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Showing papers on "Incubation published in 1969"


Journal ArticleDOI
TL;DR: An early function in translation is shown to be rate limiting at the elevated temperature and is the cause of polyribosome disaggregation and an RNA factor is produced which appears to promote the association of ribosomes with messenger RNA.

281 citations


Journal ArticleDOI
TL;DR: Two mouse-adapted scrapie agents of different sheep origin were compared: the titre, reached in the brains of mice in the terminal stage of scrapie, is of the same order for both agents, and the implications of this type of host-genotype, agent-strain interaction are discussed.
Abstract: Two mouse-adapted scrapie agents of different sheep origin were compared. The titre, reached in the brains of mice in the terminal stage of scrapie, is of the same order for both agents. There is a threefold difference between the incubation periods of the two agents in some mouse strains, of which C57 is one, and in this strain incubation of the 22A agent, given as a large dose by a peripheral route, occupies almost the whole life-span.The most fundamental difference between the agents concerns the reversal of the ranking of incubation periods, typically in the VM and C57 mouse strams: incubation of ME7 in VM takes almost twice as long as in C57, whereas most sub-lines of 22A take half as long in VM as in C57. The implications of this type of host-genotype, agent-strain interaction are discussed in terms of the possible nature of agent differences, the possibility of latent infection and the consequences for scrapie eradication programmes.

136 citations


Journal ArticleDOI
TL;DR: In this paper, the authors derived the incubation times and frequency factors for some cases of heterogeneous nucleation on grain boundaries and showed that an energetically favorable reaction possibly may not occur if another reaction with a smaller incubation time is possible.

107 citations


Journal ArticleDOI
TL;DR: A rapid recovery of the maltose-uptake system occurred when inactivated cells were incubated in a maltose nutrient medium; protein synthesis appeared to be a prerequisite for the recovery process.

104 citations


Journal ArticleDOI
TL;DR: Air cell temperatures were the same for eggs incubated in light and dark suggesting that the phenomenon observed is due to light rather than temperature.

75 citations


Journal ArticleDOI
TL;DR: The ability of liver slices from chicks and hens to utilize acetate-1- 14 C for lipid synthesis and oxidation to CO 2 was found to be similar.

68 citations


Journal ArticleDOI
TL;DR: In this article, incubations of soil with 14C-stareh and 14Cglucose were studied under laboratory conditions, and the results showed that the total glucose in the mixtures rapidly decreased but the amounts of other sugars present showed little change during incubation.
Abstract: To gain information about the breakdown and synthesis of carbohydrate, incubations of soil with 14C-stareh and 14C-glucose were studied under laboratory conditions. Carbon dioxide was liberated equivalent to 60–80 per cent of the substrate during incubation of soil with glucose (14 days) and with starch (84 days). The carbohydrate content of the hydrolysate of the substrate-soil mixture returned almost to the initial soil value within 35 days of incubation with 0.5 per cent starch, and within 7 days with 1 per cent glucose. The total glucose in the mixtures rapidly decreased but the amounts of other sugars present showed little change during incubation. To obtain the specific activities of sugars present in the hydrolysate various methods of separation were used including charcoal column, Celite column, and paper chromatography of the free sugars, and resin column chromatography of their borate complexes. With both substrates there was a rapid redistribution of 14C amongst the sugars. Galactose and mannose acquired considerable activity in all cases, rhamnose and fucose became labelled in one experiment, but arabinose and xylose were not labelled. This pattern of distribution remained unchanged with further incubation and glucose remained the most highly labelled sugar (70–80 per cent of total sugar radioactivity) for as long as the incubations were studied.

57 citations


Journal ArticleDOI
TL;DR: In this article, the authors studied natural and hormonally induced incubation patch development in the California quail, Lophortyx californicus, and found that the quail patch was not as edematous as is that of passerine birds.

53 citations


Journal ArticleDOI
TL;DR: Spermine and spermidine reach maximum concentrations in the chick embryo brain between the 12th and 14th day of incubation, and an increased radioactivity in the region of 147 S, 206 S, 259 S and 280 S in embryos injected with spermine or sperMidine is found.
Abstract: — Spermine and spermidine reach maximum concentrations in the chick embryo brain between the 12th and 14th day of incubation. Sucrose-density-gradient analysis of polyribosome distribution in the developing chick embryo brain, showed the presence of polyribosomal aggregates in the regions of 147 S and 206 S between the sixth and eighth day of incubation. After the 16th day of incubation the presence of heavier polyribosomal aggregates in the region of 259 S and 280 S was found. The injection of spermine or spermidine into the air space of embryos on the tenth day of incubation leads to a remarkable increase in the incorporation rate of [3H]formate into the ribosomes. Studies under similar experimental conditions, showed an increased radioactivity in the region of 147 S, 206 S, 259 S and 280 S in embryos injected with spermine or spermidine.

44 citations


Journal ArticleDOI
TL;DR: The ionic parameters of incubation media which foster both the development and subsequent reduction of swelling of slices of cerebral cortex under isosmotic conditions of incubations in vitro are described and proposals for possible clinical applications are suggested.
Abstract: The ionic parameters of incubation media which foster both the development and subsequent reduction of swelling of slices of cerebral cortex under isosmotic conditions of incubation in vitro are described. A linear relationship between increasing chloride concentrations in incubation media and progressive swelling of tissue slices (under conditions of constant temperature and K+ concentrations and isotonicity of incubation media) is demonstrated. Subsequent reduction of chloride concentration in incubation media together with reciprocal replacement by isethionate is associated with significant and characteristic reduction in the volume of tissue swelling when all other conditions of incubation, including isotonicity of the media, are kept constant. The ionic composition of the fluid of swelling under different conditions of incubation is derived together with the ionic composition and expected transmembrane potentials of the neuronal compartment of cerebral cortex in vitro. Mechanisms involved in the development and subsequent reduction of swelling of cerebral cortex in vitro are discussed, and proposals for possible clinical applications are suggested.

42 citations


Journal ArticleDOI
TL;DR: Radioautography indicated that during this period there was a continuous increase in the radioactivity present in the acid-insoluble fractions of the root and leaf tissues relative to thatpresent in the coleorhiza and coleoptile.
Abstract: 1. Both the acid-soluble fraction and the nucleic acid fraction of wheat embryos were extensively labelled after incubation for 6hr. in the presence of [8-(14)C]adenine. Subsequent incubation in the absence of labelled adenine resulted in no loss of radioactivity to the medium during a 48hr. period. Radioautography indicated that during this period there was a continuous increase in the radioactivity present in the acid-insoluble fractions of the root and leaf tissues relative to that present in the coleorhiza and coleoptile. 2. During incubation at 25 degrees there was a 26-fold increase in the activity of 3'-nucleotidase between 4hr. and 24hr.; the activities of enzymes hydrolysing AMP and IMP increased to a smaller extent. The activities of adenine phosphoribosyltransferase and hypoxanthine phosphoribosyltransferase increased three- to five-fold during incubation at 25 degrees for 24hr. 3. Adenosine kinase, inosine phosphorylase and 5-phosphoribosyl pyrophosphate synthetase activities were high in extracts from dry embryos and did not increase during 48hr. at 25 degrees . 4. The increase in 3'-nucleotidase activity was prevented by cycloheximide, cryptopleurine or incubation at 4 degrees , but not by actinomycin D; these treatments did not depress the activity of the other enzymes measured. 5. The results are discussed in relation to RNA translocation within the wheat embryo during germination.

Journal ArticleDOI
TL;DR: Removal of oxygen from the gas phase increased leakage and abolished the active uptake of inositol, effects which could not be prevented by the addition of energy sources such as glucose and ATP.

Journal ArticleDOI
TL;DR: Analysis of cold-acid extracts of Euglena gracilis cells indicates that the two kinds of cells contain about the same concentrations of pool amino acids, but that the low-carbon cells contain somewhat higher concentrations of peptides in the pool.
Abstract: 1. Cells of Euglena gracilis grown in the dark on high ratios of carbon source to nitrogen source (‘high-carbon cells’) are unable to form chlorophyll during a subsequent incubation in the light; cells grown in the dark on low ratios of carbon to nitrogen (‘low-carbon cells’) synthesize chlorophyll at a rapid rate during the subsequent incubation in the light. High-carbon cells will form chlorophyll rapidly if supplied with a nitrogen source during the incubation in the light: of the nitrogen sources tested, ammonium sulphate was the most effective at overcoming the block in chlorophyll synthesis. The nitrogen source does not have to be present during the actual incubation in the light: a 5hr. exposure of high-carbon cells to ammonium sulphate in the dark, followed by removal of the nitrogen source, is sufficient to bring about rapid chlorophyll synthesis during a subsequent incubation in the light. 2. The synthesis of chlorophyll by low-carbon cells exposed to the light is strongly repressed by the addition of ethanol or other utilizable carbon sources during the incubation in the light. Chlorophyll synthesis ceases altogether between 5 and 10hr. after the addition of the carbon source. Carotenoid synthesis is also inhibited, but to a smaller extent. The inhibitory effects of ethanol are prevented if ammonium sulphate is added at the same time. 3. High-carbon cells contain about four times as much carbohydrate per cell and about twice as much lipid per cell as low-carbon cells. The content per cell of total protein, soluble protein and DNA are about the same in both types of cell. The low-carbon cells sometimes, but not always, contain more RNA than the high-carbon cells. Analysis of cold-acid extracts indicates that the two kinds of cells contain about the same concentrations of pool amino acids, but that the low-carbon cells contain somewhat higher concentrations of peptides in the pool. Ion-exchange analysis of pool extracts shows a number of differences between high-carbon and low-carbon cells with respect to the concentrations of individual amino acids: in particular low-carbon cells contain higher concentrations of alanine. High-carbon cells have approximately twice as much protease activity as low-carbon cells. 4. The possible biochemical basis for the differing ability of high-carbon and low-carbon cells to form chloroplasts in the light is discussed.

Journal ArticleDOI
TL;DR: The enzyme responsible for ACh synthesis, choline acetyltransferase, is stable at incubation temperatures higher than previous acclimation temperatures, and the activity of the enzyme is greater at higher acclimated temperatures.

Journal ArticleDOI
TL;DR: The purpose of the present study was to attempt to define some of the lesspolar metabolites of testosterone formed by rat brain in vitro and to ascertain if brain from another animal source would produce the same or different metabolites under similar conditions of incubation.
Abstract: Rat and bovine brain have been incubated with testosterone-4-14C under standard conditions. With use of paper chromatography, the extracted metabolites were noted to fall into less-polar, iso-polar, and more polar fractions. The components of the less-polar fraction were separated by acetylation and thin-layer chromatography and the major end-products identified by recrystallization to constant specific activity or constant 3H/14C ratios. Androst-4-enedione and 5\\g=a\\-dihydrotestosteronewere formed consistently under the conditions utilized. Trace amounts of other less-polar metabolites were noted occasionally. That mammalian brain is capable of metabolizing steroid substrates under in vitro conditions has been well-established (Grosser 8c Bliss 1963, 1966; Peter¬ son et al. 1965; Sholiton et al. 1965, 1966). When cortisol, cortisone, 11/3hydroxy-androstenedione or adrenosterone are used as substrate, the major enzymatic activity of rat brain appears to be the equilibration of the 11-keto: 11-hydroxy position. More recently, we have incubated rat brain with testosterone-4-14C, a steroid in which no Ojxygen function is present at the C-ll position (Sholiton et al. 1966). Under the conditions utilized, about 10 per cent of the original radioactive substrate was metabolized to end-products more polar and less-polar than the substrate (Fig. 1). The purpose of the present study was to attempt to define some of the lesspolar metabolites of testosterone formed by rat brain in vitro and to ascertain Downloaded from Bioscientifica.com at 11/10/2018 03:48:53AM via free access if brain from another animal source (in this instance, bovine) would produce the same or different metabolites under similar conditions of incubation. METHODS AND MATERIALS* Incubation of 1 gram aliquots of rat and bovine brain with a standard amount of testosterone-4-14C was performed as previously described (Sholiton et al. 1966). Rat brain was freshly resected from male and female adult virgin Wistar rats immediately upon decapitation. Bovine brain was secured at a local abattoir immediately upon removal and chilled with ice. With the latter, 1 gram aliquots for incubation were obtained from cerebral cortex, cerebral peduncles and hypothalamus. Homogenization was performed with a 10 ml glass homogenizer and incubation was carried out in a Dubnoff shaker (atmosphere: 95% oxygen, 5 %> CO9) for a 5-hour period at 37°C. The incubation was fortified with a NADPH-generating system provided by the addition of the following: nicotinomide-adenine-dinucleotide (NADP), IO-3 M, and glucose-6-phosphate (G-6-P), IO-2 M. To each incubation 10 ml of freshly prepared Krebs-Ringer bicarbonate buffer (pH 7.4) was added. The incubation was terminated by the addition of glacial acetic acid followed by immediate freezing. Extraction was accomplished with the use of ethyl acetate following addition of sodium sulfate, 20 % by weight. The organic phase was evaporated to dryness under reduced pressure and the extract was then taken up with re-distilled chloroform. The chloroform extract was applied to a Florosil® column (15 mm diameter, packed to 88 mm in height) and eluted with 4 % methanol in chloroform. The latter was taken to dryness and re-diluted with 1 ml of absolute methanol. Recovery of radioactivity in the above manipulations was determined in several incubates. About 95 %> of ori¬ ginal substrate radioactivity was noted in the ethyl acetate extract with 75 °/o of initial radioactivity obtained in the 4 % methanol in chloroform fraction. Further column elution with 10°/o methanol in chloroform and 25% methanol in chloroform yielded less than 2 % of total radioactivity. Hence, only the 4 % methanol in chloro¬ form eluate was utilized for further Chromatographie separation. Paper Chromatographie separation of the methanolic extract was accomplished on * Glossary of Trivial Names: Adrenosterone: androst-4-ene-3,l 1,17-trione. Aetiocholanolone: 3a-hydroxy-5/?-androstan-l 7-one. 5a-Androstanedione: 5a-androstane-3,l7-dione. Androst-4-enediol: 3a,17/?-dihydroxy-androst-4-ene. Androst-4-enedione: androst-4-ene-3,17-dione. Androsterone: 3«-hydroxy-5a-androstan-l7-one. Cortisol: ll/?,17,21-trihydroxy-pregn-4-ene-3,20-dione. Cortisone: 17,21-trihydroxy-pregn-4-ene-3,l 1,20-trione. Dehydroc/ii'androsterone: 3/?-hydroxy-androst-5-en-l 7-one. 5a-Dihydrotestosterone: 5a-androstan-17/?-ol-3-one. £/;¿testosterone: 17a-hydroxy-androst-4-en-3-one. 1 l/S-Hydroxy-androstenedione: 11/?-hydroxy-androst-4-ene-3,l 7-dione. 20/?-Hydroxycortisol: ll/?,17,20/?,21-tetrahydroxy-pregn-4-en-3-one. Testosterone: 17/?-hydroxy-androst-4-en-3-one. Tetrahydrocortisol: 3a, 11/5,17,21 -tetrahydroxy-5/5-pregnan-20-one. Downloaded from Bioscientifica.com at 11/10/2018 03:48:53AM via free access Whatman No. 3 MM paper strips (3 cm wide) in system iso-octane:methanol:water (10:8:2) for 6 h at 22°C. A radioscan of the chromatogram revealed three primary peaks of metabolic radioactivity (Fig. 1) for both the bovine and rat incubates and in the rat a small secondary peak which migrated further than the less-polar peak (peak No. 2). Further separation of the metabolites of the less-polar metabolic pool was obtained in the following manner. The less-polar peaks were eluted from the paper chromato¬ gram with methanol. The eluates were then acetylated using a standard technique involving overnight incubation with anhydrous pyridine, acetic anhydride (1:1 v/v) (Kliman Se Peterson 1960). The acetylated derivatives were separated by the applica¬ tion to an alumina-gel G thin-layer Chromatographie system (methylene-chloride: chloroform 97:3) run at room temperature for 45 min. Unexposed X-ray film (Ansco high-speed Supreme Emulsion) was applied to the Chromatographie plate for 72 h (Fig. 2). The X-ray film was then developed and exposed areas were correlated with identical areas on the alumina-gel plate. These areas were removed from the plate and eluted with ethyl-acetate, sodium-sulphate and water. The organic phase was then pipetted into an evaporating dish and taken to dryness. The radiometabolites were reconstituted with methanol and an aliquot counted in toluene phosphor with a Packard Tri-Carb liquid scintillation spectrophotometer. Identification of radiometabolites was accomplished by using established techniques for comparison of Chromatographie mobilities of unknowns and acetylated derivatives against standard reference compounds, by derivative formation, and finally by re¬ crystallization to constant specific activity (Tables 1 and 2). Recrystallization to con¬ stant 3H/14C ratios was accomplished with both androst-4-enedione and aetiocholano¬ lone by the use of tritiated standards to which the 14C radiometabolite had been added.

Journal ArticleDOI
TL;DR: In a new incubation system, liver slices from rat have been shown to incorporate glucose into lipids, which are released into the incubation medium, stimulated by insulin with a proportionally more marked increase in esterified fatty acids than in free fatty acids.
Abstract: In a new incubation system, liver slices from rat have been shown to incorporate glucose into lipids, which are released into the incubation medium. This synthesis was stimulated by insulin with a proportionally more marked increase in esterified fatty acids than in free fatty acids.

Journal ArticleDOI
TL;DR: It is concluded that the enzyme that splits 2-acetamido-1-l-beta-aspartamido -1,2-dideoxy- beta-d- glucose is an amidase and there was spontaneous liberation of ammonia from this compound on prolonged incubation.
Abstract: 1. The activity of the enzyme that splits 2-acetamido-1-l-β-aspartamido-1,2-dideoxy-β-d- glucose (1-aspartamido-β-N-acetylglucosamine) was measured in tissues from different mammalian species. 2. The enzyme from an aqueous extract of rat liver was purified 150-fold in 56% yield. 3. Optimum activity for the hydrolysis of 1-aspartamido-β-N-acetylglucosamine was at pH7, and ammonia and N-acetylglucosamine were liberated in equimolar amounts. At pH8·5, 1-amino-N-acetylglucosamine was the only sugar produced after short periods of incubation. On prolonged incubation there was spontaneous liberation of ammonia from this compound. 4. It is concluded that the enzyme is an amidase.



Journal ArticleDOI
TL;DR: Comparison of the condition of the epidermis with pituitary prolactin content revealed interesting relationships between synthesis and release of this hormone throughout the quail reproductive cycle, indicating that the incubation of eggs stimulates release of Prolactin from the pituitaries.

Journal ArticleDOI
TL;DR: The addition of oxygen at the beginning of incubation inhibited methane production and increased the accumulation of hydrogen, and when the oxygen was infused continuously there was a net uptake of oxygen by micro-organisms.
Abstract: 1. The effect of oxygen on the fermentation of sucrose by mixed rumen micro-organisms in vitro was studied by adding oxygen to the gas phase in three ways: at the beginning of incubation, at two hourly intervals during incubation and continuously.2. The additions of oxygen had no measurable effect on the utilization of sucrose or on the production of carbon dioxide, steam-volatile acids and particulate organic matter by the micro-organisms. The addition of oxygen at the beginning of incubation inhibited methane production and increased the accumulation of hydrogen. Similar but much less pronounced changes occurred when the oxygen was infused continuously.3. In all the experiments there was a net uptake of oxygen by micro-organisms. When large amounts of oxygen were present in the gas phase the rates of uptake were proportional to these amounts. When small amounts of oxygen were added, the rates of uptake were independent of the amount added and had a value of approximately 5 ml/h when 100 ml of strained rumen contents were incubated.

Journal ArticleDOI
TL;DR: In this article, three fermentation trials were conducted using cellulose, ground corn, and sucrose as substrates, and a factorial arrangement was used to study the effects of 0, 3, 6, 9, and 12% sucrose levels, 30 and 70% cellulose levels, and incubation periods of incubation at 39C on pH, lactate concentration, and volatile fatty acid proportions of the medium.


Journal ArticleDOI
TL;DR: Inhibition of spore germination was found to be directly correlated with the strength of the radiation dose and indirectly correlated to the spore concentration, and Penicillium expansum was the most sensitive to radiation both in culture and in fruit tissues.

Journal ArticleDOI
TL;DR: Strains of Leuconostoc citrovorum were compared for their growth characteristics in sterile skimmilk at 22 and 30C and generally chains formed by the cultures tended to be longest after 10 to 14 hr of incubation, regardless of temperature.

Journal ArticleDOI
TL;DR: It is indicated that insulin stimulates carbohydrate metabolism in larval Taenia crassiceps (Cestoda) when incubated in vitro for 2 hours in glucose and insulin fortified Eagle's medium; glucose uptake, lactic acid production, and glycogenesis were all stimulated under these conditions.

Journal ArticleDOI
TL;DR: In this article, the autolysis of the cells of Str. cremoris and L. helveticus was investigated by shaking these cells suspended in M/15 phosphate buffer, under starvation condition, pH 7.0, at 35°C for 10 days.
Abstract: Autolysis of the cells of Str. cremoris and L. helveticus, both of which were harvested from the liquid culture after 48 hr cultivation, were investigated by shaking these cells suspended in M/15 phosphate buffer, under starvation condition, pH 7.0, at 35°C for 10 days. Both amounts of nitrogen and DNA substance released from the cells of Str. cremoris were about 20%o after 3 days incubation but the amounts of the nitrogen and DNA substance released from the cells of L. helveticus were about 20% and 60%, respectively, after 3 days incubation. Those values obtained from two kinds of bacteria became almost constant after 10 days incubation. Proteolytic activities in supernatants prepared from these two cell suspensions were detected after 3 days incubation and the maximum activities were attained after 6 days incubation. The activities of lactic dehydrogenase released from Str. cremoris and L. helveticus during cultivation in skim milk were detected even after one day cultivation. These indicate that autolysis of both kinds of lactic acid bacteria occurred only after one day cultivation in milk even under condition rich in nutrients, and intracellular protease, which could hydrolyze milk protein, αs casein, was released.

Journal ArticleDOI
TL;DR: The stimulation produced by glucose upon protein biosynthesis in testes from adult rats was investigated in order to determine whether glucose increases the transport of amino acids into the cells of the testis and if so whether glucose also increases some aspect ofprotein biosynthesis other than amino acid transport.
Abstract: The stimulation produced by glucose upon protein biosynthesis in testes from adult rats was investigated in order to determine whether glucose increases the transport of amino acids into the cells of the testis and if so whether glucose also increases some aspect of protein biosynthesis other than amino acid transport 1 Increasing concentration of lysine-14C in the incubation medium did not prevent glucose from stimulating the incorporation of the amino acid into testicular protein within the range of concentration examined However, glucose increased the concentration of free lysine-14C in the testis within the first 5 min of incubation and when protein biosynthesis was inhibited by puromycin, glucose increased the concentration of lysine-14C above control values (no glucose added) at all periods of incubation tested Moreover, when the specific activity of free lysine-14C and of protein was measured in the same sample of tissue, glucose increased the specific activity of free testicular lysine-14C abo

Journal ArticleDOI
TL;DR: The temperature of incubation affected the typability of beta-hemolytic group A streptococci by T-agglutination tests, and incubation at the lower temperature was required for successful typing of higher percentages of strains from the skin and other clinical sources than from the throat.
Abstract: The temperature of incubation affected the typability of beta-hemolytic group A streptococci by T-agglutination tests. When strains could not be typed after routine incubation at 30 C, they were incubated at 22 to 25 C, and nearly a 10% increase in typability was achieved. The clinical source of the strains was related to their typability. Incubation at the lower temperature was required for successful typing of higher percentages of strains from the skin and other clinical sources than from the throat. Sixty per cent of the skin strains were represented by six serotypes. Of these, 53% of the strains required incubation at 22 to 25 C before they could be typed.

Journal ArticleDOI
TL;DR: A method is described by which sufficient spermatozoa can be separated rapidly from their incubation medium to assay individual metabolites accumulating from [U·14C]fructose, and the main intracellular metabolite was Acetate.
Abstract: A method is described by which sufficient spermatozoa can be separated rapidly from their incubation medium to assay individual metabolites accumulating from [U·14C]fructose. Acetate and lactate made up 60-80% of the substrate carbon accumulated within the cell. Acetate was the main intracellular metabolite and its concentration in the cell was 10-20 times its extracellular level. The intra-cellular accumulation of lactate varied with the period of incubation but its concen-tration in the cell was always below that in the medium. The remaining substrate carbon in the cell was made up of fructose and at least three other unidentified compounds. No accumulation of substrate carbon was detected in citric acid cycle intermediates.