Methyl donors dietary supplementation to gestating sows diet improves the growth rate of offspring and is associating with changes in expression and DNA methylation of insulin-like growth factor-1 gene

In ovo betaine injection improves breast muscle growth in newly hatched goslings through FXR/IGF-2 pathway

Betaine has been shown to enhance growth performance and increase breast muscle yield in ducks and broilers through various mechanisms, including the modification of DNA methylation. However, the impact of in ovo betaine injection on muscle growth in newly hatched goslings remains unclear. In this study, fifty eggs were injected with saline or betaine at 7.5 mg/egg prior to incubation, and the subsequent effects on breast muscle growth in the newly hatched goslings were investigated. Betaine significantly increased (P < 0.05) the hatch weight, breast muscle weight, and breast muscle index, accompanied by an augmentation in muscle bundle cross-sectional area. Concurrently, betaine significantly upregulated (P < 0.05) the expression levels of myogenic regulatory factors, including myogenin (MyoG) and paired box 7 (Pax7) both mRNA and protein, while downregulating (P < 0.05) the mRNA and protein levels of myostatin (MSTN). Histological analysis revealed a higher abundance of proliferating cell nuclear antigen (PCNA) and Pax7 immune-positive cells in the breast muscle of the betaine group, consistent with elevated PCNA and Pax7 mRNA and protein levels. Additionally, significantly increased (P < 0.05) contents of insulin-like growth factor 1 (IGF-1) and insulin-like growth factor 2 (IGF-2) were observed in the breast muscle of the betaine group, so was mRNA expression of IGF-1, IGF-2, and insulin-like growth factor 1 receptor (IGF-1R). Betaine also significantly in8creased (P < 0.05) global DNA methylation of the breast muscle, accompanied by enhanced mRNA and protein levels of methionine cycle and DNA methylation-related enzymes, Interestingly, the promoter regions of IGF-1, IGF-2, and IGF-1R genes were significantly hypomethylated (P < 0.05). Moreover, in ovo betaine injection significantly upregulated (P < 0.05) the protein level of farnesoid X receptor (FXR) in breast muscle and FXR binding to the promoter of IGF-2 gene. These findings suggest that in ovo betaine injection promotes breast muscle growth during embryonic development in goslings through the FXR-mediated IGF-2 pathway, ultimately improving hatch weight and breast muscle weight.

Effects of maternal methyl donor intake during pregnancy on ileum methylation and function in an intrauterine growth restriction pig model

BACKGROUND

Intrauterine growth retardation (IUGR) affects intestinal growth, morphology, and function, which leads to poor growth performance and high mortality. The present study explored whether maternal dietary methyl donor (MET) supplementation alleviates IUGR and enhances offspring's growth performance by improving intestinal growth, function, and DNA methylation of the ileum in a porcine IUGR model.

METHODS

Forty multiparous sows were allocated to the control or MET diet groups from mating until delivery. After farrowing, 8 pairs of IUGR and normal birth weight piglets from 8 litters were selected for sampling before suckling colostrum.

RESULTS

The results showed that maternal MET supplementation tended to decrease the IUGR incidence and increased the average weaning weight of piglets. Moreover, maternal MET supplementation significantly reduced the plasma concentrations of isoleucine, cysteine, urea, and total amino acids in sows and newborn piglets. It also increased lactase and sucrase activity in the jejunum of newborn piglets. MET addition resulted in lower ileal methionine synthase activity and increased betaine homocysteine S-methyltransferase activity in the ileum of newborn piglets. DNA methylation analysis of the ileum showed that MET supplementation increased the methylation level of DNA CpG sites in the ileum of newborn piglets. Down-regulated differentially methylated genes were enriched in folic acid binding, insulin receptor signaling pathway, and endothelial cell proliferation. In contrast, up-regulated methylated genes were enriched in growth hormone receptor signaling pathway and nitric oxide biosynthetic process.

CONCLUSIONS

Maternal MET supplementation can reduce the incidence of IUGR and increase the weaning litter weight of piglets, which may be associated with better intestinal function and methylation status.

Parental betaine supplementation promotes gosling growth with epigenetic modulation of IGF gene family in the liver

Betaine is widely used as a feed additive in the chicken industry to promote laying performance and growth performance, yet it is unknown whether betaine can be used in geese to improve the laying performance of goose breeders and the growth traits of offspring goslings. In this study, laying goose breeders at 39 wk of age were fed basal (Control, CON) or betaine-supplemented diets at low (2.5 g/kg, LBT) or high (5 g/kg, HBT) levels for 7 wk, and the breeder eggs laid in the last week were collected for incubation. Offspring goslings were examined at 35 and 63 d of age. The laying rate tended to be increased (P = 0.065), and the feed efficiency of the breeders was improved by betaine supplementation, while the average daily gain of the offspring goslings was significantly increased (P < 0.05). Concentrations of insulin-like growth factor 2 (IGF-2) in serum and liver were significantly increased in the HBT group (P < 0.05), with age-dependent alterations of serum T3 levels. Concurrently, hepatic mRNA expression of the IGF gene family was significantly increased in goslings derived from betaine-treated breeders (P < 0.05). A higher ratio of proliferating cell nuclear antigen (PCNA)-immunopositive nuclei was found in the liver sections of the HBT group, which was confirmed by significantly upregulated hepatic expression of PCNA mRNA and protein (P < 0.05). Moreover, hepatic expression of thyroxine deiodinase type 1 (Dio1) and thyroid hormone receptor β (TRβ) was also significantly upregulated in goslings of the HBT group (P < 0.05). These changes were associated with significantly higher levels of global DNA 5-mC methylation, together with increased expression of methyl transfer genes (P < 0.05), including betaine-homocysteine methyltransferase (BHMT), glycine N-methyltransferase (GNMT), and DNA (cytosine-5-)-methyltransferase 1 (DNMT1). The promoter regions of IGF-2 genes, as well as the predicted TRβ binding site on the IGF-2 gene, were significantly hypomethylated (P < 0.05). These results indicate that gosling growth can be improved by dietary betaine supplementation in goose breeders via epigenetic modulation of the IGF gene family, especially IGF-2, in the liver.

Transgenerational transmission of environmental effects in livestock in the age of global warming

Recent decades provide mounting evidence for the continual increase in global temperatures, now termed "global warming," to the point of drastic worldwide change in the climate. Climatic change is a long-term shift in temperatures and weather patterns, including increased frequency and intensity of extreme environmental events such as heat waves accompanied by extreme temperatures and high humidity. Climate change and global warming put several challenges to the livestock industry by directly affecting the animal's production, reproduction, health, and welfare. The broad impact of global warming, and in particular heat stress, on-farm animals' performance has been comprehensively studied. It has been estimated that the US livestock industry's loss caused by heat stress is up to $2.4 billion annually. However, the long-term intergenerational and transgenerational effects of climatic change and global warming on farm animals are sparse. Transgenerational effects, which are mediated by epigenetic mechanisms, can affect the animal's performance regardless of its immediate environment by altering its phenotypic expression to fit its ancestors' environment. In many animal species, environmental effects are epigenetically encoded within a narrow time interval during the organism's gametogenesis, and these epigenetic modifications can then be intergenerationally transmitted. Several epigenetic mechanisms mediate intergenerational transmission of environmental effects, typically in a parent-dependent manner. Therefore, exposure of the animal to an extreme climatic event and other environmental stressors during gametogenesis can undergo epigenetic stabilization in the germline and be passed to the offspring. As a result, the offspring might express a phenotype adjusted to fit the stressors experienced by their ancestors, regardless of their direct environment. The purpose of this perspective is to review current evidence for intergenerational and transgenerational transmission of environmental stress effects, specifically in the context of global warming and climate change, and to offer viewpoints on the possible impacts on the livestock industry.

Epigenetic control of heredity

Epigenetics is the field of science that deals with the study of changes in gene function that do not involve changes in DNA sequence and are heritable while epigenetics inheritance is the process of transmission of epigenetic modifications to the next generation. It can be transient, intergenerational, or transgenerational. There are various epigenetic modifications involving mechanisms such as DNA methylation, histone modification, and noncoding RNA expression, all of which are inheritable. In this chapter, we summarize the information on epigenetic inheritance, its mechanism, inheritance studies on various organisms, factors affecting epigenetic modifications and their inheritance, and the role of epigenetic inheritance in the heritability of diseases.

An exploratory study on the effect of choline and folate deficiency on levels of vascularization proteins and transcription factors in first trimester trophoblast HTR-8/SVneo cells

AIMS

We studied the effect of choline and folate deficiencies on levels of predetermined placental proteins during early development.

METHODS

We incubated HTR-8/SVneo cells under choline and folate deficiency conditions and measured levels of some placental proteins using ELISA methods.

RESULTS

Concentrations of LRP2 protein in cell lysates were higher in cells incubated in choline and folate deficient media compared to the control media (mean [SD] = 2.95 [1.30] vs. 1.65 [0.27] ng/mg protein, p = 0.004). The levels of LRP2 protein in lysates of cells incubated in choline and folate deficient media were significantly higher than the concentrations in lysates of cells incubated in choline deficient but folate sufficient media (1.96 [0.28] ng/mg protein) or those incubated in choline sufficient but folate deficient media (1.77 [0.24] ng/mg protein) (p < 0.05 for both). The cellular levels of CDX2 protein were significantly higher in cells incubated in choline and folate deficient media compared to the control media (1.78 [0.60] vs. 0.99 [0.42] pg/mg protein, p = 0.002); and compared to CDX2 levels in cells incubated in choline deficient but folate sufficient media (0.87 [0.13] pg/mg protein, p < 0.001) or in choline sufficient but folate deficient media (0.96 [0.16] pg/mg protein, p < 0.001). The levels of sFLT-1 and IGF1 in culture media and that of EOMES in HTR-8/SVneo cell lysates remained unchanged under all deficiency conditions.

DISCUSSION

LRP2 and CDX2 are likely to be molecular targets for early choline and folate deficiencies in human trophoblast cells. The results should be confirmed in animal models and in other models of placental cells.

Effects of dietary dimethylglycine supplementation on laying performance, egg quality, and tissue index of hens during late laying period

In this study, the effects of 5 graded dietary levels (0.025, 0.05, 0.075, 0.1, and 0.125%) of dimethylglycine (DMG) were studied in laying hens during the late laying period (71–78 wk). Graded doses of DMG from 0.025 to 0.125% in the diet produced quadratic positive (P < 0.05) responses in the laying rate, egg-feed ratio, yolk color, grade follicular weight, and the number of large white follicles and linear positive (P < 0.05) responses in average egg weight, and the number of large white follicles. With 0.1% DMG, the laying rate and egg-feed ratio improved (P < 0.05), and the abdominal fat percentage decreased. Considering the laying performance under the conditions used in this study, the best-fit model for the DMG requirements of laying hens was estimated to range from 0.049 to 0.065% DMG during the late laying period based on a regression analysis. The addition of DMG did not affect the total cholesterol (TCH) and triglyceride (TG) contents in the plasma of laying hens; however, it significantly reduced the abdominal fat rate. DMG may change the course of lipid deposition in laying hens during the late laying period. In conclusion, supplementation with DMG can improve the laying rate and follicles development of laying hens.

Methionine Protects Mammary Cells against Oxidative Stress through Producing S-Adenosylmethionine to Maintain mTORC1 Signaling Activity

The mechanistic target of rapamycin complex 1 (mTORC1) signaling plays pivotal roles in cell growth and diseases. However, it remains mechanistically unclear about how to maintain mTORC1 activity during mammary glands development. Here we showed that mammary glands suffered from aggravated oxidative stress as pregnancy advanced and was accompanied by an increase in H₂O₂ levels, while the consumption for methionine and S-adenosylmethionine (SAM) rather than S-adenosylhomocysteine (SAH) were promoted in vivo. Likewise, H₂O₂ promoted SAM synthesis and reduced SAM utilization for methylation depending on H₂O₂ levels and treatment time in vitro. H₂O₂ inhibited phosphorylation of S6 kinase Thr 389 (p-S6K1 (T389)), 4E-BP1 Thr 37/46 and ULK1 Ser 757, the downstream of mTORC1, in mammary epithelial cells. However, methionine and SAM were shown to activate mTORC1 under H₂O₂-exposed condition. Moreover, this effect was not disabled by SGI-1027 which inhibits SAM transmethylation. In conclusion, methionine appeared to protect mammary cells against oxidative stress through producing SAM to maintain mTORC1 signaling activity.

Impacts of Epigenetic Processes on the Health and Productivity of Livestock

The dynamic changes in the epigenome resulting from the intricate interactions of genetic and environmental factors play crucial roles in individual growth and development. Numerous studies in plants, rodents, and humans have provided evidence of the regulatory roles of epigenetic processes in health and disease. There is increasing pressure to increase livestock production in light of increasing food needs of an expanding human population and environment challenges, but there is limited related epigenetic data on livestock to complement genomic information and support advances in improvement breeding and health management. This review examines the recent discoveries on epigenetic processes due to DNA methylation, histone modification, and chromatin remodeling and their impacts on health and production traits in farm animals, including bovine, swine, sheep, goat, and poultry species. Most of the reports focused on epigenome profiling at the genome-wide or specific genic regions in response to developmental processes, environmental stressors, nutrition, and disease pathogens. The bulk of available data mainly characterized the epigenetic markers in tissues/organs or in relation to traits and detection of epigenetic regulatory mechanisms underlying livestock phenotype diversity. However, available data is inadequate to support gainful exploitation of epigenetic processes for improved animal health and productivity management. Increased research effort, which is vital to elucidate how epigenetic mechanisms affect the health and productivity of livestock, is currently limited due to several factors including lack of adequate analytical tools. In this review, we (1) summarize available evidence of the impacts of epigenetic processes on livestock production and health traits, (2) discuss the application of epigenetics data in livestock production, and (3) present gaps in livestock epigenetics research. Knowledge of the epigenetic factors influencing livestock health and productivity is vital for the management and improvement of livestock productivity.

Maternal exercise and its beneficial effects on glucose metabolism in offspring

It shows that detrimental exposures and conditions in mothers can lead to the development of obesity and type 2 diabetes in offspring. This can lead to a vicious cycle of metabolic dysfunction, where rising rates of obesity, pre-diabetes, and diabetes in individuals of reproductive age, propagating risks to subsequent generations. It is well established that regular exercise has important health benefits for people with obesity and type 2 diabetes. Recently, increasing studies aim to examine the effects of maternal exercise on metabolic health in offspring. This review aims to demonstrate the evidence linking maternal exercise during critical periods of development and its implications for glucose metabolism in offspring, including intervention timing, sexual dimorphism, different exercise type, and intensity. Then we further examine the potential role of epigenetic modifications in this process.

Investigation of growth retardation in Macrobrachium rosenbergii based on genetic/epigenetic variation and molt performance

Giant freshwater prawn, Macrobrachium rosenbergii is an important freshwater aquaculture species worldwide, and China contributes the most to its global production. However, in recent years in China, many prawns have shown serious growth retardation, which is referred to as "iron prawn." To explore the mechanism behind this phenomenon, we compared the difference between these "iron prawns" and normal prawns in three aspects-changes in genetic diversity, DNA methylation, and transcriptomes-as well as comparing differences in their molt performance. The results are as follows: first, compared with normal prawns, "iron prawns" showed no significant decrease in genetic diversity, but they did show obvious genetic differentiation, and different DNA methylation levels were observed. The genetic and epigenetic variations that existed between "iron prawn" and normal prawn indicated the influence of germplasm on growth performance. Second, transcriptome analysis revealed 1813 differentially expressed genes (DEGs) between the "iron prawn" and normal prawn, and the DEGs mainly enriched the glucose metabolism- and immune-related pathways, such as in glycolysis/gluconeogenesis metabolism, insulin secretion, glucagon signaling pathway, antigen processing and presentation, as well as in complement and coagulation cascades. Enrichment analysis indicated the importance of the glucose level and pathogen attacks to growth performance in the "iron prawn." Finally, a comparison of the molt performance showed that the length of the molt cycle in the "iron prawn" was comparable to normal prawns with the same size, but the specific growth was much lower in the "iron prawn." This result suggested that lower body weight gain per molt cycle should be responsible for growth retardation in the "iron prawn," but not in the longer molt cycle. The results in this study provided fundamental information about the mechanism behind growth retardation in M. rosenbergii.

Environmental epigenetics and epigenetic inheritance in domestic farm animals

Epigenetics refers to molecular factors and processes around DNA that can affect genome activity and gene expression independent of DNA sequence. Epigenetic mechanisms drive developmental processes and have also been shown to be tied to disease development. Many epigenetic studies have been done using plants, rodent, and human models, but fewer have focused on domestic livestock species. The goal of this review is to present current epigenetic findings in livestock species (cattle, pigs, sheep and poultry). Much of this research examined epigenetic effects following exposure to toxicants, nutritional changes or infectious disease in those animals directly exposed, or in the offspring they produced. A limited number of studies in domestic animals have examined epigenetic transgenerational inheritance in the absence of continued exposures. One example used a porcine model to investigate the effect that feeding males a diet supplemented with micronutrients had on liver DNA methylation and muscle mass in grand-offspring (the transgenerational F2 generation). Further research into how epigenetic mechanisms affect the health and production traits of domestic livestock and their offspring is important to elucidate.

Cellular Mechanisms and Epigenetic Changes: Role of Nutrition in Livestock

In the context of physiologic responses that determine the growth, development, and health status of livestock, the role of epigenetics and the underlying cellular mechanisms it affects remain to be fully elucidated. Although recent work has provided evidence that maternal dietary energy level, carbohydrate type, or intestinal supply of methyl donors can elicit molecular changes in tissues of the embryo, fetus, or neonate, there are few data linking epigenetics with biochemical and physiologic outcomes. Therefore, efforts linking the epigenome with physiologic and developmental outcomes offer exciting opportunities for discoveries that can impact efficiency of nutrient use and well-being of livestock.

DNA methylation markers in obesity, metabolic syndrome, and weight loss

The fact that not all individuals exposed to the same environmental risk factors develop obesity supports the hypothesis of the existence of underlying genetic and epigenetic elements. There is suggestive evidence that environmental stimuli, such as dietary pattern, particularly during pregnancy and early life, but also in adult life, can induce changes in DNA methylation predisposing to obesity and related comorbidities. In this context, the DNA methylation marks of each individual have emerged not only as a promising tool for the prediction, screening, diagnosis, and prognosis of obesity and metabolic syndrome features, but also for the improvement of weight loss therapies in the context of precision nutrition. The main objectives in this field are to understand the mechanisms involved in transgenerational epigenetic inheritance, and featuring the nutritional and lifestyle factors implicated in the epigenetic modifications. Likewise, DNA methylation modulation caused by diet and environment may be a target for newer therapeutic strategies concerning the prevention and treatment of metabolic diseases.

Polyamine Metabolism and Gene Methylation in Conjunction with One-Carbon Metabolism

Recent investigations have revealed that changes in DNA methylation status play an important role in aging-associated pathologies and lifespan. The methylation of DNA is regulated by DNA methyltransferases (DNMT1, DNMT3a, and DNMT3b) in the presence of S-adenosylmethionine (SAM), which serves as a methyl group donor. Increased availability of SAM enhances DNMT activity, while its metabolites, S-adenosyl-l-homocysteine (SAH) and decarboxylated S-adenosylmethionine (dcSAM), act to inhibit DNMT activity. SAH, which is converted from SAM by adding a methyl group to cytosine residues in DNA, is an intermediate precursor of homocysteine. dcSAM, converted from SAM by the enzymatic activity of adenosylmethionine decarboxylase, provides an aminopropyl group to synthesize the polyamines spermine and spermidine. Increased homocysteine levels are a significant risk factor for the development of a wide range of conditions, including cardiovascular diseases. However, successful homocysteine-lowering treatment by vitamins (B6, B12, and folate) failed to improve these conditions. Long-term increased polyamine intake elevated blood spermine levels and inhibited aging-associated pathologies in mice and humans. Spermine reversed changes (increased dcSAM, decreased DNMT activity, aberrant DNA methylation, and proinflammatory status) induced by the inhibition of ornithine decarboxylase. The relation between polyamine metabolism, one-carbon metabolism, DNA methylation, and the biological mechanism of spermine-induced lifespan extension is discussed.