Optimization of Ultrasonic-Assisted Extraction Process of Polysaccharides from American Ginseng and Evaluation of Its Immunostimulating Activity

Ultrasonic-assisted extraction （UAE） of American ginseng polysaccharides （AGP） was investigated using response surface methodology. Three-factor-three-level Box-Behnken design was employed to optimize the ultrasonic power, extraction time and ratio of water to raw material to obtain a high AGP yield. The analysis of variance and response surface plots indicated that ultrasonic power was the most important factor affecting the extraction yield. The optimal conditions were ultrasonic power 400 W, extraction time 71 min, and ratio of water to raw material 33 mL g-1. Under these conditions, the yield of AGP was 8.09%, which was agreed closely to the predicted value. Gas chromatography （GC） analysis showed that AGP was composed of arabinose, rhamnose, galactose, glucose, and galacturonic acid. Fourier transform infrared spectra revealed the general characteristic absorption peaks of AGP. In addition, AGP exhibited good immunostimulating activities by up-regulating the production of nitric oxide and cytokines. Compared with hot water extraction, UAE required shorter extraction time and gave a higher extraction yield, without changing the structure and immunostimulating activity of AGP. The results indicated that UAE could be an effective and advisable technique for the large scale production of plant polysaccharides.     

The Establishment of Double-Transgenic Mice that Co-Express the appA and MxA Genes Mediated by Type A Spermatogonia In vivo

Type A spermatogonial stem cells are the only immortal diploid cells in the postnatal animal that undergo self-renewal through the lifetime of an animal and transmit genes to subsequent generations. In this paper, the generation and characterization of double-transgenic mice co-expressing the Escherichia coli appA gene and human MxA gene generated via the in vivo transfection of type A spermatogonial cells were reported for the ifrst time. The dicistronic expression vector pcDNA-appA-MxA（AMP） and ExGen500 transfection reagent were injected into the testicular tissue of 7-d-old male ICR mice. The mice that underwent testis-mediated gene transfer were mated with wild-type female mice, and the integration and expression of the foreign genes in the offspring were evaluated. Transgenic mice that co-expressed appA and MxA showed a gene integration rate of 8.89%（16/180）. The transgenic mice were environmentally friendly, as the amount of phosphorous remaining in the manure was reduced by as much as 11.1%by the appA gene （P〈0.05）;these animals also exhibited a strong anti-viral phenotype.     

贵州10味道地中药材及其水煎液中铜含量的测定

[目的]测定贵州10味道地中药材及其水煎液中微量元素铜的含量。[方法]采用火焰原子吸收光谱法,测定了贵州10味道地中药材及其水煎液中微量元素铜的含量。[结果]火焰原子吸收光谱法测定铜含量的线性范围为0～1.0μg/ml,相关系数R2=0.9999,平均回收率为101.83%,RSD=0.45%（n=5）。10种中药材中铜的含量为7.0～31.0mg/kg,水煎液中铜的含量为0.3～2.4mg/kg。[结论]为中药材种植和加工过程中的质量控制以及传统中药用药的安全性评价提供依据。     

Cell Production and Expansion in the Primary Root of Maize in Response to Low-Nitrogen Stress

Maize plants respond to low-nitrogen stress by enhancing root elongation. The underlying physiological mechanism remains unknown. Seedlings of maize （Zea mays L., cv. Zhengdan 958） were grown in hydroponics with the control （4 mmol L-1） or low-nitrogen （40 μmol L-1） for 12 d, supplied as nitrate. Low nitrogen enhanced root elongation rate by 4.1-fold, accompanied by increases in cell production rate by 2.2-fold, maximal elemental elongation rate （by 2.5-fold）, the length of elongation zone （by 1.5-fold）, and ifnal cell length by 1.8-fold. On low nitrogen, the higher cell production rate resulted from a higher cell division rate and in fact the number of dividing cells was reduced. Consequently, the residence time of a cell in the division zone tended to be shorter under low nitrogen. In addition, low nitrogen increased root diameter, an increase that occurred speciifcally in the cortex and was accompanied by an increase in cell number. It is concluded that roots elongates in response to low-nitrogen stress by accelerating cell production and expansion.     

Fruit Yield and Quality,and Irrigation Water Use Efifciency of Summer Squash Drip-Irrigated with Different Irrigation Quantities in a Semi-Arid Agricultural Area

Fruit yield, yield components, fruit mineral content, total phenolic content, antioxidant activity and irrigation water use efifciency （IWUE） of summer squash responses to different irrigation quantities were evaluated with a ifeld study. Irrigations were done when the total evaporated water from a Class A pan was about 30 mm. Different irrigation quantities were adjusted using three different plant-pan coefifcients （Kcp, 100% （Kcp1）, 85% （Kcp2） and 70% （Kcp3））. Results indicated that lower irrigation quantities provided statistically lower yield and yield components. The highest seasonal fruit yield （80.0 t ha-1） was determined in the Kcp1 treatment, which applied the highest volume of irrigation water （452.9 mm）. The highest early fruit yield, average fruit weight and fruit diameter, length and number per plant were also determined in the Kcp1 treatment, with values of 7.25 t ha-1, 264.1 g, 5.49 cm, 19.95 cm and 10.92, respectively. Although the IWUE value was the highest in the Kcp1 treatment （176.6 kg ha-1 mm-1）, it was statistically similar to the value for Kcp3 treatment （157.1 kg ha-1 mm-1）. Total phenolic content and antioxidant activity of fruits was higher in the Kcp1 （44.27 μg gallic acid equivalents （GAE） mg-1 fresh sample） and in the Kcp2 （84.75%） treatments, respectively. Major （Na, N, P, K, Ca, Mg and S） and trace （Fe, Cu, Mn, Zn and B） mineral contents of squash fruits were the highest in the Kcp2 treatment, with the exception of P, Ca and Cu. Mineral contents and total phenolic content were signiifcantly affected by irrigation quantities, but antioxidant activity was not affected. It can be concluded that the Kcp1 treatment was the most suitable for achieving higher yield and IWUE. However, the Kcp2 treatment will be the most suitable due to the high fruit quality and relatively high yield in water shortage conditions.     

Effect of Nitric Oxide on the Interaction Between Mitochondrial Malate Dehydrogenase and Citrate Synthase

Mitochondrial malate dehydrogenase （mMDH） and citrate synthase （CS） are sequential enzymes in Krebs cycle. mMDH, CS and the complex between mMDH and CS （mMDH＋CS） were treated with nitric oxide solution. The roles of notric oxide （NO） on the secondary structures and the interactions between mMDH and CS were studied using circular diehroism （CD） and Fourier transform surface plasmon resonance （FT-SPR）, respectivley. The effects of NO on the activities of mMDH, CS and mMDH＋CS were also studied. And the regulations by NO on mMDH and CS were simulated by PyMOL software. The results of SPR conifrmed that strong interaction between mMDH and CS existed and NO could signiifcantly regulate the interaction between the two enzymes. NO reduced the mass percents ofα-helix and increased that of random in mMDH, CS and mMDH＋CS. NO increased the activities of CS and mMDH＋CS, and inhibited the activity of mMDH. Graphic simulation indicated that covalent bond was formed between NO and Asn242 in active site of CS. However, there was no direct bond between NO and mMDH. The increase in activity of mMDH＋CS complex depended mostly on the interaction between NO and CS. All the results suggested that the regulations by NO on the activity and interaction between mMDH and CS were accord with the changes in mMDH, CS and mMDH＋CS caused by NO.     

Transgenic cry1Ab/vip3H＋epsps Rice with Insect and Herbicide Resistance Acted No Adverse Impacts on the Population Growth of a Non-Target Herbivore,the White-Backed Planthopper,Under Laboratory and Field Conditions

Numerous Bt rice lines expressing Cry protein derived from Bacillus thuringiensis Berliner （Bt） have been developed since 1989. However, the potential risks posed by Bt rice on non-target organisms still remain debate. The white-backed planthopper （WBPH）, Sogatella furcifera （Horváth）, is one of the most economically important insect pests of rice in Asian countries and also one of the main non-target herbivores of transgenic rice. In the current study, impacts of transgenic cry1Ab/vip3H＋epsps rice （G6H1） with both insect and herbicide resistance on WBPH were evaluated to ascertain whether this transgenic rice line had potential risks for this sap-sucking pest under laboratory and ifeld conditions. The laboratory results showed that no signiifcant difference in egg developmental duration, nymphal survival rate and female fecundity was found for WBPH between G6H1 and its non-transgenic isoline （XS110）. However, the development duration of nymphs was signiifcantly shorter and female longevity signiifcantly longer when WBPH fed on G6H1 by comparison with those on its control. To verify the results found in laboratory, a 3-yr ifeld trial was conducted to monitor WBPH population using both the vacuum-suction machine and beat plate methods. Although the seasonal density of WBPH nymphs and total density of nymphs and adults were not signiifcantly affected by transgenic rice regardless of the sampling methods, the seasonal density of WBPH adults in transgenic rice plots was slightly lower than that in the control when using the vacuum-suction machine. Based on these results both from laboratory and ifeld, it is clear that our tested transgenic rice line will not lead higher population of WBPH. However, long-term ifeld experiments to monitor the population dynamics of WPBH at large scale need to be conducted to conifrm the present conclusions in future.     

The Effects of Three Mineral Nitrogen Sources and Zinc on Maize and Wheat Straw Decomposition and Soil Organic Carbon

The incorporation of straw in cultivated ifelds can potentially improve soil quality and crop yield. However, the presence of recalcitrant carbon compounds in straw slow its decomposition rate. The objective of this study was to determine the effects of different nitrogen sources, with and without the application of zinc, on straw decomposition and soil quality. Soils were treated with three different nitrogen sources, with and without zinc： urea （CO（NH2）2）, ammonium sulfate （（NH4）2SO4）, and ammonium chloride （NH4Cl）. The combined treatments were as follows：maize （M） and wheat （W） straw incorporated into urea-, ammonium sulfate-, or ammonium chloride-treated soil （U, S, and C, respectively） with and without zinc （Z） （MU, MUZ, WU, WUZ;MS, MSZ, WS, WSZ;MC, MCZ, WC, WCZ, respectively）;straw with zinc only （MZ, WZ）;straw with untreated soil （MS, WS）;and soil-only or control conditions （NT）. The experiment consisted of 17 treatments with four replications. Each pot contained 150 g soil and 1.125 g straw, had a moisture content of 80%of the ifeld capacity, and was incubated for 53 days at 25°C. The rates of CO2-C emission, cumulative CO2-C evolution, total CO2 production in the soils of different treatments were measured to infer decomposition rates. The total organic carbon （TOC）, labile organic carbon （LOC）, and soil microbial biomass in the soils of different treatments were measured to infer soil quality. All results were signiifcantly different （P〈0.05） with the exception of the labile organic carbon （LOC）. The maize and wheat straw showed different patterns in CO2 evolution rates. For both straw types, Zn had a synergic effect with U, but an antagonistic effect with the other N sources as determined by the total CO2 produced. The MUZ treatment showed the highest decomposition rate and cumulative CO2 concentration （1 120.29 mg/pot）, whereas the WACZ treatment had the lowest cumulative CO2 concentration （1 040.57 mg/pot）. The additio     

Comparing Immature Development and Life History Traits in Two Coexisting Host-Feeding Parasitoids,Diglyphus isaea and Neochrysocharis formosa （Hymenoptera：Eulophidae）

Coexisting natural enemies that share a common host resource in the same guild usually exhibit variation in their life history traits, due to their need to share a similar ecological niche. In this study, we compared the immature development times and adult life history traits of two coexisting, host-feeding parasitoids, Diglyphus isaea Walker and Neochrysocharis formosa Westwood （Hymenoptera：Eulophidae）, of which both attack larvae of the same agromyzid leafminers. These two species are both synovigenic, idiobiont parasitoids, whose adults consume host lfuids （“host feeding”） and lay anhydropic eggs. Of the two, D. isaea has a larger body but little or no initial egg load, and engages in similar lifetime host-feeding events. However, it achieves higher fecundity, longer adult longevity, and higher host suppression ability than N. formosa, which has a smaller body and higher initial egg load. Although D. isaea engages in similar lifetime host-feeding events with N. formosa, all of its gains in life history traits per host-feeding event of D. isaea were larger than those of N. formosa. The age-speciifc fecundity and host mortality curves of N. formosa were more skewed in early life than those of D. isaea. In addition, the ovigeny index of N. formosa was negatively correlated to body size. Our results conifrmed that two coexisting parasitoids, which share the same host resource, show different immature development patterns and life history traits, suggesting that different resource allocation mode could be a general rule of coexisting species sharing the same habitat or host.     

ISSR-Based Molecular Characterization of an Elite Germplasm Collection of Sweet Potato （Ipomoea batatas L.） in China

To determine the genetic diversity and population structure of sweet potato accessions cultivated in China, and to establish the genetic relationships among their germplasm types, a representative collection of 240 accessions was analyzed using inter-simple sequence repeat （ISSR） markers. The mean genetic similarity coefifcient, Nei’s gene diversity, and shared allele distance of tested sweet potato accessions were 0.7302, 0.3167 and 0.2698, respectively. The 240 accessions could be divided into six subgroups and ifve subpopulations based on neighbor-joining （NJ） clustering and STRUCTURE results, and obvious genetic relationships among the tested sweet potato accessions were identiifed. The marker-based NJ clustering and population structure showed no distinct assignment pattern corresponding to lfesh color or geographical ecotype of the tested sweet potato germplasm. Analysis of molecular variance （AMOVA） revealed small but signiifcant difference between white and orange-lfeshed sweet potato accessions. Small but signiifcant difference were also observed among sweet potato accessions from the Southern summer-autumn sweet potato region, the Yellow River Basin spring and summer sweet potato region and the Yangtze River Basin summer sweet potato region. This study demonstrates that genetic diversity in the tested sweet potato germplasm collection in China is lower than that in some reported sweet potato germplasm collections from other regions. Pedigree investigations suggest that more diverse Chinese sweet potato varieties should be formed by broadening the selection scope of breeding parents and incorporating the introduced varieties into future breeding programs.     

Effects of Tillage Practices on Water Consumption,Water Use Efifciency and Grain Yield in Wheat Field

Water shortage is a serious issue threatening the sustainable development of agriculture in the North China Plain, with the winter wheat （Triticum aestivum L.） as its largest water-consuming crop. The effects of tillage practices on the water consumption and water use efifciency （WUE） of wheat under high-yield conditions using supplemental irrigation based on testing soil moisture dynamic change were examined in this study. This experiment was conducted from 2007 to 2010, with ifve tillage practice treatments, namely, strip rotary tillage （SR）, strip rotary tillage after subsoiling （SRS）, rotary tillage （R）, rotary tillage after subsoiling （RS）, and plowing tillage （P）. The results showed that in the SRS and RS treatments the total water and soil water consumptions were 11.81, 25.18%and 12.16, 14.75%higher than those in SR and R treatments, respectively. The lowest ratio of irrigation consumption to total water consumption in the SRS treatment was 18.53 and 21.88%for the 2008-2009 and 2009-2010 growing seasons, respectively. However, the highest percentage of water consumption was found in the SRS treatment from anthesis to maturity. No signiifcant difference was found between the WUE of the lfag leaf at the later iflling stage in the SRS and RS treatments, but the lfag leaf WUE at these stages were higher than those of other treatments. The SRS and RS treatments exhibited the highest grain yield （9 573.76 and 9 507.49 kg ha-1 for 3-yr average） with no signiifcant difference between the two treatments, followed by P, R and SR treatments. But the SRS treatment had the highest WUE. Thus, the 1-yr subsoiling tillage, plus 2 yr of strip rotary planting operation may be an efifcient measure to increase wheat yield and WUE.     

Inlfuence of Host Shift on Genetic Differentiation of the Oriental Fruit Fly,Bactrocera dorsalis

Invasion of the oriental fruit lfy, Bactrocera dorsalis, into new niches containing different food sources （a process referred to as host shift）, may cause population genetic differentiation and sympatric speciation. To attempt to infer that experimentally, test populations were established by transferring a subset of the original populations, which had been grown on banana for many generations, onto navel orange, and then subculturing the navel orange population and banana population for at least 20 generations. Four pairs of SSR primers with high polymorphism on laboratory strains were used to detect population genetic differentiation. All six tested populations （the 5th, 10th and 15th generations of B. dorsalis fed on banana and navel orange, respectively） were found to have low genetic diversity. Furthermore, the genetic diversity of the navel orange populations was found to decline after being crossed for several generations. Populations initially were deviated from Hardy-Weinberg equilibrium, however, equilibrium was achieved with increasing numbers of generations in both of the host populations. Limited gene lfows were found among the six populations. The Nei’s standard genetic distances between the two host populations of the same generation were initially low, but increased with generation number. Genetic distances between banana and navel orange populations of the same generation were lower than genetic distances between different generations grown on the same host plant. Analysis of molecular distance （AMOVA） results based on generation groups and host groups demonstrated that genetic variation among generations was greater than that between the two host populations. The results indicated that population genetic differentiation occurred after the host shift, albeit at low level. Biogeography and taxonomy of the B. dorsalis complex revealed that speciation of B. dorsalis might be tightly associated with host shift or host specialization of B. dorsalis following dispersal.     

Myristic Acid （MA） Promotes Adipogenic Gene Expression and the Differentiation of Porcine Intramuscular Adipocyte Precursor Cells

Intramuscular fat （IMF） content is considered to be a key factor that affects the marbling, tenderness, juiciness and lfavor of pork. To investigate the effects of myristic acid （MA） on the differentiation of porcine intramuscular adipocytes, cells were isolated from longissimus dorsi muscle （LDM） and treated with 0, 10, 50 or 100μmol L-1 MA. The results showed that MA signiifcantly promotes the differentiation of intramuscular adipocytes in a dose-dependent manner. MA also led to a parallel increase in the expression of peroxisome proliferator activated receptor-γ（PPARγ） and adipose-related genes, such as glucose transporter 1 （GLUT1）, lipoprotein lipase （LPL）, adipocyte fatty acid binding protein 4 （FABP4/aP2）, fatty acid translocase （FAT）, acetyl-CoA carboxylaseα（ACCα）, adipose triglyceride lipase （ATGL） and fatty acid synthase （FASN）. However, no signiifcant effects of MA were observed on the expression of CAAT enhancer binding protein-α（C/EBPα） or hormone sensitive lipase （HSL）. The expression of pyruvate dehydrogenase kinase 4 （PDK4） was increased by MA during the early stages of differentiation （day 1-3）. In addition, MA also increased the absolute content of C14 （P〈0.001） and saturated fatty acids （SFA） （P〈0.05） to varying degrees, but no effects were observed on other fatty acids. These results suggest that MA might be able to enhance the IMF content of pork and increase the accumulation of myristic and myristoleic acid in muscle, which might have beneifcial implications for human health.     

A Critical Review on Superchilling Preservation Technology in Aquatic Product

aquatic product, known as one of the good resources for white meat, has been widely accepted by the consumers due to its high protein, low fat, especially low cholesterol. With the fast development of living standards around the world, the consumer demands for high quality, nutrition, safety and freshness of ifshery food are increasing. Thus, high efifcient preservation technologies for aquatic products become particularly important. Superchilling is one of the controlled-temperature preservation technologies for seafood. Aquatic products can be kept in better quality under superchilling conditions. This review introduced the principle and development of superchilling process, mainly focusing on research progresses and technical dififculties of superchilling. The growth mechanism of ice crystals and the feasibility of application of computational lfuid dynamics in analyzing the temperatures variation and ice crystals during superchilling progress were also discussed, which will provide theoretical foundation for its improvement and application.     

Rice Grain Damage by Combination and Sequence Infestations by the Rice Leaffolder,Cnaphalocrocis medinalis Guenee （Lepidoptera：Pyralidae）, and the White-Backed Rice Planthopper,Sogatella furcifera Horváth （Hemiptera：Delphacidae）

The rice leaffolder （RLF）, Cnaphalocrocis medinalis Guenée （Lepidoptera：Pyralidae）, and the white-backed rice planthopper （WBPH）, Sogatella furcifera Horváth （Hemiptera： Delphacidae）, are major insect pests in China and several other Asian countries. These two pests commonly occur simultaneously or in a temporal sequence. Thus, the investigation of the effect of complex infestations or temporal sequence infestations by these pests on rice yield has a practical signiifcance for the control of these pests. The present study comprised experiments with the following four different variables in potted rice at the tillering stage：single pest species infestation, complex infestation, complete combination infestation and temporal sequence infestation （C. medinalis infestation prior to S. furcifera and S. furcifera infestation prior to C. medinalis）. The results showed that the four infestations resulted in a signiifcant decrease in 1 000-grain weight （1 000GW） and rate of yield loss （RYL） but an increase in blighted grain rate （BGR）, with a signiifcant positive correlation with the infestation density. However, the inlfuences of the complex infestation, complete combination infestation or sequence infestation on the 1 000GW, BGR and RYL were greater than those of the single pest species infestations but did not have addition effects, i.e., the effects of the complex infestation and combination infestation or sequence infestation on the 1 000GW, BGR and RYL were less than the additive effects of the two single pest species infestations at the same densities. In the condition of the same total infestation pressure, no signiifcant differences in the 1 000GW, BGR and RYL were found between C. medinalis infestation prior to S. furcifera and S. furcifera infestation prior to C. medinalis as well as between the sequence infestation and the complex infestation.     

Do Land Characteristics Affect Farmers’ Soil Fertility Management？

Soil fertility management （SFM） has important implications for sustaining agricultural development and food self-sufifciency. Better understanding the determinants of farmers’ SFM can be a great help to the adoption of effective SFM practices. Based on a dataset of 315 plots collected from a typical rice growing area of South China, this study applied statistical method and econometric models to examine the impacts of land characteristics on farmers’ SFM practices at plot scale. Main results showed that in general land characteristics affected SFM behaviors. Securer land tenure arrangements facilitated effective practices of SFM through more diversiifed and more soil-friendly cropping pattern choices. Plot size signiifcantly reduced the intensities of phosphorus and potassium fertilizer application. Given other factors, 1 ha increase in plot size might reduce 3.0 kg ha-1 P2O5 and 1.8 kg ha-1 K2O. Plots far from the homestead were paid less attention in terms of both chemical fertilizers and manure applications. Besides, plots with better quality were put more efforts on management by applying more nitrogen and manure, and by planting green manure crops. Signiifcant differences existed in SFM practices between the surveyed villages with different socio-economic conditions. The ifndings are expected to provide important references to the policy-making incentive for improving soil quality and crop productivity.     

Molecular Mapping of a Stripe Rust Resistance Gene YrH9020a Transferred from Psathyrostachys huashanica Keng on Wheat Chromosome 6D

Stripe rust （yellow rust）, caused by Puccinia striiformis f. sp. tritici （Pst）, is one of the most devastating diseases of wheat throughout the world. H9020-1-6-8-3 is a translocation line originally developed from interspeciifc hybridization between wheat line 7182 and Psathyrostachys huashanica Keng and is resistant to most Pst races in China. To identify the resistance gene（s） in the translocation line, H9020-1-6-8-3 was crossed with susceptible cultivar Mingxian 169, and seedlings of the parents, F1, F2, F3, and BC1 generations were tested with prevalent Chinese Pst race CYR32 under controlled greenhouse conditions. The results indicated that there is a single dominant gene, temporarily designated as YrH9020a, conferring resistance to CYR32. The resistance gene was mapped by the F2 population from Mingxian 169/H9020-1-6-8-3. It was linked to six microsatellite markers, including Xbarc196, Xbarc202, Xbarc96, Xgpw4372, Xbarc21, and Xgdm141, lfanked by Xbarc96 and Xbarc202 with at 4.5 and 8.3 cM, respectively. Based on the chromosomal locations of these markers and the test of Chinese Spring （CS） nullitetrasomic and ditelosomic lines, the gene was assigned to chromosome 6D. According to the origin and the chromosomal location, YrH9020a might be a new resistance gene to stripe rust. The lfanking markers linked to YrH9020a could be useful for marker-assisted selection in breeding programs.