Notes on the growth and sporulation of a natural population of Aphanizomenon flos-aquae

Aphanizomenon flos-aquae contributed regularly to the summer phytoplankton in Kinnego Bay, a highly eutrophic part of Lough Neagh. Growth of the alga was variable in different years, and was apparently related to the duration of depletion of dissolved nitrate-nitrogen in the water. Although four growth pulses occurred during the study period, sporulation was only observed during one of these, when the population was very dense although evenly distributed down the water column. It seems that Aphanizomenon overwintered in Kinnego Bay as vegetative filaments and that production of akinetes was not necessary for perennation of the species. The observed sporulation in 1973 may have been induced by the high pH values caused by dense phytoplankton crops; no other measured environmental factors were particularly unfavourable to growth of Aphanizomenon at this time.     

Observations on parasitic gastroenteritis and bronchitis in grazing calves: effect of low level feed incorporation of morantel in early season.

Pott J. M., Jones R. M. and Cornwell R. I. 1979. Observations on parasitic gastroenteritis and bronchitis in grazing calves: effect of low level feed incorporation of morantel in early season. International Journal for Parasitology9: 153–157. Twenty-four castrated Friesian calves were divided into two equal groups on a body weight basis and grazed separate halves of an infected pasture. One group was given 1.5 mg/kg per day morantel tartrate in the feed over a period extending from 2 weeks before turning out in early May to early July. The other group of calves received an equivalent amount of unmedicated food as controls. Pasture larval counts showed a similar pattern and level of infection from February to July on both pastures. This consisted of a fall from moderate winter levels to very low levels in April/July. The control pasture then showed a typical sharp rise in August to high levels extending through September and falling to moderate levels in October. The pasture being grazed by treated calves showed only a small rise in larval counts in August. The total pasture contamination was reduced by 85% compared with controls during August/October. Faecal egg and larval counts showed similar differences between treated and control calves. Mild clinical signs of parasitic gastroenteritis and bronchitis were seen in controls but not in the treated group. The latter had a weight gain advantage of 20.5 kg the difference becoming marked in the last month of the trial.     

Prostaglandin and thromboxane production by human and guinea-pig macrophages and leucocytes.

The ability of partially purified human and guinea-pig haematogenous cell populations, when cultured in vitro, to metabolise arachidonic acid (AA) has been studied. Supernatants from 24 hour cell culture have been subjected to analysis for products of AA metabolism by gas chromatography with electron-capture detection. The cell types studied were human peripheral blood monocytes (both glass adherent and non-adherent), neutrophils, eosinophils and leukemia leucocytes; thoracic duct lymphocytes and lung alveolar macrophages. From the guinea-pig, induced and non-induced macrophage or neutrophil enriched peritoneal exudate populations, lymph node cells, peritoneal eosinophils and peripheral blood platelets were examined. Supernatants were assayed for the presence of PGE2, PGD2, PGF2 alpha, TXB2 and 6-keto-PGF1 alpha. In all types studied PGE2 and TXB2 were the major products formed. The identification of PGE2 and TXB2 was confirmed by GC/MS with multiple ion monitoring. The results have been compared with other reports and their possible significance discussed in relation to the proposed role of prostaglandins as mediators and modulators in immunopathology.     

A mutation which alters initiation of transcription by RNA polymerase III on the Ad5 chromosome

Mutant dl 309 is a viable Ad5 deletion mutant. Whereas wild-type Ad5-infected HeLa cells contain two VAI RNA species [VAI(A) and VAI(G)] which differ by three nucleotides at their 5' ends, dl 309-infected HeLa cells contain VAI(G) but no VAI(A) RNA. Nucleotide sequence analysis indicates that dl 309 lacks two base pairs which precede the 5' end of VAI(A) by 22 nucleotides. Since the 5' ends of VAI RNAs are not processed, the 309 deletion serves to identify a portion of the sequence required for RNA polymerase III initiation. Since dl 309 grows as well as wild-type Ad5 in HeLa cells, the VAI(A) species is not essential for viral growth in these cells.     

Growth of selected fungi on leaf-protein supernatant

Summary Some 19 strains ofAspergillus niger,A. oryzae, andPaccilomyces spp. are tested for their ability to grow on the supernatant remaining after the expressed juice from sugar beet tops and meadow grass has been heat-treated to precipitate crude leaf protein, and supplemented as required by glucose or ammonium sulphate. With effective strains ofA. niger,A. oryzae,P. elegans orP. variotii and an optimized carbohydrate/nitrogen ratio, over 70% of the organic content of the supernatant is rapidly converted into mycelial biomass of high protein content.     

Studies on experimental growth retardation in sheep. The effect of removal of a endometrial caruncles on fetal size and metabolism.

Experimental intrauterine growth retardation was studied in sheep. Endometrial caruncles (anlagen of maternal cotyledon) were removed before pregnancy and at a second operation, catheters were implanted into the ewe and fetus at 105-135 days of pregnancy. Three groups of fetuses were defined: low birthweight-for-dates (small-caruncle), normal birthweight-for-dates (normal-sized-caruncle) from ewes which had endometrial caruncles removed and the controls. The mean placental weights in these groups were 139 plus or minus 5 g, 283 plus or minus 46 g, 334 plus or minus 22 g respectively. The brains, kidneys and adrenals of the small-caruncle-fetuses were significantly greater in proportion to body weight than in the controls and the appearance of ossification centres was delayed. Arterial oxygen tension was lower and packed cell volume higher in the small-caruncle-fetuses (PaO2 15 plus or minus 0.6 mmHg; packed cell volume 37.3 plus or minus 1.6%) and normal sized caruncles (PaO2 20.7 plus or minus 1.2 mmHg; packed cell volume 35.2 plus or minus 0.7%) than in the controls (PaO2 23.2 plus or minus 0.7 mmHg; packed cell volume 29.8 plus or minus 0.7%). Plasma concentrations of glucose (0.65 plus or minus 0.12 micromol/ml), lactate (0.9 plus or minus 0.1 micromol/ml) and pyruvate (0.08 plus or minus 0.025 micromol/ml) were lower in small-caruncle fetuses than in the control fetuses (glucose 1.05 plus or minus 0.06 micromol/ml, lactate 1.83 plus or minus 0.7 micromol/ml, pyruvate 0.21 plus or minus 0.06 micromol/ml). The corresponding values for the normal-sized-caruncle fetuses were glucose 0.71 plus or minus 0.12, lactate 1.18 plus or minus 0.7 and pyruvate 0.12 plus or minus 0.03 micromol/ml. The plasma concentration of alanine in the small-caruncle-fetuses (0.25 plus or minus 0.09 micromol/ml) was higher than in the normal-sized-caruncle (0.073 plus or minus 0.009 micromol/ml) or control fetuses (0.12 plus or minus 0.013 micromol/ml). The results indicate that fetal growth retardation due to restriction of placental growth after removal of endometrial caruncles is associated with chronic hypoxaemia, polycythaemia and hypoglycaemia. The restriction of nutrient supply probably accounts for the altered pattern of fetal growth but the relative importance of the changes observed remains uncertain.     

Rabbit erythrocyte purine nucleoside phosphorylase. Differential-inactivation studies.

1. Qualitative studies on the stability of rabbit erythrocyte purine nucleoside phosphorylase showed a marked decrease in the susceptibility of the enzyme to thermal inactivation and digestion by proteinases of different specificities in response to certain of its substrates. 2. The extent to which inosine stabilizes the enzyme against thermal and proteolytic inactivation is related in a quantitative manner to the concentration of this substrate; it is proposed that differences in the rates of inactivation of the enzyme may reflect substrate-induced conformational changes in the enzyme structure that could alter the binding properties of the enzyme in a kinetically significant way. 3. A synergistic effect in the stabilization of the enzyme is observed in response to both substrates, inosine and phosphate, when the enzyme is inactivated with Pronase. 4. In the presence of substrate an increased rate of inactivation after reaction with 5,5'-dithiobis-(2-nitrobenzoic acid) is reported. 5. Differential-inactivation studies were also carried out with calf spleen purine nucleoside phosphorylase, and the results are discussed in relation to the kinetic properties displayed by this enzyme.     

Stimulation of phosphatidylinositol turnover in various tissues by cholinergic and adrenergic agonists, by histamine and by caerulein

Studies are reported of the biochemical and pharmacological characteristics of the stimulation of phosphatidylinositol metabolism that is produced in appropriate target tissues by stimulation of various receptors that use Ca(2+) as their second messenger. (1) Muscarinic cholinergic and alpha-adrenergic phosphatidylinositol responses were observed in rat lacrimal gland, and a response to caerulein was detected in the longitudinal smooth muscle of guinea-pig ileum. (2) The muscarinic cholinergic phosphatidylinositol response of rat lacrimal gland, like that of several other tissues, is not dependent on the availability of extracellular Ca(2+). (3) Three phosphatidylinositol responses, namely to histamine in guinea-pig ileum smooth muscle, to alpha-adrenergic stimulation in rat vas deferens and to muscarinic cholinergic stimulation in rat lacrimal gland, were all found to involve phosphatidylinositol breakdown. (4) The stereospecificity of the muscarinic receptor responsible for the phosphatidylinositol response of guinea-pig pancreas was tested by using the two stereoisomeric forms of acetyl-beta-methylcholine; the S-isomer was very much more active than the R-isomer in provoking both phosphatidylinositol breakdown and its labelling with (32)P, as it is in provoking other physiological responses such as contractility or secretion. (5) Pilocarpine, a muscarinic partial agonist, provoked a significantly smaller phosphatidylinositol breakdown in rat parotid fragments than did carbamoylcholine, a potent muscarinic agonist. (6) All of these results are consistent with, but do not prove, a previously offered hypothesis that suggests that phosphatidylinositol breakdown is a reaction essential to stimulus-response coupling at a variety of cell-surface receptors that mobilize Ca(2+) from and through the plasma membranes of target tissues.     

Effect of calcium ions on ethanol oxidation and drug glucuronidation in isolated hepatocytes.

The effect of extracellular Ca2+ concentration on ethanol oxidation and drug metabolism was studied in isolated rat hepatocytes. Both ethanol oxidation and drug glucuronidation showed similar dependence upon Ca2+, which was a stimulation of activity as Ca2+ was increased to physiological concentration, and inhibition at higher concentration.     

The fine structural localization of acid phosphatase in pore cells of embryonic and newly hatched Deroceras reticulatum (Pulmonata: Stylommatophora)

Summary The fine structure of the pore cells in pre- and post-hatched Deroceras reticulatum is described. The cells have been divided into three main types on morphological grounds, one type being particularly rich in glycogen. Certain pore cells contain haemocyanin granules in grooves below cytoplasmic tongues, and in characteristic double-membrane-bounded vesicles within dilated cisternae of rough endoplasmic reticulum, as well as in other identified areas. All types of pore cells show fine fibres reminiscent of collagen associated with the basal lamina and pore complexes.In addition to acid phosphatase activity in lysosomes and Golgi elements, intra- and extracisternal activity has been demonstrated in association with the rough endoplasmic reticulum. The intracisternal activity is in close proximity to the Golgi apparatus and may represent enzyme that is about to enter the GERL system. Extracisternal activity may be associated with cellular lysis and death, or may represent local areas of degradation leading to cytodifferentiation. Remnants of lysed pore cells appear to be taken up by connective tissue amoebocytes.The authors wish to acknowledge the financial support of the Agricultural Research Council (G.B.) Grant No. AG 72/21, the photographic assistance of Mr. Nigel Green, and some technical assistance from Miss Jane Morgans