PubMed Health⌕ Search

SEARCH · PubMed Health

Results for “Killifishes”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 19 recordsLinked to original sources
PubMed2026

Anoxia tolerant DNA replication is supported by ATR kinase in the annual killifish Austrofundulus limnaeus.

Hypoxia and anoxia suppress cell proliferation due to an increase in replication stress and activation of DNA damage checkpoints. Embryos of the annual killifish Austrofundulus limnaeus tolerate prolonged anoxia, indicating improved genomic stability under oxygen starvation. We investigated the cell cycle regulation of the anoxia tolerant killifish embryonic cell line PSU-AL-WS40NE during anoxia. Live-cell imaging confirms continued proliferation of WS40NE cells for the first 24 h of anoxia with minimal cell death. Fluorescence imaging shows that cells accumulate in G1 after the first day in anoxia with a rapid entry into S phase upon reoxygenation. Pharmacological inhibition shows a reliance on ataxia telangiectasia and Rad3 related (ATR) signaling, suggesting that increased γH2AX levels are driven by replication stress instead of DNA damage. This conclusion is supported by a lack of induction of a G2 checkpoint, suggesting minimal DNA damage during anoxic exposure. Maintaining cellular proliferation during anoxia and accumulating cells in the G1 phase for extended anoxic exposure is likely one way that embryos of the killifish can survive prolonged anoxia, which provides insight into mechanisms that enable cells to proliferate under metabolic stress.

Animals↗
PubMed1977

Rapid modulation of gill Na+ + K+-dependent ATPase activity during acclimation of the killifish Fundulus heteroclitus to salinity change.

The enzymatic properties of membrane-bound Na+ + K+-ATPase from gills of killifish acclimated to fresh water, to 16% sea water, or to 30% sea water appear to be identical, indicating that the same enzyme may function to absorb Na+ in low salinities and excrete Na+ at the gills in high salinities. Ammonium ion is an effective substitute for K+: in the ATPase reaction itself, in blocking phosphorylation of the ATPase protein, and in inhibiting the binding of ouabain to the enzyme. The specific activities of the Na+ + K+-ATPase in the three different salinities are consistent with the expected Na+ pumping rates: higher in fresh water and 30% sea water than in 16% sea water. Within one-half hour after transfer of killifish from one salinity to another, gill Na+ + K+-ATPase activities reach equilibrium levels. The rapid increase in Na+ + K+-ATPase activity in gill microsomes of fish acclimating from fresh water to 30% sea water is accompanied by a slow decrease in the number of binding sites for ouabain, supporting the idea that acclimation to short-term salinity changes may involve modifications in the catalytic rate rather than the number of Na+ + K+-ATPase molecules.

Acclimatization↗
PubMed2026

Review: The African turquoise killifish as a model for the integrative physiology of vertebrate aging.

With increasing emphasis on extending healthy lifespan, aging research requires vertebrate models that permit efficient mechanistic investigation and intervention testing within practical time and cost constraints. The African turquoise killifish (Nothobranchius furzeri) has attracted growing attention because it combines an exceptionally short life cycle with an intact vertebrate physiological context and an expanding genetic toolkit, enabling relatively rapid evaluation of candidate aging interventions and mechanistic analysis across molecular, tissue, and organismal levels. This review assesses N. furzeri from an integrative-physiology perspective, focusing on germline-soma interactions, gut microbiota-host crosstalk, nutrient sensing and metabolic remodeling, temperature responsiveness, and AMPK-mTOR-linked programs. It also examines expanding genome-engineering and reporter approaches that support mechanistic and tissue-resolved investigation of these physiological processes. Building on recent reviews of killifish biology, disease modeling, regeneration, and the hallmarks of aging, we synthesize evidence across major intervention domains, distinguish established phenotypic effects from incompletely resolved mechanisms, and highlight functional endpoints, methodological standardization, and the appropriate interpretation of the model's translational relevance. Together, these features position N. furzeri as a strategically useful vertebrate platform for rapid mechanistic testing, intervention evaluation, and prioritization of aging-related pathways. Future progress will require improved methodological standardization, tissue-resolved causal studies, and question-driven cross-species validation where appropriate.

Animals↗
PubMed1977

Methylmercury teratogenesis in the killifish, Fundulus heteroclitus.

Exposure of developing eggs of the killifish, Fundulus heteroclitus, to 0.03 or 0.04 mg/l of methylmercuric chloride resulted in a variety of abnormalities. Percentage of axis formation was reduced somewhat, and many embryos developed cyclopia or intermediate conditions leading to cyclopia, reflecting interference with induction of the forebrain. Defects in the cardiovascular system also appeared in the form of failure of the heart to differentiate properly into chambers. The heart was a thin, feebly beating tube, incapable of causing the blood to circulate. Other tissues, however, continued developing fairly normally, and embryos showed spontaneous movement comparable to controls. Embryos with severe cardiovascular or optic defects did not hatch. Upon hatching, some embryos which had previously appeared normal were found to have skeletal malformations in the form of vertebral bends or the inability to uncurl from the position which they had while still inside the chorion. Exposure to the toxicant for shorter periods of time (6, 12, or 24 hours) reduced the incidence of abnormalities. The second day of development was found to be the most sensitive period.

Abnormalities, Drug-Induced↗
PubMed2025

Altered translation elongation contributes to key hallmarks of aging in the killifish brain.

Aging is a major risk factor for neurodegeneration and is characterized by diverse cellular and molecular hallmarks. To understand the origin of these hallmarks, we studied the effects of aging on the transcriptome, translatome, and proteome in the brain of short-lived killifish. We identified a cascade of events in which aberrant translation pausing led to altered abundance of proteins independently of transcriptional regulation. In particular, aging caused increased ribosome stalling and widespread depletion of proteins enriched in basic amino acids. These findings uncover a potential vulnerable point in the aging brain's biology-the biogenesis of basic DNA and RNA binding proteins. This vulnerability may represent a unifying principle that connects various aging hallmarks, encompassing genome integrity, proteostasis, and the biosynthesis of macromolecules.

Animals↗
PubMed1979

Pathways of cycloleucine transport in killifish small intestine.

By using blocking concentrations of competitors, i.e., concentrations of other neutral amino acids that cause maximal inhibition, cycloleucine transport into slices or everted sacs of killifish (fundulus heteroclitus) small intestine could be partitioned into three pathways. One is apparently not mediated, a second is inhibited by all neutral amino acids tested (component 1), and a third, is inhibited by alpha-aminocarboxylic acids (component 2), but not by beta-alanine or taurine. Both mediated pathways were Na dependent, and each yielded a linear double reciprocal plot of initial slice uptake vs. cycloleucine concentration. Apparent Kt and Vmax values for component 1 were 0.03 mM and 33 pmol/mg tissue per 3 min, respectively; corresponding values for component 2 were 0.12 mM and 28 pmol/mg tissue per 3 min. Additional experiments with an intestinal brush border membrane vesicle preparation indicate that these mediated components reflect true differences in carrier specificity rather than the differential effects of inhibitors on metabolism or on the Na gradient that drives cycloleucine transport.

Amino Acids↗
PubMed1979

A new and unusual eimerian (protozoa: Eimeriidae) from the liver of the Gulf killifish, Fundulus grandis.

Oocysts and sporocysts of Eimeria funduli sp. n. are described from the Gulf killifish, Fundulus grandis, on the basis of light microscopy, transmission and scanning electron miscroscopy, and location in the liver of infected hosts. The spherical sporulated oocysts of E. funduli isolated from liver tissue measure 20-31 (25) micrometer across with ovoid sporocysts 9-11 X 5-7 (10 X 6) micrometer. A micropyle, polar granule, and oocyst residuum are absent, but sporocysts have Stieda and substieda bodies, a few residual granules, and 10-25 (15) unique projecting structures with expanded distal portions that we term "sporopodia". Sporopodia 1-3 (2) micrometer high support a transparent membrane that completely surrounds the sporocyst. Sporozoites have one large posterior refractile body. Ultrastructurally, the oocyst wall consists of two thin layers of granular material: an electron-dense outer layer with a rough external surface and an electron-lucent inner one of approximately equal thickness. One or two unit membranes line the inner surface of the inner layer. Each layer is 40-60 (55) nm thick. The sporocyst wall, 78-130 (110) nm thick, consists of an electron-lucent material with the outer surface being more electron dense and giving rise to osmiophilic sporopodia; closely associated with these and the outer surface are one or two unit membranes. A thin osmiophilic layer of fine granular material lines the inner surface.

Animals↗
PubMed1978

Hemoglobins of the killifish Fundulus heteroclitus. Separation, characterization, and a model for the subunit compositions.

Polyacrylamide and starch gel electrophoresis of the hemoglobin of the killifish Fundulus heteroclitus reveal the presence of four clearly distinguishable components. These isohemoglobins, each tetramers consisting of alpha and beta chains, can be preparatively separated by ion exchange chromatography on DEAE-cellulose and are homogeneous according to isoelectric focusing in polyacrylamide gels. Oxygen equilibria of the isolated hemoglobin components (Hb I, Hb II, Hb III, and Hb IV) show only minor differences in the magnitude of the Bohr effect and in the effect of ATP on the binding of oxygen. Four different globin chains, alphaa, alphab, betaa, and betab, can be separated by ion exchange on CM-cellulose. Hb I is a homotetramer of alphab and betab chains, Hb IV consists of alphaa and betaa subunits, and components II and III are heterotetramers consisting of all four chains. The alpha and beta chains differ significantly in amino acid composition. A model suggesting the existence of 10 different isohemoglobins, 6 of which have stable intersubunit contacts, has been proposed to account for the qualitative and quantitative aspects of the electrophoretic behavior of the components. Separations of the isohemoglobins on DEAE-cellulose under slightly modified conditions provide additional support for the model.

Amino Acids↗
PubMed1979

The effects of hypophysectomy on the retinomotor responses of the killifish, Fundulus heteroclitus.

This paper presents the results of an investigation concerned with the effects of long-term hypophysectomy on the retinomotor responses of the euryhaline killifish, Fundulus heteroclitus: 1. The eye of hypophysectomised Fundulus heteroclitus responds to light and dark in the same manner as that of intact controls: the retina is not in a state of permanent light-adaptation as claimed by Vilter (1942) for the hypophysectomised eel. 2. There is no evidence of a persistent circadian rhythm during continous darkness. 3. Unilateral illumination of the eye of intact fish results in dispersion of retinal pigment in both illuminated and unilluminated eyes, as in the goldfish (Ali, 1964), but no such contralateral response was evident after hypophysectomy. The cones are unresponsive.

Adaptation, Physiological↗
PubMed2024

Detection of mitochondrial tDRs in killifish embryos and other non-model organisms.

In recent years a diversity of small noncoding RNAs have been identified that originate from the mitochondrial genome. These mitosRNAs are often dominated by tRNA-derived small RNAs (mito-tDRs). Differential expression of mito-tDRs is associated with responses to stress. They also appear to be expressed differentially during development and their expression may be enriched in stress-tolerant animals. Very little is currently known about roles or modes of action of these sequences, although they are implicated in a diversity of processes such as cell cycle regulation, mRNA stability, regulation of ROS production, and import of proteins into the mitochondrion. To better understand the various roles these sequences may play, it is critical that we understand their diversity, cellular location, and the context for their expression. This protocol outlines the methodologies used to detect mitosRNAs, including mito-tDRs, in embryos and cells of the annual killifish Austrofundulus limnaeus. We highlight critical steps in the isolation of RNA, creation of sequencing libraries, bioinformatics processing of sequence data, and methods for validation of expression that support a robust discovery pipeline for mitosRNAs even from species with incomplete reference genome sequences.

Animals↗
PubMed1976

Teleost chloride cell. II. Autoradiographic localization of gill Na,K-ATPase in killifish Fundulus heteroclitus adapted to low and high salinity environments.

The specific binding and inhibitory action of (3H)ouabain were employed to localize transport Na,K-ATPase in the euryhaline teleost gill, a NaCl-transporting osmoregulatory tissue in which both enzyme activity and transepithelial transport vary with environmental salinity. In killifish fully adapted to 10%, 100%, or 200% seawater, the gills were internally perfused and externally irrigated in situ. After suitable internal or external exposure to (3H)ouabain, individual gill arches were excised for Na,K-ATPase assay, measurement of radiolabel binding, or quantitative high-resolution autoradiography. Internal exposure to 50 muM ouabain resulted in essentially complete enzyme inhibition, and binding paralleled the increases in enzyme activity at higher salinities; in contrast, external exposure gave minimal and erratic results consistent with leakage of external ouabain into interstitial fluid. (3H)Ouabain autoradiographs demonstrated that, irrespective of exposure or salinity, most of the gill binding was associated with chloride cell. These cells increased in size and number with salinity and, at the subcellular level, the distribution pattern for bound ouabain was always identical to that for the amplified basal-lateral (tubular system) membrane. The combined physiologicmorphologic results constitute final direct proof that chloride cells are the primary site of gill Na,K-ATPase. More important, they provide convincing evidence for unexpected increases in basal-lateral enzyme at higher salinities and thus raise a fundamental objection to the long-postulated role of the Na pump in secretory NaCl transport.

Adenosine Triphosphatases↗
PubMed2025

Global maintenance of histone post-translational modifications during the transition into anoxia in embryos of the annual killifish Austrofundulus limnaeus.

Many organisms have adapted to survive anoxic or hypoxic environments, but the epigenetic responses involved in this successful stress response are not well described in most species. Embryos of the annual killifish Austrofundulus limnaeus have the greatest tolerance to anoxia of all vertebrates, making them a powerful model to study the cellular mechanisms necessary for anoxia tolerance. However, the global histone landscape of this species has never been quantified or explored in relation to stress tolerance. Liquid chromatography-mass spectrometry and a Python bioinformatics workflow were used to identify histones and their post-translational modifications. This pipeline resulted in the detection of 252 unique biologically relevant histone post-translational modifications (hPTMs) (unimod + residue). These PTMs represent 16 types of biologically relevant hPTMs present during both anoxia and normoxia in Wourms' stage 36 embryos. This hPTM library presents an exciting opportunity to study histone modifications across development and in response to environmental stressors. No significant changes in PTM or histone abundance were observed between anoxic and normoxic embryos, suggesting that 24 h of anoxia is not sufficient to induce epigenetic or histone isoform changes at the organismal level. This result is inconsistent with data presented for similar stresses in mammalian cells and thus stabilization of the hPTM landscape may be an adaptation that supports anoxia tolerance.

anoxia↗
PubMed1978

Effect of prehatching weightlessness on adult fish behavior in dynamic environments.

At 16-17 months of age, three groups of fish from the embryonated eggs in the ASTP killifish experiment were subjected to postflight tests consisting of rapidly changing environments. It was found that the group of fish with the least amount of development at orbital insertion (A-32) had a decreased rheotropism for both the moving background and the rotating water current tests when compared to ground control fish. Exposure to parabolic aircraft flight conditions revealed that the A-32 fish were less disoriented during zero gravity periods and were hypersensitive to high-gravity periods. These results suggested a modified vestibular competency due to a 9-d prehatching weightlessness exposure.

Adaptation, Physiological↗
PubMed2026

Evolutionary Reorganization of Transcriptomic Architecture Across a UVB Tolerance Gradient in Fish.

Environmental stressors such as ultraviolet radiation impose strong selective pressures on organisms, yet how adaptation to such stressors shapes transcriptomic responses at the network level remains poorly understood. Although stratospheric ozone is recovering globally, substantial regional variation in UV exposure persists, particularly in high-altitude environments where extreme UV levels can occur. Here, we compared three fish models representing distinct biological responses to UVB exposure: wild-type zebrafish (Danio rerio), a melanin-deficient zebrafish mutant (nacre) lacking a major protective mechanism against UVB damage, and the high-altitude Andean killifish Orestias ascotanensis, a species naturally exposed to extreme UVB radiation. Together, these models define a gradient spanning physiological protection, impaired protection, and evolutionary adaptation to UVB stress. Using RNA-seq and protein-protein interaction networks, we show that transcriptomic responses differ markedly across this gradient. Wild-type and nacre zebrafish exhibited relatively limited transcriptomic changes (∼2%-2.4% of genes changing), whereas O. ascotanensis displayed a large-scale and highly coordinated response (∼21.6% of genes changing) characterized by functionally specialized networks enriched in DNA repair pathways. These differences involved not only transcriptomic magnitude but also marked reorganization of transcriptomic architecture. Integration with positive selection analyses revealed that positively selected genes were concentrated within highly interconnected regions of transcriptomic networks, consistent with adaptation involving network reorganization. Furthermore, ortholog-based analyses suggest that adaptive responses involve differential reorganization of a conserved functional background. Together, our results support a model in which adaptation to environmental stress is associated with the reorganization of conserved transcriptomic networks across physiological and evolutionary contexts, providing a systems-level perspective on the molecular basis of adaptation.

UVB radiation↗