Appearance of purine-catabolizing enzymes in fix and fix root nodules on soybean and effect of oxygen on the expression of the enzymes in callus tissue

The appearance of enzymes involved in the formation of ureides, allantoin, and allantoic acid, from inosine 5′-monophosphate was analyzed in developing root nodules of soybean (Glycine max). Concomitant with development of effective nodules, a substantial increase in specific activities of the enzymes 5′-nucleotidase (35-fold), purine nucleosidase (10-fold), xanthine dehydrogenase (25-fold), and uricase (200-fold), over root levels was observed. The specific activity of allantoinase remained constant during nodule development. With ineffective nodules the activities were generally lower than in effective nodules; however, the activities of 5′-nucleotidase and allantoinase were 2-fold higher in ineffective nodules unable to synthesize leghemoglobin than in effective nodules. Since the expression of uricase has been shown to be regulated by oxygen (K Larsen, BU Jochimsen 1986 EMBO J 5: 15-19), the expression of the remaining enzymes in the purine catabolic pathway were tested in response to variations in O₂ concentration in sterile soybean callus tissue. Purine nucleosidase responded to this treatment, exhibiting a 4-fold increase in activity around 2% O₂. 5′-Nucleotidase, xanthine dehydrogenase, and allantoinase remained unaffected by variations in the O₂ concentration. Hence, the expression of two enzymes involved in ureide formation, purine nucleosidase and uricase, has been demonstrated to be influenced by O₂ concentration.     

The effects of ionizing radiation on the pulmonary vasculature of intact rats and isolated pulmonary endothelium

We studied the effects of ionizing radiation on the morphology of the pulmonary circulation using an in vivo rat model and an in vitro pulmonary artery endothelial cell model. Gamma radiation was given as either an acute (30 Gy) or fractionated (5 X 6 Gy) dose to one hemithorax of rats. An acute 30-Gy dose delivered resulted in a 70% decrease in pulmonary arterial perfusion, using technetium-99m microaggregated albumin (99mTc-MAA), in the irradiated lung by 2-3 weeks after irradiation. Pulmonary microradiographs, using a barium sulfate perfusion method, obtained 2-3 weeks after irradiation demonstrated widespread loss of capillary filling and segmentation of the vessels. Histologic examination demonstrated intact capillaries, suggesting that the alterations in pulmonary perfusion were at the precapillary level. Similar abnormalities in lung perfusion and morphology were found after delivery of fractionated doses of radiation, but the onset of the changes was delayed, occurring 4-6 weeks postirradiation. Using cultured pulmonary endothelial cell monolayers, cell sloughing and retraction from the surface substrate were observed within 24 h after in vitro delivery of 30 Gy. Similar findings occurred in monolayers given fractionated doses (5 X 6 Gy) of radiation 2-3 days after the final dose. The in vivo animal and in vitro endothelial cell models offer a useful means of examining the morphologic alterations involved in radiation lung vascular damage.     

Ganglioside changes associated with temporal lobe epilepsy in the human hippocampus

To understand better the molecular and cellular events associated with status epilepticus, a multifaceted analysis has begun on hippocampal tissues therapeutically removed from patients with temporal lobe epilepsy. In this first study, quantitative changes in major ganglioside species are reported, as well as the immunocytochemical localization on the ganglioside GD3 in epileptic human hippocampus. Although significant variations were found between patients, the pattern of change was consistent when compared to normal values obtained from an autopsied specimen and the literature. Total ganglioside content was reduced in epileptic hippocampi, which was attributable, in part, to pyramidal cell loss found in CA1 and CA3. In each case, the percentage of ganglioside GD3 was increased significantly, while ganglioside GD1a decreased. The former change is probably associated with reactive astrocytosis and the latter with loss of neuronal dendrites. Immunocytochemical localization revealed GD3 in the stratum radiatum and the subgranular layer of the dentate gyrus. In these areas, GD3 was present in punctate structures and astrocytes. These findings indicate that GD3 increases in selected areas of the sclerotic hippocampus and is presumably related to localized accumulation of reactive glial cells. Since gangliosides have a high affinity for calcium and localized increase in extracellular calcium could disrupt normal neuronal function, the localized increase in GD3 may not only denote reactive glial cells but may contribute directly to the altered, hyperexcitable condition of epilepsy.     

Regulation of blue-green algal buoyancy and bloom formation by light,inorganic nitrogen,C02, and trophic level interactions

In highly eutrophic ponds, buoyancy of the gas-vacuolate blue-green alga Anabaenopsis Elenkinii (Miller) was regulated by complex interactions between chemical and physical parameters, as well as by biological interactions between various trophic levels. Algal buoyancy and surface bloom formation were enhanced markedly by decreased light intensity, and to a lesser extent by decreased CO₂ availability and increased availability of inorganic nitrogen. In the absence of dense populations of large-bodied Cladocera, early season blooms of diatoms and green algae reduced light availability in the ponds thus creating conditions favorable for increased buoyancy and bloom formation by A. Elenkinii. The appearance of blue-green algal blooms could be prevented by a reduced density of planktivorous fish, which allowed development of dense cladoceran populations. The cladocerans limited the growth of precursory blooms of diatoms and green algae, and given the resulting clear-water conditions, buoyancy of A. Elenkinii was reduced, and blue-green algal blooms never appeared.     

A Pseudomonas stutzeri outer membrane protein inserts copper into N2O reductase

Among a set of frameshift mutagen (ICR-191; Polysciences, Inc.)-induced mutations that confer inability to grow anaerobically with N2O as the sole electron acceptor, one class was found that produced an inactive N2O reductase which lacked copper. All of these mutant strains failed to produce a 61,000-Mr protein located in the outer membrane. This protein, termed NosA, seems not to be responsible for bringing copper into the cell because the mutant strains and their parent were similarly sensitive to the copper content of the growth medium and no intermediate copper concentration in the medium permitted the mutant strains (nosA) to grow anaerobically with N2O as the sole electron acceptor. We conclude that NosA is necessary to insert copper into N2O reductase or to maintain it there.     

Immunoperoxidase confirmation of parathyroid origin of ultrasound-guided fine needle aspirates of the parathyroid glands

It may be difficult to differentiate between cells of parathyroid and thyroid origin in ultrasound-guided fine needle aspirations of the neck region, even in patients with a clinical history of hyperparathyroidism. A parathyroid hormone antibody was used in an immunohistochemical system to confirm a parathyroid origin in fine needle aspirate smears from nine patients with hyperparathyroidism. Immunoperoxidase positivity for parathyroid hormone confirmed a parathyroid origin in six of nine cases and was strongly suggestive, although equivocal, in the remaining three cases. Technical problems included nonuniform staining and background staining.     

The action of two classes of pyrethroids on the inhibition of brain Na-Ca and Ca + Mg ATP hydrolyzing activities of the American cockroach

Ca2+-stimulated ATP hydrolyzing activities (i.e. Na-Ca ATP hydrolysis and Ca + Mg ATP hydrolysis) measured in cockroach brain tissue were highly sensitive to the action of pyrethroid insecticides under in vitro conditions. Non-cyano-containing pyrethroids inhibited Na-Ca ATP hydrolysis to a greater extent than their cyano-containing counterparts. The reverse is true for pyrethroid action on Ca + Mg ATP hydrolysis. Nonmitochondrial Ca + Mg ATP hydrolysis of disrupted synaptosomes was the most sensitive activity examined. Ca2+-stimulated ATP hydrolyzing activities were inhibited in cockroaches poisoned by permethrin in vivo. In vivo poisoning occurred in the presence of a similar amount of bound [14C]permethrin which had been determined to cause a substantial amount of inhibition to Ca2+-stimulated ATP hydrolyzing activities in vitro.