ThechlL (frxC) gene: Phylogenetic distribution in vascular plants and DNA sequence fromPolystichum acrostichoides (Pteridophyta) andSynechococcus sp. 7002 (Cyanobacteria)

We examinedchlL (frxC) gene evolution using several approaches. Sequences from the chloroplast genome of the fernPolystichum acrostichoides and from the cyanobacteriumSynechococcus sp. 7002 were determined and found to be highly conserved. A complete physical map of the fern chloroplast genome and partial maps of other vascular plant taxa show thatchlL is located primarily in the small single copy region as inMarchantia polymorpha. A survey of a wide variety of non-angiospermous vascular plant DNAs shows thatchlL is widely distributed but has been lost in the pteridophytePsilotum and (presumably independently) within the Gnetalean gymnosperms.The namefrxC was originally used to denote a gene encoding a product with probable Fe : S cluster binding activity. This activity was postulated due to the amino acid sequence similarity between this product and the Fe : S-binding nitrogenase iron proteinnifH. Fe : S-binding is a property shared by ferredoxins, which are denoted by the prefix frx. However, this gene does not encode a ferredoxin. It is much larger than any known ferredoxin, it binds its Fe : S cluster between two halves of a homodimer (Fujita & al. 1989,Burke & al. 1993 a, c) instead of within a single subunit, and it lacks the pattern of clustered cysteines present in all ferredoxins (Meyer 1988). Therefore, we use the namechlL to recognize the sequence and functional similarities to the bacterial PChlide reductase subunit,bchL. Similar usage has been adopted for this (Suzuki & Bauer 1992) and other (Choquet & al. 1992,Burke & al. 1993b) PChlide reductase subunits.     

Use of 31P magnetisation transfer magnetic resonance spectroscopy to measure ATP changes after 670 nm transcranial photobiomodulation in older adults

Mitochondrial function declines with age, and many pathological processes in neurodegenerative diseases stem from this dysfunction when mitochondria fail to produce the necessary energy required. Photobiomodulation (PBM), long-wavelength light therapy, has been shown to rescue mitochondrial function in animal models and improve human health, but clinical uptake is limited due to uncertainty around efficacy and the mechanisms responsible. Using ³¹P magnetisation transfer magnetic resonance spectroscopy (MT-MRS) we quantify, for the first time, the effects of 670 nm PBM treatment on healthy ageing human brains. We find a significant increase in the rate of ATP synthase flux in the brain after PBM in a cohort of older adults. Our study provides initial evidence of PBM therapeutic efficacy for improving mitochondrial function and restoring ATP flux with age, but recognises that wider studies are now required to confirm any resultant cognitive benefits.     

Bioremediation of experimental petroleum spills on mineral soils in the Vestfold Hills,Antarctica

The effect of nutrient and water enhancement on the biodegradation of petroleum was tested in Antarctic mineral soils. Nitrogen, phosphorus and potassium were applied in solution, with or without gum xanthan or plastic covers, to sites artificially contaminated with distillate. The effectiveness of these procedures was assessed by measuring changes in total petroleum hydrocarbons; heptadecane/pristane and octadecane/phytane ratios; in concentrations of major hydrocarbon components and in microbial numbers and activity.Significantly lower hydrocarbon concentrations were recorded after one year in soils treated with fertilizer solutions, but only in the surface 3 cm. These soils also showed lowered heptadecane/pristane and octadecane/ phytane ratios and had the highest levels of microbial activity relative to other plots. Soils treated with gum xanthan. or covered with plastic had the highest residual hydrocarbon levels. Both treatments inhibited evaporative loss of hydrocarbon, and there were indications that gum xanthan was utilized by the microbiota as an alternative carbon source to distillate. Higher temperatures were recordecd under the plastic but no stimulation of biodegradation was detected.Estimated numbers of metabolically active bacteria were in the range 10⁷ to 10⁸ g^–1 dry weight of soil, with an estimated biomass of 0.03 to 0.26 mg g^–1 soil. Estimated numbers of amoebae were in the range 10⁶ to 10⁷ g^–1 soil (biomass of 2 to 4 mgg^–1). The highest populations were recorded in fertilized, contaminated soils, the only soils where petroleum degradation was demonstrated.     

Synthesis and evaluation of the antidepressant activity of the enantiomers of bupropion

The synthesis of the enantiomers of bupropion, (rac)-2-tert-butylamino-3′-chloropropiophenone 1 (Wellbutrin®) is described. The enantiomers were compared with the racemate in both the tetrabenazine-induced sedation model and the inhibition of uptake of biogenic amine assay. No significant differences were found in their potencies to reverse tetrabenazine-induced sedation in mice or in their IC₅₀ values as inhibitors of biogenic amine uptake into nerve endings obtained from mouse brain. © 1993 Wiley-Liss, Inc.     

An electrogenetic toggle switch model

Synthetic biology uses molecular biology to implement genetic circuits that perform computations. These circuits can process inputs and deliver outputs according to predefined rules that are encoded, often entirely, into genetic parts. However, the field has recently begun to focus on using mechanisms beyond the realm of genetic parts for engineering biological circuits. We analyse the use of electrogenic processes for circuit design and present a model for a merged genetic and electrogenetic toggle switch operating in a biofilm attached to an electrode. Computational simulations explore conditions under which bistability emerges in order to identify the circuit design principles for best switch performance. The results provide a basis for the rational design and implementation of hybrid devices that can be measured and controlled both genetically and electronically.