shi B. Sato

Toward memory-based translation

An essential problem of example-based translation is how to utilize more than one translation example for translating one source sentence.This paper proposes a method to solve this problem. We introduce the representation, called matching expression, which represents the combination of fragments of translation examples. The translation process consists of three steps: (1) Make the source matching expression from the source sentence. (2) Transfer the source matching expression into the target matching expression. (3) Construct the target sentence from the target matching expression.This mechanism generates some candidates of translation. To select the best translation out of them, we define the score of a translation.

Increased lipid rafts and accelerated lipopolysaccharide-induced tumor necrosis factor-α secretion in Abca1-deficient macrophages

Lipid rafts on the cell surface are believed to be very important as platforms for various cellular functions. The aim of this study was to know whether defective lipid efflux may influence lipid rafts on the cell surface and their related cellular functions. We investigated macrophages with defective lipid efflux from ATP binding cassette transporter A1-deficient (Abca1-KO) mice. Lipid rafts were evaluated by the following two novel probes: a biotinylated and protease (subtilisin Carlsberg)-nicked derivative of 𝛉-toxin and a fluorescein ester of polyethylene glycol-derived cholesterol. Lipid rafts in Abca1-KO macrophages were increased, as demonstrated by both probes. Moreover, activities of nuclear factor κB, mRNA and intracellular distribution, and secretion of tumor necrosis factor-α (TNF-α) were examined after stimulation by lipopolysaccharides (LPSs). LPS-induced responses of the activation of nuclear factor κB and TNF-α were more prompt and accelerated in the Abca1-KO macrophages compared with wild-type macrophages. Modification of lipid rafts by cyclodextrin and nystatin corrected the abnormal response, suggesting an association between the increased lipid rafts and abnormal TNF-α secretion. We report here that Abca1-KO macrophages with defective lipid efflux exhibited increased lipid rafts on the cell surface and accelerated TNF-α secretion.

Cinnamycin (Ro 09-0198) Promotes Cell Binding and Toxicity by Inducing Transbilayer Lipid Movement

Cinnamycin is a unique toxin in that its receptor, phosphatidylethanolamine (PE), resides in the inner layer of the plasma membrane. Little is known about how the toxin recognizes PE and causes cytotoxicity. We showed that cinnamycin induced transbilayer phospholipid movement in target cells that leads to the exposure of inner leaflet PE to the toxin. Model membrane studies revealed that cinnamycin induced transbilayer lipid movement in a PE concentration-dependent manner. Re-orientation of phospholipids was accompanied by an increase in the incidence of β-sheet structure in cinnamycin. When the surface concentration of PE was high, cinnamycin induced membrane re-organization such as membrane fusion and the alteration of membrane gross morphology. These results suggest that cinnamycin promotes its own binding to the cell and causes toxicity by inducing transbilayer lipid movement.

Eicosapentaenoic acid plays a beneficial role in membrane organization and cell division of a cold-adapted bacterium, Shewanella livingstonensis Ac10.

Shewanella livingstonensis Ac10, a psychrotrophic gram-negative bacterium isolated from Antarctic seawater, produces eicosapentaenoic acid (EPA) as a component of phospholipids at low temperatures. EPA constitutes about 5% of the total fatty acids of cells grown at 4 degrees C. We found that five genes, termed orf2, orf5, orf6, orf7, and orf8, are specifically required for the synthesis of EPA by targeted disruption of the respective genes. The mutants lacking EPA showed significant growth retardation at 4 degrees C but not at 18 degrees C. Supplementation of a synthetic phosphatidylethanolamine that contained EPA at the sn-2 position complemented the growth defect. The EPA-less mutant became filamentous, and multiple nucleoids were observed in a single cell at 4 degrees C, indicating that the mutant has a defect in cell division. Electron microscopy of the cells by high-pressure freezing and freeze-substitution revealed abnormal intracellular membranes in the EPA-less mutant at 4 degrees C. We also found that the amounts of several membrane proteins were affected by the depletion of EPA. While polyunsaturated fatty acids are often considered to increase the fluidity of the hydrophobic membrane core, diffusion of a small hydrophobic molecule, pyrene, in the cell membranes and large unilamellar vesicles prepared from the lipid extracts was very similar between the EPA-less mutant and the parental strain. These results suggest that EPA in S. livingstonensis Ac10 is not required for bulk bilayer fluidity but plays a beneficial role in membrane organization and cell division at low temperatures, possibly through specific interaction between EPA and proteins involved in these cellular processes.

CTM: an example-based translation aid system

This paper describes a Japanese-English translation aid system, CTM, which has a useful capability for flexible retrieval of texts from bilingual corpora or translation databases. Translation examples (pairs of a text and its translation equivalent) are very helpful for us to translate the similar text. Our character-based best match retrieval method can retrieve translation examples similar to the given input. This method has the following advantages: (1) this method accepts free-style translation examples, i.e., pairs of any text string and its translation equivalent, (2) morphological analysis is unneccessary, (3) this method accepts free-style inputs (i.e., any text strings) for retrieval. We show the retrieval examples with the following characteristic features: phrasal expression, long-distance dependency, idiom, synonym, and semantic ambiguity.

MBT2: a method for combining fragments of examples in example-based translation

Abstract Example-Based Translation is a new approach to machine translation. The basic idea of this approach is very simple: it is to translate a sentence by using translation examples of similar sentences. One of the major issues of Example-Based Translation is to study the utilization of more than one translation example when translating one source sentence. This paper proposes MBT2, which is a method of translating complete sentences by using multiple examples. The representation, matching expression , is introduced, which represents the combination of fragments of translation examples. The translation process of MBT2 consists of three stages: 1. (1) Making a source-matching expression from a source sentence. 2. (2) Transferring a source-matching expression into a target-matching expression. 3. (3) Constructing a target sentence from a target-matching expression. This mechanism generates several translation candidates and the score of a translation is defined to select the best translation out of them.

Dynamic clustering and dispersion of lipid rafts contribute to fusion competence of myogenic cells

Recent research indicates that the leading edge of lamellipodia of myogenic cells (myoblasts and myotubes) contains presumptive fusion sites, yet the mechanisms that render the plasma membrane fusion-competent remain largely unknown. Here we show that dynamic clustering and dispersion of lipid rafts contribute to both cell adhesion and plasma membrane union during myogenic cell fusion. Adhesion-complex proteins including M-cadherin, beta-catenin, and p120-catenin accumulated at the leading edge of lamellipodia, which contains the presumptive fusion sites of the plasma membrane, in a lipid raft-dependent fashion prior to cell contact. In addition, disruption of lipid rafts by cholesterol depletion directly prevented the membrane union of myogenic cell fusion. Time-lapse recording showed that lipid rafts were laterally dispersed from the center of the lamellipodia prior to membrane fusion. Adhesion proteins that had accumulated at lipid rafts were also removed from the presumptive fusion sites when lipid rafts were laterally dispersed. The resultant lipid raft- and adhesion complex-free area at the leading edge fused with the opposing plasma membrane. These results demonstrate a key role for dynamic clustering/dispersion of lipid rafts in establishing fusion-competent sites of the myogenic cell membrane, providing a novel mechanistic insight into the regulation of myogenic cell fusion.

Clathrin‐Dependent and Clathrin‐Independent Endocytosis are Differentially Sensitive to Insertion of Poly (Ethylene Glycol)‐Derivatized Cholesterol in the Plasma Membrane

We examined the effect of a cholesterol derivative, poly (ethylene glycol) cholesteryl ether on the structure/function of clathrin‐coated pits and caveolae. Addition of the compound to cultured cells induced progressive smoothening of the surface. Markedly, when the incorporated amount exceeded 10% equivalent of the surface area, fluid pinocytosis, but not endocytosis of transferrin, became inhibited in K562 cells. In A431 cells, both clathrin‐independent fluid phase uptake and the internalization of fluorescent cholera‐toxin B through caveolae were inhibited with concomitant flattening of caveolae. In contrast, clathrin‐mediated internalization of transferrin was not affected until the incorporated poly (ethylene glycol) cholesteryl ether exceeded 20% equivalent of the plasma membrane surface area, at which point opened clathrin‐coated pits accumulated. The cells were ruptured upon further addition of poly (ethylene glycol) cholesteryl ether. We propose that the primary reason for the differential effect of poly (ethylene glycol) cholesteryl ether is that the bulk membrane phase and caveolae are both more elastic than the rigid clathrin‐coated pits. We analyzed the results with the current mechanical model (Rauch and Farge, Biophys J 2000;78:3036–3047) and suggest here that the functional clathrin‐lattice is much stiffer than typical phospholipid bilayers.

Verb Paraphrase based on Case Frame Alignment

This paper describes a method of translating a predicate-argument structure of a verb into that of an equivalent verb, which is a core component of the dictionary-based paraphrasing. Our method grasps several usages of a headword and those of the def-heads as a form of their case frames and aligns those case frames, which means the acquisition of word sense disambiguation rules and the detection of the appropriate equivalent and case marker transformation.

Automatic Collection of Related Terms from the Web

This paper proposes a method of collecting a dozen terms that are closely related to a given seed term. The proposed method consists of three steps. The first step, compiling corpus step, collects texts that contain the given seed term by using search engines. The second step, automatic term recognition, extracts important terms from the corpus by using Nakagawas method. These extracted terms become the candidates for the final step. The final step, filtering step, removes inappropriate terms from the candidates based on search engine hits. An evaluation result shows that the precision of the method is 85%.