Muscle precursor cells in the developing limbs of two isopods (Crustacea, Peracarida): an immunohistochemical study using a novel monoclonal antibody against myosin heavy chain

Considerations for cultivated crustacean meat: potential cell sources, potential differentiation and immortalization strategies, and lessons from crustacean and other animal models

Cultivated crustacean meat (CCM) is a means to create highly valued shrimp, lobster, and crab products directly from stem cells, thus removing the need to farm or fish live animals. Conventional crustacean enterprises face increasing pressures in managing overfishing, pollution, and the warming climate, so CCM may provide a way to ensure sufficient supply as global demand for these products grows. To support the development of CCM, this review briefly details crustacean cell culture work to date, before addressing what is presently known about crustacean muscle development, particularly the molecular mechanisms involved, and how this might relate to recent work on cultivated meat production in vertebrate species. Recognizing the current lack of cell lines available to establish CCM cultures, we also consider primary stem cell sources that can be obtained non-lethally including tissues from limbs which are readily released and regrown, and putative stem cells in circulating hemolymph. Molecular approaches to inducing myogenic differentiation and immortalization of putative stem cells are also reviewed. Finally, we assess the current status of tools available to CCM researchers, particularly antibodies, and propose avenues to address existing shortfalls in order to see the field progress.

Differentiation and Maturation of Muscle and Fat Cells in Cultivated Seafood: Lessons from Developmental Biology

Cultivated meat, also known as cultured or cell-based meat, is meat produced directly from cultured animal cells rather than from a whole animal. Cultivated meat and seafood have been proposed as a means of mitigating the substantial harms associated with current production methods, including damage to the environment, antibiotic resistance, food security challenges, poor animal welfare, and-in the case of seafood-overfishing and ecological damage associated with fishing and aquaculture. Because biomedical tissue engineering research, from which cultivated meat draws a great deal of inspiration, has thus far been conducted almost exclusively in mammals, cultivated seafood suffers from a lack of established protocols for producing complex tissues in vitro. At the same time, fish such as the zebrafish Danio rerio have been widely used as model organisms in developmental biology. Therefore, many of the mechanisms and signaling pathways involved in the formation of muscle, fat, and other relevant tissue are relatively well understood for this species. The same processes are understood to a lesser degree in aquatic invertebrates. This review discusses the differentiation and maturation of meat-relevant cell types in aquatic species and makes recommendations for future research aimed at recapitulating these processes to produce cultivated fish and shellfish.

Embryonic Development and Histological Analysis of Skeletal Muscles of Tenuidactylus caspius (Eichwald, 1831) Lizards (Reptilia: Squamata)

During embryonic development of the Caspian thin-toed gecko migration, formation of myoblast and myosatellite cells occurs in the cranial-distal direction. Somite formation begins in the body part close to the skull and ends in the tail. The time of separation of somites from the proximal mesoderm depends on the temperature of the air and the substrate. Myoblast cells reach their targets and are connected, and the membranes in the area of their contact are destroyed. Myoblast’s fusion creates myosymplasts. The intermediate stage is observed after the formation of small myosymplasts. After that, the chain shape of myosymplasts are transformed into an intermediate plaque form. At this intermediate stage, the number of a nucleus is small, the shape of the nucleus differs from each other, and the location of the nucleus varies. Afterward, the connection of the intermediate forms with each other and with myoblasts forms a rounded shape, where the initial development of myotubules takes place. A fully formed myotubular and myosatellite cells are surrounded by a basal membrane and shape a muscle fiber. The skeletal muscles of the adult Caspian thin-toed gecko are mainly composed of white fibers. Thus, it allows the gecko to move very fast in a short time. Due to the small number of mitochondria in the myotubes, oxygen gas demand is decreased and the body is prevented from overheating.

Evolution of a chordate-specific mechanism for myoblast fusion

Vertebrate myoblast fusion allows for multinucleated muscle fibers to compound the size and strength of mononucleated cells, but the evolution of this important process is unknown. We investigated the evolutionary origins and function of membrane-coalescing agents Myomaker and Myomixer in various groups of chordates. Here, we report that Myomaker likely arose through gene duplication in the last common ancestor of tunicates and vertebrates, while Myomixer appears to have evolved de novo in early vertebrates. Functional tests revealed a complex evolutionary history of myoblast fusion. A prevertebrate phase of muscle multinucleation driven by Myomaker was followed by the later emergence of Myomixer that enables the highly efficient fusion system of vertebrates. Evolutionary comparisons between vertebrate and nonvertebrate Myomaker revealed key structural and mechanistic insights into myoblast fusion. Thus, our findings suggest an evolutionary model of chordate fusogens and illustrate how new genes shape the emergence of novel morphogenetic traits and mechanisms.

Eggs to long-legs: embryonic staging of the harvestman Phalangium opilio (Opiliones), an emerging model arachnid

Background

The comparative embryology of Chelicerata has greatly advanced in recent years with the integration of classical studies and genetics, prominently spearheaded by developmental genetic works in spiders. Nonetheless, the understanding of the evolution of development and polarization of embryological characters in Chelicerata is presently limited, as few non-spider species have been well studied. A promising focal species for chelicerate evo-devo is the daddy-long-legs (harvestman) Phalangium opilio, a member of the order Opiliones. Phalangium opilio, breeds prolifically and is easily accessible in many parts of the world, as well as tractable in a laboratory setting. Resources for this species include developmental transcriptomes, a draft genome, and protocols for RNA interference, but a modern staging system is critically missing for this emerging model system.

Results

We present a staging system of P. opilio embryogenesis that spans the most important morphogenetic events with respect to segment formation, appendage elongation and head development. Using time-lapse imaging, confocal microscopy, colorimetric in situ hybridization, and immunohistochemistry, we tracked the development of synchronous clutches from egg laying to adulthood. We describe key events in segmentation, myogenesis, neurogenesis, and germ cell formation.

Conclusion

Considering the phylogenetic position of Opiliones and the unduplicated condition of its genome (in contrast to groups like spiders and scorpions), this species is poised to serve as a linchpin for comparative studies in arthropod development and genome evolution. The staging system presented herein provides a valuable reference for P. opilio that we anticipate being useful to the arthropod evo-devo community, with the goal of revitalizing research in the comparative development of non-spider arachnids.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12983-022-00454-z.

Analysis of transcriptome difference between rapid-growing and slow-growing in Penaeus vannamei

Penaeus vannamei is the principle cultured shrimp species in China. However, with the increase of culture density, the growth difference between individuals is also expanding. Here, we make use of RNA-seq to study the growth mechanisms of P. vannamei. After 120 days, we examined the transcriptomes of rapid-growing individuals (RG) and slow-growing individuals (SG). A total of 2116 and 176 differentially expressed genes (DEGs) were found in SG and RG, respectively. Moreover, the main DEGs are opsin, heat shock protein (HSP), actin, myosin, superoxide dismutase (SOD), cuticle protein, and chitinase. GO analysis further revealed that the DEGs were enriched in biological processes significantly, such as "sensory perception," "sensory perception of light stimulus," "response to stimulus," and "response to stress." Additionally, KEGG enrichment analysis showed that the DEGs were mainly enriched in "pentose and glucuronate interconversions," "amino sugar and nucleotide sugar metabolism," "glycophospholipid biosynthesis," and "glutathione metabolism." Interestingly, the upstream genes in the ecdysone signaling pathway, including molting inhibition hormone (MIH) and crustacean hyperglycemic hormone (CHH), did not differ significantly between RG and SG, which suggests that the cause for the inconsistent growth performance is due to the stress levels rather than the ecdysone signal pathway. In summary, this work provides data that will be useful for future studies on shrimp growth and development.

Cuticle morphogenesis in crustacean embryonic and postembryonic stages

The crustacean cuticle is a chitin-based extracellular matrix, produced in general by epidermal cells and ectodermally derived epithelial cells of the digestive tract. Cuticle morphogenesis is an integrative part of embryonic and postembryonic development and it was studied in several groups of crustaceans, but mainly with a focus on one selected aspect of morphogenesis. Early studies were focused mainly on in vivo or histological observations of embryonic or larval molt cycles and more recently, some ultrastructural studies of the cuticle differentiation during development were performed. The aim of this paper is to review data on exoskeletal and gut cuticle formation during embryonic and postembryonic development in crustaceans, obtained in different developmental stages of different species and to bring together and discuss different aspects of cuticle morphogenesis, namely data on the morphology, ultrastructure, composition, connections to muscles and molt cycles in relation to cuticle differentiation. Based on the comparative evaluation of microscopic analyses of cuticle in crustacean embryonic and postembryonic stages, common principles of cuticle morphogenesis during development are discussed. Additional studies are suggested to further clarify this topic and to connect the new knowledge to related fields.

The making of an octopus arm

BACKGROUND

Most of our current findings on appendage formation and patterning stem from studies on chordate and ecdysozoan model organisms. However, in order to fully understand the evolution of animal appendages, it is essential to include information on appendage development from lophotrochozoan representatives. Here, we examined the basic dynamics of the Octopus vulgaris arm's formation and differentiation - as a highly evolved member of the lophotrochozoan super phylum - with a special focus on the formation of the arm's musculature.

RESULTS

The octopus arm forms during distinct phases, including an early outgrowth from an epithelial thickening, an elongation, and a late differentiation into mature tissue types. During early arm outgrowth, uniform proliferation leads to the formation of a rounded bulge, which subsequently elongates along its proximal-distal axis by means of actin-mediated epithelial cell changes. Further differentiation of all tissue layers is initiated but end-differentiation is postponed to post-hatching stages. Interestingly, muscle differentiation shows temporal differences in the formation of distinct muscle layers. Particularly, first myocytes appear in the area of the future transverse prior to the longitudinal muscle layer, even though the latter represents the more dominant muscle type at hatching stage. Sucker rudiments appear as small epithelial outgrowths with a mesodermal and ectodermal component on the oral part of the arm. During late differentiation stages, cell proliferation becomes localized to a distal arm region termed the growth zone of the arm.

CONCLUSIONS

O. vulgaris arm formation shows both, similarities to known model species as well as species-specific patterns of arm formation. Similarities include early uniform cell proliferation and actin-mediated cell dynamics, which lead to an elongation along the proximal-distal axis. Furthermore, the switch to an adult-like progressive distal growth mode during late differentiation stages is reminiscent of the vertebrate progress zone. However, tissue differentiation shows a species-specific delay, which is correlated to a paralarval pelagic phase after hatching and concomitant emerging behavioral modifications. By understanding the general dynamics of octopus arm formation, we established a basis for further studies on appendage patterning, growth, and differentiation in a representative of the lophotrochozoan super phylum.

Myogenesis of Malacostraca - the "egg-nauplius" concept revisited

BACKGROUND

Malacostracan evolutionary history has seen multiple transformations of ontogenetic mode. For example direct development in connection with extensive brood care and development involving planktotrophic nauplius larvae, as well as intermediate forms are found throughout this taxon. This makes the Malacostraca a promising group for study of evolutionary morphological diversification and the role of heterochrony therein. One candidate heterochronic phenomenon is represented by the concept of the 'egg-nauplius', in which the nauplius larva, considered plesiomorphic to all Crustacea, is recapitulated as an embryonic stage.

RESULTS

Here we present a comparative investigation of embryonic muscle differentiation in four representatives of Malacostraca: Gonodactylaceus falcatus (Stomatopoda), Neocaridina heteropoda (Decapoda), Neomysis integer (Mysida) and Parhyale hawaiensis (Amphipoda). We describe the patterns of muscle precursors in different embryonic stages to reconstruct the sequence of muscle development, until hatching of the larva or juvenile. Comparison of the developmental sequences between species reveals extensive heterochronic and heteromorphic variation. Clear anticipation of muscle differentiation in the nauplius segments, but also early formation of longitudinal trunk musculature independently of the teloblastic proliferation zone, are found to be characteristic to stomatopods and decapods, all of which share an egg-nauplius stage.

CONCLUSIONS

Our study provides a strong indication that the concept of nauplius recapitulation in Malacostraca is incomplete, because sequences of muscle tissue differentiation deviate from the chronological patterns observed in the ectoderm, on which the egg-nauplius is based. However, comparison of myogenic sequences between taxa supports the hypothesis of a zoea-like larva that was present in the last common ancestor of Eumalacostraca (Malacostraca without Leptostraca). We argue that much of the developmental sequences of larva muscle patterning were retained in the eumalacostracan lineage despite the reduction of free swimming nauplius larvae, but was severely reduced in the peracaridean clade.

The ultrastructure of the striated muscles of Derocheilocaris typica (Mystacocarida, Crustacea)

The striated muscles of Derocheilocaris typica consist of mononucleated cells, each containing one filament bundle. Large muscles consist of two or more cells adjacent to each other. The mitochondria line up along the filament bundle on one side. The nucleus is situated in the mitochondrial row and has a small cytoplasmic area around it filled with glycogen. The sarcomeres are between 3 and 6 μm long. The Z-line and H band are present. Six thin filaments surround one thick filament. All muscles belong to the phasic type. The tubular system emanates from the ends of the muscle cell and penetrates the whole cell. The tubules are formed as cisterns, which also open at the cell membrane at the level of the I bands. They have sarcoplasmic cisterns on both sides forming a continuous triad system. Partially transformed epidermal cells mediate muscle insertions on the cuticle. Tendons are formed with the transformed epidermal cells being supplemented by fibroblasts forming collagen fibers. Dorsal and ventral abdominal muscles are innervated from the dorso-lateral nerve arising from the nerve chain. Each muscle cell receives one axon, which forms one synapse on the mitochondrial-free side of the muscles. Axons form terminal spines, which make axo-axonal synapses.

Reconstruction of cell lineage and spatiotemporal pattern formation of the mesoderm in the amphipod crustacean Orchestia cavimana

BACKGROUND

Cell lineage studies in amphipods have revealed an early restriction of blastomere fate. The mesendodermal cell lineage is specified with the third cleavage of the egg. We took advantage of this stereotyped mode of development by fluorescently labeling the mesodermal precursors in embryos of Orchestia cavimana and followed the morphogenesis of the mesodermal cell layer through embryonic development.

RESULTS

The mesoderm of the trunk segments is formed by a very regular and stereotypic cell division pattern of the mesoteloblasts and their segmental daughters. The head mesoderm in contrast is generated by cell movements and divisions out of a mesendodermal cell mass. Our reconstructions reveal the presence of three different domains within the trunk mesoderm of the later embryo. We distinguish a cell group median to the limbs, a major central population from which the limb mesoderm arises and a dorsolateral branch of mesodermal cells.

CONCLUSIONS

Our detailed description of mesodermal development relates different precursor cell groups to distinct muscle groups of the embryo. A dorsoventral subdivision of mesoderm is prepatterned within the longitudinal mesodermal columns of the germ-band stage. This makes amphipods excellent crustacean models for studying mesodermal differentiation on a cellular and molecular level.

Myogenesis in the thoracic limbs of the American lobster

Newly hatched lobster larvae have biramous thoracic limbs composed of an endopodite, which is used for walking in the adult, and an exopodite used for swimming. Several behavioural and physiological aspects of larval locomotion as well the ontogeny of the neuromuscular system have been examined in developing decapod crustaceans. Nevertheless, the cellular basis of embryonic muscle formation in these animals is poorly understood. Therefore, the present report analyses muscle formation in embryos of the American lobster Homarus americanus Milne Edwards, 1837 (Malacostraca, Eucarida, Decapoda, Homarida) using the monoclonal antibody 016C6 that recognizes an isoform of myosin heavy chain. 016C6 labelling at 25% of embryonic development (E25%) revealed that syncytial muscle precursor cells establish the muscles in the endopodites. During subsequent embryogenesis, these muscle precursors subdivide into several distinct units thereby giving rise to pairs of antagonistic primordial muscles in each of the successive podomeres, the layout of which at E45% already resembles the arrangement in the adult thoracopods. The pattern of primordial muscles was also mapped in the exopodites of thoracic limbs three to eight. Immunohistochemistry against acetylated α-tubulin and against presynaptic vesicle-associated phosphoproteins at E45% demonstrated the existence of characteristic neural tracts within the developing limbs as well as putative neuromuscular synapses in both the embryonic exo- and endopodites. The results are compared to muscle development in other Crustacea.

Muscle development in the marbled crayfish--insights from an emerging model organism (Crustacea, Malacostraca, Decapoda)

The development of the crustacean muscular system is still poorly understood. We present a structural analysis of muscle development in an emerging model organism, the marbled crayfish--a representative of the Cambaridae. The development and differentiation of muscle tissue and its relation to the mesoderm-forming cells are described using fluorescent and non-fluorescent imaging tools. We combined immunohistochemical staining for early isoforms of myosin heavy chain with phallotoxin staining of F-actin, which distinguishes early and more differentiated myocytes. We were thus able to identify single muscle precursor cells that serve as starting points for developing muscular units. Our investigations show a significant developmental advance in head appendage muscles and in the posterior end of the longitudinal trunk muscle strands compared to other forming muscle tissues. These findings are considered evolutionary relics of larval developmental features. Furthermore, we document the development of the muscular heart tissue from myogenic precursors and the formation and differentiation of visceral musculature.

The embryonic development of the malacostracan crustacean Porcellio scaber (Isopoda, Oniscidea)

To examine the evolution of development and put it into a phylogenetic context, it is important to have, in addition to a model organism like Drosophila, more insights into the huge diversity of arthropod morphologies. In recent years, the malacostracan crustacean Porcellio scaber Latreille, 1804 has become a popular animal for studies in evolutionary and developmental biology, but a detailed and complete description of its embryonic development is still lacking. Therefore, the embryonic development of the woodlouse P. scaber is described in a series of discrete stages easily identified by examination of living animals and the widely used technique of nuclei staining on fixed specimens. It starts with the first cleavage of the zygote and ends with a hatched manca that eventually leaves the mother's brood pouch. Classical methods like normal light microscopy, scanning electron microscopy and fluorescence microscopy are used, in addition to confocal LCM and computer-aided 3D reconstruction in order to visualise important processes during ontogeny. The purpose of these studies is to offer an easy way to define the different degrees of development for future comparative analyses of embryonic development amongst crustaceans in particular, as well as between different arthropod groups. In addition, several aspects of Porcellio embryonic development, such as the mouth formation, limb differentiations and modifications or the formation of the digestive tract, make this species particularly interesting for future studies in evolutionary and developmental biology.

Pleonal muscle development in the shrimp Penaeus (Litopenaeus) vannamei (Crustacea: Malacostraca: Decapoda: Dendrobranchiata)

Penaeoidean shrimp pleonal muscle is a valuable economic resource worldwide, but little is known of its development during larval stages. The development of pleonal muscle in Penaeus (Litopenaeus) vannamei was studied by rhodamine-phalloidin staining and laser-scanning confocal microscopy. Dorsal pleonal muscle was first evident at the protozoea I stage while ventral pleonal muscle was present by the protozoea II stage. Identifiable ventral pleonal muscles were evident by the protozoea III stage and all ventral muscle types were present in the mysis I. The tail flex response began at the mysis stage and growth of existing pleonal muscles continued. The pleopods formed during the mysis stages, with coxal and basis muscles developed by mysis III. The pleopods became functional beginning with the first post-larval stage. We conclude that the pleonal muscle pattern of P. vannamei larvae is similar to that of adult Penaeus setiferus, and that homologous muscles are present. The major formation of dorsal pleonal muscles occurs during the protozoea II stage, while significant development of ventral pleonal muscles occurs during the protozoea III stage.

Three-dimensional reconstruction of the naupliar musculature and a scanning electron microscopy atlas of nauplius development of Balanus improvisus (Crustacea: Cirripedia: Thoracica)

An atlas of the naupliar development of the cirripede Balanus improvisus Darwin, 1854 using scanning electron microscopy (SEM) is provided. Existing spikes on the hindbody increase in number with each moult and are an applicable character for identification of the different nauplius stages, as is the setation pattern of the first antennae. The naupliar musculature of B. improvisus was stained with phalloidin to visualise F-actin, followed by analysis using confocal laser scanning microscopy (CLSM) with subsequent application of 3D imaging software. The larval musculature is already fully established in the first nauplius stage and remains largely unchanged during all the six nauplius stages. The musculature associated with the feeding apparatus is highly elaborated and the labrum possesses lateral muscles and distal F-actin-positive structures. The alimentary tract is entirely surrounded by circular muscles. The extrinsic limb musculature comprises muscles originating from the dorsal and the ventral sides of the head shield, respectively. The hindbody shows very prominent postero-lateral muscles that insert on the dorso-lateral side of the head shield and bend towards ventro-posterior. We conclude that the key features of the naupliar gross anatomy and muscular architecture of B. improvisus are important characters for phylogenetic inferences if analysed in a comparative evolutionary framework.