Influence of charged groups on the conformational stability of succinoglycan in dilute aqueous solution

Viscosity, optical activity, and differential scanning calorimetry data clearly point out that partial and/or total removal of charged substituent groups, i.e. succinate and pyruvyl residues, from succinoglycan lead to water soluble derivatives exhibiting a higher stability order → disorder conformational changes with respect to the native polysaccharide. The new succinoglycan derivatives also exhibit very little, if any, hysteresis upon ‘renaturation’ (cooling) as opposed to the case of the parent polymer. The absence of ionized groups is thus beneficial, thermodynamically and kinetically, to the attainment in dilute aqueous solution of an ordered conformation by the uncharged succinoglycan backbone, as allowed by the regular enchainment of its constituent sugar residues.     

Effect of ionic milieu to the free radicals generated by phenizine methosulphate (PMS)

The effect of free radicals generated by PMS was studied for membrane damage in the presence of different ions in the erythrocyte model. The degree of membrane damage depended on the quality of ionic composition in the incubation medium. We supposed that the degree of membrane damage depends on the average life and concentration and/or reactivity of the free radicals generated. For control of this supposition free radicals were generated by PMS in the presence of Sodium-di-thionite in isosmotic, waterly systems with different ionic composition. At different time intervals the concentration of free radicals was measured by the ESR method. It seams that concentration of radicals depends on the qualitative composition of ionic milieu. The increase of the average life of free radicals generated by PMS is accompanied by decrease in their reactivity. This is reflected by a moderate membrane damage.     

Urinary elastase 1 in chronic pancreatic disease

Serum and urine elastase 1, its renal output and clearance and urinary gamma-glutamyltransferase and ribonuclease excretions were measured in 16 patients with pancreatic cancer, 23 with chronic pancreatitis and in 22 healthy controls in order to evaluate elastase 1 plasma-urine transfer in chronic pancreatic disease and to investigate any factors that might influence the clearance of this enzyme. In an additional group of 17 patients with different pancreatic diseases the serum molecular size distribution of elastase 1 after chromatography was ascertained. An increased urinary elastase 1 output was found in 4/16 patients with pancreatic cancer and in 6/23 with chronic pancreatitis. No correlation was found between circulating elastase 1 and its urinary output; a negative correlation was detected between the serum levels of this enzyme and its clearance. The excretion of ribonuclease and gamma-glutamyltransferase was correlated with elastase 1 output and clearance. While the majority of elastase 1 in serum was accounted for by high molecular forms, probably the expression of complexes with serum inhibitors, free circulating enzyme was present in all patients with high serum elastase 1. Our findings suggest that elastase 1 urinary excretion increases in some patients with chronic pancreatic disease regardless of the neoplastic or inflammatory nature of the illness. Although the availability of different amounts of ultrafiltrable enzyme may play a role in influencing elastase 1 plasma-urine transfer, renal tubular damage appears to be the most important factor influencing the increase in the urinary output of elastase 1.     

Bovine lens aldose reductase: identification of two enzyme forms

Two structurally different forms of bovine lens aldose reductase have been identified. Freshly prepared lens extracts contain an unactivated "b form" (ARb) which is sensitive to inhibition by Sorbinil. Upon incubation of the extracts with oxygen radical generating systems, ARb is converted to a more active "a form" (ARa), which is not inhibited by Sorbinil. ARa and ARb were purified to electrophoretic homogeneity.     

Expression of bovine and mouse endothelial cell antioxidant enzymes following TNF-alpha exposure

Endothelial cells are primary targets for injury by reactive oxygen species. Endothelial catalase, copper-zinc superoxide dismutase (CuZnSOD), and manganous superoxide dismutase (MnSOD) provide potential antioxidant enzymatic defenses against oxidant-induced cellular damage. Previous studies in vivo and in vitro have demonstrated that in certain cell types exposure to oxidants may increase the expression of one or more of these antioxidant enzymes, thus providing greater intracellular potential to withstand oxidant-induced cell stress. To test whether endothelial antioxidant enzyme expression is influenced by similar oxidant-induced stresses in vitro, we have exposed endothelial cells to tumor necrosis factor-alpha (TNF-alpha) and have measured levels of catalase, CuZnSOD and MnSOD mRNA, and protein. Our results demonstrate a selective increase of MnSOD mRNA, with coordinate increases of both MnSOD protein and enzyme activity in endothelial cells treated for 24/h with TNF-alpha. In contrast, levels of catalase and CuZnSOD mRNA and protein remained unchanged in these cells after TNF-alpha treatment. These observations were made in microvessel endothelial cells derived from murine and bovine sources. Our results indicate that TNF-alpha can act specifically to increase enzymatic antioxidant potential in endothelial cells by induction of a particular antioxidant enzyme encoding mRNA species. These data demonstrate the capacity of endothelial cells to mount an antioxidant defense in response to exposure to an inducer of oxidative damage.     

Developmental regulation of expression of the lactate dehydrogenase (LDH) multigene family during mouse spermatogenesis

Expression of the Lactate Dehydrogenase (LDH) genes during various stages of spermatogenesis was studied by using a combination of Northern blot analyses and in situ hybridization techniques. These studies have indicated that developmentally programmed expression of all three functional LDH genes occurs during differentiation of germ cells. The LDH/C (ldh-3) gene was expressed exclusively during meiosis and spermiogenesis, beginning in leptotene/zygotene spermatocytes and continuing through to the elongated spermatids. LDH/C (ldh-3) gene expression was accompanied by transient expression of the LDH/A (ldh-1) gene in pachytene spermatocytes and round spermatids. The LDH/B (ldh-2) gene was expressed mainly in Sertoli and spermatogonial cells. By using somatic cell hybrids, the LDH/C (ldh-3) gene has been mapped to mouse chromosome 7, establishing that it is syntenic with the LDH/A (ldh-1) gene locus. Experimental observations made in this study provide new insight into the order and sequence of events involved in the regulation of gene expression of the LDH gene family during spermatogenesis.     

Pericentric inversion of chromosome 19 in three families

Summary Pericentric inversion of chromosome 19 has been found in several members of three unrelated families from a restricted geographical region. In one of the families, an additional pericentric inversion of chromosome 9 was observed. Reproductive problems, multiple abortions in two families and a neonatal death in the third, were present. A review of previously described cases is included, and the genetic risk connected with this type of rearrangement is also discussed.     

Seasonal variations on water relations ofAmygdalus communis L. under drip irrigated and non irrigated conditions

Almond plants (Amygdalus communis L.) of the Garrigues variety were grown in the field drip irrigated and rainfed. Leaf water potential (Ψ) and leaf conductance (g₁) were determined throughout one growing season. Pre-dawn measurement for Ψ in the irrigated treatment was consistent through the growing season, whereas in the rainfed treatment it decreased gradually. Ψ values at midday (Ψ minimum) was closely dependent on atmospheric evaporative demand, and their recovery was quicker in the wet treatment than in the dry. The g₁ values were higher in the wet than dry treatments, decreasing in both cases by leaf ageing. Maximum values for g₁ were reached when evaporative demand was highest in the day. The relationship between Ψ and g₁ revealed a decrease in the hysteresis throughout the growing season, being most marked in the dry treatment. The results highlight the close dependence of Ψ and g₁ on evaporative demand, leaf ageing and irrigtion treatment during the growing season.     

First evidence for polyamine conjugation mediated by an enzymic activity in plants

An enzyme activity, found for the first time in plants, mainly located in the 22,000g supernatant of the crude extract of sprout apices of Helianthus tuberosus L. cv OB1 tubers, is able in vitro to covalently bind polyamines to endogenous substrates of different molecular weights. The major assay parameters, such as pH, dithiothreitol, and extract concentrations were optimized. The time course of the reaction, the dependence on putrescine concentration, its competition with histamine, the capacity to bind spermidine and spermine better than putrescine, the stability of the reaction product and analysis of the latter by sodium dodecyl sulfate polyacrylamide gel electrophoresis and thin-layer chromatography suggest that putrescine is linked to endogenous substrates by means of an enzyme reaction that shows some similarities with transglutaminase activities detected in animals. However, the activities of the crude extract and of a fraction eluted from a Sephadex G25 column were not affected by CaCl₂ concentrations lower or equal to 5 millimolar; 4 or 10 millimolar EGTA caused a very small reduction; higher concentrations of CaCl₂ and 15 millimolar or more of EDTA were inhibitory. N,N′-dimethylcasein was not recognized as a substrate. These data indicate that this activity also displays some characteristics which are different from those of animal transglutaminases.     

Symplastic Transfer of Fluorescent Dyes from Mesophyll to Sieve Tube in Stripped Leaf Tissue and Partly Isolated Minor Veins of Commelina benghalensis

We have stripped small (3 × 3 mm) fields of the upper and the opposite lower epidermis of Commelina benghalensis leaves. Pectinase treatment of the resulting chlorenchyma windows produced free-lying viable minor veins with small lumps of mesophyll cells attached. These veins were still connected with the intact remainder of the leaf. Fluorescent dyes were injected into mesophyll cells or mestome sheath cells. Continuous following of the dye from the moment of injection and use of the simple vein system allowed an unhindered and precise assessment of the cell-to-cell route of dye transfer. Disodium fluorescein and Lucifer Yellow CH injected into mesophyll or mestome sheath cells readily moved to the sieve tube. This symplastic dye transfer from mesophyll to sieve tube was also observed after injection into unmacerated stripped leaf tissue. The displacement of fluorescent dyes substantiates a symplastic continuity between mesophyll and sieve tube and therefore supports the possibility of symplastic phloem loading.