Fin Tissue Research Articles

Verifying the relationship between δ13C isotope profile variables and individual feed conversion ratio in large rainbow trout (Oncorhynchus mykiss)

The study aimed to verify the relationship found between individual indicator traits, derived from an isotope ratio of 13C/12C in various tissues (muscle, liver, and adipose), and individual feed efficiency. A 50-day experiment was performed with 46 rainbow trout (Oncorhynchus mykiss) kept in individual tanks after a dietary switch, using an experimental feed based on maize gluten with an enhanced level of 13C, during the grow-out phase. Individual growth, feed intake, and isotope profiles (muscle, liver, fin, and adipose tissue) were recorded. Using a Lasso-regression model, feed efficiency was found to be positively associated with visceral adipose tissue synthesis, meaning that feed efficiency was worsened when visceral adipose synthesis increased. The results indicated that deposition efficiency through lipid metabolism (δ13C in adipose tissue) was the most important determinant of feed efficiency of rainbow trout at this life stage. The results suggest that phenotyping of lipid deposition efficiency is possible through the use of feed ingredients with a natural abundance of stable isotopes.

Cytological and Molecular Approaches for Ploidy Determination: Results from a Wild Walleye Population

AbstractWith the increasing use of triploid fish for sport fisheries management, biologists, researchers, and managers working in field environments need practical methods to determine ploidy. Cytological methods (e.g., flow cytometry, Coulter counter) using erythrocytes are the most common for ploidy determination in fishes. However, collecting and storing erythrocytes can be logistically challenging during field work, and donor fish need to be alive or freshly killed. With rapid advances in molecular genetics, biologists, researchers, and managers may be unaware of molecular approaches for ploidy determination that could alleviate the difficulties associated with cytological methods and allow ploidy determination from archived samples (e.g., fin clips, scales, otoliths). In this study, we analyzed the agreement between molecular‐based (using fin tissue) and Coulter counter‐based (using blood) ploidy determinations for Walleyes Stizostedion vitreum—the first assessment of concordance between molecular and cytological methods for determining ploidy in the family Percidae. We found that agreement between these two methods was >98%. The high degree of agreement and greater ease of collecting and storing samples for molecular‐based approaches relative to the traditional cytological ones support the utility of molecular methods for ploidy determination.

Quantitative Method Development to Determine Feed Consumption Using a Dye

Although there are many methods to determine ingestion and absorption of aquafeeds, none exist that are simple, cost-effective, and quantitative and that can mark fish with a long-lasting, visible indicator. In addition to aquafeed development, selective baits are needed that can be used for aquatic invasive species removal efforts, including for Grass Carp Ctenopharyngodon idella. Bait incorporated with a pesticide would allow for selective removal of targeted species. A method to quickly assess multiple bait formulations was developed to expediate development for invasive species management. Incorporation of Sudan Black B (SBB) in aquafeeds at concentrations greater than 75 and 120 mg SBB/kg fish resulted in pigmented external soft tissues of Largemouth Bass Micropterus salmoides and Rainbow Trout Oncorhynchus mykiss, respectively, 24 h after consumption. Visual confirmation of consumption was detectable in the gastrointestinal tract at all concentrations tested (≥10 mg SBB/kg) and quantifiable by absorbance measured at 601 nm from extracted SBB in tissues at concentrations less than those required for visual pigmentation. Although SBB was detectable in multiple tissues, fin and mandible tissues yielded the greatest accuracy in estimating consumption from extracted SBB. Compared with other tissues tested, liver tissue accumulated the highest level of SBB but had the greatest variability, while muscle tissue accumulated little detectable SBB. We used the SBB analytical method to compare consumption of six novel baits that were in the initial developmental stages to produce a palatable bait formulation designed to attract Grass Carp for management control. Overwhelming preference of a rapeseed bait formulation was confirmed using SBB as a tracer of consumption in the laboratory; however, use of SBB under natural conditions may be valuable for answering additional questions. Baits incorporated with SBB allowed for the rapid, simultaneous assessment of multiple formulations and could allow for future refinement of management baits, with results available as quickly as 24–72 h after application.

Trophic niche of Australian cownose rays (Rhinoptera neglecta) and whitespotted eagle rays (Aetobatus ocellatus) along the east coast of Australia.

Australian cownose rays (Rhinoptera neglecta) and whitespotted eagle rays (Aetobatus ocellatus) are large myliobatiform rays that co‐occur off temperate eastern Australia. Here, we performed stable‐isotope analyses (δ13C, δ15N and δ34S) on fin clips of both species to gain insights into their trophic interactions and isotopic niches, and assess the effect of preservation (ethanol‐stored versus frozen) on isotopic values of fin‐clip tissue of R. neglecta. Linear mixed models identified species as the main factor contributing to variation among δ15N and δ34S values, and disc width for δ13C. Bayesian ecological niche modelling indicated a 57.4% to 74.5% overlap of trophic niches, with the niche of R. neglecta being smaller and more constrained. Because values of δ13C were similar between species, variation in isotopic niches were due to differences in δ15N and δ34S values. Linear mixed models failed to detect differences in isotopic values of ethanol‐stored and frozen fin tissue of R. neglecta. This study provides the first examination of the trophic ecology of R. neglecta and the comparison of isotopic niche with A. ocellatus, which will facilitate future research into the trophic interactions of these species and aid better resource management.

Understanding the complexity of epimorphic regeneration in zebrafish caudal fin tissue: A transcriptomic and proteomic approach.

The complex epimorphic regeneration of zebrafish caudal fin tissue is hasty and absolute. This study was executed to understand the role of various genes/proteins involved in the regeneration of zebrafish caudal fin tissue through differential transcriptomics and proteomics analysis. Based on our study 1408 genes and 661 proteins were found differentially regulated in the regenerating caudal fin tissue for having at least 1-log fold change. Interleukin, Solute carrier, Protein arginine methyltransferase, Homeobox, Neurotransmitter and several novel genes were found to be associated with regeneration for its differential regulation during the mechanism. Based on the network and pathway analysis the differentially regulated genes and proteins were found allied with activation of cell proliferation, cell viability, cell survival & cell movement and inactivation of organismal death, morbidity, necrosis, death of embryo & cell death. This study has mapped a detailed insight of the genes/proteins expression associated with the epimorphic regeneration more profoundly.

Non-lethal sampling for the stable isotope analysis of the critically endangered European eel Anguilla anguilla: how fin and mucus compare to dorsal muscle.

Ecological studies on the critically endangered European eel Anguilla anguilla often incorporate stable isotope analysis that typically uses dorsal muscle sampled from euthanised eels. To minimise the lethal sampling of imperilled populations, fin tissue and/or epidermal mucus can provide non‐lethal alternatives to muscle. The results here indicate that δ13C and δ15N values of both eel fin and mucus are not significantly different from those of muscle and can be applied directly in comparative SI studies.

Establishment and characterization of a fin cell line from yellowfin sea bream (Acanthopagrus latus) and its application to fish virology and toxicology

Fish cell lines are ideal tools in vitro for virology and toxicology. Yellowfin sea bream ( Acanthopagrus latus ) is an economically important marine fish suffering from virus infections and is also a reliable indicator in toxicological studies. However, no continuous cell line from A. latus has been developed. Here, a new cell line (ALF) derived from the fin tissue of A. latus was established and identified. Up to now, the cell line has been subcultured for more than 50 times in Dulbecco's modified Eagle's medium. ALF cells could grow well at a range of temperature from 20 to 28 °C and had a maximum growth rate at 28 °C, and grow fastest in DMEM with 20% FBS concentration (in the range of 10% to 20%). Partial sequence amplification and sequencing of cytochrome B gene indicated that the cell line was originated from A. latus . The chromosome number of ALF cell was 48. ALF was susceptible to red-spotted grouper nervous necrosis virus (RGNNV), as suggested by the typical cytopathic effects and the amplification of RGNNV RNA-dependent RNA polymerase gene. Virus replication in ALF cells was confirmed by qRT-PCR, virus titer assay, western blot and transmission electron microscopy assays. Furthermore, the expression of four immune-related genes, TRAF3 , NF-κB1 , STAT1 and STAT2 , was varied changed in ALF cells upon RGNNV infection, indicating the induction of cellular antiviral response. In addition, p,p′-DDT was cytotoxic to ALF cells and induced cell apoptosis as evidenced by the results of annexin V-FITC/PI double staining assay, DNA fragmentation assay and the differential expression of apoptosis-related genes. Moreover, p,p'-DDT exposure increased the sensitivity of ALF cells to RGNNV via inhibiting the antiviral response in ALF cells. In conclusion, the ALF cell line will be a good in vitro platform for fish virology and toxicology studies. • A cell line (ALF) derived from the fin tissue of yellowfin sea bream ( Acanthopagrus latus ) was established and identified. • ALF is susceptible to red-spotted grouper nervous necrosis virus (RGNNV). • p,p′-DDT was cytotoxic to ALF cells and induced apoptosis in ALF cells. • p,p′-DDT increased the susceptibility of ALF cells to RGNNV via inhibiting the antiviral response in ALF cells.

Establishment and characterization of a cell line from ictalurid catfish

AbstractThe catfish industry is integral to the economy of the southern United States contributing >70% of the total U. S. finfish production. Intensive catfish production systems are more vulnerable to infectious disease outbreaks resulting in significant economic losses. Viruses are a major concern especially in the hatchery and nursery phases of catfish rearing. These infectious agents require host cell machineries to replicate. The ability to propagate fish viruses in vitro using cell cultures is imperative in advancing virus research and facilitating disease management strategies. Several viruses show host‐ or even tissue‐specificity. Scarcity of host‐specific fish cell lines forces researchers to rely on general cell lines that might not be conducive for the replication of some viruses, thus hindering their isolation, identification, and characterization. The ictalurid cell line (channel catfish ovary [CCO‐ATCC® CRL‐2772]) previously available from cell repository (ATCC) has recently been reported as cross‐contaminated by brown bullhead (BB) cells. Lack of host‐specific cell cultures and contamination issues necessitated initiation of cell cultures from the fin tissues of hybrid catfish (♀ channel catfish × ♂ blue catfish). A combination approach involving tissue explantation and enzymatic digestion methods were used to develop catfish fin cell cultures. These cultures were passaged over 100 times and transitioned into an established cell line. The hybrid catfish fin (HCF) cell line was characterized, growth conditions optimized, species of origin molecularly authenticated, and the susceptibility to fish viruses evaluated. This catfish cell line could serve as an efficient tool for virus studies, antiviral agent screening, and vaccine development benefitting catfish aquaculture.

The Effect of Fluence on Neutrophil Kinetics in Zebrafish Wounds Using Real-time In Vivo Imaging

Background: Neutrophils participate in a cooperative defense strategy with macrophages following tissue injury. Application of low dose electromagnetic radiation via 635 nm wavelength can enhance macrophage recruitment to the wound, decrease tissue levels of ROS and speed healing. The impact of this wavelength on neutrophil activity in vivo is not well-described. Given that wound healing can be enhanced if collateral damage by neutrophils within the wound is decreased, we investigated how neutrophil kinetics changed during these accelerated reparative responses. Methods: Zebrafish, transgenic for the fluorescent neutrophil marker, mpx-dendra2, underwent defined fin tissue injury, and were randomized to one of two laser treatment groups, 3 J/cm2 (n=57), or 18 J/cm2 (n=69) or to the control group, 0 J/cm2 (n=164). Electromagnetic wave exposures were administered by a 635-nm continuous 5mW He:Ne laser with recipients randomized by dose delivered. Fish were three-dimensionally time-lapse imaged 30-120 minutes post injury (mpi) and wound healing documented at 24 hours post-injury. Individual neutrophil movement was tracked according to distance from wound center. Results: The lower treatment fluence, 3 J/cm2, significantly decreased neutrophil migration speed into the wound, increased reverse migration, and promoted stasis outside the adjacent wound area when compared to control and higher energy doses. The 3 J/cm2 treatment groups also exhibited more rapid wound closure when compared to control or higher fluence. Conclusions: Unlike our previous work in macrophages in which low fluence treatment enhanced the speed of forward directed migration into the wound, the response of neutrophils was decreased speed into the wound, increased reverse migration, and stasis outside the areas of the wound edges. These findings advance the notion that low fluence treatments reduce neutrophil inflammatory responses within the wound by their reduced presence within the wound. Reduced neutrophil-mediated collateral damage may work in concert with enhanced macrophage wound activity to promote faster wound healing.

Conservation of freshwater eels in food‐web studies: Non‐lethal stable isotope analyses substitute fin for muscle tissue with lipid correction

AbstractAquatic food‐web studies involving fish and using stable isotope analysis typically sample fish white muscle, which generally requires the fish to be euthanised. Alternatively, fin tissue can be sampled non‐lethally, avoiding the need to euthanise an animal to obtain what is usually a relatively small tissue sample. We set out to develop equations for converting δ13C and δ15N values from derived non‐lethally sampled fin tissue to equivalent white muscle tissue, for use in food‐web studies. We explored δ13C and δ15N values of paired fin‐clips and white muscle from two species of anguillid fishes, the endemic longfin eel (Anguilla dieffenbachii), and the Australasian shortfin eel (A. australis), sourced from multiple studies spread throughout New Zealand. We also examined the effect of lipid extraction on δ13C and δ15N, which reduced variability of δ13C when compared to untreated samples. We were also able to estimate δ13C values of equivalent lipid‐extracted muscle samples directly from untreated fin. For δ15N, paired untreated fin and muscle values were not statistically different so fin δ15N can be used as a direct estimate of muscle δ15N. Solvent lipid extraction with a methanol–chloroform mixture, however, altered δ15N values and increased variability, so should be avoided. We present equations to estimate lipid‐corrected δ13C values of muscle tissue for use in stable isotope studies of freshwater anguillids, avoiding euthanasia. Our results demonstrate that δ13C and δ15N values can be accurately derived from non‐lethally obtained fin clips, reducing unnecessary mortality in fish species of conservation concern.

Nonlethal Fin Clip Model Validation for Stable Isotope Analysis of Spotted Gar and Alligator Gar

AbstractStable isotope analysis (SIA) can be a powerful tool for investigating trophic ecology and energy fluxes through an ecosystem. In fish, muscle tissue is generally preferred for SIA due to its intermediate turnover rate, even though sampling muscle is often lethal. Here, we evaluated the feasibility of a fin clip model using fin tissue as a nonlethal alternative to using muscle tissue for SIA (nitrogen, δ15N and carbon, δ13C) in Spotted Gar Lepisosteus oculatus and Alligator Gar Atractosteus spatula. We also investigated the effects of locality, age, and size of Spotted Gars on the robustness of the fin clip model. Muscle tissue plugs and fin tissue clips were collected from Spotted Gars (n = 104) and Alligator Gars (n = 16) at four localities in southeastern Louisiana in 2019. Both Spotted Gars and Alligator Gars showed strong positive Pearson’s correlations in δ15N and δ13C between the fin and muscle tissues, and a linear regression analysis confirmed that the correlations were significant (Spotted Gar; δ15N: R2 = 0.88; δ13C: R2 = 0.95, P < 0.001; Alligator Gar; δ15N: R2 = 0.74; δ13C: R2 = 0.94, P < 0.001). The fin clip model for Spotted Gar was affected by locality but not by size or age. Overall, our results suggest that fin tissue can be used as a nonlethal surrogate for muscle tissue for SIA for both Spotted Gars and Alligator Gars.

Carotenoid coloration and coloration-linked gene expression in red tilapia (Oreochromis sp.) tissues

BackgroundProduction, marketability and consumer preference of red tilapia often depends upon the intensity of coloration. Hence, new approaches to develop coloration are now geared to improve market acceptability and profit. This study evaluated the effects of carotenoid-rich diets on the phenotypic coloration, carotenoid level, weight gain and expression of coloration-linked genes in skin, fin and muscle tissues. Carotenoids were extracted from dried Daucus carota peel, Ipomoea aquatica leaves, and Moringa oleifera leaves. Eighty (80) size-14 fish were fed with carotenoid-rich treatments twice a day for 120 days. The phenotypic effect of the carotenoid extracts was measured through a color chart. Skin carotenoid level was measured through UV-vis spectrophotometer. csf1ra, Bcdo2 and StAR expression analysis was done using qRT-PCR.ResultsTreatments with carotenoid extracts yielded higher overall scores on phenotypic coloration and tissue carotenoid levels. Differential expression of carotenoid-linked genes such as the elevated expression in csf1ra and lower expression in Bcdo2b following supplementation of the enhanced diet supports the phenotypic redness and increased carotenoid values in red tilapia fed with D. carota peel and I. aquatica leaves.ConclusionsOverall improvement in the redness of the tilapia was achieved through the supplementation of carotenoid-rich diet derived from readily available plants. Differential expression of coloration-linked genes supports the increase in the intensity of phenotypic coloration and level of carotenoids in the tissues. The study emphasizes the importance of carotenoids in the commercial tilapia industry and highlights the potential of the plant extracts for integration and development of feeds for color enhancement in red tilapia.

Comparison of Length-at-Date Criteria and Genetic Run Assignments for Juvenile Chinook Salmon Caught at Sacramento and Chipps Island in the Sacramento–San Joaquin Delta of California

There are four distinct runs of Chinook Salmon (Oncorhynchus tshawytscha) in the Central Valley, named after their primary adult return times: fall, late-fall, winter, and spring run. Estimating the run-specific composition of juveniles entering and leaving the Sacramento–San Joaquin Delta is crucial for assessing population status and processes that affect juvenile survival through the Delta. Historically, the run of juvenile Chinook Salmon captured in the field has been determined using a length-at-date criteria (LDC); however, LDC run assignments may be inaccurate if there is high overlap in the run-specific timing and size of juveniles entering and leaving the Delta. In this study, we use genetic run assignments to assess the accuracy of LDC at two trawl locations in the Sacramento River (Delta entry) and at Chipps Island (Delta exit). Fin tissues were collected from approximately 7,500 juvenile Chinook Salmon captured in trawl samples between 2007 and 2011. Tissues were analyzed using 21 microsatellites to determine genetic run assignments for individuals, which we compared with LDC run assignments. Across years, there was extensive overlap among the distributions of run-specific fork lengths of genetically identified juveniles, indicating that run compositions based on LDC assignments would tend to underestimate fall-run and especially late-fall-run compositions at both trawl locations, and greatly overestimate spring-run compositions (both locations) and winter-run compositions (Chipps Island). We therefore strongly support ongoing efforts to include tissue sampling and genetic run identification of juvenile Chinook Salmon at key monitoring locations in the Sacramento–San Joaquin River system.

Sirt1 promotes tissue regeneration in zebrafish through regulating the mitochondrial unfolded protein response

SummaryThe mitochondrial unfolded protein response (UPRmt) is an organellar stress signaling pathway that functions to detect and restore disruption of mitochondrial proteostasis. The UPRmt is involved in a wide range of physiological and disease conditions, including aging, stem cell maintenance, innate immunity, neurodegeneration, and cancer. Here we report that the UPRmt is integral to zebrafish fin regeneration. Taking advantage of a novel zebrafish UPRmt reporter, we observed that UPRmt activation occurs in regenerating fin tissue shortly after injury. Through chemical and genetic approaches, we discovered that the Sirt1-UPRmt pathway, best known for its role in promoting lifespan extension, is crucial for fin regeneration. The metabolism of NAD+ is an important contributor to Sirt1 activity in this context. We propose that Sirt1 activation induces mitochondrial biogenesis in injured fin tissue, which leads to UPRmt activation and promotes tissue regeneration.

LAMP for the rapid diagnosis of iridovirus in aquaculture

Iridoviruses are DNA virus and have caused huge economic losses in the aquaculture industry. The aim of this study was to establish a colorimetric loop-mediated isothermal amplification (LAMP) protocol for the on-site detection of Singapore grouper iridovirus (SGIV). The SGIV-VP61 gene was chosen as the target gene to develop a colorimetric LAMP assay. The optimized condition of the colorimetric LAMP assay was incubation at 63 °C for 1 h. Samples infected with SGIV could be detected with the color change from yellow into pink. The sensitivity of the developed assay is 5.66 copies/μL of the viral DNA template. This sensitivity was about 1000 times higher than that of conventional PCR while it was slightly lower than the one-step semi-nested PCR assay. A total of 60 DNA samples extracted from the fin tissue of the SGIV-infected Asian seabass were examined for SGIV by colorimetric LAMP, semi-nested PCR and conventional PCR. The results of the colorimetric LAMP assay showed 94.87 % agreement with the semi-nested PCR. In addition, the DNA extraction method using NaOH showed a better performance in the colorimetric LAMP assay. Taken together, the colorimetric LAMP established was a sensitive, rapid and specific method for the detection of SGIV. SGIV was not detected in samples randomly taken from a genetically improved line of the Asian seabass. However, some seabass obtained from the local markets were found to contain SGIV. Thus, the LAMP assay has the potential application in the diagnosis of iridovirus diseases in the aquaculture industry.

The presence of kelp Lessonia trabeculata drives isotopic niche segregation of redspotted catshark Schroederichthys chilensis

Kelp forests are associated with high biodiversity as they provide habitat and food source for many species. Redspotted catshark Schroederichthys chilensis is a coastal shark species associated with kelp forests of southern South America dominated by Lessonia trabeculata. Despite its common occurrence redspotted catshark the knowledge on its trophic ecology is rudimentary. This study aimed to assess the effects of presence/absence of kelp L. trabeculata on the isotopic niche of redspotted catshark through comparison of δ13C and δ15N in its blood and fin tissues (non-lethal samples). We found that males were characterized by higher trophic position and enriched carbon sources compared to females in locations where kelp was present. In contrast, males and females were characterized by similar isotopic niche in absence of kelp. These differences are most probably an effect of higher prey diversity associated with microhabitats generated by kelp forests that allow sexual segregation of isotopic niche. Therefore, extensive kelp harvest may cause significant effects in isotopic niche and nutritional status of adult redspotted catshark and may negatively affect its populations.

Evaluation of muscle lipid extraction and non‐lethal fin tissue use for carbon, nitrogen, and sulfur isotope analyses in adult salmonids

RationaleChemical lipid extraction or using alternative tissues such as fish fin as opposed to muscle may alter isotopic ratios and influence interpretations of δ13C, δ15N, and previously unassessed δ34S values in stable isotope analyses (SIA). Our objectives were to determine if lipid extraction alters these isotope ratios in muscle, if lipid normalization models can be used for lipid‐rich salmonids, and if fin isotope ratios are comparable with those of muscle in adult salmonids.MethodsIn six adult salmonid species (n = 106) collected from Lake Ontario, we compared three isotope ratios in lipid‐extracted (LE) muscle with bulk muscle, and LE muscle with fin tissue, with paired t‐tests and linear regressions. We compared differences between δ13C values in LE and bulk muscle with predicted values from lipid normalization models and the log‐linear model of best fit and determined model efficiency.ResultsThe δ15N values in LE muscle increased (<1‰) relative to bulk muscle for most salmonids, with relationships nearing 1:1. There were either no differences or strong 1:1 relationships in δ34S values between species‐specific bulk and LE muscle. One lipid normalization model had greater model efficiency (97%) than the model of best fit (94%). Fin had higher δ13C values than LE muscle while δ15N trends varied (<1‰); however, both isotope ratios had either no or weak linear relationships with fin and LE muscle within species. The δ34S values in fin were similar to those in LE muscle and had strong 1:1 relationships across species.ConclusionsWe recommend using the lipid normalization model to adjust for δ13C values in lipid‐rich muscle (C:N >3.4). LE muscle could be used without δ15N or δ34S adjustments, but the minimal increase in δ15N values may affect SIA interpretation. With high unexplained variability among adult species in fin‐muscle δ13C and δ15N relationships, species‐specific fin‐muscle adjustments are warranted. No fin‐muscle tissue adjustment would be required for δ34S values.

Lrp5 mutant and crispant zebrafish faithfully model human osteoporosis, establishing the zebrafish as a platform for CRISPR-based functional screening of osteoporosis candidate genes

Genomewide association studies (GWAS) have improved our understanding of the genetic architecture of common complex diseases such as osteoporosis. Nevertheless, to attribute functional skeletal contributions of candidate genes to osteoporosis-related traits, there is a need for efficient and cost-effective in vivo functional testing. This can be achieved through CRISPR-based reverse genetic screens, where phenotyping is traditionally performed in stable germline knockout (KO) mutants. Recently it was shown that first-generation (F0) mosaic mutant zebrafish (so-called crispants) recapitulate the phenotype of germline KOs. To demonstrate feasibility of functional validation of osteoporosis candidate genes through crispant screening, we compared a crispant to a stable KO zebrafish model for the lrp5 gene. In humans, recessive loss-of-function mutations in LRP5, a co-receptor in the Wnt signaling pathway, cause osteoporosis-pseudoglioma syndrome. In addition, several GWAS studies identified LRP5 as a major risk locus for osteoporosis-related phenotypes. In this study, we showed that early stage lrp5 KO larvae display decreased notochord mineralization and malformations of the head cartilage. Quantitative micro-computed tomography (micro-CT) scanning and mass-spectrometry element analysis of the adult skeleton revealed decreased vertebral bone volume and bone mineralization, hallmark features of osteoporosis. Furthermore, regenerating fin tissue displayed reduced Wnt signaling activity in lrp5 KO adults. We next compared lrp5 mutants with crispants. Next-generation sequencing analysis of adult crispant tissue revealed a mean out-of-frame mutation rate of 76%, resulting in strongly reduced levels of Lrp5 protein. These crispants generally showed a milder but nonetheless highly comparable skeletal phenotype and a similarly reduced Wnt pathway response compared with lrp5 KO mutants. In conclusion, we show through faithful modeling of LRP5-related primary osteoporosis that crispant screening in zebrafish is a promising approach for rapid functional screening of osteoporosis candidate genes. (C) 2021 American Society for Bone and Mineral Research. (C) 2021 The Authors. Journal of Bone and Mineral Research published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research (ASBMR).

Dual‐isotope isoscapes for predicting the scale of fish movements in lowland rivers

AbstractAssessments of patterns of animal movements are important for understanding their spatial ecology. Geostatistical models of stable isotope (SI) landscapes (isoscapes) provide a complementary tool to telemetry for assessing and predicting animal movements, but are rarely applied to riverine species. Often single‐isotope gradients in freshwater environments are insufficiently variable to provide high isoscape resolution at relatively fine spatial scales. This is potentially overcome using dual‐isotope assignment procedures, and thus, the aim here was to apply single (δ13C) and dual (δ13C and δ15N) isoscapes to assigning riverine fish to origin and predicting their movements. Using the River Bure, England, as the study system, the foraging locations of a small‐bodied lowland river fish (roach Rutilus rutilus) of low vagility were predicted using their SI data and those of a common prey item (amphipods). These foraging locations were then compared to their capture locations, with the distance between these being their predicted displacement distance. The results indicated significant enrichment of δ13C and δ15N with distance downstream in roach fin tissue and amphipods; roach bivariate isotopic niches were spatially variable, with no niche overlap between upstream and downstream river reaches. Furthermore, the dual‐isoscape assignment procedure resulted in the lowest predicted displacement distances for roach, therefore enhancing model performance. The dual‐isoscape approach was then applied to determining the predicted displacement distance of individual common bream Abramis brama, a larger, more vagile species, with these data then compared against the subsequent spatial extent of their movements recorded by acoustic telemetry. When using a high probability density threshold for isotope assignment, the predicted displacement distance of common bream was a significant predictor of the spatial extent of their subsequent movements recorded by acoustic telemetry, although it was less able to predict the direction of displacement. This first probabilistic assignment to origin for riverine species using a dual‐isotope isoscape technique demonstrated that where the required spatial resolution of animal movements in freshwater is moderately broad (5–10 km), dual‐isotope isoscapes can provide a reliable alternative or complementary method to telemetry.

Dioctyl Sodium Sulfosuccinate as a Potential Endocrine Disruptor of Thyroid Hormone Activity in American bullfrog, Rana (Lithobates) catesbeiana, Tadpoles.

The thyroid hormones, thyroxine (T4) and triiodothyronine (T3), are required to regulate complex developmental processes in vertebrates and are highly sensitive to endocrine-disrupting compounds. Previous studies demonstrate that dioctyl sodium sulfosuccinate (DOSS), a common constituent of pharmaceuticals, cosmetics, and food products, disrupts canonical signaling of adipocyte differentiation by binding a nuclear hormone receptor in the same superfamily as thyroid hormone (TH) receptors. The present study was designed to determine whether DOSS is capable of disrupting TH signaling using the American bullfrog, Rana (Lithobates) catesbeiana-a cosmopolitan frog species that undergoes TH-dependent metamorphosis to transition from an aquatic tadpole to a terrestrial juvenile frog. Premetamorphic R. catesbeiana tadpoles were injected with 2pmol/g body weight T3 or 10pmol/g body weight T4 to induce precocious metamorphosis, then exposed for 48h to environmentally or clinically relevant DOSS concentrations (0.5, 5, and 50mg/L). Gene expression of three classical TH-responsive targets (thra, thrb, and thibz) was measured in tadpole liver and tail fin tissue through reverse transcription quantitative polymerase chain reaction (RT-qPCR). DOSS disrupted gene expression in liver and tail fin tissue at all three concentrations tested but the patterns of expression differed by tissue, gene transcript, and TH treatment status. To our knowledge, this is the first demonstration that DOSS can alter TH signaling. Further exploration into DOSS disruption of TH signaling is warranted, because exposure may affect other TH-dependent processes, such as salmon smoltification and perinatal human development.