Evaluation of swollenin from <Emphasis Type="Italic">Trichoderma pseudokoningii</Emphasis> as a potential synergistic factor in the enzymatic hydrolysis of cellulose with low cellulase loadings

Swollenin is a novel plant expansin-like protein that has been proposed to have a cellulose disruption activity. In this study, the recombinant swollenin (SWO2) from Trichoderma pseudokoningii S38 was successfully produced and purified in Aspergillus niger with a final yield of up to 10 mg of purified protein from 1 l of fermentation supernatant. The recombinant protein was found to exhibit very low level of endoglucanase activity and caused a slight increase in the crystallinity when treating cellulose. Simultaneous incubation of SWO2 with low-dose cellulases resulted in a significant synergistic activity in cellulose hydrolysis. Specifically, an even greater increase in the synergistic activity was obtained when cellulose was pretreated with swollenin followed by cellulase hydrolysis. Our results, therefore, provide a novel approach for the potential application of swollenin in the efficient saccharification of cellulosic materials.     

Symmetry breaking and the establishment of cell polarity in budding yeast

Cell polarity is typically oriented by external cues such as cell-cell contacts, chemoattractants, or morphogen gradients. In the absence of such cues, however, many cells can spontaneously polarize in a random direction, suggesting the existence of an internal polarity-generating mechanism whose direction can be spatially biased by external cues. Spontaneous 'symmetry-breaking' polarization is likely to involve an autocatalytic process set off by small random fluctuations. Here we review recent work on the nature of the autocatalytic process in budding yeast and on the question of why polarized cells only develop a single 'front'.     

Label-free imaging of lipid dynamics using Coherent Anti-stokes Raman Scattering (CARS) and Stimulated Raman Scattering (SRS) microscopy

The recently developed Coherent Anti-stokes Raman Scattering (CARS) microscopy and Stimulated Raman Scattering (SRS) microscopy have provided new methods to visualize the localization and regulation of biological molecules without the use of invasive and potentially perturbative labels. They allow rapid imaging of specific molecules with high resolution and sensitivity. These tools have been effectively applied to the study of lipid metabolism using Caenorhabditis elegans as a genetic model, unraveling new lipid storage phenotypes and their regulatory mechanisms. Here we review the underlying principle of CARS and SRS microscopy, as well as their recent applications in lipid biology research in C. elegans.     

Influence of supports on catalytic behavior of nickel catalysts in carbon dioxide reforming of toluene as a model compound of tar from biomass gasification

A series of supported Ni catalysts including Ni/MgO, Ni/γ-Al2O3, Ni/α-Al2O3, Ni/SiO2 and Ni/ZrO2 was tested in CO2 reforming of toluene as a model compound of tar from biomass gasification in a fluidized bed reactor, and characterized by the means of temperature programmed reduction with hydrogen (H2-TPR), XRD, TEM and temperature programmed oxidation (TPO). Combining the characterization results with the performance tests, the activity of catalyst greatly depended on Ni particles size, and the stability was affected by the coke composition. Both of them (Ni particle size and coke composition) were closely related to the interaction between nickel and support which would determine the chemical environment where Ni inhabited. The best catalytic performance was observed on Ni/MgO due to the strong interaction between NiO and MgO via the formation of Ni-Mg-O solid solution, and the highest dispersion of Ni particle in the basic environment.     

Kinetic modelling of steam gasification of various woody biomass chars: influence of inorganic elements

A study was performed on the influence of wood variability on char steam gasification kinetics. Isothermal experiments were carried out in a thermobalance in chemical regime on various wood chars produced under the same conditions. The samples exhibited large differences of average reaction rate. These differences were linked neither with the biomass species nor age and may be related to the biomass inorganic elements. A modelling approach was developed to give a quantitative insight to these observations. The grain model was used on one biomass of reference for temperatures between 750 and 900 °C and steam partial pressures between 0 and 0.27 bar. The model was applied to the other samples through the addition of an integral parameter specific to each sample. A satisfactory correlation was found between this parameter and the ratio potassium/silicium. This result highlighted the catalytic effect of potassium and inhibitor effect of silicium on the reaction.     

Detection of sugar accumulation and expression levels of correlative key enzymes in winter wheat (Triticum aestivum) at low temperatures

Carbohydrate accumulation is common in frost-resistant plants, and many enzymes participate in this process. The sugar content and expression levels of metabolic enzymes related to sugar biosynthesis in response to drops in temperature were measured in two cultivars of winter wheat (Triticum aestivum) with different cold tolerances. The results indicate that the two cultivars examined, Dongnongdongmai 1 and Jimai 22, accumulated high levels of carbohydrate before November 4 (above 0°C), and that accumulation decreased as temperatures fell. However, this decrease was more modest in Dongnongdongmai 1, which had a higher sugar content. Sucrose and fructose were the main soluble sugars, indicating an important role in freezing tolerance. Gene expression studies revealed that expression of the genes encoding chloroplastic enzymes was significantly upregulated in the tillering nodes. Expression upregulation of TaSS and TaTPT may be helpful for sugar accumulation before November 4.     

Impacts of changes in climate variability on regional vegetation in China: NDVI-based analysis from 1982 to 2000

Three methods were used to distinguish the characteristics of changes in climate variability and normalized difference vegetation index (NDVI) during the period from 1982 to 2000 in China. Great changes in climate variability and an increased trend in NDVI were observed. The changes in precipitation variability were greater than the changes in temperature variability in each month, which is attributed to changes in the monsoon system in East Asia. The abrupt changes in climate and NDVI were more significant in 1983 than in the other years due to the impacts of El Niño/Southern Oscillation (ENSO). Using these results, the influences of changes in climate variability on vegetation were studied in the whole nation, and eight regions were defined according to the vegetation division map of China. The results show that abrupt climate changes at a small scale cannot cause abrupt NDVI changes directly. At a nationwide level, over a longer time scale the persistence of above/below average temperature determines the changes in NDVI; at a shorter time scale, changes in the magnitude of precipitation influence NDVI significantly. Such regional climate variability affects vegetation in different ways owing to the diversity of vegetation types, climatic conditions and topography of the land.     

Neuropeptide exocytosis involving synaptotagmin-4 and oxytocin in hypothalamic programming of body weight and energy balance

Hypothalamic neuropeptides play essential roles in regulating energy and body weight balance. Energy imbalance and obesity have been linked to hypothalamic signaling defects in regulating neuropeptide genes; however, it is unknown whether dysregulation of neuropeptide exocytosis could be critically involved. This study discovered that synaptotagmin-4, an atypical modulator of synaptic exocytosis, is expressed most abundantly in oxytocin neurons of the hypothalamus. Synaptotagmin-4 negatively regulates oxytocin exocytosis, and dietary obesity is associated with increased vesicle binding of synaptotagmin-4 and thus enhanced negative regulation of oxytocin release. Overexpressing synaptotagmin-4 in hypothalamic oxytocin neurons and centrally antagonizing oxytocin in mice are similarly obesogenic. Synaptotagmin-4 inhibition prevents against dietary obesity by normalizing oxytocin release and energy balance under chronic nutritional excess. In conclusion, the negative regulation of synaptotagmin-4 on oxytocin release represents a hypothalamic basis of neuropeptide exocytosis in controlling obesity and related diseases.     

High lactation index is associated with insulin sensitivity

The aim of the study was to evaluate the contribution of lactation to insulin sensitivity in women 12 to 18 month postpartum using an oral glucose tolerance test (OGTT). Mean lactation index (LI), a scoring system that considers the establishment and maintenance of the lactation was used. Lactation index was calculated according to the number of months of breast-feeding per child with a maximum of 72 points. The mean LI was calculated by dividing the total number of points by the number of children. A cutoff point of 72 was considered for the LI. We investigated the inverse of the homeostasis model assessment (HOMA_Sens) and the Cederholm index. Healthy women went through standardized interview and anthropometry. After a 10- to 12-h overnight fast, a 2-h OGTT was performed. Multiple regression analysis was performed with HOMA_Sens and Cederholm index, which were adjusted for parity, percentage body fat, LI and presence/absence of breast-feeding. Both HOMA_Sens and Cederholm index were negatively associated with percentage body fat (P<.01), and Cederholm index was positively associated with LI (P=.01). Mean 120-min insulin levels were significantly lower in women with LI=72 when compared with LI<72 women. Insulin sensitivity measured by the Cederholm index is positively associated with prolonged and sustained lactation, while percentage body fat presented a negative association. In this way, sustained lactation-associated metabolic changes are considered protective to women's health.     

Use of experimental design to investigate biodiesel production by multiple-stage Ultra-Shear reactor

This work presents biodiesel production from soybean oil and bioethanol by multiple-stage Ultra-Shear reactor (USR). The experiments were carried out in the following conditions: reaction time from 6 to 12 min; catalyst concentration from 0.5% to 1.5% by weight of soybean oil; ethanol: soybean oil molar ratio from 6:1 to 10:1. The experimental design was used to investigate the influence of process variables on the conversion in biodiesel. The best ethyl ester conversion obtained was 99.26 wt.%, with ethanol:soybean oil molar ratio of 6:1, catalyst concentration of 1.35% and with 12 min of reaction time.