Protective effects of non-catalytic proteins on endoglucanase activity at air and lignin interfaces

The manner in which added non-catalytic proteins during enzymatic hydrolysis of lignocellulosic substrates enhances hydrolysis mechanisms is not completely understood. Prior research has indicated that a reduction in the non-specific adsorption of enzymes on lignin, and deactivation of enzymes exposed to air–liquid interface provide rationale. This work investigated root causes including effects of the air–liquid interface on non-catalytic proteins, and effects of lignin on endoglucanase. Three different experimental designs and three variables (air–liquid interfacial area, the types of lignin (acid or enzymatic lignin), and the presence of non-enzymatic protein (bovine serum albumin [BSA] or soy proteins ) were used. The results showed that acid isolated lignin adsorbed almost all endoglucanase activity initially present in supernatant, independent of air interface conditions (25 or 250 ml flasks) with the presence of BSA preventing this effect. Endoglucanase lost 30%–50% of its activity due to an air–liquid interface in the presence of lignin while addition of non-enzymatic protein helped to preserve this enzyme's activity. Langmuir and Freundlich models applied to experimental data indicated that the adsorption increases with increasing temperature for both endoglucanase and BSA. Adsorption of the enzyme and protein were endothermic with an increase in entropy. These results, combined, show that hydrophobicity plays a strong role in the adsorption of both endoglucanase and BSA on lignin.     

Breeding patterns of great tits ( Parus major ) in pine forests along the Portuguese west coast

The breeding biology of great tits (Parus major) was studied in two forests of maritime pine (Pinus pinaster) on the west coast of Portugal, 200 km apart: Leiria (north) and Aposti?a (south). These two forests are located in a transition zone between Atlantic climate in the north, and Mediterranean climate in the south. Breeding onset was, on average, in the second and third week of March, which are the earliest records of breeding for this species. The southern population started to breed earlier than the northern one and produced a larger first clutch, 8.3 and 7.4 eggs, respectively. Corresponding to larger clutch sizes, we also found a higher first brood fledgling production in Aposti?a compared to Leiria, 6.1 and 5.4 fledglings, respectively. However, the total number of fledglings produced per pair was higher in Leiria (8.3) than in Aposti?a (7.7), due to higher productivity of second clutches (4.7 and 2.7 fledglings, respectively). Accordingly, the allocation of eggs between successive breeding attempts was more equal in Leiria. Results are discussed in accordance to the different climatic patterns in the two areas. It is suggested that the timing of breeding and different allocation of reproductive investment between successive breeding attempts play an important role in optimizing breeding tactics in this facultative multiple-brooded passerine in different climatic areas.     

Simple and inexpensive Flow Injection Analysis for determination of sucrose using invertase and glucose oxidase immobilised on glass beads

A Flow Injection Analysis (FIA) for sucrose using invertase (E.C. 3.2.1.26), mutarotase (E.C.5.1.3.3) and glucose oxidase (E.C.1.1.3.4) was developed. The enzymes were immobilised on glass beads using glutaraldehyde. The sucrose concentration was related to oxygen saturation. Fall in O₂ concentration, as a result of sucrose oxidation, was detected by a low cost, home-made O₂ electrode. The system was able to measure sucrose from 0.025 to 100mM with a response time of 6min using 200 l of sample, with an apparent Km of 42mM of sucrose. The system has been operated satisfactorily for 50 days without loss any initial activity.     

Effects of soil and wood depletion on biodiversity

Human depletion of soil and wood resources is dramatically altering the biodiversity of both terrestrial and aquatic ecosystems. This paper provides an overview of the numerous linkages between the depletion of soil and wood resources and the loss of biodiversity. While some of these linkages are well documented, others remain speculative or unexplored. In order to understand the full ramifications of resource depletion on biodiversity, additional research is required.     

études sur les phénomenes électrocapillaires

Sans résuméI. Analyse électrocapillaire des matières colorantes. Rev. gén. Mat. Col. 1926 Vol. 30 pp 34–45II. Phénomènes électrocapillaires et le problème du cancer. Arch. Med. Exper. 1926 Vol. I p 381III. Phénomènes électrocapillaires et l'antagonismes microbiens. Bol. Istituto Sier. Milano 1927 Vol. VI p 313.     

Thermodynamics of Energy Production from Biomass

With high quality petroleum running out in the next 50 years, the world governments and petrochemical industry alike are looking at biomass as a substitute refinery feedstock for liquid fuels and other bulk chemicals. New large plantations are being established in many countries, mostly in the tropics, but also in China, North America, Northern Europe, and in Russia. These industrial plantations will impact the global carbon, nitrogen, phosphorus, and water cycles in complex ways. The purpose of this paper is to use thermodynamics to quantify a few of the many global problems created by industrial forestry and agriculture. It is assumed that a typical tree biomass-for-energy plantation is combined with an efficient local pelleting facility to produce wood pellets for overseas export. The highest biomass-to-energy conversion efficiency is afforded by an efficient electrical power plant, followed by a combination of the FISCHER-TROPSCH diesel fuel burned in a 35%-efficient car, plus electricity. Wood pellet conversion to ethanol fuel is always the worst option. It is then shown that neither a prolific acacia stand in Indonesia nor an adjacent eucalypt stand is “sustainable.” The acacia stand can be made “sustainable” in a limited sense if the cumulative free energy consumption in wood drying and chipping is cut by a factor of two by increased reliance on sun-drying of raw wood. The average industrial sugarcane-for-ethanol plantation in Brazil could be “sustainable” if the cane ethanol powered a 60%-efficient fuel cell that, we show, does not exist. With some differences (ethanol distillation vs. pellet production), this sugarcane plantation performs very similarly to the acacia plantation, and is unsustainable in conjunction with efficient internal combustion engines.     

3-Methylcrotonylglycine Disrupts Mitochondrial Energy Homeostasis and Inhibits Synaptic Na+,K+-ATPase Activity in Brain of Young Rats

Deficiency of 3-methylcrotonyl-CoA carboxylase activity is an inherited metabolic disease biochemically characterized by accumulation and high urinary excretion of 3-methylcrotonylglycine (3MCG), and also of 3-hydroisovalerate in lesser amounts. Affected patients usually have neurologic dysfunction, brain abnormalities and cardiomyopathy, whose pathogenesis is still unknown. The present study investigated the in vitro effects of 3MCG on important parameters of energy metabolism, including CO₂ production from labeled acetate, enzyme activities of the citric acid cycle, as well as of the respiratory chain complexes I–IV (oxidative phosphorylation), creatine kinase (intracellular ATP transfer), and synaptic Na⁺,K⁺-ATPase (neurotransmission) in brain cortex of young rats. 3MCG significantly reduced CO₂ production, implying that this compound compromises citric acid cycle activity. Furthermore, 3MCG diminished the activities of complex II-III of the respiratory chain, mitochondrial creatine kinase and synaptic membrane Na⁺,K⁺-ATPase. Furthermore, antioxidants were able to attenuate or fully prevent the inhibitory effect of 3MCG on creatine kinase and synaptic membrane Na⁺,K⁺-ATPase activities. We also observed that lipid peroxidation was elicited by 3MCG, suggesting the involvement of free radicals on 3MCG-induced effects. Considering the importance of the citric acid cycle and the electron flow through the respiratory chain for brain energy production, creatine kinase for intracellular energy transfer, and Na⁺,K⁺-ATPase for the maintenance of the cell membrane potential, the present data indicate that 3MCG potentially impairs mitochondrial brain energy homeostasis and neurotransmission. It is presumed that these pathomechanisms may be involved in the neurological damage found in patients affected by 3-methylcrotonyl-CoA carboxylase deficiency.     

Gene Loci in Maize Influencing Susceptibility to Chilling Dependent Photoinhibition of Photosynthesis

Variation in tolerance in chilling-dependent photoinhibition has been associated with a wide range of traits in comparative physiological studies. A sweet corn (Zea mays L.) population of 214 F_2:3 families previously mapped to near-saturation with 93 RFLP DNA markers were subjected to low temperature and high-light events prior to measurement of the maximum dark-adapted quantum efficiency of PS II (F_v/F_m), to identify loci associated with variation in chilling-dependent photoinhibition. In the first assay with ten families varying in seedling growth and germination, significant differences were observed among families in their response to and recovery from exposure to high light at low temperature. All the 214 F_2:3 families from this population were then evaluated for tolerance of chilling-dependent photoinhibition in a controlled environment and then in three replicated trials in the field, each following naturally occurring chilling events during spring. The measured effects on F_v/F_m were analyzed with software that mapped segregating loci that regulate trait expression and linked to genetic markers (PLABQTL). QTL 3.096 (i.e. 96 cM on chromosome three) was consistently identified in both controlled environment and in the mean of the three field trails. Another QTL at 8.025, described the greatest percentage of total phenotypic variance (ca. 10%) for the mean reduction in F_v/F_m of all three periods of measurement in the field. A third QTL (4.136) showed a highly significant association in the third field trial. These three QTLs were closely associated with genes that have been mechanistically related to photoinhibition tolerance and repair. The results suggest that the ratio of F_v/F_m is an approach that may be used in establishing marker-assisted breeding for improved tolerance to chilling of maize in the light and in turn better early-season growth in cool temperate climates.