Trunk Of Fish Research Articles

Advancing cortisol measurements in zebrafish: Analytical validation of a commercial ELISA kit for skin mucus cortisol analysis

Cortisol is the main stress biomarker used for zebrafish. However, zebrafish small size made it challenging to extract cortisol without harming or killing the fish. Thus, researchers adopted a terminal method, the trunk cortisol, as standard practice. Here, we developed and validated an alternative and minimally invasive technique for measuring cortisol in the skin mucus of adult zebrafish, using a commercial enzyme-linked immunosorbent assay (ELISA). For this, AB zebrafish were randomly assigned to a precision, accuracy, and specificity test. Each sample contained the skin mucus of five to ten fish or one fish trunk. The cortisol was extracted using methanol as organic solvent. The results obtained showed an adequate precision (intra-assay coefficient of variation (CV) <15%; inter-assay CV = 26%), accuracy (CV <120%), and specificity (r2 =0.96–0.98) for skin mucus cortisol levels, as well as for trunk cortisol.•A commercial ELISA was analytically validated to measure cortisol in the skin mucus of zebrafish.•Skin mucus cortisol is a non-terminal method that reduce the number of animals used and allows longitudinal studies.

Development and application of a sensitive droplet digital PCR for the detection of red mark syndrome infection in rainbow trout (Oncorhynchus mykiss)

Red Mark Syndrome (RMS) is a skin disease of uncertain etiology affecting farmed rainbow trout (Oncorhynchus mykiss). It consists of single or multiple skin lesions usually localized on the trunk of fish approaching market size.Studies showed as rickettsia-like organism (RLO), currently referred as Midichloria-like organism (MLO), is supposed to be involved in RMS.Midichloria-like has been identified consistently in RMS-affected fish. Its identification within skin and spleen has been possible through the use of PCR methods, including standard PCR, nested PCR and quantitative PCR (qPCR).Droplet digital PCR (ddPCR) is a relatively novel, sensitive, accurate and absolute quantification technique. Recent studies applied successfully this technique to infectious spleen and kidney necrosis virus (ISKNV) in teleosts, proving its superiority when compared to qPCR.The goal of the present study is to establish a sensitive ddPCR method to rapidly detect and quantify MLO DNA.We explored the feasibility of ddPCR to detect MLO from 40 rainbow trout spleen samples and compared the data with qPCR. The detection limit of the ddPCR was found to be 2.25 copy number, which is lower than the 36 copy number determined for TaqMan real-time PCR (qPCR). This indicated that the sensitivity of the ddPCR assay was one order of magnitude higher than the sensitivity of the qPCR assay. The detection results for fish samples showed that the positive detection rate of ddPCR (65%) was higher than that of qPCR (52.5%).The method used has revealed to be specific to MLO and does not cross-react with other fish bacterial DNA. The ddPCR method established in this study shows superiority for detection in minimal volume samples with low bacterial loads and may be used both as surveillance of possible transmission routes and potential sources.

Dietary isoleucine improved flesh quality, muscle antioxidant capacity, and muscle growth associated with AKT/TOR/S6K1 and AKT/FOXO3a signaling in hybrid bagrid catfish (Pelteobagrus vachelli\u2640 \xd7 Leiocassis longirostris\u2642)

BackgroundMuscle is the complex and heterogeneous tissue, which comprises the primary edible part of the trunk of fish and mammals. Previous studies have shown that dietary isoleucine (Ile) exerts beneficial effects on growth in aquatic animals. However, there were limited studies regarding the benefits of Ile on fish muscle and their effects on flesh quality and muscle growth. Thus, this study was conducted to explore whether dietary Ile had affected flesh quality and muscle growth in hybrid bagrid catfish (Pelteobagrus vachelli♀ × Leiocassis longirostris♂).MethodsA total of 630 hybrid fish, with an initial average body weight of 33.11 ± 0.09 g, were randomly allotted into seven experimental groups with three replicates each, and respectively fed seven diets with 5.0, 7.5, 10.0, 12.5, 15.0, 17.5, and 20.0 g Ile/kg diets for 8 weeks.ResultsIn the present study, we demonstrated that Ile significantly: (1) increased muscle protein and lipid contents and the frequency distribution of myofibers with ≤ 20 μm and ≥ 50 μm of diameter; (2) improved pH value, shear force, cathepsin B and L activities, hydroxyproline content, resilience, cohesiveness, and decreased cooking loss, lactate content, hardness, springiness, gumminess, and chewiness; (3) decreased reactive oxygen species (ROS), malondialdehyde (MDA), and protein carbonyl (PC) contents, GCLC and Keap1 mRNA levels, and up-regulated CuZnSOD, CAT, GPX1a, GST, and Nrf2 mRNA levels; (4) up-regulated the insulin-like growth factor 1, 2 (IGF-1, IGF-2), insulin-like growth factor 1 receptor (IGF-1R), proliferating cell nuclear antigen (PCNA), Myf5, Myod, Myog, Mrf4, and MyHC mRNA levels, and decreased MSTN mRNA level; (5) increased muscle protein deposition by activating AKT-TOR-S6K1 and AKT-FOXO3a signaling pathways.ConclusionThese results revealed that dietary Ile improved flesh quality, which might be due to increasing nutritional content, physicochemical, texture parameters, and antioxidant ability; promoting muscle growth by affecting myocytes hyperplasia and hypertrophy, and muscle protein deposition associated with protein synthesis and degradation signaling pathways. Finally, the quadratic regression analysis of chewiness, ROS, and protein contents against dietary Ile levels suggested that the optimal dietary Ile levels for hybrid bagrid catfish was estimated to be 14.19, 12.36, and 12.78 g/kg diet, corresponding to 36.59, 31.87, and 32.96 g/kg dietary protein, respectively.

A proposed role for non-junctional transverse tubules in skeletal muscle as flexible segments allowing expansion of the transverse network.

Using a variety of technical approaches, we have detected the presence of continuous triads that cover the entire length of T tubules in the main white body muscles of several small fish. This is in contrast to the discontinuous association of sarcoplasmic reticulum with T tubules in the red muscles from the same fish as well as in all other previously described muscles in a large variety of skeletal muscles. We suggest that continuous triads are permissible only in muscle fibers that are not normally subject to significant changes in sarcomere length during normal in vivo activity, as is the case for white muscles in the trunk of fish.

Post-release behaviour and survival of recreationally-angled arapaima (Arapaima cf. arapaima) assessed with accelerometer biologgers

Recreational fisheries are increasingly important sectors of tourism-based economies. In the last decade, new recreational fisheries have emerged that target species of varying conservation status including vulnerable, endangered, and unassessed species. In Guyana, catch-and-release angling tourism has begun to target arapaima, a genus of giant air-breathing fishes. Given the uncertain conservation status of this species and that no information is available to evaluate the sustainability of this activity, we sought to describe the responses of arapaima to recreational angling. We harnessed tri-axial accelerometer biologgers around the trunk of fish that had been captured and released by recreational anglers, allowing us to monitor post-release survival and behaviour, including surfacing, which is essential for this air-breathing fish to recover from exhaustion. Twenty-seven individuals were instrumented (162 ± 25 cm), 24 of which were considered survivors (89%) during the 47 ± 35 (SD) min monitoring period. Fish that died were observed to drown soon after release (i.e. within minutes), not surfacing to breathe air. Supervised machine learning classification of behaviours using a random forest algorithm identified surfacing events with 80% accuracy (i.e. out-of-bag error rate = 20%), which we applied to unobserved data periods to estimate breathing frequency after release, along with overall dynamic body acceleration (ODBA) as a proxy for activity. Neither mean breathing frequency nor ODBA were related to body size (total length), handling time (which incorporated facilitated recovery of individuals), nor time of capture (early or late in the dry season spanning water temperatures of 29.3–34.1 °C). The precise angling-related factors that led to arapaima mortality were unclear, but the frequency of mortality aligns with the mortality documented in other recreational fisheries. This mortality source can be incorporated into conservation plans and provide context to the impacts of recreational angling relative to the costs of legal or illegal harvest.

Neural Crest Transplantation Reveals Key Roles in the Evolution of Cavefish Development.

Evolutionary changes in Astyanax mexicanus cavefish with respect to conspecific surface fish, including the regression of eyes, loss of pigmentation, and modification of the cranial skeleton, involve derivatives of the neural crest. However, the role of neural crest cells in cavefish evolution and development is poorly understood. One of the reasons is that experimental methods for neural crest analysis are not well developed in the Astyanax system. Here we describe neural crest transplantation between Astyanax surface fish and cavefish embryos. We found differences in the migration of cranial neural crest cells transplanted from the surface fish anterior hindbrain to the same region of surface fish or cavefish hosts. Cranial neural crest cells migrated extensively throughout the head, and to a lesser extent the trunk, in surface fish hosts but their migration was mostly restricted to the anterior and dorsal head regions in cavefish hosts. Cranial neural crest cells derived from the surface fish transplants invaded the degenerating eyes of cavefish hosts, resulting in increased eye size and suggesting that cavefish neural crest cells are defective in forming optic derivatives. We found that melanophores were formed in albino cavefish from grafts of surface fish trunk neural crest cells, showing that the cavefish tissue environment is conducive for pigment cell development, and implicating intrinsic changes in cavefish neural crest cells in loss of body pigmentation. It is concluded that changes in neural crest cells play key roles in the evolution of cavefish development.

Immune response of olive flounder (Paralichthys olivaceus) infected with the myxosporean parasite Kudoa septempunctata

This study evaluated the pathophysiological, biochemical, and immunological status of olive flounder (Paralichthys olivaceus) infected with the myxosporean parasite Kudoa septempunctata. Flounder fish collected from Kudoa-infected and uninfected farms were confirmed by microscopic and TaqMan probe-based quantitative PCR screening. Morphological, biochemical, histological, and immune gene expression analyses were performed on uninfected and infected hosts to assess the effect of K. septempunctata. Histological studies confirmed the presence of Kudoa myxospores in the trunk muscles of infected flounder fish. Serum biochemical parameters, including the levels of myeloperoxidase activity, superoxide dismutase activity, alanine aminotransferase, alkaline phosphatase, amylase, bilirubin, total protein, cholesterol, calcium, potassium, sodium, phosphorus, glucose, and galactose, were found to exhibit no significant variations (p > 0.05) between uninfected and infected flounder fish. However, immune-related genes such as Mx, lysozyme, signal transducer and activator of transcription 1, interferon-γ, interferon regulatory factor, and tumour necrosis factor showed significantly elevated expression (p < 0.05) in the trunk muscles of infected flounder fish while no significant differences were noted in uninfected fish trunk muscle and head-kidney of infected and uninfected flounder fish.

Development of the ultrastructure of sonic muscles: a kind of neoteny?

BackgroundDrumming muscles of some sound-producing fish are ‘champions’ of contraction speed, their rate setting the fundamental frequency. In the piranha, contraction of these muscles at 150 Hz drives a sound at the same frequency. Drumming muscles of different not closely related species show evolutionary convergences. Interestingly, some characters of sonic muscles can also be found in the trunk muscles of newly hatched larvae that are able to maintain tail beat frequencies up to 100 Hz. The aim of this work was to study the development of sound production and sonic and epaxial muscles simultaneously in the red bellied piranhas (Pygocentrus nattereri) to seek for possible common characteristics.ResultsCall, pulse and period durations increased significantly with the fish size, but the call dominant frequencies decreased, and the number of pulses and the call amplitude formed a bell curve. In epaxial muscles, the fibre diameters of younger fish are first positioned in the graphical slope corresponding to sonic muscles, before diverging. The fibre diameter of older fish trunk muscles was bigger, and the area of the myofibrils was larger than in sonic muscles. Moreover, in two of the biggest fish, the sonic muscles were invaded by fat cells and the sonic muscle ultrastructure was similar to the epaxial one. These two fish were also unable to produce any sound, meaning they lost their ability to contract quickly.ConclusionsThe volume occupied by myofibrils determines the force of contraction, the volume of sarcoplasmic reticulum sets the contraction frequency, and the volume of mitochondria sets the level of sustained performance. The functional outcomes in muscles are all attributable to shifts in the proportions of those structures. A single delay in the development restricts the quantity of myofibrils, maintains a high proportion of space in the sarcoplasm and develops sarcoplasmic reticulum. High-speed sonic muscles could thus be skeletal muscles with delayed development. This hypothesis has the advantage that it could easily explain why high-speed sonic muscles have evolved so many times in different lineages.

ECOLOGICAL RISK ASSESSMENT OF HEAVY METALS IN INTEGRATED POULTRY- FISH FARMING

This report gives a preliminary assessment of ecological risk presented by heavy metals; cadmium, chromium, copper, lead and zinc in integrated poultry-fish farming. Water and sediment samples taken from a fish pond receiving poultry (chicken) manure as part of the feed were analysed for physicochemical properties and levels of the heavy metals. The heavy metals content of the sediment samples were found be markedly higher (MTotal 10.70±1.60 mg.kg-1 and contained 0.80±0.10 mg.kg-1 As; 1.00±0.30 mg.kg-1 Cd; 0.60±0.10 mg.kg-1 Cr; 2.40±0.10 mg.kg-1 Cu; 1.00±0.20 mg.kg -1 Pb and 4.90±0.90 mg.kg-1 Zn) than in the pond water (MTotal 0.85 mg.l-1) giving values of partition coefficient, measured in terms of the ratio of the levels of metals in the pond to the levels in the sediment of 0.08 with respect to the total levels of the metals and as low as 0.04 for Cu and Zn. The levels of the heavy metlas (MTotal 2.80±0.21) in the poultry manure were higher than in the pond water but markedly lower than in the sediment (MTotal 10.70±1.30 mg.kg-1). Five fish were taken from the pond, sacrificed; the fills and flesh taken from the fish trunk were dried. The levels of the heavy metals in the fish samples were generally low; MTotal 5.462±0.792 mg.kg-1 containing 0.758±0.008 mg.kg-1dw As; 2.880±0.648 mg.kg-1dw Zn; 0.126±0.001 mg.kg-1dw Cr; 1.240±0.098 mg.kg-1dw Cu; 0.322±0.018 mg.kg-1dw Cd and 0.136±0.020 mg.kg-1dw Pb, with the levels of the heavy metals in the fish gills expectedly higher than in the fish tissues. The levels of the heavy metals in the fish tissues were generally higher than in the pond water giving values of bioaccumulation index greater than 1.0 but less than 2.0. The levels of the heavy metals in the fish tissues were found to be lower than their toxicity reference values giving values of hazard quotient lower than 1.0 and suggesting that the heavy metals may not present imminent ecological concern.

An exclusively mesodermal origin of fin mesenchyme demonstrates that zebrafish trunk neural crest does not generate ectomesenchyme

The neural crest is a multipotent stem cell population that arises from the dorsal aspect of the neural tube and generates both non-ectomesenchymal (melanocytes, peripheral neurons and glia) and ectomesenchymal (skeletogenic, odontogenic, cartilaginous and connective tissue) derivatives. In amniotes, only cranial neural crest generates both classes, with trunk neural crest restricted to non-ectomesenchyme. By contrast, it has been suggested that anamniotes might generate derivatives of both classes at all axial levels, with trunk neural crest generating fin osteoblasts, scale mineral-forming cells and connective tissue cells; however, this has not been fully tested. The cause and evolutionary significance of this cranial/trunk dichotomy, and its absence in anamniotes, are debated. Recent experiments have disputed the contribution of fish trunk neural crest to fin osteoblasts and scale mineral-forming cells. This prompted us to test the contribution of anamniote trunk neural crest to fin connective tissue cells. Using genetics-based lineage tracing in zebrafish, we find that these fin mesenchyme cells derive entirely from the mesoderm and that neural crest makes no contribution. Furthermore, contrary to previous suggestions, larval fin mesenchyme cells do not generate the skeletogenic cells of the adult fin, but persist to form fibroblasts associated with adult fin rays. Our data demonstrate that zebrafish trunk neural crest does not generate ectomesenchymal derivatives and challenge long-held ideas about trunk neural crest fate. These findings have important implications for the ontogeny and evolution of the neural crest.

Zic1 and zic4 expression in the somite regulates dorsalization of the fish trunk structures

zic1 and zic4 expression in the somite regulates dorsalization of the fish trunk structures

Distance Determination via the Lateral Line in the Mottled Sculpin

We determined the ability of blinded mottled sculpin (Cottus bairdi) to determine the distance from the trunk of a vertically oscillating sphere. Sphere distance from the trunk and oscillation amplitude was varied randomly. Fish were trained to respond to a one-cycle oscillation (50 Hz) by attempting to touch the sphere with the mouth in one movement from the fish's initial position. Each of the four fish was tested with both left and right trunk canals intact. Afterward, one canal was blocked with a nylon thread and the other left intact. Precision of distance determination was measured as the correlation coefficient of the distance from the sphere to the fish's trunk before stimulus onset and the response distance. Fish were significantly better at distance determination with intact canals than on the side with the canal blocked (P < 0.001).

Zebrafish Hoxa and Evx-2 genes: cloning, developmental expression and implications for the functional evolution of posterior Hox genes

Vertebrate Hox genes are required for the establishment of regional identities along body axes. This gene family is strongly conserved among vertebrates, even in bony fish which display less complex ranges of axial morphologies. We have analysed the structural organization and expression of Abd-B related zebrafish HoxA cluster genes ( Hoxa-9, Hoxa-10, Hoxa-11 and Hoxa-13) as well as of Evx-2, a gene closely linked to the HoxD complex. We show that the genomic organization of Hoxa genes in fish resembles that of tetrapods albeit intergenic distances are shorter. During development of the fish trunk, Hoxa genes are coordinately expressed, whereas in pectoral fins, they display transcript domains similar to those observed in developing tetrapod limbs. Likewise, the Evx-2 gene seems to respond to both Hox- and Evx-types of regulation. During fin development, this latter gene is expressed as the neighbouring Hox genes, in contrast to its expression in the central nervous system which does not comply with colinearity and extends up to anterior parts of the brain. These results are discussed in the context of the functional evolution of Hoxa versus Hoxd genes and their different roles in building up paired appendages.

Histopathology of kidney of Channa punctatus exposed to chronic nonlethal level of Elsan, mercury, and ammonia

Histopathological changes in the head and trunk kidneys of Channa punctatus induced by chronic nonlethal levels of Elsan (211 ppb), mercuric chloride (16.7 ppb), and aqueous ammonia (15.64 ppm) were studied on 7, 28, 63, and 90 days of exposure. The pathology of the head kidney was characterized by degeneration and dispersion of interrenal and chromaffin tissue and necrosis in the haemopoietic elements. Kidney lesions were observed throughout the entire experimental period in fish exposed to Elsan and mercuric chloride. In contrast, the lesion induced by exposure to aqueous ammonia began to heal during the first phase of treatment. Marked abnormalities in trunk kidney histology were also found. Renal lesions consisted of minimal to mild multifocal, acute tubular epithelial degeneration, karyolysis, and dilation or shrinkage of Bowman's capsule and glomerulus. Elsan treatment resulted in a highly significant decrease in the dimension of Bowman's capsule and glomerulus at all days of sampling, except on Day 28. The response of the fish trunk kidney tissue to mercuric chloride was similar to that observed with Elsan exposure in terms of the alteration in the mean dimensions of Bowman's capsule and glomerulus. The response to ammonia was significant reduction in the size of Bowman's capsule and glomerulus throughout the experimental period except at Day 28. Little dilation of Bowman's capsule and a significant dilation of glomerulus were found at Day 28 of ammonia exposure. This study demonstrated that a chronic nonlethal exposure to Elsan, mercuric chloride affect both endocrine and excretory parts of the kidney while ammonia specifically damages the excretory part of the kidney of C. punctatus.

Evaluation of bis(tri- n-butyltin)oxide (TBTO) neurotoxicity in rainbow trout ( Oncorhynchus mykiss). I. Behaviour, weight increase, and tin content

Three-week old rainbow trout hatchlings ( Oncorhynchus mykiss) were exposed to 0.5 μg/l or 2.0 μg/l bis(tri- n-butyltin)oxide (TBTO) for 21 days in a flowthrough system. After 7 and 21 days, weight increase was determined, swimming behaviour was recorded and samples were taken to determine tin content by atomic absorption spectrophotometry. Bioaccumulation of TBTO, reduced weight increase and accumulation of tin in both fish trunk and head were dose-dependent. Fish concentrated TBTO from the surrounding water by a factor of up to 900. After 21 days, increase in weight was drastically reduced in fish treated with 2 μg/l TBTO over control fish. In comparison to control fish, TBTO-treated fish swam greater distances for longer time and with greater speed. Whereas control fish showed conspicuous orientation along the wall of the circular aquaria, swimming tracks of TBTO-exposed rainbow trout do not show this orientation.

Skin ulcer disease of flounder Platichthys liesus in the northern Baltic Sea

Skln ulcer disease of flounder Platichthys flesus (L.) was investigated a t 7 sampling sites in the northern Baltic Sea, SW Finland, dunng 1987-1989. Disease prevalences ranged from 1 8 to 11.1 % in different areas. A significant correlation was established between sex, fish length and disease prevalence. h4ales were more affected (10 7%) than females (3.1%) and larger flsh showed higher disease prevalences than smaller ones The length of the ulcerated'flounders vaned between 19 and 4 2 cm. The ulcers were not randomly distributed on the fish trunk They occurred mainly on the b l ~ n d side of the males and on the eye side of the females. Ulcers on males tended to occur close to the lateral hne; on females, the ulcers were scattered over the whole trunk. Bacterial examination of diseased specimens resulted in the isolation of a cytochrome oxidase-negative, atypical Aeromonas salrnonicida, primarily from the ulcers.

Fibers innervating different parts of the lateral line system of an Antarctic notothenioid, Trematomus bernacchii, have similar frequency responses, despite large variation in the peripheral morphology.

Regional differences in the architecture and size of lateral line canals and neuromasts were measured in an Antarctic fish, Trematomus bernacchii, and the data were used in models of canal and cupular mechanics to predict the frequency response of these two peripheral structures. These modeled predictions were then compared to frequency response functions measured with single unit recording techniques from anterior and posterior lateral line fibers innervating different canals on the head and trunk of fish of various sizes. Despite large variations in the peripheral morphology of head and trunk canals in fish of different sizes, lateral line fibers were relatively homogeneous in their frequency response properties. In response to stimuli of equal pk-pk acceleration levels, all canal neuromast fibers responded with equal and maximum responsiveness in the 10-45 Hz range, after which responsiveness fell off at about 18 dB/octave. Whereas the biomechanical models of cupular and canal responsiveness predicted the region of equal and maximum responsiveness in the 10-45 Hz range, they did not predict the high frequency cutoff nor the slope. Rather, these models predicted responsiveness out to at least 540 Hz, and a high frequency slope of 12 dB/octave. In terms of the frequency response of peripheral fibers, we conclude that (1) there can be considerable morphological variability, with little consequence for function, as long as some minimum standards for maintaining constant acceleration responsiveness in the 10-45 Hz range are met, and (2) there must be additional filters between the cupula and primary afferent fibers.

HISTOCHEMICAL DEMONSTRATION OF MUSCLE LIPASE.

A method which is an advance over the existing methods for the histochemical demonstration of lipase activity in muscle, using "Tween 85' as substrate and alizarin red S as stain for the calcium soap formed, is described. Lipase has been localized in the mitochondria of the fish trunk and pigeon breast muscles.

ELECTRICAL RESPONSES FROM THE LATERAL-LINE NERVES OF CATFISH. I

1. Records of impulses from the lateral-line nerves of catfish show that the lateral-line organs are in a state of continuous activity, producing a massive discharge of impulses. 2. The discharge may be increased during the direct application of pressure on the skin over the lateral-line canal, by ripples in the water, by irregular currents of water, and by movements of the fish's trunk. 3. The asynchronously discharging lateral-line organs respond to vibratory stimuli from tuning-forks by getting into phase with each other and by beating synchronously at frequencies ranging from 20 to 70 per second. The frequency of beating for a given preparation is independent of the frequency of the tuning-fork for the fork frequencies of 100, 200, and 250 double vibrations which were used. 4. The continuous discharge of the lateral-line system is markedly changed by alteration of temperature. The frequency declines on lowering the temperature and rises on increasing it. Spinal and facial nerves in the catfish fail to yield nerve impulses in response to changes of the skin temperature between 0 degrees and 28 degrees C., although the intact animal is known to be sensitive to temperature differences. 5. The action of the lateral-line system of Ameiurus in inhibiting responses initiated through the skin and ears (Parker and Van Heusen, 1917) is discussed in the light of the present experiments.