Three wild caught killifish (Fundulus heteroclitus) on an Institutional Animal Care and Use Committee-approved protocol were found dead within 2 days after being received. The fish were housed in two separate aquaria. Aquarium water was evaluated, and pH, salinity, ammonia, nitrate, and nitrite levels were within acceptable parameters. Several remaining fish appeared to be slow-moving and were presented for necropsy. Multiple, scattered, ulcerated skin lesions (diameter, 1 to 5 mm) were noted at necropsy and were cultured. No pathogenic bacteria were isolated. Wet-mount samples of the gills revealed multiple cysts at the gill margins, each containing a motile organism. No other gill parasites were detected. A diagnosis of trematodiasis was made. The cysts were identified as encysted metacercariae of a digenetic trematode. We surmise that the large numbers of gill flukes combined with the stress of recent shipment likely caused the observed morbidity and mortality.
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Although sex determination is a fundamental process in vertebrate development, it is very plastic. Diverse genes became major sex determinants in teleost fishes. Deciphering how individual sex-determining genes orchestrate sex determination can reveal new actors in sexual development.
View Article and Find Full Text PDFBMC Ecol Evol
January 2025
Leibniz Institute on Aging, Jena, Germany.
Maximizing the life-long reproductive output would lead to the prediction that short-lived and fast aging species would undergo no - if any - reproductive senescence. Turquoise killifish (Nothobranchius furzeri) are naturally short-lived teleosts, and undergo extensive somatic aging, characterized by molecular, cellular, and organ dysfunction following the onset of sexual maturation. Here, we tested whether naturally short-lived and fast aging male turquoise killifish maximize reproduction and display minimal - if any, reproductive senescence.
View Article and Find Full Text PDFBiol Open
January 2025
Biology Department, Woods Hole Oceanographic Institution, Woods Hole, MA 02543,USA.
Coastal fish populations are threatened by multiple anthropogenic impacts, including the accumulation of industrial contaminants and the increasing frequency of hypoxia. Some populations of the Atlantic killifish (Fundulus heteroclitus), like those in New Bedford Harbor (NBH), Massachusetts, USA, have evolved a resistance to dioxin-like polychlorinated biphenyls (PCBs) that may influence their ability to cope with secondary stressors. To address this question, we compared hepatic gene expression and DNA methylation patterns in response to mild or severe hypoxia in killifish from NBH and Scorton Creek (SC), a reference population from a relatively pristine environment.
View Article and Find Full Text PDFEvolution
December 2024
Dept. of Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA.
Hybrid zones provide valuable opportunities to interrogate the processes that drive speciation. In a new study, Hardy et al. (2024) demonstrate that the dominant vegetation type in patchy cordgrass salt marshes and mangrove swamps drives a mosaic hybrid zone between two species of killifish.
View Article and Find Full Text PDFChemosphere
November 2024
University of Monastir, Institute of Biotechnology, LR11ES41 Laboratory, 5000, Monastir, Tunisia. Electronic address:
Estuaries and lagoons are characterized by fluctuating salinity and significant amounts of microplastics (MPs) and are increasingly subjected to various anthropogenic pressures. We investigated whether the accumulation of MPs in the gills of fish inhabiting these fragile ecosystems alters osmoregulation and, consequently, their ability to tolerate fluctuating salinity. The effects of a 15-day exposure to an environmentally relevant concentration (20 μg/L) of spherical polystyrene microplastics (PS-MPs) with a diameter of 5 μm were assessed in the Mediterranean killifish Aphanius fasciatus, focusing on tissue and gene expression changes related to factors of paracellular and transcellular permeability of the gill epithelium during the transition from seawater to freshwater.
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