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I. J. Pickering Graham N. George Verena Van Fleet-Stalder Thomas G. Chasteen Roger C. Prince 《Journal of biological inorganic chemistry》1999,4(6):791-794
Received: 2 April 1999 / Accepted: 17 September 1999 相似文献
4.
Don Trinh Nguyen Jens Christian G?pfert Nobuhiro Ikezawa Gillian MacNevin Meena Kathiresan Jürgen Conrad Otmar Spring Dae-Kyun Ro 《The Journal of biological chemistry》2010,285(22):16588-16598
Sesquiterpene lactones are characteristic natural products in Asteraceae, which constitutes ∼8% of all plant species. Despite their physiological and pharmaceutical importance, the biochemistry and evolution of sesquiterpene lactones remain unexplored. Here we show that germacrene A oxidase (GAO), evolutionarily conserved in all major subfamilies of Asteraceae, catalyzes three consecutive oxidations of germacrene A to yield germacrene A acid. Furthermore, it is also capable of oxidizing non-natural substrate amorphadiene. Co-expression of lettuce GAO with germacrene synthase in engineered yeast synthesized aberrant products, costic acids and ilicic acid, in an acidic condition. However, cultivation in a neutral condition allowed the de novo synthesis of a single novel compound that was identified as germacrene A acid by gas and liquid chromatography and NMR analyses. To trace the evolutionary lineage of GAO in Asteraceae, homologous genes were further isolated from the representative species of three major subfamilies of Asteraceae (sunflower, chicory, and costus from Asteroideae, Cichorioideae, and Carduoideae, respectively) and also from the phylogenetically basal species, Barnadesia spinosa, from Barnadesioideae. The recombinant GAOs from these genes clearly showed germacrene A oxidase activities, suggesting that GAO activity is widely conserved in Asteraceae including the basal lineage. All GAOs could catalyze the three-step oxidation of non-natural substrate amorphadiene to artemisinic acid, whereas amorphadiene oxidase diverged from GAO displayed negligible activity for germacrene A oxidation. The observed amorphadiene oxidase activity in GAOs suggests that the catalytic plasticity is embedded in ancestral GAO enzymes that may contribute to the chemical and catalytic diversity in nature. 相似文献
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The climbing habit has evolved independently in many plant taxa, offering vines the ability to compete with non-climbing vegetation
for resources such as light, nutrients, and water. This review examines the structural and functional characteristics that
allow climbing plants to (1) achieve widespread dispersal, (2) transport large amounts of water throughout vessels, (3) maintain
high photosynthesis levels through a large leaf area to biomass ratio, (4) achieve rapid vertical and horizontal expansion
by fast growth rates and various climbing mechanisms and (5) survive and recover from disturbances. Due to the competitive
effects of vines on trees, management of vine growth is used to preserve tropical timber plantations, combat invasive weeds,
and promote rainforest recovery. In order to sustainably manage the vines into the future, it is necessary to understand the
mechanisms by which they can alter tropical forest succession and the impacts of various management techniques. 相似文献
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Marion S. Ecob Gillian S. Butler-Browne Robert G. Whalen 《Differentiation; research in biological diversity》1984,25(1-3):84-87
Abstract. Organotypic nerve-muscle cultures were prepared from foetal mouse spinal cord and adult mouse muscle fibres. In this system, the adult fibres degenerate and new myotubes form. The regenerated muscle fibres become innervated, develop cross-striations, and survive for several months. We have investigated the isozymes of myosin present in these muscle fibres using histochemistry and immunocytochemistry with antibodies to rat embryonic, neonatal, and adult fast myosins. We demonstrate that some of the regenerated fibres contain adult fast but not embryonic or neonatal myosin. This is the first demonstration of the production of adult myosin heavy chain in tissue culture. This system therefore offers the possibility for further study of the development of adult myosin isoforms in vitro. 相似文献
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Gillian D Alton David L Pearl Ken G Bateman W Bruce McNab Olaf Berke 《BMC veterinary research》2010,6(1):42
Background
Ontario provincial abattoirs have the potential to be important sources of syndromic surveillance data for emerging diseases of concern to animal health, public health and food safety. The objectives of this study were to: (1) describe provincially inspected abattoirs processing cattle in Ontario in terms of the number of abattoirs, the number of weeks abattoirs process cattle, geographical distribution, types of whole carcass condemnations reported, and the distance animals are shipped for slaughter; and (2) identify various seasonal, secular, disease and non-disease factors that might bias the results of quantitative methods, such as cluster detection methods, used for food animal syndromic surveillance. 相似文献9.
Rupert Cecil Gillian B. Robinson 《Biochimica et Biophysica Acta (BBA)/General Subjects》1975,404(1):164-168
It is known that insulin is adsorbed onto glass but it has been assumed that it is not adsorbed onto plastic. We find that tritium-labelled insulin is adsorbed onto all materials tried. The adsorption is reduced in the presence of other proteins and can be prevented altogether by coating the vessels with cetyl alcohol. 相似文献
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The rapid increase in protein synthesis that occurs on addition of insulin (1 mU/ml) to stepped-down 3T3 cells was blocked by pre-incubation of the cells with pertussis toxin. Cholera toxin on the other hand stimulated protein synthesis and this effect was insensitive to actinomycin D and inhibited by pro-treatment of the cells with phorbol dibutyrate to deplete cell protein kinase C. Insulin was found to cause a rapid and transient increase in diacylglycerol (DAG) synthesis. The insulin-induced increase in diacylglycerol was blocked by pertussis toxin. Exogenous DAG (10 M) stimulated protein synthesis within 1 hour. The results suggest that insuIin stimulates ribosomal activity through a signal mechanism that involves a G-protein mediated activation of phospholipase C to increase DAG levels. 相似文献