Low Co-Cultivation Temperature at 20°C Resulted in the Reproducible Maximum Increase in Both the Fresh Weight Yield and Stable Expression of GUS Activity after <i>Agrobacterium tumefaciens</i>-Mediated Transformation of Tobacco Leaf Disks

The importance of controlled temperature during the four-days co-cultivation period was evaluated under the most physiologically relevant conditions for Agrobacterium tumefaciens-mediated transformation of tobacco (Nicotiana tabacum L. cv. Xanthi (nn, Smith)) leaf disks. We compared the effect of temperatures ranging from 15°C, 18°C, 20°C, 22°C to 25°C on the stable expression of β-glucuronidase (GUS) activity of 14 days old hygromycin-selected leaf disks, and on the increase in the fresh weight yield of 28 days old kanamycin-selected calli. The highest average of GUS activity was obtained at 20°C among the five temperatures tested although the difference between the 18°C and 20°C treatment was not statistically significant. The GUS activity at 15°C was statistically lower than those at 18°C and 20°C. The GUS activity in 22°C treatment was an intermediate between the highest (18/20°C) and second highest averages (15°C), and was not statistically significantly different. The lowest average of GUS activity was observed at 25°C. The highest increase in the plate average of fresh weight yield was obtained at 20°C among the five temperature tested. The 20°C treatment was statistically significantly better than the 15°C and 18°C treatments. The 20°C co-cultivation treatment resulted in the higher FW yield than 22°C and 25°C even though the differences were not statistically significant. In conclusion, low co-cultivation temperature at 20°C resulted in the reproducible maximum increase in both the fresh weight yield and stable expression of GUS activity after transformation of tobacco leaf disks.

Effects of Rice-duck Mutualism on Diseases Insect Pests and Weeds and Economic Benefits

[Objective] Study on the effects of rice-duck mutualism on weeds and insects pests and economic benefits of paddy field. [Method] Comparison of the incidence of weeds, sheath blight and insects pest under rice-duck mutualism, conventional cultivation and control treatment, the yield and economic benefits were analyzed under the 3 treatments. [Result] Average occurrence of weeds in rice-duck mutualism group decreased by 2.33 and 52.0g ind/m^2 compared with that in conventional cultivation and control treatment ; the control rate of mutualism was up to 75% against rice hopper, but just between 25% -60% against rice leaf roller and Chilo suppressalis. The rates of diseased plant and diseased bell against rice sheath blight were higher and disease indices were lower compared with control group. The yield of mutualism group was identical with conventional cultivation, Which was greatly higher than that of control group. The results suggested an higher economic benefits and lower cost benefit ratio for rice-duck mutualism treatment. [Conclusion] Rice-duck mutualism gives birth to a positive effect to control the diseases, insect pests and weeds, as well as to economic benefits, providing basis on extension of rice-duck mutualism system.

Rice-duck co-culture benefits grain 2-acetyl-1-pyrroline accumulation and quality and yield enhancement of fragrant rice

Rice-duck co-culture is an integrated farming technology that benefits rice production, grain quality, and ecological sustainability in paddy fields. However, little is known about the effects of rice-duck co-culture on enzyme activity involved in the biosynthesis of 2-acetyl-1-pyrroline (2-AP), the volatile that gives fragrant rice its' distinctive and sought-after aroma. The present study aimed to examine the influence of rice-duck co-culture on the photosynthesis, yield, grain quality, rice aroma, and the enzymes involved in 2-acetyl-1-pyrroline biosynthesis in the cultivar Meixiangzhan 2 during the early and late rice growing seasons of 2016 in Guangzhou, China. We compared the rice grown in paddy fields with and without ducks. We found that rice-duck co-culture not only improved the yield and quality of fragrant rice grain, but also promoted the precursors of 2-AP biosynthesis formation and 2-AP accumulation in the grain. Grain 2-AP content in rice-duck co-culture was noticeably increased with 9.60% and 20.81% in early and late seasons, respectively. Proline and pyrroline-5-carboxylic acid (P5C) (precursors of 2-AP biosynthesis) and the activity of enzymes such as proline dehydrogenase (ProDH), ornithine aminotransferase (OAT) and Δ1 pyrroline-5-carboxylic acid synthetase (P5CS) were all improved by 10.15%–12.99%, 32.91%–47.75%, 17.81%–26.71%, 6.25%–21.78%, and 10.58%–38.87% under rice-duck co-culture in both seasons, respectively. Overall, our results suggest that rice-duck co-culture is an environmentally-friendly and sustainable approach to improving rice aroma and grain quality of fragrant rice.

Influencing Factors on Rice Sheath Blight Epidemics in Integrated Rice-Duck System

Sheath blight, a disease caused by the fungus Rhizoctonia solani Kuhn （anamorph）, has been the most economically significant disease of rice. It was frequently reported that the disease was well-controlled in integrated rice-duck system without the employment of fungicides. However, the effecting factors behind this phenomenon were rarely reported. In this research, experiment was carried out between two treatments, rice combined with ducks （RD） and conventional rice field without ducks rearing （CK） in early season rice paddy, to investigate the variations of sclerotia in floodwater and on rice plant, microclimate 10 cm above the waterline in rice paddy and activity of protective enzymes in rice plants. The results showed that the floating sclerotia in floodwater in RD was 86-91% lower than that in CK, and adhering sclerotia in rice plant in RD was 67-78% lower than that in CK. The relative humidity tested significantly lower and light intensity tested significantly higher in RD. The temperature in the early rice growth stages in RD was slightly lower than that in CK, but it was significantly higher （32.3-36.5~C） in the middle stage rice growth stages. The polyphenoloxidase （PPO） activity in RD were lower than that in CK, but the enhanced activity of phenylalanine ammonia-lyase （PAL）, peroxidase （POD） and Chitinase was observed in different stages of rice growth in RD, especially the Chitinase which showed higher activity in all investigating days.

Studies on Technique of Reducing Methane Emission in a Rice-Duck Ecological System and the Evaluation of Its Economic Significance

The rice-duck ecological system is one of the major practices of the traditional Chinese agriculture. A study on the effect of reducing methane emission using this practice provided theoretical and practical basis for further development and utilization of this classical agricultural technique. The effect of reducing methane emission and the economic benefits of rice-duck ecological system were studied by carrying out a field experiment and by using economic methodology. The daily variation of CH4 emission in late rice paddy field was basically consistent with the daily variation of atmospheric temperature. The highest emission occurred at the full tillering stage of late rice with a rate of 24.1 or 32.2 or 40.5 mg m^-2 h^-1 in no-tillage area with duck and no-tillage area without duck and conventional-tillage area without duck, respectively. The inhibition of methane emission was apparently effective in the rice-duck ecological system during the initial tillering stage and the full tillering stage. Compared to the no-tillage area without duck, methane emission decreased by 2.333 g m^-2. Compared to the conventional-tillage area without duck, methane emission decreased by 4.723 g m^-2. During the production period of late rice, the amount of methane emission in no-tillage area with duck was 3.373 g m^-2 lesser than that of no-tillage area without duck, and 5.59 g m^-2 less than that of conventional-tillage without duck area. The economic significance was analyzed. Farmers adopting the rice-duck ecological system obtained 2 166 and 4 207 RMB yuan ha^-1 more income than those who adopted a no-tillage without duck technique or conventional-tillage without duck technique, respectively. In addition to the reduction of the environmental pollution by methane emission, the farmers who adopted the rice-duck ecological system achieved economic benefits of 5 000 RMB yuan ha^-1, which was 2 206 and 4 274 RMB yuan ha^-1 more than those who adopted a no-tillage without duck technique and a conventional-tillage without duck technique, respectively. The rice-duck ecological system not only increased the economic benefits for farmers, but also reduced methane emission in rice paddy field. A sustainable agricultural production mode was formed.

Methane and Nitrous Oxide Emissions from Rice-Duck and Rice-Fish Complex Ecosystems and the Evaluation of Their Economic Significance

Rice-duck （RD） and rice-fish （RF） ecological systems are major complex planting and breeding models of rice paddy fields in southern China. Studying the methane （CH4） and nitrous oxide （N2O） emissions and their economic value from these two ecosystems can provide theoretical and practical basis for further development and utilization of these classical agricultural techniques. CH4 and N2O emissions from RD and RF ecological systems were measured in situ by using static chambers technique. Using global warming potentials （GWPs）, we assessed the greenhouse effect of CH4 and N2O and their economic value. Results showed that the peaks of CH4 emission fluxes from RD and RF appeared at full tillering stage and at heading stage, and the average emission fluxes were significantly （P〈 0.05） lower than that from CK. N2O fluxes remained low when the field is flooded and high after draining the water. Compared with CK, the total amount of N2O emissions was significantly （P〈0.05） higher and slightly lower than those from RD and RF, respectively. In 2006 and 2007, the total greenhouse effect of CH4 and N20 from RD and RF were 4 728.3 and 4 611 kg CO2 ha^-1, 4 545 and 4 754.3 kg CO2 ha^-1, respectively. The costs of greenhouse effect were 970.89 and 946.81 RMB yuan ha^-1, and 933.25 and 976.23 RMB yuan ha^-1, respectively, which were significant lower than those from CK （5 997.6 and 5 391.5 RMB yuan ha^-1）. Except for the environment cost of CH4 and N2O, the economic benefits from RD and RF were 2 210.64 and 4 881.92 RMB yuan ha^-1; 3 798.37 and 5 310.64 RMB yuan ha^-1, respectively, higher than those from CK. Therefore, RD and RF complex ecological planting and breeding models can effectively decrease and control CH4 and N2O emissions, and they are two of the effective strategies to reduce greenhouse gases from rice paddy fields and contribute in alleviating global warming. Thus, their adoption is important to the environment together with their economy benefits.

Dynamic Emission of CH₄from a Rice-Duck Farming Ecosystem

Global climatic change induced by emissions of greenhouse gases from human activities is an issue of increasing in-ternational environmental concerns, and agricultural practices and managements are the important contributors for such emissions. This study investigated dynamic emission of methane (CH4) from a paddy field in a rice-duck farming ecosystem. Three different cultivation treatments, namely the organic fertilizer + duck (OF+D), chemical fertilizer + duck (CF + D), and chemical fertilizer (Control) treatments, were employed in this study. Experimental data showed that hourly variations of CH4 emission from the paddy field during the day were somewhat positively correlated (R2 = 0.7 for the OF + D treatment and R2 = 0.6 for the CF+D treatment) to the hourly changes in air temperatures in addi-tion to the influences of the duck activities. The rate of CH4 emission for the CF+D treatment was higher than that of the Control treatment at the tillering stage, whereas the opposite was true at the heading stage. In contrary, the rate of CH4 emission for the OF + D treatment was always higher than that of the Control treatment regardless the tillering or heading stage. Our study revealed that the rate of CH4 emission depended not only on air temperature but also on the rice growth stage. A 6.7% increase in CH4 emission and in global warming potential (GWP) was observed for the CF + D treatment as compared to the Control treatment. This study suggested that although the impacts of duckling on the emission of CH4 depended on the rice growth stage and air temperature regime, the introduction of ducks into the rice farming system in general mitigated the overall CH4 emission and thereby the GWP.

Enhanced methane production in an anaerobic digestion and microbial electrolysis cell coupled system with co-cultivation of Geobacter and Methanosarcina

The anaerobic digestion（AD）and microbial electrolysis cell（MEC）coupled system has been proved to be a promising process for biomethane production.In this paper,it was found that by co-cultivating Geobacter with Methanosarcina in an AD–MEC coupled system,methane yield was further increased by 24.1%,achieving to 360.2 m L/g-COD,which was comparable to the theoretical methane yield of an anaerobic digester.With the presence of Geobacter,the maximum chemical oxygen demand（COD）removal rate（216.8 mg COD/（L·hr））and current density（304.3 A/m3）were both increased by 1.3 and 1.8 fold compared to the previous study without Geobacter,resulting in overall energy efficiency reaching up to 74.6%.Community analysis demonstrated that Geobacter and Methanosarcina could coexist together in the biofilm,and the electrochemical activities of both were confirmed by cyclic voltammetry.Our study observed that the carbon dioxide content in total gas generated from the AD reactor with Geobacter was only half of that generated from the same reactor without Geobacter,suggesting that Methanosarcina may obtain the electron transferred from Geobacter for the reduction of carbon dioxide to methane.Taken together,Geobacter not only can improve the performance of the MEC system,but also can enhance methane production.

Potential one-step strategy for PET degradation and PHB biosynthesis through co-cultivation of two engineered microorganisms

The management and recycling of plastic waste is a challenging global issue.Polyethylene terephthalate(PET),one of the most widely used synthetic plastics,can be hydrolyzed by a series of enzymes.However,upcycling the resulting monomers is also a problem.In this study,we designed a co-cultivation system,in which PET degradation was coupled with polyhydroxybutyrate(PHB)production.First,PETase from Ideonalla sakaiensis was expressed in Yarrowia lipolytica Po1f with a signal peptide from lipase.The engineered PETase-producing Y.lipolytica was confirmed to hydrolyze bis(2-hydroxyethyl)terephthalate(BHET)and PET powder into the monomers terephthalate(TPA)and ethylene glycol(EG).Simultaneously,a TPA-degrading Pseudomonas stutzeri strain isolated from PET waste was transformed with a recombinant plasmid containing the phb CAB operon from Ralstonia eutropha,which encodes enzymes for the biosynthesis of PHB.The two co-cultivated engineered microbes could directly hydrolyze BHET to produce the bioplastic PHB in one fermentation step.During this process,5.16 g/L BHET was hydrolyzed in 12 h,and 3.66 wt%PHB(3.54 g/L cell dry weight)accumulated in 54 h.A total of 0.31g/L TPA was produced from the hydrolyzation of PET in 228 h.Although PHB could not be synthesized directly from PET because of the low hydrolyzing efficiency of PETase,this study provides a new strategy for the biodegradation and upcycling of PET waste by artificial microflora.

School-Enterprise Cooperation in Excellent Engineer Education and Training Program at UESTC

School of Information and Software Engineering at University of Electronic Science and Technology of China(abbreviated hereafter as "SISE") joined Excellent Engineer Education and Training Program launched by Ministry of Education of China in 2011. This paper discussed nine models of school-enterprise cooperation practiced at SISE since 2011. The school-enterprise cooperation model effectively broadens the students' horizons and improves the students' practical ability and has been recognized by academic circles.

Study on Diversity of Arthropod Community in a Rice-duck Integrated Farming System in South China

The integration of ducks into rice farming has raised concerns about possible effects on arthropod communities due to frequent predation by ducks. This paper conducted a study using three treatments, including integrated rice-duck cultivation （RD）, conventional rice cultivation （CC） and a control treatment （CK）, to investigate the impact of rice-duck farming on the diversity of arthropod communities in the field. The results revealed that arthropod numbers in both RD and CC treatments showed varying degrees of reduction when compared with the CK treatment. Arthropod individual numbers, Simpson （D） and Shannon＇s diversity index （H＇） values in RD were higher than those in CC. Arthropod individual numbers, richness index （R）, D and H＇ values in both tillering and booting phases of the late rice were significantly higher in RD treatment than those in CC treatment. Rice-duck integration system was favorable for the maintenance of arthropod diversity in the cropping field and may help to lessen the decline in abundance and diversity of rice farmland arthropods caused by the utilization of chemical pesticides and fertilizers.

Effect of zinc substitution in hydroxyapatite coating on osteoblast and osteoclast differentiation under osteoblast/osteoclast co-culture

Zinc is an essential trace element required for bone remodelling process,but its role in such process remains to be elucidated.In particular,inconsistent results have been reported on the effect of Zn on osteoclastic responses,and supplement of receptor activator of nuclear factor kappa-B ligand(RANKL)factors has been commonly adopted.Co-culture is a suitable approach to elucidating the role of Zn in bone remodelling process,by better imitating the cellular environment as the presence of osteoblasts plays critical role in modulating osteoclastic functions.In this study,zincsubstituted HA coatings have been deposited using a liquid precursor plasma spraying process at two different concentrations(1,2 wt.%).The effect of zinc substitution on osteoblastic and osteoclastic differentiation has been studied in vitro.In particular,a cultivation regime was designed to first induce osteoblastic differentiation of rat bone marrow stromal cells(BMSCs)for 14 days,and then induce osteoclastic differentiation of osteoclast-like precursor RAW 264.7 cells through the aid of the osteoblasts formed for additional 14 days,in the absence of the external addition of RANKL.The results showed that Zn substitution moderately promoted the BMSC differentiation into the osteoblasts and reduced the osteoclastic activity in early time(1 day co-culture).However,promotion of the osteoclastic activity were observed at later stages,as indicated by the significantly enhanced expressions of trap5b and IL-1(8-and 15-day co-culture)and moderate stimulation of the nucleus integration and formation of the multinucleated cells(14-day co-culture).Such stimulating effect of the osteoclastic activity was absent under mono-culture of RAW 264.7 cell,with simple RANKL supplementation.The results suggest that both the zinc and the presence of MSC/osteoblast play profound and highly interacted roles on osteoclast differentiation and activity,which is critical in modulating the bone remodelling process.

Viability of combining microalgae and macroalgae cultures for treating anaerobically digested piggery effluent

Algal phytoremediation represents a practical green solution for treating anaerobically digested piggery effluent(ADPE). The potential and viability of combining microalgae and macroalgae cultivation for the efficient treatment of ADPE were evaluated in this study.Bioprospecting the ability of different locally isolated macroalgae species illustrated the potential of Cladophora sp. to successfully grow and treat ADPE with up to 150 mg/L NH_4^+ with a biomass productivity of(0.13 ± 0.02) g/(L·day) and ammonium removal rate of(10.23 ± 0.18) mg/(L·day) NH_4^+. When grown by itself, the microalgae consortium used in this study consisting of Chlorella sp. and Scenedesmus sp. was found to grow and treat undiluted ADPE(up to 525 mg/L NH_4^+) with an average ammonium removal rate of 25 mg/(L·day) NH_4^+ and biomass productivity of(0.012 ± 0.0001) g/(L·day). Nevertheless, when combined together, despite the different cultivation systems(attached and non-attached) evaluated,microalgae and macroalgae were unable to co-exist together and treat ADPE as their respective growth were inversely related to each other due to direct competition for nutrients and available resources as well as the negative physical interaction between both algal groups.