THE SYNTHESIS OF MYELIN IN DEVELOPING RAT BRAIN

Abstract— —The synthesis of myelin proteins has been studied in the grey and white matter slices of developing rat brain by measuring the incorporation of [³H]lysine and [¹⁴C]arginine into polypeptide. The incorporation was sensitive to cycloheximide and puromycin at 1 mM concentration. Developing rat optic nerve slices, free of retinal ganglion cells, were able to synthesize myelin basic and proteolipid proteins, but rat retinal preparation failed to synthesize myelin basic protein. Rabbit retinae were able to synthesize myelin basic and proteolipid proteins. Significant activity of the myelin marker enzyme 2',3'-cyclic nucleotide-2'-phosphodiesterase has been found in the rabbit retina but not in rat retina. The results presented in this communication suggest that myelin proteins in the rat CNS are synthesized by the oligodendroglial cells and that neurons probably do not participate.     

Red tide phenomena in Brunei Darussalam — some implications for fisheries

Since the first recorded occurrence in 1976, the coastal waters of Brunei Darussalam have been sporadically subjected to the effects of red tide. The 1976 incident overwhelmed the nation which had no previous experience of red tides. Subsequently, a routine was established to monitor the red tide phenomenon. This included plankton monitoring and shellfish toxicity testing, measures which helped to prevent or mitigate adverse human impacts and economic losses to the fishing industry.The second red tide occurrence was in 1980. However, this time there was greater awareness and with the experience gained from the 1976 incident, the situation was handled effectively.A subsequent incident in 1988 was discovered in a slightly different manner. High densities of Pyrodinium bahamense var. compressum, the causative organism, were found in the stomach contents of a pelagic fish, Sardinella spp. Cats which had fed on contaminated Sardinella suffered sickness and mortality. This led to a ban on the import and sale of Sardinella spp. and the closure of a local shellfish farm for almost a year.Red tide occurrences have had some impact on the fisheries of Brunei Darussalam, mainly due to the need to impose bans on the import, sale and consumption of certain species of fish and shellfish.It is suggested that the effects of red tides on finfish capture fisheries, especially planktivorous fish can be minimised by implementing simple precautions. Shellfish under culture would invariably face losses in the event of a prolonged red tide occurrence and it is proposed that an insurance scheme be implemented to cover such losses.A Red Tide Action Plan is currently in force in Brunei Darussalam. It is a contingency plan for red tide vigilance, monitoring and management, and will serve to reduce the negative impacts of red tides.     

Improving the methods for isolation of monocyte and establishing macrophage cell culture in caprine model

Monocytes are widely used for immunological research, especially in the study of innate immune system. Although methods for isolation of human monocytes have been established, the procedure for non-human monocyte has not been well developed. This paper describes an improved method for isolation of monocyte and the subsequent macrophage cultivation from caprine blood. Monocytes were isolated from 16 ml of heparinized caprine blood using double density methods; the Ficoll and Percoll. The number of monocytes obtained was 5.12 ± 0.89 × 10⁷ cells/ml at 70 % purity. The isolated monocytes were maintained in 10 % fetal bovine serum-enriched Dulbecco’s Modified Eagle Medium for maturation to form macrophage cell culture. At the end of the experiment, the harvested macrophage was 2.48 ± 0.33 × 10⁶ cells/ml.     

Effect of 2,5-hexanedione and 3,4-dimethyl-2,5-hexanedione on retrograde axonal transport in sciatic nerve

The effects of systemically introduced neurotoxic solvents 2,5-hexanedione (2,5-HD) and 3,4-dimethyl-2,5-hexanedione (DMHD) on retrograde axonal transport (RT) of¹²⁵I-labeled tetanus toxin (TT) was studied in rat and mouse sciatic nerves. The rate of retrograde transport of TT in control rat sciatic nerves was slightly higher (6.8±0.4 mm/h) than in mouse sciatic nerves (5.4±0.5 mm/h). A single high dose of 2,5-HD (1,000 mg/kg, i.p.) produced a time-dependent effect on RT in mouse sciatic nerves. 2,5-HD caused a gradual decrease in the velocity of RT (approximately 65% inhibition between 2.0–2.5 h) with a reversal to normal rate 3–5 h after the toxin administration. The effect of DMHD on RT was examined following semi-chronic treatment in rats. DMHD caused a significant decrease (approximately 50%) in the rate of TT transport, in addition, it produced weight loss and hind-limb paralysis.I had the good opportunity of being a member of Professor Alan N. Davison' research team during 1971–1977. This research paper is dedicated to his retirement.