Comparative study of the antennal lobes and their afferent pathway in the worker bee and the drone (Apis mellifera)

Summary The topography of the antennal afferent path-ways was studied comparatively in the worker bee and the drone of Apis mellifera L. by cellular marking, following localized application of cobalt chloride to the cut end of one antenna. This study dealt principally with the first relay of the afferent pathway in the glomeruli of the antennal lobe. The counting and measurement of all the glomeruli were performed on 5 worker bees and 5 drones. An important sexual dimorphism, represented by 4 large and easily identifiable glomerular complexes, was demonstrated in the drone. In both worker bee and drone, four main regions of the glomerular neuropil were distinguished according to corresponding afferent bundles. The worker possessed 166 glomeruli and the drone 103. The number, position and dimensions of the glomeruli indicated that the glomerular organization was unvarying in worker bees and in drones. Concerning the internal structure of the glomeruli, two types were distinguished: the great majority (95%) exhibited a cortical layer, whereas in the 7 posterior glomeruli the synaptic fields of association seemed to be scattered throughout the whole volume. The main results of this work (glomerular invariance, sexual dimorphism) support the hypothesis of the functional unit of the glomeruli.Unité de Recherche Associée au CNRS, UA 483     

Comparative study of the pulmonary effects of intravenous leukotrienes and other bronchoconstrictors in anaesthetized guinea pig

Pulmonary responses to intravenous leukotrienes C₄, D₄ and E₄ administered as a bolus injection and by continuous infusion were studied in anesthetized guinea pigs. LTD₄, LTC₄ and LTE₄ (respective ED₅₀ of 0.21 ± .1, 0.64 ± .2 and 2.0 ± .1 μg kg⁻¹) produced dose-dependent increases in insufflation pressure when given as a bolus injection to anesthetized guinea pigs (Konzett-Rössler). Bronchoconstriction was antagonized by FPL-55712 (50–200 μg kg⁻¹), and indomethacin (50–200 μg kg⁻¹) but was not significantly altered by mepyramine (1.0 mg kg⁻¹), methysergide (0.1 mg kg⁻¹), intal (10 mg kg⁻¹) mepacrine (5 mg kg⁻¹) or dexamethasone (10 mg kg⁻¹). The beta adrenoceptor blocker, timolol (5 μg kg⁻¹) produced a significantly greater potentiation of the responses to the leukotrienes than to arachidonic acid, histamine and acetylcholine. Responses to bolus injection of LTE₄ but not LTD₄ or LTC₄ were partially antagonized by atropine (100 μg kg⁻¹) and bilateral vagotomy. In experiments of a different design, continuous infusion of LTD₄ and LTE₄ (2.8–3.2 μg kg⁻¹ min⁻¹) into indomethacin-treated animals produced slowly developing increases in pulmonary resistance and decreases in compliance. The increase in resistance produced by LTE₄ and LTD₄ was partly reversed by intravenous FPL-55712 (1.0 mg kg⁻¹) and atropine (100 μg kg⁻¹) but was almost completely reversed by FPL-55712 (3 – 10 mg kg⁻¹). These findings indicate that leukotrienes can produce bronchoconstriction in guinea pigs through cyclooxygenase-dependent and cyclooxygenase independent mechanisms both of which are blocked by FPL-55712. Cholinergic mechanisms are involved in the mediation of part of the response to bolus injection of LTE₄ as well as a small part of the initial response to continuous infusion of LTD₄ and LTE₄. Intrinsic beta adrenoceptor activation serves to down modulate responses to the leukotrienes to a greater extent than responses to arachidonic acid, histamine and acetylcholine.     

Alterations in the Fatty Acid Composition of Rat Brain Cells (Neurons, Astrocytes, and Oligodendrocytes) and of Subcellular Fractions (Myelin and Synaptosomes) Induced by a Diet Devoid of n-3 Fatty Acids

Abstract: Rats were fed through four generations with a semisynthetic diet containing 1.0% sunflower oil (6.7 mg/ g n-6 fatty acids, 0.04 mg/g n-3 fatty acids). Ten days before mating, half of the animals received a diet in which sunflower was replaced by soya oil (6.6 mg/g n-6 fatty acids, 0.8 mg/g n-3 fatty acids) and analyses were performed on their pups. Fatty acid analysis in isolated cellular and subcellular material from sunflower-fed animals showed that the total amount of unsaturated fatty acids was not reduced in any cellular or subcellular fraction (except in 60-day-old rat neurons). All material from animals fed with sunflower oil showed an important reduction in the docosahexaenoic acid content, compensated (except in 60-day-old rat neurons) by an increase in the n-6 fatty acids (mainly C22:5 n-6). When comparing 60-day-old animals fed with soya oil or sunflower oil, the n-3/n-6 fatty acid ratio was reduced 16-fold in oligodendrocytes, 12-fold in myelin, twofold in neurons, sixfold in synaptosomes, and threefold in astrocytes. No trienes were detected. Saturated and monounsaturated fatty acids were hardly affected. This study provides data on the fatty acid composition of isolated brain cells.     

Kinetic studies of aminoglycoside acetyltransferase and phosphotransferase from Staphylococcus aureus RPAL. Relationship between the two activities

In the Staphylococcus aureus strain harbouring the plasmid RPAL, the resistance to aminoglycoside antibiotics results from two inactivating reactions catalyzed by a 6'-N-aminoglycoside acetyltransferase and a 2"-O-amino-glycoside phosphotransferase. These enzymes are copurified with a constant ratio between the two activities, the purification process consisting in affinity chromatography, native electrophoresis and gel exclusion chromatography. The kinetic mechanisms of each activity have been determined from studies of initial velocities, as well as product and dead-end inhibitions. Both activities follow a random rapid equilibrium mechanism. The substrates and cofactors of one reaction have been tested as effectors of the other reaction. No interaction between the two activities has been observed. However, the GTP cofactor of phosphotransferase protects, at weak concentrations, the acetyltransferase against thermal inactivation, which suggests that the two activities may be associated.     

Isolation and Characterization of Sex-Linked Female-Sterile Mutants in DROSOPHILA MELANOGASTER with Special Attention to Eggshell Mutants

To study genes that function mainly or exclusively during oogenesis, we have isolated and analyzed female-sterile mutations, with special emphasis on those that affect eggshell formation. Following treatment that induced 61 to 66% lethals, 8.1% of the 1071 X chromosomes tested carried recessive female sterility mutations (87 isolates), and 8.0% carried partial female-sterile mutations (86 isolates), respectively. In addition, three dominant female steriles were recovered. Some of the mutants had very low fecundity, and others laid morphologically normal eggs that failed to develop. A third category included 29 mutants that laid eggs with morphological abnormalities: 26 were female steriles, two were partial female steriles and one was fertile. Mutants of this third category were characterized in some detail and compared with 40 previously isolated mutants that laid similarly abnormal eggs. Approximately 28–31 complementation groups with morphological abnormalities were detected, some of which were large allelic series (11, 9, 7, 6 and 5 alleles). Twenty-four groups were mapped genetically or cytogenetically, and 21 were partially characterized by ultrastructural and biochemical procedures. Of the latter, one group showed clear deficiency of yolk proteins, and nine showed prominent ultrastructural defects in the chorion (at least eight accompanied by deficiencies in characterized chorion proteins). At least six groups with clear-cut effects were found at loci not previously identified with known chorion structural genes.     

Synthesis of a 125I-radiolabeled penicillin for penicillin-binding proteins studies

Radioiodination of penicillin X (p-hydroxybenzylpenicillin) with 125INa, using the chloramine-T method, is simple and almost quantitative. The product thus obtained can be used without further purification for the penicillin-binding proteins (PBPs) assay. The chemical structure of 125I-penicillin X is very close to that of penicillin G, and the affinity of the two compounds for the PBPs are very similar. 125I-penicillin X can then advantageously replace [14C]penicillin G in these experiments, as its specific radioactivity is 2000 Ci/mol, in our preparations, instead of about 50 Ci/mol; thus, the experimental procedure is simplified and the autoradiography exposure time is reduced to 12-48 h.     

Trial of support treatment with human chorionic gonadotrophin in the luteal phase after treatment with buserelin and human menopausal gonadotrophin in women taking part in an in vitro fertilisation programme.

OBJECTIVE--To evaluate the effect of support with human chorionic gonadotrophin in the luteal phase in women taking part in an in vitro fertilisation programme after buserelin and human menopausal gonadotrophin were used to hyperstimulate their ovaries. DESIGN--Controlled group comparison. SETTING--Outpatient department of a private hospital. PATIENTS--115 Women with indications for in vitro fertilisation, all of whom had at least one embryo transferred. INTERVENTIONS--After suppression of the pituitary with buserelin the ovaries of all the women were stimulated with human menopausal gonadotrophin on day 4 of the luteal phase. Human chorionic gonadotrophin (10,000 IU) was given to induce ovulation, and oocytes were recovered 34 hours later. Embryos were transferred 46 to 48 hours after insemination. Women who had received the 10,000 IU of human chorionic gonadotrophin on a date that was an uneven number (n = 61) were allocated to receive support doses of 2500 IU human chorionic gonadotrophin three and six days after that date. The remaining 54 women did not receive hormonal support. END POINT--Determination of the rates of pregnancy. MEASUREMENTS and main results--Support with human chorionic gonadotrophin did not significantly alter the progesterone or oestradiol concentrations in the early or mid-luteal phase. The mean (range) progesterone concentrations in the late luteal phase in women who did not become pregnant were, however, significantly higher in those who received support (16(9-110) nmol/l nu 8(4-46) nmol/l), and the luteal phase was significantly longer in this group (14 days nu 12 days). The rate of pregnancy was significantly higher in the women who received support than in those who did not (25/61 nu 8/54). CONCLUSIONS--When buserelin and human menopausal gonadotrophin are used to hyperstimulate ovaries support with human chorionic gonadotrophin in the luteal phase has a beneficial effect on in vitro fertilisation.     

Construction of Escherichia coli amber suppressor tRNA genes. III. Determination of tRNA specificity

Using synthetic oligonucleotides, we have constructed a collection of Escherichia coli amber suppressor tRNA genes. In order to determine their specificities, these tRNAs were each used to suppress an amber (UAG) nonsense mutation in the E. coli dihydrofolate reductase gene fol. The mutant proteins were purified and subjected to N-terminal sequence analysis to determine which amino acid had been inserted by the suppressor tRNAs at the position of the amber codon. The suppressors can be classified into three groups on the basis of the protein sequence information. Class I suppressors, tRNA(CUAAla2), tRNA(CUAGly1), tRNA(CUAHisA), tRNA(CUALys) and tRNA(CUAProH), inserted the predicted amino acid. The class II suppressors, tRNA(CUAGluA), tRNA(CUAGly2) and tRNA(CUAIle1) were either partially or predominantly mischarged by the glutamine aminoacyl tRNA synthetase. The class III suppressors, tRNA(CUAArg), tRNA(CUAAspM), tRNA(CUAIle2), tRNA(CUAThr2), tRNA(CUAMet(m)) and tRNA(CUAVal) inserted predominantly lysine.