Development and fate of Eutreptiella gymnastica bloom in nutrient-enriched enclosures in the coastal Baltic Sea

Response of the phytoplankton community to bottom-up (nutrients,organic carbon source) and top-down (fish) manipulations, bothsingly and together, were studied daily during a 3 week periodin July 1993 by using eight 50 m³ mesocosms in the coastal northernBaltic Sea. Nutrient additions (once per week) invoked a seriesof blooms of Eutreptiella gymnastica Throndsen (Euglenophyceae)(up to 13 x 10³ cells ml^–1) which formed the major part(60–90%) of the total autotrophic biomass. After rapiddepletion of nutrients (2–3 days) from the surface layer(0–6 m) downwards migration and a subsequent peak of E.gymnasticain the lower part of the water columns (6–12 m) followed.Settled material collected from the bottom of the enclosurescontained a considerable amount of E.gymnastica cells and restingcysts. Nevertheless, sinking loss rates of E.gymnastica wereestimated to be less than 1% day^–1 of the suspended cellnumbers. The fate of E.gymnastica blooms was estimated to begrazing through mesozooplankton. However, provided the nutrientsare plentiful in the water column, the growth potential of E.gymnasticaappears to exceed the ambient grazing pressure. If the nutrientsbecome depleted, it seems to be effectively controlled by mesozooplanktongrazing, which is probably limiting the likelihood of massiveE.gymnastica blooms in the coastal Baltic Sea. Our study suggeststhat E.gymnastica appears to be a fast-growing fugitive (bloom)species with flexible behavioural (vertical migration) and lifehistory (cyst formation) adaptations which is able to exertdominant role and direct trophic relations similar to otherbloom species adapted for decaying turbulence and high nutrientenvironments.     

Dechlorination and spectral changes associated with bacterial degradation of 2-(2-methyl-4-chlorophenoxy)propionic acid

Summary The bacterial degradation of mecoprop (2-(2-methyl-4-chlorophenoxy)propionic acid) was studied using a mixed culture under aerobic conditions. The release of chlorine from mecoprop indicated incomplete degradation (75%), which did not proceed to completion upon extended incubation. The UV absorbance initially increased and this was associated with spectral distortion of the shoulder and trough regions and a slight shift in the maximum wavelength of absorption. GC-MS analysis indicated that 4-chloro-2-methylphenol was an intermediate in the degradative pathway of mecoprop. The GC-MS data also suggested the formation of other phenolic compounds with repositioned chloro-and methylgroups.     

Distribution of a major surface-associated glycoprotein,fibronectin, in cultures of adherent cells

Fibronectin was present in media and cell layers of cultures of adherent cells from human skin, kidney, lung, chest wall, liver, and heart. Cell-surface fibronectin, visualized by immunofluorescence, was in dense fibrillar (cultures from lung), discrete fibrillar (e.g., cultures from skin), or punctate (some cultures from kidney) structures. The subunit sizes of cell-surface fibronectin and fibronectin soluble in medium appeared identical in sodium dodecyl sulfate-polyacrylamide gels. To explain the polymorphism of cell-surface fibronectin, there must be chemical differences among the fibronectins synthesized by different cell strains or factors in the cell layer which influence fibronectin binding and aggregation.     

Adrenergic innervation of the human gall bladder

Summary Adrenergic innervation of the human gall bladder was studied using two specific fluorescence histochemical methods. Blue-green fluorescing varicose nerves were scarce and mostly followed the course of blood vessels as typical perivascular plexuses. However, some adrenergic nerves not associated with the vessels were occasionally seen, as well as structures suggestive of a pericellular arrangement of varicose adrenergic nerve terminals on non-fluorescing ganglion cells. A few enterochromaffin cells were seen in the epithelial lining, also in the deep invaginations obviously representing the Aschoff-Rokitansky sinuses. Occasionally, small rounded cells with a rounded, relatively large nucleus, and exhibiting a weak yellow-green to blue-green granular cytoplasmic fluorescence, were observed in the wall of the gall bladder. The possible functional and evolutionary significance of these neural and endocrine elements was discussed against the data on physiological and pharmacological studies obtained from the literature. It was concluded that their significance is, in all probability, secondary to the influence of the intestinal polypeptide hormones, vagal innervation and circulating catecholamines upon the normal function of the gall bladder. The glyoxylic acid-induced fluorescence histochemical method was found to be superior to the conventional formaldehyde technique in studies on human tissue.     

Lysinuric protein intolerance mutation is not expressed in the plasma membrane of erythrocytes

Summary We measured mediated fluxes of l-lysine and l-ornithine across the plasma membrane of erythrocytes from control subjects and patients homozygous for the lysinuric protein intolerance (LPI) mutation. We found no differences in net uptake or efflux of cationic amino acids in control and LPI cells, contrary to our findings in cultured skin fribroblasts. We conclude that expression of the LPI (y⁺) transport system for cationic amino acids varies between tissues and that measurements of fluxes in erythrocytes cannot be used for diagnosis of LPI.