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Articles by M Yanagida
Total Records ( 4 ) for M Yanagida
  D. V Irvine , D. B Goto , M. W Vaughn , Y Nakaseko , W. R McCombie , M Yanagida and R. Martienssen
 

Fission yeast is an important model for epigenetic studies due to the ease with which genetic mutants can be isolated. However, it can be difficult to complement epigenetic phenotypes with genomic libraries in order to identify the genes responsible. This is because epigenetic phenotypes are typically unstable, and can prohibit complementation if silencing cannot be reestablished. Here we have resequenced the fission yeast genome following mutagenesis to readily identify a novel mutant involved in heterochromatic silencing. Candidate genes were identified as functional single base changes linked to the mutation, which were then reconstituted in a wild-type strain to recapitulate the mutant phenotype. By this procedure we identified a weak allele of ubc4, which encodes an essential E2 ubiquitin ligase, as responsible for the swi*603 mutant phenotype. In combination with a large collection of mutants and suppressor plasmids, next-generation genomic resequencing promises to dramatically enhance the power of yeast genetics, permitting the isolation of subtle alleles of essential genes, alleles with quantitative effects, and enhancers and suppressors of heterochromatic silencing.

  Y Kushi , H Kamimiya , H Hiratsuka , H Nozaki , H Fukui , M Yanagida , M Hashimoto , K Nakamura , S Watarai , T Kasama , H Kajiwara and T. Yamamoto
 

Bacterial sialyltransferases (STs) from marine sources were characterized using glycosphingolipids (GSLs). Bacterial STs were found to be β-galacotoside STs. There were two types of STs: (1) ST obtained from strains such as ishi-224, 05JTC1 (#1), ishi-467, 05JTD2 (#2), and faj-16, 05JTE1 (#3), which form 2-3 sialic acid (Sia) linkages, named 2-3ST, (2) ST obtained from strains such as ISH-224, N1C0 (#4), pda-rec, 05JTB2 (#5), and pda-0160, 05JTA2 (#6), which form 2-6 Sia linkages, named 2-6ST. All STs showed affinity to neolacto- and lacto-series GSLs, particularly in neolactotetraosyl ceramide (nLc4Cer). No large differences were observed in the pH and temperature profiles of enzyme activities. Kinetic parameters obtained by Lineweaver–Burk plot analysis showed that #3 and #4 STs had practical synthetic activity and thus it became easily possible to achieve large-scale ganglioside synthesis (100–300 µM) using these recombinant enzymes. Gangliosides synthesized from nLc4Cer by 2-3 and 2-6STs were structurally characterized by several analytical and immunological methods, and they were identified as IV3NeuAc-nLc4Cer(S2-3PG) and IV6NeuAc-nLc4Cer (S2-6PG), respectively. Further characterization of these STs using lactotetraosylceramide (Lc4Cer), neolactohexaosylceramide (i antigen), and IV6kladoLc8Cer (I antigen) showed the synthesis of corresponding gangliosides as well. Synthesized gangliosides showed binding activity to the influenza A virus [A/panama/2007/99 (H3N2)] at a similar level to purified S2-3PG and S2-6PG from mammalian sources. The above evidence suggests that these STs have unique features, including substrate specificities restricted to lacto- and neolactoseries GSLs, as well as catalytic potentials for ganglioside synthesis. This demonstrates that efficient in vitro ganglioside synthesis could be a valuable tool for selectively synthesizing Sias modifications, thereby permitting the exploration of unknown functions.

  H Nozaki , M Yanagida , K. i Koide , K Shiotani , M Kinoshita , Y Kobayashi , S Watarai , K Nakamura , A Suzuki , T Ariga and Y. Kushi
 

We have established hybridoma cell lines producing monoclonal antibodies (mAbs) directed to N-acetylglucosaminylβ1-3galactose (GlcNAcβ1-3Gal) residue by immunizing BALB/c mice with lactotriaosylceramide (Lc3Cer). These obtained hybridoma cells, specific to Lc3Cer, were dual immunoglobulin (Ig)-producing cells which secreted both IgM and IgG molecules as antibodies. The established mAbs are able to react with not only Lc3Cer but also GlcNAcβ1-3-terminal glycosphingolipids (GSLs) despite branching or lactosamine chain lengths and human transferrin with terminal GlcNAc residues. Comparison of the variable regions of the cloned IgM and IgG by reversed transcription-polymerase chain reaction analysis confirmed that the variable regions determine the specificity, the other amino acids are conserved, and these mAbs are encoded by J558 and V-21family genes. Furthermore, we have analyzed the expression of GSLs with GlcNAcβ1-3 epitope in acute leukemia cell lines and mouse fetal tissues using these mAbs, in which antigens were distributed comparatively. These mAbs are useful for studying the precise distribution of GlcNAcβ1-3Gal-terminating GSL expression in tissues as well as for detecting GSLs carrying terminal GlcNAcβ1-3Gal carbohydrate structure.

  V. A Tallada , K Tanaka , M Yanagida and I. M. Hagan
 

The fission yeast spindle pole body (SPB) comprises a cytoplasmic structure that is separated from an ill-defined nuclear component by the nuclear envelope. Upon mitotic commitment, the nuclear envelope separating these domains disperses as the two SPBs integrate into a hole that forms in the nuclear envelope. The SPB component Cut12 is linked to cell cycle control, as dominant cut12.s11 mutations suppress the mitotic commitment defect of cdc25.22 cells and elevated Cdc25 levels suppress the monopolar spindle phenotype of cut12.1 loss of function mutations. We show that the cut12.1 monopolar phenotype arises from a failure to activate and integrate the new SPB into the nuclear envelope. The activation of the old SPB was frequently delayed, and its integration into the nuclear envelope was defective, resulting in leakage of the nucleoplasm into the cytoplasm through large gaps in the nuclear envelope. We propose that these activation/integration defects arise from a local deficiency in mitosis-promoting factor activation at the new SPB.

 
 
 
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