Showing papers on "Incubation published in 2015"

Local variation in weather conditions influences incubation behavior and temperature in a passerine bird

Abstract: Incubation is an important component of avian parental care and slight changes in incubation temperature can affect offspring phenotype. Although many extrinsic and intrinsic factors may generate variation in incubation temperature, they remain underexplored under natural conditions. Using a robust data set encompassing 55 nests, 22 816 behavioral observations, and > 1 million paired ambient and egg temperatures, we describe the relationships among abiotic factors, female incubation behavior, incubation temperature, and incubation period for tree swallows Tachycineta bicolor. We report a large amount of individual variation in incubation behaviors and average incubation temperatures for our study population. The average on-bout incubation temperature was 34.1°C, with daily egg temperatures ranging from 18.0–39.2°C. Females modulated the number of times they left the nest and the amount of time they stayed off the nest according to interactions between precipitation and temperature patterns. Models generated from our observations predicted that the number of female off-bouts was the lowest under warm and dry conditions while more off-bouts were taken under cold and dry or warm and wet conditions. During cold and dry conditions, females stayed off their nest ∼4 times longer than under warm and dry conditions. However, this pattern was reversed under periods of rainfall; females tended to take shorter off-bouts when it was rainy and cold compared to longer off-bouts during warmer rain events. Furthermore, variation in female behavior was associated with differences in overall incubation temperature such that females that maintained greater incubation constancy produced higher incubation temperatures at a given ambient temperature than those that displayed lower incubation constancy. Our results provide perspective on the timing of breeding, as some of the advantages of breeding early may be countered by cooler, early season temperatures and precipitation that cause reproducing females to favor self-maintenance at a potential cost to optimal incubation temperatures for offspring development.

The energetic costs of incubation

Abstract: This chapter discusses several different aspects of the energy balance and physiological homeostasis of incubating birds, ranging from systematic, geographical and life history related variation in energy costs of incubation, to thermal considerations for birds on the nest, links between energy expenditure and fitness, and non-energetic costs of incubation. Our review of the literature shows that, across all bird species, this energy costs amounts to 3.4 times the basal metabolic rate (BMR). This is 15% lower than the cost of chick rearing (2.9 × BMR) for all birds, but is roughly equal to chick-rearing costs in those species in which only the female incubates. Energy costs are typically higher in challenging conditions, such as during incubation in harsh climates. This can impair fitness of parents and offspring, but little is understood about the physiological basis for such costs. We highlight and discuss possible mechanisms by which increased energy expenditure in incubating birds might hamper adult survival and, independently, carry over to also affect nestling phenotype and performance. We end by drawing attention to situations where the primary currency for incubation is not energy-based, which we exemplify by a discussion on the water economy of incubation in desert birds.

Inhibition of low-grade inflammation by anthocyanins from grape extract in an in vitro epithelial-endothelial co-culture model

Abstract: Background: Anthocyanins (ACNs) are the most prevalent flavonoids in berries and their health promoting effects on vascular functions are still discussed. The aim of the present study was to identify the anti-inflammatory effect of ACNs on activated human umbilical vein endothelial cells (HUVECs) after their transport across an epithelial monolayer. Study design: We established a transwell epithelial-endothelial co-culture system with Caco-2/HT29-B6 cells mimicking the intestinal layer and HUVECs as endothelial cells mimicking the vascular layer. Caco-2 were seeded alone (100%) or together with HT29-B6 cells (10 and 20%) on transwell inserts in order to simulate different metabolization sides of the gut. ACNs as well as malvidin-3-glucoside (M3G) were applied to the luminal compartment of the transwell-system. Transport and degradation rates were determined by high performance liquid chromatography with ultraviolet detection (HPLC-UV) or by ultra-PLC coupled to mass spectrometry (UPLC-MS). After 4 hours incubation time, co-cultured HUVECs were used immediately (short-term incubation) or after 20 hours (long-term incubation). Thereafter, HUVECs were stimulated for 3 hours with 1 ng mL−1 TNF-α to mimic a low-grade or 10 ng mL−1 to mimic a high-grade inflammation. Afterwards, (1.) leukocyte adhesion, (2.) expression of cell adhesion molecules (ICAM-1, VCAM-1 and E-selectin) and (3.) cytokine expression and secretion (IL-6 and IL-8) were determined using flow cytometry and real-time PCR. Results: Degradation and incubation studies revealed that ACNs were differently degraded depending on the ACN structure and the seeding densities. Incubation of ACNs and M3G to Caco-2 cells (100%) led to a fast decrease, which was not observed when HT29-B6 cells were co-cultured (10 and 20%). Concomitantly, anti-inflammatory effects were only observed using 100% Caco-2 cells, whereas mixtures of Caco-2 and HT29-B6 cells failed to induce an effect. ACN extract and M3G significantly attenuated TNF-α-stimulated low-grade leukocyte adhesion, expression of adhesion molecules E-selectin, VCAM-1 and ICAM-1 and cytokine expression and secretion (IL-8 and IL-6) as well as NF-κB mRNA expression. No effects were observed with high TNF-α (10 ng mL−1) or after short-term incubation (4 hours). Conclusions: ACNs in physiological concentrations reached the serosal compartment and reduced inflammation-related parameters, which were related to the initial steps during the pathogenesis of atherosclerosis.

Transient and permanent effects of suboptimal incubation temperatures on growth, metabolic rate, immune function and adrenocortical responses in zebra finches.

Abstract: In birds, incubation temperature can vary by several degrees Celsius among nests of a given species. Parents may alter incubation temperature to cope with environmental conditions and/or to manipulate embryonic development, and such changes in incubation behavior could have long-lasting effects on offspring phenotype. To investigate short- and long-term effects of suboptimal incubation temperatures on survival and physiological functions in zebra finches, eggs were incubated at 36.2, 37.4 or 38.4°C for the entire incubation period. The post-hatch environment was identical among the treatment groups. We found that hatching success was lowest in the 38.4°C group, while post-hatch survival was lowest in the 36.2°C group. Incubation temperature had sex-specific effects on offspring phenotype: incubation temperatures affected body mass ( M b ) but not physiological parameters of males and conversely, the physiological parameters but not M b of females. Specifically, males from the 38.4°C group weighed significantly less than males from the 36.2°C group from the nestling period to adulthood, whereas females from different incubation temperature groups did not differ in M b . In contrast, females incubated at 36.2°C had transient but significantly elevated basal metabolic rate and adrenocortical responses during the nestling and fledgling periods, whereas no treatment effect was observed in males. Innate immunity was not affected by incubation temperature in either sex. These results suggest that a 1°C deviation from what is considered an optimal incubation temperature can lower offspring performance and offspring survival.

The physiology of the avian embryo

Abstract: The freshly laid avian egg contains most of the materials needed for embryonic growth and development, but lacks the oxygen and heat needed for successful development. Microscopic pores in the eggshell allow O2 to diffuse into the egg from the environment and water vapor and CO2 produced by the embryo to diffuse out. The adult bird has a key role in incubation, providing not only the heat necessary for embryonic development but also controlling the microclimate of the egg. In the poultry industry and for research purposes, the adult bird can be conveniently replaced by an incubator. The majority of research on avian incubation is undertaken using artificially incubated chicken (Gallus gallus domesticus) eggs. Thus, in this chapter, the chicken embryo is used to elucidate the development of physiological function during avian incubation, supplemented by additional species when data are available. Developmental physiology of the gas exchange, acid–base, cardiovascular, osmoregulatory and thermoregulatory systems are examined. The optimal conditions for artificial incubation are outlined and embryonic responses to incubation extremes are described.

LC-MS-based metabolomics study of marine bacterial secondary metabolite and antibiotic production in Salinispora arenicola.

Abstract: An LC-MS-based metabolomics approach was used to characterise the variation in secondary metabolite production due to changes in the salt content of the growth media as well as across different growth periods (incubation times). We used metabolomics as a tool to investigate the production of rifamycins (antibiotics) and other secondary metabolites in the obligate marine actinobacterial species Salinispora arenicola, isolated from Great Barrier Reef (GBR) sponges, at two defined salt concentrations and over three different incubation periods. The results indicated that a 14 day incubation period is optimal for the maximum production of rifamycin B, whereas rifamycin S and W achieve their maximum concentration at 29 days. A "chemical profile" link between the days of incubation and the salt concentration of the growth medium was shown to exist and reliably represents a critical point for selection of growth medium and harvest time.

Critical windows in embryonic development: Shifting incubation temperatures alter heart rate and oxygen consumption of Lake Whitefish (Coregonus clupeaformis) embryos and hatchlings

Abstract: Critical windows are periods of developmental susceptibility when the phenotype of an embryonic, juvenile or adult animal may be vulnerable to environmental fluctuations. Temperature has pervasive effects on poikilotherm physiology, and embryos are especially vulnerable to temperature shifts. To identify critical windows, we incubated whitefish embryos at control temperatures of 2 °C, 5 °C, or 8 °C, and shifted treatments among temperatures at the end of gastrulation or organogenesis. Heart rate (f H ) and oxygen consumption ( V ˙ O 2 ) were measured across embryonic development, and V ˙ O 2 was measured in 1-day old hatchlings. Thermal shifts, up or down, from initial incubation temperatures caused persistent changes in f H and V ˙ O 2 compared to control embryos measured at the same temperature (2 °C, 5 °C, or 8 °C). Most prominently, when embryos were measured at organogenesis, shifting incubation temperature after gastrulation significantly lowered V ˙ O 2 or f H . Incubation at 2 °C or 5 °C through gastrulation significantly lowered V ˙ O 2 (42% decrease) and f H (20% decrease) at 8 °C, incubation at 2 °C significantly lowered V ˙ O 2 (40% decrease) and f H (30% decrease) at 5 °C, and incubation at 5 °C and 8 °C significantly lowered V ˙ O 2 at 2 °C (27% decrease). Through the latter half of development, V ˙ O 2 and f H in embryos were not different from control values for thermally shifted treatments. However, in hatchlings measured at 2 °C, V ˙ O 2 was higher in groups incubated at 5 °C or 8 °C through organogenesis, compared to 2 °C controls (43 or 65% increase, respectively). Collectively, these data suggest that embryonic development through organogenesis represents a critical window of embryonic and hatchling phenotypic plasticity. This study presents an experimental design that identified thermally sensitive periods for fish embryos.

Estimating the Distribution of the Incubation Periods of Human Avian Influenza A(H7N9) Virus Infections

Abstract: A novel avian influenza virus, influenza A(H7N9), emerged in China in early 2013 and caused severe disease in humans, with infections occurring most frequently after recent exposure to live poultry. The distribution of A(H7N9) incubation periods is of interest to epidemiologists and public health officials, but estimation of the distribution is complicated by interval censoring of exposures. Imputation of the midpoint of intervals was used in some early studies, resulting in estimated mean incubation times of approximately 5 days. In this study, we estimated the incubation period distribution of human influenza A(H7N9) infections using exposure data available for 229 patients with laboratory-confirmed A(H7N9) infection from mainland China. A nonparametric model (Turnbull) and several parametric models accounting for the interval censoring in some exposures were fitted to the data. For the best-fitting parametric model (Weibull), the mean incubation period was 3.4 days (95% confidence interval: 3.0, 3.7) and the variance was 2.9 days; results were very similar for the nonparametric Turnbull estimate. Under the Weibull model, the 95th percentile of the incubation period distribution was 6.5 days (95% confidence interval: 5.9, 7.1). The midpoint approximation for interval-censored exposures led to overestimation of the mean incubation period. Public health observation of potentially exposed persons for 7 days after exposure would be appropriate.

Physiological pace of life: the link between constitutive immunity, developmental period, and metabolic rate in European birds.

Abstract: Constitutive innate immunity is the first lined of defence against infections, but the causes determining its variability among species are poorly understood. The pace of life hypothesis predicts that species with a fast speed of life, characterized by high energy turnover and short developmental time, invest relatively little in defence in favour of growth and early reproduction, whereas ‘slow-living’ species are predicted to invest more resources into costly defence. We conducted phylogenetic comparative analysis on 105 European bird species and determined that the number of leukocytes, and the levels of natural antibodies (NAbs) and complement, measured on adult birds, increased or tended to positively correlate with the length of incubation period. However, we found that the length of incubation and fledging periods have opposite effects on immune defence (i.e. immune parameters show a negative association with the length of fledging period). Our results suggest that the contrasting effects of the incubation and fledging periods are related to the timing of the development of immune cells and of NAbs and complement, which largely mature during the embryonic phase of development. In support of this hypothesis, we found that species with a long relative incubation period [i.e. whose total pre-fledging developmental time (incubation plus fledging) consists largely of the incubation period] invested more in constitutive innate immunity. Finally, in support of the pace of life hypothesis, for a subsample of 63 species, we found that the basal metabolic rate significantly or tended to negatively correlate with immune measures.

Biparental incubation-scheduling: no experimental evidence for major energetic constraints

Abstract: Incubation is energetically demanding, but it is debated whether these demands constrain incubation-scheduling (i.e., the length, constancy, and timing of incubation bouts) in cases where both parents incubate. Using 2 methods, we experimentally reduced the energetic demands of incubation in the semipalmated sandpiper, a biparental shorebird breeding in the harsh conditions of the high Arctic. First, we decreased the demands of incubation for 1 parent only by exchanging 1 of the 4 eggs for an artificial egg that heated up when the focal bird incubated. Second, we reanalyzed the data from the only published experimental study that has explicitly tested energetic constraints on incubation-scheduling in a biparentally incubating species (Cresswell et al. 2003). In this experiment, the energetic demands of incubation were decreased for both parents by insulating the nest cup. We expected that the treated birds, in both experiments, would change the length of their incubation bouts, if biparental incubation-scheduling is energetically constrained. However, we found no evidence that heating or insulation of the nest affected the length of incubation bouts: the combined effect of both experiments was an increase in bout length of 3.6min (95% CI: -33 to 40), which is equivalent to a 0.5% increase in the length of the average incubation bout. These results demonstrate that the observed biparental incubation-scheduling in semipalmated sandpipers is not primarily driven by energetic constraints and therefore by the state of the incubating bird, implying that we still do not understand the factors driving biparental incubation-scheduling.

Preparation of core-shell hybrid materials by producing a protein corona around magnetic nanoparticles

Abstract: Nanoparticles experience increasing interest for a variety of medical and pharmaceutical applications. When exposing nanomaterials, e.g., magnetic iron oxide nanoparticles (MNP), to human blood, a protein corona consisting of various components is formed immediately. The composition of the corona as well as its amount bound to the particle surface is dependent on different factors, e.g., particle size and surface charge. The actual composition of the formed protein corona might be of major importance for cellular uptake of magnetic nanoparticles. The aim of the present study was to analyze the formation of the protein corona during in vitro serum incubation in dependency of incubation time and temperature. For this, MNP with different shells were incubated in fetal calf serum (FCS, serving as protein source) within a water bath for a defined time and at a defined temperature. Before and after incubation the particles were characterized by a variety of methods. It was found that immediately (seconds) after contact of MNP and FCS, a protein corona is formed on the surface of MNP. This formation led to an increase of particle size and a slight agglomeration of the particles, which was relatively constant during the first minutes of incubation. A longer incubation (from hours to days) resulted in a stronger agglomeration of the FCS incubated MNP. Quantitative analysis (gel electrophoresis) of serum-incubated particles revealed a relatively constant amount of bound proteins during the first minutes of serum incubation. After a longer incubation (>20 min), a considerably higher amount of surface proteins was determined for incubation temperatures below 40 °C. For incubation temperatures above 50 °C, the influence of time was less significant which might be attributed to denaturation of proteins during incubation. Overall, analysis of the molecular weight distribution of proteins found in the corona revealed a clear influence of incubation time and temperature on corona composition.

High Incubation Temperature and Threonine Dietary Level Improve Ileum Response Against Post-Hatch Salmonella Enteritidis Inoculation in Broiler Chicks

Abstract: This study assessed the effect of both embryonic thermal manipulation and dietary threonine level on the response of broilers inoculated with Salmonella Enteritidis, considering bacterial counts in the cecal contents, intestinal morphology, mucin and heat shock protein 70 gene expression, body weight and weight gain. Thermal manipulation was used from 11 days of incubation until hatch, defining three treatments: standard (37.7°C), continuous high temperature (38.7°C) and continuous low temperature (36.7°C). After hatch, chicks were distributed according to a 3x2+1 factorial arrangement (three temperatures and two threonine levels and one sham-inoculated control). At two days of age, all chicks were inoculated with Salmonella Enteritidis, except for the sham-inoculated control group. There was no interaction between the factors on any analyses. High temperature during incubation was able to reduce colonization by Salmonella Enteritidis in the first days, reducing both Salmonella counts and the number of positive birds. It also increased mucin expression and decreased Hsp70 expression compared with other inoculated groups. High temperature during incubation and high threonine level act independently to reduce the negative effects associated to Salmonella Enteritidis infection on intestinal morphology and performance, with results similar to sham-inoculated birds. The findings open new perspectives for practical strategies towards the pre-harvest Salmonella control in the poultry industry.

Shifts in bacterial communities of eggshells and antimicrobial activities in eggs during incubation in a ground-nesting passerine

Abstract: Microbial invasion of egg contents is a cause of embryonic death. To counter infection risks, the embryo is protected physically by the eggshell and chemically by antimicrobial proteins. If microbial pressure drives embryo mortality, then females may have evolved, through natural selection, to adapt their immune investment into eggs. Although frequently hypothesized, this match between immune allocation and microorganisms has not been explored yet. To examine if correlations between microbes on eggs and immunity in eggs exist, we collected eggs from red-capped larks (Calandrella cinerea) and simultaneously examined their bacterial communities and antimicrobial components—pH, lysozyme and ovotransferrin—during natural incubation. Using molecular techniques, we find that bacterial communities are highly dynamic: bacterial abundance increases from the onset to late incubation, Shannon’s α-diversity index increases during early incubation stages, and β-diversity analysis shows that communities from 1 day-old clutches are phylogenetically more similar to each other than the older ones. Regarding the antimicrobials, we notice a decrease of pH and lysozyme concentration, while ovotransferrin concentration increases during incubation. Interestingly, we show that two eggs of the same clutch share equivalent immune protection, independent of clutch age. Lastly, our results provide limited evidence of significant correlation between antimicrobial compounds and bacterial communities. Our study examined simultaneously, for the first time in a wild bird, the dynamics of bacterial communities present on eggshells and of albumen-associated antimicrobial components during incubation and investigated their relationship. However, the link between microorganisms and immunity of eggs remains to be elucidated further. Identifying invading microbes and their roles in embryo mortality, as well as understanding the role of the eggshell microbiome, might be key to better understand avian strategies of immune maternal investment.

Tropical flatback turtle (Natator depressus) embryos are resilient to the heat of climate change

Abstract: Climate change is threatening reproduction of many ectotherms by increasing nest temperatures, potentially making it more difficult for females to locate nest sites that provide suitable incubation regimes during embryonic development. Elevated nest temperatures could increase the incidence of embryonic mortality and/or maladaptive phenotypes. We investigated whether elevated nest temperatures reduce hatching success in tropical flatback turtles ( Natator depressus ) nesting in the Gulf of Carpentaria, Australia. Egg incubation treatments began at 29.5°C and progressively increased in temperature throughout incubation, up to maxima of 31, 32, 33, 34, and 35°C. Elevated nest temperatures did not reduce hatching success or hatchling body size relative to control temperatures (29.5°C), but did speed embryonic development. A combination of sudden exposure to high temperatures during the first two weeks of incubation (>36°C for 48 hours) and prolonged warming throughout incubation (from 29.5-35°C) did not reduce hatching success. We also recorded an unusually high pivotal sex-determining temperature in this flatback turtle population relative to other sea turtle populations; an equal ratio of male and female hatchlings is produced at ∼30.4°C. This adaptation may allow some flatback turtle populations to continue producing large numbers of hatchlings of both sexes under the most extreme climate change scenarios. Some tropical populations of nesting flatbacks may possess important adaptations to high temperature incubation environments which are not found in more southerly temperate populations.

Extrinsic Incubation Rate is Not Accelerated in Recent California Strains of West Nile Virus in Culex tarsalis (Diptera: Culicidae)

Abstract: The efficiency of West Nile virus (WNV) transmission by competent mosquito vectors is driven by temperature and defined, in part, by the extrinsic incubation period, which is the time from a mosquito's consumption of an infected bloodmeal until it becomes capable of transmitting the virus to the next vertebrate host. The extrinsic incubation period can be altered by a variety of factors involved in vector-pathogen interactions, and in North America, the WN02 strain of WNV emerged and displaced the founding NY99 strain reportedly because the duration of the extrinsic incubation period in Culex mosquitoes was shortened by a single positively selected mutation. However, recent work has suggested that this change is not universal and may depend on vector species or strain. In the current study, we estimated the extrinsic incubation periods at 22 and 30°C in Culex tarsalis Coquillett. We found that the time to transmission of the original North American WNV strain, NY99, was not different from two more recent California isolates of the WN02 genotype: one of the earliest California isolates from the southeastern deserts, and a more recent 2011 isolate from a hyperendemic region in the Central Valley. We conclude with a model-based assessment of the epidemiological effects of temperature on the duration of mosquitoes' infectious life, which estimated that most mosquitoes have an infectious life of only a few days, but its duration expands markedly at warmer temperatures.

Factors Driving Variation in Biparental Incubation Behaviour in the Reed Warbler Acrocephalus scirpaceus

Abstract: Biparental incubation is a common pattern of parental care in birds. Within species with biparental incubation, the contribution of each sex can vary widely. Many studies have addressed the factors that influence variation in female incubation behaviour, but the underlying causes of within-species variation in male incubation behaviour remain poorly understood. In this paper we analyse incubation behaviour in the Reed Warbler, a small, predominantly socially monogamous passerine nesting in reed beds. We examined the impact of time of day, weather conditions (ambient temperature, wind speed, rainfall) and progress of the breeding season on male and female incubation behaviour in 81 pairs of Reed Warbler breeding in the Barycz Valley (SW Poland). We found that females had on average higher nest attentiveness (total time spent incubating per hour) than their partners (47% vs. 29%) but mean incubation bout length (a single, uninterrupted stay at the nest) did not differ significantly between the sexes (9 min vs. 7 min). The two parents responded differently to changing environmental parameters. Female nest attentiveness was unaffected by date, time of the day, advancement of incubation and weather conditions, while males spent more time on the nest at higher wind speeds and lower temperatures. In contrast, male incubation bout length was not affected by these factors, whereas female bout length increased throughout the breeding season and was longer at lower temperatures. Incubation recesses (periods where both parents were off the nest) were longer during favourable weather conditions (at high temperatures and low wind), probably because cooling of the eggs takes much longer under such conditions and parents can spend more time foraging. A comparison of our results with those from other populations revealed important betweenpopulation and sex-specific differences in nest attentiveness expressed as the percentage of male/female time spent on the nest. We suggest that betweenpopulation variation may result from differences in habitat quality and/or food resources affecting the necessity of male contribution to parental care, variation in breeding synchrony and densities influencing male engagement in extra-pair copulations, differences in predation levels, or methodological differences.

Effects of nest predation risk on female incubation behavior and offspring growth in great tits

Abstract: Predation risk is a key driver for the evolution of reproductive strategies and life history traits. In birds, incubation behavior represents one form of parental care where trade-offs between time spent in incubation activities and self-maintenance activities are likely to change in response to predator pressure. This can have strong effects on embryonic development, but is still poorly understood. We investigated the effects of the presence of a nest predator on great tit (Parus major) incubation behavior and the subsequent effects of incubation on nestling morphological traits. We manipulated perceived predation risk using models of short-tailed weasels (Mustela erminea) in combination with great tit alarm calls specific to this predator. Directly after hatching, we swapped whole broods from treated nests with broods from untreated nests to disentangle treatment effects acting during the incubation period from potential carry-over effects on parental care acting on nestlings after hatching. In increased predation risk environments, the number of incubation sessions and recesses, but not their duration, was increased compared to the control group, and the nocturnal incubation session was longer when females were exposed to a predator. Eggs incubated by females under increased predation risk lost more mass over the incubation period compared to the control group. Also, male nestlings hatched from nests exposed to predators were lighter at hatching but were equivalent in weight to their control counterparts at fledging. This suggests that nest predation risk can influence some aspects of incubation rhythm and embryonic development, but has no long-term effects on nestling final body size.

Effects of chronic hypoxia on cardiac function measured by pressure-volume catheter in fetal chickens

Abstract: Hypoxia is a common component of many developmental insults and has been studied in early-stage chicken development. However, its impact on cardiac function and arterial-ventricular coupling in late-stage chickens is relatively unknown. To test the hypothesis that hypoxic incubation would reduce baseline cardiac function but protect the heart during acute hypoxia in late-stage chickens, white Leghorn eggs were incubated at 21% O2 or 15% O2. At 90% of incubation (19 days), hypoxic incubation caused growth restriction (-20%) and increased the LV-to-body ratio (+41%). Left ventricular (LV) pressure-volume loops were measured in anesthetized chickens in normoxia and acute hypoxia (10% O2). Hypoxic incubation lowered the maximal rate of pressure generation (ΔP/ΔtMax; -22%) and output (-57%), whereas increasing end-systolic elastance (ELV; +31%) and arterial elastance (EA; +122%) at similar heart rates to normoxic incubation. Both hypoxic incubation and acute hypoxia lengthened the half-time of relaxation (τ; +24%). Acute hypoxia reduced heart rate (-8%) and increased end-diastolic pressure (+35%). Hearts were collected for mRNA analysis. Hypoxic incubation was marked by decreased mRNA expression of sarco(endo)plasmic reticulum Ca(2+)-ATPase 2, Na(+)/Ca(2+) exchanger 1, phospholamban, and ryanodine receptor. In summary, hypoxic incubation reduces LV function in the late-stage chicken by slowing pressure generation and relaxation, which may be driven by altered intracellular excitation-contraction coupling. Cardiac efficiency is greatly reduced after hypoxic incubation. In both incubation groups acute hypoxia reduced diastolic function.

Effects of Ascorbic Acid Injection in Incubated Eggs Submitted to Heat Stress on Incubation Parameters and Chick Quality

Abstract: Dose-dependent positive effects on hatchability and hatchling weight have been attributed to ascorbic acid (AA) when eggs were submitted or not to intermittent heat stress during incubation. Fertile breeder (Cobb(r)) eggs were used to determine if the pre-incubation injection of AA in ovo affects the incubation and hatchling quality of egg incubated under thermoneutral or intermittent heat stress conditions. Eggs were not injected or injected with 0, 2,4, or 6% AA/100µL water and incubated at continuous thermoneutral (37.5oC) or hot (39.0oC) temperature. Eggshell temperature (EST) increased in the second half of the incubation period in all experimental groups. The EST of non-injected eggs and of those injected with water was higher when incubated at 39°C than at 37.5°C, but EST was not different among eggs injected with AA. Egg mass loss and eggshell conductance were higher in the eggs incubated at 39°C than at 37.5°C.Hatchability was lower in the eggs injected with AA. Liver and yolk sac weights were higher, whereas heart and liver weights were lower in hatchlings from eggs incubated at 39°C; however, hatchling weight was not affected by incubation temperature. The results showed that AA doses affected egg conductive heat loss and hatchability, and that they did not minimize the effects of high incubation temperature on liver and heart development.

Effects of the novel pyrimidynyloxybenzoic herbicide ZJ0273 on enzyme activities, microorganisms and its degradation in Chinese soils

Abstract: Enzyme activity and microbial population in soils have important roles in keeping soil fertility. ZJ0273 is a novel pyrimidynyloxybenzoic-based herbicide, which was recently developed in China. The effect of ZJ0273 on soil enzyme activity and microbial population in two different soils was investigated in this study for the first time. The protease activity was significantly inhibited by ZJ0273 and this inhibiting effect gradually weakened after 60-day incubation. The results also showed that ZJ0273 had different stimulating effects on the activities of dehydrogenase, urease, and catalase. Dehydrogenase was consistently stimulated by all the applied concentrations of ZJ0273. The stimulating effect on urease weakened after 60-day incubation. Catalase activity was subject to variations during the period of the experiments. The results of microbial population showed that the number of bacteria and actinomycetes increased in ZJ0273-treated soil compared with the control after 20 days of incubation, while fungal number decreased after only 10 days of incubation in soils. DT50 (half-life value) and k (degradation rate constant) of ZJ0273 in S1 (marine-fluvigenic yellow loamy soil) and S2 (Huangshi soil) were found 69.31 and 49.50 days and 0.010 and 0.014 day−1, respectively.

Advances in techniques to study incubation

Abstract: Birds have long fascinated people (Birkhead 2008) and we have remained closely associated with them for centuries. They provide us with food in the form of meat and eggs, they serve as companion animals, and they are at the focus of pastimes such as pigeon racing and hunting. Yet, without an understanding of reproductive processes, specifically incubation, it would be challenging to produce birds and maintain these important relationships. Knowledge of incubation in the wild is also vital for conservation (Kuehler and Witman 1988; Elliott et al. 2001; Chapter 16), and for management of wild birds that provide recreational opportunities and that are integral for ecosystem function (McGowan and Simons 2006; Coates and Delehanty 2008). However, despite being a critical component of the avian life cycle, incubation remains one of the most problematic avian life-history stages to study because this is when many species are at their most secretive (see Reynolds and Schoech 2012 and references therein). In spite of these challenges, since the late 1700s direct observations of nests, often conducted from hides, have permitted ornithologists to document and quantify incubation traits such as: session and recess lengths, i.e. time spent on and off the eggs during incubation, respectively; nest attentiveness, i.e. time for which eggs are incubated over a given period; incubation periods, i.e. total time between onset of incubation and hatching; incubation rhythms, i.e. patterns of successional sessions and recesses; and egg turning, for a wide range of species (e.g. Jenner 1788; Gross 1912; Skutch 1962). Direct observation allows the observer to detect subtle behaviours that may be missed through remote measurement or interpretation of data. As direct observation requires little or no expensive equipment, it is used extensively and especially in countries where modern technologies remain prohibitively expensive and thus inaccessible. However, direct observation has inherent disadvantages. Observers can disturb breeding adults and increase the likelihood of nest abandonment (Ellison and Cleary 1978; Henson and Grant 1991), decrease hatching success (Blackmer et al. 2004), disrupt reproductive behaviours (Verhulst et al. 2001; Holm and Laursen 2009), and increase predation risk (Bêty and Gauthier 2001; Verboven et al. 2001; but see Ibáñez-Álamo et al. 2012 and Reynolds and Schoech 2012). Since direct observation is time-consuming and labour-intensive, fatigue can result in observers collecting data of poor quality. Therefore, under most circumstances we must rely on methods other than, and sometimes in addition to, direct observation to generate data to test hypotheses about avian incubation. Over the last century numerous methods have been developed to investigate incubation that automate direct observations. In this chapter we provide an account of various methods used to monitor incubation remotely. In particular, we critically appraise the advantages and disadvantages of a relatively recently developed automated device that is widely used in studies of captive and free-living species, namely the iButton® (Maxim Integrated Products 2014). In so doing we provide advice (including decision rules) that can be employed to adopt the most appropriate method to study incubation within various ornithological contexts.

Antischistosomal and Cytotoxic Effects of the Essential Oil of Tetradenia riparia (Lamiaceae).

Abstract: This paper reports on the antischistosomal and cytotoxic effects of the essential oil obtained from Tetradenia riparia leaves (TR-EO). At concentrations of 50 and 100 µg/mL, TR-EO killed all the worms after 120 and 24 h of incubation, respectively. At a concentration equal to or higher than 50 µg/mL, this oil also separated the coupled pairs and decreased the adult worm motor activity after incubation periods higher than 72 h. In addition, at 120 h of incubation, TR-EO slightly decreased the number of eggs produced by Schistosoma mansoni adult worms and significantly reduced the percentage of developed eggs, in a dose-dependent manner. XTT-colorimetric assays showed that the tested TR-EO concentrations were not considerably cytotoxic to V79 cells (IC50 = 253.5 µg/mL). The effects of TR-EO on egg development were noteworthy; therefore, this essential oil deserves further investigation to identify the chemical constituents that elicit activity against S. mansoni.

Dissolution and aggregation of Cu nanoparticles in culture media: effects of incubation temperature and particles size

Abstract: Here, the effects of incubation temperature and particle size on the dissolution and aggregation behavior of copper nanoparticles (CuNPs) in culture media were investigated over 96 h, equivalent to the time period for acute cell toxicity tests. Three CuNPs with the nominal sizes of 25, 50, and 100 nm and one type of micro-sized particles (MPs, ~500 nm) were examined in culture media used for human and fish hepatoma cell lines acute tests. A large decrease in sizes of CuNPs in the culture media was observed in the first 24 h incubation, and subsequently the sizes of CuNPs changed slightly over the following 72 h. Moreover, the decreasing rate in size was significantly dependent on the incubation temperature; the higher the incubation temperature, the larger the decreasing rate in size. In addition to that, we also found that the release of copper ions depended on the incubation temperature. Moreover, the dissolution rate of Cu particles increased very fast in the first 24 h, with a slight increase over the following 72 h.

Latitudinal differences in temperature effects on the embryonic development and hatchling phenotypes of the Asian yellow pond turtle, Mauremys mutica

Abstract: The effect of incubation temperature on embryonic development and offspring traits has been widely reported for many species. However, knowledge remains limited about how such effects vary across populations. Here, we investigated whether incubation temperature (26, 28, and 30 °C) differentially affects the embryonic development of Asian yellow pond turtle (Mauremys mutica) eggs originating from low-latitude (Guangzhou, 23°06′N) and high-latitude (Haining, 30°19′N) populations in China. At 26 °C, the duration of incubation was shorter in the high-latitude population than in the low-latitude population. However, this pattern was reversed at 30 °C. As the incubation temperature increased, hatching success increased in the low-latitude population but slightly decreased in the high-latitude population. Hatchlings incubated at 30 °C were larger and righted themselves more rapidly than those incubated at 26 °C in the low-latitude population. In contrast, hatchling traits were not influenced by incubation temperature in the high-latitude population. Overall, 30 °C was a suitable developmental temperature for embryos from the low-latitude population, whereas 26 and 28 °C were suitable for those from the high-latitude population. This interpopulation difference in suitable developmental temperatures is consistent with the difference in the thermal environment of the two localities. Therefore, similarly to posthatching individuals, reptile embryos from different populations might have evolved diverse physiological strategies to benefit from the thermal environment in which they develop. © 2014 The Linnean Society of London, Biological Journal of the Linnean Society, 2014, 114, 35–43.