Protein kinase C beta and prolyl isomerase 1 regulate mitochondrial effects of the life-span determinant p66Shc

The 66-kilodalton isoform of the growth factor adapter Shc (p66Shc) translates oxidative damage into cell death by acting as reactive oxygen species (ROS) producer within mitochondria. However, the signaling link between cellular stress and mitochondrial proapoptotic activity of p66Shc was not known. We demonstrate that protein kinase C beta, activated by oxidative conditions in the cell, induces phosphorylation of p66Shc and triggers mitochondrial accumulation of the protein after it is recognized by the prolyl isomerase Pin1. Once imported, p66Shc causes alterations of mitochondrial Ca2+ responses and three-dimensional structure, thus inducing apoptosis. These data identify a signaling route that activates an apoptotic inducer shortening the life span and could be a potential target of pharmacological approaches to inhibit aging.     

Measurement of xylem translocation of weak electrolytes with the pressure chamber technique

Xylem translocation and root uptake of weak electrolytes were investigated with the pressure chamber technique (PCT) using de-topped soybean plants. Two compounds were organic bases (fenpropimorph and imazalil) and four were organic acids (bentazone, primisulfuron-methyl, rimsulfuron and triasulfuron). The compounds covered a wide range of log KOW and pKa values. Concentrations in external solution and in xylem sap were measured by HPLC at pH values in external solution of 4.5, 6.5 and 8.5. For weak bases, translocation was higher at low pH and the transpiration stream concentration factors (TSCF) were in the range 0.31-0.95. At pH 8.5, the concentrations in leaking xylem sap were very low for fenpropimorph, and steady-state was probably not reached. For weak acids, TSCF values derived with external pH from 4.5 to 8.5 were in the range 0.55-1.50 for primisulfuron-methyl, 0.64-1.35 for rimsulfuron, 0.81-0.93 for triasulfuron and 0.69-0.92 for bentazone. The variation of TSCF of the weak electrolytes was much smaller in these PCT experiments than in recent experiments with intact plants. The likely reason is that de-topped soybean plants in the pressure chamber seemed to be unable to regulate their xylem sap pH, which was almost identical to the pH in external solution. Without pH differences, the ion-trap process, which is responsible for accumulation or exclusion of weak acids and bases in the xylem of living plants, does not take place. Model simulations carried out for intact and de-topped plants supported this hypothesis. By variation of the pH of the xylem sap, good agreement between measurements and simulations could be achieved.     

Summer-grown seed potatoes: an attempt to produce seed for the spring season in Israel

Seed potatoes were grown in Israel during summer (June-October) at Ramat haNegev (the Negev plateau). This is the hottest season in the semi-arid climate prevailing in the region. Because of the high temperature, no tuberization occurred in cv. ‘Up-to-Date; and ‘Draga’ and ‘Cara’ showed a marked yield reduction. Reasonable yields were, however, obtained at Ramat haNegev during summer growth with the cvs. ‘Désirée’, ‘Blanka’, ‘Spunta’ and ‘Alpha’. At Bet Dagan (coastal plain) Désirée grown during summer met with many problems and yields were negligible, probably because of the higher night temperature as compared with Ramat haNegev. Growth during summer in Ramat haNegev offers the advantages of relative isolation from other potato fields (potatoes are not grown in summer) and low aphid activity, in contrast to the common growing seasons — spring and autumn. Insecticide application and planting high quality seeds — imported elite or Class A — in summer, reduced potato leaf roll virus (PLRV) infection to an average of 4.5% in 1984 and 1.8% in 1985, in comparison with an average of 20.8% in 1979, when poor quality seeds were used and no insecticides were applied. Infection with potato virus Y (PVY) was 1.7% in 1984 and 0.1% in 1985. The yielding capacity in spring 1980 of seed potato produced at Ramat haNegev in the summer of 1979, was significantly lower than that of imported and Golan Heights seed. This is attributed mainly to the high level of virus infection of the former seeds. PLRV-free seed potatoes from the same batch yielded similarly to imported seed potatoes or seed potatoes from the Golan Heights. This was reconfirmed in the 1985 experiment in which Ramat haNegev seeds were much less infected with PLRV and produced yields similar to the imported and Golan ones. Seed potatoes from Ramat haNegev behave like young seeds when planted in the spring. Therefore, their yielding capacity probably increases the earlier the harvest and the longer the subsequent growing period.     

Qualitative modelling for the development of a sustainable management strategy for the Peruvian scallop Argopecten purpuratus (Lamarck 1819)

• 1. This study is the first attempt using Levins's Theory (loop analysis) in order to develop a sustainable management for the scallop, Argopecten purpuratus, fishery in Peru during El Niño‐Southern Oscillation events (ENSO) and upwelling conditions. Based on this theoretical framework, it was possible to estimate the local stability for each of these model systems and to follow the qualitative changes of the variables in response to external factors.
• 2. Based on our results, we suggest the following management policies to be implemented: (1) during ENSO events the size at the first capture of the scallops should be >70 mm and (2) the increase in the number of fishermen during ENSO events must be prevented. Both measures increase the sustainability of fishery under ENSO and upwelling conditions. The ecological models predict that during ENSO and upwelling events, any management strategy to increase the recruitment of the scallop would not have a positive impact on the adult stock.
• 3. Finally, we suggest that more efforts must be focused on the development of extended eco‐social models, which incorporate further social and economic variables, increasing realism of the abstractions for this fishery activity.

Copyright © 2002 John Wiley & Sons, Ltd.     

Cycloartane saponins from Astragalus peregrinus as modulators of lymphocyte proliferation

From Astragalus peregrinus, four cycloartane-type saponins have been isolated and their structures elucidated by spectral means as 20(R),24(S)-epoxy-9β,19-cyclolanostane-3β,6α,16β,25-tetrol 3-O-β- -glucopyranoside (1), 20(R),24(S)-epoxy-9β,19-cyclolanostane-3β,6α,16β,25-tetrol 3-O-α- -rhamnopyranosyl-(1→4)-β- -glucopyranoside (2), 20(R),24(S)-epoxy-9β,19-cyclolanostane-3β,6α,16β,25-tetrol 3-O-α- -rhamnopyranosyl-(1→2)-β- -glucopyranoside (3) and 20(R),25-epoxy-9β,19-cyclolanostane-3β,6α,16β,24(S)-tetrol (24-O-acetyl)- 3-O-α- -rhamnopyranosyl-(1→2)-(6′-O-acetyl)-β- -glucopyranoside (4). Compounds 2 and 3 showed to stimulate the proliferation of mouse splenocytes and were not significantly cytotoxic.     

A micromorphological index of soil development for the Quaternary geology research

Profile development indices of Harden [Harden, J.W., 1982. A quantitative index of soil development from field: examples from a chronosequence in Central California. Geoderma 285, 1–98] and Ferrari and Magaldi [Ferrari, G., Magaldi, D., 1983. Significato ed applicazioni della paleopedologia nella stratigrafia del Quaternario. Boll. Mus. Civ. St. Nat. Verona 10, 315–340] have shown their utility for comparative dating of some paleosols during geomorphological and geological surveys. In Italy and other countries, pedostratigraphic methods have been commonly applied to soil profiles formed in continental formations. Unfortunately, buried and relict paleosols are very scarce or badly preserved in some areas of Italy due to past and recent tectonic activity and to strong human impact dating back to prehistoric times.In order to use relict paleosols for correct chronostratigraphic interpretation of relict paleosols and in order to correlate them with old landscape forms for the reconstruction of Quaternary sequences, a new micromorphological index (MISODI) for assessing soil development and degree of weathering was devised. The index was tested in the extensional tectonic basin of L'Aquila-Scoppito (Abruzzi, Central Italy) where some chronostratigraphic information is available.Results demonstrate that there is a good relationship between presumed relative age of paleosols and degree of weathering and pedogenesis in B and B/C horizons as assessed by this index. The index has the potential to be adapted for application to other paleosol types in other countries.     

A distinct CDV genotype causing a major epidemic in Alpine wildlife

Canine distemper virus (CDV) infection represents an important conservation threat to many carnivore species and has contributed to the population decline of several wild terrestrial and aquatic mammalian species. Since 2006, the Alpine region of North-Eastern (NE) Italy has been experiencing a severe and widespread outbreak of CDV affecting the wild carnivore population. In this study we performed an extensive phylogenetic and molecular evolutionary analysis of CDV identified during the recent wildlife epidemic in the Alpine region. Our analysis yielded data on the evolutionary dynamics of the Alpine wildlife CDV epidemic and revealed the emergence and spread of a single genetic cluster of CDV. The wide distribution of the novel cluster combined with the identification of a specific amino acid mutation, which is believed to increase the ability of the virus to replicate in a wider host range, raises concerns over the possible implications of the spread of this virus on the conservation of endangered wildlife species.     

Effect of Azospirillum inoculants on arbuscular mycorrhiza establishment in wheat and maize plants

Plant growth-promoting rhizobacteria and arbuscular mycorrhizal (AM) fungi represent two main groups of beneficial microorganisms of the rhizosphere. The role of different strains of Azospirillum on AM fungi development was evaluated by measuring the percentage of AM colonisation of the root system in durum wheat and maize plants, grown under both greenhouse and field conditions. The effect of wild-type Azospirillum brasilense strain Sp245 and genetically modified (GM) derivatives overproducing indole-3-acetic acid was assessed at greenhouse level in (1) three different cultivars of durum wheat, in the presence of indigenous AM fungi and (2) maize plants artificially inoculated with Glomus mosseae and Glomus macrocarpum. In addition, the establishment of natural AM fungal symbiosis was evaluated using Azospirillum lipoferum CRT1 in maize plants at field level. Despite the stimulatory effect of the different Azospirillum inocula on root growth, no significant differences in AM colonisation were found, independently of the AM fungus involved, either in wheat or in maize plants. Similarly, GM A. brasilense, which strongly stimulates root development, did not affect AM formation. Although these results were obtained in conditions in which the mycorrhization rate was moderate (15–30%), overall considered they indicate that the use of wild-type or GM Azospirillum phytostimulators does not alter mycorrhization.     

Ecological niche partitioning between Anopheles gambiae molecular forms in Cameroon: the ecological side of speciation

Background  

Speciation among members of the Anopheles gambiae complex is thought to be promoted by disruptive selection and ecological divergence acting on sets of adaptation genes protected from recombination by polymorphic paracentric chromosomal inversions. However, shared chromosomal polymorphisms between the M and S molecular forms of An. gambiae and insufficient information about their relationship with ecological divergence challenge this view. We used Geographic Information Systems, Ecological Niche Factor Analysis, and Bayesian multilocus genetic clustering to explore the nature and extent of ecological and chromosomal differentiation of M and S across all the biogeographic domains of Cameroon in Central Africa, in order to understand the role of chromosomal arrangements in ecological specialisation within and among molecular forms.     

Characterization of Palytoxin Binding to HaCaT Cells Using a Monoclonal Anti-Palytoxin Antibody

Palytoxin (PLTX) is the reference compound for a group of potent marine biotoxins, for which the molecular target is Na⁺/K⁺-ATPase. Indeed, ouabain (OUA), a potent blocker of the pump, is used to inhibit some PLTX effects in vitro. However, in an effort to explain incomplete inhibition of PLTX cytotoxicity, some studies suggest the possibility of two different binding sites on Na⁺/K⁺-ATPase. Hence, this study was performed to characterize PLTX binding to intact HaCaT keratinocytes and to investigate the ability of OUA to compete for this binding. PLTX binding to HaCaT cells was demonstrated by immunocytochemical analysis after 10 min exposure. An anti-PLTX monoclonal antibody-based ELISA showed that the binding was saturable and reversible, with a K_d of 3 × 10⁻¹⁰ M. However, kinetic experiments revealed that PLTX binding dissociation was incomplete, suggesting an additional, OUA-insensitive, PLTX binding site. Competitive experiments suggested that OUA acts as a negative allosteric modulator against high PLTX concentrations (0.3–1.0 × 10⁻⁷ M) and possibly as a non-competitive antagonist against low PLTX concentrations (0.1–3.0 × 10⁻⁹ M). Antagonism was supported by PLTX cytotoxicity inhibition at OUA concentrations that displaced PLTX binding (1 × 10⁻⁵ M). However, this inhibition was incomplete, supporting the existence of both OUA-sensitive and -insensitive PLTX binding sites.