Adipogenic genes expression in relation to hepatic steatosis in the liver of two duck species

Identification of alternative splicing events related to fatty liver formation in duck using full-length transcripts

BACKGROUND

Non-alcoholic fatty liver disease (NAFLD) is one of most common diseases in the world. Recently, alternative splicing (AS) has been reported to play a key role in NAFLD processes in mammals. Ducks can quickly form fatty liver similar to human NAFLD after overfeeding and restore to normal liver in a short time, suggesting that ducks are an excellent model to unravel molecular mechanisms of lipid metabolism for NAFLD. However, how alternative splicing events (ASEs) affect the fatty liver process in ducks is still unclear.

RESULTS

Here we identify 126,277 unique transcripts in liver tissue from an overfed duck (77,237 total transcripts) and its sibling control (69,618 total transcripts). We combined these full-length transcripts with Illumina RNA-seq data from five pairs of overfed ducks and control individuals. Full-length transcript sequencing provided us with structural information of transcripts and Illumina RNA-seq data reveals the expressional profile of each transcript. We found, among these unique transcripts, 30,618 were lncRNAs and 1,744 transcripts including 155 lncRNAs and 1,589 coding transcripts showed significantly differential expression in liver tissues between overfed ducks and control individuals. We also detected 27,317 ASEs and 142 of them showed significant relative abundance changes in ducks under different feeding conditions. Full-length transcript profiles together with Illumina RNA-seq data demonstrated that 10 genes involving in lipid metabolism had ASEs with significantly differential abundance in normally fed (control) and overfed ducks. Among these genes, protein products of five genes (CYP4F22, BTN, GSTA2, ADH5, and DHRS2 genes) were changed by ASEs.

CONCLUSIONS

This study presents an example of how to identify ASEs related to important biological processes, such as fatty liver formation, using full-length transcripts alongside Illumina RNA-seq data. Based on these data, we screened out ASEs of lipid-metabolism related genes which might respond to overfeeding. Our future ability to explore the function of genes showing AS differences between overfed ducks and their sibling controls, using genetic manipulations and co-evolutionary studies, will certainly extend our knowledge of genes related to the non-pathogenic fatty liver process.

Impacts of Embryonic Thermal Programming on the Expression of Genes Involved in Foie gras Production in Mule Ducks

Embryonic thermal programming has been shown to improve foie gras production in overfed mule ducks. However, the mechanisms at the origin of this programming have not yet been characterized. In this study, we investigated the effect of embryonic thermal manipulation (+1°C, 16 h/24 h from embryonic (E) day 13 to E27) on the hepatic expression of genes involved in lipid and carbohydrate metabolisms, stress, cell proliferation and thyroid hormone pathways at the end of thermal manipulation and before and after overfeeding (OF) in mule ducks. Gene expression analyses were performed by classic or high throughput real-time qPCR. First, we confirmed well-known results with strong impact of OF on the expression of genes involved in lipid and carbohydrates metabolisms. Then we observed an impact of OF on the hepatic expression of genes involved in the thyroid pathway, stress and cell proliferation. Only a small number of genes showed modulation of expression related to thermal programming at the time of OF, and only one was also impacted at the end of the thermal manipulation. For the first time, we explored the molecular mechanisms of embryonic thermal programming from the end of heat treatment to the programmed adult phenotype with optimized liver metabolism.

Sex- and Developmental Stage-Related Differences in the Hepatic Transcriptome of Japanese Quail (Coturnix japonica) Exposed to 17β-Trenbolone

Endocrine-disrupting chemicals can cause transcriptomic changes that may disrupt biological processes associated with reproductive function including metabolism, transport, and cell growth. We investigated effects from in ovo and dietary exposure to 17β-trenbolone (at 0, 1, and 10 ppm) on the Japanese quail (Coturnix japonica) hepatic transcriptome. Our objectives were to identify differentially expressed hepatic genes, assess perturbations of biological pathways, and examine sex- and developmental stage-related differences. The number of significantly differentially expressed genes was higher in embryos than in adults. Male embryos exhibited greater differential gene expression than female embryos, whereas in adults, males and females exhibited similar numbers of differentially expressed genes (>2-fold). Vitellogenin and apovitellenin-1 were up-regulated in male adults exposed to 10 ppm 17β-trenbolone, and these birds also exhibited indications of immunomodulation. Functional grouping of differentially expressed genes identified processes including metabolism and transport of biomolecules, enzyme activity, and extracellular matrix interactions. Pathway enrichment analyses identified as perturbed peroxisome proliferator-activated receptor pathway, cardiac muscle contraction, gluconeogenesis, growth factor signaling, focal adhesion, and bile acid biosynthesis. One of the primary uses of 17β-trenbolone is that of a growth promoter, and these results identify effects on mechanistic pathways related to steroidogenesis, cell proliferation, differentiation, growth, and metabolism of lipids and proteins. Environ Toxicol Chem 2021;40:2559-2570. © 2021 SETAC. This article has been contributed to by US Government employees and their work is in the public domain in the USA.

Amidation-Modified Apelin-13 Regulates PPARγ and Perilipin to Inhibit Adipogenic Differentiation and Promote Lipolysis

With the adjustment of human diet and lifestyle changes, the prevalence of obesity is increasing year by year. Obesity is closely related to the excessive accumulation of white adipose tissue (WAT), which can synthesize and secrete a variety of adipokines. Apelin is a biologically active peptide in the adipokines family. Past studies have shown that apelin plays an important regulatory role in the pathogenesis and pathophysiology of diseases such as the cardiovascular system, respiratory system, digestive system, nervous system, and endocrine system. Apelin is also closely related to diabetes and obesity. Therefore, we anticipate that apelin-13 has an effect on lipometabolism and intend to explore the effect of apelin-13 on lipometabolism at the cellular and animal levels. In in vitro experiments, amidation-modified apelin-13 can significantly reduce the lipid content; TG content; and the expression of PPARγ, perilipin mRNA, and protein in adipocytes. Animal experiments also show that amidation modification apelin-13 can improve the abnormal biochemical indicators of diet-induced obesity (DOI) rats and can reduce the average diameter of adipocytes in adipose tissue, the concentration of glycerol, and the expression of PPARγ and perilipin mRNA and protein. Our results show that apelin-13 can affect the metabolism of adipose tissue, inhibit adipogenic differentiation of adipocytes, promote lipolysis, and thereby improve obesity. The mechanism may be regulating the expression of PPARγ to inhibit adipogenic differentiation and regulating the expression of perilipin to promote lipolysis. This study helps us understand the role of apelin-13 in adipose tissue and provide a basis for the elucidation of the regulation mechanism of lipometabolism and the development of antiobesity drugs.

Development of a relevant strategy using de novo transcriptome assembly method for transcriptome comparisons between Muscovy and common duck species and their reciprocal inter-specific mule and hinny hybrids fed ad libitum and overfed

Background

Common Pekin and Muscovy ducks and their intergeneric hinny and mule hybrids have different abilities for fatty liver production. RNA-Seq analyses from the liver of these different genetic types fed ad libitum or overfed would help to identify genes with different response to overfeeding between them. However RNA-seq analyses from different species and comparison is challenging. The goal of this study was develop a relevant strategy for transcriptome analysis and comparison between different species.

Results

Transcriptomes were first assembled with a reference-based approach. Important mapping biases were observed when heterologous mapping were conducted on common duck reference genome, suggesting that this reference-based strategy was not suited to compare the four different genetic types. De novo transcriptome assemblies were then performed using Trinity and Oases. Assemblies of transcriptomes were not relevant when more than a single genetic type was considered. Finally, single genetic type transcriptomes were assembled with DRAP in a mega-transcriptome. No bias was observed when reads from the different genetic types were mapped on this mega-transcriptome and differences in gene expression between the four genetic types could be identified.

Conclusions

Analyses using both reference-based and de novo transcriptome assemblies point out a good performance of the de novo approach for the analysis of gene expression in different species. It also allowed the identification of differences in responses to overfeeding between Pekin and Muscovy ducks and hinny and mule hybrids.

Antioxidant Status and Liver Function of Young Turkeys Receiving a Diet with Full-Fat Insect Meal from Hermetia illucens

We hypothesized that full-fat insect meal from Hermetia illucens (HI) larvae can be an acceptable source of protein and energy in the diet of young turkeys, in an amount adapted to the nutritional needs of these birds, and at the same time can improve their antioxidant status and metabolism. The turkeys were fed a control diet (HI₀) without the insect meal, and three diets with increasing HI content of 5%, 10% and 15% (treatments HI₅, HI₁₀ and HI₁₅, respectively). The use of 10% or 15% HI in the diet of young turkeys, while beneficially raising levels of P, Fe and Hb, has a negative effect on lipid metabolism, increasing TC levels, lipid oxidation, and fat deposition in the liver. The inclusion of 5% HI in the diet of young turkeys has no adverse effect on the lipid status and histology of the liver, but it does not improve antioxidant status. To conclude, the level of HI meal in the diet of turkeys should not exceed 5%. However, as similar studies on turkeys have not yet been published, overly general conclusions should not be drawn from the results of the present study, and further research is necessary.

Effects of atmospheric ammonia on the production performance, serum biochemical indices, and liver RNA-seq data of laying ducks

1. Ammonia is a toxic gas and an air pollutant of great concern. The effects of ammonia-induced damage in ducks are rarely reported. 2. A total of 176 laying ducks were randomly allocated to one of two groups with four replicates and were exposed to ammonia at 5 ± 5 ppm (low ammonia, LA) or 75 ± 5 ppm (high ammonia, HA), respectively, for 30 days. 3. The results showed that atmospheric ammonia exposure significantly decreased body weight and laying performance (P < 0.05). It significantly changed serum biochemical indices by increasing alanine aminotransferase and aspartate aminotransferase (P < 0.05), and decreasing superoxide dismutase activity (P < 0.05). Haematoxylin and eosin staining of hepatocytes revealed severe fatty degeneration. Results of RNA-seq analyses revealed that eight genes were significantly up-regulated in the HA group, which were involved in catalytic activity, single-organism metabolic processes, oxidation-reduction processes, and carbohydrate metabolic processes. 4. These results indicated that atmospheric ammonia exposure reduced production performance, affected serum biochemical indices, and led to severe fatty degeneration in the liver of laying ducks. Differentially expressed genes in liver indicated that there were effects of ammonia exposure on the metabolism and detoxification capabilities in ducks.

Kinetic study of the expression of genes related to hepatic steatosis, glucose and lipid metabolism, and cellular stress during overfeeding in mule ducks

Induced by overfeeding, hepatic steatosis is a process exploited for the "foie gras" production in mule ducks. To better understand the mechanisms underlying its development, the physiological responses of mule ducks overfed with corn for a duration of 11 days were analyzed. A kinetic analysis of glucose and lipid metabolism and cell protection mechanisms was performed on 96 male mule ducks during overfeeding with three sampling times (after the 4th, the 12th, and the 22nd meal). Gene expression and protein analysis realized on the liver, muscle, and abdominal fat showed an activation of a cholesterol biosynthetic pathway during the complete overfeeding period mainly in livers with significant correlations between its weight and its cholesterolemia (r = 0.88; P < 0.0001) and between the liver weight and the hmgcr and soat1 expression (r = 0.4, P < 0.0001 and r = 0.67; P < 0.0001, respectively). Results also revealed an activation of insulin and amino acid cells signaling a pathway suggesting that ducks boost insulin sensitivity to raise glucose uptake and use via glycolysis and lipogenesis. Cellular stress analysis revealed an upregulation of key autophagy-related gene expression atg8 and sqstm1(P < 0.0001) during the complete overfeeding period, mainly in the liver, in contrast to an induction of cyp2e1(P < 0.0001), suggesting that autophagy could be suppressed during steatosis development. This study has highlighted different mechanisms enabling mule ducks to efficiently handle the starch overload by keeping its liver in a nonpathological state. Moreover, it has revealed potential biomarker candidates of hepatic steatosis as plasma cholesterol for the liver weight.

Effects of the Dietary Inclusion of Partially Defatted Black Soldier Fly (Hermetia illucens) Meal on the Blood Chemistry and Tissue (Spleen, Liver, Thymus, and Bursa of Fabricius) Histology of Muscovy Ducks (Cairina moschata domestica)

Simple Summary

Insects represent a promising feed ingredient for poultry diets, as an alternative to conventional feedstuffs. Black soldier fly (BSF; Hermetia illucens) larvae are processed to obtain two main products: the protein and fat fractions. The possible utilization of BSF defatted meal in Muscovy duck (Cairina moschata domestica) diets has been poorly investigated. However, its effect on in vivo and post-mortem traits, which are extremely important for animal welfare, has not yet been investigated. Therefore, the present study has evaluated the effect of 0%, 3%, 6%, and 9% dietary BSF meal replacement on the in vivo haematological parameters and on the post-mortem organ traits. Overall, the obtained results are encouraging as increasing dietary BSF meal did not impair the growth performance or the haematological traits. Furthermore, both the liver and renal function were unaffected or even improved. The antioxidant picture appeared improved and the histological traits were not influenced by the dietary inclusion of BSF meal. From a productive and biological point of view, the dietary replacement up to 9% of BSF meal in Muscovy duck diet is feasible and BSF meal could represent a promising feed ingredient.

Abstract

The present study has evaluated the effects of dietary partially-defatted black soldier fly (BSF; Hermetia illucens L.) larva meal on the blood parameters, antioxidant status, and histological features of the organs of broiler ducks. A total of 192 female 3-days of age Muscovy ducklings (Cairina moschata domestica) were divided into four dietary treatments (0%, 3%, 6%, and 9% BSF meal inclusion; 6 pens/treatment, 8 birds/pen). A total of 12 ducks/treatment (2 birds/pen) were slaughtered at 51 days of age and blood samples were collected to evaluate the haematological traits, serum protein, lipid and minerals, liver and renal function serum enzymes, plasma oxidative enzymes, and metabolites. Liver, spleen, thymus, and bursa of Fabricius samples were submitted to histopathological investigations. Between the serum and plasma traits, triglycerides, cholesterol, creatinine, alkaline phosphatase, magnesium, malondialdehyde, and nitrotyrosine showed a linear decrease for increasing amounts of dietary BSF meal (p <0.01); in contrast, the serum iron concentration showed a linear increase (p <0.01). Moreover, the histopathological findings were not significantly affected by the dietary BSF larva meal inclusion. The results showed that the inclusion of up to 9% BSF larva meal represents a promising feed ingredient for Muscovy duck nutrition, and improved blood traits were observed.

RNA-seq analysis of hepatic gene expression of common Pekin, Muscovy, mule and hinny ducks fed ad libitum or overfed

Background

Duck species are known to have different susceptibility to fatty liver production in response to overfeeding. In order to better describe mechanisms involved in the development of hepatic steatosis and differences between species, transcriptome analyses were conducted on RNAs extracted from the livers of Pekin and Muscovy duck species and of their reciprocal hybrids, Mule and Hinny ducks fed ad libitum or overfed to identify differentially expressed genes and associated functions.

Results

After extraction from the liver of ducks from the four genetic types, RNAs were sequenced and sequencing data were analyzed. Hierarchic clustering and principal component analyses of genes expression levels indicated that differences between individuals lie primarily in feeding effect, differences between genetic types being less important. However, Muscovy ducks fed ad libitum and overfed were clustered together. Interestingly, Hinny and Mule hybrid ducks could not be differentiated from each other, according to feeding. Many genes with expression differences between overfed and ad libitum fed ducks were identified in each genetic type. Functional annotation analyses of these differentially expressed genes highlighted some expected functions (carbohydrate and lipid metabolisms) but also some unexpected ones (cell proliferation and immunity).

Conclusions

These analyses evidence differences in response to overfeeding between different genetic types and help to better characterize functions involved in hepatic steatosis in ducks.

Electronic supplementary material

The online version of this article (10.1186/s12864-018-5415-1) contains supplementary material, which is available to authorized users.