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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 colonisation 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.
In the reported research, the reaction of glucose esterification with oleic acid was run with the use of a commercial preparation of lipase originated from Candida Antarctica yeast – Novozymes 435 – as a catalyst. Selected properties of the resultant ester were investigated in comparison with properties of glucose and its complex with oleic acid. Results obtained were compared with properties of a commercial preparation of saccharose stearate, a pure disaccharide and the obtained complex of saccharose with stearic acid. A biotechnological method was used to synthesize glucose oleinate with a degree of substitution reaching DS=0.35. The synthesis proceeded at a low temperature (60°C) at atmospheric pressure without using solvents toxic to humans. Simultaneously, a similar reaction was carried out without the use of enzyme, which enabled obtaining a complex of glucose with fatty acid. The achieved reaction products were characterised by properties different from those of a pure substrate – glucose. In addition, the character of those changes was similar as in the case of saccharose and its fatty derivatives. The ester of glucose and that of saccharose were characterised by lower heats of phase transitions than pure saccharides and their complexes with lipids. The complex of glucose with oleic acid showed high heat of phase transition and high temperature of phase transition as compared to pure glucose and its ester. Saccharose stearate reached lower values of the heat of phase transition and temperature of phase transition in respect of a pure disaccharide and its mixture with stearic acid. Solubility of glucose oleinate, in contrast to that of the other substances examined, did not increase along with increasing temperature.
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