The Goals and Research of the BioEnergy Sciences Center (BESC): Developing Cost-effective and Sustainable Means of Producing Biofuels by Overcoming Biomass Recalcitrance

The mission of BioEnergy Sciences Center is to understand and overcome the recalcitrance of biomass to conversion by modifying plant cell walls with improved biocatalysts. The papers in this volume are from the plant transformation and the biomass characterization areas, and showcase the multidisciplinary and multi-institutional nature of the center.     

Snapper rest where they see best: visually mediated choice behaviour of Australasian snapper (Chrysophrys auratus)

The sensory physiology and behaviour of many fish species are strongly affected by light. This short study demonstrates that in the Australasian snapper (Chrysophrys auratus) absolute light intensity governs visual acuity and also guides preference behaviour, with fish choosing to ‘rest where they see best’. Use of the optomotor response to test visual acuity at four light intensities (0.01, 0.05, 1 and 3 μmol s^?1 m²), showed that visual acuity (measured as directional bias) was best at a light intensity of 0.05 μmol s^?1 m² (84.9% directional bias), but weakened at the highest and lowest light intensity (41.1 and 35.3%). When provided with a choice of the same four light environments fish also spent most time in the 0.05 μmol s^?1 m² light environment, while the highest and lowest intensity light environments were usually avoided. Acclimated light intensity (that is daytime light intensity of the home aquarium) was also 0.05 μmol s^?1 m²_. By selecting an environment where visual function is optimised, C. auratus are also optimising the ability to search for prey and to detect predators. The results are discussed with reference to habitat utilisation and thoughts for trawl fishing practices.     

Constancy and control of heart rate during an increase in temperature in the Antarctic fish Pagothenia borchgrevinki

The effect of an acute temperature increase on the control of the heart of the Antarctic teleost Pagothenia borchgrevinki was examined. Heart rate was thermally independent over the range −1.2°C to 3°C, although increasing the temperature from −1.2°C to 3°C elicited a decrease in ventral aortic pressure. Administration of the muscarinic receptor antagonist atropine and the β-adrenoreceptor antagonist sotalol abolished the thermal independence of heart rate, with heart rate increasing at Q₁₀=2. As temperature was increased from −1.2°C to 3°C, cholinergic tone on the heart also increased, from 44.6±4.2% to 70.0±8.4%. At the same time the adrenergic tone increased from 35.5±3.3% to 43.0±3.1%, but the effect on the heart was masked by the increase of cholinergic tone, leading to the thermal independence of heart rate.     

Dihydrolipoamide dehydrogenase from the halophilic archaebacterium Haloferax volcanii: characterization and N-terminal sequence.

Dihydrolipoamide dehydrogenase, a flavin disulfide reductase, has been purified and characterized from Haloferax volcanii. The enzyme is a dimer of relative mass 128,000, with an optimal activity at pH 9.0 in 1 M NaCl. Following reduction with its substrate, dihydrolipoamide, the enzyme is inactivated through covalent bond formation with the trivalent arsenical p-aminophenyl arsenoxide. The amino acid composition and the amino acid sequence of the first 49 residues of the N-terminus have been determined.     

Prenatal bias in sex ratios in a marsupial,Antechinus agilis.

Biased sex ratios of young of birds and mammals clearly occur and may have an adaptive significance, but we rarely know the stage at which a bias is generated, or the mechanism. If a bias is generated prior to birth, studies of marsupials may be insightful because gestation is short and neonates are relatively undifferentiated. This study investigated whether biased sex ratios in Antechinus agilis are generated in the brief period between birth and the attachment of young to the mother''s teats. When all young born, or just pouch young, or supernumerary young were considered, litters were strongly biased towards females (0.32 males), and there was no significant difference across the groups, so a bias is generated before birth in this species. Evidence from counts of corpora lutea suggests that embryo loss during gestation cannot account fully for the level of bias observed. Therefore, prefertilization mechanisms must contribute to the generation of sex-biased litters in this marsupial.     

Viscosity and temperature effects on the rate of DNA strand separation in alkali

The time required for the completion of the process of strand separation in λ bacteriophage DNA preparations exposed to strongly alkaline conditions in aqueous glycerol solutions was directly proportional to the viscosity of the solvent. This finding supports the idea that the rate-limiting step in the denaturation of high molecular weight DNA is the uncoiling of the strands and in the course of this uncoiling the forces arising from electrostatic and entropic factors must overcome the hydrodynamic viscous drag of the solvent resisting the translation of the polynucleotide strands.