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Hepatic glycoprotein synthesis in streptozotocin diabetic rats 总被引:2,自引:0,他引:2
C Sharma E R Dalferes B Radhakrishnamurthy C J DePaolo G S Berenson 《Biochemistry international》1987,15(2):395-401
In vitro incorporation of 3H-mannose into dolichol phosphate mannose, dolichol pyrophosphate oligosaccharides, and secretory and membrane glycoproteins was investigated in liver slices from streptozotocin diabetic rats. In addition, 14C-leucine incorporation into glycoproteins was studied. 3H-mannose incorporation was significantly less in secretory glycoproteins from diabetic rat liver slices than from control tissues, but 14C-leucine incorporation in these proteins was similar in both groups. Dolichol-phosphate mannose and dolichol-phosphate oligosaccharide synthesis were significantly down-regulated in diabetes. When incubated with insulin, mannosylation of secretory proteins, dolichol-phosphate mannose and dolichol-phosphate oligosaccharides reached control levels in three hours. Dolichol-phosphate mannosyltransferase activity was significantly less in diabetes, while in the presence of insulin, the enzyme activity reached control levels in three hours. These results indicate that key intermediates in glycoprotein biosynthesis are regulated by insulin. 相似文献
24.
Phytochrome, activated by continuous red light, increases the amount of total polyadenylated RNA during photomorphogenesis of mustard (Sinapis alba L.) cotyledons. In-vitro translation of total polyadenylated RNA in a reticulocyte translation system has shown that the activity of translatable -amylase mRNA is increased by phytochrome about threefold in the 3-d-old cotyledons, based on equal amounts of polyadenylated RNA, and about eightfold on a per-cotyledon basis. Cordycepin prevents the accumulation of translatable -amylase mRNA. It is concluded that the phytochrome-mediated control of -amylase synthesis is exerted on the level of mRNA synthesis. During seedling development in continuous red light, a phytochrome-dependent increase of -amylase mRNA can be observed at least 6 h before the onset of -amylase synthesis. If, after a period of enzyme synthesis, phytochrome action is interrupted by long-wavelength far-red light followed by darkness, -amylase mRNA as well as -amylase synthesis remain at a high level for 8–10 h and then decline sharply. It is concluded that -amylase mRNA, having an apparent lifetime of the order of 8–10 h, can be formed under the influence of phytochrome during early seedling development but it activates -amylase synthesis only after a lag-phase of about 8 h, when the cotyledons acquire competence to synthesize the enzyme. The consequences of these findings for the signal-transduction chain of phytochrome are discussed.Abbreviations EDTA
Na2-ethylenediaminotetraacetic acid
- PAGE
polyacrylamide gel electrophoresis
- poly(A)+RNA
polyadenylated mRNA
- Pr, Pfr
red- and far-red-absorbing forms of phytochrome
- SDS
sodium dodecyl sulfate
- Tris
2-amino-2-(hydroxymethyl)-1,3-propanediol 相似文献
25.
C Sharma C J Depaolo E R Dalferes B Radhakrishnamurthy G S Berenson 《Proceedings of the Society for Experimental Biology and Medicine. Society for Experimental Biology and Medicine (New York, N.Y.)》1987,185(3):347-351
The rate of dolichol synthesis in normal and diabetic liver slices in the presence or absence of insulin was investigated with radiolabeled acetate and mevalonate as substrates. Cholesterol and dolichol syntheses were found low in diabetic rat liver slices when incubated either with 1-14C-acetate or 2-3H-mevalonate. In the presence of insulin, cholesterol and dolichol synthesis in diabetic rat liver slices returned to normal in nine hours when incubated with 1-14C-acetate; however, with 2-3H-mevalonate, synthesis of cholesterol and dolichol normalized in about three hours. These studies show that dolichol synthesis in rat liver slices is dependent on insulin. 相似文献
26.
Zinc Deficiency and Anther Development in Maize 总被引:1,自引:0,他引:1
Sharma Parma Nand; Chatterjee Chitralekha; Sharma Chandra Prakash; Agarwala Shirish Chandra 《Plant & cell physiology》1987,28(1):11-18
With the onset of male reproductive phase at 28 days, zinc waswithdrawn from fifty percent of maize (Zea mays L. cv. Ganga2) plants grown in refined sand at 0.13 mg Zn liter1.Plants from which zinc was withdrawn developed zinc deficiencysymptoms in young leaves after 38 days and were low in tissuezinc. Their tassel formation and pollen development was retarded.Anthers failed to develop beyond freshly liberated young pollengrain stage and vessels were formed in place of sporogenoustissue in sixty percent anthers of the younger of the two florets.Anthers from these plants showed low zinc concentration andstimulated specific activities of catalase, peroxidase, ribonucleaseand acid phosphatase. On resuming normal zinc (0.13 mg Zn liter1) through rootsto the plants from which it was withdrawn for 17 days, vegetativegrowth was partially renewed and short axillary buds were formedbut the development of anthers remained retarded. (Received April 11, 1986; Accepted October 15, 1986) 相似文献
27.
R. B. Sharma 《Plant and Soil》1987,98(3):429-432
Summary A greenhouse study in which 24, 54 and 71 per cent roots of wheat (Triticum aestivum L.) were pruned on the 73rd day from the date of planting (anthesis stage) showed that during a 7-day period following root
pruning, total transpiration and leaf water potential were significantly lower (P=0.05) and the stomatal resistance was significantly higher (P=0.05) where 54 and 71 per cent roots were pruned, as compared to no root pruning or 24 per cent root pruning. The leaf relative
water content, however, showed no significant differences. Thus about one-fourth root sytem could be reduced without adversely
affecting the plant-water status. 相似文献
28.
The chromosome complements of six cyprinid fishes were studied, using the routine air-drying Giemsa staining technique. The diploid chromosome number recorded is 2n = 50 (8m+18sm+14st+10t) with NF = 90 in Aspidoparia morar, 2n = 50 (8m+12sm+12st+18t) with NF = 82 in Crossocheilus latius latius, 2n = 50 (6m+12sm–16st+16t) with NF = 90 in Labeo pangusia, 2n = 70 (16m+6sm+16st–32t) with NF = 108 in Perilampus atpar, 2n = 48 (4m+6st+38t) with NF = 58 in Puntius chrysopterus and 2n = 50 (2m+2sm+4st+42t) with NF = 58 in P. tetrarupagus. Sex chromosomes are not identifiable in any of these species. A pair of marker chromosomes has been observed in all species excepting A. morar. 相似文献
29.
Ten species of Lepadella Bory de St. Vincent, 1826, including one new species and one new form, are documented from North-Eastern India. Two of these species are new records from this country and six are new reports from N.E. region. Comments are also made on the status and distribution of various Indian taxa. 相似文献
30.