Molecular and Integrative Physiology of Intestinal Peptide Transport

Impact of Nanoencapsulated Rosemary Essential Oil as a Novel Feed Additive on Growth Performance, Nutrient Utilization, Carcass Traits, Meat Quality and Gene Expression of Broiler Chicken

This study evaluated the effect of free and nanoencapsulated rosemary essential oil (REO) as an antibiotic alternative in broiler diets on growth performance, nutrient digestibility, carcass traits, meat quality and gene expression. Four hundred twenty day-old commercial broiler chicks (VENCOBB) were randomly allocated to seven dietary treatments, each having four replicates of fifteen chicks. The dietary treatments comprised control (CON) fed a basal diet only, AB (basal diet + 10 mg enramycin/kg), CS (basal diet + 150 mg chitosan nanoparticles/kg), REOF100 and REOF200 (basal diet + 100 mg and 200 mg free REO/kg, respectively), and REON100 and REON200 (basal diet + 100 mg and 200 mg nanoencapsulated REO/kg, respectively). Overall (7-42 d), REON200 showed the highest (p < 0.001) body weight gain (1899 g/bird) and CON had the lowest gain (1742 g/bird), while the CS, REOF100 and REOF200 groups had a similar gain, but lower than that of the AB and REON100 groups. Feed intake was not affected by dietary treatments. Overall, the feed efficiency increased (p = 0.001) by 8.47% in the REON200 group and 6.21% in the AB and REON100 groups compared with the CON. Supplementation of REO improved (p < 0.05) dry matter and crude protein digestibility, with the highest values in REON100 and REON200. Ether extract, crude fiber, calcium and phosphorus digestibility values showed no difference among the groups. The dressing, breast, thigh % increased (p < 0.05) and abdominal fat % decreased (p < 0.001) more in the REON200 group than with other treatments and CON. In breast meat quality, water holding capacity and extract reserve volume increased (p < 0.05) while drip loss and cholesterol content decreased (p < 0.05) in REON100 and REON200. No change was observed in the breast meat color among dietary treatments and CON. The REON100 and REON200 groups had reduced (p < 0.05) meat lipid peroxidation as depicted by the decreased levels of TBARS, free fatty acids and peroxide value compared to other treatments and CON. The expression of the Mucin 2, PepT1 and IL-10 genes was upregulated (p < 0.001) and TNF-α downregulated (p < 0.001) by dietary addition of REO particularly in the nanoencapsulated form compared with the CON. In conclusion, nanoencapsulated REO, especially at 200 mg/kg diet, showed promising results as an antibiotic alternative in improving the performance, nutrient digestibility, carcass traits, meat quality and upregulation of growth and anti-inflammatory genes.

Genome-wide identification of nitrate transporter 1/peptide transporter family (NPF) induced by arbuscular mycorrhiza in the maize genome

The Transporter 1/Peptide Transporter Family (NPF) is essential for the uptake and transport of nitrate nitrogen. Significant increases in nitrogen have been increasingly reported for many mycorrhizal plants, but there are few reports on maize. Here, we have identified the maize NPF family and screened for arbuscular mycorrhiza fungi (AMF) induced NPFs. In this study, a systematic analysis of the maize NPF gene family was performed. A total of 82 NPF genes were identified in maize. ZmNPF4.5 was strongly induced by AMF in both low and high nitrogen. Lotus japonicus hairy root-induced transformation experiments showed that ZmNPF4.5 promoter-driven GUS activity was restricted to cells containing tufts. Yeast backfill experiments indicate that ZmNPF4.5 functions in nitrate uptake. Therefore, we speculate that ZmNPF4.5 is a key gene for nitrate-nitrogen uptake in maize through the mycorrhizal pathway. This is a reference value for further exploring the acquisition of nitrate-nitrogen by maize through AMF pathway.

Supplementary Information

The online version contains supplementary material available at 10.1007/s12298-024-01464-3.

A novel angiotensin I-converting enzyme inhibitory peptide from walnut (Juglans sigillata) protein hydrolysates and its evaluation in Ang II-induced HUVECs and hypertensive rats

This study aims to seek angiotensin-I-converting enzyme inhibitory (ACEi) peptides from walnut using different enzymatic hydrolysis, and further to validate the potent ACEi peptides identified and screened via peptidomics and in silico analysis against hypertension in spontaneously hypertensive rats (SHRs). Results showed that walnut protein hydrolysate (WPH) prepared by combination of alcalase and simulated gastrointestinal digestion exhibited high ACEi activity. WPH was separated via Sephadex-G25, and four peptides were identified, screened and verified based on their PeptideRanker score, structural characteristic and ACE inhibition. Interestingly, FDWLR showed the highest ACEi activity with IC50 value of 8.02 μg/mL, which might be related to its close affinity with ACE observed in molecular docking. Subsequently, high absorption and non-toxicity of FDWLR was predicted via in silico absorption, distribution, metabolism, excretion and toxicity. Furthermore, FDWLR exhibited positively vasoregulation in Ang II-induced human umbilical vein endothelial cells, and great blood pressure lowering effect in SHRs.

Identification novel salt-enhancing peptides from largemouth bass and exploration their action mechanism with transmembrane channel-like 4 (TMC4) by molecular simulation

The purpose of this study was to screen and verify salt-enhancing peptides that can effectively reduce sodium consumption from Largemouth bass myosin through virtual hydrolysis, molecular simulation, and sensory evaluation. The human transmembrane channel-like 4 (TMC4) was constructed using Alphafold2, with 93.3 % of amino acids falling within allowed regions. A total of 19 peptides were predicted through virtual hydrolysis and screening. DAF, QIF, RPAL, and IPVM significantly enhanced the saltiness perception, and QIF exhibited the most pronounced effect in enhancing saltiness (P < 0.05). The residues Ala258, Ser546, Ser603, Phe259, Cys265, Glu539, Lys278 and Ser585 were identified as key binding sites. The TMC4-DAF complex achieved stability after 20, 000 ps, exhibiting an average RMSD value of 0.84 nm. DAF consistently displayed fluctuations at approximately 3.05 nm, and the number of hydrogen bonds varied between 3 and 5. These results suggested that Alphafold2 modelling can be used for predicting salt-enhancing peptides.

Characteristics and Absorption Rate of Whey Protein Hydrolysates Prepared Using Flavourzyme after Treatment with Alcalase and Protamex

The purpose of this study was to evaluate the physicochemical properties of whey protein hydrolysate and determine changes in absorption rate due to enzymatic hydrolysis. The molecular weight distribution analysis of whey protein concentrate (WPC) and low-molecule whey protein hydrolysate (LMWPH) using the Superdex G-75 column revealed that LMWPH is composed of peptides smaller than those in WPC. Fourier-transform infrared spectroscopy indicated differences in peak positions between WPC and LMWPH, suggesting hydrolysis-mediated changes in secondary structures. Moreover, LMWPH exhibited higher thermal stability and faster intestinal permeation than WPC. Additionally, oral LMWPH administration increased serum protein content at 20 min, whereas WPC gradually increased serum protein content after 40 min. Although the total amount of WPC and LMWPH absorption was similar, LMWPH absorption rate was higher. Collectively, LMWPH, a hydrolysate of WPC, has distinct physicochemical properties and enhanced absorptive characteristics. Taken together, LMWPH is composed of low-molecular-weight peptides with low antigenicity and has improved absorption compared to WPC. Therefore, LMWPH can be used as a protein source with high bioavailability in the development of functional materials.

The effects of dietary microbial 6-phytase on growth parameters, intestinal morphometric properties and selected intestinal genes expression in rainbow trout (Oncorhynchus mykiss, Walbaum 1876)

This study investigated the effects of dietary 6-phytase, produced by a genetically modified Komagataella phaffii, on growth performance, feed utilisation, flesh quality, villus morphometric properties, and intestinal mRNA expression in rainbow trout. Six iso-nitrogenous, iso-lipidic, and iso-caloric diets were formulated and fed to triplicate groups of juvenile rainbow trout weighing 32.57 ± 0.36 g (mean ± SD) for 90 days. The dietary treatments included two positive controls (PC), one formulated with 400 g/kg of fish meal named T1, and the other formulated with 170 g/kg of fish meal plus 1% avP derived from monocalcium phosphate named T2. The remaining dietary treatments consisted of a negative control (NC) formulated with 170 g/kg of fish meal (T3), NC+ 750, NC+ 1500, and NC+ 3000 OTU/kg levels of phytase designated as T4, T5, and T6 diets respectively. Compared to T1, weight gain (WG) increased by 16.29, 13.71 and 11.66% in T4, T5 and T6, respectively (p < 0.05). Feed conversion ratio (FCR) was lowered by 3.2 and 0.8% in T4 and T5 compared to T1 (p < 0.05). WG, feed intake (FI), FCR, final body length, bone ash, bone ash P, and intestinal morphometry were negatively affected in T3 fed fish (p < 0.05). Whole-body fish nutrient, bone ash, bone ash phosphorus (P) compositions and mucosal villus morphometric properties improved in rainbow trout fed diets supplemented with phytase dose ranging from 750-3000 OTU. Bone ash increased by 6.12% in T5 compared to T1 (p < 0.05). Phytase inclusion enhanced the profitability of feeding juvenile rainbow trout such diets as it reduced the feed price and economic conversion rate. Dietary inclusion of phytase down-regulated mRNA expression of genes responsible for fatty acid synthesis and lipogenesis in juvenile rainbow trout. Dietary phytase up-regulated the mRNA expression of genes (SLC4A11 and ATP1A3A) responsible for nutrient uptake and down-regulated intestinal expression of MUCIN 5AC-like genes (mucus secreting genes) in juvenile rainbow trout. Along with improving performance parameters, the inclusion of phytase in rainbow trout diet containing plant-based protein sources, can preserve intestinal morphology by regulating the mRNA expression of genes responsible for fatty acid synthesis, lipogenesis and nutrient uptake and transport.

Effects of Bioactive Peptides from Atlantic Salmon Processing By-Products on Oxyntopeptic and Enteroendocrine Cells of the Gastric Mucosa of European Seabass and Gilthead Seabream

The present study was designed to evaluate the effects of dietary levels of bioactive peptides (BPs) derived from salmon processing by-products on the presence and distribution of peptic cells (oxyntopeptic cells, OPs) and enteric endocrine cells (EECs) that contain GHR, NPY and SOM in the gastric mucosa of European seabass and gilthead seabream. In this study, 27 seabass and 27 seabreams were divided into three experimental groups: a control group (CTR) fed a control diet and two groups fed different levels of BP to replace fishmeal: 5% BP (BP5%) and 10% BP (BP10%). The stomach of each fish was sampled and processed for immunohistochemistry. Some SOM, NPY and GHR-IR cells exhibited alternating "open type" and "closed type" EECs morphologies. The BP10% group (16.8 ± 7.5) showed an increase in the number of NPY-IR cells compared to CTR (CTR 8.5 ± 4.8) and BP5% (BP10% vs. CTR p ≤ 0.01; BP10% vs. BP5% p ≤ 0.05) in the seabream gastric mucosa. In addition, in seabream gastric tissue, SOM-IR cells in the BP 10% diet (16.8 ± 3.5) were different from those in CTR (12.5 ± 5) (CTR vs. BP 10% p ≤ 0.05) and BP 5% (12.9 ± 2.5) (BP 5% vs. BP 10% p ≤ 0.01). EEC SOM-IR cells increased at 10% BP (5.3 ± 0.7) compared to 5% BP (4.4 ± 0.8) (5% BP vs. 10% BP p ≤ 0.05) in seabass. The results obtained may provide a good basis for a better understanding of the potential of salmon BPs as feed ingredients for seabass and seabream.

The teleost fish PepT1-type peptide transporters and their relationships with neutral and charged substrates

In teleosts, two PepT1-type (Slc15a1) transporters, i.e., PepT1a and PepT1b, are expressed at the intestinal level. They translocate charged di/tripeptides with different efficiency, which depends on the position of the charged amino acid in the peptide and the external pH. The relation between the position of the charged amino acid and the capability of transporting the dipeptide was investigated in the zebrafish and Atlantic salmon PepT1-type transporters. Using selected charged (at physiological pH) dipeptides: i.e., the negatively charged Asp-Gly and Gly-Asp, and the positively charged Lys-Gly and Gly-Lys and Lys-Met and Met-Lys, transport currents and kinetic parameters were collected. The neutral dipeptide Gly-Gln was used as a reference substrate. Atlantic salmon PepT1a and PepT1b transport currents were similar in the presence of Asp-Gly and Gly-Asp, while zebrafish PepT1a elicited currents strongly dependent on the position of Asp in the dipeptide and zebrafish PepT1b elicited small transport currents. For Lys- and Met-containing dipeptides smaller currents compared to Gly-Gln were observed in PepT1a-type transporters. In general, for zebrafish PepT1a the currents elicited by all tested substrates slightly increased with membrane potential and pH. For Atlantic salmon PepT1a, the transport current increased with negative potential but only in the presence of Met-containing dipeptides and in a pH-dependent way. Conversely, large currents were shown for PepT1b for all tested substrates but Gly-Lys in Atlantic salmon. This shows that in Atlantic salmon PepT1b for Lys-containing substrates the position of the charged dipeptides carrying the Lys residue defines the current amplitudes, with larger currents observed for Lys in the N-terminal position. Our results add information on the ability of PepT1 to transport charged amino acids and show species-specificity in the kinetic behavior of PepT1-type proteins. They also suggest the importance of the proximity of the substrate binding site of residues such as LysPepT1a/GlnPepT1b for recognition and specificity of the charged dipeptide and point out the role of the comparative approach that exploits the natural protein variants to understand the structure and functions of membrane transporters.

Intestinal Amino Acid Transport and Metabolic Health

Amino acids derived from protein digestion are important nutrients for the growth and maintenance of organisms. Approximately half of the 20 proteinogenic amino acids can be synthesized by mammalian organisms, while the other half are essential and must be acquired from the nutrition. Absorption of amino acids is mediated by a set of amino acid transporters together with transport of di- and tripeptides. They provide amino acids for systemic needs and for enterocyte metabolism. Absorption is largely complete at the end of the small intestine. The large intestine mediates the uptake of amino acids derived from bacterial metabolism and endogenous sources. Lack of amino acid transporters and peptide transporter delays the absorption of amino acids and changes sensing and usage of amino acids by the intestine. This can affect metabolic health through amino acid restriction, sensing of amino acids, and production of antimicrobial peptides.

The Melanocortin System in Inflammatory Bowel Diseases: Insights into Its Mechanisms and Therapeutic Potentials

The melanocortin system is a complex set of molecular mediators and receptors involved in many physiological and homeostatic processes. These include the regulation of melanogenesis, steroidogenesis, neuromodulation and the modulation of inflammatory processes. In the latter context, the system has assumed importance in conditions of chronic digestive inflammation, such as inflammatory bowel diseases (IBD), in which numerous experiences have been accumulated in mouse models of colitis. Indeed, information on how such a system can counteract colitis inflammation and intervene in the complex cytokine imbalance in the intestinal microenvironment affected by chronic inflammatory damage has emerged. This review summarises the evidence acquired so far and highlights that molecules interfering with the melanocortin system could represent new drugs for treating IBD.

Development of a Rainbow Trout (Oncorhynchus mykiss) Intestinal In Vitro Platform for Profiling Amino Acid Digestion and Absorption of a Complete Diet

The ever-increasing number and variation of raw materials utilized to provide alternative feed formulations continues to allow for a more sustainable and flexible approach. Testing all these options in vivo is still the most robust and reliable manner to pick the best raw material candidates, but it requires the use of large numbers of animals and is time-consuming and expensive. Therefore, we are developing an in vitro platform that can provide a reliable evaluation of new ingredients. The main aim of this work was to combine an in vitro digestion protocol of extruded, commercially relevant aquafeeds with the exposure of intestinal epithelial cells to the extracted bio-available fraction (BAF). The results show that 250,000 cells/cm² represents the optimal seeding density and that up to 50% BAF concentration for up to 24 h had no negative effects on the epithelial barrier morphology and function. It is possible to determine amino acid digestibility and bioavailability in all the experimental conditions (with and without BSA, at 25% and 50% dilution) and at all time points (0, 6, and 24 h). However, BAF concentration, the medium used for its dilution, and the length of exposure to the different epithelial cell lines can all influence the results and, therefore, must be selected according to the final aim of the experiment.

Development, characterization and in vivo zinc absorption capacity of a novel soy meal hydrolysate-zinc complexes

Background

Zinc is an essential trace element for the human body. Recently, a novel Zn-binding peptide, Lys-Tyr-Lys-Arg-Gln-Arg-Trp (PP), was purified and identified from soy protein hydrolysates with high Zn-binding capacity (83.21 ± 2.65%) by our previous study. The preparation of soy meal hydrolysates (SMHs)-Zn complexes is convenient and low-cost, while PP (Lys-Tyr-Lys-Arg-Gln-Arg-Trp)-Zn complexes have a higher coordination rate but a relatively high cost. The aim of this study was to investigate the effect of soy meal hydrolysates (SMHs)-Zn complexes on zinc absorption in mice model, and synthetic soy peptide (PP)-Zn complexes with high Zn-binding capacity were used as control. Firstly, SMHs were prepared by enzymolysis, and the PP (Lys-Tyr-Lys-Arg-Gln-Arg-Trp) were synthesized based on previous studies. The binding mechanism of soy hydrolysates and zinc was analyzed by spectral analysis. Furthermore, the cytotoxicity of the SMHs-Zn complexes was also studied using the CCK-8 method. The effect of zinc absorption was evaluated based on Zn content, total protein and albumin content, relevant enzyme system, and the PeT1 and ZnT1 mRNA expression levels.

Result

The result showed that zinc was bound with carboxyl oxygen and amino nitrogen atoms on SMHs, with hydrophobic and electrostatic interactions as auxiliary stabilizing forces. SMHs-Zn were proved to have great solubility and a small particle size at different pH values, and it showed a beneficial effect on Caco-2 cells growth. Moreover, it was proved that SMHs-Zn and PP-Zn could increase the levels of zinc and the activity of Zn-related enzymes in mice. SMHs-Zn possessed higher PepT1 and ZnT1 mRNA expression levels than PP-Zn in the small intestine.

Conclusion

SMHs-Zn with a lower Zn-binding capacity had similar effects on zinc absorption in mice as PP-Zn, suggesting that the bioavailability of peptide-zinc complexes in mice was not completely dependent on their Zn-binding capacity, but may also be related to the amino acid composition.

Maternal heterozygosity of Slc6a19 causes metabolic perturbation and congenital NAD deficiency disorder in mice

Nicotinamide adenine dinucleotide (NAD) is a key metabolite synthesised from vitamin B3 or tryptophan. Disruption of genes encoding NAD synthesis enzymes reduces NAD levels and causes congenital NAD deficiency disorder (CNDD), characterised by multiple congenital malformations. SLC6A19 (encoding B0AT1, a neutral amino acid transporter), represents the main transporter for free tryptophan in the intestine and kidney. Here, we tested whether Slc6a19 heterozygosity in mice limits the tryptophan available for NAD synthesis during pregnancy and causes adverse pregnancy outcomes. Pregnant Slc6a19+/- mice were fed diets depleted of vitamin B3, so that tryptophan was the source of NAD during gestation. This perturbed the NAD metabolome in pregnant Slc6a19+/- females, resulting in reduced NAD levels and increased rates of embryo loss. Surviving embryos were small and exhibited specific combinations of CNDD-associated malformations. Our results show that genes not directly involved in NAD synthesis can affect NAD metabolism and cause CNDD. They also suggest that human female carriers of a SLC6A19 loss-of-function allele might be susceptible to adverse pregnancy outcomes unless sufficient NAD precursor amounts are available during gestation. This article has an associated First Person interview with the first author of the paper.

The Synergistic Effects of the Combination of L-Carnitine and Lycopene on the Lycopene Bioavailability and Duodenal Health of Roosters

The objective of this study was to investigate the impact of Lycopene and L-Carnitine, individually or in combination, on various physiological and molecular factors related to intestinal health and absorption ability in Roosters, such as intestinal morphology, serum biochemical parameters, genes involved in Lycopene uptake, nutritional transport genes, and tight junction genes. The findings of the study revealed that the combination of L-Carnitine and Lycopene supplementation had been found to increase the serum concentration levels of TP and ALB. Interestingly, the relative mRNA expression of genes responsible for Lycopene uptakes, such as SR-BI and BCO2, was higher in the LC group compared to other groups. Additionally, the expression of specific nutritional transport genes in the duodenum was significantly affected by both CAR and LC supplementation groups. The tight junction gene OCLN showed a significant increase in expression in the combination group compared to using either Lycopene or L-Carnitine alone. This study concludes that using Lycopene and L-carnitine in combination in poultry feed can potentially improve intestinal morphology and serum biochemical parameters, increase Lycopene bioavailability, improve nutrients uptake, and enhance the integrity of duodenal tight junctions in Roosters.

Collagen supplementation in skin and orthopedic diseases: A review of the literature

Collagen is one of the main components of the extracellular matrix of the dermis and articular cartilage and influences the body's mechanical, organizational, and tissue formation properties. Produced from food industry by-products, it is considered a nutraceutical product widely used as an ingredient or supplement in food, pharmaceutical, and cosmetic industries. This study aimed to conduct a literature review on the scientific evidence regarding the beneficial effects of collagen consumption in the treatment of skin and orthopedic diseases. Literature data have shown that hydrolyzed collagen supplementation promotes skin changes, such as decreased wrinkle formation; increased skin elasticity; increased hydration; increased collagen content, density, and synthesis, which are factors closely associated with aging-related skin damage. Regarding orthopedic changes, collagen supplementation increases bone strength, density, and mass; improves joint stiffness/mobility, and functionality; and reduces pain. These aspects are associated with bone loss due to aging and damage caused by strenuous physical activity. Thus, this review addresses the economic and health potential of this source of amino acids and bioactive peptides extracted from food industry by-products.

The Contribution of Phytate-Degrading Enzymes to Chicken-Meat Production

The contribution that exogenous phytases have made towards sustainable chicken-meat production over the past two decades has been unequivocally immense. Initially, their acceptance by the global industry was negligible, but today, exogenous phytases are routine additions to broiler diets, very often at elevated inclusion levels. The genesis of this remarkable development is based on the capacity of phytases to enhance phosphorus (P) utilization, thereby reducing P excretion. This was amplified by an expanding appreciation of the powerful anti-nutritive properties of the substrate, phytate (myo-inositol hexaphosphate; IP₆), which is invariably present in all plant-sourced feedstuffs and practical broiler diets. The surprisingly broad spectra of anti-nutritive properties harbored by dietary phytate are counteracted by exogenous phytases via the hydrolysis of phytate and the positive consequences of phytate degradation. Phytases enhance the utilization of minerals, including phosphorus, sodium, and calcium, the protein digestion, and the intestinal uptakes of amino acids and glucose to varying extents. The liberation of phytate-bound phosphorus (P) by phytase is fundamental; however, the impacts of phytase on protein digestion, the intestinal uptakes of amino acids, and the apparent amino acid digestibility coefficients are intriguing and important. Numerous factors are involved, but it appears that phytases have positive impacts on the initiation of protein digestion by pepsin. This extends to promoting the intestinal uptakes of amino acids stemming from the enhanced uptakes of monomeric amino acids via Na⁺-dependent transporters and, arguably more importantly, from the enhanced uptakes of oligopeptides via PepT-1, which is functionally dependent on the Na⁺/H⁺ exchanger, NHE. Our comprehension of the phytate-phytase axis in poultry nutrition has expanded over the past 30 years; this has promoted the extraordinary surge in acceptance of exogenous phytases, coupled with the development of more efficacious preparations in combination with the deflating inclusion costs for exogenous phytases. The purpose of this paper is to review the progress that has been made with phytate-degrading enzymes since their introduction in 1991 and the underlying mechanisms driving their positive contribution to chicken-meat production now and into the future.

Diet-induced gut dysbiosis and inflammation: Key drivers of obesity-driven NASH

Sucrose, the primary circulating sugar in plants, contains equal amounts of fructose and glucose. The latter is the predominant circulating sugar in animals and thus the primary fuel source for various tissue and cell types in the body. Chronic excessive energy intake has, however, emerged as a major driver of obesity and associated pathologies including nonalcoholic fatty liver diseases (NAFLD) and the more severe nonalcoholic steatohepatitis (NASH). Consumption of a high-caloric, western-style diet induces gut dysbiosis and inflammation resulting in leaky gut. Translocation of gut-derived bacterial content promotes hepatic inflammation and ER stress, and when either or both of these are combined with steatosis, it can cause NASH. Here, we review the metabolic links between diet-induced changes in the gut and NASH. Furthermore, therapeutic interventions for the treatment of obesity and liver metabolic diseases are also discussed with a focus on restoring the gut-liver axis.

Effects of dietary supplementation with bioactive peptides derived from rapeseed protein on the growth performance, serum biochemistry and faecal micro‐organism composition of weaned piglets

The present study investigated the effects of supplementing bioactive peptides derived from rapeseed protein (rapeseed peptide, Rsp) on the growth performance, serum biochemistry and faecal micro-organism composition of weaned piglets. Sixty Duroc × Landrace × Yorkshire weaned piglets of similar weights were randomly divided into three groups. The control group (NC) was fed a basal diet, and the two treatment groups, Rsp-1 and Rsp-2, were fed a basal diet supplemented with 1% or 2% Rsp, respectively, for 28 days. Each treatment consisted of five replicates with four piglets per replicate. The results showed that Rsp treatment significantly improved the average daily gain and had a better feed-to-gain ratio (p < 0.05). The diarrhoea incidence and indices of Rsp-1 and Rsp-2 groups were significantly lower than the NC group (p < 0.05), and the effect of Rsp-2 on reducing the incidence of diarrhoea was significantly higher than that of Rsp-1 (p < 0.05). The serum albumin, serum immunoglobulin A and catalase levels of the Rsp-1 and Rsp-2 groups were significantly better than the NC group (p < 0.05). Additionally, Rsp treatment significantly gained the relative abundance of faecal Lactobacillaceae and decreased the relative abundance of faecal Eubacterium_coprostanoligenes_group, Treponema and Coprococcus (p < 0.05). In summary, Rsp supplementation improved the growth performance, ameliorated the diarrhoea, enhanced the immune and antioxidant functions and changed the composition of faecal micro-organisms in piglets. These findings indicate that Rsp positively affected the health of weaned piglets.

The Physiological Function and Potential Role of the Ubiquitous Na+/H+ Exchanger Isoform 8 (NHE8): An Overview Data

The Na⁺/H⁺ exchanger transporters (NHE) play an important role in various biologic processes including Na⁺ absorption, intracellular pH homeostasis, cell volume regulation, proliferation, and apoptosis. The wide expression pattern and cellular localization of NHEs make these proteins pivotal players in virtually all human tissues and organs. In addition, recent studies suggest that NHEs may be one of the primeval transport protein forms in the history of life. Among the different isoforms, the most well-characterized NHEs are the Na⁺/H⁺ exchanger isoform 1 (NHE1) and Na⁺/H⁺ exchanger isoform 3 (NHE3). However, Na⁺/H⁺ exchanger isoform 8 (NHE8) has been receiving attention based on its recent discoveries in the gastrointestinal tract. In this review, we will discuss what is known about the physiological function and potential role of NHE8 in the main organ systems, including useful overviews that could inspire new studies on this multifaceted protein.

Characterization of a synthetic zinc-chelating peptide from sea cucumber (Stichopus japonicus) and its gastrointestinal digestion and absorption in vitro

BACKGROUND

Zinc absorption in intestinal system could be strongly affected by the gastrointestinal digestion and absorption of zinc-chelating peptides serving as zinc carriers. In this study, a novel zinc-chelating sea cucumber synthetic peptide (SCSP) was synthesized to estimate its gastrointestinal digestion and promotive effect of zinc absorption in vitro.

RESULTS

Analysis of isothermal titration calorimetry suggested that the binding of SCSP and zinc (N ≈ 1) was exothermic, with relatively weak binding affinity (K = 1.0 × 10^-3  mol L^-1 ). The formation of SCSP-Zn complexes brought morphological changes to the peptides confirmed by scanning electron microscopy (SEM), which also indicated 6.88% of the existence of zinc element. In addition, the SCSP-Zn complexes remained stable under simulated human gastrointestinal digestion. In an in vitro study, the SCSP-Zn complex could successfully transport through the intestinal membrane in the model of everted rat gut sacs (nearly 7.5 μM cm^-2 ) as well as Caco-2 cells where the zinc transport reached 0.0014 mg mL^-1 carried by SCSP. Fluorescence staining experiments revealed free zinc accumulation inside the tissues and cells treated with the SCSP-Zn complex.

CONCLUSIONS

The chelation SCSP-Zn had the promotion ability of zinc absorption in vitro and ex vivo experiments, which suggested a theoretical basis for the design and production of effective zinc chelating peptides as zinc carriers to improve zinc bioavailability. © 2022 Society of Chemical Industry.

Anti-inflammatory effects of tripeptide WLS on TNF-α-induced HT-29 cells and DSS-induced colitis in mice

Inflammatory bowel disease is a chronic disease of the intestinal tract, which is related to increased levels of various inflammatory mediators. This study aims to explore the anti-inflammatory mechanism of small molecular peptide WLS and its alleviating effect on inflammatory bowel disease (IBD). In TNF-α-induced HT-29 cells, WLS inhibited IL-8 secretion, decreased gene expression of pro-inflammatory cytokines IL-8, IL-6, IL-1β, and TNF-α, and inhibited the activation of MAPK/NF-κB signaling pathways. In the dextran sulfate sodium salt (DSS) induced colitis mouse model, WLS inhibited weight loss and disease activity index scores, increased colon length, improved colon histopathology, inhibited secretion of IL-6 and TNF-α in the colon, and down-regulated gene expression of pro-inflammatory cytokines (IL-6, TNF-α, IL-1β, IFN-γ, IL-17A). This study revealed that WLS was a novel small molecule peptide with anti-inflammatory activity and may be a potential candidate for the treatment of inflammatory bowel disease.

Lysine Dipeptide Enhances Gut Structure and Whole-Body Protein Synthesis in Neonatal Piglets with Intestinal Atrophy

BACKGROUND

Parenteral nutrition (PN) is often a necessity for preterm infants; however, prolonged PN leads to gut atrophy, weakened gut barrier function, and a higher risk of intestinal infections. Peptide transporter-1 (PepT1) is a di- or tripeptide transporter in the gut and, unlike other nutrient transporters, its activity is preserved with the onset of intestinal atrophy from PN. As such, enteral amino acids in the form of dipeptides may be more bioavailable than free amino acids when atrophy is present.

OBJECTIVES

In Yucatan miniature piglets with PN-induced intestinal atrophy, we sought to determine the structural and functional effects of enteral refeeding with lysine as a dipeptide, compared to free L-lysine.

METHODS

Piglets aged 7-8 days were PN-fed for 4 days to induce intestinal atrophy, then were refed with enteral diets with equimolar lysine supplied as lysyl-lysine (Lys-Lys; n = 7), free lysine (n = 7), or Lys-Lys with glycyl-sarcosine (n = 6; to determine whether competitive inhibition of Lys-Lys uptake would abolish PepT1-mediated effects). The diets provided lysine at 75% of the requirement and were gastrically delivered for a total of 18 hours. Whole-body and tissue-specific protein synthesis, as well as indices for gut structure and barrier function, were measured.

RESULTS

The villus height, mucosal weight, and free lysine concentration were higher in the Lys-Lys group compared to the other 2 groups (P < 0.05). Lysyl-lysine led to greater whole-body protein synthesis compared to free lysine (P < 0.05). Mucosal myeloperoxidase activity was lower in the Lys-Lys group (P < 0.05), suggesting less inflammation. The inclusion of glycyl-sarcosine with Lys-Lys abolished the dipeptide effects on whole-body and tissue-specific protein synthesis (P < 0.05), suggesting that improved lysine availability was mediated by PepT1.

CONCLUSIONS

Improved intestinal structure and whole-body protein synthesis suggests that feeding strategies designed to exploit PepT1 may help to avoid adverse effects when enteral nutrition is reintroduced into the compromised guts of neonatal piglets.

Dietary crude protein concentrations, feed grains and whey protein interactively influence apparent digestibility coefficients of amino acids, protein, starch and performance of broiler chickens

The present study was designed to investigate the impacts of dietary crude protein (CP) concentrations (220 and 180 g/kg) in either maize- or wheat-based diets, without or with 25 g/kg inclusions of whey powder (WP) concentrate on performance parameters and apparent amino acid digestibility coefficients in broiler chickens. The maize and wheat used in this study had CP levels of 84 and 119 g/kg, respectively. The 2 × 2 × 2 factorial array of 8 dietary treatments was offered to a total of 336 off-sex, male Ross 308 chicks from 7 to 35 d post-hatch with 7 replicate cages (6 birds per cage) per treatment. A treatment interaction (P = 0.016) between dietary CP and feed grains was detected for weight gains, where birds offered 180 g/kg maize-based diets displayed a weight gain advantage of 6.74% (2,628 vs. 2,462 g/bird) compared to their wheat-based counterparts. An interaction (P = 0.022) between feed grains and whey protein was observed for FCR as the addition of WP to maize-based diets improved FCR by 3.45% (1.314 vs. 1.361), but compromised FCR in wheat-based diets by 2.98% (1.415 vs. 1.374). A treatment interaction (P = 0.038) between dietary CP and feed grains was recorded for relative abdominal fat-pad weights weight gains as birds offered 180 g/kg CP maize-based diets had 43.4% (11.17 vs. 7.79 g/kg) heavier fat-pads than their wheat-based counterparts. Following the reduction in dietary-CP, apparent amino acid digestibility coefficients were depressed to greater extents in wheat-based diets. However, significant interactions between CP and feed grains were found in 14 of the 16 amino acids assessed and significant interactions between CP and WP were observed for 15 amino acids. Maize was the more suitable feed grain in terms of weight gain and FCR in 180 g/kg CP diets despite causing greater fat deposition. The inclusion of WP in reduced-CP diets did not enhance bird performance. Data generated indicate concentrations of microbial amino acids in distal ileal digesta were depressing apparent amino acid digestibility coefficients, which was more evident in wheat-based diets. Higher gut viscosities in birds offered wheat-based diets may have facilitated the proliferation of microbiota along the small intestine.

Increased arginine, lysine, and methionine levels can improve the performance, gut integrity and immune status of turkeys but the effect is interactive and depends on challenge conditions

Arginine (Arg), lysine (Lys), and methionine (Met) can be used to support the health status of turkeys. The present study investigated selected performance, gut integrity, and immunological parameters in turkeys reared in optimal or challenge conditions. The experiment lasted for 28 days, and it had a completely randomized 2 × 3 factorial design with two levels of dietary Arg, Lys and Met (high or low) and challenge with Clostridium perfringens (C. perfringens), Escherichia coli lipopolysaccharide (LPS) or no challenge (placebo). Increased dietary levels of Arg, Lys and Met had a beneficial effect on turkey performance and immunological parameters, and it improved selected indicators responsible for maintaining gut integrity in different challenge conditions. Under optimal conditions (with no challenge), high ArgLysMet diets did not compromise bird performance and they improved selected performance parameters in challenged birds. The immune system of turkeys was not excessively stimulated by high ArgLysMet diets, which did not disrupt the redox balance and had no negative effect on gut integrity. High ArgLysMet diets increased the expression levels of selected genes encoding nutrient transporters and tight junction proteins. However, the influence exerted by different dietary inclusion levels of Arg, Lys and Met on gut integrity was largely determined by the stressor (C. perfringens vs. LPS). Further studies are required to investigate the role of Arg, Lys and Met levels in the diet on the immune response, gut function and performance of turkeys in different challenge conditions.

Cryo-EM Structure of an Atypical Proton-Coupled Peptide Transporter: Di- and Tripeptide Permease C

Proton-coupled Oligopeptide Transporters (POTs) of the Major Facilitator Superfamily (MFS) mediate the uptake of short di- and tripeptides in all phyla of life. POTs are thought to constitute the most promiscuous class of MFS transporters, with the potential to transport more than 8400 unique substrates. Over the past two decades, transport assays and biophysical studies have shown that various orthologues and paralogues display differences in substrate selectivity. The E. coli genome codes for four different POTs, known as Di- and tripeptide permeases A-D (DtpA-D). DtpC was shown previously to favor positively charged peptides as substrates. In this study, we describe, how we determined the structure of the 53 kDa DtpC by cryogenic electron microscopy (cryo-EM), and provide structural insights into the ligand specificity of this atypical POT. We collected and analyzed data on the transporter fused to split superfolder GFP (split sfGFP), in complex with a 52 kDa Pro-macrobody and with a 13 kDa nanobody. The latter sample was more stable, rigid and a significant fraction dimeric, allowing us to reconstruct a 3D volume of DtpC at a resolution of 2.7 Å. This work provides a molecular explanation for the selectivity of DtpC, and highlights the value of small and rigid fiducial markers such as nanobodies for structure determination of low molecular weight integral membrane proteins lacking soluble domains.

Protein sources and starch-protein digestive dynamics manipulate growth performance in broiler chickens defined by an equilateral-triangle response surface design

A total of 360 male, off-sex Ross 308 chicks were offered 10 dietary treatments from 14 to 35 d post–hatch in an equilateral-triangle response surface design feeding study in order to confirm the importance of protein and amino acid digestive dynamics in broiler chickens. The 3 apical diets were nutritionally-equivalent containing either soybean meal, non-bound amino acids or whey protein concentrate as the major source of dietary protein and amino acids. Appropriate blends of the 3 apical diets comprised the balance of 7 diets and each dietary treatment was offered to 6 replicate cages with 6 birds per cage. Growth performance, nutrient utilisation, apparent protein and starch digestibility coefficients were determined in 4 small intestinal segments. The optimal weight gain (2,085 g/bird) and feed conversion ratios (FCR, 1.397) were generated by Diet 50S50W which included a 50:50 blend of apical diets rich in whey protein concentrate and soybean meal. Broiler chickens offered Diet 50S50W also had the highest experimental and predicted jejunal digestibility (0.685 in proximal jejunum and 0.823 in distal jejunum). FCR was not correlated with apparent distal ileal digestibility coefficient (P > 0.05) of protein but was correlated with apparent protein digestibility in proximal jejunum (r = −0.369, P = 0.040) and distal jejunum (r = −0.316, P = 0.015). Surplus dietary starch was correlated with increased fat pad weight (r = 0.781, P = 0.008). The findings confirmed the relevance of protein digestion rate, reflected by jejunal digestibility, on feed conversion of broiler chickens. A balance between protein-bound and non-bound crystalline or synthetic amino acids may be required for optimal growth and protein digestion.

Serum Metabolomics Benefits Discrimination Kidney Disease Development in Type 2 Diabetes Patients

Background

Diabetic kidney disease (DKD) is the primary cause of end-stage renal disease, raising a considerable burden worldwide. Recognizing novel biomarkers by metabolomics can shed light on new biochemical insight to benefit DKD diagnostics and therapeutics. We hypothesized that serum metabolites can serve as biomarkers in the progression of DKD.

Methods

A cross-sectional study of 1,043 plasma metabolites by untargeted LC/MS among 89 participants identified associations between proteinuria severity and metabolites difference. Pathway analysis from differently expressed metabolites was used to determine perturbed metabolism pathways. The results were replicated in an independent, cross-sectional cohort of 83 individuals. Correlation and prediction values were used to examine the association between plasma metabolites level and proteinuria amount.

Results

Diabetes, and diabetic kidney disease with different ranges of proteinuria have shown different metabolites patterns. Cysteine and methionine metabolism pathway, and Taurine and hypotaurine metabolism pathway were distinguishable in the existence of DKD in DC (diabetes controls without kidney disease), and DKD with different ranges of proteinuria. Two interesting tetrapeptides (Asn-Met-Cys-Ser and Asn-Cys-Pro-Pro) circulating levels were elevated with the DKD proteinuria progression.

Conclusions

These findings underscore that serum metabolomics provide us biochemical perspectives to identify some clinically relevant physiopathologic biomarkers of DKD progression.

Investigating the effects of peptide-based, MOS and protease feed additives on the growth performance and fecal microbial composition of weaned pigs

Background

Digestive disorders in weaning pigs remain a major challenge for swine producers. Different types of commercial feed additives have been developed to promote gut health and development in young pigs, but their effects on resident gut microbial communities remain largely unexplored. The aim of this study was to investigate the impact of a peptide-based product (Peptiva) in combination with mannose oligosaccharides (MOS) and an exogenous protease on the performance and fecal microbiome of nursery pigs.

Methods

A total of 1097 weaned pigs were divided into 44 pens (24–26 pigs/pen) with each pen randomly assigned to one of four experimental diets as part of Phase II and Phase III of a standard nursery phase feeding program. Fecal samples collected from representative control and treatment pigs were used to investigate bacterial composition profiles by high throughput sequencing of PCR-generated amplicons targeting the V1-V3 region of the 16S rRNA gene.

Results

Higher gain:feed was observed for pigs fed Peptiva and MOS compared to Controls during the period when experimental diets were fed, but the benefits of supplementation were not maintained after pigs were transitioned to a non-supplemented diet. Three candidate bacterial species, identified as Operational Taxonomic Units (OTUs), were found to have significantly different abundances between control samples and treatment samples during the same phase. In Phase III samples, SD_Ssd-00039, predicted to be a strain of Streptococcus alactolyticus based on nucleotide sequence identity, was the most highly represented of these OTUs with an average abundance in pigs fed Peptiva, MOS and protease that was 3.9 times higher than in Controls. The report also presents evidence of microbial succession that occurred during the trial, with 16 of the 32 most abundant OTUs found to vary between Phase II and Phase III samples for the same dietary treatment.

Conclusions

Dietary supplementation with a combination of a peptide-based product, MOS, and protease increased the growth performance of weaned pigs compared to control animals during the nursery phase, but these benefits were no longer observed within 2 weeks after all animals were transitioned to a non-supplemented diet. Supplementation with these feed additives was found to modulate the composition of the swine gut microbiome during this period.

Supplementary Information

The online version contains supplementary material available at 10.1186/s40104-022-00681-8.

DL-methionine and DL-methionyl-DL-methionine increase intestinal development and activate Wnt/β-catenin signaling activity in domestic pigeons (Columba livia)

This experiment was undertaken to investigate the effects of parental dietary DL-methionine (DL-Met) and DL-methionyl-DL-methionine (DL-Met-Met) supplementation on the intestinal development of young squabs. A total of 108 pairs of breeding pigeons and 432 one-day-old squabs were randomly divided into 3 groups: the control group (CON) was fed a basal diet (CP = 15%) and the experimental groups were fed a basal diet supplemented with 0.3% DL-Met or DL-Met-Met. Each pair of breeding pigeons nourished 4 young squabs, and 8 squabs from each treatment were randomly sampled at the end of the experiment. The results indicated that DL-Met and DL-Met-Met supplementation improved the intestinal morphology and structure in the squabs, as reflected by the increased relative intestinal weight of each small intestinal segment, villus height, and villus to crypt ratio. In addition, DL-Met and DL-Met-Met supplementation significantly increased the protein expression of cell proliferation markers (Ki67 and PCNA) and tight junction proteins (ZO-1 and Claudin-1) in the jejunum and strengthened the fluorescence signal intensity of Ki67, PCNA and Villin. Moreover, the expression of Wnt/β-catenin signaling pathway-related proteins (Frizzled 7 [FZD7], p-GSK-3β, Active β-catenin, β-catenin, TCF4, c-Myc, and Cyclin D1), and intestinal peptide transporter 1 (PepT1) in the jejunum was considerably higher in the treatment group than in the CON group (P < 0.05), with the DL-Met-Met group having the highest expression. Consistently, the molecular docking results predicted the possibility that DL-Met or DL-Met-Met binds to the membrane receptor FZD7, which mediates Wnt/β-catenin signaling. Collectively, the improvement of the intestinal development in squabs after parental dietary 0.3% DL-Met and DL-Met-Met supplementation could be through activation of Wnt/β-catenin signaling pathway, and DL-Met-Met is superior to DL-Met. Our findings may provide basic data for further optimizing the feeding formula of breeding pigeons and improving the growth and development of squabs.

Investigation of the intestinal trans-epithelial transport and antioxidant activity of two hempseed peptides WVSPLAGRT (H2) and IGFLIIWV (H3)

A preceding paper has shown that a hempseed peptic hydrolysate displays a cholesterol-lowering activity with a statin-like mechanism of action in HepG2 cells and a potential hypoglycemic activity by the inhibition of dipeptidyl peptidase-IV in Caco-2 cells. In the framework of a research aimed at fostering the multifunctional behavior of hempseed peptides, we present here the identification and evaluation of some antioxidant peptides from the same hydrolysate. After evaluation of its diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity, a trans-epithelial transport experiment was performed using differentiated Caco-2 cells that permitted the identification of five transported peptides that were synthesized and evaluated by measuring the oxygen radical absorbance capacity (ORAC), the ferric reducing antioxidant power (FRAP), and the 2,2-azino-bis-(3-ethylbenzothiazoline-6-sulfonic) acid (ABTS), and diphenyl-2-picrylhydrazyl radical DPPH assays. The most active peptides, i.e. WVSPLAGRT (H2) and IGFLIIWV (H3), were then tested in cell assays. Both peptides were able to reduce the H₂O₂-induced reactive oxygen species (ROS), lipid peroxidation, and nitric oxide (NO) production levels in HepG2 cells, via the modulation of Nrf-2 and iNOS pathways, respectively.

Microcystin-LR incorporated into colonic cells through probenecid-sensitive transporters leads to upregulated MCP-1 expression induced by JNK activation

Harmful algae that inhabit eutrophic lakes produce cyanotoxic microcystins. Therefore, the relationship between chronic exposure to microcystins via drinking water and organ disorders has been investigated. The present study aimed to determine whether representative microcystin-LR is involved in increased monocyte chemoattractant protein-1 (MCP-1) expression in rat colonic mucosa and enterocyte-like differentiated Caco-2 cells. The mRNA expression of MCP-1 was increased in the colons of rats administered with microcystin-LR, compared with controls. Furthermore, mRNA levels of MCP-1 expression significantly and positively correlated with those of Adhesion G Protein-Coupled Receptor E1 (ADGRE1; EMR1; F4/80), an indicator of macrophage infiltration, suggesting that increased MCP-1 expression induced by microcystin-LR promotes macrophage infiltration into the colon. Microcystin-LR increased MCP-1 expression in enterocyte-like differentiated Caco-2 cells, by activating c-Jun N-terminal kinase (JNK), but not extracellular signal-regulated kinase (ERK) or p38. The findings of transporter inhibitors indicated that microcystin-LR is incorporated into cells via ATP Binding Cassette (ABC) or solute carrier (SLC) transporters other than the organic anion transporting polypeptides (OATPs)1B1, 1B3, 2B1, and 1A2, which this leads to increased MCP-1 expression in the colon through activating JNK. Thus, increased MCP-1 expression induced by microcystin-LR might be a trigger for initiating tumorigenesis with inflammation in the colon because increased MCP-1 expression induces inflammation associated with macrophage infiltration into the colon, and chronic inflammation is associated with the initiation of tumorigenesis.

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Microcystin-LR upregulated colonic MCP-1 expression in rats.

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Increased MCP-1 expression correlated with accumulated macrophages in rat colon.

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Microcystin-LR evoked MCP-1 expression by activating JNK in cultured colon cells.

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Rifampicin was not involved in microcystin-LR-induced JNK activation.

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Probenecid suppressed JNK/MCP-1 pathway activation induced by microcystin-LR.

Effects of methionine as free amino acid and dipeptide on productive efficiency and meat quality of broilers under acute and chronic heat stress

Context Methionine in the form of free amino acid has been widely studied in broilers challenged by heat stress (HS). However, the effects of methionine dipeptide in broilers subjected to HS are not known. Aims To evaluate the effects of methionine as free amino acid and dipeptide on the performance, oxidative status, plasma parameters and meat quality of broilers subjected to acute and chronic HS. Methods Broilers were evaluated at the following three experimental periods: 24 h of evaluation (21–22 days of age); 10 days of evaluation (22–32 days of age); and 20 days of evaluation (22–42 days of age). Broilers were divided into two groups; one group was raised in thermal comfort, and the other group was raised in continuous HS of 30°C. In both groups, animals received a diet without methionine supplementation (MD), with supplementation of methionine as free amino acid (dl-M), and with supplementation of methionine as dipeptide (dl-MM). Key results HS reduced body weight gain after 10 and 20 days of evaluation. Broilers under HS condition fed the MD diet had the highest concentrations of thiobarbituric acid reactive substances (TBARS) at 22 days of age and carbonylated proteins (CP) at 32 days of age. At 42 days of age, broilers fed the MD diet had higher concentrations of TBARS and CP. At 32 days of age, broilers under HS had lower high-density lipoprotein and higher low-density lipoprotein concentrations. In breast meat, broilers in thermal comfort fed the dl-M or dl-MM diets had a lower cooking loss. Broilers in HS fed the dl-M diet had the lowest cooking loss. HS reduced the pH of the meat of legs. Conclusions The acute and chronic HS affect the broiler performance in different ways. Methionine supplementation contributes to reduce the effects of HS. There were no notable differences between the supplementation of dl-M or dl-MM. Implications Productivity and the quality of the chicken meat are the most important attributes of the production. The ambient temperature can influence these parameters. The methionine in its most varied forms, due to its direct and indirect antioxidant function, has been shown to be an effective source of protection for the animal in adverse conditions such as during HS.

Oral Intake of Enzymatically Decomposed AP Collagen Peptides Improves Skin Moisture and Ceramide and Natural Moisturizing Factor Contents in the Stratum Corneum

The stratum corneum (SC) is the outermost layer of the epidermis and plays an important role in maintaining skin moisture and protecting the skin from the external environment. Ceramide and natural moisturizing factor (NMF) are the major SC components that maintain skin moisture. In this study, we investigated whether the oral intake of enzymatically decomposed AP collagen peptides (APCPs) can improve skin moisture and barrier function by assessing changes in the ceramide and NMF contents in the SC after APCP ingestion with the aim to develop a skin functional food. Fifty participants orally ingested APCP (1000 mg) or placebo for 12 weeks, and then, skin hydration and skin texture were evaluated. SC samples were collected to analyze skin scaling, ceramide, and NMF contents. Participants in the APCP group exhibited improved skin moisture content by 7.33% (p = 0.031) and roughness by -4.09% (p = 0.036) when compared with those in the placebo group. NMF content; the amounts of amino acids (AA), including glycine and proline; and AA derivatives were significantly increased in the APCP group (31.98 μg/mg protein) compared to those in the placebo group (-16.01 μg/mg protein) (p = 0.006). The amounts of total ceramides and ceramide subclasses were significantly higher in the APCP group than in the placebo group (p = 0.014). In conclusion, our results demonstrate that APCP intake improves skin moisture and increase the ceramide and NMF contents in the SC, thereby enhancing the skin barrier function.

Discovery of novel, potent and orally efficacious inhibitor of neutral amino acid transporter B0AT1 (SLC6A19)

Amino acid restriction by inhibition of neutral amino acid transporter, B⁰AT1 (SLC6A19) activity has been recently shown to improve glyceamic control by upregulating glucagon like peptide (GLP1) and fibroblast growth factor (FGF21) in mice. Hence, pharmacological inhibition of B⁰AT1 is expected to treat type-2 diabetes and related disorder. In this study, rationally designed trifluoromethyl sulfonyl derivatives were identified as novel, potent and orally bioavailable B⁰AT1 inhibitors. Compound 39 was found to be nanomolar potent (IC₅₀: 0.035 µM) B⁰AT1 inhibitor with excellent pharmacokinetic profile (%F: 66) in mice and efficacious in vivo in diet induced obese (DIO) mice model.

The recycling regulation of sodium-hydrogen exchanger isoform 3(NHE3) in epithelial cells

As the main exchanger of electroneutral NaCl absorption, sodium-hydrogen exchanger isoform 3 (NHE3) circulates in the epithelial brush border (BB) and intracellular compartments in a multi-protein complex. The size of the NHE3 complex changes during rapid regulation events. Recycling regulation of NHE3 in epithelial cells can be roughly divided into three stages. First, when stimulated by Ca²⁺, cGMP, and cAMP-dependent signaling pathways, NHE3 is converted from an immobile complex found at the apical microvilli (MV) into an easily internalized and mobile form that relocates to a compartment near the base of the MV. Second, NHE3 is internalized by clathrin and albumin-dependent pathways into cytoplasmic endosomal compartments, where the complex is reprocessed and reassembled. Finally, NHE3 is translocated from the recycling endosomes (REs) to the apex of epithelial cells, a process that can be stimulated by an increase in sodium-glucose cotransporter 1 (SGLT1) activity, epidermal growth factor receptor (EGFR) signaling, Ca²⁺ signaling, and binding to βPix and SH3 and multiple ankyrin repeat domains 2 (Shank2) proteins. This review describes the molecular steps and protein interactions involved in the recycling movement of NHE3 from the apex of epithelial cells, into vesicles, where it is reprocessed and reassembled, and returned to its original location on the plasma membrane, where it exerts its physiological function.

Amino Acid Homeostasis in Mammalian Cells with a Focus on Amino Acid Transport

Amino acid homeostasis is maintained by import, export, oxidation, and synthesis of nonessential amino acids, and by the synthesis and breakdown of protein. These processes work in conjunction with regulatory elements that sense amino acids or their metabolites. During and after nutrient intake, amino acid homeostasis is dominated by autoregulatory processes such as transport and oxidation of excess amino acids. Amino acid deprivation triggers processes such as autophagy and the execution of broader transcriptional programs to maintain plasma amino acid concentrations. Amino acid transport plays a crucial role in the absorption of amino acids in the intestine, the distribution of amino acids across cells and organs, the recycling of amino acids in the kidney, and the recycling of amino acids after protein breakdown.

IAF, QGF, and QDF Peptides Exhibit Cholesterol-Lowering Activity through a Statin-like HMG-CoA Reductase Regulation Mechanism: In Silico and In Vitro Approach

In this study, in silico approaches are employed to investigate the binding mechanism of peptides derived from cowpea β-vignin and HMG-CoA reductase. With the obtained information, we designed synthetic peptides to evaluate their in vitro enzyme inhibitory activity. In vitro, the total protein extract and <3 kDa fraction, at 5000 µg, support this hypothesis (95% and 90% inhibition of HMG-CoA reductase, respectively). Ile-Ala-Phe, Gln-Gly-Phe, and Gln-Asp-Phe peptides were predicted to bind to the substrate binding site of HMGCR via HMG-CoAR. In silico, it was established that the mechanism of HMG-CoA reductase inhibition largely entailed mimicking the interactions of the decalin ring of simvastatin and via H-bonding; in vitro studies corroborated the predictions, whereby the HMG-CoA reductase activity was decreased by 69%, 77%, and 78%, respectively. Our results suggest that Ile-Ala-Phe, Gln-Gly-Phe, and Gln-Asp-Phe peptides derived from cowpea β-vignin have the potential to lower cholesterol synthesis through a statin-like regulation mechanism.

The impact of collagen protein ingestion on musculoskeletal connective tissue remodeling: a narrative review

Collagen is the central structural component of extracellular connective tissue, which provides elastic qualities to tissues. For skeletal muscle, extracellular connective tissue transmits contractile force to the tendons and bones. Connective tissue proteins are in a constant state of remodeling and have been shown to express a high level of plasticity. Dietary-protein ingestion increases muscle protein synthesis rates. High-quality, rapidly digestible proteins are generally considered the preferred protein source to maximally stimulate myofibrillar (contractile) protein synthesis rates. In contrast, recent evidence demonstrates that protein ingestion does not increase muscle connective tissue protein synthesis. The absence of an increase in muscle connective tissue protein synthesis after protein ingestion may be explained by insufficient provision of glycine and/or proline. Dietary collagen contains large amounts of glycine and proline and, therefore, has been proposed to provide the precursors required to facilitate connective tissue protein synthesis. This literature review provides a comprehensive evaluation of the current knowledge on the proposed benefits of dietary collagen consumption to stimulate connective tissue remodeling to improve health and functional performance.

Learning of food preferences: mechanisms and implications for obesity & metabolic diseases

Omnivores, including rodents and humans, compose their diets from a wide variety of potential foods. Beyond the guidance of a few basic orosensory biases such as attraction to sweet and avoidance of bitter, they have limited innate dietary knowledge and must learn to prefer foods based on their flavors and postoral effects. This review focuses on postoral nutrient sensing and signaling as an essential part of the reward system that shapes preferences for the associated flavors of foods. We discuss the extensive array of sensors in the gastrointestinal system and the vagal pathways conveying information about ingested nutrients to the brain. Earlier studies of vagal contributions were limited by nonselective methods that could not easily distinguish the contributions of subsets of vagal afferents. Recent advances in technique have generated substantial new details on sugar- and fat-responsive signaling pathways. We explain methods for conditioning flavor preferences and their use in evaluating gut-brain communication. The SGLT1 intestinal sugar sensor is important in sugar conditioning; the critical sensors for fat are less certain, though GPR40 and 120 fatty acid sensors have been implicated. Ongoing work points to particular vagal pathways to brain reward areas. An implication for obesity treatment is that bariatric surgery may alter vagal function.

Growth Hormone Overexpression Induces Hyperphagia and Intestinal Morphophysiological Adaptations to Improve Nutrient Uptake in Zebrafish

The excess of circulating growth hormone (GH) in most transgenic animals implies mandatory growth resulting in higher metabolic demand. Considering that the intestine is the main organ responsible for the digestion, absorption, and direction of dietary nutrients to other tissues, this study aimed to investigate the mechanisms by which gh overexpression modulates the intestine to support higher growth. For this purpose, we designed an 8-weeks feeding trial to evaluate growth parameters, feed intake, and intestinal morphometric indices in the adult gh-transgenic zebrafish (Danio rerio) model. To access the sensitivity of the intestine to the excess of circulating GH, the messenger RNA (mRNA) expression of intestine GH receptors (GHRs) (ghra and ghrb) was analyzed. In addition, the expression of insulin-like growth factor 1a (igf1a) and genes encoding for di and tripeptide transporters (pept1a and pept1b) were assessed. Gh-transgenic zebrafish had better growth performance and higher feed intake compared to non-transgenic sibling controls. Chronic excess of GH upregulates the expression of its cognate receptor (ghrb) and the main growth factor related to trophic effects in the intestine (igf1a). Moreover, transgenic zebrafish showed an increased intestinal absorptive area and higher expression of crucial genes related to the absorption of products from meal protein degradation. These results reinforce the ability of GH to modulate intestinal morphology and the mechanisms of assimilation of nutrients to sustain the energy demand for the continuous growth induced by the excess of circulating GH.

Onset of nutrient consumption during early life stage digestive system development of two tuna species (Thunnus orientalis and Thunnus albacares)

To specify the timing of exogenous nutrient consumption in the larvae of two commercially important tuna species, the Pacific bluefin tuna (PBF) Thunnus orientalis and the yellowfin tuna (YFT) Thunnus albacares, the gene expressions of peptide transporter 1 (PEPT1) were examined. The mRNA expressions of PEPT1 first occurred at 2 days post hatching (dph) in PBF larvae and 3 dph for the YFT, and PEPT1 was found to only be expressed in the intestinal tract. The histological changes of the digestive tract of the YFT larvae were observed and compared to PBF larvae from a previous study. The intestines were developed at the hatching day for both species. It was found that the developmental timing of internal organs differed between the species, with the YFT showing an approximately one-day delay. The major organs such as liver, pancreas and gall bladder that excrete digestive enzymes appeared at 1 dph for PBF and 2 dph for YFT. The development of external morphological features was similar to organ development timings, with mouth-opening and first feeding starting at 2 dph for PBF, and 3 dph for YFT. Growth during the first month is rapid and variable for both species, ranging from 1.06 to 1.56 mm/d. Our findings provide new information about the early onset of feeding and larval development for the two species which would contribute to future aquaculture.

KFP-1, a Novel Calcium-Binding Peptide Isolated from Kefir, Promotes Calcium Influx Through TRPV6 Channels

INTRODUCTION

Kefir is an acidic and alcoholic fermented milk product with multiple health-promoting benefits. A previous study demonstrated that kefir enhanced calcium absorption in intestinal Caco-2 cells. In this study, kefir-fermented peptide-1 (KFP-1) is isolated from the kefir peptide fraction, and its function as a calcium-binding peptide is characterized.

METHODS AND RESULTS

KFP-1 was identified as a 17-residue peptide with a sequence identical to that of κ-casein (residues 138-154) in milk protein. KFP-1 is demonstrated to promote calcium influx in Caco-2 and IEC-6 small intestinal cells in a concentration-dependent manner. TRPV6, but not L-type voltage-gated calcium channels, is associated with the calcium influx induced by KFP-1. An in vitro calcium binding assay indicates that the full-length KFP-1 peptide has a higher calcium-binding capacity than the two truncated KFP-1 peptides, KFP-1∆C5 and KFP-1C5. Alexa Fluor 594 labeling shows that KFP-1 is taken up by Caco-2 cells and interacts with calcium ions and TRPV6 protein. Moreover, KFP-1 is found moderately resistant to pepsin and pancreatin digestions and enhanced calcium uptake by intestinal enterocytes in vivo.

CONCLUSION

These data suggest that KFP-1, a novel calcium-binding peptide, binds extracellular calcium ions and enters Caco-2 and IEC-6 cells, and promotes calcium uptake through TRPV6 calcium channels. The present study is of great importance for developing kefir-derived metal ion-binding peptides as functional nutraceutical additives.

The Dynamic Conversion of Dietary Protein and Amino Acids into Chicken-Meat Protein

This review considers the conversion of dietary protein and amino acids into chicken-meat protein and seeks to identify strategies whereby this transition may be enhanced. Viable alternatives to soybean meal would be advantageous but the increasing availability of non-bound amino acids is providing the opportunity to develop reduced-crude protein (CP) diets, to promote the sustainability of the chicken-meat industry and is the focus of this review. Digestion of protein and intestinal uptakes of amino acids is critical to broiler growth performance. However, the transition of amino acids across enterocytes of the gut mucosa is complicated by their entry into either anabolic or catabolic pathways, which reduces their post-enteral availability. Both amino acids and glucose are catabolised in enterocytes to meet the energy needs of the gut. Therefore, starch and protein digestive dynamics and the possible manipulation of this 'catabolic ratio' assume importance. Finally, net deposition of protein in skeletal muscle is governed by the synchronised availability of amino acids and glucose at sites of protein deposition. There is a real need for more fundamental and applied research targeting areas where our knowledge is lacking relative to other animal species to enhance the conversion of dietary protein and amino acids into chicken-meat protein.