Selective Increase In Synthesis Research Articles

Lysozyme in the pericardial complex of Manduca sexta

The pericardial cell-heart complex (pericardial complex) of fifth instar Manduca sexta larvae has been shown to contain, to synthesize and to release lysozyme. Lysozyme activity was present in homogenates of pericardial complex. Immunocytochemical analysis demonstrated that lysozyme in the pericardial complex was located in pericardial cells. Injection of peptidoglycan elicitors, which markedly increase levels of hemolymph lysozyme, also elevated lysozyme activity in homogenates of pericardial complex, but only moderately. Lysozyme synthesis in the pericardial complex was demonstrated in vitro by the incorporation of [ 3H]leucine into immunoprecipitable lysozyme. This tissue did exhibit an increase in the release of a variety of newly synthesized proteins but not a selective increase in the synthesis and release of lysozyme after peptidoglycan stimulation. In similar experiments, cultured fat body from naive larvae incorporated [ 3H]leucine into secreted, immunoprecipitable lysozyme at a rate 100-fold greater than that observed for pericardial complex and exhibited a selective increase in lysozyme synthesis and release to 6.5 times its basal level when stimulated with peptidoglycan. We conclude that, of these two tissues, fat body is the primary source of hemolymph lysozyme. On the other hand, pericardial cell lysozyme may function in the intracellular, lysosomal degradation of pinocytosed fragments of bacterial invaders.

Thyroid function and thyrotropin levels in rabbits immunized to produce antibodies against thyroid hormones

Various parameters of thyroid function were studied in 27 rabbits, out of which 10 were immunized to produce antibodies against triiodothyronine (T 3), 9 against thyroxine (T 4) and 8 were normals. Estimations of T 3, T 4, Free T 4 (FT 4) and thyrotropin (TSH) in blood, qualitative and quantitative analysis of iodoamino acids in serum, protein bound iodine-131 (PB 131I), butanol extractable iodine-125 (BE 125I) and measurement of the disappearance rates of 125I-labelled T 3 and T 4 from plasma were done. In addition, glandular changes were also studied by measurement of 131I uptake, thyroid scanning and chromatographic analysis of hydrolysate of soluble iodoproteins. In T 3 immunized animals, levels of T 3 in serum increased by 38 to 125 times, levels of TSH also showed a significant rise (7.4 ± 1.2 vs 28 ± 9 ng/mL). Chromatographic analysis of iodoamino acids in serum as well as in the hydrolysate of the thyroid gland demonstrated a selective increase in synthesis of T 3. Rate of disappearance of T 3 from blood showed a significant decline. Thyroid glands in the immunized rabbits showed signs of hypertrophy and hyperplasia. Identical studies done in rabbits immunized to produce antibodies against T 4 showed a similar pattern though of variable degree. Our studies indicate that the thyroid glands of the immunized rabbits undergo marked alterations resulting in selective increase in the synthesis and secretion of the particular thyroid hormone against which they were immunized. They do so under the influence of increased levels of TSH.