Zebrafish最新文献

Brycon is a fish genus in the order Characiformes, distributed from southern Mexico to the La Plata River in Argentina. Several of its species, including Brycon nattereri, are threatened with extinction or considered vulnerable because they are highly sensitive to anthropogenic factors. The decline of these species may be related to the growth of agriculture and mining in the Brazilian Cerrado region, thus their recovery requires management plans. In this study, we use morphological, chromosomal, and genetic analysis to suggest that two distinct evolutionary units exist under the same denomination B. nattereri, indistinguishable by the descriptive morphological characters of the species until the present moment and show that the population of the São Francisco River is more diverse than that of the upper Paraná River basin. These results may help with future management and conservation programs of Brycon species in the Paraná and São Francisco river basins, two major Brazilian hydrographic basins.

Inducible gene expression systems are valuable tools for studying biological processes. We previously developed an optogenetic gene expression system called TAEL that is optimized for use in zebrafish. When illuminated with blue light, TAEL transcription factors dimerize and activate gene expression downstream of the TAEL-responsive C120 promoter. By using light as the inducing agent, the TAEL/C120 system overcomes limitations of traditional inducible expression systems by enabling fine spatial and temporal regulation of gene expression. In this study, we describe ongoing efforts to improve the TAEL/C120 system. We made modifications to both the TAEL transcriptional activator and the C120 regulatory element, collectively referred to as TAEL 2.0. We demonstrate that TAEL 2.0 consistently induces higher levels of reporter gene expression and at a faster rate, but with comparable background and toxicity as the original TAEL system. With these improvements, we were able to create functional stable transgenic lines to express the TAEL 2.0 transcription factor either ubiquitously or with a tissue-specific promoter. We demonstrate that the ubiquitous line in particular can be used to induce expression at late embryonic and larval stages, addressing a major deficiency of the original TAEL system. This improved optogenetic expression system will be a broadly useful resource for the zebrafish community.

Explants are three-dimensional tissue fragments maintained outside the organism. The goals of this article are to review the history of fish explant culture and discuss applications of this technique that may assist the modern zebrafish laboratory. Because most zebrafish workers do not have a background in tissue culture, the key variables of this method are deliberately explained in a general way. This is followed by a review of fish-specific explantation approaches, including presurgical husbandry, aseptic dissection technique, choice of media and additives, incubation conditions, viability assays, and imaging studies. Relevant articles since 1970 are organized in a table grouped by organ system. From these, I highlight several recent studies using explant culture to study physiological and embryological processes in teleosts, including circadian rhythms, hormonal regulation, and cardiac development.

Depression is a complex and disabling psychiatric disorder, which is expected to be a leading cause for disability by 2030. According to World Health Organization, about 350 million people are suffering with mental health disorders around the globe, especially depression. However, the mechanisms involved in stress-induced depression have not been fully elucidated. In this study, a stress-like state was pharmacologically induced in zebrafish using reserpine, a drug widely used to mediate depression in experimental animal models. Zebrafish received single intraperitoneal (i.p.) injections of 20, 40, and 80 mg/kg body weight reserpine doses and were subjected to open-field test at 2, 24, 48, 72, and 96 h after the treatment. Along with observed changes in behavior and measurement of cortisol levels, the fish were further examined for perturbations in their brain metabolites by ¹H nuclear magnetic resonance (NMR)-based metabolomics. We found a significant increase in freezing duration, whereas total distance travelled was decreased 24 h after single intraperitoneal injection of reserpine. Cortisol level was also found to be higher after 48 h of reserpine treatment. The ¹H NMR data showed that the levels of metabolites such as glutamate, glutamine, histamine, valine, leucine and histidine, lactate, l-fucose, betaine and γ-amino butyric acid (GABA), β-hydroxyisovalerate, and glutathione were significantly decreased in the reserpine-treated group. This study provided some insights into the molecular nature of stress that could contribute toward a better understanding of depression disorder.

The popularity of zebrafish in both basic biological and biomedical research has led to an increased need for understanding their behavior. Locomotor behavior is an important outcome of different factors, such as specific genotypes or external stimuli that influence the nervous and musculoskeletal system. Locomotion can be studied by forced swimming in a swim tunnel, a device capable of generating a laminar water flow at different speeds in a chamber where zebrafish can be placed. However, commercially available swim tunnels are relatively expensive and in-house built systems are mostly presented without clear building instructions or proper validation procedures. In this study, we developed an alternative, cheap (<250 euro), and user-friendly, but customizable benchtop swim tunnel, called the "Zebrafish exercise-tunnel" (ZE-Tunnel). Detailed step-by-step instructions on how to construct the tunnel components, including the frame, mechanical, and electric components are given. The ZE-Tunnel was reliably used to exercise fish for prolonged periods and its performance was successfully validated by replicating previously published experiments on critical speed testing in zebrafish. Finally, implementation of behavioral video analysis using freely available motion-tracking software showed differences in swimming dynamics in the Chihuahua skeletal zebrafish mutant.

Parkinson's disease (PD) is a chronic neurodegenerative disorder mainly attributed to the progressive loss of dopaminergic neurons in the substantia nigra, which leads to uncontrolled voluntary movements causing tremors, postural instability, joint stiffness, and speech and locomotion difficulties, among other symptoms. Previous studies have shown the participation of specific peptides in neurodegenerative diseases. In this context, the present work analyzed changes in the peptide profile in zebrafish brain induced to parkinsonian conditions with 6-hydroxydopamine, using isotopic labeling techniques plus mass spectrometry. These analyses allowed the relative quantitation and identification of 118 peptides. Of these, nine peptides showed significant changes, one peptide was increased and eight decreased. The most altered sequences were fragment of cytosolic and extracellular proteins related to lipid metabolism and dynamic cytoskeleton. These results open new perspectives of study about the function of peptides in PD.

Farlowella is the second richest genus in Loricariinae, broadly distributed in freshwater streams and rivers of South America. In this article, we aimed to expand on the cytogenetic and molecular data available for two allopatric populations of Farlowella hahni. Both populations had diploid chromosome number 58, but with karyotype differences, indicative of chromosomal rearrangements. C-banding showed large heterochromatic blocks at telomeric regions in acrocentric chromosomes in both populations. Fluorescence in situ hybridization (FISH) revealed a single 18S rDNA site in both populations and a single 5S rDNA site for individuals from lower Paraná River basin (native region) and multiple 5S rDNA sites for individuals from upper Paraná River basin (non-native region). Mitochondrial sequence analyses did not separate the two F. hahni populations. The cytogenetic and molecular data obtained are relevant in a preliminary study and suggested the existence of cryptic diversity and the hypothesis that at least two Farlowella lineages may coexist in the Paraná basin.

The Zebrafish Embryo Genotyper (ZEG) device provides a promising tool for genotyping live embryos. Although the gross morphology and survival of embryos after the use of ZEG are unaffected, the cellular and molecular effects of the ZEG protocol remain unknown. To address this, we have examined the integrity of specific tissues, and evaluated the expression of stress-responsive genes to determine the impact of the ZEG protocol. Our analyses reveal that although ZEG results in a low-level acute stress response, no long-lasting effects are evident, supporting its utilization for a variety of downstream assays.

Low and variable growth and survival rates (SR) of 6-10 days postfertilization zebrafish larvae are a problem. This problem seems to be linked to starter feed characteristics. This study is an attempt to find alternatives to address these requests. For this, larvae were fed fresh and lyophilized microalgae (Chlorella, Scenedesmus, and Haematococcus), egg yolk (YOLK), lyophilized Artemia nauplii (LAN), and a combination of them. The lowest SR was observed in algae-fed larvae. All died on day 11 showing an emaciated appearance, similar to starved larvae. The highest SR was observed in YOLK- and LAN-fed larvae, which also showed an elongated anterior part of the body. Negative correlations of SR with vegfaa (vascular endothelial growth factor) and morphometric traits with igf2a (insulin-like growth factor) were also found and supported by changes at the molecular level. The presence of algae in the digestive tract of the larvae and the observation of fecal droppings indicate that the algae have an appropriate size and are palatable. The increase in the digestive enzyme activity shows the larval effort to digest the algae. The fact that the algae-fed larvae died even before the larvae were kept in starvation indicates the dramatic amount of energy that the larvae spent in microalgae digestion. Although both YOLK- and LAN-fed larvae had the highest SR, LAN group started to feed on Artemia nauplii sooner. This can be linked to the delayed growth in YOLK-fed larvae and an accelerated growth in the case of LAN-fed group. LAN is an expensive feed with negative effects on water quality, whereas YOLK is a cheap and nutritionally balanced feed with fine granular texture that contributes to a larval SR similar to LAN without affecting water quality. In conclusion, microalgae cannot be considered a suitable starter food for zebrafish, whereas LAN and YOLK can be considered good starter feeds.

After its introduction for scientific investigation in the 1950s, the cypriniform zebrafish, Danio rerio, has become a valuable model for the study of regenerative processes and mechanisms. Zebrafish exhibit epimorphic regeneration, in which a nondifferentiated cell mass formed after amputation is able to fully regenerate lost tissue such as limbs, heart muscle, brain, retina, and spinal cord. The process of limb regeneration in zebrafish comprises several stages characterized by the activation of specific signaling pathways and gene expression. We review current research on key factors in limb regeneration using zebrafish as a model.