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PubMed1981

Sarcocystis singaporensis Zaman and Colley, (1975) 1976, Sarcocystis villivilliso sp. n., and Sarcocystis zamani sp. n.: development, morphology, and persistence in the laboratory rat, Rattus norvegicus.

Sporocysts obtained in Singapore in the feces of the boid snake, Python reticulatus, were given by mouth to laboratory rats, mice, and a monkey (Macaca mulatta). Infections developed in rats only. Schizonts were observed in vascular endothelium of various tissues of rats examined at 7 to 15 days of infection; and in each of 20 rats examined at 1 mo to 2 yr, cysts of three species of Sarcocystis were observed. Based on observations made by light and electron microscopy, one species was identified as S. singaporensis and redescribed; two species, S. villivillosi and S. zamani, were described as new. The cyst wall of S. singaporensis is thick with tall, stalked, digitiform villi. That of S. villivillosi is moderately thin and bears short, stout villi that are covered with microvilli; and that of S. zamani is thin and bears delicate, branched villi. The cyst of S. zamani is macroscopic with rounded ends; it induces multiplication of host-cell nuclei and causes resorption of the myofibrils. Cysts of the other species are microscopic with fusiform shape that changes markedly with contraction of the host cell. Refrigerated sporocysts of S. singaporensis, S. zamani, and S. villivillosi remained viable for at least 24, 14, and 6 mo, respectively. Sarcocystis singaporensis and S. zamani apparently have been reported previously from several species of Malaysian wild rodents; S. villivillosi represents a unique type in rodents.

Animals↗
PubMed1993

Ticks (Acarina: Ixodidae) of reptiles from central, Lusaka and southern provinces of Zambia.

During the period 1988-1991, reptiles (23 snakes, 36 tortoises, 25 chameleons and 2 monitor lizards) from Central, Lusaka and Southern Provinces of Zambia were caught and checked for ticks. Only 2 snakes, respectively one Python sebae (Gmelin, 1789) and one Bitis arietans (Merrem, 1820), 8 tortoises, respectively seven Geochelone pardalis (Bell, 1828) and one Kinixys belliana (Gray, 1831) were found infested with a small number of ticks: nymphs and adults of Aponomma latum (Koch, 1844) and Amblyomma marmoreum Koch, 1844. Ticks were not observed on chameleons Chamaeleo dilepis (Leach, 1819) and monitor lizards Varanus niloticus (Linneo, 1758). The author makes some observations about the role and the effects of ticks on reptiles and discusses the present findings, comparing the data provided by other authors.

Animals↗
PubMed1996

Sarcocystis singaporensis: studies on host specificity, pathogenicity, and potential use as a biocontrol agent of wild rats.

Host specificity and pathogenicity of Sarcocystis singaporensis were investigated as a prerequisite to a subsequent application of the parasite as a biocontrol agent of wild rats in Egypt. After inoculation of 7 snake species comprising the families Elapidae, Viperidae, Colubridae, and Boidae with sarcocysts, sporocyst development was only observed in a reticulated python. Among amphibians, reptiles, and rodents that orally received various sporocyst doses in the laboratory, 2 x 10(4) sporocysts or more were lethal to roof rats Rattus rattus frugivorous, brown rats Rattus norvegicus, and bandicoot rats Nesokia indica. Sarcocysts developed in Rattus spp. and Nile grass rats Arvicanthis niloticus. Subsequently, the pathogenicity of S. singaporensis was tested under natural control situations offering bait pellets containing high amounts of sporocysts to a free-living population of roof rats, which was monitored by indirect census baiting commonly used in rodenticide evaluation. Ten days after consumption of the bait pellets, the infected population collapsed, leading to a control success of 73%. A negative control population, which received a placebo, remained stable. These data demonstrate for the first time that S. singaporensis can be used as a biocontrol agent of wild rats. However, an immunization experiment with roof rats in the laboratory showed that these are capable of mounting a rapid specific immune response resulting in survival of acute sarcocystosis.

Amphibians↗
PubMed1996

[Radiologic diagnosis for a Gabonese case].

We describe a case of porocephalosis diagnosed in a 50 year old Gabonese male hospitalized in France for a HIV-related renal insufficiency. A standard abdominal radiography showed numerous ring-shaped calcifications, predominantly in the hepatic area. This aspect was very suggestive of the diagnosis in a patient living in Central Africa and eating occasionally meat of snake. The parasites live normally in the lungs of snakes (python, Bitis sp.). People become infected in eating undercooked snake or in handling snakes. In the majority of cases, the disease is asymptomatic and diagnosis made accidentally as in the case of our patient.

Animals↗
PubMed2002

Adult-like complexity of the larval antennal lobe of D. melanogaster despite markedly low numbers of odorant receptor neurons.

We provide a detailed analysis of the larval head chemosensory system of Drosophila melanogaster, based on confocal microscopy of cell-specific reporter gene expression in P[GAL4] enhancer trap lines. In particular, we describe the neuronal composition of three external and three pharyngeal chemosensory organs, the nerve tracts chosen by their afferents, and their central target regions. With a total of 21 olfactory and 80 gustatory neurons, the sensory level is numerically much simpler than that of the adult. Moreover, its design is different than in the adult, showing an association between smell and taste sensilla. In contrast, the first-order relay of the olfactory afferents, the larval antennal lobe (LAL), exhibits adult-like features both in terms of structure and cell number. It shows a division into approximately 30 subunits, reminiscent of glomeruli in the adult antennal lobe. Taken together, the design of the larval chemosensory system is a "hybrid," with larval-specific features in the periphery and central characteristics in common with the adult. The largely reduced numbers of afferents and the similar architecture of the LAL and the adult antennal lobe, render the larval chemosensory system of Drosophila a valuable model system, both for studying smell and taste and for examining the development of its adult organization.

Animal Structures↗
PubMed2026

Practicing Data Science in Interactive Notebooks.

The Jupyter Notebook is a platform for interactive computing that displays code and results in the same browser, making it valuable for teaching, prototyping, data analysis, and collaboration. Its explicit and transparent structure greatly reproducibility while its backend server supports flexible deployment. In the past few years, Jupyter notebooks and similar tools have become increasingly popular. In this chapter, we will review key aspects of data analysis in a cloud environment and demonstrate common tasks for analyzing metabolomics data using template notebooks. This is an accompaniment to the basic bioinformatics tools and essential data science toolkit introduced in the first edition.

Software↗
PubMed1996

Effects of a D2 receptor agonist RO 41-9067 alone and with clonidine on sleep parameters in the rat.

The effects of RO 41-9067, a D2 dopamine receptors agonist, on different sleep parameters were studied in the rat. RO 41-9067 dose dependently decreased paradoxical sleep, and only at the higher dose increased waking during the light period. In contrast, the higher dose of RO 41-9067 increased paradoxical sleep and decreased waking during the dark period. Finally, the combination of RO 41-9067 and clonidine significantly prevent the decrease of total sleep time and paradoxical sleep found after clonidine alone. These results, compared with those of classical D2 dopamine receptors agonists, suggest an action for RO 41-9067 on D2 dopamine receptors depending on the cerebral structure, a different action particularly on the striatum and/or on the structures responsible for paradoxical sleep. An active role for D2 dopamine receptors and an interaction between noradrenergic and dopaminergic systems in the regulation of sleep is proposed.

Adrenergic alpha-Agonists↗
PubMed2001

Extracellular serotonin variations during vigilance states in the preoptic area of rats: a microdialysis study.

Numerous studies have shown that serotonergic transmission decreases from waking (W) to slow wave sleep (SWS) to paradoxical sleep (PS), suggesting an active role of serotonin (5-HT) in W but not in sleep. Conversely, the inhibition of 5-HT activity produces insomnia. This insomnia can be reversed by injections of 5-hydroxytryptophan in the preoptic area (POA), suggesting that 5-HT is necessary in this cerebral structure for sleep. Using microdialysis, we studied, 5-HT variations in the POA of rats in relation to vigilance states. 5-HT levels were higher during W than during during SWS and PS. 5-HT increased just before the rats fell asleep and then decreased during sleep. A decreased 5-HT transmission was also observed from SWS to PS. These data document a positive correlation between 5-HT levels in POA and wakefulness. Moreover, these observations are in favour of a permissive role of 5-HT in the POA during PS. A comparison between the POA and the prefrontal cortex in the sleep-wake cycle is discussed.

Animals↗
PubMed1997

Effects of nisoxetine, a selective noradrenaline transporter blocker, on sleep in rats.

Nisoxetine has been shown to block specifically noradrenaline (NA) reuptake. Therefore, this potential antidepressant is a valuable tool for investigating the involvement of the NA system in sleep regulation. This study aimed to investigate the effects of different doses of nisoxetine on sleep parameters in rats. The main effects were observed with the highest dose and concern paradoxical sleep (PS). Indeed, although total sleep time was not modified, PS appeared later and its amount and the number of its episodes were reduced. These changes suggest a critical involvement of NA in the induction of PS.

Animals↗
PubMed1993

Thapsigargin inhibits voltage-activated calcium channels in adrenal glomerulosa cells.

Thapsigargin, an inhibitor of the microsomal Ca2+ pumps, has been extensively used to study the intracellular Ca2+ pool participating in the generation of the agonist-induced Ca2+ signal in various cell types. A dual effect of this agent was observed in bovine adrenal zona glomerulosa cells. At nanomolar concentrations, thapsigargin stimulated a sustained Ca2+ influx, probably resulting from Ca(2+)-store depletion. In contrast, when added at micromolar concentrations, thapsigargin prevented the rise in cytosolic free Ca2+ concentration ([Ca2+]c) induced by K+. This inhibitory effect of thapsigargin on voltage-activated Ca2+ channels was confirmed by measuring Ba2+ currents by the patch-clamp technique. Both low-threshold (T-type) and high-threshold (L-type) Ca2+ channels were affected by micromolar concentrations of thapsigargin. Analysis of the current-voltage relationship for T-type channels revealed that thapsigargin did not modify the sensitivity of these channels to the voltage, but decreased the maximal current flowing through the channels. In conclusion, thapsigargin appears to exert a dual effect on adrenal glomerulosa cells. At lower concentrations, this agent induces a sustained Ca2+ entry, whereas at higher concentrations it decreases [Ca2+]c by blocking voltage-activated Ca2+ channels.

Animals↗
PubMed1995

The site of action of Ca2+ in the activation of steroidogenesis: studies in Ca(2+)-clamped bovine adrenal zona-glomerulosa cells.

The Ca(2+)-messenger system plays a crucial role in the regulation of steroid production in adrenal zona-glomerulosa cells, as it is known to mediate the action of both angiotensin II and K+. In the present study we used intact isolated glomerulosa cells in which the cytosolic free Ca2+ concentration ([Ca2+]c) was clamped at various levels with the Ca2+ ionophore ionomycin in order to locate the site(s) of action of Ca2+. By measuring in parallel steroid synthesis and [Ca2+]c, we show that Ca2+ levels (50-860 nM) regulate the production of both pregnenolone (up to 669 +/- 71.1% of the basal production) and aldosterone (up to 301 +/- 42.2%; EC50 = 303 nM). By contrast, Ca2+ did not stimulate the conversion of 11-deoxycorticosterone into aldosterone. Ca2+ modulation did not affect the formation of pregnenolone from freely diffusible analogues of cholesterol, indicating that Ca2+ acts at a step upstream of cholesterol side-chain cleavage. Moreover cycloheximide, an inhibitor of protein translation and of adrenocorticotropin-induced facilitation of intramitochondrial cholesterol transport, the rate-limiting step in steroidogenesis, also blocked Ca(2+)-triggered pregnenolone formation. This is consistent with a model in which Ca2+ promotes cholesterol transfer between mitochondrial membranes. In addition, agents using the cyclic AMP pathway as well as angiotensin II potentiated the steroidogenic response to increases in [Ca2+]c by augmenting both the efficacy and the potency of Ca2+. This effect of angiotensin II did not involve protein kinase C. These results establish a direct link between agonist-induced [Ca2+]c rises and a specific step of the steroidogenic pathway.

Aldosterone↗
PubMed2002

Fine-mapping of the intestinal receptor locus for enterotoxigenic Escherichia coli F4ac on porcine chromosome 13.

The aim of this study was to refine the localization of the receptor locus for fimbriae F4ac. Small intestinal enterocyte preparations from 187 pigs were phenotyped by an in vitro adhesion test using two strains of Escherichia coli representing the variants F4ab and F4ac. The three-generation pedigree comprised eight founders, 18 F1 and 174 F2 animals, for a total of 200 pigs available for the linkage analysis. Results of the adhesion tests on 171 F2 pigs slaughtered at 8 weeks of age show that 23.5% of the pigs were adhesive for F4ab and non-adhesive for F4ac (phenotype F4abR+/F4acR-; R means receptor). Pigs of this phenotype were characterized by a weak adhesion receptor for F4ab. No pigs were found expressing only F4acR and lacking F4abR. Receptors for F4ab and F4ac (F4abR+/F4acR+) were expressed by 54.5% of the pigs. Animals of this phenotype strongly bound both F4ab and F4ac E. coli. In the segregation study, the serum transferrin (TF) gene and 10 microsatellites on chromosome 13 were linked with F4acR (recombination fractions (theta) between 0.00 and 0.11 and lod score values (Z) between 11.4 and 40.4). The 11-point analysis indicates the F4acR locus was located in the interval S0068-Sw1030 close to S0075 and Sw225, with recombination fractions (theta) of 0.05 between F4acR and S0068, 0.04 with Sw1030, and 0.00 with S0075 and Sw225. The lack of pigs displaying the F4abR-/F4acR+ phenotype and the presence of two phenotypes for F4abR (a strong receptor present in phenotype F4abR+/F4acR+ and a weak receptor in phenotype F4abR+/F4acR-) led us to conclude that the receptor for F4ac binds F4ab bacteria as well, and that it is controlled by one gene localized between S0068 and Sw1030 on chromosome 13.

Animals↗
PubMed1995

Inhibition of low threshold calcium channels by angiotensin II in adrenal glomerulosa cells through activation of protein kinase C.

In adrenal glomerulosa cells, low threshold voltage-activated (T-type) calcium channels play a crucial role in coupling physiological variations of extracellular potassium to aldosterone biosynthesis. Angiotensin II markedly reduced the activity of these channels by shifting their activation curve toward positive voltage values. This inhibition of the channels resulted in a marked decrease of the cytosolic free calcium concentration maintained by potassium. This effect was abolished by losartan, a specific antagonist of the angiotensin II AT1 receptor. Hormone action on T-type channels appeared to be mediated by protein kinase C because 1) it was mimicked by phorbol ester and diacylglycerol, and 2) it was significantly reduced by decreasing protein kinase C activity with specific inhibitors such as chelerythrine chloride or a pseudosubstrate of the enzyme, as well as by protein kinase C down-regulation. Similarly, protein kinase C activation reduced the cytosolic calcium response to potassium and the steroidogenic action of this agonist. Low threshold T-type calcium channels therefore appear as potential sites for the modulation of steroidogenesis by protein kinase C in adrenal glomerulosa cells.

Aldosterone↗
PubMed1996

Activation of yeast protein kinase C by Rho1 GTPase.

We have investigated the role of the essential Rho1 GTPase in cell integrity signaling in budding yeast. Conditional rho1 mutants display a cell lysis defect that is similar to that of mutants in the cell integrity signaling pathway mediated by protein kinase C (Pkc1), which is suppressed by overexpression of Pkc1.rho1 mutants are also impaired in pathway activation in response to growth at elevated temperature. Pkc1 co-immunoprecipitates with Rho1 in yeast extracts, and recombinant Rho1 associates with Pkc1 in vitro in a GTP-dependent manner. Recombinant Rho1 confers upon Pkc1 the ability to be stimulated by phosphatidylserine, indicating that Rho1 controls signal transmission through Pkc1.

Cell Cycle Proteins↗
PubMed1995

Effects of WIN 35,428 a potent antagonist of dopamine transporter on sleep and locomotor activity in rats.

The new cocaine derivative CFT naphthalene sulphonate (WIN 35,428), has been shown to have a considerably longer duration of action and greater potency than cocaine as a central stimulant and it appears to have a similar mode of action on dopamine (DA) systems. The purpose of the present study was first to investigate the effects of low doses of WIM 35,428 with particular reference to the involvement of dopaminergic system in paradoxical sleep (PS), other sleep parameters and locomotor activity in the rat. WIN 35,428 a potent ligand of dopamine transporter showed biphasic effects upon PS and locomotor activity with low doses increasing and high doses decreasing PS. These changes reflect a functional involvement probably relevant to the action of Win 35,428 on DA transporters.

Analysis of Variance↗
PubMed1998

Microdialysis and EEG in rats reveal cortical PGE2 changes during sleep and wakefulness.

Prostaglandin (PG) E2 production was assessed in freely moving rats using the technique of microdialysis in the prefrontal cortex associated with parallel cortical EEG recordings. PGE2 concentrations were 40% higher during wakefulness than during slow wave sleep. PGE2 values varied during wakefulness with a maximal increase in the middle of the stage and a drop towards lower values before the occurrence of slow wave sleep. These variations were similar to those observed previously in the rostromedial hypothalamus, where PGE2 concentration was 2.6 times lower than that in the cortex. These data document a positive correlation between cortical EEG activation and PGE2 levels. Taken together with pharmacological data on the awakening effect of centrally administered PGE2, these observations are in favor of an involvement of PGE2 in the generation of wakefulness.

Animals↗
PubMed2000

Neuromodulation of the prefrontal cortex during sleep: a microdialysis study in rats.

To test the hypothesis that biogenic amines of the prefrontal cortex are involved in state-dependent cortical and behavioural activation, changes in extracellular levels of serotonin (5-HT), dopamine (DA), and noradrenaline (NA) were determined during the sleep-wake cycle in freely moving rats using microdialysis probes with parallel EEG recording. Serotonin gradually increased up to 450% during wakefulness (W) as compared to slow wave sleep (SWS), before decreasing toward stable levels during the next episode of SWS. Dopamine and its metabolite homovanillic acid (HVA) were reduced during W as compared to SWS. Although contradictory with the generally admitted enhancement of DA activity related to vigilance, this may be due to the particular role of DA neurons in the prefrontal cortex. However, DA and HVA showed dramatic changes announcing the transition between SWS and W. During paradoxical sleep (PS), DA and 5-HT showed complex changes, the direction of which depended on whether PS was followed by SWS or W. Biogenic amines of the prefrontal cortex are probably involved in cortical and behavioural activation.

Animals↗