Showing papers by "Donald V. Lightner published in 1990"
TL;DR: Purified IHHNV is a non-enveloped icosahedral particle averaging 22 nm in diameter, exhibiting a mean buoyant density of 1.40 g/ml in CsCl, which suggests this virus could be a member of the Parvoviridae family.
Abstract: Infectious hypodermal and haematopoietic necrosis (IHHN) is one of the most important viral diseases of cultured penaeid shrimps and is potentially a limiting factor in the development of farming projects for some species of these shrimps. Although the IHHN agent was recognized early as being viral in origin, attempts to characterize it were inconclusive because of difficulties in obtaining sufficient amounts of purified virions to permit its characterization. Recent improvements of purification procedures have allowed the physicochemical characterization of this virus. Purified IHHNV is a non-enveloped icosahedral particle averaging 22 nm in diameter, exhibiting a mean buoyant density of 1.40 g/ml in CsCl. The genome is a single molecule of ssDNA with an estimated size of 4.1 kb by molecule length measurement in transmission electron microscopy. As determined by SDS-PAGE, the particle contains four polypeptides with Mrs of 74K, 47K, 39K and 37.5K, respectively. From its characteristics, this virus could be a member of the Parvoviridae family.
147 citations
TL;DR: Diseased larvae fed a suspension of the water-insoluble antibacterial Romet-30 exhibited a statistically greater overall survival and a greater survival to the post-larval stage by Student's t-test at the 5% significance level.
Abstract: Nauplii of the brine shrimp, Artemia, and cultures of the soil nematode, Panagrellus redivivus, were fed a suspension of the water-insoluble antibacterial Romet-30 (sulfadimethoxine plus ormetoprim) to determine if they could be used as a mechanism for delivery of the drug to larval penaeid shrimp.
Romet-30 was added to groups of brine shrimp nauplii and nematodes in 1 L beakers to achieve a concentration of 3 mg of drug per ml of seawater. After a 4 h uptake period, predetermined numbers of organisms were assayed for antibiotic content using the micro-plate diffusion method and a Romet-30 sensitive strain of Vibrio alginolyticus as the indicator. The resulting zones of inhibition were compared to that of a standard Kirby-Bauer sensitivity disc containing 25 μg of the drug that was placed on each plate as standard control. Negative controls consisted of equal numbers of nauplii and nematodes that were not exposed to the antibiotic. Artemia nauplii and nematodes accumulated approximately 0.1 μg of the drug per nauplius and approximately 0.25 μg per nematode. They exhibited no signs of toxicity from exposure to the drug and contained the antibiotic in sufficient quantity to provide a theoretical therapeutic dose of the drug when fed to penaeid larvae.
In subsequent tests, normal and diseased larval Penaeus stylirostris readily accepted Romet-30 enriched Artemia. Diseased larvae fed the drug in this manner exhibited a statistically greater overall survival and a greater survival to the post-larval stage by Student's t-test at the 5% significance level.
42 citations
TL;DR: The nondestructive nature of this new technique may be its most important asset; animals tested for IHHNV via this method need not be sacrificed and are thus still available for use as brood stock.
Abstract: The shrimp Penaeus vannamei is frequently an asymptomatic carrier of infectious hypodermal and hematopoietic necrosis virus (IHHNV). In addition, there is increasing evidence that P. vannamei may also suffer severe disease from infection by IHHNV under some culture conditions. Hence, a nondestructive technique has been developed that has the potential to replace the old method of destructive subsampling, at least with this penaeid species. The new procedure is simpler, faster, less labor intensive, and equally precise when compared with the old method. The procedure involves the excision of the first pereiopod, followed by standard histological examination of the appendage nerve cord for the presence of pathognomonic Cowdry type A intranuclear inclusions. The nondestructive nature of this new technique may be its most important asset; animals tested for IHHNV via this method need not be sacrificed and are thus still available for use as brood stock.
9 citations
TL;DR: Occlusion bodies in wet mounts of phloxine-stained tissue squashes and paraffin sections of penaeid shrimp infected with Baculovirus penaei and Penaeus monodon-type baculov virus fluoresced when viewed with an epifluorescent microscope.
Abstract: Occlusion bodies in wet mounts of phloxine-stained tissue squashes and paraffin sections of penaeid shrimp infected with Baculovirus penaei and Penaeus monodon-type baculovirus fluoresced when viewed with an epifluorescent microscope. Inclusions of hepatopancreatic parvo-like virus, infectious hypodermal and hematopoietic necrosis virus, and Autographa californica nuclear polyhedrosis virus did not fluoresce. The use of phloxine stain (alone or as a component of an eosin preparation) and fluorescent microscopy may enhance detection of lowgrade infections by these disease-causing agents.
6 citations