Initiator tRNAs are used exclusively for initiation of protein synthesis and not for elongation. We show that both Escherichia coli and eukaryotic initiator tRNAs have negative determinants, at the same positions, that block their activity in elongation. The primary negative determinant in E. coli initiator tRNA is the C1xA72 mismatch at the end of the acceptor stem. The primary negative determ...

A new protocol for carcinogenesis in rat liver is described in order that confirmatory experiments might be undertaken concurrently. The basic protocol, designated IPI (initiator + promoter + initiator), is presented in several alternative forms, including the possible use of X-irradiation as the initiator. The rationale is discussed in terms of the two-hit somatic mutation theory of Armitage a...

Commercial initiator – 2,2-dimethoxy-2-phenyl acetophenone (Irgacure 651, Ciba, Switzerland) was introduced to poly(methyl methacrylate) (PMMA) matrix to enhance the polymer degradation. Two types of thin polymeric films (PMMA and PMMA+5% Irgacure) were UV-irradiated in laboratory conditions (Xenon lamp, air atmosphere, room temperature). The photochemical changes in pure PMMA and PMMA doped wi...

In prokaryotes, many of the physical mechanisms governing the process of initiating DNA replication are now emerging. For example, certain organizational features of origins, such as the use of repetitive sequence elements for initiator-binding sites, are found throughout bacteria and many archaea. Common themes in the regulation of initiation, including origin sequestration by trans-acting fac...

Transcription associated with a terminal deoxynucleotide transferase gene initiator element is shown to respond to the transcription factor GAL4-VP16 both in vivo and in vitro. High-level transcription requires both an intact initiator element and bound activator. Transcription from this initiator-directed promoter is synergistic in vivo in that five GAL4 DNA binding sites yield 36 times the ex...

styrene polymerization through frp and atrp methods was carried out at 110oc, while in-depth studies were performed by monte carlo simulation.the changes in monomer conversion, initiator concentration, average molecular weight, and polydispersity index were computed over the course of the polymerization. as the results indicate, compared to atrp, the frp reaches higher conversion in a similar r...

Mixed-initiative in dialogue does not mean that either speaker is free to take the lead in the conversation at any time. Rather, who can show initiative, and when, is restricted. In this paper, we define initiative and control as two levels of dialogue phenomena, and give further evidence for our theory of restricted initiative that control belongs to the initiator of a discourse segment. We sh...