Chick Embryo Heart Research Articles

The proximal segment of the embryonic outflow (conus) does not participate in aortic vestibule development.

ObjectiveThere is no consensus on the embryonic components or morphogenetic processes involved in mature ventricular outflow tract development. Our goal was to use in vivo labelling to investigate the prospective fate of the myocardium of each conal wall. The conal and atrioventricular cushion mesenchyme changes during transformation into mature structures and their role in apoptosis were also investigated.MethodsPlastic labels were placed at the cephalic and caudal conal limits of chicken embryo hearts (stage 22HH) and traced up to stage 36HH. Histological analyses, scanning electron microscopy and apoptotic detection using Lysotracker-Red were performed. The conal longitudinal length and medial displacement were registered. Muscle myosin was identified by immunofluorescence.ResultsLabels positioned in the myocardium of each conal wall moved to the right ventricle (RV), shifting from the arterial subvalvular myocardial zone to the apex. No labels were found in the aortic vestibule. At stage 22HH, the conus was a tubular structure composed of myocardium and endocardium with scarce mesenchyme. The dorso-left conal myocardial wall gradually lost continuity and the free ends separated, while the myocardium was distributed to the RV free wall (24HH-28HH). At stage 22HH, conal crests were not observed, but they were apparent at the dorsal zone of the conus at stage 26HH; towards stage 30HH, they fused to form the supraventricular crest, and the pulmonary infundibulum was evident. The ventro-superior cushion of the AV canal was reorganized into the fibrous and muscular structures lined the aortic vestibule.ConclusionsThe posterior conus is an erroneous concept. The conal myocardium is reorganized in the free wall of the RV. Internally, the conal lumen is transformed into the pulmonary infundibulum. The aortic vestibule is formed from the ventro-superior cushion of the AV canal. Thus, the ventricular outflow tracts have different embryonic origins.

Thalidomide remodels developing heart in chick embryo: discovery of a thalidomide mediated hematoma in heart muscle.

Despite of medical disaster caused by thalidomide in 1960s, the drug came to clinical use again for the treatment of erythema nodosum leprosum (ENL) and multiple myeloma. Recently, a new generation of children affected by thalidomide intake by their mothers during pregnancy has been identified in Brazil. In the past few years, there is the great enhancement in our understanding of the molecular mechanisms and targets of thalidomide with the help of modern OMICS technologies. However, understanding of cardiac-specific anomalies in fetus due to thalidomide intake by the respective mother has not been explored fully. At organ level, thalidomide causes congenital heart diseases, limb deformities in addition to ocular, and neural and ear abnormalities. The period of morning sickness and cardiogenesis is synchronized in pregnant women. Therefore, thalidomide intake during the first trimester could affect cardiogenesis severely. Thalidomide intake in pregnant women either causes miscarriage or heart abnormalities such as patent ductus arteriosus, ventricular septal defect (VSD), atrial septal defect (ASD), and pulmonary stenosis in survivors. In the present study, we identified a novel morphological defect (lump) in the heart of thalidomide-treated chick embryos. We characterized the lump at morphological, histo-pathological, oxidative stress, electro-physiological, and gene expression level. To our knowledge, here, we report the very first electrophysiological characterization of embryonic heart affected by thalidomide treatment.

The roles of bone morphogenetic protein 2 in perfluorooctanoic acid induced developmental cardiotoxicity and l-carnitine mediated protection

Perfluorooctanoic acid (PFOA), a wide spread environmental pollutant, was associated with developmental cardiotoxicity in chicken embryo, while the underlying molecular mechanism had not been fully elucidated. In the current study, 2 mg/kg (egg weight) PFOA and/or 100 mg/kg (egg weight) l-carnitine were exposed to embryonic day zero (ED0) chicken embryo via air cell injection, and then bone morphogenic protein 2 (BMP2) silencing lentivirus or BMP2 recombinant protein were introduced into ED2 embryo. Electrocardiography and histological methods were utilized to assess the cardiac function and morphology in hatchling chickens, respectively. Consistent with previous results, 2 mg/kg PFOA exposure at ED0 significantly elevated heart rate and thinned right ventricular wall in hatchling chickens, while l-carnitine co-treatment reverted such changes. BMP2 silencing induced very similar changes in hatchling chicken hearts as PFOA exposure, while co-exposure of recombinant BMP2 protein alleviated PFOA-induced changes. l-carnitine exposure alleviated the BMP2-silencing induced changes as well. Western blotting revealed that PFOA exposure enhanced BMP2 expression and suppressed pSMAD1 expression in ED15 chicken embryo hearts, while both changes were reverted by l-carnitine co-exposure. Furthermore, silencing of BMP2 significantly increased the expression level of PPAR alpha in ED15 chicken embryo hearts, while silencing of PPAR alpha did not have significant impact on BMP2 expression. In conclusion, BMP2/pSMAD1 signaling participates in the PFOA-induced developmental cardiotoxicity in chicken embryo, which is likely located upstream of PPAR alpha for this particular endpoint. Protection of BMP2 signaling might contribute to l-carnitine mediated protection against PFOA-induced developmental cardiotoxicity.

Effect of in ovo zinc injection on the embryonic development, tissue zinc contents, antioxidation, and related gene expressions of broiler breeder eggs

Two experiments were conducted to investigate the effect of in ovo zinc (Zn) injection on the embryonic development, tissue Zn contents, antioxidation and related gene expressions of fertilized eggs of Arbor Acres broiler breeders. Experiment 1 was conducted to determine an optimal embryonic age for early in ovo injection. A total of 720 fertilized eggs with similar weights were randomly allotted to 4 treatments with 6 replicates per treatment and 30 eggs per replicate in a completely randomized design. The eggs were injected with 0.1 mL sterilized water at 3, 6 and 9 embryonic days of incubation (E3, E6 and E9) or non-injection (the control), respectively. The results from experiment 1 showed that E3 and E6 injections increased (P<0.05) the embryonic mortalities, and decreased (P<0.05) hatchabilities compared to the non-injected control, but no differences (P>0.05) between E9 injection and the non-injected control were observed in either embryonic mortality or hatchability. The findings suggest that the E9 is the optimal embryonic age for early in ovo injection. In experiment 2, a total of 672 fertilized eggs with similar weights were randomly allocated to 7 treatments with 6 replicates per treatment and 16 eggs per replicate in a completely randomized design. The eggs were injected with 0 (the negative control), 50, 100, 150, 200, or 250 μg Zn/egg as reagent grade ZnSO4·7H2O in a 0.1-mL solution, or non-injection (the positive control), respectively at E9–10. The results from the experiment 2 demonstrated that no differences (P>0.05) among 50 and 100 μg Zn/egg groups and the negative control were observed in the embryonic mortality and hatchability, however, the injection of 200 μg Zn/egg increased (P<0.05) the embryonic mortality, and injections of 150 and 200 μg Zn/egg decreased (P<0.05) hatchabilities compared with the controls. The embryonic tibia Zn contents at E20 were increased (P<0.05) by injections of 150, 200 and 250 μg Zn/egg. Zinc injection did not affect (P > 0.05) malonaldehyde (MDA) contents, copper- and Zn-containing superoxide dismutase (CuZnSOD) activities and mRNA expression levels in the liver and heart of chick embryos at E15 and E20. Compared with the negative control, injections of 50, 150 and 200 μg Zn/egg up-regulated (P<0.05) the metallothionein (MT) mRNA expression levels in the embryonic liver at E20. These results indicated that in ovo Zn injections increased Zn contents in the embryonic tibia and MT mRNA expression levels in the embryonic liver at E20, however, injections of 150–200 μg Zn/egg were harmful to the embryonic development.

The role of PPAR alpha in perfluorooctanoic acid induced developmental cardiotoxicity and l-carnitine mediated protection–Results of in ovo gene silencing

Perfluorooctanoic acid (PFOA) is a persistent organic pollutant. This study established an in ovo peroxisome proliferator-activated receptor alpha (PPAR alpha) silencing model in chicken embryo heart, and investigated the role of PPAR alpha in PFOA induced developmental cardiotoxicity. The in ovo silencing was achieved by introducing lentivirus expressing PPAR alpha siRNA into ED2 chicken embryo via microinjection (0.05ul/g egg weight). Transfection efficacy was confirmed by fluorescent microscopy and western blotting. To assess the developmental cardiotoxicity, cardiac function (heart rate) and morphology (right ventricular wall thickness) were measured in D1 hatchling chickens. 2mg/kg (egg weight) PFOA exposure at ED0 induced significant elevation of heart rate and thinning of right ventricular wall thickness in D1 hatchling chickens. PPAR alpha silencing did not prevent PFOA-induced elevation of heart rate; however, it did significantly increase the right ventricular wall thickness as compared to PFOA exposed animals. Meanwhile, PPAR alpha silencing did not abolish the protective effects exerted by exposure to 100mg/kg (egg weight) l-carnitine. In conclusion, PFOA-induced heart rate elevation is likely PPAR alpha independent, while the right ventricular wall thinning seems to be PPAR alpha dependent. The protective effects of l-carnitine do not require PPAR alpha.

Increased Hemodynamic Load in Early Embryonic Stages Alters Myofibril and Mitochondrial Organization in the Myocardium.

Normal blood flow is essential for proper heart formation during embryonic development, as abnormal hemodynamic load (blood pressure and shear stress) results in cardiac defects seen in congenital heart disease (CHD). However, the detrimental remodeling processes that relate altered blood flow to cardiac malformation and defects remain unclear. Heart development is a finely orchestrated process with rapid transformations that occur at the tissue, cell, and subcellular levels. Myocardial cells play an essential role in cardiac tissue maturation by aligning in the direction of stretch and increasing the number of contractile units as hemodynamic load increases throughout development. This study elucidates the early effects of altered blood flow on myofibril and mitochondrial configuration in the outflow tract myocardium in vivo. Outflow tract banding was used to increase hemodynamic load in the chicken embryo heart between Hamburger and Hamilton stages 18 and 24 (~24 h during tubular heart stages). 3D focused ion beam scanning electron microscopy analysis determined that increased hemodynamic load induced changes in the developing myocardium, characterized by thicker myofibril bundles that were more disbursed in circumferential orientation, and mitochondria that organized in large clusters around the nucleus. Proteomic mass-spectrometry analysis quantified altered protein composition after banding that is consistent with altered myofibril thin filament assembly and function, and mitochondrial maintenance and organization. Additionally, pathway analysis of the proteomics data identified possible activation of signaling pathways in response to banding, including the renin-angiotensin system (RAS). Imaging and proteomic data combined indicate that myofibril and mitochondrial arrangement in early embryonic stages is a critical developmental process that when disturbed by altered blood flow may contribute to cardiac malformation and defects.

The Roles of Reactive Oxygen Species and Nitric Oxide in Perfluorooctanoic Acid-Induced Developmental Cardiotoxicity and l-Carnitine Mediated Protection.

Perfluorooctanoic acid (PFOA) is an environmental contaminant that could induce developmental cardiotoxicity in a chicken embryo, which may be alleviated by l-carnitine. To explore the roles of reactive oxygen species (ROS) and nitric oxide (NO) in such changes and the potential effects of l-carnitine, fertile chicken eggs were exposed to PFOA via an air cell injection, with or without l-carnitine co-treatment. The ROS and NO levels in chicken embryo hearts were determined with electron spin resonance (ESR), and the protein levels of the nuclear factor κ-light chain-enhancer of activated B cells (NF-κB) p65 and inducible nitric oxide synthase (iNOS) in chicken embryo hearts were assessed with western blotting. The results of ESR indicated that PFOA exposure induced an elevation in the ROS levels in ED19 chicken embryo hearts and hatchling chicken hearts, while l-carnitine could alleviate such changes. Meanwhile, increased NO levels were observed in ED19 embryo hearts and hatchling hearts following PFOA exposure, while l-carnitine co-treatment exerted modulatory effects. Western blotting revealed that p65 translocation in ED19 embryo hearts and hatchling hearts was enhanced by PFOA, while l-carnitine co-treatment alleviated such changes. iNOS expression levels in ED19 embryo hearts followed the same pattern as NO levels, while a suppression of expression was observed in hatchling hearts exposed to PFOA. ROS/NF-κB p65 and iNOS/NO seem to be involved in the late stage (ED19 and post hatch) of PFOA-induced developmental cardiotoxicity in a chicken embryo. l-carnitine could exert anti-oxidant and NO modulatory effects in the developing chicken embryo hearts, which likely contribute to its cardioprotective effects.

Increased Hemodynamic Load in Early Embryonic Stages Alters Endocardial to Mesenchymal Transition.

Normal blood flow is essential for proper heart formation during embryonic development, as abnormal hemodynamic load (blood pressure and shear stress) results in cardiac defects seen in congenital heart disease. However, the progressive detrimental remodeling processes that relate altered blood flow to cardiac defects remain unclear. Endothelial–mesenchymal cell transition is one of the many complex developmental events involved in transforming the early embryonic outflow tract into the aorta, pulmonary trunk, interventricular septum, and semilunar valves. This study elucidated the effects of increased hemodynamic load on endothelial–mesenchymal transition remodeling of the outflow tract cushions in vivo. Outflow tract banding was used to increase hemodynamic load in the chicken embryo heart between Hamburger and Hamilton stages 18 and 24. Increased hemodynamic load induced increased cell density in outflow tract cushions, fewer cells along the endocardial lining, endocardium junction disruption, and altered periostin expression as measured by confocal microscopy analysis. In addition, 3D focused ion beam scanning electron microscopy analysis determined that a portion of endocardial cells adopted a migratory shape after outflow tract banding that is more irregular, elongated, and with extensive cellular projections compared to normal cells. Proteomic mass-spectrometry analysis quantified altered protein composition after banding that is consistent with a more active stage of endothelial–mesenchymal transition. Outflow tract banding enhances the endothelial–mesenchymal transition phenotype during formation of the outflow tract cushions, suggesting that endothelial–mesenchymal transition is a critical developmental process that when disturbed by altered blood flow gives rise to cardiac malformation and defects.

The Effect of Stevia on the Chicken Embryo Heart.

Stevioside is one of the most important food additives that has become well known for its sweetness. The aim of this study was to evaluate the impact of Stevioside on the heart. 4-day-old embryonated chickens eggs were inoculated with Stevioside and kept until hatching. Shortly after, the heart tissue samples were taken to examine organ Oxidative stresses by measuring Malondialdehyde (MDA) and glutathione (GSH) levels, ferric reducing /antioxidant power (FRAP) and cupric ion reducing assay (CUPRIC). There was no significant difference in glutathione level, lipid peroxidation, FRAP, and cupric assay. It was suggested that stevioside did not cause marked damages to heart tissues in chicken embryo model.

Changes in the levels of l-carnitine, acetyl-l-carnitine and propionyl-l-carnitine are involved in perfluorooctanoic acid induced developmental cardiotoxicity in chicken embryo.

Perfluorooctanoic acid (PFOA), a persistent organic pollutant, is associated with developmental toxicity. This study investigated the mechanism of PFOA-induced developmental cardiotoxicity in chicken embryo, focusing on the interactions between developmental exposure to PFOA and the levels of l-carnitine (LC), acetyl-l-carnitine (ALC) and propionyl-l-carnitine (PLC) in the heart. To evaluate the developmental cardiotoxicity, fertile chicken eggs were exposed to 0.1, 0.5, 1, 2 or 5mg/kg PFOA via air cell injection. Furthermore, exposure to 2mg/kg PFOA, with or without 100mg/kg LC were applied to investigate the effects of LC supplement. The results of functional and morphological assessments confirmed PFOA induced developmental cardiotoxicity in chicken embryo, which could be alleviated by co-exposure to LC. LC-MS/MS results also revealed remarkable decrease in LC, ALC and PLC levels in embryonic day six (ED6) chicken embryo hearts as well as LC level in embryonic day fifteen (ED15) chicken embryo hearts following developmental exposure to 2mg/kg PFOA. Meanwhile, co-exposure to 100mg/kg LC significantly elevated the levels of LC, ALC and PLC in chicken embryo hearts. Significantly elevated expression level of carnitine acetyltransferase (CRAT) in PFOA-exposed ED6 chicken embryo hearts was observed via western blotting, while LC co-exposure counteracted such changes. In conclusion, changes in the levels of LC, ALC and PLC in early embryonic stages are associated with PFOA induced developmental cardiotoxicity in chicken embryos.

Measurement of wall strain in embryonic chick heart by spectral domain optical coherence tomography

During cardiac development, the growth, remodeling and morphogenesis of embryonic hearts are closely linked to hemodynamic forces. An understanding of the interaction mechanism between hemodynamic forces and heart development is important for the early diagnosis and treatment of various congenital defects. The myocardial wall strain (MWS) in embryonic heart is a critical parameter for quantifying the mechanical properties of cardiac tissues. Here, we focus on the radial strain which is defined as the change of the myocardial wall thickness. An effective measurement of MWS is conductive to studies of embryonic heart development. Chick embryo is a popular animal model used for studing the cardiac development due to the similarity of cardiac development between the human heart and the chick heart at early developmental stages and its easy access. Although various imaging methods have been proposed, there still remain significant challenges to imaging of early stage chick embryo heart because it is small in size and beats fast. Optical coherence tomography (OCT) is a non-contact three-dimensional imaging modality with high spatial and temporal resolution which has been widely used for imaging the biological tissue. In this paper, we describe a method to measure in vivo MWS of chicken embryonic hearts with a high speed spectral domain OCT(SDOCT) system worked at 1310 nm. We perform four-dimensional (4D) (x, y, z, t) scanning on the outflow tract (OFT) of chick embryonic hearts in a non-gated way. The transient states of the OFT are extracted from the 4D data by using the beating synchronization algorithm. The OFT center line can be achieved by image processing. Assuming that the blood flow is parallel to the center line in the blood vessel, we calculate the Doppler angle of blood flow from the OFT center line. In a certain OFT cross-section, the OFT myocardial wall (inner and external borders) is segmented from the OCT images with a semi-automatic boundary-detection algorithm. Then, the myocardial wall thickness is calculated from the Doppler angle, area and sum of inner and external radii of the segmented myocardial wall. The radial strain is obtained by calculating the myocardial wall thickness variation. Previous methods calculated the myocardial wall thickness by directly subtracting inner and external radii. The measured result may be deteriorated by insufficient resolution of the system since the myocardial wall of OFT is very thin. The present method can solve this problem by calculating the thickness through using the sum of the radii instead of the subtraction. The experimental results on embryonic chick hearts demonstrate that the proposed method can measure the MWS of OFT along arbitrary orientation and it is a useful tool for studying the biomechanical characteristics of embryonic hearts.

A descriptive study to provide evidence of the teratogenic and cellular effects of sibutramine and ephedrine on cardiac‐ and liver‐tissue of chick embryos

Exposure to drugs during pregnancy is a major concern, as some teratogenic compounds can influence normal foetal development. Although the use of drugs during pregnancy should generally be avoided, exposure of the developing foetus to teratogens may occur unknowingly since these compounds may be hidden in products that are being marketed as "all natural." The aim of the current study was to investigate the possible teratogenic and cellular effects of sibutramine-a serotonin-norepinephrine reuptake inhibitor used in the treatment of obesity-on the heart and liver tissue of chick embryos. Ephedrine was used as a positive control. The chick embryo model was chosen because it has been used in studying developmental and experimental biology and teratology with great success. The embryos were exposed to three different concentrations of sibutramine and ephedrine respectively. The results obtained revealed that both compounds exhibited embryotoxicity when compared to the control groups. Liver and heart tissue of the exposed embryos was severely affected by these compounds in a dose-related manner. Morphology similar to that of muscle dystrophy was observed in the heart, where the muscle tissue was infiltrated by adipose and connective tissue. Severe liver steatosis was also noted. A more in-depth investigation into the molecular pathways involved might provide more information on the exact mechanism of toxicity of these products influencing embryonic development.

Autophagy inhibitors reduce avian-reovirus-mediated apoptosis in cultured cells and in chicken embryos.

Avian reovirus (ARV)-induced apoptosis contributes to the pathogenesis of reovirus in infected chickens. However, methods for effectively reducing ARV-triggered apoptosis remain to be explored. Here, we show that pretreatment with chloroquine (CQ) or E64d plus pepstatin A decreases ARV-mediated apoptosis in chicken DF-1 cells. By acting as autophagy inhibitors, CQ and E64d plus pepstatin A increase microtubule-associated protein 1 light chain 3-II (LC3II) accumulation in ARV-infected cells, which results in decreased ARV protein synthesis and virus yield and thereby contributes to the reduction of apoptosis. Furthermore, ARV-mediated apoptosis in the bursa, heart and intestines of chicken embryos is attenuated by CQ and E64d plus pepstatin A treatment. Importantly, treatment with these autophagy inhibitors increases the survival of infected chicken embryos. Together, our data suggest that pharmacological inhibition of autophagy might represent a novel strategy for reducing ARV-mediated apoptosis.

Dynamics of tissue and ultrastructural changes in the embryonic heart of the chick embryo

The analysis and comparison of histostructural and ultrastructural features of systole and diastole of the chick embryo heart at 29-46th stages on Hamburger, Hamilton were carried out. The main differences between the chambers of the embryonic heart by the nature of developmental dynamics of systolic and diastolic gradients, shows geometrical transformation of the walls of the chambers to reduce, described the features of the ultrastructure of sarcomeres, depending on the location of cardiomyocytes.

Non-contact, motion-tolerant measurements of chicken (Gallus gallus) embryo heart rate (HR) using video imaging and signal processing

The chicken embryo provides an excellent model organism for physiological and developmental biology studies. The chick chorioallantoic membrane (CAM) is widely used to study angiogenesis and vasculogenesis in primary tumour growth. The cardiovascular system is the first organ system to form and function in the developing embryo. Heart rate (HR) is deemed to be an important physiological parameter in such studies. The heart rate of the developing embryo can be very informative in developmental studies of cardiac rhythm. Many studies have considered developing techniques to measure avian embryonic heart rate from incubated eggs. However, the existing techniques disturb the incubation process and/or are sensitive to embryonic motion. A novel non-contact, semi-invasive, and motion-tolerant technique to measuring embryonic heart rate from chicken eggs using video imaging and signal processing is described and implemented in this paper. The technique is based on videos captured from incubated eggs to recover heart rate signals. Heart rate is estimated using frequency analysis techniques and the values obtained are in agreement with results from the literature. The technique proposed in this paper provides a real-time approach to monitoring developmental embryonic heart rate. Also it can provide a promising technique for monitoring the developing vasculature in primary tumour growth.

3D imaging of the early embryonic chicken heart with focused ion beam scanning electron microscopy.

Early embryonic heart development is a period of dynamic growth and remodeling, with rapid changes occurring at the tissue, cell, and subcellular levels. A detailed understanding of the events that establish the components of the heart wall has been hampered by a lack of methodologies for three-dimensional (3D), high-resolution imaging. Focused ion beam scanning electron microscopy (FIB-SEM) is a novel technology for imaging 3D tissue volumes at the subcellular level. FIB-SEM alternates between imaging the block face with a scanning electron beam and milling away thin sections of tissue with a FIB, allowing for collection and analysis of 3D data. FIB-SEM was used to image the three layers of the day 4 chicken embryo heart: myocardium, cardiac jelly, and endocardium. Individual images obtained with FIB-SEM were comparable in quality and resolution to those obtained with transmission electron microscopy. Up to 1,100 serial images were obtained in 4 nm increments at 4.88 nm resolution, and image stacks were aligned to create volumes 800-1,500 μm3 in size. Segmentation of organelles revealed their organization and distinct volume fractions between cardiac wall layers. We conclude that FIB-SEM is a powerful modality for 3D subcellular imaging of the embryonic heart wall.

Increases in Levels of Epoxyeicosatrienoic and Dihydroxyeicosatrienoic Acids (EETs and DHETs) in Liver and Heart in Vivo by 2,3,7,8-Tetrachlorodibenzo-p-Dioxin (TCDD) and in Hepatic EET:DHET Ratios by Cotreatment with TCDD and the Soluble Epoxide Hydrolase Inhibitor AUDA

The environmental toxin and carcinogen 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD, dioxin) binds and activates the transcription factor aryl hydrocarbon receptor (AHR), inducing CYP1 family cytochrome P450 enzymes. CYP1A2 and its avian ortholog CYP1A5 are highly active arachidonic acid epoxygenases. Epoxygenases metabolize arachidonic acid to four regioisomeric epoxyeicosatrienoic acids (EETs) and selected monohydroxyeicosatetraenoic acids (HETEs). EETs can be further metabolized by epoxide hydrolases to dihydroxyeicosatrienoic acids (DHETs). As P450-arachidonic acid metabolites affect vasoregulation, responses to ischemia, inflammation, and metabolic disorders, identification of their production in vivo is needed to understand their contribution to biologic effects of TCDD and other AHR activators. Here we report use of an acetonitrile-based extraction procedure that markedly increased the yield of arachidonic acid products by lipidomic analysis over a standard solid-phase extraction protocol. We show that TCDD increased all four EETs (5,6-, 8,9-, 11,12-, and 14,15-), their corresponding DHETs, and 18- and 20-HETE in liver in vivo and increased 5,6-EET, the four DHETs, and 18-HETE in heart, in a chick embryo model. As the chick embryo heart lacks arachidonic acid-metabolizing activity, the latter findings suggest that arachidonic acid metabolites may travel from their site of production to a distal organ, i.e., heart. To determine if the TCDD-arachidonic acid-metabolite profile could be altered pharmacologically, chick embryos were treated with TCDD and the soluble epoxide hydrolase inhibitor 12-(3-adamantan-1-yl-ureido)-dodecanoic acid (AUDA). Cotreatment with AUDA increased hepatic EET-to-DHET ratios, indicating that the in vivo profile of P450-arachidonic acid metabolites can be modified for potential therapeutic intervention.

English

Due to the ease of absorption, accumulation in tissues, and extremely long biological half-life in the body, cadmium is considered one of the most hazardous heavy metals. The aim of the study was to investigate the effect of&nbsp;in ovo&nbsp;injection of cadmium on chicken embryo heart. A total of 160 chicken hatching eggs were used in the study. On day 4 of incubation, eggs from the experimental groups were injected with cadmium at a dose of 1 and 5 &micro;g/egg and the incubation was prolonged to 21 day until hatching. Cadmium was found to slow the heart rate and reduce heart weight. In embryos exposed to 5 &micro;g of cadmium, the histological analysis and aminotransferases concentration confirmed the occurrence of inflammatory processes in the heart muscle. &nbsp; Key words:&nbsp;Cadmium, heart, chicken embryo, cardiotoxicity.

Comparative Analysis of Nkx2-5/GATA4/TBX5 Expression in Chicken, Quail and Chicken-quail Hybrids during the Early Stage of Cardiac Development in Embryos.

The present study makes an investigation into expression of genes related to cardiac development in chicken, quail and chicken-quail hybrids during the early stage of embryogenesis. Real-time PCR was used to detect mRNA expressions of Nkx2-5, GATA4 and TBX5 in the heart of chicken, quail and chicken-quail hybrids embryos during the 3rd to 7th days of incubation. Results showed that NKX2-5 mRNA displayed a similar expression trend in chicken, quail and chicken-quail hybrids. The initial and highest expression of Nkx2-5 was focused on the 3rd day of incubation, then it declined till 5th day of incubation, thereafter, it fluctuated. Expression of Nkx2-5 gene in quail was significantly higher than in chicken and chicken-quail hybrids, and no significant difference was observed between the two latter species. GATA4 mRNA showed a similar expression trend between chicken and quail, which displayed a steady increase from 3rd to 6th d, then, the expression level decreased. However, GATA4 mRNA expression in chicken-quail hybrids was significantly higher than that in chicken and quail from 3rd to 5th d (p<0.01), but significantly lower than that in chicken and quail during the later stage of the experiment (p<0.05), due to the dramatic drop from 5th d onwards (p<0.01). TBX5 mRNA expression in chicken and quail showed the same trend as GATA4 expressed in the two species. Furthermore, TBX5 expression in chicken-quail hybrids was significantly higher than that in chicken and quail during the whole course of experiment, although relatively lower TBX5 expression was detected in the early stage. In conclusion, Nkx2-5, GATA4 and TBX5 genes showed dynamic changes during the process of cardiac development in chicken, quail and their hybrids embryos. In addition, the expression trend in chicken was similar to that in quail, and there was no significant difference for gene expression level, except NKX2-5. However, expression of these genes in chicken-quail hybrids was significantly different from their parents, the difference mechanism needs to be further explored.

Effects of 50 Hz extremely low frequency sinusoidal magnetic fields on the apoptosis of the hearts of preincubated chicken embryos at different levels of developments

Purpose: The aim of this research was to demonstrate the effects of 50 Hz sinusoidal extremely low frequency of magnetic fields (ELF-MF) on preincubated chicken embryo hearts at histopathological, biochemical, and ultrastructural levels.Materials and methods: Ninety healthy fertilized eggs were divided into six groups of control, sham and four (1–4) experimental groups exposed to 1.33, 2.66, 5.52, and 7.32 mT flux intensities. Sham groups were placed inside the coil with no exposure for 24 h, while the eggs of experimental groups were exposed to four different intensities inside the coil for 24 h before incubation. Then, all were incubated in an incubator (37 ± 0.5°C and 60% humidity) for 14 days.Results: Evidence proved that ELF-MF create damaged myocytes in experimental group 1; condensed dark nuclei, an increase in the number of apoptotic cells in addition to increased intracellular spaces in experimental group 2; light inflammation and myocyte necrosis in experimental groups 3 and 4; an increase in the number of nuclear membranes’ pores, small round unclear cristae mitochondria, and a decrease in the number of mitochondria in the myocytes of experimental group 4; and also an increase in alkaline phosphatase activities in the experimental groups.Conclusion: The effects of ELF-MF on the preincubated chicken embryos’ hearts show the necessity for conservation plans for prevention from possible harm.