Showing papers on "Incubation published in 1970"

Amino acid incorporation in vitro into protein of neuronal and glial cell-enriched fractions.

Abstract: — Slices of rabbit cerebral cortex were incubated in the presence of labelled amino acids. Following incubation, neuron- and gliaenriched fractions were obtained by density gradient centrifugation and the TCA-insoluble radioactivity determined. The protein-bound radioactivity was five to six times higher in the neuronal-enriched fraction than in the glial-enriched fraction after incubation with tritiated leucine. The neuronal fraction incorporated also a number of other amino acids to a higher extent than the glial fraction (neuron/glia ratio 2·5-6). A definite dependence of incorporation on the rate of oxygenation was demonstrated. The suppression of amino acid incorporation was more marked for the neuronal fraction than for the glial fraction during incubation in relative hypoxia. An increase of potassium concentration in the incubation medium enhanced the amino acid incorporation in both fractions. Low sodium levels decreased the incorporation. Puromycin inhibited incorporation to approximately 30 per cent of control for both fractions. Addition of cycloheximide and dinitrophenol resulted in greater inhibition of incorporation in the neuronal fraction than in the neuroglial fraction. Actinomycin D did not markedly affect the incorporation in any fraction. These results are discussed in relation to in vivo and in in vitro differences for transport and incorporation of amino acids.

The testing of proven Trypanosoma brucei and T. rhodesiense strains by the blood incubation infectivity test.

Abstract: The authors describe a simple test (the blood incubation infectivity test) by which Trypanosoma brucei (sensu stricto) may be differentiated from T. rhodesiense without recourse to human volunteers. The method consists in incubating the strain of trypanosome under test for 5 hours at 37 degrees C in vitro in human blood, followed by observation of the effect of this procedure on the strain's infectivity to rats.Thirteen strains of T. rhodesiense were investigated; in each, the ability to infect rats was retained after incubation. In all 6 strains of man-tested T. brucei, it was destroyed.The consistency of the results with proven strains suggests very strongly that the blood incubation infectivity test provides a valid means of differentiating these parasites.

Transfer of immunoglobulins and antibodies in the hen's egg

Abstract: The presence of immunoglobulins and antibodies were investigated in the fertile hen's egg during embryogenesis. The egg yolk, egg albumin, amniotic and allantoic fluids, chick embryo serum and intestinal contents were examined for the presence of immunoglobulin and level of antibodies. Immunoglobulin G was not detected in fresh egg albumin, but appeared in the albumin from the 4th day of embryogenesis and persisted through the 16th day. The antibody profile of egg albumin during embryogenesis attained two peaks, which were separated by a trough on the 8th day of embryogenesis. The immunoelectrophoretic pattern of albumin IgG was different from that of egg yolk IgG. The IgG of chick embryo serum was of γ2 mobility on the 12th day of incubation and shifted gradually to the full range of γ1 and γ2 mobilities on the 20th day of incubation. Egg-transmitted antibodies appeared on the 12th day of incubation and attained peak values on the 16th day of incubation. Moderate antibody levels were detected in the amniotic and allantoic fluids from the 12th to the 18th days of incubation.

Synthesis and release of proinsulin and insulin by isolated rat islets of Langerhans

Abstract: Isolated rat islets of Langerhans were incubated for 60, 120, and 180 min and the incorporation of leucine-3H into proinsulin and insulin moieties was followed. Synthesis and release of these hormones could be followed by separate extractions of islets and incubation media. Release of newly synthesized proinsulin and insulin occurred under the following conditions: (a) incubation for greater than 60 min; (b) glucose concentrations above 5.3 mmoles/liter; (c) incubation with 5 mM dibutyryl cyclic AMP or theophylline in 5.3 mM glucose (potentiated by 16 mM glucose); and (d) incubation with 5 mM tolbutamide and 16 mM glucose. Synthesis of proinsulin and insulin was enhanced by time of incubation, high glucose concentrations, by dibutyryl cyclic AMP or theophylline, and by tolbutamide only at 16 mM glucose. Synthesis was totally inhibited by tolbutamide at 5.3 mM glucose.

Stimulation of piriform- and neo-cortical tissues in an in vitro flow-system: metabolic properties and release of putative neurotransmitters.

Abstract: — (1) Multiple samples from the piriform cortex and neocortex of the guinea pig were maintained in separate incubation vessels through which incubation solutions based on Krebs-Ringer bicarbonate glucose media were caused to flow for chosen periods at specified rates. (2) The tissues were held in defined positions in relation to electrodes; in some experiments electrical stimuli were applied and in others incubation media were changed with respect to their oxygen, K+ or glutamate content. (3) With media flowing at 3–4 ml/min, the incubated tissues were similar in contents of K salts and phosphocreatine, and in rate of glycolysis to those incubated in non-flowing media. The tissues responded to electrical stimulation by increase in glycolysis and decrease in phosphocreatine and K content. (4) During pre-incubation periods in non-flowing media, samples of piriform cortex were exposed to solutions containing 3H-labelled glycine, noradrenaline or 5-hydroxytry-ptamine and on anlaysis were found to contain the labelled compounds at concentrations four to seven times those of the surrounding media. The labelled compounds were gradually released into the flowing incubation media, and the release of noradrenaline and 5-hydroxytryptamine was accelerated by electrical stimulation. (5) Release of the two bases was also modified by added reagents and the course of their release is discussed in relation to other metabolic changes concomitantly observed.

Possible Requirement of Adenosine Triphosphate for the Rejoining of X-ray-induced Breaks in the DNA of Ehrlich Ascites-tumour Cells

Abstract: SummaryChanges in the metabolism of Ehrlich ascites-tumour cells were examined after in vitro incubation under nitrogen at 1 atmosphere in phosphate-buffered saline in the absence of glucose, conditions which do not allow the rejoining of x-ray-induced breaks in the DNA.There was a marked reduction in the incorporation of radioactive precursors into DNA, RNA, protein, and TTP under these conditions compared with incubation in air. The reduction was partially or completely abolished by adding glucose to the incubation medium. After incubation under nitrogen without glucose, the intracellular content of ATP was greatly decreased. This decrease was also partially prevented by the addition of glucose. No significant change was observed in the content of NAD in the cells incubated under similar conditions.It was concluded that ATP is probably necessary for the rejoining of x-ray-induced breaks in the DNA of the ascites-tumour cells.

The Effect of Temperature on the Rate of Development and Survival of Alewife Eggs and Larvae

Abstract: Eggs from Lake Michigan alewives (Alosa pseudoharengus) were incubated at 79 different temperatures from 42.1 to 87.0 F. Hatching occurred at 44.4–84.9 F and was optimum (38% hatched) at about 64 F. Incubation time varied from 15 days at 45 F to 3.7 days at 70 F and 2.1 days at 84 F. Time from start to finish of hatching ranged from 13 days at about 46 F to 2–3 days at 68–70 F and 1–2 days at 80–84 F. Survival of unfed larvae held at incubation temperatures increased from 3.8 days at 51 F to 7.6 days at 58–59 F and then decreased to 2.4 days at 80–82 F.

Synthesis of nucleic acids and proteins in the dimorphic forms of Candida albicans

Abstract: Candida albicans grown in tissue culture medium 199 buds when incubated at 25°C. but produces filaments when incubated at 37°C. Macromolecular synthesis by budding and filament producing blastospores of C. albicans grown at these 2 temperatures of incubation was studied. Cells incubated at 25°C. reproduced by budding with a generation time of 2 hr. The dry weight, protein and DNA increased 2-fold as the cells doubled in number while the RNA content of such cells increased about 3·2-fold. Ninety-five per cent of cells incubated at 37°C. produced filaments in 3 hr. A net increase in protein of 49% and in RNA of 94% was detected within the first 2 hr. of incubation at 37°C. By 4 hr. incubation protein had increased to 220% of the initial value and RNA to 300%. DNA content did not increase during the first 2 hr. of incubation but by 3 hr. the DNA content had increased to 50% of the initial value. Electrophoretic analysis of the water soluble proteins from budding and filament producing cells revealed that bot...

Total soil nitrogen and nitrogen mineralization

Abstract: The mineralization capacity of 24 different soils was determined from incubation experiments. Relatively rapid mineralization and nitrification was found with soils from cultivated land, and pastures, but soils under natural vegetative covers of conifers and hardwoods were mostly ammonifying. A close relationship could be established between the total nitrogen content of the soil and the amount of mineral nitrogen formed during incubation. Important connections could also be shown between the available nitrogen contents at different times during the incubation period; these suggest that the incubation period can be considerably shortened.

Fungi in foods--i. effect of inhibitor and incubation temperature on enumeration

Abstract: Antibiotics were far superior to acidification for controlling bacteria when counting fungi in foods. Yeast and mold counts from Potato Dextrose Agar containing antibiotics were much higher than those obtained in the acidified medium, and growth of bacteria was never a problem. When incubation temperatures of 32 and 22 C were compared, more colonies appeared at 22 C.

Decomposition of the organic materials from hill soils and pastures. I. Incubation method for studying the mineralisation of carbon, nitrogen and phosphorus.

Abstract: Plant materials and sheep faeces from 2 hill sites were used to develop a method suitable for measuring the production of CO2 and mineral N and P during incubation with aqueous soil extract. Variation in sample size (2 or 5 g) and source of the extract inoculum (from A0 or A1 soil horizon) had little effect on the results, but production of mineral N and P was reduced in the absence of any inoculum. Nitrogen was lost during incubation in both open and closed systems, but by absorption of evolved ammonia in 50% sulphuric acid almost complete recovery of nitrogen was achieved in the closed system. More NH3, nitrate-N and CO2 were produced at 25% moisture-holding capacity than at 100%, but variation in moisture content had little effect on ammonium-N production. Lowering the incubation temperature resulted in reduced production of CO2 and mineral-N and P, but sheep faeces produced most ammonium-N at 10°.

Incubation effects in behavior induction in rats.

Abstract: Incubation (rest) periods interposed during donor training regimens significantly enhance the "memory transfer" effect reported by some investigators. When extracts from ihe brains of donor rats given interpolated rest during acquisition training were injected into recipient animals, statistically reliable and experimentally reproducible "memory transfer" effects were found.

Prolonged Incubation Behaviour of Red-Winged Blackbird Incubating Several Egg Sizes

Abstract: [New records for prolonged incubation of eggs are summarized The advantages for adaptation to a prolonged period of incubation only a few days longer than the normal incubation period is discussed Non-passerines tend to remain on unhatched eggs for a relatively longer period of time compared to normal incubation period length than do passerines, with such notable exceptions as Columbids Experiments were performed on wild incubating Red-winged Blackbird (Agelaius phoeniceus) females to determine some of the roles of the egg as a stimulus in prolongation of incubation Five sizes of eggs of normal shape and color were introduced into nests after the normal clutch was complete Very small or very large eggs were nearly always abandoned immediately Normal size eggs and eggs ½X and 1½X the dimensions of normal eggs were usually incubated More of the ½X eggs were abandoned on the first or second day than in the 1X and 1½X sizes and the mean length of incubation was 1506, 1938 and 1913 days, respectively There was no difference in the mean length of incubation on the 1X and 1½X eggs There was a significantly longer incubation on iX and 1½X eggs than on ½X eggs It is concluded that 1½X eggs were not super-normal stimuli but that ½X eggs were sub-normal stimuli for prolonging incubation Hypotheses are developed for explaining the differences in the stimulating capacities of different egg sizes The incubation patch as a receiver of stimuli may play a primary role The physiological condition of the incubating female especially with regard to levels of different hormone titers may be most important in maintaining the incubation patch as an effective receiver of stimuli The shape of the original nest, size of eggs and size of the female also may determine how much surface area of the brood patch is in direct contact with eggs, New records for prolonged incubation of eggs are summarized The advantages for adaptation to a prolonged period of incubation only a few days longer than the normal incubation period is discussed Non-passerines tend to remain on unhatched eggs for a relatively longer period of time compared to normal incubation period length than do passerines, with such notable exceptions as Columbids Experiments were performed on wild incubating Red-winged Blackbird (Agelaius phoeniceus) females to determine some of the roles of the egg as a stimulus in prolongation of incubation Five sizes of eggs of normal shape and color were introduced into nests after the normal clutch was complete Very small or very large eggs were nearly always abandoned immediately Normal size eggs and eggs ½X and 1½X the dimensions of normal eggs were usually incubated More of the ½X eggs were abandoned on the first or second day than in the 1X and 1½X sizes and the mean length of incubation was 1506, 1938 and 1913 days, respectively There was no difference in the mean length of incubation on the 1X and 1½X eggs There was a significantly longer incubation on iX and 1½X eggs than on ½X eggs It is concluded that 1½X eggs were not super-normal stimuli but that ½X eggs were sub-normal stimuli for prolonging incubation Hypotheses are developed for explaining the differences in the stimulating capacities of different egg sizes The incubation patch as a receiver of stimuli may play a primary role The physiological condition of the incubating female especially with regard to levels of different hormone titers may be most important in maintaining the incubation patch as an effective receiver of stimuli The shape of the original nest, size of eggs and size of the female also may determine how much surface area of the brood patch is in direct contact with eggs]

An improved holder for transfer of brain slices during in vitro incubation

Abstract: A new type of tissue holder is described in which the slices are freely floating. Rat brain-cortex slices incubated in this holder show a potassium concentration of 70.4 μmoles/g final wet wt. after incubation and transfer for 1 hr.

Effects of hemorrhagic shock and treatment with hypothermia on the potassium content and transport of single mammalian skeletal muscle cells.

Abstract: The effect of in vivo hemorrhagic shock and its treatment with hypothermia was studied by following the temporal pattern of intracellular potassium content in single skeletal muscle fibres during in vitro incubation. For the control cells isolated before the different experi mental procedures were instituted, reproducible changes in potassium content were observed during the period of incubation. The potassium content of cells isolated shortly after the taking of the biopsy was somewhat lower than of cells isolated after 10 min of incubation. After 10 to 15 min of incubation a marked loss of cellular potassium was seen, followed by a period of active reaccumulation. After hemorrhagic shock under normothermal conditions the potassium content of the cells was markedly lower and no active cellular potassium reaccumulation was obtained during prolonged incubation. Hemorrhagic shock treated with hypothermia lowered the initial pptassium content somewhat but both the periods of cellular potassium loss and active reaceumulation were seen. Hypothermia alone only slightly modified potassium transport during the first 10 to 15 min of in vitro incubation. The results are discussed from the standpoint of cellular metabolism and high-energy phosphate production with special reference to the exchange of substances between body com partments under the diffrent experimental conditions.

Effects of gamma irradiation on the available nitrogen status of soils

Abstract: Five Hawaiian soils were irradiated at various levels of gamma irradiation and analysed for available (NH4 and NO3) nitrogen content immediately after irradiation, and after periods of incubation. The release of NH4-N generally increased with increasing dosages in all soils, while NO3-N decreased in some soils. Incubation studies showed that the loss of NO3-N continued even after several days of irradiation. The rate of NH4-N mineralisation in irradiated soils was highest during the first seven days and declined later on.