Raja Kenojei Research Articles

Genotoxicity evaluation of collagen peptide derived from skate (Raja kenojei) skin: In vitro and in vivo studies

Genotoxicity evaluation of collagen peptide derived from skate (Raja kenojei) skin: In vitro and in vivo studies

Toxicity of a 90-day repeated oral dose of a collagen peptide derived from skate (Raja kenojei) skin: a rat model study.

Collagen peptides are widely employed as therapeutic materials due to their numerous beneficial properties, including for the following uses: antiaging, antioxidant applications, antibacterial applications, wound healing, tissue engineering, medication delivery, and cosmetics. Although collagen peptides are useful in these applications, to our knowledge, few published studies have been undertaken on their repeated-dose toxicity. We evaluated the possible subchronic toxicity of a collagen peptide derived from skate (Raja kenojei) skin (CPSS) in Sprague-Dawley rats by administering repeated oral doses over 90 days. Rats of both sexes were assigned randomly to one of four experimental groups, respectively receiving 0, 500, 1000, or 2000mg/kg/day of CPSS. At all doses tested, repeated oral CPSS administration had no treatment-related adverse effects in terms of clinical signs, body weight, food consumption, detailed clinical observation, sensory reactivity, functional assessment, urinalysis, ophthalmic examination, gross pathology, hematology, serum biochemistry, hormone analysis, organ weight, and histopathology. Even though there were some alterations in hematologic parameters, serum biochemistry parameters, organ weight, and histopathological findings, these did not follow a dose-response pattern and were within historical limits for control rats. The oral no-observed-adverse-effect level (NOAEL) of the CPSS was 2000mg/kg/day for both male and female rats in the applied experimental circumstances, and no target organs were identified.

Protein degradation and texture properties of skate (Raja kenojei) muscle during fermentation.

This study aimed at providing new insights into protein degradation and associated textural properties of skate (Raja kenojei) muscles. The pH and ammonia content of skate muscle were found to increase with an increase in fermentation time. During the initial phase of fermentation, the skate muscle hardened prior to demonstrating a spike in its pH and ammonia content. Protein characterization of the skate myofibrils revealed that the high proteins degraded into low molecular peptides, resulting in an increase in the hydrophobic interactions of these myofibrillar protein during fermentation. Consequently, the springiness of the skate muscles significantly (p < 0.05) decreased. Consequently, the textural profile of skate muscle during fermentation has a strong correlation with fermentation time and protein degradation.

Structure-function relationship of fermented skate skin gelatin-derived bioactive peptides: a peptidomics approach.

The online version contains supplementary material available at 10.1007/s10068-021-00998-6.

Effect of Oral Ingestion of Low-Molecular Collagen Peptides Derived from Skate (Raja Kenojei) Skin on Body Fat in Overweight Adults: A Randomized, Double-Blind, Placebo-Controlled Trial.

Recent animal studies found the potential of a collagen peptide derived from skate skin to have anti-obesity effects through the suppression of fat accumulation and regulation of lipid metabolism. However, no studies have yet been performed in humans. Here, this very first human randomized, placebo-controlled, and double-blinded study was designed to investigate the efficacy and tolerability of skate skin collagen peptides (SCP) for the reduction of body fat in overweight adults. Ninety healthy volunteers (17 men) aged 41.2 ± 10.4 years with a mean body mass index of 25.6 ± 1.9 kg/m2 were assigned to the intervention group (IG), which received 2000 mg of SCP per day or to the control group (CG) given the placebo for 12 weeks and 81 (90%) participants completed the study. Changes in body fat were evaluated using dual energy X-ray absorptiometry as a primary efficacy endpoint. After 12 weeks of the trial, the percentage of body fat and body fat mass (kg) in IG were found to be significantly better than those of subjects in CG (−1.2% vs. 2.7%, p = 0.024 and −1.2 kg vs. 0.3 kg, p = 0.025). Application of SCP was well tolerated and no notable adverse effect was reported from both groups. These results suggest the beneficial potential of SCP in the reduction of body fat in overweight adults.

Isolation and identification of hyper-ammonia-producing bacteria from commercial fermented skates (Raja kenojei).

Ammonia-producing bacteria were isolated and identified from five commercial fermented skates (A1, A2, A3, A4, and A5). In addition, the pH, ammonia nitrogen, total volatile nitrogen (TVBN), trimethylamine nitrogen (TMAN), and amino nitrogen contents of skate samples were also determined. A total of 88 strains of ammonia-producing bacteria was isolated and seven hyper-ammonia-producing bacteria isolates (A2-2, A2-3, A2-12, A2-18, A2-20, A3-6 and A3-14) were selected based on ammonia nitrogen producing ability. Those isolates were identified as Proteus hauseri (three strains), Providencia rustigianii (three strains), and Kurthia gibsonii. The pH and ammonia nitrogen content in skate samples were ranged from 8.63 to 9.03, and 4.86 to 7.31g/kg, respectively. No significant difference of pH values was observed in skate samples A2, A3, A4 and A5. While, skate samples A3, A4 and A5 showed similar level of TVBN and TMAN content. Skate sample A2 showed the highest amino nitrogen content among all samples, which indicated the highest degree of protein degradation of skate muscle during fermentation. Bivariate cluster analysis showed that skate samples A3, A4, and A5 clustered together at a relatively high level, implying a similar microbial environment during fermentation. The cluster analysis allowed different commercial fermented skates to be clearly differentiated based on the characteristics determined in this study. This study can provide important information for investigating the mechanisms underlying ammonia flavor formation in skate muscle during fermentation.

Anti-Obesity Effects of Collagen Peptide Derived from Skate (Raja kenojei) Skin Through Regulation of Lipid Metabolism.

This study investigated the anti-obesity effects of collagen peptide derived from skate skin on lipid metabolism in high-fat diet (HFD)-fed mice. All C57BL6/J male mice were fed a HFD with 60% kcal fat except for mice in the normal group which were fed a chow diet. The collagen-fed groups received collagen peptide (1050 Da) orally (100, 200, or 300 mg/kg body weight per day) by gavage, whereas the normal and control groups were given water (n = 9 per group). The body weight gain and visceral adipose tissue weight were lower in the collagen-fed groups than in the control group (p < 0.05). Plasma and hepatic lipid levels were significantly reduced by downregulating the hepatic protein expression levels for fatty acid synthesis (sterol regulatory element binding protein-1 (SREBP-1), fatty acid synthase (FAS), and acetyl-CoA carboxylase (ACC)) and cholesterol synthesis (SREBP-2 and 3-hydroxy-3-methylglutaryl-CoA reductase (HMGCR)) and upregulating those for β-oxidation (peroxisome proliferator-activated receptor alpha (PPAR-α) and carnitine palmitoyltransferase 1 (CPT1)) and synthesis of bile acid (cytochrome P450 family 7 subfamily A member 1 (CYP7A1)) (p < 0.05). In the collagen-fed groups, the hepatic protein expression level of phosphorylated 5′ adenosine monophosphate-activated protein kinase (p-AMPK) and plasma adiponectin levels were higher, and the leptin level was lower (p < 0.05). Histological analysis revealed that collagen treatment suppressed hepatic lipid accumulation and reduced the lipid droplet size in the adipose tissue. These effects were increased in a dose-dependent manner. The findings indicated that skate collagen peptide has anti-obesity effects through suppression of fat accumulation and regulation of lipid metabolism.

Evaluation of gas freshness indicator for determination of skate (Raja kenojei) quality during storage

A gas freshness indicator consisting of the pH-sensitive dye bromothymol blue-phenol red (BTB-PR) was investigated for visible color changes of fish product quality based on the quantity of volatile amines. Chromaticity values of the gas indicator accurately tracked an increase in the ammonia content in the packaging headspace of fish products, especially skate (Raja kenojei). Gradual color changes of the gas indicator response correlated with the quality of fish including pH values during storage. Ammonia content was evaluated during the fish storage using headspace solid-phase microextraction analysis with gas chromatography-flame ionization detection. The validation results suggested that good linearity (R²=0.99) and recovery of 84.00%. The limits of detection and quantification were 8.70 and 26.30 mg/L, respectively. A pH values of skate and chromaticity of gas indicator were measured and the correlation with ammonia content was evaluated. Results of this study could prove the application of gas indicator as intelligent package for improvement of food safety.

Development of freshness indicator for quality of skate (Raja kenojei) during storage.

There is much interest in the fishery industry in developing freshness indicator which can reflect the storage history of products and their quality. Freshness is one of the main considerations for the fishery industry and consumption. In this study, a freshness indicator of fish products, especially skate (Raja kenojei), was developed. The release of amines especially ammonia from decomposing fish is concentrated in headspace and they can be detected by pH-sensitive sensor unit. The sensor unit was organized with polymer matrix solution, which contains bromothymol blue-phenol red as pHsensitive dye to monitor visible color changes from yellow to purple. We investigated the sensor unit formulation, which responds to the ammonia formation in fish products. The color change of the sensor unit was evaluated as well as the selection of the proper weight of fish products and packaging material. Results will be useful to establish a basis for development of a freshness indicator and to determine the suitability of freshness indicator formulations for intelligent food packaging applications.

Physicochemical changes in kimchi containing skate (Raja kenojei) pretreated with organic acids during fermentation.

The effects of supplementing kimchi with acetic acid (TSA)- and citric acid (TSC)-treated skate were investigated during the fermentation process. The chemical and microbiological properties of the product were also investigated. The quality parameters of kimchi were determined by measuring the pH, titratable acidity, reducing sugar content, volatile basic nitrogen (VBN), biogenic amines (BAs), and microbial analysis. During fermentation, the kimchi containing skate was observed to have a lower acidity than the control. Treatment of skate with an organic acid increased the acidity and gradually decreased the reducing sugar content during fermentation. Higher concentrations of organic acid resulted in a decrease in VBN and BAs in the TSA and TSC groups compared to those in the kimchi containing skate. The results suggest that supplementing kimchi with skate treated with organic acids affects the histamine content of the products.

Effect of added skate (Raja kenojei) on the quality characteristics of steamed fish meat paste

The effect of added skate (Raja kenojei) on the quality characteristics of steamed fish meat paste was investigated. With different levels of added skate (0, 20, 40, and 60%), the moisture content, pH, and b values of steamed fish meat paste with added skate (SFMPS) significantly (p<0.05), increased, while the cohesiveness chewiness, and brittleness scores obtained from texture analysis all significantly (p<0.05), decreased, compared with control samples. Preference testing showed that brownness, smoothness, and skate flavor scores significantly (p<0.001) increased with addition of skate, compared with control samples, and the overall preference score was highest for 20% SFMPS samples. The amino acid contents of 20% SFMPS samples, which had the highest overall preference scores, were significantly (p<0.05) higher than for control samples. Addition of 20% skate was optimal for SFMPS for improving the quality characteristics of steamed fish meat paste with a higher protein content.

Nutritional Composition Changes in Skate (Raja kenojei) during Different Ripening Periods

In order to suggest fundamental data on the nutritional composition of the Korean traditional food, ripened skate, this study investigated the proximate composition, organic acid, free sugar, fatty acid, total amino acid, and macromolecule levels of skates at different ripening periods. Longer ripening periods resulted in decreased moisture levels and increased protein and ash levels. The total organic acid content increased until the 15th day of ripening, but decreased at 20 days. Phosphoric acid, oxalic acid, and lactic acid were the dominant organic acids. Eight free sugars were detected, ribose, glucose, and sucrose being the dominant forms, which significantly decreased with ripening. Palmitic and lignoceric acid were abundant in saturated fatty acids, oleic acid and palmitoleic acid were abundant in monounsaturated fatty acids, and linolenic acid, docosahexenoic acid, and arachidonic acid were abundant in polyunsaturated fatty acids. The major amino acids were glutamic acid, lysine, aspartic acid, and leucine and the total levels increased with ripening. The most abundant free amino acids were urea, sarcosine, taurine, and β-alanine, which decreased with ripening. Phosphoserine, phosphoethanolamine, α-aminobutyric acid, and cysteine levels increased.

Effect of processing conditions on functional properties of collagen powder from skate (Raja kenojei) skins

Optimum conditions for collagen extraction from skate (Raja kenojei) skins with various liming concentrations, extraction solution pH, extraction temperature and time, and functional properties were investigated. The optimum conditions for collagen extraction are as combination of place the skins in a lime solution of 0.15 N of NaOH, extract with 5 volumes water (pH 4.0) for 4 hr at 40°C, filter, centrifuge, and lyophilize to obtain collagen powder. The characteristics of skate skin collagen obtained under optimum extraction conditions were: solubility 82.7%, turbidity 0.28, and Hunter color L, a, and b values were 88.4, 0.92, and 11.2, respectively. On the other hand, the acidic pH values (3.0 and 5.0) of collagen were more resistant to precipitation upon extended heating.

Common Skate (Raja kenojei) Secretes Pentraxin into the Cutaneous Secretion: The First Skin Mucus Lectin in Cartilaginous Fish

A lactose-specific lectin with a molecular mass of about 25 kDa was purified from the skin mucus of a cartilaginous fish-the common skate (Raja kenojei). The complementary DNA sequence of the lectin was 1540 bp long and contained a reading frame encoding 226 amino acids, which showed approximately 38% identity to pentraxins of mammals and teleosts. Gene expression was observed in the skin, gill, stomach and intestine in the healthy skate. We also identified an isotype gene from the liver whose deduced amino-acid sequence shared 69.0% identity with the skin type gene. The antiserum detected protein in the skin, where the lectin is localized in the epidermal cells, and in the blood plasma. The lectin genes are multicopied in the common skate genome. Although pentraxins are acute phase proteins, mRNAs of both the isotypes were not upregulated after the in vivo challenge with formalin-killed Escherichia coli, which suggests that they are constantly present in the skin mucus and blood plasma to protect against pathogenic invasion. This lectin is the fifth type of lectin found in the cutaneous secretions of fish, demonstrating that skin mucus lectins have evolved with marked molecular diversity in fish.

한국 연안산 어류의 미네랄 함량 및 영양평가

To measure the mineral content of fishes, we collected 177 individuals from 53 fish species from the east (Pohang), west (Gunsan), and south (Tongyeong) coasts of Korea. The mean content of the macro mineral in a 100 g sample taken from the edible portion of each fish was (in descending order): P(207.4 mg), K(169.7 mg), Na(101.6 mg), Ca(44.4 mg), and Mg(30.4 mg). In comparison, the mean content of micro mineral in the fishes was (in descending order): Zn (<TEX>$8.98{\mu}g/g$</TEX>), Fe (<TEX>$5.03{\mu}g/g$</TEX>), Cu (<TEX>$0.76{\mu}g/g$</TEX>), Mn (<TEX>$0.43{\mu}g/g$</TEX>), and Ni (<TEX>$0.08{\mu}g/g$</TEX>). We could not observe clear regional variation in the mineral content of fish species. With regard to minerals considered essential for humans, the amount of Ca per sample (100 g) was the highest in the Scyliorhinus torazame (465.4 mg), and than followed by Ammodytes personatus (338.0 mg), Dasyatis akajei (267.4 mg), Raja kenojei (248.1 mg), Conger myriaster (174.1 mg), Clupanodon punctatus (86.8 mg), Muraenesox cinereus (81.2 mg), and Engraulis japonica (70.4 mg). The daily average intake of the mineral through the fishes consisted of P (100.6 mg), K (82.3 mg), Na (49.3 mg), Mg (14.8 mg), Zn (0.44 mg), Fe (0.24 mg), Cu (0.04 mg) and Mn (0.02 mg). The respective intakes of macro mineral (P, Mg, Na, Ca, K) from the fishes were about 14.4, 4.2, 3.3, 3.1 and 1.8% of the dietary reference intakes for Koreans (KDRIs) set by the Korean Nutrition Society. In comparison, the respective intakes of micro mineral (Cu, Zn, Fe, Mn) from the fishes were about 4.6, 4.4, 2.4, and 0.6% of the KDRIs.

A unique lectin identified in the cutaneous secretion of common skate (Raja kenojei), a cartilaginous fish

A unique lectin identified in the cutaneous secretion of common skate (Raja kenojei), a cartilaginous fish

CDNA cloning and characterization of Type V/XI procollagen α1 chain in the skate, Raja kenojei

The full-length cDNA of the Type V/XI procollagen α1 [pro-α1(V/XI)] chain was determined by the RACE technique, using a cDNA library constructed from the 4-week embryo of the skate, Raja kenojei. The expression property and phylogenetic analysis confirmed that the skate pro-α1(V/XI) chain was close to other vertebrate pro-α1(V) chains rather than pro-α1(XI) chains. The present study is the first evidence for the primary structure of full-length cDNA of the pro-α1(V/XI) chain in an elasmobranch.

Isolation and characterization of cDNA sequences of l-gulono-gamma-lactone oxidase, a key enzyme for biosynthesis of ascorbic acid, from extant primitive fish groups

Most advanced teleosts lack l-gulono-gamma-lactone oxidase (GULO), a key enzyme required for the biosynthesis of ascorbic acid. However, extant representatives of primitive species including sturgeon and many cartilaginous fishes, are exceptional in their ability to synthesize ascorbic acid de novo. In the present study, full-length GULO cDNAs were isolated from white sturgeon ( Acipenser transmontanus) and two shark species belonging to the Triakidae ( Triakis scyllium and Mustelus manazo). The open reading frames from all three species contained 440 amino acids and the deduced polypeptides had similar hydropathy profiles, predicted molecular masses and theoretical pI values. These GULO sequences exhibited high amino acid identity (67–97%) with each other, and also shared 61–71% identity with mammalian GULOs. Based on the GULO sequences obtained from these species, we developed degenerate primers for the isolation of partial GULO sequences by RT-PCR from other primitive species including another shark ( Mustelus griseus, Triakidae), a spiny dogfish ( Squalus acanthias, Squalidae), two ray species ( Raja kenojei, Rajidae and Dasyatis akajei, Dasyatidae) and four sturgeons ( Acipenser baeri, A. gueldenstaedtii, A. naccarii and A. ruthenus, Acipenseridae). Overall, sequence identities of these amplified GULO segments among primitive species were 63–99% at the nucleotide level and 67–100% at the amino acid level. Considerable numbers of amino acid residues were unique to either fish or mammals, and Acipenseriform species occupied an intermediate position, sharing several residues with either fish or mammalian GULOs. Phylogenetic analyses based on parsimony, distance and likelihood methods of both nucleotide and amino acid sequences resulted in trees that were in agreement with known taxonomy. The transcription and enzyme activity of GULO were kidney-specific when measured by biochemical assay and reverse transcription-PCR.

CDNA cloning and characterization of Type I procollagen α1 chain in the skate Raja kenojei

A full-length cDNA of the Type I procollagen α1 [pro-α1(I)] chain (4388 bp), coding for 1463 amino acid residues in the total length, was determined by RACE PCR using a cDNA library constructed from 4-week embryo of the skate Raja kenojei. The helical region of the skate pro-α1(I) chain consisted of 1014 amino acid residues — the same as other fibrillar collagen α chains from higher vertebrates. Comparison on denaturation temperatures of Type I collagens from the skate, rainbow trout ( Oncorhynchus mykiss) and rat ( Rattus norvegicus) revealed that the number of Gly-Pro-Pro and Gly-Gly in the α1(I) chains could be directly related to the thermal stability of the helix. The expression property of the skate pro-α1(I) chain mRNA and phylogenetic analysis with other vertebrate pro-α1(I) chains suggested that skate pro-α1(I) chain could be a precursor form of the skate Type I collagen α1 chain. The present study is the first evidence for the primary structure of full-length pro-α1(I) chain in an elasmobranch.

Purification and characterization of molecular species of collagen in the skin of skate ( Raja kenojei)

Two types, one major and the other minor, of collagen were obtained from pepsin-solubilized collagen of the skate ( Raja kenojei) skin. The major collagen was identified as Type I collagen because of a similar characteristic to those of Type I collagens from the skate muscle and cartilage. On the other hand, the SDS–PAGE pattern and peptide maps of the minor collagen were different from those of Type V and XI collagens of the skate muscle and cartilage, respectively. However, the minor collagen was similar, in amino acid composition, to Type V collagen from the skate muscle. These results suggest the existence of a molecular subspecies of Type V collagen in skate skin which is different from the muscle Type V collagen in primary structure or subunit composition.