1,287 research outputs found
Modalités de la compétition larvaire intraspécifique chez Bruchus affinis (Coleoptera, Bruchidae) dans les graines de Lathyrus sylvestris (Leguminosae, Fabaceae)
Summary. — In spring, a high concentration of Bruchus affinis eggs laid on the first appearing pods of Lathyrus sylvestris is responsible for an important intraspecific larval competition during the colonization of growing ovules. A single adult emerges from the seed, even if the seed has been infested by several larvae.
We studied the patterns of this competition. Growth and development of B. affinis larvae are concommitent with the ones of infested ovules, and two main characteristics can be pointed out : a first larval ecdysis after the colonization of a growing ovule and a larval tendency to settle down in the center of cotyledons. Larval competition is closely related to a noticeable territorial behaviour of the larvae.
Meetings of larvae moving towards the centre turn them in a situation of agression. When a larva casually meets another one from the side or the rear, it can hurt it with its mouth parts and kill it. Nevertheless, a larva which is already in the center of a wider gallery shows a greater mobility and kills more easily an approaching larva.
The bigger (or older) larva is not necessarily the «winner» of the competition even if it is generally favoured by its central position and greater mobility.Résumé. — Au printemps, la forte concentration des pontes de Bruchus affinis sur les premières gousses formées de Lathyrus sylvestris est à l'origine d'une importante compétition larvaire intra-spécifique au moment de la colonisation des ovules en croissance. Un seul adulte émerge de la graine même si celle-ci a été colonisée par plusieurs larves.
L'analyse des modalités de cette compétition est abordée. La croissance et le développement des larves de B. affinis sont concomitants de ceux des ovules colonisés et deux caractéristiques se dégagent : première mue larvaire après occupation d'un ovule en croissance et tendance larvaire à occuper le centre des cotylédons. La compétition larvaire est en relation étroite avec un comportement territorial très marqué de la larve.
Les rencontres fortuites par recoupement des galeries larvaires lors de la progression vers le centre mettent les larves en situation de compétition. Lorsque'une larve en rejoint fortuitement une autre sur le côté ou par derrière, elle peut la blesser avec ses pièces buccales et l'éliminer. Mais une larve, déjà au centre dans une galerie plus large, a une mobilité plus grande et élimine plus facilement toute autre larve tentant de la rejoindre.
La larve la plus grosse (ou la plus âgée) n'est pas nécessairement le «vainqueur» de la compétition, bien qu'elle soit en général plus favorisée par sa position au centre et sa meilleure mobilité.N'diaye Saliou, Fabres Gérard, Labeyrie Vincent. Modalités de la compétition larvaire intraspécifique chez Bruchus affinis (Coleoptera, Bruchidae) dans les graines de Lathyrus sylvestris (Leguminosae, Fabaceae). In: Bulletin de la Société entomologique de France, volume 97 (2), juin 1992. pp. 135-144
Pathogenicity of local Metarhizium anisopliae var. acridum strains on Locusta migratoria migratorioides Reiche and Farmaire and Zonocerus variegatus Linnaeus in Senegal
Locusts and grasshoppers are the most important economical threat in the sahelian agricultural system. Principal control strategies of these pests are synthetic chemicals which are, however, harmful to the environment and human health. Metarhizium anisopliae based biopesticide Green Muscle IMI330189 has been recently developed for the control of locusts and grasshoppers. In this paper, we assessed the pathogenicity of three local strains of M. anisopliae var. acridum on Locusta migratoria migratorioides and Zonocerus variegatus, in comparison to the commercial product, IMI330189. There was various level of pathogenicity within the strains on the two pests. On L. migratoria, DPV5 caused the highest mortality after three weeks (91.2%). There was a significant difference between DPV5 and IMI330189. However, there were no significant differences between IMI330189 and the other strains. On Z. variegatus there were no significant differences between IMI330189 DPV5 and DPV10. DPV15 had the lowest pathogenic activity. Moreover, the comparison of susceptibility of both insect pests to Metarhizium strains showed that L. migratoria is more susceptible than Z. variegatus. DPV5 had the shortest LT50 on L. migratoria 7.1 days whereas on Z. variegatus, the LT50 value of DPV5 was comparable to IMI330189. Our study suggests that, DPV5 which was isolated from Kraussaria angulifera in Senegal is a promising candidate for future development for locusts and grasshoppers control in the country.Keywords: Green Muscle, African migratory locust, grasshoppers, local strains, biopesticide
Plasmodium falciparum malaria co-infection with tick-borne relapsing fever in Dakar
Abstract
Background
West African tick-borne relapsing fever (TBRF) due to Borrelia crocidurae and malaria are co-endemics in Senegal. Although expected to be high, co-infections are rarely reported. A case of falciparum malaria and B. crocidurae co-infection in a patient from Velingara (South of Senegal) is discussed.
Case
A 28\ua0year-old-male patient presented to Aristide Le Dantec Hospital for recurrent fever. He initially presented to a local post health of Pikine (sub-urban of Dakar) and was diagnosed for malaria on the basis of positive malaria rapid diagnostic test (RDT) specific to Plamodium falciparum . The patient was treated as uncomplicated falciparum malaria. Four days after admission the patient was referred to Le Dantec Hospital. He presented with fever (39\ua0\ub0C), soreness, headache and vomiting. The blood pressure was 120/80\ua0mmHg. The rest of the examination was normal. A thick film from peripheral blood was performed and addressed to the parasitology laboratory of the hospital. Thick film was stained with 10% Giemsa. Trophozoite of P. falciparum was identified at parasite density of 47 parasites per microlitre. The presence of Borrelia was also observed, concluding to malaria co-infection with borreliosis.
Conclusions
Signs of malaria can overlap with signs of borreliosis leading to the misdiagnosis of the latter. Thick and thin smear or QBC test or molecular method may be helpful to detect both Plamodium species and Borrelia . In addition, there is a real need to consider co-infections with other endemics pathogens when diagnosing malaria
Non-local corrections to dynamical mean-field theory from the two-particle self-consistent method
Theoretical methods that are accurate for both short-distance observables and
long-wavelength collective modes are still being developed for the Hubbard
model. Here, we benchmark against published diagrammatic quantum Monte Carlo
results an approach that combines local observables from dynamical mean-field
theory (DMFT) with the two-particle self-consistent theory (TPSC). This method
(TPSC+DMFT) is relevant for weak to intermediate interaction, satisfies the
local Pauli principle and allows us to compute a spin susceptibility that
satisfies the Mermin-Wagner theorem. The DMFT double occupancy determines the
spin and charge vertices through local spin and charge sum rules. The TPSC
self-energy is also improved by replacing its local part with the local DMFT
self-energy. With this method, we find improvements for both spin and charge
fluctuations and for the self-energy. We also find that the accuracy check
developed for TPSC is a good predictor of deviations from benchmarks. TPSC+DMFT
can be used in regimes where quantum Monte Carlo is inaccessible. In addition,
this method paves the way to multi-band generalizations of TPSC that could be
used in advanced electronic structure codes that include DMFT.Comment: 15 pages, 19 figures. Changes from v1: added reference
Insights into pneumococcal pneumonia using lung aspirates and nasopharyngeal swabs collected from pneumonia patients in The Gambia.
We investigated the pathogenesis of pneumococcal pneumonia using clinical specimens collected for pneumonia surveillance in The Gambia. Lung aspirates and nasopharyngeal swabs from 31 patients were examined by culture, qPCR, whole genome sequencing, serotyping, and reverse transcription qPCR. Five lung aspirates cultured pneumococci, with a matching strain identified in the nasopharynx. Three virulence genes including ply (pneumolysin) were upregulated >20-fold in the lung compared with the nasopharynx. Nasopharyngeal pneumococcal density was higher in pediatric pneumonia patients compared with controls (p <0.0001). Findings suggest that changes in pneumococcal gene expression occurring in the lung environment may be important in pathogenesis
Osteolipoma: An unusual tumor of the parotid region
SummaryPurpose of studyOncology of the parotid region is rich and varied, like its components. During his career, the ENT surgeon may come across such an exceptional tumor as osteolipoma. The aim of this study was to describe the rarity and the etiopathogeny of osteolipoma with parapharyngeal location.Patients and methodWe had the opportunity to find this uncommon tumor in a 21-year-old female patient. The mass located in the parotid region was hard, barely mobile and at first looked like a parotid tumor. Total parotidectomy with facial nerve preservation was performed. It revealed a stony and dented tumor inside the internal lobe of the parotid located in the parapharyngeal space between the vertical portion of the mandible anteriorly and the styloid apophyse posteriorly. Macroscopic examination of the piece evidenced a lipomatous mass with hard as bone nodes in its middle. Histology revealed an osteolipoma.ConclusionA review of the literature shows the uncommon occurrence of this type of tumor. A few rare cases were reported among which two involving the parapharyngeal space
High resolution melting: a useful field-deployable method to measure dhfr and dhps drug resistance in both highly and lowly endemic Plasmodium populations
Background: Emergence and spread of drug resistance to every anti-malarial used to date, creates an urgent need for development of sensitive, specifc and feld-deployable molecular tools for detection and surveillance of validated drug resistance markers. Such tools would allow early detection of mutations in resistance loci. The aim of this study was to compare common population signatures and drug resistance marker frequencies between two populations with diferent levels of malaria endemicity and history of anti-malarial drug use: Tanzania and Sénégal. This was accomplished by implementing a high resolution melting assay to study molecular markers of drug resistance as compared to polymerase chain reaction–restriction fragment length polymorphism (PCR/RFLP) methodology.
Methods: Fifty blood samples were collected each from a lowly malaria endemic site (Sénégal), and a highly malaria endemic site (Tanzania) from patients presenting with uncomplicated Plasmodium falciparum malaria at clinic. Data representing the DHFR were derived using both PCR–RFLP and HRM assay; while genotyping data representing the DHPS were evaluated in Senegal and Tanzania using HRM. Msp genotyping analysis was used to characterize the multiplicity of infection in both countries.
Results: A high prevalence of samples harbouring mutant DHFR alleles was observed in both population using both genotyping techniques. HRM was better able to detect mixed alleles compared to PCR/RFLP for DHFR codon 51 in Tanzania; and only HRM was able to detect mixed infections from Senegal. A high prevalence of mutant alleles in DHFR (codons 51, 59, 108) and DHPS (codon 437) were found among samples from Sénégal while no mutations were observed at DHPS codons 540 and 581, from both countries. Overall, the frequency of samples harbouring either a single DHFR mutation (S108N) or double mutation in DHFR (C59R/S108N) was greater in Sénégal compared to Tanzania
Conclusion: Here the results demonstrate that HRM is a rapid, sensitive, and feld-deployable alternative technique to PCR–RFLP genotyping that is useful in populations harbouring more than one parasite genome (polygenomic infections). In this study, a high levels of resistance polymorphisms was observed in both dhfr and dhps, among samples from Tanzania and Sénégal. A routine monitoring by molecular markers can be a way to detect emergence of resistance involving a change in the treatment policy
Anévrismes de l’aorte abdominale sous-rénale rompus: aspects chirurgicaux à Dakar: à propos de 6 observations
La rupture des anévrismes de l'aorte est une situation catastrophique. La chirurgie ouverte et le traitement endovasculaire sont débattus comme option. Dans cette étude sont évaluées les modalités du traitement chirurgical et ses résultats sur 6 malades opérés pour rupture d'un anévrysme de l'aorte abdominale sous-rénale. Dans 4 cas, il s'agissait d'une « rupture contenue » dans le péritoine pariétal postérieur, avec un hématome péri vertébral. Dans les 2 autres cas, il s'agissait d'une rupture en péritoine libre. Tous les malades avaient bénéficié après contrôle de l'hémostase d'une mise à plat de l'anévrisme suivie de greffe d'une prothèse aortique. Des complications précoces étaient notées chez 2 patients à type d'insuffisance rénale aigue et de poussée hypertensive. La mortalité opératoire était de 16,66%. La morbi-motalité des anévrismes rompus de l'aorte abdominale est particulièrement élevée, d'où la nécessité d'un dépistage précoce des patients à risque et l'introduction de la chirurgie endovasculaire
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