scholarly journals Hydrolysis of an exogenous 125I-labelled protein by rat yolk sacs. Evidence for intracellular degradation within lysosomes

1979 ◽  
Vol 184 (3) ◽  
pp. 519-526 ◽  
Author(s):  
G Livesey ◽  
K E Williams

When added to the serum-free medium in which 17.5-day rat yolk sacs were incubated, formaldehyde-denatured 125I-labelled bovine serum albumin was rapidly degraded. More than 80% of the radiolabelled digestion products appearing in the incubation medium consisted of [125I]iodo-L-tyrosine; larger digestion products were found only in association with the yolk-sac tissue. In the early stages of an incubation, low-molecular-weight digestion products began to appear in the incubation medium only after they could be detected within the tissue, and progressive association of trichloroacetic acid-insoluble radioactivity with the tissue preceded both these events. None of the observed proteolysis could be attributed to proteinases released into the incubation medium. Tissue-associated acid-insoluble radioactivity showed a lysosomal distribution on sub-cellular fractionation, and cell-free homogenates of yolk sacs degraded albumin only at acid pH values. Progressively decreasing the rat of pinosome formation (either by progressively lowering the incubation temperature or by the use of increasing concentrations of the metabolic inhibitor rotenone) caused a corresponding decrease in the rate of degradation of albumin. These findings indicate that, in vitro, formaldehyde-denatured 125I-labelled bovine serum albumin is digested by rat yolk sacs exclusively intracellularly, within lysosomes.

1980 ◽  
Vol 188 (3) ◽  
pp. 895-903 ◽  
Author(s):  
G Livesey ◽  
K E Williams ◽  
S E Knowles ◽  
F J Ballard

In rat yolk sacs incubated in vitro, the rates of degradation of endogenous [3H]leucine-labelled proteins and of pinocytically ingested 125I-labelled bovine serum albumin were both decreased in the presence of either ammonium, methylammonium or ethylammonium ions (0-20 mM) or much lower concentrations of chloroquine (0-500 microM). These effects were also accompanied by an inhibition of pinocytosis, as measured by the rate of uptake of 125I-labelled polyvinylpyrrolidone, and by a fall in the [ATP]/[ADP] ratio within the tissue. Re-incubation in inhibitor-free medium of yolk sacs previously exposed to a weak base restored pinocytic and proteolytic capacities, except for tissues exposed to chloroquine at concentrations above 0.1 mM (these appeared to be cytotoxic); an attendent rise in [ATP]/[ADP] ratios to near normal values was also observed. Weak bases, at concentrations that fully arrested the breakdown of 125I-labelled albumin, failed to inhibit by more than 45% the degradation of [3H]leucine-labelled endogenous proteins. Since 125I-labelled bovine serum albumin has been shown to be degraded entirely intralysosomally by yolk sacs, this suggests either that the hydrolysis of endogenous proteins is shared between lysosomes and some other site or that, unlike 125I-labelled albumin, some endogenous proteins can be degraded within lysosomes at abnormally high pH.


1973 ◽  
Vol 134 (2) ◽  
pp. 415-424 ◽  
Author(s):  
William R. Moyle ◽  
Robert L. Jungas ◽  
Roy O. Greep

1. Experiments were designed to localize intracellularly the enzymes and sterol substrates required for steroidogenesis in Leydig-cell tumours. Subcellular fractions were prepared by differential centrifugation of tumour homogenates. Both free and esterified cholesterol were associated primarily with the fractions sedimenting at 1400gav. and the lipid layer floating on the surface of the isolation tubes; they were not found in the mitochondria, where the conversion of cholesterol into pregnenolone occurred. 2. Hydrolysis of esterified cholesterol was required before it could be oxidized to pregnenolone. 3. An enzyme capable of hydrolysing cholesterol esters was located external to the mitochondria. 4. Mitochondria were subfractionated by allowing them to swell in 0.02m-phosphate buffer (pH7.2) and separating the inner and outer membranes by sedimentation in sucrose gradients. The outer membrane, identified by its content of monoamine oxidase, contained most of the cholesterol associated with the mitochondria. The inner membrane, identified by its content of succinate dehydrogenase, contained the cholesterol side-chain-cleaving enzyme and very little cholesterol. 5. Accumulation of sterols by the mitochondria was studied by incubating this fraction with labelled free and esterified cholesterol suspended in lipid-free bovine serum albumin. Two phases of cholesterol accumulation were observed. The first phase, requiring 10–15min, was independent of the incubation temperature, and was inhibited by the presence of bovine serum albumin in the incubation medium. The second phase of accumulation was independent of the serum albumin content of the medium but was inhibited by low incubation temperature. 6. Esterified cholesterol was not accumulated by the mitochondria after the initial rapid binding phase. 7. The findings suggest that cholesterol was not rapidly accumulated by the mitochondrial fraction in vitro and that mechanisms may be required to facilitate cholesterol transport into mitochondria in intact tumour cells during the periods in which steroidogenesis is stimulated maximally.


1982 ◽  
Vol 35 (2) ◽  
pp. 179
Author(s):  
P Quinn

When human spermatozoa are incubated with zona-free ova in the presence of polyethylene glycol (PEG), the spermatozoa attach to the ova. Although the binding occurs when bovine serum albumin (BSA) is omitted from the incubation medium, the spermatozoa are better maintained and bind in higher numbers in the presence of both PEG and BSA. No spermatozoa bind to zona-intact ova or to zona-free ova in the absence of PEG. The number of spermatozoa bound to ova is dependent on the concentration of PEG (optimum between 10 and 15 % wjv), time of incubation (increases linearly) and concentration of spermatozoa (increases linearly).


2019 ◽  
Vol 86 (5) ◽  
pp. 855-860
Author(s):  
E. S. Gorodnichev ◽  
A. A. Kuleshova ◽  
A. V. Bykov ◽  
A. M. Saletsky

1969 ◽  
Vol 26 (5) ◽  
pp. 1392-1397 ◽  
Author(s):  
James E. Stewart ◽  
Diane M. Foley

The levels of fluorescent material in the hemolymph of lobsters injected with serum proteins from lobster hemolymph labelled with fluorescein remained relatively constant over a 6-day test period; the levels in lobsters injected with bovine serum albumin labelled with fluorescein declined rapidly. A precipitin-like reaction was observed when lobster hemolymph serum was titrated with bovine serum albumin in vitro.


2006 ◽  
Vol 16 (9) ◽  
pp. 2450-2453 ◽  
Author(s):  
Xiong-Jie Jiang ◽  
Jian-Dong Huang ◽  
Yu-Jiao Zhu ◽  
Fen-Xiang Tang ◽  
Dennis K.P. Ng ◽  
...  

2011 ◽  
Vol 284-286 ◽  
pp. 1764-1769 ◽  
Author(s):  
Vitalijs Lakevics ◽  
Janis Locs ◽  
Dagnija Loca ◽  
Valentina Stepanova ◽  
Liga Berzina-Cimdina ◽  
...  

Sorption experiments of bovine serum albumin (BSA) on hydroxyapatite (HAp) ceramic granules, prepared at three temperatures 900°C, 1000°C and 1150°C were performed at room temperature 18,6 °C and phosphate buffer, pH 5,83; 6.38 and 7,39. Thermal treatment contributed to the decrease of bovine serum albumin immobilization indicating that sorption process depended on HAp ceramics specific surface area and pH values of phosphate buffer solution. However, it was confirmed that granule size was also an important parameter for bovine serum albumin adsorption. As a result of these experiments, the most appropriate adsorption conditions and phosphate buffer pH values influence on to BSA sorption were analyzed.


2021 ◽  
Author(s):  
Alessandra Capezzone de Joannon ◽  
Angela Testa ◽  
Natalie Falsetto ◽  
Michela Procaccini ◽  
Lorella Ragni

Aim: Ethanol is highly effective at inactivating enveloped viruses, including SARS-CoV-2. The aim of this study is to evaluate the virucidal activity of Amuchina Gel Xgerm (74% ethanol) against SARS-CoV-2, according to the European Standard EN14476:2013+A2:2019. Materials & methods: Virucidal activity of the study product was evaluated against SARS-CoV-2 strain USAWA1/2020 in suspension, in the presence of 0.3 g/l of bovine serum albumin. Results: The log10 reduction of SARS-CoV-2 in the presence of bovine serum albumin was ≥4.11 ± 0.12 after 30 s of exposure to the study product (80% dilution). Cytotoxicity was observed in the 100 dilution, affecting the detection limit by 1 log10. Conclusion: Virucidal activity against SARS-CoV-2 supports the effectiveness of this alcohol-based formulation as a prevention measure for COVID-19 illness.


2008 ◽  
Vol 2 (1) ◽  
Author(s):  
Md Ashraful Alam ◽  
Md Abdul Awal ◽  
Mahbub Mostofa ◽  
Md Kamrul Islam ◽  
Nusrat Subhan

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