Effects of plant residues on C:N:P of soil, microbial biomass, and extracellular enzyme in an alpine mea-dow on the Qinghai-Tibetan Plateau, China.

Plant residues can affect C:N:P of soil, microbial biomass, and extracellular enzyme, but the effects are still unclear. We conducted a field experiment in an alpine meadow on the eastern part of the Qinghai-Tibetan Plateau to explore the effects of removing aboveground plant or roots and adding plant residues on the C:N:P of soil, microbial biomass, and extracellular enzyme. The results showed that removing aboveground plant biomass significantly decreased soil C:N (the change was -23.7%, the same below) and C:P (-14.7%), microbial biomass C:P and N:P, while significantly increased microbial biomass C:N, and enzyme C:N:P compared with meadow without human disturbance. Removing all plant biomass (aboveground and roots) significantly reduced soil C:N (-11.6%), C:P (-24.0%), N:P (-23.3%) and microbial biomass C:N in comparison to removing aboveground plant, while significantly improved microbial biomass N:P and enzyme N:P. Adding plant residues after removing aboveground plant significantly increased microbial biomass C:N and C:P, enzyme C:N compared with removing aboveground plant, while significantly decreased enzyme N:P. Compared with removing all the plant, adding plant residues after removing whole plant significantly reduced soil C:N (-16.4%), microbial biomass C:P, N:P and enzyme N:P, while significantly increased enzyme C:N. Our results suggest that removal of plants could have a strong effect on C:N:P of soil, microbial biomass, and extracellular enzyme, and C:N:P of microbial biomass and that extracellular enzyme woule be more sensitive to plant residues. Roots could play a key role in stabilizing C:N:P of soil, microbial biomass, and extracellular enzyme under plant residues addition. Adding plant residues could be a suitable solution for restoring alpine meadows under the circumstance of intact roots, which was conducive to soil C storage, but might not be suitable for alpine meadows with serious root damage, which would increase soil CO2 emission.

[Soil denitrifying enzyme activity and its influencing factors in a bamboo forest riparian zone in the upper reaches of the Taihu Lake Basin, China]. / å¤ªæ¹–æµåŸŸä¸Šæ¸¸ç«¹æž—æ²³å²¸å¸¦åœŸå£¤åç¡åŒ–é ¶æ´»æ€§åŠå ¶å½±å“å› ç´ .

Soil denitrifying enzyme activity (DEA) was measured by acetylene inhibition technique, along with exploration of factors influencing DEA in a bamboo forest riparian zone in the upper reaches of the Taihu Lake Basin during summer. Our aim was to provide important insights into the assessment of ecological functions of bamboo forest riparian zone on reducing nitrogen pollution in rivers. The results showed that the riparian soil DEA ranged from 6.32 to 23.22 µg N·kg-1·h-1, with a mean value of 14.65 µg N·kg-1·h-1. The vertical distribution (0-40 cm soil profile) of DEA was affected by several factors, such as soil organic carbon (SOC), total nitrogen (TN), nitrate nitrogen (NO3--N), soil water content, and activity of carbon and nitrogen hydrolase, which resulted in decreased DEA with increasing soil depth. The horizontal changes in DEA (at the same soil depth but at different distances from river) was mainly governed by the variation in SOC concentration. In this area, the concentration of soil dissolved organic carbon was relatively low, which might inhibit the soil DEA during summer.

[Characteristics and Drivers of Dissolved Carbon Dioxide and Methane Concentrations in the Nantiaoxi River System in the Upper Reaches of the Taihu Lake Basin During Summer-Autumn].

Inland waters are vital sinks for active carbon (C) and potential sources of greenhouse gas emissions. In this study, the characteristics of dissolved carbon dioxide (CO2) and methane (CH4) concentrations in the Nantiaoxi River system in the upper reaches of the Taihu Lake basin were observed between Jul. 2019 and Nov. 2019 (summer and autumn) using headspace equilibration-gas chromatography. Simultaneously, physical and chemical parameters were also determined to understand the factors influencing dissolved CO2 and CH4 concentrations. The results showed that the mean dissolved CO2 concentrations and saturation levels in water were (505.47±16.99) µg·L-1 and (256.31±8.32)%, respectively, and the corresponding values for CH4 were (1.88±0.09) µg·L-1 and (5218.74±264.30)%, respectively. The saturation levels of dissolved CO2 and CH4 at all observation points were greater than 100%, indicating that the Nantiaoxi River system is a potential source of CO2 and CH4. The highest mean dissolved CO2 concentrations in water were found in agricultural areas followed by residential and forest areas, and there were significant differences among the three land-use types. The mean dissolved CH4 concentrations in the water in residential areas were significantly higher than those in agricultural area forest areas. The dissolved CO2 concentrations, saturation levels of CO2, dissolved CH4 concentrations, and saturation levels of CH4 in water were all negatively correlated with oxidation reduction potential (ORP) (P<0.01) and positively correlated with electrical conductivity (EC) (P<0.01). The discrepancies in chlorophyll (Chl-a), nitrate (NO3--N), total nitrogen (TN), and EC were the main reasons for differences in dissolved CO2 concentrations among the different land use types. Phytoplankton growth could be promoted by the higher input of nitrogen pollutants into rivers in agricultural and residential areas, and respiration could be also enhanced, resulting in higher dissolved CO2 concentrations. The higher concentrations of dissolved organic carbon (DOC) and ammonium nitrogen (NH4+-N) in the water, and the water temperature in residential areas, were probably the main causes of the higher dissolved CH4 concentrations. Rainfall also had some influence on dissolved CO2 and CH4 concentrations in the water associated with the different land use types. Specifically, higher concentrations of nitrogen pollutants and the enhancement of DOC were the main drivers of high dissolved CO2 concentrations in agricultural areas as well as the higher dissolved CH4 concentrations in residential areas following rainfall events.

[Accumulation Characteristics and Release Regularity of Nutrients in Sediments of a Surface-flow Constructed Wetland After Long-term Operation].

Sediments serve as an important carrier during the migration and transformation of pollutants in surface-flow constructed wetlands. Exploring the accumulation characteristics and release patterns of nutrients is of great significance for assessing the purification functions of constructed wetlands after long-term operation. The contents of total organic carbon (TOC), total nitrogen (TN), and total phosphorus (TP) in sediments at various locations of the 5-year-old Yanlong Lake surface-flow constructed wetland were analyzed and static release experiments with cylindrical core samples were carried out. The results showed that after five years, sediments at this site have become moderately polluted and the nutrient accumulation level is mainly being affected by the influent flow, water depth, and plant effects. Additionally, ① nutrients in sediments were found to increase along the flow direction; ② they also increase as the depth of overlying water increases and are relatively affected by the carbon; ③ healthier growth of the wetland plants could lead to more nutrients being accumulated in sediments. The release trend of nutrients fell after a rise and basically reached equilibrium after 20 days, and the release rate was mainly affected by the accumulation level of nutrients, which is similar to the trend in light nutrient containing reservoirs. Plant residues contained in the sediments were associated with the stronger release of nutrients. These results can provide a scientific basis for solutions aimed at maintaining the purification capacity of long-running surface-flow constructed wetlands.

The novel lipopolysaccharide-binding protein CRISPLD2 is a critical serum protein to regulate endotoxin function.

LPS is an immunostimulatory component of Gram-negative bacteria. Acting on the immune system in a systemic fashion, LPS exposes the body to the hazard of septic shock. In this study we report that cysteine-rich secretory protein LCCL domain containing 2 (CRISPLD2/Crispld2; human and mouse/rat versions, respectively), expressed by multitissues and leukocytes, is a novel LPS-binding protein. As a serum protein, median CRISPLD2 concentrations in health volunteers and umbilical cord blood samples are 607 microg/ml and 290 microg/ml, respectively. Human peripheral blood granulocytes and mononuclear cells including monocytes, NK cells, and T cells spontaneously release CRISPLD2 (range, 0.2-0.9 microg/ml) and enhance CRISPLD2 secretion (range, 1.5-4.2 microg/ml) in response to stimulation of both LPS and humanized anti-human TLR4-IgA Ab in vitro. CRISPLD2 exhibits significant LPS binding affinity similar to that of soluble CD14, prevents LPS binding to target cells, reduces LPS-induced TNF-alpha and IL-6 production, and protects mice against endotoxin shock. In in vivo experiments, serum Crispld2 concentrations increased in response to a nontoxic dose of LPS and correlated negatively with LPS lethality, suggesting that CRISPLD2 serum concentrations not only are indicators of the degree of a body's exposure to LPS but also reflect an individual's LPS sensitivity.

ZBTB34, a novel human BTB/POZ zinc finger protein, is a potential transcriptional repressor.

BTB/POZ protein family plays a key role in many biological processes both in Drosophila and vertebrates through regulating the transcriptional activities of some downstream genes. Here, we obtained a novel member of human BTB/POZ protein family, named as ZBTB34 (Zinc finger and BTB domain containing 34), which encodes 504 amino acid residues with a BTB/POZ domain at its N-terminus that is similar to the same domain of other known transcription regulators. RT-PCR analysis indicated that ZBTB34 was expressed ubiquitously in most adult human tissues, and whilst immunofluorescence assays showed that ZBTB34 was mainly localized to nucleus. Interestingly, the reporter assay in mammalian cells suggested that ZBTB34 might function as a transcriptional repressor. This present work as the first report about the functional exploration of the novel ZBTB34 gene would be contributed to profound understanding of the transcriptional regulation via BTB/POZ protein family.

[Construction of an activation tagging library of Arabidopsis and cloning for mutant genes].

Activation tagging is an important strategy in plant genomics by generating gain-of-function mutants. In this work, a library of Arabidopsis mutants was constructed by in planta transformation mediated by Agrobacterium tumefaciens containing an activation tagging vector pSKI015 with herbicide Basta as a selection marker (Fig. 1). Among 20000 independent transformants, 38 lines, i.e. about 0.2% of T(1) progeny, show visible morphological phenotypic variations (Fig. 2). Results of Southern blot analysis revealed that most of the transformants have more than three copies of T-DNA insertion (Fig. 3). Plasmid rescue and TAIL-PCR were used to recover the flanking genomic sequences of mutated target genes as the first step towards mutant gene cloning (Fig. 4, 5).

Alpha-picolinic acid, a fungal toxin and mammal apoptosis-inducing agent, elicits hypersensitive-like response and enhances disease resistance in rice.

Alpha-picolinic acid (PA), a metabolite of tryptophan and an inducer of apoptosis in the animal cell, has been reported to be a toxin produced by some of plant fungal pathogens and used in screening for disease resistant mutants. Here, we report that PA is an efficient apoptosis agent triggering cell death of hypersensitive-like response in planta. Confirmed by Fluorescence Activated Cell Sorter (FACS), rice suspension cells and leaves exhibited programmed cell death induced by PA. The PA-induced cell death was associated with the accumulation of reactive oxygen species that could be blocked by diphenylene iodonium chloride, indicating that the generation of reactive oxygen species was NADPH-oxidase dependent. We also demonstrated the induction of rice defense-related genes and subsequent resistant enhancement by PA against the rice blast fungus Magnaporthe grisea. Hence, it was concluded that the PA-stimulated defense response likely involves the onset of the hypersensitive response in rice, which also provides a simple eliciting tool for studying apoptosis in the plant cell.