微卫星PCR产物变性与非变性PAGE-银染检测方法的比较

用鸡的微卫星引物对6个中国地方鸡种的两个微卫星位点进行PCR扩增。将扩增产物在变性与非变性聚丙烯酰胺凝胶（PAGE）上进行电泳,经银染,表明微卫星产物在二者上的电泳结果有明显的差异。在非变性聚丙烯酰胺凝胶中,表现为有较多的非特异带,而在变性胶中微卫星扩增产物条带清晰,易于鉴定。Abstract：The genomic DNAs from six chicken breeds in China were amplified using two microsatellite primers. The PCR products were detected by non-denatured and denatured PAGE gels respectively, and the gels were dyed by silver. There were distinct differences between the two kinds of gel. In non-denatured gels. There were many nonspecific bands while clear purposed bands were showed in denatured gels.     

简单快速的DNA银染和胶保存方法

本文介绍了一套简单快速的DNA银染以及胶保存的方法,整个过程仅需10~15分钟,而且背景浅,条带清楚,灵敏度高,稳定性好。胶保存采用双层玻璃纸夹心法,可长久地保存胶显色时的原貌。以常规PAG胶检测和HLA的SSCP分型为例,利用该套方法进行了银染以及胶的保存,均得到了满意的结果。该方法具有推广价值。 Abstract:This paper introduced the simple and rapid methods of silver staining and gel preservation.It was taken only about 10 and 15 minutes to stain a gel.The background of gel was light,the bands were clear,the sensibility was high and the stabilization was well by the method of silver staining.The gel preservation adopted a method named two-layer transparent plastic paper "Sandwich" which could keep the gel with primitive colors for a long time.The methods were used on PAG checking and SSCP typing of HLA and the results were satisfactory.The set of methods are expected to be widely used in laboratories.     

Evaluation of protocols used in 2-d electrophoresis for proteome analysis of young rice caryopsis

In order to obtain a high-resolution electrophorogram of rice young panicle proteome, we evaluated various protocols commonly used in two-dimensional (2D) polyacrylamide gel electrophoresis (PAGE) of proteins, including gel staining protocol, pH range of immobilized pH gradient (IPG) strips and sample loading quantity. Results showed that a silver staining protocol using sensitized solution containing glacial acetic acid, sodium acetate and sodium thiosulfate (reported by Heukeshoven and Dernick in 1988) and a Coomassie Brilliant Blue staining method using solution containing G-250, ammonium sulfate and phosphoric acid (reported by Pink et al in 2010) demonstrated the superior staining effect. In addition, we also showed that higher resolution was achieved when IPG gel strip with pH range of 5-8 was used, compared to that with pH range of 4-7. Finally, the optimal loading quantity was determined as 130 μg using the 17 cm-long nonlinear IPG strip with pH 5-8 in combination with the silver nitrate staining protocol. The evaluated results would be helpful in proteome analysis of young rice caryopsis.     

Purification and characterization of glyceraldehyde-3-phosphate dehydrogenase from European pilchard Sardina pilchardus

The NAD＋-dependent cytosolic glyceralehyde-3-phosphate dehydrogenase （GAPDH; EC 1.2.1.12） was purified from the skeletal muscle of European pilchard Sardina pilchardus and its physicochemical and kinetic properties were investigated. The purification method consisted of two steps, ammonium sulfate fractionation followed by Blue Sepharose CL-6B chromatography, resulting in an approximately 78-fold increase in specific activity and a final yield of approximately 25%. The Michaelis constants （Kin） for NAD＋ and D-glyceraldehyde-3-phosphate were 92.0 μM and 73.4 μM, respectively. The maximal velocity （Vmax） of the purified enzyme was estimated to be 37.6 U/mg. Under the assay conditions, the optimum pH and temperature were 8.0 and 30 ℃. The molecular weight of the purified enzyme was 37 kDa determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Non-denaturing polyacrylamide gels yielding a molecular weight of 154 kDa suggested that the enzyme is a homotetramer. Polyclonal antibodies against the purified enzyme were used to recognize the enzyme in different sardine tissues by Western blot analysis. The isoelectric point, obtained by an isoelectric focusing system in polyacrylamide slab gels, revealed only one GAPDH isoform （pI 7.9）.     

The changes in water-use efficiency and stoma density of Leymus chinensis along Northeast China Transect

Leymus chinensis is a keystone species in the temperate zone grassland of China. Along the NECT (Northeast China Transect) in 2001, water-use efficiency of L. chinensis was analyzed with δ¹³C, and changes in the stoma density of its leaves were observed and computed under a microscope. Results showed that the ecological plasticity modulation of the stoma density of L. chinensis and its water-use efficiency were two important mechanisms for its broad ecological adaptability. From east to west along the NECT, the δ¹³C of the species varied from -27.49‰ to -23.57‰, consisting with the reduction of annual precipitation, soil water and annual average temperature, but increased with the increase of the elevation of sampling sites. The stoma density increased from 96.9/mm² to 169.5/mm², indicating that the water-use efficiency for the species was improved along the gradient. The linear coefficient between the two parameters was significant (R² = 0.7338). The results of a stepwise regression analysis showed that the soil water was the first marked factor for determining the stoma density, and the next was the annual precipitation, which suggested that the water factors were the primary ecological factors influencing the stoma density of L. chinensis. The findings in this study showed that the responses of the stoma density and the water-use efficiency for L. chinensis to environmental changes were very complicated. They may be the outcome operated synthetically by all environmental factors in the long-term adaptation to different ecological environments, including human activity, for L. chinensis.     

The changes in water-use efficiency and stoma density of Leymus chinensis along Northeast China Transect

Leymus chinensis is a keystone species in the temperate zone grassland of China. Along the NECT (Northeast China Transect) in 2001, water-use efficiency of L. chinensis was analyzed with δ¹³C, and changes in the stoma density of its leaves were observed and computed under a microscope. Results showed that the ecological plasticity modulation of the stoma density of L. chinensis and its water-use efficiency were two important mechanisms for its broad ecological adaptability. From east to west along the NECT, the δ¹³C of the species varied from -27.49‰ to -23.57‰, consisting with the reduction of annual precipitation, soil water and annual average temperature, but increased with the increase of the elevation of sampling sites. The stoma density increased from 96.9/mm² to 169.5/mm², indicating that the water-use efficiency for the species was improved along the gradient. The linear coefficient between the two parameters was significant (R² = 0.7338). The results of a stepwise regression analysis showed that the soil water was the first marked factor for determining the stoma density, and the next was the annual precipitation, which suggested that the water factors were the primary ecological factors influencing the stoma density of L. chinensis. The findings in this study showed that the responses of the stoma density and the water-use efficiency for L. chinensis to environmental changes were very complicated. They may be the outcome operated synthetically by all environmental factors in the long-term adaptation to different ecological environments, including human activity, for L. chinensis.     

AFLP分析中多态性扩增产物的回收、克隆及鉴定

本研究在摸索和优化了水稻AFLP分析体系的基础上,发展了多态性AFLP产物的高效克隆方法。特异AFLP扩增产物直接从变性聚丙烯酰胺凝胶上分离纯化,再经过一至二轮PCR扩增,即可高效地克隆于pGEM-Teasy vector系统中。本实验利用该方法成功地克隆了水稻温敏核不育等位突变系546 0S和5460F间的4个多态性AFLP产物,Southern bloting分析证明其中3个产物在水稻基因组中为单拷贝序列,另一个为低拷贝序列。AFLP技术强有力的多态性检出能力再结合多态性扩增产物的高效克隆方法,为寻找与目标基因紧密连锁的分子标记提供了有力工具。 Abstracts:An efficient method for cloning DNA fragment from denaturing polyacrylamide gels was developed to allow the isolation of specific bands obtained from amplified fragment length polymorphism(AFLP)products.After isolation and purification from the thin denaturing polyacrylamide gels,specific AFLP products were successfully cloned after one or two rounds of PCR reamplification.Using this method 4 polymorphic AFLP products between a pair of rice allelic lines differing for thermo-sensitive genic male sterile(TGMS)ene were cloned and it was confirmed that 3 of the AFLP products represented single copy sequences and the other 1 represented low copy sequence in rice genome.     

Use of 5´-anchored primers for the enhanced recovery of specific microsatellite markers in Brassica napus L.

Microsatellite markers have assumed great significance in biological research. The isolation and characterisation of microsatellites involves DNA library construction and screening, DNA sequencing, primer design and PCR optimisation. When a microsatellite is situated close to the beginning or end of a cloned fragment, specific primers cannot be designed for one of the flanking sequences, thus hindering the utilisation of such microsatellites as markers. The present approach was to use one 5′-anchored primer complementary to the microsatellite sequence in combination with one specific Cy5- labelled primer with a view to retrieving useful microsatellites, which would otherwise be lost. Six pairs of a 5′ anchored primer and a specific primer were used across a set of 31 Brassica napus winter cultivars and one accession each of five additional Brassica species. Using laser fluorometry a single labelled product was observed after amplification with each of four primer pairs, and one primer pair gave two labelled products. Three products corresponded in size with the products expected if 5′ anchoring was effective, indicating the amplification of locus-specific full-length products including all of the microsatellite repeats. All six primer pairs showed polymorphisms across the Brassica species examined, but only one primer pair showed polymorphisms within B. napus, making it useful for genetic analysis in rapeseed cultivars. The other primer pairs could be useful in studying gene introgression into B. napus or for investigating interspecific crosses involving different Brassica species. Received: 5 August 1999 / Accepted: 1 November 1999     

Construction of Oryza sativa genome contigs by fingerprint strategy

We described the construction of BAC contigs of the genome of a indica variety of Oryza sativa.Guang Lu Ai 4. An entire representative(Sixfold coverage of rice chromosomes)and genetically stable BAC library of rice genome constructed in this lab has been systematically analysed by restriction enzyme fragmentation and polyacrylamide gel electrophoresis.And all the images thus obtained were subject to image-processing,which consisted of preliminary location of bands,cooperative tracking of lanes by correlation of adjacent bads.a precise densitometric pass,alignment at the marker bands with the standard,optional interactive editing,and normalization of the accepted bands.The contigs were generated based on the Computer Software specially designed for genome mapping.The number of contigs with 600 kb in length on average was 464.of contigs with 1000kb in length on average was 107; of contigs with 1500 kb in length on average was Construction of Oryza Sativa genome contigs.23.Therefor,all the contigs we have obtained ampunted up to 420 megabases in length.Considering the size of rice genome(430 megabased),the contigs generated in this lab have covered nearly 98% of the rice genome.We are now in the process of mapping the contigs to chromosomes.     

有和无甘油的聚丙烯酰胺胶在检测突变时的差别

有文献报道在非变性的聚丙烯酰胺中加入甘油可提高SSCP检测的灵敏度。我们的实验结果建议研究者在进行SSCP筛查未知突变时最好采用不加甘油的非变性的聚丙烯酰胺胶,这既省力省钱,又灵敏。在判读SSCP胶时,千万不要看到在双链带位置有一条比正常迁移率慢的带就判定为插入突变。此时要判定突变的性质,最好测序。 Abstract：It was reported that glycerol in the non-denatured SSCP polyacrylamide gel could increase the sensibility of detecting mutation. We detected the mutation of PKD 1 gene in the patients with autosomal dominant polycystic kidney disease.PCR com bined with SSCP(single-strained conformation polymorphism),the non-denatured 10% polyacrylamide gel without glycerol or 10% polyacrylamide gel with 5% glycerol and DNA sequencing method were used.Our results showed that four single strand b ands were found in the non-denatured polyacrylamide gel without glycerol while t wo single strand bands were found in the polyacrylamide gel with glycerol in the same patient.Sequence showed there is a deletion of G in one DNA molecular and a G→A substitution in another DNA molecular in the patient with abnormal shift SSCP bands.Therefore, our experiment suggested that non-denat ured polyacrylamide gel was better than the polyacrylamide gel with glycerol in detection mutation,and it will save labor and money.It also suggeste d that one basedeletion can cause a slow double-strand DNA following the normal double strand band,which was caused by the heterogeneous DNA molecule formed bet ween the normal DNA strand and the one base deletion DNA strand with the protrud ing base.Our results suggest that when judging mutation in SSCP gel,it is not re liable to decide that mutation is inversion according to slow mobility in the ge l,and when the characteristic of mutation need to be judged,it must be sequenced .     

Embryogenesis induction in petals of Araujia sericifera

The embryogenic capacity of Araujia sericifera petals and some of the factors involved in the induction of embryos was investigated. The influence of 6-benzyladenine and α-naphthalene acetic acid, light intensity (90 or 5 μmol m^-2 s^-1) and silver thiosulphate (inhibitor of ethylene action) were studied. It was found that petals are an easy system in which to induce somatic embryogenesis. Plants were recovered from somatic embryos. Although 6-benzyladenine is essential for inducing an efficient response, a high dosage increased callogenesis and reduced embryogenesis. The highest rate of embryogenesis is induced with high light intensity (90–100 μmol m^-2 s^-1), even though the presence of silver thiosulphate in the medium markedly reduced embryo induction. This revised version was published online in June 2006 with corrections to the Cover Date.     

The effects of planktivorous fishes on the plankton community in a eutrophic lake

Stocking silver carp, a phytoplankton feeder, and bighead carp, an omnivorous plankton feeder, into an eutrophic lake at high densities caused a dramatic change in the lake ecosystem.Microcystis, which had been dominant in summer and a main food of the fishes decreased markedly, and green algae smaller than 10 μm then became dominant. Consequently, chlorophyll-a per unit area decreased slightly, while the rate of production was higher than that in the previous years. As the total density of the fishes increased (from 0.09 to 0.11 fish m⁻²), the growth of silver carp was retarded, while that of bighead carp increased.Microcystis, was unable to become dominant due to increased grazing pressure by the fishes, and small green algae became dominant. The lake conditions thus became more favourable for zooplankters which selectively consumed small green algae, and accordingly, the production of zooplankton rose. Bighead carp consumed more animal food, which they assimilate at a higher rate than plant food, and grew better in spite of the fact that the fish density increased. The feeding rate of silver carp was greatly reduced because the green algae were too small to ingest, and the fish therefore grew poorly. Results of a computer simulation of a model consisting of five compartments, representing the blue-green algae, green algae, zooplankton, silver and bighead carp, support the food-web change observed in the lake.     

新Y-STR DYS605在山西汉族人群中的多态性分布

为了应用更多的Y染色体特异性STR基因座以用于法医学和人类遗传学研究,本文用PCR结合PAGE技术检测128例山西汉族无关男性DYS605等位基因分布状况。结果显示：山西地区汉族男性DYS605基因座观察到22,21,20,19,18共5个等位基因,基因频率分别为0.0156;0.1797;0.4531;0.2891;0.0625。等位基因20和19之间的电泳距离在非变性胶上非常接近,要有足够的电泳距离才能区分。测序表明该基因座包括3个串联重复区,其中一个为可变重复区。20例女性DNA未发现扩增产物。Abstract: We study the polymorphism at DYS605 ,a new tetranucleotide Y-STR locus,in a Chinese Han population of Shanxi to meet the need of more genetic markers in forensic practice and genetic analysis. DNA were extracted from 128 unrelated male venous blood, and amplified using GDB primers. PCR products were detected using non-denaturing polyacrylamide gel electrophoresis and silver staining. Five alleles named 22,21,20,19,18 were observed with frequency of 0.0156;0.1797;0.4531;0.2891;0.0625. PCR products were not found in female DNA. Using a long enough gel for a long electrophoresis time is strongly encouraged because the rung between allele 20 and allele19 is smaller than expected. Allele sequences show that the repetitive units of DYS605 were composed with the variant units and non-variant units.     

Effect of a mistletoe extract (Iscador® QuFrF) on viability and migratory behavior of human peripheral CD4+ and CD8+ T lymphocytes in three-dimensional collagen lattices

Summary Migration and tissue distribution of immunocompetent cells may be critical prerequisites for efficient immune surveillance. The effect of various concentrations of the mistletoe extract Iscador? QuFrF on the locomotory behavior and viability of immunomagnetically isolated human CD4⁺ and CD8⁺ T lymphocytes within three-dimensional collagen gels was investigated. Although variation in baseline activities of spontaneously migrating T cells was donor-dependent, a dose-dependent stimulation of the locomotory activity in both CD4⁺ and CD8⁺ T cells for noncytotoxic concentrations of Iscador QuFrF (0.25–1.25 μg/ml) was detected. The optimal concentration of mistletoe extract and time of maximal response were specific for each donor. As shown by cell tracking and subsequent data analysis, CD4⁺ T cells exposed to the mistletoe extract displayed a significant increase in mean velocity and time locomoting; total distance migrated was nearly doubled. In contrast, CD8⁺ T cells showed less pronounced changes in these critical parameters. Cytotoxic effects of the mistletoe preparation on T lymphocytes, which could at least partially be attributed to the induction of apoptosis, were drastically reduced in the presence of fetal calf serum in the culture system. Our data suggest that the direct stimulation of T-cell migration in the presence of mistletoe components may modulate in a dose-dependent manner the system of immune surveillance and recognition in patients under mistletoe therapy.     

Water-holding capacity of ground covers and soils in alpine and sub-alpine shrubs in western Sichuan, China

The water-holding functions of soils and ground covers in terms of moss and litters in the three major shrubs at different altitude gradients were studied using field investigation. The water-holding functions were measured and expressed with Biomass (t/hm²) of moss and litters, along with their maximal water holding capacity (MWHC, t/hm²) and maximal water holding rate (MWHR, %). The physical characteristics of the soils included bulk density, MWHC, capillary water holding capacity (CWHC), and least water holding capacity (LWHC). The result showed that Rhododendron przewalskii shrub exhibited the highest water-holding capacity among the three types. The average MWHC of the moss, litters, and at a depth of 0–40cm in R. przewalskii at different elevation gradients was 46.73,139.98 t/hm², and 2216.92 t/hm², respectively, whereas the average MWHC of the moss, litters, and soils in Quercus aquifolioides was 1.64, 72.08 t/hm² and 2114.88 t/hm², respectively. There was no moss in Quercus cocciferoides, and the average MWHC of litters and soils at a depth of 0–40 cm at different elevation gradients was 84.55 t/hm² and 2062.83 t/hm², respectively. The biomass and MWHC of the moss layer in R. przewalskii shrub significantly decreased with increasing elevation, whereas the reverse occurred in Q. aquifolioides before the maximum was reached at 3400 m, and then the SCM and MWHC decreased. MWHR of the moss layer in R. przewalskii was higher than that in Q. aquifolioides. The biomass and MWHC of the litters in R. przewalskii and Q. aquifolioides decreased with increasing elevation, whereas the reverse occurred in Q. cocciferoide. Regardless of shrub types, soil bulk density increased significantly with increasing soil depth, whereas MWHC decreased significantly with increasing soil depth. Significant decrease in CWHC and LWHC were found only in certain shrub communities. The MWHC with respect to the 0–40cm soil depth significantly decreased with increasing elevation only in R. przewalskii shrub, whereas there was no significant difference in MWHCs among the different elevation gradients for the other two types.     

Water-holding capacity of ground covers and soils in alpine and sub-alpine shrubs in western Sichuan, China

The water-holding functions of soils and ground covers in terms of moss and litters in the three major shrubs at different altitude gradients were studied using field investigation. The water-holding functions were measured and expressed with Biomass (t/hm²) of moss and litters, along with their maximal water holding capacity (MWHC, t/hm²) and maximal water holding rate (MWHR, %). The physical characteristics of the soils included bulk density, MWHC, capillary water holding capacity (CWHC), and least water holding capacity (LWHC). The result showed that Rhododendron przewalskii shrub exhibited the highest water-holding capacity among the three types. The average MWHC of the moss, litters, and at a depth of 0–40cm in R. przewalskii at different elevation gradients was 46.73,139.98 t/hm², and 2216.92 t/hm², respectively, whereas the average MWHC of the moss, litters, and soils in Quercus aquifolioides was 1.64, 72.08 t/hm² and 2114.88 t/hm², respectively. There was no moss in Quercus cocciferoides, and the average MWHC of litters and soils at a depth of 0–40 cm at different elevation gradients was 84.55 t/hm² and 2062.83 t/hm², respectively. The biomass and MWHC of the moss layer in R. przewalskii shrub significantly decreased with increasing elevation, whereas the reverse occurred in Q. aquifolioides before the maximum was reached at 3400 m, and then the SCM and MWHC decreased. MWHR of the moss layer in R. przewalskii was higher than that in Q. aquifolioides. The biomass and MWHC of the litters in R. przewalskii and Q. aquifolioides decreased with increasing elevation, whereas the reverse occurred in Q. cocciferoide. Regardless of shrub types, soil bulk density increased significantly with increasing soil depth, whereas MWHC decreased significantly with increasing soil depth. Significant decrease in CWHC and LWHC were found only in certain shrub communities. The MWHC with respect to the 0–40cm soil depth significantly decreased with increasing elevation only in R. przewalskii shrub, whereas there was no significant difference in MWHCs among the different elevation gradients for the other two types.     

The influence of substratum age on patterns of protozoan assemblages in freshwater Aufwuchs — a case study

The sulfate reduction rate was measured for almost four years in the profundal sediments of Lake Kizaki, a mesotrophic lake in central Japan. The rate was generally highest in the surface layer and decreased with depth. Seasonally, sulfate reduction tended to be high in spring and summer, and then to decrease until the end of stratification (December) in spite of a constant in situ temperature of around 6 °C, although fluctuations were found in every year. The rate also fluctuated greatly according to year. The maximum rate of sulfate reduction was 0.33 mmol m⁻² d⁻¹ in May, 1990, and the minimum was 0.004 mmol m⁻² d⁻¹ in March, 1993. These relatively low rates, compared with those reported for freshwater sediments, seem to be due to low concentrations of sulfate in the sediments (5–23 μmol l⁻¹ in the surface layer). The rate was highly correlated with the concentration of sulfate in the sediments. The addition of sulfate stimulated sulfate reduction in all sediment samples tested, but adding lactate did not. Therefore, sulfate reduction should be limited mainly by the supply of sulfate. Measurements of sulfate reduction rates at different concentrations of added sulfate revealed a low concentration of half-saturation constant as low as 12 μmol l⁻¹.     

Gelling agents for tissue culture of the seaweed Hizikia fusiformis

Callus and blade formation of the seaweed Hizikia fusiformis depended on the gelling agents used under axenic culture conditions. Excised cylindrical pieces (5 mm) of the hold fast were cultured on seven different gelling agents in seawater with added Provasoli's enrichment (PESI), at 40 μmol m⁻² s⁻¹ light intensity, 18 −C for 1 month. The highest percent of callus formation (47%), from holdfast pieces, was produced on solid medium composed of 2.0% high gel strength agar. No callus was formed in liquid medium. Blades, from holdfast pieces, were formed in PESI liquid medium at the rate of 45%, while the high level of axenic blade formation (30%) on solid support was observed on 0.5% high gel strength agar. Callus and blade were identified with the original strain, at the DNA level, using random amplified polymorphic DNAs. This revised version was published online in August 2006 with corrections to the Cover Date.     

Carbon accumulation and distribution in Pinus massoniana and Cunninghamia lanceolata mixed forest ecosystem in Daqingshan, Guangxi, China

Carbon accumulation and distribution were studied at three sampling plots in a 13-year-old mixed planatation of Pinus massoniana and Cunninghamia lanceolata in Daqingshan, Guangxi, China. The results showed that carbon content varied with tissues and tree species, but the total carbon content of Pinus massoniana was higher than that of Cunninghamia lanceolata. The average tissue carbon contents of Pinus massoniana were: wood (58.6%) > root (56.3%) > branch (51.2%) > bark (49.8%) > leaf (46.8%), while those of Cunninghamia lanceolata were: bark (52.2%) > leaf (51.8%) > wood (50.2%) > root (47.5%) > branch (46.7%). The carbon contents of the soil (at a depth of 60cm) ranged from 1.45% to 1.84% with an average of 1.70%. Carbon contents were higher in the surface soil (0–20cm) than in the deep layer (below 20cm). The average carbon contents were the highest for trees (51.1%), followed by litter (48.3%), shrubs (44.1%), and herbs (33.0%). The biomass of the trees in the three plots ranged from 85.35 t hm^-2 to 101.35 t hm^-2 with an average of 93.83 t hm^-2, in which 75.7%–82.6% was Pinus massoniana. The biomass of the understory was 2.10–3.95 t hm^-2 with an average of 2.72 t hm^-2, while the standing stock of ground litter was 5.49–7.91 t hm^-2 with an average of 6.75 t hm^-2. The carbon storage in the mixed plantation reached the maximum in the soil layer (69.02%), followed by vegetation (29.03%), and standing litter (1.82%). The carbon storage in the tree layer occupied 23.90% of the total ecosystem and 97.7% of the vegetation layer. Pinus massoniana accounted for 65.39% of the total carbon storage in the tree layer. Tissue carbon storage was directly related to the corresponding amount of biomass. Trunks had the highest carbon storage, accounting for 53.23% of the trees in Pinus massoniana and 55.57% in Cunninghamia lanceolata, respectively. Roots accounted for about 19.22% of the total tree carbon. The annual net productivity of the mixed plantation was 11.46 t hm^-2a^-1, and that of sequestered carbon was 5.96 t hm^-2a^-1, which was equivalent to fixing CO₂ of 21.88 t hm^-2a^-1. The plantation was found to be an important sink of atmospheric CO₂.     

Multichannel automated chamber system for continuous monitoring of CO2 exchange between the agro-ecosystem or soil and the atmosphere

A multichannel automated chamber system was developed for continuous monitoring of CO₂ exchange at multiple points between agro-ecosystem or soil and atmosphere. This system consisted of an automated chamber subsystem with a CO₂ concentration analyzer and a data logging subsystem. Both subsystems were under the control of a programmable logic controller (PLC). The automated chamber subsystem contained 18 chambers (50 cm × 50 cm × 50 cm) and a compressor. The chamber lids were closed and can be automatically opened. During measurement, one of the 18 chambers was kept closed for three minutes for measuring and the other chambers were kept open to maintain the natural soil conditions to the maximum extent. Environmental variables were simultaneously measured using sensors and recorded by the data logger. The reliability of the multichannel automated chamber system was tested and the results showed that the turbulence of the fans had no significant effect on the CO₂ exchange. The changes in the air and the temperature of soil and soil moisture inside the chambers, caused by the enclosure of the chambers, were not significant. The net ecosystem CO₂ exchange for the wheat ecosystem was ?2.35 μmol·m^?2·s^>?1 and the soil respiration was 3.87 μmol·m^?2·s^>?1 in the wheat field, and 6.61 μmol·m^?2·s^>?1 in the apple orchard.