Yong Rhee

Gene expression changes in Arabidopsis seedlings during short- to long-term exposure to 3-D clinorotation

Seedlings of Arabidopsis thaliana (cv. Columbia) were used to evaluate dynamic transcriptional-level genome responses to simulated microgravity condition created by 3-D clinorotation. The DNA chip data analysis showed that the plant may respond to simulated microgravity by dynamic induction (up- and down-regulations) of the responsive genes in the genome. The qRT-PCR results on the investigated genes showed that the expression patterns of the genes (molecular response) were generally similar to the physiological response patterns detected in stress-challenged plants. Expression patterns were categorized into short or continual up- or down-regulated patterns, as well as stochastic changes from short- to long-term simulated microgravity stress. The induced genes are then assumed to establish a new molecular plasticity to the newly adjusted genome status in the basic milieu of maintaining homeostasis during the process of adaptation to simulated microgravity.

The Effect of Cucumber mosaic virus 2b Protein to Transient Expression and Transgene Silencing Mediated by Agro-infiltration

The transient and rapid expression system of a foreign protein in planta is a very useful technique in biotechnology application. We have investigated optimum condition of Agrobacterium-infiltration technique in which expression level of foreign proteins were maximized without detrimental effects on plants using GFP and Cucumber mosaic virus 2b protein, which is known as an enhancer of gene expression and a suppressor of post-transcriptional gene silencing(PTGS). The optimum expression level of both RNA and protein of GFP with minimum leaf impairment was obtained at

Identification of nickel response genes in abnormal early developments of sea urchin by differential display polymerase chain reaction.

Bioassays and biomarkers have been previously developed to assess the effects of heavy metal contaminants on the early life stages of the sea urchin. In this study, malformation in the early developmental processes was observed in sea urchin (Strongylocentrotus intermedius) larvae exposed to 10 ppm Ni for over 30 h. The most critical stage at which the triggering of nickel effects takes place is thought to be the blastula stage, which occurs after fertilization in larval development. To investigate the molecular-level responses of sea urchin exposed to heavy metal stress and to explore the differentially expressed genes that are induced or repressed by nickel, differential display polymerase chain reaction (DD-PCR) was used with sea urchin mRNAs. The malformation-related genes expressed in the early life stages of the sea urchin were cloned from larvae exposed to 10 ppm of nickel for 15 h, and accessed via DD-PCR. Sequence analysis results revealed that each of the genes evidenced high homology with EGF2, PCSK9, serine/threonine protein kinase, apolipophorin precursor protein, and MGC80921 protein/transcript variant 2. This result may prove useful in the development of novel biomarkers for the assessment of heavy metal stresses on sea urchin embryos.

Expression analysis of D-type cyclin in potato (Solanum tuberosum L.) under different culture conditions

Key messageTaken together, this study suggests that potato D-type cyclin genes are expressed differentially between in vitro and planta caused by intrinsic differences in physiology and gene action at the cellular and whole organism levels.AbstractCyclin performs a pivotal role in control of the cell cycle by forming a complex with cyclin-dependent kinases (CDKs). In this study, the potato cyclin D3 genes (StCycD3.1, StCycD3.2, and StCycD3.3) were isolated and analyzed. A sequence analysis showed that the potato cyclin D3 genes shared high levels of sequence homology with tomato cyclin D3 genes. The potato cyclin D3 genes revealed organ-specific expression; StCycD3.1 was strongly expressed in above-ground organs, whereas StCycD3.2 was strongly expressed in underground organs. The expression patterns of the potato cyclin D3 genes were analyzed under a variety of environmental conditions such as different carbon sources and hormones. Glucose (as a carbon source) and zeatin (as a hormone) were effective single factors for increasing potato cyclin D3 expression. Sucrose and zeatin were the most effective combination for high-level induction of the genes. Time-course-based gene expression patterns were evaluated in treatments of leaf explants with combinations of different light conditions and hormones. The potato cyclin D3 genes were expressed abundantly in the presence of hormones during the late stage of long-term dark conditions. The gene expression patterns were also monitored in entire potato plants under different light conditions. The gene expression levels were consistently low under the different light regimes but potato cyclin D3 genes were up-regulated during a shift in illumination from dark to light.

Expression of tissue-type plasminogen activator and its derivative proteins in transgenic alfalfa plants

Tissue-type plasminogen activator (t-PA) is a thrombolytic agent important in fibirn clot lysis. T-PA causes fibirn-specific plasminogen activation. Six binary vectors harboring t-PA and its derivative genes were cloned and expressed in transgenic alfalfa plants. The insertion of the t-PA and its derivative genes in genomic DNA of alfalfa plants was confirmed by PCR. The presence of the t-PA and its derivative transcripts in total RNAs of the transgenic alfalfa leaves was verified by RT-PCR. ELISA experiments demonstrated that the highest level of recombinant t-PA expression was / total soluble protein (mg) in alfalfa plants. The amount of recombinant t-PA and its derivative proteins in transgenic plants was estimated to range from 9.7 to / total soluble proteins (mg). Western blot analysis of the transformed alfalfa leaves revealed bands of approximately 68-kDa recombinant t-PA and its derivative proteins. The fibrinolysis of recombinant t-PA and its derivative proteins was confirmed by a fibrin plate assay (range from 3.2 to 8.1 cm). The results presented provide information for the development of an additional production of recombinant human proteins having pharmaceutical applications using transgenic plants.