Medicago cell variants showing altered nitrogen utilization

Nineteen chlorate-resistant variants were isolated after mutagenesis from cells of Medicago coerulea. The level of nitrate reductase activity was variable in these lines and ranged from 100% to less than 5% of the wild type level. Xanthine dehydrogenase was not affected in any of those variants tested.Methylammonium-resistant variants were also isolated from the same type of cells. They show a different regulation of nitrogen utilization. In particular, the enzymatic level of nitrate reductase which, in wild type cells, is sensitive to ammonium repression, is much less affected in the variants. Differences were also seen in the regulation of other functions of the nitrogen-utilizing pathway: xanthine dehydrogenase and, possibly, adenine uptake.on leave from EniChem SpA, Milan, Italy     

A carrot somatic embryo mutant is rescued by chitinase.

At the nonpermissive temperature, somatic embryogenesis of the temperature-sensitive (ts) carrot cell mutant ts11 does not proceed beyond the globular stage. This developmental arrest can be lifted by the addition of proteins secreted by wild-type cells to the culture medium. From this mixture of secreted proteins, a 32-kD glycoprotein, designated extracellular protein 3 (EP3), that allows completion of somatic embryo development in ts11 at the nonpermissive temperature was purified. On the basis of peptide sequences and biochemical characterization, EP3 was identified as a glycosylated acidic endochitinase. The addition of the 32-kD endochitinase to ts11 embryo cultures at the nonpermissive temperature appeared to promote the formation of a correctly formed embryo protoderm. These results imply that a glycosylated acidic endochitinase has an important function in early plant somatic embryo development.     

Effect of guanabenz on the peristaltic reflex and on the spontaneous rhythmic movements of the ileum isolated from the rabbit: do the alpha-2-adrenoreceptors constitute a homogenous population?

The inhibitory effect of the predominantly alpha-2 adrenoceptor agonist, guanabenz, on the peristaltic reflex and on the pendular movements of the rabbit isolated ileum was investigated. Guanabenz depressed or abolished the peristaltic reflex as well as the pendular movements. These effects were concentration-dependent. Guanabenz is much more potent inhibiting the peristaltic reflex (IC50 1 X 10(-7) M) than the pendular movements (IC50 1 X 10(-5) M). The choline ester, acetylcholine restored the peristaltic reflex and the anticholinesterase, eserine, restored the pendular movements previously abolished by guanabenz. During the blockade of the peristaltic reflex produced by guanabenz, the pendular movements were virtually not changed. It is therefore reasonable to suppose that the inhibitory effect of guanabenz reflects the different properties of alpha-2 adrenoceptors associated with cholinergic nerve terminals within the myenteric plexus and the longitudinal smooth muscle subserving the peristaltic reflex and the pendular movements.     

Inhibition of carbonic anhydrase isoforms I,II, IX and XII with secondary sulfonamides incorporating benzothiazole scaffolds

Carbonic anhydrases (CAs, EC 4.2.1.1) catalyze the fundamental reaction of CO₂ hydration in all living organisms, being actively involved in the regulation of a plethora of patho/physiological conditions. A series of benzothiazole-based sulfonamides were synthesized and tested as possible CA inhibitors. Their inhibitory activity was assessed against the cytosolic human isoforms hCA I and hCA II and the transmembrane hCA IX and hCA XII. Several of the investigated derivatives showed interesting inhibition activity and selectivities for inhibiting hCA IX and hCA XII over the off-target ones hCA I and hCA II. Furthermore, computational procedures were used to investigate the binding mode of this class of compounds, within the active site of hCA IX.     

Nomenclatural remarks on the chasmophytic vegetation of the Centaureo-Campanuletalia

The thermophilous chasmophytic vegetation on limestone of the Adriatic Region has been arranged in the endemic order Centaureo-Campanuletalia (class Asplenietea trichomanis). The distribution range of the order covers a large area around the Adriatic Sea – from the south and north east of Italy to Slovenia, Croatia, Bosnia i Hercegovina, Montenegro and Albania. The Centaureo-Campanuletalia or its subordinated syntaxa are quoted in the main syntaxonomic synopses of the Region as well as in technical reports. The critical analysis of the nomenclature of the order, based on the International Code of Phytosociological Nomenclature (ICPN), showed many invalid or incorrect names while it is evident that the usage of correct names in scientific literature is crucial, both for the advances of syntaxonomic knowledge and their application for practical purposes. This paper presents a revision of the nomenclature for the Centaureo-Campanuletalia and related syntaxa in order to stabilize this nomenclature at least at alliance level. As a result, three syntaxa were validated (Centaureo dalmaticae-Campanuletalia pyramidalis, Centaureo cuspidatae-Portenschlagiellion ramosissimae, Inulo verbascifoliae-Centaureetum cuspidatae) and five others were lectotypified.     

Psychomotor excitation caused by beta-endorphin: effect of rubidium and lithium

Effects of lithium and rubidium administered into the cerebral ventricles of conscious cats on psychomotor excitation produced by synthetic human beta-endorphin similarly injected have been investigated. Lithium, but not rubidium, prevented the psychomotor stimulation caused by beta-endorphin. Naloxone, applied intracerebroventricularly, also prevented the psychomotor stimulation produced by this polypeptide. It appears, therefore, that only lithium has a psychotherapeutic value when homeostatic neurohumoral mechanisms are disturbed in the central nervous system by a surplus of beta-endorphin.     

Quantitative assessment of changes in blood CO(2) tension mediated by the haldane effect.

Adequate assessment of circulatory and gas-exchange interactions may involve the quantification of the Haldane effect (HE) and of the changes in blood PCO(2) mediated by changes in Hb-O(2) saturation and O(2)-linked CO(2) binding. This is commonly prevented by the complexity of the involved calculations. To simplify the task, a large series of patient measurements has been processed by regression analysis, thus developing an accurate fit for this quantification (v-a) PCO(2)HE + 0.460 [(a-v) HbO(2)]0.999e0.015(PvCO(2))-0.852(Hct) (n = 247, r(2) = 0. 99, P < 0.001), where (v-a)PCO(2 HE) is the reduction in venous PCO(2) (Pv(CO(2)), Torr) allowed by the chemical binding of CO(2) in blood due to the HE (Torr), (a-v)HbO(2) is the arteriovenous difference in Hb-bound O(2) (ml/dl), and Hct is hematocrit fraction. Values of (v-a)PCO(2 HE) estimated by this expression compared well with the results of previously published experiments. This formula is useful in assessing the impact of HE on Pv(CO(2)) and venoarterial PCO(2) gradient and the survival advantage offered by HE in extreme conditions. Use may be extended to all investigative and clinical settings in which changes in blood O(2) saturation and O(2)-linked CO(2) binding must be converted into the corresponding changes in dissolved CO(2) and PCO(2).     

Di-peptidyl peptidase-4 inhibitor sitagliptin protects vascular function in metabolic syndrome: possible role of epigenetic regulation

Metabolic syndrome (MetS) is a complex medical disorder characterized by insulin resistance, hypertension, and high risk of coronary disease and stroke. Microvascular rarefaction and endothelial dysfunction have also been linked with MetS, and recent evidence from clinical studies supports the efficacy of incretin-based antidiabetic therapies for vascular protection in diabetes. Previous studies pointed out the importance of dipeptidyl peptidase-4 (DPP-4) inhibition in endothelial cells due to getting protection against metabolic pathologies. We therefore aimed to investigate the acute effects of a DPP-4 inhibitor, sitagliptin, on vascular function in rats with high-sucrose diet-induced MetS. In order to elucidate the mechanisms implicated in the effects of DPP-4 inhibition, we tested the involvement of NO pathway and epigenetic regulation in the MetS. Acute use of sitagliptin protects the vascular function in the rats with MetS in part due to NO pathway via restoring the depressed aortic relaxation responses mediated by receptors. Application of sitagliptin enhanced the depressed phosphorylation levels of both the endothelial NO synthase and the apoptotic status of protein kinase B, known as Akt, in endothelium-intact thoracic aorta from rats with MetS. One-hour application of sitagliptin on aortic rings from rats with MetS also induced remarkable histon posttranslational modifications such as increased expression of H3K27Me3, but not of H3K27Me2, resulting in an accumulation of the H3K27Me3. Our findings suggest that, in addition to its well-known hypoglycemic action, sitagliptin may also have beneficial effects on hyperglycemia-induced vascular changes in an endotheium-dependent manner. These present results with sitagliptin aside from the glycaemic control, may demonstrate its important role in the treatment of patients with MetS.