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141.
The morphology of mycelial fungi in liquid culture effects culture rheology and this in turn may affect product yield. It is therefore important to understand how environmental factors influence mycelial morphology and this paper describes the effect of dilution rate on two strains of Fusarium graminearum, the relatively sparsely branched parental strain (A3/5) and a relatively highly branched "colonial" variant (C106). At any given dilution rate, the concentration of mycelial fragments present at steady state of both strains remained approximately constant with time, suggesting that mycelial fragmentation occurred in a regular manner. However, for both strains fragment concentration decreased with increasing dilution rate. The strains had a similar morphology at a dilution rate of 0.07 h(-1). The length of the hyphal growth unit of A3/5 increased with increase in dilution rate, while that of C106 decreased with increase in dilution rate. At all dilution rates, C106 produced up to ten times more macroconidia than A3/5. 相似文献
142.
Metabolism of progesterone by avian granulosa cells in culture 总被引:1,自引:0,他引:1
J P Wiebe K D Buckingham R L Zobell F Hertelendy 《The Journal of steroid biochemistry and molecular biology》1990,37(1):113-120
Previous studies have demonstrated that progesterone is the primary product of steroidogenesis in avian granulosa cells during short-term incubation. However, during more prolonged culture, lasting several days, the progesterone content in the medium was found to decrease progressively, indicating in vitro metabolic conversion. In the present study we have isolated and identified a number of progesterone metabolites. Granulosa cells, isolated from mature ovarian follicles of laying hens, were cultured in medium 199 supplemented with fetal calf serum and containing [14C]progesterone. After 4 days in culture, cells + media were extracted and the radioactive metabolites separated and identified by TLC, HPLC and GC-MS. Several of the metabolites were further characterized by derivatization and crystallization to constant specific activity. A total of 24 radioactive substances was detected. Of these, 15 have been positively identified, 5 tentatively and the remaining 4 are unidentified. The principal metabolite, representing more than 45% of the total radioactivity, was identified as 3 alpha-hydroxy-5 beta-pregnan-20-one. In addition, significant amounts of 3 alpha-hydroxy-5 alpha-pregnan-20-one (5.76%), 5 beta-pregnane-3,20-dione (3.05%), and 5 alpha-pregnane-3,20-dione (2.95%) were detected and identified. The results indicate that avian granulosa cells possess 3 alpha-hydroxy-steroid dehydrogenase (3 alpha-HSD), 17 beta-HSD, 20 alpha-HSD, 20 beta-HSD, 17 alpha-hydroxylase, C17-20-lyase and 5 alpha- and 5 beta-reductase activities. These enzyme activities may convert progesterone to biologically inactive or less active metabolites. However, a functional role for some of these metabolites cannot be ruled out. 相似文献
143.
Influence of hydrogen fluoride fumigation on the water economy of soybean plants 总被引:3,自引:2,他引:1 下载免费PDF全文
The influence of hydrogen fluoride fumigation on water economy was studied using soybean (Glycine max [L] Merr.). Fumigation caused partial stomatal closure in 1 hour and practically complete closure within 4 hours. The transpiration rate was greatly reduced by fumigation, while the leaf temperature was increased. Water potential increased after 1 day but fell drastically when necrosis occurred. Effects of interrupted fumigation during the day were somewhat less severe in all respects than those of continuous fumigation; nighttime fumigation caused only minor effects. Fluoride uptake was also much less from nighttime than from daytime fumigations. 相似文献
144.
[125I]iodohydroxynitrobenzylthioinosine ([125I]IH-NBMPR), a new gamma-labeled nucleoside transport inhibitor, has been prepared at a theoretical specific activity of 2000 Ci/mmol (1 Ci = 37 GBq). IH-NBMPR was more acidic than hydroxynitrobenzylthioinosine (H-NBMPR), having a pKa of 4.6. Site-specific binding of [125I]IH-NBMPR to membrane-enriched fractions (MEF) from S49 mouse lymphoma cells was pH dependent, increasing with the fraction of undissociated molecules present; it was maximal at pH 4.5 and negligible at pH 7.0. Scatchard analysis of specific binding to MEF from S49 cells under equilibrium conditions at pH 5.0 yielded a Kd of 15 nM (equivalent to 4.0 nM for the undissociated fraction of inhibitor molecules) and maximum number of binding sites (Bmax) of 4.9 pmol/mg protein. Specific binding of IH-NBMPR could not be demonstrated in MEF from AE1 cells, a nucleoside transport-deficient mutant of S49 cells. Influx of uridine into mouse erythrocytes at pH 5.0 in the presence of 5 microM IH-NBMPR (1.4 microM undissociated IH-NBMPR) was reduced to about 7% of the control value, indicating that this compound is an effective nucleoside transport inhibitor. Photoactivation of site-bound [125I]IH-NBMPR, following equilibration of the ligand with MEF from S49 cells at pH 5.0, resulted in specific covalent labeling of a polypeptide with a relative molecular mass of 52,000-63,000, identified on sodium dodecyl sulfate-polyacrylamide gels. These results indicate that the new, iodinated ligand is an inhibitor of nucleoside transport and that it binds specifically and with high affinity to nucleoside transporter polypeptides in mammalian cells. 相似文献
145.
The presence of arylsulfatase(s) was confirmed in salt marsh soils. The temperatures of maximum activity and inactivation, the pH range over which the enzyme was active, and the Km values were similar to those of soil enzymes. Unlike soil arylsulfatases, however, the salt marsh enzymes do not appear to be repressed by sulfate. It is postulated that these enzymes may be necessary for the initiation of arylsulfate ester metabolism. 相似文献
146.
1-alpha- and 1-beta-D-Arabinofuranosyl-2-nitroimidazole (alpha-AZA and beta-AZ A) are synthons for a number of potential markers of tissue hypoxia. A one pot synthesis in which 2-nitroimidazole is coupled with a mixture of alpha- and beta-1-O-acetyl-2,3,5-tri-O-benzoyl-D-arabinofuranose in the presence of stannic chloride, followed by deprotection using ammonia/methanol, is described Previously reported conditions for coupling 2-nitroimidazole to 1-alpha-bromoarabinofuranose protected by base-hydrolyzable groups afforded alpha-AZA almost exclusively. 相似文献
147.
Growth and phycocyanin production in batch and fed-batch cultures of the microalga Galdieria sulphuraria 074G, which was grown heterotrophically in darkness on glucose, fructose, sucrose, and sugar beet molasses, was investigated. In batch cultures, specific growth rates and yields of biomass dry weight on the pure sugars were 1.08-1.15 day-1 and 0.48-0.50 g g-1, respectively. They were slightly higher when molasses was the carbon source. Cellular phycocyanin contents during the exponential growth phase were 3-4 mg g-1 in dry weight. G. sulphuraria was able to tolerate concentrations of glucose and fructose of up to 166 g L-1 (0.9 M) and an ammonium sulfate concentration of 22 g L-1 (0.17 M) without negative effects on the specific growth rate. When the total concentration of dissolved substances in the growth medium exceeded 1-2 M, growth was completely inhibited. In carbon-limited fed-batch cultures, biomass dry weight concentrations of 80-120 g L-1 were obtained while phycocyanin accumulated to concentrations between 250 and 400 mg L-1. These results demonstrate that G. sulphuraria is well suited for growth in heterotrophic cultures at very high cell densities, and that such cultures produce significant amounts of phycocyanin. Furthermore, the productivity of phycocyanin in the heterotrophic fed-batch cultures of G. sulphuraria was higher than is attained in outdoor cultures of Spirulina platensis, where phycocyanin is presently obtained. 相似文献
148.
Sepúlveda MS Wiebe JJ Honeyfield DC Rauschenberger HR Hinterkopf JP Johnson WE Gross TS 《Journal of wildlife diseases》2004,40(4):782-786
Thiamine deficiency has been linked to early mortality syndrome in salmonids in the Great Lakes. This study was conducted to compare thiamine concentrations in American alligators (Alligator mississippiensis) and Florida largemouth bass (Micropterus salmoides floridanus) eggs from sites with high embryo mortality and high exposure to organochlorine pesticides (OCPs) (Lakes Apopka and Griffin, and Emeralda Marsh, Florida, USA) to those from sites that have historically exhibited low embryo mortality and low OCPs (Lakes Woodruff and Orange, Florida). During June-July 2000, 20 alligator clutches were collected from these sites, artificially incubated, and monitored for embryo mortality. Thiamine and OCPs were measured in one egg/clutch. During February 2002, 10 adult female bass were collected from Emeralda Marsh and Lake Woodruff and mature ovaries analyzed for thiamine and OCP concentrations. Although ovaries from the Emeralda Marsh bass contained almost 1,000-fold more OCPs compared with the reference site, Lake Woodruff, there were no differences in thiamine concentrations between sites (11,710 vs. 11,857 pmol/g). In contrast, alligator eggs from the reference site had five times the amount of thiamine compared with the contaminated sites (3,123 vs. 617 pmol/g). Similarly, clutches with >55% hatch rates had significantly higher concentrations of thiamine compared with clutches with <54% hatch rates (1,119 vs. 201 pmol/g). These results suggest that thiamine deficiency might be playing an important role in alligator embryo survival but not in reproductive failure and recruitment of largemouth bass. The cause(s) of this thiamine deficiency are unknown but might be related to differences in the nutritional value of prey items across the sites studied and/or to the presence of high concentration of contaminants in eggs. 相似文献
149.
OBJECTIVE: To determine the outcome and side effects of a new drug protocol to induce abortion. DESIGN: Case series. SETTING: An urban primary care practice. PATIENTS: One hundred consecutive patients who requested elective termination of pregnancies of less than 8 weeks'' gestation. INTERVENTION: Subjects received methotrexate (50 mg/m2 body surface area, administered intramuscularly) and, 3 days afterward, misoprostol (800 micrograms, given vaginally). OUTCOME MEASURES: Number of abortions induced within 24 hours and within 10 days of misoprostol administration, number of surgical aspirations conducted because of incomplete abortion, mean amount of bleeding and pain and the number of women who, if faced with the same situation, said they would again choose a drug-induced abortion over a surgical one. RESULTS: Abortion occurred within 24 hours of misoprostol administration among 48 women and within 10 days among 69 women. In total, 89 women had an abortion without surgical aspiration. Of these women, 71 said they would choose a drug-induced abortion if faced with the choice again. CONCLUSION: Abortion induced with methotrexate and misoprostol appears to be a feasible alternative to surgical abortion and deserves further study. 相似文献
150.
The fine structure of more than 20 marine pseudomonads and more than 15 achromobacters was examined. Under the conditions extant, clear differences between members of these two groups were seen. The pseudomonads displayed the characteristic gram-negative morphology: the cell wall was irregularly undulant and the cytoplasmic membrane more nearly planar, ribonucleoprotein (RNP) particles were loosely packed throughout the periphery of the cytoplasm, and the deoxyribonucleic acid (DNA) was axially disposed. Cell division appeared to be by constriction. Some strains characteristically produced evaginations or blebs of the cell wall. Occasionally, thick, densely stained ring structures were seen which are possibly analogous to mesosomes. In contrast, the achromobacters demonstrated a regularly undulant outer cell wall element and a planar inner wall. The cytoplasmic membrane was thin and not readily observed. RNP particles were densely stained and tightly packed in the cytoplasm; the DNA was most often lobate in disposition. Cellular division was mediated by the formation of a septum which consisted of the cytoplasmic membrane and the inner element of the cell wall. Mesosomes were observed in all of the strains examined. Dense inclusion bodies were also seen in many strains. 相似文献