Abstract:The technique of SSR markers was used to study the genetic diversity of the sweet corn inbred lines，56 pairs of primers selected from 150 pairs of primers. A total of 155 polymorphic bands，an aver-age of 2. 77 alleles per primer，variation of 2-5 alleles for each primer , mean polymorphic information content of 0. 42 and its range from 0. 13 to 0. 71 were detected. Clustering analysis in UPGMA classified the sweet corn inbred lines into 3 groups，which were similar to germplasmic genealogy.

Abstract:The rice parents with lower grain mass per panicle and 1000-grain mass CB1, CB7 and the higher parent CB4 were chosen to construct the combines CB1×CB4 and CB7×CB4; also the corresponding P₁，F₁，P₂，B₁，B₂，F₂populations were established and planted as middle and late two planting seasons and the mass per panicle and 1000-grain mass traits were checked, respectively. The Akaike’s information criterion (AIC) of the major genes plus polygenes mixed inheritance model was used to identify the existence of major genes affecting quantitative traits in B₁，B₂，F₂populations, and when the major genes existed, the genetic effects of the major genes and polygenes and their genetic variance were estimated through segregation analysis. The results showed: One major genes plus polygenes was the most fitted genetic model for grain mass per panicle in the all B₁，B₂，F₂ populations. The heritability values of the major genes varied from 58.06% to 75.60% and those of polygenes varied from 5.03% to 25.46%, and the total heritability values were from 68.07% to 96.68%. The heritability values of the same genetic population under the different planting seasons showed little difference, while those of population of combination of CB7/CB4 were higher than those of population of combination CB1/CB4 of the same planting season. The findings suggested that parents selection constructing the genetic population should be considered when analyzing the heredity of the grain mass per panicle trait. One additive major gene plus additive-dominance polygenes was the most fitted genetic model for 1000-grain mass in the all B₁，B₂，F₂ populations. The heritability values of the major genes of population of combination CB1/CB4 as middle season planting were the highest in the two genetic populations of the two planting seasons and varied from 60.06% to 69.38%. While the polygenes heritability values of population of combination CB1/CB4 as middle season planting were the lowest and varied from 10.70% to 23.21%. The total genes heritability values of population of combination CB1/CB4 as middle season planting was varied from 71.48% to 83.55%. The first order parameter d value of population of combination CB1/CB4 as middle season planting was the lowest in the two genetic populations of the two planting seasons, which suggested that parents selection constructing the genetic population should be considered when analyzing genetic of the grain mass trait.

Abstract:An effective method for the isolation of plasma membrane (PM) from rice,Oryza sativa,seedlings was established using aqueous two-phase system which was composed of Dextran T 500 and PEG 3350. The effect of the concentration of the polymer on partition of PM in polymer system was studied．Phase separation was carried out in a series of two-phase systems containing 6.1%-6.5% (w) of each polymer dissolved in phase buffer. The result indicated that the most effective phase partition system which consisted of 6.3%/6.3%(w) PEG 3350/Dextran T 500 in 0.25 mol/L sucrose, 5 mmol/L potassium phosphate and 3 mmol/L KCl (pH 7.8) was suitable for the isolation of PM from rice. The electron micrograph stained with uranyl actate-lead citrate stain and marker enzyme activities analysis proved that the isolated PM had obtained high purity (93.5%) and right-side out sealed vesicles. Purified PM proteins were also obtained from crude PM in good yield (2.73%). To improve the solubilization of hydrophobic PM proteins and dissociate protein complexes, PM proteins were treated by an optimized rehydration buffer including new zwitteronic detergents, just as ASB-14 and CHAPS. 1-D SDS-PAGE of purified PM proteins showed more band numbers and well-proportioned bands intensity than that of crude PM. PM proteins were also separated by IEF/SDS-PAGE. 579±17 well-resolved proteins with a much clearer background were obtained, which also showed good reproducibility among three independent experiments. The result above showed that the method to purify PM proteins using the aqueous two-phase partition system could be suitable for high-throughput PM proteomic analysis, such as SDS-PAGE combined with HPLC-ESI-MS/MS and 2-DE analysis.

Abstract:The variation and inter-relations between the three kinds of antioxidant capacity (total oxidation resistance, the capacity to inhibit superoxide anion and hydroxyl radical), relavant enzymes ［peroxidase（POD）, superoxide dismutase （SOD）and catalase （CAT）］, and the oxidation products ［malonaldehyde （MDA）and （H₂O₂）］ during the postharvest senescence of longan (cv. Shixia) aril stored at 4 ℃ and 20 ℃were studied. The results showed that the longan aril suffered a process of irreversible senescence during the storage at high and low temperatures, and the senescence progress at high temperature far shorter than that at low temperature. The variation and effect levels in the peroxide products, three kinds of antioxidant capacity and relevant enzymes varied with the different storage temperatures. Furthermore, longan aril was more subject to the damage from free oxygen radicals at high storage temperature than low temperature, and POD, SOD and CAT were more positive to be induced by free oxygen radicals. The correlation analysis showed that there were no significant differences between the three oxidation resistance. POD and CAT played a more important role than SOD in anti-oxidation during the senescence of longan aril at 4 ℃, while SOD and POD were closely related to the capacity to inhibit superoxide anion, MDA and H₂O₂ contents and played a more important role than CAT.

Abstract:In this study, electronic nose technology combined with quality and physiological indexes was used to evaluate three levels of maturity of ‘Jinxiuhuangtao’ peach. The results showed that color turning peaches could be distinguished from mature and ripe peaches using the score plot of principal component analysis (PCA) by the electronic nose measurement. However, mature and ripe peaches were not well distinguished from each other because of existence of overlapping. The predicted results were compared with the results of the traditional chemical and physical test methods (firmness, total soluble solids, titration acid volatile and aromatic constituents) and physiological indexes (ethylene release rate). The comparisons showed that PCA analysis was more accurate than discriminant factor analysis (DFA). Electronic nose technology could provide a basic tool for distinguishing different levels of maturity of peaches.

Abstract:In order to investigate the effects of the C/N ratio and bacterial reagent addition on dynamic changes of organics degradation and biological indicators during the organic garden waste composting, a compost test with different disposing measures was conducted. The results showed that the adjustment of C/N ratio and the bacterial reagents addition benefited the compost temperature rising and acceleration of maturity, reduced the compost toxicity, promoted the degradation of volatile solids, accelerated the decomposition of organic carbon, the total and free humic acid，increased the HA/ FA ratio, and improved the compost quality. The results indicated that the adjustment of C/N ratio combined with the bacterial reagents addition was more effective to the maturity and quality improvement of compost than the only regulating C/N ratio.

Abstract:The virus isolate Okra06 was obtained from the diseased okra plants exhibiting yellow vein and leaf curl symptoms in Guangzhou, Guangdong Province. The results of PCR detection indicated that the virus belonged to the genus Begomovirus of the family Geminiviridae. The genome of the virus was cloned and sequenced. The results showed that it had only A component（DNA-A）. The complete nucleotide sequence of DNA-A was determined to be 2 737 nucleotides, encoding six potential ORFs. The comparison showed that Okra06 DNA-A had the highest nucleotide sequence identity (99.7%) with CLCuMV-［G6］. Six ORFs shared 100%, 100%, 99.6%, 99.8%, 100% and 99.7% nucleotide sequence identities with CLCuMV–［G6］, respectively. The Okra06 was also associated with satellite DNA β molecular. The full-length sequence of DNA β was determined to be 1 346 nucleotides, encoding one potential ORF (C1). The comparison further showed that Okra06 DNA β had the highest nucleotide sequence identity(99.5%)with G6 DNA β. Phylogenetic analysis revealed that DNA β of isolate Okra06, G6 and Gx08 were more closely related than the other begomoviruses associated with DNA β, and were clustered in a separate branch and further clustered with other isolates of CLCuMV DNA β or CLCuV DNA β. Those results revealed that the virus isolate Okra06 infecting okra plants in Guangdong belonged to the species CLCuMV, and it should be the Hibiscus strain.

Abstract:To investigate the resistant effect of silicon on leaves of two rice varieties with nanometer SiO₂ inoculation treatment against Magnaporthe grisea, resistant variety Nongda 18 to M. grisea and susceptible variety Mongolian rice to the pathogenic fungus were observed with SEM and TEM compared with control groups without the SiO₂ treatment. The findings showed there were only a few hyphae of M. grisea on both leaves, and less hypha quantities than control group without Si treatment. Based on TEM pictures, it was clearly observed that Si might prevent the hypha from penetration by enclosing hypha around sites penetrated. Consequently, the result indicated that nanometer SiO₂ was able to protect rice from the pathogentic fungus.

Abstract:To investigate the effects of mosquitofish, Gambusia affinis on aquatic insect biodiversity in South China, three common species of aquatic insects in mosquitofish habitat, i.e., Cloeon bengalense, Chironomus kiiensis and Aedes albopictus, were selected under the lab condition to test the feeding preference of mosquitofish. The resulted showed that mosquitofish had no significant feeding selection on all preys in low density under the single-predator-and-multiple-preys experimental design. But mosquitofish preferred the larvae and pupa of A. albopictus to other preys with the increase of prey density. When the prey ratio was 1∶1 under the single-predator-and-two-prey experimental design, mosquitofish frequently prefer larvae of A. albopictus to the other prey. However, there was no significant influence to total prey consumption for mosquitofish when prey ratio was changed but total prey numbers unchanged. The results suggested that G. affinis preferred to feed on the mobile prey close to water surface and showed no interest in the unmoving or dead prey, and mosquito larvae were the favorite prey of mosquitofish compared with mayflies and chironomids.

Abstract:Somatic embryogenesis of Fraxinus mandshurica was conducted by using young zygotic cotyledons as explants. The polysaccharide content, soluble protein content, SOD activity, POD activity, CAT activity and PPO activity were tested for analyzing the relationships between the physiological and biochemical index and the status of somatic embryogenesis, callus induction, explants browning and growth of explants. The results showed that there was interesting correlations between the polysaccharide content, soluble protein content, SOD activity, POD activity, CAT activity and PPO activity and the regeneration of callus and somatic embryos,and explant browning and growth, and it is worth being studied further.

Abstract:The standard plot method was used to study the distribution and biological cycling of 10 nutrient elements（N，P，K，Ca，Mg，Fe，Mn，Zn，Cu and B） in the 7-year-old（middle-age）Acacia crassicarpa plantation．The results indicated that concentrations of the 10 nutrient elements in different organs of A．crassicarpa plantation were in the order of leaves>bark>branch>root>stem. The contents of N were the highest，K and Ca the second，Mg and P the lowest for macro-elements，whereas Mn and Fe were the highest，B and Zn the second，and Cu the lowest for micro-elements．The nutrient storage of the plantation was 1 121.08 kg·hm^-2，of which overstorey of A. crassicarpa trees stored 848.94 kg·hm^-2 accounting for 75.72%，forest floor 116.05 kg·hm^-2 account for 10.35%，and standing litter 156.08 kg·hm^-2 account for 13.92%．The amounts of nutrient elements in different parts of trees was in the order of stem＞leaves＞branch＞bark＞root．The amounts of annual uptake，retention and return of 10 elements in the plantation were 261.87，140.59 and 121.28 kg·hm^-2，respectively．The cycling coefficient and recycling period were 0.54 and 6.04. As was observed，the nutrient utilization efficiency in middle-aged A. crassicarpa plantation was lower，but the return rate was higher and the turnover period was shorter，resulting in the recovery and maintenance of forestland fertilization.

Abstract:According to field collections and specimen identification, there are 8 genera, 41 species and 3 varieties of Lauraceae in Shenzhen, 3 of which are newly recorded, i.e., Beilschmiedia brevipaniculata, Machilus gamblei and M. robusta. Machilus has the most abundant species in Shenzhen, followed by Cinnamomum and Litsea. The dominant generic geographical elements of Lauraceae are the pan-tropical, tropical Asia and tropical America disjuncted elements. The species are dominated by the tropical Asian element and the endemic element to China, accounting for 45.45% of the total species respectively. The comparison of the geographical patterns of Lauraceae between Shenzhen and the surrounding areas showed that Shenzhen has the highest generic similarity coefficient with Hong Kong and the lowest with Jianfengling (Hainan).

Abstract:Fifty nine isolates of nitrogen-fixing bacteria and phosphate-solubilizing bacteria were isolated based on the characteristics of morphology and growth of the bacteria on the selective growth media from the rhizosphere of mangrove plants including Bruguiera gymnorhiza, B. sexangula, Kandelia candel, Rhizophora stylosa, Sonneratia apetala and S. caseolaris in Zhanjiang and Zhuhai, Guangdong Province and Dongzhai harbor, Hainan Island. Among them 7 isolates of nitrogen-fixing bacteria and 8 isolates of phosphate-solubilizing bacteria were screened as propagule inoculants of K. candel in a series of potted experiments to examine their capability to promote the growth of plants. The results showed that the inoculation with a single isolate of phosphate-solubilizing bacteria He4# resulted in a significant increase in plant height, root mass and total biomass at the rate of 58.4%, 132.1% and 133.2%, respectively. The enhancement of isolate He4# on the plant growth is more significant than that of an alien isolate (Bacillus lichenciformis). The root biomass and total biomass of K. candel inoculated He4# increased by 72.7% and 90.2% than those inoculated B. lichenciformis. All pure inoculations with 7 different isolates of nitrogen-fixing bacteria showed positive response to the plant growth, and the inoculation with isolate Ngqq-R14 resulted in the maximum increase in plant height, stem diameter, stem dry mass, root dry mass and total biomass at the rate of 38.36%, 16.19%, 75.46%, 51.55% and 59.31%, respectively. Dual inoculations with 7 mixtures of one isolate of nitrogen-fixing bacteria and one isolate of phosphate-solubilizing bacteria could result in synergistic effect on the growth of the seedlings of K. candel, and the increase of plant height, stem dry mass, root dry mass and total biomass were 21.1%-69.4%, 70.7%-271.3%, 27.1%-111.3% and 66.9%-123.8% respectively. It can be concluded that using mixed cultures of microorganisms is advantageous over pure cultures, and the inoculation of mangroves with phosphate-solubilizing bacteria and nitrogen-fixing bacteria will promote the growth of mangrove plants.

Abstract:A trial containing 15 Hevea clones was comparatively analyzed and preliminarily evaluated in Rubber Research Institute of Chinese Academy of Tropical Agriculture Sciences (RRIC-CATAS). The 15 test materials were composed of both introduced and selectively bred by RRIC. The commercial clone RRIM 600 was set as control. The results showed that dry rubber content and dry rubber yield per tapping of the 15 clones in different months varied from significantly to extremely significantly. Per tapping and per month production of dry rubber of the 15 clones differed greatly. Growth, latex yield and dry rubber content of most of these clones were not significantly different. Correlation between growth and rubber yield was not significant. Four clones i.e., TSF8, TSF7, TSF10 and CATAS2-73 exhibited good latex-timber combined character.

Abstract:Variations of modulus of elasticity (MOE) of 18-year-old Eucalyptus cloeziana wood in 11 provenances were investigated according to different provenances, individuals and stem heights. MOE was measured by SANS-type computer-controlled electronic universal testing machine. The samples from felled trees were done by the national standard. The results showed that there were significant differences among provenances, individuals and stem heights in E.cloeziana wood. Provenance B47 had the largest MOE, at 26.71 GPa. Provenance 12195 had the smallest of all, at 23.50 GPa, which was significantly smaller than that of provenance B47, D47 and 17008. 7 out of 11 provenances were significantly different in individual. 2 different provenances had significant differences in MOE between stem heights. 2 kinds of tendencies on MOE along stem heights were evident: 7 provenances showed an increase as the stem height increased; the other 4 provenances increased first then decreased.

Abstract:The method of pectin extraction from sisal residue was optimized by orthogonal experiments, and pectin separation and decoloration were also studied. The optimized extraction conditions were as follows: 2.2 mol·L^-1 oxalic acid-ammonium oxalate buffer as extracting agent, the solid to liquid ratio 0.1 g·mL^-1, time 90 min, temperature 80℃. Pectin was precipitated by alcohol at pH 4.0； the yield of sisal pectin was 14.87%. The primrose yellow pectin was decolored by 1.8%-2.4% H₂O₂. The results of physicochemical property were that the degree of esterification of sisal pectin was 23%, galacturonic acid 66%, pH and ash all complying with Chinese light industey standards.

Abstract:The purpose of this paper was to study the effects of temperature, pH and inoculation level on the growth parameters of Aeromonas spp. in chilled pork under laboratory conditions. The curves generated within different conditions were fitted by Gompertz function as primary model. Then two parameters (growth rate and lag-time) of the growth curves were modeled using a quadratic polynomial equation of response surface model (RSM) as secondary model. Additional experimental conditions within the research domain were randomly selected for model validation, and mathematical testing were also applied for the developed models, including the mean square error (MSE), accuracy factor (AF) and bias factor (BF).The results indicated that modified Gompertz function could be used to model Aeromonas spp. growth under different experimental condtions (R²>0.96). Moreover, the temperature, pH and inoculation level on the growth of Aeromonas spp. were significant （P<0.05）, and RSM with lower MSE and acceptable AF and BF values provided a useful and accurate method of predicting the growth parameters of Aeromonas spp.

Abstract:Testicular cells of 5-7 days postpartum Kunming mouse were collected by two-step enzymatic digestion method. Effects of two different purification methods known as different adherence selection and percoll discontinuous density gradients were compared, whereas the effects of different growth factors on spermatogonial stem cells (SSCs) proliferation were investigated as well by MTT assay. The results showed that there was significant difference in the numbers of total testes cells acquired between 5 days postpartum pups and 7 days postpartum pups(P＜0.05), yet the numbers of SSCs had no significant difference between the two groups(P＞0.05).The purification method of different adherence selections attained higher SSCs numbers and purification ratio than Percoll method, with the ratio of 85.06%.By means of MTT assay, the results showed that LIF factor could promote SSCs proliferation, and the 20 ng/mL GDNF+20 ng/mL bFGF+10³ U/mL LIF was the best supplementation combination in Kunming mouse SSCs in vitro.

Abstract:The flaA gene was amplified from genome template of Aeromonas veronii CY0806 of Cyprinus carpio by PCR. Homogeneous analysis was carried out by comparing the sequencing results with other strains of Aeromonas and bioinformatic analysis was done on the protein coded by flaA. The results showed that flaA Gene with a length of 915 bp, coding 304 amino acids, was obtained; phylogenetic tree analysis results showed that it was on the same branch with other strains of Aeromonas. Bioinformatic analysis results showed that the relative molecular mass of the protein was 32 098.66, pI 5.57, half-life 30 h, unstability index 32.31, fat index 81.05 whereas there was no signal sequence and transmembrane domain. Results of secondary structural analysis showed that the main secondary structures were α-helix and β-sheet. At the same time the tertiary structure was also predicted by homology modeling.

Abstract:Biological diversity, structural characteristics and habitat density of the benthos in the intertidal zone near Lianyungang Tianwan Nuclear Power Plant were studied, according to the seasonal ecological surveys conducted in 2008. In ecological aspects, the benthic biomass and the density of Bsection (fish culture zones: 42.32 g·m^-2 and 71.83 ind·m^-2) were higher than those of A Division (natural habitat Beach: 11.24 g·m^-2 and 63.67 ind·m^-2). Community similarity data had shown that marine engineering may make benthos communities reduce the degree of differentiation of the area between the various habitats. The diversity index for the 4 seasons is 1.72, 1.20, 1.68 and 0.84, respectively. The seasonal changes in community diversity displayed in the most polluted winter probably had a relationship with the disturbance of marine engineering activities, which was likely to lead to the changes in the structure of ecological communities, or even the destruction of habitat and loss of biological diversity. Overall, the community structure was not very stable in the intertidal benthic animals near the Tianwan nuclear power plant. It cannot be immediately concluded that nuclear power plant engineering activities were related to the extent of the impact. We need to continue to investigate the biological resources of the area to monitor the situation, forming a long-term and effective monitoring mechanism.

Abstract:Using bioinformatics analysis, a rich antigenic determinant area in HEP-Flury nucleoprotein sequence was selected, and the codons were modified to cater the codon usage bias in Escherichia coli, and the restriction enzyme sequences were inserted in upstream and downstream. The modified gene was synthesized and cloned into prokaryotic expression vector pET-32a(+). The recombinant plasimd was designated pET-32-NP. pET-32-NP was175 transformed to E.coli BL21(DE3)pLysS, and the recombinant protein was expressed after IPTG induction. SDS-PAGE analysis showed that the expressed protein had a relative molecular mass of 34 000. Western-blotting results also revealed that the expressed protein could be recognized specifically by mouse anti-His monoclonal antibody and mouse anti-RV polyclonal antibody.

Abstract:Based on the genome sequence of newcastle disease virus(NDV) published in GenBank，nine pairs of gene-specific primers were designed to amplify cDNA of FJ-SMD-03 strain isolated from Semi-Muscovy duck in Fuzhou, Fujian ,then sequecing and analysis were performed. The results showed that FJ-SMD-03 was 15 192 nucleotides in length which consisted of six ORFs in the order of 3′leader-NP-P-M-F-HN-L-5′trailer and it had six nucleotides longer than Lasota strain in non-coding region of NP gene. The genome shared the highest similarity of the nucleotide with 1.3,carrier-pigeon/Guangdong/2008,pigeon/Italy/1166/00,AV324/96 and dove/Italy/2736/00 (94.9%-98.5%),and shared the lowest similarity of the nucleotide with vaccine strain Lasota,Mukteswar and B1(80.7%-83.3%), whereas it shared lower similarity of the nucleotide with strain F₄₈E₈ and Muscovy duck/China(Fujian)/FP1/02,Subgenotype VIId, velogenic, isolated from Muscovy duck in Fujian during 2002 for 82.5% and 87.1% respectively. The motif of cleavage site region of F gene was ¹¹²R-R-Q-K-R-F¹¹⁷, which was the sequence signature of virulent strain. Phylogenetic analysis revealed that FJ-SMD-03 belonged to subgenotype VIb, Class Ⅱ, which was the first report of the subgenotype VIb virulent NDV strain isolated from Semi-Muscovy duck. FJ-SMD-03 was closely associated with 1.3,carrier-pigeon/Guangdong/2008 and pigeon/Italy/1166/00 and formed a secondary branch in the phylogenetic tree with carrier-pigeon/Guangdong/2008, which suggested that FJ-SMD-03, carrier-pigeon/Guangdong/2008 and pigeon/Italy/1166/00 came from the same origin, which might be due to virus carried by pigeons.

Abstract:Two hundred and eighteen Escherichia coli isolates were collected and identified from edible fish in this study. Susceptibilities of 218 isolates to 17 antimicrobials were performed by agar dilution method. Prevalence of ESBLs and PMQR encoding genes was detected by PCR. Broth mating was applied to explore the transfer of ESBLs and/or PMQR determinants from 10 ESBLs and/or PMQR positive isolates to E. coli C600. Susceptibility results showed that resistance occurance of 218 E. coli to 17 antimicrobials ranged from 0.5% to 72.5%. Two ESBLs encoding genes were detected in 112 ampicillin-resistant isolates, including bla_CTX-M-79 and bla_CTX-M-14. Beta-lactamase genes, bla_LEN-4 and bla_LEN-17 were also detected in 2 isolates. Fifty-nine of 80 ciprofloxacinresistant isolates harboured PMQR determinants, of which 33 were qnrB, 5 qnrD, 21 qnrS, and 6 aac(6′)-Ib-cr. No isolates were detected to carry qnrA, qnrC and qepA. The results of conjugation experiments showed that ESBLs and/or PMQR determinants may be transferred on a same plasmid to E. coli C600.

Abstract:The study was conducted to explore LD₅₀ and pathological changes in mice caused by enterohemorrhagic Escherichia coli O157∶H7.Methods weaned mice were inoculated via enterocoelia inoculation with different doses of E.coli O157∶H7 021210 strain and simultaneously treated with nalidixic acid to determine LD₅₀.Many pathological changes were seen in mice caused by E.coli O157∶H7.

Abstract:Collected from Chaozhou Dazhishan, two species were reported as new records to Guangdong Province, China, i. e., Polygonum persicaria L. var. opacum (Sam.) A. J. Li and Isachne sylvestris Ridley. All the voucher specimens are deposited in the Dendrological Herbarium of Forestry College, South China Agricultural University (CANT).