Effects of dietary hydroxyproline on collagen metabolism, proline 4-hydroxylase activity, and expression of related gene in swim bladder of juvenile Nibea diacanthus

Effect of faba bean Vicia faba L. water/alcohol extract on growth performance, antioxidant capacity, textural properties, and collagen deposition in the swim bladder of juvenile Nibea coibor

Faba bean has gained attention as a cost-effective protein source with the potential to enhance product quality (texture properties, collagen content, etc.) in fish. However, its anti-nutrition factor, high feed conversion ratio, poor growth performance, etc. limit the widely application as a dietary source, especially in carnivorous fish. The water or alcohol extract of faba bean might resolve the problem. In this study, the juvenile Nibea coibor, known for their high-protein, large-sized, and high-grade swim bladder, were fed with seven isoproteic and isolipid experimental diets with the additive of faba bean water extract (1.25%, 2.5%, and 5%) or faba bean alcohol extract (0.9%, 1.8%, and 3.6%), with a control group without faba bean extract. After the 10-week feeding trail, the growth, antioxidant capacity, textural properties, and collagen deposition of the swim bladder were analyzed. Results showed that the 1.25% faba bean water extract group could significantly promote growth, textural quality of the swim bladder, and have beneficial effects on antioxidant response of fish. Conversely, dietary supplementation of faba bean alcohol extract resulted in reduced growth performance in a dose-dependent manner. Furthermore, fish fed diet with 1.25% faba bean water extract exhibited increased collagen content and upregulated collagen-related gene expression in the swim bladder, which was consistent with the Masson stain analysis for collagen fiber. Our results suggested that the anti-nutrient factor and bioactive component of faba bean may mainly be enriched in alcohol extract and water extract of faba bean, respectively. Besides, the appropriate addition of water extract of faba bean may improve the texture quality of the swim bladder by promoting collagen deposition. This study would provide a theoretical basis for the formulated diets with faba bean extract to promote product quality of marine fish.

Pulsed electrical stimulation and amino acid derivatives promote collagen gene expression in human dermal fibroblasts

Several collagen types are important for maintaining skin structure and function. Previous reports show that l-hydroxyproline (Hyp), N-acetyl-l-hydroxyproline (AHyp), and l-alanyl-l-glutamine (Aln-Gln) are biological active substances with collagen synthesis-promoting effects. In this study, we combined the promotive effects of pulsed electrical stimulation (PES) with three amino acid derivatives in human dermal fibroblasts. Fibroblasts were exposed to PES with a 4,800 Hz pulse frequency and a voltage at 1 or 5 V for 15 min. The gene expression of type I and III collagen (fibrillar collagen), type IV and VII collagen (basement membrane collagen and anchoring fibril collagen) were measured by RT-PCR 48 h after PES. PES alone promoted the expression of COL1A1 and COL3A1 at 5 V but did not alter that of COL4A1 and COL7A1. Each AAD and the AAD mixture promoted the expression of COL4A1 and COL7A1 but either repressed, or did not alter, that of COL1A1 and COL3A1. Compared to treatment with each AAD, PES at 5 V with Hyp promoted the expression of COL1A1 and COL3A1, enhanced COL3A1 expression with AHyp, and stimulated COL3A1 expression with Aln-Gln, while COL4A1 and COL7A1 expressions were not affected. PES and the AAD mixture significantly promoted COL4A1 expression in a voltage-dependent manner, and COL1A1 and COL3A1 demonstrated a similar but nonsignificant trend, whereas COL7A1 expression was not affected. The combination of PES with each AAD or the AAD mixture may improve skin structure and function by increasing the expression of basement membrane collagen and dermal fibrillar collagen.

Dietary Supplementation With Hydroxyproline Enhances Growth Performance, Collagen Synthesis and Muscle Quality of Carassius auratus Triploid

An eight-week experiment was undertaken to examine the effect of dietary hydroxyproline (Hyp) supplementation on growth performance, collagen synthesis, muscle quality of an improved triploid crucian carp (Carassius auratus Triploid) (ITCC). Six isonitrogenous (340 g/kg diet), isolipidic (60 g/kg diet) and isocaloric (17.80 MJ/kg diet) diets were formulated containing a certain amount of Hyp: 0.09% (the control group), 0.39, 0.76, 1.14, 1.53 and 1.90%. Each diet was randomly assigned to three tanks and each group was fed two times daily until apparent satiation. The results showed that growth performance and feed utilization of ITCC were significantly improved with the dietary Hyp level was increased from 0.09 to 0.76%. Crude protein, threonine and arginine content in the dorsal muscle in 0.76% hydroxyproline group were significantly higher than those in basic diet group (p < 0.05). The muscle textural characteristics increased remarkably with the amount of Hyp in the diet rising from 0.09 to 1.53% (p < 0.05). Meanwhile, the contents of type I collagen (Col I) and Pyridinium crosslink (PYD) in the muscle of fish were significantly increased by dietary Hyp (p < 0.05). The muscle fiber diameter and density of the fish were significantly increased when fed with 0.76% Hyp (p < 0.05). Furthermore, dietary supplementation with an appropriate concentration of Hyp substantially increased the expression of genes involved in collagen synthesis (col1a1, col1a2, p4hα1, p4hβ, smad4, smad5, smad9, and tgf-β) and muscle growth (igf-1, tor, myod, myf5, and myhc) (p < 0.05). In conclusion, dietary supplementation of Hyp can enhance fish growth performance, collagen production, muscle textural characteristics and muscle growth of ITCC. According to the SGR broken-line analysis, the recommended supplementation level of Hyp was 0.74% in the diet for ITCC, corresponding to 2.2% of dietary protein.

Cloning, tissue distribution and mRNA expression of type I collagen alpha 1 gene from Chu's croaker (Nibea coibor)

The demand for collagen has been increasing over years due to its wide application in food, cosmetics and biomedicine industries. The synthesis of collagen protein in fish depends on instructions provided by collagen, type I, alpha 1 (COL1A1) gene. However, cloning, tissue distribution and mRNA expression of COL1A1 gene in a gel-producing Chu's croaker (Nibea coibor) is currently unknown. This study cloned the cDNA of COL1A1 gene (GenBank accession number: MK641512) from six N. coibor fish. The distribution and mRNA expression pattern of COL1A1 was analyzed in eight tissues of N. coibor. The COL1A1 cDNA had a full length of 6130 bp and contained a 4344 bp open reading frame (ORF) encoding a polypeptide of 1448 amino acids. The homology of N. coibor COL1A1 amino acid had 98% similarity with Larimichthys crocea, indicating conservatism with other members in same family (Sciaenidae). The deduced polypeptide contained the same signal peptides, C-propeptide and N-propeptide domains, and triple helix domains, which are the characteristics of type I collagen in vertebrates. The mRNA of COL1A1 gene was expressed significantly higher in the spine of N. coibor than in all other tissues (P < 0.05), followed by swim bladder, skin and scales. The swim bladder had higher collagen and hydroxyproline contents than other tissues, followed by spine >, scales > and > skin (P < 0.05). Our study successfully cloned the COL1A1 gene from N. coibor for the first time. The COL1A1 gene contained all the features of collagen pro-α1(I) chain proteins, and shared high homology with other marine teleost. COL1A1 gene in N. coibor is highly expressed in spine and swim bladder, consistent with collagen distribution. Our study contributes to better understanding on collagen biosynthesis in N. coibor tissues for various industrial uses.

The TOR pathway participates in the regulation of growth development in juvenile spotted drum (Nibea diacanthus) under different dietary hydroxyproline supplementation

Commonly used aquatic feed naturally contains low-level or no hydroxyproline (Hyp). This study was conducted to evaluate the effects of dietary Hyp inclusion on growth performance, body composition, amino acid profiles, blood biochemistry, and the expression of target of rapamycin (TOR) pathway-related genes in juvenile Nibea diacanthus. Fish with similar size (initial body weight, 133.00 ± 2.14 g) were fed six isonitrogenous and isolipidic practical diets supplemented with graded levels of Hyp (0, 5, 10, 15, 20, and 25 g kg^-1 of dry matter) for 8 weeks. The results indicated that growth performance and feed utilization were improved with increased levels of dietary Hyp (P < 0.05), and the optimum amount of dietary Hyp estimated from SGR as 16.6 g kg^-1. The crude protein of whole body and swim bladder and the amino acid composition of muscle and swim bladder were significantly (P < 0.05) affected by the addition of dietary Hyp, which reflects the important role of feed composition in animal body composition. In addition, the expression levels of mammalian target of rapamycin (TOR) and ribosomal protein S6 kinase1 (S6K1) genes in the liver, muscle, and swim bladder increased with increasing Hyp content of diets, while the mRNA expression level of eukaryotic translation initiation factor 4E-binding protein (4E-BP) gene in these tissues decreased. These results indicated that Hyp improved fish growth and the ability to synthesize proteins, most likely through the TOR pathway. It is suggested that dietary Hyp supplementation is particularly necessary for application in aquatic feed.