Sensitivity of insect ovarian tissues to various pteridines as tested in tissue culture

The effect of pteridine derivatives and analogues on the cell outgrowth from the ovarian explants of the waxmoth, Galleria mellonella, was examined in hanging-drop cultures and cytochemical tests were made for succinate and glucose-6-phosphate dehydrogenases. Most of the derivatives and analogues of 2-amino-4-hydroxypteridine injured to a lesser or greater extent insect ovarian tissues in vitro, depending on the drug structure and the concentration applied. Of all the pteridine derivatives and analogues tested only 2-amino-4-mercaptopteridine and its C-6,7-dimethyl derivative (10 μM) promoted cell outgrowth from the explants as did folate.     

The biology and physiology of alga-invertebrate symbioses. III. In situ measurements of photosynthesis and calcification in some hermatypic corals

In situ measurements of the rates of photosynthesis and calcification in three species of hermatypic corals were made at Eilat, in the Gulf of Aqaba, Red Sea. Experiments were made at 5, 20 and 35 m depth under unusually poor conditions of submarine illumination for the region, and at the relatively low water temperature (21°C) for coral growth which prevails there all year. Estimates of photosynthetic rates by both the ¹⁴C and oxygen methods indicated that the ¹⁴C method does measure gross photosynthesis in these organisms even at, and below, light compensation points. Substantial rates of carbon fixation in Acropora and Millepora show that, even under bad conditions, these organisms could survive autotrophically to at least 10 m depth, as also could the massive coral Goniastrea although this had much lower photosynthetic rates under the same conditions, compensated for by a much lower respiratory rate than the other two corals.Calcification rates were variable but showed a considerable increase in light as compared with the dark in all three species, and the rates did not decrease with depth as much as might have been anticipated from the reduction in photosynthesis and ambient light energy. Photosynthetic and calcification rates were similar to those reported for similar organisms both in the Caribbean and on the Great Barrier Reef.     

Effect of adrenalin, insulin and contractions on the content of the free fatty acid fraction in skeletal muscle.

The fraction of free fatty acids (FFA) is present in skeletal muscles. However, there is almost no data regarding regulation in the content of this intramuscular lipid pool. We took advantage of the isolated muscle preparation to examine whether: a) increasing exogenous concentration of FFA (500microM or 700microM, 30min) b) insulin (10.00 I.U./L, 30min), c) adrenalin (4.4 nM, 30 min), or d) contractions (200ms, tetani, 1Hz, 30min), affect the FFA content inside myocytes. Incubation of soleus (S) and extensor digitorum longus (EDL) with increasing concentrations of exogenous FFA (from 500microM to 700microM) resulted in an increase in the total FFA fraction in both muscles studied (by 280.2% and 259.1%, respectively). In contracting muscles FFA pool was significantly reduced both in S (by 73.1%) and in EDL (by 31.1%). Neither stimulation by adrenalin nor insulin affected the total content of FFA fraction in the muscles examined. We conclude that a) increased availability of exogenous FFA at the sarcolemma level results in an increase in the size of intramuscular FFA fraction b) the intracellular FFA fraction is utilized by contracting muscles with regard to the fiber composition and to a greater extent in more oxidative muscles, c) FFA fraction remains stable upon stimulation by insulin or adrenalin.     

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).