Transferrin overexpression alters testicular function in aged mice

Many studies have shown a correlation between transferrin (Tf) concentration and sperm yield in several mammalian species. We have used transgenic mice expressing human Tf (hTf) to investigate if overexpression of Tf increases the efficiency of mouse spermatogenesis. We demonstrated that a 36% increase of Tf does not ameliorate the efficiency of mouse spermatogenesis but on the contrary resulted in a 36% decrease of testis sperm reserves. Tf overexpression had no effect on testicular determination and development, however testicular function of these transgenic mice was affected in an age-dependent manner. At 16 months of age, testicular and epididymal weights were significantly reduced. While spermatogenesis was qualitatively normal, testicular functions were perturbed. In fact, testosterone rate after human chorionic gonadotropin (hCG) stimulation was lower in Tf overexpressing mice. Intratesticular concentration of estradiol-17beta was increased and fluid accumulation after ligation of rete testis was more abundant in these transgenic mice. Surprisingly, we found that endogenous Tf levels were also increased in Tf overexpressing mice and we demonstrated for the first time that Tf may serve to upregulate its own expression in testis. Collectively, our data show that Tf overexpression has negative effects on testicular function and that Tf levels require strict regulation in the testis.     

Amputation du gland lors de la circoncision: A propos de 19 cas

Purpose

To assess the clinical features and describe treatment difficulties associated with glandular amputation during circumcision in our daily urological practice in Senegal and to warn about the risks of this procedure, which remain underestimated in this country.

Patients and Methods

The authors report a retrospective series of 19 patients who suffered glandular amputation during circumcision and who were admitted to their urology unit. The medical charts of patients hospitalised during this period were studied.

Results

The mean age of these patients was 7.6 years. 84.2% of patients presented with complete glandular amputation. The mean time to consultation was 17.6 months generally in a context of urinary tract complications. Surgical treatment consisted of meatoplasty in 68.4% of cases. Four cases were treated by glandular reimplantation which unfortunately failed.

Conclusion

The severity of this complication and the difficulties of management in our regions must encourage prevention.     

Ecological genetic studies in the chromosomal form Mopti ofAnopheles gambiae s.str. in Mali,West Africa

Among the sibling species of the AfrotropicalAnopheles gambiae complex, the nominal taxon (An. gambiae s.str.) is the major malaria vector. Its bionomics suggest a man-dependent speciation process which involves, in West Africa, various incipient species chromosomally recognized by different combinations of 2R paracentric inversions. One of the most recent evolutionary steps of such a speciation process appears to be the chromosomal form Mopti, which is associated with dry season irrigation in arid zones, and is characterized by a remarkable ecological flexibility related to three 2R alternative arrangements, namelybc, u and +, whose expected karyotypes are found in Hardy-Weinberg equilibrium. The study of this chromosomal polymorphism in samples from a 16-locality transect in Mali shows wide variations and highly significant correlation with both temporal and spatial climatic differences. Mosquitoes homokaryotypic for 2Rbc are the actual dry season and arid areas breeders. The regular rise of 2Rbc frequency, up to fixation, during each dry season, corresponds to the South-North clinal increase of the same arrangement along the transect, from about 30% in the humid savanna to near fixation in the South-Saharan zone. This coherent ecological genetics case provides full support to the hypothesis of the adaptive nature of paracentric inversions. Moreover, the very peculiar system of combinations of contiguous 2R inversions, utilized by Mopti as well as by other chromosomal forms ofAn. gambiae, suggests a process of polygenic reorganization based on linkage disequilibria and involving the inversions as driving selection units.     

Integrative taxonomy of a poorly known Sahelian rodent, Gerbillus nancillus (Muridae,Gerbillinae)

Aridification processes that affected the Sahelian area of West Africa during the last decades have induced significant changes in plant and animal communities of this region. In rodents, the genus Gerbillus characteristic of North African and Asian arid habitats has been affected by this climatic and environmental trends. Several species of this genus showed a southward range expansion in recent years into the Sahelian bioclimatic zone. Recent sampling in several localities of West Africa (Mali, Niger and Senegal) enabled us to collect numerous specimens of small gerbils. An integrative study of these samples using molecular, morphological and cytogenetical methods revealed that many of them were attributable to Gerbillus nancillus, a secretive and poorly known species. Gerbillus nancillus appears characterized by a well differentiated karyotype with 2n = 56 chromosomes, and to represent a unique genetic lineage within this genus. Body and skull measurements of G. nancillus were compared with those of the morphologically similar Gerbillus henleyi, which provided diagnostic clues between them. These new data significantly expand the distribution area of G. nancillus, which now ranges from Sudan in the East to Senegal in the West. G. nancillus is here reported from numerous new localities in Niger and Mali, and for the first time in Senegal, which raises questions about the origin of its presence and the colonization routes it followed to get there. We also show that G. henleyi and G. nancillus are sympatric and apparently often syntopic in the sub-Saharan part of the distribution of G. henleyi.     

Impact de la varicocélectomie chez les patients ayant une azoospermie non obstructive ou une oligozoospermie sévère

Objective

To evaluate the changes induced by retroperitoneal varicocelectomy on infertile men with nonobstructive azoospermia or severe oligozoospermia.

Patients and methods

The records were retrospectively evaluated for 46 infertile men with severe oligozoospermia (group I) and 15 infertile men with non-obstructive azoospermia (group II). The parameters of sperm before and after surgery and unassisted pregnancy rate were comparatively analysed.

Results

In the severe oligozoospermia group, the mean age of patients was 35.5 ± 6.4 (23–47 years). The mean duration of infertility was 4.9 ± 3.4 years (1–13 years). Of these patients, 41(89.1%) had bilateral varicocele and five (10.9%) had unilateral left-side varicocele. The varicocele was classified as grade I in two cases (4.3%), grade II in 39 cases (84.7%) and grade III in five cases (10.9%). After surgery, the mean sperm count increased from 1.85 ± 1.4 to 8.3 ± 10.3 millions/ml and mean sperm normal motility from 43.3 ± 21.5 to 47.6 ± 29.2%. The mean sperm abnormal morphology decreased from 65.05 ± 21.6 to 50.08 ± 26.9%. After a mean follow-up of 26.2 ± 11.6 months, the unassisted pregnancy rate in this group was 26.1%. In the non-obstructive azoospermia group (N = 15), the mean age of patients was 40.8 ± 7.2 (27–47 years). The mean duration of infertility was 6 ± 3.1 years (3–15 years). After varicocelectomy, an induction of spermatogenesis was observed in three patients (20%) with presence of motile sperm in the ejaculate. In this group, only one of the 15 men achieved unassisted pregnancy.

Conclusion

Retroperitoneal varicocele repair resulted in spermatogenesis induction with presence of motile ejaculated spermatozoa for some men with non-obstructive azoospermia. It induced spermatogenesis and fertility enhancement in men with severe oligozoospermia. Varicocele repair should be considered in men with non-obstructive azoospermia or severe oligozoospermia.     

Molecular Characterization of Invasive Meningococcal Isolates from Countries in the African Meningitis Belt before Introduction of a Serogroup A Conjugate Vaccine

Background

The serogroup A conjugate meningococcal vaccine, MenAfriVac, was introduced in mass vaccination campaigns in December 2010 in Burkina Faso, Mali and Niger. In the coming years, vaccination will be extended to other African countries at risk of epidemics. To document the molecular characteristics of disease-causing meningococcal strains circulating in the meningitis belt of Africa before vaccine introduction, the World Health Organization Collaborating Centers on Meningococci in Europe and United States established a common strain collection of 773 isolates from cases of invasive meningococcal disease collected between 2004 and 2010 from 13 sub-Saharan countries.

Methodology

All isolates were characterized by multilocus sequence typing, and 487 (62%) were also analyzed for genetic variation in the surface antigens PorA and FetA. Antibiotic susceptibility was tested for part of the collection.

Principal Findings

Only 19 sequence types (STs) belonging to 6 clonal complexes were revealed. ST-5 clonal complex dominated with 578 (74.8%) isolates. All ST-5 complex isolates were remarkably homogeneous in their PorA (P1.20,9) and FetA (F3-1) and characterized the serogroup A strains which have been responsible for most epidemics during this time period. Sixty-eight (8.8%) of the 773 isolates belonged to the ST-11 clonal complex which was mainly represented by serogroup W135, while an additional 38 (4.9%) W135 isolates belonged to the ST-175 complex. Forty-eight (6.2%) serogroup X isolates from West Africa belonged to the ST-181 complex, while serogroup X cases in Kenya and Uganda were caused by an unrelated clone, ST-5403. Serogroup X, ST-181, emerged in Burkina Faso before vaccine introduction.

Conclusions

In the seven years preceding introduction of a new serogroup A conjugate vaccine, serogroup A of the ST-5 clonal complex was identified as the predominant disease-causing strain.     

Narrow-sense heritability and <Emphasis Type="Italic">P</Emphasis><Subscript>ST</Subscript> estimates of DNA methylation in three <Emphasis Type="Italic">Populus nigra</Emphasis> L. populations under contrasting water availability

In a context of climate change and forest decline, a better understanding of the sources of tree flexibility involved in phenotypic plasticity and adaptation is needed. These last years, the role of epigenetics in the response to environmental variations has been established in several model plants at the genotype level but little is known at the level of natural populations grown in pedoclimatic sites. Here, we focused on three French natural populations of black poplar, a key pioneer tree from watersheds, planted in common garden and subjected to controlled variations of water availability. We estimated common genetic parameters such as narrow-sense heritability (h²), phenotypic differentiation index (P_ST), and the overall genetic differentiation index (F_ST) from genome-wide SNPs to evaluate the extent of epigenetic variations. Indeed, global DNA methylation levels from individuals exposed to drought or irrigated in a common garden were used. We found that the three populations were not distinguished by their levels of DNA methylation. However, a moderate drought was associated to a significant decrease in DNA methylation in the populations. Narrow-sense heritability and P_ST estimates of DNA methylation were similar to those found for biomass productivity. Heritability and P_ST were higher when trees were subjected to drought than in control condition. Negative genetic correlations between global DNA methylation and height or biomass were detected in drought condition only. Altogether, our data highlight that global DNA methylation acts as a genetic marker of natural population differentiation under drought stress in a pedoclimatic context.