A Serum Metabolic Profiling Analysis During the Formation of Fatty Liver in Landes Geese via GC-TOF/MS

Advance in the application of metabolomics technology in poultry

Metabolomics is a science that takes small molecular metabolites in organisms as the research object and determines the dynamic changes of metabolites at the overall level through a variety of modern analytical techniques. At present, metabolomics technology has been widely used in biological significance interpretation, food safety and quality, breeding, disease diagnosis, functional compound identification, and other fields. Its application in poultry science has also become the focus of widespread attention. With the sustainable development of analytical techniques, metabolomics has great potential in the application of poultry science. In this paper, the research progress of metabolomics in poultry growth and development, genetics and breeding, egg quality, meat quality, and disease is reviewed and concluded, which is expected to provide scientific ideas for the research of metabolomics in poultry.

Multi-omics reveals goose fatty liver formation from metabolic reprogramming

To comprehensively provide insight into goose fatty liver formation, we performed an integrative analysis of the liver transcriptome, lipidome, and amino acid metabolome, as well as peripheral adipose tissue transcriptome analysis using samples collected from the overfed geese and normally fed geese. Transcriptome analysis showed that liver metabolism pathways were mainly enriched in glucolipid metabolism, amino acid metabolism, inflammation response, and cell cycle; peripheral adipose tissue and the liver cooperatively regulated liver lipid accumulation during overfeeding. Liver lipidome patterns obviously changed after overfeeding, and 157 different lipids were yielded. In the liver amino acid metabolome, the level of Lys increased after overfeeding. In summary, this is the first study describing goose fatty liver formation from an integrative analysis of transcriptome, lipidome, and amino acid metabolome, which will provide a whole new dimension to understanding the mechanism of goose fatty liver formation.

Metagenomic reconstructions of caecal microbiome in Landes, Roman and Zhedong White geese

1. The caecal microbiota in geese play a crucial role in determining the host's health, disease status and behaviour, as evidenced by extensive epidemiological data. The present investigation conducted 10× metagenomic sequencing of caecal content samples obtained from three distinct goose species, namely Landes geese, Roman geese and Zhedong White geese (n = 5), to explore the contribution of the gut microbiome to carbohydrate metabolism.2. In total, 337GB of Illumina data were generated, which identified 1,048,575 complete genes and construction of 331 metagenomic bins, encompassing 78 species from nine phyla. Firmicutes, Bacteroidetes, Actinobacteria, Proteobacteria and Bacteria were identified as the dominant phyla while Prevotella, Bacteroides, Streptococcus, and Subdoligranulum were the most abundant genera in the caecum of geese.3. The genes were allocated to 375 pathways using the Kyoto Encyclopedia of Genes and Genome (KEGG) analysis. The most abundant classes in the caecum of geese were confirmed to be glycoside hydrolases (GHs), glycosyl transferases (GTs), as identified through the carbohydrate-active enzyme (CAZyme) database mapping. Subdoligranulum variabile and Mediterraneibacter glycyrrhizinilyticus were discovered to potentially facilitate carbohydrate digestion in geese.4. Notwithstanding, further investigation and validation are required to establish a connection between these species and CAZymes. Based on binning analysis, Mediterraneibacter glycyrrhizinilyticus and Ruminococcus sp. CAG:177 are potential species in LD geese that contribute to the production of fatty liver.

Small molecule metabolites: discovery of biomarkers and therapeutic targets

Metabolic abnormalities lead to the dysfunction of metabolic pathways and metabolite accumulation or deficiency which is well-recognized hallmarks of diseases. Metabolite signatures that have close proximity to subject's phenotypic informative dimension, are useful for predicting diagnosis and prognosis of diseases as well as monitoring treatments. The lack of early biomarkers could lead to poor diagnosis and serious outcomes. Therefore, noninvasive diagnosis and monitoring methods with high specificity and selectivity are desperately needed. Small molecule metabolites-based metabolomics has become a specialized tool for metabolic biomarker and pathway analysis, for revealing possible mechanisms of human various diseases and deciphering therapeutic potentials. It could help identify functional biomarkers related to phenotypic variation and delineate biochemical pathways changes as early indicators of pathological dysfunction and damage prior to disease development. Recently, scientists have established a large number of metabolic profiles to reveal the underlying mechanisms and metabolic networks for therapeutic target exploration in biomedicine. This review summarized the metabolic analysis on the potential value of small-molecule candidate metabolites as biomarkers with clinical events, which may lead to better diagnosis, prognosis, drug screening and treatment. We also discuss challenges that need to be addressed to fuel the next wave of breakthroughs.

The physiology of experimental overfeeding in animals

BACKGROUND

Body weight is defended by strong homeostatic forces. Several of the key biological mechanisms that counteract weight loss have been unraveled over the last decades. In contrast, the mechanisms that protect body weight and fat mass from becoming too high remain largely unknown. Understanding this aspect of energy balance regulation holds great promise for curbing the obesity epidemic. Decoding the physiological and molecular pathways that defend against weight gain can be achieved by an intervention referred to as 'experimental overfeeding'.

SCOPE OF THE REVIEW

In this review, we define experimental overfeeding and summarize the studies that have been conducted on animals. This field of research shows that experimental overfeeding induces a potent and prolonged hypophagic response that seems to be conserved across species and mediated by unidentified endocrine factors. In addition, the literature shows that experimental overfeeding can be used to model the development of non-alcoholic steatohepatitis and that forced intragastric infusion of surplus calories lowers survival from infections. Finally, we highlight studies indicating that experimental overfeeding can be employed to study the transgenerational effects of a positive energy balance and how dietary composition and macronutrient content might impact energy homeostasis and obesity development in animals.

MAJOR CONCLUSIONS

Experimental overfeeding of animals is a powerful yet underappreciated method to investigate the defense mechanisms against weight gain. This intervention also represents an alternative approach for studying the pathophysiology of metabolic liver diseases and the links between energy balance and infection biology. Future research in this field could help uncover why humans respond differently to an obesogenic environment and reveal novel pathways with therapeutic potential against obesity and cardiometabolic disorders.

Impacts of Circadian Gene Period2 Knockout on Intestinal Metabolism and Hepatic Antioxidant and Inflammation State in Mice

The period circadian regulator 2 (Per2) gene is important for the modulations of rhythmic homeostasis in the gut and liver; disruption will cause metabolic diseases, such as obesity, diabetes, and fatty liver. Herein, we investigated the alterations in intestinal metabolic and hepatic functions in Per2 knockout (Per2^−/−, KO) and wild-type (Per2^+/+, WT) mice. Growth indices, intestinal metabolomics, hepatic circadian rhythms, lipid metabolism, inflammation-related genes, antioxidant capacity, and transcriptome sequencing were performed after euthanasia. Data indicated that KO decreased the intestinal concentrations of amino acids such as γ-aminobutyric acid, aspartic acid, glycine, L-allothreonine, methionine, proline, serine, and valine while it increased the concentrations of carbohydrates such as cellobiose, D-talose, fucose, lyxose, and xylose compared with WT. Moreover, the imbalance of intestinal metabolism further seemed to induce liver dysfunction. Data indicated that Per2 knockout altered the expression of hepatic circadian rhythm genes, such as Clock, Bmal1, Per1, Per3, Cry1, and Cry2. KO also induced hepatic lipid metabolism, because of the increase of liver index and serum concentrations of low-density lipoprotein, and the upregulated expression of Pparα, Cyp7a1, and Cpt1. In addition, KO improved hepatic antioxidant capacity due to the increase activities of SOD and GSH-Px and the decrease in concentrations of MDA. Lastly, KO increased the relative expression levels of hepatic inflammation-related genes, such as Il-1β, Il-6, Tnf-α, Myd88, and Nf-κB p65, which may potentially lead to hepatic inflammation. Overall, Per2 knockout induces gut metabolic dysregulation and may potentially trigger alterations in hepatic antioxidant and inflammation responses.

Metabolic Profiling Analysis of Liver in Landes Geese During the Formation of Fatty Liver via GC-TOF/MS

Fatty liver production results from the process of overfeeding geese, inducing a dramatic increase in de novo liver lipogenesis. To investigate the alteration of liver metabolites by overfeeding, especially lipid metabolites, and the potential pathways causing these changes, 60 Landes geese at 65 days old were raised in three groups with 20 geese per group, namely, the D0 group (free from gavage), D7 group (overfeeding for 7 days), and D25 group (overfeeding for 25 days). At 90 days old, segments of liver tissue were collected from 10 geese of each group for gas chromatography time-of-flight/mass spectrometry (GC-TOF/MS) analysis. A large number of endogenous molecules in the livers of geese were altered dramatically by overfeeding. In the livers of overfed geese, the level of oleic acid was observed to continuously increase, while the levels of phenylalanine, methyl phosphate, sulfuric acid, and 3-hydroxybenzaldehyde were decreased. The most significantly different metabolites were enriched in amino acid, lipid, and nucleotide metabolism pathways. The present study further supports the idea that Landes geese efficiently produce fatty liver, and potential biomarkers and disturbed metabolic pathways during the process of forming fatty liver were identified. In conclusion, this study might provide some insights into the underlying mechanisms of fatty liver formation.