Chitin synthesis inhibiting insect growth regulators do not inhibit chitin synthase

Summary Tunicamycin, an antibiotic, and 5 insect growth regulators (diflubenzuron, Bay Sir 6874, Bay Sir 8514, CGA-19255 and Lilly 494) do not inhibit chitin synthase obtained from 4-day-oldStomoxys calcitrans pupae.     

Goldthioglucose and the blood-brain barrier

Résumé Après avoir augmenté la perméabilité corticale sang-cerveau chez des rats, on a donné à ces animaux une injection d'aurothioglucose. Aucune lésion due à l'aurothioglucose n'a été decouverte dans aucun des sites de perméabilité accrue. Les résultats montrent que la production de lésions par l'aurothioglucose n'est pas due à une permeabilité non-specifique dans certains sites hypothalamiques; ils confirment la théorie glucostatique qui suggère qu'il existe des glucorécepteurs à affinité définie situés à ces sites.

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This research was supported in part by a grant-in-aid from the National Institute of Neurological Diseases and Blindness (No. NB-01941), National Institutes of Health, U.S. Public Health Service; and by the Fund for Research and Teaching, Department of Nutrition, Harvard University.     

Antituberculosis activity of vinactane

Zusammenfassung Vinactan, eine antibiotische Substanz, isoliert vonStreptomyces vinaceus, besitzt bedeutende antituberkulöse Aktivität in infizierten Mäusen und Meerschweinchen. Erheblicher Schutzeffekt in tuberkulösen Mäusen wurde beobachtet, wenn die Therapie nicht sofort, sondern erst 9 Tage nach der Infektion einsetzte und die Behandlung mit 1 mg täglich während 21 Tagen durchgeführt wurde. In tuberkulösen Meerschweinchen, die mit 5 mg Vinactan täglich subkutan während 60 Tagen behandelt wurden, war die Entwicklung tuberkulöser Infektion in Milz, Lunge und Leber erheblich vermindert.     

Glycofection: facilitated gene transfer by cationic glycopolymers

Mammalian cells express several types of lectins involved in intracellular trafficking, including endocytosis, interorganelle routing and putatively nuclear import. In order to enhance the gene transfer efficiency, glycosylated cationic polymers have been used as nonviral vectors. We developed a simple method to convert reducing saccharides into glycosynthons. Glycosynthons are used to synthesize cationic glycopolymers, called Glycofectins. Glycofectins interact with a plasmid to give a glycoplex, a compacted form of a polymer/DNA complex. The high glycoplex efficiency depends on the sugar involved in the uptake and in the intracellular trafficking of glycoplexes. The present paper deals with glycoplexes, with gene transfer into cystic fibrosis airway epithelial and gland serous cells, and with some of the problems that have to be solved before clinical trials.     

Mechanism of glutamate receptor desensitization

Ligand-gated ion channels transduce chemical signals into electrical impulses by opening a transmembrane pore in response to binding one or more neurotransmitter molecules. After activation, many ligand-gated ion channels enter a desensitized state in which the neurotransmitter remains bound but the ion channel is closed. Although receptor desensitization is crucial to the functioning of many ligand-gated ion channels in vivo, the molecular basis of this important process has until now defied analysis. Using the GluR2 AMPA-sensitive glutamate receptor, we show here that the ligand-binding cores form dimers and that stabilization of the intradimer interface by either mutations or allosteric modulators reduces desensitization. Perturbations that destabilize the interface enhance desensitization. Receptor activation involves conformational changes within each subunit that result in an increase in the separation of portions of the receptor that are linked to the ion channel. Our analysis defines the dimer interface in the resting and activated state, indicates how ligand binding is coupled to gating, and suggests modes of dimer dimer interaction in the assembled tetramer. Desensitization occurs through rearrangement of the dimer interface, which disengages the agonist-induced conformational change in the ligand-binding core from the ion channel gate.     

The insect antenna is not a molecular sieve

Summary The deposition rate of 2 tritiated odorants onto insect antennae of different sizes and shapes is linearly proportional to the product of odorant concentration times the antennal surface area. This result challenges an assumption in a commonly accepted hypothesis that sensillar shape affects odorant deposition and that a single odorant molecule can initiate an action potential in a receptor cell. Consequently the 1-molecule-1-spike hypothesis bears reinvestigation.