Current advances in proteomic analysis of (fatty) liver

Effects of feeding guanidinoacetic acid on oxidative status and creatine metabolism in broilers subjected to chronic cyclic heat stress in the finisher phase

Dietary guanidinoacetic acid (GAA) has been shown to affect creatine (Cr) metabolic pathways resulting in increased cellular Cr and hitherto broiler performances. Yet, the impact of dietary GAA on improving markers of oxidative status remains equivocal. A model of chronic cyclic heat stress, known to inflict oxidative stress, was employed to test the hypothesis that GAA could modify bird's oxidative status. A total of 720-day-old male Ross 308 broilers were allocated to 3 treatments: 0, 0.6 or 1.2 g/kg GAA was added to corn-SBM diets and fed for 39 d, with 12 replicates (20 birds each) per treatment. The chronic cyclic heat stress model (34°C with 50-60% RH for 7 h daily) was applied in the finisher phase (d 25-39). Samples from 1 bird per pen were taken on d 26 (acute heat stress) and d 39 (chronic heat stress). GAA and Cr in plasma were linearly increased by feeding GAA on either sampling day, illustrating efficient absorption and methylation, respectively. Energy metabolism in breast and heart muscle was greatly supported as visible by increased Cr and phosphocreatine: ATP, thus providing higher capacity for rapid ATP generation in cells. Glycogen stores in breast muscle were linearly elevated by incremental GAA, on d 26 only. More Cr seems to be directed to heart muscle as opposed to skeletal muscle during chronic heat stress as tissue Cr was higher in heart but lower in breast muscle on d 39 as opposed to d 26. The lipid peroxidation marker malondialdehyde, and the antioxidant enzymes superoxide dismutase and glutathione peroxidase showed no alterations by dietary GAA in plasma. Opposite to that, superoxide dismutase activity in breast muscle was linearly lowered when feeding GAA (trend on d 26, effect on d 39). Significant correlations between the assessed parameters and GAA inclusion were identified on d 26 and d 39 using principal component analysis. To conclude, beneficial performance in heat-stressed broilers by GAA is associated with enhanced muscle energy metabolism which indirectly may also support tolerance against oxidative stress.

Proteomic Analysis of Liver from Finishing Beef Cattle Supplemented with a Rumen-Protected B-Vitamin Blend and Hydroxy Trace Minerals

Simple Summary

Greater metabolic needs in high-producing beef cattle might lead to mineral and vitamin deficiency. Previous studies have shown the benefits of B-vitamin and trace mineral supplementation in animal performance of ruminants; however, little is known about the effects of supplementing finishing beef cattle with rumen-protected forms on the liver metabolism. Therefore, the aim of the present study was to determinate the impact of rumen-protected B-vitamin blend and hydroxy trace mineral supplementation on the hepatic proteome of finishing steers. This study reports the first evidence indicating that the supplementation of these micronutrients induces protein changes concerning oxidative metabolism and responses to oxidative stress in the liver tissue.

Abstract

Vitamin B and trace minerals are crucial molecular signals involved in many biological pathways; however, their bioavailability is compromised in high-producing ruminant animals. So far, studies have mainly focused on the effects of these micronutrients on animal performance, but their use in a rumen-protected form and their impact on liver metabolism in finishing beef cattle is poorly known. We used a shotgun proteomic approach combined with biological network analyses to assess the effects of a rumen-protected B-vitamin blend, as well as those of hydroxy trace minerals, on the hepatic proteome. A total of 20 non-castrated Nellore males with 353 ± 43 kg of initial body weight were randomly assigned to one of the following treatments: CTRL—inorganic trace minerals without supplementation of a protected vitamin B blend, or SUP—supplementation of hydroxy trace minerals and a protected vitamin B blend. All animals were fed the same amount of the experimental diet for 106 days, and liver biopsies were performed at the end of the experimental period. Supplemented animals showed 37 up-regulated proteins (p < 0.10), and the enrichment analysis revealed that these proteins were involved in protein folding (p = 0.04), mitochondrial respiratory chain complex I (p = 0.01) and IV (p = 0.01), chaperonin-containing T-complex 2 (p = 0.01), glutathione metabolism (p < 0.01), and other aspects linked to oxidative-stress responses. These results indicate that rumen-protected vitamin B and hydroxy trace mineral supplementation during the finishing phase alters the abundance of proteins associated with the electron transport chain and other oxidation–reduction pathways, boosting the production of reactive oxygen species, which appear to modulate proteins linked to oxidative-damage responses to maintain cellular homeostasis.

Partial or complete replacement of fishmeal with fermented soybean meal on growth performance, fecal composition, and meat quality in broilers

The current study was aimed to examine the effect of partial or complete replacement of fishmeal (FM) with fermented soybean meal (FSBM) on growth performance, fecal composition, and meat quality in broiler chickens. A total number of 240 one-day-old broiler chicks were randomly allotted into four dietary treatments with six replications and ten birds per one pen. Dietary treatments were followed as; 1) Diet incorporated with 4% FM without FSBM (Control), 2) Diet incorporated with 3% FM and 2% FSBM (FSBM2), 3) Diet incorporated with 2% FM and 3% FSBM (FSBM3) and 4) Diet incorporated with 4% FSBM without FM (FSBM4). Body weight and feed intake were recorded weekly for 35 days of the experimental period. Moreover, fecal samples were collected to evaluate moisture, ash, nitrogen, calcium and phosphorus content on day 21 post-hatch. On day 35, two birds were sacrificed from each pen to measure meat quality parameters and visceral organ weights. Results revealed that, no dietary treatment effect (p > 0.05) was observed either in both body weight or average daily gain of broilers within the entire experimental period while broilers fed FSBM2 increased (p < 0.05) average daily feed intake by 10.07% whereas FSBM4 improved (p < 0.05) feed efficiency ratio by 8.45% compared to birds fed other dietary treatments on day 7 post-hatch. Besides, birds fed FSBM3 obtained the improved (p < 0.05) feed conversion ratio over the birds fed control diet by 7.51% from hatch to day 35 post-hatch (1.60 vs. 1.73). Nevertheless, no difference (p > 0.05) was detected on visceral organ weight, proximate composition and physicochemical characteristics of meat while broilers offered FSBM4 obtained the lowest (p < 0.05) calcium and phosphorous in faces (2.27% and 1.21% respectively) over those offered control feed and other FSBM treatments. In conclusion, FSBM would be a better replacement for ousting FM partially or completely in broiler diet as it did not impair the growth performance and meat quality while reducing the calcium and phosphorous excretion in broilers for 35 days post-hatch.

Dietary supplementation with L-arginine and combinations of different oil sources beneficially regulates body fat deposition, lipogenic gene expression, growth performance and carcass yield in broiler chickens

Context Broiler meat with excessive of fat and saturated fatty acids content has serious health implication for consumers. The accumulation of abdominal fats in broiler chickens constitutes a loss of dietary energy and also reduces carcass yield. Oil rich in unsaturated fatty acids and l-arginine are effective for reducing fat deposition and improve meat quality. Aims The aim of this study was to examine the effects of supplementation of l-arginine (l-Arg) with four combinations of palm oil (PO) and sunflower oil (SO) on growth performance, carcass yield, fat deposition, lipogenic gene expression and blood lipid profile in broiler chickens. Methods A total of 180 1-day-old chicks (Cobb 500) were randomly assigned to five dietary treatments as: T1, 6% PO (control); T2, 6% PO + 0.25% l-Arg; T3, 4% PO + 2% SO + 0.25% l-Arg; T4, 2% PO + 4% SO + 0.25% l-Arg; and T5, 6% SO + 0.25% l-Arg. Key results Birds fed l-Arg and combinations of PO and SO had higher weight gain at starter and finisher period compared with the control. The carcass yield increased, and relative abdominal fat reduced in broiler fed with combinations of l-Arg and increased level of SO in the diet. The concentration of oleic, palmitoleic and total monounsaturated fatty acids in liver tissue decreased by addition of l-Arg in broiler diet. The palmitic and total saturated fatty acid decreased, and total unsaturated fatty acid and polyunsaturated fatty acids increased in liver tissue when PO replaced progressively by SO supplemented with l-Arg in the diet. The acetyl-CoA carboxylase , stearoyl-CoA desaturase and fatty acid synthetase gene expression tended to decrease by supplementation of l-Arg with an increased level of SO compared with control. Conclusion Supplementation with l-Arg and combination of PO and SO at the ratio of 4:2 could inhibit lipogenesis and subsequent lower abdominal fat deposition and enhance growth performance and carcass yield in broiler chickens. Implications Ratio of PO and SO, 4:2 with l-Arg supplementation in the dietary of broiler chickens can contribute to a better growth performance, lesser fat deposition and greater carcass yield.

Liver proteomics unravel the metabolic pathways related to Feed Efficiency in beef cattle

Improving nutrient utilization efficiency is essential for livestock, given the current scenario of increasing demand for animal protein and sustainable resource use. In this context, understanding the biology of feed efficiency (FE) in beef cattle allows the development of markers for identification and selection of best animals for animal production. Thus, 98 young Nellore bulls were evaluated for FE and at the end of the experiment liver samples from six High Feed Efficient (HFE) and six Low Feed Efficient (LFE) animals were collected for protein extraction, digestion and analysis by HPLC-MS/MS. Data were analyzed for differential abundant proteins (DAPs), protein networks, and functional enrichment. Serum endotoxin was also quantified. We found 42 DAPs and 3 protein networks significantly related to FE. The main pathways associated with FE were: microbial metabolism; biosynthesis of fatty acids, amino acids and vitamins; glycolysis/gluconeogenesis; xenobiotic metabolism and; antigen processing and presentation. Serum endotoxins were significantly higher in LFE animals supporting the results. Therefore, the findings presented here confirmed the altered hepatic metabolism and pronounced hepatic inflammation in LFE animals supporting that the increased bacterial load is at least in part responsible for the hepatic lesions and inflammation in LFE animals.

Proteomics and metabolomics characterizing the pathophysiology of adaptive reactions to the metabolic challenges during the transition from late pregnancy to early lactation in dairy cows

The transition from late pregnancy to early lactation is a critical period in a dairy cow's life due to the rapidly increasing drain of nutrients from the maternal organism towards the foetus and into colostrum and milk. In order to cope with the challenges of parturition and lactation, comprehensive adaptive reactions comprising the endocrine and the immune system need to be accomplished. There is high variation in this coping ability and both metabolic and infectious diseases, summarized as "production diseases", such as hypocalcaemia (milk fever), fatty liver syndrome, laminitis and ketosis, may occur and impact welfare, productive lifespan and economic outcomes. Proteomics and metabolomics have emerged as valuable techniques to characterize proteins and metabolite assets from tissue and biological fluids, such as milk, blood and urine. In this review we provide an overview on metabolic status and physiological changes during the transition period and the related production diseases in dairy cows, and summarize the state of art on proteomics and metabolomics of biological fluids and tissues involved in metabolic stress during the peripartum period. We also provide a current and prospective view of the application of the recent achievements generated by omics for biomarker discovery and their potential in diagnosis.

BIOLOGICAL SIGNIFICANCE

For high-yielding dairy cows there are several "occupational diseases" that occur mainly during the metabolic challenges related to the transition from pregnancy to lactation. Such diseases and their sequelae form a major concern for dairy production, and often lead to early culling of animals. Beside the economical perspective, metabolic stress may severely influence animal welfare. There is a multitude of studies about the metabolic backgrounds of such so called production diseases like ketosis, fatty liver, or hypocalcaemia, although the investigations aiming to assess the complexity of the pathophysiological reactions are largely focused on gene expression, i.e. transcriptomics. For extending the knowledge towards the proteome and the metabolome, the respective technologies are of increasing importance and can provide an overall view of how dairy cows react to metabolic stress, which is needed for an in-depth understanding of the molecular mechanisms of the related diseases. We herein review the current findings from studies applying proteomics and metabolomics to transition-related diseases, including fatty liver, ketosis, endometritis, hypocalcaemia and laminitis. For each disease, a brief overview of the up to date knowledge about its pathogenesis is provided, followed by an insight into the most recent achievements on the proteome and metabolome of tissues and biological fluids, such as blood serum and urine, highlighting potential biomarkers. We believe that this review would help readers to be become more familiar with the recent progresses of molecular background of transition-related diseases thus encouraging research in this field.

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.

Proteomics and the search for welfare and stress biomarkers in animal production in the one-health context

Stress and welfare are important factors in animal production in the context of growing production optimization and scrutiny by the general public.

Relationship between Proteolytic Activities and Cooking Loss Variability in Liver Issued from Force-Fed Mule Ducks

We investigated liver protease activities to better understand the mechanisms responsible for losses during the cooking of Mule ducks' fatty livers. Fatty livers of similar masses (520 g) were randomly selected among a large flock of overfed male Mule ducks and divided into two groups on the basis of their cooking loss rate, L+ (high cooking losses, 36%) and L- (low cooking losses, 21%). In addition to dry matter and total lipid contents, main hepatic protease (matrix metalloproteinase 2, cathepsins, and calpains) activities were measured by zymography. The results show that L+ samples present higher total relative proteolytic activity (6.15 ± 1.07 vs 4.46 ± 0.52 for L+ and L- samples, respectively) and total lipid content (61.0 ± 3.03% vs 53.7 ± 3.22% for L+ and L- samples, respectively) than L- samples. The results imply that proteases could be involved in the fragilization of the hepatocyte structure, resulting thus in higher cooking losses in L+ samples.

Proteomic profiling of liver from Elaphe taeniura, a common snake in eastern and southeastern Asia

Snake liver has been implicated in the adaptation of snakes to a variety of habitats. However, to date, there has been no systematic analysis of snake liver proteins. In this study, we undertook a proteomic analysis of liver from the colubrid snake Elaphe taeniura using a combination of two-dimensional electrophoresis (2-DE) and matrix-assisted laser desorption/ionization time of flightmass spectrometry (MALDI-TOF MS). We also constructed a local protein sequence database based on transcriptome sequencing to facilitate protein identification. Of the 268 protein spots revealed by 2-DE 109 gave positive MS signals, 84 of which were identified by searching the NCBInr, Swiss-Prot and local databases. The other 25 protein spots could not be identified, possibly because their transcripts were not be stable enough to be detected by transcriptome sequencing. GO analysis showed that most proteins may be involved in binding, catalysis, cellular processes and metabolic processes. Forty-two of the liver proteins identified were found in other reptiles and in amphibians. The findings of this study provide a good reference map of snake liver proteins that will be useful in molecular investigations of snake physiology and adaptation.

Proteomic analysis of liver mitochondria of apolipoprotein E knockout mice treated with metformin

Nonalcoholic fatty liver disease (NAFLD) is strongly associated with insulin resistance. Metformin, a widely known anti-diabetic drug, used for patients with type 2 diabetes mellitus, is also claimed to be useful in treatment of NAFLD. However, both the clinical efficacy and the putative mechanisms underlying the clinical effects of metformin in treating NAFLD are unclear. Adenosine monophosphate-activated protein kinase (AMPK), the primary molecular target for metformin, is a known regulator of mitochondrial function. Thus, we used a proteomic approach to investigate the effect of metformin on liver mitochondria of apolipoprotein E knockout (apoE(-/-)) mice, an animal model of NAFLD. Two-dimensional electrophoresis coupled with mass spectrometry was applied to study the changes in liver mitochondrial protein expression in 6-month old metformin-treated apoE(-/-) mice as compared to non-treated animals. Collectively, 25 differentially expressed proteins were indentified upon metformin treatment including proteins related to metabolism, oxidative stress and cellular respiration. The most up-regulated protein was glycine N-methyltransferase (GNMT) - an enzyme, whose deficiency was shown to be directly related to the development of NAFLD. Our results clearly point to the strong mitochondrial action of metformin in NAFLD. Up-regulation of GNMT may represent an important mechanism of beneficial action of metformin in NAFLD treatment.