Wyniki wyszukiwania - BazTech

Ograniczanie wyników

Znaleziono wyników: 3

Liczba wyników na stronie

Wyniki wyszukiwania

Wyszukiwano:
w słowach kluczowych: rozwielitki

Sortuj według:

Ogranicz wyniki do:

Effects of ZnO, CuO, Au, and TiO2 nanoparticles on Daphnia magna and early life stages of zebrafish danio rerio

Liu J., Fan D., Wang L., Shi L., Ding J., Chen Y., Shen S.

Environment Protection Engineering

2014

Vol. 40, nr 1

139--149

The effects of four different kinds of nanoparticles (NPs), namely, CuO, ZnO, TiO2, and Au, of the sizes ranging from <20 nm to 50 nm on Daphnia magna, early life stage of zebrafish, and various enzymes have been investigated. The experimental results showed that the NPs inhibited both the body length and hatching rate of zebrafish larvae; the small nanoparticles exhibited more toxicity. In a 21 day chronic toxicity test, metal ions of higher concentrations significantly reduced the number of Daphnia magna offspring. Studies on enzyme activity showed that the NPs reduced the glutathione content and inhibited catalase and superoxide dismutase activities, resulting in shorter body length, lower hatching success, and lower reproduction of zebrafish larvae. Therefore, studies should focus more on the potential toxicity of smaller NPs.

The fate of the ephippia - Daphnia dispersal in time and space

Pietrzak Barbara, Slusarczyk Miroslaw

Polish Journal of Ecology

2006

Vol. 54, nr 4

709-714

When conditions deteriorate, freshwater cladocerans from the genus Daphnia switch to production of diapausing eggs encased in chitinous shells called ephippia. Ephippia may serve for temporal escape and recolonisation of the habitat or for geographical dispersal and colonization of other habitats. While dormancy and dispersal of ephippia have been well studied, initial factors determining the fate of the ephippia have remained unknown. We first consider the fate of an ephippium that sinks to the bottom of the water body, where it enriches the egg bank present in the sediments. We then discuss the potential and evidence for dispersal of ephippia, which is probably facilitated by their flotation on the water surface. Finally, we concentrate on the moment of the release of the ephippium showing a likely mechanism that determines its further fate - temporal or spatial dispersal - and we demonstrate it to be accomplished through maternal behaviour.

Adaptive changes in morphology of Daphnia filter appendages in response to food stress

Bednarska Anna

Polish Journal of Ecology

2006

Vol. 54, nr 4

663-668

Morphological adaptations of Daphnia filtration apparatus in response to unsuitable food conditions are examined and set against earlier published data. To maximize food gathering under limiting food conditions, Daphnia can respond morphologically by plastic changes in the size and structure of its filter apparatus. Under low food quantity and/or poor quality, the area of Daphnia filter screen increases and the mesh size decreases.