Single and continuous exposure of the adult American oyster, Crassostrea virginica, to marine vibrios

1974 ◽  
Vol 20 (4) ◽  
pp. 513-517 ◽  
Author(s):  
Haskell S. Tubiash
Keyword(s):  
Crassostrea Virginica ◽  
Microbial Population ◽  
Vibrio Anguillarum ◽  
Test System ◽  
Continuous Exposure ◽  
Bivalve Mollusks ◽  
American Oyster ◽  
Test Organisms ◽  
High Concentrations ◽  
Marine Vibrios

Adult American oysters, Crassostrea virginica, were challenged by single and continuous exposure to high concentrations of vibrios and other bacteria reportedly pathogenic to aquatic animals. A reduction in microbial population in a test system containing oysters compared with an oyster-free control indicated that the mollusks were ingesting or otherwise clearing the bacteria. Oysters exposed to one strain of Vibrio anguillarum experienced higher mortalities than those exposed to the other test organisms, but in no case did mortalities approach those previously found in similarly challenged larval bivalve mollusks. These bacteria appear to be of marginal significance as primary pathogens of adult American oysters.

The Effect of High Concentrations of Ethylene on Seed Germination of Douglas Fir (Pseudotsugamenziesii (Mirb.) Franco)

1975 ◽  
Vol 5 (3) ◽  
pp. 419-423 ◽  
Author(s):  
Carey Borno ◽  
Iain E. P. Taylor
Keyword(s):  
Seed Germination ◽  
Germination Rate ◽  
Inhibitory Effect ◽  
Germination Percentage ◽  
Douglas Fir ◽  
Control Treatment ◽  
Continuous Exposure ◽  
Short Term ◽  
Short Term Exposure ◽  
High Concentrations

Stratified, imbibed Douglas fir (Pseudotsugamenziesii (Mirb.) Franco) seeds were exposed to 100% ethylene for times between 0 and 366 h. Germination rate and germination percentage were increased by treatments up to 48 h. The 12-h treatment gave largest stimulation; 30% enhancement of final germination percentage over control. Treatment for 96 h caused increased germination rate for the first 5 days but reduced the germination percentage. Germinants were subject to continuous exposure to atmospheres containing 0.1 – 200 000 ppm ethylene in air, but it did not stimulate growth, and the gas was inhibitory above 100 ppm. Although some effects of high concentrations of ethylene may have been due to the lowering of oxygen supplies, this alone was insufficient to account for the full inhibitory effect. The mechanism of stimulation by short-term exposure to ethylene is discussed.

Intracellular distribution of lead in Tetrahymena during continuous exposure to the metal

1979 ◽  
Vol 39 (1) ◽  
pp. 383-396
Author(s):  
J.R. Nilsson
Keyword(s):  
Cell Growth ◽  
Growth Medium ◽  
Food Vacuole ◽  
Continuous Exposure ◽  
Organic Growth ◽  
Food Vacuoles ◽  
Entire Cell ◽  
Membrane Bound ◽  
Lag Period ◽  
High Concentrations

Lead acetate (0.1–0.2%) forms a precipitate with the organic growth medium. The Tetrahymena cells ingest this lead-containing precipitate and cell growth is resumed after a variable lag period. Ingested lead is observed as electron-dense material in food vacuoles. Soon after exposure, cytoplasmic lead (preserved with certain fixation only) is revealed as electron-dense particles in cilia and in a halo around digestive vacuoles. Later the lead particles pervade the entire cell but after the lag period they are confined to membrane-bound spaces. In dilute growth medium, high concentrations of lead inhibit food-vacuole formation and cell growth. Under these conditions lead is deposited in alveoli of the pellicle and is also found in autophagic vacuoles and other membrane-limited structures. The study has revealed that lead enters Tetrahymena through the membrane of digestive vacuoles and through the cell surface. The change in distribution of lead during the lag period indicates that a mechanism is activated for removal of lead into membrane-bound spaces. The final storage of lead seems to be in lysosomes.

Regulation of metallothionein genes in the American oyster (Crassostrea virginica): Ontogeny and differential expression in response to different stressors

Gene ◽  
2006 ◽  
Vol 379 ◽  
pp. 156-165 ◽  
Author(s):  
Matthew J. Jenny ◽  
Gregory W. Warr ◽  
Amy H. Ringwood ◽  
David A. Baltzegar ◽  
Robert W. Chapman
Keyword(s):  
Differential Expression ◽  
Crassostrea Virginica ◽  
American Oyster

scholarly journals A comparison of ten USEPA approved total coliform/E. coli tests

2007 ◽  
Vol 5 (2) ◽  
pp. 267-282 ◽  
Author(s):  
Jeremy Olstadt ◽  
James Jay Schauer ◽  
Jon Standridge ◽  
Sharon Kluender
Keyword(s):  
Environmental Protection Agency ◽  
False Positive ◽  
The United States ◽  
Total Coliform ◽  
Test System ◽  
E Coli ◽  
Test Systems ◽  
High Concentrations ◽  
Different Strains ◽  
Positive Results

Since 2002, the United States Environmental Protection Agency (USEPA) has approved ten enzyme-based total coliform and E. coli detection tests for examination of drinking water. These tests include: Colilert®, Colilert-18®, Colisure®, m-Coli Blue 24®, Readycult® Coliforms 100, Chromocult®, Coliscan®, E*Colite®, Colitag™ and MI Agar. The utility of the enzyme based test systems is based on both the ability of the test to detect the target organisms at low levels and the ability of the test system to suppress the growth of non-target organisms that might result in false positive results. Differences in the ability of some of these methods to detect total coliform and E. coli, as well as suppress Aeromonas spp., a common cause of “false positive” results, have been observed. As a result, this study was undertaken to elucidate the strengths and weaknesses of each method. Water samples were collected from three geographically and chemically diverse groundwaters in Wisconsin. One-hundred milliliter aliquots were individually spiked with both low concentrations (one to ten organisms) and high concentrations (fifty to one-hundred) of each of five different total coliform organisms (Serratia, Citrobacter, Enterobacter, E. coli, & Klebsiella). These spiked samples were used to test the capability of ten enzyme-based test systems to both detect and enumerate the spiked organisms. In addition, 100 ml samples were independently spiked with two different strains of Aeromonas spp. at six different levels, to assess the ability of each enzyme-based test to suppress Aeromonas spp. Analysis of the data indicated that wide variability exists among USEPA approved tests to detect and quantify total coliforms, as well as suppress Aeromonas spp.

Marine Biosurfactants, III. Toxicity Testing with Marine Microorganisms and Comparison with Synthetic Surfactants

1991 ◽  
Vol 46 (3-4) ◽  
pp. 210-216 ◽  
Author(s):  
Knut Poremba ◽  
Wilfried Gunkel ◽  
Siegmund Lang ◽  
Fritz Wagner
Keyword(s):  
Marine Bacterium ◽  
Sea Water ◽  
Toxicity Testing ◽  
Test System ◽  
Marine Microorganisms ◽  
Oil Dispersants ◽  
Test Organisms ◽  
Pure Cultures ◽  
Microtox Test ◽  
Synthetic Surfactants

Eight synthetic and nine biogenetic surfactants were tested on their toxicity. Because of their possible application as oil dispersants against oil slicks on sea. the test organisms used were marine microorganisms (mixed and pure cultures of bacteria, microalgae, and protozoa). Bacterial growth was hardly effected or stimulated, whilst that of algae and flagellates was reduced. All substances tested were biodegradaded in sea water. The bioluminescence of Photobacter phosphoreum (Microtox test) was the most sensitive test system used. A ranking shows that most biogenetic surfactants were less toxic than synthetic surfactants. No toxicity could be detected with the glucose-lipid GL. produced by the marine bacterium Alcaligenes sp. MM 1.

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