Showing papers on "Incubation published in 1981"

Energetic Cost of Incubation in the Zebra Finch

Abstract: -At temperatures below 28”C, rate of oxygen consumption (vjo2) of Zebra Finches (Poephila guttuta) incubating eggs averaged 20% higher than the \ioz of non-incubating Zebra Finches sitting in a nest at the same temperature. This increase represents the energetic cost of incubation. The O,, of non-incubating birds sitting in a nest was lower than values reported for birds perched in the open at the same temperature. In the Zebra Finch, the ameliorating effects of the nest microclimate approximately compensate for the increment in metabolic rate due to incubation. The energetic cost of incubation increased when birds had to rewarm cold eggs. Incubating birds responded to artificially cooled eggs by elevating their metabolic rate and increasing heat flow to the clutch. The pattern of adult attentiveness at the nest determines the number of times and amount by which the eggs must be rewarmed. Because it is energetically more expensive to rewarm eggs than to maintain temperature once the eggs are warm, the cost of incubation depends in part on the attentiveness pattern. Reproduction, especially the care of eggs and young, places special demands on the way birds allocate available energy. Various techniques have been used to estimate the energetic costs associated with territorial defense (Stiles 1971, Wolf and Hainsworth I971), nest building (Collias and Collias 1967, Withers 1977a), egg production (King 1973), and the feeding of nestlings (Utter and Lefebvre 1973). These activities, together with incubation of the eggs, include most of the time and energy that birds devote to reproductive activities. However, the costs of incubation, an activity that takes up a significant portion of the reproductive cycle, are difficult to measure and have been the subject of controversy (Kendeigh 1973, King 1973). Linear heat flow models have been used to make indirect estimates of the energetic cost of incubation based on the assumption that heat loss from eggs must be balanced by extra heat production by the parent (Kendeigh 1963, Ricklefs 1974). For example, Drent (1970) found that Kendeigh’ s (1963) model accurately described the heat input required to keep the eggs of Herring Gulls (Larus urgentu Mertens 1977) and Baird’ s Sandpiper, (Calidris hairi Norton 1973). However, neither author compared the oxygen consumption of incubating and non-incubating birds, and consequently it is impossible to estimate the energy expended solely for incubation. In contrast, Biebach (1977, 1979) measured the oxygen consumption of both incubating and non-incubating Starlings (Sturnus dgaris) and calculated the energetic cost of incubation at several nest temperatures. Gessaman and Findell (1979) measured CO, production of three incubating and non-incubating American Kestrels (F&o sparzjerius) but their results are ambiguous. Mertens (1980) measured heat loss from the nest of a Great Tit, using heat flux disks mounted in the nestbox walls, and found that heat loss from the bird and nest increased considerably during incubation. The energetic cost of warming cooled eggs “to the incubation temperature” has not been determined. Kendeigh et al. (1977) suggested that energy expended to rewarm eggs could be calculated from estimates of the heat needed to rewarm eggs, but this procedure ignores the inefficiency of heat transfer from the parent to the eggs. If a bird increases its heat production in order to re-

Turkey Prolactin: Validation of a Radioimmunoassay and Measurement of Changes Associated with Broodiness

Abstract: A sensitive and highly specific radioimmunoassay procedure has been developed for measuring levels of circulating turkey prolactin. Mean plasma prolactin levels in broody turkey hens were found to be 9 times those of laying hens and 23 to 50 times those of molting hens, male poults, and adult toms. The plasma prolactin concentration of laying hens was found to increase gradually beginning about 10 days prior to the onset of broodiness, and to increase sharply at about the time of persistent nesting. Interrruption of incubation behavior by nest-deprivation and constant light was associated with a precipitous decline in prolactin levels. A hen that continued to exhibit incubation behavior despite this treatment showed no decline in plasma prolactin levels. A hen that continued to exhibit incubation behavior despite this treatment showed no decline in plasma prolactin concentration. These results confirm and expand the findings of some other investigators that incubation behavior in the turkey is associated with dramatically elevated prolactin levels.

The possible role of prolactin in the regulation of nesting behaviour and the secretion of luteinizing hormone in broody bantams

Abstract: The time spent each day on the nest and the rate of formation of the brood patch before the onset of incubation were measured in bantams (Gallus domesticus) and related to changes in the concentrations of plasma LH and prolactin. The hens spent progressively more time on the nest in the 5 days before the onset of incubation so that by the first day of incubation they were spending more than 90% of their time in this way. The concentration of plasma prolactin increased while that of LH fell on successive days before the onset of incubation: the increase in plasma prolactin preceded the fall in plasma LH by 2 days. The formation of the brood patch closely followed the increase in the concentration of plasma prolactin. In four out of five bantams the increase in nesting behavior was preceded by an increase in the secretion of prolactin. An injection of chicken prolactin antiserum into bantams incubating eggs resulted in a significant (P less than 0.05) increase in the plasma concentration of LH. The observations suggest that, in the bantam, the onset of incubation is initiated by an increase in the secretion of prolactin which also suppresses the secretion of LH.

Concentrations of prolactin and luteinizing hormone in plasma of doves in relation to incubation and development of the crop gland.

Abstract: The concentrations of prolactin and LH were measured in the plasma of male and female ring doves (Streptopelia risoria) during the breeding cycle. Prolactin concentrations were low during courtship and early incubation but increased markedly (P less than 0.01 in both sexes) between days 7 and 15 of incubation, during the period of rapid growth of the crop sac. Levels remained raised for 4 days after the young had hatched but then declined as the crop sacs gradually regressed. These observations showed that concentrations of prolactin were high at the time when the crop sacs were proliferating and producing 'milk' for feeding the young, but that there was no increase in prolactin secretion at the onset of incubation as occurs in ducks, hens and other birds. In samples taken from doves at various times of the day and night there was no increase in plasma prolactin during the first few days of incubation. Concentrations of LH in plasma were generally higher in male doves than in females, but in both sexes were significantly higher during courtship than during incubation and brooding the young. Concentrations increased again when the young were independent and the parents began a second round of courtship.

Incubation during the egg-laying period in relation to clutch-size and other aspects of reproduction in the Great Tit Parus major

Abstract: The brood patch of the female was well-developed several days before the clutch was complete. Effective incubation started as soon as the first egg was laid and was combined with the nightly rest. Although lasting only 0.5-1.5 h to begin with, the time spent incubating progressively increased. Daytime incubation started later and, on average, was first fully developed 2.8 d after the night-time incubation was fully established. The rate of incubation development was significantly correlated with clutch-size and the hatching period. Because the mortality of the latest hatched young increases with age difference within broods, selection tends to keep the incubation time in the egg-laying period below a certain 'critical' level (about 1000 minutes). The possibility that the amount of time devoted to incubation in the laying period influences the endocrine state of the female and thus the clutch-size, is discussed.

Transformation in Escherichia coli: stages in the process.

Abstract: Transformation experiments with Escherichia coli recipient cells and linear chromosomal deoxyribonucleic acid (DNA) are reported. E. coli can be rendered competent for DNA uptake by a temperature shock (0 degrees C leads to 42 degrees C leads to 0 degrees C) of the recipient cells in the presence of a high concentration of either Ca2+ or Mg2+ ions. Uptake of DNA into a deoxyribonuclease-resistant form, for which the presence of Ca2+ is essential, was possible during the temperature shock but appeared to occur most readily after the heat shock during incubation at 0 degrees C. When DNA was added to cells that had been heat shocked in the presence of divalent cations only, DNA uptake also occurred. This suggests that competence induction and uptake may be regarded as separate stages. Under conditions used to induce competence, we observed an extensive release of periplasmic enzymes, probably reflecting membrane damage induced during development of competence. After the conversion of donor DNA into a deoxyribonuclease-resistant form, transformants could be selected. It appeared that incubation, before plating, of the transformation mixture in a medium containing high Ca2+ and Mg2+ concentrations and supplemented with all growth requirements increased the transformation frequency. This incubation probably causes recovery of physiologically labile cells.

Lesion growth and virus localization in leaves of Nicotiana tabacum cv. Xanthi nc. after inoculation with tobacco mosaic virus and incubation alternately at 22°C and 32°C

Abstract: Factors which determine lesion size were studied with Nicotiana tabacum L. cv. Xanthi nc. and tobacco mosaic virus (TMV). Inoculated plants were incubated alternately at 22 and 32°G. Incubation at 32°C was used as a condition under which multiplication and spread of the virus are uninhibited by the plant; incubation at 22°G for 1 day thereafter was necessary to visualize the spread of the virus at 32°C. Effect of different treatments on lesion size was compared in fully grown leaves of increasing age. Size of lesions formed at 22°G was leaf age dependent, as was size of lesions formed after incubation at 32 oC followed by 22°C. Infectivity of the virus from the latter lesions was proportional to lesion area. Increase in size of these lesions at 22°G was also leaf age dependent. The width of the zone of damaged cells around lesions formed at 22°G depended on the age of the leaves and on the age of the lesions. Lesions formed at 22°G increased in size after incubation at 32°C followed by 22°C, and this increase depended on the age of the lesions. Furthermore, with older lesions, sectorial outgrowth occurred or lesions did not grow at all. For complete localization of the virus at least 12 days at 22°G were necessary. All effects mentioned here that were leaf or lesion age dependent were smaller with increasing leaf or lesion age. After interruption of the incubation at 32°C by short periods at 22°C necroses only appeared if the interval at 22°C was longer than 5 to 6 h; the size of these necroses was larger with increasing time interval at 22°C.

Depletion of substance P‐like immunoreactivity in the cat dental pulp by antidromic nerve stimulation

Abstract: Tissue levels of substance P-like immunoreactivity (SPLI) were determined by radioimmunoassay in incubated cat dental pulps with and without previous electrical stimulation of the inferior alveolar nerve (I.A.N.). The ability of the dental pulp to degrade substance P (SP) was also studied. The pulpal SPLI levels in teeth incubated at 37 degrees C for up to 240 min immediately after removal from the jaws did not differ from those in contralateral unincubated teeth. Following I.A.N. stimulation (3-45 min at 10 V, 15 Hz and 5 ms) and subsequent incubation (30 min at 37 degrees C) of the teeth the SPLI levels in ipsilateral pulps were significantly lower (45% reduction) than those in contralateral unstimulated controls. Incubation of homogenized pulp tissue at 37 degrees C with synthetic bovine SP or 125I-Tyr8-SP led to rapid inactivation of SP, whereas similar incubation of whole blood with 125I-Tyr8-SP had little effect. Endogenous SPLI levels were also rapidly reduced (50% reduction within 3 min) in incubated pulp homogenates. Incubation at a lower temperature (22 degrees C) resulted in a somewhat reduced rate of degradation and incubation with boiled homogenates failed to inactivate SP. The results indicate that the pulp contains enzymes capable of destroying SP and that within the nerve terminals SP is stored in such a way that it is protected against degradation. The data obtained also provide further evidence for a nerve evoked release of SP.

Kinetics of extracellular release of 14C-labelled organic carbon by submerged macrophytes

Abstract: The release of extracellular organic carbon (EOC) by six submerged freshwater macrophytes was measured in time course studies with a '4C-technique. Incubation in light in an open water-flow system made it possible to assay the time courses of 14C-fixation and the simultaneous release of labelled EOC. Heterotrophic utilization of the released products by epiphytic communities was measured. Two patterns of release kinetics were found: (1) Constant rates of release occurred during the incubations, (2) The rates still increased after 24 h of incubation. During the first hours of incubation the rates of release increased in all species. Elodea reached constant rates after 2-4 h and Littorella and Ceratophyllum demersum after about 20 h. In the experiments with C. submersum and Nitella the rates of release increased almost linearly during the entire incubation period. The kinetics of release were in agreement with the molecular weight distribution of the dissolved EOC measured with gel chromatography. Low molecular weight products ( 10000 Daltons) dominated the dissolved EOC released by C. submersum and Nitella. A large fraction (18-60%) of the total EOC could be recovered on filters with a pore size of 0.2 ,tm. This particulate fraction probably represents some abiotic removal. The quantities of release were low in all species and did not exceed 0.9% of the photosynthetic carbon fixation. Heterotrophic uptake by the epiphytic communities was less than 10% of the EOC released. The results emphasize that the 14C-labelling of extracellular products is a time dependent process.

Factors affecting the induction of phenotypically determined serum resistance of Neisseria gonorrhoeae grown in media containing serum or its diffusible components.

Abstract: Phenotypically determined resistance of gonococci to killing by normal human serum can be generated by growth of susceptible organisms in media containing guinea pig, calf or human serum. However, even in the best medium tested, i.e. defined medium containing 50% (v/v) guinea pig serum, resistance was greatly reduced after 24 h incubation and the maximum number of colony-forming units generated was 107 to 108 ml-1. Resistance was not acquired after incubation in guinea pig serum at low temperature (8°C), supporting previous indications that metabolic activity was necessary for the generation of resistance. Alteration of the concentration of glutamine, proline, lactate or iron had little or no effect on the generation of serum resistance under the conditions used. Optimum conversion to resistance occurred at pH 6.0 to 6.5 and both non-diffusible and diffusate fractions of dialysed guinea pig serum promoted resistance. Furthermore, resistant organisms could be produced by incubation in defined medium containing the diffusate from guinea pig serum and 0.1% bovine serum albumin, a step which should facilitate identification of the resistance-promoting factor.

Characteristics of gonads and oviducts in hatchlings and young of Chelydra serpentina resulting from three incubation temperatures.

Abstract: Eggs of Chelydra serpentina were incubated at 30 degrees C and 26 degrees C. In addition, incubation was done at 20 degree C during the temperature-sensitive period for sex determination. Incubation at 20 degrees C and 30 degrees C resulted in females; incubation at 26 degrees C resulted in males in 99% of the cases. The average gonadal length was less in the males. The average length of the 20 degree C ovaries did not vary significantly from that of the 30 degrees C ovaries. The condition of the oviducts was correlated with histology of the gonads in hatchlings and in 3-month-old animals. When at least one of the oviducts was obvious and intact, ovaries were present. If the oviducts were absent or interrupted, testes were present. Histological characteristics of the gonads resulting from the three incubation temperatures are described. In the 26 degree C testes, cellular infiltrations occurred frequently. The ovaries of 20 degrees C hatchlings tended to have a less developed germinal epithelium than that of the 30 degrees C animals. Also, epithelial cysts occurred frequently in the 20 degrees C ovaries. The incidence of follicles at 3 months was not differential.

Respiratory Gas Exchange and Growth of White Tern Embryos

Abstract: -The parameters of respiratory gas exchange and growth in White Tern (Gygis alba) eggs were examined during natural incubation. The 02 consumption of eggs (Mo2) reached a plateau on day 32 of the 35.5-day incubation period resulting in an average Mo2 of 159 ml 02 STPD' day-' immediately prior to external pipping, and air cell gas tensions of 100 torr for 02 and 49 torr for CO2. Mo2 increased rapidly during the 5.2-day pip (star fracture)-to-hatch interval, achieving an 02 uptake of 470 ml 02 STPD day-1 in hatchling chicks. The level of pre-pipping Io02 appears to be adaptive to prolonged incubation and is related to the extent to which the incubation period deviates from the expected value based on initial egg mass. The mean pre-external pipping daily water loss (1MH20) was 78.7 mg day-' but increased to 275 mg day-' in externally pipped eggs, yielding a 17.5% total fractional mass loss over the entire incubation period. The pre-pipping cost of prolonged semi-precocial development, calculated by indirect calorimetry, was 2.71 kJ per gram yolk-free embryonic tissue. The total energy expenditure for embryonic development was 3.32 kJ per gram of hatchling tissue. The White Tern (Gygis alba) is one of only two terns with prolonged incubation (Whittow 1980). It has the longest incubation time in relation to its egg mass of any tern (Rahn et al. 1976, Whittow 1980). Available data on the incubation physiology of the White Tern suggest that it is subject to the same constraints as are other seabirds with prolonged incubation (Rahn et al. 1976, Whittow 1980). In addition, the eggs are adapted for prolonged incubation through curtailment of daily water loss from the egg; this is related to the relatively low watervapor conductance of the shell and a low egg temperature (Rahn et al. 1976, Howell 1978). In procellariiform seabirds, prolonged incubation is associated also with slow embryonic growth and an increased energy cost of incubation (Ackerman et al. 1980, Whittow 1980, Pettit et al. 1981a, b). However, the degree of development at hatching is greater in the White Tern (semiprecocial) than in the Procellariiformes, which are considered to be semi-altricial (Nice 1962). The White Tern and procellariiforms may therefore differ in the oxygen and energy cost of incubation. The present study was undertaken in order to provide information on the growth, embryonic oxygen consumption, and the energetics of incubation in the White Tern. An important part of our study was to document the even s occurring between pipping and hatching, signalling the transition from diffusi e gas transport across the pores of the shell to e convective gas transport of the lungs.

Steroid radioimmunoassay--effect of shortened incubation time on specificity.

Abstract: Use of a briefer incubation interval in several steroid radioimmunoassays markedly increases cross reactions with some closely related steroids. The dissociation rates of the various steroid/antibody complexes play a critical role in determining the specificity of the antiserum, and the maximum specificity of an antiserum will be exploited only if it is incubated to equilibrium. The commonly used method for estimating the time required to reach equilibrium--i.e., the time required for the %(B0/T) value to "plateau"--grossly underestimates the true interval required, and we suggest that the minimum incubation period for steroid radioimmunoassay should be based on a knowledge of both the dissociation and the association rate.

Aspects of incubation in ostriches

Abstract: Summary Bertram, B. C. R. & Burger, A. E. 1981. Aspects of incubation in Ostriches. Ostrich 52:36-43. We studied incubation in domesticated Ostriches Struthio camelus in South Africa and wild Ostriches in Kenya. Although the eggs were large, with relatively high thermal capacities, unattended eggs exposed to the sun reached dangerously high temperatures (40,5°C). Experimental exposure of fresh eggs to the sun for seven days prior to incubation greatly reduced the percentage of embryos which developed, and no embryos survived 15 days of exposure. In the wild. Ostriches frequently shade their eggs in the pre-incubation period to prevent overheating. During natural incubation, temperatures in the eggs (range 30,8-33,8°C) and of nest-air (31,9-34,6°C) were remarkably constant, despite the daily ambient fluctuations of air temperatures (17,8-38,9°C). Similarly the humidity of the nest-air (39–52%) was lower and less variable than the ambient air (39–72%). Water loss during 42 days of incubation was 11–12% of i...

Factors Affecting the Induction of Secondary Dormancy in Lettuce

Abstract: The relationship between the temperature at which germination of 50% of the seeds is inhibited in the light (GT(50) Light) and secondary dormancy was investigated in three cultivars of Lactuca sativa L. Seeds were incubated for varying periods under non-germinating conditions and subsequent germination in response to red light (R) was determined over a wide range of temperatures. Dark incubation at 32 C reduced the GT(50) Light of cv. New York but did not affect germination at temperatures below 24 C. Dark, 32 C incubation had no effect on the GT(50) Light of cv. Great Lakes. In cv. Grand Rapids, dark incubation at 15, 24, 32, or 35 C initially reduced the GT(50) Light. However, longer incubations induced a secondary dormancy, i.e., the seeds became unable to germinate at all temperatures in response to R given after the high temperature incubation. A single exposure to R at the beginning of a 32 C incubation slowed the induction of secondary dormancy. Repeated exposures to R prevented the induction of secondary dormancy, but did not prevent a decline in the GT(50) Light. GA(3) mimicked the effect of repeated R.The differences in the germination behavior of the three cultivars suggest that there may be qualitative differences in the germination mechanism of these cultivars. This research demonstrates the significance of monitoring germination at a range of temperatures to avoid misinterpretation of the data.

Effects of thyroid hormones and thyrotropin-releasing hormone on thyrotropin biosynthesis by mouse pituitary tumor cells in vitro.

Abstract: Mouse thyrotropic tumor cells grown in primary culture were shown to synthesize TSH and proteins, as determined by the incorporation of radioactive proline into immunoprecipitable TSH and trichloroacetic acid-precipitable proteins. The net TSH content of the cells and medium determined by RIA is also increased during 24 h of incubation, and newly formed hormone is detected in the medium within 1 h after the addition of proline tracer. To study the effect of T4 and T3 on TSH synthesis, cultures were pulse-labeled with [3H]proline after they had been exposed to either T3 or T4. After 48 but not 24 h, exposure to either T3 or T4 was followed by inhibition. When studied after 48 h of incubation, T4, (10-13 M) or T3 (10-11 M) at the lowest concentration tested, was inhibitory to TSH synthesis. At concentrations of T4 and T3 greater than 10-9 M, the inhibitory effects on TSH synthesis were partially reversed, suggesting a biphasic response. Incubation in TRH (10-7 M) for 24 h led to a significant increase in TS...

Determination of Scrapie Agent Titer from Incubation Period Measurements in Hamsters

Abstract: One of the most distinctive and remarkable features of slow virus infections is the prolonged incubation period during which the host is free of disease (1). These long incubation periods terminate with the onset of clinical disease which progresses to death in a relatively short time. Considerable interest has surrounded the mechanisms regulating the length of the incubation periods of the spongiform encephalopathies: scrapie of sheep and goats, transmissible encephalopathy of mink, and kuru and Creutzfeldt-Jakob disease (CJD) of humans (2,3). Factors controlling the length of the incubation period in scrapie include: the dose of agent, the genetic background of the host, the strain and passage history of the agent, the lymphoid system of the host, and the metabolic and endocrinological state of the host (4, 5). The shortest incubation periods are found in scrapie, where hamsters develop clinical disease in two months, while the longest incubation periods approach three decades in kuru and probably CJD (6–8).

Effects of postdecapitative ischemia on arachidonate release from brain synaptosomes

Abstract: Synaptosomal phosphoglycerides were labeled after incubation with [1-14C]arachidonic acid, ATP, Mg2+, CoASH, and a small amount of 1-acylglycerophosphocholines Under this incubation system, radioactivity was directed largely to diacylglycerophosphocholines but diacylglycerophosphoinositols were also labeled to a lesser extent Synaptosomes obtained after a 5-min ischemic treatment indicated a decrease (10–20%) in incorporation of radioactivity into the phospholipids The ischemic synaptosomes also tended to retain a larger portion of the labeled arachidonate during the wash with bovine serum albumin Upon incubation of the prelabeled synaptosomes in a sucrose-Tris (pH 74) medium at 37°C, a time-dependent release of labeled arachidonate from the phospholipids was observed in both control and ischemic samples Arachidonate release from the prelabeled synaptosomes was not affected by EDTA (1 mM) or taurocholate (04%) but was stimulated by Ca2+ (25 mM) or Ca2+ (35 mM) together with EDTA (1 mM) After incubation at 37°C for 1 hr without added factors, the phospholipid degradation, as well as the appearance of free fatty acids, were higher in the ischemic samples (especially after 1 min of treament) as compared to controls

Water Relations of Desert Iguana (Dipsosaurus dorsalis) Eggs

Abstract: Egg mass increased for about the first 65% of the incubation period, and then declined. The mean maximum gain in mass was 47.6%, and on the last day of incubation the mean mass of an egg was 32.7% greater than the mass at oviposition. The water potential of eggs varied throughout incubation. Frequent measurements are required to define the complex changes in egg mass and water potential that occur during incubation. Changes in the water potential of an egg may be related to ontogenetic patterns of nitrogen excretion. Calculated net hydraulic conductance varied throughout incubation. It may be inappropriate to define a unique hydraulic conductance value to reptile eggs with membranous shells. Measurements of mass change and water potential of eggs indicate that eggs may simultaneously transpire and absorb water while maintaining a net water potential below ambient water potential. Metabolic heat generation and active regulation of solute concentrations in extraembryonic water compartments may explain these...