Depleting gene activities in early Drosophila embryos with the "maternal-Gal4-shRNA" system.

In a developing Drosophila melanogaster embryo, mRNAs have a maternal origin, a zygotic origin, or both. During the maternal-zygotic transition, maternal products are degraded and gene expression comes under the control of the zygotic genome. To interrogate the function of mRNAs that are both maternally and zygotically expressed, it is common to examine the embryonic phenotypes derived from female germline mosaics. Recently, the development of RNAi vectors based on short hairpin RNAs (shRNAs) effective during oogenesis has provided an alternative to producing germline clones. Here, we evaluate the efficacies of: (1) maternally loaded shRNAs to knockdown zygotic transcripts and (2) maternally loaded Gal4 protein to drive zygotic shRNA expression. We show that, while Gal4-driven shRNAs in the female germline very effectively generate phenotypes for genes expressed maternally, maternally loaded shRNAs are not very effective at generating phenotypes for early zygotic genes. However, maternally loaded Gal4 protein is very efficient at generating phenotypes for zygotic genes expressed during mid-embryogenesis. We apply this powerful and simple method to unravel the embryonic functions of a number of pleiotropic genes.

[Evolution of antibiotic-resistance Staphylococcus aureus in Saint Camille Medical Centre in Ouagadougou]. / Evolution de la résistance de Staphylococcus aureus aux antibiotiques au Centre Médical Saint Camille de Ouagadougou.

BACKGROUND: Monitoring the antibiotic resistance of microorganisms in a specific geographic area can be useful in developing new approaches to first-intention antibiotherapy. OBJECTIVE: The purpose of this study was to describe the evolution of resistance of Staphylococcus aureus to antibiotics routinely used at Saint Camille Medical Centre in Ouagadougou, Burkina Faso from 1996 to 2006. METHOD: Strains of S. aureus, isolated from various pathologic sources were tested to determine their susceptibility to antibiotics. Sensitivity tests were performed in accordance with the guidelines of the Antibiogram Committee of the French Society for Microbiology (version 2007). RESULTS: During the study period, 1160 staphylococci strains were isolated including 73.45% identified as S. aureus. Susceptibility tests demonstrated a significant increase in resistance to beta-lactam antibiotics. The proportion of strains showing resistance to ampicillin reached 58.29% in 2000. Resistance to these antibiotics regressed significantly from 2000 to 2006. Resistance to pristinamycin and erythromycin showed a tendency to increase while resistance to gentamicin and oleandomycin showed no statistically significant change. CONCLUSION: This study demonstrated that S. aureus was the most common Staphylococcus genus present at the center and that it was resistant to several antibiotics. Reducing use of beta-lactam probably accounted for the significant decline in resistance to this type of antibiotic. Care should also be given to the use of other antibiotics such as pristinamycin and erythromycin since resistance appears to be increasing.

Aetiology of acute gastro-enteritis in children at Saint Camille Medical Centre, Ouagadougou, Burkina Faso.

UNLABELLED: The present study aims at identifying the infectious agents responsible for child Acute GastroEnteritis (AGE) in Ouagadougou. From May 5 2006 to June 22 2008, 648 children aged from 2 to 41 months, with at least an average of 3 loose stools per day have been enrolled for coproculture, parasitology and virology test. Among them, 34 (5.25%) were HIV seropositive. A single sample of faeces from each child was used to identify enteropathogens. An infectious aetiology was identified in 41.20% of cases. The pathogenic agents detected as responsible for the AGE are: Rotavirus 21.1%; Adenovirus 1.9%; Giardia 7.6% Entamoeba; 1.08%; entero-pathogenic E. coli 41.7%; Salmonella 3.40%; Shigella 1.85% and Yersinia 1.70%. CONCLUSION: Therefore, these AGE etiologic agents constitute a problem of public health in Burkina Faso. Their control for the child would require: (1) a regular paediatric and clinical follow up; (2) health education of the population for food hygiene and (3) in case of absence of HIV infection in the mother, a promotion of exclusive breast-feeding up to the age of 4 months.

[Osteogenesis imperfecta diagnoses early, apropos of a case at the Yalgadou Ouédraogo National Hospital Center of Ouagadougou]. / Ostéogenèse imparfaite (O.I.) à révélation précoce (a propos d'un cas au Centre Hospitalier National Yalgadou Ouédraogo de Ouagadougou).

Osteogenesis imperfecta which represents a family tragedy for parents, a curiosity for physicians and radiologists, constitutes a real constitutional osteoporosis, usually rare with dominant autosomic transmission. Authors report a case of a 37 week amenorrhea living foetus, presenting an osteogenesis imperfecta. This affection, with early in utero manifestations, has a bad prognosis (baby deceased 72 hours after birth). Diagnosis was suspected at echography and conformed by x-rays investigations. The new born got also clinical and pathological examinations. Authors emphasize the unusualness and the gravity of these early clinical features. They insist on doing echography and radiography for the location of osseous and visceral lesions before and afterbirth.

[Malignant keratoma]. / Kératome malin.

INTRODUCTION: Birth of an Harlequin fetus in an African maternity ward is an exceptional event. There is no question as to the diagnosis, but no treatment is available. CASE REPORT: A female infant was delivered with typical lesions of malignant keratoma. Death occurred 20 hours after birth. DISCUSSION: In countries with adequate intensive care facilities (hydration, acitretine), such infants may occasionally survive with the risk of developing major lamellar ichthyosis which remains a handicap for the rest of life. In Burkina-Faso, such therapeutic facilities are lacking as are means of antenatal diagnosis. The ethical question as to whether or not to attempt survival measures is quite different under these conditions.

Peroxidase content of soybean root nodules.

A peroxidase has been isolated from soybean nodules and its main characteristics have been determined. Its molecular weight (48 000) and spectral properties are similar to those of usual plant peroxidases. Its activity is comparable to that of low-efficiency plant peroxidases. The rate constant of the reaction with H2O2 is 3 x 10(5) M-1 x s-1. In this reaction, nodule peroxidase yields an oxidized intermediate analogous to the compound I species of peroxidases already studied. A comparison is made with the pseudoperoxidatic activity of soybean leghemoglobin components. Leghemoglobins a and c react with H2O2 with rate constants of 5 x 10(3) and 2.5 x 10(3) M-1 x s-1, respectively, yielding the leghemoglobin (IV) species. During these reactions leghemoglobins are inactivated.

Kinetic studies of the reaction of ferric soybean leghemoglobins with hydrogen peroxide, cyanide and nicotinic acid.

A kinetic study of the reaction of two soybean leghemoglobins (components a and c) with hydrogen peroxide to form the oxidized compound (leghemoglobin IV) has been carried out over the pH range 2.5--10. Three different ionization processes of leghemoglobins with pKa values of 3,4.7 +/- 0.2 and 8.2 +/- 0.1 are required to explain the rate/pH profiles. Protonation of the former group and ionization of the latter cause a decrease in the rate of reaction of the hemoproteins with H2O2. The results are compared to those obtained for the reactions of plant peroxidases and myoglobin with H2O2. The results obtained from the kinetic study of cyanide binding to soybean leghemoglobins indicate that CN- is the reactive species. Two ionization processes of leghemoglobins with pKa values of 4.7 +/- 0.2 and 8.2 +/- 0.1 affect the reaction rates. The association and dissociation rate constants corresponding to nicotinic acid binding to leghemoglobins a and c have been measured over the pH range 2.5--7. The dissociation rate constant is affected by ionization of a group with pKa less than 2.5 for both leghemoglobin-nicotinate complexes. In this pH range the association rate constant is only affected by ionization of a group with pKa value of 4.7 +/- 0.2. The analysis of these results shows that both ionization processes corresponding to ring nitrogen atom of the ligand (pKa approximately equal to 4.9) and to a heme-linked group (pKa approximately equal to 4.7 +/- 0.2) influence the association rate constant. Furthermore, it appears that in the binding site of leghemoglobins the pKa value corresponding to ionization of the ring nitrogen atom of nicotinic acid is shifted from the normal value of 4.9 to a value of less than 2.5. This pecularity might explain the exceptional reactivity of leghemoglobins for nicotinic acid, over a large pH range. For both cyanide and nicotinic acid binding reactions, the ionizable group of leghemoglobins with pKa value of 4.7 +/- 0.2 seems to act as an electrostatic gate. When the group is deprotonated, it restricts the access of anion ligands to the heme pocket. For all the three reactions studied, leghemoglobin a reacts about twice as fast as leghemoglobin c.