Deforestation impacts soil biodiversity and ecosystem services worldwide

Deforestation poses a global threat to biodiversity and its capacity to deliver ecosystem services. Yet, the impacts of deforestation on soil biodiversity and its associated ecosystem services remain virtually unknown. We generated a global dataset including 696 paired-site observations to investigate how native forest conversion to other land uses affects soil properties, biodiversity, and functions associated with the delivery of multiple ecosystem services. The conversion of native forests to plantations, grasslands, and croplands resulted in higher bacterial diversity and more homogeneous fungal communities dominated by pathogens and with a lower abundance of symbionts. Such conversions also resulted in significant reductions in carbon storage, nutrient cycling, and soil functional rates related to organic matter decomposition. Responses of the microbial community to deforestation, including bacterial and fungal diversity and fungal guilds, were predominantly regulated by changes in soil pH and total phosphorus. Moreover, we found that soil fungal diversity and functioning in warmer and wetter native forests is especially vulnerable to deforestation. Our work highlights that the loss of native forests to managed ecosystems poses a major global threat to the biodiversity and functioning of soils and their capacity to deliver ecosystem services.

Complete Mitochondrial Genomes of Nedyopus patrioticus: New Insights into the Color Polymorphism of Millipedes

There has been debate about whether individuals with different color phenotypes should have different taxonomic status. In order to determine whether the different color phenotypes of Nedyopus patrioticus require separate taxonomic status or are simply synonyms, here, the complete mitochondrial genomes (mitogenomes) of two different colored N. patrioticus, i.e., red N. patrioticus and white N. patrioticus, are presented. The two mitogenomes were 15,781 bp and 15,798 bp in length, respectively. Each mitogenome contained 13 PCGs, 19 tRNAs, 2 rRNAs, and 1 CR, with a lack of trnI, trnL2, and trnV compared to other Polydesmida species. All genes were located on a single strand in two mitogenomes. Mitochondrial DNA analyses revealed that red N. patrioticus and white N. patrioticus did not show clear evolutionary differences. Furthermore, no significant divergence was discovered by means of base composition analysis. As a result, we suggest that white N. patrioticus might be regarded as a synonym for red N. patrioticus. The current findings confirmed the existence of color polymorphism in N. patrioticus, which provides exciting possibilities for future research. It is necessary to apply a combination of molecular and morphological methods in the taxonomy of millipedes.

Increased fine root production coupled with reduced aboveground production of plantations under a three-year experimental drought

Climate change has led to more frequent and intense droughts. A better understanding of forest production under drought stress is critical for assessing the resilience of forests and their capacity to deliver ecosystem services under climate change. However, the direction and magnitude of drought effects on aboveground and belowground forest ecosystem components remain poorly understood. Here, we conducted a drought experiment including 30 % and 50 % throughfall reduction in a poplar plantation in the eastern coast of China to test how different drought intensities affected aboveground and fine root production. We further investigated the responses of soil physicochemical properties (e.g., soil moisture, soil pH, soil carbon, and soil nitrogen), and microbial properties (e.g., total microbial biomass, fungi:bacteria ratios, and Gram+:Gram- bacteria ratios) to drought. We found that the aboveground production decreased by 12.2 % and 19.3 % following 30 % and 50 % drought intensities, respectively. However, fine root production increased by 21.6 % and 35.1 % under 30 % and 50 % drought intensities, respectively. Moreover, all above- and belowground components exhibited stronger responses to 50 % compared with 30 % drought intensity. Our results provide some of the first direct evidence for simultaneous responses of forest above- and belowground production to moderate and intense droughts, by demonstrating that fine root production is more sensitive than aboveground production to both levels of drought stress.

Fungal necromass is reduced by intensive drought in subsoil but not in topsoil

The frequency and intensity of droughts worldwide are challenging the conservation of soil organic carbon (SOC) pool. Microbial necromass is a key component of SOC, but how it responds to drought at specific soil depths remains largely unknown. Here, we conducted a 3-year field experiment in a forest plantation to investigate the impacts of drought intensities under three treatments (ambient control [CK], moderate drought [30% throughfall removal], and intensive drought [50% throughfall removal]) on soil microbial necromass pools (i.e., bacterial necromass carbon, fungal necromass carbon, and total microbial necromass carbon). We showed that the effects of drought on microbial necromass depended on microbial groups, soil depth, and drought intensity. While moderate drought increased total (+9.1% ± 3.3%) and fungal (+13.5% ± 4.9%) necromass carbon in the topsoil layer (0-15 cm), intensive drought reduced total (-31.6% ± 3.7%) and fungal (-43.6% ± 4.0%) necromass in the subsoil layer (15-30 cm). In contrast, both drought treatments significantly increased the BNC in the topsoil and subsoil. Our results suggested that the effects of drought on the microbial necromass of the subsoil were more pronounced than those of the topsoil. This study highlights the complex responses of microbial necromass to drought events depending on microbial community structure, drought intensity and soil depth with global implications when forecasting carbon cycling under climate change.

Biodegradation of Low Density Polyethylene by the Fungus Cladosporium sp. Recovered from a Landfill Site

Low density polyethylene (LDPE) has been widely used commercially for decades; however, as a non-degradable material, its continuous accumulation has contributed to serious environmental issues. A fungal strain, Cladosporium sp. CPEF-6 exhibiting a significant growth advantage on MSM-LDPE (minimal salt medium), was isolated and selected for biodegradation analysis. LDPE biodegradation was analyzed by weight loss percent, change in pH during fungal growth, environmental scanning electron microscopy (ESEM), and Fourier transformed infrared spectroscopy (FTIR). Inoculation with the strain Cladosporium sp. CPEF-6 resulted in a 0.30 ± 0.06% decrease in the weight of untreated LDPE (U-LDPE). After heat treatment (T-LDPE), the weight loss of LDPE increased significantly and reached 0.43 ± 0.01% after 30 days of culture. The pH of the medium was measured during LDPE degradation to assess the environmental changes caused by enzymes and organic acids secreted by the fungus. The fungal degradation of LDPE sheets was characterized by ESEM analysis of topographical alterations, such as cracks, pits, voids, and roughness. FTIR analysis of U-LDPE and T-LDPE revealed the appearance of novel functional groups associated with hydrocarbon biodegradation as well as changes in the polymer carbon chain, confirming the depolymerization of LDPE. This is the first report demonstrating the capacity of Cladosporium sp. to degrade LDPE, with the expectation that this finding can be used to ameliorate the negative impact of plastics on the environment.

Phosphorus additions imbalance terrestrial ecosystem C:N:P stoichiometry

Carbon (C):nitrogen (N):phosphorus (P) stoichiometry in plants, soils, and microbial biomass influences productivity and nutrient cycling in terrestrial ecosystems. Anthropogenic inputs of P to ecosystems are increasing; however, our understanding of the impacts of P addition on terrestrial ecosystem C:N:P ratios remains elusive. By conducting a meta-analysis with 1413 paired observations from 121 publications, we showed that P addition significantly decreased plant, soil, and microbial biomass N:P and C:P ratios, but had negligible effects on C:N ratios. The reductions in N:P and C:P ratios became more evident as the P application rates and experimental duration increased. The P addition effects on terrestrial ecosystem C:N:P stoichiometry did not vary with ecosystem types or climates. Moreover, the responses of N:P and C:P ratios in soil and microbial biomass were associated with the responses of soil pH and fungi:bacteria ratios. Additionally, P additions increased net primary productivity, microbial biomass, soil respiration, N mineralization, and N nitrification, but decreased ammonium and nitrate contents. Decreases in plant N:P and C:P ratios were both negatively correlated to net primary productivity and soil respiration, but positively correlated to ammonium and nitrate contents; microbial biomass, soil respiration, ammonium contents, and nitrate contents all increased with declining soil N:P and C:P ratios. Our findings highlight that P additions could imbalance C:N:P stoichiometry and potentially impact the terrestrial ecosystem functions.

Soil nutrients and plant diversity affect ectomycorrhizal fungal community structure and functional traits across three subalpine coniferous forests

The symbiotic relationship between ectomycorrhizal fungi (EMF) and the roots of host plants is significantly important in regulating the health and stability of ecosystems, especially of those such as the climate warming affected subalpine forest ecosystems. Therefore, from the coniferous forest systems located in the Southern Qinghai-Tibetan Plateau, root tips from three forest tree species: Pinus wallichiana, Abies spectabilis and Picea spinulosa, were collected to look for the local causes of EMF community composition and diversity patterns. The EMF colonization rate, diversity and taxonomic community structure were determined by morphotyping and sanger sequencing of the fungal ITS gene from the root tip samples. Soil exploration types were identified based on the morphologies of the ectomycorrhizas, coupled with soil properties analysis and plant diversity survey. Contrasting patterns of EMF community and functional diversity were found across the studied three forests types dominated by different coniferous tree species. In terms of associations between soil and EMF properties, the total phosphorus (TP) and nitrate (NO₃⁻) contents in soil negatively correlated with the colonization rate and the Shannon diversity index of EMF in contrast to the positive relationship between TP and EMF richness. The soil total nitrogen (TN), ammonium (NH₄⁺) and plant diversity together caused 57.6% of the total variations in the EMF taxonomic community structure at the three investigated forest systems. Whereas based on the soil exploration types alone, NH₄⁺ and TN explained 74.2% of variance in the EMF community structures. Overall, the findings of this study leverage our understanding of EMF dynamics and local influencing factors in coniferous forests dominated by different tree species within the subalpine climatic zone.

Genetic Diversity and Population Structure of Spirobolus bungii as Revealed by Mitochondrial DNA Sequences

Soil macrofauna, such as Spirobolus bungii, are an important component of ecosystems. However, systematic studies of the genetic diversity, population genetic structure, and the potential factors affecting the genetic differentiation of S. bungii are lacking. We performed a population genetic study of 166 individuals from the mountains to the south of the Yangtze River, north of the Yangtze River in Nanjing city, and near Tianjin city, in order to investigate the correlations between geographical distance and genetic diversity. A total of 1182 bp of COX2 and Cytb gene sequences of mitochondrial DNA, and 700 bp of the 18S rRNA gene sequence were analyzed. There were two haplotypes and one variable site in the 18S rRNA gene, and 28 haplotypes and 78 variable sites in the COX2 and Cytb genes. In this study, the 18S rRNA gene was used for species identification, and mtDNA (concatenated sequences with Cytb and COX2) was used for population genetic analysis. Structure cluster analysis indicated that the genetic structures of the different populations of S. bungii tended to be consistent at small geographical scales. Phylogenetic trees revealed that the haplotypes were clearly divided into three branches: the area south of the Yangtze River, the area to the north of the Yangtze River in Nanjing, and the area in Tianjin. Large geographical barriers and long geographical distance significantly blocked gene flow between populations of S. bungii. Our results provide a basic theoretical basis for subsequent studies of millipede taxonomy and population genetic evolution.

'biogeom': An R package for simulating and fitting natural shapes

Many natural objects exhibit radial or axial symmetry in a single plane. However, a universal tool for simulating and fitting the shapes of such objects is lacking. Herein, we present an R package called 'biogeom' that simulates and fits many shapes found in nature. The package incorporates novel universal parametric equations that generate the profiles of bird eggs, flowers, linear and lanceolate leaves, seeds, starfish, and tree-rings, and three growth-rate equations that generate the profiles of ovate leaves and the ontogenetic growth curves of animals and plants. 'biogeom' includes several empirical datasets comprising the boundary coordinates of bird eggs, fruits, lanceolate and ovate leaves, tree rings, seeds, and sea stars. The package can also be applied to other kinds of natural shapes similar to those in the datasets. In addition, the package includes sigmoid curves derived from the three growth-rate equations, which can be used to model animal and plant growth trajectories and predict the times associated with maximum growth rate. 'biogeom' can quantify the intra- or interspecific similarity of natural outlines, and it provides quantitative information of shape and ontogenetic modification of shape with important ecological and evolutionary implications for the growth and form of the living world.

A Method to Reduce off-Targets in CRISPR/Cas9 System in Plants

One of the strategies to reduce the off-target mutations in CRISPR/Cas9 system is to use the temperature-independent gene transformation method. Mesoporous silica nanoparticles (MSNs)-gene delivery system is temperature-independent; thus, it can transfer the interesting plasmid (pDNA) to the target plant at different temperatures, including 37 °C. Due to the high activity of SpCas9 at 37 °C compared to lower temperatures, on-target mutagenesis increases at 37 °C. Therefore, we describe the synthesis of the functionalized MSNs with the particle size of less than 40 nm, binding pDNA to the MSNs, and transferring of the pDNA-MSNs into the target plants.

Incapability of biochar to mitigate biogas slurry induced N2O emissions: Field investigations after 7 years of biochar application in a poplar plantation

Nitrous oxide (N₂O) is a potent atmospheric greenhouse gas that is largely emitted from soils due to the enhanced use of reactive nitrogen in agriculture and plantations. In this study, we evaluated the N₂O mitigation ability of biochar after 7 years of application in a poplar plantation. The field experiment was based on combinations of three biochar (0, 80, and 120 t ha^-1) and four biogas slurry (0, 125, 250, and 375 m³ ha^-1) rates following a factorial design. N₂O flux rates were measured for seven consecutive months using in situ static chambers. Soil physicochemical characteristics, potential nitrification rate (PNR), denitrification (DEA), and N₂O reduction were recorded once each in September 2019 and January 2020 via lab incubations. In addition, qPCR assays were used to assess the abundance of key nitrifying and denitrifying functional genes. Biochar application after 7 years had no significant effects on N₂O flux rates, PNR, and DEA rates. However, a triggering effect of biogas slurry on soil N₂O emission was observed, although there was no correlation between biogas slurry rates and N₂O emission rates. Factorial ANOVA showed a significant effect of biogas slurry and its interaction with biochar on the relative abundance of bacterial denitrifying and nitrifying functional genes. Additionally, significant correlations of N₂O emission rates with PNR rates and NO₃^- concentration indicated that nitrification was the dominant pathway of N₂O emission. Thus, a single biochar application did not mitigate N₂O emission rates induced by biogas slurry on a long-term scale.

Toxic effects of 2,4,4'- trichlorobiphenyl (PCB-28) on growth, photosynthesis characteristics and antioxidant defense system of Lemna minor L

Polychlorinated biphenyls (PCBs) are a common category of persistent man-made organic pollutants that are widespread in the ambient environment. Although Lemna minor L. is an extensively applied plant for aquatic remediation in ecotoxicology research worldwide, little is known regarding its responses to the potentially toxic effects of PCBs. For this study, a 14-day dissolved exposure was conducted to explore the effects of 2,4,4'- trichlorobiphenyl (PCB-28) on the growth, photosynthesis characteristics and antioxidant defense system of L. minor plants. We found that 100 and 200 μg/L of PCB-28 decreased the fresh weight, chlorophyll and protein content, and activities of superoxide dismutase, peroxidase, glutathione S-transferase, and nitroreductase, whereas plasma membrane permeability, and the malondialdehyde and reactive oxygen species concentrations were increased. However, it was observed that 5 and 20 μg/L of PCB-28 had no significant effects on these physiological indices. The ultra-structure of chloroplast demonstrated that 100 and 200 μg/L PCB-28 severely damaged the chloroplast structures. Moreover, correlation analysis revealed that the content of reactive oxygen species had negative correlations with the fresh weight, chlorophyll and protein content, as well as the activities of superoxide dismutase, peroxidase, glutathione S-transferase, and nitroreductase, but had positive correlations with the malondialdehyde content and plasma membrane permeability. This work provides valuable data toward elucidating the physiology and biochemistry of PCBs induced phytotoxicity.

Meta-analysis shows non-uniform responses of above- and belowground productivity to drought

Terrestrial productivity underpins ecosystem carbon (C) cycling and multi-trophic diversity. Despite the negative impacts of drought on terrestrial C cycling, our understanding of the responses of above- and belowground productivity to drought remains incomplete. Here, we synthesized the responses of terrestrial productivity and soil factors (e.g., soil moisture, soil pH, soil C, soil nitrogen (N), soil C:N, fungi:bacteria ratio, and microbial biomass C) to drought via a global meta-analysis of 734 observations from 107 studies. Our results revealed that the productivity variables above- and belowground (i.e., net primary productivity, aboveground net primary productivity, belowground net primary productivity, total biomass, aboveground biomass, root biomass, gross ecosystem productivity, and net ecosystem productivity) were decreased across all ecosystems. However, drought did not significantly affect litter mass across all ecosystems, and the responses of above- and belowground productivity to drought were non-uniform. Furthermore, the responses of these productivity variables to drought were more pronounced with drought intensity and duration, and consistent across ecosystem types and background climates. Drought significantly decreased soil moisture, soil C concentrations, soil C:N ratios, and microbial biomass C, whereas it enhanced soil pH values and fungi:bacteria ratios. Moreover, the negative effects of drought on above- and belowground productivity variables were correlated mostly with the response of soil pH to drought among all soil factors. Our study indicated that litter biomass, which mostly represents productivity levels via traditional ecosystem models, was not able to predict the responses of terrestrial ecosystem productivity to drought. The strong relationship between the responses of soil pH and terrestrial productivity to drought suggests that the incorporation of soil pH into Earth system models might facilitate the prediction of terrestrial C cycling and its feedbacks to drought.

Genetic Diversity and Population Structure of Metaphire vulgaris Based on the Mitochondrial COI Gene and Microsatellites

The earthworm species Metaphire vulgaris (a member of the Clitellata class) is widely distributed across China, and has important ecological functions and medicinal value. However, investigations into its genetic diversity and differentiation are scarce. Consequently, we evaluated the genetic diversity of five populations of M. vulgaris (GM, HD, NYYZ, QDDY, and QDY) in Yancheng, China via the mitochondrial COI gene and the novel microsatellites developed there. A total of nine haplotypes were obtained by sequencing the mitochondrial COI gene, among which NYYZ and QDDY populations had the greatest number of haplotypes (nh = 5). Further, the nucleotide diversity ranged from 0.00437 to 0.1243. The neighbor-joining trees and the TCS network of haplotypes indicated that earthworm populations within close geographical range were not genetically isolated at these small scale distances. Results of the identification of microsatellite molecular markers revealed that the allele number in 12 microsatellite loci ranged from 4 to 13. The observed heterozygosity ranged from 0.151 to 0.644, whereas the expected heterozygosity ranged from 0.213 to 0.847. The polymorphism data content of most sites was >0.5, which indicated that the designed sites had high polymorphism. Structural analysis results indicated that GM, HD, and NYYZ had similar genetic structures across the five populations. The Nei's genetic distance between HD and NYYZ populations was the smallest (D s = 0.0624), whereas that between HD and QDY populations was the largest (D s = 0.2364). The UPGMA tree showed that HD were initially grouped with NYYZ, followed by GM, and then with QDDY. Furthermore, cross-species amplification tests were conducted for Metaphire guillelmi, which indicated that the presented markers were usable for this species. This study comprised a preliminary study on the genetic diversity of M. vulgaris, which provides basic data for future investigations into this species.

Identification, evolution, expression, and docking studies of fatty acid desaturase genes in wheat (Triticum aestivum L.)

Backgrounds

Fatty acid desaturases (FADs) introduce a double bond into the fatty acids acyl chain resulting in unsaturated fatty acids that have essential roles in plant development and response to biotic and abiotic stresses. Wheat germ oil, one of the important by-products of wheat, can be a good alternative for edible oils with clinical advantages due to the high amount of unsaturated fatty acids. Therefore, we performed a genome-wide analysis of the wheat FAD gene family (TaFADs).

Results

68 FAD genes were identified from the wheat genome. Based on the phylogenetic analysis, wheat FADs clustered into five subfamilies, including FAB2, FAD2/FAD6, FAD4, DES/SLD, and FAD3/FAD7/FAD8. The TaFADs were distributed on chromosomes 2A-7B with 0 to 10 introns. The Ka/Ks ratio was less than one for most of the duplicated pair genes revealed that the function of the genes had been maintained during the evolution. Several cis-acting elements related to hormones and stresses in the TaFADs promoters indicated the role of these genes in plant development and responses to environmental stresses. Likewise, 72 SSRs and 91 miRNAs in 36 and 47 TaFADs have been identified. According to RNA-seq data analysis, the highest expression in all developmental stages and tissues was related to TaFAB2.5, TaFAB2.12, TaFAB2.15, TaFAB2.17, TaFAB2.20, TaFAD2.1, TaFAD2.6, and TaFAD2.8 genes while the highest expression in response to temperature stress was related to TaFAD2.6, TaFAD2.8, TaFAB2.15, TaFAB2.17, and TaFAB2.20. Furthermore, docking simulations revealed several residues in the active site of TaFAD2.6 and TaFAD2.8 in close contact with the docked oleic acid that could be useful in future site-directed mutagenesis studies to increase the catalytic efficiency of them and subsequently improve agronomic quality and tolerance of wheat against environmental stresses.

Conclusions

This study provides comprehensive information that can lead to the detection of candidate genes for wheat genetic modification.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12864-020-07199-1.

Response of Plants to Water Stress: A Meta-Analysis

Plants are key to the functionality of many ecosystem processes. The duration and intensity of water stress are anticipated to increase in the future; however, a detailed elucidation of the responses of plants to water stress remains incomplete. For this study, we present a meta-analysis derived from the 1,301 paired observations of 84 studies to evaluate the responses of plants to water stress. The results revealed that although water stress inhibited plant growth and photosynthesis, it increased reactive oxygen species (ROS), plasma membrane permeability, enzymatic antioxidants, and non-enzymatic antioxidants. Importantly, these responses generally increased with the intensity and duration of water stress, with a more pronounced decrease in ROS anticipated over time. Our findings suggested that the overproduction of ROS was the primary mechanism behind the responses of plants to water stress, where plants appeared to acclimatize to water stress, to some extent, over time. Our synthesis provides a framework for better understanding the responses and mechanisms of plants under drought conditions.

Characterization of the complete mitochondrial genome of Drawida gisti (Metagynophora, Moniligastridae) and comparison with other Metagynophora species

Here, the complete mitochondrial genome (mitogenome) of Drawida gisti was sequenced and compared with the mitogenomes of other Metagynophora species. The circular mitogenome was 14,648 bp in length and contained two ribosomal RNA genes (rRNAs), 13 protein-coding genes (PCGs), and 22 transfer RNA genes (tRNAs). The types of constitutive genes and the direction of the coding strand that appeared in Drawida mitogenome were identical to those observed in other Metagynophora species, except for a missing lengthy non-coding region. The conservative relationships between Drawida species were supported by the overall analyses of 13 PCGs, two rRNAs, and 22 tRNAs. A comparison of the Metagynophora mitogenomes revealed that the ATP8 gene possessed the highest polymorphism among the 13 PCGs and two rRNAs. Phylogenetic analysis suggested that the Moniligastridae contained Drawida, which is a primitive Metagynophora group. Our study provides a step forward toward elucidating the evolutionary linkages within Drawida and even Metagynophora.

Responses of plants to polybrominated diphenyl ethers (PBDEs) induced phytotoxicity: A hierarchical meta-analysis

Biologists have extensively investigated the toxicity of polybrominated diphenyl ethers (PBDEs) on plants in ecosystems, where experiments revealed that PBDEs can promote, inhibit, or have no significant effects on the physiological and biochemical functionality of plants. These studies have stimulated many theoretical works that aimed to elucidate the differences in the toxicity of PBDEs on various plants. However, there has been no quantitative attempt to reconcile theory with the results of empirical experiments. To close this gap between theory and experiments, we conducted a hierarchical meta-analysis to examine the toxicity of PBDEs on plants and confirmed potential sources of variation across numerous studies. Through the analysis of 1299 observations garnered from 41 studies, we revealed the significant toxicity of PBDEs on plants. This result was verified to be robust and showed no signs of bias. Our study affirmed that functional indexes can contribute to variations that lead to the toxicity of PBDEs on various plants. Furthermore, we found that lower congeners PBDEs were more toxic to plants than higher congeners PBDEs, and higher plants were more resistant to PBDEs induced phytotoxicity than lower plants. For interactive effects, only specific PBDEs concentrations had significant effects on glutathione S-transferase activities, and experimental durations had no significant impacts on any functional indexes. These results reconciled empirical studies and assisted us with elucidating the ecotoxicology of PBDEs induced phytotoxicity.

Feasible Green Strategy for the Quantitative Bioaccumulation of Heavy Metals by Lemna minor: Application of the Self-Thinning Law

This study involved the development of mathematical linear regression models to describe the relationships between mean plant biomass (M) and population density (D), M and frond diameter (L), frond numbers (N) and L of Lemna minor under different initial population densities (3200, 4450, and 6400 plants/m²), respectively, from the perspective of the self-thinning law. Our results revealed that the value of the allometric exponents for M and D were - 3/2. Further, the concentrations of Zn, Pb, Cu, Fe, and Ni accumulated in L. minor plants were 0.86, 0.32, 0.36, 0.62, and 0.39 mg/kg, respectively. Based on these developed equations and the heavy metal accumulations by L. minor, the phytoremediation capacity of L. minor was quantified via its frond diameters. Overall, the present study provides a cost-effective green method for managing the phytoremediation of heavy metal-contaminated aquatic environments.

Microwave-Water Bath Hybrid Warming for Frozen Cryoprotectant Solution Using a Helical Antenna

BACKGROUND

Successful cryopreservation of organs and/or tissues of large dimension is challenging due to damages by solute concentration and thermal stress caused by crystallization during cooling and devitrification/recrystallization during rewarming. The key to reduce thermal stresses in cryopreserved biomaterials during rewarming is fast and uniform heating.

OBJECTIVE

To explore a hybrid warming process using two heat sources (microwave and water bath) simultaneously to achieve faster and more uniform heating.

MATERIALS AND METHODS

Rewarming of frozen cryoprotectants (CPA) using microwave and 37ºC water bath at the same time was experimentally studied. A helical antenna was installed at the center of a 1.8 mL cryovial. Microwave (2.4 GHz) was generated, amplified and transported to the helical antenna through the matched coaxial cables. Frozen CPA solution in the cryovial at an initial temperature of -196ºC was rewarmed by microwave and water bath. The temperature of two selected points in the sample with the maximum temperature difference was measured by thermocouples during rewarming.

RESULTS

During rewarming of the frozen sample in 37ºC water bath without microwave, the warming rate was 70.2ºC min-1 with the maximum temperature gradient of 1.07ºC mm^-1 in the sample. With microwave added to form a hybrid warming process, the warming rate was increased to be 100.5ºC min^-1 with a smaller temperature gradient of 0.68ºC mm^-1.

CONCLUSION

The study indicated that warming rate and temperature uniformity increased with the microwave-water bath hybrid heating process.

Strategies to Increase On-Target and Reduce Off-Target Effects of the CRISPR/Cas9 System in Plants

The CRISPR/Cas9 system (clustered regularly interspaced short palindromic repeat-associated protein 9) is a powerful genome-editing tool in animals, plants, and humans. This system has some advantages, such as a high on-target mutation rate (targeting efficiency), less cost, simplicity, and high-efficiency multiplex loci editing, over conventional genome editing tools, including meganucleases, transcription activator-like effector nucleases (TALENs), and zinc finger nucleases (ZFNs). One of the crucial shortcomings of this system is unwanted mutations at off-target sites. We summarize and discuss different approaches, such as dCas9 and Cas9 paired nickase, to decrease the off-target effects in plants. According to studies, the most effective method to reduce unintended mutations is the use of ligand-dependent ribozymes called aptazymes. The single guide RNA (sgRNA)/ligand-dependent aptazyme strategy has helped researchers avoid unwanted mutations in human cells and can be used in plants as an alternative method to dramatically decrease the frequency of off-target mutations. We hope our concept provides a new, simple, and fast gene transformation and genome-editing approach, with advantages including reduced time and energy consumption, the avoidance of unwanted mutations, increased frequency of on-target changes, and no need for external forces or expensive equipment.

The complete mitochondrial genome of Lumbricus rubellus (Oligochaeta, Lumbricidae) and its phylogenetic analysis

The complete mitochondrial genome of Lumbricus rubellus was analyzed by next-generation sequencing. The mitogenome was 15,464 bp in length, comprising 13 protein-coding genes (PCGs), 22 transfer RNAs, 2 ribosomal RNAs, and a non-coding region. The phylogenetic analysis of 13 PCGs within the class Oligochaeta suggested that L. rubellus was placed as sister to L. terrestris of the same genus. The results obtained here can contribute to the phylogenetic analysis of earthworms.

Growth, physiological function, and antioxidant defense system responses of Lemna minor L. to decabromodiphenyl ether (BDE-209) induced phytotoxicity

Polybrominated diphenyl ethers (PBDEs), represent one of the new types of persistent organic pollutants (POPs) that are currently found in ambient aquatic ecosystems. Lemna minor L. is a floating freshwater plant, which is widely employed for phytotoxicity studies of xenobiotic substances. For this study, we investigated the growth, physiological functions, and antioxidant capacities of L. minor, which were exposed to 0-20 mg L^-1 decabromodiphenyl ether (BDE-209) for 14 days. A logistic model was suitable for describing the growth of L. minor when the BDE-209 concentration was in the range of from 0 to 15 mg L^-1. When exposed to 5 and 10 mg L^-1 BDE-209, the growth of L. minor was significantly increased, where the intrinsic rate (r) and the maximum capacity of the environment (K) of L. minor were significantly higher than those of the control. In this case, the chlorophyll content and soluble proteins were also markedly increased. Moreover, the photosynthetic function (Fv/Fm, PI) was enhanced. However, for 15 mg L^-1 BDE-29 treated group, the growth of L. minor was significantly inhibited, with decreases in chlorophyll and the soluble protein content, until the L. minor yellowed and expired under a concentration of 20 mg L^-1. Photosynthetic functions were also negatively correlated with increasing increments of BDE-209 (15 and 20 mg L^-1). The malondialdehyde (MDA), superoxide anion radical (O₂^̄·) content, and permeability of the plasma membranes increased with higher BDE-209 concentrations (0-20 mg L^-1). The superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT) activities of L. minor increased when the BDE-209 concentration ranged from 0 to 10 mg L^-1; however, the activities of SOD and POD were decreased. Only the CAT activity remained higher in contrast to the control group under 15-20 mg L^-1 BDE-209. These results demonstrated that 15 mg L^-1 BDE-209 imparted high toxicity to L. minor, which was a consequence of the overproduction of reactive oxygen species (ROS), which conveyed oxidative damage to plant cells. This study provided a theoretical understanding of BDE-209 induced toxicity as relates to the physiology and biochemistry of higher hydrophytes.

Mechanistic analysis and experimental verification of bicarbonate-controlled enteric coat dissolution: Potential in vivo implications

Enteric coatings have shown in vivo dissolution rates that are poorly predicted by traditional in vitro tests, with the in vivo dissolution being considerably slower than in vitro. To provide a more mechanistic understanding of this, the dependence of the release properties of various enteric-coated (EC) products on bulk pH and bicarbonate molarity was investigated. It was found that, at presumably in vivo-relevant values, the bicarbonate molarity is a more significant determinant of the dissolution profile than the bulk pH. The findings also indicate that this steep relationship between the dissolution of enteric coatings and bicarbonate molarity limits those coatings' performance in vivo. This is attributed to the relatively low bicarbonate molarities in human intestinal fluids. Further, the hydration and dehydrations kinetics of carbonic acid and carbon dioxide are not sufficiently rapid to reach equilibrium in the diffusion layer surrounding a dissolving ionizable solid. This results in the effective pKa of bicarbonate in the diffusion layer being lower than that determined potentiometrically at equilibrium in the bulk surrounding fluid. These results demonstrate the importance of thoroughly investigating the intestinal bicarbonate concentrations and using bicarbonate buffers or properly designed surrogates (if possible) when evaluating enteric drug products during product development and quality control.

Global negative effects of nitrogen deposition on soil microbes

Soil microbes comprise a large portion of the genetic diversity on Earth and influence a large number of important ecosystem processes. Increasing atmospheric nitrogen (N) deposition represents a major global change driver; however, it is still debated whether the impacts of N deposition on soil microbial biomass and respiration are ecosystem-type dependent. Moreover, the extent of N deposition impacts on microbial composition remains unclear. Here we conduct a global meta-analysis using 1408 paired observations from 151 studies to evaluate the responses of soil microbial biomass, composition, and function to N addition. We show that nitrogen addition reduced total microbial biomass, bacterial biomass, fungal biomass, biomass carbon, and microbial respiration. Importantly, these negative effects increased with N application rate and experimental duration. Nitrogen addition reduced the fungi to bacteria ratio and the relative abundances of arbuscular mycorrhizal fungi and gram-negative bacteria and increased gram-positive bacteria. Our structural equation modeling showed that the negative effects of N application on soil microbial abundance and composition led to reduced microbial respiration. The effects of N addition were consistent across global terrestrial ecosystems. Our results suggest that atmospheric N deposition negatively affects soil microbial growth, composition, and function across all terrestrial ecosystems, with more pronounced effects with increasing N deposition rate and duration.

Quantitative assessments of water-use efficiency in Temperate Eurasian Steppe along an aridity gradient

Water-use efficiency (WUE), defined as the ratio of net primary productivity (NPP) to evapotranspiration (ET), is an important indicator to represent the trade-off pattern between vegetation productivity and water consumption. Its dynamics under climate change are important to ecohydrology and ecosystem management, especially in the drylands. In this study, we modified and used a late version of Boreal Ecosystem Productivity Simulator (BEPS), to quantify the WUE in the typical dryland ecosystems, Temperate Eurasian Steppe (TES). The Aridity Index (AI) was used to specify the terrestrial water availability condition. The regional results showed that during the period of 1999–2008, the WUE has a clear decreasing trend in the spatial distribution from arid to humid areas. The highest annual average WUE was in dry and semi-humid sub-region (DSH) with 0.88 gC mm^-1 and the lowest was in arid sub-region (AR) with 0.22 gC mm^-1. A two-stage pattern of WUE was found in TES. That is, WUE would enhance with lower aridity stress, but decline under the humid environment. Over 65% of the region exhibited increasing WUE. This enhancement, however, could not indicate that the grasslands were getting better because the NPP even slightly decreased. It was mainly attributed to the reduction of ET over 70% of the region, which is closely related to the rainfall decrease. The results also suggested a similar negative spatial correlation between the WUE and the mean annual precipitation (MAP) at the driest and the most humid ends. This regional pattern reflected the different roles of water in regulating the terrestrial ecosystems under different aridity levels. This study could facilitate the understanding of the interactions between terrestrial carbon and water cycles, and thus contribute to a sustainable management of nature resources in the dryland ecosystems.

Irf8 regulates the progression of myeloproliferative neoplasm-like syndrome via Mertk signaling in zebrafish

Interferon regulatory factor (IRF)-8 is a critical transcription factor involved in the pathogenesis of myeloid neoplasia. However, the underlying mechanisms in vivo are not well known. Investigation of irf8-mutant zebrafish in this study indicated that Irf8 is evolutionarily conserved as an essential neoplastic suppressor through tight control of the proliferation and longevity of myeloid cells. Surviving irf8 mutants quickly developed a myeloproliferative neoplasm (MPN)-like disease with enhanced output of the myeloid precursors, which recurred after transplantation. Multiple molecules presented notable alteration and Mertk signaling was aberrantly activated in the hematopoietic cells in irf8 mutants. Transgenic mertk overexpression in Tg(coro1a:mertk) zebrafish recapitulated the myeloid neoplasia-like syndrome in irf8 mutants. Moreover, functional interference with Mertk, via morpholino knockdown or genetic disruption, attenuated the myeloid expansion phenotype caused by Irf8 deficiency. Therefore, Mertk signaling is a critical downstream player in the Irf8-mediated regulation of the progression of myeloid neoplasia. Our study extends the understanding of the mechanisms underlying leukemogenesis.

CO2 Emission Increases with Damage Severity in Moso Bamboo Forests Following a Winter Storm in Southern China

Despite the prevalence of disturbances in forests, the effects of disturbances on soil carbon processes are not fully understood. We examined the influences of a winter storm on soil respiration and labile soil organic carbon (SOC) of a Moso Bamboo (Phyllostachys heterocycle) plantation in the Wuyi Mountains in Southern China from May 2008 to May 2009. We sampled stands that were damaged at heavy, moderate, and light levels, which yielded aboveground biomass inputs to the soil at 22.12 ± 0.73 (mean ± 1 s.e.m.), 10.40 ± 1.09, and 5.95 ± 0.73 Mg per hectare, respectively. We found that soil respiration rate and annual cumulative CO2 emissions were significantly higher in heavily damaged sites than moderately and lightly damaged sites. Soil temperature was the most important environmental factor affecting soil respiration rate across all studied stands. However, soil respiration sensitivity to temperature (Q10) decreased in heavily damaged sites. Microbial biomass carbon and its proportion to total SOC increased with damage intensity. Soil respiration rate was positively correlated to microbial biomass carbon and soil moisture. Our results indicated that the increase of soil respiration following canopy disturbance from winter storm resulted from increased microbial biomass carbon, soil moisture, and temperature.

Association of Soil Aggregation with the Distribution and Quality of Organic Carbon in Soil along an Elevation Gradient on Wuyi Mountain in China

Forest soils play a critical role in the sequestration of atmospheric CO₂ and subsequent attenuation of global warming. The nature and properties of organic matter in soils have an influence on the sequestration of carbon. In this study, soils were collected from representative forestlands, including a subtropical evergreen broad-leaved forest (EBF), a coniferous forest (CF), a subalpine dwarf forest (DF), and alpine meadow (AM) along an elevation gradient on Wuyi Mountain, which is located in a subtropical area of southeastern China. These soil samples were analyzed in the laboratory to examine the distribution and speciation of organic carbon (OC) within different size fractions of water-stable soil aggregates, and subsequently to determine effects on carbon sequestration. Soil aggregation rate increased with increasing elevation. Soil aggregation rate, rather than soil temperature, moisture or clay content, showed the strongest correlation with OC in bulk soil, indicating soil structure was the critical factor in carbon sequestration of Wuyi Mountain. The content of coarse particulate organic matter fraction, rather than the silt and clay particles, represented OC stock in bulk soil and different soil aggregate fractions. With increasing soil aggregation rate, more carbon was accumulated within the macroaggregates, particularly within the coarse particulate organic matter fraction (250–2000 μm), rather than within the microaggregates (53–250μm) or silt and clay particles (< 53μm). In consideration of the high instability of macroaggregates and the liability of SOC within them, further research is needed to verify whether highly-aggregated soils at higher altitudes are more likely to lose SOC under warmer conditions.

Fertilizer regime impacts on abundance and diversity of soil fauna across a poplar plantation chronosequence in coastal Eastern China

Soil fauna are critical for ecosystem function and sensitive to the changes of soil fertility. The effects of fertilization on soil fauna communities, however, remain poorly understood. We examined the effects of fertilization form and quantity on the abundance, diversity and composition of soil fauna across an age-sequence of poplar plantations (i.e., 4-, 9- and 20-yr-old) in the coastal region of eastern China. We found that the effects of fertilization on faunal abundance, diversity, and composition differed among stand ages. Organic fertilizers increased the total abundance of soil fauna, whereas low level inorganic fertilizers imparted increases only in the 4- and 9-yr-old stands. The number of faunal groups did not change with fertilization, but Shannon’s and Margalef diversity indices increased under low level organic fertilization, and decreased under inorganic fertilization in the 9- and 20-yr-old stands. Community composition of soil fauna differed strongly with fertilization and stand age. The changes in soil fauna were strongly associated with the changes in microbial biomass carbon, dissolved organic carbon and nitrogen, and available phosphorus and potassium. Our findings suggest that the responses of soil fauna to fertilization may be mediated through the fertilization effects on soil nutrient availability.

Carbon: nitrogen stoichiometry following afforestation: a global synthesis

Though carbon (C): nitrogen (N) stoichiometry has been widely studied in terrestrial ecosystems, little is known about its variation following afforestation. By synthesizing the results of 53 studies, we examined temporal and spatial variation in C: N ratios and in N-C scaling relationships of both the organic and the mineral soil horizons. Results showed that C: N ratios remained constant in the mineral horizon but significantly decreased in the organic horizon over the age sequence following afforestation. Among different climate zones, C: N ratios of the organic and the mineral horizons increased and decreased, respectively, with increasing mean annual temperature (MAT) (decreasing latitude). Pasture exhibited higher C: N ratios than cropland in the organic horizon while C: N of the mineral horizon did not change much among different land use types. For both the organic and the mineral horizons, hardwoods exhibited lower C: N ratios than pine and softwoods. Additionally, N and C in general scaled isometrically in both the organic and the mineral horizons over the age sequence and among different climate zones, land use types, and plantation species following afforestation. Our results suggest that C and N may remain coupled following afforestation.

Analyzing the impact of climate and management factors on the productivity and soil carbon sequestration of poplar plantations

It is crucial to investigate how climate and management factors impact poplar plantation production and soil carbon sequestration interactively. We extracted above-ground net primary production (ANPP), climate and management factors from peer-reviewed journal articles and analyzed impact of management factor and climate on the mean annual increment (MAI) of poplar ANPP statistically. Previously validated mechanistic model (ED) is used to perform case simulations for managed poplar plantations under different harvesting rotations. The meta-analysis indicate that the dry matter MAI was 6.3 Mg ha(-1) yr(-1) (n=641, sd=4.9) globally, and 5.1 (n=292, sd=4.0), 8.1 (n=224, sd=4.7) and 4.4 Mg ha(-1) yr(-1) (n=125, sd=3.2) in Europe, the US and China, respectively. Poplar MAI showed a significant response to GDD, precipitation and planting density and formed a quadratic relationship with stand age. The low annual production for poplar globally was probably caused by suboptimal water availability, rotation length and planting density. SEM attributes the variance of poplar growth rate more to climate than to management effects. Case simulations indicated that longer rotation cycle significantly increased soil carbon storage. Findings of this work suggests that management factor of rotation cycle alone could have dramatic impact on the above ground growth, as well as on the soil carbon sequestration of poplar plantations and will be helpful to quantify the long-term carbon sequestration through short rotation plantation. The findings of this study are useful in guiding further research, policy and management decisions towards sustainable poplar plantations.

mTOR pathway is involved in ADP-evoked astrocyte activation and ATP release in the spinal dorsal horn in a rat neuropathic pain model

BACKGROUND

ATP/ADP-evoked spinal astrocyte activation plays a vital role in the development of neuropathic pain. We aim to investigate the role of mammalian target of rapamycin (mTOR) pathway on the spinal astrocyte activation in the neuropathic pain development in rats.

METHODS

Sprague Dawley (SD) rats were subjected to chronic constriction of the sciatic nerve (CCI). Rapamycin or ADP was intrathecally injected daily to explore their effects on spinal astrocyte activation and pain development. Expression of glial fibrillary acidic protein (GFAP) and mTOR in the spinal dorsal horn was assessed by immunohistochemistry. Von Frey hairs and Hargreaves paw withdrawal test were conducted to evaluate mechanical allodynia and thermal sensitivity, respectively. Firefly luciferase ATP assay was used to assess the change of ATP level in cerebrospinal fluid (CSF) and medium of cultured astrocytes.

RESULTS

GFAP expression was enhanced in the ipsilateral spinal dorsal horn from day 3 after surgery. GFAP and mTOR expression in the rat spinal dorsal horn on post-surgical day 14 was enhanced by daily intrathecal injection of ADP, which was inhibited by rapamycin. Rapamycin decreased lower mechanical pain threshold and the thermal withdrawal latency. Intrathecal injection of ADP enhanced the ATP release, which was partially inhibited by rapamycin. Study of cultured astrocytes indicated that ATP could be released from astrocytes.

CONCLUSION

Our data demonstrated that ADP enhanced neuropathic pain in CCI rats, which was inhibited by rapamycin. This study indicates that targeting mTOR pathway could serve as a novel therapeutic strategy in neuropathic pain management.

Long term effect of land reclamation from lake on chemical composition of soil organic matter and its mineralization

Since the late 1950s, land reclamation from lakes has been a common human disturbance to ecosystems in China. It has greatly diminished the lake area, and altered natural ecological succession. However, little is known about its impact on the carbon (C) cycle. We conducted an experiment to examine the variations of chemical properties of dissolved organic matter (DOM) and C mineralization under four land uses, i.e. coniferous forest (CF), evergreen broadleaf forest (EBF), bamboo forest (BF) and cropland (CL) in a reclaimed land area from Taihu Lake. Soils and lake sediments (LS) were incubated for 360 days in the laboratory and the CO₂ evolution from each soil during the incubation was fit to a double exponential model. The DOM was analyzed at the beginning and end of the incubation using UV and fluorescence spectroscopy to understand the relationships between DOM chemistry and C mineralization. The C mineralization in our study was influenced by the land use with different vegetation and management. The greatest cumulative CO₂-C emission was observed in BF soil at 0–10 cm depth. The active C pool in EBF at 10–25 cm had longer (62 days) mean residence time (MRT). LS showed the highest cumulative CO₂-C and shortest MRT comparing with the terrestrial soils. The carbohydrates in DOM were positively correlated with CO₂-C evolution and negatively correlated to phenols in the forest soils. Cropland was consistently an outlier in relationships between DOM chemistry and CO₂-evolution, highlighting the unique effects that this land use on soil C cycling, which may be attributed the tillage practices. Our results suggest that C mineralization is closely related to the chemical composition of DOM and sensitive to its variation. Conversion of an aquatic ecosystem into a terrestrial ecosystem may alter the chemical structure of DOM, and then influences soil C mineralization.

Modified Sauvé-Kapandji procedure for restoration of forearm rotation in devascularized hands

INTRODUCTION

The purpose of this study is to evaluate the clinical outcomes in patients with forearm rotation limitation after successful wrist-level revascularization who underwent a modified Sauvé-Kapandji (S-K) procedure.

METHODS

This was a retrospective review of the clinical records of nine patients (three women, six men) after successful wrist-level revascularization who underwent late restoration of forearm rotation. All patients were evaluated using a Mayo Modified Wrist Score. The mean patient age was 35 (range 19-45) years. Mean time to reconstruction was 2.5 (range 0.5-4) years.

RESULTS

Mean postoperative pronation was 74°; mean postoperative supination was 80°. Overall results were excellent/good in seven patients, fair in one, and poor in one. No bone bridge was formed between the pseudarthrosis in any patient. Two patients had neurapraxia. Moderate pain and snapping occurred in one patient during movement at the ulnar amputation site.

CONCLUSION

This modification of the S-K procedure can restore rotation of the forearm after hand revascularization; as such, it provides an alternative salvage procedure.

Dissolved organic carbon in headwater streams and riparian soil organic carbon along an altitudinal gradient in the Wuyi Mountains, China

Stream water dissolved organic carbon (DOC) correlates positively with soil organic carbon (SOC) in many biomes. Does this relationship hold in a small geographic region when variations of temperature, precipitation and vegetation are driven by a significant altitudinal gradient? We examined the spatial connectivity between concentrations of DOC in headwater stream and contents of riparian SOC and water-soluble soil organic carbon (WSOC), riparian soil C:N ratio, and temperature in four vegetation types along an altitudinal gradient in the Wuyi Mountains, China. Our analyses showed that annual mean concentrations of headwater stream DOC were lower in alpine meadow (AM) than in subtropical evergreen broadleaf forest (EBF), coniferous forest (CF), and subalpine dwarf forest (SDF). Headwater stream DOC concentrations were negatively correlated with riparian SOC as well as WSOC contents, and were unrelated to riparian soil C:N ratio. Our findings suggest that DOC concentrations in headwater streams are affected by different factors at regional and local scales. The dilution effect of higher precipitation and adsorption of soil DOC to higher soil clay plus silt content at higher elevation may play an important role in causing lower DOC concentrations in AM stream of the Wuyi Mountains. Our results suggest that upscaling and downscaling of the drivers of DOC export from forested watersheds when exploring the response of carbon flux to climatic change or other drivers must done with caution.

Pulsed ultrasound modulated optical tomography utilizing the harmonic response of lock-in detection

Ultrasound modulated optical tomography (USMOT) can image the optical properties of a scattering medium at a spatial resolution approaching that of ultrasound (US). A lock-in parallel speckle detection technique is proposed to detect pulsed US modulated light using a multipixel detector. The frequency components of the pass band match those of the US pulse train and provide efficient detection. The modulation depth is extracted by taking the difference between a pair of speckle patterns modulated by a pair of phase-inversed US bursts. Modification to pulse inversion mode enables the second harmonic US modulation due to nonlinear US propagation to be detected.

Spatial-seasonal variation of soil denitrification under three riparian vegetation types around the Dianchi Lake in Yunnan, China

Outbreaks of nuisance cyanobacterial bloom are predicted to occur frequently under the effect of severe eutrophication in the water body of Lake Dianchi since the 1990s. Riparian buffers are now well recognized for their roles in the removal of inorganic nitrogen mainly via denitrification. Little is known, however, about the mechanisms of nitrate removal in the riparian buffers of Lake Dianchi. We investigated the wet and dry seasonal dynamics of denitrification rate (DNR) in the soil profiles along the topographic gradient in three riparian buffers with different vegetation types (i.e. forest, open forest, and grass). A strong vertical pattern was observed in soil organic C and N concentrations (i.e. total N, DON, NO3-N, and NH4-N) along the soil layers. We also found significantly higher in situ denitrification activity in the upper horizon along each topohydrosequence while the activities of soil denitrification could be detected down to deeper soil horizons (0.1 to 0.8 mg N per kg dry soil per day), which may contribute significantly to the reduction of the ground water nitrate. Meanwhile, the DNR in the zones near the lake was significantly higher than that in zones near the border with the upland terrace, and also in the wet seasons than in dry seasons. Denitrification rates in the forest, open forest and grass sites were significantly different only in wet seasons. Especially, we found soil organic C had a strong correlation with denitrification in all sites, despite the large intersite variability of soil and vegetation. Our data suggested spatial heterogeneity of substrate availability along a hydrologic and topographic gradient can be the primary control on spatial-seasonal patterns of denitrification in riparian buffers.

Temperature sensitivity of soil organic carbon mineralization along an elevation gradient in the Wuyi Mountains, China

Soil organic carbon (SOC) actively participates in the global carbon (C) cycle. Despite much research, however, our understanding of the temperature sensitivity of soil organic carbon (SOC) mineralization is still very limited. To investigate the responses of SOC mineralization to temperature, we sampled surface soils (0–10 cm) from evergreen broad-leaf forest (EBF), coniferous forest (CF), sub-alpine dwarf forest (SDF), and alpine meadow (AM) along an elevational gradient in the Wuyi Mountains, China. The soil samples were incubated at 5, 15, 25, and 35°C with constant soil moisture for 360 days. The temperature sensitivity of SOC mineralization (Q₁₀) was calculated by comparing the time needed to mineralize the same amount of C at any two adjacent incubation temperatures. Results showed that the rates of SOC mineralization and the cumulative SOC mineralized during the entire incubation significantly increased with increasing incubation temperatures across the four sites. With the increasing extent of SOC being mineralized (increasing incubation time), the Q₁₀ values increased. Moreover, we found that both the elevational gradient and incubation temperature intervals significantly impacted Q₁₀ values. Q₁₀ values of the labile and recalcitrant organic C linearly increased with elevation. For the 5–15, 15–25, and 25–35°C intervals, surprisingly, the overall Q₁₀ values for the labile C did not decrease as the recalcitrant C did. Generally, our results suggest that subtropical forest soils may release more carbon than expected in a warmer climate.

Effects of acoustic stimuli on neuronal activity in the auditory cortex of the rat

Spontaneous activity of cortical neurons exhibits alternative fluctuations of membrane potential consisting of phased depolarization called "up-state" and persistent hyperpolarization called "down-state" during slow wave sleep and anesthesia. Here, we examined the effects of sound stimuli (noise bursts) on neuronal activity by intracellular recording in vivo from the rat auditory cortex (AC). Noise bursts increased the average time in the up-state by 0.81+/-0.65 s (range, 0.27-1.74 s) related to a 10 s recording duration. The rise times of the spontaneous up-events averaged 69.41+/-18.04 ms (range, 40.10-119.21 ms), while those of the sound-evoked up-events were significantly shorter (p<0.001) averaging only 22.54+/-8.81 ms (range, 9.31-45.74 ms). Sound stimulation did not influence ongoing spontaneous up-events. Our data suggest that a sound stimulus does not interfere with ongoing spontaneous neuronal activity in auditory cortex but can evoke new depolarizations in addition to the spontaneous ones.

Silencing Jnk1 and Jnk2 accelerates basal lipolysis and promotes fatty acid re-esterification in mouse adipocytes

AIMS/HYPOTHESIS

Elevated plasma levels of NEFA impair insulin action. Given the positive linear correlation between NEFA released by adipocytes and plasma NEFA levels, identification of mechanisms controlling adipocyte lipolysis and NEFA release could provide a guide to new therapies for insulin resistance and type 2 diabetes.

METHODS

Short hairpin RNA-mediated gene ablation was used to determine the functions of c-Jun N-terminal kinase (JNK)1 and JNK2 in adipocytes.

RESULTS

Combined JNK1/JNK2 deficiency drastically increased basal glycerol release, whereas individual JNK1- or JNK2-deficiency had no effect, indicating that JNK1/JNK2-deficiency enhances basal lipolysis, whereas the alternate subtype compensates for a single JNK subtype deficiency in the regulation of basal lipolysis. The profoundly increased glycerol release associated with JNK1/JNK2-deficiency was not accompanied by a concomitant increase in NEFA release over time. In addition, JNK1-deficiency, but not JNK2-deficiency, drastically decreased NEFA release as compared with that in JNK-intact cells, a result of increased NEFA re-esterification. In microarray, quantitative RT-PCR and western blotting, JNK1-, JNK2- and JNK1/JNK2-deficiencies selectively upregulated many genes involved in NEFA management, without affecting the expression of genes involved in insulin signalling. Assays using reporter genes driven by peroxisome proliferator-activated receptor gamma (PPAR-gamma)-responsive promoters indicate distinct roles for JNK1 and JNK2 in regulating the transcriptional effects of PPAR-gamma.

CONCLUSIONS/INTERPRETATION

While JNK1 and JNK2 have shared roles in the regulation of basal lipolysis, JNK1 has a more profound role in supporting baseline NEFA release. Inhibition of JNK1 activity in adipocytes has potential therapeutic uses for management of elevated circulating NEFA levels at the onset of insulin resistance.

Response surface methodology for optimizing the fermentation medium of alpha-galactosidase in solid-state fermentation

AIMS

Alpha-galactosidase is applied in food and feed industries for hydrolysing raffinose series oligosaccharides (RO) that are the factors primarily responsible for flatulence upon ingestion of soybean-derived products. The objective of the current work was to develop an optimal culture medium for the production of alpha-galactosidase in solid-state fermentation (SSF) by a mutant strain Aspergillus foetidus.

METHODS AND RESULTS

Response surface methodology (RSM) was applied to evaluate the effects of variables, namely the concentrations of wheat bran, soybean meal, KH(2)PO(4), MnSO(4).H(2)O and CuSO(4).5H(2)O on alpha-galactosidase production in the solid substrate. A fractional factorial design (FFD) was firstly used to isolate the main factors that affected the production of alpha-galactosidase and the central composite experimental design (CCD) was then adopted to derive a statistical model for optimizing the composition of the fermentation medium. The experimental results showed that the optimum fermentation medium for alpha-galactosidase production by Aspergillus foetidus ZU-G1 was composed of 8.2137 g wheat bran, 1.7843 g soybean meal, 0.001 g MnSO(4).H(2)O and 0.001 g CuSO(4).5H(2)O in 10 g dry matter fermentation medium.

CONCLUSIONS

After incubating 96 h in the optimum fermentation medium, alpha-galactosidase activity was predicted to be 2210.76 U g(-1) dry matter in 250 ml shake flask. In the present study, alpha-galactosidase activity reached 2207.19 U g(-1) dry matter.

SIGNIFICANCE AND IMPACT OF THE STUDY

Optimization of the solid substrate was a very important measure to increase enzyme activity and realize industrial production of alpha-galactosidase. The process of alpha-galactosidase production in laboratory scale may have the potential to scale-up.

Studies on a kinetic model for butyric acid bioproduction by Clostridium butyricum

AIMS

This paper discusses the establishment of a kinetic model for cell growth, butyric acid production and substrate consumption of Clostridium butyricum ZJUCB in batch cultivation.

METHODS AND RESULTS

Mathematic simulations were proposed by the logistic equation for the cell growth, the Luedeking-Piret equation for butyric acid production and the Luedeking-Piret-like equation for glucose consumption.

CONCLUSION

We compared the performance of our model against that obtained by the empirically experimental design. The experiment-validated model was found suitable for studying butyric acid fermentation kinetics in a complex dynamic behaviour of C. butyricum, especially for its singular growth phenomenon.

SIGNIFICANCE AND IMPACT OF THE STUDY

The model parameters are estimated from the data fitting and evaluated for simulation of the time courses of the concentrations of cell biomass, butyric acid and glucose and the model appears to fit the experimental data well. The results may be useful for butyric acid production by microbial fermentation.

[Biological characteristics of different forest soils in Nanjing-Zhenjiang mountan area]

Studies on the biological characteristics, including soil microbe, soil enzyme activity, soil nutritient content, and litter decomposition of different forest soils in Nanjing-Zhenjiang mountain area showed that the amounts of microbes and the activities of six enzymes in forest soils changed regularly in different forests during different months. The contents of nutritional elements varied regularly with forest growth bio-cycles, and were inerrelated prominently with the amounts of soil microbes and the activities of soil enzymes. There existed temporal-spatial differences in the decomposition rate of litters and the reverted velocity of nutrients among different forests. The comparisons of various biological characteristics among secondary Quercus variabilis forest, Phllostachys pubescens forest, and Cunninghamia lanceolata forest indicated that secondary Quercus variabilis forest had the most abundant nutrients in soil, and possessed the strongest ability of self-fertilization. Therefore, to construct coniferous forests with broadleaf trees in this area could avoid or abate the decline of soil fertility.

[Effects of activin and follistatin on FSH receptor mRNA expression of cultured Shao duck granulosa cells]

The aim of this study was to investigate the action of activin and follistatin either alone or in combination on FSH receptor mRNA expression. The results showed that activin alone increased FSH receptor mRNA level in the presence or absence of FSH in cultured granulosa cells, and the stimulating effect of activin on FSH receptor level was dose-dependent. This effect of activin was inhibited by FSP treatment which alone had no effect on FSH receptor expression. From the results, it can be concluded that activin and follistatin both exert autocrine actions on granulosa cells, and the two factors, possibly by regulating FSH receptor expression, may play important roles in follicular development.