Primary productivity of the River Ely,South Wales,U.K.

The present study was carried out on the non-tidal reaches of the River Ely, South Wales, from October 1979 to October 1980. The seasonal variations of the chlorophyll-a content of the phytoplankton was unimodal with one maximum in May and a minimum in December. The chlorophyll-a content varied from 0.277 to 41.259 mg m^?3. The primary productivity showed a bimodal seasonal distribution with two maxima in May and September and lower values throughout the remainder of the year, particularly in winter. The value for the primary productivity varied from 0.269 to 24.302 mg C m^?3 h^?1. A positive correlation was obtained between chlorophyll-a content and primary productivity. The seasonal distribution of the dominant algal species and the saprobity of the River Ely were also studied. The diatom species almost showed a similar seasonal periodicity. Their concentrations were low during the winter months and high during most of the spring and summer months. Many of the dominant diatom species found in the phytoplankton populations were either considered by the other authors as saprobic (Nitzchia palea) or as inhabitants of eutrophic waters (Gomphonema parvulum, Navicula cryptocephala and Synedra ulna). Chlamydomonas spp. were the most abundant green algae followed by Chlorella vulgaris. The effect of sewage effluent disposal and cattle excreta at three of the sampling sites might partly explain the presence of high Chlamydomonas spp. populations at those sites. Physical factors (low flow rates, high transparency and water temperature) and organic pollution at some sampling sites seemed to play an important role in increasing the number of algal species during spring and summer. The non-tidal reaches of the River Ely were found to be β-mesosaprobic above and below Station 5 and α-mesosaprobic at the latter station and therefore, the river can be considered as polluted at Station 5 and mildly polluted at the others.     

Modulation of lipoprotein lipase activity in cultured rat mesenchymal heart cells and preadipocytes by dibutyryl cyclic AMP, cholera toxin and 3-isobutyl-1-methylxanthine

We have compared the effects of cellular cyclic AMP modulation on the regulation of lipoprotein lipase in cultures of rat epididymal pad preadipocytes and mesenchymal heart cells. Addition of dibutyryl cyclic AMP (dibutyryl cAMP) or 3-isobutyl-1-methylxanthine (IBMX) to preadipocytes grown in serum-containing culture medium resulted in a progressive decrease in lipoprotein lipase activity released into the culture medium so that at 6-8 h enzyme activity ranged between 20 and 30% of that recovered in the control dishes. Similar short-term (6-8 h) studies of the heart cell cultures showed a variable and much less pronounced depression of lipoprotein lipase activity. Thus, following dibutyryl cAMP and IBMX treatment, lipoprotein lipase activity ranged between 70 and 95% of control values. Incubation for 6 h with cholera toxin was followed by a 4-fold rise in the concentration of cellular cyclic AMP in both types of culture, but while in heart cell cultures enzyme activity was unchanged, lipoprotein lipase activity in preadipocytes decreased to 30% of control value. After 24 h incubation with all three effectors, an increase in lipoprotein lipase activity was seen. In the preadipocytes the increase ranged between 50 and 150% above control value, in the heart cell cultures it was 100-250%. 24-h incubation of heart cell cultures with dibutyryl cAMP resulted in a 6-fold increase of heparin-releasable lipoprotein lipase activity while residual activity was doubled. The rise in surface-bound lipoprotein lipase was evidenced also by an increase in the lipolysis of chylomicron triacylglycerol. In the presence of cycloheximide, the dibutyryl cAMP-induced heparin-releasable and residual lipoprotein lipase activity declined at the same rate as the basal activity. The reason for the difference in response of cultured preadipocytes and heart cells to the effectors during the first 8 h of incubation has not been elucidated, but could be related to a possible absence of hormone-sensitive lipase in the heart cells, and hence in a difference in intracellular metabolism of triacylglycerol. On the other hand, a common mechanism can be postulated for the long-term effect of cyclic AMP on the induction of lipoprotein lipase activity in both types of cultures. It probably involves mRNA and protein synthesis, which culminates in an increase in enzyme activity.     

Effect of antidepressant drugs on the in-vitro egg-penetrating ability of golden hamster epididymal spermatozoa

Tricyclic antidepressants appeared to be without effect, except for desipramine which significantly decreased whiplash motility after spermatozoa were added to eggs, and clomipramine which decreased motility and whiplash motility in epididymal sperm suspensions after pretreatment of males. Mianserin and viloxazine were also without effect, but nomifensine significantly decreased sperm motility and whiplash motility and inhibited egg penetration almost completely. After 3 h preincubation with 0.75 mmol nomifensine hydrogen maleate/l, 2/181 and 0/256 eggs were penetrated in two separate series of experiments. Control groups in these series gave medians of 90-100% penetration by 4.5-5.5 h after spermatozoa and eggs were mixed. Maleic acid had a similar effect (1/253 eggs penetrated) whilst nomifensine hydrochloride was inactive, suggesting that the effect was due to the maleate moiety of the original nomifensine hydrogen maleate salt used.     

The effect of triacontanol on growth, photosynthesis and photorespiration in Chlamydomonas reinhardtii and Anacystis nidulans

Chlamydomonas reinhardtii Dangerad 11–32(90) (−), which exhibits C3 properties, and Anacystis nidulans (Strain no. UTEX 625), which exhibits C4 properties, were used to study the effects of triacontanol on growth, photosynthesis and photorespiration. Photosynthetic rate was measured as CO2 uptake and the O2 inhibition of photosynthesis was used as a measure of photorespiration. Triacontanol dissolved in chloroform and dispersed in Tween-20 and triacontanol colloidally dispersed in an aqueous solution of sodium tallow alkyl sulfate were tested. Chlamydomonas cultures increased significantly in cell number after 4 days, and in chlorophyll content after 3 days of treatment with 2.3 × 10⁻⁸ M TRIA in chloroform/Tween-20. In cultures of Anacystis the chlorophyll content became significantly higher 3 days after treatment with 2.3 × 10⁻⁹ M TRIA and the cell number was noticeably higher than the controls.
CO₂ uptake by triacontanol-treated Chlamydomonas cultures was about the same in both 2 and 21% O2, and the O2 inhibition was significantly reduced as compared with the controls. Photosynthesis in Anacystis was O2-insensitive under the experimental condition used. When Anacystis was treated with triacontanol there was no change in the rate of CO2 uptake and no change in the O2 sensitivity of its CO2 uptake. It appears that triacontanol affects some process which regulated the balance between photosynthesis and photorespiration, but other processes which result in increased growth are probably also affected.     

Patterns of isotype commitment in human B cells: limiting dilution analysis of Epstein Barr virus-infected cells

The frequency of Epstein Barr virus- (EBV) inducible IgM, IgG, and IgA-secreting cells in human peripheral blood and tonsil was determined by performing limiting dilution experiments in suspension culture. We devised a method of propagating small numbers of EBV-infected B cells with irradiated umbilical cord blood cells as a feeder layer. Precursor cell frequencies can be derived from these experiments; we have shown by statistical analysis that they conform to the single hit model of the Poisson distribution. By using this technique, a significant percentage of surface immunoglobulin-bearing lymphocytes are activated to secrete immunoglobulin in vitro. On the average, 8 to 38% of B cells in peripheral blood and tonsil can be propagated and the secreted immunoglobulin from the clonal progeny can be analyzed. Neither the EBV immune status of the donor nor the source of the umbilical cord blood feeder layer could account for the variations in cloning efficiency observed among donors. A surprisingly high frequency of B cells secreted IgA in vitro and we have shown that a small proportion of B cell clones in tonsil and peripheral blood secrete both IgM and IgA during the 4-wk culture period. Other B cells, including all those that produce IgG, appear to be committed to the secretion of a single isotype. Thus, these studies establish methodology for the analysis of the secreted products of human B cells at the single cell level and demonstrate that the progeny of at least some clones can secrete more than one isotype in vitro.     

Maternal smoking and trisomy among spontaneously aborted conceptions

In a study of spontaneous abortions, we found an apparently robust association of trisomy with smoking that varies with maternal age. Among women under age 30, smoking either before or at the time of conception is less common in women aborting trisomic conceptions than in controls delivering at 28 weeks or later. Among older women, smoking is more common in women aborting trisomic conceptions than in controls. Our results point to an effect of smoking on the frequency of trisomic abortions that varies with age, and they suggest that the causes of recognized trisomic abortions differ in younger and older women.     

The role of GTP in prostaglandin E1 stimulation of adenylate cyclase in platelet membranes.

Adenylate cyclase activity in platelet membrane preparations was measured in the presence of prostaglandin E1 (PGE1), GTP and a non-hydrolysable analogue of GDP, guanosine 5'-[beta-thio]diphosphate (GDP[beta S]). A dose-dependent inhibition of adenylate cyclase by GDP[beta S] was observed that could be reversed either by adding increased amounts of GTP or of PGE1.     

Formation of complexes between avidin and β-adrenergic receptors using biotinyl-alprenolol derivatives

The goal of this study was to synthesize biotinylated derivatives of alprenolol, a β-adrenergic antagonist, and to determine whether these ligands could bind simultaneously to both avidin (a biotin-binding protein) and to the β-adrenergic receptor. Such ligands would be useful for β-adrenergic receptor localization and purification, since avidin can be covalently labelled with fluorescent or electron-dense markers or can be linked to solid supports for affinity chromatography. Three biotinyl derivatives of alprenolol were synthesized and characterized. Each derivative bound to avidin and also possesed high affinity for the duck erythrocyte β-adrenergic receptor. Two of the compounds, biotinyl-caproyl-cysteaminyl-alprenolol (BCCA) and biotinyl-dodecanoyl-cysteaminyl-alprenolol (BDCA) had the same affinities for the duck erythrocyte β-adrenergic receptor (membrane-bound or digitonin-solubilized) in the absence and presence of avidin. This indicated that high affinity complexes could be formed between the β-adrenergic receptor and avidin using these bifunctional biotinyl-alprenolol ligands. In contrast, biotinyl-cysteaminyl-alprenolol (BCA), in which the distance between the biotin and alprenolol moieties was shorter, had greatly reduced affinity for the duck erythrocyte β-adrenergic receptor in the presence of avidin. Additional studies showed that BDCA, avidin-BDCA, and ferritin-avidin-BDCA were equally potent in inhibiting the isoproterenol stimulation of cAMP accumulation in intact HeLa cells. The data reported in this paper demonstrate the importance of an appropriate spacer sequence to allow correct apposition of the receptor and avidin molecules, and suggest that BDCA may be a useful probe for β-adrenergic receptor localization and purification.     

Glucose Metabolism in Neisseria gonorrhoeae

The metabolism of glucose was examined in several clinical isolates of Neisseria gonorrhoeae. Radiorespirometric studies revealed that growing cells metabolized glucose by a combination on the Entner-Doudoroff and pentose phosphate pathways. A portion of the glyceraldehyde-3-phosphate formed via the Entner-Doudoroff pathway was recycled by conversion to glucose-6-phosphate. Subsequent catabolism of this glucose-6-phosphate by either the Entner-Doudoroff or pentose phosphate pathways yielded CO(2) from the original C6 of glucose. Enzyme analyses confirmed the presence of all enzymes of the Entner-Doudoroff, pentose phosphate, and Embden-Meyerhof-Parnas pathways. There was always a high specific activity of glucose-6-phosphate dehydrogenase (EC 1.1.1.49) relative to that of 6-phosphogluconate dehydrogenase (EC 1.1.1.44). The glucose-6-phosphate dehydrogenase utilized either nicotinamide adenine dinucleotide phosphate or nicotinamide adenine dinucleotide as electron acceptor. Acetate was the only detectable nongaseous end product of glucose metabolism. Following the disappearance of glucose, acetate was metabolized by the tricarboxylic acid cycle as evidenced by the preferential oxidation of [1-(14)C]acetate over that of [2-(14)C]acetate. When an aerobically grown log-phase culture was subjected to anaerobic conditions, lactate and acetate were formed from glucose. Radiorespirometric studies showed that under these conditions, glucose was dissimilated entirely by the Entner-Doudoroff pathway. Further studies determined that this anaerobic dissimilation of glucose was not growth dependent.