[Tsetse fly wings, an identity card of the insect?]. / Les ailes de glossines, une carte d'identité de l'insecte?

The size of tsetse flies is often associated with population dynamics and vectorial capacity parameters. Adult fly size is generally estimated from measurements of wing segments. To take measure of the wing, a semi-automatic software was developed by CIRAD-EMVT and IRD. It was used in wild populations of Glossina tachinoides Westwood and G. palpalis gambiensis Vanderplank (Diptera: Glossinidae) trapped near Bobo-Dioulasso, Burkina Faso. From an numeric picture of the wing, the software calculates the length of vein segments, the ratios between these lengths, the surface of the tsetse characteristic "hatchet cell", and the greyness on the wings. The data were interesting at the level of taxonomy. In addition, they help specify physiological characteristics of the studied populations.

Iodine kinetics and effectiveness of stable iodine prophylaxis after intake of radioactive iodine: a review.

Ingestion of potassium iodide (KI) offers effective protection against irradiation of the thyroid after accidental exposure to radioactive iodine. This prophylaxis aims at rapidly obtaining maximal thyroid protection without adverse effects. This article reviews studies on iodine kinetics in humans and on the efficacy of KI in protecting the thyroid. In adults with normal thyroid function, ingestion of 100 mg of iodide just before exposure to radioactive iodine blocks at least 95% of the thyroid dose. If exposure persists after iodide ingestion (100 mg), the percentage of averted dose may decrease significantly. Daily ingestion of a dose of 15 mg of KI would then maintain the thyroid blockade at a level above 90%. The efficacy of iodide and the occurrence of antithyroid effects also depend on external and individual factors such as dietary iodine intake, thyroid function, and age. The KI dosage regimen should be adjusted for age at exposure. For the fetus, the newborn, children, and adolescents, the risk of radiation-induced thyroid cancer in case of accidental exposure to radioactive iodine justifies KI prophylaxis, despite the risk of hypothyroidism, especially in newborns. For the elderly, the benefits of KI may be lower than the risk of iodine-induced hyperthyroidism.

Afro-tropical anopheline mosquitoes. III. Description of three new species: Anopheles carnevalei sp. nov., An. hervyi sp. nov., and An. dualaensis sp. nov., and resurrection of An. rageaui Mattingly and Adam.

Anopheles (Cellia) carnevalei sp. nov. is described as a new species morphologically similar to Anopheles nili. This aggressive human biter was collected in Ivory Coast. Anopheles (Cellia) hervyi sp. nov. was collected in southern Niger and is described as a new species morphologically similar to Anopheles salbaii. Anopheles (Cellia) dualaensis sp. nov. is a new species from Duala in southern Cameroon. The synonymy of Anopheles cavernicolus and Anopheles smithii is confirmed. Based on extensive reexamination of larval and adult morphology, the authors suggest that Anopheles (Cellia) rageaui Mattingly and Adam should no longer be considered as a synonymn of An. smithii.

Intraspecific variability in natural populations of Glossina palpalis gambiensis from West Africa, revealed by genetic and morphometric analyses.

Glossina palpalis gambiensis Vanderplank (Diptera: Glossinidae) from West Africa (Senegal and Burkina Faso) were analysed for microsatellite DNA polymorphisms and size of the wings. In the overall sample a strong heterozygote deficiency was found at two polymorphic microsatellite loci. It led to a highly significant value of Fis (within-sample heterozygote deficit) in the western zone of Sideradougou area in Burkina Faso. Genetic differentiation was significant on a macrogeographic scale, i.e. between tsetse coming from Senegal and Burkina Faso. Wing measures also differed between these two countries; flies from Senegal appeared to be smaller. Microsatellite loci further allowed differentiation of populations of G. palpalis gambiensis trapped on the same hydrographic network a few kilometres apart. The results are interpreted as indicating that further investigations will allow the study of genetic variability of tsetse flies in relation to the dynamics of transmission of human and animal trypanosomoses.

Chicken neuronal acetylcholine receptor alpha 2-subunit gene exhibits neuron-specific expression in the brain and spinal cord of transgenic mice.

Transgenic mice carrying the complete structural gene of the alpha 2 subunit of the chicken neuronal nicotinic acetylcholine receptor (nAChR) and 7 kilobase pairs (kbp) of 5' upstream and 3 kbp of 3' downstream sequences have been generated. The transgene was stably integrated in transgenic lines and transmitted to their progeny. Avian transgene expression was predominant in the central nervous system as detected by specific alpha 2-subunit cDNA amplification. Moreover, in at least two independent mouse lines, its expression appeared to be neuron-specific and reproducibly restricted to subregions in the brain and spinal cord, as revealed by in situ hybridization histochemistry. Most cranial motor nuclei were positive, and several of the alpha 2-subunit transgene-expressing structures corresponded to cholinergic areas in rodents. This study reveals that regulatory mechanisms giving rise to neuronal-specific gene expression have been conserved at least in part between birds and mammals.

Differential expression of the neuronal acetylcholine receptor alpha 2 subunit gene during chick brain development.

In situ hybridization histochemistry reveals localized expression of the nicotinic acetylcholine receptor (nAChR) alpha 2 subunit mRNA restricted to the lateral spiriform nucleus (SpL) of the chick diencephalon. The alpha 2 nAChR transcripts are not detected in immature SpL neurons at 4.5-5 days of embryonic development. They begin to accumulate in the SpL at embryonic day 11 and increase until the newborn stage. Specific alpha 2 cDNA amplification by the polymerase chain reaction shows that during this period, the absolute content of alpha 2 mRNA increases about 20-fold. The expression of the alpha 2 nAChR gene is thus developmentally regulated and appears concomitant with the entry of cholinergic fibers into the SpL, as demonstrated by choline acetyltransferase immunohistochemistry.

Acetylcholine receptor expression in primary cultures of embryonic chick myotubes--I. Discoordinate regulation of alpha-, gamma- and delta-subunit gene expression by calcitonin gene-related peptide and by muscle electrical activity.

The neuropeptide calcitonin gene-related peptide calcitonin gene-related peptide, and muscle electrical activity regulate in opposite directions the content of nicotinic acetylcholine receptor alpha-subunit mRNA in primary cultures of chick embryonic myotubes. Indeed, treating the cells with calcitonin gene-related peptide or blocking the spontaneous activity of muscle cells by tetrodotoxin (an inhibitor of sodium channels) increases, although to different levels, the content of acetylcholine receptor alpha-subunit mRNA [Fontaine B., Klarsfeld A. and Changeux J. P. (1987) J. Cell Biol. 105, 1337-1342; Klarsfeld A. and Changeux J. P. (1985) Proc. natn. Acad. Sci. U.S.A. 82, 4558-4562]. In this paper, we demonstrate that, under these in vitro culture conditions, calcitonin gene-related peptide (0.1 microM) and tetrodotoxin (0.5 microM) regulate to a smaller extent (no more than 2.5-fold above control) the levels of acetylcholine receptor gamma- and delta-subunit mRNAs. No effect of either compound on acetylcholine receptor biosynthesis was observed during the initial three days of culture. The response to calcitonin gene-related peptide was already maximal when the cells were treated between days three and four after plating (about 3-fold increase of the alpha-subunit mRNA level). The effect of tetrodotoxin resulted in a six-fold increase of the acetylcholine receptor alpha-subunit mRNA level in cells treated between days three and four, and still increased when the cells were exposed to tetrodotoxin through days six and eight (up to a maximum of 20-fold).(ABSTRACT TRUNCATED AT 250 WORDS)

Neuronal death and synapse elimination in the olivocerebellar system: III. Cell counts in the inferior olive of developing rats X-irradiated from birth.

The change with age of cell number in the developing inferior olivary nucleus (ION) of the normal rat, compared to the time course of the regression of the polyneuronal innervation of Purkinje cells by olivary axons (i.e., the climbing fibers), suggests that the involution of the redundant olivocerebellar contacts is caused by a reduction of axonal branching rather than by degeneration of the parent cells, this being also suggested by the normal size of the olivary population in adult rodents whose Purkinje cells retain polyneuronal innervation. However, the similar size of the adult ION population does not necessarily imply that the development history is the same in normal and multiply innervated adult rodents. Therefore, cell counts were performed in developing rats which had been repeatedly X-irradiated from birth until postnatal day 14 and which retained polyneuronal innervation. The results show that, although less marked than during normal development, the evolution of the ION population is also characterized by a phase of cell loss followed by a slow increase. However, the number of cells in X-irradiated rats is higher than in their controls from birth to postnatal day 15 but becomes identical at 20 days and later. These data confirm that cell death in the ION does not play a major role in the shaping of olivocerebellar connections.

Peripheral maps and synapse elimination in the cerebellum of the rat. II. Representation of peripheral inputs through the climbing fiber pathway in the posterior vermis of X-irradiated adult rats.

The present study gives a detailed description of the functional characteristics and of the topographic distribution of responses mediated through the climbing fiber (CF) pathway in the cerebellum of adult rats which have been repeatedly irradiated from birth so that the Purkinje cells (PCs) in the adult remained innervated by several climbing fibers instead of one. Experiments were carried out under urethane anaesthesia. After electrical stimulation of the contralateral snout, the ipsilateral and contralateral hindlimb or forepad, and the tail, CF-EPSPs were recorded from PCs in an area extending 1000 microns laterally to the midline in the vermal part of lobules VII and VIII. The stepwise variation of CF-EPSP amplitude demonstrated the multiple innervation of the PCs by CFs in these animals. The responses of a given PC through separate CFs were analyzed separately and, using precise micromapping techniques and computer analysis, cells were located on the map of the unfolded PC layer. Taking into account the mean latency of the responses and the probability of discharge of the PCs, restricted areas of projection were found for the snout, the forepads and the tail. Zones of short-latency responses formed compact patches of approximately 1 mm2. Their disposition was very similar to that found in normal rats. The responses evoked through the different CFs converging on a given PC were in general very homogeneous and very similar to those recorded in control rats. There was some overlap of projection zones from tail and snout and from forepads and snout. In this latter case, there was a convergence of several peripheral inputs on some of the PCs tested. No precise projection of the hindlimbs could be detected in the same lobules. These results suggest that, with the type of stimulation used, the representation of peripheral inputs through CF pathway is roughly conserved even though multiple innervation of PCs by CFs is maintained until adulthood.

Chromosomal localization of muscle nicotinic acetylcholine receptor genes in the mouse.

The chromosomal localization of the genes encoding the four subunits of muscle nicotinic receptor was determined by analyzing restriction fragment length polymorphisms between two mouse species Mus musculus domesticus (DBA/2) and Mus spretus (SPE). Analysis of the progeny of the interspecies mouse backcross (DBA/2 X SPE) X DBA/2 showed that the alpha-subunit gene cosegregates with the alpha-cardiac actin gene on chromosome 17, that the beta-subunit gene is located on chromosome 11, and that the gamma- and delta-subunit genes cosegregate and are located on chromosome 1.

[Note on the relations between vectors of leishmaniasis and forest trees in French Guiana]. / Note sur les relations des vecteurs de leishmaniose avec les essences forestières en Guyane française.

The study of relationships between Phlebotomine sandflies and different species of trees, 0 to 1.5 m above ground, was carried out in the French Guiana forest. We found that certain forest trees are more propitious than others to the development or maintenance of certain leishmaniasis vectors. Lu. umbratilis, vector of Leishmania braziliensis guyanensis, represents between 28 and 88% of samples collected on trunks. The association of Lu. umbratilis and Lu. rorotaensis represents between 58 and 98% Lu. flaviscutellata, vector of Leishmania mexicana amazonensis, frequently caught on humans, was not found on tree trunks.

Neuronal death and synapse elimination in the olivocerebellar system. I. Cell counts in the inferior olive of developing rats.

A transient multiple innervation of cerebellar Purkinje cells by climbing fibers has been described during postnatal development of the rat. The aim of the present study was to determine if the regression of redundant synapses is related to the loss of presynaptic cells in the inferior olivary nucleus (ION), which is the sole source of climbing fibers in rodents. To this end, the population size of the ION was evaluated by counting healthy cells of the four main subnuclei in rats from birth to adulthood. The cell population at birth was found to be very similar to that of the adult animal (27,655 versus 28,385), but a loss of 25% of the cells occurred in the first five days, presumably through their death since degenerating cells were observed over the same period. Although cell loss was found throughout the whole nucleus, it was more pronounced in the medial accessory olive. A subsequent apparent increase of the cell population was observed so that the adult value was again reached at 15 days. The evolution of the ION population is then characterized by a period of moderate cell death which takes place before the peak of polyneuronal innervation of Purkinje cells by olivary axons is attained. This strongly suggests that the removal of the redundant synaptic contacts established by climbing fibers onto Purkinje cells during development is caused by a progressive reduction of the branching of olivary axons rather than by degeneration of the presynaptic cells.

[Natural hosts of Trypanosoma cruzi in French Guiana. High endemicity of zymodeme 1 in wild marsupials]. / Les hôtes naturels de Trypanosoma cruzi en Guyane Francaise. Endémicité élevée du zymodème 1 chez les Marsupiaux sauvages.

During an epidemiological survey in French Guiana, three species of Marsupiala were found infected by Trypanosoma cruzi with high infection rates (30,8% for Didelphis marsupialis). Six Triatomine bug species were recorded, five of them being well known vectors of Chagas' disease. Iso-enzyme characterization of 22 stocks isolated (16 from D. marsupialis, 3 from Philander opossum and 3 from Rhodnius prolixus) revealed that they were all related to zymodeme 1 of Miles. The silvatic cycle is endemic in the various ecotopes studied. The high prevalence rates of infection in D. marsupialis in the human settlement of Cacao and the finding in this locality of domestic breeding of Rhodnius pictipes lead to suspect the occurrence of a peridomestic cycle in this village. The evidence of R. prolixus colonizing houses in the vicinity of Cayenne emphasizes the risk of Chagas' disease in French Guiana.

[Isolation of the Lagos-bat virus in the Central African Republic]. / Isolement du virus Lagos-bat en Empire Centrafricain.

The second reported isolate of Lagos-bat virus has been obtained from bats Micropterus pusillus caught in 1974 in the Central African Empire, thus extending the geographic area of this virus and adding another species of vertebrate host among its reservoirs.