Effect Of Incubation Temperature Research Articles

Incubation Temperature Affects Duckling Body Size and Food Consumption Despite No Effect on Associated Feeding Behaviors.

SynopsisDevelopmental conditions can have consequences for offspring fitness. For example, small changes (<1°C) in average avian incubation temperature have large effects on important post-hatch offspring phenotypes, including growth rate, thermoregulation, and behavior. Furthermore, average incubation temperatures differ among eggs within the same nest, to the extent (i.e., >1°C) that differences in offspring phenotypes within broods should result. A potential consequence of within-nest incubation temperature variation is inequality in behaviors that could cause differences in resource acquisition within broods. To investigate this, we incubated wood duck (Aix sponsa) eggs at one of two ecologically-relevant incubation temperatures (35°C or 36°C), formed mixed-incubation temperature broods after ducklings hatched, and conducted trials to measure duckling behaviors associated with acquisition of heat (one trial) or food (three trials). Contrary to our predictions, we found no effect of incubation temperature on duckling behaviors (e.g., time spent occupying heat source, frequency of feeding bouts). However, we found evidence that ducklings incubated at the higher temperature consumed more food during the 1-h feeding trials, and grew faster in body mass and structural size (culmen and tarsus) throughout the study, than those incubated at the lower temperature. Apparent food consumption during the trials was positively related to culmen length, suggesting that differences in food consumption may be driven by structural size. This could result in positive feedback, which would amplify size differences between offspring incubated at different temperatures. Thus, our study identifies incubation temperature as a mechanism by which fitness-related phenotypic differences can be generated and even amplified within avian broods.

Effect of Incubation Temperature, Light Intensity and Salinity on Growth, Lipid Content and Composition of Two Egyptian Race a of Botryococcus Braunii

Effects of the incubation temperature, light intensity and NaCl salinity on growth in addition to lipid content and composition of two isolates of Botryococcus braunii, (JN580448.1 and JN580451.1) were investigated. The light to dark period was 16h: 8h. Cultures were incubated for 7 weeks and harvested with GF/C filters for dry weight determination. Lipids were extracted by n-hexane and analyzed by GC/MS. Compared to control cultures, the temperature of 30oC induced significant (P ≤ 0.05) increase in biomass by 14.89% and 29.89% and lipids by 16.15% and 20.29% for isolates EG-Bb01 and EG-Bb04, respectively. The light intensity 48.6 μ mol photons m-2s-1 induced very high significant (P ≤ 0.001) increase in biomass (88.71% and 100.7%) and lipids (118.63% and 94.61%) of EG-Bb01 and EGBb04, respectively. Similarly, 17 mM NaCl salinity induced high significant (P ≤ 0.01) increase in biomass (23.82% and 17.71%) and lipids (32.92% and 24.51%) of EG-Bb01 and EG-Bb04, respectively. Considerable numbers of short C6-C15 chain compounds were detected in biomass of cultures grown under light intensity of 48.6 μ mol photons m-2s-1 and in cultures supplemented with 17mM NaCl. These results may indicate that the Egyptian isolates of Botryococcus are potential source of hydrocarbon biofuel.

Sex and Incubation Temperature Independently Affect Embryonic Development and Offspring Size in a Turtle with Temperature-Dependent Sex Determination

Developmental environments can have lasting effects on an individual's phenotype. In many reptiles, for example, egg incubation temperature permanently determines offspring sex (temperature-dependent sex determination, TSD) and also influences a suite of morphological, physiological, and behavioral traits. Thus, the contributions of sex and incubation temperature to phenotypic variation are difficult to identify because these factors are confounded under TSD. We used chemical manipulations to experimentally decouple gonadal sex and incubation temperature in a turtle with TSD (Chrysemys picta) to examine their relative and interactive effects on variation in incubation duration and offspring size. We show that warm incubation temperature accelerates development as expected and that exogenous estradiol treatment to eggs further shortens incubation duration across all incubation temperatures. Moreover, estradiol unexpectedly induced male development, resulting in male offspring hatching sooner than female offspring. Variation in offspring size was also influenced by incubation temperature and gonadal sex, but interactions between these two variables were relatively small or nonsignificant. The fitness consequences of these effects are unknown, but we provide preliminary results from our attempts at examining the long-term and sex-specific effects of incubation temperature. Manipulative experimental approaches, combined with longer-term experiments that track individuals through reproduction, will provide novel insights into the adaptive significance of developmental plasticity in long-lived organisms.

Best swimmers hatch from intermediate temperatures: Effect of incubation temperature on swimming performance of olive ridley sea turtle hatchlings

Marine turtle hatchling survival depends not only on suitable incubation temperatures allowing for viable embryo development but also adequate locomotor capacity to avoid predation while crawling from the beach to the sea and when swimming into the open ocean. To investigate the effects of temperature on swimming performance of olive ridley (Lepidochelys olivacea) hatchlings, we incubated eggs at different constant temperatures (24–34 °C) using a split-clutch approach. Swimming performance of hatchlings was tested and video-recorded for 24 h in static water under a day/night cycle (experiment 1) and for 30 min in continuously flowing water in the dark (experiment 2). Data from experiment 1 were evaluated visually to estimate the time of swimming activity. For experiment 2, we used software to calculate movement parameters from which hatchling performance was estimated. In both experiments, intermediate incubation temperatures (28–30 °C) were optimal not only for hatchling success and morphological dimensions but also for swimming performance, with 30 °C being the most favorable. Performance from hatchlings diminished with higher and lower temperatures, especially at the coldest range (26–27 °C). Phenotypic plasticity was observed from low and high incubation temperatures, with higher variation in performance among hatchlings from eggs incubated at 26–27 °C and 32–33 °C than for those incubated at 28–30 °C. Our results consistently showed that incubation temperature exerts the greatest influence on swimming performance and that maternal origin (clutch) has a significant effect on individual hatchling morphology. Given that the olive ridley year-round breeding leads to variable nest incubation temperatures in hot summers and cooler winter months, our results highlight the need for careful temperature management to produce hatchlings with optimal swimming capacities and, hence, highest survival probabilities.

Limited Support for Thyroid Hormone or Corticosterone Related Gene Expression as a Proximate Mechanism of Incubation Temperature-Dependent Phenotypes in Birds.

The conditions that animals experience during early development can have profound consequences for health and fitness. In birds, one of the most important aspects of development is egg incubation temperature. A small decrease in average temperature leads to various impacts on offspring phenotype, such as smaller body sizes, slower growth rates, and less efficient metabolic activity. Little is known, however, about the proximate mechanisms underlying these incubation temperature-induced phenotypic changes. Two important hormones which could play a proximate role are thyroid hormone and corticosterone, which mobilize stored energy reserves and coordinate the normal growth of tissues, particularly in the brain. Previous research shows that circulating blood concentrations of both hormones are influenced by incubation temperature, but the mechanism by which incubation temperature may lead to these changes is unknown. We hypothesized that incubation temperature induces changes in thyroid hormone and corticosterone regulation, leading to changes in expression of hormone-sensitive genes in the brain. To test this, we incubated wood duck (Aix sponsa) eggs at three different temperatures within the natural range (35.0, 35.8, and 37.0°C). We measured mRNA expression of thyroid hormone-related neuroendocrine endpoints (deiodinase 2/3, thyroid hormone receptor α/β, neural regeneration related protein, and Krueppel-like factor 9) in newly hatched ducklings and corticosterone-related neuroendocrine endpoints (mineralocorticoid receptor, glucocorticoid receptor, cholecystokinin, and brain-derived neurotrophic factor) in 15 day-old ducklings using qPCR on brain tissue from the hippocampus and hypothalamus. Contrary to our predictions, we found that mRNA expression of thyroid hormone-related endpoints in both brain areas were largely unaffected by incubation temperature, although there was a trend for an inverse relationship between mRNA expression and incubation temperature for several genes in the hypothalamus. We also found that mineralocorticoid receptor mRNA expression in the hypothalamus was lower in ducklings incubated at the low relative to the high temperatures. This study is the first to evaluate the effects of incubation temperature on mRNA expression of neuroendocrine endpoints in the developing avian brain and suggests that these particular endpoints may be largely resistant to changes in incubation temperature. Thus, further research into the proximate mechanisms for incubation temperature-induced developmental plasticity is needed.

Temperature Affects Hatching Success of Cocoons in the Invasive Asian Earthworm Amynthas agrestis from the Southern Appalachians

Invasive Asian earthworms are increasingly common in the eastern USA where they are a major cause of terrestrial ecosystem disturbance. Among these, Amynthas agrestis (Crazy Worm, Alabama Jumper, and other common names) has been shown to alter above- and belowground food webs. Life-history traits of these earthworms are largely unknown, particularly in their invaded range. Here, we sought to answer questions about temperature effects on hatching success for cocoons of this species, using specimens collected from the southern Appalachian Mountains. We conducted 2 experiments investigating the effects of incubation temperature and the effect of varying the duration of cold temperature on hatching success. Of the temperatures tested, we found that cocoons hatched with greatest success at 10 °C, but our tests indicate a long duration at that temperature may be needed to result in an increase in hatching success. These results indicate that temperature and the duration of temperature exposure affect hatching success in this species. While our results contribute to the growing body of knowledge about the life-history traits of invasive Asian earthworms in the eastern US, more research is needed to provide a finer-resolution understanding of the optimum level and duration of temperatures for hatching success of A. agrestis.

Effect of incubation temperature on sex-dependent embryo mortality and morphological traits in Mallard.

Although birds have genetically determined sex, the sex ratio has been reported to deviate from parity in several studies. Temperature-dependent sex determination, which is common in reptiles, is absent in birds. However, females are able to adjust their investment into eggs according to the sex of the embryo, which may cause sex-specific embryonic mortality. Incubation temperature may also cause sex-biased embryonic mortality, and it may differentially affect the phenotype of male and female hatchlings. We aimed to investigate differences between male and female Mallard embryos regarding their egg size, mortality during incubation and hatchling phenotype in relation to incubation temperature. Mallard eggs were incubated under six constant incubation temperatures (ranging from 35.0 to 38.0 °C). Hatchlings were weighed, and their morphological traits were measured. We determined the sex of hatchlings and unhatched embryos by genetic analysis and found higher male embryonic mortality at 35.5 °C (44 males vs. 28 females) and a higher proportion of female hatchlings at 38 °C (24 males vs. 38 females); however, these results were not statistically significant. Our results suggest that Mallard females do not differentiate quantitatively between sexes during egg production. Male hatchlings were significantly larger but not heavier than females. The size difference between sexes was most pronounced at temperatures around 36 °C, which is the mean temperature of naturally incubated Mallard eggs.

Exposure of Avian Embryos to Cycling Incubation Temperatures Reduces Adult Bactericidal Ability.

In birds, the temperature at which eggs are incubated shapes many aspects of hatchling phenotype, but long-term effects are less studied. We studied the effect of incubation temperature and pattern on the subsequent development of innate immune function in Japanese quail (Coturnix japonica). We incubated quail eggs in one of three replicated treatments: control (37.5°C), low (36.0°C), and cyclical incubation. The cyclical treatment had the same average temperature as the low-temperature treatment (36.0°C) and an upper temperature that was the same as the control. When individuals were 5, 20, and 55 d of age (i.e., adults), we measured the ability of blood plasma to kill Escherichia coli. Throughout development there was a nonsignificant trend for immune function to be lower in the cycling treatment. In adulthood, however, individuals incubated at cycling temperatures had significantly lower immune function than control birds but did not differ from individuals incubated at constant low temperatures. Males and females responded similarly to the incubation treatment, but females developed a greater plasma bactericidal ability than males. We conclude that variation in innate immune function of adult birds is shaped by temperature fluctuations experienced during incubation.

Experimental design and syntrophic microbial pathways for biofuel production from sugarcane bagasse under thermophilic condition

The molecular mechanisms behind the bioconversion of sugarcane bagasse into biofuel by promising metabolic pathways were studied, suggesting that proteolytic, cellulolytic and methanogenic microorganisms such as Coprothermobacter, Clostridium, and Methanothermobacter, respectively, took an important syntrophic role in lignocellulosic-derived fuel production. The mixed acid fermentation was the main route to the acetic, formic, butyric, and propionic acid production by acid-forming bacteria. Some aspects of biotechnological application of such metabolic pathways were evaluated from a central composite design, in which the effect of incubation temperature (from 45.8 to 74.2 °C) and yeast extract concentration (from 0.58 to 3.42 g/L) on hydrogen production were assessed. The interaction between these factors significantly affected the hydrogen production, which reached the highest value (17.3 mmol/L) using 3.42 g/L of yeast extract at 60 °C, and favored a plastic and physiological diverse microbial community related to bioconversion of SCB.

Effects of Fermentative Factors on Biochemical, Microbiological and Sensory Characteristics of Probiotic Iranian Fermented Milk (Doogh)

Background: Doogh is a traditional Iranian fermented milk drink that is currently a very popular product in Iran. In the present study, the combined effects of incubation temperature, type of starter culture, and final pH of fermentation on the viability of two probiotic strains (Lactobacillus acidophilus La-5 (A) and Bifidobacterium lactis Bb-12 (B)) and biochemical and sensory characteristics of probiotic Doogh were investigated. &lt;/P&gt;&lt;P&gt; Method: Different treatments were prepared with yoghurt starter culture containing probiotics, using reconstituted skimmed milk with 6% of solid nonfat. They were incubated at 38°C or 44°C until pH 4.0 or pH 4.5 and were kept for 21 days at 4&amp;#176;C or 8&amp;#176;C storage temperature. The biochemical properties of treatments were evaluated during fermentation and refrigerated storage. The viable count and sensory attributes of treatments were studied at the end of fermentation and at the end of storage. &lt;/P&gt;&lt;P&gt; Results: Results showed that the greatest mean pH drop rate, mean acidity increase rate and mean redox potential increase rate and the shortest incubation time were observed in treatments incubated at 44&amp;#176;C with final pH of 4.5. The highest survival of both probiotic strains during storage was related to treatments with fermentation temperature of 38&amp;#176;C and final pH of 4.5. Treatments ABY1-38&amp;#176;C-4.0 had the highest sensorial total acceptance at the end of refrigerated storage. &lt;/P&gt;&lt;P&gt; Conclusion: It would be concluded that the best treatment was ABY3-38&amp;#176;C-4 stored at 8°C in regards of probiotics’ viability and sensory characteristics of Doogh. Thus, controlling the temperature of refrigerated storage is the most importance factor during storage and distribution.

Influence of Incubation Temperature on 9,10-Anthraquinone-2-Sulfonate (AQS)-Mediated Extracellular Electron Transfer.

The electron shuttling process has been recognized as an important microbial respiration process. Because the incubation temperature can influence both the reactivity of electron mediators and cell growth, it may also affect the electron-shuttle-mediated extracellular electron transfer (EET) process. Here, the effect of incubation temperature (22–38°C) was investigated in a bioelectrochemical system (BES) using Shewanella oneidensis MR-1 and 50 μM of 9,10-anthraquinone-2-sulfonate (AQS). We found that current generation increased as the temperature was increased from 22 to 34°C and then decreased sharply at 38°C. The biofilm biomass, as indicated by the total protein extracted from the electrode, increased as the temperature increased from 22 to 34°C and then decreased at 38°C, mirroring the current generation results. These results were further confirmed by increasing the temperature slowly, step-by-step, in a single BES with a constant biofilm biomass, suggesting that the EET rates could be substantially influenced by temperature, even with the same biofilm. The effects of temperature on the AQS bioreduction rate, c-type cytochrome (c-Cyts)-bound-cofactor-mediated EET, the AQS mid-point potential, and the AQS diffusion coefficient were studied. From these results, we were able to conclude that temperature influenced the EET rates by changing the c-Cyts-bound-cofactor-mediated EET process and the AQS bioreduction rate, and that the change in biofilm formation was a dominant factor influencing the overall EET rates. These findings should contribute to the fundamental understanding of EET processes. Moreover, optimization of the operating parameters for current generation will be helpful for the practical application of bioelectrochemical techniques.

Evaluation of Factors Affecting Antimicrobial Activity of Bacteriocin from Lactobacillus plantarum Microencapsulated in Alginate-Gelatin Capsules and Its Application on Pork Meat as a Bio-Preservative.

Antimicrobial compounds from traditional fermented foods have shown activity against a wide range of pathogen and spoilage microorganisms for several years. In this study, a Lactic acid bacteria (LAB), isolated from Vietnamese traditional fermented yogurt (Lactobacillus plantarum SC01), was encapsulated in alginate-gelatin (ALG-GEL) and the effect of incubation temperature, medium pH and surfactants were assessed. The aims of this research were to evaluate antimicrobial activity of bacteriocin produced by L. plantarum SC01. Another aim the research was to study the quality of pork meat treated with its Bacteriocin in 2 h as a bio-preservative at different storage times (0 h, 12 h, 24 h and 48 h) in room temperature, compared to control (treated with salt 40.0%). The antimicrobial activity of L. plantarum SC01 was identified through the inhibition rate of five indicator organisms, including Escherichia coli, Salmonella sp., Staphylococcus aureus, Listeria monocytogenes, and Bacillus subtilis by co-culture method. The results showed that L. plantarum SC01 microencapsulated in ALG-GEL (2.5% alginate and 6.0% gelatin, w/v) and 3.0% bacteria supplied into modified MRS medium (MRSOPTSC01) produced highly active compound inhibited the growth of indicator organisms at a density of 104–108 CFU/mL. Antibacterial compounds were highly active in a treatment at 80 °C; not to be affected by pH; affected by surfactant as Ethylenediaminetetraacetic acid (EDTA), Sodium dodecyl sulfate (SDS), and Tween. Moreover, LAB obtained from this study show the potent Bacteriocin in its usage as a preservative in food.

Engineered extremes: microbial interactions with steel and bentonite in a geological disposal facility

The conditions of the deep subsurface, combined by perturbations caused by geological disposal of radioactive waste create multiple extreme conditions (limited space availability, high pH, high temperature etc.) for microbial communities. Microbial activity has the potential to cause corrosion of steel and alteration of bentonite clays used in geological disposal facilities. To understand the limits on microbial growth, and the potential for microbial activity to affect the swelling behaviour of the bentonite and metal corrosion, a suite of laboratory experiments is being conducted. In situ repository conditions have been replicated in the MIND (Horizon2020) project. Preliminary results show evidence of corrosion in all experiments, an increase in the basal spacings of smectites in the zone immediately surrounding the steel and inoculated samples had evidence of calcite crystal formation, accompanied by differences in the iron phases. These experiments simulate the in situ conditions well, but the complex nature of this experimental design (high pressure and flow) reduces the practicality of varying the environmental conditions. To complement these investigations, a low-tech solution has been implemented with unpressurised, hydrated bentonite batch experiments. The simpler nature of this set-up allows for investigation of more parameters. Microcosms with artificial groundwater used in the MIND set-up are being compared to the MIND groundwater composition, modelled to represent permafrost conditions. The effect of incubation temperature is also being investigated. Combined, these experiments will help to understand the influence of microbes under the extremes of geological disposal facilities and how their behaviour may change by external parameters.

Incubation temperature effects on muscle weight, bone strength and walking ability in broilers

Incubation temperature effects on muscle weight, bone strength and walking ability in broilers

Effects of incubation temperature on hatchling performance and phenotype in loggerhead sea turtle Caretta caretta

ESR Endangered Species Research Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsSpecials ESR 38:45-53 (2019) - DOI: https://doi.org/10.3354/esr00935 Effects of incubation temperature on hatchling performance and phenotype in loggerhead sea turtle Caretta caretta Alejandro Usategui-Martín1,*, Ana Liria-Loza1, Jeffrey D. Miller2, María Medina-Suárez3, Saray Jiménez-Bordón4, Valentín Pérez-Mellado5, Daniel Montero1 1University of Las Palmas de Gran Canaria, EcoAqua University Institute, Telde, Las Palmas 35214, Spain 2Biological Research and Education Consultants, Missoula, Montana 55801, USA 3NGO Cabo Verde Natura 2000, Sal Rei 5110, Cape Verde 4NGO Asociación para el Desarrollo Sostenible y Conservación de la Biodiversidad, Agüimes, Las Palmas 35118, Spain 5University of Salamanca, Department of Animal Biology, Salamanca 37007, Spain *Corresponding author: ausategui@gmail.com ABSTRACT: Under natural conditions sea turtle eggs are subjected to a changing thermal environment, but little is known about the effect of these temperature fluctuations during incubation on the performance and phenotype of hatchlings. The aim of this study was to determine how incubation temperature pattern (increasing or stable) and incubation temperature regime (low or high) affect incubation and hatching duration, hatching and emergence success, hatchling phenotype (carapace length and weight) and self-righting interval at hatching. Loggerhead sea turtle Caretta caretta (Linnaeus, 1758) clutches were collected at different beaches on the Cape Verde archipelago and divided among incubators with different temperature regimes and patterns. Minimum straight carapace length and weight of all individuals were measured at hatching. In addition, the hatching duration and the time interval required for each hatchling to self-right were recorded. Results showed that incubation temperature regimes influenced all studied parameters more than the increasing temperature pattern. Low incubation temperature regimes, both in the increasing and stable pattern, increased the incubation time, produced bigger hatchlings and caused a slower righting response compared to the high temperature regimes. An optimal range of incubation temperatures was determined by assessing the most favorable values for hatchlings, although some differences were found in the higher temperatures of this optimal range between different rookeries. This means that turtle incubation in the laboratory should, as far as possible, follow the natural incubation temperature fluctuation of the studied rookery. KEY WORDS: Loggerhead sea turtle · Caretta caretta · Incubation temperature regime · Incubation temperature pattern · Hatchling performance · Hatchling phenotype · North Atlantic Full text in pdf format PreviousNextCite this article as: Usategui-Martín A, Liria-Loza A, Miller JD, Medina-Suárez M, Jiménez-Bordón S, Pérez-Mellado V, Montero D (2019) Effects of incubation temperature on hatchling performance and phenotype in loggerhead sea turtle Caretta caretta. Endang Species Res 38:45-53. https://doi.org/10.3354/esr00935 Export citation Mail this link - Contents Mailing Lists - RSS Facebook - Tweet - linkedIn Cited by Published in ESR Vol. 38. Online publication date: February 07, 2019 Print ISSN: 1863-5407; Online ISSN: 1613-4796 Copyright © 2019 Inter-Research.

Effects of incubation temperature and acetonitrile amount on microwave-assisted tryptic digestion of proteins

The effects of incubation temperature and acetonitrile (ACN) amount on microwave-assisted tryptic digestion of horse skeletal muscle myoglobin (MYG) and bovine serum albumin (BSA) were investigated. Microwave-assisted tryptic digestion was performed on BSA or MYG solutions containing different amounts (0, 10, and 20%) of ACN for different times (10, 20, 30, 40, and 50 min) at different temperatures (25, 37, and 55 °C). Conventional overnight tryptic digestion was also conducted with gentle mixing at 37 °C for 16 h. Digested samples were analyzed using matrix-assisted laser desorption/ionization mass spectrometry. Similar sequence coverage (SC) values were obtained under most conditions except when the protein sample solutions were digested with 20% ACN at 55 °C, which provided the lowest SC for both MYG and BSA for all investigated digestion times. Considering the missed cleavage (MC) ratios for 50-min microwave-assisted digestion, the highest MC ratio, (i.e., lowest trypsin activity) was observed for the digestion condition of 20% ACN at 55 °C for both proteins, while the lowest MC ratio was observed with 0% ACN at 25 °C for MYG and with 0% ACN at 55 °C for BSA. Conventional overnight tryptic digestion at 37 °C provided more completely cleaved peptides than 50-min microwave-assisted tryptic digestion at the same temperature.

Temperature dependence of characteristics of organic precursors, bromide, and disinfection byproduct formation

This study characterized the potential effects of elevated water temperature on source water quality and corresponding disinfection byproduct (DBP) formation. Results of laboratory simulations showed that although DBP formation increased with temperature, both the concentrations of dissolved organic carbon (DOC) and DBP formation decreased when water was incubated at higher temperatures (35 °C) prior to chlorination, probably due to increased microbial activity leading to greater degradation of organic precursors that affects DBP formation. However, the effect of incubation temperature prior to chlorination on final DBP formation varies with the characteristics of source water. When bromide was present, the ratio of Br-DBPs increased. The concentrations of total trihalomethanes (THMs) and haloacetonitriles (HANs) also increased when levels of bromide increased. This trend was not substantial for total haloacetic acids (HAAs). The hydrophobic organic precursors of THMs and HANs can be effectively removed by coagulation and filtration processes, and the effects of higher incubation temperature may thus be compromised. However, no apparent changes were observed for HAAs. The effects of bromide may also be more apparent in HAA and HAN formation after coagulation and filtration treatments.

Effect of thermal manipulation during embryogenesis on the promoter methylation and expression of myogenesis-related genes in duck skeletal muscle

Avian embryos are an ideal system to investigate the effect of incubation temperature on embryonic development, but the characteristics and mechanisms of temperature effects on poultry embryonic myogenesis are unclear. In this study, we investigated the effect of increasing the incubation temperature by 1 °C on the expression of nine myogenesis-related genes in ducks and then explored the correlation between the alteration of promoter methylation and the expression of two of the nine genes under thermal manipulation (TM). The qRT-PCR results showed that TM during embryonic days (ED) 1–10 promoted (P < 0.05) the expression of genes in breast muscle (PAX3, PAX7, MYOG, MCK, SIX1, TNNC1) and leg muscle (MYOD, MYOG, MYF5, MCK, AKIRIN2, TNNC1). TM during ED10-20 promoted the expression of PAX3, MYF5 and MCK and inhibited AKIRIN2 expression in breast muscle (P < 0.05); however, it inhibited the expression of PAX3, PAX7, MYOD, MYOG, MYF5, SIX1, AKIRIN2 and TNNC1 and promoted MCK expression in leg muscle (P < 0.05). TM during ED20-27 inhibited the expression of genes in breast muscle (PAX7) and leg muscle (MYOD, MYOG, MYF5, TNNC1) and promoted MCK expression in breast and leg muscle (P < 0.05). Furthermore, with the Sequenom MassARRAY platform, it was observed that the average methylation level of AKIRIN2 (ED10) and TNNC1 (ED20) in leg muscle decreased (P < 0.05) after TM. Notably, we found significant (P < 0.05) inverse correlations between the methylation and mRNA levels of AKIRIN2 under TM during ED1-10 (r = − 0.969) and ED10-20 (r = − 0.805). Taken together, TM during ED1-10 was more favorable for improving duck myogenesis-related gene expression than TM during ED10-20 and ED20-27. TM during duck embryogenesis seemed to have a greater effect on the development of leg muscle than breast muscle and might alter AKIRIN2 expression by changing its promoter methylation status. These findings may be helpful to understand temperature effects on the muscle development of avian embryos and to explore the role of epigenetic regulation during this process.

Effects of temperature and other environmental factors on the post‐diapause development of walnut husk fly Rhagoletis completa (Diptera: Tephritidae)

AbstractTo more effectively manage walnut husk fly Rhagoletis completa (Diptera: Tephritidae), in California walnut orchards, it is important to understand the factors that affect the timing of adult emergence. In the present study, we examine the effects of incubation temperature, pre‐chill and chill durations, latitude, cultivar and size on the post‐diapause development of R. completa puparia. The lower developmental threshold, upper developmental threshold and optimal temperature for puparial development are estimated to be 4, 34 and 26.6 °C, respectively. The thermal requirement for adult emergence after 120 days of chilling is estimated to be 2024 degree days. Percentage adult emergence declines at both higher and lower incubation temperatures. Chill duration at 5 °C for diapausing puparia has a nonlinear negative effect on the thermal requirement but no effect on percentage emergence. Insufficient chilling leads to poor synchronization of adult emergence. Greater pre‐chill duration at room temperature increases the thermal requirement and slightly decreased percentage emergence. Latitude has a negative effect on the thermal requirement. Puparia from northern California black walnut (Juglans hindsii) have a slightly greater thermal requirement than puparia from cultivated walnut (Julgans regia). There is no significant difference in puparial fresh weight or mean thermal requirement between males and females, although the positive correlation between thermal requirement and puparial fresh weight is stronger for females than males. The effects of temperature and other environmental factors on the post‐diapause development of R. completa are discussed in relation to observations from other Rhagoletis species.

72 Effect of incubation temperature and of CO2 concentration during early cleavage on equine in vitro embryo production

Intracytoplasmic sperm injection (ICSI) is currently being used for equine in vitro embryo production for both research and clinical purposes. However, some basic parameters for in vitro embryo production, such as the optimum incubator temperature and the optimum CO2 concentration/pH of medium for early embryo development, have not yet been established in the horse. The incubation temperature used by many laboratories for equine in vitro embryo production is 38.2°C, whereas the range of normal rectal temperature in the horse is 37.2 to 38.3°C. In Exp. 1, we evaluated maturation, cleavage, and blastocyst rates under 3 different culture temperatures. Cumulus-oocyte complexes were recovered from slaughterhouse-derived ovaries and shipped overnight at room temperature. Oocyte maturation was performed concurrently in separate incubators set to 37.2, 37.7, or 38.2°C. Mature oocytes were subjected to ICSI, then cultured in mixed gas (6% CO2, 5% O2, and remainder N2) at the same temperature at which they were matured. Embryo culture media used were a commercial human medium (global) for Days 0 to 5, then DMEM/F-12 from Day 5 to 10, both with 10% fetal bovine serum (FBS). In Exp. 2, we evaluated 3 different CO2 concentrations (6, 6.5, or 7% CO2) in mixed gas for the Day 0 to 5 culture in global+FBS, at 38.2°C. Cumulus-oocyte complexes were recovered from live mares by transvaginal aspiration and held overnight at room temperature; all other parameters remained the same as for Exp. 1. Data were analysed by Fisher’s exact test. In Exp. 1, a total of 280 oocytes were utilised; the outcomes for the 37.2, 37.7, and 38.2°C treatments were, respectively: maturation rates of 33, 38, and 42%; cleavage rates of 84, 86, and 88%; and blastocyst rates per injected oocyte of 35, 44, and 44%. There were no significant differences among the 3 temperature treatments for any parameter (P&amp;gt;0.2). In Exp. 2, the pH of the global+FBS medium was 7.38, 7.35, and 7.3 for 6, 6.5, and 7% CO2, respectively. A total of 106 mature oocytes underwent ICSI; the outcomes for the 3 CO2 atmospheres, respectively, were cleavage rates of 68, 80, and 70% and blastocyst rates per injected oocyte of 42, 54, and 27%. The blastocyst rate for the 7% CO2 treatment was significantly lower than that for the 6.5% CO2 treatment (P&amp;lt;0.05). These results indicate that equine in vitro embryo production is equally effective throughout the range of normal equine body temperature, and that equine blastocyst production is sensitive to small changes in CO2 atmosphere/pH of medium during early cleavage-stage development. Research was supported by the Clinical Equine ICSI Program, Texas A&amp;amp;M University, the Link Equine Research Endowment, Texas A&amp;amp;M University, and Fonds en Santé Équine (FSÉ), Faculté de Médecine Vétérinaire, and Université de Montréal.