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61.
Two different single nucleotide transitions of hypoxanthine-guanine phosphoribosyltransferase (HPRT) were identified in a Japanese patient with Lesch-Nyhan syndrome (LNS) and a patient with hereditary gout. HPRT enzyme activities in the two patients were severely deficient, but the size and amount of mRNA were normal according to Northern analysis. Entire coding regions of HPRT cDNAs were amplified by PCR and sequenced. A G-to-A substitution at base 208 in exon 3, which predicted glycine 70 to arginine, was detected in the LNS patient (identical mutation with HPRTUtrecht). A C-to-A substitution at base 73 in exon 2, which predicted proline 25 to threonine, was detected in the gout patient (designated HPRTYonago). We transfected normal HPRT cDNA, mutant cDNA with HRPTUtrecht or mutant cDNA with HPRTYonago, respectively, to HPRT-deficient mouse cells and isolated permanent expression cell lines. The HPRT-deficient mouse cells had no detectable HPRT activity and a very low amount of HPRT mRNA. When the HPRT-deficient mouse cells were transfected with normal human cDNA, HPRT enzyme activity increased to 21.8% that of normal mouse cells. The mouse cells transfected with HPRTUtrecht showed no increase in HPRT activity; however, when the mouse cells were transfected with HPRTYonago, the activity increased to 2.4% that of normal activity. The proliferative phenotypes of these cells in HAT medium and in medium containing 6-thioguanine were similar to those of skin fibroblasts from the patients. This series of studies confirmed that each of the two point mutations was responsible for the decreases in HPRT enzyme activity, and the proliferative phenotypes in HAT medium and medium containing 6-thioguanine. 相似文献
62.
Yoshihiro Imamura Nobuyuki Hamada Takayuki Nagai Masahisa Shingu 《Microbiology and immunology》1994,38(8):673-676
Stool specimens from infants who visited a clinic because of acute gastroenteritis were tested for the presence of human rotavirus. Among the samples obtained were specimens taken from seven patients who had visited the clinic at two different times. In six of these seven children, human rotavirus (HRV) was detected in only one of the specimens taken (i.e. during only one of the two visits). One patient was shown to have excreted HRV twice; in both cases the HRV was serotyped to be type 1. The present results indicate that the symptomatic reinfection of HRV was not a widely occurring phenomenon in the group of infants tested. 相似文献
63.
Takayuki Nakatsubo 《Ecological Research》1994,9(3):245-250
In order to evaluate the importance of growth of mosses in controlling evaporative water loss, the evaporation rates of some
subalpine moss species of various growth forms were compared with each other. The growth forms of the xerophytic species examined
were large cushion and compact mat, while those of the mesophytic species in the coniferous forest floor were smooth mat,
weft and tall turf. The evaporation rate per moss dry weight (Ew) was much smaller in the xerophytic species than in the mesophytic
species. However, the evaporation rate per basal area of moss colony (Ea) was not necessarily smaller in the xerophytic species.
The relation between Ea and dry weight per basal area of the colony (Wa) had a close correlation with the growth form. It
was concluded that the difference in the evaporation rate per weight between the exerophytic species and the mesophytic species
was largely due to the difference in Wa, and that the growth forms of the xerophytic species were suitable for increasing
Wa without increasing surface roughness. 相似文献
64.
Seasonal variation in the physical properties of agar and biomass of Gracilaria sp. (chorda type) from Tosa Bay,southern Japan 总被引:1,自引:1,他引:0
Plants of Gracilaria sp.(chorda type), which grow along the coast of Uranouchi Inlet in Tosa Bay, southern Japan, showed the highest biomass in the summer (26 °C to 31 °C) and spring season (15.1 °C to 24.9 °C). Maximum biomass was 6952 g m–2 in July, but gradually decreased in the autumn (30.5 °C in September to 20 °C in November) and winter (19.5 °C in December to 14.9 °C in February). Variation in yields and gel strength of the agars, were shown to depend on the time in the season. After alkali treatment (5% NaOH, 2 h) at three different temperatures (70, 80, and 90 °C), the agars showed gel strengths essentially that of commercial grade agars, with the best gel obtained at 80 °C. Maximum gel strength (1455 g cm–2 of 1.5% agar gel) occurred in winter when the biomass and agar yield were low. Minimum gel strength was in spring. Gel strength was inversely correlated with agar yield, but was positively correlated with apparent viscosity. Maximum viscosity was 40 cP. in December. Gelling temperatures, pH of 1.5% agar gel, and moisture content in agars showed little variation. 相似文献
65.
Histochemical assessment of selected carbohydrate sequences on Langerhans cells of human oral mucosa was made by combined use of enzyme digestion and immunostain-ing with monoclonal antibodies against specific carbohydrate structures. In both frozen sections and epithelial sheets without the enzyme pretreatment, mucosal Langerhans cells, identified by positive staining with anti-CD1a and HLA-DR antibodies, did not express any carbohydrate antigens on their surface. In contrast, following neuraminidase pretreatment of both types of material, the fucosylated type 2 chain (LeX) became detectable on Langerhans cells, indicating that sialic acid is the terminal residue of this sequence. Other enzymes were ineffective in this apparent unmasking, and the staining patterns of the other related carbohydrate sequences (Ley. Lea, Leb) remained unaffected by pretreatment with any of the enzymes used. These findings suggest that the mucosal Langerhans cells possess a unique carbohydrate chain, the sialyl fucosylated type 2 sequence (sialyl LeX antigen). 相似文献
66.
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68.
Nitrogen-fixing (acetylene-reducing) activity of intact saplings ofAlnus maximowiczii was measured under natural conditions in the subalpine zone of Mt Fuji. The nitrogen-fixing activity was detected from the
middle of June when expansion of leaves had just begun to the end of October when the shedding of leaves was almost completed.
Diurnal changes in the activity were almost parallel with those of ground temperature. The measured nitrogen-fixing activity
was related to ground temperature and total leaf area. Using this relation, annual nitrogen fixation was estimated from the
data of ground temperature and leaf area measured in the field. The amount of annual nitrogen fixation was almost the same
as that of nitrogen used for annual growth. It was concluded that nitrogen fixation by nodules made a considerable contribution
to the nitrogen economy in the saplings ofA. maximowiczii. 相似文献
69.
Tan Kah-Siew; Hoson Takayuki; Masuda Yoshio; Kamisaka Seiichiro 《Plant & cell physiology》1992,33(2):103-108
Irradiation of white fluorescent light (5 W m2) inhibitedthe growth of Oryza coleoptiles. Light irradiation increasedstress-relaxation parameters of coleoptile cell walls, minimumstressrelaxationtime and relaxation rate, and decreased cellwall extensibility (strain/load). Under light conditions, thecontents of ferulic and diferulic acids ester-linked to thehemicellulosic arabinose residue in cell walls increased andcorrelated with the modification of the cell wall mechanicalproperties. These results suggest that light irradiation enhancesthe formation of diferulic acid bridges in hemicelluloses, makingcell walls mechanically rigid and thus inhibits cell elongationin rice coleoptiles. Also, irrespective of coleoptile age orthe presence of light, the ratio of diferulic acid to ferulicacid was almost constant, suggesting that the rate limitingstep in the formation of diferulic acid bridges in Oryza cellwalls is in the step of feruloylation. (Received September 24, 1991; Accepted December 3, 1991) 相似文献
70.