Dinoflagellés et acritarches des marnes heersiennes de gelinden (base du landénien,Paléocéne,Belgique)

The marls of Gelinden (Heersian stratotype or lowest part of the Landenian) contain rich assemblages of microplankton (98 species), including 73 species of dinoflagellates and 12 species of acritarchs. Some, probably new, are described in open nomenclature.Comparison between Gelinden assemblages and others from the Lower Tertiary and Upper Creataceous confirms the fully Tertiary aspect of the microplanktonic assemblages.Our results added to data obtained from macroflora and Foraminifera more accurately define the conditions of sedimentation into the “bay of Gelinden”: open sea, relatively deep water, not far from shore.     

Value of the β transfer integral in Fe-S clusters

 The purpose of this commentary is to stress that in mixed-valence systems, electron localization and electron delocalization are competitive, the first being most often the stronger. In iron-sulfur clusters where a delocalized Fe(II)Fe(III) pair of maximal spin exists, a minimum value of 1200 cm^–1 is proposed for the resonance integral β parametrizing the electron delocalization. Received: 12 January 1996 / Accepted: 23 January 1996     

A rapid and efficient regeneration system for pea (Pisum sativum), suitable for transformation

A method for plant regeneration via organogenesis in pea (Pisum sativum) using nodal thin cell layer segments has been developed.From 10 to 12 days old sterile pea seedlings, nodal expiants were excised from which leaves and axillary buds were removed. Shoot regeneration was consistently obtained from liquid cultures where the expiants were floated on the medium. Shoots could be harvested after two weeks and thereafter up to ten weeks and no important effect of the cultivar (Bodil, Puget, Rondo and Trille) used could be observed as far as shooting capacity was concerned.Rooting frequency of the regenerated shoots was cultivar dependent. Plantlets were obtained within 7 weeks after expiant excision. Agrobacterium tumefaciens carrying a disarmed Tiplasmid and a binary vector containing the ß-glucuronidase reporter gene, were used in cocultivation experiments on pea nodal expiants in order to obtain transgenic shoots.Abbreviations DHZ dihydrozeatin - IBA indole-3-butyric acid - GUS ß-glucuronidase - NPTII neomycin phosphotransferase II     

Non-selective cation and dysfunctional chloride cahnnels in the apical membrane of nasal epithelial cells cultured from cystic fibrosis patients

Chloride channels and non-selective cation channels in the apical membranes of cultured nasal epithelial cells from three cystic fibrosis patients were investigated with the patch-clamp techinique. Outwardly rectifying chloride channels were found in 31% of the inside-out patches, but activity of this channel was never observed in cell-attached patches, even after stimulation with adrenaline. In 30% of the patches with chloride channels, activation occurred immediately after excision. Most of the channels, however, activated only after a membrane depolarization of +40 to +120 mV. Once activated, the chloride channels were indistinguishable from thsoe in nasal epithelial cells of control patients. Amiloride-insensitive, calcium- and voltage-dependent, non-selective cation channels were present in 11% of the cell-attached and 43% of the cell-free patches and could not be distinguished from those in controls. The cystic fibrosis chloride channel defect is conserved in cultured nasal epithelial cells, while a non-selective cation channel is apparently not affected.