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Teaching the scientific thrill
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reversed for scientists in industry. As noted by Eleanor Babco, Executive Director of the Washington-based Commission Professionals in Science and Technology (Washington DC, USA), the employment market puts a value on work that transfers data from the laboratory to the human. S de B (http://www.the-scientist.com/yr2001/sep/ prof_010917.html)
Exercise your brain New light has been shed on the well-known antidepressant effect of exercise by a pilot study reported in the British Journal of Sports Medicine. It was suspected that an endorphin-like substance, phenylethylamine, might be responsible for the well-being associated with as little as four hours of exercise weekly. On non-exercising days, urine samples were tested for phenylacetic acid, a by-product of phenylethylamine turnover. Urine samples were again collected after treadmill exercise in which heart rate had climbed to at least 70% of maximal heart rate capacity, a level thought to be capable of changing mood. Phenylacetic acid levels increased by ~77% after exercise. However, the rise in levels varied widely across the group tested, with maximal increases seen in those subjects who rated the exercise as difficult. The authors believe that many factors might be involved in the phenylacetic acid response to exercise but, considering that the chemical structure of phenylethylamine is very similar to that of amphetamines, this chemical might be part of a ‘runner’s high,’ a phenomenon linked to natural endorphin activity in the brain. S de B (http://unisci.com/stories/20013/0928016.htm)
Bacteria modify the negative approach Lipid A constitutes much of the outer lipid coat of disease-causing Gram negative organisms such as Escherichia coli, Salmonella and Pseudomonas. A novel method of bacterial resistance has been identified, by which an unusual sugar, aminoarabinose, is attached to the lipid, with the overall effect of reducing the net negative charge of the bacterial coat. Antibiotics (e.g. polymyxin) attach to the bacterial lipid coat via positively charged http://tibs.trends.com
TRENDS in Biochemical Sciences Vol.26 No.11 November 2001
groups, the interactions of which are lessened with weakened negativity of the aminoarabinose-coated lipid. Duke University Medical Center biochemist Christian Raetz (Durham, NC, USA) said, ‘…we have discovered the enzyme that attaches this modifying group to lipid A, as well as a novel precursor molecule (named undecaprenyl phosphate-aminoarabinose) that donates this aminoarabinose to lipid A. It might be possible to redesign peptide antibiotics to work even against bacteria with aminoarabinose attached to their lipid A. … Also, one could imagine devising inhibitors of our aminoarabinose transferase enzyme that would render polymyxin resistant mutants sensitive again.’ The transferase enzyme was pinpointed by genetically analysing a polymyxin-resistant strain of Salmonella (the arnT gene codes for the protein responsible for transferring aminoarabinose to lipid A). A similar gene to arnT has been identified in resistant strains of E. coli. In future studies, the scientists will trace the full metabolic pathway, which could yield additional enzyme targets for inhibitory drugs. These findings are being published in the Journal of Biological Chemistry. S de B (http://www.jbc.org/ http://www.eurekalert.org/pub_releases/ 2001-09/du-hbh091801.php)
Plastic protein mimics Proteins derive their versatility of function from their ability to form a wide array of differently shaped and sized molecules. Jonathan Parquette, Assistant Professor of Chemistry at Ohio State University ‘…wanted to mimic that versatile structure in a synthetic form.’ Dendritic macromolecules are tiny, spaghetti-like plastic filaments that are highly branched and regularly repeating, creating a three dimensional structure that becomes increasingly globular at higher generations, potentially mimicking the globular morphology of proteins. The filaments are, however, extremely soft and pliable, a potential problem in maintaining a specific folded shape. Metal coordination can allow conformational locking of the dendrimer secondary structure, creating a specific threedimensional structure. At present, the molecule is the same size as a small protein, spherical in shape and supported from the inside by branching beams of polymer, containing hollow portions that could theoretically hold drugs or other chemicals.
647
Parquette described his work at the September BioMEMS (Biomedical Microelectromechanical Systems) and Biomedical Nanotechnology World 2001 meeting in Columbus (OH, USA). It is hoped that these synthetic folded devices can be developed to open and close on cue; for example, when encountering specific tumour cells within the body, so that drugs encapsulated within are specifically delivered to a given target. ‘Along the outside of the molecule, the atoms fasten together like a zipper,’ explained Parquette. ‘Getting them to zip up is half the puzzle. Getting them to unzip on demand is the other half’. Another application for these dendritic macromolecules is in the formation of ultrafast light-responsive chips in molecular electronics, an approach particularly feasible if a stimulus, such as light, could be used to make the dendrimers unfold. S de B (http://www.healthtech.com/2001/mfb/ abstracts/Parquette.htm; http://www.osu.edu/researchnews/archive/ dendrim.htm)
Teaching the scientific thrill In an attempt to transmit the excitement of scientific discovery to undergraduate students, the Howard Hughes Medical Institute (HHMI, Chevy Chase, MD, USA) has issued a challenge to science professors across America. It plans to award $1 million each to 20 research scientists who come-up with novel creative approaches to undergraduate teaching that convey the enthusiasm experienced by those in the front line of research. The scientists selected will become ‘HHMI Professors’ in the fall of 2002. Thomas R. Cech, President of the Institute, explained why HHMI has issued the challenge, ‘Research is advancing at a breathtaking pace, but many college students are still learning science the same old way, by listening to lectures in large classes and memorizing facts from textbooks’. ‘We wish to empower scientists at research universities to become more involved and come-up with really innovative ideas that ‘break the mold’ and take a fresh look at science education.’ S de B (http://www.hhmi.org/news/083101.html)
0968-0004/01/$ – see front matter © 2001 Elsevier Science Ltd. All rights reserved.
Stephanie de Bono [email protected]
reversed for scientists in industry. As noted by Eleanor Babco, Executive Director of the Washington-based Commission Professionals in Science and Technology (Washington DC, USA), the employment market puts a value on work that transfers data from the laboratory to the human. S de B (http://www.the-scientist.com/yr2001/sep/ prof_010917.html)
Exercise your brain New light has been shed on the well-known antidepressant effect of exercise by a pilot study reported in the British Journal of Sports Medicine. It was suspected that an endorphin-like substance, phenylethylamine, might be responsible for the well-being associated with as little as four hours of exercise weekly. On non-exercising days, urine samples were tested for phenylacetic acid, a by-product of phenylethylamine turnover. Urine samples were again collected after treadmill exercise in which heart rate had climbed to at least 70% of maximal heart rate capacity, a level thought to be capable of changing mood. Phenylacetic acid levels increased by ~77% after exercise. However, the rise in levels varied widely across the group tested, with maximal increases seen in those subjects who rated the exercise as difficult. The authors believe that many factors might be involved in the phenylacetic acid response to exercise but, considering that the chemical structure of phenylethylamine is very similar to that of amphetamines, this chemical might be part of a ‘runner’s high,’ a phenomenon linked to natural endorphin activity in the brain. S de B (http://unisci.com/stories/20013/0928016.htm)
Bacteria modify the negative approach Lipid A constitutes much of the outer lipid coat of disease-causing Gram negative organisms such as Escherichia coli, Salmonella and Pseudomonas. A novel method of bacterial resistance has been identified, by which an unusual sugar, aminoarabinose, is attached to the lipid, with the overall effect of reducing the net negative charge of the bacterial coat. Antibiotics (e.g. polymyxin) attach to the bacterial lipid coat via positively charged http://tibs.trends.com
TRENDS in Biochemical Sciences Vol.26 No.11 November 2001
groups, the interactions of which are lessened with weakened negativity of the aminoarabinose-coated lipid. Duke University Medical Center biochemist Christian Raetz (Durham, NC, USA) said, ‘…we have discovered the enzyme that attaches this modifying group to lipid A, as well as a novel precursor molecule (named undecaprenyl phosphate-aminoarabinose) that donates this aminoarabinose to lipid A. It might be possible to redesign peptide antibiotics to work even against bacteria with aminoarabinose attached to their lipid A. … Also, one could imagine devising inhibitors of our aminoarabinose transferase enzyme that would render polymyxin resistant mutants sensitive again.’ The transferase enzyme was pinpointed by genetically analysing a polymyxin-resistant strain of Salmonella (the arnT gene codes for the protein responsible for transferring aminoarabinose to lipid A). A similar gene to arnT has been identified in resistant strains of E. coli. In future studies, the scientists will trace the full metabolic pathway, which could yield additional enzyme targets for inhibitory drugs. These findings are being published in the Journal of Biological Chemistry. S de B (http://www.jbc.org/ http://www.eurekalert.org/pub_releases/ 2001-09/du-hbh091801.php)
Plastic protein mimics Proteins derive their versatility of function from their ability to form a wide array of differently shaped and sized molecules. Jonathan Parquette, Assistant Professor of Chemistry at Ohio State University ‘…wanted to mimic that versatile structure in a synthetic form.’ Dendritic macromolecules are tiny, spaghetti-like plastic filaments that are highly branched and regularly repeating, creating a three dimensional structure that becomes increasingly globular at higher generations, potentially mimicking the globular morphology of proteins. The filaments are, however, extremely soft and pliable, a potential problem in maintaining a specific folded shape. Metal coordination can allow conformational locking of the dendrimer secondary structure, creating a specific threedimensional structure. At present, the molecule is the same size as a small protein, spherical in shape and supported from the inside by branching beams of polymer, containing hollow portions that could theoretically hold drugs or other chemicals.
647
Parquette described his work at the September BioMEMS (Biomedical Microelectromechanical Systems) and Biomedical Nanotechnology World 2001 meeting in Columbus (OH, USA). It is hoped that these synthetic folded devices can be developed to open and close on cue; for example, when encountering specific tumour cells within the body, so that drugs encapsulated within are specifically delivered to a given target. ‘Along the outside of the molecule, the atoms fasten together like a zipper,’ explained Parquette. ‘Getting them to zip up is half the puzzle. Getting them to unzip on demand is the other half’. Another application for these dendritic macromolecules is in the formation of ultrafast light-responsive chips in molecular electronics, an approach particularly feasible if a stimulus, such as light, could be used to make the dendrimers unfold. S de B (http://www.healthtech.com/2001/mfb/ abstracts/Parquette.htm; http://www.osu.edu/researchnews/archive/ dendrim.htm)
Teaching the scientific thrill In an attempt to transmit the excitement of scientific discovery to undergraduate students, the Howard Hughes Medical Institute (HHMI, Chevy Chase, MD, USA) has issued a challenge to science professors across America. It plans to award $1 million each to 20 research scientists who come-up with novel creative approaches to undergraduate teaching that convey the enthusiasm experienced by those in the front line of research. The scientists selected will become ‘HHMI Professors’ in the fall of 2002. Thomas R. Cech, President of the Institute, explained why HHMI has issued the challenge, ‘Research is advancing at a breathtaking pace, but many college students are still learning science the same old way, by listening to lectures in large classes and memorizing facts from textbooks’. ‘We wish to empower scientists at research universities to become more involved and come-up with really innovative ideas that ‘break the mold’ and take a fresh look at science education.’ S de B (http://www.hhmi.org/news/083101.html)
0968-0004/01/$ – see front matter © 2001 Elsevier Science Ltd. All rights reserved.
Stephanie de Bono [email protected]