Ornithine decarboxylase immunoreactivity in the pituitary gland. A comparative lightmicroscopical study

In the present study efforts are made to localize ornithine decarboxylase enzyme protein--the key enzyme of polyamine biosynthesis--in the adenohypophysis of different vertebrates by means of immunocytochemistry. The antigenic expression of ornithine decarboxylase was revealed in the pituitary of the clawed frog (Xenopus laevis D.), but not in rat and human adenohypophysis. The immunocytochemical results are compared with the staining pattern of the periodic acid-Schiff-reaction. No correlation between these results and the immunocytochemically obtained data has been found. Conclusions are drawn from the location of the enzyme and possible phylogenetic and humoral regulation mechanism.     

<Emphasis Type="Italic">POLG1</Emphasis> p.R722H mutation associated with multiple mtDNA deletions and a neurological phenotype

Background  

The c.2447G>A (p.R722H) mutation in the gene POLG1 of the catalytic subunit of human mitochondrial polymerase gamma has been previously found in a few occasions but its pathogenicity has remained uncertain. We set out to ascertain its contribution to neuromuscular disease.     

Extraction of astaxanthin from giant tiger (Panaeus monodon) shrimp waste using palm oil: studies of extraction kinetics and thermodynamic

Study of extraction of astaxanthin from giant tiger (Panaeus monodon) shrimp waste using palm oil was conducted to determine the extraction kinetics and thermodynamic parameters. Two extraction models were proposed: mass transfer kinetic model and reaction kinetic model. It was found that both of mass transfer and reaction kinetic control the extraction of astaxanthin from shrimp waste using palm oil. The thermodynamic parameters of extraction were also obtained in this study.     

NMR properties of conjugated linoleic acid (CLA) methyl ester hydroperoxides

NMR data on lipid hydroperoxides is scarce. In this study, hydroperoxides were produced from methyl 9-cis,11-trans-octadecadienoate and from methyl 10-trans,12-cis-octadecadienoate by autoxidation in the presence of 20% of alpha-tocopherol. Ten different hydroperoxides were isolated from the autoxidation mixtures of the two conjugated linoleic acid (CLA) methyl esters by SPE and HPLC. The assignment of the 1H and 13C NMR spectra of these hydroperoxides was accomplished by 2D NMR experiments and by spectral simulations. Substitution of a hydroperoxyl group at the allylic position in CLA methyl esters induced a 53.93 ppm downfield shift on the hydroperoxyl-bearing carbon resonance. The effects on the olefinic alpha, beta, gamma, and delta carbon resonances were -3.45, +4.96, -1.22, and +4.42 ppm, respectively. Furthermore, the solvent effects of deuterochloroform, deuteroacetone, and deuterobenzene on the 13C resonances of the hydroperoxides suggest that deuterochloroform is the appropriate solvent for 13C NMR studies on mixtures of lipid hydroperoxides.     

Luminal Ca2+ regulation of single cardiac ryanodine receptors: insights provided by calsequestrin and its mutants

The luminal Ca2+ regulation of cardiac ryanodine receptor (RyR2) was explored at the single channel level. The luminal Ca2+ and Mg2+ sensitivity of single CSQ2-stripped and CSQ2-associated RyR2 channels was defined. Action of wild-type CSQ2 and of two mutant CSQ2s (R33Q and L167H) was also compared. Two luminal Ca2+ regulatory mechanism(s) were identified. One is a RyR2-resident mechanism that is CSQ2 independent and does not distinguish between luminal Ca2+ and Mg2+. This mechanism modulates the maximal efficacy of cytosolic Ca2+ activation. The second luminal Ca2+ regulatory mechanism is CSQ2 dependent and distinguishes between luminal Ca2+ and Mg2+. It does not depend on CSQ2 oligomerization or CSQ2 monomer Ca2+ binding affinity. The key Ca2+-sensitive step in this mechanism may be the Ca2+-dependent CSQ2 interaction with triadin. The CSQ2-dependent mechanism alters the cytosolic Ca2+ sensitivity of the channel. The R33Q CSQ2 mutant can participate in luminal RyR2 Ca2+ regulation but less effectively than wild-type (WT) CSQ2. CSQ2-L167H does not participate in luminal RyR2 Ca2+ regulation. The disparate actions of these two catecholaminergic polymorphic ventricular tachycardia (CPVT)-linked mutants implies that either alteration or elimination of CSQ2-dependent luminal RyR2 regulation can generate the CPVT phenotype. We propose that the RyR2-resident, CSQ2-independent luminal Ca2+ mechanism may assure that all channels respond robustly to large (>5 muM) local cytosolic Ca2+ stimuli, whereas the CSQ2-dependent mechanism may help close RyR2 channels after luminal Ca2+ falls below approximately 0.5 mM.     

Successional changes in habitat caused by sedimentation in navigation pools

Effects of Cu and Zn through food as well as through the water on the growth and emergence of the young larvae of Epeorus latifolium (Ephemeroptera), were investigated using an indoor model stream. The critical lowest concentrations of Cu which have significant effects on the growth of the larvae were between 10 and 15 µg l^-1 Cu. Growth and emergence of the larvae fed on the algae (diatoms) which accumulated more than 1000 µg Cu g^-1 (dry wt.) were significantly impaired. Growth of the mayfly larvae exposed to 100 or 300 µg l^-1 Zn ceased after the second week, and all died before emergence. At 30 µg l^-1 Zn, the growth rate decreased gradually and many larvae died before emergence. The molt interval also nearly doubled that of the control at these concentrations. Growth and emergence of the mayfly fed the algae which accumulated more than 2000 µg g^-1 of Zn were significantly affected.     

Developmental changes in mouse brain polyamine metabolism

Mouse brain ornithine decarboxylase (ODC) activity is high at the time of birth, whereas S-adenosyl-l-methionine decarboxylase (SAM-DC) activity is low. ODC activity, and putrescine, spermidine and spermine concentrations decline rapidly during postnatal development to the low level characteristic of mature brains, while SAM-DC activity behaves in the opposite manner. The fluctuations in mouse brain polyamine metabolism are in accord with those found in the rat. The apparentK _m values of ODC and SAM-DC for their substrates decline parallel with the decrease of substrate and product concentrations during ontogeny suggesting substrate and/or product dependent regulation of polyamine synthesis in the developing brain.     

Diurnal levels of polyamines and activities of ornithine andS-adenosyl-l-methionine decarboxylases in mouse brain

The levels of putrescine and spermine in mouse brain were rather constant at different times of day, as were the activities of ornithine andS-adenosyl-l-methionine decarboxylases. Contrary to an earlier report, the level of spermidine was found to be relatively constant. A possibly significant feature in the present results was the steady decline during the light period and rise during darkness of cerebral spermidine and spermine levels, the differences between maximum and minimum being about 15% for both compounds.     

The hydrologic environment of Pool 19 of the Mississippi River

Invertebrate populations and biomass were studied over four years (1978–1981) in a coastal, saline lagoon in eastern England. Both temperature and salinities fluctuated sharply, with salinities as high as 72.4 gl⁻¹. Of 14 taxa recorded, only three occurred in significant numbers. Nereis diversicolor exhibited summer peaks over all four years, but there was a gradual trend of decline. Corophium volutator showed peaks in 1978 and 1979, but was largely absent thereafter. Chironomus salinarius showed a peak in numbers in 1978, but was rare in 1979 and largely absent in the following two years. The peak biomass was more than 4 000 mg m-2 in 1978, but was less than half this in subsequent years, when it consisted mainly of N. diversicolor. Laboratory experiments tended to confirm that high summer salinities were the cause of poor invertebrate success. The controlled ingress of brackish water into the lagoon from the adjacent estuary should result in a greater and more predictable production of invertebrates, which form the food supply of the chicks of an important colony of avocets Recurvirostra avocetta.