The cytochrome oxidase II gene in mitochondria of the sugar-beetBeta vulgaris L.

We have cloned and analyzed the sugar-beet mitochondrial gene for cytochrome oxidase subunit II (coxII). The sugar-beet and its deduced amino acid sequence were compared to its homologouscoxII gene sequences from both monocot and dicot plants. It was found to be highly conserved (89–95%) compared to homologue in other plant species. The 780 bp coding sequence of the sugar beetcoxII gene is interrupted at position 383 by a 1463 bp intron. This intron contains an additional 107 bp sequence that is not found in any of the plantcoxII genes studied thus far. The structure of the intron suggests that a large intron existed in an ancestralcoxII gene before monocots and dicots diverged in evolution. Three CGG codons in the sugar-beetcoxII coding sequence align with conserved tryptophan residues in the homologous gene of other species, suggesting that RNA editing takes place also in sugar-beet mitochondria. In 13 out of 24 codons ofcoxII mRNA that were found to be edited in four other plants, the sugar-beet gene already utilizes the edited codons. This phenomenon may indicate that the mitochondrial genome in sugar-beet is phylogenetically more archaic relative to these plants. An additional sequence of 279 bp that is identical to the first exon ofcoxII was identified in the mtDNA of the sugar-beet. This pseudo-gene is transcribed and its existence in the mitochondrial genome is unexplained.     

The effects of endotoxaemia on protein metabolism in skeletal muscle and liver of fed and fasted rats.

The response of muscle and liver protein metabolism to either a single or three successive daily injections of an endotoxin (Escherichia coli lipopolysaccharide, serotype 0127 B8; 1 mg/ml, 0.3 mg/100 g body wt.) was studied in vivo in the fed rat, and at 24 and 30 h after endotoxin treatment during fasting. In the fed rats there was a catabolic response in muscle, owing to a 60-100% increase in muscle protein degradation rate, and a 52% fall in the synthesis rate. Although there was a 20% decrease in food intake, the decrease in protein synthesis was to some extent independent of this, since rats treated with endotoxin and fasted also showed a lower rate of muscle protein synthesis, which was in excess of the decrease caused by fasting alone. The mechanism of this decreased protein synthesis involved decreased translational activity, since in both fed and fasted rats there was a decreased rate of synthesis per unit of RNA. This occurred despite the fact that insulin concentrations were either maintained or increased, in the fasted rats, to those observed in fed rats. In the liver total protein mass was increased in the fed rats by 16% at 24 h, and the fractional synthesis rate at that time was increased by 35%. In rats fasted after endotoxin treatment the liver protein mass was not decreased as it was in the control fasted rats, and the fractional synthesis rate was increased by 22%. In both cases the increased synthesis rate reflected an elevated hepatic RNA concentration. The extent of this increase in hepatic protein synthesis was sufficient at one point to compensate for the fall in estimated muscle protein synthesis, so that the sum total in the two tissues was maintained.     

Time course of the effect of catabolic doses of corticosterone on protein turnover in rat skeletal muscle and liver.

The time course of the response of protein synthesis in muscle and liver to catabolic doses of corticosterone (10 mg/day per 100 g body wt.) was studied in vivo in growing rats over a 12-day period. The rate of protein synthesis in muscle and liver and the rate of actomyosin synthesis in muscle were measured by the phenylalanine-flooding technique, and 3-methylhistidine (N tau-methylhistidine) synthesis was measured by injection of labelled histidine. 3-Methylhistidine concentrations in tissue free pools and urinary excretion were also measured to compare directly with the rate of muscle protein degradation determined as the difference between synthesis and growth each day during the treatment. The overall rate of protein synthesis in muscle fell gradually over the first 4 days, reaching a rate after 5 days that was 36% of the initial rate, and this lower rate was then maintained for the following week. This decrease in the overall rate was accompanied with changes in the relative rate of synthesis in muscle proteins, since during the first 4 days there was a disproportionate decrease in the rate of actomyosin synthesis, and specifically 3-methylhistidine synthesis. In the latter case the synthesis rate was decreased to only 4% of its initial rate after 4 days. These changes in protein synthesis in muscle were accompanied by a transient increase in the rate of protein degradation, which was more than doubled on days 2 and 3 of treatment but which returned to the original rate on day 5, and a similar pattern of response was indicated by urinary 3-methylhistidine excretion, which also exhibited a transient increase. Thus in this case 3-methylhistidine excretion and measured rates of protein degradation in muscle do correlate. The transient effects of the glucocorticoids on degradation compared with the sustained effect on synthesis suggest that these two responses are achieved by different mechanisms. The hepatic size and protein mass were increased by the treatment, and protein synthesis was well maintained until after 12 days, when the rate was suppressed. Although the fractional synthesis rate was transiently increased for 24 h, it is argued that the enlarged liver most likely reflects a decrease in protein degradation resulting from the increased amino acid supply to the liver. This would result from the cessation of muscle growth while dietary supply was maintained.     

An Improved Diluent for Rubella Hemagglutination and Hemagglutination-Inhibition Tests

Rubella hemagglutinating (HA) antigen was prepared in BHK-21 tissue as 5% cell suspensions and from unconcentrated and 20× concentrated infected supernatant fluids. In some instances, unconcentrated fluids were treated with Tween 80 and ether; cell suspensions were treated with ether alone. Preparations were tested for HA activity in dextrose-gelatin-Veronal (DGV) buffer solutions; 0.85% NaCl; Sorenson's phosphate-buffered saline, pH 7.2; and a diluent of 0.9% NaCl, 0.1% CaCl₂ (anhydrous), and 0.1% MgSO₄·7H₂O. HA titers were consistently two- to fourfold higher in the saline with added Ca⁺⁺ and Mg⁺⁺ than in DGV. Hemagglutination-inhibition titers of paired human sera were the same in either diluent. It is suggested that the interaction between rubella HA antigen and the red cells of young (less than 1-day-old) chicks may be at least partially ion dependent and that titers are enhanced by increased quantities of divalent cations.     

Seasonal variability in mercury inputs into the Ria de Aveiro,Portugal

Water, suspended particulate matter (SPM) and sediments were collected from the Esteiro de Estarreja (Ria de Aveiro, Portugal), which receives considerable quantities of waste mercury from a chlor-alkali plant. Dissolved and particulate Hg concentrations in the effluent ranged between 4 –167 g I^–1 and 141–3144 g g^–1, respectively, at pH values of >10. The effluent plume undergoes significant chemical changes during advection downestuary. The evidence suggested that adsorption of dissolved Hg onto organic-rich SPM was an important process. A maximum sediment Hg concentration of 500 g g^–1 was found about 1.5 km from the discharge, as a result of the settling of Hg-rich SPM. Downestuary Hg concentrations in sediments decline to about 100 g g^–1 at the mouth of the Esteiro. The particle-water interactions are discussed in terms of the transport of dissolved and particulate Hg into the Ria de Aveiro.     

Particle sources and trace element reactivity in the Humber plume

Samples of suspended particulate matter (SPM) collected from the Humber Estuary had higher concentrations of particulate metals than SPM from Holderness coastal waters (U.K.). Characterised SPM from both sources was used in laboratory experiments involving the uptake of radiotracer¹⁰⁹Cd,¹³⁷Cs,⁵⁴Mn and⁶⁵Zn. Kinetic experiments, over five days, showed that the rate and extent of uptake was highly dependent on particle type, with¹⁰⁹Cd,⁵⁴Mn and⁶⁵Zn being more reactive with Humber Estuary particles than those from Holderness and¹³⁷Cs having the opposite trend. Adsorption experiments were also carried out on suspensions in which SPM from the Humber Estuary and Holderness coastal water were mixed in various proportions. These experiments revealed that K_d for⁶⁵Zn increased linearly with the proportion of Humber SPM, K_d for¹³⁷Cs decreased linearly with increase in Humber SPM and K_d for⁵⁴Mn and¹⁰⁹Cd displayed non-linear behaviour. The results of the study were used to develop an algorithm for predicting the partition coefficients in the Humber Plume based on the extent of particle mixing from the two source regions. The use of^206/207Pb ratios in determining the extent of particle mixing is discussed, along with the application of the algorithm to the modelling of particulate trace metal behaviour in the Humber-Wash coastal zone.     

ANTIVIRAL ACTIVITY OF CULTURED BLUE-GREEN ALGAE (CYANOPHYTA)1

Lipophilic and hydrophilic extracts from approximately 600 strains of cultured cyanophytes, representing some 300 species, were examined for antiviral activity against three pathogenic viruses. Approximately 10% of the cultures produced substances that caused significant reduction in cytopathic effect normally associated with viral infection. The screening program identified the order Chroococcales as commonly producing antiviral agents.     

The Second Messenger, Cyclic AMP, Is Not Sufficient for Myelin Gene Induction in the Peripheral Nervous System

Abstract: The adenylyl cyclase-cyclic AMP (cAMP) second messenger pathway has been proposed to regulate myelin gene expression; however, a clear correlation between endogenous cAMP levels and myelin-specific mRNA levels has never been demonstrated during the induction or maintenance of differentiation by the myelinating Schwann cell. Endogenous cAMP levels decreased to 8–10% of normal nerve by 3 days after crush or permanent transection injury of adult rat sciatic nerve. Whereas levels remained low after transection injury, cAMP levels reached only 27% of the normal values by 35 days after crush injury. Because P₀ mRNA levels were 60% of normal levels by 14 days and 100% by 21 days after crush injury, cAMP increased only well after P₀ gene induction. cAMP, therefore, does not appear to trigger myelin gene induction but may be involved in myelin assembly or maintenance. Forskolin, an activator of adenylyl cyclase, increased endoneurial cAMP levels only in the normal nerve, and in the crushed nerve beginning at 16 days after injury, but at no time in the transected nerve. Only by treating transected nerve with 3-isobutyl-1-methylxanthine (IBMX), an inhibitor of cAMP phosphodiesterases, in combination with forskolin was it possible to increase cAMP levels. No induction of myelin genes, however, was observed with short- or long-term treatment with IBMX and forskolin in the transected nerve. A three-fold increase in phosphodiesterase activity was observed at 35 days after both injuries, and a nonmyelinated nerve was shown to have even higher activity. These experiments, therefore, suggest an important role for phosphodiesterase in the inactivation of this second messenger-dependent stimuli when Schwann cells are non-myelinating, such as after sciatic nerve injury or in the nonmyelinated nerve, which again implies that cAMP may be required for the maintenance of the myelin sheath.