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1.
A respiration-deficient (RD) mutant was isolated from the petite-negative, salt-tolerant yeast Zygosaccharomyces rouxii. One strain among sixteen glycerol-non-utilizing mutants exhibited vigorous liberation of CO2 but no uptake of O2. Furthermore, this strain lacked cytochrome aa3 and had a reduced level of cytochrome b. The few mitochondria found in cells of this strain contained few or no cristae. Salt tolerance and intracellular accumulation of glycerol by the RD strain were almost equal to that of the wild-type strain in media containing NaCl up to 2.5 M. In media with more than 3 M NaCl, the growth of the RD mutant was retarded and the intracellular accumulation of glycerol was depressed in spite of ample production.  相似文献   
2.
Development of female flowers in Zelkova serrata was observed using epi-illuminated microscopy and scanning electron microscopy, with particular attention given to placentation. After the inception of staminodial primordia, the floral apex becomes flat, and the first and subsequently the second carpel primordia appear at opposite comers of the pistil primordium. Inside each carpel primordium a fossette forms. Through differential growth this depression becomes clear and the carpel wall encircles one side of the future placental region. The placental region is detectable even in early stages, but clear signs of ovule inception appear late when the placental region is elevated onto one side of the ovary wall by intercalary growth. Although the relative size of the two carpels varies among flowers, the placental position always appears to be the border between the two carpels and the floral apex. This suggests that the placentation of Zelkova is parietal. The ovule position in tricarpellate ovaries also suggests an evolutionary derivation from ovaries with parietal placentation. Parietal placentation appears to be the original condition in Urticales.  相似文献   
3.
Cells from a mouse B lymphoma were transfected by DQ alpha and DQ beta genes derived from a DR4 haplotype. Quantitatively, the resulting expression of human class II molecules was similar to that of human B lymphoblastoid cell lines. Qualitatively, the transformant class II molecules differed from normal class II molecules in their carbohydrate moiety. As for their antigenic specificity, they were shown to carry two determinants previously identified on DQ molecules controlled by DR4 haplotypes, i. e., DQw3 and DCHON. The transformant molecules did not carry a third DR4-associated specificity, DC5 (equivalent to TA10), and must possess a structure allelic to DC5. However, no corresponding alloantigenic specificity was detected by a screening of relevant alloantisera.  相似文献   
4.
Summary An alkalophilic bacterium producing high amounts of the cell-associated -mannosidase and extracellular -mannanase was isolated from soil. The isolate (AM-001) that grew well in alkaline pH media was identified as a strain of Bacillus sp. The optimal cultivation temperature for enzyme production was 31° C for -mannosidase and 37° C for -mannanase with the optimum production medium composed of 1% konjac powder, 0.2% yeast extract, 2% Polypepton, 0.1% K2HPO4, 0.02% MgSO4 · 7H2O and 0.5% Na2CO3. Optimum pH and temperature for -mannosidase were 7.0 and 55° C, and for -mannanase were 9.0 and 65° C.  相似文献   
5.
Abstract: Incubation of rat pheochromocytoma PC12 cells with 4β-phorbol-12β-myristate-13α-acetate (PMA), an activator of Ca2+/phospholipid-dependent protein kinase (protein kinase C), or forskolin, an activator of adenylate cyclase, is associated with increased activity and enhanced phosphorylation of tyrosine hydroxylase. Neither the activation nor increased phosphorylation of tyrosine hydroxylase produced by PMA is dependent on extracellular Ca2+. Both activation and phosphorylation of the enzyme by PMA are inhibited by pretreatment of the cells with trifluo-perazine (TFP). Treatment of PC 12 cells with l-oleoyl-2-acetylglycerol also leads to increases in the phosphorylation and enzymatic activity of tyrosine hydroxylase; 1, 2-diolein and 1, 3-diolein are ineffective. The effects of forskolin on the activation and phosphorylation of the enzyme are independent of Ca2+ and are not inhibited by TIT5. Forskolin elicits an increase in cyclic AMP levels in PC 12 cells. The increases in both cyclic AMP content and the enzymatic activity and phosphorylation of tyrosine hydroxylase following exposure of PC 12 cells to different concentrations of forskolin are closely correlated. In contrast, cyclic AMP levels do not increase in cells treated with PMA. Tryptic digestion of the phosphorylated enzyme isolated from untreated cells yields four phosphopeptides separable by HPLC. Incubation of the cells in the presence of the Ca2+ ionophore ionomycin increases the phosphorylation of three of these tryptic peptides. However, in cells treated with either PMA or forskolin, there is an increase in the phosphorylation of only one of these peptides derived from tyrosine hydroxylase. The peptide phosphorylated in PMA-treated cells is different from that phosphorylated in forskolin-treated cells. The latter peptide is identical to the peptide phosphorylated in dibutyryl cyclic AMP-treated cells. These results indicate that tyrosine hydroxylase is activated and phosphorylated on different sites in PC 12 cells exposed to PMA and forskolin and that phosphorylation of either of these sites is associated with activation of tyrosine hydroxylase. The results further suggest that cyclic AMP-dependent and Ca2+/ phospholipid-dependent protein kinases may play a role in the regulation of tyrosine hydroxylase in PC 12 cells.  相似文献   
6.
7.
Mutagenesis of human granulocyte colony stimulating factor   总被引:9,自引:0,他引:9  
To define the structure-function relationship, we have made a number of mutants of human granulocyte colony-stimulating factor (hG-CSF) by in vitro mutagenesis. The results indicate that most of the mutations located in the internal and C-terminal regions of the molecule abolished the activity, whereas the mutants without N-terminal 4, 5, 7, or 11 amino acids retained the activity. N-terminal amino acids were also altered by cassette mutagenesis using a synthetic oligonucleotide mixture. Among them, KW2228, in which Thr-1, Leu-3, Gly-4, Pro-5 and Cys-17 were respectively substituted with Ala, Thr, Tyr, Arg and Ser, showed more potent granulopoietic activity than that of intact hG-CSF both in vitro and in vivo.  相似文献   
8.
The 35-year-old man with myelodysplastic syndrome (MDS) and granulocytopenia with dry cough and high fever was eventually found to have a left perinephric abscess ofStaphylococcus aureus. He underwent left nephrectomy and drainage of perinephric space in conjunction with appropriate antibiotics. However, because of persistent granulocytopenia,Staph. aureus never cleared up with formation of only poor granulation. Recombinant human granulocyte colony-stimulating factor (G-CSF) was added to the above treatment leading to prompt improvement in granulocytopenia and emergence of the good granulation tissue. G-CSF will probably become one of the important agents in treating MDS with granulocytopenia.  相似文献   
9.
HLA class 11 molecules were isolated from mouse L cells transfected with a DR gene and an allele, 52a, of locus DR III from an HLA-homozygous cell line, AVL, of the DR3 haplotype. The isolated molecules were found to possess a new allospecificity, named TR81. This specificity behaved allelic to the previously described DR III locus. The TR81 specificity was also present on the DR I gene product of the DR3 haplotype. The nucleotide sequence of the gene encoding TR81 differs from TR81-negative DR genes of the DRw52 family in only two codons, both located in the regions known to be involved in a gene conversion event. Consequently, the following conclusions can be formulated. (a) TR81 is a bi-locus specificity and allelic to TR22 only in its DR III locus localization. (b) The TR81 specificity is the phenotypic counterpart of the gene conversion event which led to the generation of the DR I gene of the DR3 haplotype. (c) One or both individual amino acid substitutions in the first domain of the DR chain are responsible for the TR81 allospecificity. (d) Since TR81 is expressed on the DR I chain of the DR3 haplotype, it is possible that TR81 and DR3 represent the same serological specificity.  相似文献   
10.
Chitinase activity was induced in cultured carrot cells by incubationwith mycelial walls of a fungus, Chaetomium globosum. Both intra-and extracellular chitinases were resolved into four componentsby gel filtration chromatography. The extracellular enzymesliberated soluble oligosaccharides of different sizes from insolublechitin, suggesting that these carrot chitinases are endo-hydrolases.The solubilized chitinase digests obtained from insoluble mycelialwalls of C. globosum and chitin were fractionated by gel filtrationchromatography, and the elicitor activity of each fraction forthe accumulation of phenolic acids in cultured carrot cellswas determined. In both solubilized fragments of fungal wallsand of chitin, elicitor-active oligosaccharides were distributedin many fractions, however, potent activity for inducing phenolicacid synthesis was observed in the high molecular weight fractions. (Received October 5, 1987; Accepted February 12, 1988)  相似文献   
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