (PS) by larvae of Zophobas atratus as well as of specialized bacterial consortia from their gut, which were obtained in different enrichment conditions (aerobic, anaerobic, presence or absence of combined nitrogen). Plastics ingested by larvae obtained in Spain did not show any signs of oxidation but only limited depolymerization, preferably from the lowest molecular weight chains. Gut microbiota composition changed as an effect of plastic feeding. Such differences were more evident in bacterial enrichment cultures, where the polymer type influenced the composition more than by culture conditions, with an increase in the presence of nitrogen-fixers in anaerobic conditions. PS and PP degradation by different enrichment cultures was confirmed under aerobic and anaerobic conditions by respirometry tests, with anaerobic conditions favouring a more active plastic degradation. In addition, exposure to selected bacterial consortia in aerobiosis induced limited surface oxidation of PS. This possibly indicates that different biochemical routes are being utilized in the anaerobic gut and in aerobic conditions to degrade the polymer.

A Strategy to Enhance Photo-Algal Hydrogen Production Using External H+ Ions in a Dual Photobioreactor

The use of microalgae for direct biohydrogen energy generation exhibits significant promise as an alternative to traditional bio-energy production due to zero-emission of CO2. It is known that during photolysis, algae are capable of producing hydrogen (H2) gas instead of oxygen (O2) under enriched acetate conditions by algal fermentative metabolisms [1]. The utilization of acetate as a practical oxygen regulator in photosystem II (PSII), but the algal hydrogen production was relatively low due to the insufficient H+ ions available in the photobioreactor (PBR) [2]. Therefore, given that hydrogen ions from acetate contribute to H2 production, it is still unclear whether supplying additional external H+ ions can enhance H2 production.Here, we demonstrate a feasibility study on improving algal H2 production using a dual PBR system. This system enables the continuous transfer of H+ ions generated from photolysis to an algal H2 PBR through a proton exchange membrane (PEM), thereby enhancing photo-algal hydrogen production. The maximum H2 production of 108 µmol L-1 was obtained for Chlamydomonas reinhardtii in a single PBR for 15 days at a light intensity of 100 µmol m-2 s-1 [3]. However, by leveraging the external H+ ions supply, the dual PBR system increased photo-algal hydrogen production from 108 up to 760 µmol L-1 for the same period, which is 7 times greater compared to single chamber operation. This indicates that supplying external H+ ions in the operation of the dual PBR is one of the important parameters for improving biohydrogen production. Our findings contribute to the ongoing development of high-performance algal H2 production, offering valuable insights into optimizing the amount of H+ ions for enhanced hydrogen production.[1] Clemens KL, Force DA, Britt RD. Acetate binding at the photosystem II oxygen evolving complex: an S2-state multiline signal ESEEM study. J Am Chem Soc. 2002;124(36):10921-33.[2] Hwang J-H, Church J, Lim J, Lee WH. Photosynthetic biohydrogen production in a wastewater environment and its potential as renewable energy. Energy. 2018;149:222-9.[3] Hwang J-H, Lee WH. Continuous photosynthetic biohydrogen production from acetate-rich wastewater: Influence of light intensity. Int J Hydrogen Energy. 2021;46(42):21812-21.

How nitrate and ammonium impact soil organic carbon transformation with reference to aggregate size

While nitrogen (N) deposition and over-fertilization enrich N in soil, it is unclear how it impacts soil organic carbon (SOC) transformation at the aggregate scale. Herein, a 90-day study reveals the transformation mechanisms of SOC in soil aggregates under nitrate and ammonium enrichment conditions. Results showed that nitrate treatment (NT) and ammonium treatment (AT) significantly increased SOC content by 15.6 % and 18.9 %, respectively. In addition, NT increased SOC accrual in large macro-aggregates (LMA), while AT increased SOC accrual in small macro-aggregates (SMA) and micro-aggregates (MA). Further analysis of pyrolysis products showed that N enrichment drove the transformation of labile soil organic matter (SOM) composition into recalcitrant SOM, with polysaccharides declining from 19–30 % to 2–13 %, while lipids rose from 18–27 % to 33–45 %. LMA and SMA contained more aromatic compounds than MA. This is linked to the inhibition of the expression of C degradation function genes, while almost all genes encoding SOC degradation are down-regulated under N enrichment. In the meantime, NT increased the abundance of genes encoding the degradation of N-containing compounds in LMA. Moreover, NO3− enrichment exerted a higher inhibitory effect on labile SOC degradation while NH4+ enrichment substantially inhibited recalcitrant SOC. Finally, Random Forest analysis confirmed that N enrichment elevated the importance of N-containing compounds' metabolism, which diminished when the size of soil aggregates decreased. In contrast, the importance of genes encoding saccharides and cellulose metabolism increased in smaller aggregates. This study highlights that both N type and aggregate size were determining factors in shaping SOC transformation in the N enrichment process.

Differential rearing alters Fos in the accumbens core and ventral palidum following reinstatement of cocaine seeking in male Sprague-Dawley rats

Rearing rats in environmental enrichment produces a protective effect when exposed to stimulants, as enriched rats display attenuated cocaine seeking during reinstatement. However, less is known about what changes in the brain are responsible for this protective effect. The current study investigated differences in Fos protein expression following reinstatement of cocaine seeking in differentially reared rats. Rats were reared in either enriched (EC) or impoverished (IC) conditions for 30 days, after which rats self-administered cocaine in 2-h sessions. Following self-administration, rats underwent extinction and cue-induced or cocaine-primed reinstatement of cocaine seeking, brains were extracted, and Fos immunohistochemistry was performed. IC rats sought cocaine significantly more than EC rats during cue-induced reinstatement, and cocaine seeking was positively correlated with Fos expression in the nucleus accumbens core and ventral pallidum. IC rats displayed greater Fos expression than EC rats in the accumbens and ventral pallidum, suggesting a role of these areas in the enrichment-induced protective effect.

Plant-soil hydraulic interaction and rhizosphere bacterial community under biochar and CO2 enrichment

The increasing atmospheric CO2 concentration is a global concern that affects the plant-bacteria-soil system. Previous studies have investigated plant growth and bacteria activity under CO2 enrichment. However, the effects of coupled elevated CO2 and biochar amendment on the interactions of soil and medicinal plants are not well understood. This study aims to investigate the medicinal plant-soil hydraulic interactions and rhizosphere bacteria communities under coupled CO2 enrichment and biochar conditions. Two levels of CO2 concentration (400, 1000 ppm) and two biochar dosages (3%, 5% by mass) were considered. Pseudostellaria heterophylla was used as the tested medicinal plant. During plant growth, coupled CO2 enrichment and biochar at 3% and 5% dosage increased the volumetric water content at a matric suction of 33 kPa by 97% and 82% respectively, which indicates enhanced water retention. The transpiration rate of P. heterophylla was slightly reduced by 11–30% with an increase in biochar dosage due to higher total suction, while it was significantly reduced by up to 57% due to CO2 enrichment. In the rhizosphere of P. heterophylla, elevated CO2 (1000 ppm) coupled with 3% biochar dramatically increase the relative abundance of Thaumarchaeota, which played an important role in C and N cycles. Moreover, coupled CO2 enrichment and biochar addition resulted in the highest bacterial richness, while 3% biochar at ambient CO2 induced the highest bacterial diversity. This study provides a basis for understanding the medicinal plant-bacteria-soil system under CO2 enrichment and biochar conditions.

Experience-dependent grooming microstructure alterations and gastrointestinal dysfunction in the SAPAP3 knockout mouse model of compulsive behaviour

BackgroundCompulsive- and anxiety-like behaviour can be efficiently modelled in SAPAP3 knockout (KO) mice, a preclinical model of relevance to obsessive-compulsive disorder (OCD). Although there is emerging evidence in the clinical literature of gastrointestinal dysfunction in OCD, no previous studies have investigated gut function in preclinical models of relevance to OCD. Similarly, the effects of voluntary exercise (EX) or environmental enrichment (EE) have not yet been explored in this context. MethodWe comprehensively phenotyped the SAPAP3 KO mouse model, including the assessment of grooming microstructure, anxiety- and depressive-like behaviour, and gastrointestinal function. Mice were exposed to either standard housing (SH), exercise (EX, provided by giving mice access to running wheels), or environmental enrichment (EE) for 4 weeks to investigate the effects of enriched housing conditions in this animal model relevant to OCD. FindingsOur study is the first to assess grooming microstructure, perseverative locomotor activity, and gastrointestinal function in SAPAP3 KO mice. We are also the first to report a sexually dimorphic effect of grooming in young-adult SAPAP3 KO mice; along with changes to grooming patterning and indicators of gut dysfunction, which occurred in the absence of gut dysbiosis in this model. Overall, we found no beneficial effects of voluntary exercise or environmental enrichment interventions in this mouse model; and unexpectedly, we revealed a deleterious effect of wheel-running exercise on grooming behaviour. We suspect that the detrimental effects of experimental housing in our study may be indicative of off-target effects of stress—a conclusion that warrants further investigation into the effects of chronic stress in this preclinical model of compulsive behaviour.