The effect of temperature and of cofactor concentrations on the conversion of 4-14C-progesterone to corticosterone by rat adrenal preparations

1970 ◽  
Vol 48 (7) ◽  
pp. 740-745 ◽  
Author(s):  
Charles P. W. Tsang ◽  
J. Stachenko
Keyword(s):  
Incubation Period ◽  
Significant Degree ◽  
Effect Of Temperature ◽  
Steroid Hydroxylase ◽  
Generating System

When a Krebs–Ringer bicarbonate medium in which adrenal quarters have been preincubated (hereafter called PIM), is reincubated for 3 h in the presence of 4-14C-progesterone and a NADPH-generating system, it possesses the capacity of hydroxylating the progesterone molecule (5). When the PIM is prepared at 0 °C, its subsequent incubation at 37 °C enhances the conversion of progesterone to 21-hydroxy- and 11β-hydroxy-steroids 30-fold and fivefold, respectively, above those observed upon incubation of PIM prepared at 37 °C. Similarly when dilute homogenates (0.6 mg tissue per milliliter) are preincubated for 1 h at 21 °C prior to a 3-h incubation period in the presence of 4-14C-progesterone and proper cofactors, 21- and 11β-hydroxylations of progesterone are, respectively, six times and twice greater than when the preincubation temperature is 37 °C.It is concluded that: (i) 21- and 11β-hydroxylating systems are inactivated to a significant degree at 37 °C and that under these conditions the 21-hydroxylase system is much more labile than the 11β-hydroxylase system; and (ii) this difference in the degree of denaturation of these two steroid hydroxylase systems explains in part the accumulation of 11β-hydroxyprogesterone in the PIM as well as in homogenates.

Effect of Temperature on ADP-Induced Platelet Aggregation

1973 ◽  
Vol 29 (01) ◽  
pp. 183-189
Author(s):  
C. A Praga ◽  
E. M Pogliani
Keyword(s):  
Platelet Aggregation ◽  
Incubation Period ◽  
Room Temperature ◽  
Important Variable ◽  
Practical Significance ◽  
Effect Of Temperature ◽  
Induce Platelet Aggregation ◽  
Cuvette Holder ◽  
Exact Temperature

SummaryTemperature represents a very important variable in ADP-induced platelet aggregation.When low doses of ADP ( < 1 (μM) are used to induce platelet aggregation, the length of the incubation period of PRP in the cuvette holder of the aggregometer, thermostatted at 37° C, is very critical. Samples of the same PRP previously kept at room temperature, were incubated for increasing periods of time in the cuvette of the aggregometer before adding ADP, and a significant decrease of aggregation, proportional to the length of incubation, was observed. Stirring of the PRP during the incubation period made these changes more evident.To measure the exact temperature of the PRP during incubation in the aggre- gometer, a thermocouple device was used. While the temperature of the cuvette holder was stable at 37° C, the PRP temperature itself increased exponentially, taking about ten minutes from the beginning of the incubation to reach the value of 37° C. The above results have a practical significance in the reproducibility of the platelet aggregation test in vitro and acquire particular value when the effect of inhibitors of ADP induced platelet aggregation is studied.Experiments carried out with three anti-aggregating agents (acetyl salicyclic acid, dipyridamole and metergoline) have shown that the incubation conditions which influence both the effect of the drugs on platelets and the ADP breakdown in plasma must be strictly controlled.

Effect of Temperature on Incubation Time for Spontaneous Morphology Change in Electrodeposited Copper Metallization

2005 ◽  
Vol 863 ◽  
Author(s):  
S. Ahmed ◽  
D.N. Buckley ◽  
S. Nakahara ◽  
Y. Kuo
Keyword(s):  
Incubation Period ◽  
Incubation Time ◽  
Annealing Time ◽  
Room Temperature ◽  
Diffusion Mechanism ◽  
Systematic Investigation ◽  
Effect Of Temperature ◽  
Copper Metallization ◽  
Morphology Change ◽  
A Value

AbstractA systematic investigation of the effect of annealing time and temperature on the incubation period for spontaneous morphology change (SMC) in electrodeposited copper metallization is reported. The incubation time is greatly reduced at higher temperatures. At each temperature, the remaining incubation time at room temperature was found to decrease approximately linearly with increasing annealing time. An Arhennius plot of the measured rates of decrease showed good linearity and yielded a value of 0.48 eV for the activation energy. This is consistent with a vacancy diffusion mechanism for the process occurring during the incubation period and supports our proposed mechanism for SMC.

scholarly journals Effect of Temperature on Thekopsora minima Urediniospores and Uredinia

Plant Disease ◽  
2004 ◽  
Vol 88 (4) ◽  
pp. 359-362 ◽  
Author(s):  
S. E. Pfister ◽  
S. Halik ◽  
D. R. Bergdahl
Keyword(s):  
Incubation Period ◽  
Germ Tube ◽  
Polynomial Regression ◽  
Tube Growth ◽  
Effect Of Temperature ◽  
Optimum Temperature ◽  
Infection Efficiency ◽  
Percent Germination ◽  
Leaf Disks ◽  
Germ Tube Growth

Thekopsora minima is a heteroecious rust, with spermogonia and aecia occurring on the needles of hemlock (Tsuga spp.) and uredinia, telia, and basidia occurring on the leaves of ericaceous genera, including species of Rhododendron. The effect of temperature was determined for urediniospore germination, germ tube growth, and infection efficiency on Rhododendron ‘White Lights’. Percent germination and germ tube growth were assessed at 10, 15, 20, 25, and 30°C after 3 h of incubation on 1.5% water agar in the dark. Polynomial regression analyses revealed a significant effect of temperature on both germination (P < 0.001, R2adj = 0.936) and germ tube growth (P < 0.001, R2adj = 0.933), with predicted optimum temperatures of 21.5 and 22.0°C, respectively. Germination and germ tube growth were reduced greatly at 30°C and below 15°C. Temperature also was found to have a significant effect on infection efficiency, as measured by incubation period (P < 0.001, R2adj = 0.808) and uredinia produced (P < 0.001, R2adj = 0.866). On excised leaf disks of Rhododendron ‘White Lights’ maintained under a 14-h photoperiod, the shortest mean incubation periods of 10.7 and 10.0 days were at 20 and 25°C, respectively, with a predicted optimum of 23°C. The mean incubation period at 15 and 30°C was approximately 4 and 3 days longer, respectively, than at the predicted optimum temperature. The number of uredinia produced was similar at 15, 20, and 25°C, but was reduced sixfold at 30°C. The predicted optimum temperature for uredinial production was 19.5°C, with a 5% variation in uredinia production between 17.5 and 22°C.

Studies on the Bionomics of the Case-bearing Clothes Moth, Tinea pellionella (L.)

1956 ◽  
Vol 47 (1) ◽  
pp. 167-182 ◽  
Author(s):  
P. S. Cheema
Keyword(s):  
Larval Development ◽  
Incubation Period ◽  
Wide Distribution ◽  
Effect Of Temperature ◽  
Continuous Darkness ◽  
Significant Difference ◽  
Temperature And Humidity ◽  
Important Pest ◽  
Orange G ◽  
Extent Of Damage

Tinea pellionella (L.), commonly known as the Case-bearing Clothes Moth or Fur Moth, is of world-wide distribution and is of considerable economic importance. It has been recorded on a variety of substances, particularly those of a keratinous nature. In India, it has been found as an important pest of woollen textiles. Its life-history and habits have been systematically investigated at different levels of temperature and humidity.The incubation period is 4 to 5, 5, 6 to 7 and 6 to 7 days at 21·5, 25, 30 and 32·5°C., respectively. Temperatures higher than 32·5°C. have been found lethal to eggs. Humidity has no effect on the incubation period. Percentage viability of eggs is greater at lower than at higher temperatures.Both temperature and humidity have been found to influence the larval development and the number of larval instars. Irrespective of temperature, higher humidities favour shorter larval development and the shortest larval period is at 25°C. and 90 per cent. R.H.Woollen materials impregnated with yeast are more suited for the larval development than those not so treated. Larvae do not exhibit colour preference. Woollen fabrics dyed with Cloth fast orange G 4 per cent, manufactured by “ Ciba ”, however, inhibit the growth of freshly hatched larvae.The behaviour of the larvae to direct sunlight has been studied. The rôle of (a) diffused light alternated with darkness, (b) darkness, (c) temperature and (d) humidity on the extent of damage caused by the larvae has been investigated. Under the conditions of the experiments, the amount of damage in continuous darkness was significantly greater than in alternating light and darkness, and that at 90 per cent. R.H. significantly greater than at 30 per cent., but there was no significant difference in the amount of damage at 27·5° and 32·5°C., respectively, and 90 per cent. R.H.The mode of pupation has been described. The pupal period has been studied and found.to occupy 18 ± 0·4, 10·3 ± 0·16 and 10·3 ± 0·33 days at 21·5, 25 and 30°C. and 90 per cent. R.H., respectively. Humidity has no effect on this period.The effect of temperature and humidity on (a) the preoviposition, oviposition and postoviposition periods and (b) number of eggs laid by a female has been studied. The life-span of the male and female, the relationship between the weight of the female at emergence and fecundity (which was highly significant) on the one hand and length of life (which was not significant) on the other has also been investigated. Sex ratio between females and males has been found to be 2·6:1. Three to four generations in a year have been recorded at 26 ± 8·0°C. and 82 ± 10 per cent. R.H. when the larvae are fed on woollen fabrics impregnated with yeast.

scholarly journals Effect of Temperature on the Incubation Period and Leaf Colonization in Bacterial Blight of Anthurium

1999 ◽  
Vol 89 (11) ◽  
pp. 1007-1014 ◽  
Author(s):  
R. Fukui ◽  
H. Fukui ◽  
A. M. Alvarez
Keyword(s):  
Linear Relationship ◽  
Leaf Area ◽  
Incubation Period ◽  
Xanthomonas Campestris ◽  
Resistant Cultivar ◽  
Effect Of Temperature ◽  
Susceptible Cultivar ◽  
Degree Days ◽  
Degree Day ◽  
Leaf Tissues

Effect of temperature on leaf colonization in anthurium blight was studied using a bioluminescent strain of Xanthomonas campestris pv. dieffenbachiae. In a susceptible cultivar, colonization of leaf tissues (monitored by detection of bioluminescence) and symptom development (assessed visually) advanced rapidly at higher temperatures. For a susceptible cultivar, there was a linear relationship between degree-days and percent leaf area colonized by the pathogen, indicating that leaf colonization in a susceptible cultivar was a direct function of the cumulative effect of temperature. The degree-day intercept of the regression line represented the time from inoculation to detection of bioluminescence, and the slope indicated the increase of leaf colonization per degree-day. There also was a linear relationship between the logarithm of degree-days and the logarithm of percent leaf area showing visible symptoms in a susceptible cultivar. The degree-day intercept of this relationship represented the incubation period (about 500 degree-days). The degree-days required to detect bioluminescence was not considerably different between susceptible and resistant cultivars. However, the subsequent rates of leaf colonization were significantly lower for a resistant cultivar than for a susceptible cultivar in all temperature regimes. The results suggest that multiplication of the pathogen in the leaf tissues is optimized in the susceptible cultivar. In contrast, in the resistant cultivar, the defense mechanisms overshadow the temperature effect. The differential response to temperatures may be an additional indicator of cultivar susceptibility.

Studies on sunflower rust. XI. Effect of temperature and light on germination and infection of sunflowers by Puccinia helianthi

1972 ◽  
Vol 50 (9) ◽  
pp. 1879-1886 ◽  
Author(s):  
P. N. Sood ◽  
W. E. Sackston
Keyword(s):  
Light Intensity ◽  
Incubation Period ◽  
Dark Period ◽  
Effect Of Temperature ◽  
Appressorium Formation ◽  
Leaf Discs ◽  
Puccinia Helianthi ◽  
Race 2 ◽  
Race 4

Urediospores of four races of Puccinia helianthi incubated on water agar for 6 h or on sunflower leaf discs for 16 h germinated equally well from 10 to 25 °C, but significantly less at 30° and least at 5 °C. Appressorium formation was highest at 10 to 25 °C, lower at 30 °C, and lowest at 5 °C for races 1 and 3; none occurred at 30 and 5° in races 2 and 4. The optimum for penetration by races 1 and 3 was 20 °C, for race 2, 15° to 20 °C, and for race 4, 20° to 25 °C. Results were the same on susceptible and resistant hosts.Germination percentage on water agar was reduced with increasing light intensity from 2200 to 17 600 lx during incubation for 6 h. Germination on sunflower leaf discs was reduced with increasing light intensity during incubation for 16 h. Appressorium formation and penetration were adversely affected by increasing light intensity.Inhibition by light was overcome during a subsequent dark period when inoculated leaf discs were exposed to various cycles of light and dark during a 16-h incubation period.

The effect of temperature upon the hatching of the eggs of Pediculus humanus corporis de Geer (Anoplura)

Parasitology ◽  
1941 ◽  
Vol 33 (2) ◽  
pp. 243-249 ◽  
Author(s):  
H. S. Leeson
Keyword(s):  
Incubation Period ◽  
High Temperatures ◽  
Constant Temperature ◽  
Low Temperatures ◽  
Effect Of Temperature ◽  
Pediculus Humanus ◽  
Short Time

The hatching of the eggs of Pediculus humanus corporis De Geer is influenced by temperature.High temperatures accelerate and low temperatures delay development.The lowest constant temperature at which eggs will hatch is 24° and the highest 37°.At 24° eggs begin to hatch on the seventeenth day and continue hatching until the twenty-first. At 37° eggs hatch on the sixth and seventh days. The temperature at which eggs hatch in the shortest time is 35° and the time 5 days. At these extremes many eggs are killed so that the percentages of successful hatches are very low. Eggs are killed by 2 days' exposure to 39°.Temperatures at which the maximum number of eggs hatch he between 29 and 32°. In this range of “favourable” temperatures, up to 97% of successful hatches may be recorded. The incubation period is from 7 to 11 days. This is a convenient range of temperatures for laboratory purposes and gives largest numbers in a reasonably short time.Newly deposited eggs will not hatch if kept for 14 days at 23° or for shorter periods at lower temperatures, until at 8° exposure for 7 days is sufficient to ensure that all eggs are dead.If partially developed eggs are exposed to temperatures of 15° or lower, development ceases. If they are restored to a favourable temperature within 7 days, development is resumed and some of the eggs will hatch.Older eggs which have almost reached hatching point at a “favourable” temperature hatch if transferred to temperatures as low as 18°. They do not hatch at 15° or lower if kept at such temperatures for at least 9 days.

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