Search

2021 APR 10 (NewsRx) -- By a News Reporter-Staff News Editor at Obesity, Fitness & Wellness Week -- Investigators publish new report on Nanotechnology - Nanospheres. According to news reporting [...]

2020 OCT 31 (NewsRx) -- By a News Reporter-Staff News Editor at Obesity, Fitness & Wellness Week -- Fresh data on Drugs and Therapies - Pharmaceutical Science are presented in [...]

A research study conducted by the University of Madras in India has found that aspartame, an artificial sweetener commonly used in food and beverages, may cause developmental defects and teratogenicity in zebrafish embryos. The study focused on the role of two proteins, SIRT1 and FOXO, which are involved in neurodevelopment. The researchers discovered that aspartame exposure led to reduced larval formation, impaired cartilage development, and altered head length and locomotor behavior in zebrafish. Additionally, aspartame was found to inhibit autophagy flux in neuronal cells by impairing the SIRT1/FOXO3a axis. These findings suggest potential neurotoxicity and developmental risks associated with aspartame consumption. [Extracted from the article]

The DF4nanoGrouping framework endorsed by the European Centre for Ecotoxicology and Toxicology of Chemicals employs acellular assays, in vitroand in vivoanimal testing to perform hierarchical toxicity screening and classification of engineered nanomaterials (ENMs) for hazard prioritization with minimal animal testing. While independent in vitroand in vivonanotoxicity models are widely available, models that maximize toxicological information while minimizing costs and animal testing are much preferred by frameworks such as DF4nanoGrouping due to ethical and financial constraints over rodent testing. Herein, we investigated the zebrafish embryo as an additional test system that can be employed within the hierarchical testing frameworks, such as the DF4nanoGrouping. Toxicity data for ten diverse and well-studied ENMs, namely zinc oxide (ZnO), copper oxide (CuO), titanium dioxide (anatase, TiO2-A; rutile, TiO2-R), cerium dioxide (CeO2), zinc ferrite (ZnFe2O4), zirconium dioxide (ZrO2), quantum dots (Qdots), nano gold (nAu), and respirable microscopic crystalline SiO2(MIN-U-Sil 5), was compiled using the acellular FRAS assay, in vitroTHP-1 cells and the in vivozebrafish model, combined with state-of-the-art dosimetry models. ZnO was the most toxic of the tested ENMs in both models, yet significant changes in several descriptive endpoints, which were differentially affected by various ENMs, were noted only in the zebrafish model. The zebrafish model provided better resolution in toxicity endpoints and ranking of ENMs and was inclusive of the outcomes of the THP-1 model. Based on zebrafish toxicity endpoint data, CuO, CeO2and crystalline SiO2ranked moderate to highly toxic and comparable to ZnO. TiO2-A, TiO2-R and ZnFe2O4caused moderate toxicity, whereas ZrO2, Qdots and Au ranked minimally toxic. Our comparative analysis suggests that the zebrafish model, due to its ability to offer comparable high throughput and costs to in vitrocell models, but richer organ-level toxicological data, provides an attractive testing platform for hazard testing and prioritization of ENMs, and can serve as a bridge between in vitroand in vivorodent models. The zebrafish model deserves more consideration in nanotoxicology research for hazard screening, ranking and prioritization purposes.

A new fluorescent probe was developed for the detection of hydrazine (N2H4) with high sensitivity, good selectivity, a fast response time (3 min) and a low detection limit (7.4 nmol/L). And this probe was successfully applied to detect N2H4in living cells and zebra fish with low cytotoxicity.

A recent report from Brown University explores the effects of developmental exposure to perfluorooctane sulfonate (PFOS) on neural cell types in the developing brain. The study used larval zebrafish as a model organism and found that PFOS exposure resulted in a shift away from the homeostatic microglia state, up-regulation of the microglia activation gene p2ry12, heightened neural activity, and anxiety-like behavior in the exposed larvae. The researchers also discovered that optogenetic silencing of neurons or microglia normalized microglial responses to injury. This study provides valuable insights into the impact of toxicant exposures on microglia function and highlights the importance of assessing neuronal hyperactivity as an endpoint in studying the effects of PFOS exposure. [Extracted from the article]

Sydney, Australia (SPX) May 21, 2024 The four zebrafish aboard China's Tiangong space station, orbiting about 400 km above Earth, are in good condition, according to experts from the Chinese [...]

What's black and white and might help humans regenerate their eyes all over? The tiny zebra fish. While only a few centimeters long, the freshwater minnow native to the Himalayan [...]

2017 APR 22 (NewsRx) -- By a News Reporter-Staff News Editor at Obesity, Fitness & Wellness Week -- Researchers detail new data in Connective Tissue Cells. According to news reporting [...]

2016 NOV 26 (NewsRx) -- By a News Reporter-Staff News Editor at Obesity, Fitness & Wellness Week -- Research findings on Drugs and Therapies - Anticholinergics are discussed in a [...]

We have developed a novel ratiometric fluorescent probe NEPBwith large stokes shift and long emission wavelength for detecting hydrazine in living cells and zebra fish.

2016 SEP 17 (NewsRx) -- By a News Reporter-Staff News Editor at Obesity, Fitness & Wellness Week -- Investigators publish new report on Corpus Luteum Hormones. According to news originating [...]

Chemicals, Exploratory Animal and Medical Research, Health and Medicine, Nitrates, Nitric Acid, Silver Nitrate, Silver Compounds Keywords: Chemicals; Exploratory Animal and Medical Research; Health and Medicine; Nitrates; Nitric Acid; Silver Compounds; Silver Nitrate EN Chemicals Exploratory Animal and Medical Research Health and Medicine Nitrates Nitric Acid Silver Compounds Silver Nitrate 4650 4650 1 08/07/23 20230811 NES 230811 2023 AUG 11 (NewsRx) -- By a News Reporter-Staff News Editor at Health & Medicine Week -- Investigators publish new report on exploratory animal and medical research. [Extracted from the article]

New research suggests that fish can experience psychological stress, contrary to the belief that they cannot. The study found that fish undergo cognitive appraisal of stressors, indicating a subjective and perceptual experience of stress. Individual biases in the cognitive appraisal of stimuli were also observed, with some fish consistently evaluating ambiguous stimuli as positive or negative. Additionally, the social context was shown to modulate the response to aversive stimuli. The research concludes that psychologically stressed fish can potentially develop ulcers. [Extracted from the article]

A highly sensitive and selective fluorescent probe, NClO, was developed for ratiometric detection of HClO and had been successfully applied to detect intracellular HClO both in living cells and in zebra fish.

Traditional teratological protocols in mammals are mandatory for pharmaceutical and chemical product registration, but require hundreds of animals and are complex and money/time-consuming. Among alternative methods, low vertebrate (the teleost zebrafish and the amphibian Xenopus) whole embryo developmental toxicological tests appear evolutionary closer to humans than invertebrates and produce more useful data for human health extrapolation. At least during early stages, in fact, all vertebrate embryos share, from both morphological and molecular point of view, developmental pathways. By consequence similar toxicological responses of embryos to toxicant are expected. Advantages and disadvantages of these two alternative whole organism tests are briefly reviewed.

Zebra fish was used as testing animal to be stimulated by heavy metals (Cd2+ and Pb2+) in 1/20, 1/10, 1/5 half-lethal concentrations respectively. The superoxide dismutase (SOD) and catalase (CAT) were used as biomarkers to study the response of heavy metals pollutants in water on antioxidant enzyme of zebra fish. The results indicated that the activities of SOD weakened with the time increasing in the polluted water containing Cd2+, but the activities of CAT increased under the low concentration, and the activities trend of CAT increased at the initial period and then decreased when the concentration of Cd2+ increased a certain degree. Moreover, the activities of SOD became stronger along the time increasing in the polluted water containing Pb2+, but the enhancing trend of SOD gradually became weaker along increased concentrations, however for the activities of CAT enhanced in the initial period and then fell with the time, and the trend of decline was more and more obvious.

A critical appraisal of existing water becomes significant for assessment of sustainable development of any resource. The present research work is oriented to find out toxic effects of aluminium on a freshwater fish Brachydanioreri . By following standard procedures for toxicity determination, it was found that 61.66ppm, 59.57ppm, 57.94 ppm and 56.92ppm of aluminium toxicity for 24h, 48h, 72h and 96hours LC50 doses, whereas LC0 and LC100 doses were 52 ppm and 65ppm respectively. Erratic swimming, hyperactivity changes in opercular movement, loss of equilibrium, mucus secretion all over the body and chromatic changes on skin were observed. All these observations can be considered to monitor the quality of water contaminated with chemicals. Keywords: Aluminium | Toxicity | Brachydanio rerio | LC50 | Heavymetal | Freshwater fish., Introduction The pollution of the ecosystems by metals is a worldwide problem and ecologists try to identify various ways to control and monitor metal pollution in order to maintain the [...]

This forlorn-looking face of a 4-day-old zebrafish embryo represents 'a whole new avenue of research' for geneticist Oscar Ruiz, who studies how faces and facial abnormalities develop at the cellular [...]

Biobide, the Spanish biotech centre is using zebra fish for the development of new medicines for life-threatening diseases. The relevant details regarding its trails with the fish are discussed.

2023 JUL 8 (NewsRx) -- By a News Reporter-Staff News Editor at Obesity, Fitness & Wellness Week -- Research findings on opioids are discussed in a new report. According to [...]

The present study was performed to investigate the molecular mechanism of 6-gingerol on adipocyte-mediated systemic inflammation m vitro and in high-fat diet-induced obese zebra fish. 6-Gingerol decreased adipogenesis due to the suppression of adipocyte differentiation markers, including peroxisome proliferator-activated receptor gamma, CCAATT enhancer binding protein α, and adipocyte protein 2, and triglyceride synthesis enzymes, including sterol regulatory element-binding protein-1, fatty acid synthase, lysophosphatidic acid acyltransferase, and acyl-coA:diacylglycerol acyltransferase 1, in 3T3-L1. A coculture insert system using 3T3-L1 with RAW 264.7 (coculture insert system using fully differentiated 3T3-L1 cells with RAW 264.7 macrophages) revealed that 6-gingerol increased anti-inflammatory cytokine interleukin-10. The expression ofTNFα, monocyte chemotac-tic protein-1, interleukin-1β, and interleukin-6 were decreased in the coculture insert system using fully differentiated 3T3-L1 cells with RAW 264.7 macrophages treated with 6-gingerol. Moreover, the co-culture insert system using fully differentiated 3T3-L1 cells with RAW 264.7 macrophages treated with 6-gingerol inhibited the protein expression of TNFα and monocyte chemotactic protein-1 in RAW 264.7. 6-Gingerol decreased c-JUN N-terminal kinase and I kappa B kinase beta and its downstream target AP-1 expression in the coculture insert system using fully differentiated 3T3-L1 cells with RAW 264.7 macrophages. Furthermore, 6-gingerol decreased the expression of inducible nitric oxide synthase stimulated by the coculture insert system using fully differentiated 3T3-L1 cells with RAW 264.7 macrophages in RAW 264.7 and attenuated nitric oxide production in diet-induced obese zebra fish. Our results suggest that 6-gingerol suppresses inflammation through the regulation of the c-JUN N-terminal kinase-I kappa B kinase beta and its downstream targets. [ABSTRACT FROM AUTHOR]

The acute zebra fish embryo test (Danio rerio Hamilton-Buchanan, 1822) is an accepted bioassay to assess the toxicity of waste water that may be used for the replacement of testing with adult fish. It is also suggested for chemical hazard characterization and assessment, although only a few groups of substances have yet been studied. Specifically acting substances such as neurotoxic insecticides pose a potentially hazard for non-target fish. To establish whether the proposed zebra fish embryo test protocol and the inhibition of cholinesterases (acetylcholinesterase EC 3.1.1.7, propionylcholinesterase EC 3.1.1.8) and carboxylesterase (EC 3.1.1.1) enzymes can be used in a similar fashion for hazard characterization and risk assessment of chemicals and environmental samples, two types of experiments were conducted. Visual effects of exposure to the organophosphate metabolite paraoxon-methyl after 24 and 48 h in the zebra fish embryo test system were analysed with the use of an inverse microscope (rate of mortality, developmental disturbances, heart rate and others). The inhibition to cholinesterases and carboxylesterase was also measured. Enzyme inhibition as a biomarker of exposure was about 70 times more sensitive than the effects in the zebra fish embryo test with an IC50 below 1.2 µmol compared with an EC50 of 91 µmol. The dose-response relationships showed different curve characteristics with a linear increase of enzyme inhibition compared with a sigmoidal curve for the overt effects. Significant overt effects could only be seen at concentrations at which already 80% of the activities of the different esterases were inhibited.

Early vertebrate embryos pass through a period of remarkable morphological similarity. Possible causes for such similarity of early embryos include modularity, developmental constraints, stabilizing selection, canalization, and exhausted genetic variability. Supposedly, each process creates different patterns of variation and covariation of embryonic traits. We study the patterns of variation of the embryonic phenotype to test ideas about possible evolutionary mechanisms shaping the early embryonic development. We use the zebra fish, Danio rerio, as a model organism and apply repeated measures of individual embryos to study temporal changes of phenotypic variability during development. In particular, we are looking at the embryonic development from 12 hours post fertilization until 27 hours post fertilization. During this time period, the development of individual embryos is documented at hourly intervals. We measured maximum diameter of the eye, length of embryo, number of somites, inclination of somites, and the yolk size (as a maternal effect). The coefficient of variation (CV) was used as a measure of variability that was independent of size. We used a principal component analysis for analysis of morphological integration. The experimental setup kept environment × genotype interactions constant. Nongenetic parental contributions had no significant effects on interindividual variability. Thus all observed phenotypic variation was based on additive genetic variance and error variance. The average CV declined from 14% to 7.7%. The decline of the CV was in particular expressed during 15–19 h post fertilization and occurred in association with multiple correlations among embryonic traits and a relatively high degree of morphological integration. We suggest that internal constraints determine the patterns of variability during early embryonic development of zebra fish. J. Exp. Zool. (Mol. Dev. Evol.) 302B:000000, 2004. © 2004 Wiley‐Liss, Inc.

Acetyl-l-carnitine (ALCAR) and myo-inositol are reported to enhance motor activity in animal models; modulate membrane phospholipid metabolism (ALCAR and myo-inositol) and high-energy phosphate metabolism (ALCAR) back to normal; and be effective treatments of major depression in humans. Fish in general and zebra fish in particular present unique animal models for the in vivo study of high-energy phosphate and membrane phospholipid metabolism by noninvasive in vivo 31PNMR. This 31PNMR study of free-swimming zebra fish showed that both ALCAR and myo-inositol decreased levels of phosphodiesters and inorganic orthophosphate and increased levels of PCr in the fish. These findings demonstrate both ALCAR and myo-inositol modulate membrane phospholipid and high-energy phosphate metabolism in free-swimming zebra fish.

ABSTRACTVesicular stomatitis virus glycoprotein G-pseudotyped mouse retroviral vectors have been used as mutagens for a large-scale insertional mutagenesis screen in the zebra fish. To reproducibly generate high-titer virus stocks, we devised a method for rapidly selecting cell lines that can yield high-titer viruses and isolated a producer cell line that yields virus at a high titer on zebra fish embryos. Virus produced from this line, designated GT virus, is nontoxic following injection of zebra fish blastulae and efficiently infects embryonic cells that give rise to the future germ line. Using GT virus preparations we generated roughly 500,000 germ line-transmissible proviral insertions in a population of 25,000 founder fish in about 2 months. The GT virus contains a gene trap, and trap events can be detected in the offspring of almost every founder fish. We discuss potential applications of this highly efficient method for generating germ line-transmissible insertions in a vertebrate

We describe work on producing a selective plane illumination microscope for cardiac imaging in zebra fish embryos. The system has a novel synchronization system for imaging oscillating structures (e.g. the heart) and will have adaptive optics for image optimization.

2023 MAR 25 (NewsRx) -- By a News Reporter-Staff News Editor at Obesity, Fitness & Wellness Week -- Researchers detail new data in cell and developmental biology. According to news [...]

The effects of cyanotoxins on fish have been studied mainly in adults, rather than in early life stages which could be more sensitive or, in view of their immobility, more readily affected. The uptake of microcystin-LR by different early life stages of the zebra fish (Danio rerio) was investigated using ¹⁴C-labelled microcystin-LR. The effects on the activity of the detoxication enzymes, microsomal and soluble glutathione S-transferases (GST), and glutathione peroxidase (GP-X) were examined. There was a detectable uptake of microcystin from the first day of embryonic development up to 5 day old larvae. On average, an absorption of 0.5 ng microcystin for eggs and eleuthero-embryos was calculated over the entire exposure time. Because of the differences in volume of the eggs and eleuthero-embryos, there was an increase in the microcystin-LR concentration between these stages. In the eggs, approximately 25% of the medium concentration was found, and in eleuthero-embryos an equilibrium between fish and medium was reached. The activity of the detoxication enzymes differed during ontogenesis, but the effects of activation and suppression of these enzymes were similar at all stages. Minor activation of the soluble GST was found and a marked activation of GP-X was evident. The reaction of the microsomal GST was not so obvious. These results showed that there was an uptake of microcystin-LR by early life stages of the zebra fish and that the detoxication system reacted to this toxin, possibly indicating the ability of the organism to metabolize microcystin-LR to a less harmful compound. Chronic toxic effects, such as reduction in growth, in such early life stages when organogenesis is not finished and hence the microcystin-LR affects not one single target organ but the whole organism, might be due to the increased energy demand of these detoxication processes. ©1999 John Wiley & Sons, Inc. Environ Toxicol 14: 89–95, 1999

The early development of the zebra fish (Danio rerio) embryo is characterized by a series of rapid and synchronous cell cycles with no detectable transcription. This period is followed by the midblastula transition (MBT), during which the cell cycle gradually lengthens, cell synchrony is lost, and zygotic transcription is initially detected. In this work, we examined the changes in the pattern of the cell cycle during MBT in zebra fish and whether these changes are dependent on the initiation of zygotic transcription. To characterize the pattern of the early zebra fish cell cycles, the embryonic DNA content was determined by flow cytometric analysis. We found that G1phase is below detection levels during the first 10 cleavages and can be initially detected at the onset of MBT. Inhibition of zygotic transcription, by microinjection of actinomycin D, abolished the appearance of G1phase at MBT. Premature activation of zygotic transcription, by microinjection of nonspecific DNA, induced G1phase before the onset of MBT, while coinjection of actinomycin D and nonspecific DNA abolished this early appearance of G1phase. We therefore suggest that during the early development of the zebra fish embryo, G1phase appears at the onset of MBT and that the activation of transcription at MBT is essential and sufficient for the G1-phase induction.

The E2A protein is a mammalian transcription factor of the helix-loop-helix family which is implicated in cell-specific gene expression in several cell lineages. Mouse E2A contains two independent transcription activation domains, ADI and ADII; whereas ADI functions effectively in a variety of cultured cell lines, ADII shows preferential activity in pancreatic beta cells. To analyze this preferential activity in an in vivo setting, we adapted a system involving transient gene expression in microinjected zebra fish embryos. Fertilized one- to four-cell embryos were coinjected with an expression plasmid and a reporter plasmid. The expression plasmids used encode the yeast Gal4 DNA-binding domain (DBD) alone, or Gal4 DBD fused to ADI, ADII, or VP16. The reporter plasmid includes the luciferase gene linked to a promoter containing repeats of UASg, the Gal4-binding site. Embryo extracts prepared 24 h after injection showed significant luciferase activity in response to each of the three activation domains. To determine the cell types in which the activation domains were functioning, a reporter plasmid encoding beta-galactosidase and then in situ staining of whole embryos were used. Expression of ADI led to activation in all major groups of cell types of the embryo (skin, sclerotome, myotome, notochord, and nervous system). On the other hand, ADII led to negligible expression in the sclerotome, notochord, and nervous system and much more frequent expression in the myotome. Parallel experiments conducted with transfected mammalian cells have confirmed that ADII shows significant activity in myoblast cells but little or no activity in neuronal precursor cells, consistent with our observations in zebra fish. This transient-expression approach permits rapid in vivo analysis of the properties of transcription activation domains: the data show that ADII functions preferentially in cells of muscle lineage, consistent with the notion that certain activation domains contribute to selective gene activation in vivo.

The purpose of this study was to investigate the effect of density of fish on the rate of avoidance learning in a schooling fish. Naive adult zebra fish (Brachydanio rerio) were trained in a two-way aquatic shuttlebox, in isolation, in groups of two, or in groups of five. The number of trials to reach progressively more exacting levels of performance (1, 2, 3, … ,9 consecutive correct avoidance responses on 2 successive days), was used to quantify the rate of learning for individuals in the three groups. Using this measure, individuals in groups of five reached any given level of performance in fewer trials than individuals tested alone, which in turn reached the progressive criteria in fewer trials than individuals tested in pairs. In addition, the mean latency of response to the conditioned stimulus for individuals in groups of five was significantly lower than for individuals tested alone or in groups of two by Day 3 of the experiment. The rate of learning in zebra fish schools at these densities may be due to either a balance between imitation learning and conflict-inhibition among the fish or the elicitation of different behavioral responses by shock, depending upon environmental stimuli.The purpose of this study was to investigate the effect of density of fish on the rate of avoidance learning in a schooling fish. Naive adult zebra fish (Brachydanio rerio) were trained in a two-way aquatic shuttlebox, in isolation, in groups of two, or in groups of five. The number of trials to reach progressively more exacting levels of performance (1, 2, 3, … ,9 consecutive correct avoidance responses on 2 successive days), was used to quantify the rate of learning for individuals in the three groups. Using this measure, individuals in groups of five reached any given level of performance in fewer trials than individuals tested alone, which in turn reached the progressive criteria in fewer trials than individuals tested in pairs. In addition, the mean latency of response to the conditioned stimulus for individuals in groups of five was significantly lower than for individuals tested alone or in groups of two by Day 3 of the experiment. The rate of learning in zebra fish schools at these densities may be due to either a balance between imitation learning and conflict-inhibition among the fish or the elicitation of different behavioral responses by shock, depending upon environmental stimuli.

To determine cis-acting elements required for neuron specific expression of a necdin gene, we tried to use zebra fish assay system in vivo instead of cell lines in vitro. Various expression vectors carrying upstream sequences of necdin gene fused to MEKA (lacZ) gene as a reporter were injected into fertilized zebra fish embryos and then the expression of the reporter gene was analyzed by the whole mount immunochemical method. No promoter activity was obtained with a construct carrying sequence from −63 to +63 of the necdin gene, while promoter activity with preferential skin expression was obtained with a construct having sequence from −86 to +28. Further upstream sequence from −173 to +28 exhibited neuron specific expression as well as that from −845 to +63. These results indicate that a cis-acting element responsible for neuron specific expression is located in an 87bp sequence from −173 to −87 of necdin gene.Copyright 1995, 1999 Academic Press, Inc.

The early development of the zebra fish (Danio rerio) embryo is characterized by a series of rapid and synchronous cell cycles with no detectable transcription. This period is followed by the midblastula transition (MBT), during which the cell cycle gradually lengthens, cell synchrony is lost, and zygotic transcription is initially detected. In this work, we examined the changes in the pattern of the cell cycle during MBT in zebra fish and whether these changes are dependent on the initiation of zygotic transcription. To characterize the pattern of the early zebra fish cell cycles, the embryonic DNA content was determined by flow cytometric analysis. We found that G1 phase is below detection levels during the first 10 cleavages and can be initially detected at the onset of MBT. Inhibition of zygotic transcription, by microinjection of actinomycin D, abolished the appearance of G1 phase at MBT. Premature activation of zygotic transcription, by microinjection of nonspecific DNA, induced G1 phase before the onset of MBT, while coinjection of actinomycin D and nonspecific DNA abolished this early appearance of G1 phase. We therefore suggest that during the early development of the zebra fish embryo, G1 phase appears at the onset of MBT and that the activation of transcription at MBT is essential and sufficient for the G1-phase induction.

Retinoid X receptors (RXRs), along with retinoic acid (RA) receptors (RARs), mediate the effects of RA on gene expression. Three subtypes of RXRs (alpha, beta, and gamma) which bind to and are activated by the 9-cis stereoisomer of RA have been characterized. They activate gene transcription by binding to specific sites on DNA as homodimers or as heterodimers with RARs and other related nuclear receptors, including the vitamin D receptor, thyroid hormone receptors (TRs), and peroxisome proliferator-activated receptors. Two additional RXR subtypes (delta and epsilon) isolated from zebra fish cDNA libraries are described here; although both subtypes form DNA-binding heterodimers with RARs and TR, neither binds 9-cis RA, and both are transcriptionally inactive on RXR response elements. In cotransfection studies with TR, the delta subtype was found to function in a dominant negative manner, while the epsilon subtype had a slight stimulatory effect on thyroid hormone (T3)-dependent transcriptional activity. The discovery of these two novel receptors in zebra fish expands the functional repertoire of RXRs to include ligand-independent and dominant negative modulation of type II receptor function.

To gain insight into the role of Myc family oncoproteins and their associated protein Max in vertebrate growth and development, we sought to identify homologs in the zebra fish (Brachydanio rerio). A combination of a polymerase chain reaction-based cloning strategy and low-stringency hybridization screening allowed for the isolation of zebra fish c-, N-, and L-myc and max genes; subsequent structural characterization showed a high degree of conservation in regions that encode motifs of known functional significance. On the functional level, zebra fish Max, like its mammalian counterpart, served to suppress the transformation activity of mouse c-Myc in rat embryo fibroblasts. In addition, the zebra fish c-myc gene proved capable of cooperating with an activated H-ras to effect the malignant transformation of mammalian cells, albeit with diminished potency compared with mouse c-myc. With respect to their roles in normal developing tissues, the differential temporal and spatial patterns of steady-state mRNA expression observed for each zebra fish myc family member suggest unique functions for L-myc in early embryogenesis, for N-myc in establishment and growth of early organ systems, and for c-myc in increasingly differentiated tissues. Furthermore, significant alterations in the steady-state expression of zebra fish myc family genes concomitant with relatively constant max expression support the emerging model of regulation of Myc function in cellular growth and differentiation.

The nuclei in the blastomeres of Brachydanio reriocan be observed easily in life. They are visible in the prophase and telophase as well as in the interkinetic phase. This discovery is used (1) to confirm and consolidate the results obtained from sectioned material; (2) to fix the blastomeres in any desired mitotic phase; and (3) to determine the duration of mitosis and its phases.The duration of mitosis and its phases under constant conditions, particularly with respect to temperature, is found to be constant for each cleavage. The time from the breakdown of 32 nuclei to the breakdown of 64 nuclei is 18 minutes at 25° C. This places the cleavage divisions of the zebra fish among the most rapid ever observed. The first six cleavages show a trend towards acceleration, the sixth being the most rapid one. From then on the speed of the divisions slows down. This trend is essentially undisturbed by changes in temperature.The nuclear divisions during cleavage are characterized (1) by the formation of chromosomal vesicles in the telophase (some of these vesicles can frequently be seen in life to persist through the interphase); (2) by a comparatively short duration of this type of telophase; (3) by a very short, if any, true interphase; (4) by the lack of nucleoli; and (5) by the absence of a typical spireme formation in the prophase.The very short duration of the telophase has been recorded for the first time. The other observations have been found in the cleavage divisions of a majority of the species examined. In the zebra fish egg they continue until about the twelfth cleavage, when the form of mitosis typical for the adult first appears. It is suggested that this type of mitosis is probably associated with the rapid sequence of divisions and is generally characteristic of cleavage mitoses. The most characteristic feature of this type of karyokinesis is the formation of the chromosomal vesicles, but the shortening of the interphase and telophase, and the lack of spireme formation in the prophase are also obvious.

Boston MA (SPX) Nov 18, 2022 A new study from MIT and Harvard University suggests that the brains of the seemingly simple zebrafish are more sophisticated than previously thought. The [...]

We applied an acute stress model to zebra fish in order to measure the changes in the metabolome due to biological stress. This was done by submitting the fish to fifteen minutes of acute confinement (netting) stress, and then five minutes for the open field and light/dark field tests. A polar extract of the zebra fish was then subjected to ¹H nuclear magnetic spectroscopy. Multivariate data analysis of the spectra showed a clear separation associated to a wide range of metabolites between zebra fish that were submitted to open field and light/dark field tests. Alanine, taurine, adenosine, creatine, lactate, and histidine were high in zebra fish to which the light/dark field test was applied, regardless of stress, while acetate and isoleucine/lipids appeared to be higher in zebra fish exposed to the open field test. These results show that any change in the environment, even for a small period of time, has a noticeable physiological impact. This research provides an insight of howdifferentmechanisms are activated under different environments tomaintain the homeostasis of the body. It should also contribute to establish zebra fish as a model for metabolomics studies. [ABSTRACT FROM AUTHOR]

Blood is amazingly delicate and unstable. Essentially a suspension of cells and proteins in water, blood forms clots or clumps in response to any harsh mechanical treatment. That property keeps [...]

Research in genetics, cancer treatment and drug therapy requires that large numbers of cells be injected with drugs or DNA to investigate cell behaviour. Traditionally, this task has been performed manually. The cell preparation stage, which includes cell separation, cell transfer, cell patterning and cell release is very time consuming. In order to increase the throughput of the cell injection process, a system that can replicate the actions of technicians is required. To prepare the cells for injection, cells must be separated and patterned without damage. This paper presents a new design to solve this problem. A cell preparation system has been designed, utilising FLOW 3D simulations, to separate and pattern cells for injection. Flow simulations of suspended cells and corresponding experiments have demonstrated that the proposed system is capable of successfully carrying out cell separation, cell patterning and cell transfer, enhancing the speed and throughput of this important laboratory technique.

1. Extracellular unit recording was done in the brain and spinal cord of unanesthesized zebra fish larvae embedded in a drop of gelatin under a compound microscope. Startle responses were elicited either by vibrating a stylus against the ear vesicle, or by direct electrical stimulation of the spinal cord. 2. As in adult fish, the Mauthner neurons produced a prominent negative potential (0.5-1 mV) which occurred at the beginning of the startle reflex. The axonal conduction velocity was 1.7-3.7 m/s. 3. With vibratory stimulation, the startle reflex was elicited most reliably at rates of 1/min or less, though the Mauthner cells would follow stimulation rates of 1/s when the spinal cord was stimulated electrically. At this rate there was considerable fatigue of the spike itself, which became smaller in amplitude and longer in duration. 4. The auditory system functions during vibratory stimulation of the ear vesicle, and probably activates the Mauthner cells, though it was not concluded that this was an exclusive excitatory pathway during these experiments. Lateral line or purely tactile receptors might also be involved. The latency of the Mauthner spike varied inversely (range, 6-17.5 ms) with the intensity of the vibratory stimulus. Muscle contractions began 2 ms after the Mauthner spike. 5. We recorded several forms of startle behavior, including a single tail flip or a tail flip followed by regular or irregular tail movements. The Mauthner neuron almost always fired at the beginning of the response, but it never fired again during subsequent movements. This supports an earlier contention that the Mauthner cell initiates the tail flip but is not involved in iterative swimming behavior.

A medium is described for the culture of follicular isolates from adult female zebra fish, Brachydanio rerio. Preliminary observations are made on the behaviour of the cells of the cultured isolates in the absence of an oocyte and ovarian influence.