Bioconversion of dilute-acid pretreated sorghum bagasse to ethanol by Neurospora crassa

Bioethanol production from sweet sorghum bagasse (SB), the lignocellulosic solid residue obtained after extraction of sugars from sorghum stalks, can further improve the energy yield of the crop. The aim of the present work was to evaluate a cost-efficient bioconversion of SB to ethanol at high solids loadings (16?% at pretreatment and 8?% at fermentation), low cellulase activities (1-7 FPU/g SB) and co-fermentation of hexoses and pentoses. The fungus Neurospora crassa DSM 1129 was used, which exhibits both depolymerase and co-fermentative ability, as well as mixed cultures with Saccharomyces cerevisiae 2541. A dilute-acid pretreatment (sulfuric acid 2?g/100?g SB; 210?°C; 10?min) was implemented, with high hemicellulose decomposition and low inhibitor formation. The bioconversion efficiency of N. crassa was superior to S. cerevisiae, while their mixed cultures had negative effect on ethanol production. Supplementing the in situ produced N. crassa cellulolytic system (1.0 FPU/g SB) with commercial cellulase and β-glucosidase mixture at low activity (6.0 FPU/g SB) increased ethanol production to 27.6?g/l or 84.7?% of theoretical yield (based on SB cellulose and hemicellulose sugar content). The combined dilute-acid pretreatment and bioconversion led to maximum cellulose and hemicellulose hydrolysis 73.3?% and 89.6?%, respectively.     

Incorporation of PEG-lipids in arsonoliposomes results in formation of highly stable arsenic-containing vesicles

We investigated the effect of pegylation on the physical stability, morphology and membrane integrity of arsonoliposomes. Arsonoliposomes composed of distearoylglycerophosphocholine (DSPC), cholesterol (Chol) and the palmitoyl side chain arsonolipid (with concentrations ranging from 0 mol% [DSPC/Chol vesicles] to 53 mol% of total lipid) containing either 4 or 8 mol% DPPE-PEG2000 or DSPE-PEG2000, were prepared by sonication. Arsonoliposome membrane integrity was evaluated by measuring the retention of encapsulated calcein in vesicles (during incubation in buffer or fetal calf serum [FCS]) while physical stability was evaluated by measuring vesicle dispersion turbidity (during incubation in water or CaCl(2)). Vesicle morphology was studied by cryo-electron microscopy. Experimental results show that: (i) PEG-lipids are incorporated in arsonoliposomes (as confirmed by the vesicle zeta potential modulation), (ii) pegylation of arsonoliposomes prevents their aggregation and fusion in the presence of calcium ions and (iii) when 8 mol% of PEG-DSPE is incorporated in arsonoliposomes based on their arsonolipid content, two groups of pegylated vesicles are formed: low content arsonoliposomes (<20 mol% arsonolipid) which are highly leaky and high content arsonoliposomes (>27 mol% arsonolipid) which are highly stable (70% calcein retention after 24h incubation in fetal calf serum [FCS]). In addition to high membrane integrity, the high content pegylated arsonoliposomes are morphologically perfect round-shaped vesicles without the sharp edges typically observed with non-pegylated DSPC-containing arsonoliposomes.     

Dynamics of Aerenchyma distribution in the cortex of sulfate-deprived adventitious roots of maize

BACKGROUND AND AIMS: Aerenchyma formation in maize adventitious roots is induced in nutrient solution by the deprivation of sulfate (S) under well-oxygenated conditions. The aim of this research was to examine the extent of aerenchyma formation in the cortex of sulfate-deprived adventitious roots along the root axis, in correlation with the presence of reactive oxygen species (ROS), calcium levels and pH of cortex cells and root lignification. METHODS: The morphometry of the second whorl of adventitious (W2) roots, subject to S-deprivation conditions throughout development, was recorded in terms of root length and lateral root length and distribution. W2 roots divided into sectors according to the mean length of lateral roots, and cross-sections of each were examined for aerenchyma. In-situ detection of alterations in ROS presence, calcium levels and pH were performed by means of fluorescence microscopy using H(2)DCF-DA, fluo-3AM and BCECF, respectively. Lignification was detected using the Wiesner test. KEY RESULTS: S-deprivation reduced shoot growth and enhanced root proliferation. Aerenchyma was found in the cortex of 77 % of the root length, particularly in the region of emerging or developing lateral roots. The basal and apical sectors had no aerenchyma and no aerenchyma connection was found with the shoot. S-deprivation resulted in alterations of ROS, calcium levels and pH in aerenchymatous sectors compared with the basal non-aerenchymatous region. Lignified epidermal layers were located at the basal and the proximal sectors. S-deprivation resulted in shorter lateral roots in the upper sectors and in a limited extension of the lignified layers towards the next lateral root carrying sector. CONCLUSIONS: Lateral root proliferation is accompanied by spatially localized induced cell death in the cortex of developing young maize adventitious roots during S-deprivation.     

The greatly increased amounts of accumulated versican and decorin with specific post-translational modifications may be closely associated with the malignant phenotype of pancreatic cancer

Pancreatic carcinoma (PC) is a cancer type with highly malignant growth and dissemination pattern of which the mechanisms are poorly understood. However, the malignant phenotype is closely linked to extracellular matrix (ECM) of which proteoglycans (PGs) and hyaluronan (HA) play a crucial role in the control of tumor progression and metastasis. In this study, we demonstrated that versican and decorin, two different PGs with contradictory roles and functions in the pathobiology of cancer, were the main matrix PGs in PC presenting a great increase 27- and 7-fold, respectively, in comparison to normal pancreas (NP). PC was characterized by the disproportional increase of versican compared to decorin, about 4 to 1, with a concurrent increase of HA, which may be closely associated with the growth and aggressiveness of this carcinoma. Significant specific post-translational modifications were also observed in both versican and decorin regarding the type, hydrodynamic size, sulfation pattern and extent of uronate epimerization of their glycosaminoglycan chains (GAGs). In particular, chondroitin sulphate (CS) was the predominant GAG type in both PC-associated versican and decorin. The CS of PC-decorin was increased 11-fold, compared to NP in which dermatan sulfate (DS) was the predominant GAG type in both PGs. The sulfation pattern of GAG chains was significantly altered in PC, since 6-sulfated disaccharides predominated in both versican and decorin with a marked presence of non-sulfated disaccharides accompanied by lower hydrodynamic sizes of both CS and DS chains compared to NP. In conclusion, all these findings agree with the highly malignant phenotype of this cancer and, thus, more studies need to be addressed on the roles of the post-translational modifications of versican and decorin in the biology of cancer.     

The concept of life and its significance in the construction of the new ecosystem ecology of Bernard Patten, Sven Jørgensen and Milan Straskraba

In a series of articles, three system ecologists, B. Patten, S. J?rgensen and M. Straskraba attempt to construct a new ecosystem ecology. In this effort, an innovative ecological definition of life that originates from the cognitive domain is prevalent. To be more specific, living entities are defined as those who make models of reality. Through the exploration of this definition, we will try to point out the ontological and the epistemological characteristics of the new ecology. These characteristics facilitate the integration of physicochemical, biological and human systems into a common framework. Indeed, system ecologists attempt to unify the inorganic and the organic world, including human beings, under a universal evolutionary scheme. This scheme is organized around an innovative scientific hypothesi, namely the exergy storage hypothesis.     

TGF-beta regulates differentially the proliferation of fetal and adult human skin fibroblasts via the activation of PKA and the autocrine action of FGF-2

Transforming growth factor-beta (TGF-beta) is a potent regulator of cell proliferation; interestingly its action is clearly cell type-dependent. In particular, it inhibits epithelial and endothelial cells' proliferation, while its action on many mesenchymal cells has been reported to be stimulatory. In this direction, we have recently shown that TGF-beta regulates the proliferation of normal human skin fibroblasts according to their developmental origin: i.e. it inhibits fetal fibroblasts, while it stimulates the proliferation of adult ones. Here, we present evidence on the mechanisms underlying this differential action. Concerning fetal fibroblasts, we have found that TGF-beta activates Protein Kinase A (PKA) and induces the expression of the cyclin-dependent kinase inhibitors (CKIs) p21(CIP1/WAF1) and p15(INK4B). Moreover, the specific PKA inhibitor H-89 blocks the induction of both CKIs and annuls the TGF-beta-mediated inhibitory effect, indicating the central role of PKA in this process. In contrast, in adult cells no PKA activation is observed. Moreover, TGF-beta stimulates cell proliferation by activating the MEK-ERK pathway, as the MEK inhibitor PD98059 blocks this effect. A specific neutralizing antibody against Fibroblast Growth Factor-2 (FGF-2) inhibits both ERK activation and the mitogenic activity of TGF-beta, indicating that the latter establishes an autocrine loop, via FGF-2, leading to cell proliferation. This loop requires FGF receptor-1 (FGFR-1), as its down-regulation by siRNA approach prevents TGF-beta from stimulating ERK-1/2 activation and DNA synthesis. In conclusion, the differential proliferative response of fetal and adult normal human skin fibroblasts to TGF-beta is regulated by distinct signaling pathways and furthermore it may provide information on the bimodal effect of this factor on cell proliferation, in general.     

Vasomotion: the case for chaos

Fluctuations in vascular calibre, a phenomenon known as vasomotion, are ubiquitous in the microcirculation and represent emergent behaviour that involves synchronisation of Ca²⁺ oscillations in individual vascular cells. Ideally, coordinated interactions between locally generated vasomotion and neuro-humoral control mechanisms will allow optimal sensing of flow and pressure within vascular networks and thereby facilitate synergistic readjustments in local vascular conductance and flow under conditions of dynamically changing metabolic demand. Indeed, many studies have reported that vasomotion becomes more prominent under pathophysiological conditions, suggesting that it may serve as an adaptive homeodynamic response that maintains or re-establishes flow when perfusion is compromised. We here summarise evidence that the apparent irregular nature of vasomotion reflects deterministic interactions between a small number of dominant control variables, rather than random events, and may therefore be formally classified as chaotic. We also discuss the potential physiological benefits of chaos in the microcirculation and the key roles of signalling via gap junctions and nitric oxide.     

Estimating dung decay rates of roe deer (<Emphasis Type="Italic">Capreolus capreolus</Emphasis>) in different habitat types of a Mediterranean ecosystem: an information theory approach

For elusive species living in concealing habitats (e.g. deer in a forest habitat), indirect methods such as faecal pellet counts are considered more practical means of estimating population density and abundance. Accurate estimation of deer density using the faecal standing crop (FSC) method necessitates the reliable estimation of the mean time to decay of pellet groups present during the survey. Mean time to decay is generally habitat specific, and separate estimations should be made for each habitat type in the study area. In a confined mountainous area of Greece, the habitat-specific mean time to decay of roe deer pellet groups was estimated by locating and marking fresh pellet groups on several dates in the lead up to an FSC survey and returning to the marked signs at the time of the survey to record whether or not each pellet group had survived. Several logistic models were fitted to the data, and estimations were based on a multi-model inference (MMI) approach according to information theory. The highest mean time to decay was estimated in coniferous forests, while mid-ranged values were found in maquis shrubs, and the lowest mean time to decay was observed in open areas. MMI by model averaging, based on Akaike weights, is recommended for making robust parameter estimations and for dealing with uncertainty in model selection.