Heme oxygenase/carbon monoxide system and development of the heart

Progressive differentiation controlled by intercellular signaling between pharyngeal mesoderm, foregut endoderm, and neural crest-derived mesenchyme is required for normal embryonic and fetal development. Gasotransmitters (criteria: 1) a small gas molecule; 2) freely permeable across membranes; 3) endogenously and enzymatically produced and its production regulated; 4) well-defined and specific functions at physiologically relevant concentrations; 5) functions can be mimicked by exogenously applied counterpart; and 6) cellular effects may or may not be second messenger-mediated, but should have specific cellular and molecular targets) are integral to gametogenesis and subsequent embryogenesis, fetal development, and normal heart maturation. Important for in utero development, the heme oxygenase/carbon monoxide system is expressed during gametogenesis, by the placenta, during embryonic development, and by the fetus. Complex sequences of biochemical pathways result in the progressive maturation of the human heart in utero . The resulting myocardial architecture, consisting of working myocardium, coronary arteries and veins, epicardium, valves and cardiac skeleton, endocardial lining, and cardiac conduction system, determines function. Oxygen metabolism in normal and maldeveloping hearts, which develop under reduced and fluctuating oxygen concentrations, is poorly understood. "Normal" hypoxia is critical for heart formation, but "abnormal" hypoxia in utero affects cardiogenesis. The heme oxygenase/carbon monoxide system is important for in utero cardiac development, and other factors also result in alterations of the heme oxygenase/carbon monoxide system during in utero cardiac development. This review will address the role of the heme oxygenase/carbon monoxide system during cardiac development in embryo and fetal development.

Insights into the microscopic heterogeneity of whey proteins between yak colostrum and mature milk based on 4D lable-free quantitative phosphoproteomics

This study aimed to reveal the change patterns of the phosphorylation modification status of yak whey phosphoproteins during lactation and their physiological effects. Herein, we comprehensively characterized whey phosphoproteome in yak colostrum and mature milk using an ultra-high throughput phosphoproteomics approach incorporating trapped ion mobility technology. A total of 344 phosphorylation sites from 206 phosphoproteins were identified, with individual site modification predominating. Notably, 117 significantly different phosphorylation sites were distributed on 89 whey phosphoproteins. Gene ontology analysis indicated that these significantly different whey phosphoproteins (SDWPPs) were mainly annotated to carbohydrate metabolic process, membrane, extracellular region and calcium ion binding. Metabolic pathway enrichment analysis demonstrated that SDWPPs were critically involved in protein processing in endoplasmic reticulum, NOD-like receptor signaling pathway and N-glycan biosynthesis. Our results elucidate the phosphorylation profiles of yak whey phosphoproteins at different lactations and their adaptive regulatory role in meeting the nutritional requirements of yak calves during development.

Redox differences between rat neonatal and adult cardiomyocytes under hypoxia

It is generally accepted that oxidative stress plays a key role in the development of ischemia-reperfusion injury in ischemic heart disease. However, the mechanisms how reactive oxygen species trigger cellular damage are not fully understood. Our study investigates redox state and highly reactive substances within neonatal and adult cardiomyocytes under hypoxia conditions. We have found that hypoxia induced an increase in H2O2 production in adult cardiomyocytes, while neonatal cardiomyocytes experienced a decrease in H2O2 levels. This finding correlates with our observation of the difference between the electron transport chain (ETC) properties and mitochondria amount in adult and neonatal cells. We demonstrated that in adult cardiomyocytes hypoxia caused the significant increase in the ETC loading with electrons compared to normoxia. On the contrary, in neonatal cardiomyocytes ETC loading with electrons was similar under both normoxic and hypoxic conditions that could be due to ETC non-functional state and the absence of the electrons transfer to O2 under normoxia. In addition to the variations in H2O2 production, we also noted consistent pH dynamics under hypoxic conditions. Notably, the pH levels exhibited a similar decrease in both cell types, thus, acidosis is a more universal cellular response to hypoxia. We also demonstrated that the amount of mitochondria and the levels of cardiac isoforms of troponin I, troponin T, myoglobin and GAPDH were significantly higher in adult cardiomyocytes compared to neonatal ones. Remarkably, we found out that under hypoxia, the levels of cardiac isoforms of troponin T, myoglobin, and GAPDH were elevated in adult cardiomyocytes, while their level in neonatal cells remained unchanged. Obtained data contribute to the understanding of the mechanisms of neonatal cardiomyocytes' resistance to hypoxia and the ability to maintain the metabolic homeostasis in contrast to adult ones.

Effects of chronic hypoxia on the gene expression profile in the embryonic heart in three Chinese indigenous chicken breeds (Gallus gallus)

Hypoxia exposure (HE) has adverse impacts on the embryonic development of chicken, whereas the mechanism underlying the response of the heart to HE during embryo development in birds is still unclear. Therefore, our study was designed to reveal the hub genes and the signaling pathways linked to chronic hypoxia stress. Thus, the gene expression microarray GSE12675, downloaded from the GEO database, included 12 embryonic heart samples in hypoxia and normoxia of three Chinese indigenous chicken breeds [Shouguang (SG), Tibetan (TB), and Dwarf Recessive White (DRW) chickens]. A total of 653 to 714 breed-specific differentially expressed genes (DEGs) were detected in each pairwise comparison. Gene ontology (GO) showed that the DEGs were mainly involved in biological processes, including vasoconstriction, cell differentiation, and the positive regulation of vasoconstriction. KEGG enrichment revealed that the DEGs were mainly enriched in MAPK, PPAR, insulin, adrenergic signaling in cardiomyocytes, etc. Moreover, 48 genes (e.g., SGCD, DHRS9, HELQ, MCMDC2, and ESCO2) might contribute to the response of the heart to HE. Taken together, the current study provides important clues for understanding the molecular mechanism of the heart's response to HE during the embryonic period of chicken.

Hypoxia during incubation and its effects on broiler's embryonic development

In all vertebrates, hypoxia plays an important role in fetal development, driving vasculogenesis, angiogenesis, hematopoiesis, and chondrogenesis. Therefore, the ability to sense and respond to changes in the availability of oxygen (O2) is crucial for normal embryonic development as well as for developmental plasticity. Moderate levels of hypoxia trigger a regulated process which leads to adaptive responses. Regulation of angiogenesis by hypoxia is an important component of homeostatic control mechanisms that link the cardio-pulmonary-vascular O2 supply to metabolic demands in local tissues. Hypoxia leads to the activation of genes that are important for cell and tissue adaptation to low O2 conditions, such as hypoxia-inducible factor 1. Previous studies have shown a dose-response effect to hypoxia in chicken embryos, with lower and/or prolonged O2 levels affecting multiple mechanisms and providing a spectrum of responses that facilitate the ability to maintain O2 demand despite environmental hypoxia. In chicken embryos, mild to extreme hypoxia during embryogenesis improves chorioallantoic membrane and cardiovascular development, resulting in an increase in O2 carrying capacity and leading to developmental plasticity that may affect post-hatch chick performance and improve adaptation to additional environmental stresses at suboptimal environmental conditions.

Increased systemic inflammation in children with Down syndrome

Children with Down syndrome (DS) develop more infections, have an increased mortality from sepsis and an increased incidence of chronic inflammatory conditions. Cytokine dysregulation may underpin these clinical sequelae and raised pro-inflammatory biomarkers are a feature in adults with DS. The importance of the anti-inflammatory mediators IL-1ra and IL-10, as well as cytokines Epo and VEGF, which could impact on the pathogenesis and outcomes in congenital heart disease (CHD) which is more prevalent in DS, are less well known. We examined a comprehensive array of pro-(IL-2, IL-6, IL-8, IL-18, IL-1β, TNF-α, IFN-γ), and anti-inflammatory (IL-10 and IL-1ra) mediators, cytokines involved in inflammation in response to hypoxia (EPO), propagating angiogenesis (VEGF), and myelopoiesis (GM-CSF), by enzyme linked immunosorbent assay (ELISA), as well as discussing the potential impact of significant CHD and Lipopolysaccharide endotoxin on these mediators. 114 children with DS and 60 age and sex matched controls were recruited. Children with Down syndrome exhibit significantly greater levels of pro and anti-inflammatory cytokines; IL-2, IL-6, IL-10, IL-1ra, as well as increased Epo, VEGF and GM-CSF at baseline. CHD does not seem to have an impact on circulating cytokines beyond the acute surgical phase. Both cohorts had similar responses to LPS stimulation. These differences may contribute to varied clinical outcomes, acutely like in sepsis, and over time in autoimmunity.

Antioxidant Defence Systems and Oxidative Stress in Poultry Biology: An Update

Poultry in commercial settings are exposed to a range of stressors. A growing body of information clearly indicates that excess ROS/RNS production and oxidative stress are major detrimental consequences of the most common commercial stressors in poultry production. During evolution, antioxidant defence systems were developed in poultry to survive in an oxygenated atmosphere. They include a complex network of internally synthesised (e.g., antioxidant enzymes, (glutathione) GSH, (coenzyme Q) CoQ) and externally supplied (vitamin E, carotenoids, etc.) antioxidants. In fact, all antioxidants in the body work cooperatively as a team to maintain optimal redox balance in the cell/body. This balance is a key element in providing the necessary conditions for cell signalling, a vital process for regulation of the expression of various genes, stress adaptation and homeostasis maintenance in the body. Since ROS/RNS are considered to be important signalling molecules, their concentration is strictly regulated by the antioxidant defence network in conjunction with various transcription factors and vitagenes. In fact, activation of vitagenes via such transcription factors as Nrf2 leads to an additional synthesis of an array of protective molecules which can deal with increased ROS/RNS production. Therefore, it is a challenging task to develop a system of optimal antioxidant supplementation to help growing/productive birds maintain effective antioxidant defences and redox balance in the body. On the one hand, antioxidants, such as vitamin E, or minerals (e.g., Se, Mn, Cu and Zn) are a compulsory part of the commercial pre-mixes for poultry, and, in most cases, are adequate to meet the physiological requirements in these elements. On the other hand, due to the aforementioned commercially relevant stressors, there is a need for additional support for the antioxidant system in poultry. This new direction in improving antioxidant defences for poultry in stress conditions is related to an opportunity to activate a range of vitagenes (via Nrf2-related mechanisms: superoxide dismutase, SOD; heme oxygenase-1, HO-1; GSH and thioredoxin, or other mechanisms: Heat shock protein (HSP)/heat shock factor (HSP), sirtuins, etc.) to maximise internal AO protection and redox balance maintenance. Therefore, the development of vitagene-regulating nutritional supplements is on the agenda of many commercial companies worldwide.

Responses of developmental and physiological traits to manipulated incubation conditions in broiler embryos at hypoxic high altitude

Abstract. The effects of hypoxia at increased altitude levels on the cardio-respiratory development of broiler embryos are distinct in comparison with those at sea level. The aim of the study was to investigate the effects of high incubation temperature (H) and oxygen supplementation (O) during hypoxic high altitude (HA) on developmental and physiological traits of embryos and hatching performance of embryonated hatching eggs in broilers at different embryonic stages. A total of 1280 eggs obtained from broiler breeders laid at sea level were used. Eggshell quality characteristics were measured for 20 eggs. The rest of the 1260 eggs were divided into seven incubation condition (IC) groups (180 eggs per group) including a control group at 37.8 ∘C and 21 % O2; O groups, with daily 1 h 23.5 % O2 supplementation at 37.8 ∘C as O0−11, O12−21, and O18−21; H groups at 38.5 ∘C high incubation temperature at 21 % O2 as H0−11, H12−21, and H18−21 from days 0 to 11, 12 to 21, and 18 to 21 of incubation, respectively. All groups were incubated in three different incubators at hypoxic HA. The effect of IC was determined on eggshell temperature, hatching performance, embryo development, right ventricular (RV) to total ventricular (TV) ratio, and blood parameters. The highest egg water loss and embryonic mortality and the lowest hatchability were in the H0−11 group, which depended on increased eggshell temperature during incubation. On day 18 of incubation, due to the decreased egg water loss in the O12−21 and O18−21 groups, there was an increase in hatchability in fertile eggs similar to the middle and late H groups. Towards the end of incubation, embryo/chick weights were not different and RV and TV weights increased in the treated groups, and the RV ∕ TV ratio changed between 15 and 26 %. At hatching, yolk sac weight increased in H0−11 and H12−21 groups. The O groups had the lowest serum tri-iodothyronine (T3) concentration as distinct from H groups. The serum thyroxine (T4) concentration increased in the treated groups, dependent on sex of the embryo. Blood hemoglobin concentration of O groups decreased relative to other groups. The hematocrit value was the lowest in the O12−21 and highest in the H12−21 groups. The H and O treatments during pre-hatch hypoxic HA condition can be positively evaluated on physiological traits of embryos after half of incubation depended on the timing of the IC exposure to the hatching eggs obtained from broiler breeders at sea level.

The highs and lows of programmed cardiovascular disease by developmental hypoxia: studies in the chicken embryo

It is now established that adverse conditions during pregnancy can trigger a fetal origin of cardiovascular dysfunction and/or increase the risk of heart disease in later life. Suboptimal environmental conditions during early life that may promote the development of cardiovascular dysfunction in the offspring include alterations in fetal oxygenation and nutrition as well as fetal exposure to stress hormones, such as glucocorticoids. There has been growing interest in identifying the partial contributions of each of these stressors to programming of cardiovascular dysfunction. However, in humans and in many animal models this is difficult, as the challenges cannot be disentangled. By using the chicken embryo as an animal model, science has been able to circumvent a number of problems. In contrast to mammals, in the chicken embryo the effects on the developing cardiovascular system of changes in oxygenation, nutrition or stress hormones can be isolated and determined directly, independent of changes in the maternal or placental physiology. In this review, we summarise studies that have exploited the chicken embryo model to determine the effects on prenatal growth, cardiovascular development and pituitary-adrenal function of isolated chronic developmental hypoxia.

Combinatory Evaluation of Transcriptome and Metabolome Profiles of Low Temperature-induced Resistant Ascites Syndrome in Broiler Chickens

To select metabolic biomarkers and differentially expressed genes (DEGs) associated with resistant-ascites syndrome (resistant-AS), we used innovative techniques such as metabolomics and transcriptomics to comparatively examine resistant-AS chickens and AS controls. Metabolomic evaluation of chicken serum using ultra-performance liquid chromatography-quadruple time-of-flight high-sensitivity mass spectrometry (UPLC-QTOF/HSMS) showed significantly altered lysoPC(18:1), PE(18:3/16:0), PC(20:1/18:3), DG(24:1/22:6/0:0), PS(18:2/18:0), PI(16:0/16:0), PS(18:0/18:1), PS(14:1/14:0), dihydroxyacetone, ursodeoxycholic acid, tryptophan, L-valine, cycloserine, hypoxanthine, and 4-O-Methylmelleolide concentrations on day 21 and LysoPC(18:0), LysoPE(20:1/0:0), LysoPC(16:0), LysoPE(16:0/0:0), hypoxanthine, dihydroxyacetone, 4-O-Methylmelleolide, LysoPC(18:2), and PC(14:1/22:1) concentrations on day 35, between the susceptible and resistant groups. Compared to the susceptible group, transcriptomic analysis of liver samples using RNA-seq revealed 413 DEGs on day 21 and 214 DEGs on day 35 in the resistant group. Additional evaluations using gene ontology (GO) indicate that significant enrichment occurred in the oxygen transportation, defensive reactions, and protein modifications of the decreased DEGs as well as in the cell morphological formation, neural development, and transforming growth factor (TGF)-beta signalling of the increased DEGs on day 21. Oxygen transportation was also significantly enriched for downregulated DEGs on day 35. The combinatory evaluation of the metabolome and the transcriptome suggests the possible involvement of glycerophospholipid metabolism in the development of resistant-AS in broilers.

Physiological effects of hypoxic conditions during the plateau period on the chicken embryo

The chick embryo employs several adaptive responses to hypoxic challenges, affecting both metabolism and oxygen (O₂) transport. The present study assessed the effects of hypoxic conditions (17% O₂) during the plateau phase on embryonic metabolic rate, cardiovascular parameters, and development up to hatching. The study was divided into 2 experiments: (1) Control; 17% O₂ for 6h/d on E16-E18 (6H), and 17% O₂ for 12h/d on E16-E18 (12H), and (2) Control; 12H, and 17% O₂ continuously for 72h on E16-E18, (72H). Hypoxic embryos exhibited a significant increase in heart rate and an upward trend starting on E17 in hematocrit and hemoglobin levels. We observed a decrease in metabolism in 12H and 72H embryos during the plateau period; their oxygen consumption as well as yolk consumption were lower compared to Control and they hatched with a significantly lower body temperature, indicating lower heat production. There was no evidence of adaptation or long-term effects of exposure to 17% O₂ for 6h/d. Exposure to 72h of hypoxic conditions led to significant physiological changes and had a detrimental influence on embryonic development and growth. In contrast, exposure to 12h/d produced moderate hypoxic changes, which helped the embryo to cope with the stress without significant influences on its growth and development. The decrease in metabolism may represent a metabolic adaptation through a decrease in resting metabolic rate and lower heat production. Such alterations may affect post-hatch performance and energy allocation between maintenance and growth, especially under stress when there is increased oxygen demand.

Effects of Bacillus licheniformis on the growth performance and expression of lipid metabolism-related genes in broiler chickens challenged with Clostridium perfringens-induced necrotic enteritis

Background

Necrotic enteritis (NE), caused by Clostridium perfringens, has cost the poultry industry $2 billion in losses. This study aimed to investigate the effect of Bacillus licheniformis as dietary supplement on the growth, serum antioxidant status, and expression of lipid-metabolism genes of broiler chickens with C. perfringens-induced NE.

Methods

A total of 240 one-day-old broilers were randomly grouped into four: a negative control, an NE experimental model (PC), chickens fed a diet supplemented with 30 % of fishmeal from day 14 onwards and challenged with coccidiosis vaccine (FC), and NE group supplied with feed containing 1.0 × 10⁶ CFU/g B. licheniformis (BL).

Results

Body weight gain, feed conversion ratio, serum antioxidant status, and lipid-metabolism-gene expression were analyzed. In the PC group, FCR increased significantly whereas serum catalase and glutathione peroxidase activity decreased compared with NC group. Dietary B. licheniformis supplementation improved FCR and oxidative stress in experimental avian NE. Using Bacillus licheniformis as a direct-fed microbial (DFM) could also significantly upregulate catabolism-related genes, namely, peroxisome proliferator-activated receptor-α and carnitine palmitoyltransferase-1, in livers and changed the expression of lipid-anabolism genes.

Conclusion

These results suggested that dietary B. licheniformis supplementation can enhance growth and antioxidant ability, as well as change the expression of genes related to fatty-acid synthesis and oxidation in the livers of NE-infected broilers.

Molecular Mechanisms of Lipoic Acid Protection against Aflatoxin B₁-Induced Liver Oxidative Damage and Inflammatory Responses in Broilers

Alpha-lipoic acid (α-LA) was evaluated in this study for its molecular mechanisms against liver oxidative damage and inflammatory responses induced by aflatoxin B₁ (AFB₁). Birds were randomly allocated into four groups with different diets for three weeks: a basal diet, a 300 mg/kg α-LA supplementation in a basal diet, a diet containing 74 μg/kg AFB₁, and 300 mg/kg α-LA supplementation in a diet containing 74 μg/kg AFB₁. In the AFB₁ group, the expression of GSH-P_X mRNA was down-regulated (p < 0.05), and the levels of lipid peroxide and nitric oxide were increased (p < 0.05) in the chicken livers compared to those of the control group. Additionally, the mRNA level of the pro-inflammatory factor interleukin-6 was up-regulated significantly (p < 0.05), the protein expressions of both the nuclear factor kappa B (NF-κB) p65 and the inducible nitric oxide synthase were enhanced significantly (p < 0.05) in the AFB₁ group. All of these negative effects were inhibited by α-LA. These results indicate that α-LA may be effective in preventing hepatic oxidative stress, down-regulating the expression of hepatic pro-inflammatory cytokines, as well as inhibiting NF-κB expression.

Angiogenic Gene Expression in Down Syndrome Fetal Hearts

INTRODUCTION

Forty percent of Down syndrome (DS) fetuses have congenital heart defects (CHD). An abnormal angiogenic environment has been described in euploid fetuses with CHD. However, the underlying pathophysiologic pathway that contributes to CHD in DS remains unknown. The objective was to compare the expression of angiogenic factors and chronic hypoxia genes in heart tissue from DS and euploid fetuses with and without CHD.

METHODS

The gene expression profile was determined by real-time PCR quantification in heart tissue from 33 fetuses with DS, 23 euploid fetuses with CHD and 23 control fetuses.

RESULTS

Angiogenic factors mRNA expression was significantly increased in the DS group compared to the controls (soluble fms-like tyrosine kinase-1, 81%, p = 0.007; vascular endothelial growth factor A, 57%, p = 0.006, and placental growth factor, 32%, p = 0.0227). Significant increases in the transcript level of hypoxia-inducible factor-2α and heme oxygenase 1 were also observed in the DS group compared to the controls. The expression of angiogenic factors was similar in DS fetuses and CHD euploid fetuses with CHD.

CONCLUSION

Abnormal angiogenesis was detected in the hearts of DS fetuses with and without CHD. Our results suggest that DS determines an intrinsically angiogenic impairment that may be present in the fetal heart.

Expression pattern of heme oxygenase 1 gene and hypoxic adaptation in chicken embryos

Heme oxygenase 1 (HO-1), a rate-limiting enzyme of heme catabolism, has a crucial role of cytoprotective functions under hypoxia. The objective of the present study was to investigate potential differences in protective effect of HO-1 gene on chicken (Gallus gallus) embryo lung during late incubation. At embryonic day (D) D16, D18, D19, and D20 of incubation, the expression of HO-1 in the lungs of chicken embryos (Tibet and Shouguang chickens) incubated in normoxic (21% O2) and hypoxic (13% O2) conditions was measured. SNPs were screened within 5'-flanking region and coding regions with PCR-sequencing and the genotype of the SNPs was determined with PCR-RFLP in Tibet, Chahua and Shouguang chicken populations. In conclusion, the Tibet chicken had higher HO-1 expression on D19 under hypoxic incubation and had two SNPs with different frequency distributions from other chicken breeds, which might be a way that the Tibet chicken had hereditary adaptation to hypoxia during embryonic development.

Effects of lipoic acid on immune function, the antioxidant defense system, and inflammation-related genes expression of broiler chickens fed aflatoxin contaminated diets

This study was designed to evaluate the effect of low level of Aflatoxin B₁ (AFB₁) on oxidative stress, immune reaction and inflammation response and the possible ameliorating effects of dietary alpha-lipoic acid (α-LA) in broilers. Birds were randomly allocated into three groups and assigned to receive different diets: basal diet, diet containing 74 μg/kg AFB₁, and 300 mg/kg α-LA supplementation in diet containing 74 μg/kg AFB₁ for three weeks. The results showed that the serum levels of malondialdehyde, tumor necrosis factor alpha (TNFα) and interferon gamma (IFNγ) in the AFB₁-treated group were significantly increased than the control group. In addition, the increased expressions of interleukin 6 (IL6), TNFα and IFNγ were observed in birds exposed to the AFB₁-contaminated diet. These degenerative changes were inhibited by α-LA-supplement. The activities of total superoxide dismutase and glutathione peroxidase, the levels of humoral immunity, and the expressions of nuclear factor-κB p65 and heme oxygenase-1, however, were not affected by AFB₁. The results suggest that α-LA alleviates AFB₁ induced oxidative stress and immune changes and modulates the inflammatory response at least partly through changes in the expression of proinflammatory cytokines of spleen such as IL6 and TNFα in broiler chickens.

Maternal and foetal angiogenic imbalance in congenital heart defects

AIMS

Animal models showed that angiogenesis is related to abnormal heart development. Our objectives were to ascertain whether a relationship exists between congenital heart defects (CHDs) and angiogenic/anti-angiogenic imbalance in maternal and foetal blood and study the expression of angiogenic factors in the foetal heart.

METHODS AND RESULTS

Maternal and cord blood placental growth factor (PlGF), soluble fms-like tyrosine kinase-1 (sFlt-1) and soluble endoglin (sEng) were compared in 65 cases of CHD and 204 normal controls. Angiogenic factor expression and markers of hypoxia were measured in heart tissue from 23 CHD foetuses and 8 controls. In the CHD group, compared with controls, plasma PlGF levels were significantly lower (367 ± 33 vs. 566 ± 26 pg/mL; P < 0.0001) and sFlt-1 significantly higher (2726 ± 450 vs. 1971 ± 130 pg/mL, P = 0.0438). Foetuses with CHD had higher cord plasma sFlt-1 (442 ± 76 vs. 274 ± 26 pg/mL; P = 0.0285) and sEng (6.76 ± 0.42 vs. 4.99 ± 0.49 ng/mL, P = 0.0041) levels. Expression of vascular endothelial growth factor (VEGF), sFlt-1, markers of chronic hypoxia, and antioxidant activity were significantly higher in heart tissue from CHD foetuses compared with normal hearts (VEGF, 1.59-fold; sFlt-1, 1.92-fold; hypoxia inducible factor (HIF)-2α, 1.45-fold; HO-1, 1.62-fold; SOD1, 1.31-fold).

CONCLUSION

An intrinsically angiogenic impairment exists in CHD that appears to be present in both the maternal and foetal circulation and foetal heart. Our data suggest that an imbalance of angiogenic-antiangiogenic factors is associated with developmental defects of the human heart.

Effects of Clostridium butyricum and Enterococcus faecium on growth performance, lipid metabolism, and cecal microbiota of broiler chickens

To investigate the effects of Clostridium butyricum and Enterococcus faecium on the growth performance, lipid metabolism, and cecal microbiota of broilers, 264 one-day-old male Ross 308 broiler chicks were randomly allocated into four treatments with six replicates in a 2 × 2 factorial arrangement and fed four diets with two levels of C. butyricum (0 or 1 × 10⁹ cfu/kg) and two levels of E. faecium (0 or 2 × 10⁹ cfu/kg) for 42 days. There was no significant interaction between C. butyricum and E. faecium on the growth performance, lipid metabolism, and cecal microbiota of broilers. However, broilers supplemented with E. faecium had lower (P = 0.022) serum leptin level at day 21 and higher (P < 0.001) fatty acid synthase (FAS), malic enzyme (ME), and acetyl-CoA carboxylase (ACC) mRNA levels in the liver at day 42. Supplementation of C. butyricum improved (P < 0.05) the average daily feed intake and average daily gain, increased (P = 0.016) the serum insulin level at 21 days of age, enhanced (P < 0.05) the content of intramuscular fat, activities of FAS in the liver and lipoprotein lipase (LPL) in the breast muscle, mRNA expression of FAS, ME, and ACC in the liver and LPL in the breast muscle at 42 days of age, but reduced (P = 0.030) cecal Bacteroidetes relative abundance at 21 days of age. The results of this study indicate that the increased intramuscular fat content of broilers fed C. butyricum as observed may be the result of enhanced lipogenesis.

Reduced O2 concentration during CAM development--its effect on angiogenesis and gene expression in the broiler embryo CAM

Hypoxia during embryogenesis may induce changes in the development of some physiological regulatory systems, thereby causing permanent phenotypic changes in the embryo. Various levels of hypoxia at different time points during embryogenesis were found to affect both anatomical and physiological morphogenesis. These changes and adaptations depended on the timing, intensity, and duration of the hypoxic exposure and, moreover, were regulated by differential expression of developmentally important genes, mostly expressed in a stage- and time-dependent manner. Eggs incubated in a 17%-oxygen atmosphere for 12 h/d from E5 through E12 exhibited a clear and significant increase in the vascular area of the chorioallantoic membrane (CAM); an increase that was already significant within 12 h after the end of the 1st hypoxic exposures (E6). We used the combination of the genes, β-actin, RPLP0 and HPRT as a reference for gene expression profiling, in studying the expression levels of hypoxia-inducible factor 1-alpha (HIF1α), vascular endothelial growth factor alpha-2 (VEGF α 2), vascular endothelial growth factor receptor 2 (KDR), matrix metalloproteinase-2 (MMP2), and fibroblast growth factor 2 (FGF2), under normal and hypoxic conditions. In general, expression of all five investigated genes throughout the embryonic day of development had similar patterns of hypoxia-induced alterations. In E5.5 embryos, expression of HIF1α, MMP2, VEGFα2, and KDR was significantly higher in hypoxic embryos than in controls. In E6 embryos expression of HIF1α, VEGFα2, and FGF2 was significantly higher in hypoxic embryos than in controls. From E6.5 onward expression levels of the examined genes did not show any differences between hypoxic and control embryos. It can be concluded that in this experimental model, exposing broiler embryos to 17% O(2) from E5 to E7 induced significant angiogenesis, as expressed by the above genes. Further studies to examine whether this early exposure to hypoxic condition affects the chick's ability to withstand a post-hatch hypoxic environment is still required.

Direct fed microbial supplementation repartitions host energy to the immune system

Direct fed microbials and probiotics are used to promote health in livestock and poultry; however, their mechanism of action is still poorly understood. We previously reported that direct fed microbial supplementation in young broilers reduced ileal respiration without changing whole-body energy expenditure. The current studies were conducted to further investigate the effects of a direct fed microbial on energy metabolism in different tissues of broilers. One hundred ninety-two 1-d-old broiler chicks (16 chicks/pen) were randomly assigned to 2 dietary groups: standard control starter diet (CSD) and CSD plus direct fed microbial (DFMD; 0.3%) with 6 pens/treatment. Body weight, feed consumption, whole-body energy expenditure, organ mass, tissue respiration rates, and peripheral blood mononuclear cell (PBMC) ATP concentrations were measured to estimate changes in energy metabolism. No differences in whole body energy expenditure or BW gain were observed; however, decreased ileal O(2) respiration (P < 0.05) was measured in DFMD fed broilers. In contrast, the respiration rate of the thymus in those broilers was increased (P < 0.05). The PBMC from DFMD fed broilers had increased ATP concentrations and exhibited increased ATP turnover (P < 0.01). To determine if the increased energy consumption by PBMC corresponded with an altered immune response, broilers were immunized with sheep red blood cells (SRBC) and assayed for differences in their humoral response. The DFMD-fed broilers had a faster rate of antigen specific IgG production (P < 0.05) and an increase in total IgA (P < 0.05). Collectively, these data indicate that supplementation with the direct fed microbial used in this study resulted in energy re-partitioning to the immune system and an increase in antibody production independent of changes in whole body metabolism or growth performance.

Identification of differentially expressed genes in the heart precursor cells of the chick embryo

Genetic evidence has implicated several genes as being critical for heart development. However, the inducers of these genes as well as their targets and pathways they are involved with, remain largely unknown. Previous studies in the avian embryo showed that at HH4 Cerberus (cCer) transcripts are detected in the anterior endomesoderm including the heart precursor cells and later in the left lateral plate mesoderm. We have identified a promoter element of chick cCer able to drive EGFP expression in a population of cells that consistently exit from the anterior primitive streak region, from as early as stage HH3+, and that later will populate the heart. Using this promoter element as a tool allowed us to identify novel genes previously not known to potentially play a role in heart development. In order to identify and study genes expressed and involved in the correct development and differentiation of the vertebrate heart precursor cell (HPC) lineages, a differential screening using Affymetrix GeneChip system technologies was performed. Remarkably, this screening led to the identification of more than 700 transcripts differentially expressed in the heart forming regions (HFR). Bioinformatic tools allowed us to filter the large amount of data generated from this approach and to select a few transcripts for in vivo validation. Whole-mount in situ hybridization and sectioning of selected genes showed heart and vascular expression patterns for these transcripts during early chick development. We have developed an effective strategy to specifically identify genes that are differentially expressed in the HPC lineages. Within this set we have identified several genes that are expressed in the heart, blood and vascular lineages, which are likely to play a role in their development. These genes are potential candidates for future functional studies on early embryonic patterning.

Hypoxia and fetal heart development

Fetal hearts show a remarkable ability to develop under hypoxic conditions. The metabolic flexibility of fetal hearts allows sustained development under low oxygen conditions. In fact, hypoxia is critical for proper myocardial formation. Particularly, hypoxia inducible factor 1 (HIF-1) and vascular endothelial growth factor play central roles in hypoxia-dependent signaling in fetal heart formation, impacting embryonic outflow track remodeling and coronary vessel growth. Although HIF is not the only gene involved in adaptation to hypoxia, its role places it as a central figure in orchestrating events needed for adaptation to hypoxic stress. Although "normal" hypoxia (lower oxygen tension in the fetus as compared with the adult) is essential in heart formation, further abnormal hypoxia in utero adversely affects cardiogenesis. Prenatal hypoxia alters myocardial structure and causes a decline in cardiac performance. Not only are the effects of hypoxia apparent during the perinatal period, but prolonged hypoxia in utero also causes fetal programming of abnormality in the heart's development. The altered expression pattern of cardioprotective genes such as protein kinase c epsilon, heat shock protein 70, and endothelial nitric oxide synthase, likely predispose the developing heart to increased vulnerability to ischemia and reperfusion injury later in life. The events underlying the long-term changes in gene expression are not clear, but likely involve variation in epigenetic regulation.