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Fytoplankton aluviálních tůní
Pithart, David ; Kylbergerová, Magdalena ; Pechar, Libor ; Hrbáček, Jaroslav ; Fiala, Dan ; Bílý, Michal ; Rulík, M.
Phytoplankton of alluvial pools at Lužnice alluvium have been investigated by following methodological approaches: seasonal course of phytoplankton in two pools, extensive sampling (quarterly) of 30 pools, and phytoplankton diurnal vertical migration studies in several pools. Prevailing dominance of phytoflagellates, especially Cryptophyceae and Euglenophyceae and low contribution of coccal forms as Chlorococcales and Cyanophyte has been found as a main feature of phytoplankton community. This is caused by poor mixing of water column (large relative depth, wind protectio), where th ecoccal forms sediment out and are outcompeted by motile forms, able to determinate the position within the water column.
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Interaction of sperm surface proteins in the reproduction process
Jonáková, Věra ; Kraus, Marek ; Maňásková, Pavla ; Liberda, J. ; Tichá, M.
Mammalian fertilization includes highly regulated biochemical interactions between complementary molecules located on the surfaces of both gametes as well as those present in the natural environment of the gametes. Boar seminal plasma proteins AQN, AWN spermadhesins and DQH protein that are bound to the sperm at ejaculation play important role in the reproduction process. Binding of sperm to epithelial cells, recognition of gametes and binding of sperm to glycoprotein of zona pellucida are mediated by protein-saccharide interaction, lektin-type interaction. Another type of interaction (protein-protein) participates in the formation of aggregated forms, which seem to be the natural functional forms of seminal plasma proteins. Protein aggregates form the sperm coating layers and their re-modeling in the female reproductive tract is imporatnt for the sperm capacitation and for the primary binding of spermto the ovum.
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