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Showing papers on "Incubation published in 1992"


Journal ArticleDOI
TL;DR: Observations are consistent with the hypothesis that the preimplantation mammalian embryo produces a factor(s) which can stimulate its own development and have implications for clinical in-vitro fertilization, where embryos are routinely cultured individually in relatively large volumes.
Abstract: The morphology, cleavage rate and viability of preimplantation embryos from random bred Swiss mice were assessed after culture in different incubation volumes and embryo densities. Decreasing the incubation volume, from 320 to 20 microliters, significantly increased blastocyst cell number (P less than 0.01) and embryo development after transfer (P less than 0.01). Increasing the number of embryos incubated per drop from 1 to 16 significantly increased the number of two-cell embryos reaching the blastocyst stage in 5 or 320 microliters. Culturing embryos in groups significantly increased blastocyst cell numbers in all volumes employed and elevated embryo viability. Such observations are consistent with the hypothesis that the preimplantation mammalian embryo produces a factor(s) which can stimulate its own development. The results of this study have implications for clinical in-vitro fertilization, where embryos are routinely cultured individually in relatively large volumes.

274 citations


Journal ArticleDOI
TL;DR: Incubation of cells with alpha-phorbol 12,13-didecanoate failed to counteract the effect of LPS or to induce nitric oxide synthase, suggesting that activation of protein kinase C was involved in this process.

119 citations


Journal ArticleDOI
TL;DR: The time between a hatching egg being produced and set in an incubator can be divided into a laying house period and a storage period, which affects hatching results by the egg hatching period.
Abstract: The time between a hatching egg being produced and set in an incubator can be divided into a laying house period and a storage period. The period in the laying house affects hatching results by the...

117 citations


Journal ArticleDOI
TL;DR: Reversing the temperature shift can restore a culturable population comparable in numbers to the original population, but this process is largely due to regrowth.
Abstract: Vibrio vulnificus cells progressively lose culturability during incubation at 5°C. This process is accelerated by the addition of supernatants from non-culturable cells obtained by incubation at 5°C for 17 days. Thus the organism apparently produces a factor upon cold incubation which is triggering or causing the decline in culturability. Reversing the temperature shift can restore a culturable population comparable in numbers to the original population, but this process is largely due to regrowth. A few cells retaining the ability to grow apparently utilize the substrates released by the moribund cells, thus mimicking resuscitation of the whole population.

94 citations


Journal ArticleDOI
TL;DR: The results indicate that H pylori could survive in environmental water which may thus act as a potential reservoir of infection.
Abstract: AIMS: To determine the effects of physical conditions on survival of Helicobacter pylori in aquatic environments. Survival for prolonged time intervals would implicate environmental water as a possible source of infection. METHODS: The effect of ionic strength, pH, urea, protein and composition of incubation atmosphere on the survival of H pylori NCTC 11637 and two clinical isolates (CI 82 and 92) was investigated. RESULTS: H pylori strains survived for longer periods in physiological (0.15M) saline than in 0.05M or 0.6M saline solution. Optimal pH range for survival was between pH 5.8 and 6.9. Addition of urea (final concentration 100 microM/l-1 and 5 mM/l-1) to neutral unbuffered 0.15M saline resulted in a reduction in survival; addition of bovine serum albumin (1%) or gelatin (1%) resulted in variable survival times compared with saline alone. Incubation in a microaerobic gas mixture prolonged survival compared with incubation in air. CONCLUSION: H pylori survival in water over a prolonged period is possible for a range of physical variables. The results indicate that H pylori could survive in environmental water which may thus act as a potential reservoir of infection.

92 citations


Journal ArticleDOI
TL;DR: It is confirmed that the behavioral demasculinization in quail takes place mainly though not exclusively during the early stages of ontogeny, and that the sensitivity to differentiating effects of estrogens varies with age in a sexually differentiated manner.

86 citations


Journal ArticleDOI
TL;DR: Two experiments were run using broiler eggs to determine whether sex differences exist in incubation time required to hatch males and females and in various measures of chick weight (CW) and relationships between measures of CW and incubationTime and between CW and egg weight (EW).

68 citations


Journal ArticleDOI
TL;DR: The authors discuss the evidence that incubation period is inversely related to dose, the use of incubationperiod as a marker for dose, and the role that individual differences in susceptibility play in determining both the incubation periods and the outcome.
Abstract: The associations between infecting dose, incubation period, and the severity of disease were examined in a large outbreak of Salmonella typhimurium which occurred at a medical conference in Wales in 1986. Persons who had eaten two or more pieces of the chicken vehicle had, on average, shorter geometric mean incubation periods than those who had only eaten one piece: 16.6 hours (95% confidence interval (CI) 13.5-20.5) compared with 20.7 hours (95% CI 19.0-22.6) (t = 1.97, p < 0.05). Incubation period was negatively correlated with the maximum frequency of diarrheal stools (r = -0.46, 95% CI -0.56 to -0.33), the maximum temperature reached (r = -0.34, 95% CI -0.50 to -0.16), the duration of symptoms (r = -0.41, 95% CI -0.53 to -0.26), and the amount of time taken off from work (r = -0.54, 95% CI -0.65 to -0.41). Those with shorter incubation periods were more likely to have been hospitalized. There was no association between chicken consumption and any of the measures of severity. The authors discuss the evidence that incubation period is inversely related to dose, the use of incubation period as a marker for dose, and the role that individual differences in susceptibility play in determining both the incubation period and the outcome.

61 citations


Journal ArticleDOI
TL;DR: It is suggested that nest temperature or feeding conditions are the most likely factors influencing the differences in male incubation behavior between European and North American populations.
Abstract: Male Barn Swallows (Hirundo rustica) help their mates to incubate in North America but not in Europe. In this study, conducted at four colonies in southeastern Canada, males contributed an average of 9% of the total amount of incubation during daylight hours. The total percent of time that eggs were incubated (nest attentiveness) by both sexes declined through the day, largely due to a response to increasing temperature. The nest attentiveness of both males and females was negatively correlated with nest temperature (i.e., air temperature near the nest) but not consistently with weather. In general a male seemed to incubate more when his help was needed-early in the day when the female had to recover energy lost during nighttime incubation and late in the incubation period when females should have been most stressed energetically. We found no evidence that male nest attentiveness was affected by their expected opportunity to obtain extra-pair copulations - neither differences in male attractiveness due to tail-length manipulation (shortening or elonption) nor changes in the operational sex ratio affected the male's relative share of incubation duties. Using DNA fingerprinting, we also found that the male contribution was not affected by his paternity in the brood. Since colony size and the mating system of this species appear to be similar in both North America and Europe, the intensity of sexual selection should not differ substantially between these populations. Instead we suggest that nest temperature or feeding conditions are the most likely factors influencing the differences in male incubation behavior between European and North American populations.

60 citations


Journal ArticleDOI
TL;DR: In this article, the authors used both a clinical and an environmental isolate of Legionella pneumophila to study the long-term survival of the species in drinking water, creek water, and estuarine water microcosms.
Abstract: Extended survival of Legionella pneumophila, using both a clinical and an environmental isolate, was studied in drinking water, creek water, and estuarine water microcosms. Legionella populations were monitored by acridine orange direct counts (AODC) and viable count on buffered charcoal yeast extract agar amended with alpha-ketoglutarate (BCYEα). Initial colony counts of the clinical isolate in drinking and creek water microcosms were 2 × 108 cfu/ml and, after incubation for 1.5 years, the plate counts decreased to 3 × 106 cfu/ml. The AODC counts, however, did not change significantly. The clinical isolate in estuarine water decreased in plate counts to 102 (cfu/ml) over the same period. After incubation for 1.5 years at 15°C in the microcosms, Legionella plate counts of creek and drinking water decreased by two logs. Direct microscopic examination of aliquots removed from all microcosms revealed the presence of small bacilli, large bacilli and rare filamentous cells. The environmental isolate demonstrated only one colony morphology upon culture on BCYEα. Interestingly, after four months incubation in the microcosm, upon plating the clinical isolate on BCYEα, two distinct colony types were evident. Examination by immunofluorescent staining employing a monoclonal antibody against L. pneumophila revealed both bacillus and filamentous forms. The total cellular proteins of both morphotypes were examined by sodium dodecyl sulfate polyacrylyamide gel electrophoresis (SDS-PAGE), demonstrating identical protein patterns. Those Legionella cells remaining culturable during 1.5 years of incubation grew rapidly when transferred to BCYEα. Incubation was continued and it was found that some strains of L. pneumophila serogroup 1 can remain viable for longer than 2.4 years under low-nutrient conditions.

54 citations


Journal ArticleDOI
TL;DR: During 12 weeks of subsequent incubation at 28°C, the bacterial population was favoured by increasing soil pH; nevertheless, at the end of the incubation the positive effect was only significant at pH 6.5.
Abstract: Lime was added to a forest acid soil rich in organic matter. During five weeks of initial incubation at room temperature (until the various limed soil samples reached stabilized pHs of 5.5, 6.0 or 6.5), there were rapid increases in the bacterial population, denitrifiers, and fungal mycelia, particularly in the heaviest limed sample. Conversely, nitrite oxidizers decreased to undetectable numbers regardless of the lime dose applied. At this time soil samples were amended with 5% of fresh soil. During 12 weeks of subsequent incubation at 28°C, the bacterial population was favoured by increasing soil pH; nevertheless, at the end of the incubation the positive effect was only significant at pH 6.0 and 6.5. By contrast fungi were depressed by raising the pH. Nitrifiers and denitrifiers were more numerous in the limed than in the unlimed soils but only in samples at pH 6.5 were the differences significant throughout the incubation period.

Journal ArticleDOI
TL;DR: The incubation period and severity of bacterial canker of tomato caused by Clavibacter michigansensis subsp.
Abstract: The incubation period and severity of bacterial canker of tomato caused by Clavibacter michiganensis subsp. michiganensis were influenced by temperature, plant age, inoculum concentration, and cultivar. The incubation period was longer and symptom development was less severe with cooler temperatures, older plants, lower concentrations of inocula, and moderately resistant cultivars. The time required before leaves wilted or cankers developed at the edge of inoculated petioles varied from 12 to 34 days, depending on conditions (.)

Journal ArticleDOI
TL;DR: Increases in soluble and total protease activities in soils amended with agar and glucose coincided with increases in ATP content, total counts of bacteria, growth of fungi, and CO2 evolution, which appeared to be an index for the level of extracellular enzymes in soil.
Abstract: In an incubation experiment, soil was amended to induce changes in microbial growth and enzyme production. The soluble fraction of newly produced protease (extracellular enzyme) was separated from the soil by a sterilized millipore filter. The activity of total and soluble protease, ATP content, number of acridine orange-stained bacteria, and CO2 evolution in soils were measured during the incubation. Increases in soluble and total protease activities in soils amended with agar and glucose coincided with increases in ATP content, total counts of bacteria, growth of fungi, and CO2 evolution. In amended soils, the activity of soluble extracellular protease was about 30% of the total protease activity. Soluble extracellular protease activity was highly correlated with total protease activity (r=0.78, P<0.01), ATP content (r=0.74, P<0.01), and total counts of bacteria (r=0.94, P<0.01) during the first 6 days of incubation. Hence measurement of microbial biomass appeared to be an index for the level of extracellular enzymes in soil.



Journal ArticleDOI
Pamela S. Marten1
TL;DR: Survition of eggs to hatching was affected only by T 1, which also determined the percentage of eggs that survived to the eyed stage, and neither T 1 nor T 2 had any effect on the incidence of physically deformed alevins.
Abstract: I examined the effects of temperature variation during the incubation of brook trout (Salvelinus fontinalis) on duration of embryonic development, survival to hatching, incidence of deformities, and alevin length at hatching. Brook trout eggs were incubated in five water-recirculation tanks in which the temperature was varied when the eggs had completely developed eye pigmentation (eyed stage). A computer system was used to monitor and regulate temperature. The time, t (d), from fertilization to the hatching of 50% of the eggs depended upon the mean incubation temperature (°C) from fertilization to the eyed stage, T 1, and the mean temperature (°C) from the eyed stage to hatching, T 2, in the following manner: t = 176 – 14.7T 1 – 9.67T 2 + 0.800T 1 2 + 0.367T 2 2. Survival of eggs to hatching was affected only by T 1, which also determined the percentage of eggs that survived to the eyed stage. Neither T 1 nor T 2 had any effect on the incidence of physically deformed alevins. Alevin length at ha...

Journal ArticleDOI
TL;DR: Although heat-induced haemolysis and an increase in fragility have not been known to occur below 48 degrees C, these were quite apparent after incubation for 24-48 h at only 42 degrees C and suggests that with regard to thermal effects, it is important to consider not only the temperature but also the duration of heating.
Abstract: 1. Erythrocytes are known to haemolyse in vitro at 48-50 degrees C. We hypothesized that erythrocytes might be damaged at much lower temperatures if they are incubated for prolonged periods. Erythrocytes from healthy human donors (n = 7) were incubated at 37, 40, 42, 44, 46 or 48 degrees C for 4-48 h. The haemolytic percentage and osmotic fragility were then measured by a modification of the method of Parpart et al. 2. Significant haemolysis and increased fragility were not observed at any temperatures after incubation for 4 h. However, the haemolytic percentage increased after incubation for 24 h at 44 degrees C (9.1 +/- 4.9%, P less than 0.01), 46 degrees C (52.4 +/- 14.1%, P less than 0.01) and 48 degrees C (98.0 +/- 2.6%, P less than 0.01) and after incubation for 48 h at 42 degrees C (9.8 +/- 4.5%, P less than 0.01) when compared with the values before heating (1.1 +/- 0.9%). The osmotic fragility also increased after incubation for 24 h at and above 42 degrees C. 3. Although heat-induced haemolysis and an increase in fragility have not been known to occur below 48 degrees C, these were quite apparent after incubation for 24-48 h at only 42 degrees C. This suggests that with regard to thermal effects, it is important to consider not only the temperature but also the duration of heating.

Journal ArticleDOI
TL;DR: In this article, the effects of pretreating soil samples (field fresh, drying at 40° and 105°C, freezing/thawing) on N mineralization in an incubation experiment and on the dynamics of the organic N fraction extracted by K2SO4 solution were studied.
Abstract: We studied the effects of pretreating soil samples (field-fresh, drying at 40° and 105°C, freezing/thawing) on N mineralization in an incubation experiment and on the dynamics of the organic N fraction extracted by K2SO4 solution. The soil samples were collected from plots in a long-term field experiment with the application of mineral fertilizer and farmyard manure. Compared with the field-fresh soil samples, freezing/thawing resulted in higher NO 3 − -N contents while the NH 4 + -N and the organic N content were increased by drying at 105°C. During the incubation period N mineralization was highest after the samples were dried at 105°C and a little lower in those dried at 40°C. After freezing/thawing the order of magnitude of N mineralization remained the same. The difference in organic N between the beginning and the end of the incubation experiment and the mineral N content at the end of the experiment were correlated significantly. Despite this correlation, however, the change in the organic N content underestimated the N mineralization rates.

Journal ArticleDOI
TL;DR: The total culture time of 40 hours including pulsing with 3H-thymidine during the final 16 hours of incubation was the best for Con A and PHA-P-stimulated cells, whereas a longer incubation of 64 hours gave the highest results with PWM stimulations.
Abstract: SUMMARY. Optimum conditions for chicken (Gallus gallus) lymphocyte transformation tests were determined. Thrice-washed chicken buffy-coat cells obtained after slow centrifugation (40 x g for 10 minutes) responded substantially better to mitogenic stimulation than lymphocytes isolated on separation media containing Ficoll. Maximum responses were obtained with 2 x 107 lymphoid cells/mi. Responses to the mitogens were greatest when fetal bovine serum was used at a 5% concentration or pooled chicken serum and autologous plasma were used at a 1.25% concentration. Optimum mitogen concentrations varied with individual birds, timing of the culture, temperature of incubation, and serum concentration in the cultures. When 1.25% chicken serum was used in the cultures, responses were usually greatest with final concentrations of 30-50 tg/ml of concanavalin A (Con A) and 30-50 j,g/ml of phytohemagglutinin-P (PHA-P). The optimum concentration of pokeweed mitogen (PWM) varied from 1 to 40 ,g/ml among the birds and was practically impossible to establish in general. The incubation in humidified air with 5% CO2 was significantly better at 40 C than at 37 C. The total culture time of 40 hours including pulsing with 3H-thymidine during the final 16 hours of incubation was the best for Con A- and PHA-P-stimulated cells, whereas a longer incubation of 64 hours gave the highest results with PWM stimulations.

Journal ArticleDOI
TL;DR: Embryos incubated at 37°C completed fewer divisions, had a slightly increased rate of cleavage and showed an increased tendency to degenerate than embryos cultured at 32.6°C.

Journal ArticleDOI
TL;DR: The effectiveness of these incubated soils in supplying P to plants decreased with time of incubation as mentioned in this paper, though not as quickly as after air-dry incubation, and the effectiveness increased after moist incubation.
Abstract: SUMMARY Subterranean clover was grown in pots in which the only source of phosphate (P) was from bands of soil which had been incubated with P for a range of times, and at different temperatures, when either moist or air-dry. The effectiveness of these incubated soils in supplying P to plants decreased with time of incubation. Effectiveness decreased after air-dry incubation, though not as quickly as after moist incubation. These results indicate that air-dry storage of soil samples is to be avoided if the samples are to be assessed for their ability to supply P to growing plants. They also indicate that the cost-saving to Australian farmers, derived from applying phosphate prior to the start of the growing season, may be balanced or even outweighed by a loss in fertilizer effectiveness due to the reaction between P and the soil in the weeks prior to germination of seed.

Journal ArticleDOI
TL;DR: In a 60-min incubation period, the in vitro release of serotonin (5-HT) from the hypothalami of control male rats decreased by 12.3 ± 3.1% as discussed by the authors.

Journal ArticleDOI
01 Apr 1992-The Auk
TL;DR: It is suggested that initiation of full incubation is not rigidly controlled by hormonal changes associated with the laying of the penultimate egg, and therefore, asynchronous hatching of thepenultimate and, especially, the last egg does not requireFull incubation.
Abstract: Mead and Morton (1985) suggested that asynchronous hatching for birds in which only the female incubates is caused by a hormonal surge associated with the ovulation of the last ovum. This hormonal surge is believed to inhibit further ovulation and simulta- neously stimulate females to initiate full incubation. Thus, the advantages, if any, accrued from asynchronous hatching are merely epiphenomena. The hormonal hypothesis predicts that regardless of clutch size, full incubation is initiated with the laying of the penultimate egg. We also predict from the hypothesis that incubation attentiveness during egg laying will be similar in females tending either four- or five-egg clutches, especially on the day the penultimate and last eggs are laid, hatch spreads will be similar in four- and five-egg clutches, and the addition of eggs during egg laying will not induce increased incubation attentiveness. In a three-year study (1988-1990) on Yellow Warblers (Dendroica petechia) nesting at Delta Marsh, Manitoba, we found that incubation attentiveness during egg laying was similar between females that produced four- and five-egg clutches, but full incubation was not initiated prior to the last egg being laid. Despite apparently similar incubation attentiveness during egg laying, hatch spreads differed significantly between four- and five-egg clutches. Incubation attentiveness was increased experimentally by adding eggs during early egg laying. We suggest that initiation of full incubation is not rigidly controlled by hormonal changes associated with the laying of the penultimate egg. Therefore, asynchronous hatching of the penultimate and, especially, the last egg does not require full incubation. Received 16 January 1991, accepted 8 November 1991.

Journal ArticleDOI
TL;DR: Results suggest that ejaculated canine spermatozoa are capacitated by 4h incubation in TYH, and hyperactivated movement and acrosome reaction increased remarkably at 3 h and 4h of incubation.
Abstract: Ejaculated canine spermatozoa were incubated at a concentration of 0.6-4.0×108/ml, using a modified Krebs-Ringer bicarbonate solution (TYH) at 37C under 5% CO2 in air. Motility, aggregation, viability, hyperactivated movement and acrosome reaction of spermatozoa were examined at 0, 1, 2, 3, 4, 5 and 6 h of incubation. Motility and viability decreased slightly and aggregation increased at 1h of incubation, then did not significantly change until 6h of incubation (about 3.4, 65% and 75%, respectively). The percentage of spermatozoa showed hyperactivated movement and acrosome reaction increased remarkably at 3 h (53.9%) and 4h (68.0%) of incubation, respectively. The 4 h-incubated spermatozoa were inseminated at a concentration of 0.5 or 1.0×106/ml to the oocytes incubated in TYH (bovine serum albumin (BSA) -) with 10% fetal bovine serum for 48 h or 72 h. The spermatozoa penetrated into the zona pellucida at 1h after insemination. At 2 h after insemination, the spermatozoa penetrated into the cytoplasm (34.0%), then the percentage increased significantly to 63.4% at 4h after insemination. These results suggest that ejaculated canine spermatozoa are capacitated by 4h incubation in TYH.

Journal ArticleDOI
TL;DR: This study ascertained the minimum duration of an acidic stimulus necessary to induce adaptive changes in stimulated HCO3- secretion and the roles of protein synthesis and cytoskeletal function in this process and the incubation protocol failed to enhance stimulated H CO3- absorption.
Abstract: Cortical collecting ducts (CCDs) isolated from acid-loaded rabbits and perfused in vitro absorb HCO3-, whereas CCDs from normal animals secrete HCO3-. We have previously shown that CCDs incubated in vitro for 3 h at pH 6.9 show a reduction in net (baseline and stimulated) HCO3- secretion. In this study we ascertained the minimum duration of an acidic stimulus necessary to induce adaptive changes in stimulated HCO3- secretion (determined in the absence of basolateral Cl-) and the roles of protein synthesis and cytoskeletal function in this process. CCDs incubated in acid (pH 6.8, HCO3- 6 mM) for 1 h followed by incubation at pH 7.4 (HCO3- 25 mM) for 2 h showed a 41% reduction in stimulated HCO3- secretion (P < 0.001), similar to that observed after 3 h of incubation at pH 6.8. However, this incubation protocol failed to enhance stimulated HCO3- absorption (determined in the absence of luminal Cl-). Addition of 10 microM anisomycin, a reversible inhibitor of protein synthesis, throughout the entire period of incubation (1 h at pH 6.8 plus 2 h at pH 7.4) blocked adaptive reduction in HCO3- secretion, as did exposure to anisomycin only during the initial 1 h of acid incubation. In contrast, anisomycin application during the 2-h incubation at pH 7.4 failed to block this adaptation of HCO3- secretion. Application of 4 microM actinomycin D, an inhibitor of DNA transcription, during the acid incubation also prevented the adaptive response, as did application during the total or during the 2-h pH 7.4 incubation period of 0.2 microM cytochalasin D, an inhibitor of actin filament function.(ABSTRACT TRUNCATED AT 250 WORDS)

Journal ArticleDOI
TL;DR: The influence of variations in the pH, NaCl concentration, temperature, and concentrations of calcium and magnesium ions on the survival of Chlamydia pneumoniae elementary bodies (EBs) outside the host cells was investigated.
Abstract: The influence of variations in the pH, NaCl concentration, temperature, and concentrations of calcium and magnesium ions on the survival of Chlamydia pneumoniae elementary bodies (EBs) outside the host cells was investigated. The survival was determined after various incubation periods by counting the inclusion-forming units after C. pneumoniae was cultured for 72 h on monolayers of HL cells. The normal physiological conditions were restored prior to infecting the HL cells with C. pneumoniae. Declines in the infectivities of C. pneumoniae EBs were observed at pH values of lower than 5 and higher than 8 or at NaCl concentrations of less than 80 mM. The viability of C. pneumoniae EBs in SPG medium decreased as the temperature and/or incubation period increased. Incubation temperatures of up to 20 degrees C and incubation periods of up to 48 h did not affect the viability of C. pneumoniae. One hundred percent of the C. pneumoniae EBs were infective after 1 h of incubation at 35 degrees C, whereas 90, 50, and 40% survived after incubations of 8, 24, and 48 h, respectively. The viability of C. pneumoniae was unaffected within the investigated range of Ca2+ and Mg2+ ion concentrations in the medium. The presence of 10% fetal calf serum in the incubation medium had a stabilizing effect on the viability of C. pneumoniae. This effect became more pronounced as the incubation period increased.

Journal Article
TL;DR: It is suggested that incubation conditions for the optimal cytotoxicity of IT treatment can be predicted by studying the internalization and degradation of the IT or respective monoclonal antibody.
Abstract: The cytotoxicity of WT32 (CD3)-ricin A immunotoxin (IT) to the acute lymphoblastic leukemia T-cell line Jurkat was compared with the rate of internalization and intracellular degradation of WT32 and WT32-ricin A during continuous exposure. Moreover, the influence of NH4Cl and monensin on these processes was studied. Based on protein synthesis inhibition ([3H]leucine incorporation), it appeared that cytotoxicity was not fully expressed directly after exposure to IT due to a delay in either the internalization of membrane-bound IT or the action of intracellular ricin A. Varying the duration of incubation and postponing [3H]leucine addition for up to 24 h after initiation showed that cytotoxicity occurred in two phases, rapid internalization of initially bound IT followed by a continuous but slower uptake, possibly due to reexpression of the CD3 antigen. No differences were found in the rate of internalization and degradation of 125I-labeled WT32 and WT32-ricin A. Internalization started rapidly after binding at 37°C, was fastest during the first 12 h (±360,000 molecules/cell), and continued for at least 24 h (±420,000 molecules/cell). Exocytosis of intracellularly degraded molecules became measur-able after 1 to 2 h of incubation at 37°C and increased to approximately 400,000 molecules/cell in 24 h. After 4 h of incubation at 37°C the number of internalized molecules exceeded the amount of WT32 that could maximally bind to the cell membrane (±150,000 molecules/cell), confirming reexpression of antigen. The addition of NH4Cl and monensin enhanced the cytotoxicity of WT32-ricin A, probably due to an increased intracellular amount of IT. These agents appeared to reduce strongly the degradation of internalized WT32, resulting in an accumulation of intracellular molecules. NH4Cl was most effective during the first 12 h of incubation, whereas monensin increased the amount of intracellular WT32 molecules after 2 to 24 h. Our observations suggest that incubation conditions for the optimal cytotoxicity of IT treatment can be predicted by studying the internalization and degradation of the IT or respective monoclonal antibody.

Journal ArticleDOI
TL;DR: Scanning electron microscopy has been used to enhance the description of a single species, Caretta caretta (the loggerhead turtle), staged according to Miller's system for the development of marine turtles, confirming that Miller's scheme is generally applicable to C. caretta, provided that due regard is paid to the incubation temperature.
Abstract: Scanning electron microscopy has been used to enhance the description of a single species, Caretta caretta (the loggerhead turtle), staged according to Miller's system for the development of marine turtles. Incubation over a temperature range of 25°-34°C confirms previous observations that, under artificial conditions and at a constant incubation temperature, normal development is confined to a limited temperature range. Premature pipping is a feature of incubation at the lower end of this range; abnormal development, generated during the first third of the incubation period, occurs just above the normal range. Details of the external morphology of embryos from Miller stage 14 through to 25 are given together with an account of the developmental abnormalities produced at a high temperature of incubation. The data obtained confirm that Miller's scheme is generally applicable to C. caretta, provided that due regard is paid to the incubation temperature. © 1992 Wiley-Liss, Inc.

Journal ArticleDOI
TL;DR: ACTH caused major changes in steroid distribution due to increased 17-hydroxylase and 17,20-lyase activities and decreased 21-hydroxyylase activity inFG cells in culture, suggesting that mechanism(s) other than gene expression alone regulate steroid secretion in FG cells.

Journal ArticleDOI
TL;DR: Results suggest that Cd-MT may be broken down by the cysteine protease in lysosomes and that the released Cd bound low molecular weight fragment(s) was subsequently transferred to the high molecular weight protein in cytosol.