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Showing papers on "Incubation published in 2003"


Journal ArticleDOI
TL;DR: Results show that casts are an efficient source of plant nutrients and that they are less likely to produce salinity stress in container as compared to compost and synthetic fertilizers.
Abstract: Vermicomposting differs from conventional composting because the organic material is processed by the digestive systems of worms. The egested casts can be used to improve the fertility and physical characteristics of soil and potting media. In this study, the effects of earthworm casts (EW), conventional compost (CP) and NPK inorganic fertilizer (FT) amendments on N mineralization rates, microbial respiration, and microbial biomass were investigated in a laboratory incubation study. A bioassay with wheat ( Triticum aestivium L.) was also conducted to assess the amendment effects on plant growth and nutrient uptake and to validate the nutrient release results from the incubation study. Both microbial respiration and biomass were significantly greater in the CP treatment compared to EW treatment for the initial 35 days of incubation followed by similar respiration rates and biomass to the end of the study at 70 days of incubation. Soil NO 3 − increased rapidly in the EW and CP treatments in the initial 30 days of incubation, attaining 290 and 400 mg N kg −1 soil, respectively. Nitrate in the EW treatment then declined to 120 mg N kg −1 soil by day 70, while nitrate in the CP treatment remained high. While ammonium levels decreased in the CP treatment as nitrate level increased with increasing incubation time, a low level of ammonium was maintained in the EW treatment throughout the incubation. The wheat bioassay study included two additional cast treatments (EW-N and EW2) to have treatments with higher levels of N input. Plants grown with CP or FT treatment had a lower shoot biomass and higher shoot N content than in EW-N and EW-2 treatments, and also showed symptoms of salinity stress. Ionic strength and other salinity indicators in the earthworm cast treatments were much lower than in the CP treatment, indicating a lower risk of salinity stress in casts than in compost. All cast and compost amendments significantly increased wheat P and K uptake compared to either the non-amended control or the mineral fertilizer treatment. The results show that casts are an efficient source of plant nutrients and that they are less likely to produce salinity stress in container as compared to compost and synthetic fertilizers.

330 citations


Journal ArticleDOI
TL;DR: Growth and metabolism of five probiotic strains with well-documented health effects were studied in ultra-high temperature (UHT) treated milk and the importance of controlling the fermentation time since the probiotics produced different amounts of metabolic products according to fermentation time is shown.

207 citations


Journal ArticleDOI
TL;DR: It is demonstrated that infection of egg contents is prevalent and occurs within the time required to lay a clutch, and that microbial infection and ambient temperature act independently to reduce egg viability considerably.
Abstract: Many birds initiate incubation before clutch completion, which results in asynchronous hatching. The ensuing within-brood size disparity often places later-hatched nestlings at a developmental disadvantage, but the functional significance of the timing of the onset of incubation is poorly understood. Early incubation may serve to maintain the viability of early-laid eggs, which declines over time owing to the putative effects of ambient temperature. An unexplored risk to egg viability is trans-shell infection by micro-organisms. We experimentally investigated the rate and magnitude of microbial trans-shell infection of the egg, and the relative effects of ambient temperature and micro-organisms on hatching success. We show that infection of egg contents is prevalent and occurs within the time required to lay a clutch. The probability of infection depends on the climatic conditions, the exposure period and the phylogenetic composition of the eggshell microbiota. We also demonstrate that microbial infection and ambient temperature act independently to reduce egg viability considerably. Our results suggest that these two factors could affect the onset of avian incubation in a wide range of environments.

177 citations


Journal ArticleDOI
TL;DR: The most noticeable advantage of incubating eggs at the fluctuating temperature regime designed in this study is to widen the range of incubation temperatures yielding larger and well-performed hatchlings.

138 citations


Journal ArticleDOI
TL;DR: The discovery of a previously undescribed chimeric transgene with abbreviated incubation times for sCJD prions should facilitate studies on the prion species barrier and human prion diversity.
Abstract: Transgenic (Tg) mouse lines that express chimeric mouse–human prion protein (PrP), designated MHu2M, are susceptible to prions from patients with sporadic Creutzfeldt–Jakob disease (sCJD). With the aim of decreasing the incubation time to fewer than 200 days, we constructed transgenes in which one or more of the nine human residues in MHu2M were changed to mouse. The construct with murine residues at positions 165 and 167 was expressed in Tg(MHu2M,M165V,E167Q) mice and resulted in shortening the incubation time to ≈110 days for prions from sCJD patients. The construct with a murine residue at position 96 resulted in lengthening the incubation time to more than 280 days for sCJD prions. When murine residues 96, 165, and 167 were expressed, the abbreviated incubation times for sCJD prions were abolished. Variant CJD prions showed prolonged incubation times between 300 and 700 days in Tg(MHu2M) mice on first passage and incubation times of ≈350 days in Tg(MHu2M,M165V,E167Q) mice. On second and third passages of variant CJD prions in Tg(MHu2M) mice, multiple strains of prions were detected based on incubation times and the sizes of the protease-resistant, deglycosylated PrPSc fragments. Our discovery of a previously undescribed chimeric transgene with abbreviated incubation times for sCJD prions should facilitate studies on the prion species barrier and human prion diversity.

127 citations


Journal ArticleDOI
TL;DR: It is suggested that low concentrations of sucrose act as a metabolic substrate for the low-temperature-induced alterations required for the amelioration of EIL and, at higher concentrations, sucrose has a direct cryoprotective effect to minimize LOR.
Abstract: Sugar content and freezing tolerance of protoplasts of Arabidopsis thaliana leaves were manipulated by incubating seedlings in a sucrose solution before protoplast isolation. Incubation in a 400 mM sucrose solution at 2 °C in the dark increased their freezing tolerance equivalent to that achieved after a conventional cold acclimation at 2 °C. The increased freezing tolerance was due to a decrease in the incidence of freeze-induced lesions: expansion-induced lysis (EIL) between −2 and −4 °C and loss of osmotic responsiveness (LOR) between −5 and −12 °C. The concentration of sucrose in the incubation medium required to minimize the incidence of the lesions was substantially different: 10–35 mM for EIL and 30–400 mM for LOR. Incubation in the sucrose solution at 23 °C decreased LOR only at −5 and −6 °C but less than that incubated at 2 °C, and there was no effect on EIL. Incubation in sorbitol solutions at 2 °C also decreased LOR at −5 and −6 °C but much less than in the sucrose solution. These results suggest that low concentrations of sucrose act as a metabolic substrate for the low-temperature-induced alterations required for the amelioration of EIL and, at higher concentrations, sucrose has a direct cryoprotective effect to minimize LOR.

101 citations


Journal ArticleDOI
TL;DR: The results revealed that breeder diets should be investigated for aflatoxins and specifically AFB1, in cases of low hatchability and flock immunity, because low concentration of AFB1 transferred into the fertilised eggs might be the cause of serious problems.
Abstract: 1. In this study, embryotoxicity and effects of in ovo administration of aflatoxin B1 (AFB1) on the embryonic development of the bursa of Fabricius were determined in fertilised chicken eggs by histological methods and histochemical demonstration of acid phosphatase (ACP-ase) enzyme. Peripheral blood lymphocyte percentages were also estimated. 2. Embryonic stages were determined according to the Hamburger-Hamilton (H-H) scale. Mortality rates increased in AFB1-injected groups in a dose-dependent manner. Embryonic deaths were concentrated at H-H 31 in the 5 ng AFB1/egg group while the deaths were highest at H-H 25 in the 10 and 20 ng AFB1/egg groups. In the 40 ng AFB1/egg group, embryonic deaths mostly occurred during the first 70 to 72 h of incubation (H-H 20). 3. Bursal development was quite similar at d 7 of incubation in control and all experimental groups although development had been substantially impaired and retarded at d 10 of incubation in 10, 20 and 40 ng AFB1/egg groups. A gradual decrease of A...

101 citations


Journal ArticleDOI
TL;DR: Observations suggest strongly that heating and passive stretch of muscle may be useful as a means of increasing muscle mass, not only in athletes but also in patients during rehabilitation.
Abstract: Effects of heat stress, mechanical stretching or a combination of both on the expression of heat shock proteins (HSPs) and total protein level were studied in a culture system. Rat skeletal muscle cells (L6) were cultured on flexible-bottomed culture plates. They were subjected to one of the four following conditions: (1) 97 h incubation at 37 °C, (2) 1 h incubation at 41 °C followed by 96 h incubation at 37 °C, (3) 1 h incubation at 37 °C followed by 96 h cyclic stretching (18% of initial length, 2-s stretch and 4-s release) at 37 °C or (4) 1 h incubation at 41 °C followed by 96 h cyclic stretching at 37 °C. The expression of HSP72 and HSP90 and total protein was determined in the crude homogenates, supernatant and pellets. Cellular protein concentrations in the homogenates and pellets were increased by heat stress and/or mechanical stress (stretch). A cumulative effect of the combination of heating and stretch on the protein concentration in the homogenates and in the pellets was noted. The expressions of HSP72 and HSP90 in the pellets were also increased by heat stress and/or stretch. However, HSP90 in the supernatant did not change following heat stress and/or stretch. The regulation of HSP72 and HSP90 expression in skeletal muscle cells may be closely related to total protein, the abundance of which is also stimulated by mechanical and heat stresses. These observations suggest strongly that heating and passive stretch of muscle may be useful as a means of increasing muscle mass, not only in athletes but also in patients during rehabilitation.

100 citations


Journal ArticleDOI
TL;DR: Although cooling and heating of eggs during incubation influenced growth of the skeletal traits on d 10 and 18, compensation generally occurred by the time of hatch and the developmental stability of bilateral traits varied with the specific trait, with those observed earlier in incubation tending to decrease by hatch.

87 citations


Journal ArticleDOI
TL;DR: It is unlikely that maternal androgens are a key factor in the avian sex determination mechanism, as testosterone levels in chicken eggs do not change with incubation period.

86 citations


Journal ArticleDOI
TL;DR: In this article, a laboratory incubation experiment was conducted to investigate the fates of plant-derived C during the simulated fallow period in a rice soil, and the results showed that the decomposition of the incorporated residues could be divided into two phases: an initial rapid phase followed by a slower phase of decomposition.
Abstract: A laboratory incubation experiment was conducted to investigate the fates of plant-derived C during the simulated fallow period in a rice soil. The 13C labelled soil and plant materials were used to follow the residue decomposition and its effect on soil organic C (SOC) dynamics under the conditions of either incorporation into soil or intact root systems. The soils were incubated at 15 °C for 240 d and destructive sampling was conducted at 60, 150 and 240 d. To observe the temperature effect, one batch of incubation was shifted from 15 to 25 °C during the last 45 d (between 195 and 240 d). The results showed that the decomposition of the incorporated residues could be divided into two phases: an initial rapid phase followed by a slower phase of decomposition. The decomposition of straw residues was faster than root residues: with 73% of the straw residue being decomposed, compared with 56% of the root residue over 240-d incubation at 15 °C. The water-soluble organic C and microbial biomass C significantly increased after residue incorporation. The total SOC contents, however, slightly decreased, although significant amounts of straw C (14.2%) and root C (8.7%) were found in SOC at the end of incubation, suggesting that the degradation of native SOC occurred concomitantly. Similar to decomposition of the incorporated residues, the organic substances derived from rhizodeposition of the previous season were mineralized rapidly at first and then slowly. The decomposition of the intact root system, however, was extremely slow. This result suggested that the intact root system conserved more organic C in soils compared with the incorporation of fresh residues. Increase of temperature from 15 to 25 °C during the last 45-days of incubation significantly promoted the residue decomposition.

Journal ArticleDOI
TL;DR: In this paper, a comparative decomposition of tropical leaf litters (e.g. Andropogon gayanus, Casuarina equisetifolia, Faidherbia albida) of different qualities was investigated under laboratory conditions during a 60-day incubation period conducted with a typical oxisol.
Abstract: The comparative decomposition of tropical leaf litters (e.g. Andropogon gayanus, Casuarina equisetifolia, Faidherbia albida) of different qualities was investigated under laboratory conditions during a 60-day incubation period conducted with a typical oxisol. Total CO2-C, soil inorganic N, microbial biomass (fumigation-extraction), β-glucosidase and dehydrogenase activities were determined over the incubation to assess how they responded to the addition of inorganic N (+N). Cumulative CO2-C evolved from the litter-amended soils was higher than that recorded for the unamended control soil. For the unfertilized treatment (0 N), correlation coefficients calculated between initial chemical data and CO2 flux during the first day of incubation were r =0.963 for water soluble-C and 0.869 for soluble carbohydrates (P <0.05). At the end of the incubation, the amounts of CO2-C in the F. albida- and A. gayanus-amended soils were higher than that in the C. equisetifolia-amended treatment. Cumulative net N immobilization increased during the first 30 days of incubation, the amounts being similar for A. gayanus- and C. equisetifolia-amended soil and higher than that recorded in the F. albida-amended treatment. Soil microbial biomass and enzyme activities increased in the litter-amended soils during the first 15 days of incubation and decreased (except for the dehydrogenase activity) thereafter. The addition of inorganic N modified the patterns of CO2-C respiration and net N immobilization. The magnitude of these modifications varied according to the litter quality. The use of an accurate indicator based on several litter components to predict the amplitude of organic material decomposition is discussed.

Journal ArticleDOI
TL;DR: The compensatory interaction between the onset of incubation and the sex‐biased laying order achieved a compromise between maternal and offspring adaptations and contributed to rapid morphological divergence in sexual dimorphism between populations of the house finch breeding at the climatic extremes of the species range.
Abstract: The phenotype of a mother and the environment that she provides might differentially affect the phenotypes of her sons and daughters, leading to change in sexual size dimorphism. Whereas these maternal effects should evolve to accommodate the adaptations of both the maternal and offspring generations, the mechanisms by which this is accomplished are rarely known. In birds, females adjust the onset of incubation (coincident with the first egg or after all eggs are laid) in response to the environment during breeding, and thus, indirectly, determine the duration of offspring growth. In the two house finch (Carpodacus mexicanus) populations that breed at the extremes of the species' distribution (Montana and Alabama), females experience highly distinct climatic conditions during nesting. We show that in close association with these conditions, females adjusted jointly the onset of incubation and the sequence in which they produced male and female eggs and consequently modified the growth of sons and daughters. The onset of incubation in newly breeding females closely tracked ambient temperature in a pattern consistent with the main- tenance of egg viability. Because of the very different climates in Montana and Alabama, females in these populations showed the opposite patterns of seasonal change in incubation onset and the opposite sex bias in egg-laying order. In females with breeding experience, incubation onset and sex bias in laying order were closely linked regardless of the climatic variation. In nests in which incubation began with the onset of egg laying, the first-laid eggs were mostly females in Montana, but mostly males in Alabama. Because in both populations, male, but not female, embryos grew faster when exposed to longer incubation, the sex-bias produced highly divergent sizes of male and female juveniles between the populations. Overall, the compensatory interaction between the onset of incubation and the sex-biased laying order achieved a compromise between maternal and offspring adaptations and contributed to rapid morphological divergence in sexual dimorphism between populations of the house finch breeding at the climatic extremes of the species range.

Journal ArticleDOI
TL;DR: It is demonstrated that plasma and yolking follicle steroid levels produced by breeding females can be uncoupled, and steroid exposure may be independently shaped by selection to serve both reproductive and developmental functions.

Journal ArticleDOI
TL;DR: It is suggested that food availability acts in a proximate way to modify the extent of incubation attendance and hatching asynchrony in the Australian reed warbler Acrocephalus australis.
Abstract: The amount of time a bird allocates to incubation is likely to be limited by energetic constraints. If food is abundant, energetic constraints may be reduced and the time spent incubating (incubation attendance) may increase. Moreover, the onset of incubation in relation to clutch completion may be advanced, resulting in a higher degree of hatching asynchrony. We measured the effect of experimentally increased food availability on incubation attendance and an estimate of hatching asynchrony in the Australian reed warbler Acrocephalus australis. Supplementary food was provided every other day, from a few days before the start of egg laying until just prior to hatching. Incubation attendance was measured with temperature loggers at nests receiving supplementary food and control nests. Hatching asynchrony was inferred from mass and size differences between siblings shortly after hatching. We found that 1) food supplementation resulted in an increase in incubation attendance, when comparing both nests receiving supplementary food to control nests as well as feeding to non-feeding days in nests receiving supplementary food, and 2) food supplementation resulted in a greater hatching asynchrony, without affecting clutch size, average egg volume or the likelihood of eggs hatching. This suggests that food availability acts in a proximate way to modify the extent of incubation attendance and hatching asynchrony. We discuss the adaptive significance of increased incubation attendance and a shift in the degree of hatching asynchrony in relation to food availability.


Journal ArticleDOI
TL;DR: The data support previous work that P. sinensis does not have temperature-dependent sex determination, and add evidence for the prediction that turtles within the Trionychidae have genotypic sex determination exclusively.
Abstract: Eggs of Pelodiscus sinensis were incubated under one fluctuating and four constant temperatures, and hatchlings from different incubation temperatures were maintained under identical conditions to assess the effects of incubation temperature on sexual phenotype and hatchling growth. The incubation length decreased as temperature increased, but it did not differ between sexes within each temperature treatment. Hatching success was higher at intermediate temperatures (28 ◦ C, 30 ◦ Ca nd the fl uctuating temperature regime) than at low (24 ◦ C) and high (34 ◦ C) temperatures. The sex ratio of hatchlings did not differ from equality within each temperature treatment. Thus, our data support previous work that P. sinensis does not have temperature-dependent sex determination, and add evidence for the prediction that turtles within the Trionychidae have genotypic sex determination exclusively. Incubation temperature affected hatchling mass, with hatchlings from intermediate incubation temperatures being heavier than those from low (24 ◦ C) and high (34 ◦ C) incubation temperatures. Hatching size was not a predictor of post-hatching growth. Incubation temperature affected hatchling growth, with hatchlings from 24 ◦ Co verall growing faster than did hatchlings from higher incubation temperatures. The influence of incubation temperature on hatchling growth was well buffered within the range of constant temperatures from 28 ◦ Ct o 34 ◦ C. Fluctuating incubation temperatures augmented male growth but reduced female growth, as female embryos were more vulnerable to extremely high temperatures.

Journal ArticleDOI
TL;DR: A real-time reverse transcription-PCR system has been used to monitor the expression of an aflatoxin biosynthetic gene of Aspergillus flavus in wheat, and the number of nor-1 gene copies was determined during the course of incubation as a parameter for fungal growth.
Abstract: A real-time reverse transcription-PCR system has been used to monitor the expression of an aflatoxin biosynthetic gene of Aspergillus flavus in wheat. Therefore, total RNA was isolated from infected wheat samples, reverse transcribed and subjected to real-time PCR. In parallel all samples were analyzed by high-pressure liquid chromatography for aflatoxin B(1) production. The primer-probe system of the real-time PCR was targeted against nor-1, a gene of the aflatoxin biosynthetic pathway. By application of this method the nor-1 transcription was quantified during the course of incubation. After 4 days of incubation nor-1 mRNA could be detected for the first time. The amount of nor-1 mRNA increased rapidly, and the maximum was achieved after 6 days. Then, starting very slowly, the mRNA was degraded until day 8, and this was followed by a very fast degradation, reaching nondetectable levels at days 9 and 10. First traces of aflatoxin B(1)could be detected between the 5th and 6th day of incubation. The aflatoxin concentration reached its maximum after 9 days of incubation and remained constant for the whole period of observation. To ensure that differences in the nor-1 mRNA concentration were due to different expression levels, the expression of the constitutively expressed beta-tubulin gene (benA56) has also been monitored. The expression of benA56 remained constant during the whole incubation time. As a parameter for fungal growth, the number of nor-1 gene copies was determined during the course of incubation. The numbers of nor-1 gene copies increased at the beginning of the incubation and reached a plateau at day 5. They correlate well with the viable counts albeit at a higher level.

Journal ArticleDOI
TL;DR: The results suggest that bout length in semipalmated sandpipers is constrained by their cumulative energetic expenditure during an incubation bout, and this is determined partly by the high costs of steady-state incubation.
Abstract: The high energetic demands of incubation in birds may be an important ecological factor limiting the evolution of life-history traits, such as clutch size. In biparental species, however, the demands of incubation may not be a major constraint because there may always be sufficient feeding time available for the off-duty bird to regain energy used during an incubation bout. We investigated whether the energetic demands of incubation constrain optimum incubation bout length in a biparental incubator by decreasing the energetic demands of incubation. We put an insulated cup around the lining of semipalmated sandpiper nests so that the rate of cooling of eggs was reduced by 21%. Semipalmated sandpipers responded by increasing their mean incubation bout length of around 11.1 h by about 10%. Bout lengths in unmanipulated natural nests became longer as hatch approached (incubation stage), and this was independent of weather. Bout lengths may have decreased with increasing rainfall and were independent of time of day. The results suggest that bout length in semipalmated sandpipers is constrained by their cumulative energetic expenditure during an incubation bout, and this is determined partly by the high costs of steady-state incubation. The results also suggest that the incubating bird determines the bout length rather than the returning bird. Semipalmated sandpipersmay have maximized incubation bout length to minimize changeovers during incubation because these probably increasepredation risk. Selection to minimize the frequency of changeover may then be a factor contributing to the evolution ofbiparental care and life-history traits in semipalmated sandpipers. Copyright 2003.

Journal ArticleDOI
TL;DR: While humification is a bulk property, with C breakdown and stabilization occurring simultaneously and continuously in soil, its early stages can be effectively monitored for fresh plant residues as well as effects on plant root development.
Abstract: Bulk and low molecular weight (LMW) (<1 kDa) water-extractable carbon were collected from fresh and microbially degraded wheat straw (Triticum aestivum L.) and crimson clover (Trifolium incarnatum L.) residues to monitor early-stage humification over an 8-wk incubation. Copper complexation parameters were determined for both bulk and LMW water-extractable C for both plant materials in a separate 1-wk incubation. Humification progressed through increasing molar absorptivity (A285) and phenolic and total acidity (TA), and through an increase in average molecular size and degree of polymerization as determined by ultrafiltration and changes in fluorescence peak locations. Such dynamic transformations demonstrate that while humification is a bulk property, with C breakdown and stabilization occurring simultaneously and continuously in soil, its early stages can be effectively monitored for fresh plant residues. Significant changes consistently occurred during the first 7 d of the incubation and were more pronounced for LMW fractions than bulk extracts. For both residues, water-extractable C extracted initially and following a 7-d incubation desorbed and complexed 0.11 to 0.55 mmol resin-bound Cu g(-1) C. Low molecular weight water-extractable C generated the higher values within this range, and values increased consistently following incubation. Potential concerns regarding LMW soluble Cu complexes include percolation through soils or runoff into adjacent water bodies as well as effects on plant root development.

Journal ArticleDOI
TL;DR: It is suggested that only females in good condition can afford to adopt a strategy of increasing bout length early in incubation; females in poorer condition first have to recover their body condition after having produced a clutch.

Journal ArticleDOI
TL;DR: In both populations of the house finch that breed at the climatic extremes of the species' geographical range, the timing of incubation onset was closely associated with the bias in the sequence in which male and female eggs were laid within a clutch, emphasizing that maternal effects on offspring can be influenced by ecological conditions experienced by parental generation.
Abstract: Maternal phenotype and maternal environment can profoundly affect the phenotype and fitness of offspring. Yet the causes of variation in such maternal effects are rarely known. Embryos in avian eggs cannot develop without being incubated and this creates an opportunity for maternal control of duration and onset of offspring development. However, females might adjust the start of incubation (e.g., coincident with the first egg or delayed until after egg-laying) in response to environmental conditions that they experience at the time of breeding. We studied two populations of the house finch (Carpodacus mexicanus) that breed at the climatic extremes of the species' geographical range (Montana and Alabama) and found that in both populations, the timing of incubation onset was closely associated with the bias in the sequence in which male and female eggs were laid within a clutch. When females started incubation with the first egg, they produced sons and daughters in highly biased sequence, when females delayed the onset of incubation until after the egg-laying, the sequence of sons and daughters was not biased. Because in both populations, onset of incubation was associated with the ambient temperature, these results emphasize that maternal effects on offspring can be influenced by ecological conditions experienced by parental generation.

Journal ArticleDOI
TL;DR: A new methodology based on maximum likelihood model selection that evaluates and ranks the performance of four descriptive models of sex determination for discrete datasets is proposed that has the added benefit of giving standardized definitions of two commonly reported parameters of TSD: the pivotal temperature and the transitional range of temperature.
Abstract: Sex determination in some reptiles is independent of egg incubation temperature and is called genotypic sex determination (GSD) In many other reptiles, sexual phenotype is dependent on incubation

Journal ArticleDOI
TL;DR: The S. epidermidis and S. aureus strains showed significantly lower biofilm production when grown in a CO2-rich environment compared to that exhibited in aerobic incubation, while S. sciuri biofilm formation was very low regardless of the experimental conditions used.

Journal ArticleDOI
TL;DR: Data indicate that the maturation of cardiovascular control systems differs between white leghorn chickens and emus, inviting investigation of additional avian species to determine other patterns.
Abstract: Our understanding of avian embryonic cardiovascular regulation has been based on studies in chickens. The present study was undertaken to determine if the patterns established in chickens are generally applicable to the emu, a ratite bird species. We studied cardiovascular physiology over the interval from 60% to 90% of the emu’s 50-day incubation period. During this period, embryonic emus exhibit a slight fall in resting heart rate (from 171·beats·min ‐1 to 154·beats·min ‐1 ) and a doubling of mean arterial pressure (from 1.2·kPa to 2.6·kPa). Exposures to 15% or 10% O2 initially decreased heart rate during the first period of emu incubation studied [60% of incubation (60%I)] but increased heart rate in the 90%I group. Arterial pressure responded to hypoxia with an initial depression (‐1.6·kPa) at 60%I and 70%I but showed no response during the later periods of incubation (80%I and 90%I). In addition, tonic stimulation of both cholinergic and adrenergic (α and β) receptors was present on heart rate at 70%I, with the cholinergic and βadrenergic tone increasing in strength by 90%I. Arterial pressure was dependent on a constant β-adrenergic and constant α-adrenergic tone from 60%I to 90%I. A comparison with embryonic white leghorn chickens over a similar window of incubation revealed that emus and white leghorn chickens both possess an adrenergic tone on heart rate and pressure but that only emus possess a cholinergic tone on heart rate. Collectively, these data indicate that the maturation of cardiovascular control systems differs between white leghorn chickens and emus, inviting investigation of additional avian species to determine other patterns.

Journal ArticleDOI
TL;DR: It appears that both SI and SGLT-1 mRNA are expressed before hatch in the chick, but the ontogeny of expression is controlled by different mechanisms.
Abstract: Ingestion of carbohydrates from the small intestine is the major route of energy supply in animals In mammals these functions develop both pre- and postnatally and are coordinated for the sucking period In birds, the physiological requirements are different and hatchlings ingest diets rich in complex carbohydrates soon after hatching The present study examined the ontogeny of intestinal carbohydrate uptake in the chicken The expression of mRNA for a brush border enzyme, sucrase-isomaltase (SI), which is critical in disaccharide digestion, was determined, together with that of the Na-glucose transporter (SGLT)-1, which is the major apical glucose transporter, In addition, the homeobox gene cdx, which is involved in inducing SI expression in mammals was examined It was found that the expression of cdxA mRNA and cdxA protein increased from day 15 of incubation until hatch, after which further changes were small CdxA protein was shown to bind to the promoter region of SI in the chick indicating that cdxA is similar to the mammalian cdx2 The mRNA of SI was observed at 15 d incubation, increased from 17 d of incubation to a peak on day 19, decreased at hatch and had a further peak of expression 2 d post-hatch In contrast, the mRNA of SGLT-1 was not detected until 19 d of incubation when a major peak of expression was observed followed by a decrease to low levels at hatch and small increases post-hatch It appears that both SI and SGLT-1 mRNA are expressed before hatch in the chick, but the ontogeny of expression is controlled by different mechanisms

Journal ArticleDOI
TL;DR: Genotyping of poultry and lamb isolates revealed profound differences in the types obtained, and the incubation temperature of Preston media selects for certain genotypes of C. jejuni, and to detect the widest range, samples should be incubated at both 37 and 42°C.
Abstract: Preston broth and agar incubated at either 37 or 42°C have been widely used to isolate campylobacters from foodstuffs. The consequences of using either incubation temperature were investigated. Retail packs of raw chicken (n = 24) and raw lamb liver (n = 30) were purchased. Samples were incubated in Preston broth at 37 and 42°C and then streaked onto Preston agar and incubated as before. Two Campylobacter isolates per treatment were characterized. Poultry isolates were genotyped by random amplification of polymorphic DNA (RAPD), pulsed-field gel electrophoresis (PFGE), and flagellin PCR-restriction fragment length polymorphism, and lamb isolates were genotyped by RAPD only. In total, 96% of the poultry and 73% of the lamb samples yielded campylobacters. The lamb isolates were all Campylobacter jejuni, as were 96% of the poultry isolates, with the remainder being Campylobacter lari. The incubation temperature had no significant effect on the number of positive samples or on the species isolated. However, genotyping of the C. jejuni isolates revealed profound differences in the types obtained. Overall (from poultry and lamb), the use of a single incubation temperature, 37°C, gave 56% of the total number of RAPD C. jejuni genotypes, and hence, 44% remained undetected. The effect was especially marked in the poultry samples, where incubation at 37°C gave 47% of the PFGE genotypes but 53% were exclusively recovered after incubation at 42°C. Thus, the incubation temperature of Preston media selects for certain genotypes of C. jejuni, and to detect the widest range, samples should be incubated at both 37 and 42°C. Conversely, genotyping results arising from the use of a single incubation temperature should be interpreted with caution.

Journal ArticleDOI
TL;DR: It is demonstrated that different incubation temperatures during trout embryonic development did not change the stage of somatotroph cell appearance and variations of embryo growth in response to temperature could be associated with modifications in the gene expression of the GH/IGF system.
Abstract: In fish, the GH/IGF system installs very early during development suggesting that this system could promote embryonic growth and development. In contrast to mammals, the embryonic growth rate of poikilotherms depends considerably on the incubation temperature. Therefore, the aim of this study was to determine if variations of embryo growth in response to temperature could be associated with modifications in the gene expression of the GH/IGF system. In this study, using whole mount in situ hybridisation, we demonstrated that embryo incubation temperature (4, 8, and 12 degrees C) did not change the timing of GH-1 and GH-2 mRNA expression in somatotroph cells (stage 24). Similarly, at hatching (stage 30), we did not observe an obvious difference in GH protein and GH-1 and GH-2 transcript amounts in relation to the incubation temperature. Furthermore, from stage 22 to 25, the highest temperature led to a specific up-regulation of IGF-2 (2-fold between 4 and 12 degrees C), and both IGF-RIa and IGFRIb mRNA (1.5-fold between 4 and 12 degrees C), while no difference was observed for IGF-1 mRNA. Conversely, at hatching, the highest temperature specifically down-regulated IGF-2 (3-fold between 4 and 12 degrees C) and both IGF receptor mRNAs (2 fold between 4 and 12 degrees C) present in the head, while no difference was observed in the trunk. Our results demonstrated that different incubation temperatures during trout embryonic development did not change the stage of somatotroph cell appearance. Before hatching, IGF-2 and both IGF receptors, but not IGF-1 mRNA, were specifically up-regulated by high temperatures and could be related to the enhancement of embryonic growth rate.

Journal ArticleDOI
01 Jan 2003-Oikos
TL;DR: It is suggested that the unsuccessful females are of lower quality and had higher costs from parasite infections than birds which completed incubation, and that the higher return rate for treated unsuccessful females may mean that costs of parasites are substantial, and the potential fitness gain from investment in parasite defense and avoidance is large.
Abstract: Parasites are exploiting their host for the resources required for the parasite’s reproduction and survival. The effects of antiparasitic treatment during incubation on body mass and return rate in female common eiders Somateria mollissima were examined in a two year study (1998 and 1999). There was no effect of treatment on nest success, but unsuccessful females had lower body mass. Treatment had no effect on incubation time, mass-loss during incubation or return rate among successful birds. However, treatment lead to higher return rate among unsuccessful birds (treated= 69%, n =13; controls =18%, n =11). This pattern remained significant also after including the birds that returned two years after the experiment. We suggest that the unsuccessful females are of lower quality and had higher costs from parasite infections than birds which completed incubation, and that the higher return rate for treated unsuccessful females may mean that costs of parasites are substantial, and that the potential fitness gain from investment in parasite defense and avoidance is large.

Journal ArticleDOI
TL;DR: It is concluded that although turning until 18 d benefited hatchability and chick quality, it depressed potential posthatch performance of the chick to 7 d of age.