Temperature sensitive mutant of Herpes simplex virus type 1. II. Neurovirulence and latency]

The course of acute infection of mice with ts mutant or the native strain DNA and the antigens of HSV in brain nerve cells were determined. Virus DNA was detected in brains of all mice in both animal groups while the virus antigens--only in cells of mice infected with the native strain. It can be suggested, therefore, that the ability of ts mutant to replicate in central nervous system of the infected mice is lacking or much lower. The detection of virus nucleic acid 3-5 months after virus infection might indicate a possibility of establishing latent infection. However, ts mutant showed a significantly lower possibility of latency induction, as compared with highly virulent strains. It was found that the mutant ability to induce latent infection was markedly increased when mice were treated with both ts mutant and Depo-Medrol as immunosuppressive agent. This finding shows both a possibility of increase of frequency of latent infections in the state of immunosuppression, and of activation of the latent infection (recurrence of acute form of infection).     

Utilization of exogenous siderophores by enterococci]

The study was undertaken to investigate the ability of enterococci to assimilate iron via siderophores of bacteria living in the same habitats in the human organism. The potential recipients of exogenous siderophores were six Enterococcus faecalis and six Enterococcus faecium strains, isolated from clinical materials of human origin. The donors of siderophores were Gram-negative rods (various species of the Enterobacteriaceae, Pseudomonas and Acinetobacter) and Gram-positive cocci (various species of Staphylococcus and Streptococcus). All of the investigated E. faecium and only two E. faecalis strains demonstrated the ability to utilize the siderophores of the aforementioned bacterial groups, predominantly the chelators of Gram-negative rods, those of Gram-positive cocci were utilized to a smaller extent. Four recipient strains from E. faecalis species did not demonstrate the ability to utilize siderophores synthesized by all of 40 investigated donor strains.     

Application of carbon balance to submerged citric acid production by Aspergillus niger

Summary In an air-lift fermenter, the following production was obtained from 125 g sucrose in mineral medium at pH 2.5 : 15.76 g mycelium dry wt, 107.2 g citric acid anhydrous and 0.594 mol CO₂ within 138 h (run I) and 13.72 g mycelium dry wt, 114.28 g citric acid and 0.516 mol CO₂ within 144 h (run II). Initially, the carbon content of consumed sugar and products did not balance. At the end of fermentation, the carbon content of the products was 0.9%–5.5% higher than that of the consumed sugar. For the purpose of the calculations the carbon content in mycelium was accepted as 0.462.The work was a part of Project No 04.11 CPBP, topic No 2.24     

Free and conjugated gibberellins in dormancy and germination of apple seeds

Halińska, A. and Lewak, St. 1987. Free and conjugated gibberellins in dormancy and germination of apple seeds.
The presence of gibberellin A₄ (GA₄) was confirmed in partly stratified seeds of apple ( Malus domestica Borb., cv. Antonówka) by mass spectrometry of the methyl ester. Levels of free and conjugated gibberellins A₄₊₇ and A₉ changed during drying of mature seeds, during cold and warm stratification, as well as during germination of dormant and non-dormant embryos. The temporary rise in GA₄₊₇ during cold stratification and during the culture of dormant embryos as well as the lack of it under conditions of warm stratification, allowed us to postulate a role for GA₄₊₇ in the removal of dormancy. In addition, GA₉ was absent in dormant embryos and increased during cold stratification and during the culture of non-dormant embryos. This suggests the involvement of GA₉, in induction of normal development of the seedling. The equivalence between changes in free and conjugated GAs suggests that formation and hydrolysis of conjugates are involved in the control of the physiologically active levels of free GA₄₊₇ and GA₉.     

The effect of long-term selenium and vitamin E-enriched diet on the content of lipid peroxides and cholesterol in rats

The effect of long-term diets enriched with natural antioxidants was studied on Wistar rats with average initial body weight 150 g. After enrichment of the diet with selenium (0.1 ppm of sodium selenite per 100 g of diet), with vitamin E (6 mg of alpha-tocopherol per 100 g of diet) and selenium and vitamin E together the following results were obtained: diets enriched with selenium or vitamin E given for 12 months reduced the production of lipid peroxides in the liver and serum of the rats. On the other hand, addition of both antioxidants to the diet had no effect on lipid peroxide levels in the animals. Diet enrichment for 12 and 18 months with selenium or vitamin E had no effect on the levels of total cholesterol and HDL cholesterol. The obtained results suggest that selenium and alpha-tocopherol exert an inhibitory action on the processes of ageing in the experimental animal model.