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81.
Functional and ultrastructural effects of nontypeable haemophilus influenzae in a hamster trachea organ culture system 总被引:1,自引:0,他引:1
Joseph M. Mylotte Richard R. Stack Timothy F. Murphy John Asirwatham Michael A. Apicella 《In vitro cellular & developmental biology. Plant》1985,21(10):575-582
Summary A hamster trachea organ culture system was utilized to evaluate quantitatively the effects of a strain of nontypeableHaemophilus influenzae (NTHI) and culture supernatants of the same strain on ciliary activity. Tracheal explants were maintained in organ culture
for 96 to 144 h and ciliary activity was observed daily with an inverted microscope. Explants continuously exposed to a strain
of NTHI had a progressive decline in ciliary activity which was significantly lower than uninfected controls evaluated concomitantly
by 48 h of exposure and thereafter. Histologic studies revealed a progressive degeneration of mucosal cells and exfoliation
of ciliated cells. Scanning electron microscopy showed little adherence of NTHI to the mucosal surface. Sterile broth cultures
of NTHI and supernatants of organ cultures infected with the same NTHI strain had no adverse effect on ciliary activity. Infected
tracheal explants treated with ampicillin 24, 48, or 72 h after continuous bacterial challenge had no significant decline
in ciliary activity compared to controls. The lack of adherence and the histologic changes observed when hamster trachea cultures
were infected with NTHI suggested a toxin might mediate the damage observed. Broth and organ culture supernatants, however,
produced no damage. Therefore, further studies are needed to determine the role, if any, of a toxin in the production of damage
to hamster tracheal explants by NTHI.
This work was supported by a Merit Review grant from the Veterans Administration and by Grant AI-19641 from the National Institute
of Allergy and Infectious Diseases. 相似文献
82.
A Osuna G Ortega F Gamarro S Castanys M C Mascaro 《International journal for parasitology》1984,14(3):253-257
The penetration of metacyclic forms of Trypanosoma cruzi into HeLa cells after different treatments was studied. When cell development was synchronized by two different processes, maximum rates of parasitization occurred during the S phase of cell cycle (29.48 and 24.3%). However, when cells were treated with trypsin (0.1%), parasitization rates appeared to be lower than controls, reaching values similar to controls 14 h after the beginning of the treatment. Infection values remained unaltered after treatment with colcemid (0.6 μg ml?1). Cell treatment either with valinomycin (1 μg ml?1) or with actinomycin D (250 μg ml?1) caused a marked decrease in the percentage of parasitization. When cells were treated and infected in the presence of tunicamycin (100 ng ml?1), parasitization rates were increased (14.7%) compared to control cells (6%). On the other hand, no differences in parasitization rates were observed when cells were treated with cycloheximide (100 μg ml?1). Infection in a low redox medium (?100 mV) resulted in considerable increase in parasitization. 相似文献
83.
THE QUANTITATIVE STUDY OF MYCORRHIZAL INFECTION 总被引:10,自引:9,他引:1
84.
An indole 2,3-dioxygenase was purified ca 38-fold from maize leaves. The enzyme had an MW of about 98000, an optimum pH of 5.0 and the energy of activation was 9.1 kcal/mol. The Kmax for indole was 1.4 × 10?4 M. The enzyme was inhibited by diethyldithiocarbamate, salicylaldoxime and sodium dithionite. The inhibition by diethyldithiocarbamate was specifically reversed by Cu2+. The dialysed enzyme was stimulated by Cu2+. Four atoms of oxygen were utilized in the disappearance of 1 mole of indole. Inhibition of the enzyme by -SH compounds and -SH group inhibitors, and their partial removal by Cu2+ only, suggested the involvement of -SH groups in binding of Cu2+ at the catalytic site. 相似文献
85.
The mature winter leaves of Pilosella officinarum coll. Schultz and Schultz contained 29 mg esterified triterpenoid alcohols (g dry weight)−1 , of which over 80% was esterified with long-chain (C16-C18) fatty acids. The major fatty acids were 16:0, 18:2ω6 and 18:3ω3 and their amounts varied according to the season and stage of leaf development. In mature leaves the amount of triterpenoid alcohols esterified with long-chain fatty acids varied only slightly with the season. The changes in the fatty acid proportions in late winter-early spring, however, indicated a turnover in the esterified triterpenoid alcohol pool. In late winter after the snow had melted a 50% decrease occurred in the amount of triterpenoid alcohols esterified with short-chain fatty acids. The amount of esterified triterpenoid alcohols in immature leaves was relatively low [4 mg (g dry weight)−1 ].
In the mature leaves esterified triterpenoid alcohols were found in globules whose appearance varied greatly according to the season. The globules were partly dissolved in late winter, and this together with the activation of respiration, suggests that the globules function as short-term energy reservoirs. Relationships between the appearance of lipid globules and the amount of esterified triterpenoid alcohols are discussed. 相似文献
In the mature leaves esterified triterpenoid alcohols were found in globules whose appearance varied greatly according to the season. The globules were partly dissolved in late winter, and this together with the activation of respiration, suggests that the globules function as short-term energy reservoirs. Relationships between the appearance of lipid globules and the amount of esterified triterpenoid alcohols are discussed. 相似文献
86.
P. Fleurat-Lessard 《Protoplasma》1986,130(1):1-4
Summary Parenchyma cells ofMimosa pudica display close associations between two or more cisternae of the endoplasmic reticulum. These associations form simplified types of lamellar bodies in which inner paired lamellae have lost their ribonucleoprotein granules and are separated by a dense layer. 相似文献
87.
A. N. WEBBER N. R. BAKER CANDIDA D. PAIGE M. F. HIPKINS 《Plant, cell & environment》1986,9(3):203-208
Abstract Photosynthetic electron transport activities and the ability to generate and maintain a trans-thylakoid proton electrochemical gradient were examined during chloroplast development in 4-day-old wheat leaves grown under a diurnal light regime. Polarographic and spectropholometric studies on leaf tissue demonstrated that poorly developed chloroplasls at the leaf base could photo-oxidize water and transfer electrons from photosystem 2 to photosystem 1. The capacity for non-cyclic whole-chain electron transport increased during chloroplast development. Thylakoids isolated from the leaf base, although capable of pumping protons into the inlrathylakoid space, could not maintain a trans-membrane proton electrochemical gradient; this ability developed at later stages of chloroplast biogenesis in the leaf. The implications of these results for the energetics of the developing leaf are discussed. 相似文献
88.
6-(2,3,4-Trihydroxy-3-methylbutylamino) purine, trivial name trihydroxy-zeatin (THZ), an oxidation product of zeatin was applied via the epidermis or cut end of Avena leaf segments. THZ did not retard senescence of the segments in either case. With epidermal application THZ remained unmetabolised while the cut end method of application resulted in its metabolism to more polar THZ metabolites of unknown identity. The Avena leaf tissue did not apparently cleave the isoprenoid side chain of the THZ molecule. 相似文献
89.
The photosynthetic capacity of detached leaves of a non-yellowing mutant of Festuca pratensis Huds. declined during senescence at a similar rate to that in a normal cultivar. Respiratory oxygen uptake in the dark continued at similar rates in both genotypes during several days of senescence. In chloroplasts isolated from leaves at intervals after excision, the rate of photosystem I (PS I)-mediated methyl viologen reduction using reduced N,N,N,N-tetramethyl-p-phenylene diamine as electron donor also declined in both genotypes, possibly due to loss of integrity of the photosynthetic apparatus in the cytochrome f-plastocyanin region. There was a similar fall in PS II electron transport using water as electron donor and measured at the rate of reduction of 2,6-dichlorophenolindophenol. Partial restoration of this activity by the addition of diphenyl carbazide was evidence for lability of the oxygen-evolving complex during senescence. An accentuated difference between mutant and normal material in this case indicated that the mutant retains a greater number of functional PS II centres. Changes in the light-saturation characteristics of the two photosystems have been discussed in relation to the organization of the photosynthetic membranes during senescence.Abbreviations and symbols DCMU
3-(3,4-dichlorophenyl)-1,1-dimethylurea
- DCPIP
2,6-dichlorophenolindophenol
- DMSO
dimethyl sulphoxide
- DPC
diphenyl carbazide
- MV
methyl viologen
- PS I, PS II
photosystem I, II
- TMPD
N,N,N,N-tetramethyl-p-phenylene diamine 相似文献
90.
The assimilation of nitrate under dark-N2 and dark-O2 conditions in Zea mays leaf tissue was investigated using colourimetric and 15N techniques for the determination of organic and inorganic nitrogen. Studies using 15N indicated that nitrate was assimilated under dark conditions. However, the rate of nitrate assimilation in the dark was only 28% of the rate under non-saturating light conditions. No nitrite accumulated under dark aerobiosis, even though nitrate reduction occurred under these conditions. The pattern of nitrite accumulation in leaf tissue in response to dark-N2 conditions consisted of three phases: an initial lag phase, followed by a period of rapid nitrite accumulation and finally a phase during which the rate of nitrite accumulation declined. After a 1-h period of dark-anaerobiosis, both nitrate reduction and nitrite accumulation declined considerably. However, when O2 was supplied, nitrate reduction was stimulated and the accumulated nitrite was rapidly reduced. Anaerobic conditions stimulated nitrate reduction in leaf tissue after a period of dark-aerobic pretreatment. 相似文献