Thyroid function and polyamines. III. Changes in ornithine decarboxylase activity and polyamine contents in the rat thyroid during hyperplasia and involution

Changes in ornithine decarboxylase (ODC) activity and in polyamine contents of the rat thyroid were studied under various experimental conditions. Methylthiouracil (MTU) treatment produced several-fold increases in the thyroid ODC activity and in the content of putrescine, spermidine and spermine within a week. While serum thyrotropin (TSH) levels increased gradually up to 3 weeks, the content of both putrescine and spermidine tended to reach a plateau after 2 weeks of the goitrogen treatment; spermine content continued to increase progressively for 3 weeks. Discontinuance of MTU at 7 days resulted in a rapid decline in the elevated thyroid ODC activity, followed by a diminution of putrescine, spermidine and RNA contents. Thyroidal putrescine, spermidine and RNA responded more sensitively to both introduction and withdrawal of TSH stimulation than thyroidal spermine and DNA. Excess iodide, having no effect on the basal level of thyroid ODC, suppressed the MTU-induced increase in this enzyme activity without affecting circulating TSH, thyroxine (T4) and triiodothyronine (T3) levels. There was a significant negative correlation between the ODC activity and intrathyroidal concentration of iodine in MTU-pretreated rats. Theophylline increased the thyroid weight and ODC activity when given to rats fed with a subeffective dose of MTU. Analyses of serum TSH, T4, T3 and of thyroidal iodine revealed that TSH-induced thyroid ODC activity was suppressed by increased circulating thyroid hormones and/or intrathyroidal iodine. Furthermore, it was suggested that thyroid hormones and excess iodide acted directly on the thyroid to alter polyamine biosynthesis, possibly by changing the responsiveness of the gland to TSH.     

Changes in polyamine levels in various organs of Bombyx mori during its life cycle

Polyamines in various organs of larval, pupal, and moth stages of Bombyx mori, were assayed by high-performance ion-exchange chromatography and paper and thin-layer chromatography. Putrescine and spermidine were especially abundant in the silk gland, gonads, mucous gland, and sucking stomach; spermine was also present in them, but at much lower concentrations. Both norspermidine and norspermine were detected in almost all organs examined, while their precursor 1,3-diaminopropane was found only in a limited number of organs. Low concentrations of sym-homospermidine were observed in the silk gland and ovary. Cadaverine content was particularly high in the mucous gland which contained diapause eggs and the sucking stomach. Diapause eggs contained much higher levels of cadaverine than non-diapause eggs. The concentrations of most polyamines in the silk glands remained rather constant during the larval stage, and decreased markedly at the pupal stage. Polyamines in gonads, in contrast, did not decrease at the pupal stage, but putrescine, diaminopropane, and norspermidine rather increased during the pupal and moth stages.     

Polyamine distribution and the potential to form novel polyamines in phytopathogenic agrobacteria

Abstract Polyamines were analyzed in 4 species of genus Agrobacterium . Not only putrescine, spermidine and spermine, but also homospermidine and thermospermine were found in A. tumefaciens, A. radiobacter, A. rubi and A. rhizogenes . Trace amounts of aminopropylhomospermidine were also observed. Norspermidine and norspermine were formed from diamonorpropane added to the medium. Aminopropylcadaverine and its aminopropyl derivative(s) (aminopentylnorspermidine and N,N '-bis(3-aminopropyl) cadaverine) were produced from the supplemented cadaverine. A strain of A. rhizogenes normally contains only putrescine and homospermidine; no other diamines, triamines and tetraamines were synthesized.     

Nucleosome cores containing H2B,H3, H4 and HMG2 are reconstituted

Nucleosome cores mixed with the high mobility group proteins, HMG1 and HMG2, in 2 M NaCl, 5 M urea, 0.2 mM EDTA and 10 mM Tris pH 7.0, have been reconstituted by salt gradient dialysis. The reconstituted material, in 10 mM Tris pH 7.0, had a sedimentation peak at the same position as that of control nucleosome cores in sucrose density gradient ultracentrifugation. The SDS polyacrylamide gel electrophoresis of the reconstituted nucleosome cores demonstrated that they contain H2B, H3, H4 and HMG2 and are selectively deficient in H2A. The circular dichroism of DNA of the reconstituted cores was indistinguishable from that of control nucleosome cores. The results suggest that HMG2 replaces H2A as a component of the nucleosome histone core during reconstitution.     

Usage of high‐performance mattresses for transport of Indo‐Pacific bottlenose dolphin

Ground transport can be a stressful operation for dolphins if the long period of restraint causes damage to internal organs, especially to the lung, generated by their own weight. Buoyancy is deprived from dolphins under moist transport, in which dolphins are transported on mattresses. Upgrading mattresses is an effective way to modify the transportation method so as to compensate for the loss of buoyancy. In Indo‐Pacific bottlenose dolphins (Tursiops aduncus), we tried to find mattresses that performed well at distributing the dolphins' weight and preserved their pulmonary function. When using EV‐17 (thickness, 50 mm) put on EE‐20 (thickness, 50 mm), a wider support area, less extreme changes in pressure, and lower maximum pressures were observed compared with other mattress systems tested. On this mattress system, lower breathing rates, lower heart rates, and higher exhaled CO₂ concentrations were shown compared with using standard mattresses. These results suggest that the performance of the combination of EV‐17 and EE‐20 is better than that of the standard mattress in terms of the cardiopulmonary function of dolphins. Zoo Biol 27:331–340, 2008. © 2008 Wiley‐Liss, Inc.