Amyloodinium ocellatum (Brown, 1931) (Dinoflagellida) infestations in cultured marine fish at Eilat, Red Sea: epizootiology and pathology

Abstract. Since 1977, repeated outbreaks of infestation by Amyloodinium ocellatum (Dinoflagellida) in cultured gilthead bream Sparus aurata L. and seabass Dicen-trarchus labrax (L.) resulted in sporadic and mass mortalities. Fingerlings and yearlings as well as breeders were affected and, since 1978, larval and post-larval S. aurata in the hatchery. Infestations in juvenile and breeder fish were located predominantly on the gills and mucosal integument but in larval fish only the skin rather than the gills was infested. Histopathological changes of the infested gills are described. Vacuolar degeneration of the cells penetrated by the parasites' rhizoids was evident at the site of attachment and cloudy swelling was apparent in the surrounding epithelial cells. In heavy infestations the entire epithelium of the gill filaments underwent hyperplasia with consequent fusion of the lamellae. Where hyperplasia was extensive the cells gradually degenerated while the inner epithelial layer showed distinct spongiosis and in some cases completely disintegrated. All heavily infested gills lacked mucous cells.     

Tanner crab Chionocetes bairdi Rathbun haemocyte classification and an evaluation of using differential counts to measure infection with a fungal disease

Abstract. The circulating haemocytes of the tanner crab, Chionocetes bairdi , were studied and classified as hyalinocytes, intermediate granulocytes and eosinophilic granulocytes. Differential haemocyte counts of normal crabs and crabs infected with an apparently pathogenic unnamed ascomycete fungus revealed a shift in the hyalinocyte-granulocyte ratio in infected crabs. There was a highly significant increase in the percentage of granulocytes and a corresponding decrease in hyalinocytes in infected crabs. This shift was thought to be caused by a marked increase in the relative number of eosinophilic gianulocytes. There was also a highly significant statistical relationship between the severity of the internal fungus infection, established by histopathological analysis of the major organ systems, and the increased number of circulating eosinophilic granulocytes. The results of the study indicate that differential haemocyte counts may be a valuable tool in monitoring the health of C. bairdi populations.     

Experimental pathogenicity of reovirus 13p2 for juvenile American oysters Crassostrea virginica (Gmelin) and bluegill fingerlings Lepomis macrochirus (Rafinesque)

Abstract. A viral agent (13p₂), isolated from clinically normal juvenile American oysters ( Crassostrea virginica ) and characterized as a new serotype of reovirus, was tested to determine if it could replicate and produce disease in experimental juvenile oysters. Because the virus replicated well in the bluegill fry (BF-2) fish cell line, fingerling bluegills Lepomis macrochirus were included in the pathogenicity experiments. Exposure of oysters to the 13p₂ virus in ambient seawater resulted in no significant mortality and no increased virus titres or histological lesions. Virus particles were not observed in tissues of exposed oysters when examined with transmission electron microscopy (TEM). Intraperitoneal inoculation of the 13p₂ virus into bluegills resulted in 44% mortality associated with a focal necrotic hepatitis. Evidence of virus replication, when evaluated histological or by virus titration, was observed in 94% of 32 inoculated fish. Samples of infected livers examined with TEM revealed typical cytoplasmic arrays of 13p₂ virus particles in affected hepatocytes. Rising virus titres and hepatic lesions also occurred in bluegills exposed to water containing the 13p₂ virus. These results indicated the natural host of the 13p₂ virus was not the American oyster, but that it was a significant pathogen for at least one fish species.     

Toxicity and efficacy of Furanace on channel catfish Ictalurus punctatm (Rafinesque) infected experimentally with Aeromonas hydrophila

Abstract. The 96-h medium tolerance limit of Furanace (nifurpirinol: P-7138) for channel catfish Ictalurus punctatus at 21°C was 0-94 mg/1. The most effective treatment level for channel catfish, experimentally infected with Aeromonas hydrophila , was 2mg/1 for 6.5 h. Furanace at 0.5 and 1.0 mg/1 in brain heart infusion agar reduced in vitro growth of A. hydrophila and at 2.0 mg/1 growth was completely     

A bibliography of shrimp and prawn nutrition

This paper contains a bibliography of papers published on dietary and nutritional work with shrimps and prawns. In addition, selected papers on related topics, such as the nutrition of other crustacea, the natural food of shrimps and prawns, and physiology, are included. The bibliography is intended to be an aid to existing workers in the field of shrimp and prawn nutrition, to be a launch pad for scientists entering this field for the first time, and to assist those wishing to review specific aspects of this subject.     

Degradation of ioxynil by a soil fungus, Fusarium solani

A fungus, Fusarium solani, isolated from the soil, degraded ioxynil (3,5-diiodo-4-hydroxyben-zonitrile) in pure culture into at least eight products. Five products were detected in the organic fractions extracted from a culture grown in [¹⁴C]cyano-labeled ioxynil. Three additional products were separated by ion-exchange chromatography of the acidified aqueous phase. Cultures grown in the presence of [¹⁴C]ring-labeled ioxynil produced the same products in the organic extract and four to five products in the aqueous phase. The cyano-carbon of ioxynil was released as CO₂ at a faster rate than that of ring-carbons and was released after the initial ring cleavage. Two of the metabolites were identified as 3,5-diiodo-4-hydroxybenzamide and 3,5-diiodo-4-hydroxybenzoic acid.     

A method for measuring adenosine triphosphate in soil

A method was devised for the extraction and measurement of adenosine 5'-triphosphate (ATP) in soil that minimizes sorption of ATP on the soil colloids. Soil was ultrasonified for 1 min with a solution containing trichloracetic acid (0.5 m). disodium hydrogen orthophosphate (0.25 m) and paraquat dichloride (0.1 m). The ATP content of the filtered extract was determined without further treatment in a scintillation spectrometer by the firefly luciferin-luciferase system. Recovery of added ATP was greater using the extratant containing trichloracetic acid, orthophosphate and paraquat than with trichloracetic acid alone or with a sulphuric acid extradant. Recoveries of added ATP ranged from 45% to 84% in thirteen different soils; ATP contents from 0.64 to 9.03 μg g^?1 soil.     

Biodegradation of litter in Eucalyptus pauciflora communities—II. Fungal succession in fungicide- and insecticide-treated leaves

Fungal succession on untreated and fungicide- and insecticide-treated leaves of Eucalyptus pauciflora was compared. Natural succession on untreated leaves fits the general scheme for succession on deciduous tree leaves. Initial colonizers are species of Coelomycetes and Moniliales. When the numbers of Coelomycetes decrease in the late stages of decomposition, the frequency of Penicillium species and species of Zygomycetes increases. The succession is affected only marginally by DDT and dieldrin treatment while benomyl severely restricts the occurrence of most fungal species. The effect of benomyl persists even after exposure for 48 weeks in the field.     

Some problems in assessing the fluorescein diacetate-active fungal biomass in the soil

A technique for assessing the metabolically-active fungal biomass by means of fluorescein diacetate (FDA) staining was recently described (Söderström, 1977). In this note some practical details in the application of this technique to studies of FDA-active fungal biomass in the soil are discussed.