Precursors of cytoplasmic RNA in avian cell nucleus

In nucleus of chick embryo four pre-rRNA of molecular weight of 3.43, 2.93, 2.36 and 1.87 X 10(6) were found in addition to the heterogeneous population of "giant" RNA molecules larger than 4.5 X 10(6) daltons, partially polyadenylated, with few methyl groups and numerous double-stranded regions.     

Immunological and cytochemical indices of white blood cells in old age

The group of aged subjects being 66 to 97 years old was compared with the middle-age group with regard to various immunological and cytochemical indices related to lymphocytes and neutrophils. The aged showed a lowered count and percentage of T cells, increased count and percentage of "non-B, non-T" lymphocytes, increased percentage of B cells. These alterations in the composition of lymphocyte subpopulation were associated with characteristic patterns of damage affecting the enzyme-positive lysosomal apparatus of lymphocytes with regard to acid phosphatase, beta-glucuronidase and N-acetyl-beta-D-glucosaminidase. There was a hundredfold smaller number of cells having intact enzyme-positive lysosomes in the aged than in the group of comparison. The changes mentioned above were also associated with the intracellular accumulation of glycogen in lymphocytes, decreased concentration of IgG and IgM in the serum and various changes in IgA concentration. Neutrophils of the aged were fewer in the blood of the aged than in younger subjects. However, an increased activity of myeloperoxidase, alkaline phosphatase, N-acetyl-beta-D-glucosaminidase, and an increased content of glycogen and lipids could be found in these cells. NBT-positive neutrophil numbers in the aged were lowered if the stimulated test was used and if there were no changes of the spontaneous test.     

Melatonin-induced suppression of the pinealectomy-stimulated rat adrenal cortex mitotic activity

Pineal involvement in the regulation of adrenocortical mitotic activity has recently been suggested. It has been shown that melatonin (Mel) decreased the mean mitotic activity rate (MMAR) of the adrenal cortex both in vivo and in organ culture. The goal of the present study was to test the influence of pinealectomy (PX) and/or Mel-treatment on the MMAR of adrenocortical cells, as well as on the adrenal weight in rats. The stathmokinetic method was used in the study. It was found that PX significantly increased the MMAR of the adrenocortical cells. Moreover, Mel suppressed the proliferogenic effect of PX on the rat adrenocortical cells. Melatonin alone did not significantly affect the mitotic activity of the adrenal cortex. None of the three experimental procedures, i.e. Mel, PX and Mel-treatment of pinealectomized animals significantly affected the adrenal weight. The present data suggest that Mel may be involved in the inhibitory control of adrenocortical cell proliferation.