Hepatic transcriptomic analysis reveals differential regulation of metabolic and immune pathways in three strains of chickens with distinct growth rates exposed to mixed parasite infections

During parasite infections, the liver may prioritise immune-related pathways over its metabolic functions. Intestinal infections caused by Ascaridia galli and Heterakis gallinarum impair feed intake, nutrient absorption, and weight gain. Histomonas meleagridis, vectored by H. gallinarum, can also damage liver tissues, potentially impairing liver functions. This study examined the hepatic gene expression in three strains of chickens: Ross-308 (R), Lohmann Brown Plus (LB), and Lohmann Dual (LD), 2 weeks after an experimental infection (n = 18) with both A. galli and H. gallinarum or kept as uninfected control (n = 12). Furthermore, H. gallinarum infection led to a co-infection with H. meleagridis. The mixed infections reduced feed intake and the average daily weight gain (P < 0.001). The infections also increased the plasma concentrations of alpha (1)-acid glycoprotein and the antibody titre against H. meleagridis (P = 0.049), with no strain differences (P > 0.05). For host molecular response, 1887 genes were differentially expressed in LD, while 275 and 25 genes were differentially expressed in R and LB, respectively. The up-regulated genes in R and LD were mostly related to inflammatory and adaptive immune responses, while down-regulated genes in LD were involved in metabolic pathways, including gluconeogenesis. Despite performance differences among the strains, worm burdens were similar, but hepatic molecular responses differed significantly. Moreover, there was an indication of a shift in hepatic functions towards immune-related pathways. We, therefore, conclude that the liver shifts its functions from metabolic to immune-related activities in chickens when challenged with mixed parasite species.

Exogenous Linoleic Acid Intervention Alters Hepatic Glucose Metabolism in an Avian Embryo Model

In the present study, developmental changes of gluconeogenesis and glycolysis in an avian model were measured, and then the intervention effects of in ovo feeding (IOF) linoleic acid (LA) on hepatic glucose metabolism were evaluated. In Experiment 1, thirty fertilized eggs were sampled on embryonic days (E) of 16, 19, 22, 25, 28, 31, and thirty newly-hatched ducklings at hatch (E34 and E35). In Experiment 2, a total of 120 fertilized eggs (60 eggs for each group) were injected into the yolk sac with PBS as the control group and LA as the IOF LA group on E25. Twelve eggs were selected for sample collection on E28 and E31. Serum contents of glucose, pyruvate, and lactate increased ( p < 0.05) linearly or quadratically from E16 to hatch, as well as hepatic glycogen and pyruvate contents. Hepatic mRNA expression related to energy homeostasis, gluconeogenesis, and glycolysis increased ( p < 0.05) in embryogenesis, and the plateau period was presented on E25–E31. IOF LA decreased ( p < 0.05) serum contents of glucose, triacylglycerol, cholesterol, and hepatic oleic acid, unsaturated fatty acids on E28, as well as the gene expression relative to gluconeogenesis. IOF LA increased ( p < 0.05) pyruvate content in serum and liver, and hepatic gene expression relative to glycolysis on E31. In summary, hepatic gluconeogenesis and glycolysis were enhanced to meet the increasing energy demands of embryonic development during E25 – hatch. Exogenous LA intervention on E25 could inhibit hepatic gluconeogenesis and enhance glycolysis during the later developmental period, disrupting glucose embryonic homeostasis and energy status.

Alleviation of infectious-bursal-disease-virus-induced bursal injury by betaine is associated with DNA methylation in IL-6 and interferon regulatory factor 7 promoter

Infectious bursal disease virus (IBDV) often infects young chickens and causes severe immunosuppression and inflammatory injury. Betaine is an antiviral and anti-inflammatory ingredient that may exert functions through epigenetic regulation. However, the effects of betaine on an IBDV-induced bursal injury and their underlying mechanisms have not been investigated. In this study, betaine was supplemented to the drinking water of newly hatched commercial broilers for 3 wk. Afterward, the chickens were infected with the IBDV. After 5 D of infection, the bursal lesions were examined. The mRNA expression levels of IBDV VP2 gene, pro-inflammatory cytokines, and interferons were detected. Furthermore, the 5-methylcytosine level of the CpG island in the promoter region of IL-6 and interferon regulatory factor 7 (IRF7) were determined. The IBDV induced the depletion of lymphocytes and inflammation in the bursal follicles. IBDV infection considerably elevated the mRNA levels of VP2, IL-6, types I (IFNα and IFNβ) and II (IFNγ) interferons, and IRF7. The CpG island methylation in the promoter regions of IL-6 and IRF7 were substantially decreased after IBDV infection. Betaine administration attenuated the IBDV-induced bursal lesions. Meanwhile, the IBDV-induced mRNA expression levels of IL-6, IFNβ, and IRF7 were suppressed by betaine consumption. Furthermore, the hypomethylation effects of IBDV infection to the promoter regions of IL-6 and IRF7 genes were eliminated and relieved by betaine administration. Our results indicated that the IBDV-induced expression levels of IL-6 and IRF7 genes are associated with the suppression of methylation in the promoter region. Betaine administration through drinking water may alleviate the IBDV-induced bursal injury via epigenetic regulation.

Structure and age-dependent development of the turkey liver: a comparative study of a highly selected meat-type and a wild-type turkey line

In this study the macroscopic and microscopic structure of the liver of a fast growing, meat-type turkey line (British United turkeys BUT Big 6, n=25) and a wild-type turkey line (Wild Canadian turkey, n=48) were compared at the age of 4, 8, 12, 16, and 20 wk. Because the growth plates of long bones were still detectable in the 20-week-old wild-type turkeys, indicating immaturity, a group of 8 wild-type turkeys at the age of 24 wk was included in the original scope of the study. Over the term of the study, the body and liver weights of birds from the meat-type turkey line increased at a faster rate than those of the wild-type turkey line. However, the relative liver weight of the meat-type turkeys declined (from 2.7 to 0.9%) to a greater extent than that of the wild-type turkeys (from 2.8 to 1.9%), suggesting a mismatch in development between muscle weights and liver weights of the meat-type turkeys. Signs of high levels of fat storage in the liver were detected in both lines but were greater in the wild-type turkey line, suggesting a better feed conversion by the extreme-genotype birds i.e., meat-type birds. For the first time, this study presents morphologic data on the structure and arrangement of the lymphatic tissue within the healthy turkey liver, describing two different types of lymphatic aggregations within the liver parenchyma, i.e., aggregations with and without fibrous capsules. Despite differences during development, both adult meat-type and adult wild-type turkeys had similar numbers of lymphatic aggregations.

Transcriptomic Analysis of Ovaries from Pigs with High And Low Litter Size

Litter size is one of the most important economic traits for pig production as it is directly related to the production efficiency. Litter size is affected by interactions between multiple genes and the environment. While recent studies have identified some genes associated with prolificacy in pigs, transcriptomic studies of specific genes affecting litter size in porcine ovaries are rare. In order to identify candidate genes associated with litter size in swine, we assessed gene expression differences between the ovaries of Yorkshire pigs with extremely high and low litter sizes using the RNA-Seq method. A total of 1 243 differentially expressed genes were identified: 897 genes were upregulated and 346 genes were downregulated in high litter size ovary samples compared with low litter size ovary samples. A large number of these genes related to steroid hormone regulation in animal ovaries, including 59 Gene Ontology terms and 27 Kyoto Encyclopedia of Genes and Genomes pathways involved in steroid biosynthesis and ovarian steroidogenesis. From these differentially expressed genes, we identified a total of 11 genes using a bioinformatics screen that may be associated with high litter size in Yorkshire pigs. These results provide a list of new candidate genes for porcine litter size and prolificacy to be further investigated.

Long-term metabolic alterations in a febrile seizure model

OBJECTIVE

Febrile seizures (FS) are the most common neurological disease in infancy and early childhood, it can lead to metabolic changes and have long-term health implications. Aim of this study was to investigate the long-term effects of FS on metabolism.

METHODS

We measured certain metabolic parameters in hyperthermia-prone (HP) rats, which were developed using a selective breeding process and showed a lower seizure threshold than wild-type (WT) rats. Body weight, body length, abdominal circumference and the levels of fasting blood glucose, serum triglyceride, and total cholesterol concentrations were analyzed. The mRNA expression of genes involved in glucose and lipid metabolism was determined by qPCR and the histone methylation level in the liver was determined by western blot.

RESULTS

We found that the body weight of the HP rats was significantly lower than that of the WT rats. Similarly, the fasting blood glucose and serum triglyceride levels were lower in the HP group compared with the WT group. These changes were accompanied by increased mRNA expression of genes such as phosphoenolpyruvate carboxykinase (PEPCK) and carnitine palmitoyl transferase-1 (CPT-1), but not peroxisome proliferator-activated receptor α (PPARα). We also found tri-methylation of histone 3 at Lys9 and Lys27 was decreased in the HP group.

CONCLUSIONS

These data may suggest an underlying mechanism by which FS have a long-term effect on energy metabolism via histone methylation.