Effects of Ca2+ and Temperature on Potassium Uptake along Roots of Wheat, Rice and Cucumber

The differences in K⁺ uptake of different segments of excised roots of two thermophilic plants (rice, Oryza sativa L. cv. Dunghan Shali and cucumber, Cucumis sativus L. cv. Csemege Fürtös) and a non-thermophilic plant (wheat, Triticum aestivum L. cv. Aurora) were investigated in the presence and absence of Ca²⁺, at 0 and 25°C, using radiotracer K⁺(⁸⁶Rb⁺) technique. The K⁺ uptake exhibited different temperature- and Ca²⁺-dependent distributions along the root axis for the different species studied. In the case of rice and cucumber an extraordinarily large K⁺ uptake occurred in the apical root portion at 0°C if Ca²⁺ was omitted. The presence of Ca²⁺ diminished this anomaly. For wheat normal K⁺ uptake patterns were observed under similar conditions. At 25°C Ca²⁺-stimulated K⁺ uptake may appear in each root segment, depending upon species and composition of the uptake solution. The results indicate that there may be considerable differences in the compositions of the cell walls and membranes of root cells of thermophilic and non-thermophilic plants, and in their ion-exchange properties, especially in the apical region.     

Development and validation of a method for purification of mallein for the diagnosis of glanders in equines

ABSTRACT: BACKGROUND: The allergic test of mallein is one of the most frequently used tests, together with the Complement Fixation Test (CFT), for the diagnosis of glanders in endemic areas. Mallein, a purified protein derivative (PPD), is produced similarly to PPD tuberculin and the end product is a primarily proteic antigen, which is only poorly purified. The immuno-allergic activity of mallein is believed to be due to a high molecular weight group of proteins present in the antigen. To improve the quality of the antigen, in terms of sensitivity and specificity, a new method of mallein production was developed, in which purification was accomplished by ultrafiltration in a Tangential Flow Filtration system (TFF). RESULTS: The TFF methodology efficiently separated the high and low molecular weight protein groups of mallein. The five TFF-purified malleins, produced from Burkholderia mallei strains isolated from clinical cases of glanders in Brazil, proved to be more potent than standard mallein in the induction of an allergic reaction in sensitized animals. Regarding specificity, two of the purified malleins were equivalent to the standard and three were less specific. CONCLUSION: Some of the TFF-purified malleins showed considerable potential to be used as an auxiliary test in the diagnosis of glanders.     

Synaptosome Antisera affect Permeability of Synaptosomal Membranes <Emphasis Type="Italic">in vitro</Emphasis>

ANTISERA against specific regions of the brain can specifically influence the electrical activity of those regions^1,2. It is possible that these immunological techniques may be used to determine the role of specific chemical components in brain function.     

Comparative Physiology of Neurohypophysial Hormone Action on the Vertebrate Oviduct-Uterus

The neurohypophysial hormone, arginine vasotocin, is depletedfrom the hypothalamus, and rises in concentration in the bloodduring oviposition in hens. The contractile responses of isolatedoviducts from birds, reptiles and amphibians are more sensitiveto arginine vasotocin than to oxytocin or mesotocin. This evidenceclearly indicates that arginine vasotocin is involved in parturitionor oviposition in nonmammalian tetrapods. Evidence for a physiologicalrole for specific neurohypophysial hormones in the regulationof oviduct—or in some cases ovarian — contractilityin fishes is unclear and occasionally contradictory. However,it appears unlikely that arginine vasotocin is involved in thefish species that have been investigated. It is evident that,much like the neurohypophysial hormones, the neurohypophysialhormone receptors of the vertebrate myometrium have undergoneevolutionary change.