霉菌毒素Dihydroxyaflavinine非竞争性...

Dihydroxyaflavinine is an indole-derived metabolite of Aspergillus flavus. Its action on GABA-induced response was quantitatively studied on the GABAA receptor expressed in Xenopus oocytes after injection of chick brain mRNA under voltage-clamp conditions. Dihydroxyaflavinine inhibits GABA-induced current non-competitively with KI = 12 mumol/L. This blockage is rapidly reversible. In comparison, the inhibitory effect of penicillin on GABAA receptor is enhanced by increasing GABA concentration. Ro 15-1788 (a benzodiazepine ligand with KD = 0.6--2 nmol/L) of concentration as high as 1 mumol/L, does not mask the action of 10 mumol/L dihydroxyaflavinine, indicating that dihydroxyaflavinine acts on a site different from benzodiazepines. Dihydroxyaflavinine appears to expedite desensitization of the receptor, which is similar to the action of picrotoxin and in contrast with that of penicillin and bicuculline.     

Who was... Harry Champion?

From insect collecting on the Surrey heaths, to forest management in Northern India, the rarefied atmosphere of Oxford University and the challenges of international consultancy, Harry Champion's life was rarely dull. As a schoolboy, he had declared his wish to travel widely and discover new species of plant and animal, though he probably never anticipated how far he would travel or how many species he would find.     

Who was... Mary Kingsley?

Mary Kingsley was an archetype, if not the archetype, of the formidable Victorian lady. Despite her physical frailty she managed to face the most hair-raising encounters in remote West Africa with an unshakeable aplomb that almost defies belief. She also made a number of not inconsiderable contributions to biology.     

嘌呤生物合成调控研究：...

Report here is the isolation of adenosine deaminase deficient mutants and genetic mapping. Engineering transposon MudJ (lacZ, Kanr) was used for mutagenesis and six add:: MudJ were obtained among 20,000 Kanr transductants. Adenosine deaminase activity of these mutants were assayed and all are negative. Cotransduction analysis of add::MudJ indicated that add is 70% linked to pmi(31') and 37% linked to zxx1900::Tn10d-tet insertion which is 10% linked to purR(30'). Three points cross showed that add is located between pmi and Tn10d-tet insertion. Therefore the gene order is purR-zxx1900::Tn10d-tet-add-pmi.     

Who was... Almroth Wright?

Sir Almroth Edward Wright CB MD FRS (1861-1947) was Britains first academic immunologist. He was qualified in both Arts and Medicine and commenced his professional life as a Physiologist, became Professor of Pathology and led the study of immunity to infectious diseases. He was often a controversial scientist and not always right in his views, hence his nickname 'Sir Almost Right'!     

Who was ... Anna Atkins?

In a previous age of scientific investigation, before images and information were ever captured electronically, the hands and eyes of artists were trained to make botanical and zoological drawings to illustrate the latest advances in human knowledge. The principles of artistic composition and colour were incorporated in their scientifically accurate drawings. These delicate watercolours and fine pen and ink drawings are now much prized for their qualities of beauty and intricate detail and can be found adorning many a drawing-room wall.     

Who was... Frank Buckland?

Frank Buckland introduced salmon and trout to Australia. He was also one of the most popular writers on natural history in the 19th century and this interest, particularly in fish farming, rapidly overtook his work as a doctor.