Differential physiological and antioxidative responses to drought stress and recovery among four contrasting Argania spinosa ecotypes

Our study was undertaken to ascertain whether the change of the water status and the activation of superoxide dismutase and their isoenzymes in Argan tree can support edaphic drought tolerance and its recovery under rehydration. An experiment was conducted on four contrasting ecotypes of Argania spinosa plants: two contrasting coastal ecotypes (Admine (Adm) and Rabia (Rab)) and two contrasting inland ecotypes (Aoulouz (Alz) and Lakhssas (Lks)). Drought stress significantly decreased the leaf water potential and stomatal conductance in the four contrasted ecotypes. In terms of biochemical responses, significant accumulation of carbonyl groups, hydrogen peroxide and superoxide radical has been recorded in the leaves of stressed plants reflecting oxidative stress. In parallel, the activities of total superoxide dismutase (SOD) and their isoenzymes Cu/Zn-SOD, Cu/Zn-SOD and Fe-SOD were also found to have increased to scavenging ROS and protecting the cell against induced oxidative stress. The recovery kinetics of A. spinosa, as a response to rehydration, were significant and rapid. According to the traits having the most discriminating power, both inland ecotypes (Lks and Alz) showed a better upregulation of its protective mechanisms compared to coastal ecotypes (Rab and Adm). All these adaptive traits make the inland ecotypes as an elite resource of drought tolerance and might become the new focus of domestication research of argan tree in arid and semi-arid environments.     

Acute immune hemolysis induced by a degradation product of amphotericin B

We report here on an eight-year-old boy who first developed acute intravascular hemolysis following therapy with amphotericin B (AmB) and subsequently a delayed hemolytic transfusion reaction due to alloantibodies. Although there is as yet no evidence for metabolism of AmB in vivo, the hemolysis appeared to be the result of sensitization against a degradation product of the drug. The patient's serum contained a hemagglutinating IgM antibody that reacted with all red blood cells (RBC) tested in the presence of plasma obtained from patients receiving AmB (ex vivo antigen), but not in the presence of their urine, AmB itself, or with AmB-pretreated RBC. These findings indicate that the antibody was directed against a degradation product of AmB, presumably a trace metabolite, that has not yet been identified.     

Population of Aonidiella aurantii on citrus varieties in relation to their physical and chemical characteristics

Different varieties of citrus exhibit a great variation in their susceptibility to infestation by the red scale, Aonidiella aurantii. Among the thirteen varieties investigated, mandarin clemantine, santara and baladi, orange baladi and rough lemon are the most resistant; while lemon baladi, sour orange and grapefruit are the most susceptible. The susceptibility to infestation decreases with the increase of oil glands in the leaves and fruits of citrus. The total amount of nitrogen, phosphorus and carbohydrates in the leaves of different varieties shows no correlation with their susceptibility to infestation.

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Résumé Différentes variétés de Citrus montrent de grandes variations dans leur sensibilité aux attaques par Aonidiella aurantii. Parmi les 13 variétés étudiées, les plus résistantes sont: mandarine clémentine, mandarine baladi et rough lemon, tandis que lemon baladi; sour orange et pamplemousse sont les plus sensibles.La sensibilité aux infestations décroît proportionnellement avec l'accroissement du nombre des glandes à huiles essentielles sur les feuilles de citrus. La quantité totale d'azote, de phosphore et d'hydrates de carbone dans les feuilles des différentes variétés ne montre aucune corrélation avec leur sensibilité aux infestations.

     

Rose bengal activates the Ca2+ release channel from skeletal muscle sarcoplasmic reticulum.

The photooxidizing xanthene dye rose bengal (10 nM to 1 microM) stimulates rapid Ca2+ release from skeletal muscle sarcoplasmic reticulum vesicles. Following fusion of sarcoplasmic reticulum (SR) vesicles to an artificial bilayer, reconstituted Ca2+ channel activity is stimulated by nanomolar concentrations of rose bengal in the presence of a broad-spectrum light source. Rose bengal does not appear to affect K+ channels present in the SR. Following reconstitution of the sulfhydryl-activated 106-kDa Ca2+ channel protein into a bilayer, rose bengal activates the isolated protein in a light-dependent manner. Ryanodine at a concentration of 10 nM is shown to lock the 106-kDa channel protein in a subconductance state which can be reversed by subsequent addition of 500 nM rose bengal. This apparent displacement of bound ryanodine by nanomolar concentrations of rose bengal is also directly observed upon measurement of [3H]ryanodine binding to JSR vesicles. These observations indicate that photooxidation of rose bengal causes a stimulation of the Ca2+ release protein from skeletal muscle sarcoplasmic reticulum by interacting with the ryanodine binding site. Furthermore, similar effects of rose bengal on isolated SR vesicles, on single channel measurements following fusion of SR vesicles, and following incorporation of the isolated 106-kDa protein strongly implicates the 106-kDa sulfhydryl-activated Ca2+ channel protein in the Ca2+ release process.     

Properties of immunoaffinity purified 106-kDa Ca2+ release channels from the skeletal sarcoplasmic reticulum.

The sulfhydryl-gated 106-kDa Ca(2+)-release channel (SG-106) was purified by biotin-avidin chromatography from skeletal sarcoplasmic reticulum (SR) vesicles and used as an antigen to raise polyclonal antibodies. Western blots showed that the antisera crossreacted with the antigenic SG-106 and not with SR Ca2+, Mg(2+)-ATPase or with junctional foot proteins (JFPs) (Zaidi et al., 1989, J. Biol. Chem. 264(36), 21, 725-21, 736; 21, 737-21, 747). Polyclonal antibody-affinity columns were used to selectively purify SG-106-kDa proteins which, upon incorporation in planar bilayers, revealed the presence of a cationic channels with properties similar to "native" Ca(2+)-release channels obtained through the fusion of SR vesicles with planar bilayers. In agreement with measurements of Ca2+ release from SR vesicles, sulfhydryl oxidizing and reducing agents (i.e., 2,2'-dithiodipyridine and dithiothreitol) respectively increased and decreased the open-time probability of 106-kDa Ca(2+)-release channels. In contrast with reports on JFPs, ryanodine at 0.5-1 nM increased the open-time probability and at 2-10 nM locked 106-kDa Ca(2+)-release channels in a closed state rather than an open subconductance state. The SG-106 was activated by millimolar ATP, inhibited by millimolar Mg2+, and blocked by micromolar ruthenium red. Adriamycin (2-10 microM) caused a transient activation of SG-106 Ca(2+)-release channels, followed by closure in about 5 min, and intermittent activation to a subconductance state. Polyclonal antibodies used to purify the SG-106 also activated the channel when added to the cis side but not the trans side of the bilayer. Thus, SG-106 channels possess features that are similar to "native" SR Ca(2+)-release channels, are immunologically distinct from JFPs, and interact in seconds with nanomolar ryanodine in planar bilayers.     

Treatment of autoimmune thrombocytopenic purpura with rhesus antibodies (anti-Rh0(D)]

There is evidence that blockade of the reticuloendothelial system (RES) by sequestration of autologous red blood cells (RBC) leads to an elevation of platelet counts in immune thrombocytopenia. To substantiate this hypothesis, 10 Rh0(D)-positive adult patients (9 female, 1 male) with chronic autoimmune thrombocytopenic purpura (ITP) (1 to 21 years duration) were treated with low doses of intravenous IgG-anti-Rh0(D) (200 to 1,000 micrograms per dose; 300 to 3,600 micrograms per course; administration within 1 to 5 days). All patients improved clinically as indicated by cessation of bleeding. In eight out of ten patients there was a rise in platelet count. Platelet increments were excellent (greater than 100 X 10(9)/l) in one, good (50-100 X 10(9)/l) in three, fair (20-50 X 10(9)/1) in two and low (10-20 X 10(9)/1) in two patients. Splenectomized patients (N = 4) had a poorer response than non-splenectomized patients (N = 6) with mean increments of 16 X 10(9)/l (range 5-43 X 10(9)/l) versus 60 X 10(9)/l (range 10-110 X 10(9)/l). The increase in platelet counts persisted for seven to over 150 days. Transient and slight signs of haemolysis developed in seven out of ten patients (haemoglobin remained stable; increase of lactate dehydrogenase (greater than 250 IU/l) in four, decrease of haptoglobin (less than 60 mg/dl) in five patients). The direct antiglobulin test became positive in all cases due to IgG1 without complement fixation. We conclude that the interaction of antibody-coated RBC with macrophages (and, probably, other means of RBC alteration) is a feasible therapeutic approach in selected cases of ITP and related conditions.     

Disulfide linkage of biotin identifies a 106-kDa Ca2+ release channel in sarcoplasmic reticulum

Reactive disulfide reagents (RDSs) with a biotin moiety have been synthesized and found to cause Ca2+ release from sarcoplasmic reticulum (SR) vesicles. The RDSs oxidize SH sites on SR proteins via a thiol-disulfide exchange, with the formation of mixed disulfide bonds between SR proteins and biotin. Biotinylated RDSs identified a 106-kDa protein which was purified by biotin-avidin chromatography. Disulfide reducing agents, like dithiothreitol, reverse the effect of RDSs and thus promoted active re-uptake of Ca2+ and dissociated biotin from the labeled protein indicating that biotin was covalently linked to the 106-kDa protein via a disulfide bond. Several lines of evidence indicate that this protein is not Ca2+, Mg2+-ATPase and is not a proteolytic fragment or a subunit of the 400-kDa Ca2+-ryanodine receptor complex (RRC). Monoclonal antibodies against the ATPase did not cross-react with the 106-kDa protein, and polyclonal antibodies against the 106-kDa did not cross-react with either the ATPase or the 400-kDa RRC. RDSs did not label the 400-kDa RRC with biotin. Linear sucrose gradients used to purify the RRC show that the 106-kDa protein migrated throughout 5-20% linear sucrose gradients, including the high sucrose density protein fractions containing 400-kDa RRC. Protease inhibitors diisopropylfluorophosphate used to prevent proteolysis of 400-kDa proteins did not alter the migration of 106-kDa in sucrose gradients nor the patterns of biotin labeling of the 106-kDa protein. Incorporation of highly purified 106-kDa protein (free of RRC) in planar bilayers revealed cationic channels with large Na+ (gNa+ = 375 +/- 15 pS) and Ca2+ (gCa2+ = 107.7 +/- 12 pS) conductances which were activated by micromolar [Ca2+]free or millimolar [ATP] and blocked by micromolar ruthenium red or millimolar [Mg2+]. Thus, the SR contains a sulfhydryl-activated 106-kDa Ca2+ channel with apparently similar characteristics to the 400-kDa "feet" proteins.     

Reactive disulfides trigger Ca2+ release from sarcoplasmic reticulum via an oxidation reaction

Reactive disulfide compounds (RDSs) with a pyridyl ring adjacent to the S-S bond such as 2,2'-dithiodipyridine (2,2'-DTDP), 4,4'-dithiodipyridine, and N-succinimidyl 3(2-pyridyldithio)propionate (SPDP) trigger Ca2+ release from sarcoplasmic reticulum (SR) vesicles. They are known to specifically oxidize free SH sites via a thiol-disulfide exchange reaction with the stoichiometric production of thiopyridone. Thus, the formation of a mixed S-S bond between an accessible SH site on an SR protein and a RDS causes large increases in SR Ca2+ permeability. Reducing agents, glutathione (GSH) or dithiothreitol reverse the effect of RDSs and permit rapid re-uptake of Ca2+ by the Ca2+, Mg2+-ATPase. The RDSs, 2,2'-DTDP, 4,4'-dithiodipyridine and SPDP displaced [3H]ryanodine binding to the Ca2+-receptor complex at IC50 values of 7.5 +/- 0.2, 1.5 +/- 0.1, and 15.4 +/- 0.1 microM, respectively. RDSs did not alter the rapid initial phase of Ca2+ uptake by the pump, stimulated ATPase activity, and induced release from passively loaded vesicles with nonactivated pumps; thus they act at a Ca2+ release channel and not at the Ca2+, Mg2+-ATPase. Efflux rates increased in 0.25-1.0 mM [Mg2+]free then decreased in 2-5 mM [Mg2+]free. Adenine nucleotides inhibited the oxidation of SHs on SR protein by RDSs and thus reduced Ca2+ efflux rates. However, once RDSs oxidized these SH sites and opened the Ca2+ release pathway, subsequent additions of nucleotides stimulated Ca2+ efflux. In skinned fibers, 2,2'-dithiodipyridine elicited rapid twitches which were blocked by ruthenium red. These results indicate that RDSs trigger Ca2+ release from SR by oxidizing a critical SH group, and thus provide a method to covalently label the protein(s) involved in causing these changes in Ca2+ permeability.     

Improved method for the isolation of Campylobacter jejuni and Campylobacter coli bacteriophages

A centrifugation and filtration method of isolating Campylobacter phages has been developed. Forty-nine Campylobacter phages were isolated from 272 effluent samples of which 42 produced lysis with Campylobacter jejuni strains and seven with C. coli strains. Phages were recovered from pig manure, abattoir effluents, human faeces, sewage and poultry manure. Phages were not isolated from water samples, cattle and sheep faeces or farm pasture soil.