Caudal Muscle Research Articles

Effects of ecologically relevant concentrations of Boral® 500 SC, Glifosato® Biocarb, and a blend of both herbicides on markers of metabolism, stress, and nutritional condition factors in bullfrog tadpoles.

The aim of this study was to verify the effects of the isolated forms of Boral® SC 500, Glifosato® Biocarb herbicides, and a blend of both herbicides on metabolism and oxidative balance markers of Rana catesbeiana tadpoles and on their nutritional condition. Groups of tadpoles were divided into different treatments: control (no herbicides), Boral® 500 SC (sulfentrazone: 130μg/L), Glifosato® Biocarb (glyphosate: 234μg/L), and a blend of both herbicides. After 7days, the liver, caudal muscle, and blood samples were taken to subsequently perform the biomarkers determination by spectrophotometry. The intestinal condition factor increased in animals exposed to glyphosate and herbicide blends, suggesting a hyperphagic effect. This hypothesis was confirmed by the rise of triglycerides and circulating very low-density lipoprotein (VLDL). There was a significant increase in the levels of uric acid in tadpoles exposed to the herbicide blend. Corticosterone levels reduced significantly in animals exposed to glyphosate and the herbicide blend. Oxidative stress markers had a tissue-dependent response. In the liver, glutathione S-transferase increased, and superoxide dismutase and catalase decreased in animals exposed to sulfentrazone and glyphosate. Lipoperoxidation was reduced in the glyphosate treatment. In the caudal muscle, superoxide dismutase and catalase activities were maintained, and there was a decline in the levels of glutathione S-transferase and TBARS only in the blend group.

Caudal musculature in ground sharks, Carcharhiniformes, with remarks on their phylogenetic interrelationships.

Relationships among families of the shark order Carcharhiniformes are still being debated, for example, in relation to the inclusion of hammerhead sharks (Sphyrnidae) and the tiger shark (Galeocerdo cuvier) in the Carcharhinidae. Previous morphological studies have not analyzed the phylogenetic significance of axial caudal muscles among carcharhiniforms. The authors therefore describe here the axial muscles of the tail region (m. epaxialis, m. obliquus superioris, m. obliquus inferioris, m. flexor caudalis) to better understand their anatomical patterns among carcharhiniform sharks. Our results indicate that the family Pentanchidae, recently separated from scyliorhinids (catsharks), present a similar pattern of caudal muscles to catsharks, indicating their close phylogenetic relationship. Triakids, hemigaleids, leptochariids, Galeocerdo cuvier and Prionace glauca have a unique pattern in which the medial axial bundle is bulkier than all other caudal axial muscles. Sphyrnids share with carcharhinids a similar pattern of the m. obliquus superioris (approximately the same size as the dorsal m. epaxialis) and have fibers of the m. flexor caudalis arranged in a V-shape. This chevron-shape is also present on the m. flexor caudalis of hemigaleids and leptochariids. Also, sphyrnids and carcharhinids have more slender septa between muscle bundles (more notably in carcharhinids; the only exception is Galeocerdo cuvier, which has the same pattern as sphyrnids). Although being used here as an outgroup, Squaliformes is unique in lacking one of the epaxial bundles. The authors conclude that the caudal axial musculature has greater phylogenetic potential than previously understood.

Development of zebrafish paired and median fin musculature: basis for comparative, developmental, and macroevolutionary studies

The model organism Dario rerio (zebrafish) is widely used in evo-devo and comparative studies. Nevertheless, little is known about the development and differentiation of the appendicular musculature in this fish. In this study, we examined the development of the muscles of all five zebrafish fin types (pectoral, pelvic, anal, dorsal and caudal). We describe the development of the muscles of these fins, including some muscles that were never mentioned in the literature, such as the interhypurales of the caudal fin. Interestingly, these caudal muscles are present in early stages but absent in adult zebrafishes. We also compare various stages of zebrafish fin muscle development with the configuration found in other extant fishes, including non-teleostean actinopterygians as well as cartilaginous fishes. The present work thus provides a basis for future developmental, comparative, evolutionary and evo-devo studies and emphasizes the importance of developmental works on muscles for a more comprehensive understanding of the origin, development and evolution of the appendicular appendages of vertebrate animals.

Physicochemical and sensory characterization of three different portions from commercial pirarucu (Arapaima gigas) fillets

Abstract The objective of the present study was to investigate the relevant physicochemical and sensory parameters of three different Arapaima gigas muscle portions. Cranial, medial and caudal portions were analysed regarding their proximate compositions, instrumental colour and texture parameters, and sensory evaluations. The medial and caudal portions exhibited the greatest (P < 0.05) lipid contents and energy values and the lowest (P < 0.05) moisture and carbohydrate levels. The protein contents were similar (P > 0.05) for the different muscle portions. Before cooking, the medial and caudal portions displayed the greatest (P < 0.05) values for lightness, redness, hardness and chewiness. After cooking, no differences ( P > 0.05) were observed between the different muscle portions for the instrumental colour parameters, while the medial portion exhibited lower (P < 0.05) values for hardness and chewiness as compared to the caudal portion. The cranial portion received the lowest (P < 0.05) scores for flavour and overall liking. Thus the Arapaima gigas medial and caudal muscle portions presented the greatest potentials to satisfy the consumer requirements.

A new species of Camallanidae (Raillet and Henry, 1917) from a siluroid catfish in Barak River, Jiribam, Manipur (India).

Based on the two Camallanid gravid females recovered from the intestine of siluroid catfish Aorichthys aor (Hamilton, 1822) in Barak River, Jiribam, Manipur, India, Procamallanus (Spirocamallanus) jiriensis n. sp. is described. It is morphologically characterized by 20-24 (9-incomplete) spiral thickenings (ridges), occupying posterior 2/3rd of the buccal capsule. The present species differs from its closely related species Procamallanus (Spirocamallanus) chauhani (Sahay in Indian J Helminthol 18(2):114-122, 1966) in many aspects such as two pair of teeth antero laterally present in oral cavity, a pair of finger-shaped thickenings, which is laterally present at the buccal capsule, presence of well-developed globular vulvar lips, vagina directed posteriorly from vulva, a small conical spike-like projection at the rounded tail tip with well-developed caudal muscles and papillae.

Linking muscle metabolism and functional variation to field swimming performance in bluegill sunfish (Lepomis macrochirus).

Skeletal muscle has diverse mechanical roles during locomotion. In swimming fish, power-producing muscles work in concert with the accessory muscles of the fins which augment and control power transfer to the water. Although fin muscles represent a significant proportion of the locomotor muscle mass, their physiological properties are poorly characterized. To examine the relationship between muscle metabolism and the differing mechanical demands placed on distinct muscle groups, we quantified the aerobic and glycolytic capacities of the myotomal, pectoral and caudal muscles of bluegill sunfish. These were indicated by the activities of citrate synthase and lactate dehydrogenase, rate-limiting enzymes for aerobic respiration and glycolysis, respectively. The well-established roles of slow and fast myotomal muscle types in sustained and transient propulsive movements allows their use as benchmarks to which other muscles can be compared to assess their function. Slow myotomal muscle had the highest CS activity, consistent with meeting the high metabolic and mechanical power demands of body-caudal fin (BCF) swimming at the upper end of the aerobically supported speed range. The largest pectoral adductors and abductors had CS activities lower than the slow myotomal muscle, in line with their role supplying thrust for low-speed, low-power swimming. The metabolic capacities of the caudal muscles were surprisingly low and inconsistent with their activity during steady-state BCF swimming at high speeds. This may reflect adaptation to the observed swimming behavior in the field, which typically involved short bouts of BCF-propulsive cycles rather than sustained propulsive activity.

A new small-bodied ornithopod (Dinosauria, Ornithischia) from a deep, high-energy Early Cretaceous river of the Australian-Antarctic rift system.

A new small-bodied ornithopod dinosaur, Diluvicursor pickeringi, gen. et sp. nov., is named from the lower Albian of the Eumeralla Formation in southeastern Australia and helps shed new light on the anatomy and diversity of Gondwanan ornithopods. Comprising an almost complete tail and partial lower right hindlimb, the holotype (NMV P221080) was deposited as a carcass or body-part in a log-filled scour near the base of a deep, high-energy river that incised a faunally rich, substantially forested riverine floodplain within the Australian–Antarctic rift graben. The deposit is termed the ‘Eric the Red West Sandstone.’ The holotype, interpreted as an older juvenile ∼1.2 m in total length, appears to have endured antemortem trauma to the pes. A referred, isolated posterior caudal vertebra (NMV P229456) from the holotype locality, suggests D. pickeringi grew to at least 2.3 m in length. D. pickeringi is characterised by 10 potential autapomorphies, among which dorsoventrally low neural arches and transversely broad caudal ribs on the anterior-most caudal vertebrae are a visually defining combination of features. These features suggest D. pickeringi had robust anterior caudal musculature and strong locomotor abilities. Another isolated anterior caudal vertebra (NMV P228342) from the same deposit, suggests that the fossil assemblage hosts at least two ornithopod taxa. D. pickeringi and two stratigraphically younger, indeterminate Eumeralla Formation ornithopods from Dinosaur Cove, NMV P185992/P185993 and NMV P186047, are closely related. However, the tail of D. pickeringi is far shorter than that of NMV P185992/P185993 and its pes more robust than that of NMV P186047. Preliminary cladistic analysis, utilising three existing datasets, failed to resolve D. pickeringi beyond a large polytomy of Ornithopoda. However, qualitative assessment of shared anatomical features suggest that the Eumeralla Formation ornithopods, South American Anabisetia saldiviai and Gasparinisaura cincosaltensis, Afro-Laurasian dryosaurids and possibly Antarctic Morrosaurus antarcticus share a close phylogenetic progenitor. Future phylogenetic analysis with improved data on Australian ornithopods will help to test these suggested affinities.

Comparative expression analyses of bone morphogenetic protein 4 (BMP4) expressions in muscles of tilapia and common carp indicate that BMP4 plays a role in the intermuscular bone distribution in a dose-dependent manner

Intermuscular bones in fish negatively influence both meet processing and attractiveness to consumers. Tilapia (Oreochromis niloticus) and common carp (Cyprinus carpio) are both major farmed fish species globally, but whereas the former does not possess intermuscular bones, the latter does. Therefore, these two species might present a good model to study the genetic control of distribution of intermuscular bones in fish. Bone morphogenetic protein 4 (BMP4) gene is associated with tissue ossification and bone regeneration in mammals, but in fish its role in ossification remains understudied. To study the relationship between BMP4 and bone distribution in fish, we determined the expression of BMP4 in muscle tissues of common carp and tilapia on transcriptional and translational levels. As the gene has been merely predicted in silico from the genome of common carp, we have cloned and characterized it. The gene (GenBank: HQ446455) contains one intron and two exons, which encode a 400-amino acid protein with high homology to other known BMP4 protein sequences. Phylogenetic analysis showed that common carp clustered within the Cypriniformes clade (zebrafish was the closest ortholog) and tilapia within the Percomorpha clade. Using microCT scanning, we confirmed that intermuscular bones could be observed only in common carp (none in tilapia), but only in dorsal and caudal muscles (none in the ventral muscle). Expression levels of BMP4 in the muscles of common carp were in agreement with this observation both on transcriptional (qPCR) and translational (immunohistochemistry) level: higher in dorsal and caudal muscles, and lower in the ventral muscle. In tilapia, expression of BMP4 gene was also detectable in all three muscles, but expression levels in all three muscles were comparable to the one observed in the ventral muscle of carp, i.e., very low. Therefore, among the six studied muscles, the expression of BMP4 was high only in the two that possess intermuscular bones: dorsal and caudal muscles of common carp. The results of this study suggest that BMP4 is likely to play a key role in the determination of intermuscular bone distribution in fish in a dose-dependent manner.

Non-lethal heat shock induces Hsp70 synthesis and promotes tolerance against heat, ammonia and metals in post-larvae of the white leg shrimp Penaeus vannamei (Boone, 1931)

Exposure to temperatures above ambient compromises normal physiological processes and adversely affects aquatic organisms. Nonetheless, non-lethal heat shock (NLHS) protects aquatic organisms against abiotic and biotic stress, perhaps due in part to the accumulation of heat shock protein 70 (Hsp70), a well conserved molecular chaperone. Hsp70 protects cells against stress-induced damage by assisting in the recovery of misfolded proteins, facilitating the folding of nascent proteins and promoting protein degradation. In this study, the immunoprobing of western blots containing protein extracts from the caudal muscle of heated and non-heated post-larvae (PL) of the shrimp, Penaeus vannamei with an antibody specific to Hsp70 revealed that NLHS enhanced Hsp70 build-up in the caudal tissues of shrimp PL. Moreover, exposure to NLHS protected P. vannamei PL against heat, ammonia and heavy metals. The findings in this paper indicate that Hsp70 synthesized in response to NLHS contributed to the protection of P. vannamei PL against several different abiotic stressors. Such findings are potentially useful in the formulation of strategies to protect Penaeid shrimps against environmental stresses during aquaculture.

Influence of the Herbicide Facet® on Corticosterone Levels, Plasma Metabolites, and Antioxidant System in the Liver and Muscle of American Bullfrog Tadpoles

This study sought to analyze the effects of the herbicide quinclorac on body condition indices; plasma levels of corticosterone, glucose, and uric acid; activity of the antioxidant enzymes superoxide dismutase (SOD), catalase (CAT), and glutathione S-transferase (GST); and levels of lipid peroxidation (LPO) in the liver and caudal muscle of American bullfrog (Rana catesbeiana) tadpoles. After a 7-day acclimation period, animals were exposed to four concentrations (0.05, 0.1, 0.2, and 0.4 μg/L) of herbicide for a further 7 days. Then, blood samples were obtained, animals were euthanized, and the liver and caudal muscle resected. Levels of corticosterone and uric acid were reduced in tadpoles exposed to the highest concentration of herbicide, and this reduction was preceded by an increase in glucose levels. In the liver tissue, LPO was increased after exposure to 0.1 μg/L quinclorac, followed by a return to baseline values in the remaining concentrations; this response was accompanied by an increase in SOD and GST and reduction of tissue protein levels. At the highest concentration, a reduction in activity of all enzymes was observed, with protein returning to control-like levels. In muscle, SOD and GST levels declined with exposures up to 0.1 g/L and 0.4 μg/L, respectively, whereas LPO decreased in animals exposed to 0.1 μg/L. These results suggest participation of nonenzymatic antioxidant defenses, as demonstrated by the reduction in uric acid levels. Exposure to the range of quinclorac concentrations used in this study slowed body mass and length gain, reduced corticosterone levels, and modulated antioxidant defenses.

Ontogeny of myosin isoform expression and prehensile function in the tail of the gray short-tailed opossum (Monodelphis domestica).

Terrestrial opossums use their semiprehensile tail for grasping nesting materials as opposed to arboreal maneuvering. We relate the development of this adaptive behavior with ontogenetic changes in myosin heavy chain (MHC) isoform expression from 21 days to adulthood. Monodelphis domestica is expected to demonstrate a progressive ability to flex the distal tail up to age 7 mo, when it should exhibit routine nest construction. We hypothesize that juvenile stages (3-7 mo) will be characterized by retention of the neonatal isoform (MHC-Neo), along with predominant expression of fast MHC-2X and -2B, which will transition into greater MHC-1β and -2A isoform content as development progresses. This hypothesis was tested using Q-PCR to quantify and compare gene expression of each isoform with its protein content determined by gel electrophoresis and densitometry. These data were correlated with nesting activity in an age-matched sample of each age group studied. Shifts in regulation of MHC gene transcripts matched well with isoform expression. Notably, mRNA for MHC-Neo and -2B decrease, resulting in little-to-no isoform translation after age 7 mo, whereas mRNA for MHC-1β and -2A increase, and this corresponds with subtle increases in content for these isoforms into late adulthood. Despite the tail remaining intrinsically fast-contracting, a critical growth period for isoform transition is observed between 7 and 13 mo, correlating primarily with use of the tail during nesting activities. Functional transitions in MHC isoforms and fiber type properties may be associated with muscle "tuning" repetitive nest remodeling tasks requiring sustained contractions of the caudal flexors.NEW & NOTEWORTHY Little is understood about skeletal muscle development as it pertains to tail prehensility in mammals. This study uses an integrative approach of relating both MHC gene and protein expression with behavioral and morphometric changes to reveal a predominant fast MHC expression with subtle isoform transitions in caudal muscle across ontogeny. The functional shifts observed are most notably correlated with increased tail grasping for nesting activities.

Postural response characterization of standing humans to multi-directional, predictable and unpredictable perturbations to the arm

When the arm of a standing human is perturbed in an unpredictable direction, postural muscles are activated at latencies as short as 50–110ms. While the motion of the body clearly progresses in hand-to-leg sequence, there is no systematic muscle activation sequence from the arm to the leg muscles, suggesting that the activation of the muscles is not likely the result of local stretch reflexes. In fact, the lower limb muscles are activated before the upright posture is significantly disturbed. The short-latency activation amplitude and the activation probability are clearly tuned to the direction of the arm perturbation for both rostral and caudal muscles. The effect of central set on the short-latency response has been investigated by manipulating the predictability of the perturbations. Possible underlying neural mechanisms have been discussed.

Anatomic study of the musculus longus capitis flap.

To clearly delineate the anatomy of the musculus longus capitis, determine its clinical applications for reconstruction surgery, and provide a safer surgical method of developing the longus capitis muscle flap. Anatomical investigations were performed in seven adult cadavers (five cadavers for gross anatomy and two for transparent specimen preparation) with respect to the location, morphology, arterial supply, and innervation of the musculus longus capitis, as well as its spatial relationship with the cervical sympathetic trunk, superior cervical ganglion, carotid sheath, and other surrounding structures. The musculus longus capitis is located anterior to the C1-6 vertebrae, segmentally supplied by branches of the ascending cervical artery, innervated by the C1-5 nerve, and spatially close to the cervical sympathetic trunk, superior cervical ganglion, and carotid sheath. These anatomic findings indicate that the development of a cranial or caudal pedicled longus capitis muscle flap is feasible. The musculus longus capitis can be developed into a cranial or caudal pedicled flap for repair of head and neck defects with negligible morbidity of the donor site.

Effects of sustained exercise on GH-IGFs axis in gilthead sea bream (Sparus aurata)

The endocrine system regulates growth mainly through the growth hormone (GH)/insulin-like growth factors (IGFs) axis and, although exercise promotes growth, little is known about its modulation of these factors. The aim of this work was to characterize the effects of 5 wk of moderate sustained swimming on the GH-IGFs axis in gilthead sea bream fingerlings. Plasma IGF-I/GH ratio and tissue gene expression of total IGF-I and three splice variants, IGF-II, three IGF binding proteins, two GH receptors, two IGF-I receptors, and the downstream molecules were analyzed. Fish under exercise (EX) grew more than control fish (CT), had a higher plasma IGF-I/GH ratio, and showed increased hepatic IGF-I expression (mainly IGF-Ia). Total IGF-I expression levels were similar in the anterior and caudal muscles; however, IGF-Ic expression increased with exercise, suggesting that this splice variant may be the most sensitive to mechanical action. Moreover, IGFBP-5b and IGF-II increased in the anterior and caudal muscles, respectively, supporting enhanced muscle growth. Furthermore, in EX fish, hepatic IGF-IRb was reduced together with both GHRs; GHR-II was also reduced in anterior muscle, while GHR-I showed higher expression in the two muscle regions, indicating tissue-dependent differences and responses to exercise. Exercise also increased gene and protein expression of target of rapamycin (TOR), suggesting enhanced muscle protein synthesis. Altogether, these data demonstrate that moderate sustained activity may be used to increase the plasma IGF-I/GH ratio and to potentiate growth in farmed gilthead sea bream, modulating the gene expression of different members of the GH-IGFs axis (i.e., IGF-Ic, IGF-II, IGFBP-5b, GHR-I, and TOR).

The tadpoles of two species of the Bokermannohyla circumdata group (Hylidae, Cophomantini).

We describe the external morphology and oral cavity of the tadpoles of Bokermannohyla caramaschii and B. diamantina respectively from the states of Espírito Santo and Bahia, Brazil. Larvae of both species are distinguished from each other by external characters such as body shape, labial tooth-row formula, number of marginal papillae, coloration and internal oral anatomy features. Some of the character states of the tadpoles of B. caramaschii and B. diamantina that are shared with all other described tadpoles of the Bokermannohyla circumdata group, such as the absence/reduction of small flaps with accessory labial teeth laterally in the oral disc, and the absence/reduction of submarginal papillae, may represent morphological synapomorphies of this species group, or at least of some internal clade. The general pattern of brownish coloration with longitudinal stripes on the caudal muscle is also common to most species of the group. We did not find character states of the oral cavity that are exclusively shared by species of the B. circumdata group, or by other groups of Bokermannohyla.

Bases ósseas e musculares dos cortes comerciais da cauda de jacaré-do-Pantanal (Caiman yacare Daudin 1802)

A exploração comercial de jacaré-do-Pantanal (Caiman yacare) constitui importante cadeia produtiva no Estado de Mato Grosso. As características nutricionais e representatividade na massa corporal de crocodilianos tornaram a região da cauda objeto de estudos morfofisiológicos, evolutivos e tecnológicos. Como inexiste a caracterização anatômica dos músculos e ossos que constituem os cortes comerciais dessa região, objetivou-se descrever os músculos e correspondentes bases ósseas da cauda. Na descrição óssea, foram utilizados um exemplar adulto e seis juvenis. Para caracterização muscular, 24 espécimes juvenis foram conservados em freezer e dissecados a fresco, em ambos os antímeros, para verificação de simetria de ocorrência, fixações musculares, relacões de sintopia, forma e arquitetura muscular. As vértebras caudais são procélicas, exceto a primeira da série, e possuem na superfície ventral do corpo áreas para articulação com os processos hemais, exceto a primeira e as quatro ou cinco últimas. Os cortes comerciais da região são o filé de cauda, composto pelos músculos semiespinhal caudal, longuíssimo caudal, ilioisquiocaudal, caudofemoral longo, transverso e profundo da cauda, enquanto o corte ponta de cauda é constituído pelos músculos longuíssimo caudal e ilioisquiocaudal, com as cinco ou seis últimas vértebras caudais.

The Tyrosine Kinase Pyk2 Promotes Sustained Contraction of Vascular Smooth Muscle and is Activated Downstream of Calcium Entry

Objective: Sustained contraction of vascular smooth muscle is elicited by Ca2+ sensitization, which involves activation of the RhoA/Rho-kinase pathway and inhibition of myosin light-chain phosphatase (MLCP). We demonstrated previously that the tyrosine kinase Pyk2 becomes activated in rat caudal arterial smooth muscle during sustained contraction induced by membrane depolarization, and that contraction is inhibited by Pyk2 inhibitors. For the current work, we focused on the activation of Pyk2 by upstream signals. Methods: Rat caudal arterial smooth muscle strips were contracted either by 87 mM K+, 5 mM sodium orthovanadate or 10 μM ionomycin in HEPES-Tyrode's solution. Contractile force was measured by wire myography. Results: Sustained contraction of rat caudal arterial smooth muscle was sensitive to inhibition by Pyk2 inhibitors (IC50 = 0.49 ± 0.07 µM) which correlated with inhibition of Pyk2 autophosphorylation, while the initial rapid contraction was only inhibited at higher concentrations (IC50 = 2.4...

A possible instance of sexual dimorphism in the tails of two oviraptorosaur dinosaurs.

The hypothesis that oviraptorosaurs used tail-feather displays in courtship behavior previously predicted that oviraptorosaurs would be found to display sexually dimorphic caudal osteology. MPC-D 100/1002 and MPC-D 100/1127 are two specimens of the oviraptorosaur Khaan mckennai. Although similar in absolute size and in virtually all other anatomical details, the anterior haemal spines of MPC-D 100/1002 exceed those of MPC-D 100/1127 in ventral depth and develop a hitherto unreported “spearhead” shape. This dissimilarity cannot be readily explained as pathologic and is too extreme to be reasonably attributed to the amount of individual variation expected among con-specifics. Instead, this discrepancy in haemal spine morphology may be attributable to sexual dimorphism. The haemal spine form of MPC-D 100/1002 offers greater surface area for caudal muscle insertions. On this basis, MPC-D 100/1002 is regarded as most probably male, and MPC-D 100/1127 is regarded as most probably female.

Comparative Anatomy of Caudal Musculature Attachments in Catarrhines with Different Tail Length

Comparative Anatomy of Caudal Musculature Attachments in Catarrhines with Different Tail Length

Biliary excretion of tetrodotoxin in the cultured pufferfish Takifugu rubripes juvenile after intramuscular administration

Marine pufferfish of the family Tetraodontidae accumulate a considerable amount of tetrodotoxin (TTX), mainly in the liver and ovary. The detailed distribution of TTX in pufferfish body tissues, however, remains poorly understood. Here we investigated the tissue distribution and biliary excretion of TTX in cultured pufferfish Takifugu rubripes juveniles (6-month-old, 81.5 ± 2.0 g body weight) for 24 h after intramuscular administration of 0.25 μg TTX/g body weight into the caudal muscle. The blood TTX concentration was 0.53 ± 0.15 μg/mL at 1 h, and gradually decreased to 0.05 ± 0.01 μg/mL at 24 h after administration (p < 0.05). The TTX concentration in the liver declined from 1.59 ± 0.10 μg/g at 1 h to 0.48 ± 0.21 μg/g at 24 h (p < 0.05). In contrast, the TTX concentration in the skin increased from 0.27 ± 0.04 μg/g at 1 h to 0.48 ± 0.08 μg/g at 24 h (p < 0.05). The concentration of TTX in the bile remarkably increased from 0.08 ± 0.03 μg/mL at 1 h to 0.39 ± 0.05 μg/mL at 8 h (p < 0.05) and remained at almost the same level at 24 h. These findings indicate that TTX was excreted from the liver into the gallbladder bile in the pufferfish T. rubripes juveniles.