Diatoms in daphnid culture and bioassay

Keating, Kathleen Irwin; Dagbusan, Brenda Caballero

doi:10.1002/etc.5620050310

Cited by 8 publications

(7 citation statements)

References 18 publications

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“…Individual animals are reared and tested, microbe free, in the MS culture system. Details of the MS system are published elsewhere [16,17]. Glassware is acid‐washed in 10% (by weight) hydrochloric acid.…”

Section: Methodsmentioning

confidence: 99%

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Results of zinc deprivation in daphnid culture

Caffrey

Keating

1997

Enviro Toxic and Chemistry

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Daphnia pulex Leydig (Cladocera), reared in circumstances of strictly controlled trace element exposure, were deprived of zinc. When zinc was withheld from both their liquid medium and solid (algal) food, D. pulex survived for more than 20 consecutive generations before the line ceased reproduction entirely. Through these generations zinc deprivation resulted in a somewhat irregular, but continuing, shortening of life span, a decrease in fecundity (both progeny per brood and number of broods were affected), and a loss of cuticle integrity. A distinct pattern of response was observed during the gradual, multigenerational decline of the animal line. The decline can be separated into three stages: initial (first five), minimal, but steady, increase in overt damage; intermediate (sixth through 19th), varying degrees of damage with apparent severity showing a distinct alternation from generation to generation; and final (last three generations), limited reproduction with ultimate elimination of the animal line by a total absence of reproduction in generation 23.

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Section: Methodsmentioning

confidence: 99%

“…Their performance indicates that no unusual, unknown influences on culture circumstances have occurred. Nondeprived animals, or animals born in zinc‐deprived circumstances and returned as neonates to nondeprived circumstances, are reared in standard MS media (25 ppb zinc) [16,17]. Four animals per treatment are employed.…”

Section: Methodsmentioning

confidence: 99%

Results of zinc deprivation in daphnid culture

Caffrey

Keating

1997

Enviro Toxic and Chemistry

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“…Details of the MS system have been published elsewhere [2,3]. Algal and animal media consist of 21 inorganic salts, * To whom correspondence may be addressed.…”

Section: Methodsmentioning

confidence: 99%

Buffers in daphnid culture and bioassay

Keating

Caffrey

Dagbusan

1996

Enviro Toxic and Chemistry

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When an algal diet is employed, or precipitation of dissolved inorganics during autoclaving is likely, or test circumstances introduce pH changes, addition of a buffer to daphnid culture or bioassay media is appropriate. Glycylglycine, employed in our research for 20 years, is unsuitable for general use because it requires microbe‐free cultures. In contrast, n‐hydroxyethyl piperazine‐n‐2‐propane sulfonic acid (HEPPSO) and N‐2‐hydroxyethyl piperazine‐N′‐2‐ethane sulfonic acid (HEPES) offer safe and effective pH control at 300 ppm for animals, 400 ppm for algae (weight excludes Na), with no requirement for microbe‐free cultures. No negative effects on fecundity, monitored in both single and multigeneration tests, or on vigor, measured by acute bioassay performance, were observed. The 48‐h LC50 for glycylglycine is approximately 4,500 ppm. No deaths occur at or below 10,000 ppm of either HEPES or HEPPSO. When bioassayed against zinc (as chloride), animals reared in cultures buffered by HEPES, HEPPSO, or glycylglycine and tested in unfed acute bioassays performed similarly, allowing 100% survival in 1,000 ppb in 48 h with an LC50 of approximately 1,750 ppb.

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“…Trace elements in the animal's diet are controlled through these media. Additional details of the MS system are published elsewhere (2,10).…”

Section: Methodsmentioning

confidence: 99%

“…Algae were grown, harvested (never stored), and fed to animals in a strictly prescribed manner. Details of algal rearing and bases for species selection are published elsewhere (10). At feeding the food culture was thoroughly mixed and a measured portion of the entire food algal culture containing both cells and medium was added to the animal culture.…”

Section: Methodsmentioning

confidence: 99%

Selenium deficiency induced by zinc deprivation in a crustacean

Pb²

1989

Proc. Natl. Acad. Sci. U.S.A.

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For intact daphnids reared in circumstances of controlled trace element exposure, one consequence of insufficient zinc (Zn) is an increased demand on the animal's pool of available selenium (Se). This demand is manifested by the type of cuticle deterioration associated with Se deficiency and by a depression of reproduction. In the presence of 25 parts per billion (ppb) Zn, 1 ppb Se eliminates these symptoms. In the absence of detectable Zn, 5 ppb Se eliminates overt cuticle damage and substantially increases reproduction. A shortening of life span resulting from Zn deprivation is not ameliorated by Se addition. We suggest that the interplay between Zn and Se concentrations reflects an underlying interplay between interdependent, but distinct, metabolic pathways; i.e., (for Se) glutathione peroxidase and (for Zn) Cu,Zn-superoxide dismutase-each offering protection against free radical damage. Because they are not necessarily localized in a given tissue, the key to recognition of such subtle, complex trace nutrient interactions has been use of intact animals in circumstances of control previously attainable only in tissue cultures.Little specific information concerning the trace element requirements of zooplankters exists. For example, although more than 100 eukaryotic enzymes have been shown to depend on zinc (Zn) (1), no certain proof that Zn is required by a Cladoceran has been published. This reflects more the limitations of the state of the art in animal culture than an absence of common eukaryotic enzymes in zooplankters. Extensive observation of healthy animals under explicit chemical conditions is necessary for determination of trace element requirements, and such observation has not been possible with zooplankters until recently (2).The significance of trace elements in the structuring of aquatic communities has long been acknowledged (3, 4). Yet, in the absence of secure data, only reasonable speculation about the requirements of a specific organism for a specific trace element or the effects on community structure of such requirements has been possible. There is great diversity among the trace element matrices found in various fresh waters. Of particular interest have been the influences on community structure of idiosyncratically low or high concentrations of single elements (5) or of sets of elements (6). As phytoplankton culture became more sophisticated and suitable chelators (7) fostered more qualitative and quantitative control of trace elements in cultures, absolute requirements for most of the trace elements currently identified as essential by nutritionists were recognized as essential for various phytoplankters (8). Zooplankton work has lagged behind.Reflecting the generalized absence of basic proofs of trace element essentiality for zooplankters, our original intent had been simply to withdraw Zn from both the food and ambient water and to produce symptoms of severe deficiency for the first time in a daphnid culture. However, a complex response, involving an induced selenium (Se) defi...

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Diatoms in daphnid culture and bioassay

Cited by 8 publications

References 18 publications

Results of zinc deprivation in daphnid culture

Results of zinc deprivation in daphnid culture

Buffers in daphnid culture and bioassay

Selenium deficiency induced by zinc deprivation in a crustacean

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