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D V Lightner

Publications and source records attributed to D V Lightner.

At least 37 records · Page 2Linked to original sources

Characterization of hepatopancreatic parvo-like virus, a second unusual parvovirus pathogenic for penaeid shrimps.

The hepatopancreatic parvo-like virus (HPV) of penaeid shrimp was extracted from infected shrimp tissues, purified and subsequently characterized. The viral particles, icosahedral in shape, are 22 nm in diameter and possess a buoyant density of 1.41 g/ml. They contain ssDNA, of approximately 5 kb in size which encodes a single polypeptide of 54 kDa. On the basis of its general characteristics this pathogenic agent belongs to the Parvoviridae family, but because of two unusual characteristics (capsid protein formed with a single polypeptide and genome structure more closely related to the autonomous parvoviruses rather than the densoviruses), it seems to constitute a novel group in the Parvoviridae family.

Animals↗

Antimicrobials in shrimp aquaculture in the United States: regulatory status and safety concerns.

The consumption of seafood, especially shrimp, increases yearly in the U.S. The U.S. is the second largest importer of shrimp in the world, consuming more than 11% of the total world production. Aquaculture is becoming an increasingly important source of the world's shrimp, currently accounting for approximately 30% of the world's supply. Unfortunately, in this era of international trade deficits, U.S. production of aquacultured shrimp is insignificant (< 0.1%) compared with world production. As shrimp aquaculture expands in the U.S., so does the use of intensive farming techniques. Shrimp aquaculture is like any other animal husbandry industry in that shrimp are subject to disease, especially under intensive farming methods. In penaeid shrimp, the primary diseases associated with mortalities are usually viral or bacterial. The majority of bacterial infections in penaeid shrimp are attributable to Vibrio species, with mortalities ranging from insignificant to 100%. However, the rapid growth of this industry has outpaced efforts by researchers, pharmaceutical companies, and federal regulatory agencies to provide approved therapeutants for shrimp disease management. Approval of drugs and their surveillance for compliance with regulations applicable to seafoods, including aquacultured goods, is the responsibility of the FDA. There are three general areas of concern regarding human health when chemotherapeutants are used in aquaculture: (1) residues of drugs in fish destined for human consumption; (2) development of drug resistance in human pathogenic bacteria; and (3) direct toxic effects to humans from handling of drugs. Currently, there are no antibacterials approved for shrimp aquaculture in the U.S. One of the major obstacles in the development and approval of new drugs for aquaculture is the cost of conducting the required studies. The high cost to pharmaceutical companies discourages investment in shrimp chemotherapeutant research, since the current U.S. market for such products is small. Unfortunately, the U.S. shrimp aquaculture industry will remain small without legal availability of chemotherapeutants. Oxytetracycline (OTC) and Romet-30 are two antibacterials currently approved in the U.S. for catfish and salmonid aquaculture. Shrimp aquaculture facilities outside of the U.S. routinely use these drugs, as well as others, in the treatment of bacterial disease outbreaks. Much of the work required for OTC approval by the FDA for penaeid shrimp has been completed.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗

Use of non-radioactively labeled DNA probes for the detection of a baculovirus from Penaeus monodon by in situ hybridization on fixed tissue.

Clones isolated from a genomic library of the baculovirus PmSNPV (= MBV) were used to prepare DNA probes for detection of PmSNPV in shrimp tissue. Davidson's AFA fixed shrimp tissues were probed using DNA that had been labeled with the hapten, digoxigenin, by an in situ hybridization assay. The DNA probes readily distinguished PmSNPV-infected from uninfected shrimp tissue. The reactions were localized to the hepatopancreas and midgut, the sites where this virus is detected by standard histological methods. The probes did not react to shrimp infected with Baculovirus penaei (BP = PvSNPV).

Animals↗

Epidemic misuse.

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Animals↗

Performance of an aquatic multispecies system in evaluating the effects of a model microbial pest control agent on nontarget organisms.

A recirculating multispecies test system was developed in conjunction with a study of the fate and persistence of a model microbial pest control agent on non-target marine and freshwater organisms. The basic unit of the system was a 113-I glass aquarium with vertical biological filters in the center of the aquarium, such that two compartments were formed. This allowed the sequestration of predator and prey species within the same system. Organisms from six phyletic groups were subjected to a genetically altered strain of Pseudomonas putida for 15-29 d in either artificial seawater or fresh water. The system was able to maintain the animals for these periods with a minimum of maintenance. Additionally, the system design lent itself to disinfection, dismantling, and rebuilding between experiments with a minimum of labor, and has potential for longer-term studies.

Animals↗

Methods for viral isolation and DNA extraction for a penaeid shrimp baculovirus.

Procedures for the purification of virions and nucleocapsids of Baculovirus penaei (BP) of penaeid shrimp and subsequent extraction of the viral nucleic acid are described. BP-infected hepatopancrata, from two species of shrimp from different geographical locations in the Americas, were removed and homogenized in a solution of TN buffer (0.01 M Tris-HCl, 0.10 M NaCl, pH 8.0). The homogenized mixture was strained through a 100-mesh screen to remove large pieces of tissue and centrifuged to concentrate the remaining material. The pellet was suspended in TN buffer and layered on to a handmade CsCl gradient. Fractions were collected according to the bands observed in the gradient, and the optical density at 254 nm was recorded for each fraction. The resultant data was tabulated and graphed. Additionally, each fraction was examined by transmission electron microscopy to determine relative numbers of viral particles present. Large amounts of virus consistently corresponded to a specific band in the gradient, which produced a peak when the spectrophometric data was graphed. Nucleic acid was then extracted from the purified viral particles. Removal of polysaccharides was accomplished with the addition of CTAB/NaCl. The BP DNA was visualized on an agarose gel with phage lambda DNA markers for size estimation, and a preliminary endonuclease digestion was performed using BamHI.

Animals↗

Purification and characterization of the infectious hypodermal and haematopoietic necrosis virus of penaeid shrimps.

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.

Animals↗

Toxicity of a phthalate ester in the diet of a penaied shrimp.

The toxicity of di-2-ethylhexyl phthalate (DEHP), a ubiquitous environmental pollutant, was measured experimentally as a contaminant in shrimp aquaculture feeds. Diets containing 40 to 50,000 ppm DEHP were fed to Penaeus vannamei for 14 d at 4% body weight/d. DEHP concentrations in shrimp, diet, and water were measured by electron-capture gas chromatography. Whole-body residues in shrimp were 18 ppm at the highest dose, and bioconcentration factors were inversely proportional to dose. DEHP in water was less than or equal to 1.7 ppb for all dose levels. No increased mortality or histopathological alterations were observed at any dose. Absorption of DEHP by P. vannamei was measured in static 24- and 96-h bioassays. Diets enriched with [14C]DEHP to levels of 60, 600, and 6000 ppm were fed at 2% body weight/d. At all dose levels, 3.7% of total radioactivity was measured as body burden in shrimp and 40% as polar species in test water after 96 h. DEHP by oral administration was absorbed, metabolized, and excreted, and this process was linear with dose for the dose range studied.

Analysis of Variance↗

Effect of Several Algicides and Surfactants on the Filamentous Bacterium Leucothrix mucor Oersted.

Leucothrix mucor Oersted, the primary cause of filamentous gill disease in cultured shrimp, was treated with algicides and surfactants by a serial dilution method. It was found to be highly sensitive to those algicides containing quaternary ammonium compounds. Copper-containing compounds and Formalin were less effective, whereas potassium permanganate and two surfactants, Dreft and Alconox, were ineffective.

Journal Article↗

Toxicity of aflatoxin B1 to penaeid shrimp.

Single intramuscular injections of aflatoxin B1 into the tail muscle of Penaeus stylirostris produced 24- and 96-h median lethal doses of 100.5 (78.3 to 129.0) and 49.5 (29.8 to 82.3) mg/kg, respectively. A toxicity curve showed no threshold at the levels tested. The mortality response in a feeding study with P. vannamei was not dose dependent, but tissue and organ damage were similar to that seen in injected animals.

Administration, Oral↗

Ascorbic acid-dependent collagen formation in penaeid shrimp.

1. This study tested the hypothesis that black death, the ascorbic acid (AsA) related disease of penaeid shrimp, is related to collagen underhydroxylation. 2. Collagen measured as hydroxyproline (HYP) in healthy Penaeus californiensis (Holmes) and P. stylirostris (Stimpson) of a wide range of masses were determined. The results revealed a logarithmic relationship between total body collagen HYP and body weight fitting the equation y = 90x1.18 where y = total collagenous HYP (microgram) and x = body weight (g). 3. Shrimp tissues most subject to mechanical trauma (subcutis, hindgut and gills) had the highest collagenous HYP levels and were most consistently and severely affected by an ascorbic acid (AsA) deficiency disease. 4. Prolyl hydroxylase (PH) activity was demonstrated in tissues of P. californiensis and P. stylirostris by hydroxylation of [3,4-3H]proline. 5. AsA was required for shrimp PH activity using a chicken embryo substrate. 6. Nutritional trials revealed that dietary AsA was required for proline hydroxylation in collagen formation in P. californiensis.

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