Study on the Translation Initiation Mechanism on Picornaviral RNA.

To understand the initiation of translation of picornavirus RNA, cell-free translation of the RNA of encephalomyocarditis virus (EMCV) was examined after hybridization of chemically synthesized cDNA fragments to different sites of the 5\sp\prime untranslated region (5\sp\prime UTR) of the viral RNA and after deletion of specific segments of the 5\sp\prime UTR by RNase H digestion. In addition, translation competition experiments, using RNA fragments derived from different parts of the 5\sp\prime UTR, were performed. The results of these experiments are summarized as follows: (i) Binding of cDNA fragments to sequences between the 5\sp\prime terminus and nucleotide 338 caused no effect on translation of the viral RNA; (ii) binding of cDNA fragments to the sequence between nucleotides 420 and 449 caused a slight inhibition; (iii) binding of fragments to sites between nucleotides 450 and the initiator AUG codon (nucleotide 834) caused strong inhibition; (iv) deletion from the 5\sp\prime terminus to nucleotide 338 caused no effect on translation of the coding region of the RNA, whereas deletion from the 5\sp\prime terminus to nucleotide 450 or beyond totally abolished translation of the coding region; and (v) presence of a 5\sp\prime fragment (from 5\sp\prime terminus to approximate nucleotide 338) caused no effect on translation of EMCV RNA, but presence of either of two other fragments, one from approximately nucleotides 338 to 589, the second from approximately nucleotides 338 to 813, caused inhibition of translation. These results together indicate that the first part of the 5\sp\prime UTR, at least to nucleotide 338, is not required for EMCV RNA translation but the sequence near, and possibly also sequences beyond nucleotide 450 are critical for translation of the viral RNA. For the purpose of future more detailed analysis of the sequence elements that are important for translational initiation, cDNAs corresponding to the 5\sp\prime UTR and a beginning portion of the viral protein coding region of the viral RNA were synthesized and cloned, and two sets of sequential deletion mutants were constructed from the cloned cDNA. Results from an initial in vitro translation study of the synthetic mRNAs from some of these deletion clones are presented

Development of KAISTSAT-4 Expanding the Role of Small Satellite for Scientific Research

The fourth Korean small satellite, KAISTSAT-4, is under development by Satellite Technology Research Center (SaTReC) of the Korea Advanced Institute of Science and Technology (KAIST). The KAISTSAT-4 program was commenced on October 1998 with multiple mission objectives, which include exploring space science, deploying satellite-based data collection system and development of precision star sensor. Despite severe constraints on mass and size, these advanced science and engineering payloads are expected to deliver various useful results and exhibit the unique role of small satellite. We present an overview of the KAISTSAT-4 mission and describe its current status. Finally the prospect of future small satellite programs is briefly introduced