Browsing by Subject "zebrafish"

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  • Wang, Shuyuan; Alenius, Harri; El-Nezami, Hani; Karisola, Piia (2022)
    Titanium dioxide (TiO2) and zinc oxide (ZnO) nanoparticles (NPs) have attracted a great deal of attention due to their excellent electrical, optical, whitening, UV-adsorbing and bactericidal properties. The extensive production and utilization of these NPs increases their chances of being released into the environment and conferring unintended biological effects upon exposure. With the increasingly prevalent use of the omics technique, new data are burgeoning which provide a global view on the overall changes induced by exposures to NPs. In this review, we provide an account of the biological effects of ZnO and TiO2 NPs arising from transcriptomics in in vivo and in vitro studies. In addition to studies on humans and mice, we also describe findings on ecotoxicology-related species, such as Danio rerio (zebrafish), Caenorhabditis elegans (nematode) or Arabidopsis thaliana (thale cress). Based on evidence from transcriptomics studies, we discuss particle-induced biological effects, including cytotoxicity, developmental alterations and immune responses, that are dependent on both material-intrinsic and acquired/transformed properties. This review seeks to provide a holistic insight into the global changes induced by ZnO and TiO2 NPs pertinent to human and ecotoxicology.
  • Mauramo, Matti; Onali, Tuulia; Wahbi, Wafa; Vasara, Jenni; Lampinen, Anniina; Mauramo, Elina; Kivimäki, Anne; Martens, Stefan; Häggman, Hely; Sutinen, Meeri; Salo, Tuula (2021)
    Previous studies indicate that bilberry with high amounts of phenolic compounds can inhibit carcinogenic processes of colorectal cancer in vitro and in vivo. However, no studies have focused on the effects of bilberry on oral cancer. In this study, we aimed to examine the effects of bilberry powder on oral squamous cell carcinoma (OSCC) cells using both in vitro and in vivo assays. The effects of 0, 1, 10, and 25 mg/mL of whole bilberry powder on the viability, proliferation, migration, and invasion of OSCC (HSC-3) cells were examined and compared with 0.01 mg/mL of cetuximab. Two oral keratinocyte cell lines served as controls. Tumor area was analyzed in zebrafish microinjected with HSC-3 cells and treated with 2.5, 10, or 25 mu g/mL of bilberry powder. Metastases in the head or tail areas were counted. Bilberry powder inhibited the viability, proliferation, migration, and invasion of HSC-3 cells (p < 0.05), which was more pronounced with higher concentrations. Cetuximab had no effect on HSC-3 cell migration or invasion. Compared to controls, the tumor area in zebrafish treated with bilberry powder (10 and 25 mu g/mL) was reduced significantly (p = 0.038 and p = 0.021, respectively), but the number of fish with metastases did not differ between groups. Based on our in vitro and in vivo experiments, we conclude that whole bilberry powder has anti-tumor effects on OSCC cells.
  • Hujanen, Roosa; Almahmoudi, Rabeia; Salo, Tuula; Salem, Abdelhakim (2021)
    Tissue vasculature provides the main conduit for metastasis in solid tumours including head and neck squamous cell carcinoma (HNSCC). Vascular mimicry (VM) is an endothelial cell (EC)-independent neovascularization pattern, whereby tumour cells generate a perfusable vessel-like meshwork. Yet, despite its promising clinical utility, there are limited approaches to better identify VM in HNSCC and what factors may influence such a phenomenon in vitro. Therefore, we employed different staining procedures to assess their utility in identifying VM in tumour sections, wherein mosaic vessels may also be adopted to further assess the VM-competent cell phenotype. Using 13 primary and metastatic HNSCC cell lines in addition to murine- and human-derived matrices, we elucidated the impact of the extracellular matrix, tumour cell type, and density on the formation and morphology of cell-derived tubulogenesis in HNSCC. We then delineated the optimal cell numbers needed to obtain a VM meshwork in vitro, which revealed cell-specific variations and yet consistent expression of the EC marker CD31. Finally, we proposed the zebrafish larvae as a simple and cost-effective model to evaluate VM development in vivo. Taken together, our findings offer a valuable resource for designing future studies that may facilitate the therapeutic exploitation of VM in HNSCC and other tumours.
  • Abdelrehiem, Dina Ahmed Mosselhy; Virtanen, Jenni Maaret Elina; Kant, Ravi; He, Wei; Elbahri, Mady; Sironen, Tarja (2021)
    Every day, new information is presented with respect to how to best combat the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). This manuscript sheds light on such recent findings, including new co-factors (i.e., neuropilin-1) and routes (i.e., olfactory transmucosal) allowing cell entry of SARS-CoV-2 and induction of neurological symptoms, as well as the new SARS-CoV-2 variants. We highlight the SARS-CoV-2 human-animal interfaces and elaborate containment strategies using the same vaccination (i.e., nanoparticle "NP" formulations of the BNT162b2 and mRNA-1273 vaccines) for humans, minks, raccoon dogs, cats, and zoo animals. We investigate the toxicity issues of anti-CoV NPs (i.e., plasmonic NPs and quantum dots) on different levels. Namely, nano-bio interfaces (i.e., protein corona), in vitro (i.e., lung cells) and in vivo (i.e., zebrafish embryos) assessments, and impacts on humans are discussed in a narrative supported by original figures. Ultimately, we express our skeptical opinion on the comprehensive administration of such antiviral nanotheranostics, even when integrated into facemasks, because of their reported toxicities and the different NP parameters (e.g., size, shape, surface charge, and purity and chemical composition of NPs) that govern their end toxicity. We believe that more toxicity studies should be performed and be presented, clarifying the odds of the safe administration of nanotoxocological solutions and the relief of a worried public.
  • Sihvonen, Mikko (Helsingin yliopisto, 2021)
    Mycobacterium tuberculosiksen aiheuttama tuberkuloosi on yksi yleisimmistä kuolemaan johtavista sairauksista kehitysmaissa. M. tuberculosis-bakteerin tiedetään kykenevän väistämään potilaan immuunipuolustusta ja hyödyntämään makrofagien sekä muiden puolustussolujen ominaisuuksia. M. tuberculosis kykenee lisääntymään makrofagien sisällä. Eksosomit ovat solunulkoisia rakkuloita, joita kaikki solut erittävät. Eksosomeilla tiedetään olevan myös immunomodulatorisia vaikutuksia. Tutkimuksen tarkoituksena oli kehittää in vivo-malli eksosomien immunomodulatoristen ominaisuuksien mallintamiseen seeprakaloissa, hyödyntämällä seeprakalojen omaa Mycobacterium marinum-patogeeniä. Tutkimuksessa käytettiin ihmisen monosyyttilinjan soluja (THP-1), lämpötapettuja M. marinum-bakteereja ja seeprakalojen poikasia. THP-1 -soluja käsiteltiin lämpötapetuilla M. marinum bakteereilla viidellä eri bakteerikonsentraatiolla. Lisäksi tutkimuksessa oli yksi bakteereilla käsittelemätön THP-1 -soluviljelmä. Kaikista THP-1 -soluviljelmistä eristettiin ultrasentrifugaatiolla kyseisten solujen tuottamia eksosomeja. Eristettyä eksosomeja mikroinjektoitiin kuorittujen seeprakalan poikasten ruskuaispussin blood circulation valley -suoneen, jotta nähtäisiin aiheuttavatko ne muutoksia kalojen tulehduksenvälittäjäaineiden geenien ilmentymisessä eli geeniekspressiossa. Noin puolen vuorokauden jälkeen kalaryhmästä poistettiin kuolleet yksilöt ja elossa olevat kerättiin talteen RNA-eristystä varten. Eristetty RNA käännettiin DNA:ksi ja reaaliaikaisella polymeraasiketjureaktiolla, qPCR:llä, mitattiin kohdegeenien ekspressioita. Tutkimuksessa havaittiin valittujen tulehdusvälittäjäaineiden geenien ilmentymisen lisääntymistä seeprakaloissa. Geenin ilmentymstaso oli sitä suurempi, mitä suuremmalle bakteerimäärälle THP-1 -solut oli altistettu ennen eksosomien eristystä. Kaikkein korkeimmat tulehdusvälittäjäaineiden geeniekspressiotasot nähtiin altistamattomien solujen eksosomeilla injektoitujen kalojen ryhmissä. Kontrolliksi valitussa geenissä ei havaittu vastaavaa geeniekspression kasvua. Näiden tutkimustulosten perusteella lämpötapetulla M. marinumilla käsiteltyjen THP-1 -solujen eksosomeilla näyttäisi olevan kyky aiheuttaa samankaltaisia muutoksia tulehdusvälittäjäaineiden geeniekspressiossa kuin seeprakalojen suoralla M. marinum infektiolla. Tulosten vahvistamiseen tarvitaan vielä lisätutkimuksia.
  • Moog, Maia (Helsingin yliopisto, 2022)
    Catastrophic childhood epilepsies are characterized by persistent seizures and are frequently associated with cognitive and developmental impairments. Many, approximately 30%, of these epilepsies are rare genetic disorders that do not have effective therapeutic options. The bench to drug process is lengthy and expensive, and thus it is critical to find more affordable drug screening options. Zebrafish are an ideal model organism for screening studies as they share considerable (70%) genetic similarities with humans and are cheap to maintain with efficient breeding capabilities. In the present study, 37 zebrafish lines were screened for epileptic brain activity to identify high priority genes for future pharmacology studies. Each zebrafish line, generated by CRISPR-Cas9 represents a single gene loss of function mutation associated with 3 epilepsy based on genome wide association studies. Larval zebrafish were screened for spontaneous seizure activity using electrophysiological assays. The following 8 genes were significantly associated with spontaneous seizure activity in zebrafish: EEF1A, ARX, GRIN1, GABRB3, PNPO, STRADA, SCN1A, and STXBP1. There is now an open-source database for all 37 zebrafish lines, which contains sequencing information, survival curves, behavioral profiles, and electrophysiological data. The findings reveal novel target genes for future drug development and discovery. Future work is needed to explore whether zebrafish also model co-morbidities commonly seen in human patients with epilepsy.
  • Larbalestier, Hannah; Keatinge, Marcus; Watson, Lisa; White, Emma; Gowda, Siri; Wei, Wenbin; Koler, Katjusa; Semenova, Svetlana A.; Elkin, Adam M.; Rimmer, Neal; Sweeney, Sean T.; Mazzolini, Julie; Sieger, Dirk; Hide, Winston; McDearmid, Jonathan; Panula, Pertti; MacDonald, Ryan B.; Bandmann, Oliver (2022)
    The Parkinson's disease (PD) risk gene GTP cyclohydrolase 1 (GCH1) catalyzes the rate-limiting step in tetrahydrobiopterin (BH4) synthesis, an essential cofactor in the synthesis of monoaminergic neurotransmitters. To investigate the mechanisms by which GCH1 deficiency may contribute to PD, we generated a loss of function zebrafish gch1(-/- )mutant (gch1(-/-), using CRISPR/Cas technology. gch1(-/-) zebrafish develop marked monoaminergic neurotransmitter deficiencies by 5 d postfertilization (dpf), movement deficits by 8 dpf and lethality by 12 dpf. Tyrosine hydroxylase (Th) protein levels were markedly reduced without loss of ascending dopaminergic (DAergic) neurons. L-DOPA treatment of gchl(-/-) larvae improved survival without ameliorating the motor phenotype. RNAseq of gchl(-/-) larval brain tissue identified highly upregulated transcripts involved in innate immune response. Subsequent experiments provided morphologic and functional evidence of microglial activation in gchl(-/-). The results of our study suggest that GCH1 deficiency may unmask early, subclinical parkinsonism and only indirectly contribute to neuronal cell death via immune-mediated mechanisms. Our work highlights the importance of functional validation for genome-wide association studies (GWAS) risk factors and further emphasizes the important role of inflammation in the pathogenesis of PD.
  • Sillanpää, Alina (Helsingin yliopisto, 2021)
    Tuberculosis (TB) still ranks as one of the most dangerous infectious diseases around the world and it is accountable for over 1.5 million deaths every year. World Health Organization has estimated that one fourth of the world’s population is infected with Mycobacterium tuberculosis. The current treatment against TB has drawbacks and the only available vaccine against TB does not provide sufficient protection against the disease and therefore new treatments are much needed. There has also been a lack of good animal models, but the zebrafish (Danio rerio) have been recently found to be a good model to study especially granuloma formation, latency, and reactivation of TB. Their natural pathogen, Mycobacterium marinum causes similar infection in the fish than M. tuberculosis in humans. One characteristic of TB is the formation of granulomas, which are aggregates of immune cells that contain the bacteria. However, M. tuberculosis can escape the granuloma and in such a way spread in the host. The inflammasome is an innate immune system mechanism that activates the immunological response in an infection and has a role in the formation of granulomas. PYCARD is an adaptor protein that has a role in inflammasome activation, which makes it an interesting target when studying the immunological response against M. tuberculosis infection. In this study, granuloma formation in pycard-/- and pycard+/+ zebrafish were compared. The granulomas were studied for their size, location, structure and hypoxicity, and the number of granulomas in each fish was counted. Also, the number of free bacteria was assessed. No significant differences were found in any of these aspects between pycard-/- and pycard+/+ fish. Variation between individual fish was great in both groups.
  • Heine, Sari (Helsingfors universitet, 2014)
    Obesity is a significant problem for public health. Obesity develops when systems controlling food intake and consumption are imbalanced. Many different brain areas and transmitters contribute to maintain energy balance. Signals that are secreted proportional to body's fat storage (leptin and insulin) regulate energy balance in a long run. Hormones that are secreted from gastrointestinal tract control food intake in a short run. These hormones are for example cholecystokinin, peptide YY and ghrelin. Drug treatment for obesity is limited because effective drugs are lacking. The only drug to treat obesity in Europe is orlistat but it's effectiveness is modest. The development for new antiobesity drugs has been busy. Problems in drug development have however delayed drugs in the market. The aim of this study was to develop a method with which we could measure how much food zebrafish (Danio rerio) has been eaten and to study how different drugs affect feeding behavior of the zebrafish. The purpose was also to do high throughput screening of antiobesity drug with this method and to study how genes affect feeding. The amount of food that zebrafish ate was able to be measured by utilizing fluorescent rotifers as fish's food. Drugs that are known to affect feeding (fluoxetine and rimonabant) reduced the amount of food zebrafish ate when measurement was done in 6-well plate and with two hours feeding. Sibutramine did not affect food intake, although it has been shown to reduce food intake in zebrafish in another study. The effect of gene knock down was also studied with morpholino oligonucleotides. MANF, th2 or galanin gene knock down did not affect food intake in zebrafish. The conclusion is that the new method is well suited for food intake measurements and drug effectiveness studies. The method can not be used in high throughput screening because results can not be analyzed by a plate reader and the feeding can not be done in 96-well plate.
  • Wasik, Anita A.; Dash, Surjya N.; Lehtonen, Sanna (2019)
    Septins are a conserved family of GTP-binding proteins that assemble into cytoskeletal filaments to function in a highly sophisticated and physiologically regulated manner. Originally septins were discovered in the budding yeast as membrane-associated filaments that affect cell polarity and cytokinesis. In the last decades, much progress has been made in understanding the biochemical properties and cell biological functions of septins. In line with this, mammalian septins have been shown to be involved in various cellular processes, including regulation of cell polarity, cytoskeletal organization, vesicle trafficking, ciliogenesis, and cell-pathogen interactions. A growing number of studies have shown that septins play important roles in tissue and organ development and physiology; yet, little is known about their role in the kidney. In the following review, we discuss the structure and functions of septins in general and summarize the evidence for their presence and roles in the kidney.
  • Mosselhy, Dina A.; He, Wei; Hynönen, Ulla; Meng, Yaping; Mohammadi, Pezhman; Palva, Airi; Feng, Qingling; Hannula, Simo-Pekka; Nordstrom, Katrina; Linder, Markus B. (2018)
    Introduction: Antibiotic resistance is a growing concern in health care. Methicillin-resistant Staphylococcus aureus (MRSA), forming biofilms, is a common cause of resistant orthopedic implant infections. Gentamicin is a crucial antibiotic preventing orthopedic infections. Silica-gentamicin (SiO2-G) delivery systems have attracted significant interest in preventing the formation of biofilms. However, compelling scientific evidence addressing their efficacy against planktonic MRSA and MRSA biofilms is still lacking, and their safety has not extensively been studied. Materials and methods: In this work, we have investigated the effects of SiO2-G nanohybrids against planktonic MRSA as well as MRSA and Escherichia coli biofilms and then evaluated their toxicity in zebrafish embryos, which are an excellent model for assessing the toxicity of nanotherapeutics. Results: SiO2-G nanohybrids inhibited the growth and killed planktonic MRSA at a minimum concentration of 500 mu g/mL. SiO2-G nanohybrids entirely eradicated E. coli cells in biofilms at a minimum concentration of 250 mu g/mL and utterly deformed their ultrastructure through the deterioration of bacterial shapes and wrinkling of their cell walls. Zebrafish embryos exposed to SiO2-G nanohybrids (500 and 1,000 mu g/mL) showed a nonsignificant increase in mortality rates, 13.4 +/- 9.4 and 15%+/- 7.1%, respectively, mainly detected 24 hours post fertilization (hpf). Frequencies of malformations were significantly different from the control group only 24 hpf at the higher exposure concentration. Conclusion: Collectively, this work provides the first comprehensive in vivo assessment of SiO2-G nanohybrids as a biocompatible drug delivery system and describes the efficacy of SiO2-G nanohybrids in combating planktonic MRSA cells and eradicating E. coli biofilms.
  • Wahab, Awais; Hyytiäinen, Aini; Wahbi, Wafa; Tuomainen, Katja; Tervo, Sanni; Conesa-Zamora, Pablo; Jauhiainen, Laura; Mäkinen, Laura K.; Paavonen, Timo; Toppila-Salmi, Sanna; Salem, Abdelhakim; Almangush, Alhadi; Salo, Tuula; Al-Samadi, Ahmed (2021)
    Fascin 1 plays important pro-metastatic roles in head and neck carcinoma (HNSCC) migration, invasion, and metastasis. However, limited advancement in targeting metastasis remains a major obstacle in improving HNSCC patients' survival. Therefore, we assessed the therapeutic potential of fascin 1 targeted inhibition and its potential prognostic value in HNSCC patients. Using in vitro and in vivo approaches, we investigated the effect of compound G2, a novel fascin 1 inhibitor, on HNSCC cells migration, invasion, and metastasis. High-throughput screening (HTS) was used to assess cytotoxic activity of compound G2 alone or combined with irradiation. We also evaluated the prognostic potential of fascin 1 in HNSCC patients. Interestingly, compound G2 reduced carcinoma cells migration and invasion in vitro and inhibited metastasis in vivo. Moreover, HTS revealed a modest cytotoxic activity of the compound G2 on HNSCC cell lines. Irradiation did not synergistically enhance the compound G2-mediated cytotoxic activity. Survival analyses showed that high fascin 1 immunoexpression, at the tumor invasive front, was associated with cancer-specific mortality in the advanced stages of HNSCC. Collectively, our findings suggest that fascin 1 represents a promising anti-metastatic therapeutic target and a useful prognostic marker in patients with HNSCC. Novel anti-metastatic agents could provide a valuable addition to cancer therapy.
  • Chalas, Petros (Helsingin yliopisto, 2020)
    Histamine and hypocretin/orexin are neuromodulators important for regulation of alertness and wakefulness. These systems project to major areas of the brain, are highly conserved among vertebrates and they significantly innervate each other. Different studies have indicated an interaction between the histaminergic and orexin systems, however the role of histamine in this interaction is still not well-established. The goal of this study was to examine possible changes in orexin neurons development and larvae behaviour, after genetic loss of histamine decarboxylase (hdc), the histamine-synthesizing enzyme. Using whole-mount in-situ hybridization and immunofluorescence staining we observed a significant reduction in the expression of the hcrt mRNA and the orexin A peptide in 6 dpf hdcKO zebrafish larvae. However, KO of hdc had no effect on startle response, dark flash response and sleeping behaviour of 6 dpf larvae. To further investigate the regulatory role of the histaminergic system, we employed treatment of hdcWT and KO larvae with ciproxifan, a histamine H3 receptor inverse agonist. Ciproxifan treatment increased darkness habituation in 7 dpf hdcWT and KO larvae but reduced the intensity of the dark flash response only on hdcWT larvae. Furthermore, ciproxifan treatment differentially affected the expression of the orexin A peptide in 7 dpf hdcWT and KO larvae but had no effect on the expression levels of the hcrt mRNA. Collectively, these findings suggest the significance of histaminergic signaling for normal development of orexin neurons and the implication of histamine in the execution of the dark flash response. Lastly, this study indicates the complex role of the histamine H3 receptor and the requirement of further studies for better characterization of its function.
  • Marcello, Matteo; Cetrangolo, Viviana; Savarese, Marco; Udd, Bjarne (2022)
    In recent years, increasing attention has been paid to titin (TTN) and its mutations. Heterozygous TTN truncating variants (TTNtv) increase the risk of a cardiomyopathy. At the same time, TTNtv and few missense variants have been identified in patients with mainly recessive skeletal muscle diseases. The pathogenic mechanisms underlying titin-related diseases are still partly unknown. Similarly, the titin mechanical and functional role in the muscle contraction are far from being exhaustively clarified. In the last few years, several animal models carrying variants in the titin gene have been developed and characterized to study the structural and mechanical properties of specific titin domains or to mimic patients' mutations. This review describes the main animal models so far characterized, including eight mice models and three fish models (Medaka and Zebrafish) and discusses the useful insights provided by a thorough characterization of the cell-, tissue- and organism-phenotypes in these models.
  • Valle, Jenni (Helsingfors universitet, 2018)
    Gut inflammation and permeability is speculated to play a major role in the pathophysiology of several human diseases. Signs of a low-grade gut inflammation in patients with type 1 diabetes (T1D) have been found. Focus of this study was to understand the role of gut inflammation and increased gut permeability in the development of diabetic complications, especially nephropathy. Approximately, one-third of Finnish patients with T1D develop kidney disease during their lifetime. Inflammatory mechanisms may have an essential role in the pathophysiology of the disease. Lipopolysaccharide, LPS, is found in the outer membrane of gram-negative bacteria. LPS activates innate immune system and triggers the activation of inflammatory cytokines, neutrophils and macrophages as well as many pathophysiological processes in vivo, for instance fever and endotoxic shock. Aim of this study was to establish a zebrafish gut inflammation model using fluorophore conjugated endotoxin, LPS. We hypothesized that delivery of LPS in addition to EDTA in the gut of zebrafish triggers inflammation and increased gut permeability which may lead to leakage of LPS to blood stream and potentially kidney injury. This novel zebrafish inflammation model could possibly be used for studying the pathophysiological mechanisms of gut inflammation and possible kidney injury as well as for screening new anti-inflammatory drugs. In addition, this animal model can be used for studying intestinal alkaline phosphatase (IAP) in reducing gut permeability and LPS-mediated kidney damage. IAP is an enzyme produced in small-intestinal epithelium. IAP can detoxify several bacterial endotoxins including LPS and thus protect against the induction of intestinal inflammation. LPS and EDTA were delivered in the gut of 6 days old zebrafish larvae using microgavage injection. Fluorescence microscopy imaging of live zebrafish enabled following the same individual at different timepoints after injections. Paraffin sectioning of the small larvae was promising for investigating the morphology and permeability of the gut as well as possible immunostaining for detection of IAP. L-phenylalanine was used for inhibition of IAP enzyme. Using the novel method of microinjection to gut on zebrafish larvae the timing and amount of delivered materials to gut can be controlled well. The anatomy and function of the gut in zebrafish is very similar to small intestine of mammals and the highly developed vertebrate immune system makes zebrafish an interesting model organism for studying gut inflammation and permeability. In addition, inflammatory processes can be visualized in live, intact transparent zebrafish larvae. However, the technique has a lot of challenges including small size of the fish and possible tissue damage of the fish while performing injection. More experiments need to be carried out to establish the model for drug screening. Also, along with microscopy images, a more precise way for quantification the gut permeability is needed. Based on the images it’s not yet possible to conclude whether LPS increased gut permeability or if IAP inhibition with L-phenylalanine worked in zebrafish larvae. Using adult zebrafish in the future will give more information about the chronic gut inflammation and development of possible kidney injury.
  • Narumanchi, Suneeta; Wang, Hong; Perttunen, Sanni; Tikkanen, Ilkka; Lakkisto, Päivi; Paavola, Jere (2021)
    Heart failure causes significant morbidity and mortality worldwide. The understanding of heart failure pathomechanisms and options for treatment remain incomplete. Zebrafish has proven useful for modeling human heart diseases due to similarity of zebrafish and mammalian hearts, fast easily tractable development, and readily available genetic methods. Embryonic cardiac development is rapid and cardiac function is easy to observe and quantify. Reverse genetics, by using morpholinos and CRISPR-Cas9 to modulate gene function, make zebrafish a primary animal model for in vivo studies of candidate genes. Zebrafish are able to effectively regenerate their hearts following injury. However, less attention has been given to using zebrafish models to increase understanding of heart failure and cardiac remodeling, including cardiac hypertrophy and hyperplasia. Here we discuss using zebrafish to study heart failure and cardiac remodeling, and review zebrafish genetic, drug-induced and other heart failure models, discussing the advantages and weaknesses of using zebrafish to model human heart disease. Using zebrafish models will lead to insights on the pathomechanisms of heart failure, with the aim to ultimately provide novel therapies for the prevention and treatment of heart failure.
  • Yli-Rantala, Anni (Helsingfors universitet, 2014)
    Zebrafish (Danio rerio) is a vertebrate model organism. It is suited for many phases of drug development process like toxicological studies. The major advantage of using zebrafish is the possibility to conduct high-throughput screens on a whole vertebrate animal. However, there is not as much knowledge about zebrafish as there is about other model organisms. Therefore there might be differences between zebrafish and humans that affect the use of zebrafish as a model in the drug development process. The purpose of this thesis was to characterize the structure of the zebrafish oxytocin system and assess the role of oxytocin on zebrafish behaviour. In humans defects in the oxytocin system have been linked to many psychiatric disorders like autism. If the mammalian and zebrafish oxytocin systems resembled each other functionally and structurally, it would enable the use of zebrafish as a model when studying the role of oxytocin in pathophysiology of diseases and also in oxytocin system related drug development. The structure and development of zebrafish oxytocin system was studied by staining adult zebrafish brain cryosections and larval brains with antibodies made against mammalian oxytocin. The specificity of the antibodies to recognize zebrafish oxytocin was determined by absorption and cross-reactivity controls. The role of oxytocin on zebrafish locomotion was studied by inhibiting the splicing of oxytocin messenger RNA with morpholino oligonucleotides (MOs). The MOs were used to address the relevance of the model in pharmacology, since the zebrafish oxytocin receptors have not been expressed and pharmacologically characterized. In zebrafish oxytocin was produced in the cells of the preoptic nucleus. There were thick oxytocin fibers towards the pituitary and also thinner fibers into areas in the telencephalon, diencephalon, mesencephalon and rhombencephalon. One of the MOs was able to inhibit the production of oxytocin with a dose that did not cause morphological abnormalities. The MO reduced the locomotor activity of the fish, but the specificity of the MO has to be determined. The structure of the zebrafish oxytocin system resembles mammalian oxytocin system in terms of the location of oxytocin cells and fiber projections. Therefore zebrafish seems a suitable model organism for oxytocin research. However, the structure of the zebrafish oxytocin receptor system and the effect of oxytocin on other behavioural aspects have to be determined in order to further evaluate the applicability of zebrafish for oxytocin research.