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61.
Bark and Leaf Lectins of Sophora japonica Are Sequestered in Protein-Storage Vacuoles 总被引:3,自引:2,他引:1 下载免费PDF全文
The leguminous tree Sophora japonica contains a family of closely related, but distinct, lectins. Different members of this family are independently expressed in seeds, leaves, and bark (CN Hankins, J Kindinger, LM Shannon 1987 Plant Physiol 83: 825-829; 1988 Plant Physiol 86: 67-10). The inter-, and intracellular distribution of the bark and leaf lectins was studied by indirect postembedding immunogold electron microscopy. Aldehyde fixed bark and leaves postifixed with OsO4 and embedded in LR White resin permitted sensitive and specific immunogold labeling while maintaining cellular ultrastructure. The leaf and bark tissue cells contain protein-filled storage vacuoles which occupy most the cell's interior volume. The leaf and bark vacuoles closely resemble the protein bodies, or protein storage vacuoles, of seed cotyledons. The leaf and bark lectins were found to be exclusively sequestered in the protein-storage vacuoles of these tissues. 相似文献
62.
We have systematically studied the relationship between the relative stability (R) of respiration and the loop gain (LG) of the CO2 control system in 15 healthy awake adult males during progressive hypoxia. R was measured by the ventilatory oscillations after brief (less than 10 s) CO2 challenges. Control theory suggests that such oscillations are completely governed by LG. A significant positive correlation was found between R and LG (r = 0.74, P less than 0.01, n = 85). A minimal mathematical model of respiratory control was used to predict R as a function of LG. Serial correlation analysis (r = 0.09, P greater than 0.1) of the residuals indicated statistical agreement between predictions and observations. The mean residual (0.011) was not significantly different from zero (P greater than 0.1). Also, as the model predicted, sustained periodic breathing (PB) occurred whenever the estimated LG was greater than unity. The mean LG breathing room air was 0.51 and for the 13 epochs of PB was 1.17 (range 0.71-1.65). It is concluded that PB is a quantitative extension of the relative stability continuum and corresponds to unstable operation of the CO2 control system. Furthermore, relative stability can be quantitatively predicted for each subject by a minimal mathematical model. 相似文献
63.
64.
The exposure of mouse splenic lymphocytes to the microtubule assembly-promoting drug taxol (10 microM for 4 h) results in an extensive reorganization of the microtubule system to form one to a few large bundles of microtubules, which extend from the centrosome. Lymphocytes pretreated with taxol for 4 h, or cultured in the continued presence of taxol, respond normally to the mitogen concanavalin A up to, and including, the stage of DNA replication. In contrast, the induction of DNA synthesis during the alloactivation of lymphocytes is inhibited when taxol is present in the mixed leukocyte culture. If the stimulators are pretreated with this drug, the mixed leukocyte reaction occurs normally, but pretreatment of the responders inhibits the proliferative response markedly. Microscopic observations of nuclear morphologies in these populations and autoradiography indicate that taxol inhibition occurs early in alloactivation, prior to DNA replication. The responding ability of taxol-treated lymphocytes is not restored to control levels by the addition of interleukin 2, leading to the suggestion that interleukin 2 receptors do not emerge or function normally in these cells. We conclude that the capacity to respond to allogeneic cells, but not to a mitogen, is dependent on the presence of the normal submembranous organization of the microtubule system. 相似文献
65.
Chronic treatment of hamsters with estradiol for several months has previously been shown to decrease the specific content
of cytochrome P450 in the kidney, a target of hormonal carcinogenesis, but not in liver. The reason for this decrease in metabolic
enzyme activity is unknown and has been examined in this investigation. We now report that the decrease in specific content
of renal cytochrome P450 by 73% in response to estradiol was not affected by co-treatment with tamoxifen for 1 month. The
subcutaneous infusion of 250 μg/day estradiol for 7 days lowered renal cytochrome P450 by 71% from control values and was
therefore used for further mechanistic studies. This treatment decreased renal activities of estradiol 2- or 4-hydroxylase
by 77 to 80%, of 7-ethoxycoumarin-O-deethylase by 66% of control values, respectively, and completely eliminated aryl hydrocarbon
hydroxylase activities, whereas liver enzymes remained unaffected. After 7 days of infusion of estradiol, fluorescent products
of lipid peroxidation were more than doubled in hamster kidney but remained unchanged in liver. The possibility of enzyme
destruction by binding of estradiol 2,3-quinone to metabolizing enzymes was investigatedin vitro. In the presence of 2-hydroxyestradiol, cumene hydroperoxide, and microsomes, conditions known to favor the oxidation of
the steroid to quinone, the binding of catechol estrogen metabolite to microsomal protein increased 60 fold over control values
in the absence of cofactor. Purified rat liver cytochrome P450c also oxidized 2-hydroxyestradiol to 2,3-estradiol quinone.
The rate of oxidation was linear for the first 2–3 min, but thereafter decreased with time. Under these incubation conditions,
irreversible binding of catechol estrogen metabolite to cytochrome P450c increased for the first 2–3 min and then remained
at this plateau level. It was concluded that enzyme destruction by a reactive estrogen metabolite or by lipid peroxides may
be a major reason for the organ-specific decrease in cytochrome P450 enzymes in kidneys of estrogen-treated hamsters. 相似文献
66.
Shannon R. Barber John Werdel Millie Symbula John Williams Barbara A. Burkett Peyton T. Taylor James K. Roche Christopher P. Crum 《Cancer immunology, immunotherapy : CII》1992,35(1):33-38
Summary Although serological reactivity to human papillomavirus type 16 (HPV-16) proteins has been demonstrated in patients with invasive cervical carcinoma, the degree of seroreactivity to these proteins in women with preinvasive disease and its relationship to the HPV type associated with the disease are unclear. We obtained sera from 27 women undergoing cone biopsy for cervical precursor lesions and 22 controls and analyzed seroreactivity by Western blot to fusion proteins containing portions of the HPV-16 E4, L1 and L2 open-reading frames (ORFs). Positives were analyzed by scanning densitometry and intensity values for each case plotted relative to controls. Cervical biopsy specimens from patients were analyzed for HPV-16 nucleic acids by DNA · DNA in situ hybridization. Mean intensity values for seroreactivity to the pATH-E4 protein approached significance (P = 0.058) and a significantly higher proportion of cases vs controls registered values over 4.0 for pATH-E4 (26% vs 4.5%;P = 0.04) and pATH-L2 (48% vs 18%;P = 0.03) proteins. A significantly higher mean intensity value for E4 was observed for cases containing HPV-16 DNA vs HPV-16 negative cases or controls. Thus, seroreactivity to HPV-16-derived proteins may be more common in women with preinvasive cervical disease, and for some protein targets (E4) may indicate a relatively type-specific response.Supported in part by grants from the National Cancer Institute [CA 47676 (C.P.C.)], American Cancer Society [MV-395 (C.P.C.)] and an institutional support grant (J.K.R.). Dr. Crum is a recipient of a Physician Scientist Award from the National Institute of Allergy and Infectious Disease (AI00628) 相似文献
67.
Anaerobic growth on elemental sulfur using dissimilar iron reduction by autotrophic Thiobacillus ferrooxidans 总被引:2,自引:0,他引:2
Abstract Anaerobic growth on elemental sulfur using dissimilar iron reduction by Thiobacillus ferrooxidans has been demonstrated. The ferric ion reducing activity (FIR) of the anaerobic cells was double that of the aerobic cells. Significant differences in inhibition of FIR by respiratory inhibitors were observed between aerobic and anaerobic cells. A higher amount of cytochrome was detected in anaerobic cells compared to aerobic cells. Absorption minima developed with the addition of ferric sulfate in the dithionite reduced cell suspension demonstrated that the ferric ion could accept electrons from the cytochrome system of this bacterium. The possibility of two different electron transport chains in ferric ion reduction is discussed. 相似文献
68.
Roy E. Crabtree Edward C. Cyr Renée E. Bishop Laura M Falkenstein John M. Dean 《Environmental Biology of Fishes》1992,35(4):361-370
Synopsis Leptocephali were collected in June 1981 and July 1989 over the continental shelf and slope of the Florida west coast. Tarpon larvae ranged 5.5–24.4 mm standard length (SL) and were the second most abundant leptocephalus species. Sagittae examined with compound microscopes and scanning electron microscopy had increments that were presumed to be formed daily. Increment counts made using the two microscopic techniques were not significantly different. Estimated ages ranged 2–25 days with a growth rate (± standard error) of 0.92 ± 0.04 mm d–1 The least squares linear regression equation SL = 2.78 + 0.92 (age in days) best described the relationship between estimated age and length. Adult tarpon appear to undergo a substantial spawning migration from inshore areas frequented during spring and summer to offshore spawning grounds. Spawning occurs during May, June, and July, although the spawning season may be of greater duration. 相似文献
69.
Complete or partial monosomy 7 is a recurring cytogenetic abnormality in acute myelogenous leukemia (AML) and myeloproliferative syndromes (MPS) and is particularly common in patients with Fanconi's anemia and in secondary AML. A familial form of monosomy 7 has been recognized in which two or more siblings develop MPS or AML before age 20. We tested the hypothesis that a recessive cancer susceptibility locus on chromosome 7 was important in the pathogenesis of leukemia in familial monosomy 7 by determining the parental origins of the chromosome 7 retained in the bone marrows of three pairs of affected siblings. We found no overlapping region where all three pairs retained DNA derived from the same paternal or maternal chromosome. These data suggest that inactivation of a single allele of a putative tumor-suppressor gene may be sufficient to contribute to leukemic transformation in familial monosomy 7. 相似文献
70.
MNNG-induced killing of V79 cells has been found to be enhanced on inhibition of topoisomerase II activity by nalidixic acid and poly(ADP-ribose) polymerase synthesis by benzamide. Using these 2 inhibitors in conjunction after MNNG treatment, some overlap in the functions of these 2 enzymes was observed. Nalidixic acid and benzamide were found to suppress the yields of mutations and SCEs induced by MNNG. Benzamide was more effective in suppressing the mutation yield whereas nalidixic acid was more effective in suppressing SCEs. A model based on the relative requirement of topoisomerase and poly(ADP-ribose) for the repair of different types of damage has been proposed to explain the results. 相似文献