Richard O. Bennett

Comparison of trout hepatocyte culture on different substrates

SummaryComparisons were made of attachment and viability of rainbow trout (Salmo gairdneri) hepatocytes in short-term (2 days), primary culture on plastic, collagen-coated or extracellular matrix (ECM) coated dishes. Hepatocyte isolation routinely yielded cells with good viability (96%). Cells plated on ECM attached with high efficiency (93%) in contrast to cells cultured on plastic or collagen (∼20%). The cells plated on ECM flattened out and formed monolayers, while the cells on plastic and collagen rounded up and formed multi-cell aggregates in suspension. Viability of cells in all substrates remained high over the 2 day culture period. ECM is the first substrate to support trout-hepatocyte attachment in primary culture. Differentiated liver function was maintained in cells cultured on ECM as evidence by the induction of tyrosine aminotransferase by hydrocortisone (200%).

Reproduction of a Domestic Striped Bass Brood Stock

Abstract Fingerlings of striped bass (Morone saxatilis) were reared to sexual maturity in tanks, during which time they were fed only commercial trout and salmon diets. Spawning trials were conducted with two of the 6-year-old domestic females. They ovulated after being injected with 330 IU of human chorionic gonadotropin (HCG) per kilogram of body weight, and their eggs were manually stripped and fertilized with the milt from four HCG-injected males (150 IU/kg body weight). Approximately 41% of the eggs were fertilized. Aside from accidental losses or deliberate cropping of the population, no significant mortality of the progeny was observed after they hatched. The larvae were fed live brine shrimp (Artemia sp.) for 30 d after hatching and then adapted to commercial salmon or trout diets. Several hundred of these F1 domestic brood stock have been reared for 3 years in intensive culture and most of the males are now sexually mature. These results conclusively demonstrate the viability of the progeny of do...

Communications: A Classification System for Histological Lesions

Abstract This paper presents a system for classifying and coding histological data from fish and selected invertebrate species. These codes can be readily entered into a computerized spreadsheet and subsequently imported into statistical software programs. Use of this system can reduce time spent taking notes at the microscope and facilitate data analysis.

Technical Notes: Noninduced Spawning of Captive Striped Bass in Tanks

Abstract Captive striped bass (Morone saxatilis) raised as brood stock (1983 year-class; Chesapeake Bay origin) were examined for ability to spawn in tanks. Three females, one of which did not receive hormone treatments, spawned. This is the first non-hormonally induced spawning in tanks for striped bass raised in captivity.

Renal histopathological changes in the goldfish (Carassius auratus) after sublethal exposure to hexachlorobutadiene

Abstract Hexachlorobutadiene (HCBD), a chlorinated hydrocarbon, is an acute renal toxicant in mammals. Goldfish (Carassius auratus) were given a single i.p. injection of a sublethal dose (500 mg/kg) of HCBD and sampled daily for one week. No damage was observed by light microscopy 6 h post injection. At 24 h, however, cytoplasmic vacuolation and necrosis occurred in the renal tubules. This damage was localized to the epithelium of the second (P2) and third (P3) segments of the proximal tubule. The damage persisted for seven days. By the sixth day the first segment (P1) of the proximal tubule had small cytoplasmic vacuoles. The ratio of kidney to body weight was significantly greater in the treated fish on the fourth day. Gamma glutamyl transpeptidase (GGT), a histochemical marker of proximal tubule brush border in mammals, was demonstrated in the goldfish kidney. Intense staining was noted only in P2 and P3. GGT staining was also present in the lumen of the damaged, vacuolated tubules of HCBD-treated fish.

Effect of Hardness and Salinity on Survival of Striped Bass Larvae

Abstract Larval striped bass Morone saxatilis were exposed to three hardness (40, 100, and 160 mg/L as CaCO3 equivalents) and two NaCl salinity (2.0 and 3.0‰) treatments for 10 d in a modified flow-through system. Salinity had a greater effect on larval survival than did hardness over the ranges tested. Elevated NaCl salinity appeared to be detrimental; larvae exposed to 3.0‰ NaCl had significantly higher mortality than did those exposed to 2.0‰ NaCl. At 2.0‰ salinity, hardness does not appear to play an important role in larval survival (probability of survival > 0.70). At 3.0‰ salinity, mortality was greatest at hardness levels of 40 and 100 mg/L (probability of survival = 0.06 and 0.01, respectively), whereas at 160 mg/L, mortality was reduced (probability of survival = 0.39). The reason for this response is not clear, although there may be an optimal ratio of different ions contributing to total salinity. By comparison, other studies in which diluted seawater was used indicated that salinities of 0.5-...

Necropsy Examination of Fish

Necropsy examination of moribund or dead specimens is an essential step in diagnosing fish diseases. This article discusses basic anatomy and necropsy procedures. A large part of the article has been devoted to methods of procuring samples for laboratory analysis and histologic examination. To determine which findings are re_sponsible for the mortalities, the entire case history and gross necropsy findings must be reviewed. Careful observations made during the necropsy examination provide valuable information immediately, as well as later on in the interpretation oflaboratory data.

Retinoblastoma in a porkfish (Anisotremus virginicus, Linnaeus) and a brown bullhead (Ictalurus nebulosus, Lesueur)

Two cases of retinoblastoma in fish are described. The neoplasms occurred in a porkfish (Anisotremus virginicus, Linnaeus) and in a brown bullhead (Ictalurus nebulosus, Lesueur).

Ultrastructural Injury and Regeneration in the Goldfish Nephron following Sublethal Exposure to Hexachlorobutadiene

Abstract The ultrastructure of the damaged and regenerating renal epithelium of goldfish Carassius auratus exposed to hexachlorobutadiene (HCBD) was examined. As in mammals, the target organelles for HCBD-induced nephrotoxicity are the mitochondria. Extensively swollen mitochondria appeared in proximal segments P2 and P3 within 12 h of HCBD exposure. By 1 week, swollen mitochondria were also present in P 1 epithelial cells. Initially, regenerating epithelial cells in the injured nephrons appeared insensitive to the toxicity. Once they developed more differentiated characteristics, they also developed swollen mitochondria. Newly formed developing nephrons appeared several weeks following toxicant exposure. These also appeared resistant to the toxicity until they became more differentiated. The inhibitor aminooxyacetic acid protected the epithelium from the toxicity, indicating a possible role for cysteine-conjugate β-lyase in the bioactivation of HCBD metabolites in the goldfish.

A dosing system to vary pH, salinity and temperature

Abstract Construction of a dosing system to expose small aquatic organisms to varying pH and salinity under different temperature regimes is discussed. The design allows for three controlled pH levels and two salinity levels across three temperature regimes. The system is flexible and may be adapted for other experimental paradigms including pH depression, elevation or maintenance as well as use with various dilution media or “toxicants” other than salt.