Influence de la concentration du glucose et de l'azote sur la morphologie de Candida albicans et la formation de ses chlamydospores dans un milieu de culture synthétique

Résumé Candida albicans a été cultivé à l'obsurité, à 28 °C, dans un milieu de culture synthétique liquide dans lequel on fait varier les concentrations de glucose et d'azote. Des indices de chlamydosporulation ont pu etre calculés pour les milieux contenant au plus 0,08 g/l de glucose. Lorsque la concentration de glucose est plus importante, les thalles pseudomycéliens portent, dans certains cas, de nombreuses chlamydospores, mais aussi des chaines de cellules à contenu dense; ces thalles bourgeonnent des éléments levuriformes qui se détachent et continuent à bourgeonner dans le milieu de culture. Les différentes morphologies rencontrées sont décrites, illustrées et ordonnées en fonction des concentrations de glucose et d'azote du milieu.

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Candida albicans was grown in the darkness, at 28 °C, in a synthetic medium in which glucose and nitrogen concentrations were varied. Numeric appraisal of the chlamydospore index was possible only in the medium where glucose concentration was 0,08 g/l or less. When the glucose concentration raised, pseudomycelial thalli bore numerous chlamydospores but sometimes also chains of cells with a dense granular content. These thalli bud yeast cells which separate and bud again in the medium. The different morphological aspects of the cultures are decribed, illustrated and classified according to the glucose and nitrogen concentration of the medium.

     

Le chanvre (Cannabis sativa L.) : une plante cultivée à la fin de l'âge du Fer en France du Sud-Ouest ?

The ancient history of hemp (Cannabis sativa) is poorly documented in France and western Europe. Up to now, the oldest Cannabis seeds were not recorded in that area before Roman times. The waterlogged assemblage of the bottom valley site of Al Poux (Fontanes, Lot, France) delivered seeds that probably attest Cannabis cultivation in southwestern France as early as the Late Iron Age. Hemp was possibly grown in riverbank fields, but it could also have been carried to the settlement to be retted in the river. The special role of waterlogged assemblages in the preservation of hemp seeds is emphasised. It is stated that new investigations on this kind of context would be especially helpful to improve our knowledge of ancient hemp cultivation history. To cite this article: L. Bouby, C. R. Palevol 1 (2002) 89–95.     

Le « Moustérien » de Tipasa et de Ténès (littoral ouest algérois) dans la lecture climatique du second pléniglacaire

The excavations that we undertook, in 1985, in the prehistoric site of Sidi Saïd, in Tipasa (Algeria), allowed us to observe an unusual archaeological stratigraphy. An aterian industry with pedunculated pieces, surmounted by a Mousterian, rich in scrapers and single-sided retouching points, almost systematically in flint, with reduced shapes and strongly reduced (Aterian under Mousterian). This unusual case has led us to consider the reading of the Mousterian-Aterian/Ibéromaurusien passage in a different way and at the same time to take a new look at the work carried out so far on the west coast of Algiers, especially those of Lower cave of the Tenes lighthouse, west of Tipasa. An attempt to compare and correlate the site of Sidi Said and the Lower Cave of the Ténès lighthouse, enabled us to consolidate our conviction on the existence of an aterian stratigraphically below the Mousterian and to discover an original lithic industry of Mousterian tradition, with strongly reduced forms, which would be placed between stratigraphically between the Aterian and the Iberomaurusian. This industry which does not yet have a name or place in the chronology, “curiously” recalls the case of the Middle Solutrean of southwestern Europe, in the context of the second pleniglacial.     

Contribution à la connaissance des Desmidiées du Sud-est de la Province de Québec et de la Gaspésie

Sans résumé     

Génétique moléculaire de la transposition du bras long du chromosome x sur l'y lors de la spéciation humaine

Five cosmidic probes (7 b; 8 j; 22 b; CB 16 and 115 i 1) recognizes site of simple-copy DNA sequence homology between the human X and Y chromosomes. Genomic DNAS restricted with Eco RI from the great apes (Gorilla and Pan) were examined for sequences homologous to these probes, by molecular hybridization studies. Experiments reported here revealed, by genetic dosage with sex, that the great apes have homologous sequences of these five probes on their X chromosomes only. The simplest explanation of these results is that the corresponding sequences were transposed from the X chromosome to the Y chromosome after the human line diverged, like probe pDP 34 for locus DXY S1 (Page et al., 1984).     

Aspects originaux de la trichinose domestique à partir d'une infestation familiale découverte à Montréal

An outbreak of domestic trichinosis occurred in an Italian family living in Montreal. All patients had a fever, facial edema and extreme eosinophilia, and results of serologic tests were positive. Larvae of Trichinella spiralis were seen in a muscle biopsy from one of the patients. The discussion emphasizes some characteristic clinical, serologic and histopathological aspects.     

Le syndrome de kallmann de morsier aspect génétique

Kallmann syndrome (KS) is a rare, heterogeneous disorder consisting of congenital hypogonadotropic hypogonadism, associated with anosmia (or hyposmia) and other clinical manifestations such as mirror movements, and renal, urological and neurosensory disorders. The presence of anosmia with micropenis in boys is suggestive of the diagnostic of KS. In KS, the GnRH neurons do not migrate correctly from the olfactory placode to the hypothalamus during development and olfactory bulbs also fail to form, leading to anosmia. Mutations in KAL1 which encodes Anosmin-1, are responsible for the X-linked form of KS. Anosmin-1 is normally expressed in the brain, facial mesenchyme, mesonephros and metanephros. It is required to promote migration of GnRH neurons into the hypothalamus. It also allows migration of olfactory neurons from the olfactory bulbs to the hypothalamus. The loss of function mutations in FGFR1 “fibroblast growth factor” were identified in 2003 as a cause of autosomal forms of this disease. An additional autosomal cause of Kallmann syndrome was recently identified by a mutation in the prokineticin receptor-2 gene (PROKR2) (KAL-3) and its ligand prokineticin 2 (PROK2) (KAL-4). Mutations in these genes induce various degrees of olfactory and reproductive dysfunction, but not the other symptoms seen in KAL-1 and KAL-2 forms of KS. Neuropilin2, which has an important role in migration of GnRH neurons, is a recent candidate gene for KS. The authors describe the genetic features and recent findings of KS, necessary to understand this disease.     

Cytochrome P450 et activation génétique — de la pharmacologie à l’élimination du cholestérol et à la régression de l’athérosclérose

Background

Lipoproteins are closely associated with the atherosclerotic vascular process. Elevated levels of highdensity lipoprotein cholesterol (HDL-C) and apolipoprotein AI (apo AI) in plasma indicate a low probability of coronary heart disease (CHD) together with enhanced longevity, and elevated levels of low-density lipoproteincholesterol (LDL-C) and apo B indicate an increased risk of CHD and death. Studies linking gene activation and the induction of cytochrome P450 with elevated plasma levels of apo AI and HDL-C and lowered plasma levels of LDL-C presented a new potential approach to prevent and treat atherosclerotic disease.

Objective and methods

This is a review aimed at clarifying the effects of P450-enzymes and gene activation on cholesterol homeostasis, the atherosclerotic vascular process, prevention and regression of atherosclerosis and the manifestation of atherosclerotic disease, particularly CHD, the leading cause of death in the world.

Results

P450-enzymes maintain cellular cholesterol homeostasis. They respond to cholesterol accumulation by enhancing the generation of hydroxycholesterols (oxysterols) and activating cholesterol-eliminating mechanisms. The CYP7A1, CYP27A1, CYP46A1 and CYP3A4 enzymes generate major oxysterols that enter the circulation. The oxysterols activate — via nuclear receptors — ATP-binding cassette (ABC) A1 and other genes, leading to the elimination of excess cholesterol and protecting arteries from atherosclerosis. Several drugs and nonpharmacologic compounds are ligands for the liver X receptor, pregnane X receptor and other receptors, activate P450 and other genes involved in cholesterol elimination, prevent or regress atherosclerosis and reduce cardiovascular events.

Conclusions

P450-enzymes are essential in the physiological maintenance of cholesterol balance. They activate mechanisms which eliminate excess cholesterol and counteract the atherosclerotic process. Several drugs and nonpharmacologic compounds induce P450 and other genes, prevent or regress atherosclerosis and reduce the occurrence of non-fatal and fatal CHD and other atherosclerotic diseases.     

Le cancer de la verge : à propos d’un cas et revue de la littérature

Cancer of the penis is rare. It often raises the issue of acceptability of the amputation of penis. We report a case of cancer of the penis following a late circumcision. The treatment consisted of amputation of two-thirds of the penis. The patient is alive without any local recurrence 2 years after surgery. Literature review suggests that this type of cancer is very rare. The factors associated with such cancer include lack of circumcision and infection with human papilloma virus.     

Effets d’une exposition à la Vinclozoline et à la Génistéine de la gestation à l’âge adulte sur la fonction de reproduction du ratWistar mâle: protocole et résultats préliminaires

Current evidence indicates that endocrine disrupters (EDs) can induce adverse effects on the male reproductive tract in various mammalian species. Recent reports indicate deterioration in male reproductive health in several human populations, but the evidence for a causal link with endocrine disruption is still weak. In addition, the experimental conditions of most of the reportedin vivo studies are not representative of environmental exposures (for example, high doses, short-term exposure, a single ED) and the mechanisms by which EDs disrupt the reproductive system are poorly understood. The objective of the present study is to develop an animal model to assess the reproductive effects and study the putative cellular and molecular mechanisms involved after exposure to genistein (phytoestrogen) and vinclozolin (fungicide with a known antiandrogenic potential) alone or in combination. The study will be performed in male Wistar rats, with administration of low and high doses of the compounds from conception to adulthood and a subset of the males in each treatment group will be mated with unexposed females. We plan to assess the level of sperm production, histology of the reproductive organs, motility and morphometry of spermatozoa and hormone levels, as well as DNA fragmentation of spermatozoa and determination of the number of germ cells, Sertoli cells and the diameters of seminiferous tubules. Estrogen, androgen, progesterone and FSH receptors will be detected and quantified and the level of testicular apoptosis and several apoptosis pathways will be studied to determine the putative cellular and molecular mechanisms involved. The preliminary results confirmed the developmental effects previously reported for high doses of vinclozolin. More interestingly, they indicated a number of deleterious effects for male rats exposed to low dosages alone or mixtures of low and high dosages compared to controls and rats exposed to high dosages alone. For example, a number of developmental anomalies of the genitalia were observed and a significant decrease of sperm motility and motion and fertilizing ability were observed. These preliminary results provide evidence that chronic exposure to environmental levels of EDs or mixtures of EDs have a detrimental impact on the male reproductive tract. The next step involves assessment of the anatomical disorders and the study of some of the cellular and molecular mechanisms possibly involved.     

Apports de la géologie et de la géomorphologie à l’étude du mégalithisme : identifier,interpréter,dater

The contribution of geology and geomorphology to architectural and technological study of the Atlantic coast of France megaliths is important and can be grouped into three main axes: to identify, interpret and dating. Identification refers to the sourcing of the megalithic materiel from 0 to 7 km, sometimes around 10 km, or even exceptionally around 30 km. It is never the entire supply that is affected by such long distances but only a few blocks, some of them are remarkably well staged in the megalithic architecture. Another contribution lies in a fresh look at the management of stone recognized through the modes of acquisition, transformation and use of the raw material. More particularly, the geomorphology associated with technological reading offers tools for recognizing ancient standing stones. In the context of the interpretation of funerary chambers, the two sciences open a large window on the modalities of the internal structuring of monuments. From the entrance to the end of the chamber, the organization and use of the space is documented, sometimes a symbolic coding emerges from the mineral walls. This symbolic coding is based on particular petrography, on surface conditions operating a subdivision of space, on granulometries and homogeneities of differentiated surfaces. The internal organization can also be marked with natural “patterns”, which refer to a completely new aspect of Neolithic thought. Finally, the last axis concerns relative dating, by recognizing forms of postmegalithic fossil erosion, geomorphology makes it possible to identify reused stelae. A very important tool in a current research context where an important episode of reuse of standing stones at the end of the middle Neolithic is anticipated in the construction of dolmens in the south of France.     

Endémie bilharzienne à Schistosoma mansoni à la vallée du Kou : caractérisation du système de transmission et impact socioéconomique

Schistosomiasis is one of the waterborne diseases which benefit from environmental and behavioral changes induced by the mobilization of surface water resources in Sahelian countries, such as Burkina Faso. Studies have established the existence of human schistosomiasis in the Kou valley, one of the oldest hydro-agricultural zones in the country. However, the role of population behavior in the transmission pattern of this disease and its socioeconomic impact in this valley are poorly understood. It is in response to these questions that this study was undertaken. The objectives of this study were to identify activities that exposed most of the Valley's population to infection by schistosomiasis, and to contribute knowledge on the consequences of this disease. The study was conducted in the cold dry season at the Kou Valley, located in the South Sudanese area of Burkina Faso. It has adopted the strategy of direct observation to examine host–parasites interactions. The study of the socioeconomic consequences of the infection has been first to identify subjects that actually carry the parasite by screening the population by the Kato–Katz method. These were then subjected to a questionnaire. Data were analyzed using Epi Info 6.4. This work has revealed six activities at risk of infection for the residents of the Valley with an increased risk of factor for rice farming, household activities and swimming. In view of these activities, women and young people seem to be most vulnerable to infection. This disease causes significant economic losses as a function of socio-professional categories of infected persons.     

Eléments d'observation sur la cinématique,la dynamique et l'énergétique de la locomotion dans le courant chez une larve de Trichoptère à fourreau

Observations on the kinetics, dynamics and energetics of the locomotion in the current of a case-bearing Trichoptera larva. The locomotion of Trichoptera larvae was studied by means of films. It follows a sequence similar to that usually observed in walking insects, with protraction of legs from behind to forward (Fig. 1). The walking is slow. In a current, the sequence of protraction is often modified by supplementary protractions of the anterior and middle legs (exploration or skidding). The locomotion includes phase a (advance of the body) and phase b (case towing, with protractcion of posterior leg). These two phases are more clearly separated in a current than with a force (Fig. 4, 5). These two phases agree perfectly with the basic pattern described by Denis (1968) for the larval case construction. The current causes a decrease in the mean locomotion speed (L_m) by shortening and above all separating the towing phases, which are the only moments for the rapid advance of the case (Tabl. I). Turbulent water causes the case to vibrate and these vibrations vary in amplitude (from 0.1 to 2 mm) with water velocity, but not significantly. The frequency of the vibrations does not seem to go above 15 oscillations per second (above 20 cm/s), but it is possible that higher frequencies could not be correctly registered at 64 pictures per second. These vibrations may be the cause of the higher activity in the current than under a traction force without vibrations (Bournaud, 1973). The coefficient of resistance (C_w) of the larva-case complex is high (near 0,89) at velocities above 55 cm/s, but is much higher at velocities below 55 cm/s (Fig. 7). So the case of M. testacea is better adapted to high current velocities. The 55 cm/s limit also corresponds to the velocity for changes in aspects of the behaviour of this species: rate of activity, beginning of rheokinesis stage, disappearance of negative locomotion. The minimum quantity of energy necessary for regular locomotion is from 2.6 to 3.3 × 10⁻³ kgm/s/kg fresh weight, at the rheokinesis stage (absolute maximum: 10.2 × 10⁻³ kgm/s/kg). The real energetic expenditure (R_g), including the rate of activity, is much lower (0.03 to 1 × 10⁻³ kgm/s/kg), while the energetic expenditure during the towing phases (instantaneous rheokinesis) is much higher (up to 50 × 10⁻³ kgm/s/kg) (Tabl. II). However all these values are lower than those found in the animal kingdom, and the mean traction strength of M. testacea is very high (up to 29 times the larval weight). Therefore this species uses more of its energy in traction than in speed, the opposite to the situation in fishes. It is an ethological adaptation to life in a current, reinforced by the necessity of pulling a case which increases the force of the current. The available energy E obtained by the consumption of oxygen is 86.3 × 10⁻³ kgm/s/kg in still water. It is larger than (or equal to) the instantaneous rheokinesis (R_i) in the current. Only part of the energy E is transformed into muscular energy measured by R_i. Since a 30 cm/s current produces an increase in metabolism of about 30 × 10⁻³ kgm/s/kg, the needs for muscular energy R_i increase too fast to be covered only by the basal level of metabolism in still water. In fact, only a part of the muscular energy R_i (about 1 to 3%) is transformed into strictly locomotion R_g, so that this energy requirement needs less than 1/1000 of the energy obtained by metabolism in still water (Tabl. II).