Overexpression of oHIOMT results in various morphological, anatomical, physiological and molecular changes in switchgrass.

Introduction: Melatonin (N-acetyl-5-methoxytryptamine) is a molecule implicated in multiple biological functions, but exerts contrasting effects on plants owing to concentration differences. Hydroxyindole O-methyltransferase (HIOMT), which catalyzes the last step of melatonin synthesis, plays a crucial role in this context. Methods: Transgenic switchgrass overexpressing oHIOMT with different melatonin levels displayed distinct morphological changes in a concentration-dependent manner. In this study, we divided the transgenic switchgrass into two groups: melatonin-moderate transgenic (MMT) plants and melatonin-rich transgenic (MRT) plants. To determine the concentration-dependent effect of melatonin on switchgrass growth and stress resistance, we conducted comparative morphological, physiological, omics and molecular analyses between MMT, MRT and wild-type (WT) plants. Results: We found that oHIOMT overexpression, with moderate melatonin levels, was crucial in regulating switchgrass growth through changes in cell size rather than cell number. Moderate levels of melatonin were vital in regulating carbon fixation, stomatal development and chlorophyll metabolism. Regarding salt tolerance, melatonin with moderate levels activated numerous defense (e.g. morphological characteristics, anatomical structure, antioxidant enzymatic properties, non-enzymatic capacity and Na+/K+ homeostasis). Additionally, moderate levels of oHIOMT overexpression were sufficient to increase lignin content and alter monolignol compositions with an increase in the S/G lignin ratio. Discussion: Taken together, oHIOMT overexpression in switchgrass with different melatonin levels resulted in morphological, anatomical, physiological and molecular changes in a concentration-dependent manner, which characterized by stimulation at low doses and inhibition at high doses. Our study presents new ideas and clues for further research on the mechanisms of the concentration-dependent effect of melatonin.

Enhanced resistance to heat and fungal infection in transgenic Trichoderma via over-expressing the HSP70 gene.

Heat stress is one of the major abiotic stresses affecting the growth, sporulation, colonization and survival of Trichoderma viride. This study aimed to gain a better insight into the underlying mechanism governing the heat stress response of T. viride Tv-1511. We analysed the transcriptomic changes of Tv-1511 under normal and heat stress conditions using RNA sequencing. We observed that Tv-1511 regulates the biosynthesis of secondary metabolites through a complex network of signalling pathways. Additionally, it significantly activates the anti-oxidant defence system, heat shock proteins and stress-response-related transcription factors in response to heat stress. TvHSP70 was identified as a key gene, and transgenic Tv-1511 overexpressing TvHSP70 (TvHSP70-OE) was generated. We conducted an integrated morphological, physiological and molecular analyses of the TvHSP70-OE and wild-type strains. We observed that TvHSP70 over-expression significantly triggered the growth, anti-oxidant capacity, anti-fungal activity and growth-promoting ability of Tv-1511. Regarding anti-oxidant capacity, TvHSP70 primarily up-regulated genes involved in enzymatic and non-enzymatic anti-oxidant systems. In terms of anti-fungal activity, TvHSP70 primarily activated genes involved in the synthesis of enediyne, anti-fungal and aminoglycoside antibiotics. This study provides a comparative analysis of the functional significance and molecular mechanisms of HSP70 in Trichoderma. These findings provide a valuable foundation for further analyses.

Ordered porous nitrogen-doped carbon with atomically dispersed FeN4 for efficient oxygen reduction reaction in microbial fuel cell.

It is necessary to develop cost-effective platinum group materials (PGM)-free cathode catalysts for the oxygen reduction reaction (ORR) to replace the state-of-the-art noble metal for the commercialization of microbial fuel cells (MFCs). Fe-N-C catalysts are one of the promising candidates for commercial Pt/C. Herein, a new cost-effective and highly stable Fe-N-C catalyst was designed and successfully prepared via a facile process. The catalyst was prepared through one single thermal conversion from Fe-doped ZIF-8 (zeolitic imidazolate framework), a metal-organic framework (MOF) containing well-defined FeN4 coordination. The mesopores in the unique structure of MOF promoted efficient mass transfer, while those arising from the pyrolysis of the MOF produced more active sites. Unlike previous preparation methods, post-treatments were avoided here. As a result, the Fe-N-C cathode had a high ORR activity with a half-wave potential (E1/2) of 0.85 V in a 0.1 M KOH aqueous solution. The classic MFC with this cathodic catalyst provided a maximum power density of up to 1508 mW m-2.

Distribution of Cu fraction in sediments using Suaeda heteroptera - Nereis succinea combination: A greenhouse study.

A knowledge of the total amount of heavy metals is not enough to assess the environmental impact of polluted soils. Therefore, the determination of Cu fractions in sediment is important to evaluate its behavior in the environment and its mobilization capacity. The distribution of Cu (II) fractions in the sediment was studied in a laboratory simulation experiment. The results indicated that the distribution of Cu fractions was related to the concentration of Cu in sediments. In the Suaeda heteroptera group, the content of exchangeable and carbonate-bound were reducing, while the Fe-Mn oxide- and organic matter-bound were basically raising. In the Nereis succinea group, the content of Fe-Mn oxide- and organic matter-bound were from raising to reducing, and the residual was basically reducing with the increasing Cu concentrations. Generally speaking, the existence of N. succinea could enhance the uptake of Cu in the coastal sediment planted with S. heteroptera. When S. heteroptera and N. succinea in combination, effect of S. heteroptera and N. succinea on Cu fractions in sediments was significantly higher than the two working singly.

Treatment of municipal sewage with low carbon-to-nitrogen ratio via simultaneous partial nitrification, anaerobic ammonia oxidation, and denitrification (SNAD) in a non-woven rotating biological contactor.

In this study, a non-woven rotating biological contactor was evaluated for the treatment of municipal sewage via simultaneous partial nitrification, anaerobic ammonia oxidation (anammox), and denitrification (SNAD). Fluorescence in situ hybridization analysis showed that the dominant bacterial group in the aerobic outer layer of the biofilm was ammonia-oxidizing bacteria (65.13%), whereas anammox (47.17%) and denitrifying (38.91%) bacteria were present in the anaerobic inner layer. Response surface methodology was applied to develop mathematical models for the interaction between C/N and dissolved oxygen (DO) for chemical oxygen demand (COD) and total nitrogen (TN) removal. Results showed that the optimum region for SNAD was at C/N = 1.4-2.3 and DO = 0.2-0.8 mg/L. The most optimal operating condition was determined at C/N = 2.3 and DO = 0.2 mg/L, with actual removal rates of COD and TN were 83.12% and 79.13%, respectively, which are in close model consistency with model prediction (84% and 80%).

Comprehensive risk assessment and source identification of selected heavy metals (Cu, Cd, Pb, Zn, Hg, As) in tidal saltmarsh sediments of Shuangtai Estuary, China.

Heavy metals do not degrade and can remain in the environment for a long time. In this study, we analyzed the effects of Cu, Cd, Pb, Zn, Hg, and As, on environmental quality, pollutant enrichment, ecological hazard, and source identification of elements in sediments using data collected from samples taken from Shuangtai tidal wetland. The comprehensive pollution indices were used to assess environmental quality; fuzzy similarity analysis and geoaccumulation index were used to analyze pollution accumulation; correlation matrix, principal component analysis, and clustering analysis were used to analyze pollution source; environmental risk index and ecological risk index were used to assess ecological risk. The results showed that the environmental quality was either clean or almost clean. Pollutant enrichment analysis showed that the four sub-regions had similar pollution-causing metals to the background values of the soil element of the Liao River Plain, which were ranked according to their similarity. Source identification showed that all the elements were correlated. Ecological hazard analysis showed that the environmental risk index in the study area was less than zero, posing a low ecological risk. Ecological risk of the six elements was as follows: As > Cd > Hg > Cu > Pb > Zn.

[Research on Remote Sensing Inversion of Suaeda Salsa's Biomass Based on TSAVI for OLI Band Simulation].

Suaeda salsa(S.salsa) is a typical vegetation of coastal wetland in the north of Liaodong Bay. The S. salsa biomass assessment plays an important role in understanding the ecosystem productivity of coastal wetland and the formation of ecosystem structure and function. Usually the S.salsa coverage is inhomogeneous. The low S.salsa coverage can be found at a natural condition, the soil background has a strong influence on S.salsa spectral data. The Transformed Soil Adjusted Vegetation Index (TSAVI) used as independent variable was derived by the Landsat 8 OLI simulation data. The S.salsa biomass inversion models were built based on the regression analysis of TSAVI and ground measured biomass in this study. The correlation between TSAVI (600~687, 820~880 nm) and biomass was significant, the correlation coefficient was about 0.9, up to 0.92. The results of linear and quadratic models were better than those of logarithmic, exponential and power models, the determination coefficient r2 of linear and quadratic models were 0.83. Combined with F value and operation efficiency, the linear model was the best option for mature S.salsa biomass inversion. The linear model was applied to invert the S.salsa biomass by using the Landsat 8 OLI data in the study area and it was further validated using in-situ data. The correlation coefficient between the in-situ value and retrieved value was 0.962, the relative error was 0.106. For higher S.salsa coverage, the relative error was lower. The relative error of the low-cover S.salsa biomass inversion was around 0.18. The results showed that the established model has good accuracy for different coverage. In addition, with the introduction of ±5% error of soil line parameters a and b, the average relative errors were relatively stable, and the correlation coefficients were reduced, but all the correlative coefficients were above 0.9. The results showed that the established model is stable.

[Study on chemical constituents of Kochia scoparia].

OBJECTIVE: To investigate the chemical constituents of Kochia scoparia. METHODS: The constituents of EtOAc-soluble portion were isolated and purified by silica gel column chromatography. Their structures were identified by spectral features. RESULTS: Twelve compounds were isolated and identified as tectorigenin (1), pratensein (2), 5,2'-dihydroxy-6,7-methylenedioxyisoflavone (3), iriflogenin (4), 5-hydroxy-6, 7-methylenedioxyflavone (5), fumalicacid (6), N-trans-feruloylmethoxytyramine (7), N-transferuloyltyramine (8), stigmasterol (9), oleanolic acid (10), beta-stigmasterol (11), daucosterol (12). CONCLUSION: compounds 1-9 are isolated from this plant for the first time.

[Bioavailability of cadmium in seawater to Paralichthys olivaceus].

With exposure experiment, this paper studied the accumulation and elimination of cadmium (Cd) in the viscera, muscle and gill of Paralichthys olivaceus, and the effects of TOC concentration in seawater on the Cd accumulation. The results showed that when the exposure concentration of Cd was 0.5 mg x L(-1), its accumulation in test tissues increased with time, and reached equilibrium on the 10th day. The accumulation was in order of viscera (147.73 mg x kg(-1) DW) > gill (15.55 mg x kg(-1) DW) > muscle (4.578 mg x kg(-1) DW), which meant that viscera was the main place for Cd accumulation. Determinations after moving the fish into clear seawater on the 13th day of exposure showed that due to depuration, the Cd accumulation in test tissues decreased with time. On the 15th day after moving, the Cd elimination was in order of viscera (80.66%) > gill (73.66%) > muscle (56.84%), suggesting that the Cd accumulation in Paralichthys olivaceus could be reduced to meet safe food standard. The TOC concentration in seawater had a significant effect on Cd accumulation, i.e., the accumulation of Cd decreased significantly with increasing TOC concentration, demonstrating that the TOC in seawater could decrease the bioavailability of cadmium.

[pH of the gill micro-environment of Cyprinus carpio and its effect on the desorption of adsorbed Cu].

pH and CO2 content differences between fish(Cyprinus carpio) gills micro-environment and the ambient environment were investigated using the technique developed by Playle. The effect of the pH change on elutriation of copper sorbed on gibbsite was also studied in view of possible desorption of the metal within the gill micro-environment. It was found that there was no pH difference around pH 8.0 and 0.2-0.4 unit difference was observed between the gills' inspired and the expired water when the ambient pH varied from 8 up to 9.5 or from 8 down to 7.0. Similar trend was detected for CO2. More Cu adsorbed on the gibbsite can be removed by the acidified expired water from the fish gill micro-environment, comparing to the inspired water.