Long-term changes in the marine macroalgae of Lågskär, Åland Sea (N Baltic)

Species composition, abundance and depth distribution of marine macroalgae were studied at Lågskär, the Åland Sea, in August 1993. Altogether, 26 species were identified and the most diverse vegetation, comprising 18 species, was recorded at a depth of 4–7 m. Comparison with the results obtained by Andersson in 1956 indicates that the total number of species had decreased by 6, and that the best developed and most diverse algal vegetation was then recorded at a depth of 10–15 m. In 1993 species such as Aglaothamnion roseum, Audouinella efflorescens, Phyllophora pseudoceranoides, Halopteris scoparia and Sphacelaria plumigera had disappeared, or were not recorded. Sphacelaria arctica, Cladophora rupestris, Stictyosiphon tortilis and Polysiphonia fucoides , in the 1950s important and dominating species, were greatly reduced in number. However, Pilayella littoralis, Ectocarpus siliculosus, Fucus vesioculosus and Rhodomela confervoides had increased. Compared with the drastic phytobenthic changes recorded in many coastal areas of the Baltic, the changes in the offshore Lågskär area are of minor extent.     

Enhanced hydration of dipalmitoylphosphatidylcholine multibilayer by vinblastine sulphate

Vinblastine sulphate, an antimitotic and anti-inflammatory agent, modifies the thermal behaviour of the model membranes: the dipalmitoylphosphatidylcholine DPPC bilayers. The mixed DPPC and vinblastine sulphate multibilayers in the range of DPPC mole fraction 0.4 to 1 display clearly the gel-liquid crystal (chain melting) transition on the thermograms obtained with a differential scanning microcalorimeter. The molar enthalpy of this transition is slightly depressed by vinblastine sulphate (less than 10%). The temperature-composition phase diagram corresponds to a total insolubility of vinblastine sulphate inside the frozen (gel) bilayers and to a solubility of 0.2 (mole fraction) of vinblastine sulphate inside the fluid (liquid crystalline) bilayers. The dissolved vinblastine sulphate depresses the cooperativity number of the frozen ? fluid transition of the bilayers very strongly (4- to 5-times). Up to its solubility concentration, vinblastine sulphate increases the amount of the structural water of the bilayers and modifies the thermal behaviour of this water. The ‘expelled’ vinblastine sulphate molecules are retained by the polar groups of DPPC molecules and screen their electrostatic interactions with the structural water molecules. Below 0°C, the amount of the structural water, which forms the aqueous separation between two bilayers, is enhanced by vinblastine sulphate. However, the drug reduces (screens) the bilayers interaction with the structural water molecules.     

Removal of Histological Sections from Glass for Electron Microscopy: Use of Quetol 651 Resin and Heat

A method is described for using the epoxy resin Quetol 651 and heat for convenient and rapid separation of conventional histological sections from glass slides for subsequent ultrathin sectioning for retrospective electron microscopy. The same method is useful when Epon-Araldite is substituted for the Quetol 651 resin.