Generation of LexA enhancer-trap lines in Drosophila by an international scholastic network

Conditional gene regulation in Drosophila through binary expression systems like the LexA-LexAop system provides a superb tool for investigating gene and tissue function. To increase the availability of defined LexA enhancer trap insertions, we present molecular, genetic, and tissue expression studies of 301 novel Stan-X LexA enhancer traps derived from mobilization of the index SX4 line. This includes insertions into distinct loci on the X, II, and III chromosomes that were not previously associated with enhancer traps or targeted LexA constructs, an insertion into ptc, and seventeen insertions into natural transposons. A subset of enhancer traps was expressed in CNS neurons known to produce and secrete insulin, an essential regulator of growth, development, and metabolism. Fly lines described here were generated and characterized through studies by students and teachers in an international network of genetics classes at public, independent high schools, and universities serving a diversity of students, including those underrepresented in science. Thus, a unique partnership between secondary schools and university-based programs has produced and characterized novel resources in Drosophila, establishing instructional paradigms devoted to unscripted experimental science.

Inactivation of end-plate acetylcholinesterase during the course of organophosphate intoxications

Blood organophosphate (OP) levels, serum butyrylcholinesterase (BChE) activity and electrophysiological neuromuscular transmission following repetitive nerve stimulation at 10 Hz and 50 Hz were studied serially in five patients with severe acute organophosphate intoxication following suicide attempts. Eight to 45 hours after oral ingestion, blood OP levels were elevated, BChE activity was markedly reduced, while repetitive nerve stimulation studies showed no or only mild abnormalities. The latter attained the maximal abnormality 32-69 h after ingestion, when BChE was inactivated further but elevated OP levels had fallen. Recovery from these abnormalities at 10 Hz nerve stimulation occurred within 100-237 h after the intoxication and it was still incomplete at 50 Hz stimulation 48-80 h later. BChE activity varied within a wide range and showed even normal values at both times. Neuromuscular transmission studies proved to be the most useful indicator for determining the severity and time course of organophosphate intoxication.

Lophotoxin and related coral toxins covalently label the alpha-subunit of the nicotinic acetylcholine receptor

Lophotoxin and lophotoxin analog-1 are uncharged cyclic diterpenes obtained from gorgonian corals. They have been shown to block the function of nicotinic acetylcholine receptors. Inhibition results from blockade of the agonist recognition site and appears irreversible in that extensive washing does not restore receptor function. This study was undertaken to determine whether this apparently irreversible inhibition involves covalent labeling at a selective site and to further characterize this site directly. Incubation of membranes prepared from the electric organ of Torpedo californica with analog-1 followed by reduction with NaB3H4 resulted in the incorporation of radioactivity into several membrane proteins. The incorporation of radioactivity into the alpha-subunit of the receptor was blocked by prior incubation with agonists and antagonists. [3H]Lophotoxin and [3H]analog-1 were prepared by reduction with NaB3H4 and back-oxidation with CrO3. The radiolabeled coral toxins reacted selectively and covalently with the alpha-subunit of the receptor. Their binding was prevented by prior exposure to agonists and antagonists. In contrast to the site-directed alkylating agent 4-(N-maleimido)benzyltrimethylammonium iodide, prior reduction of the receptor was not required for covalent binding of 3H-labeled coral toxins. Selective reduction of Cys192 and Cys193 followed by alkylation with 4-(N-maleimido)benzyltrimethylammonium iodide blocked the binding of [3H]analog-1, whereas alkylation with iodoacetic acid or iodoacetamide did not. Thus, the binding site for the coral toxins does not overlap the binding surface near Cys192 and Cys193. Digestion of isolated labeled alpha-subunits with endoglycosidase H revealed that the polypeptide portion of the protein retained the covalently bound [3H]analog-1. Digestion with staphylococcal V8 protease revealed two major peptides of approximately 19 and 20 kDa, along with several smaller peptides. Only the 20-kDa peptide retained the covalently bound [3H]analog-1, localizing the site of covalent attachment between Ser173 and Glu335. The unique chemical structure and covalent reactivity of these gorgonian coral toxins will undoubtedly allow further insights into the structure of the agonist recognition site.

Fungal infection in chronic granulomatous disease. The importance of the phagocyte in defense against fungi

Among 245 cases of chronic granulomatous disease which were evaluated, fungal infection occurred in 20.4 percent. Fungi encountered include Aspergillus, Torulopsis and Candida. In 18 percent of the patients with fungal infection, the disease was limited to soft tissue or bone; all did well. Most of the patients had fungal pneumonia and/or widely disseminated disease; diagnosis was usually confirmed by open lung biopsy. Patients with pneumonia or disseminated disease who received no therapy succumbed to infection, whereas more than half the patients who received antifungal therapy were cured. Modalities of treatment included antifungal chemotherapy, surgical removal of infected tissue and granulocyte transfusion. Although several patients showed dramatic improvement during granulocyte transfusions given in combination with antifungal chemotherapy, the improvement achieved was not statistically significant when compared with that achieved with chemotherapy alone. These results emphasized the importance of phagocytic cells in defense against fungi and the need for further evaluation of granulocyte transfusion therapy in compromised hosts in whom fungal infections develop.

[Cryoglobulins and circulating immune complexes in rheumatoid arthritis. Clinical and biological correlations]

We studied circulating immune complexes using a test involving the precipitation of these complexes with polyethylene glycol 6000 at 2.5 percent, and characterization of the Clq bound in vivo to immunoglobulins in the serum of 126 healthy subjects, 95 hospitalized controls and 181 patients suffering from rheumatoid arthritis (RP). Likewise, the RP benefited from a study of cryoglobulins (CG). The PEG-Clq proved positive (PEG +) in 7 per cent of the healthy controls, 25 per cent in the seronegative RP. ThePEG & RP have a level of proteins, gammaglobulins, IgM and IgG that is higher than in patients in whom the test is negative. On the other hand, they have a lower level of C4. One CG was detected in 43 patients who were all PEG +. The level of CG is proportionate to the intensity of the articular inflammation, the sedimentation rate, the level of seric iron and that of hemoglobin. The composition of the precipitins obtained by activity of the PEG is very close to that of the CG.

[Morphological diagnosis of Pneumocystis carinii]

Pneumocystis carinii pneumonia can only be diagnosed once the microorganism is demonstrated. The authors review and illustrate various staining technics, and discuss for each of them specific advantages. All samples must by systematically examined both by phase contrast microscopy and by light microscopy after Gomori-Grocott and Gram-Weigert stains. This morphological study is completed by ultrastructural photographs.