Vol. 11 No. 6 (2013)

Interleukin 2 (IL-2), one of the cytokines plays an important role for the immune response. IL-2 promotes the activation of T cells and so often used in immunotherapy such as kidney epithelial malignant and melanoma cancer. Gene encoding il-2 modified Cys125 to Ser was inserted into pET22b(+) harboring pelB secrete signal for expression in E. coli BL21(DE3) cells. To enhance the correct protein folding and solubility, IL-2 was simultaneously expressed with chaperone GroESL and thioredoxin (Trx). The results indicated that IL-2 proteins co-expressed with GroESL and Trx of 20 kDa were still existed in insoluble form and consisted of the pelB secret signal.  

In recent years, arsenic contamination as well as its effects on public health are increasingly becoming important and serious issues in worldwide, especially in developing countries. Glutathione S-transferase omega-1 (GSTO1) is a phase II enzymatic detoxification of xenobiotics in a variety of animals including humans, catalyzing the arsenic methylation. The efficiency of arsenic methylation is influenced by genetic polymorphisms at individual level. To assess the variations of single nucleotide polymorphisms of GSTO1, PCR-RFLP technique was ultilized. In this study, both SNP rs11509438 and SNP rs15032 in four studied samples were found homozygoous CC. These results may serve as basis for further studies on genetic polymorphisms of infants with pre-born arsenic exposure.

The titanium dioxide nanoparticle (TiO2 nano) has been being one of the most employed amongst the different nanoparticles in the fields of nanobiotechnology. The study was conducted with the purpose of preparing nano TiO2 solution from Ti(OC4H9)4 (Tetrabutylorthotitanate) by sol-gel method and its application in preventing viral diseases in plants. The study created nano TiO2 solution having transparant-white color and good dispersal. Images observed in a scanning electron microscope showed that the size of the TiO2 nanoparticles is in the range of 15 to 50nm. Test results on the tobacco plant showed that nano TiO2 solution prepared by us are capable of inhibiting the development and symptoms of TMV.

The present study was carried out to examine anti-bacterial effects of garlic extract obtained from 7 diffirent solvents (distilled water, acid acetic 5%, ethanol 35%, ethanol 70%, methanol 70%, acetone 70%, acetone nitrile 70%) on E.coli (1 pathogenic strain E.coli O44 isolated from fecal samples of cholera infected chicken; E. coli  strain Top 10 with plasmid: E.coli Top 10 pJET 1.2/blunt resistant to ampicillin and E. coli Top 10 pPS1 resistant to kanamycin).  Results have identified that all 7 different garlic extracts had anti-bacterial effects against E coli. Garlic extracts obtained from acetonitrile 70%, acetic acid 5%, and 70% acetone) showed high anti-bacterial activity (inhibition zone diameters ≥ 20mm)

Lilium brownii var. colchesteri (BRO) has an unique characteristic, i.e., the flower color changes from yellowish-cream to white during anthesis. For introducing this trait to cut flower production in Lilium, interspecific crosses of L. longiflorum (as seed parents) and BRO (as a pollen parent) were carried out. Capsules with unviable seeds were found in all crosses. To overcome the incongruity barrier, ovary slices excised from developing ovaries at 7 to 28 days after pollination (DAP) were cultured in a Murashige and Skoog medium supplemented with 40g·L-1 sucrose, 40g·L-1 D-mannitol and 2.5g·L-1 gellan gum under 24h illumination. The hybridity of germinated bulblets were confirmed before acclimatization by isozyme analysis. Hybrid plantlets were obtained from the crosses of L. longiflorum ‘LPI’ × BRO. After acclimatization and cultivation, 11 hybrid plants produced flowers changing from yellowish cream to white during anthesis as does the pollen parent. 

Những thông tin đầy đủ hơn về các vùng di truyền trong hệ gen sẽ là cơ sở cho việc nâng cao hiệu suất sử dụng đạm ở cây trồng. Mục đích của nghiên cứu này nhằm xác định các vùng di truyền trong hệ gen của lúa có liên quan đến hiệu suất sử dụng đạm  thông qua việc phân tích QTL  đối với các dòng thuần tái tổ hợp (RILs) từ hai dòng bố mẹ Azucena và IR64. 169 RILs và hai dòng bố mẹ được trồng trong cùng điều kiện môi trường trong phytotron với các mức bón đạm khác nhau. Thí nhiệm được lặpp lại hai lần riêng biệt. Phần mềm  WinQTL Cartographer version 2.5 được sử dụng trong việc phân tích QTL với từng thí nghiệm riêng biệt. Thí nghiệm thứ nhất xác định được 44 QTL cho 15 tính trạng theo dõi bao gồm: số lá (NL), số nhánh (NT), chiều cao cây (PH), tổng khối lượng chất tươi (FM), khối lượng rễ khô (DWR), khối lượng thân và cuống lá khô (DWS), khối lượng phiến lá khô (DWL), tổng khối lượng chất khô (DM), hàm lượng chlorophyll (CCI), hàm lượng N trong rễ (%NR), hàm lượng N trong thân và cuống lá (%NS), hàm lượng N trong phiến lá (%NL), hiệu suất sử dụng đạm hấp thụ (aNUE), hiệu suất sử dụng đạm sinh lý (pNUE), hiệu suất sử dụng đạm nông học (agNUE). Các QTL này nằm trên các nhiễm sắc thể 1, 2, 3, 4, 5, 6, 7, 8,10 và12. Thí nghiệm lặp lại thứ 2 xác định được 44 QTL cho các tính trạng: NL, NT, PH, FM, DWR, DWS, DWL, DM,CCI, %NR, %NL, aNUE và agNUE trên các nhiễm sắc thể 1, 2, 3, 5, 6, 7, 8 và 12.

Protocol for in vitro multiplication of Philodendrom xanadu was established including following steps: initial culture, shoot propagation and rooting of in vitro shoots and in vitro plantlet climatization. To create initial materials, apical buds were cultured on MS medium containing benzyl adenine (BA) or kinetin (KI). The results showed that MS medium supplemented with 4.0 mg/lmg/l BA was optimal for shoot multiplication The effect of the combination of cytokinin (BA) and auxin (IAA, IBA) on shoot multiplication of Philodendrom xanadu was also investigated. The results showed that addition of IAA or IBA on basal medium (MS medium containing 4.0 mg/l BA) did not increase multiplication rate. α-NAA or activated charcoal had positive impact on  in vitro shoot rooting. 1g/l activated charcoal-added MS medium was appropriate for root induction in terms of root number per shoot and average length of root after four weeks culture. After in vitro multiplication step, in vitro plantlets were transferred to greenhouse onto four different substrates. Survival percentage of plantlets was 100% on all substrates and acclimatized plantlets showed the best growth and development on mixture of coconut fiber and burnt rice husk (1:1).

This study was conducted to establish the protocol for in vitro propagation of papaya using stem segments. Results showed that double sterilization of explants with HgCl2 0.1% first  for 10 minutes and follwed by 5 minutes was most appropriate. MS medium containing 1 mg/l α-NAA+ 0,5 mg/l BA was optimal for callus induction (90.74%) of young stem slices after 4 weeks of culture. The highest shoot multiplication rate (3.17) was obtained on MS medium supplemented with 1.0 mg/l BA and 0.1 mg/l α- NAA after 4 weeks. Root induction medium was ½ MS containing 1.0 mg/l activated charcoal and 1.5 mg/l IBA. The average rooting percentage  was 50% within 4 weeks.

Biosensor was developed by design and construction of a reporter plasmid containing GFP gen under regulation of RNR2 promoter. This reporter plasmid was transformed in yeast cells which were then treated with different concentrations of MMS and menadione. Due to induction of genotoxic compounds, such as MMS, RNR2 promoter regulates transcription and translation of GFP leading to fluorescence signal measured at 485nm (excitation wave length) and 535nm (emission wave length). Fluorescence instensity was directly proportional to MMS concentrations when yeast cells treated with less than 1mM in the environment, but decreasing when exposed to higher MMS concentrations as a result of inhibition of cellular respiration and ATP synthesis. In contrast, promoter RNR2 was not induced by menadione resulting in no fluorescence signal. Thus, this kind of biosensor is able to not only determine and detect genotoxic chemical compounds, which are harmful to human and environment, but also identify new and uncharacterized compounds which possess the same chemical properties as MMS, and could be used in new drug discovery and drug screening.

b-Galactosidase (LacA) encoded by lacA gene from Bacillus subtilis G1 (Acession No EU585783) is a hydroltic enzyme that catalyzes the hydrolysis of lactose to produce lactose-free milk products. However, LacA has limited activity toward lactose. Therefore, we employed the method of site-saturation mutagenesis using PCR amplification with degenerate primers for generating mutants based on prediction of substrate binding sites to assess the effect of amino acids to the enzyme activity. Seven amino acid residues containing Arg120, Asn158, Trp331, Glu371, Lys372, Leu373 and His374 were identified as candidates for substrate binding sites using ExPASy program in Swiss-Prot. The screening results of the 7 libraries showed that these sites affect activity when ONPG was used as substrate. Most substitutions at these sites dramatically reduced the hydrolysis activity. Notably, 99.66% of colonies with Arg120 site showed  decrease in and loss of hydrolysis activity. The result suggested that Arg120 may play an important role in substrate recognition. Mutants at Arg120 substituted by Phe, Thr and Val showed complete loss of β-galactosidase activity.

 The study was conducted to establish the protocol for in vitro regeneration of common bean (Phaseolus vulgaris L.). Cotyledonary nodes excised from 7-day in vitro seedlings were used as primary explants. The optimum treatment for shoot induction was MS salts and B5 vitamins (MSB5) medium supplemented with 11.1µM BAP and 0.5µM α-NAA, where 86.7% of cotyledonary nodes induced shoots with an average of 3.1 shoots/explant after 4 weeks of culture. Elongated, well developed individual shoots with 3-6 leaves were transferred to rooting medium containing 4.9µM of IBA. The average rooting frequency was 53.3% with a mean of 1.7 roots/shoot after 4 weeks of culture. 80% rooted plantlets survived during acclimatization period in greenhouse.

In order to develop the new tomato varieties with delayed ripening and strong resistance to yellow leaf curl disease, evaluation and identification of the genetic resources bearing desirable genes play a very important role. In this study, 200 tomato accessions were evaluated for bio-agronomic characteristics, yield potential, delayed ripening ability and resistance to yellow leaf curl disease by artificial infection. Application of DNA markers was carried out to identify the resistant genes Ty1, Ty2, Ty3 and ripening inhibitor gene (rin) in 200 tomato accessions. Results indicated that seven tomato accessions carry resistance gene Ty1, 7 accessions contain Ty3 gene, of which 2 accessions carrying both Ty1 and Ty3 gene, and 6 accessions carry rin gene. Almost the accessions containing Ty1 and Ty3 were strongly resistant to the virus isolates collected from Hanoi, Bacgiang and Hungyen provines. We also found 15 accessions with slow ripening ability and long shelf life, in which 6 accessions containing ripening inhibitor gene (rin).

PIT-1, a regulatory transcription factor, plays a role in pituitary cell differentiation and proliferation and expression level of hormones in the anterior pituitary gland. The objective of present study was to identify the single nucleotide polymorphisms of PIT-1 gene and their association with milk yield in Holstein Friesian (HF) cows. Milk yield was recorded for the whole lactation period. PCR-RFLP technique was applied for genotyping of two SNPs belonging to exon 2 (E2) and exon 6 (E6) with restriction enzymes TaqI and HinfI. The analysis of 53 Holstein milking cows showed that genotypic frequencies of AA, AB and BB of PIT-1E2 were 45.3, 28.3 and 26.4%, respectively. For the PIT-1E6, the highest frequency of GG genotype (73.6%), the lowest frequency of genotype TT (7.5%) and TG genotype (18.9%) were found. Minitab software was used to analyze genotype - phenotype association. The result revealed that theere exists positive association between locus PIT-1E2 with milk yield (P= 0.037 and ρ = 0.28) and number of milking day (P=0.015 and r= 0.306), whereas, no association of PIT-1E6 was found (P>0.05). Cows with AA genotype yielded more milk than those with BB and AB genotypes. These finding showed the potential use of AA genotype of PIT-1E2 in assisting breeding for increased milk production of Holstein Friesian cows.

The apomixis phenomenon in citrus often leads to small, seedless and poor quality fruits. It is due to no or very less auxin is synthesized in the ovary leading to the abnormal development of embryo. Therefore, the fruits can not develop normally. Of many different strategies for seedless breeding in citrus such as outcrossing, triploidy, mutagenesis, the transfer of auxin-sensitive gene particularly expressed in ovary is a very useful approach. In this study, the vector pDU04.4522 carrying the auxin-sensitive gene (INO-rolB) working under the control of INO promoter was transferred into Duong Canh mandarine and Vinh orange. In order to identify the optimal conditions for gene transfer, four experiments focusing on the co-culture stage were carried out. Results showed that the auxin-sensitive gene INO-rolB was sucessfully transferred into the cotyledon of  Duong Canh tangerine and Vinh orange. The optimal conditions for  high efficiency of gene transfer in co-culture medium were at 22°C for 3 days in the presence of 50 - 100mM acetosyringone and 2 mg/l NAA.

Bacterial leaf blight disease caused by Xanthomonas oryzae pv. oryzae is one of the most severe diseases that causes yield loss in Vietnam. Possession of genetic resources with resistance plays an important role in developing durable resistant varieties. In this study, we used DNA markers Npb181, P3 and RG556 to identify Xa4, Xa7 and xa5 genes, respectively, in 120 local sticky rice accessions. We found that 95/120 accessions have the resistant genes, of these 4 varieties were identified to carry xa5 gene, 19 varieties were identified to carry xa4, gene 82 varieties with Xa7 gene, and 10 varieties with both Xa4 and Xa7 genes. Different genes resist to different number of bacterial strains. Two strains 4 and 5 are highly virulent, even causing disease on accessions containing the efective resistant genes (Xa4, xa5 or Xa7). 18 accessions that showed good esistance and high yield potential were selected. These materials can be used for rice breeding program with high yield  and bacterial leaf blight resistance.