: Recent evidence has shown that fish have the ability to develop new nephrons following renal injury. This study evaluated the usefulness of quantifying developing nephrons in mature fish as an ecotoxicological assessment tool. Histological sections of kidney were prepared from Atlantic tomcod and brown bullhead specimens collected from reference and contaminated streams. The numbers of developing nephrons and basophilic cell clusters from which the nephrons arise per section area were determined by image analysis. The numbers of basophilic clusters and developing nephrons in tomcod kidney were found to be one to two orders of magnitude higher than for the bullhead. In tomcod from the Hudson River, the number of both basophilic clusters and developing nephrons were elevated relative to samples from the less contaminated Saco and Royal Rivers. In bullheads, when analysis was conducted over several seasons, the number of basophilic clusters and developing nephrons from Cuyahoga River samples were elevated relative to samples from the less-contaminated Old Women Creek and Toussaint River. Developing nephrons and basophilic clusters seem to have potential as general indicators of ecological condition, but may be better suited for detection of nephrotoxicity at specific sites.
By their effects on equilibrium potentials, water currents produced by respiratory and other movements of freely‐moving animals cause changes in the potential difference between stainless steel electrodes set at opposite ends of an open system continuous‐flow animal chamber. The changes are in the microvolt range, but they can be used for continuous or intermittent recording of the animalˈs responses in short‐term or long‐term studies under widely varied environmental conditions, and the method seems suitable for monitoring.
We report the rare, natural occurrence of triploidy in a brown bullhead Ameiurus (formerly Ictalurus) nebulosus. This is to our knowledge the first report of naturally occurring triploidy within the family Ictaluridae. The nuclei of blood cells were studied by flow cytometry, volume measurement, and computer‐assisted image analysis. The triploid had a genome size of 3.29 pg DNA/cell compared to 2.23 pg DNA/cell (SD, 0.02 pg) for 28 diploid brown bullheads. Volume measurement and image analysis were able to detect the triploid condition; however, flow cytometry was the most precise technique and had the greatest resolution.
Fertile sea urchins were maintained over six months in three commercial artificial seawaters (Forty Fathoms@, HW Marinemix@, and Instant Ocean@). Fertilization tests using the reference toxicants copper (Cu) and sodium dodecyl sulfate (SDS) were conducted with the sea urchins in the artificial sea salt in which the organisms were maintained. The ranges of Cu and SDS noobserved-effect concentrations (NOECs) for the tests in the three artificial seawaters overlapped one another and also the ranges of published results for animals maintained and tested in natural seawater. The 50% effect concentration (EC50) values of Cu for the tests using the three artificial seawaters were not significantly different. The EC5O value for SDS using HW Marinemix was significantly lower than values for tests using the other artificial seawaters. The artificial seawaters were judged acceptable for maintaining Arbacia punctulata and conducting fertilization tests, although additional research is required to optimize long-term maintenance of fertile animals.
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