Zebrafish最新文献

The study of swimming behavior is an important part of fish biology research and the swim tunnel is used to study swimming performance as well as metabolism of fish. In this investigation, we have developed a user-friendly, automated, modular, and low-cost swim tunnel that permits to study the performance of one or more fish separately, as well as a small group of individuals. To validate our swim tunnel, we assessed swimming activity of four different species (zebrafish, medaka, guppy, and cavefish) recording reliable data of swimming behavior and performance. Because swimming behavior has been recently used in different fields from physiology to ecotoxicology, our setup could help researchers with a low-cost solution.

The phospholipid phosphatase FIG4/Fig4 is a subunit of PIKFYVE/Pikfyve kinase complex that synthesizes phosphatidylinositol 3,5-bisphosphate (PI(3,5)P₂), a key regulator of endolysosomal trafficking and function. Loss of FIG4/Fig4 leads to intracellular deficiency of PI(3,5)P₂ signaling and multiple endolysosomal defects. Previous works were focused on the effects of FIG4/Fig4 mutations in the nervous and musculoskeletal systems in human clinical and animal studies. In this study, we describe a zebrafish recessive mutant cq35 showing robust liver vacuolation and lethality, with a predicted truncating mutation in fig4a gene. The liver vacuolation progress in fig4a mutant was reversible after regaining normal fig4a transcripts. The hepatic vacuolation pathology was identified as abnormal lysosomal storage with numerous accumulated cargoes, including autophagy intermediates, and caused progressive degeneration of bile canaliculi in mutant liver. These hepatic pathological details of fig4a mutant were repeated in zebrafish pikfyve mutant. Thus, zebrafish possess the conserved structural and functional mechanisms in Pikfyve kinase complex, based on which, pikfyve mutant phenotype covered fig4a mutant phenotype in their double mutant. Our findings represent the first description of the in vivo defects caused by FIG4/Fig4 mutation or PI(3,5)P₂ deficiency in liver, and reveal the conserved complex mechanisms associated with FIG4/Fig4-deficient disorders in zebrafish.

Overweight and obesity are worldwide epidemic health threats. They recently emerged as disruptors of brain homeostasis leading to a wide variety of neurologic disorders. This study aims at developing a fast and easy overfeeding model using zebrafish for investigating the impact of overweight on brain homeostasis. We established a 4-week overfeeding protocol using commercially available dry food in an ad libitum-like feeding. In the diet-induced obesity/overweight (DIO) fish model, weight, size, and body mass index were increased compared with controls. Also, DIO fish displayed hyperglycemia, and had higher levels of advanced glycation end products and oxidative stress (4-hydroxynonenal [4-HNE]) in a peripheral organ (tail). Although overfed fish did not display major blood-brain barrier leakage, they showed an increased cerebral oxidative stress, blunted brain cell proliferation as well as a striking decreased locomotor activity. Interestingly, switching from an overfeeding to a normal diet partially improved peripheral and central disruptions induced by overfeeding in solely 2 weeks. As a conclusion, this study provides a rapid and easy overfeeding model in zebrafish with relevant peripheral and central disruptions. This model could open the way for further investigations to better understand by which mechanisms overfeeding could disturb brain homeostasis. It also reinforces and contrasts with another zebrafish overweight model, showing that the type of the food provided could impair differently brain homeostasis.

Melatonin is a hormone related to circadian rhythms and has potential clinical applications. Our objectives were to verify the effect of melatonin on the liver of zebrafish exposed to fructose and evaluate the expression of appetite-related genes (leptin, ghrelin, and melanocortin receptor 4 [MC4R]). Animals were divided into three groups: control (CG, n = 25), fructose (FG, n = 25), and fructose+melatonin (FMG, n = 25). The study was carried out in 8 weeks. FG and FMG were exposed to 2% fructose and FMG treated with 1 μM of melatonin. Histological liver studies and gene expression analyses of Leptin, Ghrelin, and MC4R (liver and intestines) were performed. FG developed hepatic steatosis, which did not occur with CG and FMG. Genetic expression of hepatic leptin and MC4R did not show significant difference among the groups. Animals exposed to fructose (FG) presented an increased expression of intestinal leptin compared to those administered with melatonin. Animals exposed to fructose gained weight and developed an important hepatic steatosis, but melatonin reduced significantly the hepatic damage. Intestinal leptin showed increased expression in the group exposed to fructose.

Intestinal neoplasms and preneoplastic lesions are common in zebrafish research facilities. Previous studies have demonstrated that these neoplasms are caused by a transmissible agent, and two candidate agents have been implicated: a Mycoplasma sp. related to Mycoplasma penetrans and the intestinal parasitic nematode, Pseudocapillaria tomentosa, and both agents are common in zebrafish facilities. To elucidate the role of these two agents in the occurrence and severity of neoplasia and other intestinal lesions, we conducted two experimental inoculation studies. Exposed fish were examined at various time points over an 8-month period for intestinal histopathologic changes and the burden of Mycoplasma and nematodes. Fish exposed to Mycoplasma sp. isolated from zebrafish were associated with preneoplastic lesions. Fish exposed to the nematode alone or with the Mycoplasma isolate developed severe lesions and neoplasms. Both inflammation and neoplasm scores were associated with an increase in Mycoplasma burden. These results support the conclusions that P. tomentosa is a strong promoter of intestinal neoplasms in zebrafish and that Mycoplasma alone can also cause intestinal lesions and accelerate cancer development in the context of nematode infection.

Nutritional programming (NP) is considered a promising approach that can counteract the negative effects of dietary plant protein (PP) by introducing PP to fish in the early developmental stages. Therefore the objective of our study was to assess the effect of NP on PP utilization and the gut microbiome in zebrafish Danio rerio. The study included four treatment groups: (1) a positive control group that received a fishmeal (FM) diet throughout the entire trial (+ control); (2) a negative control group that received PP diet throughout the entire trial (- control); (3) an NP group that received dietary PP during the larval stage followed by FM-based diet during the juvenile stage and PP diet again during a PP challenge in the grow-out phase (NP-PP); and (4) an FM-group that received FM-based diet during the larval and juvenile stages and was challenged with a PP diet during the grow-out phase (NP-FM). During the PP challenge, the NP-PP group achieved the highest weight gain compared to the (-) control and NP-FM groups. The relative abundance of certain phyla such as Chloroflexi, Planctomycetes, and Bacteroidetes presented higher values in some groups at early juvenile stage. The fish gut microbiome also presented differences throughout the study.

Although gamete cryopreservation has facilitated advancement of reproduction research by allowing the storage of cells over prolonged periods of time, during freezing-thawing cycles, cells inevitably suffer from cryoinjuries. Here, we evaluate oxidative stress and DNA damage of zebrafish sperm at different stages of the cryopreservation process. It was generally observed that the freezing and thawing of the samples led to an increase in the generation of reactive oxygen species and the activity of the catalase enzyme and a reduction in the generation of sulfhydryl groups and superoxide dismutase activity. The alkaline comet assay demonstrated that DNA damage increased after equilibration time, with an even greater increase after freezing and thawing. The comet assay modified with the enzyme formamidopyrimidine glycosylase, and Endonuclease III demonstrated greater DNA damage than the standard comet assay, demonstrating a high degree of oxidation of purines and pyrimidines at all stages of cryopreservation. Our results show that the freeze and thaw processes cause greater oxidative stress and DNA damage than cryoprotectant toxicity during exposure at the equilibrium stage.

Gymnotus is the most studied genus of the order Gymnotiformes, but the morphological similarities of the different species make it difficult to identify taxa reliably. The present study is a continuation of the ongoing research into the taxonomic diversity of the stocks of Gymnotus sold as live bait in the Pantanal, Brazil. These studies have been based on cytogenetic analyses, DNA barcoding, and the analysis of coloration patterns. The results of the cytogenetic analysis confirmed the presence of three distinct strains, recognized as Gymnotus paraguensis, G. sylvius, and G. pantanal. However, the results revealed that the molecular operational taxonomic units identified as G. paraguensis actually include a relatively diverse set of fish, separated by considerable genetic distances. As the G. paraguensis specimens also presented considerable variation in coloration patterns, further genetic diversity analyses were conducted on these individuals, to test the hypothesis that more than one species is present in this cytotaxonomic unit. The haplotype network revealed a regional pattern in the distribution of this species. The results indicate that the observed variation in coloration patterns is associated with a high degree of phenotypic plasticity in G. paraguensis. These findings emphasize the importance of using an integrative approach for a more accurate diagnosis of Gymnotus, in particular, the species marketed as live bait for the fisheries of the upper Paraguay River basin in the Brazilian Pantanal.

Many scientific studies still use zebrafish from pet stores as animal models, even cutting-edge researches. However, these animals differ genotypically and phenotypically between them. The importance of the use of standardized models is widely recognized. Besides that, another consequence of using zebrafish from unknown origins is the acquisition of parasitized animals. This study aimed to relate the infection by Clinostomum sp. in zebrafish. Animals sold as "high standard" were acquired from a commercial company. Swimming alterations and superficial yellow dots were observed in five zebrafish with clinical signs, which were isolated, euthanized, and necropsied. Muscular yellow cysts with metacercaria associated with lesions were observed. The muscular cysts were responsible for the superficial yellow dots as well as the swimming alterations. The prevalence was 2.5%, and the mean infection intensity was 7 digeneans/host. The cysts measured a mean of 1251.43 μm long × 784.28 μm wide. Metacercariae measured a mean of 4847 μm long × 1353 μm wide. This first report about infection by Clinostomum sp. in zebrafish is globally relevant since the host and the parasite genus currently overlap worldwide. Furthermore, this study sheds light on the importance of the specific pathogen-free commercial creations or laboratory-reared zebrafish for research.

Alcoholism causes deleterious effects such as physiological and neuronal alterations leading to the cognitive and other behavioral impairments. Mitochondrial and synaptosomal deteriorations in the brain of alcoholic persons exhibited metabolic, biochemical changes and other related risk factors, which mainly affect the brain function. This study aimed to assess the effect of chronic alcohol-induced mitochondrial and synaptosomal oxidative damage along with behavioral impairment in adult zebrafish. Zebrafish of control group received the system water and normal diet ad libitum (group I); the other groups were treated with 0.20% alcohol (group II) and 0.40% alcohol (group III) directly in fish tank for 22 days. The result revealed significant increase in lipid peroxidation, protein carbonylation, superoxide dismutase, and glutathione, and significant decline in the activity of catalase and Na⁺/K⁺ ATPase compared to control. Furthermore, the alcohol-treated zebrafish also showed significant behavioral alterations. Collectively, this regulatory mechanism demonstrates the effect of long-term alcohol consumption in the zebrafish. Our results indicate that this recreational drug "alcohol" is harmful to brain mitochondria and synaptosomes, which are the main organelles, and play an important role in memory, learning, cognitive function, and ATP formation in the brain, which may represent a significant public health concern.