Getting to the root of the problem: new evidence for the use of plant root foods in Mesolithic hunter-gatherer subsistence in Europe

Vegetation History and Archaeobotany - This paper presents new evidence for the harvesting of edible plant roots and tubers at Northton, a Mesolithic hunter-gatherer site on Harris, in the Western...     

Involvement of fibronectin during epiboly and gastrulation in embryos of the common carp,Cyprinus carpio

Summary The present report firstly describes a pilot study in which, during early development of embryos of the common carp, Cyprinus carpio, the cellular adhesion to fibronectin (FN) was blocked by administration of GRGDS peptide (which binds to the FN-receptor). As this treatment resulted in developmental aberrations, suggesting a functional role for FN, the major part of the work was focussed on the distribution of reactivity of anti-FN antibodies during epiboly and gastrulation. GRGDS treatment had a concentration dependent effect on development. Incubation of embryos in 1.5 mg/ml from the 32-cell stage onwards caused a retardation of epiboly, which did not proceed beyond 60%. The embryos did not show involution, as was confirmed by histological study. These preliminary results suggest that FN is involved in both epiboly and gastrulation of carp embryos. During cleavage, no specific extracellular binding of anti-FN antiserum could be observed. However, binding to a number of cell membranes took place from early epiboly onwards. After the onset of gastrulation, we observed a gradually increasing number of the deepest epiblast cells, showing immunostaining on part of their surface, facing the yolk syncytial layer (YSL) or the involuted cells. During early epiboly, anti-FN binding was restricted to areas in front of the migratory hypoblast cells. Later on, binding was found at the border of hypoblast and epiblast cells. At 100% epiboly, some contact areas of epiblast and hypoblast showed a discontinuous lining of reactivity, whilst other areas appeared devoid of anti-FN binding sites. The results indicate that FN is involved in the migration and guidance of hypoblast cells during gastrulation in carp. Correspondence to: P. Gevers     

Striga hermonthica decreases photosynthesis in Zea mays through effects on leaf cell structure

Maize seedlings were grown in pots either with or without preconditionedseeds of the parasitic weed, Striga hermonthica. After between4 and 8 weeks, net photosynthesis in the leaves of maize plantsinfected with Striga decreased compared to leaves of uninfectedcontrol plants. The activities of four enzymes of photosyntheticmetabolism were, however, little affected by infection. A pulse-chaseexperiment using ¹⁴CO₂ showed that C₄ acids were the main earlyproducts of assimilation even when the rate of photosynthesiswas much decreased by infection, but more radio-activity appearedin glycine and serine than in leaves of healthy maize plants.Leaves of infected maize required longer to reach a steady rateof photosynthesis upon enclosure in a leaf chamber than leavesof uninfected plants after similar treatment. Electron microscopy of transverse sections of the leaves ofinfected maize indicated that the cell walls in the bundle sheathand vascular tissue were less robust than in leaves of healthyplants. The results suggest that infection with Striga causesan increase in the permeability of cell walls in the bundlesheath, leakage of CO₂ from the bundle sheath cells and decreasedeffectiveness of C₄ photosynthesis in host leaves. Key words: Zea mays, Striga hermonthica, photosynthesis, photorespiration, enzyme activity     

The effects of calystegines isolated from edible fruits and vegetables on mammalian liver glycosidases

The polyhydroxylated nortropane alkaloids called calyste-ginesoccur in many plants of the Convolvulaceae, Solanaceae, andMoraceae families. Certain of these alkaloids exhibit potentinhibitory activities against glycosidases and the recentlydemonstrated occurrence of calystegines in the leaves, skins,and sprouts of potatoes (Solatium tuberosum), and in the leavesof the eggplant (S.melongena), has raised concerns regardingthe safety of these vegetables in the human diet. We have surveyedthe occurrence of calystegines in edible fruits and vegetablesof the families Convolvulaceae, Solanaceae, and Moraceae byGC-MS. Calystegines A3, B1, B2, and C1 were detected in allthe edible fruits and vegetables tested; sweet and chili peppers,potatoes, eggplants, tomatoes, Physalis fruits, sweet potatoes,and mulberries. Calystegines B1 and C1 were potent competitiveinhibitors of the bovine, human, and rat β-glucosidaseactivities, with K₁ values of 150, 10, and 1.9 µM, respectivelyfor B1 and 15,1.5, and 1 µM, respectively, for C1. CalystegineB2 was a strong competitive inhibitor of the -galactosidaseactivity in all the livers. Human β-xylosidase was inhibitedby all four nortropanes, with calystegine C1 having a K₁ of0.13 µM. Calystegines A3 and B2 selectively inhibitedthe rat liver β-glucosidase activity. The potent inhibitionof mammalian β-glucosidase and -galactosidase activitiesin vitro raises the possibility of toxicity in humans consuminglarge amounts of plants that contain these compounds. edible plants calystegines glycosidase inhibitors bovine, human, and rat liver     

Transient Ischemia Differentially Increases Tyrosine Phosphorylation of NMDA Receptor Subunits 2A and 2B

Abstract: Activation of the N -methyl- d -aspartate (NMDA) receptor has been implicated in the events leading to ischemia-induced neuronal cell death. Recent studies have indicated that the properties of the NMDA receptor channel may be regulated by tyrosine phosphorylation. We have therefore examined the effects of transient cerebral ischemia on the tyrosine phosphorylation of NMDA receptor subunits NR2A and NR2B in different regions of the rat brain. Transient (15 min) global ischemia was produced by the four-vessel occlusion procedure. The tyrosine phosphorylation of NR2A and NR2B subunits was examined by immunoprecipitation with anti-tyrosine phosphate antibodies followed by immunoblotting with antibodies specific for NR2A or NR2B, and by immunoprecipitation with subunit-specific antibodies followed by immunoblotting with anti-phosphotyrosine antibodies. Transient ischemia followed by reperfusion induced large (23–29-fold relative to sham-operated controls), rapid (within 15 min of reperfusion), and sustained (for at least 24 h) increases in the tyrosine phosphorylation of NR2A and smaller increases in that of NR2B in the hippocampus. Ischemia-induced tyrosine phosphorylation of NR2 subunits in the hippocampus was higher than that of cortical and striatal NR2 subunits. The enhanced tyrosine phosphorylation of NR2A or NR2B may contribute to alterations in NMDA receptor function or in signaling pathways in the postischemic brain and may be related to pathogenic events leading to neuronal death.     

Bacillus polymyxa bacteriophages from Brazilian soils

Ten phages of Bacillus polymyxa were isolated from four different Brazilian soils. All were dsDNA-containing phages belonging to Bradley types A and B. Data obtained from electron microscopy and tests of resistance against physical and chemical agents showed that the isolates could be distributed among six different groups. Host range data were in agreement with this classification. When tested against 88 strains of 18 Bacillus species, these phages only infected B. polymyxa strains, thus revealing specificity for this species. Three phage groups lysed all 42 available B. polymyxa strains and are suggested for use in rapid identification of this species.This work was sponsored by the National Research Council of Brasil (CNPq) and CAPES.     

Ultrastructural changes in Blastomyces dermatitidis after in vitro exposure to lidocaine

Electron microscopic examination of yeasts of Blastomyces dermatitidis, exposed in vitro to concentrations of lidocaine that occur when the drug is used for topical anesthesia, showed that lidocaine rapidly damaged intracellular structures. The extent of damage was dependent on the concentration of drug and length of exposure. The observed ultrastructural changes were very similar to those reported for other drugs that directly damage membranes. This relationship suggests that the antifungal effect of lidocaine is the result of direct membrane damage.     

Effects of pH and ionic strength on the structure of collagen fibrils

The roles of pH and ionic strength on the structure and stability of collagen fibrils have been investigated by means of x-ray and neutron diffraction techniques. High-angle x-ray diffraction shows that a salt concentration of 0.5M KCl is sufficient to reduce the osmotic swelling and related disordering in the pH range 1–3. The relative intensities of the low-angle meridional x-ray and neutron diffraction Bragg reflections vary with pH. Difference Fourier syntheses between pH 7 and 1.6 data indicate, for both x-ray and neutron diffraction, a reduced scattering contribution from the telopeptides at low pH. Lyotropic relaxation is a crucial step in the appearance at low pH of a doubling of the 668-Å axial periodicity (D) of collagen fibrils. These results suggest that electrostatic interactions are essential for the structural stability of the telopeptide regions and of the 1D and 3D intermolecular staggers between collagen molecules.     

Calcium-activated thiol-proteinase activity in the fusion of rat erythrocytes induced by benzyl alcohol.

1. Rat erythrocytes were fused by incubation with benzyl alcohol and Ca2+. 2. Cell fusion was inhibited by EGTA, N-ethylmaleimide, tetrathionate, iodoacetamide, cystamine, Tos-Lys-CH2Cl, and to a lesser extent by Tos-Phe-CH2Cl. Phenylmethanesulphonyl fluoride, Tos-Arg-OMe and histamine did not inhibit cell fusion. 3. Gel electrophoresis of membrane proteins from "ghosts" of the erythrocytes treated with benzyl alcohol showed that a high-molecular-weight polymer was present: this was consistent with the entry into the cells of Ca2+ and the activation of a transglutaminase enzyme. 4. In the treated cells the proteins corresponding to bands 2 and 3 in human erythrocytes were decreased, and a polypeptide with a slightly greater mobility than band 3 was produced. 5. These changes were inhibited by EGTA, N-ethylmaleimide, tetrathionate, iodoacetamide, cystamine, and Tos-Lys-CH2Cl, but not by phenylmethanesulphonyl fluoride, Tos-Arg-OMe, or histamine. 6. The intramembraneous particles of the P-fracture face of cells treated with benzyl alcohol to induce fusion were decreased in number and were susceptible to cold-induced aggregation; both of these phenomena were markedly inhibited to EGTA, and partially inhibited by Tos-Lys-CH2Cl and N-ethylmaleimide. 7. These several observations indicate that a Ca2+-activated thiol-proteinase, which acts to degrade membrane proteins and to give freedom of lateral movement to intramembranous particles, may be essential feature of membrane fusion in this system. 8. It is suggested that this proteinase may act to degrade spectrin-binding proteins that attach band-3 protein to the erythrocyte cytoskeleton.