Mesenchymal stromal-cell transplants induce oligodendrocyte progenitor migration and remyelination in a chronic demyelination model

Demyelinating disorders such as leukodystrophies and multiple sclerosis are neurodegenerative diseases characterized by the progressive loss of myelin that may lead toward a chronic demyelination of the brain''s white matter, impairing normal axonal conduction velocity and ultimately causing neurodegeneration. Current treatments modifying the pathological mechanisms are capable of ameliorating the disease; however, frequently, these therapies are not sufficient to repress the progressive demyelination into a chronic condition and permanent loss of function. To this end, we analyzed the effect that bone marrow-derived mesenchymal stromal cell (BM-MSC) grafts exert in a chronically demyelinated mouse brain. As a result, oligodendrocyte progenitors were recruited surrounding the graft due to the expression of various trophic signals by the grafted MSCs. Although there was no significant reaction in the non-grafted side, in the grafted regions oligodendrocyte progenitors were detected. These progenitors were derived from the nearby tissue as well as from the neurogenic niches, including the subependymal zone and dentate gyrus. Once near the graft site, the cells matured to myelinating oligodendrocytes. Finally, electrophysiological studies demonstrated that axonal conduction velocity was significantly increased in the grafted side of the fimbria. In conclusion, we demonstrate here that in chronic demyelinated white matter, BM-MSC transplantation activates oligodendrocyte progenitors and induces remyelination in the tissue surrounding the stem cell graft.     

The Domestication Syndrome in Phoenix dactylifera Seeds: Toward the Identification of Wild Date Palm Populations

Investigating crop origins is a priority to understand the evolution of plants under domestication, develop strategies for conservation and valorization of agrobiodiversity and acquire fundamental knowledge for cultivar improvement. The date palm (Phoenix dactylifera L.) belongs to the genus Phoenix, which comprises 14 species morphologically very close, sometimes hardly distinguishable. It has been cultivated for millennia in the Middle East and in North Africa and constitutes the keystone of oasis agriculture. Yet, its origins remain poorly understood as no wild populations are identified. Uncultivated populations have been described but they might represent feral, i.e. formerly cultivated, abandoned forms rather than truly wild populations. In this context, this study based on morphometrics applied to 1625 Phoenix seeds aims to (1) differentiate Phoenix species and (2) depict the domestication syndrome observed in cultivated date palm seeds using other Phoenix species as a “wild” reference. This will help discriminate truly wild from feral forms, thus providing new insights into the evolutionary history of this species. Seed size was evaluated using four parameters: length, width, thickness and dorsal view surface. Seed shape was quantified using outline analyses based on the Elliptic Fourier Transform method. The size and shape of seeds allowed an accurate differentiation of Phoenix species. The cultivated date palm shows distinctive size and shape features, compared to other Phoenix species: seeds are longer and elongated. This morphological shift may be interpreted as a domestication syndrome, resulting from the long-term history of cultivation, selection and human-mediated dispersion. Based on seed attributes, some uncultivated date palms from Oman may be identified as wild. This opens new prospects regarding the possible existence and characterization of relict wild populations and consequently for the understanding of the date palm origins. Finally, we here describe a pipeline for the identification of the domestication syndrome in seeds that could be used in other crops.     

STRUCTURE AND FUNCTION OF BENTHIC ALGAL COMMUNITIES IN AN EXTREMELY ACID RIVER1

The composition of algal species and pigments and the structural and functional characteristics of the algal community were investigated in an acid stream of southwestern Spain, the Río Tinto. The algal community had low diversity and showed few seasonal differences. It was mainly made up of Klebsormidium flaccidum Kütz. (Silva, Mattox & Blackwell) that produced long greenish or purplish filaments, Pinnularia acoricola Hust. (producing brown patches) and Euglena mutabilis Schmitz. The algal filaments made up a consistent biofilm that also included fungal hyphae, iron bacterial sheaths, diatoms, and mineral particles. HPLC analyses on Río Tinto samples showed that undegraded chl accounted for 67% of the total chl in the filamentous patches but were a minority in the brown patch (2.6%). The brown patch had a concentration of carotenoids eight times lower than that observed in the green patch. When chl concentrations were weighted for the proportion of the different patches on the streambed, undegraded chl a accounted for 89.2 mg chl a·m ^{? 2} of stream surface area (5.4 g C·m ^{? 2}). This high algal biomass was supported by relatively high nutrient concentrations and by a high phosphatase activity (V_max = 137.7 nmol methylumbelliferyl substrate·cm ^{? 2}·h ^{? 1} 1 Received 15 July 2002. Accepted 17 February 2003. , K_m = 0.0045 μM). The remarkable algal biomass in Río Tinto potentially contributed to the bacterial–fungal community and to the macroinvertebrate community and emphasizes the role that the algae may have in the organic matter cycling and energy flow in extreme systems dominated by heterotrophic microorganisms.     

Minimally invasive silicon probe for electrical impedance measurements in small animals

It is commonly accepted that electrical impedance provides relevant information about the physiological condition of living tissues. Currently, impedance measurements are performed with relatively large electrodes not suitable for studies in small animals due to their poor spatial resolution and to the damage that they cause to the tissue. A minimally invasive needle shaped probe for electrical impedance measurements of living tissues is presented in this paper. This micro-probe consists of four square platinum electrodes (300 microm x 300 microm) on a silicon substrate (9 mm x 0.6 mm x 0.5 mm) and has been fabricated by using standard Si microelectronic techniques. The electrodes are not equally spaced in order to optimise the signal strength and the spatial resolution. Characterisation data obtained indicate that these probes provide high spatial resolution (measurement radius <4 mm) with a useful wide frequency band going from 100 Hz to 100 kHz. A series of in vivo experiments in rat kidneys subjected to ischemia was performed to demonstrate the feasibility of the probes and the measurement system. The impedance modulus and phase were measured at 1 kHz since this frequency is sufficiently low to permit the study of the extracellular medium. The extracellular pH and K+ were also simultaneously measured by using commercial miniaturised Ion Selective Electrodes. The induced ischemia period (45 min) resulted in significant changes of all measured parameters (Delta/Z/ approximately 65%; DeltapH approximately 0.8; DeltaK+ approximately 30 mM).     

Performance of a mobile mechanical screen to improve the commercial quality of wood chips for energy

The study analyzed the performance of a mobile screening device for upgrading coarse wood chips to residential user standards, by removing oversize particles and fines. The machine was designed for transportation to forest landings, logistic terminals and plant chip yards. Average productivity was 1.9 oven-dry tons (odt) h⁻¹, corresponding to a screening cost of 28.5 € odt⁻¹. This figure was lower than the price increase obtained by upgrading industrial chips to residential user standards. Hence, screening offered a profit of 4.7 € odt⁻¹, or 16% of the original screening cost. The screening process was capable of upgrading chips from industrial to residential specifications, by reducing the incidence of oversize particles below the 1% critical threshold. Screening also allowed a substantial reduction in the content of fines. A similar effect was not verified for crushed wood, which failed to meet the specifications for residential fuel.     

An inverse correlation between stress resistance and stuck fermentations in wine yeasts. A molecular study.

During alcoholic fermentations yeast cells are subjected to several stress conditions and, therefore, yeasts have developed molecular mechanisms in order to resist this adverse situation. The mechanisms involved in stress response have been studied in Saccharomyces cerevisiae laboratory strains. However a better understanding of these mechanisms in wine yeasts could open the possibility to improve the fermentation process. In this work an analysis of the stress response in three wine yeasts has been carried out by studying the expression of several representative genes under several stress conditions which occur during fermentation. We propose a simplified method to study how these stress conditions affect the viability of yeast cells. Using this approach an inverse correlation between stress-resistance and stuck fermentations has been found. We also have preliminary data about the use of the HSP12 gene as a molecular marker for stress-resistance in wine yeasts.     

Date Palm Agrobiodiversity (<Emphasis Type="Italic">Phoenix dactylifera</Emphasis> L.) in Siwa Oasis,Egypt: Combining Ethnography,Morphometry, and Genetics

We evaluate date palm (Phoenix dactylifera L.) agrobiodiversity of Siwa oasis, Egypt, located at the crossroads of ancient Trans-Saharan routes, focusing on diversity both as expressed and maintained by the folk categorization system of Siwa inhabitants (through an ethnographic analysis) and as described by genetic sciences and a morphometric tool based on size and geometry of seeds. We verified that some named types are true cultivars, sharing not only a formal identity, important for Isiwan people, but also a genetic identity. However, we also confirm the existence of “ethnovarieties,” i.e., voluntary collections of multiple clones sharing phenotypic characteristics with the same local name, suggesting the genetic richness is higher than the apparent agrobiodiversity estimated by a superficial ethnobotanical approach. Finally, our research offers new insights on the relative importance of feral and cultivated date palms.     

Halogenated derivatives of boldine with high selectivity for alpha1A-adrenoceptors in rat cerebral cortex

The selectivity of 3-nitrosoboldine and different halogenated derivatives of boldine (3-bromoboldine, 3,8-dibromoboldine and 3-chloroboldine) for alpha1-adrenoceptor subtypes was studied by examining [3H]-prazosin competition binding in rat cerebral cortex. In the competition experiments [3H]-prazosin binding was inhibited completely by all the compounds tested. The inhibition curves displayed shallow slopes which could be subdivided into high and low affinity components. The relative order of affinity and selectivity for alpha1A-adrenoceptors was 3-bromoboldine = 3,8-dibromoboldine = 3-chloroboldine > boldine > 3-nitrosoboldine. The competition curves for 3-bromoboldine remained shallow and biphasic following chloroethylclonidine treatment. Whereas the relative contribution of the high affinity sites increased, the 3-bromoboldine affinities at its high and low affinity sites remained similar to those obtained in untreated membranes. 3-Bromoboldine, 3,8-dibromoboldine, 3-chloroboldine and 3-nitrosoboldine did not significantly displace [3H]-(+)-cis-diltiazem binding to rat cerebral cortex membranes. This activity was lower than that shown by boldine. Compared to boldine, halogen (bromine or chlorine) substitution at position 3 increases the alpha1A-adrenoceptor subtype selectivity and decreases the affinity for the benzothiazepine binding site at the calcium channel. Further halogen substitution at position 8 did not significantly improve this activity with respect to 3-bromoboldine. In contrast, the NO substitution at position 3 of boldine (3-nitrosoboldine) gives a loss of affinity and selectivity for alpha1-adrenoceptor subtypes.     

Community composition and sensitivity of periphyton to atrazine in flowing waters: the role of environmental factors

The relationship between environmental variables, community composition and the sensitivity of periphyton on artificial substrata to the herbicide atrazine (EC₅₀ values obtained by concentration-effect curves of photosynthesis to atrazine) was studied for 20 stream and river sites on a latitudinal across Europe (Sweden, The Netherlands, Spain). Sensitivity to atrazine was higher in Swedish than in the Spanish or Dutch sites. Direct gradient analyses were used to relate diatom taxa and algal groups with environmental variables. A first redundancy analysis (RDA) based on diatom taxa showed a pollution gradient (atrazine and nutrient concentration) associated to diatom taxa that are indicators of different degrees of pollution. A second RDA based on algal groups showed that diatom-dominated communities corresponded both to sites at higher altitudes and less industrialized areas and to sites with higher atrazine concentration; Cyanobacteria were the most common in industrial areas, whereas Chlorophyceae dominated in sites with high water temperature and alkalinity. Linear regression analyses were applied to find the relationship between the ordination axes obtained and the EC₅₀ values. First axes of both RDA showed significant or marginally significant relationship with atrazine sensitivity. Regression analyses for the Spanish sites indicated that the sensitivity to atrazine was related with light conditions (EC₅₀ was positively correlated with light) and the percentage of different algal groups (EC₅₀ was positively correlated with the percentage of diatoms and negatively correlated with the percentage of green algae). The results indicating that differences in sensitivity are related to environmental variables such as light, nutrients or atrazine concentration, permitted us to identify biological indicators of sensitivity to atrazine in lotic systems: Bacillariophyceae-dominated periphyton communities were more tolerant than Chlorophyceae and Chrysophyceae-dominated communities. In addition, diatom taxa found to be tolerant to atrazine in this study have been considered in the literature to be tolerant to organic pollution. This revised version was published online in June 2006 with corrections to the Cover Date.