Prenatal development of monoamine neurons in the rat]

The histofluorescence method allows the study of the prenatal development of monoamines neurons in the foetal rat brain. Certain patterns of this development can be defined: the locus niger and the raphe appears fluorescent on the 14th day, the locus coeruleus on the 15th day. These systems differentiate independently in various areas of the neural axis. Their maturation are progressive: first for the DA system, then for the NA and the 5 HT systems. The mechanisms for synthesis and storage of amines precede the complete development of the effector structures.     

Ecological niche differentiation in peripheral populations: a comparative analysis of eleven Mediterranean plant species

The ‘central‐peripheral’ hypothesis has provided a baseline for many studies of population dynamics and genetic variability at species distribution limits. Although peripheral populations are often assumed to occur in ecologically marginal conditions, little is known about whether they effectively occur in a distinct ecological niche. A cross‐taxa analysis of 11 Mediterranean vascular plants were studied. We quantified variation in the ecological niche between populations at the northern range limits of species in Mediterranean France and those in the central part of the distribution in continental Spain or Italy in 2013–2014. We analyzed both the macro‐ecological niche where populations occur in terms of broad habitat and altitudinal range and the micro‐ecological niche where individual plants grow in terms of soil and structural biotic and abiotic characteristics. Most species occur in a single broad habitat type common to central and peripheral populations and have a narrower altitudinal range in the latter. In contrast, for the micro‐ecological niche we detected marked variation in several niche parameters among central and peripheral populations. Although many differences are species‐specific some are common to several species. We found a trend towards narrower micro‐niche breadth in peripheral populations. Our results illustrate the importance of studying the precise ecological characteristics where plants grow and the pertinence of a multi‐species approach to correctly assess niche variation. The ecological originality of peripheral populations underlines their evolutionary potential and conservation significance.     

PI3K–Akt signaling controls PFKFB3 expression during human T-lymphocyte activation

It is commonly accepted that brain phospholipids are highly enriched with long-chain polyunsaturated fatty acids (PUFAs). However, the evidence for this remains unclear. We used HPLC–MS to analyze the content and composition of phospholipids in rat brain and compared it to the heart, kidney, and liver. Phospholipids typically contain one PUFA, such as 18:2, 20:4, or 22:6, and one saturated fatty acid, such as 16:0 or 18:0. However, we found that brain phospholipids containing monounsaturated fatty acids in the place of PUFAs are highly elevated compared to phospholipids in the heart, kidney, and liver. The relative content of phospholipid containing PUFAs is ~ 60% in the brain, whereas it is over 90% in other tissues. The most abundant species of phosphatidylcholine (PC) is PC(16:0/18:1) in the brain, whereas PC(18:0/20:4) and PC(16:0/20:4) are predominated in other tissues. Moreover, several major species of plasmanyl and plasmenyl phosphatidylethanolamine are found to contain monounsaturated fatty acid in the brain only. Overall, our data clearly show that brain phospholipids are the least enriched with PUFAs of the four major organs, challenging the common belief that the brain is highly enriched with PUFAs.     

Environmental profile of Spanish porcelain stoneware tiles

Purpose

Porcelain stoneware tile (PST) is currently the ceramic tile of greatest commercial and innovation interest. An environmental life cycle assessment of different varieties of PST was undertaken to enable hotspots to be identified, strategies to be defined, differences between PST varieties to be evaluated and guidance for PST manufacturers to be provided in choosing the Environmental Product Declaration (EPD) programme that best suited their needs according to grouping criteria.

Methods

Analysis of previous information allowed three main parameters (thickness, glaze content and mechanical treatment) to be identified in order to encompass all PST variations. Fifteen varieties of PST were thus studied. The coverage of 1 m² of household floor surface with the different PST varieties for 50 years was defined as functional unit. The study sets out environmental data whose traceability was verified by independent third parties for obtaining 14 EPDs of PST under Spanish EPD programmes.

Results and discussion

The study presents PST inventory analysis and environmental impact over the entire life cycle of the studied PST varieties. The natural gas consumed in the manufacturing stage accounted for more than 70% abiotic depletion–fossil fuels and global warming; electricity consumption accounted for more than 60% ozone layer depletion, while the electricity generated by the cogeneration systems avoided significant environmental impacts in the Spanish power grid mix. The variations in PST thickness, amount of glaze and mechanical treatments were evaluated. The PST variety with the lowest environmental impact was the one with the lowest thickness, was unglazed and had no mechanical treatments. Similarly, the PST variety with the highest environmental impact was the one with the greatest thickness, was glazed and had been mechanically treated.

Conclusions

The PST life cycle stage with the highest environmental impact was the manufacturing stage. The main hotspots found were production and consumption of energy and raw materials extraction. Variation in thickness was a key factor that proportionally influenced almost all studied impact categories; the quantity of glaze strongly modified abiotic depletion–elements and eutrophication, while the mechanical treatments contributed mainly to ozone depletion. The study of all PST varieties led to the important conclusion, against the current trend, that differences among them were found to be so significant that declaring a number of PSTs within the same EPD is not directly possible, and it needs preliminary verification to ensure compliance with the product category rule.

     

Photosynthetic responses of Coffea arabica leaves to a short-term high light exposure in relation to N availability

It is known that the coffee (Coffea arabica L.) plant which is originally from shade habitats would have a limited ability to grow under full sun. Previous work has shown that nitrogen fertilisation can reduce the leaf damage when the plants are exposed to high light intensities during several days. In the present work we aimed to study the effects of the high irradiance during the first hours and evaluate the positive contribution of nitrogen fertilisation in the case of short-term exposure to strong light. Young plants (1.5–2 years old) grown in 1.5 kg of a mixed soil were supplemented with a nutrient solution containing 15 mM nitrogen in the form of NH₄NO₃, every 7 days (2N treatment), 15 days (1N treatment) and 45 days (0N treatment). Top mature leaves were exposed to a photosynthetic photon flux density of 1 500 μmol m^?2 s^?1 for a maximal period of 8 h, and changes in photosynthesis and pigment composition were monitored along the period of high light exposure. Photosynthetic capacity, leaf conductance to water vapour, electron transport capacity and maximum carboxylation activity, as well as some leaf fluorescence parameters (minimal fluorescence, photochemical efficiency of PSII and quantum yield of photosynthetic electron transport) were reduced by the stress, with a generally stronger impact observed in the 0N plants. The photochemical quenching was affected only in the 0N plants, while the non-photochemical quenching increased in 2N plants but decreased in the 0N ones. The results showed that 2N plants presented a better initial status of the photosynthetic parameters and of the content of photoprotective pigments. Those plants showed ability to trigger some protective mechanisms, as observed by the tendency to increase the xanthophyll pool content, specially in zeaxanthin and in non-photochemical quenching. Also, protein content presented a tendency to increase after 1.5 h, which was maintained until the end of the high light period. We conclude that nitrogen availability is a key factor in the acclimation process to high light.     

Cloning and characterization of a transposable-like repeat in the heterochromatin of the darkling beetle Misolampus goudoti.

A long repeat unit of the PstI family in Misolampus goudoti (Coleoptera, Tenebrionodae) is characterized in this work. The 30 sequenced units have small differences in length (consensus 1169 bp), but very similar nucleotide composition (mean 61.1% A+T). PstI repeats contain a 36-bp-long inverted repeat at both the 5' and 3' ends, with a fully conserved 16-bp-long motif similar to those found in class II transposable elements. However, the transposable-like PstI repeats seems to be defective, since they do not encode for any protein related with transposition. Interestingly, energetically stable hairpins resembled the structure of a miniature interspersed transposable element, suggesting that the PstI satellite DNA family in M. goudoti may have originated from an ancestral active transposable element as also described in Drosophila guanche. The presence of transposable-like structure along with the non-detection of gene conversion or unequal crossing-over events suggest that transposition could be one of the putative molecular mechanisms involved in the strong amplification and (or) homogenization of these repeats. A putative transposition of PstI repeats allowing their genomic mobility also could explain why this satellite is widely distributed to all heterochromatic regions, telomeres, pericentromeric regions, and on the Y chromosome, whereas satellites of other tenebrionids lacking transposable-like structures are restricted only to pericentromeric regions.     

Carbon Fixation, Ammonium Uptake and Regeneration in an Equatorial Lake: Biological Versus Physical Control

Ammonium uptake and regeneration were measured in the euphoticzone of Petit Saut Lake, French Guyana, to examine nitrogencycling in this recently flooded equatorial forest environment.Am-monium regeneration rates were extremely high (mostly inthe range 1–6 µmol N l^–1 h^–1), and aredue to the very high grazing rates of the microzooplankton,which consumed between 56 and 95% of the phytoplankton productionin any given incubation. These regeneration rates were aboutan order of magnitude higher than the net ammonium uptake rates.This imbalance is probably due to dissolved organic nitrogenrelease during grazing. At the bottom of the euphotic zone (4–5m), photosynthetic bacteria are responsible for ammonium uptake.Diffusion-driven ammonium fluxes are an order of magnitude lowerthan biologically driven fluxes. Therefore, ammonium fluxesare dominated by biology rather than by physics in this lake.     

Thrombin-induced contraction in alveolar epithelial cells probed by traction microscopy.

Contractile tension of alveolar epithelial cells plays a major role in the force balance that regulates the structural integrity of the alveolar barrier. The aim of this work was to study thrombin-induced contractile forces of alveolar epithelial cells. A549 alveolar epithelial cells were challenged with thrombin, and time course of contractile forces was measured by traction microscopy. The cells exhibited basal contraction with total force magnitude 55.0 +/- 12.0 nN (mean +/- SE, n = 12). Traction forces were exerted predominantly at the cell periphery and pointed to the cell center. Thrombin (1 U/ml) induced a fast and sustained 2.5-fold increase in traction forces, which maintained peripheral and centripetal distribution. Actin fluorescent staining revealed F-actin polymerization and enhancement of peripheral actin rim. Disruption of actin cytoskeleton with cytochalasin D (5 microM, 30 min) and inhibition of myosin light chain kinase with ML-7 (10 microM, 30 min) and Rho kinase with Y-27632 (10 microM, 30 min) markedly depressed basal contractile tone and abolished thrombin-induced cell contraction. Therefore, the contractile response of alveolar epithelial cells to the inflammatory agonist thrombin was mediated by actin cytoskeleton remodeling and actomyosin activation through myosin light chain kinase and Rho kinase signaling pathways. Thrombin-induced contractile tension might further impair alveolar epithelial barrier integrity in the injured lung.     

2-methoxyestradiol,an endogenous metabolite of 17b-estradiol,inhibits adipocyte proliferation

The effects of 2-methoxyestradiol (2ME), a naturally occurring mammalian metabolite of 17 -estradiol, on adipocyte growth has been investigated in mouse brown adipose tissue precursor cells developed in primary culture. 2ME inhibits brown adipocyte proliferation in a dose-response manner (IC50 = 1.7 × 10-6 M for DNA synthesis), with much higher potency than its hormone precursor 17-estradiol, and cells acquire the typical differentiated morphology - more round with a higher content of triglycerides. 2ME causes similar effects in the immortal brown adipocyte tumor-derived hibernoma cell line HIB 1B and the immortal 3T3-F442A white adipocyte line. These findings suggest a possible role for 2ME in adipocyte proliferation, and probably in the differentiation process, entering the cells in the adipogenic program.