DELETION AND INACTIVATION OF RETINOBLASTOMA SUSCEPTIBILITY GENE IN PRIMARY RETINOBLASTOMA

The status and expression of Rb gene was detected and analyzed in 19 surgical retinoblastoma specimens using Rb cDNA 3. 8 kb and 0. 9 kb fragment as probe and antibodies specific for synthetic Rb peptide or expressive product of Rb gene expression plasmld. DNA from those tumors had the hemlzygous deletion in 3 cases, the homozygous internal deletion In 2 cases and alterated restriction fragment involving In one copy of Rb gene In 1 case. The quantity of Rb protein demonstrated either absence of reduction in all the 16 cases examined In comparison with that in normal adult retina. It suggested that there were structural or/ and functional defects of Rb gene In retinoblastoma cells and provided evidence to support Knudson' s two hit hypothesis.

Resistance identification of bivalent fungi-resistant genes transformed soybean to Phytophthora sojae

Soybean is one of the most important sources of edible oil and proteins in the world. However, it suffers from many kinds of fungal diseases which is a major limiting factor in soybean production. The fungal disease can be effectively controlled by breeding plant cultivars with genetic transformation. In this study, the resistance to Phytophthora sojae of five bivalent transgenic soybean lines was identified using the hypocotyls inoculation technique. The lines were the T2 of the transgenic soybean which were transformed with kidney bean chitinase gene and barley ribosome inactivating protein gene, and were positive by Southern Blot analysis. The resistance difference was studied through comparing the death percentage of transgenic soybean with the control. The results showed that four lines were more resistant to P sojae, whereas other one had no significant difference in comparison with the control. These transgenic soybean lines with enhanced resistance to P sojae will be useful in soybean resistance breeding.

Strategies used for genetically modifying bacterial genome: site-directed mutagenesis, gene inactivation, and gene over-expression

With the availability of the whole genome sequence of Escherichia coli or Corynebacterium glutamicum, strategies for directed DNA manipulation have developed rapidly. DNA manipulation plays an important role in understanding the function of genes and in constructing novel engineering bacteria according to requirement. DNA manipulation involves modifying the autologous genes and expressing the heterogenous genes. Two alternative approaches, using electroporation linear DNA or recombinant suicide plasmid, allow a wide variety of DNA manipulation. However, the over-expression of the desired gene is generally executed via plasmid-mediation. The current review summarizes the common strategies used for genetically modifying E. coli and C. glutamicum genomes, and discusses the technical problem of multi-layered DNA manipulation. Strategies for gene over-expression via integrating into genome are proposed. This review is intended to be an accessible introduction to DNA manipulation within the bacterial genome for novices and a source of the latest experimental information for experienced investigators.

Post-transcriptional Gene Silencing Induced by Short Interfering RNAs in Cultured Transgenic Plant Cells

Short interfering RNA (siRNA) is widely used for studyingpost-transcriptional gene silencing and holds great promise as a tool for both identifying functionof novel genes and validating drug targets. Two siRNA fragments (siRNA-a and -b), which weredesigned against different specific areas of coding region of the same target green fluorescentprotein (GFP) gene, were used to silence GFP expression in cultured gfp transgenic cells of rice(Oryza sativa L.; OS), cotton (Gossypium hirsutum L.; GH), Eraser fir [Abies fraseri (Pursh) Poir;AF], and Virginia pine (Pinus virginiana Mill.; PV). Differential gene silencing was observed in thebombarded transgenic cells between two siRNAs, and these results were consistent with theinactivation of GFP confirmed by laser scanning microscopy, Northern blot, and siRNA analysis intested transgenic cell cultures. These data suggest that siRNA-mediated gene inactivation can be thesiRNA specific in different plant species. These results indicate that siRNA is a highly specifictool for targeted gene knockdown and for establishing siRNA-mediated gene silencing, which could bea reliable approach for large-scale screening of gene function and drug target validation.