Isolating cDNA clones from rice induced by Magnaporthe grisea using PCR based differential screening method

The differential hybridization technique hasbeen widely used to identify genes that are dif-ferentially expressed.However,this approachhas several drawbacks.First,the screeningprocedures are rather labor-intensive and time-consuming.Second,the amount of phageDNAs transferred onto the two filters may notbe equivalent,which leads to an inaccurate se-lection of a positive clone.Third,isolation ofphage DNA is slow and cumbersome.Here,aPCR based differential screening method that

Primarily screening and analyzing ESTs differentially expressed in rats' primary liver cancer

Objective： To screen and analyze key express sequence tags （ESTs） which were differentially displayed in every period of SD rats＇ primary hepatic carcinoma and reveal the molecular mechanism of carcinogenesis. Methods： Using diethylnitrosamine （DENA） as a cancerigenic agent, animal models with different phases of primary hepatic cancer were constructed in SD rats. Rats were respectively sacrificed at d 14, d 28, d 56, d 77, d 105 and d 112 after the rats received DENA by gavage, then the livers were harvested. One part of the livers was classified according to their pathological changes, while the other was reserved for molecular mechanism studies on hepatocarcinogenesis. The differentially expressed genes were isolated from both normal and morbid tissues by mRNA differential display technique （DDRT-PCR）. After the fragments were sequenced, bioinformatics were .used to analyze the results. Results： Twelve differentially expressed cDNA fragments were obtained. Nine fragments had the homology with known cDNA clones, especially EST-7 was similar to BN/SsNHsdMCW mitochondrion gene and the identity was 100% which suggested EST-7 may be the part of BN/SsNHsdMCW mitochondrion gene. In contrast, other three fragments （EST-1, EST-3 and EST-5） had extremely low identity to any genes registered in GENBANK databases. Conclusions： BN/SsNHsdMCW mitochondrion gene was expressed in different periods of hepatocarcinogenesis. Moreover, EST-I, EST-3 and EST-5 were suggested to contribute to the development of rat hepatocarcinogenesis, and thus may be candidates of new targets of oncogenes or cancer suppressor genes.

Differential Gene and Protein Expression in Soybean at Early Stages of Incompatible Interaction with Phytophthora sojae

Soybean root and stem rot caused by Phytophthora sojae is a destructive disease worldwide. Using genetic resistance is an important and major component in the integrated pest management of this disease. To understand molecular mechanisms of root and stem rot resistance in soybeans, the gene and protein expression in hypocotyls and stems of variety Suinong 10 carrying resistance genes Rps1a and Rps2 was investigated by using mRNA differential display reverse transcription PCR and two-dimensional electrophoresis at 0, 0.5, 1, 2, and 4 h after inoculation with P. sojae race 1. The results of the comparison of gene and protein expression showed that at least eight differential fragments at the transcriptional level were related to metabolic pathway, phytoalexin, and signal transduction in defense responses. Sequence analyses indicated that these fragments represented cinnamic acid 4-hydroxylase gene, ATP b gene coding ATP synthase b subunit and ubiquitin-conjugating enzyme gene which upregulated at 0.5 h post inoculation, blue copper protein gene and UDP-N-acetyl-a-D-galactosamine gene which upregulated at 2 h post inoculation, TGA-type basic leucine zipper protein TGA1.1 gene, cyclophilin gene, and 14-3-3 protein gene which upregulated at 4 h post inoculation. Three resistance-related proteins, a-subunit and b-subunit of ATP synthase, and cytochrome P450-like protein, were upregulated at 2 h post inoculation. The results suggested that resistance-related multiple proteins and genes were expressed in the recognition between soybean and P. sojae during zoospore germination, penetration and mycelium growth of P. sojae in soybean.

mRNA differential display on gene expression in settlement metamorphosis process of Ruditapes philippinarum larvae

The mRNA differential display (DDRT-PCR) technique was adopted to find out the genes related tosettlement metamorphosis development process of Ruditapes philippinarum larvae.In this study,we haveobtained three hundred and forty-six amplification bands in total from pediveliger larvae,veliger larvae,eye spot larvae and post-larvae.Sixty-five out of three hundred and forty-six bands are distinctly differen-tial display from band pattern,which can be put into four groups,standing for different expression char-acters.Sixteen differential display bands were cloned,sequenced and analyzed and nine different se-quences are obtained in the study.Three sequences have higher similarity to the cDNAs deposited indatabase and three are very similar to the rDNA of other species,considered as the rDNA of Ruditapesphilippinarum.The rest three sequences are found to be novel sequences after analyzed.Their accessionnumbers are AY916799,AY916798,and AY916797 respectively.We thought the novel sequences arepossibly relevant to the early embryo development of Ruditapes philippinarum larvae and can provide somefundamental understandings that are helpful for the improvement of scallop seed raising industry.

Inducible Expression of Translation Elongation Factor 1A Gene in Rice Seedlings in Response to Environmental Stresses

Differences of gene expression between salinity_stressed and control rice ( Oryza sativa L. ssp. indica ) cultivar “Zhaiyeqing 8' were compared using differential display PCR (DD_PCR) technique. Sequence analysis of one salt_inducible cDNA clone revealed that this clone represented a new member of rice translation elongation factor 1A (eEF1A) gene family and was tentatively named REF1A. Northern blot hybridization using REF1A fragment as a probe was performed to investigate the expression of rice translation elongation factor 1A gene in response to various environmental factors. It was observed that expression of the eEF1A gene in rice shoots was dramatically induced by salinity stress or exogenous application of abscisic acid (ABA). The induction of this gene by ABA stress occurred more quickly than that by salinity stress. In addition, expression of rice translation elongation factor 1A gene was also induced by drought (15% PEG6000), cold (4 ℃) or heat_shock (37 ℃) stresses. The results suggested that the induction of translation elongation factor 1A gene expression by environmental stresses might reflect the general adaptive response of rice plants to the adverse circumstances.

Effect of Epinephrine on the Settlement and Metamorphosis of Manila Clam Larvae

Chemical inducement and DDRT-PCR （differential display reverse transcription PCR） are adopted to investigate the effect of epinephrine （EPI） on the settlement and metamorphosis of Manila clam larvae. Chemical inducement shows that EPI has an effect to some extent on the metamorphosis of Manila clam larvae at all concentrations and in all treatments designed. The most significant result of inducement is obtained at the concentration of 10^-6 tool L^-1 and for 4 h. DDRT-PCR using six primer pairs shows that the gene expression pattern is quite different between EPI treatment and the control. Three hundred and forty-three amplification bands are obtained in total, among which, 67 （19.53%） are differentially appeared. Therefore, EPI has an effect on the gene expression of the eye spot larval Manila clam. It can be hypothesized that EPI is a settlement and metamorphosis inducer for Manila clam. EPI may lead to larvae settlement and metamorphosis by binding to the receptors on the membrane and then changing the gene expression of larvae cells.

RAPID DETECTION OF ONCOGENE AMPLIFICATION IN PARAFFIN SECTIONS OF BREAST CARCINOMAS USING QUANTITATIVE DIFFERENTIAL PCR AND FLUORESCENT DNA TECHNOLOGY

Gene amplification is a common mechanism of oncogene activation and contributes to tumor progression. Analysis of such genetic alterations are relevant to the understanding of tumor genetics and could provide prognostic information for the individual patient. Standard analytical approaches using Southern blot and slot blot require a large amount of good

Differential Display of Cotton cDNAs Expressed by Salicylic Acid Induction

Salicylic acid (SA) is very important in systemic acquired resistance and hypersensitive response in plant defense, and yet its role is not fully understood. This study seeks to clarify the mechanism of SA induced resistance in cotton. Total RNA was extracted from low gossypol cultivated cotton seedlings treated with exogenous SA and subjected to fluorescent differential display PCR (FDD PCR). Seven cDNA fragments were selected from the total ten differential bands. Comparison with Genbank database shows that all seven cDNA sequences are newly discovered in cotton. However, they share high amino acid identity to some registered cDNAs. Among them, three of the cDNAs could be predicted to encode basic chitinase, penicillin binding 6 b precursor and ATP dependent DNA helicase RecG, while the functions of the other four cDNAs are undetermined. Dot blot analysis demonstrates that the expression of five cDNAs in cotton seedlings is induced by SA, while SA induction has a negative effect on the transcript accumulation of the other two cDNAs (E13 and E14). Since SA was previously shown to enhance the resistance to cotton wilt disease, the finding of a basic chitinase gene in cotton expressed by SA induction will provide a new insight into induced disease resistance in cotton.