Frontiers of Agriculture in China

ISSN 1673-7334

ISSN 1673-744X(Online)

CN 11-5729/S

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Genetic bases of improved soybean cultivars released from 1923 to 2005 in China—A historical review
Dongjin XIONG, Tuanjie ZHAO, Junyi GAI
Front Agric Chin. 2010, 4 (4): 383-393.

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Improved soybean cultivars are cultivars released from a scientific breeding program in China in contrast to the historical landraces kept by farmers from their own seed lots. The pedigree data of 1300 soybean cultivars [Glycine max (L.) Merr.] released in China from 1923 to 2005 were collected, checked, and corrected. These cultivars traced back to 670 nuclear and 344 cytoplasmic ancestors; 45% (50%) of the nuclear (cytoplasmic) germplasms were from Eco-region I, 23% (26%) from II, 7% (10%) from III, 4% (5%) from IV, 1% (1%) from V, 1% (1%) from VI, 18% (7%) from foreign countries, and 0% (1%) from geographically unknown sources. Both nuclear and cytoplasmic germplasm from Eco-regions I, II, and III, and foreign countries accounted for most of the ancestry of the released cultivars. In each of the eco-regions, with the exception of region VI, but especially in region I, the local nuclear and cytoplasmic germplasm was dominant in the released cultivars. Exotic germplasm accounted for an increasing portion of the nuclear and cytoplasmic germplasm, especially in Eco-regions I and II. The genetic base of the released cultivars is relatively narrow but has been gradually broadened, especially in Eco-regions I and II; and the average number of ancestors per cultivar released between 1996 and 2005 in various eco-regions was approximately double the period between 1986 and 1995. Seventy-eight ancestors accounted for 12% of the total ancestors but explained that 64% of the nuclear contribution and 70% of the cytoplasmic contribution to the 1300 released cultivars. For broadening the genetic base of future cultivars, the utilization of germplasm from outside regions is emphasized.

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Identification of disease resistances in wheat-Leymus multicaulis derivatives and characterization of L. multicaulis chromatin using microsatellite DNA markers
Xiuli ZHANG, Jinjin CAI, Joseph M. ANDERSON, Maolin ZHAO, Herbert W. OHM, Lingrang KONG
Front Agric Chin. 2010, 4 (4): 394-405.

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To identify resistance to Fusarium head blight (FHB), cereal yellow dwarf virus (CYDV), stem rust (Sr), and powdery mildew (Pm) in 24 common wheat (Triticum aestivum)-Leymus multicaulis addition/translocation lines that were developed cytogenetically and to verify the authenticity of these lines using microsatellite (SSR) DNA markers. Resistance to FHB was identified in the wheat-L. multicaulis addition lines, Line 9 and Line 26, which both contained L. multicaulis-specific fragments as shown by SSR markers. The translocation line, Trans 1, and the addition lines, Line 5 and Line 29, have resistance to stem rust (IT 0). Resistance to CYDV was evaluated based on virus titers measured by enzyme linked immunosorbent assay (ELISA). The addition line, Line 23, showed low virus titer (0.15), indicating resistance to CYDV. The segregation distribution of CYDV resistance in 98 F2 plants of Line 23/CS showed a significant deviation from 3∶1. Inoculation with a set of 14 differential Blumeria graminis f. sp. tritici (Bgt) isolates did not detect powdery mildew resistance in translocation line Trans 1, addition line Line 9 and the amphiploid of wheat-L. multicaulis. However, Line 26 exhibited the resistance response pattern of Kavkaz, which carries Pm8, indicating that Line 26 most likely has the powdery mildew resistance gene Pm8 inherited from its parent lines Feng Kang 7 or Feng Kang 10. Twelve SSR markers, distributed on different homeologous chromosome groups of wheat, which distinguished L. multicaulis addition/translocation chromosomes, were used to verify the presence of L. multicaulis chromatin in the putative wheat-L. multicaulis addition/translocation lines. Of the 24 addition/translocation lines investigated using the 12 polymorphic SSR markers, 18 wheat-L. multicaulis derivatives showed the expected L. multicaulis-specific fragments, indicating that all of these 18 addition/translocation lines would most likely have the introgressed L. multicaulis chromosome(s). Chromosomal rearrangements also were detected in some of the wheat-L. multicaulis introgression lines.

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Long-term effect of fertilizer application on rice yield, potassium uptake in plants, and potassium balance in double rice cropping system
Yulin LIAO, Shengxian ZHENG, Yanhong LU, Zengping YANG, Jun NIE, Jian XIE
Front Agric Chin. 2010, 4 (4): 406-415.

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A 27 years field experiment was conducted on a Fe-Accumli Stagnic Anthrosol to evaluate the effects of long-term application of fertilizer, pig manure (PM), and rice straw (RS) on rice yield, uptake, and usage efficiency of potassium, soil K pools, and the nonexchangeable K release under the double rice cropping system in South Central China. Common cropping pattern in the study was early rice-late rice-fallow (winter). The field treatments included CK (no fertilizer applied), NP, NK, NPK, and NK+ PM, NP+ RS, NPK+ RS. The pig manure and rice straw was applied in both the early rice and late rice cropping season. The ranking order of 27 years average annual grain yield were the CK<NK<NP<NK+ PM<NP+ RS<NPK<NPK+ RS treatments. The negative yield change trends were observed in the CK and NP and NK treatments of unbalanced nutrient application in the case of omitted-K and P-omitted. The positive yield change trends were observed in balanced applications of NPK and combined application of fertilizer (NPK) with pig manure (NK+ PM) or rice straw (NP+ RS and NPK+ RS). The application of K fertilizer (NPK) increased grain yield by 56.7 kg·hm-2·a-1 over that obtained with no K application (NP). The combined application of pig manure with fertilizer (NK+ PM) increased by 82.2 kg·hm-2 per year compared with fertilizer application alone (NK). The combined application of rice straw with fertilizer (NP+ RS and NPK+ RS) increased on the average of 34.4 kg·hm-2 per year compared with fertilizer application alone (NP and NPK). In all fertilizer, pig manure and rice straw combinations, K uptake change trends in rice plants of the early rice was positive except for CK and NP treatments. The results showed that the total removal of K by the rice plants exceeded the amounts of total K applied to the soil in all treatments, which showed a negative K balance. This ranged from 106.3 kg·hm-2·a-1 in CK treatment to 289.6 kg·hm-2·a-1 in the NPK+ RS treatment. Continuous annual application of 199.2 K kg·hm-2 to rice resulted in an accumulation (58 kg·hm-2) of exchangeable K (1 mol NH4OAc extractable K) in 0– 45 cm soil depth over the study period, despite the higher average annual uptake of K by the system (225.7 kg·hm-2). However, nonexchangeable K increased substantially from 1090 kg·hm-2 to 1113 kg·hm-2 and 1140 kg·hm-2 in the 0–45 cm soil layer in NPK+ RS and NPK treatments after 27 years of the continuous double rice cropping system, respectively. Thus, long-term rational application of K fertilizer may increase sustainable K fertility of the continuous double rice cropped system.

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Protein extraction from rice (Oryza sativa L.) root for two-dimensional electrophresis
Xiaoliang XIANG, Shuju NING, Xia JIANG, Xiaogui GONG, Renlei ZHU, Lanfang ZHU, Daozhi WEI
Front Agric Chin. 2010, 4 (4): 416-421.

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An efficient protein extraction method for two-dimensional gel electrophoresis (2-DE) from plant samples is usually challenging due to the low protein content and high level of interfering compounds. Proteomic analyses of rice (Oryza sativa L.) roots are limited by the lack of an efficient protein extraction method. To establish an effective protocol of protein extraction suitable for 2-DE analysis in rice roots, we evaluated three protein extraction methods (trichloroacetic acid [TCA]/acetone, Mg/NP-40/TCA, and tris-base/acetone). Our results showed that the Mg/NP-40/TCA extraction method had the highest protein yield and is the best resolution of protein separation among the three methods. The TCA/acetone method exhibited clear ?protein? profiles? and ?detected? more ?protein ?spots with the highest intensity in the region of high Mr (above 45 kDa) than the other methods. However, this method was unable to detect proteins with low-Mr (less than 24.0 kDa). The Tris-base/acetone method showed the poorest resolution of protein separation. Our results suggest that the Mg/NP-40/TCA method was the most effective among the three methods and may provide enhanced proteomic information for rice and other crop roots.

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Chemical fertilizer reduction and soil fertility maintenance in rice–fish coculture system
Jian XIE, Xue WU, Jianjun TANG, Jiaen ZHANG, Xin CHEN
Front Agric Chin. 2010, 4 (4): 422-429.

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In the long run, whether the use of chemical fertilizers could be reduced and soil fertility could be maintained through rice–fish coculture is less well known. At the pilot site of the rice–fish coculture system, which is one of the five “globally important agricultural heritage systems” (GIAHS), we conducted a 4-year study to compare fertilizer use, rice yield, and soil fertility in rice–fish coculture and rice monoculture. Based on the survey data from 21 villages, rice yield did not differ between rice monoculture and rice–fish coculture, but less chemical fertilizers were used in rice–fish coculture than in rice monoculture. Survey data from 145 farms also showed that rice–fish coculture farms with high input of feed for fish used less chemical fertilizers for rice production than farms with low input of feed for fish. In the 4-year field experiment, although less fertilizer was used in rice–fish coculture, rice yield, soil organic matter, soil total nitrogen, and soluble phosphorus did not differ between rice–fish coculture and rice monoculture. Our results suggest that rice–fish coculture can reduce chemical fertilizers application, enhance land productivity, and maintain soil fertility. Our results also suggest that rice–fish coculture could reduce the risk of non-point source pollution by reducing the input of chemical fertilizers.

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Kinetics of microbial immobilization of phosphorus in a weathered subtropical soil following treatment with organic amendments and Pseudomonas sp.
Rong SHENG, Min HUANG, Heai XIAO, Tida GE, Jinshui WU, Chengli TONG, Zhoujin TAN, Daping XIE
Front Agric Chin. 2010, 4 (4): 430-437.

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To understand the role of microbial processes in phosphorus (P) immobilization in a weathered subtropical soil, the effects of application of a phosphate-solubilization microorganism strain (Pseudomonas sp. 2VCP1) on P availability in soil, dynamics in microbial biomass P (Bp), microbial biomass C (Bc) and Olsen-P were investigated during a 60-d laboratory incubation. The included treatments were P. sp. inoculums at×106 cfu·g-1 soil (CKM); glucose at 5 g·kg-1 soil (G); G with P. sp. inoculum (GM); rice straw at 5 or 10 g·kg-1 soil (5S or 10S); 5S and 10S with P. sp. inoculum (5SM and 10SM). The results indicated that the amount of soil Bc increased about 3.2, 1.7, and 2.6 times for G, 5S and 10S compared to the control (no organic amendment and P. sp.; CK), respectively. The amount of soil Bp for G and 10S almost doubled during the first 7 d, then remained relatively steady. The amount of Olsen-P in G, 5S and 10S showed a significant decrease (0–5.4 mg P·kg-1 soil) during the 60-d incubation compared to CK. However, changes in soil Bp between the treatments inoculated with P. sp. (CKM, G, 5SM, 10SM) and the uninoculated controls (CK, G, 5S, 10S) were not significant during the 60-d incubation period, whereas a small increase in Bp of the GM treatment was seen up to day 11. The amount of soil Bc in CKM, GM, 5SM and 10SM had increased but not greater than 20% compared to their corresponding uninoculated control. The amount of Olsen-P increased but not greater than 0.88 mg P·kg-1 soil. The result illustrated that there were a few effects on soil P immobilization following inoculation with P. sp. in the soil, whereas organic amendments can significantly motivate the soil native microorganisms to immobilize phosphorus.

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Studies on isolated microspore embryoid induction of C. annuum L.
Ting YIN, Song TIAN, Shuangxia LUO, Xueping CHEN, Yanhua WANG, Shuxing SHEN
Front Agric Chin. 2010, 4 (4): 438-442.

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A system to improve isolated microspore embryoid induction rate of pepper (Capsicum annuum L.) was studied in this paper. The results showed that low-temperature pretreatment, growth regulators combinations, activated carbon concentrations, and preculture temperatures were critical factors affecting embryoid formation of isolated pepper microspores in vitro. One day after pretreatment of the buds at 4°C, the anthers that differentiated and developed into embryos were cultured in double-layer medium system for one week at 7°C and then went on culturing at 28°C in darkness. All the seven genotypes of the tested pepper responded to this protocol. The embryoid induction rate of the best genotype increased from 81.11% to 147.22%. This protocol can be used as a potential tool for producing doubled haploid plants for pepper breeding.

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Presence of indigenous endophytic bacteria in jujube seedlings germinated from seeds in vitro
Xiaojie HOU, Zhengnan LI, Dangyue HAN, Qiuxian HUANG, Longxian RAN
Front Agric Chin. 2010, 4 (4): 443-448.

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The presence of indigenous endophytic bacteria in tissue-cultured seedlings germinated from seeds of Zizyphus jujuba var. Fupingdazao was investigated using cultivation, light microscopy and scanning electronic microscopy (SEM). In addition, bacteria specific 16S rDNA PCR followed by denaturing gradient gel electrophoresis (DGGE) was used. No cultivable bacteria could be detected on plates or in liquid cultures. However, large quantities of endophytic bacteria in jujube seedlings were observed under the light microscope. The bacterial cells were round (measuring 1.5 μm-1.8 μm), short rods (2.2 μm-2.9 μm × 1.1 μm-1.9 μm) and rod shaped (3.7 μm-4.4 μm × 1.6 μm-1.9 μm). Rod-shaped bacterial cells (measuring 3.5 m-4.0 m × 1.5 m-2.0 m) were observed by SEM as well. A 16S rDNA fragment of 1.5 kb could be amplified from the total DNA of seedlings of jujube using the bacterial primer pair 27F/1525R. The V3 fragment of 16S rDNA was separated by DGGE, and the 16S rDNA-PCR-DGGE showed that there were at least six dominant bands within the seedlings of Z. jujuba var. Fupingdazao. It can be concluded that endophytic bacteria that cannot be detected by cultivation are present with high densities in jujube seeds.

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Establishment of cDNA-AFLP technology system and stoneless gene difference expression in Ziziphus jujuba Mill.
Bin HAN, Ruixia BAI, Li LI, Lisha ZHANG, Chuan MA, Jiwei ZHAO, Jinxin WANG, Jianying PENG
Front Agric Chin. 2010, 4 (4): 449-455.

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An efficient and stable cDNA-amplified fragment length polymorphism (cDNA-AFLP) analysis system for Chinese jujube was established and successfully used for the studies of related stoneless gene difference expression in Ziziphus jujuba Mill. ‘Wuhejinsixiaozao’ fruit. Several main factors influencing cDNA-AFLP analysis were studied, including the preparation and purification of cDNA, restriction and ligation of cDNA, the preamplification reaction, selective amplification reaction, electrophoresis on denaturing polyacrylamide gels, and sliver staining. The results indicated that the total RNA extracted by modified SDS method was pure, complete, and suitable for reverse transcription to cDNA. Restriction digestion of cDNA was performed by using two restriction enzymes, around 150 ng DNA digested with three units of EcoRI and MseI enzymes, respectively, and incubated at 37°C for 5 h. The digested cDNA fragment was diluted 5 times and used as templates for preamplification, and the preamplification products were diluted 10 times and used as templates for selective amplification. The selective amplification fragments were subjected to PAGE electrophoresis and silver staining. By cDNA-AFLP analysis, it acquired three transcript-derived fragments (TDFs), DC1, DC5, and DC9, related with stoneless gene of Z. jujuba Mill. ‘Wuhejinsixiaozao’ fruit.

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Construction of a plant expression vector of chalcone synthase gene of Ginkgo biloba L. and its genetic transformation into tobacco
Linling LI, Hua CHENG, Jianying PENG, Shuiyuan CHENG
Front Agric Chin. 2010, 4 (4): 456-462.

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The chalcone synthase gene (chs) from Ginkgo biloba L. was cloned by PCR procedure. For constructing a plant expression vector of Gbchs, the gene was digested with XbaI and BamHI and inserted into the pBI121 vector. Gbchs was transferred into tobacco mediated by Agrobacterium tumefaciens LBA4404. PCR and Southern blot were performed, and the results showed that chs had been transformed into the genomic DNA of tobacco. The total flavones in the transformed tobacco leaves was extracted by the methanol extraction method and tested by UV spectrophotometry. The results showed that, compared to the control tobacco, the content in the transgenic tobaccos, n=6, was generally higher, and the difference reached a significant level (P<0.05) and highly significant level (P<0.01), except one sample. Moreover, the highest sample was nearly 7.7 times greater than that of the controls. All these results show that utilizing genetic manipulations to improve plants in order to regulate flavone content by gene engineering may be an effective and hopeful method.

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Effect of high-temperature stress on the activity of key enzymes in the AsA-GSH cycle in ‘Yali’ pears
Yingli LI, Jianguang ZHANG
Front Agric Chin. 2010, 4 (4): 463-467.

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Through treating fruits at higher temperatures, choosing natural fruits on different exposures on a tree canopy and collecting exclusively both sunburn and normal fruits, the metabolic patterns were studied by comparing the activity of key enzymes in the ascorbate-glutathione (AsA-GSH) cycle including ascorbate peroxidase (APX), monodehydroascorbate reductase (MDAR), and glutathione reductase (GR). The results indicated that the activity of three enzymes increased under around less than 35°C acclimating conditions, with no significant changes in membrane electrolyte leakage. The activity of APX, MDAR, and GR rose during the initial stage when fruits were treated at 45°C but decreased significantly as treating time extended. A time response existed in APX, MDAR, and GR to high temperature. For example, APX activity reached the maximum when fruits were treated for 1 h, however, MDAR and GR showed the peak when fruits were treated for 3 h and 5 h, respectively, implying the possible acting sequence relationship of three enzymes in the AsA-GSH cycle. In view of the whole cycle, APX served as the first enzyme directly scavenging active oxygen species, followed by a series of chain reactions to regenerate ascorbic acid (AsA), and GR served as the last post in the cycle. Because various ecological conditions existed in a tree canopy, there was a significant difference in the enzymatic activity among fruits bearing on either exterior or interior canopy. A significantly higher activity of APX and MDAR was found with exterior fruits, compared with interior ones, which may be regarded as a frequent acclimation to high temperature and excessive sunlight.

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Effects of drought on electrical impedance spectroscopy parameters in stems of Pinus bungeana Zucc. seedlings
Aifang WANG, Gang ZHANG
Front Agric Chin. 2010, 4 (4): 468-474.

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The effects of drought during preplanting (three treatments: soil relative water content (RWC) 75%–80%, 55%–60%, 35%–40%; B1, 2, and 3, respectively) and postplanting (four treatments: RWC 75%–80%, 55%–60%, 35%–40%, 15%–20%; A1, 2, 3, and 4, respectively) on electrical impedance spectroscopy (EIS) parameters in the stems of Pinus bungeana Zucc. seedlings were investigated by using 4-year-old container seedlings. Stem impedance spectra were modeled by a distributed circuit element model (2-DCE), which showed the extracellular and intracellular resistance (re and ri), relaxation time (τ1 and τ2), and distribution coefficient (ψ1 and ψ2) of relaxation time. After preplanting B3 drought treatment, re and ri increased significantly with the increase of soluble sugar of the stem, measured by enthronlsulphuric acid method. After four weeks postplanting A4 drought treatment, relative conductivity, and soluble sugar of stem increased significantly, and re of stem decreased significantly and continually, indicating that the cell membrane of stem cells was disrupted by severe drought. After five weeks drought treatment, τ1 of stem under A4 treatment decreased significantly, and ψ2 of stem under A2, A3, and A4 treatments was higher than that of A1 treatment. Briefly, drought made re, ri, τ1, and ψ2 of stem change regularly, but re was found to be the most informative and useful parameter measured if used as a single index to assess the drought resistance of P. bungeana Zucc. seedlings.

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Allelopathic effects of Thymus kotschyanus on seed germination and initial growth of Bromus tomentellus and Trifolium repens
Front Agric Chin. 2010, 4 (4): 475-480.

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The allelopathic influence of aqueous extracts of Thymus kotschyanus on Bromus tomentellus and Trifolium repens germination (%), germination speed, and seedling growth (length, fresh and dry weight) was examined. It was noted that aqueous extracts had a considerable inhibitory effect on target plant germination, and the effect at 50%, 75%, and 100% concentration was found to be significantly higher than that at lower concentrations (5% and 25%) and control treatment (distilled water). Seedling length in addition to fresh and dry weights was also reduced significantly over control. The inhibitory effect was increased as the extract concentration was increased. B. tomentellus showed a higher sensitivity against T. kotschyanus in allelopathic effects compared to T. repens, which indicates that B. tomentellus planted in rangelands with leaf litter of T. kotschyanus will be adversely affected in terms of its germination, growth, and ultimately low forage production.

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Nutritional evaluation of tender pods of Canavalia maritima of coastal sand dunes
Bhaskar BHAGYA, Kandikere R. SRIDHAR, Sahadevan SEENA, Chiu-Chung YOUNG, Ananthapadmanabha B. ARUN
Front Agric Chin. 2010, 4 (4): 481-488.

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This study has been performed to evaluate the nutritional, antinutritional and protein qualities of tender pods of Canavalia maritima, the coastal sand dune wild legume of southwest India. The proximal features, minerals, amino acids, fatty acids, antinutritional and protein qualities of fresh and pressure-cooked tender pods have been assessed. The crude protein was comparable to seeds of many edible legumes. Cooking significantly elevated the carbohydrates and calorific value of tender pods (P<0.05), while crude fiber was significantly decreased (P<0.05). Minerals of fresh pods did not drain too much on cooking and K, Mg, Zn and Mn in fresh as well as cooked pods were comparable or higher than the NRC-NAS recommended pattern. Although cooking decreased the essential amino acids, threonine, valine, isoleucine, phenylalanine and lysine in cooked pods were equivalent or higher than the FAO-WHO-UNU recommended pattern. The palmitoleic acid in fresh pods and eicosenoic acid in cooked pods were relatively high. Similarly, the essential fatty acids, linolenic acid and linoleic acid were confined to fresh and cooked pods respectively. The fresh pods were devoid of tannins and trypsin inhibitors. The total phenolics and hemagglutinin activity decreased substantially in cooked pods. The diet of pressure-cooked pods showed improvement of in vivo protein quality, elevation of growth parameters and positive nitrogen balance in rats. Overall, the pressure-cooking of tender pods of C. maritima improved the nutritional qualities by lowering the hemagglutinin activity.

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Determination of polychlorinated biphenyls by GC/MS with ultrasound-assisted extraction from shellfish
Qunbiao ZHOU, Yaxin SANG, Li WANG, Shuangshang JI, Jing YE, Xianghong WANG
Front Agric Chin. 2010, 4 (4): 489-493.

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An efficient extraction method by ultrasound-assisted extraction (UAE) was developed for the extraction of polychlorinated biphenyls (PCB 28, 52, 101, 118, 130, 153, 180) from various shellfish. Analytes were determined by gas chromatography–mass spectrometry in selected ion monitoring (SIM) mode. All the samples were extracted by n-hexane and decontaminated by concentrated sulfuric acid. The resulting samples were determined by quantitative detection by comparing with external standards. The average recoveries of seven kinds of PCBs ranged from 80.92% to 93.89%, and the lowest detectable limit was 0.08–0.03 μg·kg-1. The average concentrations of total PCBs were 14.12–30.61 μg·kg-1 in the samples. This method was highly effective in reducing the cost and time for the pretreatment of samples. This method may be applied for the screening and monitoring of shellfish for organic pollutants in coastal waters.

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Effects of folic acid supplementation on growth performance and hepatic folate metabolism-related gene expressions in weaned piglets
Bing YU, Guangbo YANG, Jingbo LIU, Daiwen CHEN
Front Agric Chin. 2010, 4 (4): 494-500.

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The present study was conducted to evaluate the effects of different folic acid supplemental levels on growth performance, serum biochemical indicators, and hepatic folate metabolism-related gene expressions in weaned piglets. There were 160 piglets with initially average bodyweight of 7.33 kg randomly assigned to diets containing five levels of folic acid: basal diets (C), 0.5 mg·kg-1 folic acid (FS 0.5), 2.5 mg·kg-1 folic acid (FS 2.5), 5.0 mg·kg-1 folic acid (FS 5.0), or 10.0 mg·kg-1 folic acid (FS 10.0). Blood samples were collected from a subset (n = 20; 4 pigs per treatment) of the piglets on day 0, 14, and 28. Liver samples were collected from the blood-taken piglets on day 28 of the experiment. Pigs fed basal diet supplemented with 2.5 mg·kg-1 folic acid grew faster (P<0.05) and consumed more feed (P<0.01) than groups of C, FS 5.0, and FS 10.0 during the last two weeks. Dietary treatment had no effect on F/G throughout the experiment. Pigs in the FS 2.5 group showed greater concentrations of Growth Hormone (GH) (P<0.05) and Insulin-like Growth Factors (IGF-1) (P<0.01) in serum than C and FS 10.0 on day 28. RT-PCR analysis revealed that FS 0.5, FS 2.5, and FS 5.0 had a greater abundance of the mRNA encoding 5,10-methylenetetrahydrofolate reductase than C and FS 10.0 (P<0.01). The mRNA expressions of folate binding protein in FS 0.5 and FS 2.5 were upregulated compared with pigs fed with basal diet (P<0.05). These results demonstrated that folate supplemental level of 2.5 mg·kg-1 significantly enhanced the growth performance of piglets. Folic acid had an impact on folate metabolism and the homocysteine concentrations. No folate supplementation or folate supplemental level of 10 mg·kg-1 could not increase the growth performance to the greatest degree.

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MPN-PCR enumeration of Campylobacter spp. in raw chicken meats and by-products
John Yew Huat TANG, Farinazleen Mohamad GHAZALI, Abdul Aziz SALEHA,, Yoshitsugu NAKAGUCHI, Mitsuaki NISHIBUCHI, Son RADU
Front Agric Chin. 2010, 4 (4): 501-506.

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The goal of this study is to enumerate Campylobacter in chicken meats and by-products. In the current investigation, results showed that raw chicken meats and chicken by-products were contaminated with Campylobacter ranging from<3 to 4600 MPN·g-1. Campylobacter jejuni showed a higher number compared to Campylobacter coli in the chicken samples. The current study showed that the percentage of chicken livers and gizzards harbored a higher number of Campylobacter (103–104 MPN·g-1) than other chicken parts at 33.3% and 9.2%, respectively. The different concentrations of Campylobacter between chicken meats and chicken by-products reflect the differences in the contamination level. The data on Campylobacter concentration in chicken meats and by-products will be useful in risk analysis.

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Effect of various dietary vitamin A levels on growth performance and immune response of tilapia (Oreochromis niloticus)
Ran GUO, Chhorn LIM, Hui XIA, Mediha Yildirim AKSOR, Menghe LI
Front Agric Chin. 2010, 4 (4): 507-512.

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Six purified vitamin-free casein-based diets were formulated to contain six levels vitamin A at 0, 500, 1000, 2000, 4000, and 8000 IU·kg-1, respectively. Tilapias (initial mean weight: 7.73±0.03 g) were fed the diets in quadruplicate aquaria to apparent satiation twice daily for 10 weeks. No differences in mortality, weight gain, or feed efficiency ratio (FER) were observed among the groups. Liver vitamin A levels reflected dietary vitamin A levels. Immune parameters, such as hemoglobin levels, total cell count, red blood cell count, total serum protein, and serum lysozyme activity, did not vary with the dietary vitamin A levels. White blood cell counts of fish in 2000 IU·kg-1 diet groups were significantly higher than that in other diets groups. Serum complement activities of fish in 2000 and 4000 IU·kg-1 vitamin A diet groups were also higher than those in other diet groups. After the 14-d challenge test, the mortality and antibody titer were similar among the treatments. The results indicated that dietary vitamin A inclusions did not affect the immune response of Oreochromis niloticus.

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18 articles