Effects of arbuscular mycorrhizae and extraradical mycelium of subtropical tree species on soil nitrogen mineralization and enzyme activities.

Through symbiosis with plants, arbuscular mycorrhizal (AM) fungi effectively improve the availability of soil nitrogen (N). However, the mechanism through which AM and associated extraradical mycelium affect soil N mineralization remains unknow. We carried out an in situ soil culture experiment by using in-growth cores in plantations of three subtropical tree species, Cunninghamia lanceolata, Schima superba, and Liquidambar formosana. We measured soil physical and chemical properties, net N mineralization rate, and the activities of four kinds of hydrolase (leucine aminopeptidase (LAP), ß-1,4-N-acetylglucosaminidase (NAG), ß-1,4-glucosidase (ßG), cellobiohydrolase (CB)) and two kinds of oxidases (polyphenol oxidase (POX) and peroxidase (PER)) involved in soil organic matter (SOM) mineralization in treatments of mycorrhiza (with absorbing roots and hyphae), hyphae (hyphae only), and control (mycorrhiza-free). The results showed that mycorrhizal treatments significantly affected soil total carbon and pH but did not affect N mineralization rates and all enzymatic activities. Tree species significantly affected net ammonification rate, net N mineralization rate and activities of NAG, ßG, CB, POX and PER. The net N mineralization rate and enzyme activities in the C. lanceolata stand were significantly higher than that in monoculture broad-leaved stands of either S. superba or L. formosana. There was no interactive effect of mycorrhizal treatment and tree species on any of soil properties, nor on enzymatic activities or net N mineralization rates. Soil pH was negatively and significantly correlated with five kinds of enzymatic activities except for LAP, while net N mineralization rate significantly correlated with ammonium nitrogen content, available phosphorus content, and the activity level of ßG, CB, POX, and PER. In conclusion, there was no difference in enzymatic activities and N mineralization rates between rhizosphere and hyphosphere soils of three subtropical tree species in the whole growing season. The activity of particular carbon cycle-related enzymes was closely related to soil N mineralization rate. It is suggested that differences in litter quality and root functional traits among different tree species affect soil enzyme activities and N mineralization rates through organic matter inputs and shaping soil condition.

[Study on the Plasma Parameters of the Spot-Halo Hexagon Pattern with Optical Emission Spectrum].

The spot-halo hexagon pattern consisted of the center spot and hexagon halo in dielectric barrier discharge is researched, which filled with gas-mixture of argon and air. The pictures taken from the experiment shows that there is an obvious difference on brightness between the center spot and hexagon halo. All of these phenomena suggest that the center spot and hexagon halo are probably in different plasma state. The plasma parameters of the center spot and hexagon halo in the spot-halo hexagon pattern as a function of gas pressure are studied in details by using optical emission spectra. The emission spectra of the N2 second positive band(C3Πu→B3Πg)are measured, from which the molecule vibrational temperature of the center spot and hexagon halo are calculated. Based on the relative intensity of the line at 391.4 nm and the N2 line at 394.1 nm, the change of the electron average energy of the center spot and hexagon halo as a function of gas pressure is investigated. The electron density is studied by using the broadening of the spectral line 696.5 nm. It is found that the main chart of the spot-halo hexagon pattern is the argon content from 60% to 75% and the pressure from 30 to 46 kPa. The molecule vibrational temperature and electron average energy of the hexagon halo are higher than those of the center spot at the same pressure. As the pressure gradually increased from 30 to 46 kPa, the molecule vibrational temperature and electron average energy of the center spot and hexagon halo are increased, too. The broadening of the spectral line of the hexagon halo is bigger than the center spot at the same pressure, which increases with the gas pressure increasing. It indicates that the electron density increases with gas pressure increasing. The different plasma state of the center spot and hexagon halo show that the different formations mechanism of them. It is found that there are volume discharges firstly and then comes surface discharges with e high speed camera.

[Influence of Argon Content on Plasma Temperature of Single Filament in Dielectric Barrier Discharge].

The single filament (also referred to as monofilament) which composed of two parts including the center spot and the outer halo is observed and researched for the first time in dielectric barrier discharge, which filled with gas-mixture of argon and air. The pictures taken from the experiment show that the diameter of the monofilament decreases with the increasing of the content of the argon in the argon-air mixture, and at the same time there is an obvious difference on brightness between the center spot and the outer halo. All of these phenomenons suggest that the center spot and the outer halo are probably in different plasma state. The micro character of the center spot and the outer halo is researched seriously in the experiment by the time-resolved measurement with optical method. Three plasma temperatures of the center spot and the outer halo in single filament in different argon content are studied in details by using optical emission spectra. The emission spectra of the N2 second positive band (C3 π(u) --> B3 πg) are measured, from which the molecule vibrational temperature of the center spot and the outer halo are calculated. Based on the relative intensity of the N2 line at 391.4 nm and the N2 line at 394. 1 nm, the changing relationship of the average electron energy of the center spot and the outer halo with argon content is investigated. The spectral lines of Ar I 763.2 nm (2P6 --> 1S5) and 772.077 nm (2P2 --> 1S3) are chosen to estimate electron excitation temperature of the center spot and the outer halo by the relative intensity ratio method. The results show that the optical signal corresponding to the first lasge pulse is the center spot, whose signal intensity is a litter weaker; and the optical signal containing the whole pulse is the outer halo, whose signal intensity is stronger. The three plasma temperatures including the molecule vibrational temperature, average electron energy and electron excitation temperature of the outer halo are higher than those of the spot at the same argon content without exception. In addition, the molecule vibrational temperature of the center spot and the outer halo decrease with the argon content increases from 30% to 50%, while on the other hand, electron excitation temperature and average electron energy are decrease gradually.

[Plasma temperature of white-eye hexagonal pattern in dielectric barrier discharge].

By using the water-electrode discharge experimental setup, the white-eye hexagonal pattern is firstly observed and investigated in the dielectric barrier discharge with the mixture of argon and air whose content can be varied whenever necessary, and the study shows that the white-eye cell is an interleaving of three different hexagonal sub-structures: the spot, the ring, and the halo. The white-eye hexagonal pattern has the excellent discharge stability and sustainability during the experiment. Pictures recorded by ordinary camera with long exposure time in the same argon content condition show that the spot, the ring, and the halo of the white-eye hexagonal pattern have different brightness, which may prove that their plasma states are different. And, it is worth noting that there are obvious differences not only on the brightness but also on the color of the white-eye cell in conditions of different argon content, which shows that its plasma state also changed with the variation of the argon content. The white-eye hexagonal pattern is observed at a lower applied voltage so that the temperature of the water electrodes almost keeps unchanged during the whole experiment, which is advantageous for the long term stable measurement. The plasma state will not be affected by the temperature of the electrodes during the continuous discharge. Based on the above phenomena, plasma temperatures of the spot, the ring, and the halo in white-eye hexagonal pattern including molecule vibrational temperature and variations of electron density at different argon content are investigated by means of optical emission spectroscopy (OES). The emission spectra of the N2 second positive band(C3Πu-->B3Πg)are measured, and the molecule vibrational temperature of the spot, the ring, and the halo of the white-eye hexagonal pattern are calculated by the emission intensities. Furthermore, emission spectra of Ar I (2P2-->1S5)is collected and the changes of its width with different argon content are used to estimate the variations of electron density of the spot, the ring, and the halo of the white-eye hexagonal pattern. In the same argon content condition, the molecule vibrational temperatures of halo, ring, and spot in the white-eye hexagonal pattern are in descending order, while the electron densities of halo, ring, and spot are in ascending order. With argon content increasing from 70% to 90%, both the molecule vibrational temperature and the electron density of the spot increase, while both of them of the halo decrease. And the molecule vibrational temperature of the ring keeps constant, while its electron density decreases. The experimental results indicate that the plasma state of the spot, the halo and the ring in a white-eye cell of the white-eye hexagonal pattern is different. These results are of great importance to the investigation of the multilayer structure of the patterns in dielectric barrier discharge and applications in industry.

[Ion channels on T lymphocyte].

There is increasing evidence to show that ion channels on lymphocytes play a very important role in the regulation of immune functions. In T lymphocytes, there are three types of ion channels on cell membrane: Ca2+, K+ and Cl- channel. The influx of Ca2+ into T lymphocyte through Ca2+ channel (CRAC) may act as a second messenger to activate T lymphocyte when antigen binds to the receptor (TCR). The efflux of K+ from T lymphocyte through the K+ channel contributes to the formation of T cell membrane potential. The level of the membrane potential may affect the influx of Ca2+ into T cells. Therefore, the activation and the functions of T cell can be regulated by K+ channel indirectly. Cl- channel in T lymphocyte was found in recent years and it is probably involved in the regulation of cell volume. The recent progress on ion channels in T lymphocyte is summarized briefly in the present paper.

A protein in pig spleen similar to immune suppressive protein of stress.

AIM: To purify a protein in pig spleens, which was similar to immune suppressive protein of stress (ISPS), and characterize its properties and functions. METHODS: 1) Pig spleen was extracted in dilute hydrochloric acid. 2) The extract was ultra-filtrated for having high molecular weight proteins (Mr>30 000). 3) The filtrates were purified with FPLC affinity chromatography. 4) The elute from FPLC was used for T-lymphocyte proliferation and ELISA test. 5) Lastly, SDS-PAGE was used to determine the molecular weight and purity of the final product. RESULTS: A protein purified from pig spleen (the pig ISPS homologue) inhibited concanavalin A (Con A)-induced mouse lymphocyte proliferation. The molecular weight of this protein was about Mr 190 000. It has a stronger selectivity against T-lymphocyte line such as Jurkat cell line and mastocyte line (P8l5) and has a weaker inhibitory activity on macrophage line (U937). CONCLUSION: A protein similar to rat/mouse ISPS was found in pig spleen. This may provide an opportunity to study its roles in tumors and autoimmune diseases.