Intermuscular Bones Research Articles

Diluted Acetic Acid Softened Intermuscular Bones from Silver Carp (Hypophthalmichthys molitrix) by Dissolving Hydroxyapatite and Collagen.

Intermuscular bones (IBs) pose physical hazards that threaten consumer health and food safety. This study aimed to investigate the mechanism of softening IBs from silver carp with diluted acetic acid. IBs (separated from muscle) and fillets (without removing IBs) were treated with diluted acetic acid. Analyses of sensory attributes and the hardness of treated IBs indicated that diluted acetic acid (<10 mmol/L) could soften IBs effectively. Additionally, 0.5 mmol/L acetic acid softened IBs within fillets without significantly affecting the texture and flavor of fillets. Analyses of microstructure, minerals (calcium and phosphorus) and collagen content, and the Fourier transform infrared (FTIR) spectra of IBs indicated that acetic acid broke connections (formed by collagen that shared hydroxyl groups) between collagen molecules, and between collagen and hydroxyapatite (HAP), thus inducing the dissolution of collagen and HAP. The dissolution of HAP contributed more to IBs softening than collagen.

Musculotendinous system of mesopelagic fishes: Stomiiformes (Teleostei).

Every night the greatest migration on Earth starts in the deep pelagic oceans where organisms move up to the meso- and epipelagic to find food and return to the deeper zones during the day. One of the dominant fish taxa undertaking vertical migrations are the dragonfishes (Stomiiformes). However, the functional aspects of locomotion and the architecture of the musculotendinous system (MTS) in these fishes have never been examined. In general, the MTS is organized in segmented blocks of specific three-dimensional 'W-shaped' foldings, the myomeres, separated by thin sheets of connective tissue, the myosepta. Within a myoseptum characteristic intermuscular bones or tendons may be developed. Together with the fins, the MTS forms the functional unit for locomotion in fishes. For this study, microdissections of cleared and double stained specimens of seven stomiiform species (Astronesthes sp., Chauliodus sloani, Malacosteus australis, Eustomias simplex, Polymetme sp., Sigmops elongatus, Argyropelecus affinis) were conducted to investigate their MTS. Soft tissue was investigated non-invasively in E. schmidti using a micro-CT scan of one specimen stained with iodine. Additionally, classical histological serial sections were consulted. The investigated stomiiforms are characterized by the absence of anterior cones in the anteriormost myosepta. These cones are developed in myosepta at the level of the dorsal fin and elongate gradually in more posterior myosepta. In all but one investigated stomiiform taxon the horizontal septum is reduced. The amount of connective tissue in the myosepta is very low anteriorly, but increases gradually with body length. Red musculature overlies laterally the white musculature and exhibits strong tendons in each myomere within the muscle bundles dorsal and ventral to the horizontal midline. The amount of red musculature increases immensely towards the caudal fin. The elongated lateral tendons of the posterior body segments attach in a highly complex pattern on the caudal-fin rays, which indicates that the posterior most myosepta are equipped for a multisegmental force transmission towards the caudal fin. This unique anatomical condition might be essential for steady swimming during diel vertical migrations, when prey is rarely available.

Comparison of Myosepta Development and Transcriptome Profiling between Blunt Snout Bream with and Tilapia without Intermuscular Bones.

Simple SummaryThe presence or absence of intermuscular bones (IBs) is directly related to the economic and edible value of fish. The specific regulatory mechanism of IB formation is not completely known yet. Here, we explored the molecular mechanisms that regulate the formation of IBs based on histological analysis, transcriptome profiling, and gene expression quantification using M. amblycephala (with IBs) and O. niloticus (without IBs) as models. As a result, we identified several bone-related genes and elucidated their regulatory roles in the development of IBs.Intermuscular bones (IBs) are small spicule-like bones located in the myosepta of basal teleosts, which negatively affect the edibleness and economic value of fish. Blunt snout bream (Megalobrama amblycephala, with epineural and epipleural IBs) and tilapia (Oreochromis niloticus, without epineural and epipleural IBs) are two major aquaculture species and ideal models for studying the formation mechanisms of fish IBs. Here, we compared myosepta development between M. amblycephala and O. niloticus, based on histological analysis, transcriptome profiling, and expression analysis of bone-related genes. The histological results showed that dye condensation began to appear in the myosepta 20 days post hatching (dph) in M. amblycephala, and IBs could be clearly observed 50 dph in the myosepta, based on different staining methods. However, in O. niloticus, dye condensation was not observed in the myosepta from 10 to 60 dph. Differentially expressed genes (DEGs) at different developmental stages were screened by comparing the transcriptomes of M. amblycephala and O. niloticus, and KEGG analysis demonstrated that these DEGs were enriched in many bone-related pathways, such as focal adhesion, calcium, and Wnt signaling pathways. Quantitative PCR was performed to further compare the expression levels of some bone-related genes (scxa, scxb, runx2a, runx2b, bgp, sp7, col1a2, entpd5a, entpd5b, phex, alpl, and fgf23). All the tested genes (except for alpl) exhibited higher expression levels in M. amblycephala than in O. niloticus. A comparison of the dorsal and abdominal muscle tissues between the two species also revealed significant expression differences for most of the tested genes. The results suggest that scxa, scxb, runx2a, runx2b, entpd5a, col1a2, and bgp may play important roles in IB development. Our findings provide some insights into the molecular mechanisms of IB formation, as well as clues for further functional analysis of the identified genes to better understand the development of IBs.

Bones of teleost fish demonstrate high fracture strain

The endoskeleton of teleosts (bony fish) includes a vertebral spine with articulating rib bones (RBs) similar to humans and further encompasses mineralized tissues that are not found in mammals, including intermuscular bones (IBs). RBs form through endochondral ossification and protect the inner organs, and IBs form through intramembranous ossification within the myosepta and play a role in force transmission and propulsion during locomotion. Based on previous findings suggesting that IBs show a much higher ability for fracture strain compared to mammalian bones, this study aims to investigate whether this ability is general to teleost bones or specific to IBs. We analyzed RBs and IBs of 25 North Atlantic Herring fish. RBs were analyzed using micro-mechanical tensile testing and micro-computed tomography, and both RB and IB were additionally analyzed with Raman spectroscopy. Based on our previous results from IB, we found that RBs are more elastically deformable (on average, 50% higher yield strain and 115% higher elastic work) and stronger (55% higher fracture stress) than values reported for IBs. However, these differences were neither associated with a higher Young’s modulus nor a higher degree of mineralization in RBs. Astonishingly, RBs and IBs showed similar fracture strains (12–15% on average, reaching up to 20%), reflecting a much higher ability for tensile deformation than reported for mammalian bone, and further highlighting the biomimetic potential of teleost fish bones for inspiring innovative biomaterials.

Behavioural patterns related to the marine fish consumption- An analysis of coastal belt households, Noakhali, Bangladesh

Marine fish is a major source of Omega-3 fatty acids (Eicosapentaenoic acid, EPA andDocosahexaenoic acid, DHA), which are now recognized worldwide as a key factor in human health. Thepresent study was conducted to depict the status of marine fish consumption in three districts (namely Feni,Lakhsmipur, and Noakhali) of greater Noakhali district, Bangladesh using a questionnaire survey in 240households during the month of May-June, 2018. Almost all the households (96%; n=230) consumed marinefishes. Price, availability, presence of inter-muscular bones, and characteristic fishy smell were the majorbarriers to marine fish consumption in the studied area. The average quantity of fresh and dried marine fishconsumed was 53.35 g/capita/day and 3.71 g/capita/day, respectively in greater Noakhali. Marine fresh fishconsumption in the three districts differed significantly (p&lt;0.001). The highest (80.20±32.72 g) and thelowest (40.02±27.90 g) amount of marine fresh fish consumption were observed respectively, in Lakhsmipurand Feni district and the highest (4.19±7.47 g) and the lowest (3.47±4.87 g) amount of dried marine fishconsumption were observed respectively, in Feni and Noakhali district. About 32% of consumers consumedmarine fresh fish 3 to 6 times in a week whereas 46% of consumers consumed dried fish once in a month.Consumers belonging to high-income households consume more marine fish (57.11 g) than the low-incomehouseholds (49.33 g). Harpadon nehereus, Tenualosa ilisha, Otolithes cuvieri, Polynemous paradiseus, Mugilcephalus, Oxyurichthys microlepis, and Sillago domina were among the most frequently consumed marinefishes in the studied areas. About 76% of respondents perceived eating marine fish was good for health.Increased availability, lower price and creating awareness on health benefits may lead to increasing marinefish consumption among local people in the region.

Molecular mechanisms of intermuscular bone development in fish: a review

Intermuscular bones (IBs) are slender linear bones embedded in muscle, which ossify from tendons through a process of intramembranous ossification, and only exist in basal teleosts. IBs are essential for fish swimming, but they present a choking risk during human consumption, especially in children, which can lead to commercial risks that have a negative impact on the aquaculture of these fish. In this review, we discuss the morphogenesis and functions of IBs, including their underlying molecular mechanisms, as well as the advantages and disadvantages of different methods for IB studies and techniques for breeding and generating IB-free fish lines. This review reveals that the many key genes involved in tendon development, osteoblast differentiation, and bone formation, e.g., scxa, msxC, sost, twist, bmps, and osterix, also play roles in IB development. Thus, this paper provides useful information for the breeding of new fish strains without IBs via genome editing and artificial selection.

Genome-wide association study reveals genes associated with the absence of intermuscular bones in tambaqui (Colossoma macropomum).

The presence of intermuscular bones in fisheries products limits the consumption and commercialization potential of many fish species, including tambaqui (Colossoma macropomum). These bones have caused medical emergencies and are an undesirable characteristic for fish farming because their removal is labor-intensive during fish processing. Despite the difficulty in identifying genes related to the lack of intermuscular bone in diverse species of fish, the discovery of individuals lacking intermuscular bones in a Neotropical freshwater characiform fish has provided a unique opportunity to delve into the genetic mechanisms underlying the pathways of intermuscular bone formation. In this study, we carried out a GWAS among boneless and wt tambaqui populations to identify markers associated with a lack of intermuscular bone. After analyzing 11416 SNPs in 360 individuals (12 boneless and 348 bony), we report 675 significant (Padj <0.003) associations for this trait. Of those, 13 associations were located near candidate genes related to the reduction of bone mass, promotion of bone formation, inhibition of bone resorption, central control of bone remodeling, bone mineralization and other related functions. To the best of our knowledge, for the first time, we have successfully identified genes related to a lack of intermuscular bones using GWAS in a non-model species.

Loss of scleraxis leads to distinct reduction of mineralized intermuscular bone in zebrafish

Intermuscular bones (IBs) are ossified from tendons and only occur in lower teleosts. Positive association between the regulation of scleraxis gene (scx) and tendon development gave us reasons to speculate that the scx gene may play a potential role in regulating the development of IBs. A phylogenetic analysis conducted for this study revealed potential functional differentiation between two scx orthologues, scxa and scxb. The scxa−/− and scxb−/− zebrafish were generated through CRISPR-Cas9 technology to study the role of scx in the IB and rib development. The results showed a significant reduction of the number of IBs in adult scxa-1-/- zebrafish, with almost 70% reduction (15–25 IBs) compared to the wild type scxa-1+/+ zebrafish (76–80 IBs). In the scxa-1+/+ adults, IBs were observed in both dorsal and tail segments; however, in scxa-1-/- fish IBs were observed only in the tail segment (none in the dorsal segment). Although scxa-1−/− zebrafish had rib defects, the mutants were viable and fertile as adult fish. The scxb−/− zebrafish had the same number of IBs and same skeletal phenotype as the wild-type fish. This suggests that only scxa has a crucial role in the IB development, and confirms functional differentiation of scx orthologues. To further clarify the molecular mechanism by which scxa affects the IB development, we conducted comparative transcriptome analysis of dorsal tissue samples of scxa-1+/+ (with IBs) and scxa-1−/− (without IBs), and further verified the expression of key genes via qPCR. This is the first study to identify a gene that controls the amount of IBs in fish, and it provides a new sight into the effects of scxa on the molecular mechanism of IB development in fish.

Comparative Analysis of Muscle Development in Zebrafish with Different Intermuscular-Bo nes Patterns

Comparative Analysis of Muscle Development in Zebrafish with Different Intermuscular-Bo nes Patterns

A Comparative Genomic and Transcriptional Survey Providing Novel Insights into Bone Morphogenetic Protein 2 (bmp2) in Fishes

Intermuscular bones (IBs) are only found in the muscles of fish. Bone morphogenetic protein 2 (bmp2) is considered to be the most active single osteogenesis factor. It promotes cell proliferation and differentiation during bone repair, as well as inducing the formation of bones and cartilages in vivo. However, detailed investigations of this family in fish are incredibly limited. Here, we have used a variety of published and unpublished bmp2 sequences for teleosts and cartilage fish in order to explore and expand our understanding of bmp2 genes in fish. Our results confirmed that teleost genomes contain two or more bmp2 genes, and the diversity of bmp2 genes in vertebrates appears to be as a result of a combination of whole genome duplication (WGD) and gene loss. Differences were also observed in tissue distribution and relative transcription abundance of the bmp2s through a transcriptomic analysis. Our data also indicated that bmp2b may play an important role in the formation of IBs in teleosts. In addition, protein sequence alignments and 3D structural predictions of bmp2a and bmp2b supported their similar roles in fishes. To summarize, our existing work provided novel insights into the bmp2 family genes in fishes through a mixture of comparative genomic and transcriptomic analysis.

Heritability and quantitative trait locus analyses of intermuscular bones in mirror carp (Cyprinus carpio)

Common carp (Cyprinus carpio) is one of the major aquaculture species in the world and accounts for approximately 8% of the total aquaculture production. The presence of intermuscular bones (IMBs) dramatically affects the economic value of this fish in the market. To understand the genetic variation in IMBs in common carp, in this study, we estimated the heritability and carried out quantitative trait locus (QTL) mapping of IMBs in mirror carp. We used 30 full-sib families including 871 individuals to calculate the heritability and genetic correlation and found that the heritability of the total IMB count, Y-shaped (YS) IMB count and I-shaped (IS) IMB count were moderate and significant (P < 0.001), and the values were 0.15 ± 0.08, 0.44 ± 0.12 and 0.23 ± 0.08, respectively. The phenotypic correlation among these three traits was significant, while only the genetic correlation between the IMB count and YS IMB count was significant. QTL mapping was performed with 8 families including 522 individuals, and 8 QTLs were discovered for IMBs, YS IMBs and IS IMBs, including one QTL for IMBs that explained 16.20% of the phenotypic variance, 4 QTLs for YS IMBs that explained 56.26% of the phenotypic variance, and 3 QTLs for IS IMBs that explained 38.24% of the phenotypic variance. Within the QTL regions, 29 genes with functions such as osteogenesis; osteoblast, osteoclast and chondrocyte development and differentiation; and fin or limb development were identified as candidate genes for IMB development. These results provide insight into the genetic mechanism underlying IMB development in common carp.

THE CHARACTERISTIC OF COMPOUND FEEDS FOR TILAPIA FISH

The article states that, according to the literature review, in aquaculture of freshwater fish species that acquire everincreasing production volumes, tilapia is leading with 17%, and it is follower by carp (15% of world volume). For almost 60 years, tilapia have moved into second place in the global fish production, with the prospect of taking first place in the next 2-3 years and overtake carp in world production. Since fish is a rich source of proteins and essential amino acids, vitamins, polyunsaturated fatty acids, macro and micronutrients, it is also an important component of the diet of the population. Meat of tilapia is dense, non-fat, protein content close to trout meat, does not contain intermuscular bones. One of the priorities of the development of fish farming in Ukraine is the cultivation of tilapia. The amount of feed consumption in the world is increasing every year, due to the rapid growth in demand for tilapia. Currently, Ukrainian businessmen are interested in the production of catfish and tilapia. The most famous aquapride plants that grow these breeding objects are Lauren Aquaculture LLC (Rivne region), Aqua System Organic LLC (Kiev region), Catfish from Pavlysh TM (Kirovograd region), TM “First City Fish Farm ‘’I want a catfish ”(Kiev). That is why the production of balanced domestic feed for tilapia is an important task of the feed industry of Ukraine. The theoretical study was devoted to the issue of tilapia feed production. The nutritional value of feed for tilapia depends on the stage of the life cycle of this species of fish. It was shown the world leading manufacturers of feed for tilapia, it was analyzed the nutritional value of feed for this species of fish on the content of crude protein in the starting, growth and finishing periods, respectively. The requirements for the content of essential nutrients, essential amino acids, minerals (micro and micronutrients), water-and fat-soluble vitamins and restrictions on the content of crude fiber are given. The programs of feeding of tilapia of various producers are analyzed and an own program of feeding this species of fish is developed, it is divided the starting, growth and finishing period of tilapia growing. For starter mixed feeds for tilapia, the content of crude protein should be at least 45%, crude fat at least 12%, crude fiber not more than 1.5%, gross energy not less than 18 MJ, crude ash not more than 8%. For grower’s feeds, the content of crude protein should be at least 40 %, crude fat at least 12%, crude fiber not more than 3%, gross energy not less than 17 MJ, crude ash not more than 9.5%. For finishing feeds, the content of crude protein should be at least 30 %, crude fat at least 6%, crude fiber not more than 5%, gross energy not less than 17 MJ, crude ash not more than 7%. Amino acids requirements are very important for tilapia fish, feeds for tilapia from any period should contain lysine should be at least 1.6%, methionine should be at least 0.7 %.

Development of Teleost Intermuscular Bones Undergoing Intramembranous Ossification Based on Histological-Transcriptomic-Proteomic Data.

Intermuscular bones (IBs) specially exist in lower teleost fish and the molecular mechanism for its development remains to be clarified. In this study, different staining methods and comparative proteomics were conducted to investigate the histological structure and proteome of IB development in Megalobrama amblycephala, including four key IB developmental stages (S1—IBs have not emerged in the tail part; S2—several small IBs started to ossify in the tail part; S3—IBs appeared rapidly; S4—all the IBs appeared with mature morphology). Alcian blue and alizarin red S stained results indicated that IBs were gradually formed from S2 to S4, undergoing intramembranous ossification without a cartilaginous phase. A total of 3368 proteins were identified by using the isobaric tags for relative and absolute quantitation (iTRAQ) approach. Functional annotation showed that proteins which were differentially expressed among stages were involved in calcium, MAPK, Wnt, TGF-β, and osteoclast pathways which played a critical role in bone formation and differentiation. Three proteins (collagen9α1, stat1, tnc) associated with chondrocytes did not exhibit significant changes through S2 to S4; however, proteins (entpd5, casq1a, pvalb, anxa2a, anxa5) which associated with osteoblasts and bone formation and differentiation showed significantly a higher expression level from S1 to S2, as well as to S3 and S4. These further demonstrated that development of IBs did not go through a cartilaginous phase. The inhibitors of TGF-β and Wnt pathways were tested on zebrafish (sp7/eGFP) and the results indicated that both inhibitors significantly delayed IB development. This study provides a comprehensive understanding of the IB ossification pattern, which will help further elucidate the molecular mechanisms for IB development in teleosts.

Evolution of the intermuscular bones in the Cyprinidae (Pisces) from a phylogenetic perspective.

Intermuscular bones (IBs) are widely present in morphologically generalized teleost fishes and are commonly found in the Cyprinidae. Intermuscular bones are small, hard spicules of bone that are formed by ossification in the myosepta between neighboring myomeres. Why fish have IBs, and whether there is any evolutionary pattern to their occurrence, has been poorly understood. However, the presence of IBs does substantially affect the meat quality and commercial values of many cyprinid fishes in aquaculture. In this study, we sampled 592 individuals of cyprinid fishes to systematically investigate the evolution of IBs from a phylogenetic point of view. We found that the total number of IBs in the Cyprinidae ranged from 73 to 169, and we clarified that only two categories of IBs (epineural and epipleural) were present in all examined cyprinids. Most of the IBs were distributed in the posterior region of the fish, which might be an optimal target for selecting fewer IB strains in aquaculture. There was a positive correlation between IBs and the number of vertebrae, thus making it possible to predict the approximate number of IBs by counting the number of vertebrae. Although the IBs displayed some correlation with phylogenetic relationships in some lineages and to ecological factors such as diet (especially carnivore), in an overall view the variations of IBs in cyprinids were extremely diverse. The number and patterns of IBs in these fishes may reflect their phylogenetic history, but have been shaped by multiple environment factors. In this study, we also confirmed that X‐ray photography remains an optimal and reliable method for the study of IBs.

Microstructure, mineral and mechanical properties of teleost intermuscular bones

There is an increasing interest in understanding teleost bone biomechanics in several scientific communities, for instance as interesting biomaterials with specific structure-function relationships. Intermuscular bones of teleost fish have previously been described to play a role in the mechanical force transmission between muscle and bone, but their biomechanical properties are not yet fully described. Here, we have investigated intermuscular bones (IBs) of the North Atlantic Herring with regard to their structure and micro-architecture, mineral-related properties, and micro-mechanical tensile properties. A total of 115 IBs from 18 fish were investigated. One cohort of IBs, containing 20 bones from 2 smaller fish and 23 bones of 3 larger fish, was used for mechanical testing, wide-angle X-ray scattering, and scanning electron microscopy. Another cohort, containing 36 bones from 7 smaller fish and 36 bones from 6 larger fish, was used for microCT. Results show some astonishing properties of the IBs: (i) IBs present higher ductility, lower Young's modulus but similar strength and TMD (Tissue Mineral Density) compared to mammalian bone, and (ii) IBs from small fish were 49% higher in Young’s modulus than fish bones from larger fish while their TMD was not statistically different and crystal length was 8% higher in large fish bones. Our results revealed that teleost IB presents a hybrid nature of soft and hard tissue that differs from other bone types, which might be associated with their evolution from mineralized tendons. This study provides new data regarding teleost fish bone biomechanical and micro-structural properties.

Understanding the development of intermuscular bones in teleost: status and future directions for aquaculture

AbstractAs one of the most sustainable protein sources for humans, aquaculture is the fastest growing food production sector in agriculture. According to the recent FAO estimate, there are 21 principal aquaculture fish species around the worldwide. Among these cultured species, almost half of them belong to Cypriniformes, the species from which all have a certain number of intermuscular bones (IBs). IBs are small spicule‐like bones existing in the muscle fillet, which are existed only in lower teleost and of course have a negative effect on fish quality and aquatic product processing. Many studies have been focusing on IBs number, morphology, and more and more become focusing on its development molecular mechanism. In the review, we summarized the recent progress and discussed with following directions: (i) Controversial on the origin of IBs, ossified from tendons or ligaments? (ii) IBs counts and morphology revealed big variation among different species; (iii) Ossification patterns of IBs might be related with different swimming modes among the teleost fish, and its development belongs to intramembranous ossification without cartilaginous phase; (iv) Transcriptome/microRNA (miRNA)/proteomics and gene functional analysis had been used to investigate the molecular mechanism of IBs development and some genes showed certain regulatory roles during IBs’ development; (v) The reports showed that some breeding technologies could make a certain effect on IBs counts in fish species, but there are rare reports with success on deleting or significantly reducing IBs counts. Meanwhile, we also discuss the challenges and future directions of reducing or even deleting IBs in aquaculture.

Identification and mapping of SNPs associated with number of intermuscular bone in blunt snout bream

Most of the freshwater aquaculture fish species in the world, especially cyprinid fishes, contain intermuscular bones (IBs). Different number of IBs had been indicated among different species and strains or individuals of same species, which suggested that the trait of IBs counts has the possibility of genetic improvement through selective breeding program. In this study, two groups with extreme differences for IB number were constructed to identify IB number-associated SNPs and genes in blunt snout bream (Megalobrama amblycephala), which is one of the most important aquaculture species in China. Through whole genome resequencing and bulked segregant analysis (BSA) for two groups with extreme IBs number (IB-more group with IBs number ≥130; IB-less group with IBs number ≤100), a total of 6074 high quality SNPs with |Delta-Index|≥0.5 were screened out by chi-square test and index analysis. The sliding-window analysis subsequently obtained two SNP enrichment regions, which located on chromosome 06 (32 M–34 M) and chromosome 11 (12 M–16 M), respectively, containing 21 and 300 candidate SNPs. Besides, 181 candidate SNPs with |Delta-Index|≥0.8 were detected and annotated within the genome-wide range beyond above two regions. Finally, 52 SNPs were used for data reliability verification. Genotyping of SNPs in IB-less individuals and IB-more individuals and correlation analysis between candidate SNPs and IB number traits indicated that five SNPs were significantly associated with the trait of IB number. The sequences or flanking sequences where SNPs located were then annotated to different genes, which maybe closely related to IB number trait. This is the first study to explore SNPs/genes related to the number of IBs in fish by BSA. The identified dataset provides an extensive resource for understanding the molecular mechanisms underlying IB counts in teleosts and also lays the foundation for the marker assisted breeding of IB number traits in M. amblycephala.

MRNA and microRNA transcriptomics analyses in intermuscular bones of two carp species, rice flower carp (Cyprinus carpio var. Quanzhounensis) and Jian carp (Cyprinus carpio var. Jian)

The rice flower carp (Cyprinus carpio var. Quanzhounensis) is a bony fish (superclass Osteichthyes), with very soft bones that is a significant feature unlike the other carp species. In this study, we analyzed the mRNA and microRNA (miRNA) transcriptomes in the intermuscular bones of rice flower carp and Jian carp (Cyprinus carpio var. Jian) (a typical member of common carp in China), using Illumina RNA sequencing. We identified 55,340 genes (including 47,541 known genes and 8231 predicted new genes) and 662 miRNAs (including 595 known miRNAs and 67 novel miRNAs) in the two species. By comparing the transcriptomes of the two species, we identified 1523 differentially expressed genes (DEGs) (including 576 up - and 947 downregulated DEGs) and 352 differentially expressed miRNAs (DEMs) (including 85 up- and 267 downregulated DEMs). According to the Gene Ontology (GO) annotation, 7 DEGs and 12 DEMs were found to be involved in the regulation of bone mineralization. The results of this study improve our understanding of the mRNA and miRNA profiles of carp bones, particularly those of the rice flower carp.

Genetic parameter estimates for intermuscular bone in blunt snout bream (Megalobrama amblycephala) based on a microsatellite-based pedigree

Most of the freshwater aquaculture fish species in the world, especially cyprinid fishes, contain intermuscular bones (IBs). IBs are often small and sharp, and they consequently limit how the fish can be processed, cause injury or trauma if lodged in consumers' throat or mouth and therefore affect the appeal of the fish to many consumers. In order to assess the possibility of decreasing IBs counts through selective breeding, this study evaluated the heritability of the number of IBs in blunt snout bream (Megalobrama amblycephala), which is one major aquaculture species in China. A total of 758 offsprings from 69 parents were genotyped at nine polymorphic microsatellite loci, and then 672 offspring from 213 full-sib families (33 female and 25 male breeders) were used for genetic parameter estimates. IBs were carefully teased from different poached sections of the flesh and counted. Heritability was estimated using an animal model. The results showed that IB number ranged between 84 and 146 per individual in the test population, with an average of 118 IBs. Coefficient of variation in IB number (CV) in ventral sections (13.63%) was substantially higher in comparison to dorsal sections (6.60%). The genetic correlation of IB number between the two sections was significantly positive and high (0.93) (P < .01), however, the phenotypic correlation was significantly positive but low (0.26) (P < .01). The differences among the families showed that the variation in the ventral section accounted for most of the total variation in IB number within the species, which indicated that IBs may have develop by different processes in dorsal and ventral sections. The heritability of the IBs number in M. amblycephala was low (0.098) for the dorsal section, but medium (0.236–0.410) for other sections. This study provides the first reported estimates for the heritability of the number of IBs in fish species and the finding of significant additive genetic variation for IB number indicate that it should be feasible to decrease the number of IBs through selective breeding.

External morphology, postcranial and appendicular osteology of three southwestern Atlantic flatfishes ( Paralichthys , Paralichthyidae), and comparisons with other congeneric species

ABSTRACT Comparisons of the external morphology and analysis of osteological features of the postcranial and appendicular skeletons of three southwestern Atlantic flatfish species of the genus Paralichthys (P. isosceles, P. orbignyanus and P. patagonicus) were carried out. Bones are described, and detailed morphological, morphometric and meristic characteristics of these flounders are given in order to provide information about the external and internal morphology of three species of Paralichthys occurring in the south-west Atlantic waters that add new information and will help regarding within the framework of a phylogenetic study of the group. Interspecific differences were found in the number of vertebrae and intermuscular bones, as well as in the morphology and morphometry of vertebrae, caudal skeletons, pectoral and pelvic girdle bones. Relationships between bones are discussed and bone characteristics compared with those found in other species of Paralichthys and in other pleuronectiform species. The position of Paralichthys isosceles within Paralichthys is discussed, along with other congeners such as P. triocellatus and P. oblongus.