Frontiers of Agriculture in China

ISSN 1673-7334

ISSN 1673-744X(Online)

CN 11-5729/S

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Research articles
Some factors affecting the concentration of the aroma compound 2-acetyl-1-pyrroline in two fragrant rice cultivars grown in South China
Piebiep GOUFO, Meiyang DUAN, Xiangru TANG, Sugunya WONGPORNCHAI
Front. Agric. China. 2010, 4 (1): 1-9.

Abstract   PDF (160KB)
The fragrance potential of two fragrant rice (Oryza sativa L.) cultivars grown in South China was investigated in this study using headspace SPME and static headspace in conjunction with GC-MS. About a five-fold difference of 2-acetyl-1-pyrroline (2-AP) levels were observed among the two fragrant rice cultivars, with Guixiangzhan having the highest content (3.86 µg·g−1) comparable to that obtained with Thai KDML 105 rice. Other compounds instead of 2-AP were assumed to contribute to the characteristic aroma of Peizaruanxiang. The two cultivars were subjected to two preharvest treatments (planting density and harvest date) and different storage conditions (3 to 6 months at −4, 8, 20, and 30°C). Results were discussed in terms of grain yield, milling quality, grain appearance, and amylose and protein contents of rice samples associated with differing treatments. Highest 2-AP concentrations were obtained for Guixiangzhan and Peizaruanxiang with lower planting densities, the earliest harvesting time of 10 days after heading, the shortest storage time of 3 months, and the lowest storage temperature of −4°C. These findings indicate that manipulating pre- and postharvest treatments can greatly improve the specific attributes of the domestically produced cultivars. With that in mind, China could effectively increase its share of the domestic market of fragrant rice and even tap into the international market.
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Expression of special genes inhibited by powdery mildew ( Blumeria graminis f. sp. tritici ) in wheat germplasm N9436
Jinhua WU, Zhiying MA, Yingang HU, Hong ZHANG, Changyou WANG, Qiuying WANG, Wanquan JI,
Front. Agric. China. 2010, 4 (1): 10-17.

Abstract   PDF (151KB)
Powdery mildew, caused by Blumeria graminis f. sp. tritici, is one of the most important fungal diseases in common wheat (Triticum aestivum L.) worldwide. Wheat germplasm N9436 is resistant to powdery mildew. In the present study, a backward subtracted cDNA library was constructed with cDNA from N9436 leaves inoculated by Blumeria graminis as the driver and cDNA from uninoculated N9436 leaves as the tester. A total of 120 positive clones were randomly chosen from the SSH-cDNA library and were amplified with sp6 and t7 primers to examine the insert size. After screening the repeated and redundant sequences, 59 expressed sequence tags (EST) were acquired. Nucleic acid and protein homology search were performed using the basic local alignment search tool (BLAST) program with the default settings at NCBI website ( BlastX results in nr-protein database revealed that 23 ESTs were highly homologous with known proteins involved in primary metabolism, energy metabolism, transport, signal transduction, and disease resistance and defenses. BlastNr results showed that 47 and 10 ESTs had high identities with known Unigene and function-unknown ESTs, respectively, and two ESTs matched none in the nr-database. Twenty-one ESTs were both in the nucleic acid and protein databases, including seven ESTs associated with powdery mildew resistance. Among them, one was responsible for signal transduction and six for systemic acquired resistance (SAR) system.
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Identification of Lr24 with targeted region amplified polymorphism (TRAP) analysis in wheat
Na ZHANG, Wenxiang YANG, Daqun LIU, Shengliang YUAN,
Front. Agric. China. 2010, 4 (1): 18-23.

Abstract   PDF (217KB)
This research is aimed at developing TRAP markers, as a probe for library screening, closely linked to or co-segregated with Lr24. Ninety TRAP primer pairs were used to test the resistant and susceptible parents, as well as the resistant bulk and the susceptible bulk in our study. The polymorphic TRAP primers of TcLr24 were employed to genotype the F2 population from TcLr24×Thatcher subsequently. Ten of 90 TRAP primer pairs displayed polymorphism between TcLr24 and Thatcher, accounting for 11.11%. A further study found that primer ARBI1/RGA-2F generated a 161bp fragment presented only in the resistance plants of F2 population. Forty-five other wheat leaf rust resistant NILs and 30 diploid materials of wheat were also tested to detect the specificity of the primer. This specific band was amplified in TcLr19, TcLr29, TcLr38, TcLr42 and TcLr44, but absented in all the 30 diploid materials. It was concluded that this marker ARBI1/RGA-2F was closely linked to Lr24, which could be used to detect Lr24 in the F2 population of TcLr24×Thatcher, and be further used as a probe for cDNA and BAC library screening of TcLr24.
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Arbuscular mycorrhiza fungi as an ecology indicator for evaluating desert soil conditions
Yanqing WU, Jizhi JIANG, Weike SHEN, Xueli HE,
Front. Agric. China. 2010, 4 (1): 24-30.

Abstract   PDF (196KB)
Arbuscular mycorrhiza (AM) fungi are the most common underground symbiosis. They can form vesicles and arbuscules in the roots of about 80% of plant species. In this paper, using the arbuscular mycorrhiza’s colonization as an evaluating indicator in combination with other experimental indicators, we composed a system of evaluating various indices to analyze desert soil conditions. A fuzzy optimization system model was introduced to analyze the experimental results. The results showed that the soil quality was Yulin>Ecology Station>Yanchi>Shapotou>Dingbian. ‘μi’, an indicator of soil quality, was the greatest in the topmost layer of soil, in the 0–10cm soil, at the sampling sites Yulin, Ecology Station, Yanchi and Dingbian. However, at Shapotou the maximum value of μi was found in the 10–20cm soil layer. The weight value of the AM fungal index ranged from 37% to 95% at different sites.
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Expression analysis of RUS1 and construction of RUS1 plant expressing vector
Qiaoyun WENG, Jihong XING, Jingao DONG, Zhiyong LI, Zhiping DONG,
Front. Agric. China. 2010, 4 (1): 31-36.

Abstract   PDF (148KB)
RUS1 was one of the disease resistance gene analogs obtained from Setaria italica Beauv. Semi-quantitative RT-PCR analysis result showed that RUS1 gene could be induced by Uromyces setariae-italicae and had relation to the resistance response of Setaria italica Beauv. against Uromyces setariae-italicae infection. Promoter sequence of RUS1 was obtained by the method of Genome Walking, and its length was 675 bp. RUS1 promoter and pCAMBIA1300 vector were fused to construct RUS1∷GUS vector. GUS histochemical staining result showed that promoter could activate gene expression. RUS1 gene (including the promoter sequence) was obtained through PCR amplification and then fused with pCAMBIA1300 vector to construct pCAMBIA1300∶RUS1 plant expressing vector. The research laid a foundation for gene functional identification of RUS1.
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Detection of indigenous endophytic bacteria in Eucalyptus urophylla in vitro conditions
Hongmiao SHEN, Dangyue HAN, Fenghuan YANG, Qiuxian HUANG, Longxian RAN, Zhengnan LI,
Front. Agric. China. 2010, 4 (1): 37-41.

Abstract   PDF (199KB)
The presence of indigenous endophytic bacteria in aseptically grown seedlings of Eucalyptus urophylla germinated from surface sterilized seeds was investigated using dilution plating, microscopy, and PCR detection. No culturable endophytic bacteria could be detected in suspensions of ground plant tissue incubated on solid or in liquid cultivation media. However, a large number of endophytic bacterial cells, mostly rod-shaped and measured 2–3μm×0.5–0.8μm, were observed in in vitro cultured seedlings of E. urophylla using both light and electron microscopy. Using the universal bacterial 16S rDNA primers, a predicted 190-bp fragment was amplified from total DNA isolated from the seedlings of E. urophylla. We concluded that the endophytic bacteria originated from the seed were present in seedlings of E. urophylla. However, the bacterial cells observed appeared to be nonculturable.
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Effects of N-applications and photosynthesis of maize ( Zea mays L.) on soil respiration and its diurnal variation
Lanfang YANG, Jingjing YAN, Zucong CAI,
Front. Agric. China. 2010, 4 (1): 42-49.

Abstract   PDF (159KB)
In order to understand the relationship of soil respiration to N-applications and photosynthesis, a soil pot experiment of planting maize with two N-applications was conducted. During the trumpeting stage, maize plants were shaded for three days and soil respiration was sampled by static chamber method and measured by gas chromatography. A clear diurnal cycle of soil respiration rate (SRR) showed a single peak curve in which the rate crested at about 14:00 during a day-night period and the daily average SRR was very close to that between 18:00 and 21:00. The SRR increased with soil N-application and the measured average SRR in three days was 29% higher in high N-application (HN, 300mg∙kg−1 of N) than that in low N-application (LN, 150mg∙kg−1 of N). The shaded plants significantly decreased the SRR and its diurnal variation. The soil respiration within the first, second and third day-night decreased to about 21%, 50% and 65%, respectively compared with the un-shaded plants. Under non-shading treatments, the exponential relativity of SRR was significantly dependent on temperature but not on time, while in shaded plants, it was significantly dependent on both temperature and shading time, with the relative coefficient to shading time significantly higher than that to temperature. In summary, soil N-application could increase the soil respiration, while the shaded plants not only decreased the SRR and its diurnal variation but also altered the relationship between the SRR with temperature, thus the soil respiration during maize growth was mainly derived from the recent photosynthates. Photosynthesis, together with temperature, are the key factors controlling the diurnal variation of soil respiration.
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A modified rectangular hyperbola to describe the light-response curve of photosynthesis of Bidens pilosa L. grown under low and high light conditions
Zipiao YE, Zehai ZHAO,
Front. Agric. China. 2010, 4 (1): 50-55.

Abstract   PDF (130KB)
The light-response curve of leaf net photosynthesis is an important tool for understanding the photochemical efficiency of the photosynthetic process. We measured the light-response of the photosynthetic rate of Bidens pilosa L., when grown under high light of 100% full sunlight (HL) and low light of 50% full sunlight (LL) using a gas analyzer Li-6400. The measured data were simulated by a modified rectangular hyperbola. The fitted results showed that the modified rectangular hyperbola described the part of the curve up to the light saturation and the range of levels above the saturation light intensity in Bidens pilosa L. well. It was used to directly calculate the main photosynthetic parameters, including the light-saturated net photosynthetic rate (Pmax), saturation light intensity (Im), light compensation point (Ic), dark respiration rate, and the initial slope of curve without any additional hypotheses. Good agreement was obtained between the modified rectangular hyperbola estimates and observations of Pmax and Im of B. pilosa under LH and LL conditions. Furthermore, the modified rectangular hyperbola provided a very easy and simple method for simultaneously simulating the data on the light-response curve of photosynthesis at low irradiances, saturating irradiances, photoacclimation and photoinhibition.
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Effects of drought on soluble protein content and protective enzyme system in cotton leaves
Dongxiao LI, Cundong LI, Hongchun SUN, Wenxin WANG, Liantao LIU, Yongjiang ZHANG,
Front. Agric. China. 2010, 4 (1): 56-62.

Abstract   PDF (206KB)
The effects of soil drought on soluble protein content and protective enzyme system of cotton leaves at different positions were studied in the transgenic cotton cultivar, Lumianyan28. The results indicated that the soluble protein content in main stem leaves and in middle-fruit branch leaves under drought treatment were higher than that of CK, the normal soil water management treatment. Lower fruit branch leaves under drought treatment had higher protein and enzyme levels than CK treatments. From June 25 to July 22, the activity of superoxide dismutase (SOD) in main stem leaves under drought treatment was lower than that of CK. Other time periods had varying results. The peroxidase (POD) activity in main stem leaves and in fruit branch leaves was lower at early stage and then higher at late stage, showing a trend of descending first, and then ascending obviously under the drought condition. The catalase (CAT) activity showed an increase-decrease trend, higher in main stem leaves under drought treatment than that of CK. However, it was opposite in the lower fruit branch leaves, and there were no significant differences between the two CAT treatments in the middle branch leaves. It is suggested that the soluble protein and cellular protection enzymes, such as superoxide dismutase, peroxidase activity, and catalase in main stem leaves and fruit branching leaves play important physiological functions in the early growth stage under drought stress.
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Effects of various salts on the germination of two cultivars of Medicago sativa
Front. Agric. China. 2010, 4 (1): 63-68.

Abstract   PDF (102KB)
The germination responses of Medicago sativa (Yazdi and Hamedani cultivars) seeds to salinity stress by different salt solutions were studied in this project. To evaluate salt tolerance during germination, 25 seeds of each cultivar were placed on filter paper in 9 cm petri dishes containing distilled water (control), 30, 60, 90, 120, 150, 180, 210, 240, 270, and 300 mmol·L−1 saline solutions of NaCl, CaCl2, and KCl, respectively. The results indicated that the effects of salinity levels were significant (P < 0.05) for percent seed germination, seed germination rate, mean time to germination, length of the stem, and radical and seed vigor. Seed germination decreased significantly by increasing salinity levels. These two cultivars of alfalfa were more resistant to KCl than NaCl and CaCl2 salts, respectively. In addition, the results showed that the Hamedani cultivar was more tolerant than Yazdi cv. against salinity.
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An ultrasound-assisted extraction technology of almond dregs protein
Zhenliang ZHANG, Zide ZHANG, Xiaona ZHANG, Jing LI, Congzhi ZHAO, Yan WANG,
Front. Agric. China. 2010, 4 (1): 69-73.

Abstract   PDF (167KB)
Using quadratic regression orthogonal design rotation, the ultrasound-assisted alkaline extraction process of protein from almond dregs was optimized in the experiment. The results showed that the optimized parameters of the almond dregs protein extraction process were as follows: extracting temperature 37°C, pH value 10.1, and ratio of solid to liquid 1∶29.5 (g·mL−1). The efficiency of protein extraction was 69.76% with twice extraction for each 30min under the above conditions.
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The genomic sequence of AFS-1―an alpha -farnesene synthase from the apple cultivar ‘Royal Gala’
Lesley BEUNING, Sol GREEN, Yar-Khing YAUK,
Front. Agric. China. 2010, 4 (1): 74-78.

Abstract   PDF (362KB)
The genomic sequence encoding alpha- farnesene synthase-1 (AFS-1) was amplified from genomic DNA isolated from ‘Royal Gala’ apple (Malus×domestica Borkh.). The genomic sequence consists of six introns and seven exons, which is consistent with Class III terpene synthases. Four variants of the genomic sequence were amplified. The four variants are based on the presence or absence of a repeat of two sequences, one found in intron 4 (CAGTTATTTAATT) and the other in intron 5 (TA). Although there were small nucleotide differences among the three apple cultivars ‘Royal Gala’, ‘Idared’, and ‘Ralls’, these resulted in only two amino acid changes in the protein sequence, which are unlikely to explain the resistance or susceptibility of an apple cultivar to superficial scald. Given that AFS-1 transcript levels are high in all cultivars, it appears that it is either the reactions downstream of alpha-farnesene production that control the accumulation of oxidation products related to superficial scald or that the variation in the level of its substrate, farnesyl diphosphate, may cause differences in the amount of alpha-farnesene produced.
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Effects of salicylic acid on the behavior of Yali pear infected by Alternaria kikuchiana Tanaka
Yongbo WANG, Yuxing ZHANG, Jianghong ZHANG,
Front. Agric. China. 2010, 4 (1): 79-83.

Abstract   PDF (212KB)
To investigate the inductive effect of salicylic acid (SA) on the resistance of Pyrus bretschneider cv Yali to black spot disease (Alternaria kikuchiana Tanaka), the physiological and biochemical characteristics of detached pear leaves at the age of 5 to 10 days were measured after application of SA. The results showed that exogenous SA significantly improved the resistance of Yali pear (Pyrus bretschneider cv Yali) leaves to black spot disease. For the SA treatment at 0.02mmol·L−1 SA concentration, the disease index was the lowest, and the induced resistance reached up to 63.9%. Furthermore, SA induced local and systemic resistance of Yali pear against the black spot disease. Expression of systemic resistance in leaves was detectable 3 d after SA treatments and lasted for 10 d. POD, PPO, and PAL activities of Yali pear leaves increased by SA treatment. It is suggested that exogenous SA solution as a chemical activator could induce the resistance of Yali pear to black spot disease.
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Advances in the research on the AsA-GSH cycle in horticultural crops
Yingli LI, Yufang LIU, Jianguang ZHANG,
Front. Agric. China. 2010, 4 (1): 84-90.

Abstract   PDF (135KB)
The adaptation of plants to stressed environments depends greatly upon the metabolic level of antioxidant systems within their bodies. Among the enzymatic antioxidant systems, the AsA-GSH cycle occupies a vital place and has become a hot research field in recent years. The AsA-GSH cycle can directly scavenge H2O2 produced in plants on one hand, and the antioxidants AsA and GSH produced in the cycle can also scavenge other species of active oxygen by means of additional pathways on the other hand. Environmental conditions and exogenous formulations can alter the oxidative and reductive status in plants and mediate the metabolic level of the AsA-GSH cycle within a certain range, thus regulating the resistance of plants to stresses. The present paper reviews the advances in research on the AsA-GSH cycle with respect to horticultural crops, so as to provide some beneficial reference for further studies.
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Influence of crust-covered paving on photosynthesis and chlorophyll fluorescence parameters of a city landscape plant, Firmiana simplex
Xiaojuan WANG, Zhigang WANG,
Front. Agric. China. 2010, 4 (1): 91-95.

Abstract   PDF (97KB)
In order to explore the influence of crust-covered paving on city landscape plants, the photosynthesis and chlorophyll fluorescence parameters of Firmiana simplex were studied in this paper by the LCI portable plant photosynthesis meter and the OS5-FL-mode pulse modulated chlorophyll fluorometer. The results showed that during the day, the net photosynthetic rates of Firmiana simplex leaves under the crust-covering stress were slightly lower than those of the control, and the differences were significant at 18:00; the transpiration rate of the treatment group showed a single-peak curve, with the peak appearing between 12:00–14:00, while the transpiration rate of the control group showed a bimodal curve with the peak appearing at 10:00 and 16:00, respectively. When the transpiration rate of the control showed a low peak at 14:00, the transpiration rate of treatments was very significantly higher, and the difference was as much as 45.08%. In addition to 16:00 of all day, the water use efficiency of Firmiana simplex leaves under crust-covered condition was slightly higher than that of the control; the differences were not significant in the morning but very significant in the afternoon. The stomatal conductance of treatments was significantly higher than that of the control at 14:00 and slightly lower than the control at any other time. The intercellular CO2 concentration of treatments was higher than that of the control during the day except at 16:00, and the difference was significant at 14:00 and 18:00. The maximal photochemical efficiency of PS II (Fv/Fm) and the potential activity of PS II (Fv/Fo) of treatments were both lower than those of the control during the day except at 18:00, with very significant differences at 14:00. By this token, we concluded that the crust-covered paving had somehow brought a certain stress to the city landscape plant, Firmiana simplex.
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Effects of NaCl stress on two blue fescue varieties ( Festuca glauca )
Kai LI, Huibin LI, Xiuju BIAN, Zhao MENG, Yujing ZHAO,
Front. Agric. China. 2010, 4 (1): 96-100.

Abstract   PDF (190KB)
Blue fescue is a widely used ornamental grass worldwide. Research on its salt resistance is propitious to its application in northern China where there are large areas of saline-alkali land. This study was conducted to examine the effects of NaCl stress on two blue fescue varieties Valesiaca and Select. Percentage of green leaves (PGL) of both Valesiaca and Select responded similarly to 0.3% and 0.6% NaCl treatments. Under a higher NaCl application level (1.2% NaCl), Valesiaca was reduced by below 60% at the 12th day and reached 20% at the end of the experiment, but Select to 71.67% at the 12th day and stayed over 50% unto the end. The 0.9% and 1.2% NaCl treatments sharply increased Proline content, and then reached and maintained at a maximum level throughout the treatment. Proline content of Valesiaca increased to 2.28mmol·L−1 at the 8th day after the 1.2% NaCl treatment, but only 0.95mmol·L−1 in the treatment of 0.3% at the same day. For Valesiaca, 1.2% NaCl treatment significantly increased its SOD activity to 30.69units·mg−1, nearly 50% higher than 0.3% treatment at the 8th day after treatment, and over 53% higher at the 27th day. POD activity of Valesiaca increased to 6.92units·mg−1 at the 8th day after the 1.2% NaCl treatment, but it was 2.59units·mg−1 for 0.3% stress treatment. In conclusion, similar changes of determined index were observed for both cultivars under low NaCl stress levels (0.3%–0.6%). However, Valesiaca was more sensitive and less tolerant to high level NaCl stress (0.9%–1.2%) than Select, indicating that Valesiaca was less resistant to NaCl compared with Select.
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Effects of supplemental energy sources and trans -10, cis -12 conjugated linoleic acids (CLA) on milk yield and composition in lactating Holstein cows
Xueyan LIN, Guoyi LIANG, Pengcheng SU, Zhonghua WANG,
Front. Agric. China. 2010, 4 (1): 101-108.

Abstract   PDF (129KB)
The effects of supplemental energy sources (corn or saturated fatty acids) and trans-10, cis-12CLA on milk yield and composition were investigated in the present study. Four multiparous Holstein cows (560€±€31 kg BW, 98€±€10.5DIM) were designated to a 2×2 factorial 4×4 Latin Square experiment. Treatments were isoenergetic supplementation of corn or calcium salt of saturated fatty acids (CaFA) with or without calcium salt of CLA. Both milk yield and composition were affected by sources of supplemental energy. Compared to CaFA supplementation, corn supplementation increased the milk yield, the lactose yield, and the content and yield of milk protein but decreased the yield and content of milk fat. Plasma insulin was higher, plasma glucose tended to be higher, and plasma non-esterified fatty acid (NEFA) was lower when corn rather than CaFA was supplemented. CaCLA supplementation did not affect milk yield and the yield of measured milk components, but increased the content of milk protein and decreased the content of total solids. Plasma glucose was decreased by CaCLA supplementation. Content and yield of short and medium chain fatty acids (≤16 carbon atoms) in milk fat increased or remained unchanged while those of long chain fatty acids (>16 carbon atoms) decreased or remained unchanged by corn supplementation. CaCLA supplementation failed to increase the content and yield of trans-10, cis-12CLA in milk fat, which explained the unobserved depression of milk fat synthesis by CaCLA supplementation. Yields of de novo synthesized fatty acids in the mammary gland were increased rather than decreased by corn supplementation. The decreased milk fat yield by corn supplementation could be exclusively attributed to reductions in preformed fatty acids, which might be a res-ult of depressed lipolysis by stimulated insulin secretion.
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Bioinformatics analysis of tyrosinase-related protein 1 gene ( TYRP1 ) from different species
Huiqin ZHENG, Xianglong LI, Rongyan ZHOU, Lanhui LI, Xiuli GUO, Jingfen KANG, Dongfeng LI,
Front. Agric. China. 2010, 4 (1): 109-115.

Abstract   PDF (119KB)
As one member of the tyrosinase-related family directly involved in the production of melanin, TYRP1 is involved in not only melanogenesis but also prevention of melanocyte death, stabilizing tyrosinase and helping determine the shape of melanosomes, etc. Multi-species sequence comparisons showed that there were two evolutionally conserved non-coding regions (from −1306 to −733 and from −642 to −515 according to AL138753) upstream of translational initiation sites, representing putative regulatory regions subject to subsequent experimental tests. Coding sequence length variation and genetic diversity analysis showed that Felis catus, Homo sapiens and Canis familiaris had more genetic diversities than the other species for TYRP1, especially Felis catus that could be a better choice for studying the TYRP1-associated genetic basis underlying the color diversity. As a 75kDa type-1 transmembrane glycoprotein, mature TYRP1 possesses about 17kDa modifying components, whose function predominantly depends on the existing glycosyl- groups and the Cu components. In addition, the mutated amino acids within species and the highly conserved amino acids among species were listed in our paper.
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Antibiogram and heavy metal resistance of pathogenic bacteria isolated from moribund cage cultured silver catfish ( Pangasius sutchi ) and red hybrid tilapia ( Tilapia sp.)
Seongwei LEE, Musa NAJIAH, Wee WENDY, Musa NADIRAH,
Front. Agric. China. 2010, 4 (1): 116-120.

Abstract   PDF (137KB)
Antibiogram and heavy metal resistance patterns of pathogenic bacteria isolated from moribund cage cultured silver catfish (Pangasius sutchi) and red hybrid tilapia (Tilapia sp.) from Sungai Manir, Terengganu, Malaysia were studied and characterized. Sungai Manir is one of the famous rivers in Terengganu for its wide variety of cage cultured freshwater fish. However, to date, the baseline information of antibiogram and heavy metal resistance patterns of the pathogenic bacteria attacking the freshwater fish cultured in Sungai Manir is still lacking. Therefore, this study was carried out, which may be useful for fish farmers as a guideline for fish prophylactic and treatment purposes. Furthermore, present studies also provide information on the safety level of consuming freshwater fish produced from Sungai Manir. In the present study, bacteria were isolated from 100fish of each moribund silver catfish and red hybrid tilapia using seven media including tryptic soy agar (TSA), Mac Conkey, thiosulphate citrate bile salt (TCBS), eosin methylene blue (EMB), glutamate starch pseudomonas (GSP), xylose lysine deoxycholate (XLD) and Baird Parker media. Identification of bacteria was carried out using conventional biochemical tests and confirmed by commercial bacterial identification kit. Antibiogram of the bacterial isolates against 18 antibiotics; oxolinic acid (2 µg), ampicillin (10 µg), erythromycin (15 µg), furazolidone (15 µg), lincomycin (15 µg), oleandomycin (15 µg), amoxicillin (25 µg), colistin sulphate (25 µg), sulphamethoxazole (25 µg), chloramphenicol (30 µg), doxycycline (30 µg), florfenicol (30 µg), flumequine (30 µg), kanamycin (30 µg), nalidixic acid (30 µg), tetracycline (30µg), nitrofurantoin (50 µg) and spiramycin (100 µg) was carried out using disk diffusion method, whereas heavy metal resistance patterns (Hg2+, Cd2+, Cr6+ and Cu2+) of the bacterial isolates was determined through two-fold agar dilution method. The results showed that the percentage of sensitivity case of the 120 bacterial isolates to the tested antibiotics was 62.7%. This was followed by resistance (26.9%) and intermediary sensitive (10.4%) cases. In terms of the heavy metal resistance patterns, all bacterial isolates were resistant to Hg2+ and Cr6+. However, only 27.8% and 16.7% of the bacterial isolates were sensitive to Cu2+ and Cd2+, respectively. The multiple antibiotic resistance (MAR) indices indicated that the cage cultured silver catfish and red hybrid tilapia were under high exposure to the tested antibiotic. Overall, the results of the present studies showed that Sungai Manir may be polluted with heavy metal and antibiotic residues.
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Unigene derived SSR analysis for the Fugu rubripes and insights into the characteristics of EST-SSR distribution in tissues/organs
Jiaqing WANG, Lin HOU,
Front. Agric. China. 2010, 4 (1): 121-127.

Abstract   PDF (133KB)
A total of 11348 Unigene derived ESTs from five cDNA libraries corresponding to five different tissues/organs were screened for EST-SSR, and 1097 EST–SSRs (9.67%) were detected. There were considerable variations in the amount of EST-SSRs among the five tissues/organs. In all the tissues/organs, trinucleotide repeats (67.74%) were found to be most abundant. The trinucleotide repeats GCG were the most abundant in three tissues/organs that ranged from 80.2% in skin, 83.3% in gut, to 90.2% in fin. Dinucleotide was the second abundant repeat type (13.58%), followed by tetra-(12.38%), hexa-(5.34%), and penta-(0.96%) nucleotide repeats. Furthermore, the results of the present study also indicated that the EST-SSR motifs were not randomly distributed in tissues/organs of fugu, such as trinucleotide repeats were found to be strikingly abundant in fin, followed by skin and gut, tetra-nucleotide repeats were especially rich in muscle, while pentanucleotide repeats were less common in any tissue or organ. Most of the EST-SSRs in five tissues/organs that were assigned functions during the present study represent housekeeping genes.
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