Solute Leakage from the Isolated Parenchyma of Allium cepa and Kalanchoe daigremontiana

Efflux of different solutes from leaf slices of Kalanchoëdaigremontiana and from slices of the onion bulb scale was reinvestigatedwith respect to (1) dependence on turgor, (2) selectivity, (3)integrity of protoplasts and cellular changes. In both materials efflux of solutes (electrolytes or sugars)is non-selective and strongly dependent on turgor. Treatmentof tissue slices with hypotonic solutions (below a criticalosmotic pressure) resulted in high leakage rates, an increasein free space and an increased number of damaged cells. Lowconcentrations of calcium did not prevent this loss of retentionand cell stability. Part of the surviving cells were found to have a strongly decreasedosmotic pressure of cell sap. Leakage did not occur simultaneouslyat all cells of the tissue slice. It can be concluded that effluxfrom parenchyma cells in hypotonic solutions results from irreversibleosmotic breakdown and reversible membrane defects both favouredby high turgor. Key words: Parenchyma cells, Allium cepa, Kalanchoé daigremontiana, Solute efflux, Viability, Permeability, Plasmoptysis     

Presence of the mosquito Anopheles hyrcanus in South Moravia, Czech Republic

During a survey of mosquitoes in the South Moravian lowland area, the mosquito Anopheles hyrcanus (Pallas) (Diptera: Culicidae) was found breeding in an ancient fishpond (Nesyt). It is not clear whether this southern Palaearctic species, a known vector of malaria in Asia which has not been recorded in the Czech Republic until this year, has gone undetected in the past or whether it has recently moved into the region as a result of climate change.