Inosine Monophosphate Content Research Articles

Effect of different processing steps in the production of beer fish on volatile flavor profile and their precursors determined by HS-GC-IMS, HPLC, E-nose, and E-tongue

Beer fish is characterized by its distinctive spicy flavor and strong beer aroma. Currently, there is a lack of comprehensive research analyzing the changes in taste and volatile compounds that occur during the processing of beer fish. Thus, this study used HS-GC-IMS, electronic tongue, and electronic nose to investigate the changes in flavor components during various processing stages of beer fish. The obtained results were subsequently analyzed using multivariate statistical analysis. The results showed that the final beer fish product (SF) had the greatest amount of free amino acids (888.28 mg/100 g), with alanine, glutamic acid, and glycine contributing to the taste of SF. The inosine monophosphate (IMP) content of beer fish meat varied noticeably depending on processing stages, with deep-fried fish (FF) having the greatest IMP content (61.93 mg/100 g), followed by the final product (SF) and ultrasonic-cured fish (UF). A total of 67 volatiles were detected by GC-IMS, mainly consisting of aldehydes, ketones, and alcohols, of which aldehydes accounted for >37%, which had a great influence on the volatile flavor of beer fish. The flavor components' composition varied noticeably depending on the stage of processing. PLS-DA model screened 35 volatile flavor components (VIP > 1) as markers; the most significant differences were 1-propanethiol, isoamyl alcohol, ethanol, and eucalyptol. Ultrasonic processing, frying, and soaking sauce can significantly improve the formation of flavor compounds, resulting in a notable enhancement of the final beer fish's umami taste and overall flavor quality.

RNA-Seq Reveals Pathways Responsible for Meat Quality Characteristic Differences between Two Yunnan Indigenous Chicken Breeds and Commercial Broilers.

Poultry is a source of meat that is in great demand in the world. The quality of meat is an imperative point for shoppers. To explore the genes controlling meat quality characteristics, the growth and meat quality traits and muscle transcriptome of two indigenous Yunnan chicken breeds, Wuding chickens (WDs) and Daweishan mini chickens (MCs), were compared with Cobb broilers (CBs). The growth and meat quality characteristics of these two indigenous breeds were found to differ from CB. In particular, the crude fat (CF), inosine monophosphate content, amino acid (AA), and total fatty acid (TFA) content of WDs were significantly higher than those of CBs and MCs. In addition, it was found that MC pectoralis had 420 differentially expressed genes (DEGs) relative to CBs, and WDs had 217 DEGs relative to CBs. Among them, 105 DEGs were shared. The results of 10 selected genes were also confirmed by qPCR. The differentially expressed genes were six enriched Kyoto Encyclopedia of Genes and Genomes (KEGG) biological pathways including lysosomes, phagosomes, PPAR signaling pathways, cell adhesion molecules, cytokine-cytokine receptor interaction, and phagosome sphingolipid metabolism. Interestingly, four genes (LPL, GK, SCD, and FABP7) in the PPAR signal pathway related to fatty acid (FA) metabolism were elevated in WD muscles, which may account for higher CF, inosine monophosphate content, and AA and FA contents, key factors affecting meat quality. This work laid the foundation for improving the meat quality of Yunnan indigenous chickens, especially WD. In future molecular breeding, the genes in this study can be used as molecular screening markers and applied to the molecular breeding of chicken quality characteristics.

Effect of Specific Spoilage Organisms on the Degradation of ATP-Related Compounds in Vacuum-Packed Refrigerated Large Yellow Croaker (Larimichthys crocea).

This study examined the spoilage potential of specific spoilage organisms on the degradation of adenosine triphosphate (ATP)-related compounds in vacuum-packed refrigerated large yellow croaker. The total viable count (TVC), ATP-related compounds and related enzymes of vacuum-packed refrigerated large yellow croaker inoculated with different bacteria (Pseudomonas fluorescens and Shewanella putrefaciens) were characterized using the spread plate method, high-performance liquid chromatography and assay kits, respectively. Results indicated that the TVC for both control and Shewanella putrefaciens groups reached spoilage levels at days 9 and 15, respectively. The changes of adenosine triphosphate (ATP), adenosine diphosphate (ADP), adenosine monophosphate (AMP) and adenosine deaminase activity across all groups showed no significant difference attributable to microbial growth. The results suggested that ATP to inosine monophosphate (IMP) degradation primarily occurs via fish's endogenous enzymes, with minimal microbial involvement. On day 12, the IMP content in fillets inoculated with Pseudomonas fluorescens (0.93 μmol/g) was half higher than in those inoculated with Shewanella putrefaciens (0.57 μmol/g). Both spoilage organisms facilitated IMP degradation, with Shewanella putrefaciens making a more substantial contribution. Analysis of K values and correlation coefficients revealed that Shewanella putrefaciens was the primary factor in the freshness loss of refrigerated vacuum-packed large yellow croaker. These findings offer a reference for understanding quality changes in refrigerated large yellow croaker, especially regarding umami degradation at the microbial level.

PKM2 promotes myoblast growth and inosine monophosphate-specific deposition in Jingyuan chicken

Inosine monophosphate (IMP) is widely regarded as an important indicator for evaluating the flavour of poultry meat. However, little is known about the molecular mechanisms affecting the specific deposition of IMP. In this study, we functionally verified PKM2 (Pyruvate kinase M2), a candidate gene related to IMP synthesis, in order to reveal the important role of PKM2 in meat flavour and muscle development of Jingyuan chickens. The results showed that the IMP content in breast muscle of Jingyuan chickens was negatively correlated with PKM2 mRNA expression (r = −0.1710), while the IMP content in leg muscle was significantly positively correlated with PKM2 mRNA expression (r = 0.7350) (P < 0.05). During myogenesis, PKM2 promoted the proliferation rate of myoblasts and the expression of proliferation marker genes, inhibited the apoptosis rate and the expression of apoptosis marker genes, and decreased the expression of differentiation marker genes. Up-regulation of PKM2 enhanced the expression of key genes in the purine metabolic pathway and the de novo synthesis pathway of IMP, and suppressed the expression of key genes in the salvage pathway. ELISA assays showed that PKM2 decreased IMP and hypoxanthine (HX) contents, while adenosine triphosphate (ATP) and uric acid (UA) contents were clearly elevated. In summary, these studies revealed that PKM2 regulates myogenesis and specific deposition of IMP, which can be used to improve the quality of Jingyuan chicken meat.

Molecular characterization of adenosine monophosphate deaminase 1 and the correlation analysis between its mRNA expression levels and inosine monophosphate content in large yellow croaker (Larimichthys crocea)

Declining flesh quality has drawn considerable attention in the farmed large yellow croaker (LYC; Larimichthys crocea) industry. Inosine monophosphate (IMP) is the primary flavor substance in aquatic animals. Adenosine monophosphate deaminase 1 (AMPD1) plays a critical role in IMP formation by catalyzing the deamination of AMP to IMP in the purine nucleotide cycle. To further evaluate the correlation between ampd1 mRNA expression levels and IMP content in the LYC muscle tissue, the relevant open reading frame (ORF) of L. crocea (Lcampd1) was cloned, and the IMP content and Lcampd1 mRNA expression in the muscles of LYCs of different sizes were examined. The ORF cDNA of Lcampd1 was 2211 bp in length and encoded a polypeptide of 736 amino acids (AAs). The deduced protein, LcAMPD1, possesses conserved AMPD active regions (SLSTDDP) and shows high homology with AMPD proteins of other teleost fishes. The genomic DNA sequence of Lcampd1 exhibits a high degree of evolutionary conservation in terms of structural organization among species. Phylogenetic analysis of the deduced AA sequence revealed that teleost fish and mammalian AMPD1 were separate from each other and formed a cluster with AMPD3, suggesting that AMPD1 and AMPD3 arose by duplication of a common primordial gene. In healthy LYC, Lcampd1 mRNA was expressed only in the muscle tissue. The IMP content in the muscle of LYCs with different average body weights was measured by high-performance liquid chromatography; the results showed that the IMP content in the muscle of LYCs with greater body weight was significantly higher than that in LYC with lower body weight. Moreover, a similar trend in Lcampd1 expression was observed in these muscle tissues. The Pearson correlation analysis further showed that the Lcampd1 mRNA expression was positively correlated with IMP content in the muscles of different-sized LYCs. These results suggest the potential function of Lcampd1 in determining the IMP content in LYC and provide a theoretical basis for flesh quality improvement, as well as a scientific basis for the development of the molecular breeding of LYC.

Explorations on Key Module and Hub Genes Affecting IMP Content of Chicken Pectoralis Major Muscle Based on WGCNA

Inosine monophosphate (IMP) is a substance that enhances flavor and plays a crucial role in the umami taste of chicken muscle. It is also an influential factor in determining chicken’s economic value. However, the molecular regulatory network underlying the IMP content in muscle remains unclear. To address this issue, we performed transcriptome sequencing on 20 pectoralis major muscle samples from 120-day-old Guangde feathered-leg chicken and used weighted gene co-expression network analysis (WGCNA) to identify key regulatory factors that influence IMP content. The weighted gene co-expression network was constructed using a total of 16,344 genes, leading to the identification of 20 co-expression gene modules. Among the modules that were identified, it was observed that the purple module (R = −0.51, p = 0.02) showed a significant negative correlation with the IMP content. This suggests that the genes within the purple module had the ability to regulate the IMP content. A total of 68 hub genes were identified in the purple module through gene significance (GS) &gt; 0.2 and module membership (MM) &gt; 0.8. The STRING database was used for a protein–protein interaction (PPI) network of hub genes. Furthermore, troponin I type 1 (TNNI1), myozenin 2 (MYOZ2), myosin light chain 2 regulatory cardiac slow (MYL2), and myosin light chain 3 regulatory cardiac slow (MYL3) involved in the “ATP-dependent activity”, “cAMP signaling pathway” and “cGMP-PKG signaling pathway” were identified as central regulators that contribute to IMP content. These results offer valuable information into the gene expression and regulation that affects IMP content in muscle.

Functional identification of PGM1 in the regulating development and depositing of inosine monophosphate specific for myoblasts.

Inosine monophosphate (IMP) is naturally present in poultry muscle and plays a key role in improving meat flavour. However, IMP deposition is regulated by numerous genes and complex molecular networks. In order to excavate key candidate genes that may regulate IMP synthesis, we performed proteome and metabolome analyses on the leg muscle, compared to the breast muscle control of 180-day-old Jingyuan chickens (hens), which had different IMP content. The key candidate genes identified by a differential analysis were verified to be associated with regulation of IMP-specific deposition. The results showed that the differentially expressed (DE) proteins and metabolites jointly involve 14 metabolic pathways, among which the purine metabolic pathway closely related to IMP synthesis and metabolism is enriched with four DE proteins downregulated (with higher expression in breast muscles than in leg muscles), including adenylate kinase 1 (AK1), adenosine monophosphate deaminase 1 (AMPD1), pyruvate kinase muscle isoenzyme 2 (PKM2) and phosphoglucomutase 1 (PGM1), six DE metabolites, Hypoxanthine, Guanosine, L-Glutamine, AICAR, AMP and Adenylsuccinic acid. Analysis of PGM1 gene showed that the high expression of PGM1 promoted the proliferation and differentiation of myoblasts and inhibited the apoptosis of myoblasts. ELISA tests have shown that PGM1 reduced adenosine triphosphate (ATP) and IMP and uric acid (UA), while enhancing the biosynthesis of hypoxanthine (HX). In addition, up-regulation of PGM1 inhibited the expression of purine metabolism pathway related genes, and promoted the IMP de novo and salvage synthesis pathways. This study preliminarily explored the mechanism of action of PGM1 in regulating the growth and development of myoblasts and specific IMP deposition in Jingyuan chickens, which provided certain theoretical basis for the development and utilization of excellent traits in Jingyuan chickens.

Inosine 5′- monophosphate derived umami taste intensity of beef determination by electrochemistry and chromatography

The umami sensation contributes to beef taste and acceptability. Inosine 5′- monophosphate (IMP), the most abundant 5′-ribonucleotide in meat, is known to impart an umami taste without the undesired side effects commonly associated with glutamate. Nevertheless, the investigation of IMP's role in beef flavor has thus far been overlooked. Traditional methods for detecting IMP have relied on liquid chromatography coupled with ultraviolet spectroscopy or mass spectrometry techniques. However, these methods are not practical for production settings due to the complexity and resource demands of sophisticated laboratory techniques. Alternative methods like cyclic voltammetry might offer more practical solutions for rapidly detecting IMP. The objectives of this study were to evaluate the efficiency of using electrochemistry and chromatography on differentiating beef strips spiked with different IMP contents. The IMP threshold was 0.30 mM determined by a trained panel using the Best Estimates Threshold method. Beef strip steaks of USDA Prime, Choice, and Select were spiked at 0.30 and 0.60 mM of IMP, based on green weight and an estimated moisture content of 65%. In this study, differences in the IMP content of steaks were not detected by liquid chromatography-mass spectrometry. However, the cyclic voltammetry approach differentiated IMP concentrations at 0.50 mM or above in aqueous solutions and subsequentially meat extracts from the buffered blank solutions. In conclusion, cyclic voltammetry holds potential as a rapid and effective approach for detecting IMP in beef and other meat products, offering promising applications for future research.

Multi-Omics Reveals the Effect of Crossbreeding on Some Precursors of Flavor and Nutritional Quality of Pork.

Over the last several decades, China has continuously introduced Duroc boars and used them as breeding boars. Although this crossbreeding method has increased pork production, it has affected pork quality. Nowadays, one of the primary goals of industrial breeding and production systems is to enhance the quality of meat. This research analyzed the molecular mechanisms that control the quality of pork and may be used as a guide for future efforts to enhance meat quality. The genetic mechanisms of cross-breeding for meat quality improvement were investigated by combining transcriptome and metabolome analysis, using Chinese native Jiaxing black (JXB) pigs and crossbred Duroc × Duroc × Berkshire × JXB (DDBJ) pigs. In the longissimus Dorsi muscle, the content of inosine monophosphate, polyunsaturated fatty acid, and amino acids were considerably higher in JXB pigs in contrast with that of DDBJ pigs, whereas DDBJ pigs have remarkably greater levels of polyunsaturated fatty acids than JXB pigs. Differentially expressed genes (DEGs) and differential metabolites were identified using transcriptomic and metabolomic KEGG enrichment analyses. Differential metabolites mainly include amino acids, fatty acids, and phospholipids. In addition, several DEGs that may explain differences in meat quality between the two pig types were found, including genes associated with the metabolism of lipids (e.g., DGKA, LIPG, and LPINI), fatty acid (e.g., ELOVL5, ELOVL4, and ACAT2), and amino acid (e.g., SLC7A2, SLC7A4). Combined with the DEGS-enriched signaling pathways, the regulatory mechanisms related to amino acids, fatty acids, and phospholipids were mapped. The abundant metabolic pathways and DEGs may provide insight into the specific molecular mechanism that regulates meat quality. Optimizing the composition of fatty acids, phospholipids, amino acids, and other compounds in pork is conducive to improving meat quality. Overall, these findings will provide useful information and further groundwork for enhancing the meat quality that may be achieved via hybrid breeding.

Widely targeted metabolomics investigation of the meat taste of Eriocheir sinensis under ammonia exposure

Ammonia-nitrogen may accumulate in the aquaculture water of Eriocheir sinensis. This study investigated the effects of ammonia exposure during 48 h (0, 10.47, and 41.87 mg/L) on the meat taste of E. sinensis. Sensory analysis showed that the low-concentration ammonia group had the highest umami and the lowest bitterness scores. Metabolomics combined with quantitative analysis showed that ammonia increased the 5′-inosine monophosphate content and the equivalent umami concentration and reduced the arginine content, thereby enhancing umami and reducing crab meat bitterness. Exposure to high concentrations of ammonia reduced umami amino acids (glutamic acid and aspartic acid) and increased bitter amino acid levels (leucine, isoleucine, and tryptophan), which hindered the taste development of crab meat. The increased levels of sweet amino acids (glutamine and serine) in the high-concentration ammonia group may be key ammonia detoxification products. This study revealed that phospholipids and small peptides may participate in improving crab meat flavor after ammonia exposure.

Manifestation of Heat-Induced Valuable Dietary Nucleotide Salvage in Food Prepared from Aged Fish in Fast Protein and Metabolites Liquid Chromatography, ATP-Bioluminescence Assay, and NMR Spectra

Dietary nucleotides and nucleosides, primarily inosine monophosphate (IMP) and the adenine nucleotide pool (ANP), are widely considered as essential nutrients responsible for multiple biological functions. Food prepared from meat and fish is the main source of these substances in the human diet, and it is extremely important to implement storage and processing techniques ensuring their maximum preservation and even accumulation during maturation or conditioning. In experiments with freshly refrigerated grass carp and defrosted Alaska pollock fillets it was discovered, initially using Fast Protein and Metabolites Liquid Chromatography and the ATP-bioluminescence test, and afterwards validated by NMR spectroscopy, that heat treatment identical to conventional culinary processing in aqueous or wet media at temperatures above 62 °C leads to nucleotide salvage (recovery) in aged fish. A significant increase in the concentration of IMP, and even an emergence of ANP substances, were reliably demonstrated in fish samples which had already partially or fully lost these components during prolonged storage due to the ATP breakdown metabolic reactions. Owing to this recovery, the nutritive value of ready-to-eat food can be higher than was initially evaluated in raw products before heat treatment: an effect that should certainly be considered in practical nutrition. Moreover, it is necessary to reconsider the widely acknowledged system of indices of freshness based on nucleotides and nucleosides elaborated a long time ago for raw meat and fish products.

Transcriptome and co-expression network analysis reveals the molecular mechanism of inosine monophosphate-specific deposition in chicken muscle.

The inosine monophosphate (IMP) content in chicken meat is closely related to muscle quality and is an important factor affecting meat flavor. However, the molecular regulatory mechanisms underlying the IMP-specific deposition in muscle remain unclear. This study performed transcriptome analysis of muscle tissues from different parts, feeding methods, sexes, and breeds of 180-day-old Jingyuan chickens, combined with differential expression and weighted gene co-expression network analysis (WGCNA), to identify the functional genes that regulate IMP deposition. Out of the four comparison groups, 1,775, 409, 102, and 60 differentially expressed genes (DEGs) were identified, of which PDHA2, ACSS2, PGAM1, GAPDH, PGM1, GPI, and TPI1 may be involved in the anabolic process of muscle IMP in the form of energy metabolism or amino acid metabolism. WGCNA identified 11 biofunctional modules associated with IMP deposition. The brown, midnight blue, red, and yellow modules were strongly correlated with IMP and cooking loss (p < 0.05). Functional enrichment analysis showed that glycolysis/gluconeogenesis, arginine and proline metabolism, and pyruvate metabolism, regulated by PYCR1, SMOX, and ACSS2, were necessary for muscle IMP-specific deposition. In addition, combined analyses of DEGs and four WGCNA modules identified TGIF1 and THBS1 as potential candidate genes affecting IMP deposition in muscle. This study explored the functional genes that regulate muscle development and IMP synthesis from multiple perspectives, providing an important theoretical basis for improving the meat quality and molecular breeding of Jingyuan chickens.

Exploring the quality change mechanism of tea polyphenol-assisted cured grass carp from perspectives of physicochemical and flavor

ABSTRACT In this study, the quality changes of grass carp during tea polyphenol-assisted curing were studied from physicochemical and flavor perspectives. The addition of tea polyphenols has a positive effect on maintaining the water content of fish as the curing time increases (p < 0.05). The tea polyphenol-assisted treatment maintains the brightness of grass carp meat. The addition of tea polyphenols also slowed down the rate of pH growth and enhances the texture of grass carp (p < 0.05). The addition of tea polyphenols reduced His content, which had a positive effect on the taste of the cured grass carp products. When the pickling time reached 60 min, the inosine monophosphate content of tea polyphenol-treated groups was higher than that of the group soaked in salt only. Combined with equivalent umami concentration and taste activity values, it was found that the addition of 0.1% TP could improve freshness of grass carp cured products.

Fermented mixed feed regulates intestinal microbial community and metabolism and alters pork flavor and umami

This study aimed to determine the effects of fermented mixed feed (FMF) supplementation (0%, 5% and 10%) on the intestinal microbial community and metabolism, and the compositions of volatile flavor compounds and inosine monophosphate (IMP) contents in the longissimus thoracis. In this study, 144 finishing pigs (Duroc × Berkshire × Jiaxing Black) were randomly allocated to 3 groups with 4 replicate pens per group and 12 pigs per pen. The experiment lasted 38 days after 4 days of acclimation. The 16S rRNA gene sequences and an untargeted metabolomics analysis showed FMF altered the profiles of microbes and metabolites in the colon. Heracles flash GC e-nose analysis showed that 10% FMF (treatment 3) had a greater influence on the compositions of volatile flavor compounds than 5% FMF (treatment 2). Compared to 0% FMF (treatment 1), the contents of total aldehydes, (E,E)-2,4-nonadienal, dodecanal, nonanal and 2-decenal were significantly increased by treatment 3, and treatment 3 increased IMP concentrations and gene expressions related to its synthesis. Correlations analysis showed significantly different microbes and metabolites had strong correlations with the contents of IMP and volatile flavor compounds. In conclusion, treatment 3 regulated intestinal microbial community and metabolism, that in turn altered the compositions of volatile compounds, which contributed to improving pork flavor and umami.

Effects of β-glucan with vitamin E supplementation on the growth performance, blood profiles, immune response, pork quality, pork flavor, and economic benefit in growing and finishing pigs.

This study was conducted to evaluate the effects of β-glucan with vitamin E supplementation on the growth performance, blood profiles, immune response, pork quality, pork flavor, and economic benefit in growing and finishing pigs. A total of 140 growing pigs ([Yorkshire×Landrace]×Duroc) were assigned to five treatments considering sex and initial body weight (BW) in 4 replications with 7 pigs per pen in a randomized complete block design. The experimental diets included a corn-soybean meal-based basal diet with or without 0.05% or 0.1% β-glucan and 0.02% vitamin E. The pigs were fed the diets for 12 weeks (phase I, 0 to 3; phase II, 3 to 6; phase III, 6 to 9; phase IV, 9 to 12). The BW and feed intake were measured at the end of each phase. Blood samples were collected at the end of each phase. Four pigs from each treatment were selected and slaughtered for meat quality. Economic benefit was calculated considering the total feed intake and feed price. Pork flavor was analyzed through inosine monophosphate analysis. The average daily gain and feed efficiency were improved compared to the control when β-glucan or vitamin E was added. Supplementing 0.05% β-glucan significantly increased the lymphocyte concentration compared to the addition of 0.1% β-glucan and the content of vitamin E in the blood increased when 0.02% vitamin E was added. The treatment with 0.1% β-glucan and 0.02% vitamin E showed the most economic effect because it had the shortest days to market weight and the lowest total feed cost. The addition of β-glucan or vitamin E had a positive role in improving the flavor of pork when considering that the content of inosine monophosphate was increased. However, carcass traits and meat quality were not affected by β-glucan or vitamin E. The addition of 0.1% β-glucan with 0.02% vitamin E in growing and finishing pig diets showed great growth performance and economic effects by supplying vitamin E efficiently and by improving the health condition of pigs due to β-glucan.

Fast Protein and Metabolites (Nucleotides and Nucleosides) Liquid Chromatography Technique and Chemical Sensor for the Assessment of Fish and Meat Freshness

Fast protein and metabolite liquid chromatography (FPLMC) was introduced years ago to enable the easy separation of high-molecular compounds such as proteins from small molecules and the identification of the low-molecular substances. In this paper, the method is applied for the rapid evaluation of freshness and monitoring the aging of animal meat and fish. A novel chromatographic sensor was developed with a deep UV LED-based photometric detection unit (255–265 nm), an original flow cuvette and registration scheme; the processing of a chromatogram with the sensor takes approximately 15 min. Strict isochronism between the elution of ATP metabolites, mainly hypoxanthine (Hx) and inosine monophosphate (IMP), and the time of maturation of meat or fish, was discovered. A new freshness index H* = [Hx]/[IMP] was introduced, which is proportional to the instrumental delay time in the FPMLC chromatograms: the H* index &lt; 0.5 indicates the presence of inosine monophosphate (IMP) and the high quality of the meat or fish. Reasonably strong correlations were revealed between data obtained by FPMLC and total volatile basic nitrogen TVB-N (for fish) or volatile fatty acids VFA (for meat) content. Moreover, putative nucleotide salvage and an increase in the concentration of IMP were observed in fish after heat treatment using the FPMLC sensor and NMR technique.

Effects of composite mixture of protein sources in replacing fish meal on nutritional value and flavor quality of Pacific white shrimp (Litopenaeus vannamei)

An 8-week feeding trial was conducted to investigate the effects of fish meal partially or totally replaced with poultry by-product meal (PBM), antarctic krill meal (AKM), corn gluten meal (CGM), cottonseed meal (CM) and rice protein concentrate meal (RPM) on amino acids, fatty acids, nucleotides and volatile compounds of Pacific white shrimp (Litopenaeus vannamei). Results showed that shrimps fed with partial replacement of fish meal (50 %) with AKM and PBM (1:1) significantly increased the content of inosine monophosphate (IMP), the proportion of eicosapentaenoic acid (EPA), n-9 monounsaturated fatty acids (MUFAs), and significantly decreased the content of hypoxanthine (Hx), benzaldehyde, and the proportion of saturated fatty acids (SFAs). Dietary fish meal totally replaced by the whole-plant protein diet resulted in a lower value of essential amino acids to total amino acids (EAA / TAA), n-3 / n-6 PUFAs, and a lower proportion of docosahexaenoic acid (DHA), n-3 polyunsaturated fatty acid (PUFAs). Principal component analysis and hierarchical cluster analysis revealed that shrimps fed diet with fish meal partially replaced by AKM and PBM (1:1) had the most similar volatile compounds profile to the fish meal-based diet. These results indicated that the composite mixture of PBM and AKM (1:1) is an excellent substitution for fish meal in shrimp diets.

Targeted deletion of ecto-5′-nucleotidase results in retention of inosine monophosphate content in postmortem muscle of medaka (Oryzias latipes)

Inosine monophosphate (IMP) is an important indicator of meat freshness and contributes to its umami taste. An attractive strategy for enhancing umami is to suppress the IMP-degrading activity and increase the IMP content in the skeletal muscle through genome editing technology using the CRISPR-Cas9 system. However, the molecular mechanisms underlying IMP degradation remain unclear. We cloned two ecto-5′-nucleotidase genes, designated as ecto-5′-nucleotidase-a (nt5ea) and ecto-5′-nucleotidase-b (nt5eb), from medaka (Oryzias latipes), a vertebrate model organism. Expression analysis using embryos showed that nt5ea or nt5eb overexpression remarkably upregulated IMP degradation, and that the IMP-degrading activity was higher in Nt5ea than in Nt5eb. Furthermore, we established frame-shifted or large deletion (lacking nt5ea or nt5eb locus) mutant strains and assayed the effects of gene disruptions on the amount of IMP in skeletal muscle. The nt5ea-deficient medaka showed considerable higher levels of IMP at 48 h postmortem than did the wild-type fish. The nt5eb mutants also exhibited higher IMP contents than that in the wild types, but the increase was less than that in the nt5ea mutants. Our results demonstrated that nt5e is an important regulator of IMP levels in skeletal muscle and that its loss of function was effective in maintaining IMP content.

Molecular Characterization of LKB1 of Triploid Crucian Carp and Its Regulation on Muscle Growth and Quality.

Simple SummaryLiver Kinase B1 (LKB1) can regulate energy metabolism and skeletal muscle growth. In the study, we cloned LKB1 cDNA and assessed LKB1 expression in triploid crucian carp (Carassius auratus), the molecular regulation mechanisms of LKB1 involved in muscle growth and quality. In conclusion, the LKB1 amino acid sequence of the triploid crucian carp had a high sequence identity with carp (Cyprinus carpio). Additionally, activated LKB1 can promote the expression of most myogenic regulatory factors, muscle fibers development, the formation of inosine monophosphate (IMP), which is a flavor substance of muscle, and improve meat quality by increasing elasticity and chewiness. Inhibiting LKB1 can reverse the trend. Moreover, with increasing lysine-glutamate dipeptide concentrations in the feed, the expression of LKB1 gradually increased and was highest when dipeptide concentration was 1.6%.Liver Kinase B1 (LKB1) is a serine/threonine kinase that can regulate energy metabolism and skeletal muscle growth. In the present study, LKB1 cDNA of triploid crucian carp (Carassius auratus) was cloned. The cDNA contains a complete open reading frame (ORF), with a length of 1326 bp, encoding 442 amino acids. Phylogenetic tree analysis showed that the LKB1 amino acid sequence of the triploid crucian carp had a high sequence similarity and identity with carp (Cyprinus carpio). Tissue expression analysis revealed that LKB1 was widely expressed in various tissues. LKB1 expressions in the brain were highest, followed by kidney and muscle. In the short-term LKB1 activator and inhibitor injection experiment, when LKB1 was activated for 72 h, expressions of myogenic differentiation (MyoD), muscle regulatory factor (MRF4), myogenic factor (MyoG) and myostatin 1 (MSTN1) were markedly elevated and the content of inosine monophosphate (IMP) in muscle was significantly increased. When LKB1 was inhibited for 72 h, expressions of MyoD, MyoG, MRF4 and MSTN1 were markedly decreased. The long-term injection experiment of the LKB1 activator revealed that, when LKB1 was activated for 15 days, its muscle fibers were significantly larger and tighter than the control group. In texture profile analysis, it showed smaller hardness and adhesion, greater elasticity and chewiness. Contrastingly, when LKB1 was inhibited for 9 days, its muscle fibers were significantly smaller, while the gap between muscle fibers was significantly larger. Texture profile analysis showed that adhesion was significantly higher than the control group. A feeding trial on triploid crucian carp showed that with dietary lysine-glutamate dipeptide concentration increasing, the expression of the LKB1 gene gradually increased and was highest when dipeptide concentration was 1.6%. These findings may provide new insights into the effects of LKB1 on fish skeletal muscle growth and muscle quality, and will provide a potential application value in improvement of aquaculture feed formula.

MiRNA-mRNA associations with inosine monophosphate specific deposition in the muscle of Jingyuan chicken

ABSTRACT 1. Inosine monophosphate (IMP), is an essential component for meat flavour and microRNAs (miRNAs) play a vital role in its post-transcriptional regulation. However, the mechanism of how miRNA expression affects muscle-specific IMP deposition is unclear. 2. The following study performed transcriptome sequencing and bioinformatics analysis of breast and leg muscle, which have significantly different IMP content in Jingyuan chicken. The differential miRNA-mRNAs were screened out and correlation analysis with IMP content was performed. 3. A total of 39 differentially expressed miRNAs (DE miRNAs) and 666 differentially expressed mRNAs (DE mRNAs) were identified between breast muscles and leg muscles. Using miRNA-mRNA integrated analysis, 29 miRNA-target gene pairs were obtained, composed of 13 DE miRNAs and 28 DE mRNAs. Next, purine metabolism, glycolysis/gluconeogenesis, pyruvate metabolism and the biosynthesis of amino acid pathways as necessary for muscle IMP-specific deposition were identified. The differentially expressed gene PKM2, which was significantly enriched in all four pathways, is involved in IMP anabolism in the form of energy metabolism and enzyme activity regulation. The correlation analysis suggested that the gga-miR-107-3p-KLHDC2 negative interaction may be a key regulator in IMP deposition. 4. This study explores the functional mechanism of IMP-specific deposition in Jingyuan chicken muscles at the miRNA and mRNA levels and highlights multiple candidate miRNAs and mRNAs for molecular-assisted breeding.