Frictional resistance characteristics of a capsule inside the intestine for microendoscope design.

The design of the capsule body for a self-propelled endoscope is important from the frictional resistance point of view. The motivation of this work was to gain a better understanding of the effect of capsule shape on the frictional resistance of the capsule inside a small intestine. Special experimental set-ups were built to investigate the frictional resistance of the capsule and the viscoelastic deformation characteristics of the small intestine specimen of a pig. Tests were performed with capsules of various shapes and dimensions. Experimental data showed that a smooth cylindrical capsule geometry resulted in the least frictional resistance due to the shape and relatively small surface area. Also, it was found that the variation of frictional resistance of the capsule was closely related to the local change in the viscoelastic property of the intestine due to the heterogeneity of the internal structure of the intestine.

Controlling self-incompatibility by CO2 gas treatment in Brassica campestris: structural alteration of papillae cell and differential gene expression by increased CO2 gas.

Self-imcompatibility is a controlling genetic mechanism to prevent self-pollination for Chinese cabbage (Brassica campestris), one of the major vegetable crops in Korea. To maintain inbred lines of the crop plant, a method in that high CO2 gas is treated to the pistils to overcome the self-incompatibility and thereby self-pollens can successfully make germination and fertilization has been widely used in seed companies. Despite the common utilization of this method, any molecular and cellular studies on how the self-incompatibility is removed from the Chinese cabbage plant have not been done. In this study, we show that the increased CO2 gas causes a structural alteration of the papillae cell and thereby the self-incompatibility is removed from the Chinese cabbage plant, allowing the self-pollens to germinate and penetrate the papillae cell. Also, gene expression in the pistil treated with CO2 gas was studied by DD/RT-PCR and reverse northern hybridization experiments. The results suggest that the failure in self-incompatible reaction resulted not only from the structural alteration of the papillae cell but also from change in the pistil component production that is either positively or negatively regulated by the environmental stimulation.

Isolation and characterization of a class I SLG gene from Chinese cabbage (Brassica campestris).

In Brassica species, self-incompatibility in the recognition reaction between self and non-self pollens is determined by two genes, SLG and SRK, at the S locus. We have cloned and characterized a genomic DNA fragment containing a complete open reading frame of the SLG gene from Chinese cabbage. The genomic clone, named BcSLG2, was found to possess the region that shares a homology of 77% in amino acid identity with the SLG46 gene of Brassica campestris. Northern blot analysis revealed that the BcSLG2 gene expression is restricted to the pistil of Chinese cabbage flower. In situ hybridization showed that in the pistil, the gene is expressed predominantly in the stigmatic tissue. Much lower expression in the tapetum was also detectable at an immature stage of the flower development. Southern blot hybridization with the BcSLG2 DNA probe showed polymorphism in the SLG gene organization of the Chinese cabbage plants. These results will provide valuable information in understanding the S gene complex of the Chinese cabbage plants.